* [Bug optimization/9240] wierd scheduling on v850 unless -fno-sched-spec specified
[not found] <20030109010600.9240.miles@gnu.org>
@ 2003-06-02 4:29 ` pinskia@physics.uc.edu
2003-08-23 1:44 ` [Bug optimization/9240] weird " dhazeghi at yahoo dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 5+ messages in thread
From: pinskia@physics.uc.edu @ 2003-06-02 4:29 UTC (permalink / raw)
To: gcc-bugs
PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9240
pinskia@physics.uc.edu changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2003-06-02 04:29:26
date| |
------- Additional Comments From pinskia@physics.uc.edu 2003-06-02 04:29 -------
Acording to the submitter the problem is still there and looks like -fno-sched-spec fixes
the problem.
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* [Bug optimization/9240] weird scheduling on v850 unless -fno-sched-spec specified
[not found] <20030109010600.9240.miles@gnu.org>
2003-06-02 4:29 ` [Bug optimization/9240] wierd scheduling on v850 unless -fno-sched-spec specified pinskia@physics.uc.edu
@ 2003-08-23 1:44 ` dhazeghi at yahoo dot com
2004-01-15 17:22 ` vmakarov at redhat dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 5+ messages in thread
From: dhazeghi at yahoo dot com @ 2003-08-23 1:44 UTC (permalink / raw)
To: gcc-bugs
PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9240
dhazeghi at yahoo dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|3.4 |---
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug optimization/9240] weird scheduling on v850 unless -fno-sched-spec specified
[not found] <20030109010600.9240.miles@gnu.org>
2003-06-02 4:29 ` [Bug optimization/9240] wierd scheduling on v850 unless -fno-sched-spec specified pinskia@physics.uc.edu
2003-08-23 1:44 ` [Bug optimization/9240] weird " dhazeghi at yahoo dot com
@ 2004-01-15 17:22 ` vmakarov at redhat dot com
2005-09-26 15:22 ` [Bug rtl-optimization/9240] " pinskia at gcc dot gnu dot org
2005-09-26 22:07 ` steinmtz at us dot ibm dot com
4 siblings, 0 replies; 5+ messages in thread
From: vmakarov at redhat dot com @ 2004-01-15 17:22 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From vmakarov at redhat dot com 2004-01-15 17:22 -------
Some analysis:
1. Scheduler uses own algorithm of probablity calculation (3 basic
blocks of the test have probability 100/50/100%).
2. It should use common infrastructure bb frequency and edge
probablility.
3. Even if it used the common infrastructure, bb frequnecies would be
still wrong (10000, 9001, 10000 or 100/90/100%). So builtin-expect
is ignored in the infrastructure too. I saw broken builtin-expect
many times during my 6 years work on gcc.
4. Becuase the probability of the 2nd bb is 50%, it includes 2
insns from it to schedule into the 1st bb.
So fixing the problem could be:
1. Taking builtin_expect into account in scheduler algorithm of
probablity calculation.
2. Start using the common infrastructure bb frequency and edge
probablility and fixing there builtin_expect.
Neither the 1st solution nor the 2nd one is easy. And they include
the risk of new bugs. So I think it is not reasonable to fix it for
3.4. It is a just generation of non-optimal code (scheduler works by
heuristics. there will be always some unoptimal schedules. we are
just oriented to guarantee that scheduler improves code in overall on
credible benchmarks like Spec). The problem was pressent in 3.3.
I'll try to fix the problem in 3-4 months.
Vlad
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |vmakarov at redhat dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9240
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* [Bug rtl-optimization/9240] weird scheduling on v850 unless -fno-sched-spec specified
[not found] <20030109010600.9240.miles@gnu.org>
` (2 preceding siblings ...)
2004-01-15 17:22 ` vmakarov at redhat dot com
@ 2005-09-26 15:22 ` pinskia at gcc dot gnu dot org
2005-09-26 22:07 ` steinmtz at us dot ibm dot com
4 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-09-26 15:22 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-09-26 15:21 -------
I think the patch at
http://gcc.gnu.org/ml/gcc-patches/2005-09/msg00370.html
will fix this.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9240
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/9240] weird scheduling on v850 unless -fno-sched-spec specified
[not found] <20030109010600.9240.miles@gnu.org>
` (3 preceding siblings ...)
2005-09-26 15:22 ` [Bug rtl-optimization/9240] " pinskia at gcc dot gnu dot org
@ 2005-09-26 22:07 ` steinmtz at us dot ibm dot com
4 siblings, 0 replies; 5+ messages in thread
From: steinmtz at us dot ibm dot com @ 2005-09-26 22:07 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From steinmtz at us dot ibm dot com 2005-09-26 22:07 -------
Unless the common infrastructure bb frequency and edge probabilities have been
updated to reflect builtin_expect, http://gcc.gnu.org/ml/gcc-patches/2005-
09/msg00370.html probably won't fix this problem.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9240
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