https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94779
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
CC| |marxin at gcc dot gnu.org
Status|UNCONFIRMED |RESOLVED
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Note that each switch contains an implicit default label which is missing in
your code. So your function invokes an undefined behavior (when you use the
return value of the function) for values different from 0 and 1.
I recommend:
int f1(unsigned x)
{
switch (x)
{
case 0:
return 1;
case 1:
return 2;
default:
__builtin_unreachable ();
}
}
which is fully optimized to:
cmpl $1, %edi
movl $1, %eax
sbbl $-1, %eax
ret
