(MOVBZreg (RLWINM [r] y)) && mergePPC64AndRlwinm(0xFF,r) != 0 => (RLWINM [mergePPC64AndRlwinm(0xFF,r)] y)
(MOVHZreg (RLWINM [r] y)) && mergePPC64AndRlwinm(0xFFFF,r) != 0 => (RLWINM [mergePPC64AndRlwinm(0xFFFF,r)] y)
(MOVWZreg (RLWINM [r] y)) && mergePPC64MovwzregRlwinm(r) != 0 => (RLWINM [mergePPC64MovwzregRlwinm(r)] y)
(ANDconst [m] (RLWINM [r] y)) && mergePPC64AndRlwinm(uint32(m),r) != 0 => (RLWINM [mergePPC64AndRlwinm(uint32(m),r)] y)

	}
	return encodePPC64RotateMask(r_3, int64(mask_3), 32)
}

// Test if RLWINM feeding into an ANDconst can be merged. Return the encoded RLWINM constant,
// or 0 if they cannot be merged.
func mergePPC64AndRlwinm(mask uint32, rlw int64) int64 {
	r, _, _, mask_rlw := DecodePPC64RotateMask(rlw)
	mask_out := (mask_rlw & uint64(mask))

	// Verify the result is still a valid bitmask of <= 32 bits.