[Bug target/29852] x86_64: SSE version missing for fmod{d,s,x}f3
burnus at gcc dot gnu dot org
gcc-bugzilla@gcc.gnu.org
Wed Nov 29 10:38:00 GMT 2006
------- Comment #2 from burnus at gcc dot gnu dot org 2006-11-29 10:38 -------
If one uses -mfpmath=387 or -mfpmath=sse,387, the speed also dramatically
increases.
Results with test case below on a Athlon64:
icc -O3 test.c; time ./a.out
d=100002.216410, r=100000.000026
real 0m2.549s; user 0m2.548s; sys 0m0.000s
gcc -ftree-vectorize -O3 -msse3 -ffast-math -lm test.c
d=100002.216410, r=100000.000026
real 0m5.444s; user 0m5.444s; sys 0m0.000s
gcc -ftree-vectorize -O3 -msse3 -mfpmath=sse,387 -ffast-math -lm test.c
d=100002.216410, r=100000.000026
real 0m1.363s; user 0m1.192s; sys 0m0.000s
----------------
#include <math.h>
#include <stdio.h>
int main() {
double r,d;
d = 0.0;
for(r=0.0; r < 100000.0; r += 0.001)
d = fmod(d,5.0)+r;
printf("d=%f, r=%f\n",d,r);
return 0;
}
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29852
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