func bucketShift(b uint8) uintptr {
	// Masking the shift amount allows overflow checks to be elided.
	return uintptr(1) << (b & (goarch.PtrSize*8 - 1))
}

// bucketMask returns 1<<b - 1, optimized for code generation.
func bucketMask(b uint8) uintptr {
	return bucketShift(b) - 1
}

// tophash calculates the tophash value for hash.
func tophash(hash uintptr) uint8 {