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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 tree-optimization/111839] New: Wrong code at -O3 on
 x86_64-linux-gnu since r12-2097-g9f34b780b0
Date: Mon, 16 Oct 2023 19:25:19 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111839

            Bug ID: 111839
           Summary: Wrong code at -O3 on x86_64-linux-gnu since
                    r12-2097-g9f34b780b0
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          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 -O3 produced the wrong code.

Bisected to r12-2097-g9f34b780b0

Compiler explorer: https://godbolt.org/z/Ea1hGGnob

$ cat a.c
int printf(const char *, ...);
long a;
int b, c, e, g, i;
long *d, *h;
char f =3D -26;
int main() {
  long j;
  c =3D 0;
  for (; c !=3D 7; ++c) {
    long k=3D0;
    long l =3D k;
    long **m =3D &d;
    for (; f + i!=3D0; i++)
      h =3D &l;
    g =3D h !=3D (*m =3D &j);
    int *n =3D &b;
    *n =3D g;
    for (; e;)
      for (; a; a =3D a + 1)
        ;
  }
  printf("%d\n", b);
}
$
$ gcc -fsanitize=3Daddress,undefined a.c && ./a.out
1
$ gcc -O3 a.c && ./a.out
0
$=