export function w $f() {
@start
	%x0 =w loadsb $a
	# the extension must not be eliminated
	# even though the load already extended
	%x1 =l extsb %x0
	%c =w ceql %x1, -1
	ret %c
}

# >>> driver
# char a = -1;
# extern int f();
# int main() { return !(f() == 1); }
# <<<