[Bug tree-optimization/114864] New: wrong code at -O1 with "-fno-tree-dce -fno-tree-fre" on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114864

            Bug ID: 114864
           Summary: wrong code at -O1 with "-fno-tree-dce -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: ---

This appears to be a regression from 11.*, and affects 12.* and later. 

Compiler Explorer: https://godbolt.org/z/TbYj469r3

[588] % 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/14.0.1/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 14.0.1 20240426 (experimental) (GCC) 
[589] % 
[589] % gcctk -O1 small.c; ./a.out
[590] % 
[590] % gcctk -O1 -fno-tree-dce -fno-tree-fre small.c
[591] % ./a.out
Segmentation fault
[592] % 
[592] % cat small.c
struct a {
  int b;
} const c;
void d(const struct a f) {}
void e(const struct a f) {
  f.b == 0 ? 1 : f.b;
  d(f);
}
int main() {
  e(c);
  return 0;
}