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* [Bug middle-end/30801] 4.3 performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
@ 2007-02-14 23:21 ` fxcoudert at gcc dot gnu dot org
2007-02-14 23:26 ` [Bug target/30801] " pinskia at gcc dot gnu dot org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu dot org @ 2007-02-14 23:21 UTC (permalink / raw)
To: gcc-bugs
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-02-14 23:21:03
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations
@ 2007-02-14 23:21 fxcoudert at gcc dot gnu dot org
2007-02-14 23:21 ` [Bug middle-end/30801] " fxcoudert at gcc dot gnu dot org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu dot org @ 2007-02-14 23:21 UTC (permalink / raw)
To: gcc-bugs
I noticed a performance regression on the following code:
$ cat a.c
#include <stdint.h>
#include <stdio.h>
void
add256 (uint64_t x[4], const uint64_t y[4])
{
unsigned char carry;
x[0] += y[0];
carry = (x[0] < y[0]);
x[1] += y[1]+carry;
carry = carry ? (x[1] <= y[1]) : (x[1] < y[1]);
x[2] += y[2]+carry;
carry = carry ? (x[2] <= y[2]) : (x[2] < y[2]);
x[3] += y[3]+carry;
}
int
main (void)
{
int i;
uint64_t x[4], y[4];
x[0] = 0; x[1] = 0; x[2] = 0; x[3] = 0;
y[0] = 0x0123456789abcdefULL;
y[1] = 0xfedcba9876543210ULL;
y[2] = 0xdeadbeeff001baadULL;
y[3] = 0x001001001001ffffULL;
for ( i=0 ; i<100000000 ; i++ )
add256 (x, y);
printf ("%016llx%016llx%016llx%016llx\n",
(unsigned long long)x[3],
(unsigned long long)x[2],
(unsigned long long)x[1],
(unsigned long long)x[0]);
return 0;
}
$ gcc -march=pentium4 -O3 a.c && time ./a.out
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
./a.out 1.81s user 0.00s system 99% cpu 1.818 total
$ gcc-4.3 -march=pentium4 -O3 a.c && time ./a.out
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
./a.out 2.40s user 0.01s system 87% cpu 2.746 total
where gcc is gcc version 4.1.1 20070105 (Red Hat 4.1.1-51) and gcc-4.3
is gcc version 4.3.0 20070209 (experimental).
Pawel Sikora confirmed he's seeing the same kind of regression between 4.2 and
4.3 (http://gcc.gnu.org/ml/gcc/2007-02/msg00319.html)
--
Summary: 4.3 performance regression on uint64_t operations
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: fxcoudert at gcc dot gnu dot org
GCC build triplet: x86_64-pc-linux-gnu
GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] 4.3 performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
2007-02-14 23:21 ` [Bug middle-end/30801] " fxcoudert at gcc dot gnu dot org
@ 2007-02-14 23:26 ` pinskia at gcc dot gnu dot org
2007-02-14 23:26 ` pinskia at gcc dot gnu dot org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-02-14 23:26 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2007-02-14 23:26 -------
This was NOT caused by the lowering pass at all
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|middle-end |target
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] 4.3 performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
2007-02-14 23:21 ` [Bug middle-end/30801] " fxcoudert at gcc dot gnu dot org
2007-02-14 23:26 ` [Bug target/30801] " pinskia at gcc dot gnu dot org
@ 2007-02-14 23:26 ` pinskia at gcc dot gnu dot org
2007-09-11 11:52 ` [Bug target/30801] [4.3 Regression] " jsm28 at gcc dot gnu dot org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-02-14 23:26 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from pinskia at gcc dot gnu dot org 2007-02-14 23:26 -------
(In reply to comment #1)
> This was NOT caused by the lowering pass at all.
^
subreg
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] [4.3 Regression] performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
` (2 preceding siblings ...)
2007-02-14 23:26 ` pinskia at gcc dot gnu dot org
@ 2007-09-11 11:52 ` jsm28 at gcc dot gnu dot org
2007-10-10 17:44 ` mmitchel at gcc dot gnu dot org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu dot org @ 2007-09-11 11:52 UTC (permalink / raw)
To: gcc-bugs
--
jsm28 at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|4.3 performance regression |[4.3 Regression] performance
|on uint64_t operations |regression on uint64_t
| |operations
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] [4.3 Regression] performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
` (3 preceding siblings ...)
2007-09-11 11:52 ` [Bug target/30801] [4.3 Regression] " jsm28 at gcc dot gnu dot org
@ 2007-10-10 17:44 ` mmitchel at gcc dot gnu dot org
2007-10-25 18:58 ` rask at gcc dot gnu dot org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: mmitchel at gcc dot gnu dot org @ 2007-10-10 17:44 UTC (permalink / raw)
To: gcc-bugs
--
mmitchel at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] [4.3 Regression] performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
` (4 preceding siblings ...)
2007-10-10 17:44 ` mmitchel at gcc dot gnu dot org
@ 2007-10-25 18:58 ` rask at gcc dot gnu dot org
2007-11-07 16:35 ` rask at gcc dot gnu dot org
2007-11-07 16:49 ` fxcoudert at gcc dot gnu dot org
7 siblings, 0 replies; 9+ messages in thread
From: rask at gcc dot gnu dot org @ 2007-10-25 18:58 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rask at gcc dot gnu dot org 2007-10-25 18:58 -------
I see a substantial improvent when testing on the compile farm hardware:
processor : 3
vendor_id : AuthenticAMD
cpu family : 15
model : 65
model name : Dual-Core AMD Opteron(tm) Processor 2212
stepping : 3
cpu MHz : 2000.240
cache size : 1024 KB
...
$ gcc --version | head -n 1
gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
$ gcc -O3 ~/pr30801.c && time ./a.out
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
real 0m0.555s
user 0m0.552s
sys 0m0.004s
$ (cd ~/build/gcc-x86_64-unknown-linux-gnu/gcc && ./xgcc --version | head -n 1)
xgcc (GCC) 4.3.0 20071022 (experimental)
$ (cd ~/build/gcc-x86_64-unknown-linux-gnu/gcc && ./xgcc -B./ -O3 ~/pr30801.c
&& time ./a.out)
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
real 0m0.455s
user 0m0.452s
sys 0m0.004s
Note that your -march=pentium4 option is rejected without -m32:
$ gcc -march=pentium4 -O3 ~/pr30801.c && time ./a.out
/home/rask/pr30801.c:1: error: CPU you selected does not support x86-64
instruction set
/home/rask/pr30801.c:1: error: CPU you selected does not support x86-64
instruction set
$ gcc -O3 ~/pr30801.c -m32 -march=pentium4 && time ./a.out
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
real 0m2.234s
user 0m2.232s
sys 0m0.004s
$ (cd ~/build/gcc-x86_64-unknown-linux-gnu/gcc && ./xgcc -B./ -O3 ~/pr30801.c
-m32 -march=pentium4 && time ./a.out)
064069fbc13963b920219c3e939225e38e38e38e3956d81c71c71c71c0ba0f00
real 0m1.488s
user 0m1.484s
sys 0m0.004s
So GCC 4.3 is 22 % faster with just the default -m64 + no -march and an
impressive 50 % faster with -m32 -march=pentium4.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] [4.3 Regression] performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
` (5 preceding siblings ...)
2007-10-25 18:58 ` rask at gcc dot gnu dot org
@ 2007-11-07 16:35 ` rask at gcc dot gnu dot org
2007-11-07 16:49 ` fxcoudert at gcc dot gnu dot org
7 siblings, 0 replies; 9+ messages in thread
From: rask at gcc dot gnu dot org @ 2007-11-07 16:35 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rask at gcc dot gnu dot org 2007-11-07 16:35 -------
Francois-Xavier, do you still see a performance regression? If so, please post
asm output (-S -dp) from both versions?
--
rask at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rask at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/30801] [4.3 Regression] performance regression on uint64_t operations
2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
` (6 preceding siblings ...)
2007-11-07 16:35 ` rask at gcc dot gnu dot org
@ 2007-11-07 16:49 ` fxcoudert at gcc dot gnu dot org
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu dot org @ 2007-11-07 16:49 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from fxcoudert at gcc dot gnu dot org 2007-11-07 16:49 -------
No, I don't see it any more.
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30801
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2007-11-07 16:49 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
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2007-02-14 23:21 [Bug middle-end/30801] New: 4.3 performance regression on uint64_t operations fxcoudert at gcc dot gnu dot org
2007-02-14 23:21 ` [Bug middle-end/30801] " fxcoudert at gcc dot gnu dot org
2007-02-14 23:26 ` [Bug target/30801] " pinskia at gcc dot gnu dot org
2007-02-14 23:26 ` pinskia at gcc dot gnu dot org
2007-09-11 11:52 ` [Bug target/30801] [4.3 Regression] " jsm28 at gcc dot gnu dot org
2007-10-10 17:44 ` mmitchel at gcc dot gnu dot org
2007-10-25 18:58 ` rask at gcc dot gnu dot org
2007-11-07 16:35 ` rask at gcc dot gnu dot org
2007-11-07 16:49 ` fxcoudert at gcc dot gnu dot org
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