[Bug tree-optimization/103860] New: wrong code at -O3 with -fPIC on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103860

            Bug ID: 103860
           Summary: wrong code at -O3 with -fPIC 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 GCC 5.4, and impact GCC 6.1 and later. 

[591] % 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 --disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20211228 (experimental) (GCC) 
[592] % 
[592] % gcctk -O3 small.c; ./a.out
[593] % gcctk -O2 -fPIC small.c; ./a.out
[594] % 
[594] % gcctk -O3 -fPIC small.c
[595] % ./a.out
Segmentation fault
[596] % 
[596] % cat small.c
char a(char b, char c) { return b + c; }
static int d, *e;
int f;
int main() {
  char l = -1;
  for (; l; l = a(l, 1)) {
    while (d < 0)
      ;
    if (d > 0) {
      f = 0;
      *e = 0;
    }
  }
  d = 0;
  return 0;
}