https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100047
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Component|c++ |tree-optimization
CC| |msebor at gcc dot gnu.org
Blocks| |78394, 82738
Last reconfirmed| |2021-04-12
Known to fail| |10.2.0, 11.0, 8.3.0, 9.3.0
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with GCC 11 and 10 and -Og only with the GCC 11 IL below. The
warning depends on a number of optimizations only a few of which are enabled at
-Og so it has a higher rate of false positives there. For GCC 12 with -Og we
might consider removing -Wmaybe-uninitialized from -Wall.
<bb 2> [local count: 1073741824]:
# .MEM_10 = VDEF <.MEM_1(D)>
D.56209 = D.55716;
# .MEM_11 = VDEF <.MEM_10>
D.51082 ={v} {CLOBBER};
# .MEM_12 = VDEF <.MEM_11>
MEM[(union _Storage *)&D.51082] ={v} {CLOBBER};
# .MEM_13 = VDEF <.MEM_12>
MEM[(struct _Optional_payload_base *)&D.51082]._M_engaged = 0; <<< store
# .MEM_14 = VDEF <.MEM_13>
D.56209 ={v} {CLOBBER};
# VUSE <.MEM_14>
_34 = MEM[(const struct _Optional_base
*)&D.51082]._M_payload.D.50287.D.50137._M_engaged; <<< read
if (_34 != 0) <<< not
folded
goto <bb 3>; [100.00%]
else
goto <bb 5>; [0.00%]
<bb 3> [local count: 1073741824]:
# VUSE <.MEM_14>
_36 = get (&MEM[(const struct packet_buffer *)&D.51082].m_ptr);
# VUSE <.MEM_14>
_37 = MEM[(const struct packet_buffer *)&D.51082].m_size; <<<
-Wmaybe-uninitialized
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394
[Bug 78394] False positives of maybe-uninitialized with -Og
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82738
[Bug 82738] [meta-bug] issues with the -Og optimization level
