[Bug tree-optimization/100539] New: wrong code at -Os and above with "-fno-dce -fno-inline-small-functions -fno-tree-dce"

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100539

            Bug ID: 100539
           Summary: wrong code at -Os and above with "-fno-dce
                    -fno-inline-small-functions -fno-tree-dce"
           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: ---

[514] % 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/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-languages=c,c++
--disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20210511 (experimental) [master revision
15e6b45c9ad:45dc47d4720:cf43636a74a028daf2024b33d1915274a2ff9655] (GCC) 
[515] % 
[515] % gcctk -Os small.c; ./a.out
[516] % 
[516] % gcctk -Os -fno-dce -fno-inline-small-functions -fno-tree-dce small.c
[517] % ./a.out
Segmentation fault
[518] % 
[518] % cat small.c
int a, b;
static void c(int *d) {
  int e = 0;
  for (; a < 1; a++)
    e |= (b == *d);
}
int main() {
  int g = 0;
  c(&g);
  return 0;
}