Golang obj.Link類代碼示例

func nacladdr(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
	if p.As == ALEAL || p.As == ALEAQ {
		return
	}

	if a.Reg == REG_BP {
		ctxt.Diag("invalid address: %v", p)
		return
	}

	if a.Reg == REG_TLS {
		a.Reg = REG_BP
	}
	if a.Type == obj.TYPE_MEM && a.Name == obj.NAME_NONE {
		switch a.Reg {
		// all ok
		case REG_BP, REG_SP, REG_R15:
			break

		default:
			if a.Index != REG_NONE {
				ctxt.Diag("invalid address %v", p)
			}
			a.Index = a.Reg
			if a.Index != REG_NONE {
				a.Scale = 1
			}
			a.Reg = REG_R15
		}
	}
}

func follow(ctxt *obj.Link, s *obj.LSym) {
	ctxt.Cursym = s

	firstp := ctxt.NewProg()
	lastp := firstp
	xfol(ctxt, s.Text, &lastp)
	lastp.Link = nil
	s.Text = firstp.Link
}

func initdiv(ctxt *obj.Link) {
	if ctxt.Sym_div != nil {
		return
	}
	ctxt.Sym_div = obj.Linklookup(ctxt, "_div", 0)
	ctxt.Sym_divu = obj.Linklookup(ctxt, "_divu", 0)
	ctxt.Sym_mod = obj.Linklookup(ctxt, "_mod", 0)
	ctxt.Sym_modu = obj.Linklookup(ctxt, "_modu", 0)
}

func oplook(ctxt *obj.Link, p *obj.Prog) *Optab {
	if oprange[AOR&obj.AMask].start == nil {
		buildop(ctxt)
	}

	a1 := int(p.Optab)
	if a1 != 0 {
		return &optab[a1-1:][0]
	}
	a1 = int(p.From.Class)
	if a1 == 0 {
		a1 = aclass(ctxt, &p.From) + 1
		p.From.Class = int8(a1)
	}

	a1--
	a3 := int(p.To.Class)
	if a3 == 0 {
		a3 = aclass(ctxt, &p.To) + 1
		p.To.Class = int8(a3)
	}

	a3--
	a2 := C_NONE
	if p.Reg != 0 {
		a2 = C_REG
	}

	//print("oplook %P %d %d %d\n", p, a1, a2, a3);
	r0 := p.As & obj.AMask

	o := oprange[r0].start
	if o == nil {
		o = oprange[r0].stop /* just generate an error */
	}
	e := oprange[r0].stop
	c1 := xcmp[a1][:]
	c3 := xcmp[a3][:]
	for ; -cap(o) < -cap(e); o = o[1:] {
		if int(o[0].a2) == a2 {
			if c1[o[0].a1] != 0 {
				if c3[o[0].a3] != 0 {
					p.Optab = uint16((-cap(o) + cap(optab)) + 1)
					return &o[0]
				}
			}
		}
	}

	ctxt.Diag("illegal combination %v %v %v %v", obj.Aconv(int(p.As)), DRconv(a1), DRconv(a2), DRconv(a3))
	prasm(p)
	if o == nil {
		o = optab
	}
	return &o[0]
}

func addnop(ctxt *obj.Link, p *obj.Prog) {
	q := ctxt.NewProg()
	// we want to use the canonical NOP (SLL $0,R0,R0) here,
	// however, as the assembler will always replace $0
	// as R0, we have to resort to manually encode the SLL
	// instruction as WORD $0.
	q.As = AWORD
	q.Lineno = p.Lineno
	q.From.Type = obj.TYPE_CONST
	q.From.Name = obj.NAME_NONE
	q.From.Offset = 0

	q.Link = p.Link
	p.Link = q
}

func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	// TODO(minux): add morestack short-cuts with small fixed frame-size.
	ctxt.Cursym = cursym

	// a switch for enabling/disabling instruction scheduling
	nosched := true

	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}

	p := cursym.Text
	textstksiz := p.To.Offset

	cursym.Args = p.To.Val.(int32)
	cursym.Locals = int32(textstksiz)

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 * expand BECOME pseudo
	 */
	if ctxt.Debugvlog != 0 {
		fmt.Fprintf(ctxt.Bso, "%5.2f noops\n", obj.Cputime())
	}
	ctxt.Bso.Flush()

	var q *obj.Prog
	var q1 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		/* too hard, just leave alone */
		case obj.ATEXT:
			q = p

			p.Mark |= LABEL | LEAF | SYNC
			if p.Link != nil {
				p.Link.Mark |= LABEL
			}

		/* too hard, just leave alone */
		case AMOVW,
			AMOVV:
			q = p
			if p.To.Type == obj.TYPE_REG && p.To.Reg >= REG_SPECIAL {
				p.Mark |= LABEL | SYNC
				break
			}
			if p.From.Type == obj.TYPE_REG && p.From.Reg >= REG_SPECIAL {
				p.Mark |= LABEL | SYNC
			}

		/* too hard, just leave alone */
		case ASYSCALL,
			AWORD,
			ATLBWR,
			ATLBWI,
			ATLBP,
			ATLBR:
			q = p
			p.Mark |= LABEL | SYNC

		case ANOR:
			q = p
			if p.To.Type == obj.TYPE_REG {
				if p.To.Reg == REGZERO {
					p.Mark |= LABEL | SYNC
				}
			}

		case ABGEZAL,
			ABLTZAL,
			AJAL,
			obj.ADUFFZERO,
			obj.ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case AJMP,
			ABEQ,
			ABGEZ,
			ABGTZ,
			ABLEZ,
			ABLTZ,
			ABNE,
			ABFPT, ABFPF:
			if p.As == ABFPT || p.As == ABFPF {
				// We don't treat ABFPT and ABFPF as branches here,
				// so that we will always fill nop (0x0) in their
				// delay slot during assembly.
				// This is to workaround a kernel FPU emulator bug
				// where it uses the user stack to simulate the
				// instruction in the delay slot if it's not 0x0,
				// and somehow that leads to SIGSEGV when the kernel
				// jump to the stack.
				p.Mark |= SYNC
			} else {
				p.Mark |= BRANCH
			}
//.........這裏部分代碼省略.........

func progedit(ctxt *obj.Link, p *obj.Prog) {
	p.From.Class = 0
	p.To.Class = 0

	// Rewrite B/BL to symbol as TYPE_BRANCH.
	switch p.As {
	case AB,
		ABL,
		obj.ADUFFZERO,
		obj.ADUFFCOPY:
		if p.To.Type == obj.TYPE_MEM && (p.To.Name == obj.NAME_EXTERN || p.To.Name == obj.NAME_STATIC) && p.To.Sym != nil {
			p.To.Type = obj.TYPE_BRANCH
		}
	}

	// Replace TLS register fetches on older ARM procesors.
	switch p.As {
	// Treat MRC 15, 0, <reg>, C13, C0, 3 specially.
	case AMRC:
		if p.To.Offset&0xffff0fff == 0xee1d0f70 {
			// Because the instruction might be rewriten to a BL which returns in R0
			// the register must be zero.
			if p.To.Offset&0xf000 != 0 {
				ctxt.Diag("%v: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Line())
			}

			if ctxt.Goarm < 7 {
				// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
				if progedit_tlsfallback == nil {
					progedit_tlsfallback = obj.Linklookup(ctxt, "runtime.read_tls_fallback", 0)
				}

				// MOVW	LR, R11
				p.As = AMOVW

				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGLINK
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGTMP

				// BL	runtime.read_tls_fallback(SB)
				p = obj.Appendp(ctxt, p)

				p.As = ABL
				p.To.Type = obj.TYPE_BRANCH
				p.To.Sym = progedit_tlsfallback
				p.To.Offset = 0

				// MOVW	R11, LR
				p = obj.Appendp(ctxt, p)

				p.As = AMOVW
				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGTMP
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGLINK
				break
			}
		}

		// Otherwise, MRC/MCR instructions need no further treatment.
		p.As = AWORD
	}

	// Rewrite float constants to values stored in memory.
	switch p.As {
	case AMOVF:
		if p.From.Type == obj.TYPE_FCONST && chipfloat5(ctxt, p.From.Val.(float64)) < 0 && (chipzero5(ctxt, p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
			f32 := float32(p.From.Val.(float64))
			i32 := math.Float32bits(f32)
			literal := fmt.Sprintf("$f32.%08x", i32)
			s := obj.Linklookup(ctxt, literal, 0)
			p.From.Type = obj.TYPE_MEM
			p.From.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}

	case AMOVD:
		if p.From.Type == obj.TYPE_FCONST && chipfloat5(ctxt, p.From.Val.(float64)) < 0 && (chipzero5(ctxt, p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
			i64 := math.Float64bits(p.From.Val.(float64))
			literal := fmt.Sprintf("$f64.%016x", i64)
			s := obj.Linklookup(ctxt, literal, 0)
			p.From.Type = obj.TYPE_MEM
			p.From.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}
	}

	if ctxt.Flag_dynlink {
		rewriteToUseGot(ctxt, p)
	}
}

func softfloat(ctxt *obj.Link, cursym *obj.LSym) {
	if ctxt.Goarm > 5 {
		return
	}

	symsfloat := obj.Linklookup(ctxt, "_sfloat", 0)

	wasfloat := 0
	for p := cursym.Text; p != nil; p = p.Link {
		if p.Pcond != nil {
			p.Pcond.Mark |= LABEL
		}
	}
	var next *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case AMOVW:
			if isfloatreg(&p.To) || isfloatreg(&p.From) {
				goto soft
			}
			goto notsoft

		case AMOVWD,
			AMOVWF,
			AMOVDW,
			AMOVFW,
			AMOVFD,
			AMOVDF,
			AMOVF,
			AMOVD,
			ACMPF,
			ACMPD,
			AADDF,
			AADDD,
			ASUBF,
			ASUBD,
			AMULF,
			AMULD,
			ADIVF,
			ADIVD,
			ASQRTF,
			ASQRTD,
			AABSF,
			AABSD:
			goto soft

		default:
			goto notsoft
		}

	soft:
		if wasfloat == 0 || (p.Mark&LABEL != 0) {
			next = ctxt.NewProg()
			*next = *p

			// BL _sfloat(SB)
			*p = obj.Prog{}
			p.Ctxt = ctxt
			p.Link = next
			p.As = ABL
			p.To.Type = obj.TYPE_BRANCH
			p.To.Sym = symsfloat
			p.Lineno = next.Lineno

			p = next
			wasfloat = 1
		}

		continue

	notsoft:
		wasfloat = 0
	}
}

// Rewrite p, if necessary, to access global data via the global offset table.
func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
	if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
		//     ADUFFxxx $offset
		// becomes
		//     MOVW [email protected], R9
		//     ADD $offset, R9
		//     CALL (R9)
		var sym *obj.LSym
		if p.As == obj.ADUFFZERO {
			sym = obj.Linklookup(ctxt, "runtime.duffzero", 0)
		} else {
			sym = obj.Linklookup(ctxt, "runtime.duffcopy", 0)
		}
		offset := p.To.Offset
		p.As = AMOVW
		p.From.Type = obj.TYPE_MEM
		p.From.Name = obj.NAME_GOTREF
		p.From.Sym = sym
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_R9
		p.To.Name = obj.NAME_NONE
		p.To.Offset = 0
		p.To.Sym = nil
		p1 := obj.Appendp(ctxt, p)
		p1.As = AADD
		p1.From.Type = obj.TYPE_CONST
		p1.From.Offset = offset
		p1.To.Type = obj.TYPE_REG
		p1.To.Reg = REG_R9
		p2 := obj.Appendp(ctxt, p1)
		p2.As = obj.ACALL
		p2.To.Type = obj.TYPE_MEM
		p2.To.Reg = REG_R9
		return
	}

	// We only care about global data: NAME_EXTERN means a global
	// symbol in the Go sense, and p.Sym.Local is true for a few
	// internally defined symbols.
	if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
		// MOVW $sym, Rx becomes MOVW [email protected], Rx
		// MOVW $sym+<off>, Rx becomes MOVW [email protected], Rx; ADD <off>, Rx
		if p.As != AMOVW {
			ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
		}
		if p.To.Type != obj.TYPE_REG {
			ctxt.Diag("do not know how to handle LEAQ-type insn to non-register in %v with -dynlink", p)
		}
		p.From.Type = obj.TYPE_MEM
		p.From.Name = obj.NAME_GOTREF
		if p.From.Offset != 0 {
			q := obj.Appendp(ctxt, p)
			q.As = AADD
			q.From.Type = obj.TYPE_CONST
			q.From.Offset = p.From.Offset
			q.To = p.To
			p.From.Offset = 0
		}
	}
	if p.From3 != nil && p.From3.Name == obj.NAME_EXTERN {
		ctxt.Diag("don't know how to handle %v with -dynlink", p)
	}
	var source *obj.Addr
	// MOVx sym, Ry becomes MOVW [email protected], R9; MOVx (R9), Ry
	// MOVx Ry, sym becomes MOVW [email protected], R9; MOVx Ry, (R9)
	// An addition may be inserted between the two MOVs if there is an offset.
	if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
		if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local {
			ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
		}
		source = &p.From
	} else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local {
		source = &p.To
	} else {
		return
	}
	if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
		return
	}
	if source.Sym.Type == obj.STLSBSS {
		return
	}
	if source.Type != obj.TYPE_MEM {
		ctxt.Diag("don't know how to handle %v with -dynlink", p)
	}
	p1 := obj.Appendp(ctxt, p)
	p2 := obj.Appendp(ctxt, p1)

	p1.As = AMOVW
	p1.From.Type = obj.TYPE_MEM
	p1.From.Sym = source.Sym
	p1.From.Name = obj.NAME_GOTREF
	p1.To.Type = obj.TYPE_REG
	p1.To.Reg = REG_R9

	p2.As = p.As
	p2.From = p.From
	p2.To = p.To
	if p.From.Name == obj.NAME_EXTERN {
//.........這裏部分代碼省略.........

func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	autosize := int32(0)

	ctxt.Cursym = cursym

	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}

	softfloat(ctxt, cursym)

	p := cursym.Text
	autoffset := int32(p.To.Offset)
	if autoffset < 0 {
		autoffset = 0
	}
	cursym.Locals = autoffset
	cursym.Args = p.To.Val.(int32)

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 * expand BECOME pseudo
	 */
	var q1 *obj.Prog
	var q *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case obj.ATEXT:
			p.Mark |= LEAF

		case obj.ARET:
			break

		case ADIV, ADIVU, AMOD, AMODU:
			q = p
			if ctxt.Sym_div == nil {
				initdiv(ctxt)
			}
			cursym.Text.Mark &^= LEAF
			continue

		case obj.ANOP:
			q1 = p.Link
			q.Link = q1 /* q is non-nop */
			if q1 != nil {
				q1.Mark |= p.Mark
			}
			continue

		case ABL,
			ABX,
			obj.ADUFFZERO,
			obj.ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case AB,
			ABEQ,
			ABNE,
			ABCS,
			ABHS,
			ABCC,
			ABLO,
			ABMI,
			ABPL,
			ABVS,
			ABVC,
			ABHI,
			ABLS,
			ABGE,
			ABLT,
			ABGT,
			ABLE:
			q1 = p.Pcond
			if q1 != nil {
				for q1.As == obj.ANOP {
					q1 = q1.Link
					p.Pcond = q1
				}
			}
		}

		q = p
	}

	var o int
	var p1 *obj.Prog
	var p2 *obj.Prog
	var q2 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		o = int(p.As)
		switch o {
		case obj.ATEXT:
			autosize = int32(p.To.Offset + 4)
			if autosize <= 4 {
				if cursym.Text.Mark&LEAF != 0 {
					p.To.Offset = -4
					autosize = 0
//.........這裏部分代碼省略.........

func vregoff(ctxt *obj.Link, a *obj.Addr) int64 {
	ctxt.Instoffset = 0
	aclass(ctxt, a)
	return ctxt.Instoffset
}

func progedit(ctxt *obj.Link, p *obj.Prog) {
	// Maintain information about code generation mode.
	if ctxt.Mode == 0 {
		ctxt.Mode = ctxt.Arch.Regsize * 8
	}
	p.Mode = int8(ctxt.Mode)

	switch p.As {
	case AMODE:
		if p.From.Type == obj.TYPE_CONST || (p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_NONE) {
			switch int(p.From.Offset) {
			case 16, 32, 64:
				ctxt.Mode = int(p.From.Offset)
			}
		}
		obj.Nopout(p)
	}

	// Thread-local storage references use the TLS pseudo-register.
	// As a register, TLS refers to the thread-local storage base, and it
	// can only be loaded into another register:
	//
	//         MOVQ TLS, AX
	//
	// An offset from the thread-local storage base is written off(reg)(TLS*1).
	// Semantically it is off(reg), but the (TLS*1) annotation marks this as
	// indexing from the loaded TLS base. This emits a relocation so that
	// if the linker needs to adjust the offset, it can. For example:
	//
	//         MOVQ TLS, AX
	//         MOVQ 0(AX)(TLS*1), CX // load g into CX
	//
	// On systems that support direct access to the TLS memory, this
	// pair of instructions can be reduced to a direct TLS memory reference:
	//
	//         MOVQ 0(TLS), CX // load g into CX
	//
	// The 2-instruction and 1-instruction forms correspond to the two code
	// sequences for loading a TLS variable in the local exec model given in "ELF
	// Handling For Thread-Local Storage".
	//
	// We apply this rewrite on systems that support the 1-instruction form.
	// The decision is made using only the operating system and the -shared flag,
	// not the link mode. If some link modes on a particular operating system
	// require the 2-instruction form, then all builds for that operating system
	// will use the 2-instruction form, so that the link mode decision can be
	// delayed to link time.
	//
	// In this way, all supported systems use identical instructions to
	// access TLS, and they are rewritten appropriately first here in
	// liblink and then finally using relocations in the linker.
	//
	// When -shared is passed, we leave the code in the 2-instruction form but
	// assemble (and relocate) them in different ways to generate the initial
	// exec code sequence. It's a bit of a fluke that this is possible without
	// rewriting the instructions more comprehensively, and it only does because
	// we only support a single TLS variable (g).

	if canuse1insntls(ctxt) {
		// Reduce 2-instruction sequence to 1-instruction sequence.
		// Sequences like
		//	MOVQ TLS, BX
		//	... off(BX)(TLS*1) ...
		// become
		//	NOP
		//	... off(TLS) ...
		//
		// TODO(rsc): Remove the Hsolaris special case. It exists only to
		// guarantee we are producing byte-identical binaries as before this code.
		// But it should be unnecessary.
		if (p.As == AMOVQ || p.As == AMOVL) && p.From.Type == obj.TYPE_REG && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_R15 && ctxt.Headtype != obj.Hsolaris {
			obj.Nopout(p)
		}
		if p.From.Type == obj.TYPE_MEM && p.From.Index == REG_TLS && REG_AX <= p.From.Reg && p.From.Reg <= REG_R15 {
			p.From.Reg = REG_TLS
			p.From.Scale = 0
			p.From.Index = REG_NONE
		}

		if p.To.Type == obj.TYPE_MEM && p.To.Index == REG_TLS && REG_AX <= p.To.Reg && p.To.Reg <= REG_R15 {
			p.To.Reg = REG_TLS
			p.To.Scale = 0
			p.To.Index = REG_NONE
		}
	} else {
		// load_g_cx, below, always inserts the 1-instruction sequence. Rewrite it
		// as the 2-instruction sequence if necessary.
		//	MOVQ 0(TLS), BX
		// becomes
		//	MOVQ TLS, BX
		//	MOVQ 0(BX)(TLS*1), BX
		if (p.As == AMOVQ || p.As == AMOVL) && p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_R15 {
			q := obj.Appendp(ctxt, p)
			q.As = p.As
			q.From = p.From
			q.From.Type = obj.TYPE_MEM
			q.From.Reg = p.To.Reg
			q.From.Index = REG_TLS
			q.From.Scale = 2 // TODO: use 1
			q.To = p.To
//.........這裏部分代碼省略.........

func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	ctxt.Cursym = cursym

	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}

	p := cursym.Text
	textstksiz := p.To.Offset
	aoffset := int32(textstksiz)

	cursym.Args = p.To.Val.(int32)
	cursym.Locals = int32(textstksiz)

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 */
	ctxt.Bso.Flush()
	q := (*obj.Prog)(nil)
	var q1 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case obj.ATEXT:
			p.Mark |= LEAF

		case obj.ARET:
			break

		case obj.ANOP:
			q1 = p.Link
			q.Link = q1 /* q is non-nop */
			q1.Mark |= p.Mark
			continue

		case ABL,
			obj.ADUFFZERO,
			obj.ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case ACBNZ,
			ACBZ,
			ACBNZW,
			ACBZW,
			ATBZ,
			ATBNZ,
			AB,
			ABEQ,
			ABNE,
			ABCS,
			ABHS,
			ABCC,
			ABLO,
			ABMI,
			ABPL,
			ABVS,
			ABVC,
			ABHI,
			ABLS,
			ABGE,
			ABLT,
			ABGT,
			ABLE,
			AADR, /* strange */
			AADRP:
			q1 = p.Pcond

			if q1 != nil {
				for q1.As == obj.ANOP {
					q1 = q1.Link
					p.Pcond = q1
				}
			}

			break
		}

		q = p
	}

	var o int
	var q2 *obj.Prog
	var retjmp *obj.LSym
	for p := cursym.Text; p != nil; p = p.Link {
		o = int(p.As)
		switch o {
		case obj.ATEXT:
			cursym.Text = p
			if textstksiz < 0 {
				ctxt.Autosize = 0
			} else {
				ctxt.Autosize = int32(textstksiz + 8)
			}
			if (cursym.Text.Mark&LEAF != 0) && ctxt.Autosize <= 8 {
				ctxt.Autosize = 0
			} else if ctxt.Autosize&(16-1) != 0 {
				// The frame includes an LR.
				// If the frame size is 8, it's only an LR,
//.........這裏部分代碼省略.........

// Rewrite p, if necessary, to access global data via the global offset table.
func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
	var add, lea, mov, reg int16
	if p.Mode == 64 {
		add = AADDQ
		lea = ALEAQ
		mov = AMOVQ
		reg = REG_R15
	} else {
		add = AADDL
		lea = ALEAL
		mov = AMOVL
		reg = REG_CX
	}

	if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
		//     ADUFFxxx $offset
		// becomes
		//     $MOV [email protected], $reg
		//     $ADD $offset, $reg
		//     CALL $reg
		var sym *obj.LSym
		if p.As == obj.ADUFFZERO {
			sym = obj.Linklookup(ctxt, "runtime.duffzero", 0)
		} else {
			sym = obj.Linklookup(ctxt, "runtime.duffcopy", 0)
		}
		offset := p.To.Offset
		p.As = mov
		p.From.Type = obj.TYPE_MEM
		p.From.Name = obj.NAME_GOTREF
		p.From.Sym = sym
		p.To.Type = obj.TYPE_REG
		p.To.Reg = reg
		p.To.Offset = 0
		p.To.Sym = nil
		p1 := obj.Appendp(ctxt, p)
		p1.As = add
		p1.From.Type = obj.TYPE_CONST
		p1.From.Offset = offset
		p1.To.Type = obj.TYPE_REG
		p1.To.Reg = reg
		p2 := obj.Appendp(ctxt, p1)
		p2.As = obj.ACALL
		p2.To.Type = obj.TYPE_REG
		p2.To.Reg = reg
	}

	// We only care about global data: NAME_EXTERN means a global
	// symbol in the Go sense, and p.Sym.Local is true for a few
	// internally defined symbols.
	if p.As == lea && p.From.Type == obj.TYPE_MEM && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
		// $LEA sym, Rx becomes $MOV $sym, Rx which will be rewritten below
		p.As = mov
		p.From.Type = obj.TYPE_ADDR
	}
	if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local {
		// $MOV $sym, Rx becomes $MOV [email protected], Rx
		// $MOV $sym+<off>, Rx becomes $MOV [email protected], Rx; $ADD <off>, Rx
		// On 386 only, more complicated things like PUSHL $sym become $MOV [email protected], CX; PUSHL CX
		cmplxdest := false
		pAs := p.As
		var dest obj.Addr
		if p.To.Type != obj.TYPE_REG || pAs != mov {
			if p.Mode == 64 {
				ctxt.Diag("do not know how to handle LEA-type insn to non-register in %v with -dynlink", p)
			}
			cmplxdest = true
			dest = p.To
			p.As = mov
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REG_CX
			p.To.Sym = nil
			p.To.Name = obj.NAME_NONE
		}
		p.From.Type = obj.TYPE_MEM
		p.From.Name = obj.NAME_GOTREF
		q := p
		if p.From.Offset != 0 {
			q = obj.Appendp(ctxt, p)
			q.As = add
			q.From.Type = obj.TYPE_CONST
			q.From.Offset = p.From.Offset
			q.To = p.To
			p.From.Offset = 0
		}
		if cmplxdest {
			q = obj.Appendp(ctxt, q)
			q.As = pAs
			q.To = dest
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REG_CX
		}
	}
	if p.From3 != nil && p.From3.Name == obj.NAME_EXTERN {
		ctxt.Diag("don't know how to handle %v with -dynlink", p)
	}
	var source *obj.Addr
	// MOVx sym, Ry becomes $MOV [email protected], R15; MOVx (R15), Ry
	// MOVx Ry, sym becomes $MOV [email protected], R15; MOVx Ry, (R15)
//.........這裏部分代碼省略.........

func oprrr(ctxt *obj.Link, a int) uint32 {
	switch a {
	case AADD:
		return OP(4, 0)
	case AADDU:
		return OP(4, 1)
	case ASGT:
		return OP(5, 2)
	case ASGTU:
		return OP(5, 3)
	case AAND:
		return OP(4, 4)
	case AOR:
		return OP(4, 5)
	case AXOR:
		return OP(4, 6)
	case ASUB:
		return OP(4, 2)
	case ASUBU:
		return OP(4, 3)
	case ANOR:
		return OP(4, 7)
	case ASLL:
		return OP(0, 4)
	case ASRL:
		return OP(0, 6)
	case ASRA:
		return OP(0, 7)
	case ASLLV:
		return OP(2, 4)
	case ASRLV:
		return OP(2, 6)
	case ASRAV:
		return OP(2, 7)
	case AADDV:
		return OP(5, 4)
	case AADDVU:
		return OP(5, 5)
	case ASUBV:
		return OP(5, 6)
	case ASUBVU:
		return OP(5, 7)
	case AREM,
		ADIV:
		return OP(3, 2)
	case AREMU,
		ADIVU:
		return OP(3, 3)
	case AMUL:
		return OP(3, 0)
	case AMULU:
		return OP(3, 1)
	case AREMV,
		ADIVV:
		return OP(3, 6)
	case AREMVU,
		ADIVVU:
		return OP(3, 7)
	case AMULV:
		return OP(3, 4)
	case AMULVU:
		return OP(3, 5)

	case AJMP:
		return OP(1, 0)
	case AJAL:
		return OP(1, 1)

	case ABREAK:
		return OP(1, 5)
	case ASYSCALL:
		return OP(1, 4)
	case ATLBP:
		return MMU(1, 0)
	case ATLBR:
		return MMU(0, 1)
	case ATLBWI:
		return MMU(0, 2)
	case ATLBWR:
		return MMU(0, 6)
	case ARFE:
		return MMU(2, 0)

	case ADIVF:
		return FPF(0, 3)
	case ADIVD:
		return FPD(0, 3)
	case AMULF:
		return FPF(0, 2)
	case AMULD:
		return FPD(0, 2)
	case ASUBF:
		return FPF(0, 1)
	case ASUBD:
		return FPD(0, 1)
	case AADDF:
		return FPF(0, 0)
	case AADDD:
		return FPD(0, 0)
	case ATRUNCFV:
//.........這裏部分代碼省略.........