IIRC, Google engineers used fleetwide profiling to see that many cycles were being spent in memcmp() == 0 calls. They weren't checking the return value was any

IIRC, Google engineers used fleetwide profiling to see that many cycles were being spent in memcmp() == 0 calls. They weren't checking the return value was anything other than zero. If you don't care where two buffers mismatched, you can speed thing up by converting that idiom into a call to bcmp during optimization.