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* [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop
@ 2007-02-26 13:35 ubizjak at gmail dot com
2007-02-26 15:48 ` [Bug target/30970] " ubizjak at gmail dot com
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: ubizjak at gmail dot com @ 2007-02-26 13:35 UTC (permalink / raw)
To: gcc-bugs
The testcase:
--cut here--
#define N 256
int b[N];
void test()
{
int i;
for (i = 0; i < N; i++)
b[i] = 0;
}
--cut here--
compiles with '-O2 -msse2 -ftree-vectorize' into:
test:
movl $16, %eax
pxor %xmm0, %xmm0
movdqa %xmm0, b
.p2align 4,,7
.L2:
pxor %xmm0, %xmm0
movdqa %xmm0, b(%eax)
addl $16, %eax
cmpl $1024, %eax
jne .L2
rep ; ret
Please note second pxor that is _not_ needed. Also, it should be moved out of
loop as it is loop invariant.
For slightly different testcase, where 'b[i] = 1' (or anything != 0) we get
optimized code:
test:
movl $16, %eax
movdqa .LC0, %xmm0
movdqa %xmm0, b
.p2align 4,,7
.L2:
movdqa %xmm0, b(%eax)
addl $16, %eax
cmpl $1024, %eax
jne .L2
rep ; ret
It looks like (g)cse doesn't know what 'xor N,N' means.
--
Summary: Register zeroing by xor N,N should be moved out of loop
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: ubizjak at gmail dot com
GCC host triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
@ 2007-02-26 15:48 ` ubizjak at gmail dot com
2007-02-26 17:35 ` rguenth at gcc dot gnu dot org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: ubizjak at gmail dot com @ 2007-02-26 15:48 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from ubizjak at gmail dot com 2007-02-26 15:48 -------
It is a target issue. Working on a fix.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |ubizjak at gmail dot com
|dot org |
Severity|normal |minor
Status|UNCONFIRMED |ASSIGNED
Component|rtl-optimization |target
Ever Confirmed|0 |1
GCC target triplet| |i686-pc-linux-gnu
Keywords| |ssemmx
Last reconfirmed|0000-00-00 00:00:00 |2007-02-26 15:48:01
date| |
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
2007-02-26 15:48 ` [Bug target/30970] " ubizjak at gmail dot com
@ 2007-02-26 17:35 ` rguenth at gcc dot gnu dot org
2007-02-26 17:54 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2007-02-26 17:35 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2007-02-26 17:35 -------
Shouldn't rtl invariant motion catch this?
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rakdver at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
2007-02-26 15:48 ` [Bug target/30970] " ubizjak at gmail dot com
2007-02-26 17:35 ` rguenth at gcc dot gnu dot org
@ 2007-02-26 17:54 ` pinskia at gcc dot gnu dot org
2007-02-26 19:51 ` ubizjak at gmail dot com
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-02-26 17:54 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.3.0 |---
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
` (2 preceding siblings ...)
2007-02-26 17:54 ` pinskia at gcc dot gnu dot org
@ 2007-02-26 19:51 ` ubizjak at gmail dot com
2007-02-27 21:27 ` uros at gcc dot gnu dot org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: ubizjak at gmail dot com @ 2007-02-26 19:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from ubizjak at gmail dot com 2007-02-26 19:51 -------
(In reply to comment #2)
> Shouldn't rtl invariant motion catch this?
It would be nice, but the problem is again in the fact that we lie to the
compiler about supported instructions. This one is not a valid x86 insn:
(insn 12 8 13 2 (set (mem:V4SI (symbol_ref:DI ("b") <var_decl 0x2aaaae15b000
b>) [3 S16 A128])
(const_vector:V4SI [
(const_int 0 [0x0])
(const_int 0 [0x0])
(const_int 0 [0x0])
(const_int 0 [0x0])
])) 919 {*movv4si_internal} (nil)
(nil))
This sequence is later split into pxor+store, unfortunatelly a bit late in the
game, after RTL optimizers have already done their job.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
` (3 preceding siblings ...)
2007-02-26 19:51 ` ubizjak at gmail dot com
@ 2007-02-27 21:27 ` uros at gcc dot gnu dot org
2007-03-02 14:54 ` ubizjak at gmail dot com
2007-03-02 18:37 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: uros at gcc dot gnu dot org @ 2007-02-27 21:27 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from uros at gcc dot gnu dot org 2007-02-27 21:27 -------
Subject: Bug 30970
Author: uros
Date: Tue Feb 27 21:27:27 2007
New Revision: 122387
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=122387
Log:
PR target/30970
* config/i386/sse.md (*mov<mode>_internal, *movv4sf_internal,
*movv2df_internal): Enable pattern only for valid operand
combinations.
* config/i386/i386.c (ix86_modes_tieable_p): For SSE registers,
tie only 128bit modes. For MMX registers, tie only 64bit modes.
testsuite/ChangeLog:
PR target/30970
* gcc.target/i386/gfortran.dg/pr30970.c: New test.
Added:
trunk/gcc/testsuite/gcc.target/i386/pr30970.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/i386/i386.c
trunk/gcc/config/i386/sse.md
trunk/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
` (4 preceding siblings ...)
2007-02-27 21:27 ` uros at gcc dot gnu dot org
@ 2007-03-02 14:54 ` ubizjak at gmail dot com
2007-03-02 18:37 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: ubizjak at gmail dot com @ 2007-03-02 14:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from ubizjak at gmail dot com 2007-03-02 14:54 -------
Fixed in mainline.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/30970] Register zeroing by xor N,N should be moved out of loop
2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
` (5 preceding siblings ...)
2007-03-02 14:54 ` ubizjak at gmail dot com
@ 2007-03-02 18:37 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-03-02 18:37 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30970
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2007-03-02 18:37 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2007-02-26 13:35 [Bug rtl-optimization/30970] New: Register zeroing by xor N,N should be moved out of loop ubizjak at gmail dot com
2007-02-26 15:48 ` [Bug target/30970] " ubizjak at gmail dot com
2007-02-26 17:35 ` rguenth at gcc dot gnu dot org
2007-02-26 17:54 ` pinskia at gcc dot gnu dot org
2007-02-26 19:51 ` ubizjak at gmail dot com
2007-02-27 21:27 ` uros at gcc dot gnu dot org
2007-03-02 14:54 ` ubizjak at gmail dot com
2007-03-02 18:37 ` pinskia at gcc dot gnu dot org
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