[Bug tree-optimization/103184] [12 Regression] ICE caused by r12-5102

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103184

--- Comment #3 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Hongtao.liu from comment #2)
> When mask is integer_cst, it not safe to replace_uses_by (use_lhs, lhs);
Similar ICE for variable mask.

int
tbit0 (_Atomic int* a, int n)
{
#define BIT (0x01 << n)
  return atomic_fetch_or(a, BIT) & BIT;
#undef BIT 
}