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* [Bug tree-optimization/102666] New: Wrong loop optimization for unsigned types
@ 2021-10-09 17:03 davidsondfgl at gmail dot com
2021-10-09 17:28 ` [Bug tree-optimization/102666] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: davidsondfgl at gmail dot com @ 2021-10-09 17:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102666
Bug ID: 102666
Summary: Wrong loop optimization for unsigned types
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: davidsondfgl at gmail dot com
Target Milestone: ---
The code below produces incorrect result when any optimizations (-O1/-O2/-O3)
are enabled:
$ cat unsigned-bug.c
int main(void) {
for (unsigned a = 0, b = 0; a < 6; a += 1, b += 2)
if (b < a)
return 1;
return 0;
}
$ gcc -Wall -Wextra unsigned-bug.c; ./a.out; echo $?
0
$ gcc -Wall -Wextra unsigned-bug.c -O1; ./a.out; echo $?
1
$ gcc -Wall -Wextra unsigned-bug.c -O2; ./a.out; echo $?
1
$ gcc -Wall -Wextra unsigned-bug.c -O3; ./a.out; echo $?
1
This affects all releases as of 9.1, including the master branch (commit
2b30143).
A bisect between v9.1 and v8.3 indicates that this may have been introduced in
r266171, as I can revert this commit (a81e2c6) in all releases up to v11.2 and
get the expected behavior.
It is also worthwhile to note that this only occurs for unsigned types.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102666] Wrong loop optimization for unsigned types
2021-10-09 17:03 [Bug tree-optimization/102666] New: Wrong loop optimization for unsigned types davidsondfgl at gmail dot com
@ 2021-10-09 17:28 ` pinskia at gcc dot gnu.org
2021-10-09 21:58 ` [Bug tree-optimization/102666] Wrong loop optimization for unsigned types after r9-4145 pinskia at gcc dot gnu.org
2021-10-09 22:06 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-10-09 17:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102666
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|UNCONFIRMED |RESOLVED
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 100740 (or PR 101508 or PR 101972).
*** This bug has been marked as a duplicate of bug 100740 ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102666] Wrong loop optimization for unsigned types after r9-4145
2021-10-09 17:03 [Bug tree-optimization/102666] New: Wrong loop optimization for unsigned types davidsondfgl at gmail dot com
2021-10-09 17:28 ` [Bug tree-optimization/102666] " pinskia at gcc dot gnu.org
@ 2021-10-09 21:58 ` pinskia at gcc dot gnu.org
2021-10-09 22:06 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-10-09 21:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102666
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ibuclaw at gcc dot gnu.org
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 102673 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/102666] Wrong loop optimization for unsigned types after r9-4145
2021-10-09 17:03 [Bug tree-optimization/102666] New: Wrong loop optimization for unsigned types davidsondfgl at gmail dot com
2021-10-09 17:28 ` [Bug tree-optimization/102666] " pinskia at gcc dot gnu.org
2021-10-09 21:58 ` [Bug tree-optimization/102666] Wrong loop optimization for unsigned types after r9-4145 pinskia at gcc dot gnu.org
@ 2021-10-09 22:06 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-10-09 22:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102666
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 102673 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-10-09 22:06 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-10-09 17:03 [Bug tree-optimization/102666] New: Wrong loop optimization for unsigned types davidsondfgl at gmail dot com
2021-10-09 17:28 ` [Bug tree-optimization/102666] " pinskia at gcc dot gnu.org
2021-10-09 21:58 ` [Bug tree-optimization/102666] Wrong loop optimization for unsigned types after r9-4145 pinskia at gcc dot gnu.org
2021-10-09 22:06 ` pinskia at gcc dot gnu.org
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