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* [Bug tree-optimization/108368] New: [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15
@ 2023-01-11 13:16 yann at ywg dot ch
2023-01-11 13:55 ` [Bug tree-optimization/108368] " rguenth at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: yann at ywg dot ch @ 2023-01-11 13:16 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108368
Bug ID: 108368
Summary: [13 Regression] Dead Code Elimination Regression at
-O3 since r13-1759-gdbb093f4f15
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: yann at ywg dot ch
Target Milestone: ---
Created attachment 54244
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54244&action=edit
Case file
cat case.c #1409
int a;
int b;
short c;
static int d = 4;
void foo();
void e(int f) {}
int main() {
unsigned g = -27;
for (; g > 7; ++g) {
e(c && g);
b ? 0 : a;
if (g) {
if (0 >= d)
foo();
} else
d = 0;
}
}
`gcc-f99d7d669eaa2830eb5878df4da67e77ec791522 (trunk) -O3` can not eliminate
`foo` but `gcc-releases/gcc-12.2.0 -O3` can.
`gcc-f99d7d669eaa2830eb5878df4da67e77ec791522 (trunk) -O3 -S -o /dev/stdout
case.c`
--------- OUTPUT ---------
main:
.LFB1:
.cfi_startproc
pushq %rbx
.cfi_def_cfa_offset 16
.cfi_offset 3, -16
movl $27, %ebx
.L5:
movl d(%rip), %eax
testl %eax, %eax
jle .L8
.L4:
xorl %eax, %eax
popq %rbx
.cfi_remember_state
.cfi_def_cfa_offset 8
ret
.p2align 4,,10
.p2align 3
.L8:
.cfi_restore_state
xorl %eax, %eax
call foo
subl $1, %ebx
jne .L5
jmp .L4
---------- END OUTPUT ---------
`gcc-releases/gcc-12.2.0 -O3 -S -o /dev/stdout case.c`
--------- OUTPUT ---------
main:
.LFB1:
.cfi_startproc
xorl %eax, %eax
ret
---------- END OUTPUT ---------
Bisects to: r13-1759-gdbb093f4f15
commit dbb093f4f15ea66f2ce5cd2dc1903a6894563356
Author: Andrew MacLeod <amacleod@redhat.com>
Date: Mon Jul 18 15:04:23 2022 -0400
Resolve complicated join nodes in range_from_dom.
Join nodes which carry outgoing ranges on incoming edges are uncommon,
but can still be resolved by setting the dominator range, and then
calculating incoming edges. Avoid doing so if one of the incoing edges
is not dominated by the same dominator.
* gimple-range-cache.cc (ranger_cache::range_from_dom): Check
for incoming ranges on join nodes and add to worklist.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/108368] [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15
2023-01-11 13:16 [Bug tree-optimization/108368] New: [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15 yann at ywg dot ch
@ 2023-01-11 13:55 ` rguenth at gcc dot gnu.org
2023-01-13 21:01 ` amacleod at redhat dot com
2023-02-21 13:14 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-01-11 13:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108368
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |13.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
range_from_dom looks expensive as well and the bb vs. prev_bb in walking
immediate dominators is quite confusing (not to speak about resolve_dom ...).
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/108368] [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15
2023-01-11 13:16 [Bug tree-optimization/108368] New: [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15 yann at ywg dot ch
2023-01-11 13:55 ` [Bug tree-optimization/108368] " rguenth at gcc dot gnu.org
@ 2023-01-13 21:01 ` amacleod at redhat dot com
2023-02-21 13:14 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: amacleod at redhat dot com @ 2023-01-13 21:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108368
--- Comment #2 from Andrew Macleod <amacleod at redhat dot com> ---
Not sure why it looks expensive, it is a lot cheaper than the original cache
propagation was, but still gets all the cases.
Regardless, the upcoming fix for 108356 fixes this PR as well.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/108368] [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15
2023-01-11 13:16 [Bug tree-optimization/108368] New: [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15 yann at ywg dot ch
2023-01-11 13:55 ` [Bug tree-optimization/108368] " rguenth at gcc dot gnu.org
2023-01-13 21:01 ` amacleod at redhat dot com
@ 2023-02-21 13:14 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-02-21 13:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108368
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's fixed on trunk now.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2023-01-11 13:16 [Bug tree-optimization/108368] New: [13 Regression] Dead Code Elimination Regression at -O3 since r13-1759-gdbb093f4f15 yann at ywg dot ch
2023-01-11 13:55 ` [Bug tree-optimization/108368] " rguenth at gcc dot gnu.org
2023-01-13 21:01 ` amacleod at redhat dot com
2023-02-21 13:14 ` rguenth at gcc dot gnu.org
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