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

[jv244 at cam dot ac dot uk]

------- Comment #10 from jv244 at cam dot ac dot uk  2008-12-05 16:25 -------
Timings in 4.4 are essentially unchanged

gfortran -O3 -ffast-math -march=native PR25621.f90:

 default loop   1.2920810000000000
 hand optimized loop  0.86405399999999988

fun enough inverse timings with a recent intel compiler:

 default loop  0.440028000000000
 hand optimized loop   1.26007800000000


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25621