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From: "guojiufu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/102131] [12 Regression] wrong code at -O1 and
 above on x86_64-linux-gnu
Date: Tue, 31 Aug 2021 06:34:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102131

--- Comment #2 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
Thank you!

For this case, there are two exits, and through these two exits, different
niters(number of iterations) are calculated.  It fails to handle this kind =
of
case well.

In ivcanon pass, the edge on the condition was removed incorrectly.

int a;
int main() {
  unsigned b =3D 0;
  int c =3D 1;
  for (;b < 3; b++) {
    if (c < b)
      __builtin_abort ();
    c+=3D3;
  }
  return 0;
}=