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* [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277
@ 2009-06-09 10:23 hjl dot tools at gmail dot com
2009-06-09 10:24 ` [Bug middle-end/40384] " hjl dot tools at gmail dot com
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-09 10:23 UTC (permalink / raw)
To: gcc-bugs
Revision 148277:
http://gcc.gnu.org/ml/gcc-cvs/2009-06/msg00257.html
caused:
http://gcc.gnu.org/ml/gcc-cvs/2009-06/msg00257.html
We no longer generate prefetch.
--
Summary: [4.5 regression] Revision 148277 failed 148277
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: hjl dot tools at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug middle-end/40384] [4.5 regression] Revision 148277 failed 148277
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
@ 2009-06-09 10:24 ` hjl dot tools at gmail dot com
2009-06-09 14:19 ` [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c rguenth at gcc dot gnu dot org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-09 10:24 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from hjl dot tools at gmail dot com 2009-06-09 10:24 -------
Caused:
FAIL: gcc.dg/tree-ssa/prefetch-5.c scan-tree-dump-times aprefetch "Issued
prefetch" 2
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
2009-06-09 10:24 ` [Bug middle-end/40384] " hjl dot tools at gmail dot com
@ 2009-06-09 14:19 ` rguenth at gcc dot gnu dot org
2009-06-09 22:37 ` gshobaki at gcc dot gnu dot org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2009-06-09 14:19 UTC (permalink / raw)
To: gcc-bugs
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|middle-end |tree-optimization
Target Milestone|--- |4.5.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
2009-06-09 10:24 ` [Bug middle-end/40384] " hjl dot tools at gmail dot com
2009-06-09 14:19 ` [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c rguenth at gcc dot gnu dot org
@ 2009-06-09 22:37 ` gshobaki at gcc dot gnu dot org
2009-06-10 20:15 ` hjl dot tools at gmail dot com
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: gshobaki at gcc dot gnu dot org @ 2009-06-09 22:37 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from gshobaki at gcc dot gnu dot org 2009-06-09 22:37 -------
The new cost model added in revision 148277 supresses prefetching in a loop
when it is unlikely to be profitable. One such non-profitable case is a loop
with an unknown trip count and a high prefeching cost. The prefetching cost is
modeled by the ratio between the prefetch count and the total instruction count
in a loop. When this ratio is greater than 1/10 in a loop with an unknown trip
count, prefetching is considered non-profitable and no prefetches are issued.
The first two loops in this test case fall under this category, where the trip
count is not known and the prefetch-to-insn ratio is 1/5. Possible fixes are:
1. Add more computation to the loop bodies in the test case to reduce the
prefetch-to-insn ratios and hence make the loops profitable from the cost
model's point of view.
2. Use a commad line option to set the maximum profitable prefetch-to-insn
ratio to 1/5. The syntax is --param min-insn-to-prefetch-ratio=5
3. Change the expected output such that it does not expect prefetches in this
case.
Any feedback on which one is the preferred solution?
Thanks
-Ghassan
--
gshobaki at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |gshobaki at gcc dot gnu dot
| |org
Status|UNCONFIRMED |WAITING
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (2 preceding siblings ...)
2009-06-09 22:37 ` gshobaki at gcc dot gnu dot org
@ 2009-06-10 20:15 ` hjl dot tools at gmail dot com
2009-06-12 5:00 ` hjl dot tools at gmail dot com
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-10 20:15 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from hjl dot tools at gmail dot com 2009-06-10 20:14 -------
(In reply to comment #2)
> The new cost model added in revision 148277 supresses prefetching in a loop
> when it is unlikely to be profitable. One such non-profitable case is a loop
> with an unknown trip count and a high prefeching cost. The prefetching cost is
> modeled by the ratio between the prefetch count and the total instruction count
> in a loop. When this ratio is greater than 1/10 in a loop with an unknown trip
> count, prefetching is considered non-profitable and no prefetches are issued.
> The first two loops in this test case fall under this category, where the trip
> count is not known and the prefetch-to-insn ratio is 1/5. Possible fixes are:
>
> 1. Add more computation to the loop bodies in the test case to reduce the
> prefetch-to-insn ratios and hence make the loops profitable from the cost
> model's point of view.
> 2. Use a commad line option to set the maximum profitable prefetch-to-insn
> ratio to 1/5. The syntax is --param min-insn-to-prefetch-ratio=5
> 3. Change the expected output such that it does not expect prefetches in this
> case.
>
I prefer #2 since this is a prefetch test.
--
hjl dot tools at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |hjl dot tools at gmail dot
| |com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (3 preceding siblings ...)
2009-06-10 20:15 ` hjl dot tools at gmail dot com
@ 2009-06-12 5:00 ` hjl dot tools at gmail dot com
2009-06-12 13:16 ` [Bug testsuite/40384] " hjl dot tools at gmail dot com
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-12 5:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from hjl dot tools at gmail dot com 2009-06-12 05:00 -------
Adding --param min-insn-to-prefetch-ratio=5 works.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug testsuite/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (4 preceding siblings ...)
2009-06-12 5:00 ` hjl dot tools at gmail dot com
@ 2009-06-12 13:16 ` hjl dot tools at gmail dot com
2009-06-12 13:24 ` hjl dot tools at gmail dot com
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-12 13:16 UTC (permalink / raw)
To: gcc-bugs
--
hjl dot tools at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Ever Confirmed|0 |1
Last reconfirmed|2009-06-12 13:15:49 |2009-06-12 13:16:00
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug testsuite/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (5 preceding siblings ...)
2009-06-12 13:16 ` [Bug testsuite/40384] " hjl dot tools at gmail dot com
@ 2009-06-12 13:24 ` hjl dot tools at gmail dot com
2009-06-12 13:38 ` hjl at gcc dot gnu dot org
2009-06-13 0:09 ` hjl dot tools at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-12 13:24 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from hjl dot tools at gmail dot com 2009-06-12 13:24 -------
A patch is posted at
http://gcc.gnu.org/ml/gcc-patches/2009-06/msg00964.html
--
hjl dot tools at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
URL| |http://gcc.gnu.org/ml/gcc-
| |patches/2009-
| |06/msg00964.html
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug testsuite/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (6 preceding siblings ...)
2009-06-12 13:24 ` hjl dot tools at gmail dot com
@ 2009-06-12 13:38 ` hjl at gcc dot gnu dot org
2009-06-13 0:09 ` hjl dot tools at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: hjl at gcc dot gnu dot org @ 2009-06-12 13:38 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from hjl at gcc dot gnu dot org 2009-06-12 13:38 -------
Subject: Bug 40384
Author: hjl
Date: Fri Jun 12 13:37:50 2009
New Revision: 148431
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=148431
Log:
2009-06-12 H.J. Lu <hongjiu.lu@intel.com>
PR testsuite/40384
* gcc.dg/tree-ssa/prefetch-5.c: Add --param
min-insn-to-prefetch-ratio=5.
Modified:
trunk/gcc/testsuite/ChangeLog
trunk/gcc/testsuite/gcc.dg/tree-ssa/prefetch-5.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug testsuite/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c
2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
` (7 preceding siblings ...)
2009-06-12 13:38 ` hjl at gcc dot gnu dot org
@ 2009-06-13 0:09 ` hjl dot tools at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2009-06-13 0:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from hjl dot tools at gmail dot com 2009-06-13 00:09 -------
Fixed.
--
hjl dot tools at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40384
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2009-06-09 10:23 [Bug middle-end/40384] New: [4.5 regression] Revision 148277 failed 148277 hjl dot tools at gmail dot com
2009-06-09 10:24 ` [Bug middle-end/40384] " hjl dot tools at gmail dot com
2009-06-09 14:19 ` [Bug tree-optimization/40384] [4.5 regression] Revision 148277 failed gcc.dg/tree-ssa/prefetch-5.c rguenth at gcc dot gnu dot org
2009-06-09 22:37 ` gshobaki at gcc dot gnu dot org
2009-06-10 20:15 ` hjl dot tools at gmail dot com
2009-06-12 5:00 ` hjl dot tools at gmail dot com
2009-06-12 13:16 ` [Bug testsuite/40384] " hjl dot tools at gmail dot com
2009-06-12 13:24 ` hjl dot tools at gmail dot com
2009-06-12 13:38 ` hjl at gcc dot gnu dot org
2009-06-13 0:09 ` hjl dot tools at gmail dot com
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