// Expect (SB), (FP), (PC), or (SP)
	p.get('(')
	reg := p.get(scanner.Ident).String()
	p.get(')')
	p.setPseudoRegister(a, reg, isStatic, prefix)
}

// setPseudoRegister sets the NAME field of addr for a pseudo-register reference such as (SB).
func (p *Parser) setPseudoRegister(addr *obj.Addr, reg string, isStatic bool, prefix rune) {
	if addr.Reg != 0 {
		p.errorf("internal error: reg %s already set in pseudo", reg)
	}
	switch reg {

	for i := arm64.REG_V0; i <= arm64.REG_V31; i++ {
		register[obj.Rconv(i)] = int16(i)
	}

	// System registers.
	for i := 0; i < len(arm64.SystemReg); i++ {
		register[arm64.SystemReg[i].Name] = arm64.SystemReg[i].Reg
	}

	register["LR"] = arm64.REGLINK

	// Pseudo-registers.
	register["SB"] = RSB
	register["FP"] = RFP
	register["PC"] = RPC
	register["SP"] = RSP
	// Avoid unintentionally clobbering g using R28.

// satisfies io.Seeker.
func TestReadTruncation(t *testing.T) {
	var ss []string
	for _, p := range []string{
		"testdata/gnu.tar",
		"testdata/ustar-file-reg.tar",
		"testdata/pax-path-hdr.tar",
		"testdata/sparse-formats.tar",
	} {
		buf, err := os.ReadFile(p)
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		ss = append(ss, string(buf))
	}

= Z2*Z2 * U1 = X1*T2 * H = X2*T1 * H = H-U1 * Z3 = Z1*Z2 * Z3 = Z3*H << store-out Z3 result reg.. could override Z1, if slices have same backing array * * S1 = Z2*T2 * S1 = Y1*S1 * R = Z1*T1 * R = Y2*R * R = R-S1 * * T1 = H*H * T2 = H*T1 * U1 = U1*T1 * * X3 = R*R * X3 = X3-T2 * T1 = 2*U1 * X3 = X3-T1 << store-out X3 result reg * * T2 = S1*T2 * Y3 = U1-X3 * Y3 = R*Y3 * Y3 = Y3-T2 << store-out Y3 result reg // X=Z1; Y=Z1; MUL; T- // T1 = Z1*Z1 // X- ; Y=T ; MUL; R=T // R = Z1*T1 // X=X2; Y- ; MUL;...