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[Bug tree-optimization/43716] [4.6 Regression] Revision 158105 miscompiles doduc.f90
- From: "maxim at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 May 2010 15:07:03 -0000
- Subject: [Bug tree-optimization/43716] [4.6 Regression] Revision 158105 miscompiles doduc.f90
- References: <bug-43716-12313@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #23 from mkuvyrkov at gcc dot gnu dot org 2010-05-06 15:07 -------
Subject: Re: [4.6 Regression] Revision 158105
miscompiles doduc.f90
On 5/6/10 6:59 PM, dominiq at lps dot ens dot fr wrote:
...
> Now the questions are:
> (1) why a change dealing with the propagation of minus signs interferes with
> reciprocal-math?
> (2) why moving VEC_safe_push from negate_value to eliminate_plus_minus_pair
> trigger the miscompilation?
Just to be clear, I do not think there is a miscompilation here.
The patch that [among other things] moved VEC_safe_push from
negate_value to eliminate_plus_minus_pair did that to enable "(a + (-b))
-> (a - b)" optimization in more cases.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43716