--- Comment #9 from amonakov at gcc dot gnu dot org 2010-03-10 12:54
---
Subject: Bug 43236
Author: amonakov
Date: Wed Mar 10 12:53:51 2010
New Revision: 157339
URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=157339
Log:
PR tree-optimization/43236
*
--- Comment #10 from amonakov at gcc dot gnu dot org 2010-03-10 12:57
---
Both issues are fixed with above commit.
--
amonakov at gcc dot gnu dot org changed:
What|Removed |Added
--- Comment #11 from sezeroz at gmail dot com 2010-03-10 14:17 ---
The testcase fails with 4.4 with -Ox -ftree-loop-distribution and the patch
does not apply to 4.4. Will there be a gcc-4.4 backport of this?
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sezeroz at gmail dot com changed:
What|Removed
--- Comment #8 from amonakov at gcc dot gnu dot org 2010-03-09 16:55
---
Given the fact that loop distribution only works for two-bb loops, I think the
fix is to simply take number of latch executions when the stmt is in the latch.
diff --git a/gcc/tree-loop-distribution.c
--- Comment #5 from rguenth at gcc dot gnu dot org 2010-03-03 10:38 ---
Confirmed.
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rguenth at gcc dot gnu dot org changed:
What|Removed |Added
CC|
--- Comment #6 from amonakov at gcc dot gnu dot org 2010-03-03 13:06
---
Not a regression, off-by-one error in reverse iteration case is since day one.
Patch:
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 13ac7ea..110abdc 100644
---
--- Comment #7 from amonakov at gcc dot gnu dot org 2010-03-03 13:38
---
(In reply to comment #6)
This fixes the -O[123] miscompilations. -Os is slightly harder to fix, since
we
use wrong number of iterations (cond bb is executed 11 times, latch bb with
assignment 10 times).
I
--- Comment #1 from zsojka at seznam dot cz 2010-03-02 20:20 ---
Created an attachment (id=20005)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20005action=view)
this patch causes bootstrap with BOOT_CFLAGS=-O2 -ftree-loop-distribution to
assert
Assert message is:
--- Comment #2 from zsojka at seznam dot cz 2010-03-02 20:33 ---
Created an attachment (id=20006)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20006action=view)
this patch causes regular bootstrap to assert
Assert message is:
/mnt/svn/gcc-trunk/libgcc/../gcc/libgcc2.c: In
--- Comment #3 from zsojka at seznam dot cz 2010-03-03 06:26 ---
Created an attachment (id=20008)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20008action=view)
minimal executable testcase
Fails when compiled with -ftree-loop-distribution at all -O[123s] levels:
$
--- Comment #4 from zsojka at seznam dot cz 2010-03-03 06:30 ---
(In reply to comment #3)
When output is uncommented, -Os shows different behaviour than -O[123] (but
still wrong):
-Os zeroes items [8] - [18]
-O[123] zeroes [9] - [18]
expected is [10] - [19]
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