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From: "zhendong.su at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/103376] [12 Regression] wrong code at -Os and
 above on x86_64-linux-gnu since r12-5453-ga944b5dec3adb28e
Date: Wed, 24 Nov 2021 07:09:17 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103376

--- Comment #7 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
A couple of additional tests for the same issue:

(1) at -Os and above

[622] % gcctk -O1 small.c; ./a.out
[623] % gcctk -Os small.c; ./a.out
Aborted
[624] % cat small.c
long a =3D 2653121401;
unsigned char b;
int c;
int main() {
  b =3D a;
  c =3D ~(((a ^ b) + 2) ^ 254);
  if (c > 1641845765)
    __builtin_abort();
  return 0;
}

(2) at -O2 and -O3

[511] % gcctk -Os small.c; ./a.out
[512] % gcctk -O2 small.c; ./a.out
Segmentation fault
[513] %=20
[513] % cat small.c
int printf(const char *, ...);
int a =3D 1, *b;
int main() {
  int c =3D a;
  if (a =3D=3D 2)
    printf("0");
  a =3D a ^ c;
  if (a)
    a++;
  if (a && *b)
    return a;
  return 0;
}=