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* [Bug c/23657] New: Wrong code generated: too much optimized out
@ 2005-08-31 16:05 qrczak at knm dot org dot pl
2005-08-31 16:23 ` [Bug tree-optimization/23657] [4.1 Regression] " pinskia at gcc dot gnu dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: qrczak at knm dot org dot pl @ 2005-08-31 16:05 UTC (permalink / raw)
To: gcc-bugs
/* The result should be 7. When compiled with
gcc version 4.1.0 20050815 (experimental)
with some patches from PLD (incl. PR7776, PR20297, PR23128, PR22533, PR23386)
with -O, the result is 0. */
#include <stdio.h>
int arr[100];
int *alloc(void) {return arr;}
void fill(int n) {
int *result = alloc();
int *dest = result;
for(;;) {
int *next;
dest[0] = 7;
if (--n == 0) break;
next = dest + 1;
dest = next;
}
}
int main(void) {
fill(5);
printf("%d\n", arr[1]);
return 0;
}
/* Looking at the generated assembly code, the whole loop is optimized out,
except for filling the first element. Using less temporaries or inlining
alloc() makes the bug disappear. The bug manifests only with optimization
turned on. */
--
Summary: Wrong code generated: too much optimized out
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: qrczak at knm dot org dot pl
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23657
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/23657] [4.1 Regression] Wrong code generated: too much optimized out
2005-08-31 16:05 [Bug c/23657] New: Wrong code generated: too much optimized out qrczak at knm dot org dot pl
@ 2005-08-31 16:23 ` pinskia at gcc dot gnu dot org
2005-08-31 22:14 ` qrczak at knm dot org dot pl
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-08-31 16:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-08-31 16:19 -------
Confirmed, between t41.copyrename2 and t42.dom2, the V_MAY_DEF is removed.
After
*next_8 = 7;
Before:
# TMT.51_18 = V_MAY_DEF <TMT.51_4>;
*dest_2 = 7;
I think we are forgetting to copy the alias info.
I think this is fixed by the patch for PR 23509:
http://gcc.gnu.org/ml/gcc-patches/2005-08/msg01647.html
The tree-cfg.c part that is.
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |pinskia at gcc dot gnu dot
| |org
Status|UNCONFIRMED |NEW
Component|c |tree-optimization
Ever Confirmed| |1
GCC build triplet|i686-pc-linux-gnu |
GCC host triplet|i686-pc-linux-gnu |
GCC target triplet|i686-pc-linux-gnu |
Keywords| |alias, wrong-code
Last reconfirmed|0000-00-00 00:00:00 |2005-08-31 16:19:38
date| |
Summary|Wrong code generated: too |[4.1 Regression] Wrong code
|much optimized out |generated: too much
| |optimized out
Target Milestone|--- |4.1.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23657
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/23657] [4.1 Regression] Wrong code generated: too much optimized out
2005-08-31 16:05 [Bug c/23657] New: Wrong code generated: too much optimized out qrczak at knm dot org dot pl
2005-08-31 16:23 ` [Bug tree-optimization/23657] [4.1 Regression] " pinskia at gcc dot gnu dot org
@ 2005-08-31 22:14 ` qrczak at knm dot org dot pl
2005-08-31 22:23 ` pinskia at gcc dot gnu dot org
2005-08-31 22:23 ` qrczak at knm dot org dot pl
3 siblings, 0 replies; 5+ messages in thread
From: qrczak at knm dot org dot pl @ 2005-08-31 22:14 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From qrczak at knm dot org dot pl 2005-08-31 22:11 -------
> I think this is fixed by the patch for PR 23509:
> http://gcc.gnu.org/ml/gcc-patches/2005-08/msg01647.html
Indeed, applying this patch and recompiling gcc fixed the bug. Thanks.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23657
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/23657] [4.1 Regression] Wrong code generated: too much optimized out
2005-08-31 16:05 [Bug c/23657] New: Wrong code generated: too much optimized out qrczak at knm dot org dot pl
` (2 preceding siblings ...)
2005-08-31 22:23 ` pinskia at gcc dot gnu dot org
@ 2005-08-31 22:23 ` qrczak at knm dot org dot pl
3 siblings, 0 replies; 5+ messages in thread
From: qrczak at knm dot org dot pl @ 2005-08-31 22:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From qrczak at knm dot org dot pl 2005-08-31 22:23 -------
*** This bug has been marked as a duplicate of 23509 ***
--
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23657
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/23657] [4.1 Regression] Wrong code generated: too much optimized out
2005-08-31 16:05 [Bug c/23657] New: Wrong code generated: too much optimized out qrczak at knm dot org dot pl
2005-08-31 16:23 ` [Bug tree-optimization/23657] [4.1 Regression] " pinskia at gcc dot gnu dot org
2005-08-31 22:14 ` qrczak at knm dot org dot pl
@ 2005-08-31 22:23 ` pinskia at gcc dot gnu dot org
2005-08-31 22:23 ` qrczak at knm dot org dot pl
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-08-31 22:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-08-31 22:14 -------
(In reply to comment #2)
> Indeed, applying this patch and recompiling gcc fixed the bug. Thanks.
Thanks for trying the patch. I only thought about this patch because of the symptom was about the
same as other bug was.
--
What |Removed |Added
----------------------------------------------------------------------------
URL| |http://gcc.gnu.org/ml/gcc-
| |patches/2005-
| |08/msg01647.html
Keywords| |patch
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23657
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2005-08-31 22:23 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2005-08-31 16:05 [Bug c/23657] New: Wrong code generated: too much optimized out qrczak at knm dot org dot pl
2005-08-31 16:23 ` [Bug tree-optimization/23657] [4.1 Regression] " pinskia at gcc dot gnu dot org
2005-08-31 22:14 ` qrczak at knm dot org dot pl
2005-08-31 22:23 ` pinskia at gcc dot gnu dot org
2005-08-31 22:23 ` qrczak at knm dot org dot pl
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