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* [Bug tree-optimization/21278] New: Move maximum out of a loop
@ 2005-04-29 8:17 tkoenig at gcc dot gnu dot org
2005-04-30 17:52 ` [Bug tree-optimization/21278] " pinskia at gcc dot gnu dot org
0 siblings, 1 reply; 4+ messages in thread
From: tkoenig at gcc dot gnu dot org @ 2005-04-29 8:17 UTC (permalink / raw)
To: gcc-bugs
This could help in reducing the amount of work for bounds
checking.
$ cat mymax.c
#include <stdlib.h>
#include <stdio.h>
int main()
{
char *p;
int i,j,n;
scanf("%d",&n);
j = 0;
for (i=0; i<n; i++)
{
if (j < i)
j = i;
}
printf("%d\n",j);
return 0;
}
$ gcc -g -funroll-all-loops -S -O3 -fdump-tree-optimized mymax.c
still does the do loop:
<L13>:;
j = 0;
i = 0;
<L0>:;
j = MAX_EXPR <j, i>;
i = i + 1;
if (i != n.10) goto <L0>; else goto <L4>;
when the loop could be optimized to
if (n <= 0)
j = 0;
else
j = n-1;
--
Summary: Move maximum out of a loop
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tkoenig at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21278
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21278] Move maximum out of a loop
2005-04-29 8:17 [Bug tree-optimization/21278] New: Move maximum out of a loop tkoenig at gcc dot gnu dot org
@ 2005-04-30 17:52 ` pinskia at gcc dot gnu dot org
0 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-04-30 17:52 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-04-30 17:52 -------
Confirmed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2005-04-30 17:52:01
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21278
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21278] Move maximum out of a loop
[not found] <bug-21278-4@http.gcc.gnu.org/bugzilla/>
2021-08-19 1:53 ` pinskia at gcc dot gnu.org
@ 2023-06-09 15:41 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-06-09 15:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21278
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2021-08-18 00:00:00 |2023-6-9
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, I think this is a job for final value replacement. I Know we handle &
already but this seems like something it could handle too.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/21278] Move maximum out of a loop
[not found] <bug-21278-4@http.gcc.gnu.org/bugzilla/>
@ 2021-08-19 1:53 ` pinskia at gcc dot gnu.org
2023-06-09 15:41 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-19 1:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21278
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2016-11-16 00:00:00 |2021-8-18
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
No compilers do this ...
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-06-09 15:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-04-29 8:17 [Bug tree-optimization/21278] New: Move maximum out of a loop tkoenig at gcc dot gnu dot org
2005-04-30 17:52 ` [Bug tree-optimization/21278] " pinskia at gcc dot gnu dot org
[not found] <bug-21278-4@http.gcc.gnu.org/bugzilla/>
2021-08-19 1:53 ` pinskia at gcc dot gnu.org
2023-06-09 15:41 ` pinskia at gcc dot gnu.org
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