// func getisar0() uint64
TEXT ·getisar0(SB),NOSPLIT,$0-8
	// get Instruction Set Attributes 0 into x0
	// mrs x0, ID_AA64ISAR0_EL1 = d5380600
	WORD	$0xd5380600
	MOVD	R0, ret+0(FP)
	RET

// func getisar1() uint64
TEXT ·getisar1(SB),NOSPLIT,$0-8
	// get Instruction Set Attributes 1 into x0
	// mrs x0, ID_AA64ISAR1_EL1 = d5380620
	WORD	$0xd5380620
	MOVD	R0, ret+0(FP)
	RET

// func getpfr0() uint64

		o2 |= LSL0_64

	case 35: /* mov SPR,R -> mrs */
		o1 = c.oprrr(p, AMRS)

		// SysRegEnc function returns the system register encoding and accessFlags.
		_, v, accessFlags := SysRegEnc(p.From.Reg)
		if v == 0 {
			c.ctxt.Diag("illegal system register:\n%v", p)
		}
		if (o1 & (v &^ (3 << 19))) != 0 {
			c.ctxt.Diag("MRS register value overlap\n%v", p)
		}
		if accessFlags&SR_READ == 0 {