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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/111519] New: [13/14 Regression] Wrong code at
 -O3 on x86_64-linux-gnu since r13-455-g1fe04c497d
Date: Thu, 21 Sep 2023 13:20:27 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111519

            Bug ID: 111519
           Summary: [13/14 Regression] Wrong code at -O3 on
                    x86_64-linux-gnu since r13-455-g1fe04c497d
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: roger at nextmovesoftware dot com
  Target Milestone: ---

gcc at -O3 produced the wrong code.

Bisected to r13-455-g1fe04c497d

Compiler explorer: https://godbolt.org/z/ozEaKa1rY

$ cat a.c
int printf(const char *, ...);
int a, o;
char b, f, i;
long c;
static signed char d;
static char g;
unsigned *h;
signed char *e =3D &f;
static signed char **j =3D &e;
static long k[2];
unsigned **l =3D &h;
short m;
int main(int q, char *r[]) {
  int p =3D 0;
  if (q =3D=3D 0)
    p =3D 1;
  signed char *n =3D &d;
  *n =3D 0;
  for (; c;)
    for (; i; i--)
      ;
  g =3D 0;
  for (; g <=3D 1; g++) {
    *n =3D **j;
    k[g] =3D 0 !=3D &m;
    *e =3D l && k[0];
  }
  if (p)
    printf(&b);
  for (; o < 4; o++) {
    a =3D d;
    if (p)
      printf(&b);
  }
  printf("%d\n", a);
}
$
$ gcc -O2 a.c && ./a.out
1
$ gcc -O3 a.c && ./a.out
0
$=