https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96921
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, thinking about expanding this further:
int f1(int n)
{
if (n&~63) __builtin_unreachable();
return 63 - n;
}
int f2(int n)
{
if (n&~63) __builtin_unreachable();
return 63 ^ n;
}
These two should be able to get the same code which happens on clang already.
Something like (but with the expansion of the +!, etc.)
(simplify
(minus INTEGER_CST@0 SSA_NAME@1)
(if (exact_power2(@0 + 1) && get_nonzero_bits(@1) == @0
(bit_xor @1 @0)))
