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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/101501] New: wrong code at -O3 on
 x86_64-linux-gnu
Date: Sun, 18 Jul 2021 22:50:36 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101501

            Bug ID: 101501
           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 appears to be a recent regression. Gcc-10 works fine.

$ gcc-trunk -v
gcc version 12.0.0 20210718 (experimental) [master revision
0103d18dfc9:a1cef02c5e3:853921378bfa149353b4e1c7dde5c02f80072ad7] (GCC)


$ gcc-trunk abc.c ; ./a.out
-1

$ gcc-trunk -O3 abc.c ; ./a.out
40


$ cat abc.c
char a =3D 55;
int main() {
  int b;
  char c;
d:
  c =3D a-- * 52;
  b =3D 3L * c;
  if (b)
    goto d;
  printf("%d\n", a);
}=