https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112325
Bug ID: 112325
Summary: Missed vectorization after cunrolli
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: wwwhhhyyy333 at gmail dot com
Target Milestone: ---
testcase:
#include <stdint.h>
#include <string.h>
typedef struct {
float s;
int8_t qs[32];
} block;
void foo (const int n, float * restrict s, const int8_t q[4], const block *
restrict y) {
const int qk = 32;
const int nb = n / qk;
float sumf = 0.0;
int sumi = 0;
for (int i = 0; i < nb; i++) {
uint32_t qh;
memcpy(&qh, q, 4);
for (int j = 0; j < qk/2; ++j) {
sumi += (qh >> j) * y[i].qs[j];
}
sumf += (y[i].s * (float) sumi);
}
*s = sumf;
}
This can be vectorized under -O2 -mavx512vl but not -O3 -mavx512vl, see
https://godbolt.org/z/csPr4cPen
Under -O3 -mavx512vl -fdisable-tree-cunrolli the loop can also be vectorized.
