* [Bug tree-optimization/20643] [4.0/4.1 Regression] Tree loop optimizer does worse job than RTL loop optimizer
[not found] <bug-20643-3107@http.gcc.gnu.org/bugzilla/>
@ 2005-10-03 15:10 ` sje at cup dot hp dot com
2005-10-31 2:51 ` mmitchel at gcc dot gnu dot org
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From: sje at cup dot hp dot com @ 2005-10-03 15:10 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from sje at cup dot hp dot com 2005-10-03 15:10 -------
Just to clarify the main issue here, my main concern here is not the conversion
of the for loop to a do loop but rather the alias disambiguation and the
movement of loop invariant code out of the inner most loop in P7Viterbi.
Because the new alias analysis is not as good as it used to be (with respect to
structures) more code is left in the inner loop. This is why the test case is
so much slower now than before.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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[not found] <bug-20643-3107@http.gcc.gnu.org/bugzilla/>
2005-10-03 15:10 ` [Bug tree-optimization/20643] [4.0/4.1 Regression] Tree loop optimizer does worse job than RTL loop optimizer sje at cup dot hp dot com
@ 2005-10-31 2:51 ` mmitchel at gcc dot gnu dot org
2005-10-31 3:43 ` dberlin at gcc dot gnu dot org
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From: mmitchel at gcc dot gnu dot org @ 2005-10-31 2:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from mmitchel at gcc dot gnu dot org 2005-10-31 02:51 -------
Dan, is there any chance of fixing this for 4.1?
--
mmitchel 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=20643
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[not found] <bug-20643-3107@http.gcc.gnu.org/bugzilla/>
2005-10-03 15:10 ` [Bug tree-optimization/20643] [4.0/4.1 Regression] Tree loop optimizer does worse job than RTL loop optimizer sje at cup dot hp dot com
2005-10-31 2:51 ` mmitchel at gcc dot gnu dot org
@ 2005-10-31 3:43 ` dberlin at gcc dot gnu dot org
2006-02-24 0:26 ` [Bug tree-optimization/20643] [4.0/4.1/4.2 " mmitchel at gcc dot gnu dot org
` (14 subsequent siblings)
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From: dberlin at gcc dot gnu dot org @ 2005-10-31 3:43 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from dberlin at gcc dot gnu dot org 2005-10-31 03:43 -------
Realistically?
No.
I'm about to start solving it on the improved-aliasing branch.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (2 preceding siblings ...)
2005-10-31 3:43 ` dberlin at gcc dot gnu dot org
@ 2006-02-24 0:26 ` mmitchel at gcc dot gnu dot org
2006-04-18 14:15 ` bonzini at gnu dot org
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From: mmitchel at gcc dot gnu dot org @ 2006-02-24 0:26 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from mmitchel at gcc dot gnu dot org 2006-02-24 00:25 -------
This issue will not be resolved in GCC 4.1.0; retargeted at GCC 4.1.1.
--
mmitchel at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.1.0 |4.1.1
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (3 preceding siblings ...)
2006-02-24 0:26 ` [Bug tree-optimization/20643] [4.0/4.1/4.2 " mmitchel at gcc dot gnu dot org
@ 2006-04-18 14:15 ` bonzini at gnu dot org
2006-04-28 14:06 ` rguenth at gcc dot gnu dot org
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From: bonzini at gnu dot org @ 2006-04-18 14:15 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from bonzini at gnu dot org 2006-04-18 14:15 -------
Mark, I don't believe there is any chance that it be fixed in 4.0/4.1?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (4 preceding siblings ...)
2006-04-18 14:15 ` bonzini at gnu dot org
@ 2006-04-28 14:06 ` rguenth at gcc dot gnu dot org
2006-05-25 2:35 ` mmitchel at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2006-04-28 14:06 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from rguenth at gcc dot gnu dot org 2006-04-28 14:06 -------
This is really because we do not decompose structs pointed to by parameters for
their elements, so a write to an int clobbers all of plan7_s.
With -O2 timings on i686 are for me (averages of three runs)
3.4.6 5.4s
4.0.3 7.4s
4.1.0 6.1s
4.2.0 6.6s
manually PREing gives 5.2s for mainline.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (5 preceding siblings ...)
2006-04-28 14:06 ` rguenth at gcc dot gnu dot org
@ 2006-05-25 2:35 ` mmitchel at gcc dot gnu dot org
2006-07-16 13:21 ` anemo at mba dot ocn dot ne dot jp
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From: mmitchel at gcc dot gnu dot org @ 2006-05-25 2:35 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from mmitchel at gcc dot gnu dot org 2006-05-25 02:32 -------
Will not be fixed in 4.1.1; adjust target milestone to 4.1.2.
--
mmitchel at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.1.1 |4.1.2
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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[not found] <bug-20643-3107@http.gcc.gnu.org/bugzilla/>
` (6 preceding siblings ...)
2006-05-25 2:35 ` mmitchel at gcc dot gnu dot org
@ 2006-07-16 13:21 ` anemo at mba dot ocn dot ne dot jp
2006-07-16 13:53 ` steven at gcc dot gnu dot org
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From: anemo at mba dot ocn dot ne dot jp @ 2006-07-16 13:21 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from anemo at mba dot ocn dot ne dot jp 2006-07-16 13:21 -------
I have a similer optimization problem with this tiny function.
void foo(int *a)
{
int i;
for (i = 0; i < 100; i++)
a[0] += a[1];
}
All gcc 4.x I tried generate load and store in inner loop.
On http://gcc.gnu.org/ml/gcc/2006-07/msg00282.html, I posted some results.
Is this a same probelm? If not, I should file another bug report. Thank you.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (7 preceding siblings ...)
2006-07-16 13:21 ` anemo at mba dot ocn dot ne dot jp
@ 2006-07-16 13:53 ` steven at gcc dot gnu dot org
2006-07-17 11:55 ` rakdver at gcc dot gnu dot org
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From: steven at gcc dot gnu dot org @ 2006-07-16 13:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #12 from steven at gcc dot gnu dot org 2006-07-16 13:52 -------
The test case in comment #11 looks like a classic store motion opportunity to
me. GCC 3.3 performs the store motion, GCC 4.2 r115467 does not.
Zdenek, I thought tree-ssa-lim should be able to do store motion in loops?
--
steven at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rakdver at gcc dot gnu dot
| |org
Last reconfirmed|2006-02-01 04:41:41 |2006-07-16 13:52:59
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (8 preceding siblings ...)
2006-07-16 13:53 ` steven at gcc dot gnu dot org
@ 2006-07-17 11:55 ` rakdver at gcc dot gnu dot org
2006-07-17 13:34 ` dberlin at dberlin dot org
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From: rakdver at gcc dot gnu dot org @ 2006-07-17 11:55 UTC (permalink / raw)
To: gcc-bugs
------- Comment #13 from rakdver at gcc dot gnu dot org 2006-07-17 11:54 -------
(In reply to comment #12)
> The test case in comment #11 looks like a classic store motion opportunity to
> me. GCC 3.3 performs the store motion, GCC 4.2 r115467 does not.
>
> Zdenek, I thought tree-ssa-lim should be able to do store motion in loops?
Yes, however again, the alias analysis does not tell it that a[0] does not
alias a[1]; once that is fixed, tree-ssa-lim should work just fine.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (9 preceding siblings ...)
2006-07-17 11:55 ` rakdver at gcc dot gnu dot org
@ 2006-07-17 13:34 ` dberlin at dberlin dot org
2006-07-18 16:53 ` anemo at mba dot ocn dot ne dot jp
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From: dberlin at dberlin dot org @ 2006-07-17 13:34 UTC (permalink / raw)
To: gcc-bugs
------- Comment #14 from dberlin at gcc dot gnu dot org 2006-07-17 13:34 -------
Subject: Re: [4.0/4.1/4.2 Regression] Tree loop
optimizer does worse job than RTL loop optimizer
rakdver at gcc dot gnu dot org wrote:
> ------- Comment #13 from rakdver at gcc dot gnu dot org 2006-07-17 11:54 -------
> (In reply to comment #12)
>> The test case in comment #11 looks like a classic store motion opportunity to
>> me. GCC 3.3 performs the store motion, GCC 4.2 r115467 does not.
>>
>> Zdenek, I thought tree-ssa-lim should be able to do store motion in loops?
>
> Yes, however again, the alias analysis does not tell it that a[0] does not
> alias a[1]; once that is fixed, tree-ssa-lim should work just fine.
This is because it's an incoming parameter, and as a result, this
doesn't look at all like an array access, but just a random pointer access.
I have no plans to make the alias analysis algorithm reconstruct array
indexes from random pointer arithmetic.
--Dan
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (10 preceding siblings ...)
2006-07-17 13:34 ` dberlin at dberlin dot org
@ 2006-07-18 16:53 ` anemo at mba dot ocn dot ne dot jp
2006-07-18 17:04 ` dberlin at dberlin dot org
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From: anemo at mba dot ocn dot ne dot jp @ 2006-07-18 16:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #15 from anemo at mba dot ocn dot ne dot jp 2006-07-18 16:53 -------
(In reply to comment #14)
> This is because it's an incoming parameter, and as a result, this
> doesn't look at all like an array access, but just a random pointer access.
>
> I have no plans to make the alias analysis algorithm reconstruct array
> indexes from random pointer arithmetic.
I do not think reconstructing array indexes are needed,
but is it hard to tell that *(a+0) never be an alias of *(a+1) ?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (11 preceding siblings ...)
2006-07-18 16:53 ` anemo at mba dot ocn dot ne dot jp
@ 2006-07-18 17:04 ` dberlin at dberlin dot org
2007-02-14 9:05 ` [Bug tree-optimization/20643] [4.0/4.1/4.2/4.3 " mmitchel at gcc dot gnu dot org
` (4 subsequent siblings)
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From: dberlin at dberlin dot org @ 2006-07-18 17:04 UTC (permalink / raw)
To: gcc-bugs
------- Comment #16 from dberlin at gcc dot gnu dot org 2006-07-18 17:03 -------
Subject: Re: [4.0/4.1/4.2 Regression] Tree loop
optimizer does worse job than RTL loop optimizer
anemo at mba dot ocn dot ne dot jp wrote:
> ------- Comment #15 from anemo at mba dot ocn dot ne dot jp 2006-07-18 16:53 -------
> (In reply to comment #14)
>> This is because it's an incoming parameter, and as a result, this
>> doesn't look at all like an array access, but just a random pointer access.
>>
>> I have no plans to make the alias analysis algorithm reconstruct array
>> indexes from random pointer arithmetic.
>
> I do not think reconstructing array indexes are needed,
> but is it hard to tell that *(a+0) never be an alias of *(a+1) ?
We already do say this when we know the offsets. The point is that
without reconstructing the array indexes, we'd have to follow use-def
chains for *every single pointer access* on *every single operand
update*, in order to attempt to get the offsets and disambiguate them.
This is incredibly slow.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (12 preceding siblings ...)
2006-07-18 17:04 ` dberlin at dberlin dot org
@ 2007-02-14 9:05 ` mmitchel at gcc dot gnu dot org
2007-06-11 0:54 ` pinskia at gcc dot gnu dot org
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From: mmitchel at gcc dot gnu dot org @ 2007-02-14 9:05 UTC (permalink / raw)
To: gcc-bugs
--
mmitchel at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.1.2 |4.1.3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (13 preceding siblings ...)
2007-02-14 9:05 ` [Bug tree-optimization/20643] [4.0/4.1/4.2/4.3 " mmitchel at gcc dot gnu dot org
@ 2007-06-11 0:54 ` pinskia at gcc dot gnu dot org
2007-07-04 17:59 ` [Bug tree-optimization/20643] [4.0/4.1/4.2 " pinskia at gcc dot gnu dot org
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From: pinskia at gcc dot gnu dot org @ 2007-06-11 0:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #17 from pinskia at gcc dot gnu dot org 2007-06-11 00:53 -------
the pointer_plus branch improves the code here (I can't tell if it fixes the
problem fully).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (14 preceding siblings ...)
2007-06-11 0:54 ` pinskia at gcc dot gnu dot org
@ 2007-07-04 17:59 ` pinskia at gcc dot gnu dot org
2008-07-04 16:51 ` [Bug tree-optimization/20643] [4.2 " jsm28 at gcc dot gnu dot org
2009-03-30 15:43 ` jsm28 at gcc dot gnu dot org
17 siblings, 0 replies; 18+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-07-04 17:59 UTC (permalink / raw)
To: gcc-bugs
------- Comment #18 from pinskia at gcc dot gnu dot org 2007-07-04 17:58 -------
Yep this was fixed by Pointer_plus.
The load of hmm->tsc is no longer in the inner most loop.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[4.0/4.1/4.2/4.3 Regression]|[4.0/4.1/4.2 Regression]
|Tree loop optimizer does |Tree loop optimizer does
|worse job than RTL loop |worse job than RTL loop
|optimizer |optimizer
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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` (15 preceding siblings ...)
2007-07-04 17:59 ` [Bug tree-optimization/20643] [4.0/4.1/4.2 " pinskia at gcc dot gnu dot org
@ 2008-07-04 16:51 ` jsm28 at gcc dot gnu dot org
2009-03-30 15:43 ` jsm28 at gcc dot gnu dot org
17 siblings, 0 replies; 18+ messages in thread
From: jsm28 at gcc dot gnu dot org @ 2008-07-04 16:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #19 from jsm28 at gcc dot gnu dot org 2008-07-04 16:50 -------
Closing 4.1 branch.
--
jsm28 at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[4.1/4.2 Regression] Tree |[4.2 Regression] Tree loop
|loop optimizer does worse |optimizer does worse job
|job than RTL loop optimizer |than RTL loop optimizer
Target Milestone|4.1.3 |4.2.5
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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2008-07-04 16:51 ` [Bug tree-optimization/20643] [4.2 " jsm28 at gcc dot gnu dot org
@ 2009-03-30 15:43 ` jsm28 at gcc dot gnu dot org
17 siblings, 0 replies; 18+ messages in thread
From: jsm28 at gcc dot gnu dot org @ 2009-03-30 15:43 UTC (permalink / raw)
To: gcc-bugs
------- Comment #20 from jsm28 at gcc dot gnu dot org 2009-03-30 15:43 -------
Closing 4.2 branch, fixed in 4.3.
--
jsm28 at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Known to fail|4.0.4 |4.0.4 4.2.5
Known to work| |4.3.0
Resolution| |FIXED
Target Milestone|4.2.5 |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20643
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