[Bug tree-optimization/25621] Missed optimization when unrolling the loop (splitting up the sum) (only with -ffast-math)

[Joost.VandeVondele at mat dot ethz.ch]

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.