The test and-1.c has wrong logic. In the formula: y & ~(y & -y)The part (y & -y) is always a mask with one bit set, which corresponds to the least significant "1" bit in y. The final result is that bit, is set to zero (y & ~mask)There is no boolean simplification possible, and the compiler always producesa nand instruction.
The formula is equal to y & (y-1) , maybe the testcase is testing that? Segher
