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* [Bug tree-optimization/103535] New: [missed optimization] remainder-of-2 with subtract-1
@ 2021-12-02 22:17 jengelh at inai dot de
2021-12-02 22:19 ` [Bug tree-optimization/103535] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: jengelh at inai dot de @ 2021-12-02 22:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103535
Bug ID: 103535
Summary: [missed optimization] remainder-of-2 with subtract-1
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jengelh at inai dot de
Target Milestone: ---
gcc version 11.2.1 20210816 [revision 056e324ce46a7924b5cf10f61010cf9dd2ca10e9]
(SUSE Linux) x86_64
== input ==
unsigned int fff(unsigned int p)
{
// equivalent to return p & ~1;
if (p % 2 != 0)
--p;
return p;
}
== Observed output ==
» gcc -O2 -c x.cpp; objdump -Mintel -d x.o
0: 89 fa mov edx,edi
2: 89 f8 mov eax,edi
4: 83 e2 01 and edx,0x1
7: 83 fa 01 cmp edx,0x1
a: 83 d0 ff adc eax,0xffffffff
d: c3 ret
== Expected output ==
0: 89 f8 mov eax,edi
2: 83 e0 fe and eax,0xfffffffe
5: c3 ret
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103535] [missed optimization] remainder-of-2 with subtract-1
2021-12-02 22:17 [Bug tree-optimization/103535] New: [missed optimization] remainder-of-2 with subtract-1 jengelh at inai dot de
@ 2021-12-02 22:19 ` pinskia at gcc dot gnu.org
2021-12-02 22:35 ` pinskia at gcc dot gnu.org
2021-12-02 22:40 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-02 22:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103535
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
Severity|normal |enhancement
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-12-02
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Mine for GCC 13.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103535] [missed optimization] remainder-of-2 with subtract-1
2021-12-02 22:17 [Bug tree-optimization/103535] New: [missed optimization] remainder-of-2 with subtract-1 jengelh at inai dot de
2021-12-02 22:19 ` [Bug tree-optimization/103535] " pinskia at gcc dot gnu.org
@ 2021-12-02 22:35 ` pinskia at gcc dot gnu.org
2021-12-02 22:40 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-02 22:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103535
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=103216
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I have a patch which gets the optimized code (at least being able to generate
at the rtl level):
_1 = p_3(D) & 1;
_7 = _1 != 0;
_6 = (unsigned int) _7;
_9 = p_3(D) - _6;
movl %edi, %eax
andl $-2, %eax
ret
The patch is the one for PR 103216.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103535] [missed optimization] remainder-of-2 with subtract-1
2021-12-02 22:17 [Bug tree-optimization/103535] New: [missed optimization] remainder-of-2 with subtract-1 jengelh at inai dot de
2021-12-02 22:19 ` [Bug tree-optimization/103535] " pinskia at gcc dot gnu.org
2021-12-02 22:35 ` pinskia at gcc dot gnu.org
@ 2021-12-02 22:40 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-02 22:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103535
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is actually an exact dup of bug 97711.
*** This bug has been marked as a duplicate of bug 97711 ***
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-12-02 22:17 [Bug tree-optimization/103535] New: [missed optimization] remainder-of-2 with subtract-1 jengelh at inai dot de
2021-12-02 22:19 ` [Bug tree-optimization/103535] " pinskia at gcc dot gnu.org
2021-12-02 22:35 ` pinskia at gcc dot gnu.org
2021-12-02 22:40 ` pinskia at gcc dot gnu.org
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