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From: "zhendong.su at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107833] New: wrong code at -Os and above on
 x86_64-linux-gnu
Date: Wed, 23 Nov 2022 12:48:33 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107833

            Bug ID: 107833
           Summary: wrong code at -Os and above 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: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/Tc8vbearG

It appears to be a regression from 11.3.

[561] % gcctk -v
Using built-in specs.
COLLECT_GCC=3Dgcctk
COLLECT_LTO_WRAPPER=3D/local/suz-local/software/local/gcc-trunk/libexec/gcc=
/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=3Dyes --prefix=3D/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=3Dc,c++ --disable-werror --enable-mu=
ltilib
--with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20221123 (experimental) [master r13-4262-g1cac00d0138] (=
GCC)=20
[562] %=20
[562] % gcctk -O1 small.c; ./a.out
[563] %=20
[563] % gcctk -Os small.c
[564] % ./a.out
Segmentation fault
[565] %=20
[565] % cat small.c
int printf(const char *, ...);
int a, b[1] =3D {0}, c, *d =3D b, e, *f, g;
int main() {
  int h =3D 0;
  for (; a < 2; a++) {
    int i;
    for (g =3D 0; g < 2; g++)
      if (a < h) {
        e =3D i % 2;
        c =3D *f;
      }
    for (h =3D 0; h < 3; h++) {
      if (d)
        break;
      i--;
      printf("0");
    }
  }
  return 0;
}=