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

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

Hi, Sergey!

Thanks for the review! See my comments below

On 22.09.2026 12:16, Sergey Kaplun wrote:
> Hi, Mikhail!
> Thanks for the patch!
> Generally, LGTM, with minor suggestions below.
>
> On 09.09.26, Mikhail Elhimov wrote:
>> Part of tarantool/tarantool#4808
>> ---
>> This patch is to be applied after the 'avoid hardcoded enums' patch.
>>
>> 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                               | 17 +++++++++++------
>>   .../debug-extension-tests.py                    |  2 +-
>>   2 files changed, 12 insertions(+), 7 deletions(-)
>>
>> diff --git a/src/luajit_dbg.py b/src/luajit_dbg.py
>> index 1ac1d275..262fdad1 100644
>> --- a/src/luajit_dbg.py
>> +++ b/src/luajit_dbg.py
>> @@ -1682,8 +1682,11 @@ def ir_kint64(ir):
>>   
>>   # Dumpers.
>>   
>> +FF_NAMES = EnumBasedList('FastFunc', 'FF__MAX', cut_prefix, 'FF_')
> It would be nice to replace `_` in functions names to `.`.
> Resulting: math_min -> math.min

Then what about these and similar ones (they have 3 underscores in a row):

ffi_meta___index

io_method___gc

?

May be replace only first underscore?

> Minor: I would rather placed it somewhere into the section:
> | # LuaJIT macro implementations and structure access.
Done
>> +
>>   # GCobj dumpers.
>>   
>> +
>>   def dump_lj_gco_str(gcobj):
>>       return 'string {body} @ {address}'.format(
>>           body=strdata(gcobj),
>> @@ -1705,7 +1708,7 @@ 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)
>> @@ -1718,7 +1721,8 @@ 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"
>> +        return 'fast function #{}({})'.format(ffid, ffname)
> I suggest the following format insted:
> | 'fast function {} (#{})'.format(ffname, ffid)
>
> Generally we needed ffid less then the function name.
Done
>>   
>>   
>>   def dump_lj_gco_trace(gcobj):
>> @@ -2068,7 +2072,7 @@ def dump_proto(proto):
>>   
>>   
>>   def dump_func(func):
>> -    ffid = func['ffid']
>> +    ffid = int(func['ffid'])
>>   
>>       if ffid == 0:
>>           pt = funcproto(func)
>> @@ -2076,7 +2080,8 @@ 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"
>> +        return 'fast function #{}({})\n'.format(ffid, ffname)
> I suggest the following format insted:
> | 'fast function {} (#{})\n'.format(ffname, ffid)
>
> Generally we needed ffid less then the function name.
Done
>>   
>>   
>>   # FFI dumpers.
>> @@ -2702,7 +2707,7 @@ 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 #<ffid>(<ffname>)
> I suggest the following format instead:
>
> | <FFUNC>: fast function <ffname> (#<ffid>)
Done
>>   * LJ_TTRACE: trace <traceno> @ <gcr>
>>   * LJ_TCDATA: cdata @ <gcr>
>>   * LJ_TTAB: table @ <gcr> (asize: <asize>, hmask: <hmask>)
>> @@ -2921,7 +2926,7 @@ 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>
> I suggest the following format instead:
>
> | <FFUNC>: fast function <ffname> (#<ffid>)
Done
>> +  <FFUNC>: fast function #<ffid>(<ffname>)
>>   * 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 9989032b..40a27c3a 100644
>> --- a/test/tarantool-debugger-tests/debug-extension-tests.py
>> +++ b/test/tarantool-debugger-tests/debug-extension-tests.py
>> @@ -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 #[0-9]+\(\w+\)\n'
> Lets check the specific name here. I suggest `math.min` to check the
> _ -> . mapping.
No problem, but first we need to agree on how to handle underscores (see 
above comment about multiple undescores)
>
>> ing     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'
>> -- 
>> 2.43.0
>>
-- 
Best regards,
Mikhail Elhimov