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* [Bug tree-optimization/94930] New: Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv
@ 2020-05-03 0:22 gabravier at gmail dot com
2020-05-03 14:45 ` [Bug tree-optimization/94930] " glisse at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: gabravier at gmail dot com @ 2020-05-03 0:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94930
Bug ID: 94930
Summary: Failure to optimize out subvsi in expansion of
__builtin_memcmp with 1 as the operand with -ftrapv
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int memcmp1(const void *s, const void *c)
{
return __builtin_memcmp(s, c, 1);
}
With -O3 -ftrapv, LLVM outputs this :
memcmp1(void const*, void const*): # @memcmp1(void const*, void const*)
movzx eax, byte ptr [rdi]
movzx ecx, byte ptr [rsi]
sub eax, ecx
ret
GCC outputs this :
memcmp1(void const*, void const*):
sub rsp, 8
movzx edi, BYTE PTR [rdi]
movzx esi, BYTE PTR [rsi]
call __subvsi3
add rsp, 8
ret
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/94930] Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv
2020-05-03 0:22 [Bug tree-optimization/94930] New: Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv gabravier at gmail dot com
@ 2020-05-03 14:45 ` glisse at gcc dot gnu.org
2021-04-26 1:18 ` pinskia at gcc dot gnu.org
2021-12-23 5:14 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: glisse at gcc dot gnu.org @ 2020-05-03 14:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94930
--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
AFAIK -ftrapv doesn't work very well and is kind of abandoned, in favor of
-fsanitize=signed-integer-overflow (possibly with
-fsanitize-undefined-trap-on-error), which does generate the code you expect.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/94930] Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv
2020-05-03 0:22 [Bug tree-optimization/94930] New: Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv gabravier at gmail dot com
2020-05-03 14:45 ` [Bug tree-optimization/94930] " glisse at gcc dot gnu.org
@ 2021-04-26 1:18 ` pinskia at gcc dot gnu.org
2021-12-23 5:14 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-04-26 1:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94930
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/94930] Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv
2020-05-03 0:22 [Bug tree-optimization/94930] New: Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv gabravier at gmail dot com
2020-05-03 14:45 ` [Bug tree-optimization/94930] " glisse at gcc dot gnu.org
2021-04-26 1:18 ` pinskia at gcc dot gnu.org
@ 2021-12-23 5:14 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-23 5:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94930
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2021-12-23
Status|UNCONFIRMED |NEW
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-12-23 5:14 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-05-03 0:22 [Bug tree-optimization/94930] New: Failure to optimize out subvsi in expansion of __builtin_memcmp with 1 as the operand with -ftrapv gabravier at gmail dot com
2020-05-03 14:45 ` [Bug tree-optimization/94930] " glisse at gcc dot gnu.org
2021-04-26 1:18 ` pinskia at gcc dot gnu.org
2021-12-23 5:14 ` pinskia at gcc dot gnu.org
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