[Bug tree-optimization/115467] New: wrong code at -O1 with "-fno-tree-fre" on x86_64-linux-gnu

["zhendong.su at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115467

            Bug ID: 115467
           Summary: wrong code at -O1 with "-fno-tree-fre" 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 regression from 11.* and affects 12.* and later.

Compiler Explorer: https://godbolt.org/z/o5PMfan4v


[530] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/15.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 15.0.0 20240612 (experimental) (GCC) 
[531] % 
[531] % gcctk -O1 small.c; ./a.out
[532] % 
[532] % gcctk -O1 -fno-tree-fre small.c
[533] % ./a.out
Segmentation fault
[534] % 
[534] % cat small.c
struct a {
  int b;
} const c;
int d;
void e(const struct a p, int q) { d = 0; }
void f(const struct a g) {
  e(g, g.b);
  g.b ^ d;
}
int main() {
  f(c);
  return 0;
}