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From: "qrzhang at gatech dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/101001] New: wrong code at -O3 on
 x86_64-linux-gnu
Date: Wed, 09 Jun 2021 19:37:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101001

            Bug ID: 101001
           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: ---

It affects gcc-8 to the trunk. Gcc-7 works fine.



$ gcc-trunk -v
gcc version 12.0.0 20210609 (experimental) [master revision
174e75a2107:3b61ba37fe1:5bfcfe3087eb05b76395c9efbfc1abbf3f9e1a03] (GCC)


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


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


$ cat abc.c
int a;
volatile char b;
int main() {
  char c;
  int d, f =3D 5;
  short e;
  e =3D 0;
  for (; e !=3D -15; e--) {
    d =3D 0;
    for (; d > -16; d =3D d - 4) {
      f || b;
      c =3D 0;
      for (; c !=3D 2; c =3D c - 3)
        f =3D 0;
    }
  }
  printf("%X\n", a);
}=