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From: "shaohua.li at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/111256] New: Wrong code at -O2/3/s since
 r10-1615-g75efe9cb1f8
Date: Thu, 31 Aug 2023 08:42:07 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111256

            Bug ID: 111256
           Summary: Wrong code at -O2/3/s since r10-1615-g75efe9cb1f8
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: rguenth at gcc dot gnu.org
  Target Milestone: ---

gcc at -O2/3/s produces the wrong code.

Bisected to r10-1615-g75efe9cb1f8

Compiler explorer: https://godbolt.org/z/WPzEMoW6e

$ cat a.c
int printf(const char *, ...);
int a, d, e, g;
long b, h;
long i() {
  b++;
  return b;
}
int l(int m[], int p[]) {
  if (d)
    for (; e; e++) {
      m[4] =3D m[0] =3D m[1] ^ m[2] ^ m[5];
      m[7] =3D m[3] ^ m[6];
      m +=3D 4;
    }
  m[6] =3D m[0] ^ 1;
  m[7] =3D m[1] ^ m[2] ^ m[7];
  m[9] =3D m[3] ^ m[8];
  return 1;
}
int fn3() {
  int j[] =3D {0, 7, 0, 0, 5, 0, 0, 8, 0, 0};
  int k[17];
  int c =3D l(j, k);
  return c;
}
int main() {
  for (; h <=3D 3; h =3D fn3() + h) {
    long n[2];
    for (; i() < 2;)
      n[g] =3D 508;
    for (; (int)n[0] < 2;) {
      char o[] =3D {3, 4, 6, 3, 0, 0, 5, 6, 6, 1, 7, 0, 0, 0, 0, 0};
      char *f =3D o;
      for (; *f; ++f)
        ;
    }
  }
  printf("%X\n", a);
}
$
$ gcc -O0 a.c && ./a.out
0
$ gcc -O2 a.c
% ./a.out
(Timeout)=