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[Bug tree-optimization/25621] Missed optimization when unrolling the loop (splitting up the sum) (only with -ffast-math)
- From: "Joost.VandeVondele at mat dot ethz.ch" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sun, 16 Mar 2014 15:53:50 +0000
- Subject: [Bug tree-optimization/25621] Missed optimization when unrolling the loop (splitting up the sum) (only with -ffast-math)
- Auto-submitted: auto-generated
- References: <bug-25621-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25621
--- Comment #13 from Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> ---
(In reply to Joost VandeVondele from comment #12)
> Both compilers fail to notice that S32 is basically the same code
> hand-unrolled.
with gcc 4.9
> ./a.out
default loop 0.54291800000000001
hand optimized loop 0.54291700000000009
so, some progress, both versions of the loop give the same performance. Still
not quite as good as ifort, however.