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* [Bug tree-optimization/45022] New: No prefetch for the vectorized loop
@ 2010-07-21 18:04 changpeng dot fang at amd dot com
2010-07-21 18:06 ` [Bug tree-optimization/45022] " rguenth at gcc dot gnu dot org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: changpeng dot fang at amd dot com @ 2010-07-21 18:04 UTC (permalink / raw)
To: gcc-bugs
For the following test case, if we compile with -O3 -fprefetch-loop-arrays
-march=amdfam10, the loop is versioned (for runtime alias checking) to be
vectorized. However, we see prefetches in the non-vectorize version, but
not in the vectorized version.
void foo(int beta, float *a, float *b)
{
int i;
for(i=0; i<1024; i++)
a[i] = a[i] + beta * b[i];
}
For the vectorized loop, in tree-ssa-loop-arrays.c (idx_analyze_ref):
if (TREE_CODE (base) == MISALIGNED_INDIRECT_REF
|| TREE_CODE (base) == ALIGN_INDIRECT_REF)
return false;
FALSE is returned due to mis-aligned indirect reference:
M*vect_p.18_61{misalignment: 0}
M*vect_p.23_66{misalignment: 0}
M*vect_p.31_74{misalignment: 0}
--
Summary: No prefetch for the vectorized loop
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: changpeng dot fang at amd dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/45022] No prefetch for the vectorized loop
2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
@ 2010-07-21 18:06 ` rguenth at gcc dot gnu dot org
2010-07-22 20:52 ` changpeng dot fang at amd dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2010-07-21 18:06 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2010-07-21 18:06 -------
The misaligned indirect-refs will vanish soon.
--
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=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/45022] No prefetch for the vectorized loop
2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
2010-07-21 18:06 ` [Bug tree-optimization/45022] " rguenth at gcc dot gnu dot org
@ 2010-07-22 20:52 ` changpeng dot fang at amd dot com
2010-07-22 21:17 ` rakdver at kam dot mff dot cuni dot cz
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: changpeng dot fang at amd dot com @ 2010-07-22 20:52 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from changpeng dot fang at amd dot com 2010-07-22 20:52 -------
(In reply to comment #1)
> The misaligned indirect-refs will vanish soon.
>
>From the prefetching point of view, is there any reason that we can not
prefetch
for mis-aligned or indirect refs? <I understand that prefetching for indirect
refs may be too aggressive>
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/45022] No prefetch for the vectorized loop
2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
2010-07-21 18:06 ` [Bug tree-optimization/45022] " rguenth at gcc dot gnu dot org
2010-07-22 20:52 ` changpeng dot fang at amd dot com
@ 2010-07-22 21:17 ` rakdver at kam dot mff dot cuni dot cz
2010-07-29 19:14 ` changpeng dot fang at amd dot com
2010-07-30 8:41 ` rguenther at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: rakdver at kam dot mff dot cuni dot cz @ 2010-07-22 21:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rakdver at kam dot mff dot cuni dot cz 2010-07-22 21:17 -------
Subject: Re: No prefetch for the vectorized
loop
> ------- Comment #2 from changpeng dot fang at amd dot com 2010-07-22 20:52 -------
> (In reply to comment #1)
> > The misaligned indirect-refs will vanish soon.
> >
>
> >From the prefetching point of view, is there any reason that we can not
> prefetch
> for mis-aligned or indirect refs? <I understand that prefetching for indirect
> refs may be too aggressive>
we do prefetching for indirect refs. As for mis-aligned refs, I was a bit
worried
that perhaps on some architectures, taking their address might not be valid;
but
it is likely that I am mistaken on this.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/45022] No prefetch for the vectorized loop
2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
` (2 preceding siblings ...)
2010-07-22 21:17 ` rakdver at kam dot mff dot cuni dot cz
@ 2010-07-29 19:14 ` changpeng dot fang at amd dot com
2010-07-30 8:41 ` rguenther at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: changpeng dot fang at amd dot com @ 2010-07-29 19:14 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from changpeng dot fang at amd dot com 2010-07-29 19:14 -------
(In reply to comment #1)
> The misaligned indirect-refs will vanish soon.
>
I saw your patch that remove ALIGNED_INDIRECT_REF. Do you also plan to remove
MISALIGNED_INDIRECT_REF? Thanks.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/45022] No prefetch for the vectorized loop
2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
` (3 preceding siblings ...)
2010-07-29 19:14 ` changpeng dot fang at amd dot com
@ 2010-07-30 8:41 ` rguenther at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: rguenther at suse dot de @ 2010-07-30 8:41 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from rguenther at suse dot de 2010-07-30 08:41 -------
Subject: Re: No prefetch for the vectorized
loop
On Thu, 29 Jul 2010, changpeng dot fang at amd dot com wrote:
> ------- Comment #4 from changpeng dot fang at amd dot com 2010-07-29 19:14 -------
> (In reply to comment #1)
> > The misaligned indirect-refs will vanish soon.
> >
>
> I saw your patch that remove ALIGNED_INDIRECT_REF. Do you also plan to remove
> MISALIGNED_INDIRECT_REF? Thanks.
Yes.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45022
^ permalink raw reply [flat|nested] 6+ messages in thread
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2010-07-21 18:04 [Bug tree-optimization/45022] New: No prefetch for the vectorized loop changpeng dot fang at amd dot com
2010-07-21 18:06 ` [Bug tree-optimization/45022] " rguenth at gcc dot gnu dot org
2010-07-22 20:52 ` changpeng dot fang at amd dot com
2010-07-22 21:17 ` rakdver at kam dot mff dot cuni dot cz
2010-07-29 19:14 ` changpeng dot fang at amd dot com
2010-07-30 8:41 ` rguenther at suse dot de
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