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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/103417] New: wrong code at -O1 and above on
 x86_64-linux-gnu
Date: Wed, 24 Nov 2021 20:49:58 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103417

            Bug ID: 103417
           Summary: wrong code at -O1 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: ---

This appears to be a recent regression.

[557] % 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/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=3D/local/suz-local/software/local/gcc-trunk --enable-languages=3Dc=
,c++
--disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20211124 (experimental) [master r12-5505-g5deacf6058d] (=
GCC)=20
[558] %=20
[558] % gcctk -O0 small.c; ./a.out
[559] %=20
[559] % gcctk -O1 small.c
[560] % ./a.out
Aborted
[561] %=20
[561] % cat small.c
struct {
  int a : 8;
  int b : 24;
} c =3D {0, 1};
int main() {
  if (c.b && !c.b)
    __builtin_abort();
  return 0;
}=