--- Comment #31 from rguenth at gcc dot gnu dot org 2010-07-08 09:09
---
Subject: Bug 44838
Author: rguenth
Date: Thu Jul 8 09:09:15 2010
New Revision: 161945
URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=161945
Log:
2010-07-08 Richard Guenther rguent...@suse.de
PR
--- Comment #32 from rguenth at gcc dot gnu dot org 2010-07-08 09:16
---
Fixed.
--
rguenth at gcc dot gnu dot org changed:
What|Removed |Added
--- Comment #33 from hjl at gcc dot gnu dot org 2010-07-08 13:40 ---
Subject: Bug 44838
Author: hjl
Date: Thu Jul 8 13:40:24 2010
New Revision: 161953
URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=161953
Log:
Add gcc.dg/pr44838.c.
2010-07-08 H.J. Lu hongjiu...@intel.com
--- Comment #14 from rguenth at gcc dot gnu dot org 2010-07-07 09:01
---
Huh. Unrolling preserves MEM_ATTRs even though it re-writes the RTXen. That
causes scheduling to see just a bunch of repeated
(insn 218 309 219 18 t.c:9 (parallel [
(set (mem:SI (reg/v/f:DI 1 dx
--- Comment #15 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
09:37 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
--- Comment #14 from rguenth at gcc dot gnu dot org 2010-07-07 09:01
---
Huh. Unrolling preserves
--- Comment #16 from amonakov at gcc dot gnu dot org 2010-07-07 09:54
---
(In reply to comment #15)
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
I am not sure what you mean -- I may be misunderstanding how rtl alias
analysis
works, but
--- Comment #17 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
10:09 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
(In reply to comment #15)
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL:
--- Comment #18 from rguenth at gcc dot gnu dot org 2010-07-07 10:30
---
(In reply to comment #17)
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
(In reply to comment #15)
Subject: Re: [4.6 regression] RTL loop
unrolling
--- Comment #19 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
10:35 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
I am not sure what you mean -- I may be misunderstanding how rtl alias
analysis
works, but as far as I
--- Comment #20 from rguenth at gcc dot gnu dot org 2010-07-07 10:43
---
(In reply to comment #19)
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
I am not sure what you mean -- I may be misunderstanding how rtl
alias analysis
--- Comment #21 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
10:47 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
Consider this simplified example:
for (i ...)
{
/*A*/ t = a[i];
/*B*/ a[i+1] = t;
--- Comment #22 from rguenth at gcc dot gnu dot org 2010-07-07 10:48
---
(In reply to comment #21)
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
Consider this simplified example:
for (i ...)
{
/*A*/ t =
--- Comment #23 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
10:51 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
Consider this simplified example:
for (i ...)
{
/*A*/ t = a[i];
/*B*/
--- Comment #24 from rguenth at gcc dot gnu dot org 2010-07-07 11:06
---
In
...
*p_1 = x;
y = *(p_1 + 1);
...
I can say that *p_1 does not alias *(p_1 + 1) independent on what code
is around. If it would be
BB3:
# p_1 = PHI p_0, p_2(3)
*p_1 = x;
y = *(p_1 + 1);
--- Comment #25 from matz at gcc dot gnu dot org 2010-07-07 11:15 ---
Due to SSA form the alias information reflects dependencies only between
accesses as if it ignores back edges. Hence any transformation that
transforms a back edge into a forward edge, or moves code over back edges
--- Comment #26 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
11:19 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
In
...
*p_1 = x;
y = *(p_1 + 1);
...
I can say that *p_1 does not alias *(p_1 + 1) independent
--- Comment #27 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
11:31 ---
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
Due to SSA form the alias information reflects dependencies only between
accesses as if it ignores back edges.
--- Comment #28 from rguenth at gcc dot gnu dot org 2010-07-07 11:59
---
The following is a fix (or workaround) for the problem.
Index: gcc/tree-ssa-alias.c
===
--- gcc/tree-ssa-alias.c(revision 161869)
+++
--- Comment #29 from matz at gcc dot gnu dot org 2010-07-07 12:10 ---
[just for completeness to not lose the thought:]
Thinking about this some more (triggered by the problem of not having nice
back edges in irreducible loops), it's not really the back edges that are
interesting but the
--- Comment #30 from rguenth at gcc dot gnu dot org 2010-07-07 13:58
---
I'm going to test the patch in comment #28.
--
rguenth at gcc dot gnu dot org changed:
What|Removed |Added
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