* [Bug c++/37991] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
@ 2008-11-01 21:30 ` dcb314 at hotmail dot com
2008-11-02 10:43 ` [Bug tree-optimization/37991] [4.4 Regression] " rguenth at gcc dot gnu dot org
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From: dcb314 at hotmail dot com @ 2008-11-01 21:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from dcb314 at hotmail dot com 2008-11-01 21:28 -------
Created an attachment (id=16611)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16611&action=view)
C++ source code
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
2008-11-01 21:30 ` [Bug c++/37991] " dcb314 at hotmail dot com
@ 2008-11-02 10:43 ` rguenth at gcc dot gnu dot org
2008-11-02 11:00 ` rguenth at gcc dot gnu dot org
` (5 subsequent siblings)
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From: rguenth at gcc dot gnu dot org @ 2008-11-02 10:43 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2008-11-02 10:42 -------
Confirmed. We seem to be very slowly eating all of memory during processing
a single SCC in FRE - which means iteration doesn't converge.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Component|c++ |tree-optimization
Ever Confirmed|0 |1
GCC host triplet|suse-linux-x86_64 |
GCC target triplet| |i?86-*-*, x86_64-*-*
Keywords| |compile-time-hog, memory-hog
Known to work| |4.3.2
Priority|P3 |P1
Last reconfirmed|0000-00-00 00:00:00 |2008-11-02 10:42:12
date| |
Summary|excessive memory consumption|[4.4 Regression] excessive
|- possible hang |memory consumption -
| |possible hang
Target Milestone|--- |4.4.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
2008-11-01 21:30 ` [Bug c++/37991] " dcb314 at hotmail dot com
2008-11-02 10:43 ` [Bug tree-optimization/37991] [4.4 Regression] " rguenth at gcc dot gnu dot org
@ 2008-11-02 11:00 ` rguenth at gcc dot gnu dot org
2008-11-02 11:28 ` rguenth at gcc dot gnu dot org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-11-02 11:00 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rguenth at gcc dot gnu dot org 2008-11-02 10:58 -------
Reducing.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
` (2 preceding siblings ...)
2008-11-02 11:00 ` rguenth at gcc dot gnu dot org
@ 2008-11-02 11:28 ` rguenth at gcc dot gnu dot org
2008-11-02 12:05 ` rguenth at gcc dot gnu dot org
` (3 subsequent siblings)
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From: rguenth at gcc dot gnu dot org @ 2008-11-02 11:28 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rguenth at gcc dot gnu dot org 2008-11-02 11:27 -------
The following fails this way with plain -O. The key is the typedef - if you
replace the use of UInt32 with unsinged int the testcase succeeds. Mine.
typedef unsigned int UInt32;
int Read(unsigned int *processedSize);
void FindAndReadSignature(void)
{
unsigned int numPrevBytes = 31;
for (;;)
{
unsigned int numReadBytes = (1 << 16) - numPrevBytes;
unsigned int processedSize;
int __result__ = Read(&processedSize);
unsigned int numBytesInBuffer = numPrevBytes + processedSize;
UInt32 numTests = numBytesInBuffer - 31;
for (unsigned int pos = 0; pos < numTests; pos++)
;
numPrevBytes = numBytesInBuffer - numTests;
}
}
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2008-11-02 10:42:12 |2008-11-02 11:27:05
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
` (3 preceding siblings ...)
2008-11-02 11:28 ` rguenth at gcc dot gnu dot org
@ 2008-11-02 12:05 ` rguenth at gcc dot gnu dot org
2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-11-02 12:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from rguenth at gcc dot gnu dot org 2008-11-02 12:04 -------
More reduced:
typedef int Int32;
void use_it(int);
void FindAndReadSignature(int processedSize)
{
int numPrevBytes = 1;
for (;;)
{
int numBytesInBuffer = numPrevBytes + processedSize;
Int32 numTests = numBytesInBuffer - 1;
use_it (numTests);
numPrevBytes = numBytesInBuffer - numTests;
}
}
to not oscillate we rely on numTests _not_ be varying. It happens to be
with the typedef as we forget to strip useless conversions. Otherwise
we oscillate numPrevBytes (loop entry vs. back edge) between 1 and varying.
Which may hint at that the speedup brought up by Danny (not processing a
use further if it got varying) is even a correctness thing...
I have a patch for this particular case.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dberlin at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
` (4 preceding siblings ...)
2008-11-02 12:05 ` rguenth at gcc dot gnu dot org
@ 2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
2008-11-02 20:55 ` dberlin at dberlin dot org
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-11-02 13:37 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from rguenth at gcc dot gnu dot org 2008-11-02 13:35 -------
Fixed.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
` (5 preceding siblings ...)
2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
@ 2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
2008-11-02 20:55 ` dberlin at dberlin dot org
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-11-02 13:37 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from rguenth at gcc dot gnu dot org 2008-11-02 13:36 -------
Subject: Bug 37991
Author: rguenth
Date: Sun Nov 2 13:34:58 2008
New Revision: 141532
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=141532
Log:
2008-11-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/37991
* tree-ssa-sccvn.h (copy_vuses_from_stmt): Remove.
* tree-ssa-sccvn.c (copy_vuses_from_stmt): Make static.
(set_ssa_val_to): Print if the value changed.
(simplify_binary_expression): Strip useless conversions.
* gcc.c-torture/compile/pr37991.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.c-torture/compile/pr37991.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-sccvn.c
trunk/gcc/tree-ssa-sccvn.h
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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* [Bug tree-optimization/37991] [4.4 Regression] excessive memory consumption - possible hang
2008-11-01 21:29 [Bug c++/37991] New: excessive memory consumption - possible hang dcb314 at hotmail dot com
` (6 preceding siblings ...)
2008-11-02 13:37 ` rguenth at gcc dot gnu dot org
@ 2008-11-02 20:55 ` dberlin at dberlin dot org
7 siblings, 0 replies; 9+ messages in thread
From: dberlin at dberlin dot org @ 2008-11-02 20:55 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from dberlin at gcc dot gnu dot org 2008-11-02 20:53 -------
Subject: Re: [4.4 Regression] excessive memory consumption - possible hang
On Sun, Nov 2, 2008 at 7:04 AM, rguenth at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
> ------- Comment #5 from rguenth at gcc dot gnu dot org 2008-11-02 12:04 -------
> More reduced:
>
> typedef int Int32;
> void use_it(int);
> void FindAndReadSignature(int processedSize)
> {
> int numPrevBytes = 1;
> for (;;)
> {
> int numBytesInBuffer = numPrevBytes + processedSize;
> Int32 numTests = numBytesInBuffer - 1;
> use_it (numTests);
> numPrevBytes = numBytesInBuffer - numTests;
> }
> }
>
> to not oscillate we rely on numTests _not_ be varying. It happens to be
> with the typedef as we forget to strip useless conversions. Otherwise
> we oscillate numPrevBytes (loop entry vs. back edge) between 1 and varying.
>
> Which may hint at that the speedup brought up by Danny (not processing a
> use further if it got varying) is even a correctness thing...
Things should never go up the lattice :)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37991
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