http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48509
Summary: Fails to Vectorize loop involving doubles which was
vectorized in 4.5
Product: gcc
Version: 4.6.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: [email protected]
ReportedBy: [email protected]
The following program is vectorized by gcc-4.5 but not by gcc-4.6 with the
following options: -march=native -mtune=native -ftree-vectorizer-verbose=12 -O3
-std=c99 -ffast-math -funsafe-math-optimizations -lm
#include <stdio.h>
#include <math.h>
int main() {
double g[1000];
for(int i=0; i<1000; i++) {
g[i]=2*(g[i]);
}
for(int i=0; i<1000; i++) {
printf("%f\n",g[i]);
}
}
In 4.6 it instead outputs:
main.c:5: note: not vectorized: no vectype for stmt: D.4271_4 = g[i_22];
scalar_type: double
