https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91293
Bug ID: 91293
Summary: Wrong code with -O3
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vsevolod.livinskij at frtk dot ru
Target Milestone: ---
GCC produces wrong code with -O3 option.
Reproducer:
#include <stdio.h>
long long a;
unsigned b, c;
int d = 62;
void e(long long *f, int p2) { *f = p2; }
int main() {
for (int g = 2; g <= d; g++) {
c += 5 - g;
b += g + 4;
}
e(&a, b);
printf("%llu\n", a);
}
Error:
>$ gcc -march=skylake-avx512 -O3 small.c ; ./a.out
18446744073709550508
>$ gcc -march=skylake-avx512 -O0 small.c ; ./a.out
2196
GCC version: 10.0.0 (rev. 273839)
