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[Bug fortran/36599] major execution regression for induct.f90 polyhedron benchmark in 4.3.1 on Intel
- From: "burnus at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 22 Jun 2008 17:54:02 -0000
- Subject: [Bug fortran/36599] major execution regression for induct.f90 polyhedron benchmark in 4.3.1 on Intel
- References: <bug-36599-11113@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from burnus at gcc dot gnu dot org 2008-06-22 17:54 -------
Fortran requires that parenthesis are always honoured. All other associative
maths operations are allowed in Fortran, but as IEEE is also allowed, this
gives problems e.g. INF is involved or signed zeros. Therefore, gfortran does
no associative operations by default, only if -ffinite-math-only is enabled.
But in this case, there the parenthesis are still always honoured.
At least this is my knowledge about the optimizations done at the moment.
Though, at the moment it is unclear to me, why -O3 is slower than -O2.
See also PR 35259.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36599