[Tarantool-patches] [PATCH luajit 5/5] Revert to trival pow() optimizations to prevent inaccuracies.
Maxim Kokryashkin
m.kokryashkin at tarantool.org
Sun Aug 20 12:37:48 MSK 2023
Hi, Sergey!
Thanks for the patch!
Please consider my comments below.
On Tue, Aug 15, 2023 at 12:36:31PM +0300, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> (cherry-picked from commit 96d6d5032098ea9f0002165394a8774dcaa0c0ce)
>
> This patch fixes different misbehaviour between JIT-compiled code and
Typo: s/misbehaviour/misbehaviours/
> the interpreter for power operator with the following ways:
Typo: s/with/in/
> * Drop folding optimizations for base ^ n => base * base ..., as far as
> pow(base, n) isn't interchangeable with just multiplicity of numbers
> and depends on the <math.h> implementation.
> * Since the internal power function is inaccurate for very big or small
> powers, it is dropped, and `pow()` from the standard library is used
> instead. To save consistency between JIT behaviour and the VM
Typo: s/VM/VM,/
> narrowing optimization is dropped, and only trivial folding
> optimizations are used. Also, `math_extern2` version with two
> parameters is dropped, since it's no more used.
Typo: s/more/longer/
>
> Also, this fixes failures of the [220/502] lib/string/format/num.lua
> test [1] from LuaJIT-test suite.
Typo: s/from/from the/
>
> [1]: https://www.exploringbinary.com/incorrect-floating-point-to-decimal-conversions/
>
> Sergey Kaplun:
> * added the description and the test for the problem
>
> Part of tarantool/tarantool#8825
> ---
> src/lj_asm.c | 3 +-
> src/lj_dispatch.h | 2 +-
> src/lj_ffrecord.c | 4 +-
> src/lj_ircall.h | 3 +-
> src/lj_iropt.h | 1 -
> src/lj_opt_fold.c | 37 ++++------------
> src/lj_opt_narrow.c | 24 ----------
> src/lj_opt_split.c | 2 +-
> src/lj_record.c | 2 +-
> src/lj_vm.h | 3 --
> src/lj_vmmath.c | 44 +------------------
> src/vm_arm.dasc | 13 +++---
> src/vm_arm64.dasc | 11 ++---
> src/vm_mips.dasc | 11 ++---
> src/vm_mips64.dasc | 11 ++---
> src/vm_ppc.dasc | 11 ++---
> src/vm_x64.dasc | 9 ++--
> src/vm_x86.dasc | 11 ++---
> .../lj-684-pow-inconsistencies.test.lua | 21 ++++++++-
> 19 files changed, 64 insertions(+), 159 deletions(-)
>
> diff --git a/src/lj_asm.c b/src/lj_asm.c
> index 65261d50..3a1909d5 100644
> --- a/src/lj_asm.c
> +++ b/src/lj_asm.c
> @@ -1660,8 +1660,7 @@ static void asm_pow(ASMState *as, IRIns *ir)
> IRCALL_lj_carith_powu64);
> else
> #endif
> - asm_callid(as, ir, irt_isnum(IR(ir->op2)->t) ? IRCALL_lj_vm_pow :
> - IRCALL_lj_vm_powi);
> + asm_callid(as, ir, IRCALL_pow);
> }
>
> static void asm_div(ASMState *as, IRIns *ir)
> diff --git a/src/lj_dispatch.h b/src/lj_dispatch.h
> index af870a75..b8bc2594 100644
> --- a/src/lj_dispatch.h
> +++ b/src/lj_dispatch.h
> @@ -44,7 +44,7 @@ extern double __divdf3(double a, double b);
> #define GOTDEF(_) \
> _(floor) _(ceil) _(trunc) _(log) _(log10) _(exp) _(sin) _(cos) _(tan) \
> _(asin) _(acos) _(atan) _(sinh) _(cosh) _(tanh) _(frexp) _(modf) _(atan2) \
> - _(lj_vm_pow) _(fmod) _(ldexp) _(lj_vm_modi) \
> + _(pow) _(fmod) _(ldexp) _(lj_vm_modi) \
> _(lj_dispatch_call) _(lj_dispatch_ins) _(lj_dispatch_stitch) \
> _(lj_dispatch_profile) _(lj_err_throw) \
> _(lj_ffh_coroutine_wrap_err) _(lj_func_closeuv) _(lj_func_newL_gc) \
> diff --git a/src/lj_ffrecord.c b/src/lj_ffrecord.c
> index 0746ec64..99a6b918 100644
> --- a/src/lj_ffrecord.c
> +++ b/src/lj_ffrecord.c
> @@ -590,8 +590,8 @@ static void LJ_FASTCALL recff_math_call(jit_State *J, RecordFFData *rd)
>
> static void LJ_FASTCALL recff_math_pow(jit_State *J, RecordFFData *rd)
> {
> - J->base[0] = lj_opt_narrow_pow(J, J->base[0], J->base[1],
> - &rd->argv[0], &rd->argv[1]);
> + J->base[0] = lj_opt_narrow_arith(J, J->base[0], J->base[1],
> + &rd->argv[0], &rd->argv[1], IR_POW);
> UNUSED(rd);
> }
>
> diff --git a/src/lj_ircall.h b/src/lj_ircall.h
> index ac0888a0..9c195918 100644
> --- a/src/lj_ircall.h
> +++ b/src/lj_ircall.h
> @@ -194,8 +194,7 @@ typedef struct CCallInfo {
> _(FPMATH, sqrt, 1, N, NUM, XA_FP) \
> _(ANY, log, 1, N, NUM, XA_FP) \
> _(ANY, lj_vm_log2, 1, N, NUM, XA_FP) \
> - _(ANY, lj_vm_powi, 2, N, NUM, XA_FP) \
> - _(ANY, lj_vm_pow, 2, N, NUM, XA2_FP) \
> + _(ANY, pow, 2, N, NUM, XA2_FP) \
> _(ANY, atan2, 2, N, NUM, XA2_FP) \
> _(ANY, ldexp, 2, N, NUM, XA_FP) \
> _(SOFTFP, lj_vm_tobit, 1, N, INT, XA_FP32) \
> diff --git a/src/lj_iropt.h b/src/lj_iropt.h
> index a59ba3f4..7ee1ea86 100644
> --- a/src/lj_iropt.h
> +++ b/src/lj_iropt.h
> @@ -144,7 +144,6 @@ LJ_FUNC TRef lj_opt_narrow_arith(jit_State *J, TRef rb, TRef rc,
> TValue *vb, TValue *vc, IROp op);
> LJ_FUNC TRef lj_opt_narrow_unm(jit_State *J, TRef rc, TValue *vc);
> LJ_FUNC TRef lj_opt_narrow_mod(jit_State *J, TRef rb, TRef rc, TValue *vb, TValue *vc);
> -LJ_FUNC TRef lj_opt_narrow_pow(jit_State *J, TRef rb, TRef rc, TValue *vb, TValue *vc);
> LJ_FUNC IRType lj_opt_narrow_forl(jit_State *J, cTValue *forbase);
>
> /* Optimization passes. */
> diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c
> index 7d7cc9d1..09e6c87b 100644
> --- a/src/lj_opt_fold.c
> +++ b/src/lj_opt_fold.c
> @@ -236,14 +236,10 @@ LJFOLDF(kfold_fpcall2)
> return NEXTFOLD;
> }
>
> -LJFOLD(POW KNUM KINT)
> LJFOLD(POW KNUM KNUM)
> LJFOLDF(kfold_numpow)
> {
> - lua_Number a = knumleft;
> - lua_Number b = fright->o == IR_KINT ? (lua_Number)fright->i : knumright;
> - lua_Number y = lj_vm_foldarith(a, b, IR_POW - IR_ADD);
> - return lj_ir_knum(J, y);
> + return lj_ir_knum(J, lj_vm_foldarith(knumleft, knumright, IR_POW - IR_ADD));
> }
>
> /* Must not use kfold_kref for numbers (could be NaN). */
> @@ -1084,34 +1080,17 @@ LJFOLDF(simplify_nummuldiv_negneg)
> return RETRYFOLD;
> }
>
> -LJFOLD(POW any KINT)
> -LJFOLDF(simplify_numpow_xkint)
> +LJFOLD(POW any KNUM)
> +LJFOLDF(simplify_numpow_k)
> {
> - int32_t k = fright->i;
> - TRef ref = fins->op1;
> - if (k == 0) /* x ^ 0 ==> 1 */
> + if (knumright == 0) /* x ^ 0 ==> 1 */
> return lj_ir_knum_one(J); /* Result must be a number, not an int. */
> - if (k == 1) /* x ^ 1 ==> x */
> + else if (knumright == 1) /* x ^ 1 ==> x */
> return LEFTFOLD;
> - if ((uint32_t)(k+65536) > 2*65536u) /* Limit code explosion. */
> + else if (knumright == 2) /* x ^ 2 ==> x * x */
> + return emitir(IRTN(IR_MUL), fins->op1, fins->op1);
> + else
> return NEXTFOLD;
> - if (k < 0) { /* x ^ (-k) ==> (1/x) ^ k. */
> - ref = emitir(IRTN(IR_DIV), lj_ir_knum_one(J), ref);
> - k = -k;
> - }
> - /* Unroll x^k for 1 <= k <= 65536. */
> - for (; (k & 1) == 0; k >>= 1) /* Handle leading zeros. */
> - ref = emitir(IRTN(IR_MUL), ref, ref);
> - if ((k >>= 1) != 0) { /* Handle trailing bits. */
> - TRef tmp = emitir(IRTN(IR_MUL), ref, ref);
> - for (; k != 1; k >>= 1) {
> - if (k & 1)
> - ref = emitir(IRTN(IR_MUL), ref, tmp);
> - tmp = emitir(IRTN(IR_MUL), tmp, tmp);
> - }
> - ref = emitir(IRTN(IR_MUL), ref, tmp);
> - }
> - return ref;
> }
>
> /* -- Simplify conversions ------------------------------------------------ */
> diff --git a/src/lj_opt_narrow.c b/src/lj_opt_narrow.c
> index d6601f4c..db0da10f 100644
> --- a/src/lj_opt_narrow.c
> +++ b/src/lj_opt_narrow.c
> @@ -584,30 +584,6 @@ TRef lj_opt_narrow_mod(jit_State *J, TRef rb, TRef rc, TValue *vb, TValue *vc)
> return emitir(IRTN(IR_SUB), rb, tmp);
> }
>
> -/* Narrowing of power operator or math.pow. */
> -TRef lj_opt_narrow_pow(jit_State *J, TRef rb, TRef rc, TValue *vb, TValue *vc)
> -{
> - rb = conv_str_tonum(J, rb, vb);
> - rb = lj_ir_tonum(J, rb); /* Left arg is always treated as an FP number. */
> - rc = conv_str_tonum(J, rc, vc);
> - if (tvisint(vc) || numisint(numV(vc))) {
> - int32_t k = numberVint(vc);
> - if (!(k >= -65536 && k <= 65536)) goto force_pow_num;
> - if (!tref_isinteger(rc)) {
> - /* Guarded conversion to integer! */
> - rc = emitir(IRTGI(IR_CONV), rc, IRCONV_INT_NUM|IRCONV_CHECK);
> - }
> - if (!tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */
> - TRef tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536));
> - emitir(IRTGI(IR_ULE), tmp, lj_ir_kint(J, 2*65536));
> - }
> - } else {
> -force_pow_num:
> - rc = lj_ir_tonum(J, rc); /* Want POW(num, num), not POW(num, int). */
> - }
> - return emitir(IRTN(IR_POW), rb, rc);
> -}
> -
> /* -- Predictive narrowing of induction variables ------------------------- */
>
> /* Narrow a single runtime value. */
> diff --git a/src/lj_opt_split.c b/src/lj_opt_split.c
> index a619d852..0dc6394f 100644
> --- a/src/lj_opt_split.c
> +++ b/src/lj_opt_split.c
> @@ -400,7 +400,7 @@ static void split_ir(jit_State *J)
> hi = split_call_ll(J, hisubst, oir, ir, IRCALL_softfp_div);
> break;
> case IR_POW:
> - hi = split_call_li(J, hisubst, oir, ir, IRCALL_lj_vm_powi);
> + hi = split_call_li(J, hisubst, oir, ir, IRCALL_pow);
> break;
> case IR_FPMATH:
> hi = split_call_l(J, hisubst, oir, ir, IRCALL_lj_vm_floor + ir->op2);
> diff --git a/src/lj_record.c b/src/lj_record.c
> index d1332bfc..34d1210a 100644
> --- a/src/lj_record.c
> +++ b/src/lj_record.c
> @@ -2268,7 +2268,7 @@ void lj_record_ins(jit_State *J)
>
> case BC_POW:
> if (tref_isnumber_str(rb) && tref_isnumber_str(rc))
> - rc = lj_opt_narrow_pow(J, rb, rc, rbv, rcv);
> + rc = lj_opt_narrow_arith(J, rb, rc, rbv, rcv, IR_POW);
> else
> rc = rec_mm_arith(J, &ix, MM_pow);
> break;
> diff --git a/src/lj_vm.h b/src/lj_vm.h
> index f6f28a08..79166e5e 100644
> --- a/src/lj_vm.h
> +++ b/src/lj_vm.h
> @@ -96,9 +96,6 @@ LJ_ASMF int lj_vm_errno(void);
> #endif
> #endif
>
> -LJ_ASMF double lj_vm_powi(double, int32_t);
> -LJ_ASMF double lj_vm_pow(double, double);
> -
> /* Continuations for metamethods. */
> LJ_ASMF void lj_cont_cat(void); /* Continue with concatenation. */
> LJ_ASMF void lj_cont_ra(void); /* Store result in RA from instruction. */
> diff --git a/src/lj_vmmath.c b/src/lj_vmmath.c
> index 539f955b..506867f8 100644
> --- a/src/lj_vmmath.c
> +++ b/src/lj_vmmath.c
> @@ -30,52 +30,12 @@ LJ_FUNCA double lj_wrap_sinh(double x) { return sinh(x); }
> LJ_FUNCA double lj_wrap_cosh(double x) { return cosh(x); }
> LJ_FUNCA double lj_wrap_tanh(double x) { return tanh(x); }
> LJ_FUNCA double lj_wrap_atan2(double x, double y) { return atan2(x, y); }
> +LJ_FUNCA double lj_wrap_pow(double x, double y) { return pow(x, y); }
> LJ_FUNCA double lj_wrap_fmod(double x, double y) { return fmod(x, y); }
> #endif
>
> /* -- Helper functions ---------------------------------------------------- */
>
> -/* Unsigned x^k. */
> -static double lj_vm_powui(double x, uint32_t k)
> -{
> - double y;
> - lj_assertX(k != 0, "pow with zero exponent");
> - for (; (k & 1) == 0; k >>= 1) x *= x;
> - y = x;
> - if ((k >>= 1) != 0) {
> - for (;;) {
> - x *= x;
> - if (k == 1) break;
> - if (k & 1) y *= x;
> - k >>= 1;
> - }
> - y *= x;
> - }
> - return y;
> -}
> -
> -/* Signed x^k. */
> -double lj_vm_powi(double x, int32_t k)
> -{
> - if (k > 1)
> - return lj_vm_powui(x, (uint32_t)k);
> - else if (k == 1)
> - return x;
> - else if (k == 0)
> - return 1.0;
> - else
> - return 1.0 / lj_vm_powui(x, (uint32_t)-k);
> -}
> -
> -double lj_vm_pow(double x, double y)
> -{
> - int32_t k = lj_num2int(y);
> - if ((k >= -65536 && k <= 65536) && y == (double)k)
> - return lj_vm_powi(x, k);
> - else
> - return pow(x, y);
> -}
> -
> double lj_vm_foldarith(double x, double y, int op)
> {
> switch (op) {
> @@ -84,7 +44,7 @@ double lj_vm_foldarith(double x, double y, int op)
> case IR_MUL - IR_ADD: return x*y; break;
> case IR_DIV - IR_ADD: return x/y; break;
> case IR_MOD - IR_ADD: return x-lj_vm_floor(x/y)*y; break;
> - case IR_POW - IR_ADD: return lj_vm_pow(x, y); break;
> + case IR_POW - IR_ADD: return pow(x, y); break;
> case IR_NEG - IR_ADD: return -x; break;
> case IR_ABS - IR_ADD: return fabs(x); break;
> #if LJ_HASJIT
> diff --git a/src/vm_arm.dasc b/src/vm_arm.dasc
> index 792f0363..767d31f9 100644
> --- a/src/vm_arm.dasc
> +++ b/src/vm_arm.dasc
> @@ -1485,11 +1485,11 @@ static void build_subroutines(BuildCtx *ctx)
> |.endif
> |.endmacro
> |
> - |.macro math_extern2, name, func
> + |.macro math_extern2, func
> |.if HFABI
> - | .ffunc_dd math_ .. name
> + | .ffunc_dd math_ .. func
> |.else
> - | .ffunc_nn math_ .. name
> + | .ffunc_nn math_ .. func
> |.endif
> | .IOS mov RA, BASE
> | bl extern func
> @@ -1500,9 +1500,6 @@ static void build_subroutines(BuildCtx *ctx)
> | b ->fff_restv
> |.endif
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> |.if FPU
> | .ffunc_d math_sqrt
> @@ -1548,7 +1545,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -3156,7 +3153,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> break;
> case BC_POW:
> | // NYI: (partial) integer arithmetic.
> - | ins_arithfp extern, extern lj_vm_pow
> + | ins_arithfp extern, extern pow
> break;
>
> case BC_CAT:
> diff --git a/src/vm_arm64.dasc b/src/vm_arm64.dasc
> index fb267a76..de33bde4 100644
> --- a/src/vm_arm64.dasc
> +++ b/src/vm_arm64.dasc
> @@ -1391,14 +1391,11 @@ static void build_subroutines(BuildCtx *ctx)
> | b ->fff_resn
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nn math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nn math_ .. func
> | bl extern func
> | b ->fff_resn
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> |.ffunc_n math_sqrt
> | fsqrt d0, d0
> @@ -1427,7 +1424,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -2624,7 +2621,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> | ins_arithload FARG1, FARG2
> | ins_arithfallback ins_arithcheck_num
> |.if "fpins" == "fpow"
> - | bl extern lj_vm_pow
> + | bl extern pow
> |.else
> | fpins FARG1, FARG1, FARG2
> |.endif
> diff --git a/src/vm_mips.dasc b/src/vm_mips.dasc
> index 5664f503..32caabf7 100644
> --- a/src/vm_mips.dasc
> +++ b/src/vm_mips.dasc
> @@ -1631,17 +1631,14 @@ static void build_subroutines(BuildCtx *ctx)
> |. nop
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nn math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nn math_ .. func
> |. load_got func
> | call_extern
> |. nop
> | b ->fff_resn
> |. nop
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> |// TODO: Return integer type if result is integer (own sf implementation).
> |.macro math_round, func
> @@ -1695,7 +1692,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -3588,7 +3585,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> | sltiu AT, SFARG1HI, LJ_TISNUM
> | sltiu TMP0, SFARG2HI, LJ_TISNUM
> | and AT, AT, TMP0
> - | load_got lj_vm_pow
> + | load_got pow
> | beqz AT, ->vmeta_arith
> |. addu RA, BASE, RA
> |.if FPU
> diff --git a/src/vm_mips64.dasc b/src/vm_mips64.dasc
> index 249605d4..44fba36c 100644
> --- a/src/vm_mips64.dasc
> +++ b/src/vm_mips64.dasc
> @@ -1669,17 +1669,14 @@ static void build_subroutines(BuildCtx *ctx)
> |. nop
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nn math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nn math_ .. func
> |. load_got func
> | call_extern
> |. nop
> | b ->fff_resn
> |. nop
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> |// TODO: Return integer type if result is integer (own sf implementation).
> |.macro math_round, func
> @@ -1733,7 +1730,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -3826,7 +3823,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> | sltiu TMP0, TMP0, LJ_TISNUM
> | sltiu TMP1, TMP1, LJ_TISNUM
> | and AT, TMP0, TMP1
> - | load_got lj_vm_pow
> + | load_got pow
> | beqz AT, ->vmeta_arith
> |. daddu RA, BASE, RA
> |.if FPU
> diff --git a/src/vm_ppc.dasc b/src/vm_ppc.dasc
> index 94af63e6..980ad897 100644
> --- a/src/vm_ppc.dasc
> +++ b/src/vm_ppc.dasc
> @@ -2032,14 +2032,11 @@ static void build_subroutines(BuildCtx *ctx)
> | b ->fff_resn
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nn math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nn math_ .. func
> | blex func
> | b ->fff_resn
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> |.macro math_round, func
> | .ffunc_1 math_ .. func
> @@ -2164,7 +2161,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -4157,7 +4154,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> | checknum cr1, CARG3
> | crand 4*cr0+lt, 4*cr0+lt, 4*cr1+lt
> | bge ->vmeta_arith_vv
> - | blex lj_vm_pow
> + | blex pow
> | ins_next1
> |.if FPU
> | stfdx FARG1, BASE, RA
> diff --git a/src/vm_x64.dasc b/src/vm_x64.dasc
> index acbe8dc2..09bf67e5 100644
> --- a/src/vm_x64.dasc
> +++ b/src/vm_x64.dasc
> @@ -1825,16 +1825,13 @@ static void build_subroutines(BuildCtx *ctx)
> | jmp ->fff_resxmm0
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nn math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nn math_ .. func
> | mov RB, BASE
> | call extern func
> | mov BASE, RB
> | jmp ->fff_resxmm0
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> | math_extern log10
> | math_extern exp
> @@ -1847,7 +1844,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> diff --git a/src/vm_x86.dasc b/src/vm_x86.dasc
> index bf30cce6..f16ade1a 100644
> --- a/src/vm_x86.dasc
> +++ b/src/vm_x86.dasc
> @@ -2240,8 +2240,8 @@ static void build_subroutines(BuildCtx *ctx)
> | jmp ->fff_resfp
> |.endmacro
> |
> - |.macro math_extern2, name, func
> - | .ffunc_nnsse math_ .. name
> + |.macro math_extern2, func
> + | .ffunc_nnsse math_ .. func
> |.if not X64
> | movsd FPARG1, xmm0
> | movsd FPARG3, xmm1
> @@ -2251,9 +2251,6 @@ static void build_subroutines(BuildCtx *ctx)
> | mov BASE, RB
> | jmp ->fff_resfp
> |.endmacro
> - |.macro math_extern2, func
> - | math_extern2 func, func
> - |.endmacro
> |
> | math_extern log10
> | math_extern exp
> @@ -2266,7 +2263,7 @@ static void build_subroutines(BuildCtx *ctx)
> | math_extern sinh
> | math_extern cosh
> | math_extern tanh
> - | math_extern2 pow, lj_vm_pow
> + | math_extern2 pow
> | math_extern2 atan2
> | math_extern2 fmod
> |
> @@ -3944,7 +3941,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
> | movsd FPARG1, xmm0
> | movsd FPARG3, xmm1
> |.endif
> - | call extern lj_vm_pow
> + | call extern pow
> | movzx RA, PC_RA
> | mov BASE, RB
> |.if X64
> diff --git a/test/tarantool-tests/lj-684-pow-inconsistencies.test.lua b/test/tarantool-tests/lj-684-pow-inconsistencies.test.lua
> index 5129fc45..ab9db3df 100644
> --- a/test/tarantool-tests/lj-684-pow-inconsistencies.test.lua
> +++ b/test/tarantool-tests/lj-684-pow-inconsistencies.test.lua
> @@ -2,14 +2,15 @@ local tap = require('tap')
> -- Test to demonstrate the incorrect JIT behaviour for different
> -- power operation optimizations.
> -- See also:
> --- https://github.com/LuaJIT/LuaJIT/issues/684.
> +-- https://github.com/LuaJIT/LuaJIT/issues/684,
> +-- https://github.com/LuaJIT/LuaJIT/issues/817.
> local test = tap.test('lj-684-pow-inconsistencies'):skipcond({
> ['Test requires JIT enabled'] = not jit.status(),
> })
>
> local tostring = tostring
>
> -test:plan(4)
> +test:plan(5)
>
> jit.opt.start('hotloop=1')
>
> @@ -64,6 +65,22 @@ jit.flush()
>
> test:samevalues(res, ('consistent results for folding 2921 ^ 0.5'))
>
> +-- -948388 ^ 3 = -0x1.7ad0e8ad7439dp+59.
Same as in the previous patch, we need some additinal commentary for
those magic numbers.
> +res = {}
> +-- XXX: use local variable to prevent folding via parser.
> +-- XXX: use stack slot out of trace to prevent constant folding.
> +local corner_case_3 = -948388
Naming is misleading, it seems like it is the test case number,
which it is not. Please also fix this in the previous patch for `corner_case_5`.
> +jit.on()
> +for i = 1, 4 do
> + res[i] = corner_case_3 ^ 3
> +end
> +
> +-- XXX: Prevent hotcount side effects.
> +jit.off()
> +jit.flush()
If you'll succeed making that dedicated function for those test cases in the
previous patch fix ups, this one should be rewritten too.
> +
> +test:samevalues(res, ('consistent results for int pow (-948388) ^ 3'))
> +
> -- Narrowing for non-constant base of power operation.
> local function pow(base, power)
> return base ^ power
> --
> 2.41.0
>
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