* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
@ 2022-10-26 8:03 ` marxin at gcc dot gnu.org
2022-10-26 8:03 ` marxin at gcc dot gnu.org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: marxin at gcc dot gnu.org @ 2022-10-26 8:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Component|c |tree-optimization
Last reconfirmed| |2022-10-26
Target Milestone|--- |13.0
Ever confirmed|0 |1
CC| |marxin at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
Summary|Wrong code at -Os on |[12/13 Regression] Wrong
|x86_64-linux-gnu |code at -Os on
| |x86_64-linux-gnu since
| |r12-383-g32955416d8040b1f
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
A bit reduced, started with r12-383-g32955416d8040b1f
int *a;
static int **b = &a;
int c[4];
int d;
int e(int);
static int f(char, int);
void g() { e((f(0, 0), 0)); }
int e(int h) { *a = 0; }
int f(char k, int j) {
for (;;) {
for (; k <= 3; k++) {
*b = &c[k];
for (; d <= 1; d++)
*a = 3;
}
break;
}
}
int main() {
int i;
g();
if (c[0] != 3)
__builtin_abort ();
}
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
2022-10-26 8:03 ` [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f marxin at gcc dot gnu.org
@ 2022-10-26 8:03 ` marxin at gcc dot gnu.org
2022-10-26 17:00 ` pinskia at gcc dot gnu.org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: marxin at gcc dot gnu.org @ 2022-10-26 8:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
2022-10-26 8:03 ` [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f marxin at gcc dot gnu.org
2022-10-26 8:03 ` marxin at gcc dot gnu.org
@ 2022-10-26 17:00 ` pinskia at gcc dot gnu.org
2022-10-28 9:48 ` rguenth at gcc dot gnu.org
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-10-26 17:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|13.0 |12.3
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (2 preceding siblings ...)
2022-10-26 17:00 ` pinskia at gcc dot gnu.org
@ 2022-10-28 9:48 ` rguenth at gcc dot gnu.org
2022-10-28 13:03 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-28 9:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Priority|P1 |P2
Status|NEW |ASSIGNED
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I will have a look.
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (3 preceding siblings ...)
2022-10-28 9:48 ` rguenth at gcc dot gnu.org
@ 2022-10-28 13:03 ` rguenth at gcc dot gnu.org
2022-10-28 13:40 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-28 13:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Deleted dead store: MEM <int[4]> [(int *)&c][_6] = 3;
Further reduced testcase, we mistreat SSA name indexes with must aliases.
We do have
/* If we visit this PHI by following a backedge then we have to
make sure ref->ref only refers to SSA names that are invariant
with respect to the loop represented by this PHI node. */
if (dominated_by_p (CDI_DOMINATORS, gimple_bb (stmt),
gimple_bb (temp))
&& !for_each_index (ref->ref ? &ref->ref : &ref->base,
check_name, gimple_bb (temp)))
return DSE_STORE_LIVE;
that is supposed to catch this but somehow it doesn't trigger here.
int *a;
int c[4];
int d;
static int
f(char k, int j)
{
for (; k <= 3; k++)
{
a = &c[k];
for (; d <= 1; d++)
*a = 3;
}
*a = 0;
}
int main()
{
int i;
f(0, 0);
if (c[0] != 3)
__builtin_abort ();
}
So what happens is that we elide processing of this check with
/* In addition to kills we can remove defs whose only use
is another def in defs. That can only ever be PHIs of which
we track two for simplicity reasons, the first and last in
{first,last}_phi_def (we fail for multiple PHIs anyways).
We can also ignore defs that feed only into
already visited PHIs. */
else if (single_imm_use (vdef, &use_p, &use_stmt)
&& (use_stmt == first_phi_def
|| use_stmt == last_phi_def
|| (gimple_code (use_stmt) == GIMPLE_PHI
&& bitmap_bit_p (visited,
SSA_NAME_VERSION
(PHI_RESULT (use_stmt))))))
where we have the last PHI being the outer loop virtual PHI and the first
PHI being the loop exit PHI of the outer loop and we've already processed
the single immediate use of the outer loop PHI, the inner loop PHI. But
we still have to perform the above check!
It's easiest to perform the check when we visit the PHI node instead of
delaying it to the actual processing loop.
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12/13 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (4 preceding siblings ...)
2022-10-28 13:03 ` rguenth at gcc dot gnu.org
@ 2022-10-28 13:40 ` cvs-commit at gcc dot gnu.org
2022-10-28 13:43 ` [Bug tree-optimization/107407] [12 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-10-28 13:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:031a400e49d8db156c43f9ec0b21ab0c2aee8c6d
commit r13-3546-g031a400e49d8db156c43f9ec0b21ab0c2aee8c6d
Author: Richard Biener <rguenther@suse.de>
Date: Fri Oct 28 15:03:49 2022 +0200
tree-optimization/107407 - wrong code with DSE
So what happens is that we elide processing of this check with
/* In addition to kills we can remove defs whose only use
is another def in defs. That can only ever be PHIs of which
we track two for simplicity reasons, the first and last in
{first,last}_phi_def (we fail for multiple PHIs anyways).
We can also ignore defs that feed only into
already visited PHIs. */
else if (single_imm_use (vdef, &use_p, &use_stmt)
&& (use_stmt == first_phi_def
|| use_stmt == last_phi_def
|| (gimple_code (use_stmt) == GIMPLE_PHI
&& bitmap_bit_p (visited,
SSA_NAME_VERSION
(PHI_RESULT (use_stmt))))))
where we have the last PHI being the outer loop virtual PHI and the first
PHI being the loop exit PHI of the outer loop and we've already processed
the single immediate use of the outer loop PHI, the inner loop PHI. But
we still have to perform the above check!
It's easiest to perform the check when we visit the PHI node instead of
delaying it to the actual processing loop.
PR tree-optimization/107407
* tree-ssa-dse.cc (dse_classify_store): Perform backedge
varying index check when collecting PHI uses rather than
after optimizing processing of the candidate defs.
* gcc.dg/torture/pr107407.c: New testcase.
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (5 preceding siblings ...)
2022-10-28 13:40 ` cvs-commit at gcc dot gnu.org
@ 2022-10-28 13:43 ` rguenth at gcc dot gnu.org
2022-12-12 11:20 ` cvs-commit at gcc dot gnu.org
2022-12-12 11:21 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-28 13:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |12.2.0
Summary|[12/13 Regression] Wrong |[12 Regression] Wrong code
|code at -Os on |at -Os on x86_64-linux-gnu
|x86_64-linux-gnu since |since
|r12-383-g32955416d8040b1f |r12-383-g32955416d8040b1f
Known to work| |13.0
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk sofar.
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (6 preceding siblings ...)
2022-10-28 13:43 ` [Bug tree-optimization/107407] [12 " rguenth at gcc dot gnu.org
@ 2022-12-12 11:20 ` cvs-commit at gcc dot gnu.org
2022-12-12 11:21 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-12-12 11:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:e0e37f97e67c99604129eeac2e73ccd3719ccb28
commit r12-8973-ge0e37f97e67c99604129eeac2e73ccd3719ccb28
Author: Richard Biener <rguenther@suse.de>
Date: Fri Oct 28 15:03:49 2022 +0200
tree-optimization/107407 - wrong code with DSE
So what happens is that we elide processing of this check with
/* In addition to kills we can remove defs whose only use
is another def in defs. That can only ever be PHIs of which
we track two for simplicity reasons, the first and last in
{first,last}_phi_def (we fail for multiple PHIs anyways).
We can also ignore defs that feed only into
already visited PHIs. */
else if (single_imm_use (vdef, &use_p, &use_stmt)
&& (use_stmt == first_phi_def
|| use_stmt == last_phi_def
|| (gimple_code (use_stmt) == GIMPLE_PHI
&& bitmap_bit_p (visited,
SSA_NAME_VERSION
(PHI_RESULT (use_stmt))))))
where we have the last PHI being the outer loop virtual PHI and the first
PHI being the loop exit PHI of the outer loop and we've already processed
the single immediate use of the outer loop PHI, the inner loop PHI. But
we still have to perform the above check!
It's easiest to perform the check when we visit the PHI node instead of
delaying it to the actual processing loop.
PR tree-optimization/107407
* tree-ssa-dse.cc (dse_classify_store): Perform backedge
varying index check when collecting PHI uses rather than
after optimizing processing of the candidate defs.
* gcc.dg/torture/pr107407.c: New testcase.
(cherry picked from commit 031a400e49d8db156c43f9ec0b21ab0c2aee8c6d)
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug tree-optimization/107407] [12 Regression] Wrong code at -Os on x86_64-linux-gnu since r12-383-g32955416d8040b1f
2022-10-26 7:44 [Bug c/107407] New: Wrong code at -Os on x86_64-linux-gnu shaohua.li at inf dot ethz.ch
` (7 preceding siblings ...)
2022-12-12 11:20 ` cvs-commit at gcc dot gnu.org
@ 2022-12-12 11:21 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-12-12 11:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107407
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Known to work| |12.2.1
Status|ASSIGNED |RESOLVED
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 10+ messages in thread