register[name] = int16(i)
	}
	for i := riscv.REG_F0; i <= riscv.REG_F31; i++ {
		name := fmt.Sprintf("F%d", i-riscv.REG_F0)
		register[name] = int16(i)
	}
	for i := riscv.REG_V0; i <= riscv.REG_V31; i++ {
		name := fmt.Sprintf("V%d", i-riscv.REG_V0)
		register[name] = int16(i)
	}

	// General registers with ABI names.
	register["ZERO"] = riscv.REG_ZERO
	register["RA"] = riscv.REG_RA
	register["SP"] = riscv.REG_SP

		if 0 <= n && n <= 31 {
			return arm64.REG_F0 + n, true
		}
	case "R":
		if 0 <= n && n <= 30 { // not 31
			return arm64.REG_R0 + n, true
		}
	case "V":
		if 0 <= n && n <= 31 {
			return arm64.REG_V0 + n, true
		}
	}
	return 0, false
}

// ARM64RegisterShift constructs an ARM64 register with shift operation.
func ARM64RegisterShift(reg, op, count int16) (int64, error) {