Re: [Tarantool-patches] [PATCH luajit v3] dbg: display fast function name along with ffid

[Mikhail Elhimov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Sergey!

Thanks for the review! Updated according to your comments.

On 28.09.2026 16:02, Sergey Bronnikov wrote:
> Hi, Mikhail,
>
> thanks for the patch! LGTM with minor comments below.
>
> Sergey
>
> On 9/24/26 23:14, Mikhail Elhimov wrote:
>> Part of tarantool/tarantool#4808
>> ---
>> Changes in v3:
>>    - Fixed fast function regexp in tests
>>
>> Changes in v2:
>>    - Format is changed to 'ffname (#ffid)'
>>    - Replaced single '_' with '.' in ffname
>>    - Adjusted tests to check mapping
>>
>> This patch is to be applied after 
>> https://lists.tarantool.org/pipermail/tarantool-patches/2026-September/030791.html.
>>
>> Branch: 
>> https://github.com/tarantool/luajit/tree/elhimov/gh-4808-display-fast-function-name
>> Related issue: https://github.com/tarantool/tarantool/issues/4808
>>
>>   src/luajit_dbg.py                             | 19 +++++++++++++------
>>   .../debug-extension-tests.py                  |  6 ++++--
>>   2 files changed, 17 insertions(+), 8 deletions(-)
>>
>> diff --git a/src/luajit_dbg.py b/src/luajit_dbg.py
>> index 5cd23a88..a564801b 100644
>> --- a/src/luajit_dbg.py
>> +++ b/src/luajit_dbg.py
>> @@ -1121,6 +1121,11 @@ def frames(L):
>>   # LuaJIT macro implementations and structure access.
>>     +# Get FastFunc enum members and replace any single '_' with '.'.
>> +FF_NAMES = EnumBasedList('FastFunc', 'FF__MAX', lambda x:
>> +                         re.sub('(?<!_)_(?!_)', '.', cut_prefix(x, 
>> 'FF_')))
>> +
>> +
>>   def mref(typename, obj):
>>       return dbg.cast(typename, obj['ptr64'] if LJ_GC64 else 
>> obj['ptr32'])
>>   @@ -1716,7 +1721,7 @@ def dump_lj_gco_proto(gcobj):
>>     def dump_lj_gco_func(gcobj):
>>       func = dbg.cast('struct GCfuncC *', gcobj)
>> -    ffid = func['ffid']
>> +    ffid = int(func['ffid'])
>>         if ffid == 0:
>>           pt = funcproto(func)
>> @@ -1729,7 +1734,8 @@ def dump_lj_gco_func(gcobj):
>>       elif ffid == 1:
>>           return 'C function @ {}'.format(strx64(func['f']))
>>       else:
>> -        return 'fast function #{}'.format(int(ffid))
>> +        ffname = FF_NAMES[ffid] if ffid < len(FF_NAMES) else "unknown"
> use single quotes
Done
>> +        return 'fast function {} (#{})'.format(ffname, ffid)
>>       def dump_lj_gco_trace(gcobj):
>> @@ -2079,7 +2085,7 @@ def dump_proto(proto):
>>       def dump_func(func):
>> -    ffid = func['ffid']
>> +    ffid = int(func['ffid'])
>>         if ffid == 0:
>>           pt = funcproto(func)
>> @@ -2087,7 +2093,8 @@ def dump_func(func):
>>       elif ffid == 1:
>>           return 'C function @ {}\n'.format(strx64(func['f']))
>>       else:
>> -        return 'fast function #{}\n'.format(int(ffid))
>> +        ffname = FF_NAMES[ffid] if ffid < len(FF_NAMES) else "unknown"
> the same is used in dump_lj_gco_func(), I would create a helper for this
Done
>> +        return 'fast function {} (#{})\n'.format(ffname, ffid)
>>       # FFI dumpers.
>> @@ -2713,7 +2720,7 @@ the type and some info related to it.
>>   * LJ_TFUNC: <LFUNC|CFUNC|FFUNC>
>>     <LFUNC>: Lua function @ <gcr>, <nupvals> upvalues, <chunk:line>
>>     <CFUNC>: C function <mcode address>
>> -  <FFUNC>: fast function #<ffid>
>> +  <FFUNC>: fast function <ffname> (#<ffid>)
>>   * LJ_TTRACE: trace <traceno> @ <gcr>
>>   * LJ_TCDATA: cdata @ <gcr>
>>   * LJ_TTAB: table @ <gcr> (asize: <asize>, hmask: <hmask>)
>> @@ -2932,7 +2939,7 @@ the type and some info related to it.
>>   * LJ_TFUNC: <LFUNC|CFUNC|FFUNC>
>>     <LFUNC>: Lua function @ <gcr>, <nupvals> upvalues, <chunk:line>
>>     <CFUNC>: C function <mcode address>
>> -  <FFUNC>: fast function #<ffid>
>> +  <FFUNC>: fast function <ffname> (#<ffid>)
>>   * LJ_TTRACE: trace <traceno> @ <gcr>
>>   * LJ_TCDATA: cdata @ <gcr>
>>   * LJ_TTAB: table @ <gcr> (asize: <asize>, hmask: <hmask>)
>> diff --git a/test/tarantool-debugger-tests/debug-extension-tests.py 
>> b/test/tarantool-debugger-tests/debug-extension-tests.py
>> index 5e369f00..fe5e34f5 100644
>> --- a/test/tarantool-debugger-tests/debug-extension-tests.py
>> +++ b/test/tarantool-debugger-tests/debug-extension-tests.py
> fallback "unknown" is not covered
Added the requested tests (both for 'lj-func' and 'lj-gco')
>> @@ -326,7 +326,7 @@ GCO_ARGS = (
>>       'coroutine.create(function() end),\n'
>>       'function() end,\n'
>>       'require,\n'
>> -    'print,\n'
>> +    'math.min,\n'
>>       'ffi.new("int*"),\n'
>>       '{1},\n'
>>       'newproxy(),\n'
> added also tests for: getmetatable(io.stdout).__gc and 
> getmetatable(io.stdout).__tostring to cover regexp
Done
>> @@ -338,7 +338,7 @@ GCO_RX = (
>>       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'fast function math.min \(#[0-9]+\)\n'
>>       r'cdata @ ' + RX_ADDR + r' \[\d+\] <int \*> 0x0\n'
>>       r'table @ ' + RX_ADDR + r' \(asize: \d+, hmask: ' + RX_HASH + 
>> r'\)\n'
>>       r'userdata @ ' + RX_ADDR + r'\n'
>> @@ -367,6 +367,7 @@ class TestLJTV(TestCaseBase):
>>       # Sorted in LJT order.
>>       lua_script = (
>>           'local ffi = require("ffi")\n'
>> +        'local math = require("math")\n'
>>           'print(\n'
>>           '  nil,\n'
>>           '  false,\n'
>> @@ -435,6 +436,7 @@ class TestLJGCo(TestCaseBase):
>>         lua_script = (
>>           'local ffi = require("ffi")\n'
>> +        'local math = require("math")\n'
>>           'print(\n' +
>>           GCO_ARGS +
>>           '  1\n'  # Stub for the pattern.
> add also a test with "lj-func" for any ffunc
Done

-- 
Best regards,
Mikhail Elhimov