[Tarantool-patches] [PATCH luajit v2] luajit-gdb: support dualnum mode

[Maxim Kokryashkin]

luajit-gdb.py displays integers in LJ_DUALNUM mode as nan-s. The
dumper function produces output thinking of any input value as of a
double. However, in DUALNUM mode, integers and doubles are stored
differently, so the `itype` of a float number must be less than
`LJ_TISNUM`, and the `itype` of an integer must be `LJ_TISNUM`. With
this fact in mind, we can easily differentiate one from another.

Closes tarantool/tarantool#6224
---
Changes in v2:
  - Fixed comments as per review by Sergey

 src/luajit-gdb.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/luajit-gdb.py b/src/luajit-gdb.py
index c50405ad..d4882dd7 100644
--- a/src/luajit-gdb.py
+++ b/src/luajit-gdb.py
@@ -238,8 +238,11 @@ def jit_state(g):
         0x15: 'ERR',
     }.get(int(J(g)['state']), 'INVALID')
 
+def tvisint(o):
+    return LJ_DUALNUM and itype(o) == LJ_TISNUM
+
 def tvisnumber(o):
-    return itype(o) <= (0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX'])
+    return itype(o) <= LJ_TISNUM
 
 def tvislightud(o):
     if LJ_64 and not LJ_GC64:
@@ -343,7 +346,10 @@ def dump_lj_tudata(tv):
     return 'userdata @ {}'.format(strx64(gcval(tv['gcr'])))
 
 def dump_lj_tnumx(tv):
-    return 'number {}'.format(cast('double', tv['n']))
+    if tvisint(tv):
+        return 'number {}'.format(cast('int32_t', tv['i']))
+    else:
+        return 'number {}'.format(cast('double', tv['n']))
 
 def dump_lj_invalid(tv):
     return 'not valid type @ {}'.format(strx64(gcval(tv['gcr'])))
@@ -683,7 +689,7 @@ The command requires no args and dumps current GC stats:
         ))
 
 def init(commands):
-    global LJ_64, LJ_GC64, LJ_FR2, PADDING
+    global LJ_64, LJ_GC64, LJ_DUALNUM, LJ_TISNUM, LJ_FR2, PADDING
 
     # XXX Fragile: though connecting the callback looks like a crap but it
     # respects both Python 2 and Python 3 (see #4828).
@@ -724,6 +730,7 @@ def init(commands):
     try:
         LJ_64 = str(gdb.parse_and_eval('IRT_PTR')) == 'IRT_P64'
         LJ_FR2 = LJ_GC64 = str(gdb.parse_and_eval('IRT_PGC')) == 'IRT_P64'
+        LJ_DUALNUM = lookup('lj_lib_checknumber') is not None
     except:
         gdb.write('luajit-gdb.py failed to load: '
                   'no debugging symbols found for libluajit\n')
@@ -733,6 +740,7 @@ def init(commands):
         command(name)
 
     PADDING = ' ' * len(':' + hex((1 << (47 if LJ_GC64 else 32)) - 1))
+    LJ_TISNUM = 0xfffeffff if LJ_64 and not LJ_GC64 else LJ_T['NUMX']
 
     gdb.write('luajit-gdb.py is successfully loaded\n')
 
-- 
2.32.0