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* [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain
@ 2022-08-26 11:33 rguenth at gcc dot gnu.org
2022-09-06 12:56 ` [Bug tree-optimization/106754] " cvs-commit at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-08-26 11:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106754
Bug ID: 106754
Summary: compute_control_dep_chain over-estimates domain
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
The following testcase shows compute_control_dep_chain for init_use_preds
of the 'return u' uninitialized use compute a path with w != 0 && v != 1,
leaving out the !(i < 10) loop exit predicate because of how the iteration
terminating condition on the post-dominator walk works. While there's a
special case for the loop exit edge itself, the following if (y) z = 1;
intermediate post-dominator will still make the iteration terminate early
before reaching if (v != 1) and eventually the target block. The parent
iteration which entered the loop will proceed to find that but the loop
exit condition will be lost.
extern unsigned bar (void);
extern void quux (void);
int z;
unsigned foo (unsigned v, int y, int w)
{
unsigned u;
if (v != 1)
u = bar ();
// This variantion from uninit-pred-11.c causes compute_control_dep_chain
// to run into a defect, producing z != 0 && v != 1, omitting !(i<10)
// from the path predicate
if (w)
{
for (int i = 0; i < 10; i++)
quux ();
if (y)
z = 1;
if (v != 1)
return u;
}
return 0;
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106754] compute_control_dep_chain over-estimates domain
2022-08-26 11:33 [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain rguenth at gcc dot gnu.org
@ 2022-09-06 12:56 ` cvs-commit at gcc dot gnu.org
2022-09-06 12:56 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-09-06 12:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106754
--- Comment #1 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:0a4a2667dc115ca73b552fcabf8570620dfbe55f
commit r13-2500-g0a4a2667dc115ca73b552fcabf8570620dfbe55f
Author: Richard Biener <rguenther@suse.de>
Date: Tue Sep 6 13:46:00 2022 +0200
tree-optimization/106754 - fix compute_control_dep_chain defect
The following handles the situation of a loop exit along the
control path to the PHI def or from there to the use in a different
way, aoviding premature abort of the walks as noticed in the two
cases where the exit is outermost (gcc.dg/uninit-pred-11.c) or
wrapped in a condition that is on the path (gcc.dg/uninit-pred-12.c).
Instead of handling such exits during recursion we now pick them
up in the parent when walking post-dominators. That requires an
additional post-dominator walk at the outermost level which is
facilitated by splitting out the walk to a helper function and
the existing wrapper added earlier.
The patch also removes the bogus early exit from
uninit_analysis::init_use_preds, fixing a simplified version
of the PR106155 testcase.
PR tree-optimization/106754
* gimple-predicate-analysis.cc (compute_control_dep_chain_pdom):
New function, split out from compute_control_dep_chain. Handle
loop-exit like conditions here by pushing to the control vector.
(compute_control_dep_chain): Adjust and streamline dumping.
In the wrapper perform a post-dominator walk as well.
(uninit_analysis::init_use_preds): Remove premature early exit.
* gcc.dg/uninit-pred-12.c: New testcase.
* gcc.dg/uninit-pr106155-1.c: Likewise.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106754] compute_control_dep_chain over-estimates domain
2022-08-26 11:33 [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain rguenth at gcc dot gnu.org
2022-09-06 12:56 ` [Bug tree-optimization/106754] " cvs-commit at gcc dot gnu.org
@ 2022-09-06 12:56 ` rguenth at gcc dot gnu.org
2022-11-22 10:15 ` vincent-gcc at vinc17 dot net
2022-11-28 22:36 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-09-06 12:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106754
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED
Known to work| |13.0
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106754] compute_control_dep_chain over-estimates domain
2022-08-26 11:33 [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain rguenth at gcc dot gnu.org
2022-09-06 12:56 ` [Bug tree-optimization/106754] " cvs-commit at gcc dot gnu.org
2022-09-06 12:56 ` rguenth at gcc dot gnu.org
@ 2022-11-22 10:15 ` vincent-gcc at vinc17 dot net
2022-11-28 22:36 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: vincent-gcc at vinc17 dot net @ 2022-11-22 10:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106754
Vincent Lefèvre <vincent-gcc at vinc17 dot net> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |vincent-gcc at vinc17 dot net
--- Comment #3 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to CVS Commits from comment #1)
> The patch also removes the bogus early exit from
> uninit_analysis::init_use_preds, fixing a simplified version
> of the PR106155 testcase.
This commit also fixes the PR80548 testcase. However, I had built this testcase
from more complex code, for which GCC still warns. So I'll have to find another
simplified testcase for a new PR...
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/106754] compute_control_dep_chain over-estimates domain
2022-08-26 11:33 [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain rguenth at gcc dot gnu.org
` (2 preceding siblings ...)
2022-11-22 10:15 ` vincent-gcc at vinc17 dot net
@ 2022-11-28 22:36 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-11-28 22:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106754
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |13.0
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-08-26 11:33 [Bug tree-optimization/106754] New: compute_control_dep_chain over-estimates domain rguenth at gcc dot gnu.org
2022-09-06 12:56 ` [Bug tree-optimization/106754] " cvs-commit at gcc dot gnu.org
2022-09-06 12:56 ` rguenth at gcc dot gnu.org
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