func bitSetTest(x int) bool {
	// amd64:"ANDL\t[$]9, AX"
	// amd64:"CMPQ\tAX, [$]9"
	return x&9 == 9
}

// mask contiguous one bits
func cont1Mask64U(x uint64) uint64 {
	// s390x:"RISBGZ\t[$]16, [$]47, [$]0,"
	return x & 0x0000ffffffff0000
}

// mask contiguous zero bits
func cont0Mask64U(x uint64) uint64 {
	// s390x:"RISBGZ\t[$]48, [$]15, [$]0,"
	return x & 0xffff00000000ffff
}

		me = 32 - bits.TrailingZeros32(uint32(mask))
		mbn = bits.LeadingZeros32(^uint32(mask))
		men = 32 - bits.TrailingZeros32(^uint32(mask))
	} else {
		mb = bits.LeadingZeros64(uint64(mask))
		me = 64 - bits.TrailingZeros64(uint64(mask))
		mbn = bits.LeadingZeros64(^uint64(mask))
		men = 64 - bits.TrailingZeros64(^uint64(mask))
	}
	// Check for a wrapping mask (e.g bits at 0 and 63)

	// n must always be a multiple of 8, since gcBits is
	// always rounded up 8 bytes.
	for _, n := range []int{8, 16, 32, 64, 128} {
		b.Run(fmt.Sprintf("bits=%d", n*8), func(b *testing.B) {
			// Initialize a new byte slice with pseduo-random data.
			bits := make([]byte, n)
			rand.Read(bits)

			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				runtime.MSpanCountAlloc(s, bits)
			}
		})
	}
}