https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81759
--- Comment #2 from Daniel Fruzynski <bugzi...@poradnik-webmastera.com> ---
Looks that __builtin_ffs does not check if input value is nonzero at all.
Assembler code for following code also has unnecessary instructions:
[code]
unsigned int test(unsigned int n)
{
if (n == 0)
__builtin_unreachable();
return __builtin_ffs(n) - 1;
}
[/code]
