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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/111652] New: wrong code at -O3 on
 x86_64-linux-gnu
Date: Sun, 01 Oct 2023 11:59:46 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111652

            Bug ID: 111652
           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: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

It appears to be a recent regression.

Compiler Explorer: https://godbolt.org/z/89h8W1Pvs

[505] % gcctk -v
Using built-in specs.
COLLECT_GCC=3Dgcctk
COLLECT_LTO_WRAPPER=3D/local/home/suz/suz-local/software/local/gcc-trunk/bi=
n/../libexec/gcc/x86_64-pc-linux-gnu/14.0.0/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
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231001 (experimental) (GCC)=20
[506] %=20
[506] % gcctk -O2 small.c; ./a.out
[507] %=20
[507] % gcctk -O3 small.c
[508] % ./a.out
Aborted
[509] %=20
[509] % cat small.c
volatile int a;
int b;
int main() {
  for (; b < 5; b +=3D 3) {
    b && a;
    if (b < 4)
      a--;
  }
  if (b !=3D 6)
    __builtin_abort();
  return 0;
}=