Golang Prog.As方法代码示例

func stacksplitPost(ctxt *obj.Link, p *obj.Prog, pPre *obj.Prog, pPreempt *obj.Prog) *obj.Prog {

	// MOVD	LR, R5
	p = obj.Appendp(ctxt, p)
	pPre.Pcond = p
	p.As = AMOVD
	p.From.Type = obj.TYPE_REG
	p.From.Reg = REG_LR
	p.To.Type = obj.TYPE_REG
	p.To.Reg = REG_R5
	if pPreempt != nil {
		pPreempt.Pcond = p
	}

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

	p.As = ABL
	p.To.Type = obj.TYPE_BRANCH
	if ctxt.Cursym.Cfunc {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestackc", 0)
	} else if ctxt.Cursym.Text.From3.Offset&obj.NEEDCTXT == 0 {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
	} else {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack", 0)
	}

	// BR	start
	p = obj.Appendp(ctxt, p)

	p.As = ABR
	p.To.Type = obj.TYPE_BRANCH
	p.Pcond = ctxt.Cursym.Text.Link
	return p
}

// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog
	var p2 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(int(p.Lineno), "generated nil check")
		}

		// check is
		//	CMP arg, $0
		//	JNE 2(PC) (likely)
		//	MOV AX, 0
		p1 = gc.Ctxt.NewProg()

		p2 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		gc.Clearp(p2)
		p1.Link = p2
		p2.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p2.Lineno = p.Lineno
		p1.Pc = 9999
		p2.Pc = 9999
		p.As = int16(cmpptr)
		p.To.Type = obj.TYPE_CONST
		p.To.Offset = 0
		p1.As = x86.AJNE
		p1.From.Type = obj.TYPE_CONST
		p1.From.Offset = 1 // likely
		p1.To.Type = obj.TYPE_BRANCH
		p1.To.Val = p2.Link

		// crash by write to memory address 0.
		// if possible, since we know arg is 0, use 0(arg),
		// which will be shorter to encode than plain 0.
		p2.As = x86.AMOVL

		p2.From.Type = obj.TYPE_REG
		p2.From.Reg = x86.REG_AX
		if regtyp(&p.From) {
			p2.To.Type = obj.TYPE_MEM
			p2.To.Reg = p.From.Reg
		} else {
			p2.To.Type = obj.TYPE_MEM
			p2.To.Reg = x86.REG_NONE
		}

		p2.To.Offset = 0
	}
}

// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog
	var p2 *obj.Prog

	for p := (*obj.Prog)(firstp); p != nil; p = p.Link {
		if gc.Debug_checknil != 0 && gc.Ctxt.Debugvlog != 0 {
			fmt.Printf("expandchecks: %v\n", p)
		}
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(int(p.Lineno), "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatal("invalid nil check %v\n", p)
		}

		// check is
		//	CMP arg, ZR
		//	BNE 2(PC) [likely]
		//	MOVD ZR, 0(arg)
		p1 = gc.Ctxt.NewProg()

		p2 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		gc.Clearp(p2)
		p1.Link = p2
		p2.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p2.Lineno = p.Lineno
		p1.Pc = 9999
		p2.Pc = 9999
		p.As = arm64.ACMP
		p.Reg = arm64.REGZERO
		p1.As = arm64.ABNE

		//p1->from.type = TYPE_CONST;
		//p1->from.offset = 1; // likely
		p1.To.Type = obj.TYPE_BRANCH

		p1.To.Val = p2.Link

		// crash by write to memory address 0.
		p2.As = arm64.AMOVD
		p2.From.Type = obj.TYPE_REG
		p2.From.Reg = arm64.REGZERO
		p2.To.Type = obj.TYPE_MEM
		p2.To.Reg = p.From.Reg
		p2.To.Offset = 0
	}
}

func stacksplitPost(ctxt *obj.Link, p *obj.Prog, pPre *obj.Prog, pPreempt *obj.Prog, framesize int32) *obj.Prog {
	// Now we are at the end of the function, but logically
	// we are still in function prologue. We need to fix the
	// SP data and PCDATA.
	spfix := obj.Appendp(ctxt, p)
	spfix.As = obj.ANOP
	spfix.Spadj = -framesize

	pcdata := obj.Appendp(ctxt, spfix)
	pcdata.Lineno = ctxt.Cursym.Text.Lineno
	pcdata.Mode = ctxt.Cursym.Text.Mode
	pcdata.As = obj.APCDATA
	pcdata.From.Type = obj.TYPE_CONST
	pcdata.From.Offset = obj.PCDATA_StackMapIndex
	pcdata.To.Type = obj.TYPE_CONST
	pcdata.To.Offset = -1 // pcdata starts at -1 at function entry

	// MOVD	LR, R5
	p = obj.Appendp(ctxt, pcdata)
	pPre.Pcond = p
	p.As = AMOVD
	p.From.Type = obj.TYPE_REG
	p.From.Reg = REG_LR
	p.To.Type = obj.TYPE_REG
	p.To.Reg = REG_R5
	if pPreempt != nil {
		pPreempt.Pcond = p
	}

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

	p.As = ABL
	p.To.Type = obj.TYPE_BRANCH
	if ctxt.Cursym.Cfunc {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestackc", 0)
	} else if ctxt.Cursym.Text.From3.Offset&obj.NEEDCTXT == 0 {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
	} else {
		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack", 0)
	}

	// BR	start
	p = obj.Appendp(ctxt, p)

	p.As = ABR
	p.To.Type = obj.TYPE_BRANCH
	p.Pcond = ctxt.Cursym.Text.Link
	return p
}

func outgcode(a int, g1 *obj.Addr, reg int, g2, g3 *obj.Addr) {
	var p *obj.Prog
	var pl *obj.Plist

	if asm.Pass == 1 {
		goto out
	}

	p = asm.Ctxt.NewProg()
	p.As = int16(a)
	p.Lineno = stmtline
	if nosched != 0 {
		p.Mark |= ppc64.NOSCHED
	}
	p.From = *g1
	p.Reg = int16(reg)
	p.From3 = *g2
	p.To = *g3
	p.Pc = int64(asm.PC)

	if lastpc == nil {
		pl = obj.Linknewplist(asm.Ctxt)
		pl.Firstpc = p
	} else {
		lastpc.Link = p
	}
	lastpc = p

out:
	if a != obj.AGLOBL && a != obj.ADATA {
		asm.PC++
	}
}

func outcode(a int, g2 *Addr2) {
	var p *obj.Prog
	var pl *obj.Plist

	if asm.Pass == 1 {
		goto out
	}

	p = new(obj.Prog)
	*p = obj.Prog{}
	p.Ctxt = asm.Ctxt
	p.As = int16(a)
	p.Lineno = stmtline
	p.From = g2.from
	p.To = g2.to
	p.Pc = int64(asm.PC)

	if lastpc == nil {
		pl = obj.Linknewplist(asm.Ctxt)
		pl.Firstpc = p
	} else {

		lastpc.Link = p
	}
	lastpc = p

out:
	if a != obj.AGLOBL && a != obj.ADATA {
		asm.PC++
	}
}

func Prog(as int) *obj.Prog {
	var p *obj.Prog

	if as == obj.ADATA || as == obj.AGLOBL {
		if ddumped != 0 {
			Fatalf("already dumped data")
		}
		if dpc == nil {
			dpc = Ctxt.NewProg()
			dfirst = dpc
		}

		p = dpc
		dpc = Ctxt.NewProg()
		p.Link = dpc
	} else {
		p = Pc
		Pc = Ctxt.NewProg()
		Clearp(Pc)
		p.Link = Pc
	}

	if lineno == 0 {
		if Debug['K'] != 0 {
			Warn("prog: line 0")
		}
	}

	p.As = int16(as)
	p.Lineno = lineno
	return p
}

func rewriteToPcrel(ctxt *obj.Link, p *obj.Prog) {
	// RegTo2 is set on the instructions we insert here so they don't get
	// processed twice.
	if p.RegTo2 != 0 {
		return
	}
	if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
		return
	}
	// Any Prog (aside from the above special cases) with an Addr with Name ==
	// NAME_EXTERN, NAME_STATIC or NAME_GOTREF has a CALL __x86.get_pc_thunk.cx
	// inserted before it.
	isName := func(a *obj.Addr) bool {
		if a.Sym == nil || (a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR) || a.Reg != 0 {
			return false
		}
		if a.Sym.Type == obj.STLSBSS {
			return false
		}
		return a.Name == obj.NAME_EXTERN || a.Name == obj.NAME_STATIC || a.Name == obj.NAME_GOTREF
	}

	if isName(&p.From) && p.From.Type == obj.TYPE_ADDR {
		// Handle things like "MOVL $sym, (SP)" or "PUSHL $sym" by rewriting
		// to "MOVL $sym, CX; MOVL CX, (SP)" or "MOVL $sym, CX; PUSHL CX"
		// respectively.
		if p.To.Type != obj.TYPE_REG {
			q := obj.Appendp(ctxt, p)
			q.As = p.As
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REG_CX
			q.To = p.To
			p.As = AMOVL
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REG_CX
			p.To.Sym = nil
			p.To.Name = obj.NAME_NONE
		}
	}

	if !isName(&p.From) && !isName(&p.To) && (p.From3 == nil || !isName(p.From3)) {
		return
	}
	q := obj.Appendp(ctxt, p)
	q.RegTo2 = 1
	r := obj.Appendp(ctxt, q)
	r.RegTo2 = 1
	q.As = obj.ACALL
	q.To.Sym = obj.Linklookup(ctxt, "__x86.get_pc_thunk.cx", 0)
	q.To.Type = obj.TYPE_MEM
	q.To.Name = obj.NAME_EXTERN
	q.To.Sym.Local = true
	r.As = p.As
	r.Scond = p.Scond
	r.From = p.From
	r.From3 = p.From3
	r.Reg = p.Reg
	r.To = p.To
	obj.Nopout(p)
}

// Append code to p to load g into cx.
// Overwrites p with the first instruction (no first appendp).
// Overwriting p is unusual but it lets use this in both the
// prologue (caller must call appendp first) and in the epilogue.
// Returns last new instruction.
func load_g_cx(ctxt *obj.Link, p *obj.Prog) *obj.Prog {
	p.As = AMOVQ
	if ctxt.Arch.PtrSize == 4 {
		p.As = AMOVL
	}
	p.From.Type = obj.TYPE_MEM
	p.From.Reg = REG_TLS
	p.From.Offset = 0
	p.To.Type = obj.TYPE_REG
	p.To.Reg = REG_CX

	next := p.Link
	progedit(ctxt, p)
	for p.Link != next {
		p = p.Link
	}

	if p.From.Index == REG_TLS {
		p.From.Scale = 2
	}

	return p
}

// ARMConditionCodes handles the special condition code situation for the ARM.
// It returns a boolean to indicate success; failure means cond was unrecognized.
func ARMConditionCodes(prog *obj.Prog, cond string) bool {
	if cond == "" {
		return true
	}
	bits, ok := ParseARMCondition(cond)
	if !ok {
		return false
	}
	/* hack to make B.NE etc. work: turn it into the corresponding conditional */
	if prog.As == arm.AB {
		prog.As = int16(bcode[(bits^arm.C_SCOND_XOR)&0xf])
		bits = (bits &^ 0xf) | arm.C_SCOND_NONE
	}
	prog.Scond = bits
	return true
}

func Prog(as obj.As) *obj.Prog {
	var p *obj.Prog

	p = pc
	pc = Ctxt.NewProg()
	Clearp(pc)
	p.Link = pc

	if lineno == 0 && Debug['K'] != 0 {
		Warn("prog: line 0")
	}

	p.As = as
	p.Lineno = lineno
	return p
}

func outcode(a int, g1 *obj.Addr, reg int, g2 *obj.Addr) {
	var p *obj.Prog
	var pl *obj.Plist

	if asm.Pass == 1 {
		goto out
	}

	if g1.Scale != 0 {
		if reg != 0 || g2.Scale != 0 {
			yyerror("bad addressing modes")
		}
		reg = int(g1.Scale)
	} else if g2.Scale != 0 {
		if reg != 0 {
			yyerror("bad addressing modes")
		}
		reg = int(g2.Scale)
	}

	p = asm.Ctxt.NewProg()
	p.As = int16(a)
	p.Lineno = stmtline
	if nosched != 0 {
		p.Mark |= ppc64.NOSCHED
	}
	p.From = *g1
	p.Reg = int16(reg)
	p.To = *g2
	p.Pc = int64(asm.PC)

	if lastpc == nil {
		pl = obj.Linknewplist(asm.Ctxt)
		pl.Firstpc = p
	} else {
		lastpc.Link = p
	}
	lastpc = p

out:
	if a != obj.AGLOBL && a != obj.ADATA {
		asm.PC++
	}
}

// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var reg int
	var p1 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(int(p.Lineno), "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatalf("invalid nil check %v", p)
		}
		reg = int(p.From.Reg)

		// check is
		//	CMP arg, $0
		//	MOV.EQ arg, 0(arg)
		p1 = gc.Ctxt.NewProg()

		gc.Clearp(p1)
		p1.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p1.Pc = 9999
		p1.As = arm.AMOVW
		p1.From.Type = obj.TYPE_REG
		p1.From.Reg = int16(reg)
		p1.To.Type = obj.TYPE_MEM
		p1.To.Reg = int16(reg)
		p1.To.Offset = 0
		p1.Scond = arm.C_SCOND_EQ
		p.As = arm.ACMP
		p.From.Type = obj.TYPE_CONST
		p.From.Reg = 0
		p.From.Offset = 0
		p.Reg = int16(reg)
	}
}

// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog

	for p := (*obj.Prog)(firstp); p != nil; p = p.Link {
		if gc.Debug_checknil != 0 && gc.Ctxt.Debugvlog != 0 {
			fmt.Printf("expandchecks: %v\n", p)
		}
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(int(p.Lineno), "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatalf("invalid nil check %v\n", p)
		}

		// check is
		//	CBNZ arg, 2(PC)
		//	MOVD ZR, 0(arg)
		p1 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		p1.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p1.Pc = 9999

		p.As = arm64.ACBNZ
		p.To.Type = obj.TYPE_BRANCH
		p.To.Val = p1.Link

		// crash by write to memory address 0.
		p1.As = arm64.AMOVD
		p1.From.Type = obj.TYPE_REG
		p1.From.Reg = arm64.REGZERO
		p1.To.Type = obj.TYPE_MEM
		p1.To.Reg = p.From.Reg
		p1.To.Offset = 0
	}
}

func span0(ctxt *obj.Link, cursym *obj.LSym) {
	p := cursym.Text
	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
		return
	}
	ctxt.Cursym = cursym
	ctxt.Autosize = int32(p.To.Offset + 8)

	if oprange[AOR&obj.AMask].start == nil {
		buildop(ctxt)
	}

	c := int64(0)
	p.Pc = c

	var m int
	var o *Optab
	for p = p.Link; p != nil; p = p.Link {
		ctxt.Curp = p
		p.Pc = c
		o = oplook(ctxt, p)
		m = int(o.size)
		if m == 0 {
			if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA && p.As != obj.AUSEFIELD {
				ctxt.Diag("zero-width instruction\n%v", p)
			}
			continue
		}

		c += int64(m)
	}

	cursym.Size = c

	/*
	 * if any procedure is large enough to
	 * generate a large SBRA branch, then
	 * generate extra passes putting branches
	 * around jmps to fix. this is rare.
	 */
	bflag := 1

	var otxt int64
	var q *obj.Prog
	for bflag != 0 {
		if ctxt.Debugvlog != 0 {
			fmt.Fprintf(ctxt.Bso, "%5.2f span1\n", obj.Cputime())
		}
		bflag = 0
		c = 0
		for p = cursym.Text.Link; p != nil; p = p.Link {
			p.Pc = c
			o = oplook(ctxt, p)

			// very large conditional branches
			if o.type_ == 6 && p.Pcond != nil {
				otxt = p.Pcond.Pc - c
				if otxt < -(1<<17)+10 || otxt >= (1<<17)-10 {
					q = ctxt.NewProg()
					q.Link = p.Link
					p.Link = q
					q.As = AJMP
					q.Lineno = p.Lineno
					q.To.Type = obj.TYPE_BRANCH
					q.Pcond = p.Pcond
					p.Pcond = q
					q = ctxt.NewProg()
					q.Link = p.Link
					p.Link = q
					q.As = AJMP
					q.Lineno = p.Lineno
					q.To.Type = obj.TYPE_BRANCH
					q.Pcond = q.Link.Link

					addnop(ctxt, p.Link)
					addnop(ctxt, p)
					bflag = 1
				}
			}

			m = int(o.size)
			if m == 0 {
				if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA && p.As != obj.AUSEFIELD {
					ctxt.Diag("zero-width instruction\n%v", p)
				}
				continue
			}

			c += int64(m)
		}

		cursym.Size = c
	}

	c += -c & (FuncAlign - 1)
	cursym.Size = c

	/*
	 * lay out the code, emitting code and data relocations.
	 */
//.........这里部分代码省略.........