https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103399
Bug ID: 103399
Summary: [12 Regression] Wrong code with -O2
Product: gcc
Version: 12.0
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: ---
Link to the Compiler Explorer: https://godbolt.org/z/3GE6fKvYr
Reproducer:
#include <stdio.h>
char a = 0;
long long b[8][10][18];
void e(int, long long[][10][18]) __attribute__((noipa));
void e(int f, long long g[][10][18]) {
for (int d = 0; d < f; d += 3LL)
for (int c = 0; c < ((f ? g[5][0][0] : 0) ^ g[5][0][0]) + 1; c++)
a = 42;
}
int main() {
for (size_t i = 0; i < 8; ++i)
for (size_t k = 0; k < 10; ++k)
for (size_t j = 0; j < 8; ++j)
b[i][k][j] = -1311387439415292401LL;
e(8, b);
printf("%u\n", a);
if (a != 42)
__builtin_abort();
}
Error:
>$ g++ -O1 driver.cpp && ./a.out
42
>$ g++ -O2 driver.cpp && ./a.out
0
gcc version 12.0.0 20211123 (721d8b9e26bf8205c1f2125c2626919a408cdbe4) (GCC)
