func rshConst64x32(v int64) int64 {
	// ppc64x:"SRAD"
	// riscv64:"SRAI\t",-"OR",-"SLTIU"
	return v >> uint32(33)
}

// ------------------ //
//   masked shifts    //
// ------------------ //

func lshMask64x64(v int64, s uint64) int64 {
	// arm64:"LSL",-"AND"
	// ppc64x:"RLDICL",-"ORN",-"ISEL"
	// riscv64:"SLL",-"AND\t",-"SLTIU"
	// s390x:-"RISBGZ",-"AND",-"LOCGR"
	return v << (s & 63)
}