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* [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
@ 2013-09-16 6:56 su at cs dot ucdavis.edu
2013-09-16 7:34 ` [Bug tree-optimization/58431] [4.9 Regression] " jakub at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: su at cs dot ucdavis.edu @ 2013-09-16 6:56 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58431
Bug ID: 58431
Summary: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
The current gcc trunk mis-compiles the following code on x86_64-linux at -O3 in
32-bit mode.
This is a regression from 4.8.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure
--enable-languages=c,c++,objc,obj-c++,fortran,lto
--with-gmp=/usr/local/gcc-trunk --with-mpfr=/usr/local/gcc-trunk
--with-mpc=/usr/local/gcc-trunk --with-cloog=/usr/local/gcc-trunk
--prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20130915 (experimental) [trunk revision 202599] (GCC)
$ gcc-trunk -m32 -O2 small.c
$ a.out
$ gcc-4.8 -m32 -O3 small.c
$ a.out
$ gcc-trunk -m32 -O3 small.c
$ a.out
Aborted (core dumped)
$
---------------------------------------
char a, h;
int b, d, e, g, j, k;
volatile int c;
short i;
int
main ()
{
int m = i ^= 1;
for (b = 0; b < 1; b++)
{
char o = m;
g = k;
j = j || c;
if (a != o)
for (; d < 1; d++)
;
else
{
char *p = &h;
*p = 1;
for (; e; e++)
;
}
}
if (h != 0)
__builtin_abort();
return 0;
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/58431] [4.9 Regression] wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
2013-09-16 6:56 [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode) su at cs dot ucdavis.edu
@ 2013-09-16 7:34 ` jakub at gcc dot gnu.org
2013-09-16 18:37 ` law at redhat dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-09-16 7:34 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58431
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-09-16
CC| |jakub at gcc dot gnu.org,
| |law at gcc dot gnu.org
Target Milestone|--- |4.9.0
Summary|wrong code at -O3 on |[4.9 Regression] wrong code
|x86_64-linux-gnu (in 32-bit |at -O3 on x86_64-linux-gnu
|mode) |(in 32-bit mode)
Ever confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r202489.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/58431] [4.9 Regression] wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
2013-09-16 6:56 [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode) su at cs dot ucdavis.edu
2013-09-16 7:34 ` [Bug tree-optimization/58431] [4.9 Regression] " jakub at gcc dot gnu.org
@ 2013-09-16 18:37 ` law at redhat dot com
2013-09-16 19:28 ` glisse at gcc dot gnu.org
2013-09-16 19:29 ` law at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: law at redhat dot com @ 2013-09-16 18:37 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58431
--- Comment #2 from Jeffrey A. Law <law at redhat dot com> ---
Jakub,
That doesn't make *any* sense. r202489 simply *avoids* doing any jump
threading in certain cases. If that change is indeed the trigger, then the
root cause is going to be a latent bug elsewhere.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/58431] [4.9 Regression] wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
2013-09-16 6:56 [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode) su at cs dot ucdavis.edu
2013-09-16 7:34 ` [Bug tree-optimization/58431] [4.9 Regression] " jakub at gcc dot gnu.org
2013-09-16 18:37 ` law at redhat dot com
@ 2013-09-16 19:28 ` glisse at gcc dot gnu.org
2013-09-16 19:29 ` law at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: glisse at gcc dot gnu.org @ 2013-09-16 19:28 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58431
--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
-fdisable-tree-phicprop2 lets it pass (the dumps appear identical before and
after this pass, but with verbose dumps we see some memory PHIs disappear)
-fdisable-tree-cddce2 also lets it pass, with larger differences in the dumps.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/58431] [4.9 Regression] wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode)
2013-09-16 6:56 [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode) su at cs dot ucdavis.edu
` (2 preceding siblings ...)
2013-09-16 19:28 ` glisse at gcc dot gnu.org
@ 2013-09-16 19:29 ` law at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: law at redhat dot com @ 2013-09-16 19:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58431
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #4 from Jeffrey A. Law <law at redhat dot com> ---
Verified as a duplicate.
*** This bug has been marked as a duplicate of bug 58418 ***
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2013-09-16 19:29 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2013-09-16 6:56 [Bug tree-optimization/58431] New: wrong code at -O3 on x86_64-linux-gnu (in 32-bit mode) su at cs dot ucdavis.edu
2013-09-16 7:34 ` [Bug tree-optimization/58431] [4.9 Regression] " jakub at gcc dot gnu.org
2013-09-16 18:37 ` law at redhat dot com
2013-09-16 19:28 ` glisse at gcc dot gnu.org
2013-09-16 19:29 ` law at redhat dot com
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