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* [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6
@ 2010-12-14 14:31 jakub at gcc dot gnu.org
2010-12-15 12:24 ` [Bug ada/46939] " hubicka at gcc dot gnu.org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: jakub at gcc dot gnu.org @ 2010-12-14 14:31 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
Summary: http://blog.regehr.org/archives/320 example 6
Product: gcc
Version: 4.6.0
URL: http://blog.regehr.org/archives/320
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: jakub@gcc.gnu.org
CC: hubicka@gcc.gnu.org
The reason we don't expand / 10 using a multiplication is because gcc thinks it
happens in cold code.
In *.optimized we have:
# BLOCK 5 freq:9999
# PRED: 4 [100.0%] (fallthru,exec) 2 [33.3%] (exec)
# PT = nonlocal
# strD.1584_1 = PHI <strD.1584_17(4), strD.1584_12(D)(2)>
# signD.1590_5 = PHI <signD.1590_4(4), 0(2)>
<L39>:
str.0D.2703_18 = (long unsigned intD.4) strD.1584_1;
end.1D.2704_19 = (long unsigned intD.4) endD.1592_13;
if (str.0D.2703_18 < end.1D.2704_19)
goto <bb 6>;
else
goto <bb 22>;
# SUCC: 6 [4.0%] (true,exec) 22 [96.0%] (false,exec)
# BLOCK 6 freq:400
# PRED: 5 [4.0%] (true,exec)
# VUSE <.MEMD.2753_65(D)>
D.2701_20 = *strD.1584_1;
if (D.2701_20 > 48)
goto <bb 7>;
else
goto <bb 22>;
# SUCC: 7 [4.0%] (true,exec) 22 [96.0%] (false,exec)
# BLOCK 7 freq:16
# PRED: 6 [4.0%] (true,exec)
if (D.2701_20 <= 57)
goto <bb 8>;
else
goto <bb 22>;
# SUCC: 8 [4.0%] (true,exec) 22 [96.0%] (false,exec)
...
# BLOCK 15 freq:6
# PRED: 14 [96.0%] (true,exec)
D.2735_44 = (long intD.2) digitD.1591_43;
D.2736_45 = 9223372036854775807 - D.2735_44;
D.2737_46 = D.2736_45 / 10;
if (ctx_valueD.1589_3 <= D.2737_46)
goto <bb 16>;
else
goto <bb 22>;
# SUCC: 16 [96.0%] (true,exec) 22 [4.0%] (false,exec)
while ((unsigned long) str < (unsigned long) end) is a loop, not sure why we
predict the loop header to terminate immediately, and both the >= 48 and <= 57
tests have return -1; in the other branch, so it is also strange to see them
predicted so unlikely. Honza?
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug ada/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
@ 2010-12-15 12:24 ` hubicka at gcc dot gnu.org
2010-12-15 12:54 ` hubicka at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: hubicka at gcc dot gnu.org @ 2010-12-15 12:24 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
Jan Hubicka <hubicka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2010.12.15 12:24:34
Ever Confirmed|0 |1
--- Comment #1 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-15 12:24:34 UTC ---
Predictions for bb 6
DS theory heuristics: 4.0%
first match heuristics (ignored): 4.0%
combined heuristics: 4.0%
negative return heuristics: 4.0%
So it is negative return heuristics.
Richi's profiling reorg broke statistics code, so I will need to dig into
archives before I fix it again. But last time I updated the tables the
heuristics was 96% right on SPEC. I am not terribly oposed in making it less
reliable with a comment explaining why. In SPEC it is most surely perfoming
heuristics, we have only few of them above 60%
The heuristics makes a guess that negative return values tends to be used to
return error stages. It is not true in this case.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug ada/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
2010-12-15 12:24 ` [Bug ada/46939] " hubicka at gcc dot gnu.org
@ 2010-12-15 12:54 ` hubicka at gcc dot gnu.org
2010-12-15 13:29 ` hubicka at gcc dot gnu.org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: hubicka at gcc dot gnu.org @ 2010-12-15 12:54 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
Jan Hubicka <hubicka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
--- Comment #2 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-15 12:54:10 UTC ---
As observed by Jakub, it is actually bug in the return heuristics
implementation. Will make patch shortly.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug ada/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
2010-12-15 12:24 ` [Bug ada/46939] " hubicka at gcc dot gnu.org
2010-12-15 12:54 ` hubicka at gcc dot gnu.org
@ 2010-12-15 13:29 ` hubicka at gcc dot gnu.org
2010-12-16 1:27 ` [Bug tree-optimization/46939] " hubicka at gcc dot gnu.org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: hubicka at gcc dot gnu.org @ 2010-12-15 13:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
--- Comment #3 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-15 13:28:56 UTC ---
Created attachment 22763
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22763
patch I am testing
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
` (2 preceding siblings ...)
2010-12-15 13:29 ` hubicka at gcc dot gnu.org
@ 2010-12-16 1:27 ` hubicka at gcc dot gnu.org
2010-12-16 1:40 ` hubicka at gcc dot gnu.org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: hubicka at gcc dot gnu.org @ 2010-12-16 1:27 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
--- Comment #4 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-16 01:27:25 UTC ---
Author: hubicka
Date: Thu Dec 16 01:27:23 2010
New Revision: 167893
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=167893
Log:
PR middle-end/46939
* predic.c (predict_paths_leading_to_edge): New function.
(apply_return_prediction): Use it.
(predict_paths_for_bb): Do not special case abnormals.
* gcc.target/i386/pr46939.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.target/i386/pr46939.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/predict.c
trunk/gcc/testsuite/ChangeLog
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
` (3 preceding siblings ...)
2010-12-16 1:27 ` [Bug tree-optimization/46939] " hubicka at gcc dot gnu.org
@ 2010-12-16 1:40 ` hubicka at gcc dot gnu.org
2010-12-16 9:26 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: hubicka at gcc dot gnu.org @ 2010-12-16 1:40 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
--- Comment #5 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-16 01:40:29 UTC ---
the idiv issue is fixed now. It would be nice to compare if the function now
has same speed as the other compilers.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
` (4 preceding siblings ...)
2010-12-16 1:40 ` hubicka at gcc dot gnu.org
@ 2010-12-16 9:26 ` jakub at gcc dot gnu.org
2010-12-16 15:11 ` regehr at cs dot utah.edu
2010-12-17 17:11 ` regehr at cs dot utah.edu
7 siblings, 0 replies; 9+ messages in thread
From: jakub at gcc dot gnu.org @ 2010-12-16 9:26 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-12-16 09:26:35 UTC ---
Fixed.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
` (5 preceding siblings ...)
2010-12-16 9:26 ` jakub at gcc dot gnu.org
@ 2010-12-16 15:11 ` regehr at cs dot utah.edu
2010-12-17 17:11 ` regehr at cs dot utah.edu
7 siblings, 0 replies; 9+ messages in thread
From: regehr at cs dot utah.edu @ 2010-12-16 15:11 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
--- Comment #7 from John Regehr <regehr at cs dot utah.edu> 2010-12-16 15:10:41 UTC ---
(In reply to comment #6)
> Fixed.
Awesome. We will re-test this code.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/46939] http://blog.regehr.org/archives/320 example 6
2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
` (6 preceding siblings ...)
2010-12-16 15:11 ` regehr at cs dot utah.edu
@ 2010-12-17 17:11 ` regehr at cs dot utah.edu
7 siblings, 0 replies; 9+ messages in thread
From: regehr at cs dot utah.edu @ 2010-12-17 17:11 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
--- Comment #8 from John Regehr <regehr at cs dot utah.edu> 2010-12-17 17:11:05 UTC ---
Here is the current performance that we measure, in cycles:
gcc-head: 43
icc: 41
clang-head: 41
suncc: 42
^ permalink raw reply [flat|nested] 9+ messages in thread
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2010-12-14 14:31 [Bug ada/46939] New: http://blog.regehr.org/archives/320 example 6 jakub at gcc dot gnu.org
2010-12-15 12:24 ` [Bug ada/46939] " hubicka at gcc dot gnu.org
2010-12-15 12:54 ` hubicka at gcc dot gnu.org
2010-12-15 13:29 ` hubicka at gcc dot gnu.org
2010-12-16 1:27 ` [Bug tree-optimization/46939] " hubicka at gcc dot gnu.org
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