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

[Mikhail Elhimov]

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"
+        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"
+        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
@@ -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'
@@ -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.
-- 
2.43.0