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* [Bug tree-optimization/103354] New: missed optimization with & and | and compares
@ 2021-11-22 2:17 pinskia at gcc dot gnu.org
2021-11-22 2:23 ` [Bug tree-optimization/103354] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-22 2:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103354
Bug ID: 103354
Summary: missed optimization with & and | and compares
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
int h(int a, int b, int c, int d)
{
return (c & -(a==b)) | (d & -(a!=b));
}
---- CUT ---
We currently don't optimize the above down to just:
int h(int a, int b, int c, int d)
{
return (a==b) ? c : d;
}
This is from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92342#c4
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/103354] missed optimization with & and | and compares
2021-11-22 2:17 [Bug tree-optimization/103354] New: missed optimization with & and | and compares pinskia at gcc dot gnu.org
@ 2021-11-22 2:23 ` pinskia at gcc dot gnu.org
2023-03-13 8:53 ` roger at nextmovesoftware dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-22 2:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103354
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2021-11-22
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
After my patch for PR 92342, we get:
_4 = a_9(D) == b_10(D) ? c_11(D) : 0;
_8 = a_9(D) != b_10(D) ? d_12(D) : 0;
_13 = _4 | _8;
A few patterns are needed here really:
One pattern simple is:
(simplify
(bit_ior:c
(cond @0 @1 integer_zero_p)
(cond @0 integer_zero_p @2))
(cond @0 @1 @2))
But the next one is harder and requires a double for loop. I will handle it
soon.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/103354] missed optimization with & and | and compares
2021-11-22 2:17 [Bug tree-optimization/103354] New: missed optimization with & and | and compares pinskia at gcc dot gnu.org
2021-11-22 2:23 ` [Bug tree-optimization/103354] " pinskia at gcc dot gnu.org
@ 2023-03-13 8:53 ` roger at nextmovesoftware dot com
2023-03-13 17:52 ` pinskia at gcc dot gnu.org
2023-03-13 17:53 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: roger at nextmovesoftware dot com @ 2023-03-13 8:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103354
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |roger at nextmovesoftware dot com
--- Comment #2 from Roger Sayle <roger at nextmovesoftware dot com> ---
Hi Andrew,
I believe this missed-optimization is now implemented, and GCC generates the
same (or equivalent) code for all of:
int h1(int a, int b, int c, int d) {
return (c & -(a==b)) | (d & -(a!=b));
}
int h2(int a, int b, int c, int d) {
return (a==b) ? c : d;
}
int h3(int a, int b, int c, int d) {
int t1 = a==b ? c : 0;
int t2 = a==b ? 0 : d;
return t1 | t2;
}
int h4(int a, int b, int c, int d) {
int t1 = a==b ? c : 0;
int t2 = a!=b ? d : 0;
return t1 | t2;
}
If you agree we can close this PR. I don't think this needs a new test case in
the testsuite, but I'll leave that up to you.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/103354] missed optimization with & and | and compares
2021-11-22 2:17 [Bug tree-optimization/103354] New: missed optimization with & and | and compares pinskia at gcc dot gnu.org
2021-11-22 2:23 ` [Bug tree-optimization/103354] " pinskia at gcc dot gnu.org
2023-03-13 8:53 ` roger at nextmovesoftware dot com
@ 2023-03-13 17:52 ` pinskia at gcc dot gnu.org
2023-03-13 17:53 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-13 17:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103354
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
h in comment #0 was fixed by r13-4620-g4d9db4bdd458a4 which has a testcase for
this: gcc.target/aarch64/if-compare_1.c (not a generic one though but I think
that is ok for now) .
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/103354] missed optimization with & and | and compares
2021-11-22 2:17 [Bug tree-optimization/103354] New: missed optimization with & and | and compares pinskia at gcc dot gnu.org
` (2 preceding siblings ...)
2023-03-13 17:52 ` pinskia at gcc dot gnu.org
@ 2023-03-13 17:53 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-13 17:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103354
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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2021-11-22 2:17 [Bug tree-optimization/103354] New: missed optimization with & and | and compares pinskia at gcc dot gnu.org
2021-11-22 2:23 ` [Bug tree-optimization/103354] " pinskia at gcc dot gnu.org
2023-03-13 8:53 ` roger at nextmovesoftware dot com
2023-03-13 17:52 ` pinskia at gcc dot gnu.org
2023-03-13 17:53 ` pinskia at gcc dot gnu.org
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