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* [Bug c/46850] New: optimization of inline function leads to incorrect integer comparison result
@ 2010-12-08 15:31 brad.king at kitware dot com
2010-12-08 15:35 ` [Bug c/46850] " rguenth at gcc dot gnu.org
2010-12-08 15:57 ` brad.king at kitware dot com
0 siblings, 2 replies; 3+ messages in thread
From: brad.king at kitware dot com @ 2010-12-08 15:31 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46850
Summary: optimization of inline function leads to incorrect
integer comparison result
Product: gcc
Version: 4.4.5
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: brad.king@kitware.com
Created attachment 22686
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22686
Bash script to reproduce bug
The output of the attached script is expected to be "0" but is "1".
Tested on GCC 4.4.5, Linux x86_64, but I believe it occurs elsewhere too and in
other versions.
At first I encountered the problem with -O2 but then narrowed it down to
-O -fstrict-overflow -foptimize-sibling-calls -ftree-vrp
as shown in the script. Adding
-fno-guess-branch-probability
fixes the problem. Removing "inline" from the function fixes the problem.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/46850] optimization of inline function leads to incorrect integer comparison result
2010-12-08 15:31 [Bug c/46850] New: optimization of inline function leads to incorrect integer comparison result brad.king at kitware dot com
@ 2010-12-08 15:35 ` rguenth at gcc dot gnu.org
2010-12-08 15:57 ` brad.king at kitware dot com
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2010-12-08 15:35 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46850
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-12-08 15:35:41 UTC ---
You invoke undefined behavior by overflowing a signed integer.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/46850] optimization of inline function leads to incorrect integer comparison result
2010-12-08 15:31 [Bug c/46850] New: optimization of inline function leads to incorrect integer comparison result brad.king at kitware dot com
2010-12-08 15:35 ` [Bug c/46850] " rguenth at gcc dot gnu.org
@ 2010-12-08 15:57 ` brad.king at kitware dot com
1 sibling, 0 replies; 3+ messages in thread
From: brad.king at kitware dot com @ 2010-12-08 15:57 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46850
--- Comment #2 from brad.king at kitware dot com 2010-12-08 15:57:25 UTC ---
[smacks forehead]
^ permalink raw reply [flat|nested] 3+ messages in thread
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2010-12-08 15:31 [Bug c/46850] New: optimization of inline function leads to incorrect integer comparison result brad.king at kitware dot com
2010-12-08 15:35 ` [Bug c/46850] " rguenth at gcc dot gnu.org
2010-12-08 15:57 ` brad.king at kitware dot com
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