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* [Bug rtl-optimization/107775] New: misoptimization in vec_set lower part of vector in the memory.
@ 2022-11-21 2:43 crazylht at gmail dot com
2022-11-22 8:34 ` [Bug rtl-optimization/107775] " rguenth at gcc dot gnu.org
2022-11-22 8:45 ` crazylht at gmail dot com
0 siblings, 2 replies; 3+ messages in thread
From: crazylht at gmail dot com @ 2022-11-21 2:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107775
Bug ID: 107775
Summary: misoptimization in vec_set lower part of vector in the
memory.
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
CC: tnfchris at gcc dot gnu.org
Target Milestone: ---
Target: aarch64-linux-gnu
The case is found when i'm looking at
https://gcc.gnu.org/pipermail/gcc-patches/2022-November/606373.html, currently
x86 gcc can optimize set_lower same as set_lower1, but not after adjusting in
can_change_mode_class. The issue can be reproduce with aarch64 gcc. I'm looking
at rtl dump, the main difference comes from subreg1, where currently it will
split 128-bit load/store into 2 64-bit load/stores which expose the opportunity
to optimize the upper 64-bit load/store off.
typedef double v2df __attribute__((vector_size(16)));
v2df reg;
void
set_lower (double b)
{
double v[2];
*((v2df*)&v[0]) = reg;
v[0] = b;
reg = *((v2df*)&v[0]);
}
void
set_lower1 (double b)
{
reg[0] = b;
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug rtl-optimization/107775] misoptimization in vec_set lower part of vector in the memory.
2022-11-21 2:43 [Bug rtl-optimization/107775] New: misoptimization in vec_set lower part of vector in the memory crazylht at gmail dot com
@ 2022-11-22 8:34 ` rguenth at gcc dot gnu.org
2022-11-22 8:45 ` crazylht at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-11-22 8:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107775
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
misoptimization as in wrong-code or missed-optimization?
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug rtl-optimization/107775] misoptimization in vec_set lower part of vector in the memory.
2022-11-21 2:43 [Bug rtl-optimization/107775] New: misoptimization in vec_set lower part of vector in the memory crazylht at gmail dot com
2022-11-22 8:34 ` [Bug rtl-optimization/107775] " rguenth at gcc dot gnu.org
@ 2022-11-22 8:45 ` crazylht at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: crazylht at gmail dot com @ 2022-11-22 8:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107775
--- Comment #2 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Richard Biener from comment #1)
> misoptimization as in wrong-code or missed-optimization?
missed optimization.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-11-22 8:45 UTC | newest]
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2022-11-21 2:43 [Bug rtl-optimization/107775] New: misoptimization in vec_set lower part of vector in the memory crazylht at gmail dot com
2022-11-22 8:34 ` [Bug rtl-optimization/107775] " rguenth at gcc dot gnu.org
2022-11-22 8:45 ` crazylht at gmail dot com
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