return nil
		}

		// MOV $c, R -> ADD $c, ZERO, R
		ins.as, ins.rs1, ins.rs2, ins.imm = AADDI, REG_ZERO, obj.REG_NONE, low

		// LUI is only necessary if the constant does not fit in 12 bits.
		if high != 0 {
			// LUI top20bits(c), R
			// ADD bottom12bits(c), R, R
			insLUI := &instruction{as: ALUI, rd: ins.rd, imm: high}
			inss = []*instruction{insLUI}
			if low != 0 {