Re: [Tarantool-patches] [PATCH luajit 3/4] dbg: introduce lj-gco command

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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Hi, Sergey,

thanks for the patch! LGTM

On 6/4/26 12:30, Sergey Kaplun wrote:
> Our GDB extension already has dumpers for TValues. But sometimes it
> may be useful to dump GC objects (GCobj) without stack context. This
> patch adds additional wrappers around dumpers for GC objects to get the
> corresponding GC object from a TValue. Also, the lj-gco command is
> introduced. It allows dumping GC objects without stack context. The
> output format is the same as for the lj-tv command.
>
> Part of tarantool/tarantool#4808
> ---
>   src/luajit_dbg.py                             | 182 ++++++++++++------
>   .../debug-extension-tests.py                  |  83 ++++++--
>   2 files changed, 190 insertions(+), 75 deletions(-)
>
> diff --git a/src/luajit_dbg.py b/src/luajit_dbg.py
> index 300d65e9..f5868e61 100644
> --- a/src/luajit_dbg.py
> +++ b/src/luajit_dbg.py
> @@ -882,44 +882,29 @@ def lightudV(tv):
>   
>   # Dumpers.
>   
> +# GCobj dumpers.
>   
> -def dump_lj_tnil(tv):
> -    return 'nil'
> -
> -
> -def dump_lj_tfalse(tv):
> -    return 'false'
> -
> -
> -def dump_lj_ttrue(tv):
> -    return 'true'
> -
> -
> -def dump_lj_tlightud(tv):
> -    return 'light userdata @ {}'.format(strx64(lightudV(tv)))
> -
> -
> -def dump_lj_tstr(tv):
> +def dump_lj_gco_str(gcobj):
>       return 'string {body} @ {address}'.format(
> -        body=strdata(gcval(tv['gcr'])),
> -        address=strx64(gcval(tv['gcr']))
> +        body=strdata(gcobj),
> +        address=strx64(gcobj)
>       )
>   
>   
> -def dump_lj_tupval(tv):
> -    return 'upvalue @ {}'.format(strx64(gcval(tv['gcr'])))
> +def dump_lj_gco_upval(gcobj):
> +    return 'upvalue @ {}'.format(strx64(gcobj))
>   
>   
> -def dump_lj_tthread(tv):
> -    return 'thread @ {}'.format(strx64(gcval(tv['gcr'])))
> +def dump_lj_gco_thread(gcobj):
> +    return 'thread @ {}'.format(strx64(gcobj))
>   
>   
> -def dump_lj_tproto(tv):
> -    return 'proto @ {}'.format(strx64(gcval(tv['gcr'])))
> +def dump_lj_gco_proto(gcobj):
> +    return 'proto @ {}'.format(strx64(gcobj))
>   
>   
> -def dump_lj_tfunc(tv):
> -    func = dbg.cast('struct GCfuncC *', gcval(tv['gcr']))
> +def dump_lj_gco_func(gcobj):
> +    func = dbg.cast('struct GCfuncC *', gcobj)
>       ffid = func['ffid']
>   
>       if ffid == 0:
> @@ -936,20 +921,20 @@ def dump_lj_tfunc(tv):
>           return 'fast function #{}'.format(int(ffid))
>   
>   
> -def dump_lj_ttrace(tv):
> -    trace = dbg.cast('struct GCtrace *', gcval(tv['gcr']))
> +def dump_lj_gco_trace(gcobj):
> +    trace = dbg.cast('struct GCtrace *', gcobj)
>       return 'trace {traceno} @ {addr}'.format(
>           traceno=strx64(trace['traceno']),
>           addr=strx64(trace)
>       )
>   
>   
> -def dump_lj_tcdata(tv):
> -    return 'cdata @ {}'.format(strx64(gcval(tv['gcr'])))
> +def dump_lj_gco_cdata(gcobj):
> +    return 'cdata @ {}'.format(strx64(gcobj))
>   
>   
> -def dump_lj_ttab(tv):
> -    table = dbg.cast('GCtab *', gcval(tv['gcr']))
> +def dump_lj_gco_tab(gcobj):
> +    table = dbg.cast('GCtab *', gcobj)
>       return 'table @ {gcr} (asize: {asize}, hmask: {hmask})'.format(
>           gcr=strx64(table),
>           asize=table['asize'],
> @@ -957,41 +942,94 @@ def dump_lj_ttab(tv):
>       )
>   
>   
> -def dump_lj_tudata(tv):
> -    return 'userdata @ {}'.format(strx64(gcval(tv['gcr'])))
> +def dump_lj_gco_udata(gcobj):
> +    return 'userdata @ {}'.format(strx64(gcobj))
> +
> +
> +def dump_lj_gco_invalid(gcobj):
> +    return 'not valid type @ {}'.format(strx64(gcobj))
> +
> +
> +# TValue dumpers
> +
> +def dump_lj_tv_nil(tv):
> +    return 'nil'
> +
> +
> +def dump_lj_tv_false(tv):
> +    return 'false'
> +
> +
> +def dump_lj_tv_true(tv):
> +    return 'true'
> +
> +
> +def dump_lj_tv_lightud(tv):
> +    return 'light userdata @ {}'.format(strx64(lightudV(tv)))
> +
> +
> +# Generate wrappers for TValues containing GCobj.
> +gco_fn_dumpers = [
> +    fn for fn in globals().keys() if fn.startswith('dump_lj_gco')
> +]
> +for fn_name in gco_fn_dumpers:
> +    wrapped_fn_name = fn_name.replace('gco', 'tv')
> +    # Lambda takes `fn_name` as a reference, so the additional
> +    # lambda is needed to fixate the correct wrapper.
> +    globals()[wrapped_fn_name] = (lambda f: (
> +        lambda tv: globals()[f](gcval(tv['gcr']))
> +    ))(fn_name)
>   
>   
> -def dump_lj_tnumx(tv):
> +def dump_lj_tv_numx(tv):
>       if tvisint(tv):
>           return 'integer {}'.format(dbg.cast('int32_t', tv['i']))
>       else:
>           return 'number {}'.format(dbg.cast('double', tv['n']))
>   
>   
> -def dump_lj_invalid(tv):
> -    return 'not valid type @ {}'.format(strx64(gcval(tv['gcr'])))
> -
> -
> -dumpers = {
> -    'LJ_TNIL':     dump_lj_tnil,
> -    'LJ_TFALSE':   dump_lj_tfalse,
> -    'LJ_TTRUE':    dump_lj_ttrue,
> -    'LJ_TLIGHTUD': dump_lj_tlightud,
> -    'LJ_TSTR':     dump_lj_tstr,
> -    'LJ_TUPVAL':   dump_lj_tupval,
> -    'LJ_TTHREAD':  dump_lj_tthread,
> -    'LJ_TPROTO':   dump_lj_tproto,
> -    'LJ_TFUNC':    dump_lj_tfunc,
> -    'LJ_TTRACE':   dump_lj_ttrace,
> -    'LJ_TCDATA':   dump_lj_tcdata,
> -    'LJ_TTAB':     dump_lj_ttab,
> -    'LJ_TUDATA':   dump_lj_tudata,
> -    'LJ_TNUMX':    dump_lj_tnumx,
> +gco_dumpers = {
> +    'LJ_TSTR':     dump_lj_gco_str,
> +    'LJ_TUPVAL':   dump_lj_gco_upval,
> +    'LJ_TTHREAD':  dump_lj_gco_thread,
> +    'LJ_TPROTO':   dump_lj_gco_proto,
> +    'LJ_TFUNC':    dump_lj_gco_func,
> +    'LJ_TTRACE':   dump_lj_gco_trace,
> +    'LJ_TCDATA':   dump_lj_gco_cdata,
> +    'LJ_TTAB':     dump_lj_gco_tab,
> +    'LJ_TUDATA':   dump_lj_gco_udata,
>   }
>   
>   
> +tv_dumpers = {
> +    'LJ_TNIL':     dump_lj_tv_nil,
> +    'LJ_TFALSE':   dump_lj_tv_false,
> +    'LJ_TTRUE':    dump_lj_tv_true,
> +    'LJ_TLIGHTUD': dump_lj_tv_lightud,
> +    'LJ_TSTR':     dump_lj_tv_str,  # noqa: F821 # Generated.
> +    'LJ_TUPVAL':   dump_lj_tv_upval,  # noqa: F821 # Generated.
> +    'LJ_TTHREAD':  dump_lj_tv_thread,  # noqa: F821 # Generated.
> +    'LJ_TPROTO':   dump_lj_tv_proto,  # noqa: F821 # Generated.
> +    'LJ_TFUNC':    dump_lj_tv_func,  # noqa: F821 # Generated.
> +    'LJ_TTRACE':   dump_lj_tv_trace,  # noqa: F821 # Generated.
> +    'LJ_TCDATA':   dump_lj_tv_cdata,  # noqa: F821 # Generated.
> +    'LJ_TTAB':     dump_lj_tv_tab,  # noqa: F821 # Generated.
> +    'LJ_TUDATA':   dump_lj_tv_udata,  # noqa: F821 # Generated.
> +    'LJ_TNUMX':    dump_lj_tv_numx,
> +}
> +
> +
> +def dump_gcobj(gcobj):
> +    return gco_dumpers.get(
> +        typenames(i2notu32(gcobj['gch']['gct'])), dump_lj_gco_invalid
> +    )(gcobj)
> +
> +
>   def dump_tvalue(tvalue):
> -    return dumpers.get(typenames(itypemap(tvalue)), dump_lj_invalid)(tvalue)
> +    return tv_dumpers.get(
> +        typenames(itypemap(tvalue)),
> +        dump_lj_tv_invalid  # noqa: F821 # Generated.
> +    )(tvalue)
>   
>   
>   def dump_framelink_slot_address(fr):
> @@ -1011,7 +1049,7 @@ def dump_framelink(L, fr):
>               p='P' if frame_typep(fr) & FRAME_P else ''
>           ),
>           d=dbg.cast('TValue *', fr) - dbg.cast('TValue *', frame_prev(fr)),
> -        f=dump_lj_tfunc(fr - LJ_FR2),
> +        f=dump_lj_tv_func(fr - LJ_FR2),  # noqa: F821 # Generated.
>       )
>   
>   
> @@ -1141,6 +1179,35 @@ The command requires no args and dumps current GC stats:
>           ))
>   
>   
> +class LJDumpGCobj(dbg.LJBase):
> +    '''
> +lj-gco <GCobj *>
> +
> +The command receives a pointer to <GCobj> (GCobj address) and dumps
> +the type and some info related to it.
> +
> +* LJ_TSTR: string <string payload> @ <gcr>
> +* LJ_TUPVAL: upvalue @ <gcr>
> +* LJ_TTHREAD: thread @ <gcr>
> +* LJ_TPROTO: proto @ <gcr>
> +* LJ_TFUNC: <LFUNC|CFUNC|FFUNC>
> +  <LFUNC>: Lua function @ <gcr>, <nupvals> upvalues,<chunk:line>
> +  <CFUNC>: C function <mcode address>
> +  <FFUNC>: fast function #<ffid>
> +* LJ_TTRACE: trace <traceno> @ <gcr>
> +* LJ_TCDATA: cdata @ <gcr>
> +* LJ_TTAB: table @ <gcr> (asize: <asize>, hmask: <hmask>)
> +* LJ_TUDATA: userdata @ <gcr>
> +
> +Whether the type of the given address differs from the listed above, then
> +error message occurs.
> +    '''
> +
> +    def execute(self, arg):
> +        gcobj = dbg.cast('GCobj *', dbg.eval(arg))
> +        dbg.write('{}\n'.format(dump_gcobj(gcobj)))
> +
> +
>   class LJDumpStack(dbg.LJBase):
>       '''
>   lj-stack [<lua_State *>]
> @@ -1302,6 +1369,7 @@ def load(event=None):
>       dbg.initialize_extension({
>           'lj-arch':  LJDumpArch,
>           'lj-gc':    LJGC,
> +        'lj-gco':   LJDumpGCobj,
>           'lj-stack': LJDumpStack,
>           'lj-state': LJState,
>           'lj-str':   LJDumpString,
> diff --git a/test/tarantool-debugger-tests/debug-extension-tests.py b/test/tarantool-debugger-tests/debug-extension-tests.py
> index 06a118ff..7e2b5ac4 100644
> --- a/test/tarantool-debugger-tests/debug-extension-tests.py
> +++ b/test/tarantool-debugger-tests/debug-extension-tests.py
> @@ -138,6 +138,17 @@ class TestCaseBase(unittest.TestCase):
>               self.assertRegex(self.output, self.pattern.strip())
>   
>   
> +# LLDB + Clang on macOS can't produce debug info for the C-defined
> +# macros. Thus, we hardcoded its value manually.
> +def gcval(arg):
> +    if sys.platform == 'darwin':
> +        # Assume GC64 build only.
> +        LJ_GCVMASK = '(((uint64_t)1 << 47) - 1)'
> +        return '(((' + arg + ')->gcr).gcptr64 & ' + LJ_GCVMASK + ')'
> +    else:
> +        return 'gcval(' + arg + ')'
> +
> +
>   class TestLoad(TestCaseBase):
>       extension_cmds = ''
>       location = 'lj_cf_print'
> @@ -145,6 +156,7 @@ class TestLoad(TestCaseBase):
>       pattern = (
>           r'lj-arch command initialized\n'
>           r'lj-gc command initialized\n'
> +        r'lj-gco command initialized\n'
>           r'lj-stack command initialized\n'
>           r'lj-state command initialized\n'
>           r'lj-str command initialized\n'
> @@ -223,6 +235,31 @@ class TestLJStackFunc(TestCaseBase):
>       pattern = STACK_RX
>   
>   
> +# Sorted in LJT order.
> +GCO_ARGS = (
> +    '"hello",\n'
> +    'coroutine.create(function() end),\n'
> +    'function() end,\n'
> +    'require,\n'
> +    'print,\n'
> +    'ffi.new("int*"),\n'
> +    '{1},\n'
> +    'newproxy(),\n'
> +)
> +
> +
> +GCO_RX = (
> +    r'string \"hello\" @ ' + RX_ADDR + r'\n'
> +    r'thread @ ' + RX_ADDR + r'\n'
> +    r'Lua function @ ' + RX_ADDR + r', [0-9]+ upvalues, .+:[0-9]+\n'
> +    r'C function @ ' + RX_ADDR + r'\n'
> +    r'fast function #[0-9]+\n'
> +    r'cdata @ ' + RX_ADDR + r'\n'
> +    r'table @ ' + RX_ADDR + r' \(asize: \d+, hmask: ' + RX_HASH + r'\)\n'
> +    r'userdata @ ' + RX_ADDR + r'\n'
> +)
> +
> +
>   class TestLJTV(TestCaseBase):
>       location = 'lj_cf_print'
>       extension_cmds = (
> @@ -249,15 +286,8 @@ class TestLJTV(TestCaseBase):
>           '  nil,\n'
>           '  false,\n'
>           '  true,\n'
> -        '  debug.upvalueid(print, 1), \n'  # lightuserdata
> -        '  "hello",\n'
> -        '  coroutine.create(function() end),\n'
> -        '  function() end,\n'
> -        '  require,\n'
> -        '  print,\n'
> -        '  ffi.new("int*"),\n'
> -        '  {1},\n'
> -        '  newproxy(),\n'
> +        '  debug.upvalueid(print, 1), \n' +  # lightuserdata
> +        GCO_ARGS +
>           '  1,\n'
>           '  1.1\n'
>           ')\n'
> @@ -267,15 +297,8 @@ class TestLJTV(TestCaseBase):
>           r'nil\n'
>           r'false\n'
>           r'true\n'
> -        r'light userdata @ ' + RX_ADDR + r'\n'
> -        r'string \"hello\" @ ' + RX_ADDR + r'\n'
> -        r'thread @ ' + RX_ADDR + r'\n'
> -        r'Lua function @ ' + RX_ADDR + r', [0-9]+ upvalues, .+:[0-9]+\n'
> -        r'C function @ ' + RX_ADDR + r'\n'
> -        r'fast function #[0-9]+\n'
> -        r'cdata @ ' + RX_ADDR + r'\n'
> -        r'table @ ' + RX_ADDR + r' \(asize: \d+, hmask: ' + RX_HASH + r'\)\n'
> -        r'userdata @ ' + RX_ADDR + r'\n'
> +        r'light userdata @ ' + RX_ADDR + r'\n' +
> +        GCO_RX +
>           RX_INT + r' .*1.*\n'
>           r'number 1.1\d+\n'
>       )
> @@ -312,6 +335,30 @@ class TestLJTab(TestCaseBase):
>       )
>   
>   
> +class TestLJGCo(TestCaseBase):
> +    location = 'lj_cf_print'
> +    extension_cmds = (
> +        'lj-gco ' + gcval('L->base + 0') + '\n'
> +        'lj-gco ' + gcval('L->base + 1') + '\n'
> +        'lj-gco ' + gcval('L->base + 2') + '\n'
> +        'lj-gco ' + gcval('L->base + 3') + '\n'
> +        'lj-gco ' + gcval('L->base + 4') + '\n'
> +        'lj-gco ' + gcval('L->base + 5') + '\n'
> +        'lj-gco ' + gcval('L->base + 6') + '\n'
> +        'lj-gco ' + gcval('L->base + 7') + '\n'
> +    )
> +
> +    lua_script = (
> +        'local ffi = require("ffi")\n'
> +        'print(\n' +
> +        GCO_ARGS +
> +        '  1\n'  # Stub for the pattern.
> +        ')\n'
> +    )
> +
> +    pattern = GCO_RX
> +
> +
>   for test_cls in TestCaseBase.__subclasses__():
>       test_cls.test = lambda self: self.check()
>   

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