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From: Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Sergey Kaplun <skaplun@tarantool.org>,
	Maxim Kokryashkin <m.kokryashkin@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH luajit 3/5] Improve assertions.
Date: Fri, 18 Aug 2023 14:20:21 +0300	[thread overview]
Message-ID: <4df29b39-85e5-3c92-83cd-c0ac97865744@tarantool.org> (raw)
In-Reply-To: <d9facf54b4ffd5d93b34be46c81d29c7cee33f43.1692089299.git.skaplun@tarantool.org>

Hi, Sergey

thanks for the patch! LGTM

On 8/15/23 12:36, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> (cherry-picked from commit 8ae5170cdc9c307bd81019b3e014391c9fd00581)
>
> This commit refactors assertions used in the LuaJIT. It introduces new
> module <src/lj_assert.c> with the `lj_assert_fail()` implementation.
> Wrappers of this function are used across the whole code base. Each
> macro wrapper is defined in the corresponding module gets global state
> (if possible) from its environment to be passed inside the assertion.
> For now, the global state is unused, but later it may be used for
> dumping of the VM state.
>
> Sergey Kaplun:
> * added the description for the feature
>
> Part of tarantool/tarantool#8825
> ---
>   src/CMakeLists.txt        |   1 +
>   src/Makefile.dep.original |  13 +--
>   src/Makefile.original     |   4 +-
>   src/lib_io.c              |   6 +-
>   src/lib_jit.c             |   4 +-
>   src/lib_misc.c            |  12 +--
>   src/lib_string.c          |   6 +-
>   src/lj_api.c              | 140 +++++++++++++++++---------------
>   src/lj_asm.c              | 130 ++++++++++++++++++------------
>   src/lj_asm_arm.h          | 119 ++++++++++++++++------------
>   src/lj_asm_arm64.h        |  95 ++++++++++++----------
>   src/lj_asm_mips.h         | 151 ++++++++++++++++++++---------------
>   src/lj_asm_ppc.h          | 113 +++++++++++++++-----------
>   src/lj_asm_x86.h          | 161 +++++++++++++++++++++----------------
>   src/lj_assert.c           |  28 +++++++
>   src/lj_bcread.c           |  20 ++---
>   src/lj_bcwrite.c          |  24 ++++--
>   src/lj_buf.c              |   4 +-
>   src/lj_carith.c           |  10 ++-
>   src/lj_ccall.c            |  19 +++--
>   src/lj_ccallback.c        |  42 +++++-----
>   src/lj_cconv.c            |  57 ++++++++------
>   src/lj_cconv.h            |   5 +-
>   src/lj_cdata.c            |  27 ++++---
>   src/lj_cdata.h            |   7 +-
>   src/lj_clib.c             |   6 +-
>   src/lj_cparse.c           |  25 +++---
>   src/lj_crecord.c          |  19 +++--
>   src/lj_ctype.c            |  13 +--
>   src/lj_ctype.h            |  14 +++-
>   src/lj_debug.c            |  18 +++--
>   src/lj_def.h              |  26 ++++--
>   src/lj_dispatch.c         |  11 ++-
>   src/lj_emit_arm.h         |  50 ++++++------
>   src/lj_emit_arm64.h       |  21 ++---
>   src/lj_emit_mips.h        |  22 +++---
>   src/lj_emit_ppc.h         |  12 +--
>   src/lj_emit_x86.h         |  22 +++---
>   src/lj_err.c              |  40 ++--------
>   src/lj_func.c             |  18 +++--
>   src/lj_gc.c               |  78 ++++++++++--------
>   src/lj_gc.h               |   6 +-
>   src/lj_gdbjit.c           |   5 +-
>   src/lj_ir.c               |  31 ++++----
>   src/lj_ir.h               |   5 +-
>   src/lj_jit.h              |   6 ++
>   src/lj_lex.c              |  14 ++--
>   src/lj_lex.h              |   6 ++
>   src/lj_load.c             |   2 +-
>   src/lj_mapi.c             |   2 +-
>   src/lj_mcode.c            |   2 +-
>   src/lj_memprof.c          |  35 ++++----
>   src/lj_meta.c             |   6 +-
>   src/lj_obj.h              |  35 +++++---
>   src/lj_opt_fold.c         |  88 ++++++++++++---------
>   src/lj_opt_loop.c         |   5 +-
>   src/lj_opt_mem.c          |  15 ++--
>   src/lj_opt_narrow.c       |  17 ++--
>   src/lj_opt_split.c        |  22 +++---
>   src/lj_parse.c            | 114 +++++++++++++++------------
>   src/lj_record.c           | 162 +++++++++++++++++++++++---------------
>   src/lj_snap.c             | 100 ++++++++++++++---------
>   src/lj_snap.h             |   3 +-
>   src/lj_state.c            |  18 +++--
>   src/lj_str.c              |   7 +-
>   src/lj_strfmt.c           |   4 +-
>   src/lj_strfmt.h           |   3 +-
>   src/lj_strfmt_num.c       |   6 +-
>   src/lj_strscan.c          |   9 ++-
>   src/lj_symtab.c           |  11 +--
>   src/lj_sysprof.c          |  31 ++++----
>   src/lj_tab.c              |  20 ++---
>   src/lj_target.h           |   3 +-
>   src/lj_trace.c            |  57 +++++++-------
>   src/lj_utils_leb128.c     |   5 +-
>   src/lj_vmmath.c           |   7 +-
>   src/lj_wbuf.c             |   3 +-
>   src/ljamalg.c             |   1 +
>   src/luaconf.h             |   2 +-
>   79 files changed, 1436 insertions(+), 1025 deletions(-)
>   create mode 100644 src/lj_assert.c
>
> diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
> index feeccbde..03338306 100644
> --- a/src/CMakeLists.txt
> +++ b/src/CMakeLists.txt
> @@ -59,6 +59,7 @@ make_source_list(SOURCES_FRONTEND
>   make_source_list(SOURCES_UTILS
>     SOURCES
>       lj_alloc.c
> +    lj_assert.c
>       lj_char.c
>       lj_utils_leb128.c
>       lj_vmmath.c
> diff --git a/src/Makefile.dep.original b/src/Makefile.dep.original
> index 968805ed..d35b6d9a 100644
> --- a/src/Makefile.dep.original
> +++ b/src/Makefile.dep.original
> @@ -54,6 +54,7 @@ lj_asm.o: lj_asm.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h lj_gc.h \
>    lj_ircall.h lj_iropt.h lj_mcode.h lj_trace.h lj_dispatch.h lj_traceerr.h \
>    lj_snap.h lj_asm.h lj_vm.h lj_target.h lj_target_*.h lj_emit_*.h \
>    lj_asm_*.h
> +lj_assert.o: lj_assert.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h
>   lj_bc.o: lj_bc.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h lj_bc.h \
>    lj_bcdef.h
>   lj_bcread.o: lj_bcread.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
> @@ -164,7 +165,7 @@ lj_opt_loop.o: lj_opt_loop.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
>    lj_iropt.h lj_trace.h lj_dispatch.h lj_bc.h lj_traceerr.h lj_snap.h \
>    lj_vm.h
>   lj_opt_mem.o: lj_opt_mem.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
> - lj_tab.h lj_ir.h lj_jit.h lj_iropt.h lj_ircall.h
> + lj_tab.h lj_ir.h lj_jit.h lj_iropt.h lj_ircall.h lj_dispatch.h lj_bc.h
>   lj_opt_narrow.o: lj_opt_narrow.c lj_obj.h lua.h luaconf.h lj_def.h \
>    lj_arch.h lj_bc.h lj_ir.h lj_jit.h lj_iropt.h lj_trace.h lj_dispatch.h \
>    lj_traceerr.h lj_vm.h lj_strscan.h
> @@ -224,15 +225,17 @@ lj_trace.o: lj_trace.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
>    lmisclib.h lj_sysprof.h
>   lj_udata.o: lj_udata.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
>    lj_gc.h lj_udata.h
> -lj_utils_leb128.o: lj_utils_leb128.c lj_utils.h lj_def.h lua.h luaconf.h
> +lj_utils_leb128.o: lj_utils_leb128.c lj_utils.h lj_def.h lua.h luaconf.h \
> + lj_obj.h lj_arch.h
>   lj_vmevent.o: lj_vmevent.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
>    lj_str.h lj_tab.h lj_state.h lj_dispatch.h lj_bc.h lj_jit.h lj_ir.h \
>    lj_vm.h lj_vmevent.h
>   lj_vmmath.o: lj_vmmath.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
>    lj_ir.h lj_vm.h
> -lj_wbuf.o: lj_wbuf.c lj_wbuf.h lj_def.h lua.h luaconf.h lj_utils.h
> -ljamalg.o: ljamalg.c lua.h luaconf.h lauxlib.h lj_gc.c lj_obj.h lj_def.h \
> - lj_arch.h lj_gc.h lj_err.h lj_errmsg.h lj_buf.h lj_str.h lj_tab.h \
> +lj_wbuf.o: lj_wbuf.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
> + lj_wbuf.h lj_utils.h
> +ljamalg.o: ljamalg.c lua.h luaconf.h lauxlib.h lj_assert.c lj_obj.h lj_def.h \
> + lj_arch.h lj_gc.c lj_gc.h lj_err.h lj_errmsg.h lj_buf.h lj_str.h lj_tab.h \
>    lj_func.h lj_udata.h lj_meta.h lj_state.h lj_frame.h lj_bc.h lj_ctype.h \
>    lj_cdata.h lj_trace.h lj_jit.h lj_ir.h lj_dispatch.h lj_traceerr.h \
>    lj_vm.h lj_err.c lj_debug.h lj_ff.h lj_ffdef.h lj_strfmt.h lj_char.c \
> diff --git a/src/Makefile.original b/src/Makefile.original
> index 22d36a27..8cfe55c2 100644
> --- a/src/Makefile.original
> +++ b/src/Makefile.original
> @@ -499,8 +499,8 @@ LJLIB_O= lib_base.o lib_math.o lib_bit.o lib_string.o lib_table.o \
>   	 lib_misc.o
>   LJLIB_C= $(LJLIB_O:.o=.c)
>   
> -LJCORE_O= lj_gc.o lj_err.o lj_char.o lj_bc.o lj_obj.o lj_buf.o lj_wbuf.o \
> -	  lj_str.o lj_tab.o lj_func.o lj_udata.o lj_meta.o lj_debug.o \
> +LJCORE_O= lj_assert.o lj_gc.o lj_err.o lj_char.o lj_bc.o lj_obj.o lj_buf.o \
> +	  lj_wbuf.o lj_str.o lj_tab.o lj_func.o lj_udata.o lj_meta.o lj_debug.o \
>   	  lj_state.o lj_dispatch.o lj_vmevent.o lj_vmmath.o lj_strscan.o \
>   	  lj_strfmt.o lj_strfmt_num.o lj_api.o lj_mapi.o lj_profile.o \
>   	  lj_profile_timer.o lj_memprof.o lj_symtab.o lj_sysprof.o \
> diff --git a/src/lib_io.c b/src/lib_io.c
> index db995ae6..ef39e535 100644
> --- a/src/lib_io.c
> +++ b/src/lib_io.c
> @@ -101,9 +101,6 @@ static int io_file_close(lua_State *L, IOFileUD *iof)
>       stat = pclose(iof->fp);
>   #elif LJ_TARGET_WINDOWS && !LJ_TARGET_XBOXONE && !LJ_TARGET_UWP
>       stat = _pclose(iof->fp);
> -#else
> -    lua_assert(0);
> -    return 0;
>   #endif
>   #if LJ_52
>       iof->fp = NULL;
> @@ -112,7 +109,8 @@ static int io_file_close(lua_State *L, IOFileUD *iof)
>       ok = (stat != -1);
>   #endif
>     } else {
> -    lua_assert((iof->type & IOFILE_TYPE_MASK) == IOFILE_TYPE_STDF);
> +    lj_assertL((iof->type & IOFILE_TYPE_MASK) == IOFILE_TYPE_STDF,
> +	       "close of unknown FILE* type");
>       setnilV(L->top++);
>       lua_pushliteral(L, "cannot close standard file");
>       return 2;
> diff --git a/src/lib_jit.c b/src/lib_jit.c
> index 40aa2b51..b3c1c93c 100644
> --- a/src/lib_jit.c
> +++ b/src/lib_jit.c
> @@ -227,7 +227,7 @@ LJLIB_CF(jit_util_funcbc)
>     if (pc < pt->sizebc) {
>       BCIns ins = proto_bc(pt)[pc];
>       BCOp op = bc_op(ins);
> -    lua_assert(op < BC__MAX);
> +    lj_assertL(op < BC__MAX, "bad bytecode op %d", op);
>       setintV(L->top, ins);
>       setintV(L->top+1, lj_bc_mode[op]);
>       L->top += 2;
> @@ -491,7 +491,7 @@ static int jitopt_param(jit_State *J, const char *str)
>     int i;
>     for (i = 0; i < JIT_P__MAX; i++) {
>       size_t len = *(const uint8_t *)lst;
> -    lua_assert(len != 0);
> +    lj_assertJ(len != 0, "bad JIT_P_STRING");
>       if (strncmp(str, lst+1, len) == 0 && str[len] == '=') {
>         int32_t n = 0;
>         const char *p = &str[len+1];
> diff --git a/src/lib_misc.c b/src/lib_misc.c
> index 1913a622..ca1d1c75 100644
> --- a/src/lib_misc.c
> +++ b/src/lib_misc.c
> @@ -109,7 +109,7 @@ static size_t buffer_writer_default(const void **buf_addr, size_t len,
>     const void *data = *buf_addr;
>     size_t write_total = 0;
>   
> -  lua_assert(len <= STREAM_BUFFER_SIZE);
> +  lj_assertX(len <= STREAM_BUFFER_SIZE, "stream buffer overflow");
>   
>     for (;;) {
>       const ssize_t written = write(fd, data, len - write_total);
> @@ -127,7 +127,7 @@ static size_t buffer_writer_default(const void **buf_addr, size_t len,
>       }
>   
>       write_total += written;
> -    lua_assert(write_total <= len);
> +    lj_assertX(write_total <= len, "invalid stream buffer write");
>   
>       if (write_total == len)
>         break;
> @@ -168,7 +168,7 @@ static int on_stop_cb_default(void *opt, uint8_t *buf)
>   static int set_output_path(const char *path, struct luam_Sysprof_Options *opt) {
>     struct profile_ctx *ctx = opt->ctx;
>     int fd = 0;
> -  lua_assert(path != NULL);
> +  lj_assertX(path != NULL, "no file to open by sysprof");
>     fd = open(path, O_CREAT | O_WRONLY | O_TRUNC, 0644);
>     if(fd == -1) {
>       return PROFILE_ERRIO;
> @@ -280,7 +280,7 @@ static int sysprof_error(lua_State *L, int status)
>         return luaL_fileresult(L, 0, NULL);
>   #endif
>       default:
> -      lua_assert(0);
> +      lj_assertL(0, "bad sysprof error %d", status);
>         return 0;
>     }
>   }
> @@ -401,7 +401,7 @@ LJLIB_CF(misc_memprof_start)
>         return luaL_fileresult(L, 0, fname);
>   #endif
>       default:
> -      lua_assert(0);
> +      lj_assertL(0, "bad memprof error %d", memprof_status);
>         return 0;
>       }
>     }
> @@ -430,7 +430,7 @@ LJLIB_CF(misc_memprof_stop)
>         return luaL_fileresult(L, 0, NULL);
>   #endif
>       default:
> -      lua_assert(0);
> +      lj_assertL(0, "bad memprof error %d", status);
>         return 0;
>       }
>     }
> diff --git a/src/lib_string.c b/src/lib_string.c
> index 156dae66..9b9c369a 100644
> --- a/src/lib_string.c
> +++ b/src/lib_string.c
> @@ -136,7 +136,7 @@ LJLIB_CF(string_dump)
>   /* ------------------------------------------------------------------------ */
>   
>   /* macro to `unsign' a character */
> -#define uchar(c)        ((unsigned char)(c))
> +#define uchar(c)	((unsigned char)(c))
>   
>   #define CAP_UNFINISHED	(-1)
>   #define CAP_POSITION	(-2)
> @@ -645,7 +645,7 @@ static GCstr *string_fmt_tostring(lua_State *L, int arg, int retry)
>   {
>     TValue *o = L->base+arg-1;
>     cTValue *mo;
> -  lua_assert(o < L->top);  /* Caller already checks for existence. */
> +  lj_assertL(o < L->top, "bad usage");  /* Caller already checks for existence. */
>     if (LJ_LIKELY(tvisstr(o)))
>       return strV(o);
>     if (retry != 2 && !tvisnil(mo = lj_meta_lookup(L, o, MM_tostring))) {
> @@ -717,7 +717,7 @@ again:
>   	lj_strfmt_putptr(sb, lj_obj_ptr(G(L), L->base+arg-1));
>   	break;
>         default:
> -	lua_assert(0);
> +	lj_assertL(0, "bad string format type");
>   	break;
>         }
>       }
> diff --git a/src/lj_api.c b/src/lj_api.c
> index 89998815..05e02029 100644
> --- a/src/lj_api.c
> +++ b/src/lj_api.c
> @@ -28,8 +28,8 @@
>   
>   /* -- Common helper functions --------------------------------------------- */
>   
> -#define api_checknelems(L, n)		api_check(L, (n) <= (L->top - L->base))
> -#define api_checkvalidindex(L, i)	api_check(L, (i) != niltv(L))
> +#define lj_checkapi_slot(idx) \
> +  lj_checkapi((idx) <= (L->top - L->base), "stack slot %d out of range", (idx))
>   
>   static TValue *index2adr(lua_State *L, int idx)
>   {
> @@ -37,7 +37,8 @@ static TValue *index2adr(lua_State *L, int idx)
>       TValue *o = L->base + (idx - 1);
>       return o < L->top ? o : niltv(L);
>     } else if (idx > LUA_REGISTRYINDEX) {
> -    api_check(L, idx != 0 && -idx <= L->top - L->base);
> +    lj_checkapi(idx != 0 && -idx <= L->top - L->base,
> +		"bad stack slot %d", idx);
>       return L->top + idx;
>     } else if (idx == LUA_GLOBALSINDEX) {
>       TValue *o = &G(L)->tmptv;
> @@ -47,7 +48,8 @@ static TValue *index2adr(lua_State *L, int idx)
>       return registry(L);
>     } else {
>       GCfunc *fn = curr_func(L);
> -    api_check(L, fn->c.gct == ~LJ_TFUNC && !isluafunc(fn));
> +    lj_checkapi(fn->c.gct == ~LJ_TFUNC && !isluafunc(fn),
> +		"calling frame is not a C function");
>       if (idx == LUA_ENVIRONINDEX) {
>         TValue *o = &G(L)->tmptv;
>         settabV(L, o, tabref(fn->c.env));
> @@ -59,13 +61,27 @@ static TValue *index2adr(lua_State *L, int idx)
>     }
>   }
>   
> -static TValue *stkindex2adr(lua_State *L, int idx)
> +static LJ_AINLINE TValue *index2adr_check(lua_State *L, int idx)
> +{
> +  TValue *o = index2adr(L, idx);
> +  lj_checkapi(o != niltv(L), "invalid stack slot %d", idx);
> +  return o;
> +}
> +
> +static TValue *index2adr_stack(lua_State *L, int idx)
>   {
>     if (idx > 0) {
>       TValue *o = L->base + (idx - 1);
> +    if (o < L->top) {
> +      return o;
> +    } else {
> +      lj_checkapi(0, "invalid stack slot %d", idx);
> +      return niltv(L);
> +    }
>       return o < L->top ? o : niltv(L);
>     } else {
> -    api_check(L, idx != 0 && -idx <= L->top - L->base);
> +    lj_checkapi(idx != 0 && -idx <= L->top - L->base,
> +		"invalid stack slot %d", idx);
>       return L->top + idx;
>     }
>   }
> @@ -111,17 +127,17 @@ LUALIB_API void luaL_checkstack(lua_State *L, int size, const char *msg)
>       lj_err_callerv(L, LJ_ERR_STKOVM, msg);
>   }
>   
> -LUA_API void lua_xmove(lua_State *from, lua_State *to, int n)
> +LUA_API void lua_xmove(lua_State *L, lua_State *to, int n)
>   {
>     TValue *f, *t;
> -  if (from == to) return;
> -  api_checknelems(from, n);
> -  api_check(from, G(from) == G(to));
> +  if (L == to) return;
> +  lj_checkapi_slot(n);
> +  lj_checkapi(G(L) == G(to), "move across global states");
>     lj_state_checkstack(to, (MSize)n);
> -  f = from->top;
> +  f = L->top;
>     t = to->top = to->top + n;
>     while (--n >= 0) copyTV(to, --t, --f);
> -  from->top = f;
> +  L->top = f;
>   }
>   
>   LUA_API const lua_Number *lua_version(lua_State *L)
> @@ -141,7 +157,7 @@ LUA_API int lua_gettop(lua_State *L)
>   LUA_API void lua_settop(lua_State *L, int idx)
>   {
>     if (idx >= 0) {
> -    api_check(L, idx <= tvref(L->maxstack) - L->base);
> +    lj_checkapi(idx <= tvref(L->maxstack) - L->base, "bad stack slot %d", idx);
>       if (L->base + idx > L->top) {
>         if (L->base + idx >= tvref(L->maxstack))
>   	lj_state_growstack(L, (MSize)idx - (MSize)(L->top - L->base));
> @@ -150,23 +166,21 @@ LUA_API void lua_settop(lua_State *L, int idx)
>         L->top = L->base + idx;
>       }
>     } else {
> -    api_check(L, -(idx+1) <= (L->top - L->base));
> +    lj_checkapi(-(idx+1) <= (L->top - L->base), "bad stack slot %d", idx);
>       L->top += idx+1;  /* Shrinks top (idx < 0). */
>     }
>   }
>   
>   LUA_API void lua_remove(lua_State *L, int idx)
>   {
> -  TValue *p = stkindex2adr(L, idx);
> -  api_checkvalidindex(L, p);
> +  TValue *p = index2adr_stack(L, idx);
>     while (++p < L->top) copyTV(L, p-1, p);
>     L->top--;
>   }
>   
>   LUA_API void lua_insert(lua_State *L, int idx)
>   {
> -  TValue *q, *p = stkindex2adr(L, idx);
> -  api_checkvalidindex(L, p);
> +  TValue *q, *p = index2adr_stack(L, idx);
>     for (q = L->top; q > p; q--) copyTV(L, q, q-1);
>     copyTV(L, p, L->top);
>   }
> @@ -174,19 +188,18 @@ LUA_API void lua_insert(lua_State *L, int idx)
>   static void copy_slot(lua_State *L, TValue *f, int idx)
>   {
>     if (idx == LUA_GLOBALSINDEX) {
> -    api_check(L, tvistab(f));
> +    lj_checkapi(tvistab(f), "stack slot %d is not a table", idx);
>       /* NOBARRIER: A thread (i.e. L) is never black. */
>       setgcref(L->env, obj2gco(tabV(f)));
>     } else if (idx == LUA_ENVIRONINDEX) {
>       GCfunc *fn = curr_func(L);
>       if (fn->c.gct != ~LJ_TFUNC)
>         lj_err_msg(L, LJ_ERR_NOENV);
> -    api_check(L, tvistab(f));
> +    lj_checkapi(tvistab(f), "stack slot %d is not a table", idx);
>       setgcref(fn->c.env, obj2gco(tabV(f)));
>       lj_gc_barrier(L, fn, f);
>     } else {
> -    TValue *o = index2adr(L, idx);
> -    api_checkvalidindex(L, o);
> +    TValue *o = index2adr_check(L, idx);
>       copyTV(L, o, f);
>       if (idx < LUA_GLOBALSINDEX)  /* Need a barrier for upvalues. */
>         lj_gc_barrier(L, curr_func(L), f);
> @@ -195,7 +208,7 @@ static void copy_slot(lua_State *L, TValue *f, int idx)
>   
>   LUA_API void lua_replace(lua_State *L, int idx)
>   {
> -  api_checknelems(L, 1);
> +  lj_checkapi_slot(1);
>     copy_slot(L, L->top - 1, idx);
>     L->top--;
>   }
> @@ -231,7 +244,7 @@ LUA_API int lua_type(lua_State *L, int idx)
>   #else
>       int tt = (int)(((t < 8 ? 0x98042110u : 0x75a06u) >> 4*(t&7)) & 15u);
>   #endif
> -    lua_assert(tt != LUA_TNIL || tvisnil(o));
> +    lj_assertL(tt != LUA_TNIL || tvisnil(o), "bad tag conversion");
>       return tt;
>     }
>   }
> @@ -522,7 +535,7 @@ LUA_API const char *lua_tolstring(lua_State *L, int idx, size_t *len)
>   LUA_API uint32_t lua_hashstring(lua_State *L, int idx)
>   {
>     TValue *o = index2adr(L, idx);
> -  lua_assert(tvisstr(o));
> +  lj_checkapi(tvisstr(o), "stack slot %d is not a string", idx);
>     GCstr *s = strV(o);
>     if (! strsmart(s))
>       return s->hash;
> @@ -699,14 +712,14 @@ LUA_API void lua_pushcclosure(lua_State *L, lua_CFunction f, int n)
>   {
>     GCfunc *fn;
>     lj_gc_check(L);
> -  api_checknelems(L, n);
> +  lj_checkapi_slot(n);
>     fn = lj_func_newC(L, (MSize)n, getcurrenv(L));
>     fn->c.f = f;
>     L->top -= n;
>     while (n--)
>       copyTV(L, &fn->c.upvalue[n], L->top+n);
>     setfuncV(L, L->top, fn);
> -  lua_assert(iswhite(obj2gco(fn)));
> +  lj_assertL(iswhite(obj2gco(fn)), "new GC object is not white");
>     incr_top(L);
>   }
>   
> @@ -779,7 +792,7 @@ LUA_API void *lua_newuserdata(lua_State *L, size_t size)
>   
>   LUA_API void lua_concat(lua_State *L, int n)
>   {
> -  api_checknelems(L, n);
> +  lj_checkapi_slot(n);
>     if (n >= 2) {
>       n--;
>       do {
> @@ -805,9 +818,8 @@ LUA_API void lua_concat(lua_State *L, int n)
>   
>   LUA_API void lua_gettable(lua_State *L, int idx)
>   {
> -  cTValue *v, *t = index2adr(L, idx);
> -  api_checkvalidindex(L, t);
> -  v = lj_meta_tget(L, t, L->top-1);
> +  cTValue *t = index2adr_check(L, idx);
> +  cTValue *v = lj_meta_tget(L, t, L->top-1);
>     if (v == NULL) {
>       L->top += 2;
>       jit_secure_call(L, L->top-2, 1+1);
> @@ -819,9 +831,8 @@ LUA_API void lua_gettable(lua_State *L, int idx)
>   
>   LUA_API void lua_getfield(lua_State *L, int idx, const char *k)
>   {
> -  cTValue *v, *t = index2adr(L, idx);
> +  cTValue *v, *t = index2adr_check(L, idx);
>     TValue key;
> -  api_checkvalidindex(L, t);
>     setstrV(L, &key, lj_str_newz(L, k));
>     v = lj_meta_tget(L, t, &key);
>     if (v == NULL) {
> @@ -837,14 +848,14 @@ LUA_API void lua_getfield(lua_State *L, int idx, const char *k)
>   LUA_API void lua_rawget(lua_State *L, int idx)
>   {
>     cTValue *t = index2adr(L, idx);
> -  api_check(L, tvistab(t));
> +  lj_checkapi(tvistab(t), "stack slot %d is not a table", idx);
>     copyTV(L, L->top-1, lj_tab_get(L, tabV(t), L->top-1));
>   }
>   
>   LUA_API void lua_rawgeti(lua_State *L, int idx, int n)
>   {
>     cTValue *v, *t = index2adr(L, idx);
> -  api_check(L, tvistab(t));
> +  lj_checkapi(tvistab(t), "stack slot %d is not a table", idx);
>     v = lj_tab_getint(tabV(t), n);
>     if (v) {
>       copyTV(L, L->top, v);
> @@ -886,8 +897,7 @@ LUALIB_API int luaL_getmetafield(lua_State *L, int idx, const char *field)
>   
>   LUA_API void lua_getfenv(lua_State *L, int idx)
>   {
> -  cTValue *o = index2adr(L, idx);
> -  api_checkvalidindex(L, o);
> +  cTValue *o = index2adr_check(L, idx);
>     if (tvisfunc(o)) {
>       settabV(L, L->top, tabref(funcV(o)->c.env));
>     } else if (tvisudata(o)) {
> @@ -904,7 +914,7 @@ LUA_API int lua_next(lua_State *L, int idx)
>   {
>     cTValue *t = index2adr(L, idx);
>     int more;
> -  api_check(L, tvistab(t));
> +  lj_checkapi(tvistab(t), "stack slot %d is not a table", idx);
>     more = lj_tab_next(L, tabV(t), L->top-1);
>     if (more) {
>       incr_top(L);  /* Return new key and value slot. */
> @@ -930,7 +940,7 @@ LUA_API void *lua_upvalueid(lua_State *L, int idx, int n)
>   {
>     GCfunc *fn = funcV(index2adr(L, idx));
>     n--;
> -  api_check(L, (uint32_t)n < fn->l.nupvalues);
> +  lj_checkapi((uint32_t)n < fn->l.nupvalues, "bad upvalue %d", n);
>     return isluafunc(fn) ? (void *)gcref(fn->l.uvptr[n]) :
>   			 (void *)&fn->c.upvalue[n];
>   }
> @@ -940,8 +950,10 @@ LUA_API void lua_upvaluejoin(lua_State *L, int idx1, int n1, int idx2, int n2)
>     GCfunc *fn1 = funcV(index2adr(L, idx1));
>     GCfunc *fn2 = funcV(index2adr(L, idx2));
>     n1--; n2--;
> -  api_check(L, isluafunc(fn1) && (uint32_t)n1 < fn1->l.nupvalues);
> -  api_check(L, isluafunc(fn2) && (uint32_t)n2 < fn2->l.nupvalues);
> +  lj_checkapi(isluafunc(fn1), "stack slot %d is not a Lua function", idx1);
> +  lj_checkapi(isluafunc(fn2), "stack slot %d is not a Lua function", idx2);
> +  lj_checkapi((uint32_t)n1 < fn1->l.nupvalues, "bad upvalue %d", n1+1);
> +  lj_checkapi((uint32_t)n2 < fn2->l.nupvalues, "bad upvalue %d", n2+1);
>     setgcrefr(fn1->l.uvptr[n1], fn2->l.uvptr[n2]);
>     lj_gc_objbarrier(L, fn1, gcref(fn1->l.uvptr[n1]));
>   }
> @@ -970,9 +982,8 @@ LUALIB_API void *luaL_checkudata(lua_State *L, int idx, const char *tname)
>   LUA_API void lua_settable(lua_State *L, int idx)
>   {
>     TValue *o;
> -  cTValue *t = index2adr(L, idx);
> -  api_checknelems(L, 2);
> -  api_checkvalidindex(L, t);
> +  cTValue *t = index2adr_check(L, idx);
> +  lj_checkapi_slot(2);
>     o = lj_meta_tset(L, t, L->top-2);
>     if (o) {
>       /* NOBARRIER: lj_meta_tset ensures the table is not black. */
> @@ -991,9 +1002,8 @@ LUA_API void lua_setfield(lua_State *L, int idx, const char *k)
>   {
>     TValue *o;
>     TValue key;
> -  cTValue *t = index2adr(L, idx);
> -  api_checknelems(L, 1);
> -  api_checkvalidindex(L, t);
> +  cTValue *t = index2adr_check(L, idx);
> +  lj_checkapi_slot(1);
>     setstrV(L, &key, lj_str_newz(L, k));
>     o = lj_meta_tset(L, t, &key);
>     if (o) {
> @@ -1012,7 +1022,7 @@ LUA_API void lua_rawset(lua_State *L, int idx)
>   {
>     GCtab *t = tabV(index2adr(L, idx));
>     TValue *dst, *key;
> -  api_checknelems(L, 2);
> +  lj_checkapi_slot(2);
>     key = L->top-2;
>     dst = lj_tab_set(L, t, key);
>     copyTV(L, dst, key+1);
> @@ -1024,7 +1034,7 @@ LUA_API void lua_rawseti(lua_State *L, int idx, int n)
>   {
>     GCtab *t = tabV(index2adr(L, idx));
>     TValue *dst, *src;
> -  api_checknelems(L, 1);
> +  lj_checkapi_slot(1);
>     dst = lj_tab_setint(L, t, n);
>     src = L->top-1;
>     copyTV(L, dst, src);
> @@ -1036,13 +1046,12 @@ LUA_API int lua_setmetatable(lua_State *L, int idx)
>   {
>     global_State *g;
>     GCtab *mt;
> -  cTValue *o = index2adr(L, idx);
> -  api_checknelems(L, 1);
> -  api_checkvalidindex(L, o);
> +  cTValue *o = index2adr_check(L, idx);
> +  lj_checkapi_slot(1);
>     if (tvisnil(L->top-1)) {
>       mt = NULL;
>     } else {
> -    api_check(L, tvistab(L->top-1));
> +    lj_checkapi(tvistab(L->top-1), "top stack slot is not a table");
>       mt = tabV(L->top-1);
>     }
>     g = G(L);
> @@ -1079,11 +1088,10 @@ LUALIB_API void luaL_setmetatable(lua_State *L, const char *tname)
>   
>   LUA_API int lua_setfenv(lua_State *L, int idx)
>   {
> -  cTValue *o = index2adr(L, idx);
> +  cTValue *o = index2adr_check(L, idx);
>     GCtab *t;
> -  api_checknelems(L, 1);
> -  api_checkvalidindex(L, o);
> -  api_check(L, tvistab(L->top-1));
> +  lj_checkapi_slot(1);
> +  lj_checkapi(tvistab(L->top-1), "top stack slot is not a table");
>     t = tabV(L->top-1);
>     if (tvisfunc(o)) {
>       setgcref(funcV(o)->c.env, obj2gco(t));
> @@ -1106,7 +1114,7 @@ LUA_API const char *lua_setupvalue(lua_State *L, int idx, int n)
>     TValue *val;
>     GCobj *o;
>     const char *name;
> -  api_checknelems(L, 1);
> +  lj_checkapi_slot(1);
>     name = lj_debug_uvnamev(f, (uint32_t)(n-1), &val, &o);
>     if (name) {
>       L->top--;
> @@ -1133,8 +1141,9 @@ static TValue *api_call_base(lua_State *L, int nargs)
>   
>   LUA_API void lua_call(lua_State *L, int nargs, int nresults)
>   {
> -  api_check(L, L->status == LUA_OK || L->status == LUA_ERRERR);
> -  api_checknelems(L, nargs+1);
> +  lj_checkapi(L->status == LUA_OK || L->status == LUA_ERRERR,
> +	      "thread called in wrong state %d", L->status);
> +  lj_checkapi_slot(nargs+1);
>     jit_secure_call(L, api_call_base(L, nargs), nresults+1);
>   }
>   
> @@ -1144,13 +1153,13 @@ LUA_API int lua_pcall(lua_State *L, int nargs, int nresults, int errfunc)
>     uint8_t oldh = hook_save(g);
>     ptrdiff_t ef;
>     int status;
> -  api_check(L, L->status == LUA_OK || L->status == LUA_ERRERR);
> -  api_checknelems(L, nargs+1);
> +  lj_checkapi(L->status == LUA_OK || L->status == LUA_ERRERR,
> +	      "thread called in wrong state %d", L->status);
> +  lj_checkapi_slot(nargs+1);
>     if (errfunc == 0) {
>       ef = 0;
>     } else {
> -    cTValue *o = stkindex2adr(L, errfunc);
> -    api_checkvalidindex(L, o);
> +    cTValue *o = index2adr_stack(L, errfunc);
>       ef = savestack(L, o);
>     }
>     /* Forbid Lua world re-entrancy while running the trace */
> @@ -1186,7 +1195,8 @@ LUA_API int lua_cpcall(lua_State *L, lua_CFunction func, void *ud)
>     global_State *g = G(L);
>     uint8_t oldh = hook_save(g);
>     int status;
> -  api_check(L, L->status == LUA_OK || L->status == LUA_ERRERR);
> +  lj_checkapi(L->status == LUA_OK || L->status == LUA_ERRERR,
> +	      "thread called in wrong state %d", L->status);
>     /* Forbid Lua world re-entrancy while running the trace */
>     if (tvref(g->jit_base)) {
>       setstrV(L, L->top++, lj_err_str(L, LJ_ERR_JITCALL));
> diff --git a/src/lj_asm.c b/src/lj_asm.c
> index a6906b19..d71fa8c8 100644
> --- a/src/lj_asm.c
> +++ b/src/lj_asm.c
> @@ -100,6 +100,12 @@ typedef struct ASMState {
>     uint16_t parentmap[LJ_MAX_JSLOTS];  /* Parent instruction to RegSP map. */
>   } ASMState;
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertA(c, ...)	lj_assertG_(J2G(as->J), (c), __VA_ARGS__)
> +#else
> +#define lj_assertA(c, ...)	((void)as)
> +#endif
> +
>   #define IR(ref)			(&as->ir[(ref)])
>   
>   #define ASMREF_TMP1		REF_TRUE	/* Temp. register. */
> @@ -131,9 +137,8 @@ static LJ_AINLINE void checkmclim(ASMState *as)
>   #ifdef LUA_USE_ASSERT
>     if (as->mcp + MCLIM_REDZONE < as->mcp_prev) {
>       IRIns *ir = IR(as->curins+1);
> -    fprintf(stderr, "RED ZONE OVERFLOW: %p IR %04d  %02d %04d %04d\n", as->mcp,
> -	    as->curins+1-REF_BIAS, ir->o, ir->op1-REF_BIAS, ir->op2-REF_BIAS);
> -    lua_assert(0);
> +    lj_assertA(0, "red zone overflow: %p IR %04d  %02d %04d %04d\n", as->mcp,
> +      as->curins+1-REF_BIAS, ir->o, ir->op1-REF_BIAS, ir->op2-REF_BIAS);
>     }
>   #endif
>     if (LJ_UNLIKELY(as->mcp < as->mclim)) asm_mclimit(as);
> @@ -247,7 +252,7 @@ static void ra_dprintf(ASMState *as, const char *fmt, ...)
>   	  *p++ = *q >= 'A' && *q <= 'Z' ? *q + 0x20 : *q;
>         } else {
>   	*p++ = '?';
> -	lua_assert(0);
> +	lj_assertA(0, "bad register %d for debug format \"%s\"", r, fmt);
>         }
>       } else if (e[1] == 'f' || e[1] == 'i') {
>         IRRef ref;
> @@ -265,7 +270,7 @@ static void ra_dprintf(ASMState *as, const char *fmt, ...)
>       } else if (e[1] == 'x') {
>         p += sprintf(p, "%08x", va_arg(argp, int32_t));
>       } else {
> -      lua_assert(0);
> +      lj_assertA(0, "bad debug format code");
>       }
>       fmt = e+2;
>     }
> @@ -324,7 +329,7 @@ static Reg ra_rematk(ASMState *as, IRRef ref)
>     Reg r;
>     if (ra_iskref(ref)) {
>       r = ra_krefreg(ref);
> -    lua_assert(!rset_test(as->freeset, r));
> +    lj_assertA(!rset_test(as->freeset, r), "rematk of free reg %d", r);
>       ra_free(as, r);
>       ra_modified(as, r);
>   #if LJ_64
> @@ -336,7 +341,9 @@ static Reg ra_rematk(ASMState *as, IRRef ref)
>     }
>     ir = IR(ref);
>     r = ir->r;
> -  lua_assert(ra_hasreg(r) && !ra_hasspill(ir->s));
> +  lj_assertA(ra_hasreg(r), "rematk of K%03d has no reg", REF_BIAS - ref);
> +  lj_assertA(!ra_hasspill(ir->s),
> +	     "rematk of K%03d has spill slot [%x]", REF_BIAS - ref, ir->s);
>     ra_free(as, r);
>     ra_modified(as, r);
>     ir->r = RID_INIT;  /* Do not keep any hint. */
> @@ -350,7 +357,8 @@ static Reg ra_rematk(ASMState *as, IRRef ref)
>       ra_sethint(ir->r, RID_BASE);  /* Restore BASE register hint. */
>       emit_getgl(as, r, jit_base);
>     } else if (emit_canremat(ASMREF_L) && ir->o == IR_KPRI) {
> -    lua_assert(irt_isnil(ir->t));  /* REF_NIL stores ASMREF_L register. */
> +    /* REF_NIL stores ASMREF_L register. */
> +    lj_assertA(irt_isnil(ir->t), "rematk of bad ASMREF_L");
>       emit_getgl(as, r, cur_L);
>   #if LJ_64
>     } else if (ir->o == IR_KINT64) {
> @@ -363,8 +371,9 @@ static Reg ra_rematk(ASMState *as, IRRef ref)
>   #endif
>   #endif
>     } else {
> -    lua_assert(ir->o == IR_KINT || ir->o == IR_KGC ||
> -	       ir->o == IR_KPTR || ir->o == IR_KKPTR || ir->o == IR_KNULL);
> +    lj_assertA(ir->o == IR_KINT || ir->o == IR_KGC ||
> +	       ir->o == IR_KPTR || ir->o == IR_KKPTR || ir->o == IR_KNULL,
> +	       "rematk of bad IR op %d", ir->o);
>       emit_loadi(as, r, ir->i);
>     }
>     return r;
> @@ -374,7 +383,8 @@ static Reg ra_rematk(ASMState *as, IRRef ref)
>   static int32_t ra_spill(ASMState *as, IRIns *ir)
>   {
>     int32_t slot = ir->s;
> -  lua_assert(ir >= as->ir + REF_TRUE);
> +  lj_assertA(ir >= as->ir + REF_TRUE,
> +	     "spill of K%03d", REF_BIAS - (int)(ir - as->ir));
>     if (!ra_hasspill(slot)) {
>       if (irt_is64(ir->t)) {
>         slot = as->evenspill;
> @@ -399,7 +409,9 @@ static Reg ra_releasetmp(ASMState *as, IRRef ref)
>   {
>     IRIns *ir = IR(ref);
>     Reg r = ir->r;
> -  lua_assert(ra_hasreg(r) && !ra_hasspill(ir->s));
> +  lj_assertA(ra_hasreg(r), "release of TMP%d has no reg", ref-ASMREF_TMP1+1);
> +  lj_assertA(!ra_hasspill(ir->s),
> +	     "release of TMP%d has spill slot [%x]", ref-ASMREF_TMP1+1, ir->s);
>     ra_free(as, r);
>     ra_modified(as, r);
>     ir->r = RID_INIT;
> @@ -415,7 +427,7 @@ static Reg ra_restore(ASMState *as, IRRef ref)
>       IRIns *ir = IR(ref);
>       int32_t ofs = ra_spill(as, ir);  /* Force a spill slot. */
>       Reg r = ir->r;
> -    lua_assert(ra_hasreg(r));
> +    lj_assertA(ra_hasreg(r), "restore of IR %04d has no reg", ref - REF_BIAS);
>       ra_sethint(ir->r, r);  /* Keep hint. */
>       ra_free(as, r);
>       if (!rset_test(as->weakset, r)) {  /* Only restore non-weak references. */
> @@ -444,14 +456,15 @@ static Reg ra_evict(ASMState *as, RegSet allow)
>   {
>     IRRef ref;
>     RegCost cost = ~(RegCost)0;
> -  lua_assert(allow != RSET_EMPTY);
> +  lj_assertA(allow != RSET_EMPTY, "evict from empty set");
>     if (RID_NUM_FPR == 0 || allow < RID2RSET(RID_MAX_GPR)) {
>       GPRDEF(MINCOST)
>     } else {
>       FPRDEF(MINCOST)
>     }
>     ref = regcost_ref(cost);
> -  lua_assert(ra_iskref(ref) || (ref >= as->T->nk && ref < as->T->nins));
> +  lj_assertA(ra_iskref(ref) || (ref >= as->T->nk && ref < as->T->nins),
> +	     "evict of out-of-range IR %04d", ref - REF_BIAS);
>     /* Preferably pick any weak ref instead of a non-weak, non-const ref. */
>     if (!irref_isk(ref) && (as->weakset & allow)) {
>       IRIns *ir = IR(ref);
> @@ -609,7 +622,8 @@ static Reg ra_allocref(ASMState *as, IRRef ref, RegSet allow)
>     IRIns *ir = IR(ref);
>     RegSet pick = as->freeset & allow;
>     Reg r;
> -  lua_assert(ra_noreg(ir->r));
> +  lj_assertA(ra_noreg(ir->r),
> +	     "IR %04d already has reg %d", ref - REF_BIAS, ir->r);
>     if (pick) {
>       /* First check register hint from propagation or PHI. */
>       if (ra_hashint(ir->r)) {
> @@ -673,8 +687,10 @@ static void ra_rename(ASMState *as, Reg down, Reg up)
>     IRIns *ir = IR(ref);
>     ir->r = (uint8_t)up;
>     as->cost[down] = 0;
> -  lua_assert((down < RID_MAX_GPR) == (up < RID_MAX_GPR));
> -  lua_assert(!rset_test(as->freeset, down) && rset_test(as->freeset, up));
> +  lj_assertA((down < RID_MAX_GPR) == (up < RID_MAX_GPR),
> +	     "rename between GPR/FPR %d and %d", down, up);
> +  lj_assertA(!rset_test(as->freeset, down), "rename from free reg %d", down);
> +  lj_assertA(rset_test(as->freeset, up), "rename to non-free reg %d", up);
>     ra_free(as, down);  /* 'down' is free ... */
>     ra_modified(as, down);
>     rset_clear(as->freeset, up);  /* ... and 'up' is now allocated. */
> @@ -722,7 +738,7 @@ static void ra_destreg(ASMState *as, IRIns *ir, Reg r)
>   {
>     Reg dest = ra_dest(as, ir, RID2RSET(r));
>     if (dest != r) {
> -    lua_assert(rset_test(as->freeset, r));
> +    lj_assertA(rset_test(as->freeset, r), "dest reg %d is not free", r);
>       ra_modified(as, r);
>       emit_movrr(as, ir, dest, r);
>     }
> @@ -755,8 +771,9 @@ static void ra_left(ASMState *as, Reg dest, IRRef lref)
>   #endif
>   #endif
>         } else if (ir->o != IR_KPRI) {
> -	lua_assert(ir->o == IR_KINT || ir->o == IR_KGC ||
> -		   ir->o == IR_KPTR || ir->o == IR_KKPTR || ir->o == IR_KNULL);
> +	lj_assertA(ir->o == IR_KINT || ir->o == IR_KGC ||
> +		   ir->o == IR_KPTR || ir->o == IR_KKPTR || ir->o == IR_KNULL,
> +		   "K%03d has bad IR op %d", REF_BIAS - lref, ir->o);
>   	emit_loadi(as, dest, ir->i);
>   	return;
>         }
> @@ -901,11 +918,14 @@ static void asm_snap_alloc1(ASMState *as, IRRef ref)
>   #endif
>         {  /* Allocate stored values for TNEW, TDUP and CNEW. */
>   	IRIns *irs;
> -	lua_assert(ir->o == IR_TNEW || ir->o == IR_TDUP || ir->o == IR_CNEW);
> +	lj_assertA(ir->o == IR_TNEW || ir->o == IR_TDUP || ir->o == IR_CNEW,
> +		   "sink of IR %04d has bad op %d", ref - REF_BIAS, ir->o);
>   	for (irs = IR(as->snapref-1); irs > ir; irs--)
>   	  if (irs->r == RID_SINK && asm_sunk_store(as, ir, irs)) {
> -	    lua_assert(irs->o == IR_ASTORE || irs->o == IR_HSTORE ||
> -		       irs->o == IR_FSTORE || irs->o == IR_XSTORE);
> +	    lj_assertA(irs->o == IR_ASTORE || irs->o == IR_HSTORE ||
> +		       irs->o == IR_FSTORE || irs->o == IR_XSTORE,
> +		       "sunk store IR %04d has bad op %d",
> +		       (int)(irs - as->ir) - REF_BIAS, irs->o);
>   	    asm_snap_alloc1(as, irs->op2);
>   	    if (LJ_32 && (irs+1)->o == IR_HIOP)
>   	      asm_snap_alloc1(as, (irs+1)->op2);
> @@ -953,15 +973,9 @@ static void asm_snap_alloc(ASMState *as, int snapno)
>       if (!irref_isk(ref)) {
>         asm_snap_alloc1(as, ref);
>         if (LJ_SOFTFP && (sn & SNAP_SOFTFPNUM)) {
> -	/*
> -	** FIXME: The following assert was replaced with
> -	** the conventional `lua_assert`.
> -	**
> -	** lj_assertA(irt_type(IR(ref+1)->t) == IRT_SOFTFP,
> -	** "snap %d[%d] points to bad SOFTFP IR %04d",
> -	** snapno, n, ref - REF_BIAS);
> -	*/
> -	lua_assert(irt_type(IR(ref+1)->t) == IRT_SOFTFP);
> +	lj_assertA(irt_type(IR(ref+1)->t) == IRT_SOFTFP,
> +		   "snap %d[%d] points to bad SOFTFP IR %04d",
> +		   snapno, n, ref - REF_BIAS);
>   	asm_snap_alloc1(as, ref+1);
>         }
>       }
> @@ -1045,19 +1059,20 @@ static int32_t asm_stack_adjust(ASMState *as)
>   }
>   
>   /* Must match with hash*() in lj_tab.c. */
> -static uint32_t ir_khash(IRIns *ir)
> +static uint32_t ir_khash(ASMState *as, IRIns *ir)
>   {
>     uint32_t lo, hi;
> +  UNUSED(as);
>     if (irt_isstr(ir->t)) {
>       return ir_kstr(ir)->hash;
>     } else if (irt_isnum(ir->t)) {
>       lo = ir_knum(ir)->u32.lo;
>       hi = ir_knum(ir)->u32.hi << 1;
>     } else if (irt_ispri(ir->t)) {
> -    lua_assert(!irt_isnil(ir->t));
> +    lj_assertA(!irt_isnil(ir->t), "hash of nil key");
>       return irt_type(ir->t)-IRT_FALSE;
>     } else {
> -    lua_assert(irt_isgcv(ir->t));
> +    lj_assertA(irt_isgcv(ir->t), "hash of bad IR type %d", irt_type(ir->t));
>       lo = u32ptr(ir_kgc(ir));
>   #if LJ_GC64
>       hi = (uint32_t)(u64ptr(ir_kgc(ir)) >> 32) | (irt_toitype(ir->t) << 15);
> @@ -1168,7 +1183,8 @@ static void asm_bufput(ASMState *as, IRIns *ir)
>     args[0] = ir->op1;  /* SBuf * */
>     args[1] = ir->op2;  /* GCstr * */
>     irs = IR(ir->op2);
> -  lua_assert(irt_isstr(irs->t));
> +  lj_assertA(irt_isstr(irs->t),
> +	     "BUFPUT of non-string IR %04d", ir->op2 - REF_BIAS);
>     if (irs->o == IR_KGC) {
>       GCstr *s = ir_kstr(irs);
>       if (s->len == 1) {  /* Optimize put of single-char string constant. */
> @@ -1182,7 +1198,8 @@ static void asm_bufput(ASMState *as, IRIns *ir)
>   	args[1] = ASMREF_TMP1;  /* TValue * */
>   	ci = &lj_ir_callinfo[IRCALL_lj_strfmt_putnum];
>         } else {
> -	lua_assert(irt_isinteger(IR(irs->op1)->t));
> +	lj_assertA(irt_isinteger(IR(irs->op1)->t),
> +		   "TOSTR of non-numeric IR %04d", irs->op1);
>   	args[1] = irs->op1;  /* int */
>   	if (irs->op2 == IRTOSTR_INT)
>   	  ci = &lj_ir_callinfo[IRCALL_lj_strfmt_putint];
> @@ -1248,7 +1265,8 @@ static void asm_conv64(ASMState *as, IRIns *ir)
>     IRType dt = (((ir-1)->op2 & IRCONV_DSTMASK) >> IRCONV_DSH);
>     IRCallID id;
>     IRRef args[2];
> -  lua_assert((ir-1)->o == IR_CONV && ir->o == IR_HIOP);
> +  lj_assertA((ir-1)->o == IR_CONV && ir->o == IR_HIOP,
> +	     "not a CONV/HIOP pair at IR %04d", (int)(ir - as->ir) - REF_BIAS);
>     args[LJ_BE] = (ir-1)->op1;
>     args[LJ_LE] = ir->op1;
>     if (st == IRT_NUM || st == IRT_FLOAT) {
> @@ -1304,15 +1322,16 @@ static void asm_collectargs(ASMState *as, IRIns *ir,
>   			    const CCallInfo *ci, IRRef *args)
>   {
>     uint32_t n = CCI_XNARGS(ci);
> -  lua_assert(n <= CCI_NARGS_MAX*2);  /* Account for split args. */
> +  /* Account for split args. */
> +  lj_assertA(n <= CCI_NARGS_MAX*2, "too many args %d to collect", n);
>     if ((ci->flags & CCI_L)) { *args++ = ASMREF_L; n--; }
>     while (n-- > 1) {
>       ir = IR(ir->op1);
> -    lua_assert(ir->o == IR_CARG);
> +    lj_assertA(ir->o == IR_CARG, "malformed CALL arg tree");
>       args[n] = ir->op2 == REF_NIL ? 0 : ir->op2;
>     }
>     args[0] = ir->op1 == REF_NIL ? 0 : ir->op1;
> -  lua_assert(IR(ir->op1)->o != IR_CARG);
> +  lj_assertA(IR(ir->op1)->o != IR_CARG, "malformed CALL arg tree");
>   }
>   
>   /* Reconstruct CCallInfo flags for CALLX*. */
> @@ -1690,7 +1709,10 @@ static void asm_ir(ASMState *as, IRIns *ir)
>     switch ((IROp)ir->o) {
>     /* Miscellaneous ops. */
>     case IR_LOOP: asm_loop(as); break;
> -  case IR_NOP: case IR_XBAR: lua_assert(!ra_used(ir)); break;
> +  case IR_NOP: case IR_XBAR:
> +    lj_assertA(!ra_used(ir),
> +	       "IR %04d not unused", (int)(ir - as->ir) - REF_BIAS);
> +    break;
>     case IR_USE:
>       ra_alloc1(as, ir->op1, irt_isfp(ir->t) ? RSET_FPR : RSET_GPR); break;
>     case IR_PHI: asm_phi(as, ir); break;
> @@ -1729,7 +1751,9 @@ static void asm_ir(ASMState *as, IRIns *ir)
>   #if LJ_SOFTFP32
>     case IR_DIV: case IR_POW: case IR_ABS:
>     case IR_LDEXP: case IR_FPMATH: case IR_TOBIT:
> -    lua_assert(0);  /* Unused for LJ_SOFTFP32. */
> +    /* Unused for LJ_SOFTFP32. */
> +    lj_assertA(0, "IR %04d with unused op %d",
> +		  (int)(ir - as->ir) - REF_BIAS, ir->o);
>       break;
>   #else
>     case IR_DIV: asm_div(as, ir); break;
> @@ -1777,7 +1801,8 @@ static void asm_ir(ASMState *as, IRIns *ir)
>   #if LJ_HASFFI
>       asm_cnew(as, ir);
>   #else
> -    lua_assert(0);
> +    lj_assertA(0, "IR %04d with unused op %d",
> +		  (int)(ir - as->ir) - REF_BIAS, ir->o);
>   #endif
>       break;
>   
> @@ -1854,8 +1879,10 @@ static void asm_head_side(ASMState *as)
>     for (i = as->stopins; i > REF_BASE; i--) {
>       IRIns *ir = IR(i);
>       RegSP rs;
> -    lua_assert((ir->o == IR_SLOAD && (ir->op2 & IRSLOAD_PARENT)) ||
> -	       (LJ_SOFTFP && ir->o == IR_HIOP) || ir->o == IR_PVAL);
> +    lj_assertA((ir->o == IR_SLOAD && (ir->op2 & IRSLOAD_PARENT)) ||
> +	       (LJ_SOFTFP && ir->o == IR_HIOP) || ir->o == IR_PVAL,
> +	       "IR %04d has bad parent op %d",
> +	       (int)(ir - as->ir) - REF_BIAS, ir->o);
>       rs = as->parentmap[i - REF_FIRST];
>       if (ra_hasreg(ir->r)) {
>         rset_clear(allow, ir->r);
> @@ -2115,7 +2142,7 @@ static void asm_setup_regsp(ASMState *as)
>     ir = IR(REF_FIRST);
>     if (as->parent) {
>       uint16_t *p;
> -    lastir = lj_snap_regspmap(as->parent, as->J->exitno, ir);
> +    lastir = lj_snap_regspmap(as->J, as->parent, as->J->exitno, ir);
>       if (lastir - ir > LJ_MAX_JSLOTS)
>         lj_trace_err(as->J, LJ_TRERR_NYICOAL);
>       as->stopins = (IRRef)((lastir-1) - as->ir);
> @@ -2418,7 +2445,10 @@ void lj_asm_trace(jit_State *J, GCtrace *T)
>       /* Assemble a trace in linear backwards order. */
>       for (as->curins--; as->curins > as->stopins; as->curins--) {
>         IRIns *ir = IR(as->curins);
> -      lua_assert(!(LJ_32 && irt_isint64(ir->t)));  /* Handled by SPLIT. */
> +      /* 64 bit types handled by SPLIT for 32 bit archs. */
> +      lj_assertA(!(LJ_32 && irt_isint64(ir->t)),
> +		 "IR %04d has unsplit 64 bit type",
> +		 (int)(ir - as->ir) - REF_BIAS);
>         asm_snap_prev(as);
>         if (!ra_used(ir) && !ir_sideeff(ir) && (as->flags & JIT_F_OPT_DCE))
>   	continue;  /* Dead-code elimination can be soooo easy. */
> @@ -2449,7 +2479,7 @@ void lj_asm_trace(jit_State *J, GCtrace *T)
>       asm_phi_fixup(as);
>   
>       if (J->curfinal->nins >= T->nins) {  /* IR didn't grow? */
> -      lua_assert(J->curfinal->nk == T->nk);
> +      lj_assertA(J->curfinal->nk == T->nk, "unexpected IR constant growth");
>         memcpy(J->curfinal->ir + as->orignins, T->ir + as->orignins,
>   	     (T->nins - as->orignins) * sizeof(IRIns));  /* Copy RENAMEs. */
>         T->nins = J->curfinal->nins;
> diff --git a/src/lj_asm_arm.h b/src/lj_asm_arm.h
> index 29a07c80..47564d2e 100644
> --- a/src/lj_asm_arm.h
> +++ b/src/lj_asm_arm.h
> @@ -41,7 +41,7 @@ static Reg ra_scratchpair(ASMState *as, RegSet allow)
>         }
>       }
>     }
> -  lua_assert(rset_test(RSET_GPREVEN, r));
> +  lj_assertA(rset_test(RSET_GPREVEN, r), "odd reg %d", r);
>     ra_modified(as, r);
>     ra_modified(as, r+1);
>     RA_DBGX((as, "scratchpair    $r $r", r, r+1));
> @@ -269,7 +269,7 @@ static void asm_fusexref(ASMState *as, ARMIns ai, Reg rd, IRRef ref,
>   	return;
>         }
>       } else if (ir->o == IR_STRREF && !(!LJ_SOFTFP && (ai & 0x08000000))) {
> -      lua_assert(ofs == 0);
> +      lj_assertA(ofs == 0, "bad usage");
>         ofs = (int32_t)sizeof(GCstr);
>         if (irref_isk(ir->op2)) {
>   	ofs += IR(ir->op2)->i;
> @@ -389,9 +389,11 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>         as->freeset |= (of & RSET_RANGE(REGARG_FIRSTGPR, REGARG_LASTGPR+1));
>         if (irt_isnum(ir->t)) gpr = (gpr+1) & ~1u;
>         if (gpr <= REGARG_LASTGPR) {
> -	lua_assert(rset_test(as->freeset, gpr));  /* Must have been evicted. */
> +	lj_assertA(rset_test(as->freeset, gpr),
> +		   "reg %d not free", gpr);  /* Must have been evicted. */
>   	if (irt_isnum(ir->t)) {
> -	  lua_assert(rset_test(as->freeset, gpr+1));  /* Ditto. */
> +	  lj_assertA(rset_test(as->freeset, gpr+1),
> +		     "reg %d not free", gpr+1);  /* Ditto. */
>   	  emit_dnm(as, ARMI_VMOV_RR_D, gpr, gpr+1, (src & 15));
>   	  gpr += 2;
>   	} else {
> @@ -408,7 +410,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #endif
>       {
>         if (gpr <= REGARG_LASTGPR) {
> -	lua_assert(rset_test(as->freeset, gpr));  /* Must have been evicted. */
> +	lj_assertA(rset_test(as->freeset, gpr),
> +		   "reg %d not free", gpr);  /* Must have been evicted. */
>   	if (ref) ra_leftov(as, gpr, ref);
>   	gpr++;
>         } else {
> @@ -433,7 +436,7 @@ static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
>       rset_clear(drop, (ir+1)->r);  /* Dest reg handled below. */
>     ra_evictset(as, drop);  /* Evictions must be performed first. */
>     if (ra_used(ir)) {
> -    lua_assert(!irt_ispri(ir->t));
> +    lj_assertA(!irt_ispri(ir->t), "PRI dest");
>       if (!LJ_SOFTFP && irt_isfp(ir->t)) {
>         if (LJ_ABI_SOFTFP || (ci->flags & (CCI_CASTU64|CCI_VARARG))) {
>   	Reg dest = (ra_dest(as, ir, RSET_FPR) & 15);
> @@ -530,13 +533,17 @@ static void asm_conv(ASMState *as, IRIns *ir)
>   #endif
>     IRRef lref = ir->op1;
>     /* 64 bit integer conversions are handled by SPLIT. */
> -  lua_assert(!irt_isint64(ir->t) && !(st == IRT_I64 || st == IRT_U64));
> +  lj_assertA(!irt_isint64(ir->t) && !(st == IRT_I64 || st == IRT_U64),
> +	     "IR %04d has unsplit 64 bit type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>   #if LJ_SOFTFP
>     /* FP conversions are handled by SPLIT. */
> -  lua_assert(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT));
> +  lj_assertA(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT),
> +	     "IR %04d has FP type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>     /* Can't check for same types: SPLIT uses CONV int.int + BXOR for sfp NEG. */
>   #else
> -  lua_assert(irt_type(ir->t) != st);
> +  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
>     if (irt_isfp(ir->t)) {
>       Reg dest = ra_dest(as, ir, RSET_FPR);
>       if (stfp) {  /* FP to FP conversion. */
> @@ -553,7 +560,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
>       } else {
>         Reg left = ra_alloc1(as, lref, RSET_FPR);
> @@ -572,7 +580,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>       Reg dest = ra_dest(as, ir, RSET_GPR);
>       if (st >= IRT_I8 && st <= IRT_U16) {  /* Extend to 32 bit integer. */
>         Reg left = ra_alloc1(as, lref, RSET_GPR);
> -      lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
> +      lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
>         if ((as->flags & JIT_F_ARMV6)) {
>   	ARMIns ai = st == IRT_I8 ? ARMI_SXTB :
>   		    st == IRT_U8 ? ARMI_UXTB :
> @@ -667,7 +675,7 @@ static void asm_tvptr(ASMState *as, Reg dest, IRRef ref)
>         ra_allockreg(as, i32ptr(ir_knum(ir)), dest);
>       } else {
>   #if LJ_SOFTFP
> -      lua_assert(0);
> +      lj_assertA(0, "unsplit FP op");
>   #else
>         /* Otherwise force a spill and use the spill slot. */
>         emit_opk(as, ARMI_ADD, dest, RID_SP, ra_spill(as, ir), RSET_GPR);
> @@ -811,7 +819,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>     *l_loop = ARMF_CC(ARMI_B, CC_NE) | ((as->mcp-l_loop-2) & 0x00ffffffu);
>   
>     /* Load main position relative to tab->node into dest. */
> -  khash = irref_isk(refkey) ? ir_khash(irkey) : 1;
> +  khash = irref_isk(refkey) ? ir_khash(as, irkey) : 1;
>     if (khash == 0) {
>       emit_lso(as, ARMI_LDR, dest, tab, (int32_t)offsetof(GCtab, node));
>     } else {
> @@ -867,7 +875,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>     Reg node = ra_alloc1(as, ir->op1, RSET_GPR);
>     Reg key = RID_NONE, type = RID_TMP, idx = node;
>     RegSet allow = rset_exclude(RSET_GPR, node);
> -  lua_assert(ofs % sizeof(Node) == 0);
> +  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
>     if (ofs > 4095) {
>       idx = dest;
>       rset_clear(allow, dest);
> @@ -934,7 +942,7 @@ static void asm_uref(ASMState *as, IRIns *ir)
>   static void asm_fref(ASMState *as, IRIns *ir)
>   {
>     UNUSED(as); UNUSED(ir);
> -  lua_assert(!ra_used(ir));
> +  lj_assertA(!ra_used(ir), "unfused FREF");
>   }
>   
>   static void asm_strref(ASMState *as, IRIns *ir)
> @@ -971,25 +979,27 @@ static void asm_strref(ASMState *as, IRIns *ir)
>   
>   /* -- Loads and stores ---------------------------------------------------- */
>   
> -static ARMIns asm_fxloadins(IRIns *ir)
> +static ARMIns asm_fxloadins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: return ARMI_LDRSB;
>     case IRT_U8: return ARMI_LDRB;
>     case IRT_I16: return ARMI_LDRSH;
>     case IRT_U16: return ARMI_LDRH;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP); return ARMI_VLDR_D;
> +  case IRT_NUM: lj_assertA(!LJ_SOFTFP, "unsplit FP op"); return ARMI_VLDR_D;
>     case IRT_FLOAT: if (!LJ_SOFTFP) return ARMI_VLDR_S;  /* fallthrough */
>     default: return ARMI_LDR;
>     }
>   }
>   
> -static ARMIns asm_fxstoreins(IRIns *ir)
> +static ARMIns asm_fxstoreins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: case IRT_U8: return ARMI_STRB;
>     case IRT_I16: case IRT_U16: return ARMI_STRH;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP); return ARMI_VSTR_D;
> +  case IRT_NUM: lj_assertA(!LJ_SOFTFP, "unsplit FP op"); return ARMI_VSTR_D;
>     case IRT_FLOAT: if (!LJ_SOFTFP) return ARMI_VSTR_S;  /* fallthrough */
>     default: return ARMI_STR;
>     }
> @@ -997,12 +1007,13 @@ static ARMIns asm_fxstoreins(IRIns *ir)
>   
>   static void asm_fload(ASMState *as, IRIns *ir)
>   {
> -  if (ir->op1 == REF_NIL) {
> -    lua_assert(!ra_used(ir));  /* We can end up here if DCE is turned off. */
> +  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
> +    /* We can end up here if DCE is turned off. */
> +    lj_assertA(!ra_used(ir), "NYI FLOAD GG_State");
>     } else {
>       Reg dest = ra_dest(as, ir, RSET_GPR);
>       Reg idx = ra_alloc1(as, ir->op1, RSET_GPR);
> -    ARMIns ai = asm_fxloadins(ir);
> +    ARMIns ai = asm_fxloadins(as, ir);
>       int32_t ofs;
>       if (ir->op2 == IRFL_TAB_ARRAY) {
>         ofs = asm_fuseabase(as, ir->op1);
> @@ -1026,7 +1037,7 @@ static void asm_fstore(ASMState *as, IRIns *ir)
>       IRIns *irf = IR(ir->op1);
>       Reg idx = ra_alloc1(as, irf->op1, rset_exclude(RSET_GPR, src));
>       int32_t ofs = field_ofs[irf->op2];
> -    ARMIns ai = asm_fxstoreins(ir);
> +    ARMIns ai = asm_fxstoreins(as, ir);
>       if ((ai & 0x04000000))
>         emit_lso(as, ai, src, idx, ofs);
>       else
> @@ -1038,8 +1049,8 @@ static void asm_xload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir,
>   		     (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -  lua_assert(!(ir->op2 & IRXLOAD_UNALIGNED));
> -  asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR, 0);
> +  lj_assertA(!(ir->op2 & IRXLOAD_UNALIGNED), "unaligned XLOAD");
> +  asm_fusexref(as, asm_fxloadins(as, ir), dest, ir->op1, RSET_GPR, 0);
>   }
>   
>   static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
> @@ -1047,7 +1058,7 @@ static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
>     if (ir->r != RID_SINK) {
>       Reg src = ra_alloc1(as, ir->op2,
>   			(!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -    asm_fusexref(as, asm_fxstoreins(ir), src, ir->op1,
> +    asm_fusexref(as, asm_fxstoreins(as, ir), src, ir->op1,
>   		 rset_exclude(RSET_GPR, src), ofs);
>     }
>   }
> @@ -1066,8 +1077,9 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>       rset_clear(allow, type);
>     }
>     if (ra_used(ir)) {
> -    lua_assert((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> -	       irt_isint(ir->t) || irt_isaddr(ir->t));
> +    lj_assertA((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> +	       irt_isint(ir->t) || irt_isaddr(ir->t),
> +	       "bad load type %d", irt_type(ir->t));
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && t == IRT_NUM) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
>     }
> @@ -1133,10 +1145,13 @@ static void asm_sload(ASMState *as, IRIns *ir)
>     IRType t = hiop ? IRT_NUM : irt_type(ir->t);
>     Reg dest = RID_NONE, type = RID_NONE, base;
>     RegSet allow = RSET_GPR;
> -  lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
> -  lua_assert(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK));
> +  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
> +	     "bad parent SLOAD");  /* Handled by asm_head_side(). */
> +  lj_assertA(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK),
> +	     "inconsistent SLOAD variant");
>   #if LJ_SOFTFP
> -  lua_assert(!(ir->op2 & IRSLOAD_CONVERT));  /* Handled by LJ_SOFTFP SPLIT. */
> +  lj_assertA(!(ir->op2 & IRSLOAD_CONVERT),
> +	     "unsplit SLOAD convert");  /* Handled by LJ_SOFTFP SPLIT. */
>     if (hiop && ra_used(ir+1)) {
>       type = ra_dest(as, ir+1, allow);
>       rset_clear(allow, type);
> @@ -1152,8 +1167,9 @@ static void asm_sload(ASMState *as, IRIns *ir)
>       Reg tmp = RID_NONE;
>       if ((ir->op2 & IRSLOAD_CONVERT))
>         tmp = ra_scratch(as, t == IRT_INT ? RSET_FPR : RSET_GPR);
> -    lua_assert((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> -	       irt_isint(ir->t) || irt_isaddr(ir->t));
> +    lj_assertA((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> +	       irt_isint(ir->t) || irt_isaddr(ir->t),
> +	       "bad SLOAD type %d", irt_type(ir->t));
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && t == IRT_NUM) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
>       base = ra_alloc1(as, REF_BASE, allow);
> @@ -1218,7 +1234,8 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     IRRef args[4];
>     RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
>     RegSet drop = RSET_SCRATCH;
> -  lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
> +  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
> +	     "bad CNEW/CNEWI operands");
>   
>     as->gcsteps++;
>     if (ra_hasreg(ir->r))
> @@ -1230,10 +1247,10 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     /* Initialize immutable cdata object. */
>     if (ir->o == IR_CNEWI) {
>       int32_t ofs = sizeof(GCcdata);
> -    lua_assert(sz == 4 || sz == 8);
> +    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
>       if (sz == 8) {
>         ofs += 4; ir++;
> -      lua_assert(ir->o == IR_HIOP);
> +      lj_assertA(ir->o == IR_HIOP, "expected HIOP for CNEWI");
>       }
>       for (;;) {
>         Reg r = ra_alloc1(as, ir->op2, allow);
> @@ -1306,7 +1323,7 @@ static void asm_obar(ASMState *as, IRIns *ir)
>     MCLabel l_end;
>     Reg obj, val, tmp;
>     /* No need for other object barriers (yet). */
> -  lua_assert(IR(ir->op1)->o == IR_UREFC);
> +  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
>     ra_evictset(as, RSET_SCRATCH);
>     l_end = emit_label(as);
>     args[0] = ASMREF_TMP1;  /* global_State *g */
> @@ -1580,7 +1597,7 @@ static void asm_bitshift(ASMState *as, IRIns *ir, ARMShift sh)
>   #define asm_bshr(as, ir)	asm_bitshift(as, ir, ARMSH_LSR)
>   #define asm_bsar(as, ir)	asm_bitshift(as, ir, ARMSH_ASR)
>   #define asm_bror(as, ir)	asm_bitshift(as, ir, ARMSH_ROR)
> -#define asm_brol(as, ir)	lua_assert(0)
> +#define asm_brol(as, ir)	lj_assertA(0, "unexpected BROL")
>   
>   static void asm_intmin_max(ASMState *as, IRIns *ir, int cc)
>   {
> @@ -1731,7 +1748,8 @@ static void asm_intcomp(ASMState *as, IRIns *ir)
>     Reg left;
>     uint32_t m;
>     int cmpprev0 = 0;
> -  lua_assert(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t));
> +  lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t),
> +	     "bad comparison data type %d", irt_type(ir->t));
>     if (asm_swapops(as, lref, rref)) {
>       Reg tmp = lref; lref = rref; rref = tmp;
>       if (cc >= CC_GE) cc ^= 7;  /* LT <-> GT, LE <-> GE */
> @@ -1900,10 +1918,11 @@ static void asm_hiop(ASMState *as, IRIns *ir)
>     case IR_CNEWI:
>       /* Nothing to do here. Handled by lo op itself. */
>       break;
> -  default: lua_assert(0); break;
> +  default: lj_assertA(0, "bad HIOP for op %d", (ir-1)->o); break;
>     }
>   #else
> -  UNUSED(as); UNUSED(ir); lua_assert(0);
> +  /* Unused without SOFTFP or FFI. */
> +  UNUSED(as); UNUSED(ir); lj_assertA(0, "unexpected HIOP");
>   #endif
>   }
>   
> @@ -1928,7 +1947,7 @@ static void asm_stack_check(ASMState *as, BCReg topslot,
>     if (irp) {
>       if (!ra_hasspill(irp->s)) {
>         pbase = irp->r;
> -      lua_assert(ra_hasreg(pbase));
> +      lj_assertA(ra_hasreg(pbase), "base reg lost");
>       } else if (allow) {
>         pbase = rset_pickbot(allow);
>       } else {
> @@ -1940,7 +1959,7 @@ static void asm_stack_check(ASMState *as, BCReg topslot,
>     }
>     emit_branch(as, ARMF_CC(ARMI_BL, CC_LS), exitstub_addr(as->J, exitno));
>     k = emit_isk12(0, (int32_t)(8*topslot));
> -  lua_assert(k);
> +  lj_assertA(k, "slot offset %d does not fit in K12", 8*topslot);
>     emit_n(as, ARMI_CMP^k, RID_TMP);
>     emit_dnm(as, ARMI_SUB, RID_TMP, RID_TMP, pbase);
>     emit_lso(as, ARMI_LDR, RID_TMP, RID_TMP,
> @@ -1977,7 +1996,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>   #if LJ_SOFTFP
>         RegSet odd = rset_exclude(RSET_GPRODD, RID_BASE);
>         Reg tmp;
> -      lua_assert(irref_isk(ref));  /* LJ_SOFTFP: must be a number constant. */
> +      /* LJ_SOFTFP: must be a number constant. */
> +      lj_assertA(irref_isk(ref), "unsplit FP op");
>         tmp = ra_allock(as, (int32_t)ir_knum(ir)->u32.lo,
>   		      rset_exclude(RSET_GPREVEN, RID_BASE));
>         emit_lso(as, ARMI_STR, tmp, RID_BASE, ofs);
> @@ -1991,7 +2011,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       } else {
>         RegSet odd = rset_exclude(RSET_GPRODD, RID_BASE);
>         Reg type;
> -      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
> +      lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t),
> +		 "restore of IR type %d", irt_type(ir->t));
>         if (!irt_ispri(ir->t)) {
>   	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPREVEN, RID_BASE));
>   	emit_lso(as, ARMI_STR, src, RID_BASE, ofs);
> @@ -2011,7 +2032,7 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       }
>       checkmclim(as);
>     }
> -  lua_assert(map + nent == flinks);
> +  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
>   }
>   
>   /* -- GC handling --------------------------------------------------------- */
> @@ -2097,7 +2118,7 @@ static RegSet asm_head_side_base(ASMState *as, IRIns *irp, RegSet allow)
>       rset_clear(allow, ra_dest(as, ir, allow));
>     } else {
>       Reg r = irp->r;
> -    lua_assert(ra_hasreg(r));
> +    lj_assertA(ra_hasreg(r), "base reg lost");
>       rset_clear(allow, r);
>       if (r != ir->r && !rset_test(as->freeset, r))
>         ra_restore(as, regcost_ref(as->cost[r]));
> @@ -2119,7 +2140,7 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
>     } else {
>       /* Patch stack adjustment. */
>       uint32_t k = emit_isk12(ARMI_ADD, spadj);
> -    lua_assert(k);
> +    lj_assertA(k, "stack adjustment %d does not fit in K12", spadj);
>       p[-2] = (ARMI_ADD^k) | ARMF_D(RID_SP) | ARMF_N(RID_SP);
>     }
>     /* Patch exit branch. */
> @@ -2201,7 +2222,7 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>         if (!cstart) cstart = p;
>       }
>     }
> -  lua_assert(cstart != NULL);
> +  lj_assertJ(cstart != NULL, "exit stub %d not found", exitno);
>     lj_mcode_sync(cstart, cend);
>     lj_mcode_patch(J, mcarea, 1);
>   }
> diff --git a/src/lj_asm_arm64.h b/src/lj_asm_arm64.h
> index c3d6889e..d1d4237b 100644
> --- a/src/lj_asm_arm64.h
> +++ b/src/lj_asm_arm64.h
> @@ -213,7 +213,7 @@ static uint32_t asm_fuseopm(ASMState *as, A64Ins ai, IRRef ref, RegSet allow)
>       return A64F_M(ir->r);
>     } else if (irref_isk(ref)) {
>       uint32_t m;
> -    int64_t k = get_k64val(ir);
> +    int64_t k = get_k64val(as, ref);
>       if ((ai & 0x1f000000) == 0x0a000000)
>         m = emit_isk13(k, irt_is64(ir->t));
>       else
> @@ -354,9 +354,9 @@ static int asm_fusemadd(ASMState *as, IRIns *ir, A64Ins ai, A64Ins air)
>   static int asm_fuseandshift(ASMState *as, IRIns *ir)
>   {
>     IRIns *irl = IR(ir->op1);
> -  lua_assert(ir->o == IR_BAND);
> +  lj_assertA(ir->o == IR_BAND, "bad usage");
>     if (canfuse(as, irl) && irref_isk(ir->op2)) {
> -    uint64_t mask = get_k64val(IR(ir->op2));
> +    uint64_t mask = get_k64val(as, ir->op2);
>       if (irref_isk(irl->op2) && (irl->o == IR_BSHR || irl->o == IR_BSHL)) {
>         int32_t shmask = irt_is64(irl->t) ? 63 : 31;
>         int32_t shift = (IR(irl->op2)->i & shmask);
> @@ -384,7 +384,7 @@ static int asm_fuseandshift(ASMState *as, IRIns *ir)
>   static int asm_fuseorshift(ASMState *as, IRIns *ir)
>   {
>     IRIns *irl = IR(ir->op1), *irr = IR(ir->op2);
> -  lua_assert(ir->o == IR_BOR);
> +  lj_assertA(ir->o == IR_BOR, "bad usage");
>     if (canfuse(as, irl) && canfuse(as, irr) &&
>         ((irl->o == IR_BSHR && irr->o == IR_BSHL) ||
>          (irl->o == IR_BSHL && irr->o == IR_BSHR))) {
> @@ -428,7 +428,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>       if (ref) {
>         if (irt_isfp(ir->t)) {
>   	if (fpr <= REGARG_LASTFPR) {
> -	  lua_assert(rset_test(as->freeset, fpr)); /* Must have been evicted. */
> +	  lj_assertA(rset_test(as->freeset, fpr),
> +		     "reg %d not free", fpr);  /* Must have been evicted. */
>   	  ra_leftov(as, fpr, ref);
>   	  fpr++;
>   	} else {
> @@ -438,7 +439,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   	}
>         } else {
>   	if (gpr <= REGARG_LASTGPR) {
> -	  lua_assert(rset_test(as->freeset, gpr)); /* Must have been evicted. */
> +	  lj_assertA(rset_test(as->freeset, gpr),
> +		     "reg %d not free", gpr);  /* Must have been evicted. */
>   	  ra_leftov(as, gpr, ref);
>   	  gpr++;
>   	} else {
> @@ -459,7 +461,7 @@ static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
>       rset_clear(drop, ir->r); /* Dest reg handled below. */
>     ra_evictset(as, drop); /* Evictions must be performed first. */
>     if (ra_used(ir)) {
> -    lua_assert(!irt_ispri(ir->t));
> +    lj_assertA(!irt_ispri(ir->t), "PRI dest");
>       if (irt_isfp(ir->t)) {
>         if (ci->flags & CCI_CASTU64) {
>   	Reg dest = ra_dest(as, ir, RSET_FPR) & 31;
> @@ -546,7 +548,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     int st64 = (st == IRT_I64 || st == IRT_U64 || st == IRT_P64);
>     int stfp = (st == IRT_NUM || st == IRT_FLOAT);
>     IRRef lref = ir->op1;
> -  lua_assert(irt_type(ir->t) != st);
> +  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
>     if (irt_isfp(ir->t)) {
>       Reg dest = ra_dest(as, ir, RSET_FPR);
>       if (stfp) {  /* FP to FP conversion. */
> @@ -566,7 +568,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
>       } else {
>         Reg left = ra_alloc1(as, lref, RSET_FPR);
> @@ -586,7 +589,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>       A64Ins ai = st == IRT_I8 ? A64I_SXTBw :
>   		st == IRT_U8 ? A64I_UXTBw :
>   		st == IRT_I16 ? A64I_SXTHw : A64I_UXTHw;
> -    lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
> +    lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
>       emit_dn(as, ai, dest, left);
>     } else {
>       Reg dest = ra_dest(as, ir, RSET_GPR);
> @@ -650,7 +653,8 @@ static void asm_tvstore64(ASMState *as, Reg base, int32_t ofs, IRRef ref)
>   {
>     RegSet allow = rset_exclude(RSET_GPR, base);
>     IRIns *ir = IR(ref);
> -  lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
> +  lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t),
> +	     "store of IR type %d", irt_type(ir->t));
>     if (irref_isk(ref)) {
>       TValue k;
>       lj_ir_kvalue(as->J->L, &k, ir);
> @@ -770,7 +774,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>       }
>       rset_clear(allow, scr);
>     } else {
> -    lua_assert(irt_ispri(kt) && !irt_isnil(kt));
> +    lj_assertA(irt_ispri(kt) && !irt_isnil(kt), "bad HREF key type");
>       type = ra_allock(as, ~((int64_t)~irt_toitype(ir->t) << 47), allow);
>       scr = ra_scratch(as, rset_clear(allow, type));
>       rset_clear(allow, scr);
> @@ -831,7 +835,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>       rset_clear(allow, type);
>     }
>     /* Load main position relative to tab->node into dest. */
> -  khash = isk ? ir_khash(irkey) : 1;
> +  khash = isk ? ir_khash(as, irkey) : 1;
>     if (khash == 0) {
>       emit_lso(as, A64I_LDRx, dest, tab, offsetof(GCtab, node));
>     } else {
> @@ -886,7 +890,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>     Reg key, idx = node;
>     RegSet allow = rset_exclude(RSET_GPR, node);
>     uint64_t k;
> -  lua_assert(ofs % sizeof(Node) == 0);
> +  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
>     if (bigofs) {
>       idx = dest;
>       rset_clear(allow, dest);
> @@ -936,7 +940,7 @@ static void asm_uref(ASMState *as, IRIns *ir)
>   static void asm_fref(ASMState *as, IRIns *ir)
>   {
>     UNUSED(as); UNUSED(ir);
> -  lua_assert(!ra_used(ir));
> +  lj_assertA(!ra_used(ir), "unfused FREF");
>   }
>   
>   static void asm_strref(ASMState *as, IRIns *ir)
> @@ -988,7 +992,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
>     Reg idx;
>     A64Ins ai = asm_fxloadins(ir);
>     int32_t ofs;
> -  if (ir->op1 == REF_NIL) {
> +  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
>       idx = RID_GL;
>       ofs = (ir->op2 << 2) - GG_OFS(g);
>     } else {
> @@ -1019,7 +1023,7 @@ static void asm_fstore(ASMState *as, IRIns *ir)
>   static void asm_xload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir, irt_isfp(ir->t) ? RSET_FPR : RSET_GPR);
> -  lua_assert(!(ir->op2 & IRXLOAD_UNALIGNED));
> +  lj_assertA(!(ir->op2 & IRXLOAD_UNALIGNED), "unaligned XLOAD");
>     asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR);
>   }
>   
> @@ -1037,8 +1041,9 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>     Reg idx, tmp, type;
>     int32_t ofs = 0;
>     RegSet gpr = RSET_GPR, allow = irt_isnum(ir->t) ? RSET_FPR : RSET_GPR;
> -  lua_assert(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> -	     irt_isint(ir->t));
> +  lj_assertA(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> +	     irt_isint(ir->t),
> +	     "bad load type %d", irt_type(ir->t));
>     if (ra_used(ir)) {
>       Reg dest = ra_dest(as, ir, allow);
>       tmp = irt_isnum(ir->t) ? ra_scratch(as, rset_clear(gpr, dest)) : dest;
> @@ -1057,7 +1062,8 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>     /* Always do the type check, even if the load result is unused. */
>     asm_guardcc(as, irt_isnum(ir->t) ? CC_LS : CC_NE);
>     if (irt_type(ir->t) >= IRT_NUM) {
> -    lua_assert(irt_isinteger(ir->t) || irt_isnum(ir->t));
> +    lj_assertA(irt_isinteger(ir->t) || irt_isnum(ir->t),
> +	       "bad load type %d", irt_type(ir->t));
>       emit_nm(as, A64I_CMPx | A64F_SH(A64SH_LSR, 32),
>   	    ra_allock(as, LJ_TISNUM << 15, rset_exclude(gpr, idx)), tmp);
>     } else if (irt_isaddr(ir->t)) {
> @@ -1122,8 +1128,10 @@ static void asm_sload(ASMState *as, IRIns *ir)
>     IRType1 t = ir->t;
>     Reg dest = RID_NONE, base;
>     RegSet allow = RSET_GPR;
> -  lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
> -  lua_assert(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK));
> +  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
> +	     "bad parent SLOAD");  /* Handled by asm_head_side(). */
> +  lj_assertA(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK),
> +	     "inconsistent SLOAD variant");
>     if ((ir->op2 & IRSLOAD_CONVERT) && irt_isguard(t) && irt_isint(t)) {
>       dest = ra_scratch(as, RSET_FPR);
>       asm_tointg(as, ir, dest);
> @@ -1132,7 +1140,8 @@ static void asm_sload(ASMState *as, IRIns *ir)
>       Reg tmp = RID_NONE;
>       if ((ir->op2 & IRSLOAD_CONVERT))
>         tmp = ra_scratch(as, irt_isint(t) ? RSET_FPR : RSET_GPR);
> -    lua_assert((irt_isnum(t)) || irt_isint(t) || irt_isaddr(t));
> +    lj_assertA((irt_isnum(t)) || irt_isint(t) || irt_isaddr(t),
> +	       "bad SLOAD type %d", irt_type(t));
>       dest = ra_dest(as, ir, irt_isnum(t) ? RSET_FPR : allow);
>       base = ra_alloc1(as, REF_BASE, rset_clear(allow, dest));
>       if (irt_isaddr(t)) {
> @@ -1172,7 +1181,8 @@ dotypecheck:
>       /* Need type check, even if the load result is unused. */
>       asm_guardcc(as, irt_isnum(t) ? CC_LS : CC_NE);
>       if (irt_type(t) >= IRT_NUM) {
> -      lua_assert(irt_isinteger(t) || irt_isnum(t));
> +      lj_assertA(irt_isinteger(t) || irt_isnum(t),
> +		 "bad SLOAD type %d", irt_type(t));
>         emit_nm(as, A64I_CMPx | A64F_SH(A64SH_LSR, 32),
>   	      ra_allock(as, LJ_TISNUM << 15, allow), tmp);
>       } else if (irt_isnil(t)) {
> @@ -1207,7 +1217,8 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_mem_newgco];
>     IRRef args[4];
>     RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
> -  lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
> +  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
> +	     "bad CNEW/CNEWI operands");
>   
>     as->gcsteps++;
>     asm_setupresult(as, ir, ci);  /* GCcdata * */
> @@ -1215,7 +1226,7 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     if (ir->o == IR_CNEWI) {
>       int32_t ofs = sizeof(GCcdata);
>       Reg r = ra_alloc1(as, ir->op2, allow);
> -    lua_assert(sz == 4 || sz == 8);
> +    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
>       emit_lso(as, sz == 8 ? A64I_STRx : A64I_STRw, r, RID_RET, ofs);
>     } else if (ir->op2 != REF_NIL) {  /* Create VLA/VLS/aligned cdata. */
>       ci = &lj_ir_callinfo[IRCALL_lj_cdata_newv];
> @@ -1281,7 +1292,7 @@ static void asm_obar(ASMState *as, IRIns *ir)
>     RegSet allow = RSET_GPR;
>     Reg obj, val, tmp;
>     /* No need for other object barriers (yet). */
> -  lua_assert(IR(ir->op1)->o == IR_UREFC);
> +  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
>     ra_evictset(as, RSET_SCRATCH);
>     l_end = emit_label(as);
>     args[0] = ASMREF_TMP1;  /* global_State *g */
> @@ -1551,7 +1562,7 @@ static void asm_bitshift(ASMState *as, IRIns *ir, A64Ins ai, A64Shift sh)
>   #define asm_bshr(as, ir)	asm_bitshift(as, ir, A64I_UBFMw, A64SH_LSR)
>   #define asm_bsar(as, ir)	asm_bitshift(as, ir, A64I_SBFMw, A64SH_ASR)
>   #define asm_bror(as, ir)	asm_bitshift(as, ir, A64I_EXTRw, A64SH_ROR)
> -#define asm_brol(as, ir)	lua_assert(0)
> +#define asm_brol(as, ir)	lj_assertA(0, "unexpected BROL")
>   
>   static void asm_intmin_max(ASMState *as, IRIns *ir, A64CC cc)
>   {
> @@ -1632,15 +1643,16 @@ static void asm_intcomp(ASMState *as, IRIns *ir)
>     Reg left;
>     uint32_t m;
>     int cmpprev0 = 0;
> -  lua_assert(irt_is64(ir->t) || irt_isint(ir->t) ||
> -	     irt_isu32(ir->t) || irt_isaddr(ir->t) || irt_isu8(ir->t));
> +  lj_assertA(irt_is64(ir->t) || irt_isint(ir->t) ||
> +	     irt_isu32(ir->t) || irt_isaddr(ir->t) || irt_isu8(ir->t),
> +	     "bad comparison data type %d", irt_type(ir->t));
>     if (asm_swapops(as, lref, rref)) {
>       IRRef tmp = lref; lref = rref; rref = tmp;
>       if (cc >= CC_GE) cc ^= 7;  /* LT <-> GT, LE <-> GE */
>       else if (cc > CC_NE) cc ^= 11;  /* LO <-> HI, LS <-> HS */
>     }
>     oldcc = cc;
> -  if (irref_isk(rref) && get_k64val(IR(rref)) == 0) {
> +  if (irref_isk(rref) && get_k64val(as, rref) == 0) {
>       IRIns *irl = IR(lref);
>       if (cc == CC_GE) cc = CC_PL;
>       else if (cc == CC_LT) cc = CC_MI;
> @@ -1655,7 +1667,7 @@ static void asm_intcomp(ASMState *as, IRIns *ir)
>   	Reg tmp = blref; blref = brref; brref = tmp;
>         }
>         if (irref_isk(brref)) {
> -	uint64_t k = get_k64val(IR(brref));
> +	uint64_t k = get_k64val(as, brref);
>   	if (k && !(k & (k-1)) && (cc == CC_EQ || cc == CC_NE)) {
>   	  asm_guardtnb(as, cc == CC_EQ ? A64I_TBZ : A64I_TBNZ,
>   		       ra_alloc1(as, blref, RSET_GPR), emit_ctz64(k));
> @@ -1704,7 +1716,8 @@ static void asm_comp(ASMState *as, IRIns *ir)
>   /* Hiword op of a split 64 bit op. Previous op must be the loword op. */
>   static void asm_hiop(ASMState *as, IRIns *ir)
>   {
> -  UNUSED(as); UNUSED(ir); lua_assert(0);  /* Unused on 64 bit. */
> +  UNUSED(as); UNUSED(ir);
> +  lj_assertA(0, "unexpected HIOP");  /* Unused on 64 bit. */
>   }
>   
>   /* -- Profiling ----------------------------------------------------------- */
> @@ -1712,7 +1725,7 @@ static void asm_hiop(ASMState *as, IRIns *ir)
>   static void asm_prof(ASMState *as, IRIns *ir)
>   {
>     uint32_t k = emit_isk13(HOOK_PROFILE, 0);
> -  lua_assert(k != 0);
> +  lj_assertA(k != 0, "HOOK_PROFILE does not fit in K13");
>     UNUSED(ir);
>     asm_guardcc(as, CC_NE);
>     emit_n(as, A64I_TSTw^k, RID_TMP);
> @@ -1730,7 +1743,7 @@ static void asm_stack_check(ASMState *as, BCReg topslot,
>     if (irp) {
>       if (!ra_hasspill(irp->s)) {
>         pbase = irp->r;
> -      lua_assert(ra_hasreg(pbase));
> +      lj_assertA(ra_hasreg(pbase), "base reg lost");
>       } else if (allow) {
>         pbase = rset_pickbot(allow);
>       } else {
> @@ -1742,7 +1755,7 @@ static void asm_stack_check(ASMState *as, BCReg topslot,
>     }
>     emit_cond_branch(as, CC_LS, asm_exitstub_addr(as, exitno));
>     k = emit_isk12((8*topslot));
> -  lua_assert(k);
> +  lj_assertA(k, "slot offset %d does not fit in K12", 8*topslot);
>     emit_n(as, A64I_CMPx^k, RID_TMP);
>     emit_dnm(as, A64I_SUBx, RID_TMP, RID_TMP, pbase);
>     emit_lso(as, A64I_LDRx, RID_TMP, RID_TMP,
> @@ -1783,7 +1796,7 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       }
>       checkmclim(as);
>     }
> -  lua_assert(map + nent == flinks);
> +  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
>   }
>   
>   /* -- GC handling --------------------------------------------------------- */
> @@ -1871,7 +1884,7 @@ static RegSet asm_head_side_base(ASMState *as, IRIns *irp, RegSet allow)
>       rset_clear(allow, ra_dest(as, ir, allow));
>     } else {
>       Reg r = irp->r;
> -    lua_assert(ra_hasreg(r));
> +    lj_assertA(ra_hasreg(r), "base reg lost");
>       rset_clear(allow, r);
>       if (r != ir->r && !rset_test(as->freeset, r))
>         ra_restore(as, regcost_ref(as->cost[r]));
> @@ -1895,7 +1908,7 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
>     } else {
>       /* Patch stack adjustment. */
>       uint32_t k = emit_isk12(spadj);
> -    lua_assert(k);
> +    lj_assertA(k, "stack adjustment %d does not fit in K12", spadj);
>       p[-2] = (A64I_ADDx^k) | A64F_D(RID_SP) | A64F_N(RID_SP);
>     }
>     /* Patch exit branch. */
> @@ -1981,7 +1994,7 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>       } else if ((ins & 0xfc000000u) == 0x14000000u &&
>   	       ((ins ^ (px-p)) & 0x03ffffffu) == 0) {
>         /* Patch b. */
> -      lua_assert(A64F_S_OK(delta, 26));
> +      lj_assertJ(A64F_S_OK(delta, 26), "branch target out of range");
>         *p = A64I_LE((ins & 0xfc000000u) | A64F_S26(delta));
>         if (!cstart) cstart = p;
>       } else if ((ins & 0x7e000000u) == 0x34000000u &&
> @@ -2002,7 +2015,7 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>     }
>     {  /* Always patch long-range branch in exit stub itself. */
>       ptrdiff_t delta = target - px;
> -    lua_assert(A64F_S_OK(delta, 26));
> +    lj_assertJ(A64F_S_OK(delta, 26), "branch target out of range");
>       *px = A64I_B | A64F_S26(delta);
>       if (!cstart) cstart = px;
>     }
> diff --git a/src/lj_asm_mips.h b/src/lj_asm_mips.h
> index 0f92959b..ea108aab 100644
> --- a/src/lj_asm_mips.h
> +++ b/src/lj_asm_mips.h
> @@ -23,7 +23,7 @@ static Reg ra_alloc1z(ASMState *as, IRRef ref, RegSet allow)
>   {
>     Reg r = IR(ref)->r;
>     if (ra_noreg(r)) {
> -    if (!(allow & RSET_FPR) && irref_isk(ref) && get_kval(IR(ref)) == 0)
> +    if (!(allow & RSET_FPR) && irref_isk(ref) && get_kval(as, ref) == 0)
>         return RID_ZERO;
>       r = ra_allocref(as, ref, allow);
>     } else {
> @@ -66,10 +66,10 @@ static void asm_sparejump_setup(ASMState *as)
>   {
>     MCode *mxp = as->mcbot;
>     if (((uintptr_t)mxp & (LJ_PAGESIZE-1)) == sizeof(MCLink)) {
> -    lua_assert(MIPSI_NOP == 0);
> +    lj_assertA(MIPSI_NOP == 0, "bad NOP");
>       memset(mxp, 0, MIPS_SPAREJUMP*2*sizeof(MCode));
>       mxp += MIPS_SPAREJUMP*2;
> -    lua_assert(mxp < as->mctop);
> +    lj_assertA(mxp < as->mctop, "MIPS_SPAREJUMP too big");
>       lj_mcode_sync(as->mcbot, mxp);
>       lj_mcode_commitbot(as->J, mxp);
>       as->mcbot = mxp;
> @@ -84,7 +84,8 @@ static void asm_exitstub_setup(ASMState *as)
>     /* sw TMP, 0(sp); j ->vm_exit_handler; li TMP, traceno */
>     *--mxp = MIPSI_LI|MIPSF_T(RID_TMP)|as->T->traceno;
>     *--mxp = MIPSI_J|((((uintptr_t)(void *)lj_vm_exit_handler)>>2)&0x03ffffffu);
> -  lua_assert(((uintptr_t)mxp ^ (uintptr_t)(void *)lj_vm_exit_handler)>>28 == 0);
> +  lj_assertA(((uintptr_t)mxp ^ (uintptr_t)(void *)lj_vm_exit_handler)>>28 == 0,
> +	     "branch target out of range");
>     *--mxp = MIPSI_SW|MIPSF_T(RID_TMP)|MIPSF_S(RID_SP)|0;
>     as->mctop = mxp;
>   }
> @@ -195,20 +196,20 @@ static void asm_fusexref(ASMState *as, MIPSIns mi, Reg rt, IRRef ref,
>     if (ra_noreg(ir->r) && canfuse(as, ir)) {
>       if (ir->o == IR_ADD) {
>         intptr_t ofs2;
> -      if (irref_isk(ir->op2) && (ofs2 = ofs + get_kval(IR(ir->op2)),
> +      if (irref_isk(ir->op2) && (ofs2 = ofs + get_kval(as, ir->op2),
>   				 checki16(ofs2))) {
>   	ref = ir->op1;
>   	ofs = (int32_t)ofs2;
>         }
>       } else if (ir->o == IR_STRREF) {
>         intptr_t ofs2 = 65536;
> -      lua_assert(ofs == 0);
> +      lj_assertA(ofs == 0, "bad usage");
>         ofs = (int32_t)sizeof(GCstr);
>         if (irref_isk(ir->op2)) {
> -	ofs2 = ofs + get_kval(IR(ir->op2));
> +	ofs2 = ofs + get_kval(as, ir->op2);
>   	ref = ir->op1;
>         } else if (irref_isk(ir->op1)) {
> -	ofs2 = ofs + get_kval(IR(ir->op1));
> +	ofs2 = ofs + get_kval(as, ir->op1);
>   	ref = ir->op2;
>         }
>         if (!checki16(ofs2)) {
> @@ -252,7 +253,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #if !LJ_SOFTFP
>         if (irt_isfp(ir->t) && fpr <= REGARG_LASTFPR &&
>   	  !(ci->flags & CCI_VARARG)) {
> -	lua_assert(rset_test(as->freeset, fpr));  /* Already evicted. */
> +	lj_assertA(rset_test(as->freeset, fpr),
> +		   "reg %d not free", fpr);  /* Already evicted. */
>   	ra_leftov(as, fpr, ref);
>   	fpr += LJ_32 ? 2 : 1;
>   	gpr += (LJ_32 && irt_isnum(ir->t)) ? 2 : 1;
> @@ -264,7 +266,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #endif
>   	if (LJ_32 && irt_isnum(ir->t)) gpr = (gpr+1) & ~1;
>   	if (gpr <= REGARG_LASTGPR) {
> -	  lua_assert(rset_test(as->freeset, gpr));  /* Already evicted. */
> +	  lj_assertA(rset_test(as->freeset, gpr),
> +		     "reg %d not free", gpr);  /* Already evicted. */
>   #if !LJ_SOFTFP
>   	  if (irt_isfp(ir->t)) {
>   	    RegSet of = as->freeset;
> @@ -277,7 +280,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #if LJ_32
>   	      emit_tg(as, MIPSI_MFC1, gpr+(LJ_BE?0:1), r+1);
>   	      emit_tg(as, MIPSI_MFC1, gpr+(LJ_BE?1:0), r);
> -	      lua_assert(rset_test(as->freeset, gpr+1));  /* Already evicted. */
> +	      lj_assertA(rset_test(as->freeset, gpr+1),
> +			 "reg %d not free", gpr+1);  /* Already evicted. */
>   	      gpr += 2;
>   #else
>   	      emit_tg(as, MIPSI_DMFC1, gpr, r);
> @@ -347,7 +351,7 @@ static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
>   #endif
>     ra_evictset(as, drop);  /* Evictions must be performed first. */
>     if (ra_used(ir)) {
> -    lua_assert(!irt_ispri(ir->t));
> +    lj_assertA(!irt_ispri(ir->t), "PRI dest");
>       if (!LJ_SOFTFP && irt_isfp(ir->t)) {
>         if ((ci->flags & CCI_CASTU64)) {
>   	int32_t ofs = sps_scale(ir->s);
> @@ -395,7 +399,7 @@ static void asm_callx(ASMState *as, IRIns *ir)
>     func = ir->op2; irf = IR(func);
>     if (irf->o == IR_CARG) { func = irf->op1; irf = IR(func); }
>     if (irref_isk(func)) {  /* Call to constant address. */
> -    ci.func = (ASMFunction)(void *)get_kval(irf);
> +    ci.func = (ASMFunction)(void *)get_kval(as, func);
>     } else {  /* Need specific register for indirect calls. */
>       Reg r = ra_alloc1(as, func, RID2RSET(RID_CFUNCADDR));
>       MCode *p = as->mcp;
> @@ -512,15 +516,19 @@ static void asm_conv(ASMState *as, IRIns *ir)
>   #endif
>     IRRef lref = ir->op1;
>   #if LJ_32
> -  lua_assert(!(irt_isint64(ir->t) ||
> -	       (st == IRT_I64 || st == IRT_U64))); /* Handled by SPLIT. */
> +  /* 64 bit integer conversions are handled by SPLIT. */
> +  lj_assertA(!(irt_isint64(ir->t) || (st == IRT_I64 || st == IRT_U64)),
> +	     "IR %04d has unsplit 64 bit type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>   #endif
>   #if LJ_SOFTFP32
>     /* FP conversions are handled by SPLIT. */
> -  lua_assert(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT));
> +  lj_assertA(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT),
> +	     "IR %04d has FP type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>     /* Can't check for same types: SPLIT uses CONV int.int + BXOR for sfp NEG. */
>   #else
> -  lua_assert(irt_type(ir->t) != st);
> +  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
>   #if !LJ_SOFTFP
>     if (irt_isfp(ir->t)) {
>       Reg dest = ra_dest(as, ir, RSET_FPR);
> @@ -579,7 +587,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
>       } else {
>         Reg dest = ra_dest(as, ir, RSET_GPR);
> @@ -679,7 +688,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, RID_NONE);
>       } else {
>         IRCallID cid = irt_is64(ir->t) ?
> @@ -698,7 +708,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>       Reg dest = ra_dest(as, ir, RSET_GPR);
>       if (st >= IRT_I8 && st <= IRT_U16) {  /* Extend to 32 bit integer. */
>         Reg left = ra_alloc1(as, ir->op1, RSET_GPR);
> -      lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
> +      lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
>         if ((ir->op2 & IRCONV_SEXT)) {
>   	if (LJ_64 || (as->flags & JIT_F_MIPSXXR2)) {
>   	  emit_dst(as, st == IRT_I8 ? MIPSI_SEB : MIPSI_SEH, dest, 0, left);
> @@ -795,7 +805,8 @@ static void asm_tvstore64(ASMState *as, Reg base, int32_t ofs, IRRef ref)
>   {
>     RegSet allow = rset_exclude(RSET_GPR, base);
>     IRIns *ir = IR(ref);
> -  lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
> +  lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t),
> +	     "store of IR type %d", irt_type(ir->t));
>     if (irref_isk(ref)) {
>       TValue k;
>       lj_ir_kvalue(as->J->L, &k, ir);
> @@ -944,7 +955,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>         if (isk && irt_isaddr(kt)) {
>   	k = ((int64_t)irt_toitype(irkey->t) << 47) | irkey[1].tv.u64;
>         } else {
> -	lua_assert(irt_ispri(kt) && !irt_isnil(kt));
> +	lj_assertA(irt_ispri(kt) && !irt_isnil(kt), "bad HREF key type");
>   	k = ~((int64_t)~irt_toitype(ir->t) << 47);
>         }
>         cmp64 = ra_allock(as, k, allow);
> @@ -1012,7 +1023,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>   #endif
>   
>     /* Load main position relative to tab->node into dest. */
> -  khash = isk ? ir_khash(irkey) : 1;
> +  khash = isk ? ir_khash(as, irkey) : 1;
>     if (khash == 0) {
>       emit_tsi(as, MIPSI_AL, dest, tab, (int32_t)offsetof(GCtab, node));
>     } else {
> @@ -1020,7 +1031,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>       if (isk)
>         tmphash = ra_allock(as, khash, allow);
>       emit_dst(as, MIPSI_AADDU, dest, dest, tmp1);
> -    lua_assert(sizeof(Node) == 24);
> +    lj_assertA(sizeof(Node) == 24, "bad Node size");
>       emit_dst(as, MIPSI_SUBU, tmp1, tmp2, tmp1);
>       emit_dta(as, MIPSI_SLL, tmp1, tmp1, 3);
>       emit_dta(as, MIPSI_SLL, tmp2, tmp1, 5);
> @@ -1098,7 +1109,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>     Reg key = ra_scratch(as, allow);
>     int64_t k;
>   #endif
> -  lua_assert(ofs % sizeof(Node) == 0);
> +  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
>     if (ofs > 32736) {
>       idx = dest;
>       rset_clear(allow, dest);
> @@ -1127,7 +1138,7 @@ nolo:
>     emit_tsi(as, MIPSI_LW, type, idx, kofs+(LJ_BE?0:4));
>   #else
>     if (irt_ispri(irkey->t)) {
> -    lua_assert(!irt_isnil(irkey->t));
> +    lj_assertA(!irt_isnil(irkey->t), "bad HREFK key type");
>       k = ~((int64_t)~irt_toitype(irkey->t) << 47);
>     } else if (irt_isnum(irkey->t)) {
>       k = (int64_t)ir_knum(irkey)->u64;
> @@ -1166,7 +1177,7 @@ static void asm_uref(ASMState *as, IRIns *ir)
>   static void asm_fref(ASMState *as, IRIns *ir)
>   {
>     UNUSED(as); UNUSED(ir);
> -  lua_assert(!ra_used(ir));
> +  lj_assertA(!ra_used(ir), "unfused FREF");
>   }
>   
>   static void asm_strref(ASMState *as, IRIns *ir)
> @@ -1221,14 +1232,17 @@ static void asm_strref(ASMState *as, IRIns *ir)
>   
>   /* -- Loads and stores ---------------------------------------------------- */
>   
> -static MIPSIns asm_fxloadins(IRIns *ir)
> +static MIPSIns asm_fxloadins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: return MIPSI_LB;
>     case IRT_U8: return MIPSI_LBU;
>     case IRT_I16: return MIPSI_LH;
>     case IRT_U16: return MIPSI_LHU;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP32); if (!LJ_SOFTFP) return MIPSI_LDC1;
> +  case IRT_NUM:
> +    lj_assertA(!LJ_SOFTFP32, "unsplit FP op");
> +    if (!LJ_SOFTFP) return MIPSI_LDC1;
>     /* fallthrough */
>     case IRT_FLOAT: if (!LJ_SOFTFP) return MIPSI_LWC1;
>     /* fallthrough */
> @@ -1236,12 +1250,15 @@ static MIPSIns asm_fxloadins(IRIns *ir)
>     }
>   }
>   
> -static MIPSIns asm_fxstoreins(IRIns *ir)
> +static MIPSIns asm_fxstoreins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: case IRT_U8: return MIPSI_SB;
>     case IRT_I16: case IRT_U16: return MIPSI_SH;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP32); if (!LJ_SOFTFP) return MIPSI_SDC1;
> +  case IRT_NUM:
> +    lj_assertA(!LJ_SOFTFP32, "unsplit FP op");
> +    if (!LJ_SOFTFP) return MIPSI_SDC1;
>     /* fallthrough */
>     case IRT_FLOAT: if (!LJ_SOFTFP) return MIPSI_SWC1;
>     /* fallthrough */
> @@ -1252,10 +1269,10 @@ static MIPSIns asm_fxstoreins(IRIns *ir)
>   static void asm_fload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir, RSET_GPR);
> -  MIPSIns mi = asm_fxloadins(ir);
> +  MIPSIns mi = asm_fxloadins(as, ir);
>     Reg idx;
>     int32_t ofs;
> -  if (ir->op1 == REF_NIL) {
> +  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
>       idx = RID_JGL;
>       ofs = (ir->op2 << 2) - 32768 - GG_OFS(g);
>     } else {
> @@ -1269,7 +1286,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
>       }
>       ofs = field_ofs[ir->op2];
>     }
> -  lua_assert(!irt_isfp(ir->t));
> +  lj_assertA(!irt_isfp(ir->t), "bad FP FLOAD");
>     emit_tsi(as, mi, dest, idx, ofs);
>   }
>   
> @@ -1280,8 +1297,8 @@ static void asm_fstore(ASMState *as, IRIns *ir)
>       IRIns *irf = IR(ir->op1);
>       Reg idx = ra_alloc1(as, irf->op1, rset_exclude(RSET_GPR, src));
>       int32_t ofs = field_ofs[irf->op2];
> -    MIPSIns mi = asm_fxstoreins(ir);
> -    lua_assert(!irt_isfp(ir->t));
> +    MIPSIns mi = asm_fxstoreins(as, ir);
> +    lj_assertA(!irt_isfp(ir->t), "bad FP FSTORE");
>       emit_tsi(as, mi, src, idx, ofs);
>     }
>   }
> @@ -1290,8 +1307,9 @@ static void asm_xload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir,
>       (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -  lua_assert(LJ_TARGET_UNALIGNED || !(ir->op2 & IRXLOAD_UNALIGNED));
> -  asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR, 0);
> +  lj_assertA(LJ_TARGET_UNALIGNED || !(ir->op2 & IRXLOAD_UNALIGNED),
> +	     "unaligned XLOAD");
> +  asm_fusexref(as, asm_fxloadins(as, ir), dest, ir->op1, RSET_GPR, 0);
>   }
>   
>   static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
> @@ -1299,7 +1317,7 @@ static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
>     if (ir->r != RID_SINK) {
>       Reg src = ra_alloc1z(as, ir->op2,
>         (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -    asm_fusexref(as, asm_fxstoreins(ir), src, ir->op1,
> +    asm_fusexref(as, asm_fxstoreins(as, ir), src, ir->op1,
>   		 rset_exclude(RSET_GPR, src), ofs);
>     }
>   }
> @@ -1321,8 +1339,9 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>       }
>     }
>     if (ra_used(ir)) {
> -    lua_assert((LJ_SOFTFP32 ? 0 : irt_isnum(ir->t)) ||
> -	       irt_isint(ir->t) || irt_isaddr(ir->t));
> +    lj_assertA((LJ_SOFTFP32 ? 0 : irt_isnum(ir->t)) ||
> +	       irt_isint(ir->t) || irt_isaddr(ir->t),
> +	       "bad load type %d", irt_type(ir->t));
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && irt_isnum(t)) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
>   #if LJ_64
> @@ -1427,10 +1446,13 @@ static void asm_sload(ASMState *as, IRIns *ir)
>   #else
>     int32_t ofs = 8*((int32_t)ir->op1-2);
>   #endif
> -  lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
> -  lua_assert(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK));
> +  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
> +	     "bad parent SLOAD");  /* Handled by asm_head_side(). */
> +  lj_assertA(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK),
> +	     "inconsistent SLOAD variant");
>   #if LJ_SOFTFP32
> -  lua_assert(!(ir->op2 & IRSLOAD_CONVERT));  /* Handled by LJ_SOFTFP SPLIT. */
> +  lj_assertA(!(ir->op2 & IRSLOAD_CONVERT),
> +	     "unsplit SLOAD convert");  /* Handled by LJ_SOFTFP SPLIT. */
>     if (hiop && ra_used(ir+1)) {
>       type = ra_dest(as, ir+1, allow);
>       rset_clear(allow, type);
> @@ -1443,8 +1465,9 @@ static void asm_sload(ASMState *as, IRIns *ir)
>     } else
>   #endif
>     if (ra_used(ir)) {
> -    lua_assert((LJ_SOFTFP32 ? 0 : irt_isnum(ir->t)) ||
> -	       irt_isint(ir->t) || irt_isaddr(ir->t));
> +    lj_assertA((LJ_SOFTFP32 ? 0 : irt_isnum(ir->t)) ||
> +	       irt_isint(ir->t) || irt_isaddr(ir->t),
> +	       "bad SLOAD type %d", irt_type(ir->t));
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && irt_isnum(t)) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
>       base = ra_alloc1(as, REF_BASE, allow);
> @@ -1556,7 +1579,8 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
>     RegSet drop = RSET_SCRATCH;
>     Reg tmp;
> -  lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
> +  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
> +	     "bad CNEW/CNEWI operands");
>   
>     as->gcsteps++;
>     if (ra_hasreg(ir->r))
> @@ -1571,7 +1595,7 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>       int32_t ofs = sizeof(GCcdata);
>       if (sz == 8) {
>         ofs += 4;
> -      lua_assert((ir+1)->o == IR_HIOP);
> +      lj_assertA((ir+1)->o == IR_HIOP, "expected HIOP for CNEWI");
>         if (LJ_LE) ir++;
>       }
>       for (;;) {
> @@ -1585,7 +1609,7 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>       emit_tsi(as, sz == 8 ? MIPSI_SD : MIPSI_SW, ra_alloc1(as, ir->op2, allow),
>   	     RID_RET, sizeof(GCcdata));
>   #endif
> -    lua_assert(sz == 4 || sz == 8);
> +    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
>     } else if (ir->op2 != REF_NIL) {  /* Create VLA/VLS/aligned cdata. */
>       ci = &lj_ir_callinfo[IRCALL_lj_cdata_newv];
>       args[0] = ASMREF_L;     /* lua_State *L */
> @@ -1640,7 +1664,7 @@ static void asm_obar(ASMState *as, IRIns *ir)
>     MCLabel l_end;
>     Reg obj, val, tmp;
>     /* No need for other object barriers (yet). */
> -  lua_assert(IR(ir->op1)->o == IR_UREFC);
> +  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
>     ra_evictset(as, RSET_SCRATCH);
>     l_end = emit_label(as);
>     args[0] = ASMREF_TMP1;  /* global_State *g */
> @@ -1715,7 +1739,7 @@ static void asm_add(ASMState *as, IRIns *ir)
>       Reg dest = ra_dest(as, ir, RSET_GPR);
>       Reg right, left = ra_hintalloc(as, ir->op1, dest, RSET_GPR);
>       if (irref_isk(ir->op2)) {
> -      intptr_t k = get_kval(IR(ir->op2));
> +      intptr_t k = get_kval(as, ir->op2);
>         if (checki16(k)) {
>   	emit_tsi(as, (LJ_64 && irt_is64(t)) ? MIPSI_DADDIU : MIPSI_ADDIU, dest,
>   		 left, k);
> @@ -1816,7 +1840,7 @@ static void asm_arithov(ASMState *as, IRIns *ir)
>   {
>     /* TODO MIPSR6: bovc/bnvc. Caveat: no delay slot to load RID_TMP. */
>     Reg right, left, tmp, dest = ra_dest(as, ir, RSET_GPR);
> -  lua_assert(!irt_is64(ir->t));
> +  lj_assertA(!irt_is64(ir->t), "bad usage");
>     if (irref_isk(ir->op2)) {
>       int k = IR(ir->op2)->i;
>       if (ir->o == IR_SUBOV) k = -k;
> @@ -2003,7 +2027,7 @@ static void asm_bitop(ASMState *as, IRIns *ir, MIPSIns mi, MIPSIns mik)
>     Reg dest = ra_dest(as, ir, RSET_GPR);
>     Reg right, left = ra_hintalloc(as, ir->op1, dest, RSET_GPR);
>     if (irref_isk(ir->op2)) {
> -    intptr_t k = get_kval(IR(ir->op2));
> +    intptr_t k = get_kval(as, ir->op2);
>       if (checku16(k)) {
>         emit_tsi(as, mik, dest, left, k);
>         return;
> @@ -2036,7 +2060,7 @@ static void asm_bitshift(ASMState *as, IRIns *ir, MIPSIns mi, MIPSIns mik)
>   #define asm_bshl(as, ir)	asm_bitshift(as, ir, MIPSI_SLLV, MIPSI_SLL)
>   #define asm_bshr(as, ir)	asm_bitshift(as, ir, MIPSI_SRLV, MIPSI_SRL)
>   #define asm_bsar(as, ir)	asm_bitshift(as, ir, MIPSI_SRAV, MIPSI_SRA)
> -#define asm_brol(as, ir)	lua_assert(0)
> +#define asm_brol(as, ir)	lj_assertA(0, "unexpected BROL")
>   
>   static void asm_bror(ASMState *as, IRIns *ir)
>   {
> @@ -2228,13 +2252,13 @@ static void asm_comp(ASMState *as, IRIns *ir)
>     } else {
>       Reg right, left = ra_alloc1(as, ir->op1, RSET_GPR);
>       if (op == IR_ABC) op = IR_UGT;
> -    if ((op&4) == 0 && irref_isk(ir->op2) && get_kval(IR(ir->op2)) == 0) {
> +    if ((op&4) == 0 && irref_isk(ir->op2) && get_kval(as, ir->op2) == 0) {
>         MIPSIns mi = (op&2) ? ((op&1) ? MIPSI_BLEZ : MIPSI_BGTZ) :
>   			    ((op&1) ? MIPSI_BLTZ : MIPSI_BGEZ);
>         asm_guard(as, mi, left, 0);
>       } else {
>         if (irref_isk(ir->op2)) {
> -	intptr_t k = get_kval(IR(ir->op2));
> +	intptr_t k = get_kval(as, ir->op2);
>   	if ((op&2)) k++;
>   	if (checki16(k)) {
>   	  asm_guard(as, (op&1) ? MIPSI_BNE : MIPSI_BEQ, RID_TMP, RID_ZERO);
> @@ -2390,10 +2414,11 @@ static void asm_hiop(ASMState *as, IRIns *ir)
>     case IR_CNEWI:
>       /* Nothing to do here. Handled by lo op itself. */
>       break;
> -  default: lua_assert(0); break;
> +  default: lj_assertA(0, "bad HIOP for op %d", (ir-1)->o); break;
>     }
>   #else
> -  UNUSED(as); UNUSED(ir); lua_assert(0);  /* Unused without FFI. */
> +  /* Unused on MIPS64 or without SOFTFP or FFI. */
> +  UNUSED(as); UNUSED(ir); lj_assertA(0, "unexpected HIOP");
>   #endif
>   }
>   
> @@ -2462,7 +2487,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>   #if LJ_SOFTFP32
>         Reg tmp;
>         RegSet allow = rset_exclude(RSET_GPR, RID_BASE);
> -      lua_assert(irref_isk(ref));  /* LJ_SOFTFP: must be a number constant. */
> +      /* LJ_SOFTFP: must be a number constant. */
> +      lj_assertA(irref_isk(ref), "unsplit FP op");
>         tmp = ra_allock(as, (int32_t)ir_knum(ir)->u32.lo, allow);
>         emit_tsi(as, MIPSI_SW, tmp, RID_BASE, ofs+(LJ_BE?4:0));
>         if (rset_test(as->freeset, tmp+1)) allow = RID2RSET(tmp+1);
> @@ -2479,7 +2505,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>   #if LJ_32
>         RegSet allow = rset_exclude(RSET_GPR, RID_BASE);
>         Reg type;
> -      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
> +      lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t),
> +		 "restore of IR type %d", irt_type(ir->t));
>         if (!irt_ispri(ir->t)) {
>   	Reg src = ra_alloc1(as, ref, allow);
>   	rset_clear(allow, src);
> @@ -2502,7 +2529,7 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       }
>       checkmclim(as);
>     }
> -  lua_assert(map + nent == flinks);
> +  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
>   }
>   
>   /* -- GC handling --------------------------------------------------------- */
> @@ -2700,7 +2727,7 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>   	}
>         } else if (p+1 == pe) {
>   	/* Patch NOP after code for inverted loop branch. Use of J is ok. */
> -	lua_assert(p[1] == MIPSI_NOP);
> +	lj_assertJ(p[1] == MIPSI_NOP, "expected NOP");
>   	p[1] = tjump;
>   	*p = MIPSI_NOP;  /* Replace the load of the exit number. */
>   	cstop = p+2;
> diff --git a/src/lj_asm_ppc.h b/src/lj_asm_ppc.h
> index 62a5c3e2..971dcc88 100644
> --- a/src/lj_asm_ppc.h
> +++ b/src/lj_asm_ppc.h
> @@ -181,7 +181,7 @@ static void asm_fusexref(ASMState *as, PPCIns pi, Reg rt, IRRef ref,
>   	return;
>         }
>       } else if (ir->o == IR_STRREF) {
> -      lua_assert(ofs == 0);
> +      lj_assertA(ofs == 0, "bad usage");
>         ofs = (int32_t)sizeof(GCstr);
>         if (irref_isk(ir->op2)) {
>   	ofs += IR(ir->op2)->i;
> @@ -268,7 +268,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #if !LJ_SOFTFP
>         if (irt_isfp(ir->t)) {
>   	if (fpr <= REGARG_LASTFPR) {
> -	  lua_assert(rset_test(as->freeset, fpr));  /* Already evicted. */
> +	  lj_assertA(rset_test(as->freeset, fpr),
> +		     "reg %d not free", fpr);  /* Already evicted. */
>   	  ra_leftov(as, fpr, ref);
>   	  fpr++;
>   	} else {
> @@ -281,7 +282,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #endif
>         {
>   	if (gpr <= REGARG_LASTGPR) {
> -	  lua_assert(rset_test(as->freeset, gpr));  /* Already evicted. */
> +	  lj_assertA(rset_test(as->freeset, gpr),
> +		     "reg %d not free", gpr);  /* Already evicted. */
>   	  ra_leftov(as, gpr, ref);
>   	  gpr++;
>   	} else {
> @@ -319,7 +321,7 @@ static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
>       rset_clear(drop, (ir+1)->r);  /* Dest reg handled below. */
>     ra_evictset(as, drop);  /* Evictions must be performed first. */
>     if (ra_used(ir)) {
> -    lua_assert(!irt_ispri(ir->t));
> +    lj_assertA(!irt_ispri(ir->t), "PRI dest");
>       if (!LJ_SOFTFP && irt_isfp(ir->t)) {
>         if ((ci->flags & CCI_CASTU64)) {
>   	/* Use spill slot or temp slots. */
> @@ -431,14 +433,18 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     int stfp = (st == IRT_NUM || st == IRT_FLOAT);
>   #endif
>     IRRef lref = ir->op1;
> -  lua_assert(!(irt_isint64(ir->t) ||
> -	       (st == IRT_I64 || st == IRT_U64))); /* Handled by SPLIT. */
> +  /* 64 bit integer conversions are handled by SPLIT. */
> +  lj_assertA(!(irt_isint64(ir->t) || (st == IRT_I64 || st == IRT_U64)),
> +	     "IR %04d has unsplit 64 bit type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>   #if LJ_SOFTFP
>     /* FP conversions are handled by SPLIT. */
> -  lua_assert(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT));
> +  lj_assertA(!irt_isfp(ir->t) && !(st == IRT_NUM || st == IRT_FLOAT),
> +	     "IR %04d has FP type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>     /* Can't check for same types: SPLIT uses CONV int.int + BXOR for sfp NEG. */
>   #else
> -  lua_assert(irt_type(ir->t) != st);
> +  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
>     if (irt_isfp(ir->t)) {
>       Reg dest = ra_dest(as, ir, RSET_FPR);
>       if (stfp) {  /* FP to FP conversion. */
> @@ -467,7 +473,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
>       } else {
>         Reg dest = ra_dest(as, ir, RSET_GPR);
> @@ -503,7 +510,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>       Reg dest = ra_dest(as, ir, RSET_GPR);
>       if (st >= IRT_I8 && st <= IRT_U16) {  /* Extend to 32 bit integer. */
>         Reg left = ra_alloc1(as, ir->op1, RSET_GPR);
> -      lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
> +      lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
>         if ((ir->op2 & IRCONV_SEXT))
>   	emit_as(as, st == IRT_I8 ? PPCI_EXTSB : PPCI_EXTSH, dest, left);
>         else
> @@ -699,7 +706,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>   	    (((char *)as->mcp-(char *)l_loop) & 0xffffu);
>   
>     /* Load main position relative to tab->node into dest. */
> -  khash = isk ? ir_khash(irkey) : 1;
> +  khash = isk ? ir_khash(as, irkey) : 1;
>     if (khash == 0) {
>       emit_tai(as, PPCI_LWZ, dest, tab, (int32_t)offsetof(GCtab, node));
>     } else {
> @@ -754,7 +761,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>     Reg node = ra_alloc1(as, ir->op1, RSET_GPR);
>     Reg key = RID_NONE, type = RID_TMP, idx = node;
>     RegSet allow = rset_exclude(RSET_GPR, node);
> -  lua_assert(ofs % sizeof(Node) == 0);
> +  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
>     if (ofs > 32736) {
>       idx = dest;
>       rset_clear(allow, dest);
> @@ -813,7 +820,7 @@ static void asm_uref(ASMState *as, IRIns *ir)
>   static void asm_fref(ASMState *as, IRIns *ir)
>   {
>     UNUSED(as); UNUSED(ir);
> -  lua_assert(!ra_used(ir));
> +  lj_assertA(!ra_used(ir), "unfused FREF");
>   }
>   
>   static void asm_strref(ASMState *as, IRIns *ir)
> @@ -853,25 +860,27 @@ static void asm_strref(ASMState *as, IRIns *ir)
>   
>   /* -- Loads and stores ---------------------------------------------------- */
>   
> -static PPCIns asm_fxloadins(IRIns *ir)
> +static PPCIns asm_fxloadins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: return PPCI_LBZ;  /* Needs sign-extension. */
>     case IRT_U8: return PPCI_LBZ;
>     case IRT_I16: return PPCI_LHA;
>     case IRT_U16: return PPCI_LHZ;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP); return PPCI_LFD;
> +  case IRT_NUM: lj_assertA(!LJ_SOFTFP, "unsplit FP op"); return PPCI_LFD;
>     case IRT_FLOAT: if (!LJ_SOFTFP) return PPCI_LFS;
>     default: return PPCI_LWZ;
>     }
>   }
>   
> -static PPCIns asm_fxstoreins(IRIns *ir)
> +static PPCIns asm_fxstoreins(ASMState *as, IRIns *ir)
>   {
> +  UNUSED(as);
>     switch (irt_type(ir->t)) {
>     case IRT_I8: case IRT_U8: return PPCI_STB;
>     case IRT_I16: case IRT_U16: return PPCI_STH;
> -  case IRT_NUM: lua_assert(!LJ_SOFTFP); return PPCI_STFD;
> +  case IRT_NUM: lj_assertA(!LJ_SOFTFP, "unsplit FP op"); return PPCI_STFD;
>     case IRT_FLOAT: if (!LJ_SOFTFP) return PPCI_STFS;
>     default: return PPCI_STW;
>     }
> @@ -880,10 +889,10 @@ static PPCIns asm_fxstoreins(IRIns *ir)
>   static void asm_fload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir, RSET_GPR);
> -  PPCIns pi = asm_fxloadins(ir);
> +  PPCIns pi = asm_fxloadins(as, ir);
>     Reg idx;
>     int32_t ofs;
> -  if (ir->op1 == REF_NIL) {
> +  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
>       idx = RID_JGL;
>       ofs = (ir->op2 << 2) - 32768;
>     } else {
> @@ -897,7 +906,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
>       }
>       ofs = field_ofs[ir->op2];
>     }
> -  lua_assert(!irt_isi8(ir->t));
> +  lj_assertA(!irt_isi8(ir->t), "unsupported FLOAD I8");
>     emit_tai(as, pi, dest, idx, ofs);
>   }
>   
> @@ -908,7 +917,7 @@ static void asm_fstore(ASMState *as, IRIns *ir)
>       IRIns *irf = IR(ir->op1);
>       Reg idx = ra_alloc1(as, irf->op1, rset_exclude(RSET_GPR, src));
>       int32_t ofs = field_ofs[irf->op2];
> -    PPCIns pi = asm_fxstoreins(ir);
> +    PPCIns pi = asm_fxstoreins(as, ir);
>       emit_tai(as, pi, src, idx, ofs);
>     }
>   }
> @@ -917,10 +926,10 @@ static void asm_xload(ASMState *as, IRIns *ir)
>   {
>     Reg dest = ra_dest(as, ir,
>       (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -  lua_assert(!(ir->op2 & IRXLOAD_UNALIGNED));
> +  lj_assertA(!(ir->op2 & IRXLOAD_UNALIGNED), "unaligned XLOAD");
>     if (irt_isi8(ir->t))
>       emit_as(as, PPCI_EXTSB, dest, dest);
> -  asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR, 0);
> +  asm_fusexref(as, asm_fxloadins(as, ir), dest, ir->op1, RSET_GPR, 0);
>   }
>   
>   static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
> @@ -936,7 +945,7 @@ static void asm_xstore_(ASMState *as, IRIns *ir, int32_t ofs)
>     } else {
>       Reg src = ra_alloc1(as, ir->op2,
>         (!LJ_SOFTFP && irt_isfp(ir->t)) ? RSET_FPR : RSET_GPR);
> -    asm_fusexref(as, asm_fxstoreins(ir), src, ir->op1,
> +    asm_fusexref(as, asm_fxstoreins(as, ir), src, ir->op1,
>   		 rset_exclude(RSET_GPR, src), ofs);
>     }
>   }
> @@ -958,8 +967,9 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>       ofs = 0;
>     }
>     if (ra_used(ir)) {
> -    lua_assert((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> -	       irt_isint(ir->t) || irt_isaddr(ir->t));
> +    lj_assertA((LJ_SOFTFP ? 0 : irt_isnum(ir->t)) ||
> +	       irt_isint(ir->t) || irt_isaddr(ir->t),
> +	       "bad load type %d", irt_type(ir->t));
>       if (LJ_SOFTFP || !irt_isnum(t)) ofs = 0;
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && irt_isnum(t)) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
> @@ -1042,12 +1052,16 @@ static void asm_sload(ASMState *as, IRIns *ir)
>     int hiop = (LJ_SOFTFP && (ir+1)->o == IR_HIOP);
>     if (hiop)
>       t.irt = IRT_NUM;
> -  lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
> -  lua_assert(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK));
> -  lua_assert(LJ_DUALNUM ||
> -	     !irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)));
> +  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
> +	     "bad parent SLOAD");  /* Handled by asm_head_side(). */
> +  lj_assertA(irt_isguard(ir->t) || !(ir->op2 & IRSLOAD_TYPECHECK),
> +	     "inconsistent SLOAD variant");
> +  lj_assertA(LJ_DUALNUM ||
> +	     !irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)),
> +	     "bad SLOAD type");
>   #if LJ_SOFTFP
> -  lua_assert(!(ir->op2 & IRSLOAD_CONVERT));  /* Handled by LJ_SOFTFP SPLIT. */
> +  lj_assertA(!(ir->op2 & IRSLOAD_CONVERT),
> +	     "unsplit SLOAD convert");  /* Handled by LJ_SOFTFP SPLIT. */
>     if (hiop && ra_used(ir+1)) {
>       type = ra_dest(as, ir+1, allow);
>       rset_clear(allow, type);
> @@ -1060,7 +1074,8 @@ static void asm_sload(ASMState *as, IRIns *ir)
>     } else
>   #endif
>     if (ra_used(ir)) {
> -    lua_assert(irt_isnum(t) || irt_isint(t) || irt_isaddr(t));
> +    lj_assertA(irt_isnum(t) || irt_isint(t) || irt_isaddr(t),
> +	       "bad SLOAD type %d", irt_type(ir->t));
>       dest = ra_dest(as, ir, (!LJ_SOFTFP && irt_isnum(t)) ? RSET_FPR : allow);
>       rset_clear(allow, dest);
>       base = ra_alloc1(as, REF_BASE, allow);
> @@ -1127,7 +1142,8 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_mem_newgco];
>     IRRef args[4];
>     RegSet drop = RSET_SCRATCH;
> -  lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
> +  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
> +	     "bad CNEW/CNEWI operands");
>   
>     as->gcsteps++;
>     if (ra_hasreg(ir->r))
> @@ -1140,10 +1156,10 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     if (ir->o == IR_CNEWI) {
>       RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
>       int32_t ofs = sizeof(GCcdata);
> -    lua_assert(sz == 4 || sz == 8);
> +    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
>       if (sz == 8) {
>         ofs += 4;
> -      lua_assert((ir+1)->o == IR_HIOP);
> +      lj_assertA((ir+1)->o == IR_HIOP, "expected HIOP for CNEWI");
>       }
>       for (;;) {
>         Reg r = ra_alloc1(as, ir->op2, allow);
> @@ -1190,7 +1206,7 @@ static void asm_tbar(ASMState *as, IRIns *ir)
>     emit_tai(as, PPCI_STW, link, tab, (int32_t)offsetof(GCtab, gclist));
>     emit_tai(as, PPCI_STB, mark, tab, (int32_t)offsetof(GCtab, marked));
>     emit_setgl(as, tab, gc.grayagain);
> -  lua_assert(LJ_GC_BLACK == 0x04);
> +  lj_assertA(LJ_GC_BLACK == 0x04, "bad LJ_GC_BLACK");
>     emit_rot(as, PPCI_RLWINM, mark, mark, 0, 30, 28);  /* Clear black bit. */
>     emit_getgl(as, link, gc.grayagain);
>     emit_condbranch(as, PPCI_BC|PPCF_Y, CC_EQ, l_end);
> @@ -1205,7 +1221,7 @@ static void asm_obar(ASMState *as, IRIns *ir)
>     MCLabel l_end;
>     Reg obj, val, tmp;
>     /* No need for other object barriers (yet). */
> -  lua_assert(IR(ir->op1)->o == IR_UREFC);
> +  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
>     ra_evictset(as, RSET_SCRATCH);
>     l_end = emit_label(as);
>     args[0] = ASMREF_TMP1;  /* global_State *g */
> @@ -1676,7 +1692,7 @@ static void asm_bitshift(ASMState *as, IRIns *ir, PPCIns pi, PPCIns pik)
>   #define asm_brol(as, ir) \
>     asm_bitshift(as, ir, PPCI_RLWNM|PPCF_MB(0)|PPCF_ME(31), \
>   		       PPCI_RLWINM|PPCF_MB(0)|PPCF_ME(31))
> -#define asm_bror(as, ir)	lua_assert(0)
> +#define asm_bror(as, ir)	lj_assertA(0, "unexpected BROR")
>   
>   #if LJ_SOFTFP
>   static void asm_sfpmin_max(ASMState *as, IRIns *ir)
> @@ -1951,10 +1967,11 @@ static void asm_hiop(ASMState *as, IRIns *ir)
>     case IR_CNEWI:
>       /* Nothing to do here. Handled by lo op itself. */
>       break;
> -  default: lua_assert(0); break;
> +  default: lj_assertA(0, "bad HIOP for op %d", (ir-1)->o); break;
>     }
>   #else
> -  UNUSED(as); UNUSED(ir); lua_assert(0);  /* Unused without FFI. */
> +  /* Unused without SOFTFP or FFI. */
> +  UNUSED(as); UNUSED(ir); lj_assertA(0, "unexpected HIOP");
>   #endif
>   }
>   
> @@ -2014,7 +2031,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>   #if LJ_SOFTFP
>         Reg tmp;
>         RegSet allow = rset_exclude(RSET_GPR, RID_BASE);
> -      lua_assert(irref_isk(ref));  /* LJ_SOFTFP: must be a number constant. */
> +      /* LJ_SOFTFP: must be a number constant. */
> +      lj_assertA(irref_isk(ref), "unsplit FP op");
>         tmp = ra_allock(as, (int32_t)ir_knum(ir)->u32.lo, allow);
>         emit_tai(as, PPCI_STW, tmp, RID_BASE, ofs+(LJ_BE?4:0));
>         if (rset_test(as->freeset, tmp+1)) allow = RID2RSET(tmp+1);
> @@ -2027,7 +2045,8 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       } else {
>         Reg type;
>         RegSet allow = rset_exclude(RSET_GPR, RID_BASE);
> -      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t));
> +      lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) || irt_isinteger(ir->t),
> +		 "restore of IR type %d", irt_type(ir->t));
>         if (!irt_ispri(ir->t)) {
>   	Reg src = ra_alloc1(as, ref, allow);
>   	rset_clear(allow, src);
> @@ -2047,7 +2066,7 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       }
>       checkmclim(as);
>     }
> -  lua_assert(map + nent == flinks);
> +  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
>   }
>   
>   /* -- GC handling --------------------------------------------------------- */
> @@ -2145,7 +2164,7 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
>       as->mctop = p;
>     } else {
>       /* Patch stack adjustment. */
> -    lua_assert(checki16(CFRAME_SIZE+spadj));
> +    lj_assertA(checki16(CFRAME_SIZE+spadj), "stack adjustment out of range");
>       p[-3] = PPCI_ADDI | PPCF_T(RID_TMP) | PPCF_A(RID_SP) | (CFRAME_SIZE+spadj);
>       p[-2] = PPCI_STWU | PPCF_T(RID_TMP) | PPCF_A(RID_SP) | spadj;
>     }
> @@ -2222,14 +2241,16 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>       } else if ((ins & 0xfc000000u) == PPCI_B &&
>   	       ((ins ^ ((char *)px-(char *)p)) & 0x03ffffffu) == 0) {
>         ptrdiff_t delta = (char *)target - (char *)p;
> -      lua_assert(((delta + 0x02000000) >> 26) == 0);
> +      lj_assertJ(((delta + 0x02000000) >> 26) == 0,
> +		 "branch target out of range");
>         *p = PPCI_B | ((uint32_t)delta & 0x03ffffffu);
>         if (!cstart) cstart = p;
>       }
>     }
>     {  /* Always patch long-range branch in exit stub itself. */
>       ptrdiff_t delta = (char *)target - (char *)px - clearso;
> -    lua_assert(((delta + 0x02000000) >> 26) == 0);
> +    lj_assertJ(((delta + 0x02000000) >> 26) == 0,
> +	       "branch target out of range");
>       *px = PPCI_B | ((uint32_t)delta & 0x03ffffffu);
>     }
>     if (!cstart) cstart = px;
> diff --git a/src/lj_asm_x86.h b/src/lj_asm_x86.h
> index 5f5fe3cf..74f2d853 100644
> --- a/src/lj_asm_x86.h
> +++ b/src/lj_asm_x86.h
> @@ -31,7 +31,7 @@ static MCode *asm_exitstub_gen(ASMState *as, ExitNo group)
>   #endif
>     /* Jump to exit handler which fills in the ExitState. */
>     *mxp++ = XI_JMP; mxp += 4;
> -  *((int32_t *)(mxp-4)) = jmprel(mxp, (MCode *)(void *)lj_vm_exit_handler);
> +  *((int32_t *)(mxp-4)) = jmprel(as->J, mxp, (MCode *)(void *)lj_vm_exit_handler);
>     /* Commit the code for this group (even if assembly fails later on). */
>     lj_mcode_commitbot(as->J, mxp);
>     as->mcbot = mxp;
> @@ -60,7 +60,7 @@ static void asm_guardcc(ASMState *as, int cc)
>     MCode *p = as->mcp;
>     if (LJ_UNLIKELY(p == as->invmcp)) {
>       as->loopinv = 1;
> -    *(int32_t *)(p+1) = jmprel(p+5, target);
> +    *(int32_t *)(p+1) = jmprel(as->J, p+5, target);
>       target = p;
>       cc ^= 1;
>       if (as->realign) {
> @@ -131,7 +131,7 @@ static IRRef asm_fuseabase(ASMState *as, IRRef ref)
>     as->mrm.ofs = 0;
>     if (irb->o == IR_FLOAD) {
>       IRIns *ira = IR(irb->op1);
> -    lua_assert(irb->op2 == IRFL_TAB_ARRAY);
> +    lj_assertA(irb->op2 == IRFL_TAB_ARRAY, "expected FLOAD TAB_ARRAY");
>       /* We can avoid the FLOAD of t->array for colocated arrays. */
>       if (ira->o == IR_TNEW && ira->op1 <= LJ_MAX_COLOSIZE &&
>   	!neverfuse(as) && noconflict(as, irb->op1, IR_NEWREF, 1)) {
> @@ -150,7 +150,7 @@ static IRRef asm_fuseabase(ASMState *as, IRRef ref)
>   static void asm_fusearef(ASMState *as, IRIns *ir, RegSet allow)
>   {
>     IRIns *irx;
> -  lua_assert(ir->o == IR_AREF);
> +  lj_assertA(ir->o == IR_AREF, "expected AREF");
>     as->mrm.base = (uint8_t)ra_alloc1(as, asm_fuseabase(as, ir->op1), allow);
>     irx = IR(ir->op2);
>     if (irref_isk(ir->op2)) {
> @@ -217,8 +217,9 @@ static void asm_fuseahuref(ASMState *as, IRRef ref, RegSet allow)
>         }
>         break;
>       default:
> -      lua_assert(ir->o == IR_HREF || ir->o == IR_NEWREF || ir->o == IR_UREFO ||
> -		 ir->o == IR_KKPTR);
> +      lj_assertA(ir->o == IR_HREF || ir->o == IR_NEWREF || ir->o == IR_UREFO ||
> +		 ir->o == IR_KKPTR,
> +		 "bad IR op %d", ir->o);
>         break;
>       }
>     }
> @@ -230,9 +231,10 @@ static void asm_fuseahuref(ASMState *as, IRRef ref, RegSet allow)
>   /* Fuse FLOAD/FREF reference into memory operand. */
>   static void asm_fusefref(ASMState *as, IRIns *ir, RegSet allow)
>   {
> -  lua_assert(ir->o == IR_FLOAD || ir->o == IR_FREF);
> +  lj_assertA(ir->o == IR_FLOAD || ir->o == IR_FREF,
> +	     "bad IR op %d", ir->o);
>     as->mrm.idx = RID_NONE;
> -  if (ir->op1 == REF_NIL) {
> +  if (ir->op1 == REF_NIL) {  /* FLOAD from GG_State with offset. */
>   #if LJ_GC64
>       as->mrm.ofs = (int32_t)(ir->op2 << 2) - GG_OFS(dispatch);
>       as->mrm.base = RID_DISPATCH;
> @@ -271,7 +273,7 @@ static void asm_fusefref(ASMState *as, IRIns *ir, RegSet allow)
>   static void asm_fusestrref(ASMState *as, IRIns *ir, RegSet allow)
>   {
>     IRIns *irr;
> -  lua_assert(ir->o == IR_STRREF);
> +  lj_assertA(ir->o == IR_STRREF, "bad IR op %d", ir->o);
>     as->mrm.base = as->mrm.idx = RID_NONE;
>     as->mrm.scale = XM_SCALE1;
>     as->mrm.ofs = sizeof(GCstr);
> @@ -378,9 +380,10 @@ static Reg asm_fuseloadk64(ASMState *as, IRIns *ir)
>   	     checki32(mctopofs(as, k)) && checki32(mctopofs(as, k+1))) {
>       as->mrm.ofs = (int32_t)mcpofs(as, k);
>       as->mrm.base = RID_RIP;
> -  } else {
> +  } else {  /* Intern 64 bit constant at bottom of mcode. */
>       if (ir->i) {
> -      lua_assert(*k == *(uint64_t*)(as->mctop - ir->i));
> +      lj_assertA(*k == *(uint64_t*)(as->mctop - ir->i),
> +		 "bad interned 64 bit constant");
>       } else {
>         while ((uintptr_t)as->mcbot & 7) *as->mcbot++ = XI_INT3;
>         *(uint64_t*)as->mcbot = *k;
> @@ -420,12 +423,12 @@ static Reg asm_fuseload(ASMState *as, IRRef ref, RegSet allow)
>     }
>     if (ir->o == IR_KNUM) {
>       RegSet avail = as->freeset & ~as->modset & RSET_FPR;
> -    lua_assert(allow != RSET_EMPTY);
> +    lj_assertA(allow != RSET_EMPTY, "no register allowed");
>       if (!(avail & (avail-1)))  /* Fuse if less than two regs available. */
>         return asm_fuseloadk64(as, ir);
>     } else if (ref == REF_BASE || ir->o == IR_KINT64) {
>       RegSet avail = as->freeset & ~as->modset & RSET_GPR;
> -    lua_assert(allow != RSET_EMPTY);
> +    lj_assertA(allow != RSET_EMPTY, "no register allowed");
>       if (!(avail & (avail-1))) {  /* Fuse if less than two regs available. */
>         if (ref == REF_BASE) {
>   #if LJ_GC64
> @@ -606,7 +609,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   #endif
>   	  emit_loadi(as, r, ir->i);
>         } else {
> -	lua_assert(rset_test(as->freeset, r));  /* Must have been evicted. */
> +	/* Must have been evicted. */
> +	lj_assertA(rset_test(as->freeset, r), "reg %d not free", r);
>   	if (ra_hasreg(ir->r)) {
>   	  ra_noweak(as, ir->r);
>   	  emit_movrr(as, ir, r, ir->r);
> @@ -615,7 +619,8 @@ static void asm_gencall(ASMState *as, const CCallInfo *ci, IRRef *args)
>   	}
>         }
>       } else if (irt_isfp(ir->t)) {  /* FP argument is on stack. */
> -      lua_assert(!(irt_isfloat(ir->t) && irref_isk(ref)));  /* No float k. */
> +      lj_assertA(!(irt_isfloat(ir->t) && irref_isk(ref)),
> +		 "unexpected float constant");
>         if (LJ_32 && (ofs & 4) && irref_isk(ref)) {
>   	/* Split stores for unaligned FP consts. */
>   	emit_movmroi(as, RID_ESP, ofs, (int32_t)ir_knum(ir)->u32.lo);
> @@ -691,7 +696,7 @@ static void asm_setupresult(ASMState *as, IRIns *ir, const CCallInfo *ci)
>         ra_destpair(as, ir);
>   #endif
>       } else {
> -      lua_assert(!irt_ispri(ir->t));
> +      lj_assertA(!irt_ispri(ir->t), "PRI dest");
>         ra_destreg(as, ir, RID_RET);
>       }
>     } else if (LJ_32 && irt_isfp(ir->t) && !(ci->flags & CCI_CASTU64)) {
> @@ -810,8 +815,10 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     int st64 = (st == IRT_I64 || st == IRT_U64 || (LJ_64 && st == IRT_P64));
>     int stfp = (st == IRT_NUM || st == IRT_FLOAT);
>     IRRef lref = ir->op1;
> -  lua_assert(irt_type(ir->t) != st);
> -  lua_assert(!(LJ_32 && (irt_isint64(ir->t) || st64)));  /* Handled by SPLIT. */
> +  lj_assertA(irt_type(ir->t) != st, "inconsistent types for CONV");
> +  lj_assertA(!(LJ_32 && (irt_isint64(ir->t) || st64)),
> +	     "IR %04d has unsplit 64 bit type",
> +	     (int)(ir - as->ir) - REF_BIAS);
>     if (irt_isfp(ir->t)) {
>       Reg dest = ra_dest(as, ir, RSET_FPR);
>       if (stfp) {  /* FP to FP conversion. */
> @@ -847,7 +854,8 @@ static void asm_conv(ASMState *as, IRIns *ir)
>     } else if (stfp) {  /* FP to integer conversion. */
>       if (irt_isguard(ir->t)) {
>         /* Checked conversions are only supported from number to int. */
> -      lua_assert(irt_isint(ir->t) && st == IRT_NUM);
> +      lj_assertA(irt_isint(ir->t) && st == IRT_NUM,
> +		 "bad type for checked CONV");
>         asm_tointg(as, ir, ra_alloc1(as, lref, RSET_FPR));
>       } else {
>         Reg dest = ra_dest(as, ir, RSET_GPR);
> @@ -882,7 +890,7 @@ static void asm_conv(ASMState *as, IRIns *ir)
>       Reg left, dest = ra_dest(as, ir, RSET_GPR);
>       RegSet allow = RSET_GPR;
>       x86Op op;
> -    lua_assert(irt_isint(ir->t) || irt_isu32(ir->t));
> +    lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t), "bad type for CONV EXT");
>       if (st == IRT_I8) {
>         op = XO_MOVSXb; allow = RSET_GPR8; dest |= FORCE_REX;
>       } else if (st == IRT_U8) {
> @@ -953,7 +961,7 @@ static void asm_conv_fp_int64(ASMState *as, IRIns *ir)
>       emit_sjcc(as, CC_NS, l_end);
>       emit_rr(as, XO_TEST, hi, hi);  /* Check if u64 >= 2^63. */
>     } else {
> -    lua_assert(((ir-1)->op2 & IRCONV_SRCMASK) == IRT_I64);
> +    lj_assertA(((ir-1)->op2 & IRCONV_SRCMASK) == IRT_I64, "bad type for CONV");
>     }
>     emit_rmro(as, XO_FILDq, XOg_FILDq, RID_ESP, 0);
>     /* NYI: Avoid narrow-to-wide store-to-load forwarding stall. */
> @@ -967,8 +975,8 @@ static void asm_conv_int64_fp(ASMState *as, IRIns *ir)
>     IRType st = (IRType)((ir-1)->op2 & IRCONV_SRCMASK);
>     IRType dt = (((ir-1)->op2 & IRCONV_DSTMASK) >> IRCONV_DSH);
>     Reg lo, hi;
> -  lua_assert(st == IRT_NUM || st == IRT_FLOAT);
> -  lua_assert(dt == IRT_I64 || dt == IRT_U64);
> +  lj_assertA(st == IRT_NUM || st == IRT_FLOAT, "bad type for CONV");
> +  lj_assertA(dt == IRT_I64 || dt == IRT_U64, "bad type for CONV");
>     hi = ra_dest(as, ir, RSET_GPR);
>     lo = ra_dest(as, ir-1, rset_exclude(RSET_GPR, hi));
>     if (ra_used(ir-1)) emit_rmro(as, XO_MOV, lo, RID_ESP, 0);
> @@ -1180,13 +1188,13 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>         emit_rmro(as, XO_CMP, tmp|REX_64, dest, offsetof(Node, key.u64));
>       }
>     } else {
> -    lua_assert(irt_ispri(kt) && !irt_isnil(kt));
> +    lj_assertA(irt_ispri(kt) && !irt_isnil(kt), "bad HREF key type");
>       emit_u32(as, (irt_toitype(kt)<<15)|0x7fff);
>       emit_rmro(as, XO_ARITHi, XOg_CMP, dest, offsetof(Node, key.it));
>   #else
>     } else {
>       if (!irt_ispri(kt)) {
> -      lua_assert(irt_isaddr(kt));
> +      lj_assertA(irt_isaddr(kt), "bad HREF key type");
>         if (isk)
>   	emit_gmroi(as, XG_ARITHi(XOg_CMP), dest, offsetof(Node, key.gcr),
>   		   ptr2addr(ir_kgc(irkey)));
> @@ -1194,7 +1202,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>   	emit_rmro(as, XO_CMP, key, dest, offsetof(Node, key.gcr));
>         emit_sjcc(as, CC_NE, l_next);
>       }
> -    lua_assert(!irt_isnil(kt));
> +    lj_assertA(!irt_isnil(kt), "bad HREF key type");
>       emit_i8(as, irt_toitype(kt));
>       emit_rmro(as, XO_ARITHi8, XOg_CMP, dest, offsetof(Node, key.it));
>   #endif
> @@ -1209,7 +1217,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
>   #endif
>   
>     /* Load main position relative to tab->node into dest. */
> -  khash = isk ? ir_khash(irkey) : 1;
> +  khash = isk ? ir_khash(as, irkey) : 1;
>     if (khash == 0) {
>       emit_rmro(as, XO_MOV, dest|REX_GC64, tab, offsetof(GCtab, node));
>     } else {
> @@ -1276,7 +1284,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>   #if !LJ_64
>     MCLabel l_exit;
>   #endif
> -  lua_assert(ofs % sizeof(Node) == 0);
> +  lj_assertA(ofs % sizeof(Node) == 0, "unaligned HREFK slot");
>     if (ra_hasreg(dest)) {
>       if (ofs != 0) {
>         if (dest == node && !(as->flags & JIT_F_LEA_AGU))
> @@ -1293,7 +1301,8 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>       Reg key = ra_scratch(as, rset_exclude(RSET_GPR, node));
>       emit_rmro(as, XO_CMP, key|REX_64, node,
>   	       ofs + (int32_t)offsetof(Node, key.u64));
> -    lua_assert(irt_isnum(irkey->t) || irt_isgcv(irkey->t));
> +    lj_assertA(irt_isnum(irkey->t) || irt_isgcv(irkey->t),
> +	       "bad HREFK key type");
>       /* Assumes -0.0 is already canonicalized to +0.0. */
>       emit_loadu64(as, key, irt_isnum(irkey->t) ? ir_knum(irkey)->u64 :
>   #if LJ_GC64
> @@ -1304,7 +1313,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>   			  (uint64_t)(uint32_t)ptr2addr(ir_kgc(irkey)));
>   #endif
>     } else {
> -    lua_assert(!irt_isnil(irkey->t));
> +    lj_assertA(!irt_isnil(irkey->t), "bad HREFK key type");
>   #if LJ_GC64
>       emit_i32(as, (irt_toitype(irkey->t)<<15)|0x7fff);
>       emit_rmro(as, XO_ARITHi, XOg_CMP, node,
> @@ -1328,13 +1337,13 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
>   	       (int32_t)ir_knum(irkey)->u32.hi);
>     } else {
>       if (!irt_ispri(irkey->t)) {
> -      lua_assert(irt_isgcv(irkey->t));
> +      lj_assertA(irt_isgcv(irkey->t), "bad HREFK key type");
>         emit_gmroi(as, XG_ARITHi(XOg_CMP), node,
>   		 ofs + (int32_t)offsetof(Node, key.gcr),
>   		 ptr2addr(ir_kgc(irkey)));
>         emit_sjcc(as, CC_NE, l_exit);
>       }
> -    lua_assert(!irt_isnil(irkey->t));
> +    lj_assertA(!irt_isnil(irkey->t), "bad HREFK key type");
>       emit_i8(as, irt_toitype(irkey->t));
>       emit_rmro(as, XO_ARITHi8, XOg_CMP, node,
>   	      ofs + (int32_t)offsetof(Node, key.it));
> @@ -1407,7 +1416,8 @@ static void asm_fxload(ASMState *as, IRIns *ir)
>       if (LJ_64 && irt_is64(ir->t))
>         dest |= REX_64;
>       else
> -      lua_assert(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t));
> +      lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t),
> +		 "unsplit 64 bit load");
>       xo = XO_MOV;
>       break;
>     }
> @@ -1452,13 +1462,16 @@ static void asm_fxstore(ASMState *as, IRIns *ir)
>       case IRT_NUM: xo = XO_MOVSDto; break;
>       case IRT_FLOAT: xo = XO_MOVSSto; break;
>   #if LJ_64 && !LJ_GC64
> -    case IRT_LIGHTUD: lua_assert(0);  /* NYI: mask 64 bit lightuserdata. */
> +    case IRT_LIGHTUD:
> +      /* NYI: mask 64 bit lightuserdata. */
> +      lj_assertA(0, "store of lightuserdata");
>   #endif
>       default:
>         if (LJ_64 && irt_is64(ir->t))
>   	src |= REX_64;
>         else
> -	lua_assert(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t));
> +	lj_assertA(irt_isint(ir->t) || irt_isu32(ir->t) || irt_isaddr(ir->t),
> +		   "unsplit 64 bit store");
>         xo = XO_MOVto;
>         break;
>       }
> @@ -1472,8 +1485,8 @@ static void asm_fxstore(ASMState *as, IRIns *ir)
>         emit_i8(as, k);
>         emit_mrm(as, XO_MOVmib, 0, RID_MRM);
>       } else {
> -      lua_assert(irt_is64(ir->t) || irt_isint(ir->t) || irt_isu32(ir->t) ||
> -		 irt_isaddr(ir->t));
> +      lj_assertA(irt_is64(ir->t) || irt_isint(ir->t) || irt_isu32(ir->t) ||
> +		 irt_isaddr(ir->t), "bad store type");
>         emit_i32(as, k);
>         emit_mrm(as, XO_MOVmi, REX_64IR(ir, 0), RID_MRM);
>       }
> @@ -1508,8 +1521,9 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>   #if LJ_GC64
>     Reg tmp = RID_NONE;
>   #endif
> -  lua_assert(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> -	     (LJ_DUALNUM && irt_isint(ir->t)));
> +  lj_assertA(irt_isnum(ir->t) || irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> +	     (LJ_DUALNUM && irt_isint(ir->t)),
> +	     "bad load type %d", irt_type(ir->t));
>   #if LJ_64 && !LJ_GC64
>     if (irt_islightud(ir->t)) {
>       Reg dest = asm_load_lightud64(as, ir, 1);
> @@ -1556,7 +1570,8 @@ static void asm_ahuvload(ASMState *as, IRIns *ir)
>     as->mrm.ofs += 4;
>     asm_guardcc(as, irt_isnum(ir->t) ? CC_AE : CC_NE);
>     if (LJ_64 && irt_type(ir->t) >= IRT_NUM) {
> -    lua_assert(irt_isinteger(ir->t) || irt_isnum(ir->t));
> +    lj_assertA(irt_isinteger(ir->t) || irt_isnum(ir->t),
> +	       "bad load type %d", irt_type(ir->t));
>   #if LJ_GC64
>       emit_u32(as, LJ_TISNUM << 15);
>   #else
> @@ -1638,13 +1653,14 @@ static void asm_ahustore(ASMState *as, IRIns *ir)
>   #endif
>         emit_mrm(as, XO_MOVto, src, RID_MRM);
>       } else if (!irt_ispri(irr->t)) {
> -      lua_assert(irt_isaddr(ir->t) || (LJ_DUALNUM && irt_isinteger(ir->t)));
> +      lj_assertA(irt_isaddr(ir->t) || (LJ_DUALNUM && irt_isinteger(ir->t)),
> +		 "bad store type");
>         emit_i32(as, irr->i);
>         emit_mrm(as, XO_MOVmi, 0, RID_MRM);
>       }
>       as->mrm.ofs += 4;
>   #if LJ_GC64
> -    lua_assert(LJ_DUALNUM && irt_isinteger(ir->t));
> +    lj_assertA(LJ_DUALNUM && irt_isinteger(ir->t), "bad store type");
>       emit_i32(as, LJ_TNUMX << 15);
>   #else
>       emit_i32(as, (int32_t)irt_toitype(ir->t));
> @@ -1659,10 +1675,13 @@ static void asm_sload(ASMState *as, IRIns *ir)
>   		(!LJ_FR2 && (ir->op2 & IRSLOAD_FRAME) ? 4 : 0);
>     IRType1 t = ir->t;
>     Reg base;
> -  lua_assert(!(ir->op2 & IRSLOAD_PARENT));  /* Handled by asm_head_side(). */
> -  lua_assert(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK));
> -  lua_assert(LJ_DUALNUM ||
> -	     !irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)));
> +  lj_assertA(!(ir->op2 & IRSLOAD_PARENT),
> +	     "bad parent SLOAD"); /* Handled by asm_head_side(). */
> +  lj_assertA(irt_isguard(t) || !(ir->op2 & IRSLOAD_TYPECHECK),
> +	     "inconsistent SLOAD variant");
> +  lj_assertA(LJ_DUALNUM ||
> +	     !irt_isint(t) || (ir->op2 & (IRSLOAD_CONVERT|IRSLOAD_FRAME)),
> +	     "bad SLOAD type");
>     if ((ir->op2 & IRSLOAD_CONVERT) && irt_isguard(t) && irt_isint(t)) {
>       Reg left = ra_scratch(as, RSET_FPR);
>       asm_tointg(as, ir, left);  /* Frees dest reg. Do this before base alloc. */
> @@ -1682,7 +1701,8 @@ static void asm_sload(ASMState *as, IRIns *ir)
>       RegSet allow = irt_isnum(t) ? RSET_FPR : RSET_GPR;
>       Reg dest = ra_dest(as, ir, allow);
>       base = ra_alloc1(as, REF_BASE, RSET_GPR);
> -    lua_assert(irt_isnum(t) || irt_isint(t) || irt_isaddr(t));
> +    lj_assertA(irt_isnum(t) || irt_isint(t) || irt_isaddr(t),
> +	       "bad SLOAD type %d", irt_type(t));
>       if ((ir->op2 & IRSLOAD_CONVERT)) {
>         t.irt = irt_isint(t) ? IRT_NUM : IRT_INT;  /* Check for original type. */
>         emit_rmro(as, irt_isint(t) ? XO_CVTSI2SD : XO_CVTTSD2SI, dest, base, ofs);
> @@ -1728,7 +1748,8 @@ static void asm_sload(ASMState *as, IRIns *ir)
>       /* Need type check, even if the load result is unused. */
>       asm_guardcc(as, irt_isnum(t) ? CC_AE : CC_NE);
>       if (LJ_64 && irt_type(t) >= IRT_NUM) {
> -      lua_assert(irt_isinteger(t) || irt_isnum(t));
> +      lj_assertA(irt_isinteger(t) || irt_isnum(t),
> +		 "bad SLOAD type %d", irt_type(t));
>   #if LJ_GC64
>         emit_u32(as, LJ_TISNUM << 15);
>   #else
> @@ -1780,7 +1801,8 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>     CTInfo info = lj_ctype_info(cts, id, &sz);
>     const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_mem_newgco];
>     IRRef args[4];
> -  lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
> +  lj_assertA(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL),
> +	     "bad CNEW/CNEWI operands");
>   
>     as->gcsteps++;
>     asm_setupresult(as, ir, ci);  /* GCcdata * */
> @@ -1810,7 +1832,7 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>       int32_t ofs = sizeof(GCcdata);
>       if (sz == 8) {
>         ofs += 4; ir++;
> -      lua_assert(ir->o == IR_HIOP);
> +      lj_assertA(ir->o == IR_HIOP, "missing CNEWI HIOP");
>       }
>       do {
>         if (irref_isk(ir->op2)) {
> @@ -1824,7 +1846,7 @@ static void asm_cnew(ASMState *as, IRIns *ir)
>         ofs -= 4; ir--;
>       } while (1);
>   #endif
> -    lua_assert(sz == 4 || sz == 8);
> +    lj_assertA(sz == 4 || sz == 8, "bad CNEWI size %d", sz);
>     } else if (ir->op2 != REF_NIL) {  /* Create VLA/VLS/aligned cdata. */
>       ci = &lj_ir_callinfo[IRCALL_lj_cdata_newv];
>       args[0] = ASMREF_L;     /* lua_State *L */
> @@ -1883,7 +1905,7 @@ static void asm_obar(ASMState *as, IRIns *ir)
>     MCLabel l_end;
>     Reg obj;
>     /* No need for other object barriers (yet). */
> -  lua_assert(IR(ir->op1)->o == IR_UREFC);
> +  lj_assertA(IR(ir->op1)->o == IR_UREFC, "bad OBAR type");
>     ra_evictset(as, RSET_SCRATCH);
>     l_end = emit_label(as);
>     args[0] = ASMREF_TMP1;  /* global_State *g */
> @@ -2000,7 +2022,7 @@ static int asm_swapops(ASMState *as, IRIns *ir)
>   {
>     IRIns *irl = IR(ir->op1);
>     IRIns *irr = IR(ir->op2);
> -  lua_assert(ra_noreg(irr->r));
> +  lj_assertA(ra_noreg(irr->r), "bad usage");
>     if (!irm_iscomm(lj_ir_mode[ir->o]))
>       return 0;  /* Can't swap non-commutative operations. */
>     if (irref_isk(ir->op2))
> @@ -2391,8 +2413,9 @@ static void asm_comp(ASMState *as, IRIns *ir)
>       IROp leftop = (IROp)(IR(lref)->o);
>       Reg r64 = REX_64IR(ir, 0);
>       int32_t imm = 0;
> -    lua_assert(irt_is64(ir->t) || irt_isint(ir->t) ||
> -	       irt_isu32(ir->t) || irt_isaddr(ir->t) || irt_isu8(ir->t));
> +    lj_assertA(irt_is64(ir->t) || irt_isint(ir->t) ||
> +	       irt_isu32(ir->t) || irt_isaddr(ir->t) || irt_isu8(ir->t),
> +	       "bad comparison data type %d", irt_type(ir->t));
>       /* Swap constants (only for ABC) and fusable loads to the right. */
>       if (irref_isk(lref) || (!irref_isk(rref) && opisfusableload(leftop))) {
>         if ((cc & 0xc) == 0xc) cc ^= 0x53;  /* L <-> G, LE <-> GE */
> @@ -2474,7 +2497,7 @@ static void asm_comp(ASMState *as, IRIns *ir)
>   	  /* Use test r,r instead of cmp r,0. */
>   	  x86Op xo = XO_TEST;
>   	  if (irt_isu8(ir->t)) {
> -	    lua_assert(ir->o == IR_EQ || ir->o == IR_NE);
> +	    lj_assertA(ir->o == IR_EQ || ir->o == IR_NE, "bad usage");
>   	    xo = XO_TESTb;
>   	    if (!rset_test(RSET_RANGE(RID_EAX, RID_EBX+1), left)) {
>   	      if (LJ_64) {
> @@ -2630,10 +2653,11 @@ static void asm_hiop(ASMState *as, IRIns *ir)
>     case IR_CNEWI:
>       /* Nothing to do here. Handled by CNEWI itself. */
>       break;
> -  default: lua_assert(0); break;
> +  default: lj_assertA(0, "bad HIOP for op %d", (ir-1)->o); break;
>     }
>   #else
> -  UNUSED(as); UNUSED(ir); lua_assert(0);  /* Unused on x64 or without FFI. */
> +  /* Unused on x64 or without FFI. */
> +  UNUSED(as); UNUSED(ir); lj_assertA(0, "unexpected HIOP");
>   #endif
>   }
>   
> @@ -2699,8 +2723,9 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>         Reg src = ra_alloc1(as, ref, RSET_FPR);
>         emit_rmro(as, XO_MOVSDto, src, RID_BASE, ofs);
>       } else {
> -      lua_assert(irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> -		 (LJ_DUALNUM && irt_isinteger(ir->t)));
> +      lj_assertA(irt_ispri(ir->t) || irt_isaddr(ir->t) ||
> +		 (LJ_DUALNUM && irt_isinteger(ir->t)),
> +		 "restore of IR type %d", irt_type(ir->t));
>         if (!irref_isk(ref)) {
>   	Reg src = ra_alloc1(as, ref, rset_exclude(RSET_GPR, RID_BASE));
>   #if LJ_GC64
> @@ -2745,7 +2770,7 @@ static void asm_stack_restore(ASMState *as, SnapShot *snap)
>       }
>       checkmclim(as);
>     }
> -  lua_assert(map + nent == flinks);
> +  lj_assertA(map + nent == flinks, "inconsistent frames in snapshot");
>   }
>   
>   /* -- GC handling --------------------------------------------------------- */
> @@ -2789,16 +2814,16 @@ static void asm_loop_fixup(ASMState *as)
>     MCode *target = as->mcp;
>     if (as->realign) {  /* Realigned loops use short jumps. */
>       as->realign = NULL;  /* Stop another retry. */
> -    lua_assert(((intptr_t)target & 15) == 0);
> +    lj_assertA(((intptr_t)target & 15) == 0, "loop realign failed");
>       if (as->loopinv) {  /* Inverted loop branch? */
>         p -= 5;
>         p[0] = XI_JMP;
> -      lua_assert(target - p >= -128);
> +      lj_assertA(target - p >= -128, "loop realign failed");
>         p[-1] = (MCode)(target - p);  /* Patch sjcc. */
>         if (as->loopinv == 2)
>   	p[-3] = (MCode)(target - p + 2);  /* Patch opt. short jp. */
>       } else {
> -      lua_assert(target - p >= -128);
> +      lj_assertA(target - p >= -128, "loop realign failed");
>         p[-1] = (MCode)(int8_t)(target - p);  /* Patch short jmp. */
>         p[-2] = XI_JMPs;
>       }
> @@ -2904,7 +2929,7 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
>     }
>     /* Patch exit branch. */
>     target = lnk ? traceref(as->J, lnk)->mcode : (MCode *)lj_vm_exit_interp;
> -  *(int32_t *)(p-4) = jmprel(p, target);
> +  *(int32_t *)(p-4) = jmprel(as->J, p, target);
>     p[-5] = XI_JMP;
>     /* Drop unused mcode tail. Fill with NOPs to make the prefetcher happy. */
>     for (q = as->mctop-1; q >= p; q--)
> @@ -3077,17 +3102,17 @@ void lj_asm_patchexit(jit_State *J, GCtrace *T, ExitNo exitno, MCode *target)
>     uint32_t statei = u32ptr(&J2G(J)->vmstate);
>   #endif
>     if (len > 5 && p[len-5] == XI_JMP && p+len-6 + *(int32_t *)(p+len-4) == px)
> -    *(int32_t *)(p+len-4) = jmprel(p+len, target);
> +    *(int32_t *)(p+len-4) = jmprel(J, p+len, target);
>     /* Do not patch parent exit for a stack check. Skip beyond vmstate update. */
>     for (; p < pe; p += asm_x86_inslen(p)) {
>       intptr_t ofs = LJ_GC64 ? (p[0] & 0xf0) == 0x40 : LJ_64;
>       if (*(uint32_t *)(p+2+ofs) == statei && p[ofs+LJ_GC64-LJ_64] == XI_MOVmi)
>         break;
>     }
> -  lua_assert(p < pe);
> +  lj_assertJ(p < pe, "instruction length decoder failed");
>     for (; p < pe; p += asm_x86_inslen(p))
>       if ((*(uint16_t *)p & 0xf0ff) == 0x800f && p + *(int32_t *)(p+2) == px)
> -      *(int32_t *)(p+2) = jmprel(p+6, target);
> +      *(int32_t *)(p+2) = jmprel(J, p+6, target);
>     lj_mcode_sync(T->mcode, T->mcode + T->szmcode);
>     lj_mcode_patch(J, mcarea, 1);
>   }
> diff --git a/src/lj_assert.c b/src/lj_assert.c
> new file mode 100644
> index 00000000..7989dbe6
> --- /dev/null
> +++ b/src/lj_assert.c
> @@ -0,0 +1,28 @@
> +/*
> +** Internal assertions.
> +** Copyright (C) 2005-2020 Mike Pall. See Copyright Notice in luajit.h
> +*/
> +
> +#define lj_assert_c
> +#define LUA_CORE
> +
> +#if defined(LUA_USE_ASSERT) || defined(LUA_USE_APICHECK)
> +
> +#include <stdio.h>
> +
> +#include "lj_obj.h"
> +
> +void lj_assert_fail(global_State *g, const char *file, int line,
> +		    const char *func, const char *fmt, ...)
> +{
> +  va_list argp;
> +  va_start(argp, fmt);
> +  fprintf(stderr, "LuaJIT ASSERT %s:%d: %s: ", file, line, func);
> +  vfprintf(stderr, fmt, argp);
> +  fputc('\n', stderr);
> +  va_end(argp);
> +  UNUSED(g);  /* May be NULL. TODO: optionally dump state. */
> +  abort();
> +}
> +
> +#endif
> diff --git a/src/lj_bcread.c b/src/lj_bcread.c
> index f6c7ad25..cddf6ff1 100644
> --- a/src/lj_bcread.c
> +++ b/src/lj_bcread.c
> @@ -53,7 +53,7 @@ static LJ_NOINLINE void bcread_error(LexState *ls, ErrMsg em)
>   /* Refill buffer. */
>   static LJ_NOINLINE void bcread_fill(LexState *ls, MSize len, int need)
>   {
> -  lua_assert(len != 0);
> +  lj_assertLS(len != 0, "empty refill");
>     if (len > LJ_MAX_BUF || ls->c < 0)
>       bcread_error(ls, LJ_ERR_BCBAD);
>     do {
> @@ -63,7 +63,7 @@ static LJ_NOINLINE void bcread_fill(LexState *ls, MSize len, int need)
>       MSize n = (MSize)(ls->pe - ls->p);
>       if (n) {  /* Copy remainder to buffer. */
>         if (sbuflen(&ls->sb)) {  /* Move down in buffer. */
> -	lua_assert(ls->pe == sbufP(&ls->sb));
> +	lj_assertLS(ls->pe == sbufP(&ls->sb), "bad buffer pointer");
>   	if (ls->p != p) memmove(p, ls->p, n);
>         } else {  /* Copy from buffer provided by reader. */
>   	p = lj_buf_need(&ls->sb, len);
> @@ -112,7 +112,7 @@ static LJ_AINLINE uint8_t *bcread_mem(LexState *ls, MSize len)
>   {
>     uint8_t *p = (uint8_t *)ls->p;
>     ls->p += len;
> -  lua_assert(ls->p <= ls->pe);
> +  lj_assertLS(ls->p <= ls->pe, "buffer read overflow");
>     return p;
>   }
>   
> @@ -125,7 +125,7 @@ static void bcread_block(LexState *ls, void *q, MSize len)
>   /* Read byte from buffer. */
>   static LJ_AINLINE uint32_t bcread_byte(LexState *ls)
>   {
> -  lua_assert(ls->p < ls->pe);
> +  lj_assertLS(ls->p < ls->pe, "buffer read overflow");
>     return (uint32_t)(uint8_t)*ls->p++;
>   }
>   
> @@ -133,7 +133,7 @@ static LJ_AINLINE uint32_t bcread_byte(LexState *ls)
>   static LJ_AINLINE uint32_t bcread_uleb128(LexState *ls)
>   {
>     uint32_t v = lj_buf_ruleb128(&ls->p);
> -  lua_assert(ls->p <= ls->pe);
> +  lj_assertLS(ls->p <= ls->pe, "buffer read overflow");
>     return v;
>   }
>   
> @@ -150,7 +150,7 @@ static uint32_t bcread_uleb128_33(LexState *ls)
>      } while (*p++ >= 0x80);
>     }
>     ls->p = (char *)p;
> -  lua_assert(ls->p <= ls->pe);
> +  lj_assertLS(ls->p <= ls->pe, "buffer read overflow");
>     return v;
>   }
>   
> @@ -197,7 +197,7 @@ static void bcread_ktabk(LexState *ls, TValue *o)
>       o->u32.lo = bcread_uleb128(ls);
>       o->u32.hi = bcread_uleb128(ls);
>     } else {
> -    lua_assert(tp <= BCDUMP_KTAB_TRUE);
> +    lj_assertLS(tp <= BCDUMP_KTAB_TRUE, "bad constant type %d", tp);
>       setpriV(o, ~tp);
>     }
>   }
> @@ -219,7 +219,7 @@ static GCtab *bcread_ktab(LexState *ls)
>       for (i = 0; i < nhash; i++) {
>         TValue key;
>         bcread_ktabk(ls, &key);
> -      lua_assert(!tvisnil(&key));
> +      lj_assertLS(!tvisnil(&key), "nil key");
>         bcread_ktabk(ls, lj_tab_set(ls->L, t, &key));
>       }
>     }
> @@ -256,7 +256,7 @@ static void bcread_kgc(LexState *ls, GCproto *pt, MSize sizekgc)
>   #endif
>       } else {
>         lua_State *L = ls->L;
> -      lua_assert(tp == BCDUMP_KGC_CHILD);
> +      lj_assertLS(tp == BCDUMP_KGC_CHILD, "bad constant type %d", tp);
>         if (L->top <= bcread_oldtop(L, ls))  /* Stack underflow? */
>   	bcread_error(ls, LJ_ERR_BCBAD);
>         L->top--;
> @@ -437,7 +437,7 @@ static int bcread_header(LexState *ls)
>   GCproto *lj_bcread(LexState *ls)
>   {
>     lua_State *L = ls->L;
> -  lua_assert(ls->c == BCDUMP_HEAD1);
> +  lj_assertLS(ls->c == BCDUMP_HEAD1, "bad bytecode header");
>     bcread_savetop(L, ls, L->top);
>     lj_buf_reset(&ls->sb);
>     /* Check for a valid bytecode dump header. */
> diff --git a/src/lj_bcwrite.c b/src/lj_bcwrite.c
> index a86d6d00..ce5837f6 100644
> --- a/src/lj_bcwrite.c
> +++ b/src/lj_bcwrite.c
> @@ -29,8 +29,17 @@ typedef struct BCWriteCtx {
>     void *wdata;			/* Writer callback data. */
>     int strip;			/* Strip debug info. */
>     int status;			/* Status from writer callback. */
> +#ifdef LUA_USE_ASSERT
> +  global_State *g;
> +#endif
>   } BCWriteCtx;
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertBCW(c, ...)	lj_assertG_(ctx->g, (c), __VA_ARGS__)
> +#else
> +#define lj_assertBCW(c, ...)	((void)ctx)
> +#endif
> +
>   /* -- Bytecode writer ----------------------------------------------------- */
>   
>   /* Write a single constant key/value of a template table. */
> @@ -61,7 +70,7 @@ static void bcwrite_ktabk(BCWriteCtx *ctx, cTValue *o, int narrow)
>       p = lj_strfmt_wuleb128(p, o->u32.lo);
>       p = lj_strfmt_wuleb128(p, o->u32.hi);
>     } else {
> -    lua_assert(tvispri(o));
> +    lj_assertBCW(tvispri(o), "unhandled type %d", itype(o));
>       *p++ = BCDUMP_KTAB_NIL+~itype(o);
>     }
>     setsbufP(&ctx->sb, p);
> @@ -121,7 +130,7 @@ static void bcwrite_kgc(BCWriteCtx *ctx, GCproto *pt)
>         tp = BCDUMP_KGC_STR + gco2str(o)->len;
>         need = 5+gco2str(o)->len;
>       } else if (o->gch.gct == ~LJ_TPROTO) {
> -      lua_assert((pt->flags & PROTO_CHILD));
> +      lj_assertBCW((pt->flags & PROTO_CHILD), "prototype has unexpected child");
>         tp = BCDUMP_KGC_CHILD;
>   #if LJ_HASFFI
>       } else if (o->gch.gct == ~LJ_TCDATA) {
> @@ -132,12 +141,14 @@ static void bcwrite_kgc(BCWriteCtx *ctx, GCproto *pt)
>         } else if (id == CTID_UINT64) {
>   	tp = BCDUMP_KGC_U64;
>         } else {
> -	lua_assert(id == CTID_COMPLEX_DOUBLE);
> +	lj_assertBCW(id == CTID_COMPLEX_DOUBLE,
> +		     "bad cdata constant CTID %d", id);
>   	tp = BCDUMP_KGC_COMPLEX;
>         }
>   #endif
>       } else {
> -      lua_assert(o->gch.gct == ~LJ_TTAB);
> +      lj_assertBCW(o->gch.gct == ~LJ_TTAB,
> +		   "bad constant GC type %d", o->gch.gct);
>         tp = BCDUMP_KGC_TAB;
>         need = 1+2*5;
>       }
> @@ -289,7 +300,7 @@ static void bcwrite_proto(BCWriteCtx *ctx, GCproto *pt)
>       MSize nn = (lj_fls(n)+8)*9 >> 6;
>       char *q = sbufB(&ctx->sb) + (5 - nn);
>       p = lj_strfmt_wuleb128(q, n);  /* Fill in final size. */
> -    lua_assert(p == sbufB(&ctx->sb) + 5);
> +    lj_assertBCW(p == sbufB(&ctx->sb) + 5, "bad ULEB128 write");
>       ctx->status = ctx->wfunc(sbufL(&ctx->sb), q, nn+n, ctx->wdata);
>     }
>   }
> @@ -349,6 +360,9 @@ int lj_bcwrite(lua_State *L, GCproto *pt, lua_Writer writer, void *data,
>     ctx.wdata = data;
>     ctx.strip = strip;
>     ctx.status = 0;
> +#ifdef LUA_USE_ASSERT
> +  ctx.g = G(L);
> +#endif
>     lj_buf_init(L, &ctx.sb);
>     status = lj_vm_cpcall(L, NULL, &ctx, cpwriter);
>     if (status == 0) status = ctx.status;
> diff --git a/src/lj_buf.c b/src/lj_buf.c
> index 0dfe7f98..923f4276 100644
> --- a/src/lj_buf.c
> +++ b/src/lj_buf.c
> @@ -30,7 +30,7 @@ static void buf_grow(SBuf *sb, MSize sz)
>   
>   LJ_NOINLINE char *LJ_FASTCALL lj_buf_need2(SBuf *sb, MSize sz)
>   {
> -  lua_assert(sz > sbufsz(sb));
> +  lj_assertG_(G(sbufL(sb)), sz > sbufsz(sb), "SBuf overflow");
>     if (LJ_UNLIKELY(sz > LJ_MAX_BUF))
>       lj_err_mem(sbufL(sb));
>     buf_grow(sb, sz);
> @@ -40,7 +40,7 @@ LJ_NOINLINE char *LJ_FASTCALL lj_buf_need2(SBuf *sb, MSize sz)
>   LJ_NOINLINE char *LJ_FASTCALL lj_buf_more2(SBuf *sb, MSize sz)
>   {
>     MSize len = sbuflen(sb);
> -  lua_assert(sz > sbufleft(sb));
> +  lj_assertG_(G(sbufL(sb)), sz > sbufleft(sb), "SBuf overflow");
>     if (LJ_UNLIKELY(sz > LJ_MAX_BUF || len + sz > LJ_MAX_BUF))
>       lj_err_mem(sbufL(sb));
>     buf_grow(sb, len + sz);
> diff --git a/src/lj_carith.c b/src/lj_carith.c
> index 04c18054..4ae1e9ee 100644
> --- a/src/lj_carith.c
> +++ b/src/lj_carith.c
> @@ -122,7 +122,7 @@ static int carith_ptr(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
>   	setboolV(L->top-1, ((uintptr_t)pp < (uintptr_t)pp2));
>   	return 1;
>         } else {
> -	lua_assert(mm == MM_le);
> +	lj_assertL(mm == MM_le, "bad metamethod %d", mm);
>   	setboolV(L->top-1, ((uintptr_t)pp <= (uintptr_t)pp2));
>   	return 1;
>         }
> @@ -208,7 +208,9 @@ static int carith_int64(lua_State *L, CTState *cts, CDArith *ca, MMS mm)
>   	*up = lj_carith_powu64(u0, u1);
>         break;
>       case MM_unm: *up = (uint64_t)-(int64_t)u0; break;
> -    default: lua_assert(0); break;
> +    default:
> +      lj_assertL(0, "bad metamethod %d", mm);
> +      break;
>       }
>       lj_gc_check(L);
>       return 1;
> @@ -301,7 +303,9 @@ uint64_t lj_carith_shift64(uint64_t x, int32_t sh, int op)
>     case IR_BSAR-IR_BSHL: x = lj_carith_sar64(x, sh); break;
>     case IR_BROL-IR_BSHL: x = lj_carith_rol64(x, sh); break;
>     case IR_BROR-IR_BSHL: x = lj_carith_ror64(x, sh); break;
> -  default: lua_assert(0); break;
> +  default:
> +    lj_assertX(0, "bad shift op %d", op);
> +    break;
>     }
>     return x;
>   }
> diff --git a/src/lj_ccall.c b/src/lj_ccall.c
> index c1e12f56..a989f657 100644
> --- a/src/lj_ccall.c
> +++ b/src/lj_ccall.c
> @@ -391,7 +391,8 @@
>   #define CCALL_HANDLE_GPR \
>     /* Try to pass argument in GPRs. */ \
>     if (n > 1) { \
> -    lua_assert(n == 2 || n == 4);  /* int64_t or complex (float). */ \
> +    /* int64_t or complex (float). */ \
> +    lj_assertL(n == 2 || n == 4, "bad GPR size %d", n); \
>       if (ctype_isinteger(d->info) || ctype_isfp(d->info)) \
>         ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
>       else if (ngpr + n > maxgpr) \
> @@ -642,7 +643,8 @@ static void ccall_classify_ct(CTState *cts, CType *ct, int *rcl, CTSize ofs)
>       ccall_classify_struct(cts, ct, rcl, ofs);
>     } else {
>       int cl = ctype_isfp(ct->info) ? CCALL_RCL_SSE : CCALL_RCL_INT;
> -    lua_assert(ctype_hassize(ct->info));
> +    lj_assertCTS(ctype_hassize(ct->info),
> +		 "classify ctype %08x without size", ct->info);
>       if ((ofs & (ct->size-1))) cl = CCALL_RCL_MEM;  /* Unaligned. */
>       rcl[(ofs >= 8)] |= cl;
>     }
> @@ -667,12 +669,13 @@ static int ccall_classify_struct(CTState *cts, CType *ct, int *rcl, CTSize ofs)
>   }
>   
>   /* Try to split up a small struct into registers. */
> -static int ccall_struct_reg(CCallState *cc, GPRArg *dp, int *rcl)
> +static int ccall_struct_reg(CCallState *cc, CTState *cts, GPRArg *dp, int *rcl)
>   {
>     MSize ngpr = cc->ngpr, nfpr = cc->nfpr;
>     uint32_t i;
> +  UNUSED(cts);
>     for (i = 0; i < 2; i++) {
> -    lua_assert(!(rcl[i] & CCALL_RCL_MEM));
> +    lj_assertCTS(!(rcl[i] & CCALL_RCL_MEM), "pass mem struct in reg");
>       if ((rcl[i] & CCALL_RCL_INT)) {  /* Integer class takes precedence. */
>         if (ngpr >= CCALL_NARG_GPR) return 1;  /* Register overflow. */
>         cc->gpr[ngpr++] = dp[i];
> @@ -693,7 +696,8 @@ static int ccall_struct_arg(CCallState *cc, CTState *cts, CType *d, int *rcl,
>     dp[0] = dp[1] = 0;
>     /* Convert to temp. struct. */
>     lj_cconv_ct_tv(cts, d, (uint8_t *)dp, o, CCF_ARG(narg));
> -  if (ccall_struct_reg(cc, dp, rcl)) {  /* Register overflow? Pass on stack. */
> +  if (ccall_struct_reg(cc, cts, dp, rcl)) {
> +    /* Register overflow? Pass on stack. */
>       MSize nsp = cc->nsp, n = rcl[1] ? 2 : 1;
>       if (nsp + n > CCALL_MAXSTACK) return 1;  /* Too many arguments. */
>       cc->nsp = nsp + n;
> @@ -989,7 +993,7 @@ static int ccall_set_args(lua_State *L, CTState *cts, CType *ct,
>       if (fid) {  /* Get argument type from field. */
>         CType *ctf = ctype_get(cts, fid);
>         fid = ctf->sib;
> -      lua_assert(ctype_isfield(ctf->info));
> +      lj_assertL(ctype_isfield(ctf->info), "field expected");
>         did = ctype_cid(ctf->info);
>       } else {
>         if (!(ct->info & CTF_VARARG))
> @@ -1137,7 +1141,8 @@ static int ccall_get_results(lua_State *L, CTState *cts, CType *ct,
>     CCALL_HANDLE_RET
>   #endif
>     /* No reference types end up here, so there's no need for the CTypeID. */
> -  lua_assert(!(ctype_isrefarray(ctr->info) || ctype_isstruct(ctr->info)));
> +  lj_assertL(!(ctype_isrefarray(ctr->info) || ctype_isstruct(ctr->info)),
> +	     "unexpected reference ctype");
>     return lj_cconv_tv_ct(cts, ctr, 0, L->top-1, sp);
>   }
>   
> diff --git a/src/lj_ccallback.c b/src/lj_ccallback.c
> index 37edd00f..3738c234 100644
> --- a/src/lj_ccallback.c
> +++ b/src/lj_ccallback.c
> @@ -107,9 +107,9 @@ MSize lj_ccallback_ptr2slot(CTState *cts, void *p)
>   /* Initialize machine code for callback function pointers. */
>   #if LJ_OS_NOJIT
>   /* Disabled callback support. */
> -#define callback_mcode_init(g, p)	UNUSED(p)
> +#define callback_mcode_init(g, p)	(p)
>   #elif LJ_TARGET_X86ORX64
> -static void callback_mcode_init(global_State *g, uint8_t *page)
> +static void *callback_mcode_init(global_State *g, uint8_t *page)
>   {
>     uint8_t *p = page;
>     uint8_t *target = (uint8_t *)(void *)lj_vm_ffi_callback;
> @@ -143,10 +143,10 @@ static void callback_mcode_init(global_State *g, uint8_t *page)
>         *p++ = XI_JMPs; *p++ = (uint8_t)((2+2)*(31-(slot&31)) - 2);
>       }
>     }
> -  lua_assert(p - page <= CALLBACK_MCODE_SIZE);
> +  return p;
>   }
>   #elif LJ_TARGET_ARM
> -static void callback_mcode_init(global_State *g, uint32_t *page)
> +static void *callback_mcode_init(global_State *g, uint32_t *page)
>   {
>     uint32_t *p = page;
>     void *target = (void *)lj_vm_ffi_callback;
> @@ -165,10 +165,10 @@ static void callback_mcode_init(global_State *g, uint32_t *page)
>       *p = ARMI_B | ((page-p-2) & 0x00ffffffu);
>       p++;
>     }
> -  lua_assert(p - page <= CALLBACK_MCODE_SIZE);
> +  return p;
>   }
>   #elif LJ_TARGET_ARM64
> -static void callback_mcode_init(global_State *g, uint32_t *page)
> +static void *callback_mcode_init(global_State *g, uint32_t *page)
>   {
>     uint32_t *p = page;
>     void *target = (void *)lj_vm_ffi_callback;
> @@ -185,10 +185,10 @@ static void callback_mcode_init(global_State *g, uint32_t *page)
>       *p = A64I_LE(A64I_B | A64F_S26((page-p) & 0x03ffffffu));
>       p++;
>     }
> -  lua_assert(p - page <= CALLBACK_MCODE_SIZE);
> +  return p;
>   }
>   #elif LJ_TARGET_PPC
> -static void callback_mcode_init(global_State *g, uint32_t *page)
> +static void *callback_mcode_init(global_State *g, uint32_t *page)
>   {
>     uint32_t *p = page;
>     void *target = (void *)lj_vm_ffi_callback;
> @@ -204,10 +204,10 @@ static void callback_mcode_init(global_State *g, uint32_t *page)
>       *p = PPCI_B | (((page-p) & 0x00ffffffu) << 2);
>       p++;
>     }
> -  lua_assert(p - page <= CALLBACK_MCODE_SIZE);
> +  return p;
>   }
>   #elif LJ_TARGET_MIPS
> -static void callback_mcode_init(global_State *g, uint32_t *page)
> +static void *callback_mcode_init(global_State *g, uint32_t *page)
>   {
>     uint32_t *p = page;
>     uintptr_t target = (uintptr_t)(void *)lj_vm_ffi_callback;
> @@ -236,11 +236,11 @@ static void callback_mcode_init(global_State *g, uint32_t *page)
>       p++;
>       *p++ = MIPSI_LI | MIPSF_T(RID_R1) | slot;
>     }
> -  lua_assert(p - page <= CALLBACK_MCODE_SIZE);
> +  return p;
>   }
>   #else
>   /* Missing support for this architecture. */
> -#define callback_mcode_init(g, p)	UNUSED(p)
> +#define callback_mcode_init(g, p)	(p)
>   #endif
>   
>   /* -- Machine code management --------------------------------------------- */
> @@ -263,7 +263,7 @@ static void callback_mcode_init(global_State *g, uint32_t *page)
>   static void callback_mcode_new(CTState *cts)
>   {
>     size_t sz = (size_t)CALLBACK_MCODE_SIZE;
> -  void *p;
> +  void *p, *pe;
>     if (CALLBACK_MAX_SLOT == 0)
>       lj_err_caller(cts->L, LJ_ERR_FFI_CBACKOV);
>   #if LJ_TARGET_WINDOWS
> @@ -280,7 +280,10 @@ static void callback_mcode_new(CTState *cts)
>     p = lj_mem_new(cts->L, sz);
>   #endif
>     cts->cb.mcode = p;
> -  callback_mcode_init(cts->g, p);
> +  pe = callback_mcode_init(cts->g, p);
> +  UNUSED(pe);
> +  lj_assertCTS((size_t)((char *)pe - (char *)p) <= sz,
> +	       "miscalculated CALLBACK_MAX_SLOT");
>     lj_mcode_sync(p, (char *)p + sz);
>   #if LJ_TARGET_WINDOWS
>     {
> @@ -421,8 +424,9 @@ void lj_ccallback_mcode_free(CTState *cts)
>   
>   #define CALLBACK_HANDLE_GPR \
>     if (n > 1) { \
> -    lua_assert(((LJ_ABI_SOFTFP && ctype_isnum(cta->info)) ||  /* double. */ \
> -		ctype_isinteger(cta->info)) && n == 2);  /* int64_t. */ \
> +    lj_assertCTS(((LJ_ABI_SOFTFP && ctype_isnum(cta->info)) ||  /* double. */ \
> +		 ctype_isinteger(cta->info)) && n == 2,  /* int64_t. */ \
> +		 "bad GPR type"); \
>       ngpr = (ngpr + 1u) & ~1u;  /* Align int64_t to regpair. */ \
>     } \
>     if (ngpr + n <= maxgpr) { \
> @@ -579,7 +583,7 @@ static void callback_conv_args(CTState *cts, lua_State *L)
>         CTSize sz;
>         int isfp;
>         MSize n;
> -      lua_assert(ctype_isfield(ctf->info));
> +      lj_assertCTS(ctype_isfield(ctf->info), "field expected");
>         cta = ctype_rawchild(cts, ctf);
>         isfp = ctype_isfp(cta->info);
>         sz = (cta->size + CTSIZE_PTR-1) & ~(CTSIZE_PTR-1);
> @@ -671,7 +675,7 @@ lua_State * LJ_FASTCALL lj_ccallback_enter(CTState *cts, void *cf)
>   {
>     lua_State *L = cts->L;
>     global_State *g = cts->g;
> -  lua_assert(L != NULL);
> +  lj_assertG(L != NULL, "uninitialized cts->L in callback");
>     if (tvref(g->jit_base)) {
>       setstrV(L, L->top++, lj_err_str(L, LJ_ERR_FFI_BADCBACK));
>       if (g->panic) g->panic(L);
> @@ -756,7 +760,7 @@ static CType *callback_checkfunc(CTState *cts, CType *ct)
>         CType *ctf = ctype_get(cts, fid);
>         if (!ctype_isattrib(ctf->info)) {
>   	CType *cta;
> -	lua_assert(ctype_isfield(ctf->info));
> +	lj_assertCTS(ctype_isfield(ctf->info), "field expected");
>   	cta = ctype_rawchild(cts, ctf);
>   	if (!(ctype_isenum(cta->info) || ctype_isptr(cta->info) ||
>   	      (ctype_isnum(cta->info) && cta->size <= 8)) ||
> diff --git a/src/lj_cconv.c b/src/lj_cconv.c
> index ca2a5d30..37c88852 100644
> --- a/src/lj_cconv.c
> +++ b/src/lj_cconv.c
> @@ -122,19 +122,25 @@ void lj_cconv_ct_ct(CTState *cts, CType *d, CType *s,
>     CTInfo dinfo = d->info, sinfo = s->info;
>     void *tmpptr;
>   
> -  lua_assert(!ctype_isenum(dinfo) && !ctype_isenum(sinfo));
> -  lua_assert(!ctype_isattrib(dinfo) && !ctype_isattrib(sinfo));
> +  lj_assertCTS(!ctype_isenum(dinfo) && !ctype_isenum(sinfo),
> +	       "unresolved enum");
> +  lj_assertCTS(!ctype_isattrib(dinfo) && !ctype_isattrib(sinfo),
> +	       "unstripped attribute");
>   
>     if (ctype_type(dinfo) > CT_MAYCONVERT || ctype_type(sinfo) > CT_MAYCONVERT)
>       goto err_conv;
>   
>     /* Some basic sanity checks. */
> -  lua_assert(!ctype_isnum(dinfo) || dsize > 0);
> -  lua_assert(!ctype_isnum(sinfo) || ssize > 0);
> -  lua_assert(!ctype_isbool(dinfo) || dsize == 1 || dsize == 4);
> -  lua_assert(!ctype_isbool(sinfo) || ssize == 1 || ssize == 4);
> -  lua_assert(!ctype_isinteger(dinfo) || (1u<<lj_fls(dsize)) == dsize);
> -  lua_assert(!ctype_isinteger(sinfo) || (1u<<lj_fls(ssize)) == ssize);
> +  lj_assertCTS(!ctype_isnum(dinfo) || dsize > 0, "bad size for number type");
> +  lj_assertCTS(!ctype_isnum(sinfo) || ssize > 0, "bad size for number type");
> +  lj_assertCTS(!ctype_isbool(dinfo) || dsize == 1 || dsize == 4,
> +	       "bad size for bool type");
> +  lj_assertCTS(!ctype_isbool(sinfo) || ssize == 1 || ssize == 4,
> +	       "bad size for bool type");
> +  lj_assertCTS(!ctype_isinteger(dinfo) || (1u<<lj_fls(dsize)) == dsize,
> +	       "bad size for integer type");
> +  lj_assertCTS(!ctype_isinteger(sinfo) || (1u<<lj_fls(ssize)) == ssize,
> +	       "bad size for integer type");
>   
>     switch (cconv_idx2(dinfo, sinfo)) {
>     /* Destination is a bool. */
> @@ -357,7 +363,7 @@ void lj_cconv_ct_ct(CTState *cts, CType *d, CType *s,
>       if ((flags & CCF_CAST) || (d->info & CTF_VLA) || d != s)
>         goto err_conv;  /* Must be exact same type. */
>   copyval:  /* Copy value. */
> -    lua_assert(dsize == ssize);
> +    lj_assertCTS(dsize == ssize, "value copy with different sizes");
>       memcpy(dp, sp, dsize);
>       break;
>   
> @@ -389,7 +395,7 @@ int lj_cconv_tv_ct(CTState *cts, CType *s, CTypeID sid,
>   	lj_cconv_ct_ct(cts, ctype_get(cts, CTID_DOUBLE), s,
>   		       (uint8_t *)&o->n, sp, 0);
>   	/* Numbers are NOT canonicalized here! Beware of uninitialized data. */
> -	lua_assert(tvisnum(o));
> +	lj_assertCTS(tvisnum(o), "non-canonical NaN passed");
>         }
>       } else {
>         uint32_t b = s->size == 1 ? (*sp != 0) : (*(int *)sp != 0);
> @@ -406,7 +412,7 @@ int lj_cconv_tv_ct(CTState *cts, CType *s, CTypeID sid,
>       CTSize sz;
>     copyval:  /* Copy value. */
>       sz = s->size;
> -    lua_assert(sz != CTSIZE_INVALID);
> +    lj_assertCTS(sz != CTSIZE_INVALID, "value copy with invalid size");
>       /* Attributes are stripped, qualifiers are kept (but mostly ignored). */
>       cd = lj_cdata_new(cts, ctype_typeid(cts, s), sz);
>       setcdataV(cts->L, o, cd);
> @@ -421,19 +427,22 @@ int lj_cconv_tv_bf(CTState *cts, CType *s, TValue *o, uint8_t *sp)
>     CTInfo info = s->info;
>     CTSize pos, bsz;
>     uint32_t val;
> -  lua_assert(ctype_isbitfield(info));
> +  lj_assertCTS(ctype_isbitfield(info), "bitfield expected");
>     /* NYI: packed bitfields may cause misaligned reads. */
>     switch (ctype_bitcsz(info)) {
>     case 4: val = *(uint32_t *)sp; break;
>     case 2: val = *(uint16_t *)sp; break;
>     case 1: val = *(uint8_t *)sp; break;
> -  default: lua_assert(0); val = 0; break;
> +  default:
> +    lj_assertCTS(0, "bad bitfield container size %d", ctype_bitcsz(info));
> +    val = 0;
> +    break;
>     }
>     /* Check if a packed bitfield crosses a container boundary. */
>     pos = ctype_bitpos(info);
>     bsz = ctype_bitbsz(info);
> -  lua_assert(pos < 8*ctype_bitcsz(info));
> -  lua_assert(bsz > 0 && bsz <= 8*ctype_bitcsz(info));
> +  lj_assertCTS(pos < 8*ctype_bitcsz(info), "bad bitfield position");
> +  lj_assertCTS(bsz > 0 && bsz <= 8*ctype_bitcsz(info), "bad bitfield size");
>     if (pos + bsz > 8*ctype_bitcsz(info))
>       lj_err_caller(cts->L, LJ_ERR_FFI_NYIPACKBIT);
>     if (!(info & CTF_BOOL)) {
> @@ -449,7 +458,7 @@ int lj_cconv_tv_bf(CTState *cts, CType *s, TValue *o, uint8_t *sp)
>       }
>     } else {
>       uint32_t b = (val >> pos) & 1;
> -    lua_assert(bsz == 1);
> +    lj_assertCTS(bsz == 1, "bad bool bitfield size");
>       setboolV(o, b);
>       setboolV(&cts->g->tmptv2, b);  /* Remember for trace recorder. */
>     }
> @@ -553,7 +562,7 @@ void lj_cconv_ct_tv(CTState *cts, CType *d,
>       sid = cdataV(o)->ctypeid;
>       s = ctype_get(cts, sid);
>       if (ctype_isref(s->info)) {  /* Resolve reference for value. */
> -      lua_assert(s->size == CTSIZE_PTR);
> +      lj_assertCTS(s->size == CTSIZE_PTR, "ref is not pointer-sized");
>         sp = *(void **)sp;
>         sid = ctype_cid(s->info);
>       }
> @@ -571,7 +580,7 @@ void lj_cconv_ct_tv(CTState *cts, CType *d,
>         CType *cct = lj_ctype_getfield(cts, d, str, &ofs);
>         if (!cct || !ctype_isconstval(cct->info))
>   	goto err_conv;
> -      lua_assert(d->size == 4);
> +      lj_assertCTS(d->size == 4, "only 32 bit enum supported");  /* NYI */
>         sp = (uint8_t *)&cct->size;
>         sid = ctype_cid(cct->info);
>       } else if (ctype_isrefarray(d->info)) {  /* Copy string to array. */
> @@ -635,10 +644,10 @@ void lj_cconv_bf_tv(CTState *cts, CType *d, uint8_t *dp, TValue *o)
>     CTInfo info = d->info;
>     CTSize pos, bsz;
>     uint32_t val, mask;
> -  lua_assert(ctype_isbitfield(info));
> +  lj_assertCTS(ctype_isbitfield(info), "bitfield expected");
>     if ((info & CTF_BOOL)) {
>       uint8_t tmpbool;
> -    lua_assert(ctype_bitbsz(info) == 1);
> +    lj_assertCTS(ctype_bitbsz(info) == 1, "bad bool bitfield size");
>       lj_cconv_ct_tv(cts, ctype_get(cts, CTID_BOOL), &tmpbool, o, 0);
>       val = tmpbool;
>     } else {
> @@ -647,8 +656,8 @@ void lj_cconv_bf_tv(CTState *cts, CType *d, uint8_t *dp, TValue *o)
>     }
>     pos = ctype_bitpos(info);
>     bsz = ctype_bitbsz(info);
> -  lua_assert(pos < 8*ctype_bitcsz(info));
> -  lua_assert(bsz > 0 && bsz <= 8*ctype_bitcsz(info));
> +  lj_assertCTS(pos < 8*ctype_bitcsz(info), "bad bitfield position");
> +  lj_assertCTS(bsz > 0 && bsz <= 8*ctype_bitcsz(info), "bad bitfield size");
>     /* Check if a packed bitfield crosses a container boundary. */
>     if (pos + bsz > 8*ctype_bitcsz(info))
>       lj_err_caller(cts->L, LJ_ERR_FFI_NYIPACKBIT);
> @@ -659,7 +668,9 @@ void lj_cconv_bf_tv(CTState *cts, CType *d, uint8_t *dp, TValue *o)
>     case 4: *(uint32_t *)dp = (*(uint32_t *)dp & ~mask) | (uint32_t)val; break;
>     case 2: *(uint16_t *)dp = (*(uint16_t *)dp & ~mask) | (uint16_t)val; break;
>     case 1: *(uint8_t *)dp = (*(uint8_t *)dp & ~mask) | (uint8_t)val; break;
> -  default: lua_assert(0); break;
> +  default:
> +    lj_assertCTS(0, "bad bitfield container size %d", ctype_bitcsz(info));
> +    break;
>     }
>   }
>   
> diff --git a/src/lj_cconv.h b/src/lj_cconv.h
> index 0a0b66c9..54a61fd4 100644
> --- a/src/lj_cconv.h
> +++ b/src/lj_cconv.h
> @@ -27,13 +27,14 @@ enum {
>   static LJ_AINLINE uint32_t cconv_idx(CTInfo info)
>   {
>     uint32_t idx = ((info >> 26) & 15u);  /* Dispatch bits. */
> -  lua_assert(ctype_type(info) <= CT_MAYCONVERT);
> +  lj_assertX(ctype_type(info) <= CT_MAYCONVERT,
> +	     "cannot convert ctype %08x", info);
>   #if LJ_64
>     idx = ((uint32_t)(U64x(f436fff5,fff7f021) >> 4*idx) & 15u);
>   #else
>     idx = (((idx < 8 ? 0xfff7f021u : 0xf436fff5) >> 4*(idx & 7u)) & 15u);
>   #endif
> -  lua_assert(idx < 8);
> +  lj_assertX(idx < 8, "cannot convert ctype %08x", info);
>     return idx;
>   }
>   
> diff --git a/src/lj_cdata.c b/src/lj_cdata.c
> index d3042f24..35d0e76a 100644
> --- a/src/lj_cdata.c
> +++ b/src/lj_cdata.c
> @@ -35,7 +35,7 @@ GCcdata *lj_cdata_newv(lua_State *L, CTypeID id, CTSize sz, CTSize align)
>     uintptr_t adata = (uintptr_t)p + sizeof(GCcdataVar) + sizeof(GCcdata);
>     uintptr_t almask = (1u << align) - 1u;
>     GCcdata *cd = (GCcdata *)(((adata + almask) & ~almask) - sizeof(GCcdata));
> -  lua_assert((char *)cd - p < 65536);
> +  lj_assertL((char *)cd - p < 65536, "excessive cdata alignment");
>     cdatav(cd)->offset = (uint16_t)((char *)cd - p);
>     cdatav(cd)->extra = extra;
>     cdatav(cd)->len = sz;
> @@ -77,8 +77,8 @@ void LJ_FASTCALL lj_cdata_free(global_State *g, GCcdata *cd)
>     } else if (LJ_LIKELY(!cdataisv(cd))) {
>       CType *ct = ctype_raw(ctype_ctsG(g), cd->ctypeid);
>       CTSize sz = ctype_hassize(ct->info) ? ct->size : CTSIZE_PTR;
> -    lua_assert(ctype_hassize(ct->info) || ctype_isfunc(ct->info) ||
> -	       ctype_isextern(ct->info));
> +    lj_assertG(ctype_hassize(ct->info) || ctype_isfunc(ct->info) ||
> +	       ctype_isextern(ct->info), "free of ctype without a size");
>       lj_mem_free(g, cd, sizeof(GCcdata) + sz);
>       g->gc.cdatanum--;
>     } else {
> @@ -118,7 +118,7 @@ CType *lj_cdata_index(CTState *cts, GCcdata *cd, cTValue *key, uint8_t **pp,
>   
>     /* Resolve reference for cdata object. */
>     if (ctype_isref(ct->info)) {
> -    lua_assert(ct->size == CTSIZE_PTR);
> +    lj_assertCTS(ct->size == CTSIZE_PTR, "ref is not pointer-sized");
>       p = *(uint8_t **)p;
>       ct = ctype_child(cts, ct);
>     }
> @@ -129,7 +129,8 @@ collect_attrib:
>       if (ctype_attrib(ct->info) == CTA_QUAL) *qual |= ct->size;
>       ct = ctype_child(cts, ct);
>     }
> -  lua_assert(!ctype_isref(ct->info));  /* Interning rejects refs to refs. */
> +  /* Interning rejects refs to refs. */
> +  lj_assertCTS(!ctype_isref(ct->info), "bad ref of ref");
>   
>     if (tvisint(key)) {
>       idx = (ptrdiff_t)intV(key);
> @@ -215,7 +216,8 @@ collect_attrib:
>   static void cdata_getconst(CTState *cts, TValue *o, CType *ct)
>   {
>     CType *ctt = ctype_child(cts, ct);
> -  lua_assert(ctype_isinteger(ctt->info) && ctt->size <= 4);
> +  lj_assertCTS(ctype_isinteger(ctt->info) && ctt->size <= 4,
> +	       "only 32 bit const supported");  /* NYI */
>     /* Constants are already zero-extended/sign-extended to 32 bits. */
>     if ((ctt->info & CTF_UNSIGNED) && (int32_t)ct->size < 0)
>       setnumV(o, (lua_Number)(uint32_t)ct->size);
> @@ -236,13 +238,14 @@ int lj_cdata_get(CTState *cts, CType *s, TValue *o, uint8_t *sp)
>     }
>   
>     /* Get child type of pointer/array/field. */
> -  lua_assert(ctype_ispointer(s->info) || ctype_isfield(s->info));
> +  lj_assertCTS(ctype_ispointer(s->info) || ctype_isfield(s->info),
> +	       "pointer or field expected");
>     sid = ctype_cid(s->info);
>     s = ctype_get(cts, sid);
>   
>     /* Resolve reference for field. */
>     if (ctype_isref(s->info)) {
> -    lua_assert(s->size == CTSIZE_PTR);
> +    lj_assertCTS(s->size == CTSIZE_PTR, "ref is not pointer-sized");
>       sp = *(uint8_t **)sp;
>       sid = ctype_cid(s->info);
>       s = ctype_get(cts, sid);
> @@ -269,12 +272,13 @@ void lj_cdata_set(CTState *cts, CType *d, uint8_t *dp, TValue *o, CTInfo qual)
>     }
>   
>     /* Get child type of pointer/array/field. */
> -  lua_assert(ctype_ispointer(d->info) || ctype_isfield(d->info));
> +  lj_assertCTS(ctype_ispointer(d->info) || ctype_isfield(d->info),
> +	       "pointer or field expected");
>     d = ctype_child(cts, d);
>   
>     /* Resolve reference for field. */
>     if (ctype_isref(d->info)) {
> -    lua_assert(d->size == CTSIZE_PTR);
> +    lj_assertCTS(d->size == CTSIZE_PTR, "ref is not pointer-sized");
>       dp = *(uint8_t **)dp;
>       d = ctype_child(cts, d);
>     }
> @@ -289,7 +293,8 @@ void lj_cdata_set(CTState *cts, CType *d, uint8_t *dp, TValue *o, CTInfo qual)
>       d = ctype_child(cts, d);
>     }
>   
> -  lua_assert(ctype_hassize(d->info) && !ctype_isvoid(d->info));
> +  lj_assertCTS(ctype_hassize(d->info), "store to ctype without size");
> +  lj_assertCTS(!ctype_isvoid(d->info), "store to void type");
>   
>     if (((d->info|qual) & CTF_CONST)) {
>     err_const:
> diff --git a/src/lj_cdata.h b/src/lj_cdata.h
> index 66b023bd..193e4241 100644
> --- a/src/lj_cdata.h
> +++ b/src/lj_cdata.h
> @@ -18,7 +18,7 @@ static LJ_AINLINE void *cdata_getptr(void *p, CTSize sz)
>     if (LJ_64 && sz == 4) {  /* Support 32 bit pointers on 64 bit targets. */
>       return ((void *)(uintptr_t)*(uint32_t *)p);
>     } else {
> -    lua_assert(sz == CTSIZE_PTR);
> +    lj_assertX(sz == CTSIZE_PTR, "bad pointer size %d", sz);
>       return *(void **)p;
>     }
>   }
> @@ -29,7 +29,7 @@ static LJ_AINLINE void cdata_setptr(void *p, CTSize sz, const void *v)
>     if (LJ_64 && sz == 4) {  /* Support 32 bit pointers on 64 bit targets. */
>       *(uint32_t *)p = (uint32_t)(uintptr_t)v;
>     } else {
> -    lua_assert(sz == CTSIZE_PTR);
> +    lj_assertX(sz == CTSIZE_PTR, "bad pointer size %d", sz);
>       *(void **)p = (void *)v;
>     }
>   }
> @@ -40,7 +40,8 @@ static LJ_AINLINE GCcdata *lj_cdata_new(CTState *cts, CTypeID id, CTSize sz)
>     GCcdata *cd;
>   #ifdef LUA_USE_ASSERT
>     CType *ct = ctype_raw(cts, id);
> -  lua_assert((ctype_hassize(ct->info) ? ct->size : CTSIZE_PTR) == sz);
> +  lj_assertCTS((ctype_hassize(ct->info) ? ct->size : CTSIZE_PTR) == sz,
> +	       "inconsistent size of fixed-size cdata alloc");
>   #endif
>     cd = (GCcdata *)lj_mem_newgco(cts->L, sizeof(GCcdata) + sz);
>     cd->gct = ~LJ_TCDATA;
> diff --git a/src/lj_clib.c b/src/lj_clib.c
> index a8672052..2f11b2e9 100644
> --- a/src/lj_clib.c
> +++ b/src/lj_clib.c
> @@ -349,7 +349,8 @@ TValue *lj_clib_index(lua_State *L, CLibrary *cl, GCstr *name)
>         lj_err_callerv(L, LJ_ERR_FFI_NODECL, strdata(name));
>       if (ctype_isconstval(ct->info)) {
>         CType *ctt = ctype_child(cts, ct);
> -      lua_assert(ctype_isinteger(ctt->info) && ctt->size <= 4);
> +      lj_assertCTS(ctype_isinteger(ctt->info) && ctt->size <= 4,
> +		   "only 32 bit const supported");  /* NYI */
>         if ((ctt->info & CTF_UNSIGNED) && (int32_t)ct->size < 0)
>   	setnumV(tv, (lua_Number)(uint32_t)ct->size);
>         else
> @@ -361,7 +362,8 @@ TValue *lj_clib_index(lua_State *L, CLibrary *cl, GCstr *name)
>   #endif
>         void *p = clib_getsym(cl, sym);
>         GCcdata *cd;
> -      lua_assert(ctype_isfunc(ct->info) || ctype_isextern(ct->info));
> +      lj_assertCTS(ctype_isfunc(ct->info) || ctype_isextern(ct->info),
> +		   "unexpected ctype %08x in clib", ct->info);
>   #if LJ_TARGET_X86 && LJ_ABI_WIN
>         /* Retry with decorated name for fastcall/stdcall functions. */
>         if (!p && ctype_isfunc(ct->info)) {
> diff --git a/src/lj_cparse.c b/src/lj_cparse.c
> index cd032b8e..6d9490ca 100644
> --- a/src/lj_cparse.c
> +++ b/src/lj_cparse.c
> @@ -28,6 +28,12 @@
>   ** If in doubt, please check the input against your favorite C compiler.
>   */
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertCP(c, ...)	(lj_assertG_(G(cp->L), (c), __VA_ARGS__))
> +#else
> +#define lj_assertCP(c, ...)	((void)cp)
> +#endif
> +
>   /* -- Miscellaneous ------------------------------------------------------- */
>   
>   /* Match string against a C literal. */
> @@ -61,7 +67,7 @@ LJ_NORET static void cp_err(CPState *cp, ErrMsg em);
>   
>   static const char *cp_tok2str(CPState *cp, CPToken tok)
>   {
> -  lua_assert(tok < CTOK_FIRSTDECL);
> +  lj_assertCP(tok < CTOK_FIRSTDECL, "bad CPToken %d", tok);
>     if (tok > CTOK_OFS)
>       return ctoknames[tok-CTOK_OFS-1];
>     else if (!lj_char_iscntrl(tok))
> @@ -392,7 +398,7 @@ static void cp_init(CPState *cp)
>     cp->curpack = 0;
>     cp->packstack[0] = 255;
>     lj_buf_init(cp->L, &cp->sb);
> -  lua_assert(cp->p != NULL);
> +  lj_assertCP(cp->p != NULL, "uninitialized cp->p");
>     cp_get(cp);  /* Read-ahead first char. */
>     cp->tok = 0;
>     cp->tmask = CPNS_DEFAULT;
> @@ -853,12 +859,13 @@ static CTypeID cp_decl_intern(CPState *cp, CPDecl *decl)
>       /* The cid is already part of info for copies of pointers/functions. */
>       idx = ct->next;
>       if (ctype_istypedef(info)) {
> -      lua_assert(id == 0);
> +      lj_assertCP(id == 0, "typedef not at toplevel");
>         id = ctype_cid(info);
>         /* Always refetch info/size, since struct/enum may have been completed. */
>         cinfo = ctype_get(cp->cts, id)->info;
>         csize = ctype_get(cp->cts, id)->size;
> -      lua_assert(ctype_isstruct(cinfo) || ctype_isenum(cinfo));
> +      lj_assertCP(ctype_isstruct(cinfo) || ctype_isenum(cinfo),
> +		  "typedef of bad type");
>       } else if (ctype_isfunc(info)) {  /* Intern function. */
>         CType *fct;
>         CTypeID fid;
> @@ -891,7 +898,7 @@ static CTypeID cp_decl_intern(CPState *cp, CPDecl *decl)
>         /* Inherit csize/cinfo from original type. */
>       } else {
>         if (ctype_isnum(info)) {  /* Handle mode/vector-size attributes. */
> -	lua_assert(id == 0);
> +	lj_assertCP(id == 0, "number not at toplevel");
>   	if (!(info & CTF_BOOL)) {
>   	  CTSize msize = ctype_msizeP(decl->attr);
>   	  CTSize vsize = ctype_vsizeP(decl->attr);
> @@ -946,7 +953,7 @@ static CTypeID cp_decl_intern(CPState *cp, CPDecl *decl)
>   	  info = (info & ~CTF_ALIGN) | (cinfo & CTF_ALIGN);
>   	info |= (cinfo & CTF_QUAL);  /* Inherit qual. */
>         } else {
> -	lua_assert(ctype_isvoid(info));
> +	lj_assertCP(ctype_isvoid(info), "bad ctype %08x", info);
>         }
>         csize = size;
>         cinfo = info+id;
> @@ -1596,7 +1603,7 @@ end_decl:
>   	cp_errmsg(cp, cp->tok, LJ_ERR_FFI_DECLSPEC);
>         sz = sizeof(int);
>       }
> -    lua_assert(sz != 0);
> +    lj_assertCP(sz != 0, "basic ctype with zero size");
>       info += CTALIGN(lj_fls(sz));  /* Use natural alignment. */
>       info += (decl->attr & CTF_QUAL);  /* Merge qualifiers. */
>       cp_push(decl, info, sz);
> @@ -1856,7 +1863,7 @@ static void cp_decl_multi(CPState *cp)
>   	  /* Treat both static and extern function declarations as extern. */
>   	  ct = ctype_get(cp->cts, ctypeid);
>   	  /* We always get new anonymous functions (typedefs are copied). */
> -	  lua_assert(gcref(ct->name) == NULL);
> +	  lj_assertCP(gcref(ct->name) == NULL, "unexpected named function");
>   	  id = ctypeid;  /* Just name it. */
>   	} else if ((scl & CDF_STATIC)) {  /* Accept static constants. */
>   	  id = cp_decl_constinit(cp, &ct, ctypeid);
> @@ -1913,7 +1920,7 @@ static TValue *cpcparser(lua_State *L, lua_CFunction dummy, void *ud)
>       cp_decl_single(cp);
>     if (cp->param && cp->param != cp->L->top)
>       cp_err(cp, LJ_ERR_FFI_NUMPARAM);
> -  lua_assert(cp->depth == 0);
> +  lj_assertCP(cp->depth == 0, "unbalanced cparser declaration depth");
>     return NULL;
>   }
>   
> diff --git a/src/lj_crecord.c b/src/lj_crecord.c
> index 804cdbf4..e1d1110f 100644
> --- a/src/lj_crecord.c
> +++ b/src/lj_crecord.c
> @@ -61,7 +61,8 @@ static GCcdata *argv2cdata(jit_State *J, TRef tr, cTValue *o)
>   static CTypeID crec_constructor(jit_State *J, GCcdata *cd, TRef tr)
>   {
>     CTypeID id;
> -  lua_assert(tref_iscdata(tr) && cd->ctypeid == CTID_CTYPEID);
> +  lj_assertJ(tref_iscdata(tr) && cd->ctypeid == CTID_CTYPEID,
> +	     "expected CTypeID cdata");
>     id = *(CTypeID *)cdataptr(cd);
>     tr = emitir(IRT(IR_FLOAD, IRT_INT), tr, IRFL_CDATA_INT);
>     emitir(IRTG(IR_EQ, IRT_INT), tr, lj_ir_kint(J, (int32_t)id));
> @@ -237,13 +238,14 @@ static void crec_copy(jit_State *J, TRef trdst, TRef trsrc, TRef trlen,
>       if (len > CREC_COPY_MAXLEN) goto fallback;
>       if (ct) {
>         CTState *cts = ctype_ctsG(J2G(J));
> -      lua_assert(ctype_isarray(ct->info) || ctype_isstruct(ct->info));
> +      lj_assertJ(ctype_isarray(ct->info) || ctype_isstruct(ct->info),
> +		 "copy of non-aggregate");
>         if (ctype_isarray(ct->info)) {
>   	CType *cct = ctype_rawchild(cts, ct);
>   	tp = crec_ct2irt(cts, cct);
>   	if (tp == IRT_CDATA) goto rawcopy;
>   	step = lj_ir_type_size[tp];
> -	lua_assert((len & (step-1)) == 0);
> +	lj_assertJ((len & (step-1)) == 0, "copy of fractional size");
>         } else if ((ct->info & CTF_UNION)) {
>   	step = (1u << ctype_align(ct->info));
>   	goto rawcopy;
> @@ -629,7 +631,8 @@ static TRef crec_ct_tv(jit_State *J, CType *d, TRef dp, TRef sp, cTValue *sval)
>         /* Specialize to the name of the enum constant. */
>         emitir(IRTG(IR_EQ, IRT_STR), sp, lj_ir_kstr(J, str));
>         if (cct && ctype_isconstval(cct->info)) {
> -	lua_assert(ctype_child(cts, cct)->size == 4);
> +	lj_assertJ(ctype_child(cts, cct)->size == 4,
> +		   "only 32 bit const supported");  /* NYI */
>   	svisnz = (void *)(intptr_t)(ofs != 0);
>   	sp = lj_ir_kint(J, (int32_t)ofs);
>   	sid = ctype_cid(cct->info);
> @@ -756,7 +759,7 @@ static void crec_index_bf(jit_State *J, RecordFFData *rd, TRef ptr, CTInfo info)
>     IRType t = IRT_I8 + 2*lj_fls(ctype_bitcsz(info)) + ((info&CTF_UNSIGNED)?1:0);
>     TRef tr = emitir(IRT(IR_XLOAD, t), ptr, 0);
>     CTSize pos = ctype_bitpos(info), bsz = ctype_bitbsz(info), shift = 32 - bsz;
> -  lua_assert(t <= IRT_U32);  /* NYI: 64 bit bitfields. */
> +  lj_assertJ(t <= IRT_U32, "only 32 bit bitfields supported");  /* NYI */
>     if (rd->data == 0) {  /* __index metamethod. */
>       if ((info & CTF_BOOL)) {
>         tr = emitir(IRTI(IR_BAND), tr, lj_ir_kint(J, (int32_t)((1u << pos))));
> @@ -768,7 +771,7 @@ static void crec_index_bf(jit_State *J, RecordFFData *rd, TRef ptr, CTInfo info)
>         tr = emitir(IRTI(IR_BSHL), tr, lj_ir_kint(J, shift - pos));
>         tr = emitir(IRTI(IR_BSAR), tr, lj_ir_kint(J, shift));
>       } else {
> -      lua_assert(bsz < 32);  /* Full-size fields cannot end up here. */
> +      lj_assertJ(bsz < 32, "unexpected full bitfield index");
>         tr = emitir(IRTI(IR_BSHR), tr, lj_ir_kint(J, pos));
>         tr = emitir(IRTI(IR_BAND), tr, lj_ir_kint(J, (int32_t)((1u << bsz)-1)));
>         /* We can omit the U32 to NUM conversion, since bsz < 32. */
> @@ -883,7 +886,7 @@ again:
>   	  crec_index_bf(J, rd, ptr, fct->info);
>   	  return;
>   	} else {
> -	  lua_assert(ctype_isfield(fct->info));
> +	  lj_assertJ(ctype_isfield(fct->info), "field expected");
>   	  sid = ctype_cid(fct->info);
>   	}
>         }
> @@ -1133,7 +1136,7 @@ static TRef crec_call_args(jit_State *J, RecordFFData *rd,
>       if (fid) {  /* Get argument type from field. */
>         CType *ctf = ctype_get(cts, fid);
>         fid = ctf->sib;
> -      lua_assert(ctype_isfield(ctf->info));
> +      lj_assertJ(ctype_isfield(ctf->info), "field expected");
>         did = ctype_cid(ctf->info);
>       } else {
>         if (!(ct->info & CTF_VARARG))
> diff --git a/src/lj_ctype.c b/src/lj_ctype.c
> index 0ea89c74..a42e3d60 100644
> --- a/src/lj_ctype.c
> +++ b/src/lj_ctype.c
> @@ -153,7 +153,7 @@ CTypeID lj_ctype_new(CTState *cts, CType **ctp)
>   {
>     CTypeID id = cts->top;
>     CType *ct;
> -  lua_assert(cts->L);
> +  lj_assertCTS(cts->L, "uninitialized cts->L");
>     if (LJ_UNLIKELY(id >= cts->sizetab)) {
>       if (id >= CTID_MAX) lj_err_msg(cts->L, LJ_ERR_TABOV);
>   #ifdef LUAJIT_CTYPE_CHECK_ANCHOR
> @@ -182,7 +182,7 @@ CTypeID lj_ctype_intern(CTState *cts, CTInfo info, CTSize size)
>   {
>     uint32_t h = ct_hashtype(info, size);
>     CTypeID id = cts->hash[h];
> -  lua_assert(cts->L);
> +  lj_assertCTS(cts->L, "uninitialized cts->L");
>     while (id) {
>       CType *ct = ctype_get(cts, id);
>       if (ct->info == info && ct->size == size)
> @@ -298,9 +298,9 @@ CTSize lj_ctype_vlsize(CTState *cts, CType *ct, CTSize nelem)
>       }
>       ct = ctype_raw(cts, arrid);
>     }
> -  lua_assert(ctype_isvlarray(ct->info));  /* Must be a VLA. */
> +  lj_assertCTS(ctype_isvlarray(ct->info), "VLA expected");
>     ct = ctype_rawchild(cts, ct);  /* Get array element. */
> -  lua_assert(ctype_hassize(ct->info));
> +  lj_assertCTS(ctype_hassize(ct->info), "bad VLA without size");
>     /* Calculate actual size of VLA and check for overflow. */
>     xsz += (uint64_t)ct->size * nelem;
>     return xsz < 0x80000000u ? (CTSize)xsz : CTSIZE_INVALID;
> @@ -323,7 +323,8 @@ CTInfo lj_ctype_info(CTState *cts, CTypeID id, CTSize *szp)
>       } else {
>         if (!(qual & CTFP_ALIGNED)) qual |= (info & CTF_ALIGN);
>         qual |= (info & ~(CTF_ALIGN|CTMASK_CID));
> -      lua_assert(ctype_hassize(info) || ctype_isfunc(info));
> +      lj_assertCTS(ctype_hassize(info) || ctype_isfunc(info),
> +		   "ctype without size");
>         *szp = ctype_isfunc(info) ? CTSIZE_INVALID : ct->size;
>         break;
>       }
> @@ -528,7 +529,7 @@ static void ctype_repr(CTRepr *ctr, CTypeID id)
>         ctype_appc(ctr, ')');
>         break;
>       default:
> -      lua_assert(0);
> +      lj_assertG_(ctr->cts->g, 0, "bad ctype %08x", info);
>         break;
>       }
>       ct = ctype_get(ctr->cts, ctype_cid(info));
> diff --git a/src/lj_ctype.h b/src/lj_ctype.h
> index 0c220a88..c4f3bdde 100644
> --- a/src/lj_ctype.h
> +++ b/src/lj_ctype.h
> @@ -260,6 +260,12 @@ typedef struct CTState {
>   
>   #define CT_MEMALIGN	3	/* Alignment guaranteed by memory allocator. */
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertCTS(c, ...)	(lj_assertG_(cts->g, (c), __VA_ARGS__))
> +#else
> +#define lj_assertCTS(c, ...)	((void)cts)
> +#endif
> +
>   /* -- Predefined types ---------------------------------------------------- */
>   
>   /* Target-dependent types. */
> @@ -392,7 +398,8 @@ static LJ_AINLINE CTState *ctype_cts(lua_State *L)
>   /* Check C type ID for validity when assertions are enabled. */
>   static LJ_AINLINE CTypeID ctype_check(CTState *cts, CTypeID id)
>   {
> -  lua_assert(id > 0 && id < cts->top); UNUSED(cts);
> +  UNUSED(cts);
> +  lj_assertCTS(id > 0 && id < cts->top, "bad CTID %d", id);
>     return id;
>   }
>   
> @@ -408,8 +415,9 @@ static LJ_AINLINE CType *ctype_get(CTState *cts, CTypeID id)
>   /* Get child C type. */
>   static LJ_AINLINE CType *ctype_child(CTState *cts, CType *ct)
>   {
> -  lua_assert(!(ctype_isvoid(ct->info) || ctype_isstruct(ct->info) ||
> -	     ctype_isbitfield(ct->info)));  /* These don't have children. */
> +  lj_assertCTS(!(ctype_isvoid(ct->info) || ctype_isstruct(ct->info) ||
> +	       ctype_isbitfield(ct->info)),
> +	       "ctype %08x has no children", ct->info);
>     return ctype_get(cts, ctype_cid(ct->info));
>   }
>   
> diff --git a/src/lj_debug.c b/src/lj_debug.c
> index c4edcabb..46c442c6 100644
> --- a/src/lj_debug.c
> +++ b/src/lj_debug.c
> @@ -55,7 +55,8 @@ static BCPos debug_framepc(lua_State *L, GCfunc *fn, cTValue *nextframe)
>     const BCIns *ins;
>     GCproto *pt;
>     BCPos pos;
> -  lua_assert(fn->c.gct == ~LJ_TFUNC || fn->c.gct == ~LJ_TTHREAD);
> +  lj_assertL(fn->c.gct == ~LJ_TFUNC || fn->c.gct == ~LJ_TTHREAD,
> +	     "function or frame expected");
>     if (!isluafunc(fn)) {  /* Cannot derive a PC for non-Lua functions. */
>       return NO_BCPOS;
>     } else if (nextframe == NULL) {  /* Lua function on top. */
> @@ -101,7 +102,7 @@ static BCPos debug_framepc(lua_State *L, GCfunc *fn, cTValue *nextframe)
>   #if LJ_HASJIT
>     if (pos > pt->sizebc) {  /* Undo the effects of lj_trace_exit for JLOOP. */
>       GCtrace *T = (GCtrace *)((char *)(ins-1) - offsetof(GCtrace, startins));
> -    lua_assert(bc_isret(bc_op(ins[-1])));
> +    lj_assertL(bc_isret(bc_op(ins[-1])), "return bytecode expected");
>       pos = proto_bcpos(pt, mref(T->startpc, const BCIns));
>     }
>   #endif
> @@ -134,7 +135,7 @@ BCLine lj_debug_frameline(lua_State *L, GCfunc *fn, cTValue *nextframe)
>     BCPos pc = debug_framepc(L, fn, nextframe);
>     if (pc != NO_BCPOS) {
>       GCproto *pt = funcproto(fn);
> -    lua_assert(pc <= pt->sizebc);
> +    lj_assertL(pc <= pt->sizebc, "PC out of range");
>       return lj_debug_line(pt, pc);
>     }
>     return -1;
> @@ -215,7 +216,7 @@ static TValue *debug_localname(lua_State *L, const lua_Debug *ar,
>   const char *lj_debug_uvname(GCproto *pt, uint32_t idx)
>   {
>     const uint8_t *p = proto_uvinfo(pt);
> -  lua_assert(idx < pt->sizeuv);
> +  lj_assertX(idx < pt->sizeuv, "bad upvalue index");
>     if (!p) return "";
>     if (idx) while (*p++ || --idx) ;
>     return (const char *)p;
> @@ -440,13 +441,14 @@ int lj_debug_getinfo(lua_State *L, const char *what, lj_Debug *ar, int ext)
>     } else {
>       uint32_t offset = (uint32_t)ar->i_ci & 0xffff;
>       uint32_t size = (uint32_t)ar->i_ci >> 16;
> -    lua_assert(offset != 0);
> +    lj_assertL(offset != 0, "bad frame offset");
>       frame = tvref(L->stack) + offset;
>       if (size) nextframe = frame + size;
> -    lua_assert(frame <= tvref(L->maxstack) &&
> -	       (!nextframe || nextframe <= tvref(L->maxstack)));
> +    lj_assertL(frame <= tvref(L->maxstack) &&
> +	       (!nextframe || nextframe <= tvref(L->maxstack)),
> +	       "broken frame chain");
>       fn = frame_func(frame);
> -    lua_assert(fn->c.gct == ~LJ_TFUNC);
> +    lj_assertL(fn->c.gct == ~LJ_TFUNC, "bad frame function");
>     }
>     for (; *what; what++) {
>       if (*what == 'S') {
> diff --git a/src/lj_def.h b/src/lj_def.h
> index 2d8fff66..ba4dcc9d 100644
> --- a/src/lj_def.h
> +++ b/src/lj_def.h
> @@ -338,14 +338,28 @@ static LJ_AINLINE uint32_t lj_getu32(const void *v)
>   #define LJ_FUNCA_NORET	LJ_FUNCA LJ_NORET
>   #define LJ_ASMF_NORET	LJ_ASMF LJ_NORET
>   
> -/* Runtime assertions. */
> -#ifdef lua_assert
> -#define check_exp(c, e)		(lua_assert(c), (e))
> -#define api_check(l, e)		lua_assert(e)
> +/* Internal assertions. */
> +#if defined(LUA_USE_ASSERT) || defined(LUA_USE_APICHECK)
> +#define lj_assert_check(g, c, ...) \
> +  ((c) ? (void)0 : \
> +   (lj_assert_fail((g), __FILE__, __LINE__, __func__, __VA_ARGS__), 0))
> +#define lj_checkapi(c, ...)	lj_assert_check(G(L), (c), __VA_ARGS__)
>   #else
> -#define lua_assert(c)		((void)0)
> +#define lj_checkapi(c, ...)	((void)L)
> +#endif
> +
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertG_(g, c, ...)	lj_assert_check((g), (c), __VA_ARGS__)
> +#define lj_assertG(c, ...)	lj_assert_check(g, (c), __VA_ARGS__)
> +#define lj_assertL(c, ...)	lj_assert_check(G(L), (c), __VA_ARGS__)
> +#define lj_assertX(c, ...)	lj_assert_check(NULL, (c), __VA_ARGS__)
> +#define check_exp(c, e)		(lj_assertX((c), #c), (e))
> +#else
> +#define lj_assertG_(g, c, ...)	((void)0)
> +#define lj_assertG(c, ...)	((void)g)
> +#define lj_assertL(c, ...)	((void)L)
> +#define lj_assertX(c, ...)	((void)0)
>   #define check_exp(c, e)		(e)
> -#define api_check		luai_apicheck
>   #endif
>   
>   /* Static assertions. */
> diff --git a/src/lj_dispatch.c b/src/lj_dispatch.c
> index ee735450..ddee68de 100644
> --- a/src/lj_dispatch.c
> +++ b/src/lj_dispatch.c
> @@ -380,7 +380,7 @@ static void callhook(lua_State *L, int event, BCLine line)
>       hook_enter(g);
>   #endif
>       hookf(L, &ar);
> -    lua_assert(hook_active(g));
> +    lj_assertG(hook_active(g), "active hook flag removed");
>       setgcref(g->cur_L, obj2gco(L));
>   #if LJ_HASPROFILE && !LJ_PROFILE_SIGPROF
>       lj_profile_hook_leave(g);
> @@ -428,7 +428,8 @@ void LJ_FASTCALL lj_dispatch_ins(lua_State *L, const BCIns *pc)
>   #endif
>         J->L = L;
>         lj_trace_ins(J, pc-1);  /* The interpreter bytecode PC is offset by 1. */
> -      lua_assert(L->top - L->base == delta);
> +      lj_assertG(L->top - L->base == delta,
> +		 "unbalanced stack after tracing of instruction");
>       }
>     }
>   #endif
> @@ -488,7 +489,8 @@ ASMFunction LJ_FASTCALL lj_dispatch_call(lua_State *L, const BCIns *pc)
>   #endif
>       pc = (const BCIns *)((uintptr_t)pc & ~(uintptr_t)1);
>       lj_trace_hot(J, pc);
> -    lua_assert(L->top - L->base == delta);
> +    lj_assertG(L->top - L->base == delta,
> +	       "unbalanced stack after hot call");
>       goto out;
>     } else if (J->state != LJ_TRACE_IDLE &&
>   	     !(g->hookmask & (HOOK_GC|HOOK_VMEVENT))) {
> @@ -497,7 +499,8 @@ ASMFunction LJ_FASTCALL lj_dispatch_call(lua_State *L, const BCIns *pc)
>   #endif
>       /* Record the FUNC* bytecodes, too. */
>       lj_trace_ins(J, pc-1);  /* The interpreter bytecode PC is offset by 1. */
> -    lua_assert(L->top - L->base == delta);
> +    lj_assertG(L->top - L->base == delta,
> +	       "unbalanced stack after hot instruction");
>     }
>   #endif
>     if ((g->hookmask & LUA_MASKCALL)) {
> diff --git a/src/lj_emit_arm.h b/src/lj_emit_arm.h
> index dee8bdcc..ee299821 100644
> --- a/src/lj_emit_arm.h
> +++ b/src/lj_emit_arm.h
> @@ -81,7 +81,8 @@ static void emit_m(ASMState *as, ARMIns ai, Reg rm)
>   
>   static void emit_lsox(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
>   {
> -  lua_assert(ofs >= -255 && ofs <= 255);
> +  lj_assertA(ofs >= -255 && ofs <= 255,
> +	     "load/store offset %d out of range", ofs);
>     if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
>     *--as->mcp = ai | ARMI_LS_P | ARMI_LSX_I | ARMF_D(rd) | ARMF_N(rn) |
>   	       ((ofs & 0xf0) << 4) | (ofs & 0x0f);
> @@ -89,7 +90,8 @@ static void emit_lsox(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
>   
>   static void emit_lso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
>   {
> -  lua_assert(ofs >= -4095 && ofs <= 4095);
> +  lj_assertA(ofs >= -4095 && ofs <= 4095,
> +	     "load/store offset %d out of range", ofs);
>     /* Combine LDR/STR pairs to LDRD/STRD. */
>     if (*as->mcp == (ai|ARMI_LS_P|ARMI_LS_U|ARMF_D(rd^1)|ARMF_N(rn)|(ofs^4)) &&
>         (ai & ~(ARMI_LDR^ARMI_STR)) == ARMI_STR && rd != rn &&
> @@ -106,7 +108,8 @@ static void emit_lso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
>   #if !LJ_SOFTFP
>   static void emit_vlso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
>   {
> -  lua_assert(ofs >= -1020 && ofs <= 1020 && (ofs&3) == 0);
> +  lj_assertA(ofs >= -1020 && ofs <= 1020 && (ofs&3) == 0,
> +	     "load/store offset %d out of range", ofs);
>     if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
>     *--as->mcp = ai | ARMI_LS_P | ARMF_D(rd & 15) | ARMF_N(rn) | (ofs >> 2);
>   }
> @@ -124,7 +127,7 @@ static int emit_kdelta1(ASMState *as, Reg d, int32_t i)
>     while (work) {
>       Reg r = rset_picktop(work);
>       IRRef ref = regcost_ref(as->cost[r]);
> -    lua_assert(r != d);
> +    lj_assertA(r != d, "dest reg not free");
>       if (emit_canremat(ref)) {
>         int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
>         uint32_t k = emit_isk12(ARMI_ADD, delta);
> @@ -142,13 +145,13 @@ static int emit_kdelta1(ASMState *as, Reg d, int32_t i)
>   }
>   
>   /* Try to find a two step delta relative to another constant. */
> -static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
> +static int emit_kdelta2(ASMState *as, Reg rd, int32_t i)
>   {
>     RegSet work = ~as->freeset & RSET_GPR;
>     while (work) {
>       Reg r = rset_picktop(work);
>       IRRef ref = regcost_ref(as->cost[r]);
> -    lua_assert(r != d);
> +    lj_assertA(r != rd, "dest reg %d not free", rd);
>       if (emit_canremat(ref)) {
>         int32_t other = ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i;
>         if (other) {
> @@ -159,8 +162,8 @@ static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
>   	k2 = emit_isk12(0, delta & (255 << sh));
>   	k = emit_isk12(0, delta & ~(255 << sh));
>   	if (k) {
> -	  emit_dn(as, ARMI_ADD^k2^inv, d, d);
> -	  emit_dn(as, ARMI_ADD^k^inv, d, r);
> +	  emit_dn(as, ARMI_ADD^k2^inv, rd, rd);
> +	  emit_dn(as, ARMI_ADD^k^inv, rd, r);
>   	  return 1;
>   	}
>         }
> @@ -171,23 +174,24 @@ static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
>   }
>   
>   /* Load a 32 bit constant into a GPR. */
> -static void emit_loadi(ASMState *as, Reg r, int32_t i)
> +static void emit_loadi(ASMState *as, Reg rd, int32_t i)
>   {
>     uint32_t k = emit_isk12(ARMI_MOV, i);
> -  lua_assert(rset_test(as->freeset, r) || r == RID_TMP);
> +  lj_assertA(rset_test(as->freeset, rd) || rd == RID_TMP,
> +	     "dest reg %d not free", rd);
>     if (k) {
>       /* Standard K12 constant. */
> -    emit_d(as, ARMI_MOV^k, r);
> +    emit_d(as, ARMI_MOV^k, rd);
>     } else if ((as->flags & JIT_F_ARMV6T2) && (uint32_t)i < 0x00010000u) {
>       /* 16 bit loword constant for ARMv6T2. */
> -    emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
> -  } else if (emit_kdelta1(as, r, i)) {
> +    emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), rd);
> +  } else if (emit_kdelta1(as, rd, i)) {
>       /* One step delta relative to another constant. */
>     } else if ((as->flags & JIT_F_ARMV6T2)) {
>       /* 32 bit hiword/loword constant for ARMv6T2. */
> -    emit_d(as, ARMI_MOVT|((i>>16) & 0x0fff)|(((i>>16) & 0xf000)<<4), r);
> -    emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
> -  } else if (emit_kdelta2(as, r, i)) {
> +    emit_d(as, ARMI_MOVT|((i>>16) & 0x0fff)|(((i>>16) & 0xf000)<<4), rd);
> +    emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), rd);
> +  } else if (emit_kdelta2(as, rd, i)) {
>       /* Two step delta relative to another constant. */
>     } else {
>       /* Otherwise construct the constant with up to 4 instructions. */
> @@ -197,15 +201,15 @@ static void emit_loadi(ASMState *as, Reg r, int32_t i)
>         int32_t m = i & (255 << sh);
>         i &= ~(255 << sh);
>         if (i == 0) {
> -	emit_d(as, ARMI_MOV ^ emit_isk12(0, m), r);
> +	emit_d(as, ARMI_MOV ^ emit_isk12(0, m), rd);
>   	break;
>         }
> -      emit_dn(as, ARMI_ORR ^ emit_isk12(0, m), r, r);
> +      emit_dn(as, ARMI_ORR ^ emit_isk12(0, m), rd, rd);
>       }
>     }
>   }
>   
> -#define emit_loada(as, r, addr)		emit_loadi(as, (r), i32ptr((addr)))
> +#define emit_loada(as, rd, addr)	emit_loadi(as, (rd), i32ptr((addr)))
>   
>   static Reg ra_allock(ASMState *as, intptr_t k, RegSet allow);
>   
> @@ -261,7 +265,7 @@ static void emit_branch(ASMState *as, ARMIns ai, MCode *target)
>   {
>     MCode *p = as->mcp;
>     ptrdiff_t delta = (target - p) - 1;
> -  lua_assert(((delta + 0x00800000) >> 24) == 0);
> +  lj_assertA(((delta + 0x00800000) >> 24) == 0, "branch target out of range");
>     *--p = ai | ((uint32_t)delta & 0x00ffffffu);
>     as->mcp = p;
>   }
> @@ -289,7 +293,7 @@ static void emit_call(ASMState *as, void *target)
>   static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
>   {
>   #if LJ_SOFTFP
> -  lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
> +  lj_assertA(!irt_isnum(ir->t), "unexpected FP op"); UNUSED(ir);
>   #else
>     if (dst >= RID_MAX_GPR) {
>       emit_dm(as, irt_isnum(ir->t) ? ARMI_VMOV_D : ARMI_VMOV_S,
> @@ -313,7 +317,7 @@ static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
>   static void emit_loadofs(ASMState *as, IRIns *ir, Reg r, Reg base, int32_t ofs)
>   {
>   #if LJ_SOFTFP
> -  lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
> +  lj_assertA(!irt_isnum(ir->t), "unexpected FP op"); UNUSED(ir);
>   #else
>     if (r >= RID_MAX_GPR)
>       emit_vlso(as, irt_isnum(ir->t) ? ARMI_VLDR_D : ARMI_VLDR_S, r, base, ofs);
> @@ -326,7 +330,7 @@ static void emit_loadofs(ASMState *as, IRIns *ir, Reg r, Reg base, int32_t ofs)
>   static void emit_storeofs(ASMState *as, IRIns *ir, Reg r, Reg base, int32_t ofs)
>   {
>   #if LJ_SOFTFP
> -  lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
> +  lj_assertA(!irt_isnum(ir->t), "unexpected FP op"); UNUSED(ir);
>   #else
>     if (r >= RID_MAX_GPR)
>       emit_vlso(as, irt_isnum(ir->t) ? ARMI_VSTR_D : ARMI_VSTR_S, r, base, ofs);
> diff --git a/src/lj_emit_arm64.h b/src/lj_emit_arm64.h
> index 1001b1d8..96fbab72 100644
> --- a/src/lj_emit_arm64.h
> +++ b/src/lj_emit_arm64.h
> @@ -8,8 +8,9 @@
>   
>   /* -- Constant encoding --------------------------------------------------- */
>   
> -static uint64_t get_k64val(IRIns *ir)
> +static uint64_t get_k64val(ASMState *as, IRRef ref)
>   {
> +  IRIns *ir = IR(ref);
>     if (ir->o == IR_KINT64) {
>       return ir_kint64(ir)->u64;
>     } else if (ir->o == IR_KGC) {
> @@ -17,7 +18,8 @@ static uint64_t get_k64val(IRIns *ir)
>     } else if (ir->o == IR_KPTR || ir->o == IR_KKPTR) {
>       return (uint64_t)ir_kptr(ir);
>     } else {
> -    lua_assert(ir->o == IR_KINT || ir->o == IR_KNULL);
> +    lj_assertA(ir->o == IR_KINT || ir->o == IR_KNULL,
> +	       "bad 64 bit const IR op %d", ir->o);
>       return ir->i;  /* Sign-extended. */
>     }
>   }
> @@ -122,7 +124,7 @@ static int emit_checkofs(A64Ins ai, int64_t ofs)
>   static void emit_lso(ASMState *as, A64Ins ai, Reg rd, Reg rn, int64_t ofs)
>   {
>     int ot = emit_checkofs(ai, ofs), sc = (ai >> 30) & 3;
> -  lua_assert(ot);
> +  lj_assertA(ot, "load/store offset %d out of range", ofs);
>     /* Combine LDR/STR pairs to LDP/STP. */
>     if ((sc == 2 || sc == 3) &&
>         (!(ai & 0x400000) || rd != rn) &&
> @@ -166,10 +168,10 @@ static int emit_kdelta(ASMState *as, Reg rd, uint64_t k, int lim)
>     while (work) {
>       Reg r = rset_picktop(work);
>       IRRef ref = regcost_ref(as->cost[r]);
> -    lua_assert(r != rd);
> +    lj_assertA(r != rd, "dest reg %d not free", rd);
>       if (ref < REF_TRUE) {
>         uint64_t kx = ra_iskref(ref) ? (uint64_t)ra_krefk(as, ref) :
> -				     get_k64val(IR(ref));
> +				     get_k64val(as, ref);
>         int64_t delta = (int64_t)(k - kx);
>         if (delta == 0) {
>   	emit_dm(as, A64I_MOVx, rd, r);
> @@ -312,7 +314,7 @@ static void emit_cond_branch(ASMState *as, A64CC cond, MCode *target)
>   {
>     MCode *p = --as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(A64F_S_OK(delta, 19));
> +  lj_assertA(A64F_S_OK(delta, 19), "branch target out of range");
>     *p = A64I_BCC | A64F_S19(delta) | cond;
>   }
>   
> @@ -320,7 +322,7 @@ static void emit_branch(ASMState *as, A64Ins ai, MCode *target)
>   {
>     MCode *p = --as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(A64F_S_OK(delta, 26));
> +  lj_assertA(A64F_S_OK(delta, 26), "branch target out of range");
>     *p = ai | A64F_S26(delta);
>   }
>   
> @@ -328,7 +330,8 @@ static void emit_tnb(ASMState *as, A64Ins ai, Reg r, uint32_t bit, MCode *target
>   {
>     MCode *p = --as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(bit < 63 && A64F_S_OK(delta, 14));
> +  lj_assertA(bit < 63, "bit number out of range");
> +  lj_assertA(A64F_S_OK(delta, 14), "branch target out of range");
>     if (bit > 31) ai |= A64I_X;
>     *p = ai | A64F_BIT(bit & 31) | A64F_S14(delta) | r;
>   }
> @@ -337,7 +340,7 @@ static void emit_cnb(ASMState *as, A64Ins ai, Reg r, MCode *target)
>   {
>     MCode *p = --as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(A64F_S_OK(delta, 19));
> +  lj_assertA(A64F_S_OK(delta, 19), "branch target out of range");
>     *p = ai | A64F_S19(delta) | r;
>   }
>   
> diff --git a/src/lj_emit_mips.h b/src/lj_emit_mips.h
> index 313d030a..7f0d27ca 100644
> --- a/src/lj_emit_mips.h
> +++ b/src/lj_emit_mips.h
> @@ -4,8 +4,9 @@
>   */
>   
>   #if LJ_64
> -static intptr_t get_k64val(IRIns *ir)
> +static intptr_t get_k64val(ASMState *as, IRRef ref)
>   {
> +  IRIns *ir = IR(ref);
>     if (ir->o == IR_KINT64) {
>       return (intptr_t)ir_kint64(ir)->u64;
>     } else if (ir->o == IR_KGC) {
> @@ -15,16 +16,17 @@ static intptr_t get_k64val(IRIns *ir)
>     } else if (LJ_SOFTFP && ir->o == IR_KNUM) {
>       return (intptr_t)ir_knum(ir)->u64;
>     } else {
> -    lua_assert(ir->o == IR_KINT || ir->o == IR_KNULL);
> +    lj_assertA(ir->o == IR_KINT || ir->o == IR_KNULL,
> +	       "bad 64 bit const IR op %d", ir->o);
>       return ir->i;  /* Sign-extended. */
>     }
>   }
>   #endif
>   
>   #if LJ_64
> -#define get_kval(ir)		get_k64val(ir)
> +#define get_kval(as, ref)	get_k64val(as, ref)
>   #else
> -#define get_kval(ir)		((ir)->i)
> +#define get_kval(as, ref)	(IR((ref))->i)
>   #endif
>   
>   /* -- Emit basic instructions --------------------------------------------- */
> @@ -82,18 +84,18 @@ static void emit_tsml(ASMState *as, MIPSIns mi, Reg rt, Reg rs, uint32_t msb,
>   #define emit_canremat(ref)	((ref) <= REF_BASE)
>   
>   /* Try to find a one step delta relative to another constant. */
> -static int emit_kdelta1(ASMState *as, Reg t, intptr_t i)
> +static int emit_kdelta1(ASMState *as, Reg rd, intptr_t i)
>   {
>     RegSet work = ~as->freeset & RSET_GPR;
>     while (work) {
>       Reg r = rset_picktop(work);
>       IRRef ref = regcost_ref(as->cost[r]);
> -    lua_assert(r != t);
> +    lj_assertA(r != rd, "dest reg %d not free", rd);
>       if (ref < ASMREF_L) {
>         intptr_t delta = (intptr_t)((uintptr_t)i -
> -	(uintptr_t)(ra_iskref(ref) ? ra_krefk(as, ref) : get_kval(IR(ref))));
> +	(uintptr_t)(ra_iskref(ref) ? ra_krefk(as, ref) : get_kval(as, ref)));
>         if (checki16(delta)) {
> -	emit_tsi(as, MIPSI_AADDIU, t, r, delta);
> +	emit_tsi(as, MIPSI_AADDIU, rd, r, delta);
>   	return 1;
>         }
>       }
> @@ -223,7 +225,7 @@ static void emit_branch(ASMState *as, MIPSIns mi, Reg rs, Reg rt, MCode *target)
>   {
>     MCode *p = as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(((delta + 0x8000) >> 16) == 0);
> +  lj_assertA(((delta + 0x8000) >> 16) == 0, "branch target out of range");
>     *--p = mi | MIPSF_S(rs) | MIPSF_T(rt) | ((uint32_t)delta & 0xffffu);
>     as->mcp = p;
>   }
> @@ -299,7 +301,7 @@ static void emit_storeofs(ASMState *as, IRIns *ir, Reg r, Reg base, int32_t ofs)
>   static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
>   {
>     if (ofs) {
> -    lua_assert(checki16(ofs));
> +    lj_assertA(checki16(ofs), "offset %d out of range", ofs);
>       emit_tsi(as, MIPSI_AADDIU, r, r, ofs);
>     }
>   }
> diff --git a/src/lj_emit_ppc.h b/src/lj_emit_ppc.h
> index 21c3c2ac..ddc864cd 100644
> --- a/src/lj_emit_ppc.h
> +++ b/src/lj_emit_ppc.h
> @@ -41,13 +41,13 @@ static void emit_rot(ASMState *as, PPCIns pi, Reg ra, Reg rs,
>   
>   static void emit_slwi(ASMState *as, Reg ra, Reg rs, int32_t n)
>   {
> -  lua_assert(n >= 0 && n < 32);
> +  lj_assertA(n >= 0 && n < 32, "shift out or range");
>     emit_rot(as, PPCI_RLWINM, ra, rs, n, 0, 31-n);
>   }
>   
>   static void emit_rotlwi(ASMState *as, Reg ra, Reg rs, int32_t n)
>   {
> -  lua_assert(n >= 0 && n < 32);
> +  lj_assertA(n >= 0 && n < 32, "shift out or range");
>     emit_rot(as, PPCI_RLWINM, ra, rs, n, 0, 31);
>   }
>   
> @@ -57,17 +57,17 @@ static void emit_rotlwi(ASMState *as, Reg ra, Reg rs, int32_t n)
>   #define emit_canremat(ref)	((ref) <= REF_BASE)
>   
>   /* Try to find a one step delta relative to another constant. */
> -static int emit_kdelta1(ASMState *as, Reg t, int32_t i)
> +static int emit_kdelta1(ASMState *as, Reg rd, int32_t i)
>   {
>     RegSet work = ~as->freeset & RSET_GPR;
>     while (work) {
>       Reg r = rset_picktop(work);
>       IRRef ref = regcost_ref(as->cost[r]);
> -    lua_assert(r != t);
> +    lj_assertA(r != rd, "dest reg %d not free", rd);
>       if (ref < ASMREF_L) {
>         int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
>         if (checki16(delta)) {
> -	emit_tai(as, PPCI_ADDI, t, r, delta);
> +	emit_tai(as, PPCI_ADDI, rd, r, delta);
>   	return 1;
>         }
>       }
> @@ -144,7 +144,7 @@ static void emit_condbranch(ASMState *as, PPCIns pi, PPCCC cc, MCode *target)
>   {
>     MCode *p = --as->mcp;
>     ptrdiff_t delta = (char *)target - (char *)p;
> -  lua_assert(((delta + 0x8000) >> 16) == 0);
> +  lj_assertA(((delta + 0x8000) >> 16) == 0, "branch target out of range");
>     pi ^= (delta & 0x8000) * (PPCF_Y/0x8000);
>     *p = pi | PPCF_CC(cc) | ((uint32_t)delta & 0xffffu);
>   }
> diff --git a/src/lj_emit_x86.h b/src/lj_emit_x86.h
> index b3dc4ea5..eaef17fc 100644
> --- a/src/lj_emit_x86.h
> +++ b/src/lj_emit_x86.h
> @@ -92,7 +92,7 @@ static void emit_rr(ASMState *as, x86Op xo, Reg r1, Reg r2)
>   /* [addr] is sign-extended in x64 and must be in lower 2G (not 4G). */
>   static int32_t ptr2addr(const void *p)
>   {
> -  lua_assert((uintptr_t)p < (uintptr_t)0x80000000);
> +  lj_assertX((uintptr_t)p < (uintptr_t)0x80000000, "pointer outside 2G range");
>     return i32ptr(p);
>   }
>   #else
> @@ -208,7 +208,7 @@ static void emit_mrm(ASMState *as, x86Op xo, Reg rr, Reg rb)
>         rb = RID_ESP;
>   #endif
>       } else if (LJ_GC64 && rb == RID_RIP) {
> -      lua_assert(as->mrm.idx == RID_NONE);
> +      lj_assertA(as->mrm.idx == RID_NONE, "RIP-rel mrm cannot have index");
>         mode = XM_OFS0;
>         p -= 4;
>         *(int32_t *)p = as->mrm.ofs;
> @@ -401,7 +401,8 @@ static void emit_loadk64(ASMState *as, Reg r, IRIns *ir)
>       emit_rma(as, xo, r64, k);
>     } else {
>       if (ir->i) {
> -      lua_assert(*k == *(uint64_t*)(as->mctop - ir->i));
> +      lj_assertA(*k == *(uint64_t*)(as->mctop - ir->i),
> +		 "bad interned 64 bit constant");
>       } else if (as->curins <= as->stopins && rset_test(RSET_GPR, r)) {
>         emit_loadu64(as, r, *k);
>         return;
> @@ -433,7 +434,7 @@ static void emit_sjmp(ASMState *as, MCLabel target)
>   {
>     MCode *p = as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(delta == (int8_t)delta);
> +  lj_assertA(delta == (int8_t)delta, "short jump target out of range");
>     p[-1] = (MCode)(int8_t)delta;
>     p[-2] = XI_JMPs;
>     as->mcp = p - 2;
> @@ -445,7 +446,7 @@ static void emit_sjcc(ASMState *as, int cc, MCLabel target)
>   {
>     MCode *p = as->mcp;
>     ptrdiff_t delta = target - p;
> -  lua_assert(delta == (int8_t)delta);
> +  lj_assertA(delta == (int8_t)delta, "short jump target out of range");
>     p[-1] = (MCode)(int8_t)delta;
>     p[-2] = (MCode)(XI_JCCs+(cc&15));
>     as->mcp = p - 2;
> @@ -471,10 +472,11 @@ static void emit_sfixup(ASMState *as, MCLabel source)
>   #define emit_label(as)		((as)->mcp)
>   
>   /* Compute relative 32 bit offset for jump and call instructions. */
> -static LJ_AINLINE int32_t jmprel(MCode *p, MCode *target)
> +static LJ_AINLINE int32_t jmprel(jit_State *J, MCode *p, MCode *target)
>   {
>     ptrdiff_t delta = target - p;
> -  lua_assert(delta == (int32_t)delta);
> +  UNUSED(J);
> +  lj_assertJ(delta == (int32_t)delta, "jump target out of range");
>     return (int32_t)delta;
>   }
>   
> @@ -482,7 +484,7 @@ static LJ_AINLINE int32_t jmprel(MCode *p, MCode *target)
>   static void emit_jcc(ASMState *as, int cc, MCode *target)
>   {
>     MCode *p = as->mcp;
> -  *(int32_t *)(p-4) = jmprel(p, target);
> +  *(int32_t *)(p-4) = jmprel(as->J, p, target);
>     p[-5] = (MCode)(XI_JCCn+(cc&15));
>     p[-6] = 0x0f;
>     as->mcp = p - 6;
> @@ -492,7 +494,7 @@ static void emit_jcc(ASMState *as, int cc, MCode *target)
>   static void emit_jmp(ASMState *as, MCode *target)
>   {
>     MCode *p = as->mcp;
> -  *(int32_t *)(p-4) = jmprel(p, target);
> +  *(int32_t *)(p-4) = jmprel(as->J, p, target);
>     p[-5] = XI_JMP;
>     as->mcp = p - 5;
>   }
> @@ -509,7 +511,7 @@ static void emit_call_(ASMState *as, MCode *target)
>       return;
>     }
>   #endif
> -  *(int32_t *)(p-4) = jmprel(p, target);
> +  *(int32_t *)(p-4) = jmprel(as->J, p, target);
>     p[-5] = XI_CALL;
>     as->mcp = p - 5;
>   }
> diff --git a/src/lj_err.c b/src/lj_err.c
> index 8d7134d9..89c51e98 100644
> --- a/src/lj_err.c
> +++ b/src/lj_err.c
> @@ -483,17 +483,10 @@ void lj_err_verify(void)
>   #if !LJ_TARGET_OSX
>     /* Check disabled on MacOS due to brilliant software engineering at Apple. */
>     struct dwarf_eh_bases ehb;
> -  /*
> -  ** FIXME: The following assertions were replaced with
> -  ** the conventional `lua_assert` ones.
> -  **
> -  ** lj_assertX(_Unwind_Find_FDE((void *)lj_err_throw, &ehb), "broken build: external frame unwinding enabled, but missing -funwind-tables");
> -  ** lj_assertX(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb), "broken build: external frame unwinding enabled, but system libraries have no unwind tables");
> -  */
> -  lua_assert(_Unwind_Find_FDE((void *)lj_err_throw, &ehb));
> +  lj_assertX(_Unwind_Find_FDE((void *)lj_err_throw, &ehb), "broken build: external frame unwinding enabled, but missing -funwind-tables");
>   #endif
>     /* Check disabled, because of broken Fedora/ARM64. See #722.
> -  lua_assert(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb));
> +  lj_assertX(_Unwind_Find_FDE((void *)_Unwind_RaiseException, &ehb), "broken build: external frame unwinding enabled, but system libraries have no unwind tables");
>     */
>   }
>   #endif
> @@ -514,13 +507,7 @@ static int err_unwind_jit(int version, int actions,
>       ExitNo exitno;
>       uintptr_t addr = _Unwind_GetIP(ctx);  /* Return address _after_ call. */
>       uintptr_t stub = lj_trace_unwind(G2J(g), addr - sizeof(MCode), &exitno);
> -    /*
> -    ** FIXME: The following assert was replaced with
> -    ** the conventional `lua_assert`.
> -    **
> -    ** lj_assertG(tvref(g->jit_base), "unexpected throw across mcode frame");
> -    */
> -    lua_assert(tvref(g->jit_base));
> +    lj_assertG(tvref(g->jit_base), "unexpected throw across mcode frame");
>       if (stub) {  /* Jump to side exit to unwind the trace. */
>         G2J(g)->exitcode = LJ_UEXCLASS_ERRCODE(uexclass);
>   #ifdef LJ_TARGET_MIPS
> @@ -603,15 +590,8 @@ uint8_t *lj_err_register_mcode(void *base, size_t sz, uint8_t *info)
>   #ifdef LUA_USE_ASSERT
>     {
>       struct dwarf_eh_bases ehb;
> -    /*
> -    ** FIXME: The following assert was replaced with
> -    ** the conventional `lua_assert`.
> -    **
> -    ** lj_assertX(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1, &ehb),
> -    **      "bad JIT unwind table registration");
> -    */
> -    lua_assert(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1,
> -               &ehb));
> +    lj_assertX(_Unwind_Find_FDE(info + sizeof(err_frame_jit_template)+1, &ehb),
> +	       "bad JIT unwind table registration");
>     }
>   #endif
>     return info + sizeof(err_frame_jit_template);
> @@ -716,13 +696,7 @@ void lj_err_verify(void)
>   {
>     int got = 0;
>     _Unwind_Backtrace((_Unwind_Trace_Fn)err_verify_bt, &got);
> -  /*
> -  ** FIXME: The following assert was replaced with
> -  ** the conventional `lua_assert`.
> -  **
> -  ** lj_assertX(got == 2, "broken build: external frame unwinding enabled, but missing -funwind-tables");
> -  */
> -  lua_assert(got == 2);
> +  lj_assertX(got == 2, "broken build: external frame unwinding enabled, but missing -funwind-tables");
>   }
>   #endif
>   
> @@ -852,7 +826,7 @@ static ptrdiff_t finderrfunc(lua_State *L)
>   	return savestack(L, frame_prevd(frame)+1);  /* xpcall's errorfunc. */
>         return 0;
>       default:
> -      lua_assert(0);
> +      lj_assertL(0, "bad frame type");
>         return 0;
>       }
>     }
> diff --git a/src/lj_func.c b/src/lj_func.c
> index 639dad87..2efecb0f 100644
> --- a/src/lj_func.c
> +++ b/src/lj_func.c
> @@ -24,9 +24,11 @@ void LJ_FASTCALL lj_func_freeproto(global_State *g, GCproto *pt)
>   
>   /* -- Upvalues ------------------------------------------------------------ */
>   
> -static void unlinkuv(GCupval *uv)
> +static void unlinkuv(global_State *g, GCupval *uv)
>   {
> -  lua_assert(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv);
> +  UNUSED(g);
> +  lj_assertG(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv,
> +	     "broken upvalue chain");
>     setgcrefr(uvnext(uv)->prev, uv->prev);
>     setgcrefr(uvprev(uv)->next, uv->next);
>   }
> @@ -40,7 +42,7 @@ static GCupval *func_finduv(lua_State *L, TValue *slot)
>     GCupval *uv;
>     /* Search the sorted list of open upvalues. */
>     while (gcref(*pp) != NULL && uvval((p = gco2uv(gcref(*pp)))) >= slot) {
> -    lua_assert(!p->closed && uvval(p) != &p->tv);
> +    lj_assertG(!p->closed && uvval(p) != &p->tv, "closed upvalue in chain");
>       if (uvval(p) == slot) {  /* Found open upvalue pointing to same slot? */
>         if (isdead(g, obj2gco(p)))  /* Resurrect it, if it's dead. */
>   	flipwhite(obj2gco(p));
> @@ -61,7 +63,8 @@ static GCupval *func_finduv(lua_State *L, TValue *slot)
>     setgcrefr(uv->next, g->uvhead.next);
>     setgcref(uvnext(uv)->prev, obj2gco(uv));
>     setgcref(g->uvhead.next, obj2gco(uv));
> -  lua_assert(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv);
> +  lj_assertG(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv,
> +	     "broken upvalue chain");
>     return uv;
>   }
>   
> @@ -84,12 +87,13 @@ void LJ_FASTCALL lj_func_closeuv(lua_State *L, TValue *level)
>     while (gcref(L->openupval) != NULL &&
>   	 uvval((uv = gco2uv(gcref(L->openupval)))) >= level) {
>       GCobj *o = obj2gco(uv);
> -    lua_assert(!isblack(o) && !uv->closed && uvval(uv) != &uv->tv);
> +    lj_assertG(!isblack(o), "bad black upvalue");
> +    lj_assertG(!uv->closed && uvval(uv) != &uv->tv, "closed upvalue in chain");
>       setgcrefr(L->openupval, uv->nextgc);  /* No longer in open list. */
>       if (isdead(g, o)) {
>         lj_func_freeuv(g, uv);
>       } else {
> -      unlinkuv(uv);
> +      unlinkuv(g, uv);
>         lj_gc_closeuv(g, uv);
>       }
>     }
> @@ -98,7 +102,7 @@ void LJ_FASTCALL lj_func_closeuv(lua_State *L, TValue *level)
>   void LJ_FASTCALL lj_func_freeuv(global_State *g, GCupval *uv)
>   {
>     if (!uv->closed)
> -    unlinkuv(uv);
> +    unlinkuv(g, uv);
>     lj_mem_freet(g, uv);
>   }
>   
> diff --git a/src/lj_gc.c b/src/lj_gc.c
> index c306047a..19d4c963 100644
> --- a/src/lj_gc.c
> +++ b/src/lj_gc.c
> @@ -42,7 +42,8 @@
>   
>   /* Mark a TValue (if needed). */
>   #define gc_marktv(g, tv) \
> -  { lua_assert(!tvisgcv(tv) || (~itype(tv) == gcval(tv)->gch.gct)); \
> +  { lj_assertG(!tvisgcv(tv) || (~itype(tv) == gcval(tv)->gch.gct), \
> +	       "TValue and GC type mismatch"); \
>       if (tviswhite(tv)) gc_mark(g, gcV(tv)); }
>   
>   /* Mark a GCobj (if needed). */
> @@ -56,7 +57,8 @@
>   static void gc_mark(global_State *g, GCobj *o)
>   {
>     int gct = o->gch.gct;
> -  lua_assert(iswhite(o) && !isdead(g, o));
> +  lj_assertG(iswhite(o), "mark of non-white object");
> +  lj_assertG(!isdead(g, o), "mark of dead object");
>     white2gray(o);
>     if (LJ_UNLIKELY(gct == ~LJ_TUDATA)) {
>       GCtab *mt = tabref(gco2ud(o)->metatable);
> @@ -69,8 +71,9 @@ static void gc_mark(global_State *g, GCobj *o)
>       if (uv->closed)
>         gray2black(o);  /* Closed upvalues are never gray. */
>     } else if (gct != ~LJ_TSTR && gct != ~LJ_TCDATA) {
> -    lua_assert(gct == ~LJ_TFUNC || gct == ~LJ_TTAB ||
> -	       gct == ~LJ_TTHREAD || gct == ~LJ_TPROTO || gct == ~LJ_TTRACE);
> +    lj_assertG(gct == ~LJ_TFUNC || gct == ~LJ_TTAB ||
> +	       gct == ~LJ_TTHREAD || gct == ~LJ_TPROTO || gct == ~LJ_TTRACE,
> +	       "bad GC type %d", gct);
>       setgcrefr(o->gch.gclist, g->gc.gray);
>       setgcref(g->gc.gray, o);
>     }
> @@ -103,7 +106,8 @@ static void gc_mark_uv(global_State *g)
>   {
>     GCupval *uv;
>     for (uv = uvnext(&g->uvhead); uv != &g->uvhead; uv = uvnext(uv)) {
> -    lua_assert(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv);
> +    lj_assertG(uvprev(uvnext(uv)) == uv && uvnext(uvprev(uv)) == uv,
> +	       "broken upvalue chain");
>       if (isgray(obj2gco(uv)))
>         gc_marktv(g, uvval(uv));
>     }
> @@ -198,7 +202,7 @@ static int gc_traverse_tab(global_State *g, GCtab *t)
>       for (i = 0; i <= hmask; i++) {
>         Node *n = &node[i];
>         if (!tvisnil(&n->val)) {  /* Mark non-empty slot. */
> -	lua_assert(!tvisnil(&n->key));
> +	lj_assertG(!tvisnil(&n->key), "mark of nil key in non-empty slot");
>   	if (!(weak & LJ_GC_WEAKKEY)) gc_marktv(g, &n->key);
>   	if (!(weak & LJ_GC_WEAKVAL)) gc_marktv(g, &n->val);
>         }
> @@ -213,7 +217,8 @@ static void gc_traverse_func(global_State *g, GCfunc *fn)
>     gc_markobj(g, tabref(fn->c.env));
>     if (isluafunc(fn)) {
>       uint32_t i;
> -    lua_assert(fn->l.nupvalues <= funcproto(fn)->sizeuv);
> +    lj_assertG(fn->l.nupvalues <= funcproto(fn)->sizeuv,
> +	       "function upvalues out of range");
>       gc_markobj(g, funcproto(fn));
>       for (i = 0; i < fn->l.nupvalues; i++)  /* Mark Lua function upvalues. */
>         gc_markobj(g, &gcref(fn->l.uvptr[i])->uv);
> @@ -229,7 +234,7 @@ static void gc_traverse_func(global_State *g, GCfunc *fn)
>   static void gc_marktrace(global_State *g, TraceNo traceno)
>   {
>     GCobj *o = obj2gco(traceref(G2J(g), traceno));
> -  lua_assert(traceno != G2J(g)->cur.traceno);
> +  lj_assertG(traceno != G2J(g)->cur.traceno, "active trace escaped");
>     if (iswhite(o)) {
>       white2gray(o);
>       setgcrefr(o->gch.gclist, g->gc.gray);
> @@ -310,7 +315,7 @@ static size_t propagatemark(global_State *g)
>   {
>     GCobj *o = gcref(g->gc.gray);
>     int gct = o->gch.gct;
> -  lua_assert(isgray(o));
> +  lj_assertG(isgray(o), "propagation of non-gray object");
>     gray2black(o);
>     setgcrefr(g->gc.gray, o->gch.gclist);  /* Remove from gray list. */
>     if (LJ_LIKELY(gct == ~LJ_TTAB)) {
> @@ -342,7 +347,7 @@ static size_t propagatemark(global_State *g)
>       return ((sizeof(GCtrace)+7)&~7) + (T->nins-T->nk)*sizeof(IRIns) +
>   	   T->nsnap*sizeof(SnapShot) + T->nsnapmap*sizeof(SnapEntry);
>   #else
> -    lua_assert(0);
> +    lj_assertG(0, "bad GC type %d", gct);
>       return 0;
>   #endif
>     }
> @@ -396,11 +401,13 @@ static GCRef *gc_sweep(global_State *g, GCRef *p, uint32_t lim)
>       if (o->gch.gct == ~LJ_TTHREAD)  /* Need to sweep open upvalues, too. */
>         gc_fullsweep(g, &gco2th(o)->openupval);
>       if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) {  /* Black or current white? */
> -      lua_assert(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED));
> +      lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
> +		 "sweep of undead object");
>         makewhite(g, o);  /* Value is alive, change to the current white. */
>         p = &o->gch.nextgc;
>       } else {  /* Otherwise value is dead, free it. */
> -      lua_assert(isdead(g, o) || ow == LJ_GC_SFIXED);
> +      lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
> +		 "sweep of unlive object");
>         setgcrefr(*p, o->gch.nextgc);
>         if (o == gcref(g->gc.root))
>   	setgcrefr(g->gc.root, o->gch.nextgc);  /* Adjust list anchor. */
> @@ -418,7 +425,8 @@ static GCRef *gc_sweep_str_chain(global_State *g, GCRef *p)
>     GCobj *o;
>     while ((o = gcref(*p)) != NULL) {
>       if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) {  /* Black or current white? */
> -      lua_assert(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED));
> +      lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
> +		 "sweep of undead string");
>         makewhite(g, o);  /* Value is alive, change to the current white. */
>   #if LUAJIT_SMART_STRINGS
>         if (strsmart(&o->str)) {
> @@ -429,7 +437,8 @@ static GCRef *gc_sweep_str_chain(global_State *g, GCRef *p)
>   #endif
>         p = &o->gch.nextgc;
>       } else {  /* Otherwise value is dead, free it. */
> -      lua_assert(isdead(g, o) || ow == LJ_GC_SFIXED);
> +      lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
> +		 "sweep of unlive string");
>         setgcrefr(*p, o->gch.nextgc);
>         lj_str_free(g, &o->str);
>       }
> @@ -454,11 +463,12 @@ static int gc_mayclear(cTValue *o, int val)
>   }
>   
>   /* Clear collected entries from weak tables. */
> -static void gc_clearweak(GCobj *o)
> +static void gc_clearweak(global_State *g, GCobj *o)
>   {
> +  UNUSED(g);
>     while (o) {
>       GCtab *t = gco2tab(o);
> -    lua_assert((t->marked & LJ_GC_WEAK));
> +    lj_assertG((t->marked & LJ_GC_WEAK), "clear of non-weak table");
>       if ((t->marked & LJ_GC_WEAKVAL)) {
>         MSize i, asize = t->asize;
>         for (i = 0; i < asize; i++) {
> @@ -515,7 +525,7 @@ static void gc_finalize(lua_State *L)
>     global_State *g = G(L);
>     GCobj *o = gcnext(gcref(g->gc.mmudata));
>     cTValue *mo;
> -  lua_assert(tvref(g->jit_base) == NULL);  /* Must not be called on trace. */
> +  lj_assertG(tvref(g->jit_base) == NULL, "finalizer called on trace");
>     /* Unchain from list of userdata to be finalized. */
>     if (o == gcref(g->gc.mmudata))
>       setgcrefnull(g->gc.mmudata);
> @@ -607,7 +617,7 @@ static void atomic(global_State *g, lua_State *L)
>   
>     setgcrefr(g->gc.gray, g->gc.weak);  /* Empty the list of weak tables. */
>     setgcrefnull(g->gc.weak);
> -  lua_assert(!iswhite(obj2gco(mainthread(g))));
> +  lj_assertG(!iswhite(obj2gco(mainthread(g))), "main thread turned white");
>     gc_markobj(g, L);  /* Mark running thread. */
>     gc_traverse_curtrace(g);  /* Traverse current trace. */
>     gc_mark_gcroot(g);  /* Mark GC roots (again). */
> @@ -622,7 +632,7 @@ static void atomic(global_State *g, lua_State *L)
>     udsize += gc_propagate_gray(g);  /* And propagate the marks. */
>   
>     /* All marking done, clear weak tables. */
> -  gc_clearweak(gcref(g->gc.weak));
> +  gc_clearweak(g, gcref(g->gc.weak));
>   
>     lj_buf_shrink(L, &g->tmpbuf);  /* Shrink temp buffer. */
>   
> @@ -668,14 +678,14 @@ static size_t gc_onestep(lua_State *L)
>         g->strbloom.cur[1] = g->strbloom.next[1];
>   #endif
>       }
> -    lua_assert(old >= g->gc.total);
> +    lj_assertG(old >= g->gc.total, "sweep increased memory");
>       g->gc.estimate -= old - g->gc.total;
>       return GCSWEEPCOST;
>       }
>     case GCSsweep: {
>       GCSize old = g->gc.total;
>       setmref(g->gc.sweep, gc_sweep(g, mref(g->gc.sweep, GCRef), GCSWEEPMAX));
> -    lua_assert(old >= g->gc.total);
> +    lj_assertG(old >= g->gc.total, "sweep increased memory");
>       g->gc.estimate -= old - g->gc.total;
>       if (gcref(*mref(g->gc.sweep, GCRef)) == NULL) {
>         if (g->strnum <= (g->strmask >> 2) && g->strmask > LJ_MIN_STRTAB*2-1)
> @@ -708,7 +718,7 @@ static size_t gc_onestep(lua_State *L)
>       g->gc.debt = 0;
>       return 0;
>     default:
> -    lua_assert(0);
> +    lj_assertG(0, "bad GC state");
>       return 0;
>     }
>   }
> @@ -782,7 +792,8 @@ void lj_gc_fullgc(lua_State *L)
>     }
>     while (g->gc.state == GCSsweepstring || g->gc.state == GCSsweep)
>       gc_onestep(L);  /* Finish sweep. */
> -  lua_assert(g->gc.state == GCSfinalize || g->gc.state == GCSpause);
> +  lj_assertG(g->gc.state == GCSfinalize || g->gc.state == GCSpause,
> +	     "bad GC state");
>     /* Now perform a full GC. */
>     g->gc.state = GCSpause;
>     do { gc_onestep(L); } while (g->gc.state != GCSpause);
> @@ -795,9 +806,11 @@ void lj_gc_fullgc(lua_State *L)
>   /* Move the GC propagation frontier forward. */
>   void lj_gc_barrierf(global_State *g, GCobj *o, GCobj *v)
>   {
> -  lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
> -  lua_assert(g->gc.state != GCSfinalize && g->gc.state != GCSpause);
> -  lua_assert(o->gch.gct != ~LJ_TTAB);
> +  lj_assertG(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o),
> +	     "bad object states for forward barrier");
> +  lj_assertG(g->gc.state != GCSfinalize && g->gc.state != GCSpause,
> +	     "bad GC state");
> +  lj_assertG(o->gch.gct != ~LJ_TTAB, "barrier object is not a table");
>     /* Preserve invariant during propagation. Otherwise it doesn't matter. */
>     if (g->gc.state == GCSpropagate || g->gc.state == GCSatomic)
>       gc_mark(g, v);  /* Move frontier forward. */
> @@ -834,7 +847,8 @@ void lj_gc_closeuv(global_State *g, GCupval *uv)
>   	lj_gc_barrierf(g, o, gcV(&uv->tv));
>       } else {
>         makewhite(g, o);  /* Make it white, i.e. sweep the upvalue. */
> -      lua_assert(g->gc.state != GCSfinalize && g->gc.state != GCSpause);
> +      lj_assertG(g->gc.state != GCSfinalize && g->gc.state != GCSpause,
> +		 "bad GC state");
>       }
>     }
>   }
> @@ -854,14 +868,15 @@ void lj_gc_barriertrace(global_State *g, uint32_t traceno)
>   void *lj_mem_realloc(lua_State *L, void *p, GCSize osz, GCSize nsz)
>   {
>     global_State *g = G(L);
> -  lua_assert((osz == 0) == (p == NULL));
> +  lj_assertG((osz == 0) == (p == NULL), "realloc API violation");
>   
>     setgcref(g->mem_L, obj2gco(L));
>     p = g->allocf(g->allocd, p, osz, nsz);
>     if (p == NULL && nsz > 0)
>       lj_err_mem(L);
> -  lua_assert((nsz == 0) == (p == NULL));
> -  lua_assert(checkptrGC(p));
> +  lj_assertG((nsz == 0) == (p == NULL), "allocf API violation");
> +  lj_assertG(checkptrGC(p),
> +	     "allocated memory address %p outside required range", p);
>     g->gc.total = (g->gc.total - osz) + nsz;
>     g->gc.allocated += nsz;
>     g->gc.freed += osz;
> @@ -878,7 +893,8 @@ void * LJ_FASTCALL lj_mem_newgco(lua_State *L, GCSize size)
>     o = (GCobj *)g->allocf(g->allocd, NULL, 0, size);
>     if (o == NULL)
>       lj_err_mem(L);
> -  lua_assert(checkptrGC(o));
> +  lj_assertG(checkptrGC(o),
> +	     "allocated memory address %p outside required range", o);
>     g->gc.total += size;
>     g->gc.allocated += size;
>     setgcrefr(o->gch.nextgc, g->gc.root);
> diff --git a/src/lj_gc.h b/src/lj_gc.h
> index 40b02cb0..bd880652 100644
> --- a/src/lj_gc.h
> +++ b/src/lj_gc.h
> @@ -76,8 +76,10 @@ LJ_FUNC void lj_gc_barriertrace(global_State *g, uint32_t traceno);
>   static LJ_AINLINE void lj_gc_barrierback(global_State *g, GCtab *t)
>   {
>     GCobj *o = obj2gco(t);
> -  lua_assert(isblack(o) && !isdead(g, o));
> -  lua_assert(g->gc.state != GCSfinalize && g->gc.state != GCSpause);
> +  lj_assertG(isblack(o) && !isdead(g, o),
> +	     "bad object states for backward barrier");
> +  lj_assertG(g->gc.state != GCSfinalize && g->gc.state != GCSpause,
> +	     "bad GC state");
>     black2gray(o);
>     setgcrefr(t->gclist, g->gc.grayagain);
>     setgcref(g->gc.grayagain, o);
> diff --git a/src/lj_gdbjit.c b/src/lj_gdbjit.c
> index c219ffac..9947eacc 100644
> --- a/src/lj_gdbjit.c
> +++ b/src/lj_gdbjit.c
> @@ -724,7 +724,7 @@ static void gdbjit_buildobj(GDBJITctx *ctx)
>     SECTALIGN(ctx->p, sizeof(uintptr_t));
>     gdbjit_initsect(ctx, GDBJIT_SECT_eh_frame, gdbjit_ehframe);
>     ctx->objsize = (size_t)((char *)ctx->p - (char *)obj);
> -  lua_assert(ctx->objsize < sizeof(GDBJITobj));
> +  lj_assertX(ctx->objsize < sizeof(GDBJITobj), "GDBJITobj overflow");
>   }
>   
>   #undef SECTALIGN
> @@ -782,7 +782,8 @@ void lj_gdbjit_addtrace(jit_State *J, GCtrace *T)
>     ctx.spadjp = CFRAME_SIZE_JIT +
>   	       (MSize)(parent ? traceref(J, parent)->spadjust : 0);
>     ctx.spadj = CFRAME_SIZE_JIT + T->spadjust;
> -  lua_assert(startpc >= proto_bc(pt) && startpc < proto_bc(pt) + pt->sizebc);
> +  lj_assertJ(startpc >= proto_bc(pt) && startpc < proto_bc(pt) + pt->sizebc,
> +	     "start PC out of range");
>     ctx.lineno = lj_debug_line(pt, proto_bcpos(pt, startpc));
>     ctx.filename = proto_chunknamestr(pt);
>     if (*ctx.filename == '@' || *ctx.filename == '=')
> diff --git a/src/lj_ir.c b/src/lj_ir.c
> index 2f7ddb24..9a51186f 100644
> --- a/src/lj_ir.c
> +++ b/src/lj_ir.c
> @@ -38,7 +38,7 @@
>   #define fins			(&J->fold.ins)
>   
>   /* Pass IR on to next optimization in chain (FOLD). */
> -#define emitir(ot, a, b)        (lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
> +#define emitir(ot, a, b)	(lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
>   
>   /* -- IR tables ----------------------------------------------------------- */
>   
> @@ -90,8 +90,9 @@ static void lj_ir_growbot(jit_State *J)
>   {
>     IRIns *baseir = J->irbuf + J->irbotlim;
>     MSize szins = J->irtoplim - J->irbotlim;
> -  lua_assert(szins != 0);
> -  lua_assert(J->cur.nk == J->irbotlim || J->cur.nk-1 == J->irbotlim);
> +  lj_assertJ(szins != 0, "zero IR size");
> +  lj_assertJ(J->cur.nk == J->irbotlim || J->cur.nk-1 == J->irbotlim,
> +	     "unexpected IR growth");
>     if (J->cur.nins + (szins >> 1) < J->irtoplim) {
>       /* More than half of the buffer is free on top: shift up by a quarter. */
>       MSize ofs = szins >> 2;
> @@ -148,9 +149,10 @@ TRef lj_ir_call(jit_State *J, IRCallID id, ...)
>   /* Load field of type t from GG_State + offset. Must be 32 bit aligned. */
>   LJ_FUNC TRef lj_ir_ggfload(jit_State *J, IRType t, uintptr_t ofs)
>   {
> -  lua_assert((ofs & 3) == 0);
> +  lj_assertJ((ofs & 3) == 0, "unaligned GG_State field offset");
>     ofs >>= 2;
> -  lua_assert(ofs >= IRFL__MAX && ofs <= 0x3ff);  /* 10 bit FOLD key limit. */
> +  lj_assertJ(ofs >= IRFL__MAX && ofs <= 0x3ff,
> +	     "GG_State field offset breaks 10 bit FOLD key limit");
>     lj_ir_set(J, IRT(IR_FLOAD, t), REF_NIL, ofs);
>     return lj_opt_fold(J);
>   }
> @@ -181,7 +183,7 @@ static LJ_AINLINE IRRef ir_nextk(jit_State *J)
>   static LJ_AINLINE IRRef ir_nextk64(jit_State *J)
>   {
>     IRRef ref = J->cur.nk - 2;
> -  lua_assert(J->state != LJ_TRACE_ASM);
> +  lj_assertJ(J->state != LJ_TRACE_ASM, "bad JIT state");
>     if (LJ_UNLIKELY(ref < J->irbotlim)) lj_ir_growbot(J);
>     J->cur.nk = ref;
>     return ref;
> @@ -277,7 +279,7 @@ TRef lj_ir_kgc(jit_State *J, GCobj *o, IRType t)
>   {
>     IRIns *ir, *cir = J->cur.ir;
>     IRRef ref;
> -  lua_assert(!isdead(J2G(J), o));
> +  lj_assertJ(!isdead(J2G(J), o), "interning of dead GC object");
>     for (ref = J->chain[IR_KGC]; ref; ref = cir[ref].prev)
>       if (ir_kgc(&cir[ref]) == o)
>         goto found;
> @@ -299,7 +301,7 @@ TRef lj_ir_ktrace(jit_State *J)
>   {
>     IRRef ref = ir_nextkgc(J);
>     IRIns *ir = IR(ref);
> -  lua_assert(irt_toitype_(IRT_P64) == LJ_TTRACE);
> +  lj_assertJ(irt_toitype_(IRT_P64) == LJ_TTRACE, "mismatched type mapping");
>     ir->t.irt = IRT_P64;
>     ir->o = LJ_GC64 ? IR_KNUM : IR_KNULL;  /* Not IR_KGC yet, but same size. */
>     ir->op12 = 0;
> @@ -313,7 +315,7 @@ TRef lj_ir_kptr_(jit_State *J, IROp op, void *ptr)
>     IRIns *ir, *cir = J->cur.ir;
>     IRRef ref;
>   #if LJ_64 && !LJ_GC64
> -  lua_assert((void *)(uintptr_t)u32ptr(ptr) == ptr);
> +  lj_assertJ((void *)(uintptr_t)u32ptr(ptr) == ptr, "out-of-range GC pointer");
>   #endif
>     for (ref = J->chain[op]; ref; ref = cir[ref].prev)
>       if (ir_kptr(&cir[ref]) == ptr)
> @@ -360,7 +362,8 @@ TRef lj_ir_kslot(jit_State *J, TRef key, IRRef slot)
>     IRRef2 op12 = IRREF2((IRRef1)key, (IRRef1)slot);
>     IRRef ref;
>     /* Const part is not touched by CSE/DCE, so 0-65535 is ok for IRMlit here. */
> -  lua_assert(tref_isk(key) && slot == (IRRef)(IRRef1)slot);
> +  lj_assertJ(tref_isk(key) && slot == (IRRef)(IRRef1)slot,
> +	     "out-of-range key/slot");
>     for (ref = J->chain[IR_KSLOT]; ref; ref = cir[ref].prev)
>       if (cir[ref].op12 == op12)
>         goto found;
> @@ -381,7 +384,7 @@ found:
>   void lj_ir_kvalue(lua_State *L, TValue *tv, const IRIns *ir)
>   {
>     UNUSED(L);
> -  lua_assert(ir->o != IR_KSLOT);  /* Common mistake. */
> +  lj_assertL(ir->o != IR_KSLOT, "unexpected KSLOT");  /* Common mistake. */
>     switch (ir->o) {
>     case IR_KPRI: setpriV(tv, irt_toitype(ir->t)); break;
>     case IR_KINT: setintV(tv, ir->i); break;
> @@ -399,7 +402,7 @@ void lj_ir_kvalue(lua_State *L, TValue *tv, const IRIns *ir)
>       break;
>       }
>   #endif
> -  default: lua_assert(0); break;
> +  default: lj_assertL(0, "bad IR constant op %d", ir->o); break;
>     }
>   }
>   
> @@ -459,7 +462,7 @@ int lj_ir_numcmp(lua_Number a, lua_Number b, IROp op)
>     case IR_UGE: return !(a < b);
>     case IR_ULE: return !(a > b);
>     case IR_UGT: return !(a <= b);
> -  default: lua_assert(0); return 0;
> +  default: lj_assertX(0, "bad IR op %d", op); return 0;
>     }
>   }
>   
> @@ -472,7 +475,7 @@ int lj_ir_strcmp(GCstr *a, GCstr *b, IROp op)
>     case IR_GE: return (res >= 0);
>     case IR_LE: return (res <= 0);
>     case IR_GT: return (res > 0);
> -  default: lua_assert(0); return 0;
> +  default: lj_assertX(0, "bad IR op %d", op); return 0;
>     }
>   }
>   
> diff --git a/src/lj_ir.h b/src/lj_ir.h
> index 43e55069..46af54e4 100644
> --- a/src/lj_ir.h
> +++ b/src/lj_ir.h
> @@ -412,11 +412,12 @@ static LJ_AINLINE IRType itype2irt(const TValue *tv)
>   
>   static LJ_AINLINE uint32_t irt_toitype_(IRType t)
>   {
> -  lua_assert(!LJ_64 || LJ_GC64 || t != IRT_LIGHTUD);
> +  lj_assertX(!LJ_64 || LJ_GC64 || t != IRT_LIGHTUD,
> +	     "no plain type tag for lightuserdata");
>     if (LJ_DUALNUM && t > IRT_NUM) {
>       return LJ_TISNUM;
>     } else {
> -    lua_assert(t <= IRT_NUM);
> +    lj_assertX(t <= IRT_NUM, "no plain type tag for IR type %d", t);
>       return ~(uint32_t)t;
>     }
>   }
> diff --git a/src/lj_jit.h b/src/lj_jit.h
> index a8b6f9a7..361570a0 100644
> --- a/src/lj_jit.h
> +++ b/src/lj_jit.h
> @@ -507,6 +507,12 @@ LJ_ALIGN(16)		/* For DISPATCH-relative addresses in assembler part. */
>   #endif
>   jit_State;
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertJ(c, ...)	lj_assertG_(J2G(J), (c), __VA_ARGS__)
> +#else
> +#define lj_assertJ(c, ...)	((void)J)
> +#endif
> +
>   /* Trivial PRNG e.g. used for penalty randomization. */
>   static LJ_AINLINE uint32_t LJ_PRNG_BITS(jit_State *J, int bits)
>   {
> diff --git a/src/lj_lex.c b/src/lj_lex.c
> index c66660d7..cef3c683 100644
> --- a/src/lj_lex.c
> +++ b/src/lj_lex.c
> @@ -76,7 +76,7 @@ static LJ_AINLINE LexChar lex_savenext(LexState *ls)
>   static void lex_newline(LexState *ls)
>   {
>     LexChar old = ls->c;
> -  lua_assert(lex_iseol(ls));
> +  lj_assertLS(lex_iseol(ls), "bad usage");
>     lex_next(ls);  /* Skip "\n" or "\r". */
>     if (lex_iseol(ls) && ls->c != old) lex_next(ls);  /* Skip "\n\r" or "\r\n". */
>     if (++ls->linenumber >= LJ_MAX_LINE)
> @@ -90,7 +90,7 @@ static void lex_number(LexState *ls, TValue *tv)
>   {
>     StrScanFmt fmt;
>     LexChar c, xp = 'e';
> -  lua_assert(lj_char_isdigit(ls->c));
> +  lj_assertLS(lj_char_isdigit(ls->c), "bad usage");
>     if ((c = ls->c) == '0' && (lex_savenext(ls) | 0x20) == 'x')
>       xp = 'p';
>     while (lj_char_isident(ls->c) || ls->c == '.' ||
> @@ -110,7 +110,8 @@ static void lex_number(LexState *ls, TValue *tv)
>     } else if (fmt != STRSCAN_ERROR) {
>       lua_State *L = ls->L;
>       GCcdata *cd;
> -    lua_assert(fmt == STRSCAN_I64 || fmt == STRSCAN_U64 || fmt == STRSCAN_IMAG);
> +    lj_assertLS(fmt == STRSCAN_I64 || fmt == STRSCAN_U64 || fmt == STRSCAN_IMAG,
> +		"unexpected number format %d", fmt);
>       if (!ctype_ctsG(G(L))) {
>         ptrdiff_t oldtop = savestack(L, L->top);
>         luaopen_ffi(L);  /* Load FFI library on-demand. */
> @@ -127,7 +128,8 @@ static void lex_number(LexState *ls, TValue *tv)
>       lj_parse_keepcdata(ls, tv, cd);
>   #endif
>     } else {
> -    lua_assert(fmt == STRSCAN_ERROR);
> +    lj_assertLS(fmt == STRSCAN_ERROR,
> +		"unexpected number format %d", fmt);
>       lj_lex_error(ls, TK_number, LJ_ERR_XNUMBER);
>     }
>   }
> @@ -137,7 +139,7 @@ static int lex_skipeq(LexState *ls)
>   {
>     int count = 0;
>     LexChar s = ls->c;
> -  lua_assert(s == '[' || s == ']');
> +  lj_assertLS(s == '[' || s == ']', "bad usage");
>     while (lex_savenext(ls) == '=' && count < 0x20000000)
>       count++;
>     return (ls->c == s) ? count : (-count) - 1;
> @@ -462,7 +464,7 @@ void lj_lex_next(LexState *ls)
>   /* Look ahead for the next token. */
>   LexToken lj_lex_lookahead(LexState *ls)
>   {
> -  lua_assert(ls->lookahead == TK_eof);
> +  lj_assertLS(ls->lookahead == TK_eof, "double lookahead");
>     ls->lookahead = lex_scan(ls, &ls->lookaheadval);
>     return ls->lookahead;
>   }
> diff --git a/src/lj_lex.h b/src/lj_lex.h
> index 33fa8657..ae05a954 100644
> --- a/src/lj_lex.h
> +++ b/src/lj_lex.h
> @@ -83,4 +83,10 @@ LJ_FUNC const char *lj_lex_token2str(LexState *ls, LexToken tok);
>   LJ_FUNC_NORET void lj_lex_error(LexState *ls, LexToken tok, ErrMsg em, ...);
>   LJ_FUNC void lj_lex_init(lua_State *L);
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertLS(c, ...)	(lj_assertG_(G(ls->L), (c), __VA_ARGS__))
> +#else
> +#define lj_assertLS(c, ...)	((void)ls)
> +#endif
> +
>   #endif
> diff --git a/src/lj_load.c b/src/lj_load.c
> index 9a31d9a1..19ac6ba2 100644
> --- a/src/lj_load.c
> +++ b/src/lj_load.c
> @@ -159,7 +159,7 @@ LUALIB_API int luaL_loadstring(lua_State *L, const char *s)
>   LUA_API int lua_dump(lua_State *L, lua_Writer writer, void *data)
>   {
>     cTValue *o = L->top-1;
> -  api_check(L, L->top > L->base);
> +  lj_checkapi(L->top > L->base, "top slot empty");
>     if (tvisfunc(o) && isluafunc(funcV(o)))
>       return lj_bcwrite(L, funcproto(funcV(o)), writer, data, 0);
>     else
> diff --git a/src/lj_mapi.c b/src/lj_mapi.c
> index 9d97c747..679ca943 100644
> --- a/src/lj_mapi.c
> +++ b/src/lj_mapi.c
> @@ -28,7 +28,7 @@ LUAMISC_API void luaM_metrics(lua_State *L, struct luam_Metrics *metrics)
>     jit_State *J = G2J(g);
>   #endif
>   
> -  lua_assert(metrics != NULL);
> +  lj_assertL(metrics != NULL, "uninitialized metrics struct");
>   
>     metrics->strhash_hit = g->strhash_hit;
>     metrics->strhash_miss = g->strhash_miss;
> diff --git a/src/lj_mcode.c b/src/lj_mcode.c
> index 10db4457..808a9897 100644
> --- a/src/lj_mcode.c
> +++ b/src/lj_mcode.c
> @@ -354,7 +354,7 @@ MCode *lj_mcode_patch(jit_State *J, MCode *ptr, int finish)
>       /* Otherwise search through the list of MCode areas. */
>       for (;;) {
>         mc = ((MCLink *)mc)->next;
> -      lua_assert(mc != NULL);
> +      lj_assertJ(mc != NULL, "broken MCode area chain");
>         if (ptr >= mc && ptr < (MCode *)((char *)mc + ((MCLink *)mc)->size)) {
>   	if (LJ_UNLIKELY(mcode_setprot(mc, ((MCLink *)mc)->size, MCPROT_GEN)))
>   	  mcode_protfail(J);
> diff --git a/src/lj_memprof.c b/src/lj_memprof.c
> index c600c4f0..a492cf58 100644
> --- a/src/lj_memprof.c
> +++ b/src/lj_memprof.c
> @@ -144,7 +144,7 @@ static void memprof_write_func(struct memprof *mp, uint8_t aevent)
>     else if (iscfunc(fn))
>       memprof_write_cfunc(out, aevent, fn, L, &mp->lib_adds);
>     else
> -    lua_assert(0);
> +    lj_assertL(0, "unknown function type to write by memprof");
>   }
>   
>   #if LJ_HASJIT
> @@ -164,7 +164,7 @@ static void memprof_write_trace(struct memprof *mp, uint8_t aevent)
>   {
>     UNUSED(mp);
>     UNUSED(aevent);
> -  lua_assert(0);
> +  lj_assertX(0, "write trace memprof event without JIT");
>   }
>   
>   #endif
> @@ -215,10 +215,12 @@ static void *memprof_allocf(void *ud, void *ptr, size_t osize, size_t nsize)
>     struct lj_wbuf *out = &mp->out;
>     void *nptr;
>   
> -  lua_assert(MPS_PROFILE == mp->state);
> -  lua_assert(oalloc->allocf != memprof_allocf);
> -  lua_assert(oalloc->allocf != NULL);
> -  lua_assert(ud == oalloc->state);
> +  lj_assertX(MPS_PROFILE == mp->state, "bad memprof profile state");
> +  lj_assertX(oalloc->allocf != memprof_allocf,
> +	     "unexpected memprof old alloc function");
> +  lj_assertX(oalloc->allocf != NULL,
> +	     "uninitialized memprof old alloc function");
> +  lj_assertX(ud == oalloc->state, "bad old memprof profile state");
>   
>     nptr = oalloc->allocf(ud, ptr, osize, nsize);
>   
> @@ -252,10 +254,10 @@ int lj_memprof_start(struct lua_State *L, const struct lj_memprof_options *opt)
>     struct alloc *oalloc = &mp->orig_alloc;
>     const size_t ljm_header_len = sizeof(ljm_header) / sizeof(ljm_header[0]);
>   
> -  lua_assert(opt->writer != NULL);
> -  lua_assert(opt->on_stop != NULL);
> -  lua_assert(opt->buf != NULL);
> -  lua_assert(opt->len != 0);
> +  lj_assertL(opt->writer != NULL, "uninitialized memprof writer");
> +  lj_assertL(opt->on_stop != NULL, "uninitialized on stop memprof callback");
> +  lj_assertL(opt->buf != NULL, "uninitialized memprof writer buffer");
> +  lj_assertL(opt->len != 0, "bad memprof writer buffer lenght");
>   
>     if (mp->state != MPS_IDLE) {
>       /* Clean up resourses. Ignore possible errors. */
> @@ -293,8 +295,9 @@ int lj_memprof_start(struct lua_State *L, const struct lj_memprof_options *opt)
>   
>     /* Override allocating function. */
>     oalloc->allocf = lua_getallocf(L, &oalloc->state);
> -  lua_assert(oalloc->allocf != NULL);
> -  lua_assert(oalloc->allocf != memprof_allocf);
> +  lj_assertL(oalloc->allocf != NULL, "uninitialized memprof old alloc function");
> +  lj_assertL(oalloc->allocf != memprof_allocf,
> +	     "unexpected memprof old alloc function");
>     lua_setallocf(L, memprof_allocf, oalloc->state);
>   
>     return PROFILE_SUCCESS;
> @@ -323,10 +326,12 @@ int lj_memprof_stop(struct lua_State *L)
>   
>     mp->state = MPS_IDLE;
>   
> -  lua_assert(mp->g != NULL);
> +  lj_assertL(mp->g != NULL, "uninitialized global state in memprof state");
>   
> -  lua_assert(memprof_allocf == lua_getallocf(L, NULL));
> -  lua_assert(oalloc->allocf != NULL);
> +  lj_assertL(memprof_allocf == lua_getallocf(L, NULL),
> +	     "bad current allocator function on memprof stop");
> +  lj_assertL(oalloc->allocf != NULL,
> +	     "uninitialized old alloc function on memprof stop");
>     lua_setallocf(L, oalloc->allocf, oalloc->state);
>   
>     if (LJ_UNLIKELY(lj_wbuf_test_flag(out, STREAM_STOP))) {
> diff --git a/src/lj_meta.c b/src/lj_meta.c
> index 7ef7a8e0..4cb1a261 100644
> --- a/src/lj_meta.c
> +++ b/src/lj_meta.c
> @@ -47,7 +47,7 @@ void lj_meta_init(lua_State *L)
>   cTValue *lj_meta_cache(GCtab *mt, MMS mm, GCstr *name)
>   {
>     cTValue *mo = lj_tab_getstr(mt, name);
> -  lua_assert(mm <= MM_FAST);
> +  lj_assertX(mm <= MM_FAST, "bad metamethod %d", mm);
>     if (!mo || tvisnil(mo)) {  /* No metamethod? */
>       mt->nomm |= (uint8_t)(1u<<mm);  /* Set negative cache flag. */
>       return NULL;
> @@ -363,7 +363,7 @@ TValue * LJ_FASTCALL lj_meta_equal_cd(lua_State *L, BCIns ins)
>     } else if (op == BC_ISEQN) {
>       o2 = &mref(curr_proto(L)->k, cTValue)[bc_d(ins)];
>     } else {
> -    lua_assert(op == BC_ISEQP);
> +    lj_assertL(op == BC_ISEQP, "bad bytecode op %d", op);
>       setpriV(&tv, ~bc_d(ins));
>       o2 = &tv;
>     }
> @@ -426,7 +426,7 @@ void lj_meta_istype(lua_State *L, BCReg ra, BCReg tp)
>   {
>     L->top = curr_topL(L);
>     ra++; tp--;
> -  lua_assert(LJ_DUALNUM || tp != ~LJ_TNUMX);  /* ISTYPE -> ISNUM broken. */
> +  lj_assertL(LJ_DUALNUM || tp != ~LJ_TNUMX, "bad type for ISTYPE");
>     if (LJ_DUALNUM && tp == ~LJ_TNUMX) lj_lib_checkint(L, ra);
>     else if (tp == ~LJ_TNUMX+1) lj_lib_checknum(L, ra);
>     else if (tp == ~LJ_TSTR) lj_lib_checkstr(L, ra);
> diff --git a/src/lj_obj.h b/src/lj_obj.h
> index bf95e1eb..fb21cba9 100644
> --- a/src/lj_obj.h
> +++ b/src/lj_obj.h
> @@ -735,6 +735,11 @@ struct lua_State {
>   #define curr_topL(L)		(L->base + curr_proto(L)->framesize)
>   #define curr_top(L)		(curr_funcisL(L) ? curr_topL(L) : L->top)
>   
> +#if defined(LUA_USE_ASSERT) || defined(LUA_USE_APICHECK)
> +LJ_FUNC_NORET void lj_assert_fail(global_State *g, const char *file, int line,
> +				  const char *func, const char *fmt, ...);
> +#endif
> +
>   /* -- GC object definition and conversions -------------------------------- */
>   
>   /* GC header for generic access to common fields of GC objects. */
> @@ -788,10 +793,6 @@ typedef union GCobj {
>   
>   /* -- TValue getters/setters ---------------------------------------------- */
>   
> -#ifdef LUA_USE_ASSERT
> -#include "lj_gc.h"
> -#endif
> -
>   /* Macros to test types. */
>   #if LJ_GC64
>   #define itype(o)	((uint32_t)((o)->it64 >> 47))
> @@ -863,8 +864,8 @@ static LJ_AINLINE void *lightudV(global_State *g, cTValue *o)
>     uint64_t u = o->u64;
>     uint64_t seg = lightudseg(u);
>     uint32_t *segmap = mref(g->gc.lightudseg, uint32_t);
> -  lua_assert(tvislightud(o));
> -  lua_assert(seg <= g->gc.lightudnum);
> +  lj_assertG(tvislightud(o), "lightuserdata expected");
> +  lj_assertG(seg <= g->gc.lightudnum, "bad lightuserdata segment %d", seg);
>     return (void *)(((uint64_t)segmap[seg] << 32) | lightudlo(u));
>   }
>   #else
> @@ -915,9 +916,19 @@ static LJ_AINLINE void setrawlightudV(TValue *o, void *p)
>     ((o)->u64 = (uint64_t)(void *)(f) - (uint64_t)lj_vm_asm_begin)
>   #endif
>   
> -#define tvchecklive(L, o) \
> -  UNUSED(L), lua_assert(!tvisgcv(o) || \
> -  ((~itype(o) == gcval(o)->gch.gct) && !isdead(G(L), gcval(o))))
> +static LJ_AINLINE void checklivetv(lua_State *L, TValue *o, const char *msg)
> +{
> +  UNUSED(L); UNUSED(o); UNUSED(msg);
> +#if LUA_USE_ASSERT
> +  if (tvisgcv(o)) {
> +    lj_assertL(~itype(o) == gcval(o)->gch.gct,
> +	       "mismatch of TValue type %d vs GC type %d",
> +	       ~itype(o), gcval(o)->gch.gct);
> +    /* Copy of isdead check from lj_gc.h to avoid circular include. */
> +    lj_assertL(!(gcval(o)->gch.marked & (G(L)->gc.currentwhite ^ 3) & 3), msg);
> +  }
> +#endif
> +}
>   
>   static LJ_AINLINE void setgcVraw(TValue *o, GCobj *v, uint32_t itype)
>   {
> @@ -930,7 +941,8 @@ static LJ_AINLINE void setgcVraw(TValue *o, GCobj *v, uint32_t itype)
>   
>   static LJ_AINLINE void setgcV(lua_State *L, TValue *o, GCobj *v, uint32_t it)
>   {
> -  setgcVraw(o, v, it); tvchecklive(L, o);
> +  setgcVraw(o, v, it);
> +  checklivetv(L, o, "store to dead GC object");
>   }
>   
>   #define define_setV(name, type, tag) \
> @@ -977,7 +989,8 @@ static LJ_AINLINE void setint64V(TValue *o, int64_t i)
>   /* Copy tagged values. */
>   static LJ_AINLINE void copyTV(lua_State *L, TValue *o1, const TValue *o2)
>   {
> -  *o1 = *o2; tvchecklive(L, o1);
> +  *o1 = *o2;
> +  checklivetv(L, o1, "copy of dead GC object");
>   }
>   
>   /* -- Number to integer conversion ---------------------------------------- */
> diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c
> index cd803d87..0007107b 100644
> --- a/src/lj_opt_fold.c
> +++ b/src/lj_opt_fold.c
> @@ -282,7 +282,7 @@ static int32_t kfold_intop(int32_t k1, int32_t k2, IROp op)
>     case IR_BROR: k1 = (int32_t)lj_ror((uint32_t)k1, (k2 & 31)); break;
>     case IR_MIN: k1 = k1 < k2 ? k1 : k2; break;
>     case IR_MAX: k1 = k1 > k2 ? k1 : k2; break;
> -  default: lua_assert(0); break;
> +  default: lj_assertX(0, "bad IR op %d", op); break;
>     }
>     return k1;
>   }
> @@ -354,7 +354,7 @@ LJFOLDF(kfold_intcomp)
>     case IR_ULE: return CONDFOLD((uint32_t)a <= (uint32_t)b);
>     case IR_ABC:
>     case IR_UGT: return CONDFOLD((uint32_t)a > (uint32_t)b);
> -  default: lua_assert(0); return FAILFOLD;
> +  default: lj_assertJ(0, "bad IR op %d", fins->o); return FAILFOLD;
>     }
>   }
>   
> @@ -368,10 +368,12 @@ LJFOLDF(kfold_intcomp0)
>   
>   /* -- Constant folding for 64 bit integers -------------------------------- */
>   
> -static uint64_t kfold_int64arith(uint64_t k1, uint64_t k2, IROp op)
> +static uint64_t kfold_int64arith(jit_State *J, uint64_t k1, uint64_t k2,
> +				 IROp op)
>   {
> -  switch (op) {
> +  UNUSED(J);
>   #if LJ_HASFFI
> +  switch (op) {
>     case IR_ADD: k1 += k2; break;
>     case IR_SUB: k1 -= k2; break;
>     case IR_MUL: k1 *= k2; break;
> @@ -383,9 +385,12 @@ static uint64_t kfold_int64arith(uint64_t k1, uint64_t k2, IROp op)
>     case IR_BSAR: k1 >>= (k2 & 63); break;
>     case IR_BROL: k1 = (int32_t)lj_rol((uint32_t)k1, (k2 & 63)); break;
>     case IR_BROR: k1 = (int32_t)lj_ror((uint32_t)k1, (k2 & 63)); break;
> -#endif
> -  default: UNUSED(k2); lua_assert(0); break;
> +  default: lj_assertJ(0, "bad IR op %d", op); break;
>     }
> +#else
> +  UNUSED(k2); UNUSED(op);
> +  lj_assertJ(0, "FFI IR op without FFI");
> +#endif
>     return k1;
>   }
>   
> @@ -397,7 +402,7 @@ LJFOLD(BOR KINT64 KINT64)
>   LJFOLD(BXOR KINT64 KINT64)
>   LJFOLDF(kfold_int64arith)
>   {
> -  return INT64FOLD(kfold_int64arith(ir_k64(fleft)->u64,
> +  return INT64FOLD(kfold_int64arith(J, ir_k64(fleft)->u64,
>   				    ir_k64(fright)->u64, (IROp)fins->o));
>   }
>   
> @@ -419,7 +424,7 @@ LJFOLDF(kfold_int64arith2)
>     }
>     return INT64FOLD(k1);
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -435,7 +440,7 @@ LJFOLDF(kfold_int64shift)
>     int32_t sh = (fright->i & 63);
>     return INT64FOLD(lj_carith_shift64(k, sh, fins->o - IR_BSHL));
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -445,7 +450,7 @@ LJFOLDF(kfold_bnot64)
>   #if LJ_HASFFI
>     return INT64FOLD(~ir_k64(fleft)->u64);
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -455,7 +460,7 @@ LJFOLDF(kfold_bswap64)
>   #if LJ_HASFFI
>     return INT64FOLD(lj_bswap64(ir_k64(fleft)->u64));
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -480,10 +485,10 @@ LJFOLDF(kfold_int64comp)
>     case IR_UGE: return CONDFOLD(a >= b);
>     case IR_ULE: return CONDFOLD(a <= b);
>     case IR_UGT: return CONDFOLD(a > b);
> -  default: lua_assert(0); return FAILFOLD;
> +  default: lj_assertJ(0, "bad IR op %d", fins->o); return FAILFOLD;
>     }
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -495,7 +500,7 @@ LJFOLDF(kfold_int64comp0)
>       return DROPFOLD;
>     return NEXTFOLD;
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -520,7 +525,7 @@ LJFOLD(STRREF KGC KINT)
>   LJFOLDF(kfold_strref)
>   {
>     GCstr *str = ir_kstr(fleft);
> -  lua_assert((MSize)fright->i <= str->len);
> +  lj_assertJ((MSize)fright->i <= str->len, "bad string ref");
>     return lj_ir_kkptr(J, (char *)strdata(str) + fright->i);
>   }
>   
> @@ -616,8 +621,9 @@ LJFOLDF(bufput_kgc)
>   LJFOLD(BUFSTR any any)
>   LJFOLDF(bufstr_kfold_cse)
>   {
> -  lua_assert(fleft->o == IR_BUFHDR || fleft->o == IR_BUFPUT ||
> -	     fleft->o == IR_CALLL);
> +  lj_assertJ(fleft->o == IR_BUFHDR || fleft->o == IR_BUFPUT ||
> +	     fleft->o == IR_CALLL,
> +	     "bad buffer constructor IR op %d", fleft->o);
>     if (LJ_LIKELY(J->flags & JIT_F_OPT_FOLD)) {
>       if (fleft->o == IR_BUFHDR) {  /* No put operations? */
>         if (!(fleft->op2 & IRBUFHDR_APPEND))  /* Empty buffer? */
> @@ -637,8 +643,9 @@ LJFOLDF(bufstr_kfold_cse)
>       while (ref) {
>         IRIns *irs = IR(ref), *ira = fleft, *irb = IR(irs->op1);
>         while (ira->o == irb->o && ira->op2 == irb->op2) {
> -	lua_assert(ira->o == IR_BUFHDR || ira->o == IR_BUFPUT ||
> -		   ira->o == IR_CALLL || ira->o == IR_CARG);
> +	lj_assertJ(ira->o == IR_BUFHDR || ira->o == IR_BUFPUT ||
> +		   ira->o == IR_CALLL || ira->o == IR_CARG,
> +		   "bad buffer constructor IR op %d", ira->o);
>   	if (ira->o == IR_BUFHDR && !(ira->op2 & IRBUFHDR_APPEND))
>   	  return ref;  /* CSE succeeded. */
>   	if (ira->o == IR_CALLL && ira->op2 == IRCALL_lj_buf_puttab)
> @@ -697,7 +704,7 @@ LJFOLD(CALLL CARG IRCALL_lj_strfmt_putfchar)
>   LJFOLDF(bufput_kfold_fmt)
>   {
>     IRIns *irc = IR(fleft->op1);
> -  lua_assert(irref_isk(irc->op2));  /* SFormat must be const. */
> +  lj_assertJ(irref_isk(irc->op2), "SFormat must be const");
>     if (irref_isk(fleft->op2)) {
>       SFormat sf = (SFormat)IR(irc->op2)->i;
>       IRIns *ira = IR(fleft->op2);
> @@ -1216,10 +1223,10 @@ LJFOLDF(simplify_tobit_conv)
>   {
>     /* Fold even across PHI to avoid expensive num->int conversions in loop. */
>     if ((fleft->op2 & IRCONV_SRCMASK) == IRT_INT) {
> -    lua_assert(irt_isnum(fleft->t));
> +    lj_assertJ(irt_isnum(fleft->t), "expected TOBIT number arg");
>       return fleft->op1;
>     } else if ((fleft->op2 & IRCONV_SRCMASK) == IRT_U32) {
> -    lua_assert(irt_isnum(fleft->t));
> +    lj_assertJ(irt_isnum(fleft->t), "expected TOBIT number arg");
>       fins->o = IR_CONV;
>       fins->op1 = fleft->op1;
>       fins->op2 = (IRT_INT<<5)|IRT_U32;
> @@ -1259,7 +1266,7 @@ LJFOLDF(simplify_conv_sext)
>     /* Use scalar evolution analysis results to strength-reduce sign-extension. */
>     if (ref == J->scev.idx) {
>       IRRef lo = J->scev.dir ? J->scev.start : J->scev.stop;
> -    lua_assert(irt_isint(J->scev.t));
> +    lj_assertJ(irt_isint(J->scev.t), "only int SCEV supported");
>       if (lo && IR(lo)->o == IR_KINT && IR(lo)->i + ofs >= 0) {
>       ok_reduce:
>   #if LJ_TARGET_X64
> @@ -1335,7 +1342,8 @@ LJFOLDF(narrow_convert)
>     /* Narrowing ignores PHIs and repeating it inside the loop is not useful. */
>     if (J->chain[IR_LOOP])
>       return NEXTFOLD;
> -  lua_assert(fins->o != IR_CONV || (fins->op2&IRCONV_CONVMASK) != IRCONV_TOBIT);
> +  lj_assertJ(fins->o != IR_CONV || (fins->op2&IRCONV_CONVMASK) != IRCONV_TOBIT,
> +	     "unexpected CONV TOBIT");
>     return lj_opt_narrow_convert(J);
>   }
>   
> @@ -1441,7 +1449,7 @@ LJFOLDF(simplify_intmul_k64)
>       return simplify_intmul_k(J, (int32_t)ir_kint64(fright)->u64);
>     return NEXTFOLD;
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -1449,7 +1457,7 @@ LJFOLD(MOD any KINT)
>   LJFOLDF(simplify_intmod_k)
>   {
>     int32_t k = fright->i;
> -  lua_assert(k != 0);
> +  lj_assertJ(k != 0, "integer mod 0");
>     if (k > 0 && (k & (k-1)) == 0) {  /* i % (2^k) ==> i & (2^k-1) */
>       fins->o = IR_BAND;
>       fins->op2 = lj_ir_kint(J, k-1);
> @@ -1699,7 +1707,8 @@ LJFOLDF(simplify_shiftk_andk)
>       fins->ot = IRTI(IR_BAND);
>       return RETRYFOLD;
>     } else if (irk->o == IR_KINT64) {
> -    uint64_t k = kfold_int64arith(ir_k64(irk)->u64, fright->i, (IROp)fins->o);
> +    uint64_t k = kfold_int64arith(J, ir_k64(irk)->u64, fright->i,
> +				  (IROp)fins->o);
>       IROpT ot = fleft->ot;
>       fins->op1 = fleft->op1;
>       fins->op1 = (IRRef1)lj_opt_fold(J);
> @@ -1747,8 +1756,8 @@ LJFOLDF(simplify_andor_k64)
>     IRIns *irk = IR(fleft->op2);
>     PHIBARRIER(fleft);
>     if (irk->o == IR_KINT64) {
> -    uint64_t k = kfold_int64arith(ir_k64(irk)->u64,
> -				  ir_k64(fright)->u64, (IROp)fins->o);
> +    uint64_t k = kfold_int64arith(J, ir_k64(irk)->u64, ir_k64(fright)->u64,
> +				  (IROp)fins->o);
>       /* (i | k1) & k2 ==> i & k2, if (k1 & k2) == 0. */
>       /* (i & k1) | k2 ==> i | k2, if (k1 | k2) == -1. */
>       if (k == (fins->o == IR_BAND ? (uint64_t)0 : ~(uint64_t)0)) {
> @@ -1758,7 +1767,7 @@ LJFOLDF(simplify_andor_k64)
>     }
>     return NEXTFOLD;
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -1794,8 +1803,8 @@ LJFOLDF(reassoc_intarith_k64)
>   #if LJ_HASFFI
>     IRIns *irk = IR(fleft->op2);
>     if (irk->o == IR_KINT64) {
> -    uint64_t k = kfold_int64arith(ir_k64(irk)->u64,
> -				  ir_k64(fright)->u64, (IROp)fins->o);
> +    uint64_t k = kfold_int64arith(J, ir_k64(irk)->u64, ir_k64(fright)->u64,
> +				  (IROp)fins->o);
>       PHIBARRIER(fleft);
>       fins->op1 = fleft->op1;
>       fins->op2 = (IRRef1)lj_ir_kint64(J, k);
> @@ -1803,7 +1812,7 @@ LJFOLDF(reassoc_intarith_k64)
>     }
>     return NEXTFOLD;
>   #else
> -  UNUSED(J); lua_assert(0); return FAILFOLD;
> +  UNUSED(J); lj_assertJ(0, "FFI IR op without FFI"); return FAILFOLD;
>   #endif
>   }
>   
> @@ -2058,7 +2067,7 @@ LJFOLDF(merge_eqne_snew_kgc)
>   {
>     GCstr *kstr = ir_kstr(fright);
>     int32_t len = (int32_t)kstr->len;
> -  lua_assert(irt_isstr(fins->t));
> +  lj_assertJ(irt_isstr(fins->t), "bad equality IR type");
>   
>   #if LJ_TARGET_UNALIGNED
>   #define FOLD_SNEW_MAX_LEN	4  /* Handle string lengths 0, 1, 2, 3, 4. */
> @@ -2122,7 +2131,7 @@ LJFOLD(HLOAD KKPTR)
>   LJFOLDF(kfold_hload_kkptr)
>   {
>     UNUSED(J);
> -  lua_assert(ir_kptr(fleft) == niltvg(J2G(J)));
> +  lj_assertJ(ir_kptr(fleft) == niltvg(J2G(J)), "expected niltv");
>     return TREF_NIL;
>   }
>   
> @@ -2333,7 +2342,7 @@ LJFOLDF(fwd_sload)
>       TRef tr = lj_opt_cse(J);
>       return tref_ref(tr) < J->chain[IR_RETF] ? EMITFOLD : tr;
>     } else {
> -    lua_assert(J->slot[fins->op1] != 0);
> +    lj_assertJ(J->slot[fins->op1] != 0, "uninitialized slot accessed");
>       return J->slot[fins->op1];
>     }
>   }
> @@ -2448,8 +2457,9 @@ TRef LJ_FASTCALL lj_opt_fold(jit_State *J)
>     IRRef ref;
>   
>     if (LJ_UNLIKELY((J->flags & JIT_F_OPT_MASK) != JIT_F_OPT_DEFAULT)) {
> -    lua_assert(((JIT_F_OPT_FOLD|JIT_F_OPT_FWD|JIT_F_OPT_CSE|JIT_F_OPT_DSE) |
> -		JIT_F_OPT_DEFAULT) == JIT_F_OPT_DEFAULT);
> +    lj_assertJ(((JIT_F_OPT_FOLD|JIT_F_OPT_FWD|JIT_F_OPT_CSE|JIT_F_OPT_DSE) |
> +		JIT_F_OPT_DEFAULT) == JIT_F_OPT_DEFAULT,
> +	       "bad JIT_F_OPT_DEFAULT");
>       /* Folding disabled? Chain to CSE, but not for loads/stores/allocs. */
>       if (!(J->flags & JIT_F_OPT_FOLD) && irm_kind(lj_ir_mode[fins->o]) == IRM_N)
>         return lj_opt_cse(J);
> @@ -2511,7 +2521,7 @@ retry:
>       return lj_ir_kint(J, fins->i);
>     if (ref == FAILFOLD)
>       lj_trace_err(J, LJ_TRERR_GFAIL);
> -  lua_assert(ref == DROPFOLD);
> +  lj_assertJ(ref == DROPFOLD, "bad fold result");
>     return REF_DROP;
>   }
>   
> diff --git a/src/lj_opt_loop.c b/src/lj_opt_loop.c
> index 10613641..d3b0fcee 100644
> --- a/src/lj_opt_loop.c
> +++ b/src/lj_opt_loop.c
> @@ -300,7 +300,8 @@ static void loop_unroll(LoopState *lps)
>     loopmap = &J->cur.snapmap[loopsnap->mapofs];
>     /* The PC of snapshot #0 and the loop snapshot must match. */
>     psentinel = &loopmap[loopsnap->nent];
> -  lua_assert(*psentinel == J->cur.snapmap[J->cur.snap[0].nent]);
> +  lj_assertJ(*psentinel == J->cur.snapmap[J->cur.snap[0].nent],
> +	     "mismatched PC for loop snapshot");
>     *psentinel = SNAP(255, 0, 0);  /* Replace PC with temporary sentinel. */
>   
>     /* Start substitution with snapshot #1 (#0 is empty for root traces). */
> @@ -371,7 +372,7 @@ static void loop_unroll(LoopState *lps)
>     }
>     if (!irt_isguard(J->guardemit))  /* Drop redundant snapshot. */
>       J->cur.nsnapmap = (uint32_t)J->cur.snap[--J->cur.nsnap].mapofs;
> -  lua_assert(J->cur.nsnapmap <= J->sizesnapmap);
> +  lj_assertJ(J->cur.nsnapmap <= J->sizesnapmap, "bad snapshot map index");
>     *psentinel = J->cur.snapmap[J->cur.snap[0].nent];  /* Restore PC. */
>   
>     loop_emit_phi(J, subst, phi, nphi, onsnap);
> diff --git a/src/lj_opt_mem.c b/src/lj_opt_mem.c
> index c8265b4f..59fddbdd 100644
> --- a/src/lj_opt_mem.c
> +++ b/src/lj_opt_mem.c
> @@ -18,6 +18,7 @@
>   #include "lj_jit.h"
>   #include "lj_iropt.h"
>   #include "lj_ircall.h"
> +#include "lj_dispatch.h"
>   
>   /* Some local macros to save typing. Undef'd at the end. */
>   #define IR(ref)		(&J->cur.ir[(ref)])
> @@ -56,8 +57,8 @@ static AliasRet aa_table(jit_State *J, IRRef ta, IRRef tb)
>   {
>     IRIns *taba = IR(ta), *tabb = IR(tb);
>     int newa, newb;
> -  lua_assert(ta != tb);
> -  lua_assert(irt_istab(taba->t) && irt_istab(tabb->t));
> +  lj_assertJ(ta != tb, "bad usage");
> +  lj_assertJ(irt_istab(taba->t) && irt_istab(tabb->t), "bad usage");
>     /* Disambiguate new allocations. */
>     newa = (taba->o == IR_TNEW || taba->o == IR_TDUP);
>     newb = (tabb->o == IR_TNEW || tabb->o == IR_TDUP);
> @@ -99,7 +100,7 @@ static AliasRet aa_ahref(jit_State *J, IRIns *refa, IRIns *refb)
>       /* Disambiguate array references based on index arithmetic. */
>       int32_t ofsa = 0, ofsb = 0;
>       IRRef basea = ka, baseb = kb;
> -    lua_assert(refb->o == IR_AREF);
> +    lj_assertJ(refb->o == IR_AREF, "expected AREF");
>       /* Gather base and offset from t[base] or t[base+-ofs]. */
>       if (keya->o == IR_ADD && irref_isk(keya->op2)) {
>         basea = keya->op1;
> @@ -117,8 +118,9 @@ static AliasRet aa_ahref(jit_State *J, IRIns *refa, IRIns *refb)
>         return ALIAS_NO;  /* t[base+-o1] vs. t[base+-o2] and o1 != o2. */
>     } else {
>       /* Disambiguate hash references based on the type of their keys. */
> -    lua_assert((refa->o==IR_HREF || refa->o==IR_HREFK || refa->o==IR_NEWREF) &&
> -	       (refb->o==IR_HREF || refb->o==IR_HREFK || refb->o==IR_NEWREF));
> +    lj_assertJ((refa->o==IR_HREF || refa->o==IR_HREFK || refa->o==IR_NEWREF) &&
> +	       (refb->o==IR_HREF || refb->o==IR_HREFK || refb->o==IR_NEWREF),
> +	       "bad xREF IR op %d or %d", refa->o, refb->o);
>       if (!irt_sametype(keya->t, keyb->t))
>         return ALIAS_NO;  /* Different key types. */
>     }
> @@ -192,7 +194,8 @@ static TRef fwd_ahload(jit_State *J, IRRef xref)
>   	if (key->o == IR_KSLOT) key = IR(key->op1);
>   	lj_ir_kvalue(J->L, &keyv, key);
>   	tv = lj_tab_get(J->L, ir_ktab(IR(ir->op1)), &keyv);
> -	lua_assert(itype2irt(tv) == irt_type(fins->t));
> +	lj_assertJ(itype2irt(tv) == irt_type(fins->t),
> +		   "mismatched type in constant table");
>   	if (irt_isnum(fins->t))
>   	  return lj_ir_knum_u64(J, tv->u64);
>   	else if (LJ_DUALNUM && irt_isint(fins->t))
> diff --git a/src/lj_opt_narrow.c b/src/lj_opt_narrow.c
> index 4f285334..2cfb775b 100644
> --- a/src/lj_opt_narrow.c
> +++ b/src/lj_opt_narrow.c
> @@ -372,17 +372,17 @@ static IRRef narrow_conv_emit(jit_State *J, NarrowConv *nc)
>       } else if (op == NARROW_CONV) {
>         *sp++ = emitir_raw(convot, ref, convop2);  /* Raw emit avoids a loop. */
>       } else if (op == NARROW_SEXT) {
> -      lua_assert(sp >= nc->stack+1);
> +      lj_assertJ(sp >= nc->stack+1, "stack underflow");
>         sp[-1] = emitir(IRT(IR_CONV, IRT_I64), sp[-1],
>   		      (IRT_I64<<5)|IRT_INT|IRCONV_SEXT);
>       } else if (op == NARROW_INT) {
> -      lua_assert(next < last);
> +      lj_assertJ(next < last, "missing arg to NARROW_INT");
>         *sp++ = nc->t == IRT_I64 ?
>   	      lj_ir_kint64(J, (int64_t)(int32_t)*next++) :
>   	      lj_ir_kint(J, *next++);
>       } else {  /* Regular IROpT. Pops two operands and pushes one result. */
>         IRRef mode = nc->mode;
> -      lua_assert(sp >= nc->stack+2);
> +      lj_assertJ(sp >= nc->stack+2, "stack underflow");
>         sp--;
>         /* Omit some overflow checks for array indexing. See comments above. */
>         if ((mode & IRCONV_CONVMASK) == IRCONV_INDEX) {
> @@ -398,7 +398,7 @@ static IRRef narrow_conv_emit(jit_State *J, NarrowConv *nc)
>   	narrow_bpc_set(J, narrow_ref(ref), narrow_ref(sp[-1]), mode);
>       }
>     }
> -  lua_assert(sp == nc->stack+1);
> +  lj_assertJ(sp == nc->stack+1, "stack misalignment");
>     return nc->stack[0];
>   }
>   
> @@ -452,7 +452,7 @@ static TRef narrow_stripov(jit_State *J, TRef tr, int lastop, IRRef mode)
>   TRef LJ_FASTCALL lj_opt_narrow_index(jit_State *J, TRef tr)
>   {
>     IRIns *ir;
> -  lua_assert(tref_isnumber(tr));
> +  lj_assertJ(tref_isnumber(tr), "expected number type");
>     if (tref_isnum(tr))  /* Conversion may be narrowed, too. See above. */
>       return emitir(IRTGI(IR_CONV), tr, IRCONV_INT_NUM|IRCONV_INDEX);
>     /* Omit some overflow checks for array indexing. See comments above. */
> @@ -499,7 +499,7 @@ TRef LJ_FASTCALL lj_opt_narrow_tobit(jit_State *J, TRef tr)
>   /* Narrow C array index (overflow undefined). */
>   TRef LJ_FASTCALL lj_opt_narrow_cindex(jit_State *J, TRef tr)
>   {
> -  lua_assert(tref_isnumber(tr));
> +  lj_assertJ(tref_isnumber(tr), "expected number type");
>     if (tref_isnum(tr))
>       return emitir(IRT(IR_CONV, IRT_INTP), tr, (IRT_INTP<<5)|IRT_NUM|IRCONV_ANY);
>     /* Undefined overflow semantics allow stripping of ADDOV, SUBOV and MULOV. */
> @@ -627,9 +627,10 @@ static int narrow_forl(jit_State *J, cTValue *o)
>   /* Narrow the FORL index type by looking at the runtime values. */
>   IRType lj_opt_narrow_forl(jit_State *J, cTValue *tv)
>   {
> -  lua_assert(tvisnumber(&tv[FORL_IDX]) &&
> +  lj_assertJ(tvisnumber(&tv[FORL_IDX]) &&
>   	     tvisnumber(&tv[FORL_STOP]) &&
> -	     tvisnumber(&tv[FORL_STEP]));
> +	     tvisnumber(&tv[FORL_STEP]),
> +	     "expected number types");
>     /* Narrow only if the runtime values of start/stop/step are all integers. */
>     if (narrow_forl(J, &tv[FORL_IDX]) &&
>         narrow_forl(J, &tv[FORL_STOP]) &&
> diff --git a/src/lj_opt_split.c b/src/lj_opt_split.c
> index c10a85cb..a619d852 100644
> --- a/src/lj_opt_split.c
> +++ b/src/lj_opt_split.c
> @@ -235,7 +235,7 @@ static IRRef split_bitshift(jit_State *J, IRRef1 *hisubst,
>   	return split_emit(J, IRTI(IR_BOR), t1, t2);
>         } else {
>   	IRRef t1 = ir->prev, t2;
> -	lua_assert(op == IR_BSHR || op == IR_BSAR);
> +	lj_assertJ(op == IR_BSHR || op == IR_BSAR, "bad usage");
>   	nir->o = IR_BSHR;
>   	t2 = split_emit(J, IRTI(IR_BSHL), hi, lj_ir_kint(J, (-k&31)));
>   	ir->prev = split_emit(J, IRTI(IR_BOR), t1, t2);
> @@ -250,7 +250,7 @@ static IRRef split_bitshift(jit_State *J, IRRef1 *hisubst,
>   	ir->prev = lj_ir_kint(J, 0);
>   	return lo;
>         } else {
> -	lua_assert(op == IR_BSHR || op == IR_BSAR);
> +	lj_assertJ(op == IR_BSHR || op == IR_BSAR, "bad usage");
>   	if (k == 32) {
>   	  J->cur.nins--;
>   	  ir->prev = hi;
> @@ -429,7 +429,7 @@ static void split_ir(jit_State *J)
>   	hi = split_emit(J, IRT(IR_HIOP, IRT_SOFTFP), nref, nref);
>   	break;
>         case IR_FLOAD:
> -	lua_assert(ir->op1 == REF_NIL);
> +	lj_assertJ(ir->op1 == REF_NIL, "expected FLOAD from GG_State");
>   	hi = lj_ir_kint(J, *(int32_t*)((char*)J2GG(J) + ir->op2 + LJ_LE*4));
>   	nir->op2 += LJ_BE*4;
>   	break;
> @@ -465,8 +465,9 @@ static void split_ir(jit_State *J)
>   	  break;
>   	}
>   #endif
> -	lua_assert(st == IRT_INT ||
> -		   (LJ_32 && LJ_HASFFI && (st == IRT_U32 || st == IRT_FLOAT)));
> +	lj_assertJ(st == IRT_INT ||
> +		   (LJ_32 && LJ_HASFFI && (st == IRT_U32 || st == IRT_FLOAT)),
> +		   "bad source type for CONV");
>   	nir->o = IR_CALLN;
>   #if LJ_32 && LJ_HASFFI
>   	nir->op2 = st == IRT_INT ? IRCALL_softfp_i2d :
> @@ -496,7 +497,8 @@ static void split_ir(jit_State *J)
>   	hi = nir->op2;
>   	break;
>         default:
> -	lua_assert(ir->o <= IR_NE || ir->o == IR_MIN || ir->o == IR_MAX);
> +	lj_assertJ(ir->o <= IR_NE || ir->o == IR_MIN || ir->o == IR_MAX,
> +		   "bad IR op %d", ir->o);
>   	hi = split_emit(J, IRTG(IR_HIOP, IRT_SOFTFP),
>   			hisubst[ir->op1], hisubst[ir->op2]);
>   	break;
> @@ -553,7 +555,7 @@ static void split_ir(jit_State *J)
>   	hi = split_bitshift(J, hisubst, oir, nir, ir);
>   	break;
>         case IR_FLOAD:
> -	lua_assert(ir->op2 == IRFL_CDATA_INT64);
> +	lj_assertJ(ir->op2 == IRFL_CDATA_INT64, "only INT64 supported");
>   	hi = split_emit(J, IRTI(IR_FLOAD), nir->op1, IRFL_CDATA_INT64_4);
>   #if LJ_BE
>   	ir->prev = hi; hi = nref;
> @@ -619,7 +621,7 @@ static void split_ir(jit_State *J)
>   	hi = nir->op2;
>   	break;
>         default:
> -	lua_assert(ir->o <= IR_NE);  /* Comparisons. */
> +	lj_assertJ(ir->o <= IR_NE, "bad IR op %d", ir->o);  /* Comparisons. */
>   	split_emit(J, IRTGI(IR_HIOP), hiref, hisubst[ir->op2]);
>   	break;
>         }
> @@ -697,7 +699,7 @@ static void split_ir(jit_State *J)
>   #if LJ_SOFTFP
>         if (st == IRT_NUM || (LJ_32 && LJ_HASFFI && st == IRT_FLOAT)) {
>   	if (irt_isguard(ir->t)) {
> -	  lua_assert(st == IRT_NUM && irt_isint(ir->t));
> +	  lj_assertJ(st == IRT_NUM && irt_isint(ir->t), "bad CONV types");
>   	  J->cur.nins--;
>   	  ir->prev = split_num2int(J, nir->op1, hisubst[ir->op1], 1);
>   	} else {
> @@ -828,7 +830,7 @@ void lj_opt_split(jit_State *J)
>     if (!J->needsplit)
>       J->needsplit = split_needsplit(J);
>   #else
> -  lua_assert(J->needsplit >= split_needsplit(J));  /* Verify flag. */
> +  lj_assertJ(J->needsplit >= split_needsplit(J), "bad SPLIT state");
>   #endif
>     if (J->needsplit) {
>       int errcode = lj_vm_cpcall(J->L, NULL, J, cpsplit);
> diff --git a/src/lj_parse.c b/src/lj_parse.c
> index e238afa3..3f6caaec 100644
> --- a/src/lj_parse.c
> +++ b/src/lj_parse.c
> @@ -169,6 +169,12 @@ LJ_STATIC_ASSERT((int)BC_MULVV-(int)BC_ADDVV == (int)OPR_MUL-(int)OPR_ADD);
>   LJ_STATIC_ASSERT((int)BC_DIVVV-(int)BC_ADDVV == (int)OPR_DIV-(int)OPR_ADD);
>   LJ_STATIC_ASSERT((int)BC_MODVV-(int)BC_ADDVV == (int)OPR_MOD-(int)OPR_ADD);
>   
> +#ifdef LUA_USE_ASSERT
> +#define lj_assertFS(c, ...)	(lj_assertG_(G(fs->L), (c), __VA_ARGS__))
> +#else
> +#define lj_assertFS(c, ...)	((void)fs)
> +#endif
> +
>   /* -- Error handling ------------------------------------------------------ */
>   
>   LJ_NORET LJ_NOINLINE static void err_syntax(LexState *ls, ErrMsg em)
> @@ -206,7 +212,7 @@ static BCReg const_num(FuncState *fs, ExpDesc *e)
>   {
>     lua_State *L = fs->L;
>     TValue *o;
> -  lua_assert(expr_isnumk(e));
> +  lj_assertFS(expr_isnumk(e), "bad usage");
>     o = lj_tab_set(L, fs->kt, &e->u.nval);
>     if (tvhaskslot(o))
>       return tvkslot(o);
> @@ -231,7 +237,7 @@ static BCReg const_gc(FuncState *fs, GCobj *gc, uint32_t itype)
>   /* Add a string constant. */
>   static BCReg const_str(FuncState *fs, ExpDesc *e)
>   {
> -  lua_assert(expr_isstrk(e) || e->k == VGLOBAL);
> +  lj_assertFS(expr_isstrk(e) || e->k == VGLOBAL, "bad usage");
>     return const_gc(fs, obj2gco(e->u.sval), LJ_TSTR);
>   }
>   
> @@ -319,7 +325,7 @@ static void jmp_patchins(FuncState *fs, BCPos pc, BCPos dest)
>   {
>     BCIns *jmp = &fs->bcbase[pc].ins;
>     BCPos offset = dest-(pc+1)+BCBIAS_J;
> -  lua_assert(dest != NO_JMP);
> +  lj_assertFS(dest != NO_JMP, "uninitialized jump target");
>     if (offset > BCMAX_D)
>       err_syntax(fs->ls, LJ_ERR_XJUMP);
>     setbc_d(jmp, offset);
> @@ -368,7 +374,7 @@ static void jmp_patch(FuncState *fs, BCPos list, BCPos target)
>     if (target == fs->pc) {
>       jmp_tohere(fs, list);
>     } else {
> -    lua_assert(target < fs->pc);
> +    lj_assertFS(target < fs->pc, "bad jump target");
>       jmp_patchval(fs, list, target, NO_REG, target);
>     }
>   }
> @@ -398,7 +404,7 @@ static void bcreg_free(FuncState *fs, BCReg reg)
>   {
>     if (reg >= fs->nactvar) {
>       fs->freereg--;
> -    lua_assert(reg == fs->freereg);
> +    lj_assertFS(reg == fs->freereg, "bad regfree");
>     }
>   }
>   
> @@ -548,7 +554,7 @@ static void expr_toreg_nobranch(FuncState *fs, ExpDesc *e, BCReg reg)
>     } else if (e->k <= VKTRUE) {
>       ins = BCINS_AD(BC_KPRI, reg, const_pri(e));
>     } else {
> -    lua_assert(e->k == VVOID || e->k == VJMP);
> +    lj_assertFS(e->k == VVOID || e->k == VJMP, "bad expr type %d", e->k);
>       return;
>     }
>     bcemit_INS(fs, ins);
> @@ -643,7 +649,7 @@ static void bcemit_store(FuncState *fs, ExpDesc *var, ExpDesc *e)
>       ins = BCINS_AD(BC_GSET, ra, const_str(fs, var));
>     } else {
>       BCReg ra, rc;
> -    lua_assert(var->k == VINDEXED);
> +    lj_assertFS(var->k == VINDEXED, "bad expr type %d", var->k);
>       ra = expr_toanyreg(fs, e);
>       rc = var->u.s.aux;
>       if ((int32_t)rc < 0) {
> @@ -651,10 +657,12 @@ static void bcemit_store(FuncState *fs, ExpDesc *var, ExpDesc *e)
>       } else if (rc > BCMAX_C) {
>         ins = BCINS_ABC(BC_TSETB, ra, var->u.s.info, rc-(BCMAX_C+1));
>       } else {
> +#ifdef LUA_USE_ASSERT
>         /* Free late alloced key reg to avoid assert on free of value reg. */
>         /* This can only happen when called from expr_table(). */
> -      lua_assert(e->k != VNONRELOC || ra < fs->nactvar ||
> -		 rc < ra || (bcreg_free(fs, rc),1));
> +      if (e->k == VNONRELOC && ra >= fs->nactvar && rc >= ra)
> +	bcreg_free(fs, rc);
> +#endif
>         ins = BCINS_ABC(BC_TSETV, ra, var->u.s.info, rc);
>       }
>     }
> @@ -669,7 +677,7 @@ static void bcemit_method(FuncState *fs, ExpDesc *e, ExpDesc *key)
>     expr_free(fs, e);
>     func = fs->freereg;
>     bcemit_AD(fs, BC_MOV, func+1+LJ_FR2, obj);  /* Copy object to 1st argument. */
> -  lua_assert(expr_isstrk(key));
> +  lj_assertFS(expr_isstrk(key), "bad usage");
>     idx = const_str(fs, key);
>     if (idx <= BCMAX_C) {
>       bcreg_reserve(fs, 2+LJ_FR2);
> @@ -809,7 +817,8 @@ static void bcemit_arith(FuncState *fs, BinOpr opr, ExpDesc *e1, ExpDesc *e2)
>       else
>         rc = expr_toanyreg(fs, e2);
>       /* 1st operand discharged by bcemit_binop_left, but need KNUM/KSHORT. */
> -    lua_assert(expr_isnumk(e1) || e1->k == VNONRELOC);
> +    lj_assertFS(expr_isnumk(e1) || e1->k == VNONRELOC,
> +		"bad expr type %d", e1->k);
>       expr_toval(fs, e1);
>       /* Avoid two consts to satisfy bytecode constraints. */
>       if (expr_isnumk(e1) && !expr_isnumk(e2) &&
> @@ -897,19 +906,20 @@ static void bcemit_binop(FuncState *fs, BinOpr op, ExpDesc *e1, ExpDesc *e2)
>     if (op <= OPR_POW) {
>       bcemit_arith(fs, op, e1, e2);
>     } else if (op == OPR_AND) {
> -    lua_assert(e1->t == NO_JMP);  /* List must be closed. */
> +    lj_assertFS(e1->t == NO_JMP, "jump list not closed");
>       expr_discharge(fs, e2);
>       jmp_append(fs, &e2->f, e1->f);
>       *e1 = *e2;
>     } else if (op == OPR_OR) {
> -    lua_assert(e1->f == NO_JMP);  /* List must be closed. */
> +    lj_assertFS(e1->f == NO_JMP, "jump list not closed");
>       expr_discharge(fs, e2);
>       jmp_append(fs, &e2->t, e1->t);
>       *e1 = *e2;
>     } else if (op == OPR_CONCAT) {
>       expr_toval(fs, e2);
>       if (e2->k == VRELOCABLE && bc_op(*bcptr(fs, e2)) == BC_CAT) {
> -      lua_assert(e1->u.s.info == bc_b(*bcptr(fs, e2))-1);
> +      lj_assertFS(e1->u.s.info == bc_b(*bcptr(fs, e2))-1,
> +		  "bad CAT stack layout");
>         expr_free(fs, e1);
>         setbc_b(bcptr(fs, e2), e1->u.s.info);
>         e1->u.s.info = e2->u.s.info;
> @@ -921,8 +931,9 @@ static void bcemit_binop(FuncState *fs, BinOpr op, ExpDesc *e1, ExpDesc *e2)
>       }
>       e1->k = VRELOCABLE;
>     } else {
> -    lua_assert(op == OPR_NE || op == OPR_EQ ||
> -	       op == OPR_LT || op == OPR_GE || op == OPR_LE || op == OPR_GT);
> +    lj_assertFS(op == OPR_NE || op == OPR_EQ ||
> +	       op == OPR_LT || op == OPR_GE || op == OPR_LE || op == OPR_GT,
> +	       "bad binop %d", op);
>       bcemit_comp(fs, op, e1, e2);
>     }
>   }
> @@ -951,10 +962,10 @@ static void bcemit_unop(FuncState *fs, BCOp op, ExpDesc *e)
>         e->u.s.info = fs->freereg-1;
>         e->k = VNONRELOC;
>       } else {
> -      lua_assert(e->k == VNONRELOC);
> +      lj_assertFS(e->k == VNONRELOC, "bad expr type %d", e->k);
>       }
>     } else {
> -    lua_assert(op == BC_UNM || op == BC_LEN);
> +    lj_assertFS(op == BC_UNM || op == BC_LEN, "bad unop %d", op);
>       if (op == BC_UNM && !expr_hasjump(e)) {  /* Constant-fold negations. */
>   #if LJ_HASFFI
>         if (e->k == VKCDATA) {  /* Fold in-place since cdata is not interned. */
> @@ -1049,8 +1060,9 @@ static void var_new(LexState *ls, BCReg n, GCstr *name)
>         lj_lex_error(ls, 0, LJ_ERR_XLIMC, LJ_MAX_VSTACK);
>       lj_mem_growvec(ls->L, ls->vstack, ls->sizevstack, LJ_MAX_VSTACK, VarInfo);
>     }
> -  lua_assert((uintptr_t)name < VARNAME__MAX ||
> -	     lj_tab_getstr(fs->kt, name) != NULL);
> +  lj_assertFS((uintptr_t)name < VARNAME__MAX ||
> +	      lj_tab_getstr(fs->kt, name) != NULL,
> +	      "unanchored variable name");
>     /* NOBARRIER: name is anchored in fs->kt and ls->vstack is not a GCobj. */
>     setgcref(ls->vstack[vtop].name, obj2gco(name));
>     fs->varmap[fs->nactvar+n] = (uint16_t)vtop;
> @@ -1105,7 +1117,7 @@ static MSize var_lookup_uv(FuncState *fs, MSize vidx, ExpDesc *e)
>         return i;  /* Already exists. */
>     /* Otherwise create a new one. */
>     checklimit(fs, fs->nuv, LJ_MAX_UPVAL, "upvalues");
> -  lua_assert(e->k == VLOCAL || e->k == VUPVAL);
> +  lj_assertFS(e->k == VLOCAL || e->k == VUPVAL, "bad expr type %d", e->k);
>     fs->uvmap[n] = (uint16_t)vidx;
>     fs->uvtmp[n] = (uint16_t)(e->k == VLOCAL ? vidx : LJ_MAX_VSTACK+e->u.s.info);
>     fs->nuv = n+1;
> @@ -1156,7 +1168,8 @@ static MSize gola_new(LexState *ls, GCstr *name, uint8_t info, BCPos pc)
>         lj_lex_error(ls, 0, LJ_ERR_XLIMC, LJ_MAX_VSTACK);
>       lj_mem_growvec(ls->L, ls->vstack, ls->sizevstack, LJ_MAX_VSTACK, VarInfo);
>     }
> -  lua_assert(name == NAME_BREAK || lj_tab_getstr(fs->kt, name) != NULL);
> +  lj_assertFS(name == NAME_BREAK || lj_tab_getstr(fs->kt, name) != NULL,
> +	      "unanchored label name");
>     /* NOBARRIER: name is anchored in fs->kt and ls->vstack is not a GCobj. */
>     setgcref(ls->vstack[vtop].name, obj2gco(name));
>     ls->vstack[vtop].startpc = pc;
> @@ -1186,8 +1199,9 @@ static void gola_close(LexState *ls, VarInfo *vg)
>     FuncState *fs = ls->fs;
>     BCPos pc = vg->startpc;
>     BCIns *ip = &fs->bcbase[pc].ins;
> -  lua_assert(gola_isgoto(vg));
> -  lua_assert(bc_op(*ip) == BC_JMP || bc_op(*ip) == BC_UCLO);
> +  lj_assertFS(gola_isgoto(vg), "expected goto");
> +  lj_assertFS(bc_op(*ip) == BC_JMP || bc_op(*ip) == BC_UCLO,
> +	      "bad bytecode op %d", bc_op(*ip));
>     setbc_a(ip, vg->slot);
>     if (bc_op(*ip) == BC_JMP) {
>       BCPos next = jmp_next(fs, pc);
> @@ -1206,9 +1220,9 @@ static void gola_resolve(LexState *ls, FuncScope *bl, MSize idx)
>       if (gcrefeq(vg->name, vl->name) && gola_isgoto(vg)) {
>         if (vg->slot < vl->slot) {
>   	GCstr *name = strref(var_get(ls, ls->fs, vg->slot).name);
> -	lua_assert((uintptr_t)name >= VARNAME__MAX);
> +	lj_assertLS((uintptr_t)name >= VARNAME__MAX, "expected goto name");
>   	ls->linenumber = ls->fs->bcbase[vg->startpc].line;
> -	lua_assert(strref(vg->name) != NAME_BREAK);
> +	lj_assertLS(strref(vg->name) != NAME_BREAK, "unexpected break");
>   	lj_lex_error(ls, 0, LJ_ERR_XGSCOPE,
>   		     strdata(strref(vg->name)), strdata(name));
>         }
> @@ -1272,7 +1286,7 @@ static void fscope_begin(FuncState *fs, FuncScope *bl, int flags)
>     bl->vstart = fs->ls->vtop;
>     bl->prev = fs->bl;
>     fs->bl = bl;
> -  lua_assert(fs->freereg == fs->nactvar);
> +  lj_assertFS(fs->freereg == fs->nactvar, "bad regalloc");
>   }
>   
>   /* End a scope. */
> @@ -1283,7 +1297,7 @@ static void fscope_end(FuncState *fs)
>     fs->bl = bl->prev;
>     var_remove(ls, bl->nactvar);
>     fs->freereg = fs->nactvar;
> -  lua_assert(bl->nactvar == fs->nactvar);
> +  lj_assertFS(bl->nactvar == fs->nactvar, "bad regalloc");
>     if ((bl->flags & (FSCOPE_UPVAL|FSCOPE_NOCLOSE)) == FSCOPE_UPVAL)
>       bcemit_AJ(fs, BC_UCLO, bl->nactvar, 0);
>     if ((bl->flags & FSCOPE_BREAK)) {
> @@ -1370,13 +1384,13 @@ static void fs_fixup_k(FuncState *fs, GCproto *pt, void *kptr)
>       Node *n = &node[i];
>       if (tvhaskslot(&n->val)) {
>         ptrdiff_t kidx = (ptrdiff_t)tvkslot(&n->val);
> -      lua_assert(!tvisint(&n->key));
> +      lj_assertFS(!tvisint(&n->key), "unexpected integer key");
>         if (tvisnum(&n->key)) {
>   	TValue *tv = &((TValue *)kptr)[kidx];
>   	if (LJ_DUALNUM) {
>   	  lua_Number nn = numV(&n->key);
>   	  int32_t k = lj_num2int(nn);
> -	  lua_assert(!tvismzero(&n->key));
> +	  lj_assertFS(!tvismzero(&n->key), "unexpected -0 key");
>   	  if ((lua_Number)k == nn)
>   	    setintV(tv, k);
>   	  else
> @@ -1424,21 +1438,21 @@ static void fs_fixup_line(FuncState *fs, GCproto *pt,
>       uint8_t *li = (uint8_t *)lineinfo;
>       do {
>         BCLine delta = base[i].line - first;
> -      lua_assert(delta >= 0 && delta < 256);
> +      lj_assertFS(delta >= 0 && delta < 256, "bad line delta");
>         li[i] = (uint8_t)delta;
>       } while (++i < n);
>     } else if (LJ_LIKELY(numline < 65536)) {
>       uint16_t *li = (uint16_t *)lineinfo;
>       do {
>         BCLine delta = base[i].line - first;
> -      lua_assert(delta >= 0 && delta < 65536);
> +      lj_assertFS(delta >= 0 && delta < 65536, "bad line delta");
>         li[i] = (uint16_t)delta;
>       } while (++i < n);
>     } else {
>       uint32_t *li = (uint32_t *)lineinfo;
>       do {
>         BCLine delta = base[i].line - first;
> -      lua_assert(delta >= 0);
> +      lj_assertFS(delta >= 0, "bad line delta");
>         li[i] = (uint32_t)delta;
>       } while (++i < n);
>     }
> @@ -1528,7 +1542,7 @@ static void fs_fixup_ret(FuncState *fs)
>     }
>     fs->bl->flags |= FSCOPE_NOCLOSE;  /* Handled above. */
>     fscope_end(fs);
> -  lua_assert(fs->bl == NULL);
> +  lj_assertFS(fs->bl == NULL, "bad scope nesting");
>     /* May need to fixup returns encoded before first function was created. */
>     if (fs->flags & PROTO_FIXUP_RETURN) {
>       BCPos pc;
> @@ -1608,7 +1622,7 @@ static GCproto *fs_finish(LexState *ls, BCLine line)
>     L->top--;  /* Pop table of constants. */
>     ls->vtop = fs->vbase;  /* Reset variable stack. */
>     ls->fs = fs->prev;
> -  lua_assert(ls->fs != NULL || ls->tok == TK_eof);
> +  lj_assertL(ls->fs != NULL || ls->tok == TK_eof, "bad parser state");
>     return pt;
>   }
>   
> @@ -1702,14 +1716,15 @@ static void expr_bracket(LexState *ls, ExpDesc *v)
>   }
>   
>   /* Get value of constant expression. */
> -static void expr_kvalue(TValue *v, ExpDesc *e)
> +static void expr_kvalue(FuncState *fs, TValue *v, ExpDesc *e)
>   {
> +  UNUSED(fs);
>     if (e->k <= VKTRUE) {
>       setpriV(v, ~(uint32_t)e->k);
>     } else if (e->k == VKSTR) {
>       setgcVraw(v, obj2gco(e->u.sval), LJ_TSTR);
>     } else {
> -    lua_assert(tvisnumber(expr_numtv(e)));
> +    lj_assertFS(tvisnumber(expr_numtv(e)), "bad number constant");
>       *v = *expr_numtv(e);
>     }
>   }
> @@ -1759,11 +1774,11 @@ static void expr_table(LexState *ls, ExpDesc *e)
>   	fs->bcbase[pc].ins = BCINS_AD(BC_TDUP, freg-1, kidx);
>         }
>         vcall = 0;
> -      expr_kvalue(&k, &key);
> +      expr_kvalue(fs, &k, &key);
>         v = lj_tab_set(fs->L, t, &k);
>         lj_gc_anybarriert(fs->L, t);
>         if (expr_isk_nojump(&val)) {  /* Add const key/value to template table. */
> -	expr_kvalue(v, &val);
> +	expr_kvalue(fs, v, &val);
>         } else {  /* Otherwise create dummy string key (avoids lj_tab_newkey). */
>   	settabV(fs->L, v, t);  /* Preserve key with table itself as value. */
>   	fixt = 1;   /* Fix this later, after all resizes. */
> @@ -1782,8 +1797,9 @@ static void expr_table(LexState *ls, ExpDesc *e)
>     if (vcall) {
>       BCInsLine *ilp = &fs->bcbase[fs->pc-1];
>       ExpDesc en;
> -    lua_assert(bc_a(ilp->ins) == freg &&
> -	       bc_op(ilp->ins) == (narr > 256 ? BC_TSETV : BC_TSETB));
> +    lj_assertFS(bc_a(ilp->ins) == freg &&
> +		bc_op(ilp->ins) == (narr > 256 ? BC_TSETV : BC_TSETB),
> +		"bad CALL code generation");
>       expr_init(&en, VKNUM, 0);
>       en.u.nval.u32.lo = narr-1;
>       en.u.nval.u32.hi = 0x43300000;  /* Biased integer to avoid denormals. */
> @@ -1813,7 +1829,7 @@ static void expr_table(LexState *ls, ExpDesc *e)
>         for (i = 0; i <= hmask; i++) {
>   	Node *n = &node[i];
>   	if (tvistab(&n->val)) {
> -	  lua_assert(tabV(&n->val) == t);
> +	  lj_assertFS(tabV(&n->val) == t, "bad dummy key in template table");
>   	  setnilV(&n->val);  /* Turn value into nil. */
>   	}
>         }
> @@ -1844,7 +1860,7 @@ static BCReg parse_params(LexState *ls, int needself)
>       } while (lex_opt(ls, ','));
>     }
>     var_add(ls, nparams);
> -  lua_assert(fs->nactvar == nparams);
> +  lj_assertFS(fs->nactvar == nparams, "bad regalloc");
>     bcreg_reserve(fs, nparams);
>     lex_check(ls, ')');
>     return nparams;
> @@ -1931,7 +1947,7 @@ static void parse_args(LexState *ls, ExpDesc *e)
>       err_syntax(ls, LJ_ERR_XFUNARG);
>       return;  /* Silence compiler. */
>     }
> -  lua_assert(e->k == VNONRELOC);
> +  lj_assertFS(e->k == VNONRELOC, "bad expr type %d", e->k);
>     base = e->u.s.info;  /* Base register for call. */
>     if (args.k == VCALL) {
>       ins = BCINS_ABC(BC_CALLM, base, 2, args.u.s.aux - base - 1 - LJ_FR2);
> @@ -2701,8 +2717,9 @@ static void parse_chunk(LexState *ls)
>     while (!islast && !parse_isend(ls->tok)) {
>       islast = parse_stmt(ls);
>       lex_opt(ls, ';');
> -    lua_assert(ls->fs->framesize >= ls->fs->freereg &&
> -	       ls->fs->freereg >= ls->fs->nactvar);
> +    lj_assertLS(ls->fs->framesize >= ls->fs->freereg &&
> +		ls->fs->freereg >= ls->fs->nactvar,
> +		"bad regalloc");
>       ls->fs->freereg = ls->fs->nactvar;  /* Free registers after each stmt. */
>     }
>     synlevel_end(ls);
> @@ -2737,9 +2754,8 @@ GCproto *lj_parse(LexState *ls)
>       err_token(ls, TK_eof);
>     pt = fs_finish(ls, ls->linenumber);
>     L->top--;  /* Drop chunkname. */
> -  lua_assert(fs.prev == NULL);
> -  lua_assert(ls->fs == NULL);
> -  lua_assert(pt->sizeuv == 0);
> +  lj_assertL(fs.prev == NULL && ls->fs == NULL, "mismatched frame nesting");
> +  lj_assertL(pt->sizeuv == 0, "toplevel proto has upvalues");
>     return pt;
>   }
>   
> diff --git a/src/lj_record.c b/src/lj_record.c
> index 6030f77c..d1332bfc 100644
> --- a/src/lj_record.c
> +++ b/src/lj_record.c
> @@ -50,34 +50,52 @@
>   static void rec_check_ir(jit_State *J)
>   {
>     IRRef i, nins = J->cur.nins, nk = J->cur.nk;
> -  lua_assert(nk <= REF_BIAS && nins >= REF_BIAS && nins < 65536);
> +  lj_assertJ(nk <= REF_BIAS && nins >= REF_BIAS && nins < 65536,
> +	     "inconsistent IR layout");
>     for (i = nk; i < nins; i++) {
>       IRIns *ir = IR(i);
>       uint32_t mode = lj_ir_mode[ir->o];
>       IRRef op1 = ir->op1;
>       IRRef op2 = ir->op2;
> +    const char *err = NULL;
>       switch (irm_op1(mode)) {
> -    case IRMnone: lua_assert(op1 == 0); break;
> -    case IRMref: lua_assert(op1 >= nk);
> -      lua_assert(i >= REF_BIAS ? op1 < i : op1 > i); break;
> +    case IRMnone:
> +      if (op1 != 0) err = "IRMnone op1 used";
> +      break;
> +    case IRMref:
> +      if (op1 < nk || (i >= REF_BIAS ? op1 >= i : op1 <= i))
> +	err = "IRMref op1 out of range";
> +      break;
>       case IRMlit: break;
> -    case IRMcst: lua_assert(i < REF_BIAS);
> +    case IRMcst:
> +      if (i >= REF_BIAS) { err = "constant in IR range"; break; }
>         if (irt_is64(ir->t) && ir->o != IR_KNULL)
>   	i++;
>         continue;
>       }
>       switch (irm_op2(mode)) {
> -    case IRMnone: lua_assert(op2 == 0); break;
> -    case IRMref: lua_assert(op2 >= nk);
> -      lua_assert(i >= REF_BIAS ? op2 < i : op2 > i); break;
> +    case IRMnone:
> +      if (op2) err = "IRMnone op2 used";
> +      break;
> +    case IRMref:
> +      if (op2 < nk || (i >= REF_BIAS ? op2 >= i : op2 <= i))
> +	err = "IRMref op2 out of range";
> +      break;
>       case IRMlit: break;
> -    case IRMcst: lua_assert(0); break;
> +    case IRMcst: err = "IRMcst op2"; break;
>       }
> -    if (ir->prev) {
> -      lua_assert(ir->prev >= nk);
> -      lua_assert(i >= REF_BIAS ? ir->prev < i : ir->prev > i);
> -      lua_assert(ir->o == IR_NOP || IR(ir->prev)->o == ir->o);
> +    if (!err && ir->prev) {
> +      if (ir->prev < nk || (i >= REF_BIAS ? ir->prev >= i : ir->prev <= i))
> +	err = "chain out of range";
> +      else if (ir->o != IR_NOP && IR(ir->prev)->o != ir->o)
> +	err = "chain to different op";
>       }
> +    lj_assertJ(!err, "bad IR %04d op %d(%04d,%04d): %s",
> +	       i-REF_BIAS,
> +	       ir->o,
> +	       irm_op1(mode) == IRMref ? op1-REF_BIAS : op1,
> +	       irm_op2(mode) == IRMref ? op2-REF_BIAS : op2,
> +	       err);
>     }
>   }
>   
> @@ -87,9 +105,10 @@ static void rec_check_slots(jit_State *J)
>     BCReg s, nslots = J->baseslot + J->maxslot;
>     int32_t depth = 0;
>     cTValue *base = J->L->base - J->baseslot;
> -  lua_assert(J->baseslot >= 1+LJ_FR2);
> -  lua_assert(J->baseslot == 1+LJ_FR2 || (J->slot[J->baseslot-1] & TREF_FRAME));
> -  lua_assert(nslots <= LJ_MAX_JSLOTS);
> +  lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot");
> +  lj_assertJ(J->baseslot == 1+LJ_FR2 || (J->slot[J->baseslot-1] & TREF_FRAME),
> +	     "baseslot does not point to frame");
> +  lj_assertJ(nslots <= LJ_MAX_JSLOTS, "slot overflow");
>     for (s = 0; s < nslots; s++) {
>       TRef tr = J->slot[s];
>       if (tr) {
> @@ -97,56 +116,65 @@ static void rec_check_slots(jit_State *J)
>         IRRef ref = tref_ref(tr);
>         IRIns *ir = NULL;  /* Silence compiler. */
>         if (!LJ_FR2 || ref || !(tr & (TREF_FRAME | TREF_CONT))) {
> -	lua_assert(ref >= J->cur.nk && ref < J->cur.nins);
> +	lj_assertJ(ref >= J->cur.nk && ref < J->cur.nins,
> +		   "slot %d ref %04d out of range", s, ref - REF_BIAS);
>   	ir = IR(ref);
> -	lua_assert(irt_t(ir->t) == tref_t(tr));
> +	lj_assertJ(irt_t(ir->t) == tref_t(tr), "slot %d IR type mismatch", s);
>         }
>         if (s == 0) {
> -	lua_assert(tref_isfunc(tr));
> +	lj_assertJ(tref_isfunc(tr), "frame slot 0 is not a function");
>   #if LJ_FR2
>         } else if (s == 1) {
> -	lua_assert((tr & ~TREF_FRAME) == 0);
> +	lj_assertJ((tr & ~TREF_FRAME) == 0, "bad frame slot 1");
>   #endif
>         } else if ((tr & TREF_FRAME)) {
>   	GCfunc *fn = gco2func(frame_gc(tv));
>   	BCReg delta = (BCReg)(tv - frame_prev(tv));
>   #if LJ_FR2
> -	if (ref)
> -	  lua_assert(ir_knum(ir)->u64 == tv->u64);
> +	lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
> +		   "frame slot %d PC mismatch", s);
>   	tr = J->slot[s-1];
>   	ir = IR(tref_ref(tr));
>   #endif
> -	lua_assert(tref_isfunc(tr));
> -	if (tref_isk(tr)) lua_assert(fn == ir_kfunc(ir));
> -	lua_assert(s > delta + LJ_FR2 ? (J->slot[s-delta] & TREF_FRAME)
> -				      : (s == delta + LJ_FR2));
> +	lj_assertJ(tref_isfunc(tr),
> +		   "frame slot %d is not a function", s-LJ_FR2);
> +	lj_assertJ(!tref_isk(tr) || fn == ir_kfunc(ir),
> +		   "frame slot %d function mismatch", s-LJ_FR2);
> +	lj_assertJ(s > delta + LJ_FR2 ? (J->slot[s-delta] & TREF_FRAME)
> +				      : (s == delta + LJ_FR2),
> +		   "frame slot %d broken chain", s-LJ_FR2);
>   	depth++;
>         } else if ((tr & TREF_CONT)) {
>   #if LJ_FR2
> -	if (ref)
> -	  lua_assert(ir_knum(ir)->u64 == tv->u64);
> +	lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
> +		   "cont slot %d continuation mismatch", s);
>   #else
> -	lua_assert(ir_kptr(ir) == gcrefp(tv->gcr, void));
> +	lj_assertJ(ir_kptr(ir) == gcrefp(tv->gcr, void),
> +		   "cont slot %d continuation mismatch", s);
>   #endif
> -	lua_assert((J->slot[s+1+LJ_FR2] & TREF_FRAME));
> +	lj_assertJ((J->slot[s+1+LJ_FR2] & TREF_FRAME),
> +		   "cont slot %d not followed by frame", s);
>   	depth++;
>         } else {
> -	if (tvisnumber(tv))
> -	  lua_assert(tref_isnumber(tr));  /* Could be IRT_INT etc., too. */
> -	else
> -	  lua_assert(itype2irt(tv) == tref_type(tr));
> +	/* Number repr. may differ, but other types must be the same. */
> +	lj_assertJ(tvisnumber(tv) ? tref_isnumber(tr) :
> +				    itype2irt(tv) == tref_type(tr),
> +		   "slot %d type mismatch: stack type %d vs IR type %d",
> +		   s, itypemap(tv), tref_type(tr));
>   	if (tref_isk(tr)) {  /* Compare constants. */
>   	  TValue tvk;
>   	  lj_ir_kvalue(J->L, &tvk, ir);
> -	  if (!(tvisnum(&tvk) && tvisnan(&tvk)))
> -	    lua_assert(lj_obj_equal(tv, &tvk));
> -	  else
> -	    lua_assert(tvisnum(tv) && tvisnan(tv));
> +	  lj_assertJ((tvisnum(&tvk) && tvisnan(&tvk)) ?
> +		     (tvisnum(tv) && tvisnan(tv)) :
> +		     lj_obj_equal(tv, &tvk),
> +		     "slot %d const mismatch: stack %016llx vs IR %016llx",
> +		     s, tv->u64, tvk.u64);
>   	}
>         }
>       }
>     }
> -  lua_assert(J->framedepth == depth);
> +  lj_assertJ(J->framedepth == depth,
> +	     "frame depth mismatch %d vs %d", J->framedepth, depth);
>   }
>   #endif
>   
> @@ -182,7 +210,7 @@ static TRef getcurrf(jit_State *J)
>   {
>     if (J->base[-1-LJ_FR2])
>       return J->base[-1-LJ_FR2];
> -  lua_assert(J->baseslot == 1+LJ_FR2);
> +  lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot");
>     return sloadt(J, -1-LJ_FR2, IRT_FUNC, IRSLOAD_READONLY);
>   }
>   
> @@ -427,7 +455,8 @@ static void rec_for_loop(jit_State *J, const BCIns *fori, ScEvEntry *scev,
>     TRef stop = fori_arg(J, fori, ra+FORL_STOP, t, mode);
>     TRef step = fori_arg(J, fori, ra+FORL_STEP, t, mode);
>     int tc, dir = rec_for_direction(&tv[FORL_STEP]);
> -  lua_assert(bc_op(*fori) == BC_FORI || bc_op(*fori) == BC_JFORI);
> +  lj_assertJ(bc_op(*fori) == BC_FORI || bc_op(*fori) == BC_JFORI,
> +	     "bad bytecode %d instead of FORI/JFORI", bc_op(*fori));
>     scev->t.irt = t;
>     scev->dir = dir;
>     scev->stop = tref_ref(stop);
> @@ -483,7 +512,7 @@ static LoopEvent rec_for(jit_State *J, const BCIns *fori, int isforl)
>   						   IRT_NUM;
>       for (i = FORL_IDX; i <= FORL_STEP; i++) {
>         if (!tr[i]) sload(J, ra+i);
> -      lua_assert(tref_isnumber_str(tr[i]));
> +      lj_assertJ(tref_isnumber_str(tr[i]), "bad FORI argument type");
>         if (tref_isstr(tr[i]))
>   	tr[i] = emitir(IRTG(IR_STRTO, IRT_NUM), tr[i], 0);
>         if (t == IRT_INT) {
> @@ -615,7 +644,8 @@ static void rec_loop_jit(jit_State *J, TraceNo lnk, LoopEvent ev)
>   static int rec_profile_need(jit_State *J, GCproto *pt, const BCIns *pc)
>   {
>     GCproto *ppt;
> -  lua_assert(J->prof_mode == 'f' || J->prof_mode == 'l');
> +  lj_assertJ(J->prof_mode == 'f' || J->prof_mode == 'l',
> +	     "bad profiler mode %c", J->prof_mode);
>     if (!pt)
>       return 0;
>     ppt = J->prev_pt;
> @@ -793,7 +823,7 @@ void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
>       BCReg cbase = (BCReg)frame_delta(frame);
>       if (--J->framedepth <= 0)
>         lj_trace_err(J, LJ_TRERR_NYIRETL);
> -    lua_assert(J->baseslot > 1+LJ_FR2);
> +    lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
>       gotresults++;
>       rbase += cbase;
>       J->baseslot -= (BCReg)cbase;
> @@ -818,7 +848,7 @@ void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
>       BCReg cbase = (BCReg)frame_delta(frame);
>       if (--J->framedepth < 0)  /* NYI: return of vararg func to lower frame. */
>         lj_trace_err(J, LJ_TRERR_NYIRETL);
> -    lua_assert(J->baseslot > 1+LJ_FR2);
> +    lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
>       rbase += cbase;
>       J->baseslot -= (BCReg)cbase;
>       J->base -= cbase;
> @@ -845,7 +875,7 @@ void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
>       J->maxslot = cbase+(BCReg)nresults;
>       if (J->framedepth > 0) {  /* Return to a frame that is part of the trace. */
>         J->framedepth--;
> -      lua_assert(J->baseslot > cbase+1+LJ_FR2);
> +      lj_assertJ(J->baseslot > cbase+1+LJ_FR2, "bad baseslot for return");
>         J->baseslot -= cbase+1+LJ_FR2;
>         J->base -= cbase+1+LJ_FR2;
>       } else if (J->parent == 0 && J->exitno == 0 &&
> @@ -860,7 +890,7 @@ void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
>         emitir(IRTG(IR_RETF, IRT_PGC), trpt, trpc);
>         J->retdepth++;
>         J->needsnap = 1;
> -      lua_assert(J->baseslot == 1+LJ_FR2);
> +      lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot for return");
>         /* Shift result slots up and clear the slots of the new frame below. */
>         memmove(J->base + cbase, J->base-1-LJ_FR2, sizeof(TRef)*nresults);
>         memset(J->base-1-LJ_FR2, 0, sizeof(TRef)*(cbase+1+LJ_FR2));
> @@ -908,12 +938,13 @@ void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
>         }  /* Otherwise continue with another __concat call. */
>       } else {
>         /* Result type already specialized. */
> -      lua_assert(cont == lj_cont_condf || cont == lj_cont_condt);
> +      lj_assertJ(cont == lj_cont_condf || cont == lj_cont_condt,
> +		 "bad continuation type");
>       }
>     } else {
>       lj_trace_err(J, LJ_TRERR_NYIRETL);  /* NYI: handle return to C frame. */
>     }
> -  lua_assert(J->baseslot >= 1+LJ_FR2);
> +  lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot for return");
>   }
>   
>   /* -- Metamethod handling ------------------------------------------------- */
> @@ -1168,7 +1199,7 @@ static void rec_mm_comp_cdata(jit_State *J, RecordIndex *ix, int op, MMS mm)
>       ix->tab = ix->val;
>       copyTV(J->L, &ix->tabv, &ix->valv);
>     } else {
> -    lua_assert(tref_iscdata(ix->key));
> +    lj_assertJ(tref_iscdata(ix->key), "cdata expected");
>       ix->tab = ix->key;
>       copyTV(J->L, &ix->tabv, &ix->keyv);
>     }
> @@ -1265,7 +1296,8 @@ static void rec_idx_abc(jit_State *J, TRef asizeref, TRef ikey, uint32_t asize)
>       /* Got scalar evolution analysis results for this reference? */
>       if (ref == J->scev.idx) {
>         int32_t stop;
> -      lua_assert(irt_isint(J->scev.t) && ir->o == IR_SLOAD);
> +      lj_assertJ(irt_isint(J->scev.t) && ir->o == IR_SLOAD,
> +		 "only int SCEV supported");
>         stop = numberVint(&(J->L->base - J->baseslot)[ir->op1 + FORL_STOP]);
>         /* Runtime value for stop of loop is within bounds? */
>         if ((uint64_t)stop + ofs < (uint64_t)asize) {
> @@ -1383,7 +1415,7 @@ TRef lj_record_idx(jit_State *J, RecordIndex *ix)
>   
>     while (!tref_istab(ix->tab)) { /* Handle non-table lookup. */
>       /* Never call raw lj_record_idx() on non-table. */
> -    lua_assert(ix->idxchain != 0);
> +    lj_assertJ(ix->idxchain != 0, "bad usage");
>       if (!lj_record_mm_lookup(J, ix, ix->val ? MM_newindex : MM_index))
>         lj_trace_err(J, LJ_TRERR_NOMM);
>     handlemm:
> @@ -1467,10 +1499,10 @@ TRef lj_record_idx(jit_State *J, RecordIndex *ix)
>   	emitir(IRTG(oldv == niltvg(J2G(J)) ? IR_EQ : IR_NE, IRT_PGC),
>   	       xref, lj_ir_kkptr(J, niltvg(J2G(J))));
>         if (ix->idxchain && lj_record_mm_lookup(J, ix, MM_newindex)) {
> -	lua_assert(hasmm);
> +	lj_assertJ(hasmm, "inconsistent metamethod handling");
>   	goto handlemm;
>         }
> -      lua_assert(!hasmm);
> +      lj_assertJ(!hasmm, "inconsistent metamethod handling");
>         if (oldv == niltvg(J2G(J))) {  /* Need to insert a new key. */
>   	TRef key = ix->key;
>   	if (tref_isinteger(key))  /* NEWREF needs a TValue as a key. */
> @@ -1578,7 +1610,7 @@ static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
>     int needbarrier = 0;
>     if (rec_upvalue_constify(J, uvp)) {  /* Try to constify immutable upvalue. */
>       TRef tr, kfunc;
> -    lua_assert(val == 0);
> +    lj_assertJ(val == 0, "bad usage");
>       if (!tref_isk(fn)) {  /* Late specialization of current function. */
>         if (J->pt->flags >= PROTO_CLC_POLY)
>   	goto noconstify;
> @@ -1700,7 +1732,7 @@ static void rec_func_vararg(jit_State *J)
>   {
>     GCproto *pt = J->pt;
>     BCReg s, fixargs, vframe = J->maxslot+1+LJ_FR2;
> -  lua_assert((pt->flags & PROTO_VARARG));
> +  lj_assertJ((pt->flags & PROTO_VARARG), "FUNCV in non-vararg function");
>     if (J->baseslot + vframe + pt->framesize >= LJ_MAX_JSLOTS)
>       lj_trace_err(J, LJ_TRERR_STACKOV);
>     J->base[vframe-1-LJ_FR2] = J->base[-1-LJ_FR2];  /* Copy function up. */
> @@ -1769,7 +1801,7 @@ static void rec_varg(jit_State *J, BCReg dst, ptrdiff_t nresults)
>   {
>     int32_t numparams = J->pt->numparams;
>     ptrdiff_t nvararg = frame_delta(J->L->base-1) - numparams - 1 - LJ_FR2;
> -  lua_assert(frame_isvarg(J->L->base-1));
> +  lj_assertJ(frame_isvarg(J->L->base-1), "VARG in non-vararg frame");
>     if (LJ_FR2 && dst > J->maxslot)
>       J->base[dst-1] = 0;  /* Prevent resurrection of unrelated slot. */
>     if (J->framedepth > 0) {  /* Simple case: varargs defined on-trace. */
> @@ -1887,7 +1919,7 @@ static TRef rec_cat(jit_State *J, BCReg baseslot, BCReg topslot)
>     TValue savetv[5];
>     BCReg s;
>     RecordIndex ix;
> -  lua_assert(baseslot < topslot);
> +  lj_assertJ(baseslot < topslot, "bad CAT arg");
>     for (s = baseslot; s <= topslot; s++)
>       (void)getslot(J, s);  /* Ensure all arguments have a reference. */
>     if (tref_isnumber_str(top[0]) && tref_isnumber_str(top[-1])) {
> @@ -2011,7 +2043,7 @@ void lj_record_ins(jit_State *J)
>         if (bc_op(*J->pc) >= BC__MAX)
>   	return;
>         break;
> -    default: lua_assert(0); break;
> +    default: lj_assertJ(0, "bad post-processing mode"); break;
>       }
>       J->postproc = LJ_POST_NONE;
>     }
> @@ -2379,7 +2411,8 @@ void lj_record_ins(jit_State *J)
>         J->loopref = J->cur.nins;
>       break;
>     case BC_JFORI:
> -    lua_assert(bc_op(pc[(ptrdiff_t)rc-BCBIAS_J]) == BC_JFORL);
> +    lj_assertJ(bc_op(pc[(ptrdiff_t)rc-BCBIAS_J]) == BC_JFORL,
> +	       "JFORI does not point to JFORL");
>       if (rec_for(J, pc, 0) != LOOPEV_LEAVE)  /* Link to existing loop. */
>         lj_record_stop(J, LJ_TRLINK_ROOT, bc_d(pc[(ptrdiff_t)rc-BCBIAS_J]));
>       /* Continue tracing if the loop is not entered. */
> @@ -2432,7 +2465,8 @@ void lj_record_ins(jit_State *J)
>       rec_func_lua(J);
>       break;
>     case BC_JFUNCV:
> -    lua_assert(0);  /* Cannot happen. No hotcall counting for varag funcs. */
> +    /* Cannot happen. No hotcall counting for varag funcs. */
> +    lj_assertJ(0, "unsupported vararg hotcall");
>       break;
>   
>     case BC_FUNCC:
> @@ -2492,11 +2526,11 @@ static const BCIns *rec_setup_root(jit_State *J)
>       J->bc_min = pc;
>       break;
>     case BC_ITERL:
> -    lua_assert(bc_op(pc[-1]) == BC_ITERC);
> +    lj_assertJ(bc_op(pc[-1]) == BC_ITERC, "no ITERC before ITERL");
>       J->maxslot = ra + bc_b(pc[-1]) - 1;
>       J->bc_extent = (MSize)(-bc_j(ins))*sizeof(BCIns);
>       pc += 1+bc_j(ins);
> -    lua_assert(bc_op(pc[-1]) == BC_JMP);
> +    lj_assertJ(bc_op(pc[-1]) == BC_JMP, "ITERL does not point to JMP+1");
>       J->bc_min = pc;
>       break;
>     case BC_LOOP:
> @@ -2528,7 +2562,7 @@ static const BCIns *rec_setup_root(jit_State *J)
>       pc++;
>       break;
>     default:
> -    lua_assert(0);
> +    lj_assertJ(0, "bad root trace start bytecode %d", bc_op(ins));
>       break;
>     }
>     return pc;
> diff --git a/src/lj_snap.c b/src/lj_snap.c
> index 9146cddc..2dc281cb 100644
> --- a/src/lj_snap.c
> +++ b/src/lj_snap.c
> @@ -110,7 +110,7 @@ static MSize snapshot_framelinks(jit_State *J, SnapEntry *map, uint8_t *topslot)
>     cTValue *ftop = isluafunc(fn) ? (frame+funcproto(fn)->framesize) : J->L->top;
>   #if LJ_FR2
>     uint64_t pcbase = (u64ptr(J->pc) << 8) | (J->baseslot - 2);
> -  lua_assert(2 <= J->baseslot && J->baseslot <= 257);
> +  lj_assertJ(2 <= J->baseslot && J->baseslot <= 257, "bad baseslot");
>     memcpy(map, &pcbase, sizeof(uint64_t));
>   #else
>     MSize f = 0;
> @@ -129,7 +129,7 @@ static MSize snapshot_framelinks(jit_State *J, SnapEntry *map, uint8_t *topslot)
>   #endif
>         frame = frame_prevd(frame);
>       } else {
> -      lua_assert(!frame_isc(frame));
> +      lj_assertJ(!frame_isc(frame), "broken frame chain");
>   #if !LJ_FR2
>         map[f++] = SNAP_MKFTSZ(frame_ftsz(frame));
>   #endif
> @@ -141,10 +141,10 @@ static MSize snapshot_framelinks(jit_State *J, SnapEntry *map, uint8_t *topslot)
>     }
>     *topslot = (uint8_t)(ftop - lim);
>   #if LJ_FR2
> -  lua_assert(sizeof(SnapEntry) * 2 == sizeof(uint64_t));
> +  lj_assertJ(sizeof(SnapEntry) * 2 == sizeof(uint64_t), "bad SnapEntry def");
>     return 2;
>   #else
> -  lua_assert(f == (MSize)(1 + J->framedepth));
> +  lj_assertJ(f == (MSize)(1 + J->framedepth), "miscalculated snapshot size");
>     return f;
>   #endif
>   }
> @@ -223,7 +223,8 @@ static BCReg snap_usedef(jit_State *J, uint8_t *udf,
>   #define DEF_SLOT(s)		udf[(s)] *= 3
>   
>     /* Scan through following bytecode and check for uses/defs. */
> -  lua_assert(pc >= proto_bc(J->pt) && pc < proto_bc(J->pt) + J->pt->sizebc);
> +  lj_assertJ(pc >= proto_bc(J->pt) && pc < proto_bc(J->pt) + J->pt->sizebc,
> +	     "snapshot PC out of range");
>     for (;;) {
>       BCIns ins = *pc++;
>       BCOp op = bc_op(ins);
> @@ -234,7 +235,7 @@ static BCReg snap_usedef(jit_State *J, uint8_t *udf,
>       switch (bcmode_c(op)) {
>       case BCMvar: USE_SLOT(bc_c(ins)); break;
>       case BCMrbase:
> -      lua_assert(op == BC_CAT);
> +      lj_assertJ(op == BC_CAT, "unhandled op %d with RC rbase", op);
>         for (s = bc_b(ins); s <= bc_c(ins); s++) USE_SLOT(s);
>         for (; s < maxslot; s++) DEF_SLOT(s);
>         break;
> @@ -288,7 +289,8 @@ static BCReg snap_usedef(jit_State *J, uint8_t *udf,
>         break;
>       default: break;
>       }
> -    lua_assert(pc >= proto_bc(J->pt) && pc < proto_bc(J->pt) + J->pt->sizebc);
> +    lj_assertJ(pc >= proto_bc(J->pt) && pc < proto_bc(J->pt) + J->pt->sizebc,
> +	       "use/def analysis PC out of range");
>     }
>   
>   #undef USE_SLOT
> @@ -361,19 +363,20 @@ static RegSP snap_renameref(GCtrace *T, SnapNo lim, IRRef ref, RegSP rs)
>   }
>   
>   /* Copy RegSP from parent snapshot to the parent links of the IR. */
> -IRIns *lj_snap_regspmap(GCtrace *T, SnapNo snapno, IRIns *ir)
> +IRIns *lj_snap_regspmap(jit_State *J, GCtrace *T, SnapNo snapno, IRIns *ir)
>   {
>     SnapShot *snap = &T->snap[snapno];
>     SnapEntry *map = &T->snapmap[snap->mapofs];
>     BloomFilter rfilt = snap_renamefilter(T, snapno);
>     MSize n = 0;
>     IRRef ref = 0;
> +  UNUSED(J);
>     for ( ; ; ir++) {
>       uint32_t rs;
>       if (ir->o == IR_SLOAD) {
>         if (!(ir->op2 & IRSLOAD_PARENT)) break;
>         for ( ; ; n++) {
> -	lua_assert(n < snap->nent);
> +	lj_assertJ(n < snap->nent, "slot %d not found in snapshot", ir->op1);
>   	if (snap_slot(map[n]) == ir->op1) {
>   	  ref = snap_ref(map[n++]);
>   	  break;
> @@ -390,7 +393,7 @@ IRIns *lj_snap_regspmap(GCtrace *T, SnapNo snapno, IRIns *ir)
>       if (bloomtest(rfilt, ref))
>         rs = snap_renameref(T, snapno, ref, rs);
>       ir->prev = (uint16_t)rs;
> -    lua_assert(regsp_used(rs));
> +    lj_assertJ(regsp_used(rs), "unused IR %04d in snapshot", ref - REF_BIAS);
>     }
>     return ir;
>   }
> @@ -408,7 +411,7 @@ static TRef snap_replay_const(jit_State *J, IRIns *ir)
>     case IR_KNUM: case IR_KINT64:
>       return lj_ir_k64(J, (IROp)ir->o, ir_k64(ir)->u64);
>     case IR_KPTR: return lj_ir_kptr(J, ir_kptr(ir));  /* Continuation. */
> -  default: lua_assert(0); return TREF_NIL; break;
> +  default: lj_assertJ(0, "bad IR constant op %d", ir->o); return TREF_NIL;
>     }
>   }
>   
> @@ -486,7 +489,7 @@ void lj_snap_replay(jit_State *J, GCtrace *T)
>   	tr = snap_replay_const(J, ir);
>       } else if (!regsp_used(ir->prev)) {
>         pass23 = 1;
> -      lua_assert(s != 0);
> +      lj_assertJ(s != 0, "unused slot 0 in snapshot");
>         tr = s;
>       } else {
>         IRType t = irt_type(ir->t);
> @@ -512,8 +515,9 @@ void lj_snap_replay(jit_State *J, GCtrace *T)
>         if (regsp_reg(ir->r) == RID_SUNK) {
>   	if (J->slot[snap_slot(sn)] != snap_slot(sn)) continue;
>   	pass23 = 1;
> -	lua_assert(ir->o == IR_TNEW || ir->o == IR_TDUP ||
> -		   ir->o == IR_CNEW || ir->o == IR_CNEWI);
> +	lj_assertJ(ir->o == IR_TNEW || ir->o == IR_TDUP ||
> +		   ir->o == IR_CNEW || ir->o == IR_CNEWI,
> +		   "sunk parent IR %04d has bad op %d", refp - REF_BIAS, ir->o);
>   	if (ir->op1 >= T->nk) snap_pref(J, T, map, nent, seen, ir->op1);
>   	if (ir->op2 >= T->nk) snap_pref(J, T, map, nent, seen, ir->op2);
>   	if (LJ_HASFFI && ir->o == IR_CNEWI) {
> @@ -531,7 +535,8 @@ void lj_snap_replay(jit_State *J, GCtrace *T)
>   	    }
>   	}
>         } else if (!irref_isk(refp) && !regsp_used(ir->prev)) {
> -	lua_assert(ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT);
> +	lj_assertJ(ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT,
> +		   "sunk parent IR %04d has bad op %d", refp - REF_BIAS, ir->o);
>   	J->slot[snap_slot(sn)] = snap_pref(J, T, map, nent, seen, ir->op1);
>         }
>       }
> @@ -581,7 +586,9 @@ void lj_snap_replay(jit_State *J, GCtrace *T)
>   	      val = snap_pref(J, T, map, nent, seen, irs->op2);
>   	      if (val == 0) {
>   		IRIns *irc = &T->ir[irs->op2];
> -		lua_assert(irc->o == IR_CONV && irc->op2 == IRCONV_NUM_INT);
> +		lj_assertJ(irc->o == IR_CONV && irc->op2 == IRCONV_NUM_INT,
> +			   "sunk store for parent IR %04d with bad op %d",
> +			   refp - REF_BIAS, irc->o);
>   		val = snap_pref(J, T, map, nent, seen, irc->op1);
>   		val = emitir(IRTN(IR_CONV), val, IRCONV_NUM_INT);
>   	      } else if ((LJ_SOFTFP32 || (LJ_32 && LJ_HASFFI)) &&
> @@ -634,7 +641,9 @@ static void snap_restoreval(jit_State *J, GCtrace *T, ExitState *ex,
>       if (ir->o == IR_KPTR) {
>         o->u64 = (uint64_t)(uintptr_t)ir_kptr(ir);
>       } else {
> -      lua_assert(!(ir->o == IR_KKPTR || ir->o == IR_KNULL));
> +      lj_assertJ(!(ir->o == IR_KKPTR || ir->o == IR_KNULL),
> +		 "restore of const from IR %04d with bad op %d",
> +		 ref - REF_BIAS, ir->o);
>         lj_ir_kvalue(J->L, o, ir);
>       }
>       return;
> @@ -655,13 +664,14 @@ static void snap_restoreval(jit_State *J, GCtrace *T, ExitState *ex,
>         o->u64 = *(uint64_t *)sps;
>   #endif
>       } else {
> -      lua_assert(!irt_ispri(t));  /* PRI refs never have a spill slot. */
> +      lj_assertJ(!irt_ispri(t), "PRI ref with spill slot");
>         setgcV(J->L, o, (GCobj *)(uintptr_t)*(GCSize *)sps, irt_toitype(t));
>       }
>     } else {  /* Restore from register. */
>       Reg r = regsp_reg(rs);
>       if (ra_noreg(r)) {
> -      lua_assert(ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT);
> +      lj_assertJ(ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT,
> +		 "restore from IR %04d has no reg", ref - REF_BIAS);
>         snap_restoreval(J, T, ex, snapno, rfilt, ir->op1, o);
>         if (LJ_DUALNUM) setnumV(o, (lua_Number)intV(o));
>         return;
> @@ -689,7 +699,7 @@ static void snap_restoreval(jit_State *J, GCtrace *T, ExitState *ex,
>   
>   #if LJ_HASFFI
>   /* Restore raw data from the trace exit state. */
> -static void snap_restoredata(GCtrace *T, ExitState *ex,
> +static void snap_restoredata(jit_State *J, GCtrace *T, ExitState *ex,
>   			     SnapNo snapno, BloomFilter rfilt,
>   			     IRRef ref, void *dst, CTSize sz)
>   {
> @@ -697,6 +707,7 @@ static void snap_restoredata(GCtrace *T, ExitState *ex,
>     RegSP rs = ir->prev;
>     int32_t *src;
>     uint64_t tmp;
> +  UNUSED(J);
>     if (irref_isk(ref)) {
>       if (ir_isk64(ir)) {
>         src = (int32_t *)&ir[1];
> @@ -719,8 +730,9 @@ static void snap_restoredata(GCtrace *T, ExitState *ex,
>         Reg r = regsp_reg(rs);
>         if (ra_noreg(r)) {
>   	/* Note: this assumes CNEWI is never used for SOFTFP split numbers. */
> -	lua_assert(sz == 8 && ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT);
> -	snap_restoredata(T, ex, snapno, rfilt, ir->op1, dst, 4);
> +	lj_assertJ(sz == 8 && ir->o == IR_CONV && ir->op2 == IRCONV_NUM_INT,
> +		   "restore from IR %04d has no reg", ref - REF_BIAS);
> +	snap_restoredata(J, T, ex, snapno, rfilt, ir->op1, dst, 4);
>   	*(lua_Number *)dst = (lua_Number)*(int32_t *)dst;
>   	return;
>         }
> @@ -741,7 +753,8 @@ static void snap_restoredata(GCtrace *T, ExitState *ex,
>         if (LJ_64 && LJ_BE && sz == 4) src++;
>       }
>     }
> -  lua_assert(sz == 1 || sz == 2 || sz == 4 || sz == 8);
> +  lj_assertJ(sz == 1 || sz == 2 || sz == 4 || sz == 8,
> +	     "restore from IR %04d with bad size %d", ref - REF_BIAS, sz);
>     if (sz == 4) *(int32_t *)dst = *src;
>     else if (sz == 8) *(int64_t *)dst = *(int64_t *)src;
>     else if (sz == 1) *(int8_t *)dst = (int8_t)*src;
> @@ -754,8 +767,9 @@ static void snap_unsink(jit_State *J, GCtrace *T, ExitState *ex,
>   			SnapNo snapno, BloomFilter rfilt,
>   			IRIns *ir, TValue *o)
>   {
> -  lua_assert(ir->o == IR_TNEW || ir->o == IR_TDUP ||
> -	     ir->o == IR_CNEW || ir->o == IR_CNEWI);
> +  lj_assertJ(ir->o == IR_TNEW || ir->o == IR_TDUP ||
> +	     ir->o == IR_CNEW || ir->o == IR_CNEWI,
> +	     "sunk allocation with bad op %d", ir->o);
>   #if LJ_HASFFI
>     if (ir->o == IR_CNEW || ir->o == IR_CNEWI) {
>       CTState *cts = ctype_cts(J->L);
> @@ -766,13 +780,14 @@ static void snap_unsink(jit_State *J, GCtrace *T, ExitState *ex,
>       setcdataV(J->L, o, cd);
>       if (ir->o == IR_CNEWI) {
>         uint8_t *p = (uint8_t *)cdataptr(cd);
> -      lua_assert(sz == 4 || sz == 8);
> +      lj_assertJ(sz == 4 || sz == 8, "sunk cdata with bad size %d", sz);
>         if (LJ_32 && sz == 8 && ir+1 < T->ir + T->nins && (ir+1)->o == IR_HIOP) {
> -	snap_restoredata(T, ex, snapno, rfilt, (ir+1)->op2, LJ_LE?p+4:p, 4);
> +	snap_restoredata(J, T, ex, snapno, rfilt, (ir+1)->op2,
> +			 LJ_LE ? p+4 : p, 4);
>   	if (LJ_BE) p += 4;
>   	sz = 4;
>         }
> -      snap_restoredata(T, ex, snapno, rfilt, ir->op2, p, sz);
> +      snap_restoredata(J, T, ex, snapno, rfilt, ir->op2, p, sz);
>       } else {
>         IRIns *irs, *irlast = &T->ir[T->snap[snapno].ref];
>         for (irs = ir+1; irs < irlast; irs++)
> @@ -780,8 +795,11 @@ static void snap_unsink(jit_State *J, GCtrace *T, ExitState *ex,
>   	  IRIns *iro = &T->ir[T->ir[irs->op1].op2];
>   	  uint8_t *p = (uint8_t *)cd;
>   	  CTSize szs;
> -	  lua_assert(irs->o == IR_XSTORE && T->ir[irs->op1].o == IR_ADD);
> -	  lua_assert(iro->o == IR_KINT || iro->o == IR_KINT64);
> +	  lj_assertJ(irs->o == IR_XSTORE, "sunk store with bad op %d", irs->o);
> +	  lj_assertJ(T->ir[irs->op1].o == IR_ADD,
> +		     "sunk store with bad add op %d", T->ir[irs->op1].o);
> +	  lj_assertJ(iro->o == IR_KINT || iro->o == IR_KINT64,
> +		     "sunk store with bad const offset op %d", iro->o);
>   	  if (irt_is64(irs->t)) szs = 8;
>   	  else if (irt_isi8(irs->t) || irt_isu8(irs->t)) szs = 1;
>   	  else if (irt_isi16(irs->t) || irt_isu16(irs->t)) szs = 2;
> @@ -790,14 +808,16 @@ static void snap_unsink(jit_State *J, GCtrace *T, ExitState *ex,
>   	    p += (int64_t)ir_k64(iro)->u64;
>   	  else
>   	    p += iro->i;
> -	  lua_assert(p >= (uint8_t *)cdataptr(cd) &&
> -		     p + szs <= (uint8_t *)cdataptr(cd) + sz);
> +	  lj_assertJ(p >= (uint8_t *)cdataptr(cd) &&
> +		     p + szs <= (uint8_t *)cdataptr(cd) + sz,
> +		     "sunk store with offset out of range");
>   	  if (LJ_32 && irs+1 < T->ir + T->nins && (irs+1)->o == IR_HIOP) {
> -	    lua_assert(szs == 4);
> -	    snap_restoredata(T, ex, snapno, rfilt, (irs+1)->op2, LJ_LE?p+4:p,4);
> +	    lj_assertJ(szs == 4, "sunk store with bad size %d", szs);
> +	    snap_restoredata(J, T, ex, snapno, rfilt, (irs+1)->op2,
> +			     LJ_LE ? p+4 : p, 4);
>   	    if (LJ_BE) p += 4;
>   	  }
> -	  snap_restoredata(T, ex, snapno, rfilt, irs->op2, p, szs);
> +	  snap_restoredata(J, T, ex, snapno, rfilt, irs->op2, p, szs);
>   	}
>       }
>     } else
> @@ -812,10 +832,12 @@ static void snap_unsink(jit_State *J, GCtrace *T, ExitState *ex,
>         if (irs->r == RID_SINK && snap_sunk_store(T, ir, irs)) {
>   	IRIns *irk = &T->ir[irs->op1];
>   	TValue tmp, *val;
> -	lua_assert(irs->o == IR_ASTORE || irs->o == IR_HSTORE ||
> -		   irs->o == IR_FSTORE);
> +	lj_assertJ(irs->o == IR_ASTORE || irs->o == IR_HSTORE ||
> +		   irs->o == IR_FSTORE,
> +		   "sunk store with bad op %d", irs->o);
>   	if (irk->o == IR_FREF) {
> -	  lua_assert(irk->op2 == IRFL_TAB_META);
> +	  lj_assertJ(irk->op2 == IRFL_TAB_META,
> +		     "sunk store with bad field %d", irk->op2);
>   	  snap_restoreval(J, T, ex, snapno, rfilt, irs->op2, &tmp);
>   	  /* NOBARRIER: The table is new (marked white). */
>   	  setgcref(t->metatable, obj2gco(tabV(&tmp)));
> @@ -903,7 +925,7 @@ const BCIns *lj_snap_restore(jit_State *J, void *exptr)
>   #if LJ_FR2
>     L->base += (map[nent+LJ_BE] & 0xff);
>   #endif
> -  lua_assert(map + nent == flinks);
> +  lj_assertJ(map + nent == flinks, "inconsistent frames in snapshot");
>   
>     /* Compute current stack top. */
>     switch (bc_op(*pc)) {
> diff --git a/src/lj_snap.h b/src/lj_snap.h
> index 2c9ae3d6..4aec8509 100644
> --- a/src/lj_snap.h
> +++ b/src/lj_snap.h
> @@ -13,7 +13,8 @@
>   LJ_FUNC void lj_snap_add(jit_State *J);
>   LJ_FUNC void lj_snap_purge(jit_State *J);
>   LJ_FUNC void lj_snap_shrink(jit_State *J);
> -LJ_FUNC IRIns *lj_snap_regspmap(GCtrace *T, SnapNo snapno, IRIns *ir);
> +LJ_FUNC IRIns *lj_snap_regspmap(jit_State *J, GCtrace *T, SnapNo snapno,
> +				IRIns *ir);
>   LJ_FUNC void lj_snap_replay(jit_State *J, GCtrace *T);
>   LJ_FUNC const BCIns *lj_snap_restore(jit_State *J, void *exptr);
>   LJ_FUNC void lj_snap_grow_buf_(jit_State *J, MSize need);
> diff --git a/src/lj_state.c b/src/lj_state.c
> index 4add3d65..684336d5 100644
> --- a/src/lj_state.c
> +++ b/src/lj_state.c
> @@ -70,7 +70,8 @@ static void resizestack(lua_State *L, MSize n)
>     GCobj *up;
>     int32_t oldvmstate = G(L)->vmstate;
>   
> -  lua_assert((MSize)(tvref(L->maxstack)-oldst)==L->stacksize-LJ_STACK_EXTRA-1);
> +  lj_assertL((MSize)(tvref(L->maxstack)-oldst) == L->stacksize-LJ_STACK_EXTRA-1,
> +	     "inconsistent stack size");
>   
>     /*
>     ** Lua stack is inconsistent while reallocation, profilers
> @@ -182,8 +183,9 @@ static void close_state(lua_State *L)
>     global_State *g = G(L);
>     lj_func_closeuv(L, tvref(L->stack));
>     lj_gc_freeall(g);
> -  lua_assert(gcref(g->gc.root) == obj2gco(L));
> -  lua_assert(g->strnum == 0);
> +  lj_assertG(gcref(g->gc.root) == obj2gco(L),
> +	     "main thread is not first GC object");
> +  lj_assertG(g->strnum == 0, "leaked %d strings", g->strnum);
>     lj_trace_freestate(g);
>   #if LJ_HASFFI
>     lj_ctype_freestate(g);
> @@ -197,7 +199,9 @@ static void close_state(lua_State *L)
>       lj_mem_freevec(g, mref(g->gc.lightudseg, uint32_t), segnum, uint32_t);
>     }
>   #endif
> -  lua_assert(g->gc.total == sizeof(GG_State));
> +  lj_assertG(g->gc.total == sizeof(GG_State),
> +	     "memory leak of %lld bytes",
> +	     (long long)(g->gc.total - sizeof(GG_State)));
>   #ifndef LUAJIT_USE_SYSMALLOC
>     if (g->allocf == lj_alloc_f)
>       lj_alloc_destroy(g->allocd);
> @@ -315,17 +319,17 @@ lua_State *lj_state_new(lua_State *L)
>     setmrefr(L1->glref, L->glref);
>     setgcrefr(L1->env, L->env);
>     stack_init(L1, L);  /* init stack */
> -  lua_assert(iswhite(obj2gco(L1)));
> +  lj_assertL(iswhite(obj2gco(L1)), "new thread object is not white");
>     return L1;
>   }
>   
>   void LJ_FASTCALL lj_state_free(global_State *g, lua_State *L)
>   {
> -  lua_assert(L != mainthread(g));
> +  lj_assertG(L != mainthread(g), "free of main thread");
>     if (obj2gco(L) == gcref(g->cur_L))
>       setgcrefnull(g->cur_L);
>     lj_func_closeuv(L, tvref(L->stack));
> -  lua_assert(gcref(L->openupval) == NULL);
> +  lj_assertG(gcref(L->openupval) == NULL, "stale open upvalues");
>     lj_mem_freevec(g, tvref(L->stack), L->stacksize, TValue);
>     lj_mem_freet(g, L);
>   }
> diff --git a/src/lj_str.c b/src/lj_str.c
> index 8ff955ed..321e8c4f 100644
> --- a/src/lj_str.c
> +++ b/src/lj_str.c
> @@ -53,8 +53,9 @@ int32_t LJ_FASTCALL lj_str_cmp(GCstr *a, GCstr *b)
>   static LJ_AINLINE int str_fastcmp(const char *a, const char *b, MSize len)
>   {
>     MSize i = 0;
> -  lua_assert(len > 0);
> -  lua_assert((((uintptr_t)a+len-1) & (LJ_PAGESIZE-1)) <= LJ_PAGESIZE-4);
> +  lj_assertX(len > 0, "fast string compare with zero length");
> +  lj_assertX((((uintptr_t)a+len-1) & (LJ_PAGESIZE-1)) <= LJ_PAGESIZE-4,
> +	     "fast string compare crossing page boundary");
>     do {  /* Note: innocuous access up to end of string + 3. */
>       uint32_t v = lj_getu32(a+i) ^ *(const uint32_t *)(b+i);
>       if (v) {
> @@ -138,7 +139,7 @@ lj_fullhash(const uint8_t *v, MSize len)
>     MSize c = 0xcafedead;
>     MSize d = 0xdeadbeef;
>     MSize h = len;
> -  lua_assert(len >= 12);
> +  lj_assertX(len >= 12, "full hash calculation for too short (%d) string", len);
>     for(; len>8; len-=8, v+=8) {
>       a ^= lj_getu32(v);
>       b ^= lj_getu32(v+4);
> diff --git a/src/lj_strfmt.c b/src/lj_strfmt.c
> index 237cc575..ff5568c3 100644
> --- a/src/lj_strfmt.c
> +++ b/src/lj_strfmt.c
> @@ -320,7 +320,7 @@ SBuf *lj_strfmt_putfxint(SBuf *sb, SFormat sf, uint64_t k)
>     if ((sf & STRFMT_F_LEFT))
>       while (width-- > pprec) *p++ = ' ';
>   
> -  lua_assert(need == (MSize)(p - ps));
> +  lj_assertX(need == (MSize)(p - ps), "miscalculated format size");
>     setsbufP(sb, p);
>     return sb;
>   }
> @@ -449,7 +449,7 @@ const char *lj_strfmt_pushvf(lua_State *L, const char *fmt, va_list argp)
>       case STRFMT_ERR:
>       default:
>         lj_buf_putb(sb, '?');
> -      lua_assert(0);
> +      lj_assertL(0, "bad string format near offset %d", fs.len);
>         break;
>       }
>     }
> diff --git a/src/lj_strfmt.h b/src/lj_strfmt.h
> index 6e1d9017..0e1d8946 100644
> --- a/src/lj_strfmt.h
> +++ b/src/lj_strfmt.h
> @@ -79,7 +79,8 @@ static LJ_AINLINE void lj_strfmt_init(FormatState *fs, const char *p, MSize len)
>   {
>     fs->p = (const uint8_t *)p;
>     fs->e = (const uint8_t *)p + len;
> -  lua_assert(*fs->e == 0);  /* Must be NUL-terminated (may have NULs inside). */
> +  /* Must be NUL-terminated. May have NULs inside, too. */
> +  lj_assertX(*fs->e == 0, "format not NUL-terminated");
>   }
>   
>   /* Raw conversions. */
> diff --git a/src/lj_strfmt_num.c b/src/lj_strfmt_num.c
> index 9271f68a..c26204b7 100644
> --- a/src/lj_strfmt_num.c
> +++ b/src/lj_strfmt_num.c
> @@ -257,7 +257,7 @@ static int nd_similar(uint32_t* nd, uint32_t ndhi, uint32_t* ref, MSize hilen,
>     } else {
>       prec -= hilen - 9;
>     }
> -  lua_assert(prec < 9);
> +  lj_assertX(prec < 9, "bad precision %d", prec);
>     lj_strfmt_wuint9(nd9, nd[ndhi]);
>     lj_strfmt_wuint9(ref9, *ref);
>     return !memcmp(nd9, ref9, prec) && (nd9[prec] < '5') == (ref9[prec] < '5');
> @@ -414,14 +414,14 @@ static char *lj_strfmt_wfnum(SBuf *sb, SFormat sf, lua_Number n, char *p)
>   	** Rescaling was performed, but this introduced some error, and might
>   	** have pushed us across a rounding boundary. We check whether this
>   	** error affected the result by introducing even more error (2ulp in
> -	** either direction), and seeing whether a roundary boundary was
> +	** either direction), and seeing whether a rounding boundary was
>   	** crossed. Having already converted the -2ulp case, we save off its
>   	** most significant digits, convert the +2ulp case, and compare them.
>   	*/
>   	int32_t eidx = e + 70 + (ND_MUL2K_MAX_SHIFT < 29)
>   			 + (t.u32.lo >= 0xfffffffe && !(~t.u32.hi << 12));
>   	const int8_t *m_e = four_ulp_m_e + eidx * 2;
> -	lua_assert(0 <= eidx && eidx < 128);
> +	lj_assertG_(G(sbufL(sb)), 0 <= eidx && eidx < 128, "bad eidx %d", eidx);
>   	nd[33] = nd[ndhi];
>   	nd[32] = nd[(ndhi - 1) & 0x3f];
>   	nd[31] = nd[(ndhi - 2) & 0x3f];
> diff --git a/src/lj_strscan.c b/src/lj_strscan.c
> index 11d341ee..bb07b251 100644
> --- a/src/lj_strscan.c
> +++ b/src/lj_strscan.c
> @@ -93,7 +93,7 @@ static void strscan_double(uint64_t x, TValue *o, int32_t ex2, int32_t neg)
>     }
>   
>     /* Convert to double using a signed int64_t conversion, then rescale. */
> -  lua_assert((int64_t)x >= 0);
> +  lj_assertX((int64_t)x >= 0, "bad double conversion");
>     n = (double)(int64_t)x;
>     if (neg) n = -n;
>     if (ex2) n = ldexp(n, ex2);
> @@ -263,7 +263,7 @@ static StrScanFmt strscan_dec(const uint8_t *p, TValue *o,
>       uint32_t hi = 0, lo = (uint32_t)(xip-xi);
>       int32_t ex2 = 0, idig = (int32_t)lo + (ex10 >> 1);
>   
> -    lua_assert(lo > 0 && (ex10 & 1) == 0);
> +    lj_assertX(lo > 0 && (ex10 & 1) == 0, "bad lo %d ex10 %d", lo, ex10);
>   
>       /* Handle simple overflow/underflow. */
>       if (idig > 310/2) { if (neg) setminfV(o); else setpinfV(o); return fmt; }
> @@ -532,7 +532,7 @@ int LJ_FASTCALL lj_strscan_num(GCstr *str, TValue *o)
>   {
>     StrScanFmt fmt = lj_strscan_scan((const uint8_t *)strdata(str), str->len, o,
>   				   STRSCAN_OPT_TONUM);
> -  lua_assert(fmt == STRSCAN_ERROR || fmt == STRSCAN_NUM);
> +  lj_assertX(fmt == STRSCAN_ERROR || fmt == STRSCAN_NUM, "bad scan format");
>     return (fmt != STRSCAN_ERROR);
>   }
>   
> @@ -541,7 +541,8 @@ int LJ_FASTCALL lj_strscan_number(GCstr *str, TValue *o)
>   {
>     StrScanFmt fmt = lj_strscan_scan((const uint8_t *)strdata(str), str->len, o,
>   				   STRSCAN_OPT_TOINT);
> -  lua_assert(fmt == STRSCAN_ERROR || fmt == STRSCAN_NUM || fmt == STRSCAN_INT);
> +  lj_assertX(fmt == STRSCAN_ERROR || fmt == STRSCAN_NUM || fmt == STRSCAN_INT,
> +	     "bad scan format");
>     if (fmt == STRSCAN_INT) setitype(o, LJ_TISNUM);
>     return (fmt != STRSCAN_ERROR);
>   }
> diff --git a/src/lj_symtab.c b/src/lj_symtab.c
> index 54984c05..38b5e9e1 100644
> --- a/src/lj_symtab.c
> +++ b/src/lj_symtab.c
> @@ -36,8 +36,8 @@ void lj_symtab_dump_trace(struct lj_wbuf *out, const GCtrace *trace)
>     BCLine lineno = 0;
>   
>     const BCIns *startpc = mref(trace->startpc, const BCIns);
> -  lua_assert(startpc >= proto_bc(pt) &&
> -             startpc < proto_bc(pt) + pt->sizebc);
> +  lj_assertX(startpc >= proto_bc(pt) && startpc < proto_bc(pt) + pt->sizebc,
> +	     "start trace PC out of range");
>   
>     lineno = lj_debug_line(pt, proto_bcpos(pt, startpc));
>   
> @@ -354,8 +354,9 @@ static int resolve_symbolnames(struct dl_phdr_info *info, size_t info_size,
>     ** Assertion was taken from the GLIBC tests:
>     ** https://code.woboq.org/userspace/glibc/elf/tst-dlmodcount.c.html#37
>     */
> -  lua_assert(info_size > offsetof(struct dl_phdr_info, dlpi_subs)
> -      + sizeof(info->dlpi_subs));
> +  lj_assertL(info_size > offsetof(struct dl_phdr_info, dlpi_subs)
> +			 + sizeof(info->dlpi_subs),
> +	     "bad dlpi_subs");
>   
>     lib_cnt = info->dlpi_adds - *conf->lib_adds;
>   
> @@ -401,7 +402,7 @@ static int resolve_symbolnames(struct dl_phdr_info *info, size_t info_size,
>         ** sysprof, unless someone have deleted the LuaJIT binary
>         ** right after the start.
>         */
> -      lua_assert(0);
> +      lj_assertL(0, "bad executed binary symtab section");
>     }
>   
>     /*
> diff --git a/src/lj_sysprof.c b/src/lj_sysprof.c
> index 2e9ed9b3..52d4d2a5 100644
> --- a/src/lj_sysprof.c
> +++ b/src/lj_sysprof.c
> @@ -111,9 +111,9 @@ static void stream_epilogue(struct sysprof *sp)
>   
>   static void stream_lfunc(struct lj_wbuf *buf, const GCfunc *func)
>   {
> -  lua_assert(isluafunc(func));
> +  lj_assertX(isluafunc(func), "bad lua function in sysprof stream");
>     const GCproto *pt = funcproto(func);
> -  lua_assert(pt != NULL);
> +  lj_assertX(pt != NULL, "bad lua function prototype in sysprof stream");
>     lj_wbuf_addbyte(buf, LJP_FRAME_LFUNC);
>     lj_wbuf_addu64(buf, (uintptr_t)pt);
>     lj_wbuf_addu64(buf, (uint64_t)pt->firstline);
> @@ -121,14 +121,14 @@ static void stream_lfunc(struct lj_wbuf *buf, const GCfunc *func)
>   
>   static void stream_cfunc(struct lj_wbuf *buf, const GCfunc *func)
>   {
> -  lua_assert(iscfunc(func));
> +  lj_assertX(iscfunc(func), "bad C function in sysprof stream");
>     lj_wbuf_addbyte(buf, LJP_FRAME_CFUNC);
>     lj_wbuf_addu64(buf, (uintptr_t)func->c.f);
>   }
>   
>   static void stream_ffunc(struct lj_wbuf *buf, const GCfunc *func)
>   {
> -  lua_assert(isffunc(func));
> +  lj_assertX(isffunc(func), "bad fast function in sysprof stream");
>     lj_wbuf_addbyte(buf, LJP_FRAME_FFUNC);
>     lj_wbuf_addu64(buf, func->c.ffid);
>   }
> @@ -136,7 +136,7 @@ static void stream_ffunc(struct lj_wbuf *buf, const GCfunc *func)
>   static void stream_frame_lua(struct lj_wbuf *buf, const cTValue *frame)
>   {
>     const GCfunc *func = frame_func(frame);
> -  lua_assert(func != NULL);
> +  lj_assertX(func != NULL, "bad function in sysprof stream");
>     if (isluafunc(func))
>       stream_lfunc(buf, func);
>     else if (isffunc(func))
> @@ -145,7 +145,7 @@ static void stream_frame_lua(struct lj_wbuf *buf, const cTValue *frame)
>       stream_cfunc(buf, func);
>     else
>       /* Unreachable. */
> -    lua_assert(0);
> +    lj_assertX(0, "bad function type in sysprof stream");
>   }
>   
>   static void stream_backtrace_lua(struct sysprof *sp)
> @@ -155,9 +155,9 @@ static void stream_backtrace_lua(struct sysprof *sp)
>     cTValue *top_frame = NULL, *frame = NULL, *bot = NULL;
>     lua_State *L = NULL;
>   
> -  lua_assert(g != NULL);
> +  lj_assertX(g != NULL, "uninitialized global state in sysprof state");
>     L = gco2th(gcref(g->cur_L));
> -  lua_assert(L != NULL);
> +  lj_assertG(L != NULL, "uninitialized Lua state in sysprof state");
>   
>     top_frame = g->top_frame - 1; //(1 + LJ_FR2)
>   
> @@ -200,7 +200,7 @@ static void default_backtrace_host(void *(writer)(int frame_no, void *addr))
>     const int depth = backtrace(backtrace_buf, max_depth);
>     int level;
>   
> -  lua_assert(depth <= max_depth);
> +  lj_assertX(depth <= max_depth, "depth of C stack is too big");
>     for (level = SYSPROF_HANDLER_STACK_DEPTH; level < depth; ++level) {
>       if (!writer(level - SYSPROF_HANDLER_STACK_DEPTH + 1, backtrace_buf[level]))
>         return;
> @@ -209,7 +209,7 @@ static void default_backtrace_host(void *(writer)(int frame_no, void *addr))
>   
>   static void stream_backtrace_host(struct sysprof *sp)
>   {
> -  lua_assert(sp->backtracer != NULL);
> +  lj_assertX(sp->backtracer != NULL, "uninitialized sysprof backtracer");
>     sp->backtracer(stream_frame_host);
>     lj_wbuf_addu64(&sp->out, (uintptr_t)LJP_FRAME_HOST_LAST);
>   }
> @@ -268,9 +268,9 @@ static void stream_event(struct sysprof *sp, uint32_t vmstate)
>   {
>     event_streamer stream = NULL;
>   
> -  lua_assert(vmstfit4(vmstate));
> +  lj_assertX(vmstfit4(vmstate), "vmstate don't fit in 4 bits");
>     stream = event_streamers[vmstate];
> -  lua_assert(NULL != stream);
> +  lj_assertX(stream != NULL, "uninitialized sysprof stream");
>     stream(sp, vmstate);
>   }
>   
> @@ -282,7 +282,8 @@ static void sysprof_record_sample(struct sysprof *sp, siginfo_t *info)
>     uint32_t _vmstate = ~(uint32_t)(g->vmstate);
>     uint32_t vmstate = _vmstate < LJ_VMST_TRACE ? _vmstate : LJ_VMST_TRACE;
>   
> -  lua_assert(pthread_self() == sp->thread);
> +  lj_assertX(pthread_self() == sp->thread,
> +	     "bad thread during sysprof record sample");
>   
>     /* Caveat: order of counters must match vmstate order in <lj_obj.h>. */
>     ((uint64_t *)&sp->counters)[vmstate]++;
> @@ -317,7 +318,7 @@ static void sysprof_signal_handler(int sig, siginfo_t *info, void *ctx)
>         break;
>   
>       default:
> -      lua_assert(0);
> +      lj_assertX(0, "bad sysprof profiler state");
>         break;
>     }
>   }
> @@ -344,7 +345,7 @@ static int sysprof_validate(struct sysprof *sp,
>         return PROFILE_ERRRUN;
>   
>       default:
> -      lua_assert(0);
> +      lj_assertX(0, "bad sysprof profiler state");
>         break;
>     }
>   
> diff --git a/src/lj_tab.c b/src/lj_tab.c
> index c5f358e5..1d6a4b7f 100644
> --- a/src/lj_tab.c
> +++ b/src/lj_tab.c
> @@ -38,7 +38,7 @@ static LJ_AINLINE Node *hashmask(const GCtab *t, uint32_t hash)
>   /* Hash an arbitrary key and return its anchor position in the hash table. */
>   static Node *hashkey(const GCtab *t, cTValue *key)
>   {
> -  lua_assert(!tvisint(key));
> +  lj_assertX(!tvisint(key), "attempt to hash integer");
>     if (tvisstr(key))
>       return hashstr(t, strV(key));
>     else if (tvisnum(key))
> @@ -57,7 +57,7 @@ static LJ_AINLINE void newhpart(lua_State *L, GCtab *t, uint32_t hbits)
>   {
>     uint32_t hsize;
>     Node *node;
> -  lua_assert(hbits != 0);
> +  lj_assertL(hbits != 0, "zero hash size");
>     if (hbits > LJ_MAX_HBITS)
>       lj_err_msg(L, LJ_ERR_TABOV);
>     hsize = 1u << hbits;
> @@ -78,7 +78,7 @@ static LJ_AINLINE void clearhpart(GCtab *t)
>   {
>     uint32_t i, hmask = t->hmask;
>     Node *node = noderef(t->node);
> -  lua_assert(t->hmask != 0);
> +  lj_assertX(t->hmask != 0, "empty hash part");
>     for (i = 0; i <= hmask; i++) {
>       Node *n = &node[i];
>       setmref(n->next, NULL);
> @@ -103,7 +103,7 @@ static GCtab *newtab(lua_State *L, uint32_t asize, uint32_t hbits)
>     /* First try to colocate the array part. */
>     if (LJ_MAX_COLOSIZE != 0 && asize > 0 && asize <= LJ_MAX_COLOSIZE) {
>       Node *nilnode;
> -    lua_assert((sizeof(GCtab) & 7) == 0);
> +    lj_assertL((sizeof(GCtab) & 7) == 0, "bad GCtab size");
>       t = (GCtab *)lj_mem_newgco(L, sizetabcolo(asize));
>       t->gct = ~LJ_TTAB;
>       t->nomm = (uint8_t)~0;
> @@ -186,7 +186,8 @@ GCtab * LJ_FASTCALL lj_tab_dup(lua_State *L, const GCtab *kt)
>     GCtab *t;
>     uint32_t asize, hmask;
>     t = newtab(L, kt->asize, kt->hmask > 0 ? lj_fls(kt->hmask)+1 : 0);
> -  lua_assert(kt->asize == t->asize && kt->hmask == t->hmask);
> +  lj_assertL(kt->asize == t->asize && kt->hmask == t->hmask,
> +	     "mismatched size of table and template");
>     t->nomm = 0;  /* Keys with metamethod names may be present. */
>     asize = kt->asize;
>     if (asize > 0) {
> @@ -312,7 +313,7 @@ void lj_tab_resize(lua_State *L, GCtab *t, uint32_t asize, uint32_t hbits)
>   
>   static uint32_t countint(cTValue *key, uint32_t *bins)
>   {
> -  lua_assert(!tvisint(key));
> +  lj_assertX(!tvisint(key), "bad integer key");
>     if (tvisnum(key)) {
>       lua_Number nk = numV(key);
>       int32_t k = lj_num2int(nk);
> @@ -465,7 +466,8 @@ TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key)
>     if (!tvisnil(&n->val) || t->hmask == 0) {
>       Node *nodebase = noderef(t->node);
>       Node *collide, *freenode = getfreetop(t, nodebase);
> -    lua_assert(freenode >= nodebase && freenode <= nodebase+t->hmask+1);
> +    lj_assertL(freenode >= nodebase && freenode <= nodebase+t->hmask+1,
> +	       "bad freenode");
>       do {
>         if (freenode == nodebase) {  /* No free node found? */
>   	rehashtab(L, t, key);  /* Rehash table. */
> @@ -473,7 +475,7 @@ TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key)
>         }
>       } while (!tvisnil(&(--freenode)->key));
>       setfreetop(t, nodebase, freenode);
> -    lua_assert(freenode != &G(L)->nilnode);
> +    lj_assertL(freenode != &G(L)->nilnode, "store to fallback hash");
>       collide = hashkey(t, &n->key);
>       if (collide != n) {  /* Colliding node not the main node? */
>         Node *nn;
> @@ -555,7 +557,7 @@ TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key)
>     if (LJ_UNLIKELY(tvismzero(&n->key)))
>       n->key.u64 = 0;
>     lj_gc_anybarriert(L, t);
> -  lua_assert(tvisnil(&n->val));
> +  lj_assertL(tvisnil(&n->val), "new hash slot is not empty");
>     return &n->val;
>   }
>   
> diff --git a/src/lj_target.h b/src/lj_target.h
> index 8dcae957..b4be6781 100644
> --- a/src/lj_target.h
> +++ b/src/lj_target.h
> @@ -152,7 +152,8 @@ typedef uint32_t RegCost;
>   /* Return the address of an exit stub. */
>   static LJ_AINLINE char *exitstub_addr_(char **group, uint32_t exitno)
>   {
> -  lua_assert(group[exitno / EXITSTUBS_PER_GROUP] != NULL);
> +  lj_assertX(group[exitno / EXITSTUBS_PER_GROUP] != NULL,
> +	     "exit stub group for exit %d uninitialized", exitno);
>     return (char *)group[exitno / EXITSTUBS_PER_GROUP] +
>   	 EXITSTUB_SPACING*(exitno % EXITSTUBS_PER_GROUP);
>   }
> diff --git a/src/lj_trace.c b/src/lj_trace.c
> index 17743159..236e06a0 100644
> --- a/src/lj_trace.c
> +++ b/src/lj_trace.c
> @@ -110,7 +110,8 @@ static void perftools_addtrace(GCtrace *T)
>       name++;
>     else
>       name = "(string)";
> -  lua_assert(startpc >= proto_bc(pt) && startpc < proto_bc(pt) + pt->sizebc);
> +  lj_assertX(startpc >= proto_bc(pt) && startpc < proto_bc(pt) + pt->sizebc,
> +	     "trace PC out of range");
>     lineno = lj_debug_line(pt, proto_bcpos(pt, startpc));
>     if (!fp) {
>       char fname[40];
> @@ -200,7 +201,7 @@ void lj_trace_reenableproto(GCproto *pt)
>   {
>     if ((pt->flags & PROTO_ILOOP)) {
>       BCIns *bc = proto_bc(pt);
> -    BCPos i, sizebc = pt->sizebc;;
> +    BCPos i, sizebc = pt->sizebc;
>       pt->flags &= ~PROTO_ILOOP;
>       if (bc_op(bc[0]) == BC_IFUNCF)
>         setbc_op(&bc[0], BC_FUNCF);
> @@ -222,27 +223,28 @@ static void trace_unpatch(jit_State *J, GCtrace *T)
>       return;  /* No need to unpatch branches in parent traces (yet). */
>     switch (bc_op(*pc)) {
>     case BC_JFORL:
> -    lua_assert(traceref(J, bc_d(*pc)) == T);
> +    lj_assertJ(traceref(J, bc_d(*pc)) == T, "JFORL references other trace");
>       *pc = T->startins;
>       pc += bc_j(T->startins);
> -    lua_assert(bc_op(*pc) == BC_JFORI);
> +    lj_assertJ(bc_op(*pc) == BC_JFORI, "FORL does not point to JFORI");
>       setbc_op(pc, BC_FORI);
>       break;
>     case BC_JITERL:
>     case BC_JLOOP:
> -    lua_assert(op == BC_ITERL || op == BC_LOOP || bc_isret(op));
> +    lj_assertJ(op == BC_ITERL || op == BC_LOOP || bc_isret(op),
> +	       "bad original bytecode %d", op);
>       *pc = T->startins;
>       break;
>     case BC_JMP:
> -    lua_assert(op == BC_ITERL);
> +    lj_assertJ(op == BC_ITERL, "bad original bytecode %d", op);
>       pc += bc_j(*pc)+2;
>       if (bc_op(*pc) == BC_JITERL) {
> -      lua_assert(traceref(J, bc_d(*pc)) == T);
> +      lj_assertJ(traceref(J, bc_d(*pc)) == T, "JITERL references other trace");
>         *pc = T->startins;
>       }
>       break;
>     case BC_JFUNCF:
> -    lua_assert(op == BC_FUNCF);
> +    lj_assertJ(op == BC_FUNCF, "bad original bytecode %d", op);
>       *pc = T->startins;
>       break;
>     default:  /* Already unpatched. */
> @@ -254,7 +256,8 @@ static void trace_unpatch(jit_State *J, GCtrace *T)
>   static void trace_flushroot(jit_State *J, GCtrace *T)
>   {
>     GCproto *pt = &gcref(T->startpt)->pt;
> -  lua_assert(T->root == 0 && pt != NULL);
> +  lj_assertJ(T->root == 0, "not a root trace");
> +  lj_assertJ(pt != NULL, "trace has no prototype");
>     /* First unpatch any modified bytecode. */
>     trace_unpatch(J, T);
>     /* Unlink root trace from chain anchored in prototype. */
> @@ -370,7 +373,8 @@ void lj_trace_freestate(global_State *g)
>     {  /* This assumes all traces have already been freed. */
>       ptrdiff_t i;
>       for (i = 1; i < (ptrdiff_t)J->sizetrace; i++)
> -      lua_assert(i == (ptrdiff_t)J->cur.traceno || traceref(J, i) == NULL);
> +      lj_assertG(i == (ptrdiff_t)J->cur.traceno || traceref(J, i) == NULL,
> +		 "trace still allocated");
>     }
>   #endif
>     lj_mcode_free(J);
> @@ -425,8 +429,9 @@ static void trace_start(jit_State *J)
>     if ((J->pt->flags & PROTO_NOJIT)) {  /* JIT disabled for this proto? */
>       if (J->parent == 0 && J->exitno == 0) {
>         /* Lazy bytecode patching to disable hotcount events. */
> -      lua_assert(bc_op(*J->pc) == BC_FORL || bc_op(*J->pc) == BC_ITERL ||
> -		 bc_op(*J->pc) == BC_LOOP || bc_op(*J->pc) == BC_FUNCF);
> +      lj_assertJ(bc_op(*J->pc) == BC_FORL || bc_op(*J->pc) == BC_ITERL ||
> +		 bc_op(*J->pc) == BC_LOOP || bc_op(*J->pc) == BC_FUNCF,
> +		 "bad hot bytecode %d", bc_op(*J->pc));
>         setbc_op(J->pc, (int)bc_op(*J->pc)+(int)BC_ILOOP-(int)BC_LOOP);
>         J->pt->flags |= PROTO_ILOOP;
>       }
> @@ -437,7 +442,8 @@ static void trace_start(jit_State *J)
>     /* Get a new trace number. */
>     traceno = trace_findfree(J);
>     if (LJ_UNLIKELY(traceno == 0)) {  /* No free trace? */
> -    lua_assert((J2G(J)->hookmask & HOOK_GC) == 0);
> +    lj_assertJ((J2G(J)->hookmask & HOOK_GC) == 0,
> +	       "recorder called from GC hook");
>       lj_trace_flushall(J->L);
>       J->state = LJ_TRACE_IDLE;  /* Silently ignored. */
>       return;
> @@ -513,7 +519,7 @@ static void trace_stop(jit_State *J)
>       goto addroot;
>     case BC_JMP:
>       /* Patch exit branch in parent to side trace entry. */
> -    lua_assert(J->parent != 0 && J->cur.root != 0);
> +    lj_assertJ(J->parent != 0 && J->cur.root != 0, "not a side trace");
>       lj_asm_patchexit(J, traceref(J, J->parent), J->exitno, J->cur.mcode);
>       /* Avoid compiling a side trace twice (stack resizing uses parent exit). */
>       traceref(J, J->parent)->snap[J->exitno].count = SNAPCOUNT_DONE;
> @@ -532,7 +538,7 @@ static void trace_stop(jit_State *J)
>       traceref(J, J->exitno)->link = traceno;
>       break;
>     default:
> -    lua_assert(0);
> +    lj_assertJ(0, "bad stop bytecode %d", op);
>       break;
>     }
>   
> @@ -553,8 +559,8 @@ static void trace_stop(jit_State *J)
>   static int trace_downrec(jit_State *J)
>   {
>     /* Restart recording at the return instruction. */
> -  lua_assert(J->pt != NULL);
> -  lua_assert(bc_isret(bc_op(*J->pc)));
> +  lj_assertJ(J->pt != NULL, "no active prototype");
> +  lj_assertJ(bc_isret(bc_op(*J->pc)), "not at a return bytecode");
>     if (bc_op(*J->pc) == BC_RETM) {
>       J->ntraceabort++;
>       return 0;  /* NYI: down-recursion with RETM. */
> @@ -774,7 +780,7 @@ static void trace_hotside(jit_State *J, const BCIns *pc)
>         isluafunc(curr_func(J->L)) &&
>         snap->count != SNAPCOUNT_DONE &&
>         ++snap->count >= J->param[JIT_P_hotexit]) {
> -    lua_assert(J->state == LJ_TRACE_IDLE);
> +    lj_assertJ(J->state == LJ_TRACE_IDLE, "hot side exit while recording");
>       /* J->parent is non-zero for a side trace. */
>       J->state = LJ_TRACE_START;
>       lj_trace_ins(J, pc);
> @@ -848,7 +854,7 @@ static TraceNo trace_exit_find(jit_State *J, MCode *pc)
>       if (T && pc >= T->mcode && pc < (MCode *)((char *)T->mcode + T->szmcode))
>         return traceno;
>     }
> -  lua_assert(0);
> +  lj_assertJ(0, "bad exit pc");
>     return 0;
>   }
>   #endif
> @@ -878,13 +884,13 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
>     T = traceref(J, J->parent); UNUSED(T);
>   #ifdef EXITSTATE_CHECKEXIT
>     if (J->exitno == T->nsnap) {  /* Treat stack check like a parent exit. */
> -    lua_assert(T->root != 0);
> +    lj_assertJ(T->root != 0, "stack check in root trace");
>       J->exitno = T->ir[REF_BASE].op2;
>       J->parent = T->ir[REF_BASE].op1;
>       T = traceref(J, J->parent);
>     }
>   #endif
> -  lua_assert(T != NULL && J->exitno < T->nsnap);
> +  lj_assertJ(T != NULL && J->exitno < T->nsnap, "bad trace or exit number");
>     exd.J = J;
>     exd.exptr = exptr;
>     errcode = lj_vm_cpcall(L, NULL, &exd, trace_exit_cp);
> @@ -975,14 +981,7 @@ uintptr_t LJ_FASTCALL lj_trace_unwind(jit_State *J, uintptr_t addr, ExitNo *ep)
>       return (uintptr_t)exitstub_trace_addr(T, exitno);
>   #endif
>     }
> -  /* Cannot correlate addr with trace/exit. This will be fatal. */
> -  /*
> -  ** FIXME: The following assert was replaced with
> -  ** the conventional `lua_assert`.
> -  **
> -  ** lj_assertJ(0, "bad exit pc");
> -  */
> -  lua_assert(0);
> +  lj_assertJ(0, "bad exit pc");
>     return 0;
>   }
>   #endif
> diff --git a/src/lj_utils_leb128.c b/src/lj_utils_leb128.c
> index 0d50b839..d66961da 100644
> --- a/src/lj_utils_leb128.c
> +++ b/src/lj_utils_leb128.c
> @@ -9,6 +9,7 @@
>   #define LUA_CORE
>   
>   #include "lj_utils.h"
> +#include "lj_obj.h"
>   
>   #define LINK_BIT          (0x80)
>   #define MIN_TWOBYTE_VALUE (0x80)
> @@ -112,7 +113,7 @@ size_t LJ_FASTCALL lj_utils_write_leb128(uint8_t *buffer, int64_t value)
>     /* Omit LINK_BIT in case of overflow. */
>     buffer[i++] = (uint8_t)(value & PAYLOAD_MASK);
>   
> -  lua_assert(i <= LEB128_U64_MAXSIZE);
> +  lj_assertX(i <= LEB128_U64_MAXSIZE, "bad leb128 size");
>   
>     return i;
>   }
> @@ -126,7 +127,7 @@ size_t LJ_FASTCALL lj_utils_write_uleb128(uint8_t *buffer, uint64_t value)
>   
>     buffer[i++] = (uint8_t)value;
>   
> -  lua_assert(i <= LEB128_U64_MAXSIZE);
> +  lj_assertX(i <= LEB128_U64_MAXSIZE, "bad uleb128 size");
>   
>     return i;
>   }
> diff --git a/src/lj_vmmath.c b/src/lj_vmmath.c
> index 9c0d3fde..14e66687 100644
> --- a/src/lj_vmmath.c
> +++ b/src/lj_vmmath.c
> @@ -60,7 +60,8 @@ double lj_vm_foldarith(double x, double y, int op)
>   int32_t LJ_FASTCALL lj_vm_modi(int32_t a, int32_t b)
>   {
>     uint32_t y, ua, ub;
> -  lua_assert(b != 0);  /* This must be checked before using this function. */
> +  /* This must be checked before using this function. */
> +  lj_assertX(b != 0, "modulo with zero divisor");
>     ua = a < 0 ? (uint32_t)-a : (uint32_t)a;
>     ub = b < 0 ? (uint32_t)-b : (uint32_t)b;
>     y = ua % ub;
> @@ -84,7 +85,7 @@ double lj_vm_log2(double a)
>   static double lj_vm_powui(double x, uint32_t k)
>   {
>     double y;
> -  lua_assert(k != 0);
> +  lj_assertX(k != 0, "pow with zero exponent");
>     for (; (k & 1) == 0; k >>= 1) x *= x;
>     y = x;
>     if ((k >>= 1) != 0) {
> @@ -123,7 +124,7 @@ double lj_vm_foldfpm(double x, int fpm)
>     case IRFPM_SQRT: return sqrt(x);
>     case IRFPM_LOG: return log(x);
>     case IRFPM_LOG2: return lj_vm_log2(x);
> -  default: lua_assert(0);
> +  default: lj_assertX(0, "bad fpm %d", fpm);
>     }
>     return 0;
>   }
> diff --git a/src/lj_wbuf.c b/src/lj_wbuf.c
> index 897ef083..0001a02e 100644
> --- a/src/lj_wbuf.c
> +++ b/src/lj_wbuf.c
> @@ -10,6 +10,7 @@
>   
>   #include <errno.h>
>   
> +#include "lj_obj.h"
>   #include "lj_wbuf.h"
>   #include "lj_utils.h"
>   
> @@ -52,7 +53,7 @@ void LJ_FASTCALL lj_wbuf_terminate(struct lj_wbuf *buf)
>   
>   static LJ_AINLINE void wbuf_reserve(struct lj_wbuf *buf, size_t n)
>   {
> -  lua_assert(n <= buf->size);
> +  lj_assertX(n <= buf->size, "wbuf overflow");
>     if (LJ_UNLIKELY(wbuf_left(buf) < n))
>       lj_wbuf_flush(buf);
>   }
> diff --git a/src/ljamalg.c b/src/ljamalg.c
> index 6ad5289c..0ffc7e81 100644
> --- a/src/ljamalg.c
> +++ b/src/ljamalg.c
> @@ -28,6 +28,7 @@
>   #include "lua.h"
>   #include "lauxlib.h"
>   
> +#include "lj_assert.c"
>   #include "lj_gc.c"
>   #include "lj_err.c"
>   #include "lj_char.c"
> diff --git a/src/luaconf.h b/src/luaconf.h
> index 8029040a..38146008 100644
> --- a/src/luaconf.h
> +++ b/src/luaconf.h
> @@ -146,7 +146,7 @@
>   #define LUALIB_API	LUA_API
>   #define LUAMISC_API	LUA_API
>   
> -/* Support for internal assertions. */
> +/* Compatibility support for assertions. */
>   #if defined(LUA_USE_ASSERT) || defined(LUA_USE_APICHECK)
>   #include <assert.h>
>   #endif

  parent reply	other threads:[~2023-08-18 11:20 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-15  9:36 [Tarantool-patches] [PATCH luajit 0/5] Fix pow inconsistencies and improve asserts Sergey Kaplun via Tarantool-patches
2023-08-15  9:36 ` [Tarantool-patches] [PATCH luajit 1/5] test: introduce `samevalues()` TAP checker Sergey Kaplun via Tarantool-patches
2023-08-17 14:03   ` Maxim Kokryashkin via Tarantool-patches
2023-08-17 15:03     ` Sergey Kaplun via Tarantool-patches
2023-08-18 10:43   ` Sergey Bronnikov via Tarantool-patches
2023-08-18 10:58     ` Sergey Kaplun via Tarantool-patches
2023-08-18 11:12       ` Sergey Bronnikov via Tarantool-patches
2023-08-21 10:47         ` Igor Munkin via Tarantool-patches
2023-08-24  7:44           ` Sergey Bronnikov via Tarantool-patches
2023-08-15  9:36 ` [Tarantool-patches] [PATCH luajit 2/5] Remove pow() splitting and cleanup backends Sergey Kaplun via Tarantool-patches
2023-08-17 14:52   ` Maxim Kokryashkin via Tarantool-patches
2023-08-17 15:33     ` Sergey Kaplun via Tarantool-patches
2023-08-20  9:48       ` Maxim Kokryashkin via Tarantool-patches
2023-08-18 11:08   ` Sergey Bronnikov via Tarantool-patches
2023-08-15  9:36 ` [Tarantool-patches] [PATCH luajit 3/5] Improve assertions Sergey Kaplun via Tarantool-patches
2023-08-17 14:58   ` Maxim Kokryashkin via Tarantool-patches
2023-08-18  7:56     ` Sergey Kaplun via Tarantool-patches
2023-08-18 11:20   ` Sergey Bronnikov via Tarantool-patches [this message]
2023-08-15  9:36 ` [Tarantool-patches] [PATCH luajit 4/5] Fix pow() optimization inconsistencies Sergey Kaplun via Tarantool-patches
2023-08-18 12:45   ` Sergey Bronnikov via Tarantool-patches
2023-08-21  8:07     ` Sergey Kaplun via Tarantool-patches
2023-08-20  9:26   ` Maxim Kokryashkin via Tarantool-patches
2023-08-21  8:06     ` Sergey Kaplun via Tarantool-patches
2023-08-21  9:00       ` Maxim Kokryashkin via Tarantool-patches
2023-08-21  9:31         ` Sergey Kaplun via Tarantool-patches
2023-08-15  9:36 ` [Tarantool-patches] [PATCH luajit 5/5] Revert to trival pow() optimizations to prevent inaccuracies Sergey Kaplun via Tarantool-patches
2023-08-18 12:49   ` Sergey Bronnikov via Tarantool-patches
2023-08-21  8:16     ` Sergey Kaplun via Tarantool-patches
2023-08-20  9:37   ` Maxim Kokryashkin via Tarantool-patches
2023-08-21  8:15     ` Sergey Kaplun via Tarantool-patches
2023-08-21  9:06       ` Maxim Kokryashkin via Tarantool-patches
2023-08-21  9:36         ` Sergey Kaplun via Tarantool-patches
2023-08-24  7:47 ` [Tarantool-patches] [PATCH luajit 0/5] Fix pow inconsistencies and improve asserts Sergey Bronnikov via Tarantool-patches
2023-08-31 15:18 ` Igor Munkin via Tarantool-patches

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