[Bug tree-optimization/95045] New: wrong code at -O3 on x86_64-linux-gnu

[qrzhang at gatech dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

            Bug ID: 95045
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: qrzhang at gatech dot edu
  Target Milestone: ---

Recent regression. Bisection points to g:283cb9ea6293e813e4


$ gcc-trunk -v
gcc version 11.0.0 20200510 (experimental) [master revision
4ae915cdbf0:8eedda9eef3:ef6394205d7bcab00dca01182d708ad5a6360a7b] (GCC)


$ gcc-trunk abc.c ; ./a.out
4


$ gcc-trunk -O3  abc.c ; ./a.out
0


$ cat abc.c
int a, c, f;
long b;
char d;
int e[3];
int g[9][3][2];
int main() {
  {
  h:
    for (f = 0; f <= 5; f++) {
      b = 3;
      for (; b >= 0; b--) {
        e[2] = d = 0;
        for (; d <= 3; d++) {
          g[8][2][0] = e[1] = c = 0;
          for (; c <= 1; c++)
            e[c + 1] = g[d + 5][2][c] = 4;
        }
        if (a)
          goto h;
      }
    }
  }
  printf("%d\n", e[2]);
}