https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99100
Bug ID: 99100
Summary: Inconsistent vector length used in autovectorizer for
AVX-512
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: shibatch.sf.net at gmail dot com
Target Milestone: ---
When AVX512 instruction is available, the auto-vectorizer in gcc
sometimes generates calls to AVX2 functions instead of AVX512 functions.
-mprefer-vector-width=512 does not affect the result.
$ cat vabitest.c
#include <stdio.h>
#include <math.h>
_Pragma ("omp declare simd simdlen(8) notinbranch")
__attribute__((const)) double myfunc(double x);
#define N 1024
__attribute__ ((__aligned__(256))) double a[N], b[N], c[N];
int main(void) {
for (int i = 0; i < N; i++) a[i] = myfunc(b[i]);
for (int i = 0; i < N; i++) c[i] = sin(b[i]);
}
$ gcc-10 -ffast-math -O3 -mavx512f -fopenmp vabitest.c -S -o- | grep _ZGV
call _ZGVdN8v_myfunc@PLT
call _ZGVeN8v_sin@PLT
