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[Bug tree-optimization/31862] Loop IM and other optimizations harmful for -fopenmp
- From: "dnovillo at acm dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 May 2007 14:44:16 -0000
- Subject: [Bug tree-optimization/31862] Loop IM and other optimizations harmful for -fopenmp
- References: <bug-31862-87@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #5 from dnovillo at acm dot org 2007-05-08 15:44 -------
Subject: Re: Loop IM and other optimizations harmful for -fopenmp
On 8 May 2007 14:37:05 -0000, rguenth at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
> OMP is not a good generic programming model for threaded code. Exactly because
> of this issues.
No. This is wrong. The model simply requires the compiler to be
smarter. Sequential compilers are not aware of parallel semantics.
If the compiler was thread-aware, these issues would be transparent to
the user (as they should be).
The original code did not have a race condition. The compiler
transformations introduced a race-condition. This *is* a compiler
bug.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31862