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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/112721] New: [14 Regression] Wrong code at
 -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c
Date: Mon, 27 Nov 2023 08:04:21 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: wrong-code
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X-Bugzilla-Who: shaohua.li at inf dot ethz.ch
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112721

            Bug ID: 112721
           Summary: [14 Regression] Wrong code at -O1/s on
                    x86_64-linux-gnu since r14-5831-gaae723d360c
           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: mjambor at suse dot cz
  Target Milestone: ---

gcc at -O1/s produces the wrong code.

Bisected to r14-5831-gaae723d360c

Compiler explorer: https://godbolt.org/z/671M9YPPj

$ cat a.c
int printf(const char *, ...);
struct a {
  int b;
};
int c, e;
long d;
unsigned *f(unsigned *g) {
  for (; c;)
    e =3D d;
  return g;
}
int main() {
  int *h;
  struct a i =3D {8};
  int *j =3D &i.b;
  h =3D f(j);
  *h =3D 0;
  printf("%d\n", i.b);
}
$
$ gcc -O0 a.c && ./a.out
0
$ gcc -O1 a.c && ./a.out
8
$=