}
			a.Reg = arm64.REG_UXTX + Rnum
		case "SXTB":
			if a.Type == obj.TYPE_MEM {
				return errors.New("invalid shift for the register offset addressing mode")
			}
			a.Reg = arm64.REG_SXTB + Rnum
		case "SXTH":
			if a.Type == obj.TYPE_MEM {
				return errors.New("invalid shift for the register offset addressing mode")
			}
			a.Reg = arm64.REG_SXTH + Rnum
		case "SXTW":
			if a.Type == obj.TYPE_MEM {

<code>R0.SXTB&lt;&lt;imm</code>: left shift the result of <code>R0.SXTB</code> by <code>imm</code> bits.
The <code>imm</code> value can be 0, 1, 2, 3, or 4.
The other extensions include <code>SXTH</code> (16-bit), <code>SXTW</code> (32-bit), and <code>SXTX</code> (64-bit).
</li>

<li>

	SUBW	R1.UXTX<<1, R3, R2              // 6264214b
	SUBS	R3.UXTX, R8, R9                 // 096123eb
	SUBSW	R17.UXTH, R15, R21              // f521316b
	SUBW	ZR<<14, R19, R13                // 6d3a1f4b
	CMP	R2.SXTH, R13                    // bfa122eb
	CMN	R1.SXTX<<2, R10                 // 5fe921ab
	CMPW	R2.UXTH<<3, R11                 // 7f2d226b
	CMNW	R1.SXTB, R9                     // 3f81212b