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* [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value
@ 2020-06-17 20:17 gabravier at gmail dot com
2020-06-17 22:14 ` [Bug tree-optimization/95729] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: gabravier at gmail dot com @ 2020-06-17 20:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95729
Bug ID: 95729
Summary: Failure to optimize away certain returns when the
condition to reach them is a calculation that already
results in that value
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int f(int a, int b)
{
if (a != b)
return a - b;
else
return 0;
}
This can be optimized to `return a - b;`. This optimization is done by LLVM,
but not by GCC.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95729] Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value
2020-06-17 20:17 [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value gabravier at gmail dot com
@ 2020-06-17 22:14 ` pinskia at gcc dot gnu.org
2020-06-18 8:39 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2020-06-17 22:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95729
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95729] Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value
2020-06-17 20:17 [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value gabravier at gmail dot com
2020-06-17 22:14 ` [Bug tree-optimization/95729] " pinskia at gcc dot gnu.org
@ 2020-06-18 8:39 ` rguenth at gcc dot gnu.org
2021-11-17 9:41 ` pinskia at gcc dot gnu.org
2023-05-06 23:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-06-18 8:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95729
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2020-06-18
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. Sth for phiopt and/or a cond_expr match.pd pattern (which phiopt
could exercise btw). a != b ? a - b : 0 -> a - b
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95729] Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value
2020-06-17 20:17 [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value gabravier at gmail dot com
2020-06-17 22:14 ` [Bug tree-optimization/95729] " pinskia at gcc dot gnu.org
2020-06-18 8:39 ` rguenth at gcc dot gnu.org
@ 2021-11-17 9:41 ` pinskia at gcc dot gnu.org
2023-05-06 23:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-17 9:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95729
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org
Status|NEW |ASSIGNED
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
;; a != b ? a - b : 0
Something like:
(simplify
(cond (ne:c @0 @1) (minus@2 @0 @1) zero_p)
(if (!HONOR_NANS (type) && !HONOR_SIGNED_ZEROS (type))
@2)
(simplify
(cond (eq:c @0 @1) zero_p (minus@2 @0 @1))
(if (!HONOR_NANS (type) && !HONOR_SIGNED_ZEROS (type))
@2)
Note I noticed LLVM 13 no longer does this optimization (I wonder if they have
a testsuite).
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/95729] Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value
2020-06-17 20:17 [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value gabravier at gmail dot com
` (2 preceding siblings ...)
2021-11-17 9:41 ` pinskia at gcc dot gnu.org
@ 2023-05-06 23:12 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-05-06 23:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95729
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
basically an exact dup of bug 19832.
*** This bug has been marked as a duplicate of bug 19832 ***
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-05-06 23:12 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-17 20:17 [Bug tree-optimization/95729] New: Failure to optimize away certain returns when the condition to reach them is a calculation that already results in that value gabravier at gmail dot com
2020-06-17 22:14 ` [Bug tree-optimization/95729] " pinskia at gcc dot gnu.org
2020-06-18 8:39 ` rguenth at gcc dot gnu.org
2021-11-17 9:41 ` pinskia at gcc dot gnu.org
2023-05-06 23:12 ` pinskia at gcc dot gnu.org
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