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* [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x)
@ 2012-11-02 14:56 glisse at gcc dot gnu.org
2012-11-02 15:43 ` [Bug tree-optimization/55180] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: glisse at gcc dot gnu.org @ 2012-11-02 14:56 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55180
Bug #: 55180
Summary: Missed optimization abs(-x) -> abs(x)
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: glisse@gcc.gnu.org
double f(double x){
double y=-x;
return __builtin_fabs(y);
}
The negation doesn't disappear, even at -Ofast, I still see both "xor" and
"and" in the asm. (I don't think this optimization requires any unsafe math
option, but I am not completely sure about the trapping behavior)
Note that if I write __builtin_fabs(-x), the negation is removed before it has
a chance to appear in a dump.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/55180] Missed optimization abs(-x) -> abs(x)
2012-11-02 14:56 [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x) glisse at gcc dot gnu.org
@ 2012-11-02 15:43 ` pinskia at gcc dot gnu.org
2012-11-02 16:12 ` glisse at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-11-02 15:43 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55180
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Depends on| |16107
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-11-02 15:43:29 UTC ---
Related to or a dup of bug 16107.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/55180] Missed optimization abs(-x) -> abs(x)
2012-11-02 14:56 [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x) glisse at gcc dot gnu.org
2012-11-02 15:43 ` [Bug tree-optimization/55180] " pinskia at gcc dot gnu.org
@ 2012-11-02 16:12 ` glisse at gcc dot gnu.org
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: glisse at gcc dot gnu.org @ 2012-11-02 16:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55180
Marc Glisse <glisse at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> 2012-11-02 16:11:43 UTC ---
Thanks, I had missed that one. ABS_EXPR is a bit special in that it has its own
tree code, instead of appearing as a call to a builtin function, but the issue
is the same indeed, the optimization is there but can never be applied.
*** This bug has been marked as a duplicate of bug 16107 ***
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/55180] Missed optimization abs(-x) -> abs(x)
2012-11-02 14:56 [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x) glisse at gcc dot gnu.org
2012-11-02 15:43 ` [Bug tree-optimization/55180] " pinskia at gcc dot gnu.org
2012-11-02 16:12 ` glisse at gcc dot gnu.org
@ 2014-12-01 4:28 ` pinskia at gcc dot gnu.org
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2014-12-01 4:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55180
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|DUPLICATE |---
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reopening since this is not a dup of that bug.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/55180] Missed optimization abs(-x) -> abs(x)
2012-11-02 14:56 [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x) glisse at gcc dot gnu.org
` (2 preceding siblings ...)
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
@ 2014-12-01 4:28 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2014-12-01 4:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55180
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |5.0
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
But it was fixed in GCC 5.0.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-12-01 4:28 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2012-11-02 14:56 [Bug tree-optimization/55180] New: Missed optimization abs(-x) -> abs(x) glisse at gcc dot gnu.org
2012-11-02 15:43 ` [Bug tree-optimization/55180] " pinskia at gcc dot gnu.org
2012-11-02 16:12 ` glisse at gcc dot gnu.org
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
2014-12-01 4:28 ` pinskia at gcc dot gnu.org
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