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* [Bug target/98962] New: Perform bitops on floats directly with SSE
@ 2021-02-03 21:06 glisse at gcc dot gnu.org
2021-02-04 8:14 ` [Bug rtl-optimization/98962] " rguenth at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: glisse at gcc dot gnu.org @ 2021-02-03 21:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Bug ID: 98962
Summary: Perform bitops on floats directly with SSE
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: glisse at gcc dot gnu.org
Target Milestone: ---
Target: x86_64-*-*
(from https://stackoverflow.com/q/66023408/1918193 )
float f(float a){
unsigned ai;
__builtin_memcpy(&ai, &a, 4);
unsigned ri = ai ^ (1U << 31);
float r;
__builtin_memcpy(&r, &ri, 4);
return r;
}
results in
movd %xmm0, %eax
addl $-2147483648, %eax
movd %eax, %xmm0
while llvm simplifies it to
xorps .LCPI0_0(%rip), %xmm0
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
@ 2021-02-04 8:14 ` rguenth at gcc dot gnu.org
2021-02-04 10:10 ` jakub at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-02-04 8:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2021-02-04
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Component|target |rtl-optimization
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
So we expand from
_4 = VIEW_CONVERT_EXPR<unsigned int>(a_3(D));
_2 = _4 ^ 2147483648;
_1 = VIEW_CONVERT_EXPR<float>(_2);
return _1;
resulting in
(insn 6 5 7 (parallel [
(set (reg:SI 87)
(xor:SI (subreg:SI (reg/v:SF 85 [ a ]) 0)
(const_int -2147483648 [0xffffffff80000000])))
(clobber (reg:CC 17 flags))
]) "z.c":4:20 -1
(nil))
(insn 7 6 8 (set (reg:SF 84 [ <retval> ])
(subreg:SF (reg:SI 87) 0)) "z.c":7:10 -1
(nil))
initial RTL but CSE1 makes
(insn 6 3 7 2 (parallel [
(set (reg:SI 87)
(plus:SI (subreg:SI (reg/v:SF 85 [ a ]) 0)
(const_int -2147483648 [0xffffffff80000000])))
(clobber (reg:CC 17 flags))
]) "z.c":4:20 209 {*addsi_1}
out of this likely removing the possibility that fwprop or combine elide
the subregs.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
2021-02-04 8:14 ` [Bug rtl-optimization/98962] " rguenth at gcc dot gnu.org
@ 2021-02-04 10:10 ` jakub at gcc dot gnu.org
2021-02-04 10:31 ` jakub at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-02-04 10:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Couldn't e.g. stv do this?
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
2021-02-04 8:14 ` [Bug rtl-optimization/98962] " rguenth at gcc dot gnu.org
2021-02-04 10:10 ` jakub at gcc dot gnu.org
@ 2021-02-04 10:31 ` jakub at gcc dot gnu.org
2021-02-04 12:23 ` ubizjak at gmail dot com
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-02-04 10:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |uros at gcc dot gnu.org
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Another possibility is add x/v constraints to *andsi_1 and *anddi_1 with the
immediates and disparage that alternative enough to reflect the fact that the
immediate will need to be forced into memory.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
` (2 preceding siblings ...)
2021-02-04 10:31 ` jakub at gcc dot gnu.org
@ 2021-02-04 12:23 ` ubizjak at gmail dot com
2021-07-25 1:25 ` pinskia at gcc dot gnu.org
2021-11-28 6:49 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: ubizjak at gmail dot com @ 2021-02-04 12:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #3)
> Another possibility is add x/v constraints to *andsi_1 and *anddi_1 with the
> immediates and disparage that alternative enough to reflect the fact that
> the immediate will need to be forced into memory.
Using this approach we risk that under general reg pressure, RA will start to
allocate XMM registers using gr-xmm reloads also in unwanted cases.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
` (3 preceding siblings ...)
2021-02-04 12:23 ` ubizjak at gmail dot com
@ 2021-07-25 1:25 ` pinskia at gcc dot gnu.org
2021-11-28 6:49 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-07-25 1:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
One thing I noticed is clang just changes f to be -a and optimizes that way.
This was on aarch64.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/98962] Perform bitops on floats directly with SSE
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
` (4 preceding siblings ...)
2021-07-25 1:25 ` pinskia at gcc dot gnu.org
@ 2021-11-28 6:49 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-28 6:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98962
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |the4naves at gmail dot com
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 101311 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-11-28 6:49 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-02-03 21:06 [Bug target/98962] New: Perform bitops on floats directly with SSE glisse at gcc dot gnu.org
2021-02-04 8:14 ` [Bug rtl-optimization/98962] " rguenth at gcc dot gnu.org
2021-02-04 10:10 ` jakub at gcc dot gnu.org
2021-02-04 10:31 ` jakub at gcc dot gnu.org
2021-02-04 12:23 ` ubizjak at gmail dot com
2021-07-25 1:25 ` pinskia at gcc dot gnu.org
2021-11-28 6:49 ` pinskia at gcc dot gnu.org
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