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* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
[not found] <bug-24073-6528@http.gcc.gnu.org/bugzilla/>
@ 2006-08-23 21:24 ` stuart at apple dot com
2006-08-23 21:54 ` stuart at apple dot com
1 sibling, 0 replies; 10+ messages in thread
From: stuart at apple dot com @ 2006-08-23 21:24 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from stuart at apple dot com 2006-08-23 21:24 -------
Cloned 28825 from this bug to track the MMX instruction issue.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
[not found] <bug-24073-6528@http.gcc.gnu.org/bugzilla/>
2006-08-23 21:24 ` [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good stuart at apple dot com
@ 2006-08-23 21:54 ` stuart at apple dot com
1 sibling, 0 replies; 10+ messages in thread
From: stuart at apple dot com @ 2006-08-23 21:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from stuart at apple dot com 2006-08-23 21:54 -------
Time has passed, and GCC has improved on this testcase. Here is what we
generate today (trunk, 23aug2006) for the original testcase:
movss b(%rip), %xmm0
movss a(%rip), %xmm1
unpcklps %xmm0, %xmm1
movaps %xmm1, %xmm0
xorps %xmm1, %xmm1
movlhps %xmm1, %xmm0
ret
This isn't perfect, but it's much better than before.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread
[parent not found: <bug-24073-4@http.gcc.gnu.org/bugzilla/>]
* [Bug target/24073] New: (vector float){a, b, 0, 0} code gen is not good
@ 2005-09-27 4:06 pinskia at gcc dot gnu dot org
2005-09-27 4:06 ` [Bug target/24073] " pinskia at gcc dot gnu dot org
` (6 more replies)
0 siblings, 7 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-27 4:06 UTC (permalink / raw)
To: gcc-bugs
Take the following example:
#define vector __attribute__((vector_size(16)))
float a; float b;
vector float f(void) { return (vector float){ a, b, 0.0, 0.0}; }
---
Currently we get:
subl $12, %esp
movss _b, %xmm0
movss _a, %xmm1
unpcklps %xmm0, %xmm1
movaps %xmm1, %xmm0
xorl %eax, %eax
xorl %edx, %edx
movl %eax, (%esp)
movl %edx, 4(%esp)
xorps %xmm1, %xmm1
movlhps %xmm1, %xmm0
addl $12, %esp
------
We should be able to produce:
movss _b, %xmm0
movss _a, %xmm1
shufps 60, /*[0, 3, 3, 0]*/, %xmm1, %xmm0 // _a, 0, 0, _b
shufps 201, /*[3, 0, 2, 1]*/, %xmm0, %xmm0 // _a, _b, 0, 0
This is from Nathan Begeman.
--
Summary: (vector float){a, b, 0, 0} code gen is not good
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: minor
Priority: P2
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pinskia at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
@ 2005-09-27 4:06 ` pinskia at gcc dot gnu dot org
2005-09-27 4:22 ` pinskia at gcc dot gnu dot org
` (5 subsequent siblings)
6 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-27 4:06 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |ssemmx
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
2005-09-27 4:06 ` [Bug target/24073] " pinskia at gcc dot gnu dot org
@ 2005-09-27 4:22 ` pinskia at gcc dot gnu dot org
2005-09-27 5:09 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
6 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-27 4:22 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
GCC target triplet| |i786-pc-darwin7.9
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
2005-09-27 4:06 ` [Bug target/24073] " pinskia at gcc dot gnu dot org
2005-09-27 4:22 ` pinskia at gcc dot gnu dot org
@ 2005-09-27 5:09 ` pinskia at gcc dot gnu dot org
2005-09-27 5:51 ` belyshev at depni dot sinp dot msu dot ru
` (3 subsequent siblings)
6 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-27 5:09 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-09-27 05:07 -------
The issue is in ix86_expand_vector_init.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
` (2 preceding siblings ...)
2005-09-27 5:09 ` pinskia at gcc dot gnu dot org
@ 2005-09-27 5:51 ` belyshev at depni dot sinp dot msu dot ru
2005-09-27 11:19 ` uros at kss-loka dot si
` (2 subsequent siblings)
6 siblings, 0 replies; 10+ messages in thread
From: belyshev at depni dot sinp dot msu dot ru @ 2005-09-27 5:51 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From belyshev at depni dot sinp dot msu dot ru 2005-09-27 05:51 -------
Confirmed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2005-09-27 05:51:20
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
` (3 preceding siblings ...)
2005-09-27 5:51 ` belyshev at depni dot sinp dot msu dot ru
@ 2005-09-27 11:19 ` uros at kss-loka dot si
2005-09-27 11:41 ` uros at kss-loka dot si
2005-09-27 14:34 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 10+ messages in thread
From: uros at kss-loka dot si @ 2005-09-27 11:19 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From uros at kss-loka dot si 2005-09-27 11:19 -------
With a couple of months old mainline gcc (20050716), following asm is produced:
(-O2 -msse2 -fomit-frame-pointer):
subl $12, %esp
movss b, %xmm0
movss a, %xmm1
unpcklps %xmm0, %xmm1
movaps %xmm1, %xmm0
xorl %eax, %eax
xorl %edx, %edx
movl %eax, (%esp)
movl %edx, 4(%esp)
>>> movlps (%esp), %xmm1
addl $12, %esp
movlhps %xmm1, %xmm0
ret
This explains where all those xor and moves come from. It looks that newer
compilers somehow fix the damage by using xorps, a bit late in the game, IMO.
This part of bug depends on PR target/22076.
Other than that, the problem is that V4SF vector initialization is decomposed
to two V2SF initializations (these are MMX insns and this further confuses
x87/MMX switching patch) that are later concated to V4SF.
--
What |Removed |Added
----------------------------------------------------------------------------
BugsThisDependsOn| |22076
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
` (4 preceding siblings ...)
2005-09-27 11:19 ` uros at kss-loka dot si
@ 2005-09-27 11:41 ` uros at kss-loka dot si
2005-09-27 14:34 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 10+ messages in thread
From: uros at kss-loka dot si @ 2005-09-27 11:41 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From uros at kss-loka dot si 2005-09-27 11:41 -------
I think that following example wins the contest:
vector float f(void) { return (vector float){ a, a, b, b}; }
gcc -O2 -msse -fomit-frame-pointer
subl $28, %esp
movss a, %xmm0
movss %xmm0, 4(%esp)
movss b, %xmm0
movd 4(%esp), %mm0
punpckldq %mm0, %mm0
movss %xmm0, 4(%esp)
movq %mm0, 16(%esp)
movd 4(%esp), %mm0
punpckldq %mm0, %mm0
movq %mm0, 8(%esp)
movlps 16(%esp), %xmm1
movhps 8(%esp), %xmm1
addl $28, %esp
movaps %xmm1, %xmm0
ret
Note the usage of MMX registers.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread* [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
` (5 preceding siblings ...)
2005-09-27 11:41 ` uros at kss-loka dot si
@ 2005-09-27 14:34 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-27 14:34 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-09-27 14:33 -------
(In reply to comment #4)
> I think that following example wins the contest:
>
> vector float f(void) { return (vector float){ a, a, b, b}; }
For this, it is a different bug. The issue with the above is that ix86_expand_vector_init_duplicate check
for mmx_okay is bad.
Currently, we have
if (!mmx_ok && !TARGET_SSE)
but I if I change it to:
if (!mmx_ok)
we get:
movss _a, %xmm0
movss _b, %xmm1
unpcklps %xmm0, %xmm0
unpcklps %xmm1, %xmm1
movlhps %xmm1, %xmm0
Which looks ok to me. That testcase should be opened into another bug as it is obviously wrong.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24073
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-08-21 21:28 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <bug-24073-6528@http.gcc.gnu.org/bugzilla/>
2006-08-23 21:24 ` [Bug target/24073] (vector float){a, b, 0, 0} code gen is not good stuart at apple dot com
2006-08-23 21:54 ` stuart at apple dot com
[not found] <bug-24073-4@http.gcc.gnu.org/bugzilla/>
2021-08-21 21:28 ` pinskia at gcc dot gnu.org
2005-09-27 4:06 [Bug target/24073] New: " pinskia at gcc dot gnu dot org
2005-09-27 4:06 ` [Bug target/24073] " pinskia at gcc dot gnu dot org
2005-09-27 4:22 ` pinskia at gcc dot gnu dot org
2005-09-27 5:09 ` pinskia at gcc dot gnu dot org
2005-09-27 5:51 ` belyshev at depni dot sinp dot msu dot ru
2005-09-27 11:19 ` uros at kss-loka dot si
2005-09-27 11:41 ` uros at kss-loka dot si
2005-09-27 14:34 ` pinskia at gcc dot gnu dot org
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