Golang Link.Diag方法代码示例

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

	a1 := int(p.Optab)
	if a1 != 0 {
		return &optab[a1-1]
	}
	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);

	ops := oprange[p.As&obj.AMask]
	c1 := &xcmp[a1]
	c3 := &xcmp[a3]
	for i := range ops {
		op := &ops[i]
		if int(op.a2) == a2 && c1[op.a1] && c3[op.a3] {
			p.Optab = uint16(cap(optab) - cap(ops) + i + 1)
			return op
		}
	}

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

// 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 obj.As
	var 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; $LEA <off>(Rx), 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 = lea
			q.From.Type = obj.TYPE_MEM
			q.From.Reg = p.To.Reg
			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
//.........这里部分代码省略.........

//.........这里部分代码省略.........
			p.As = AMOVW
			p.Scond |= C_PBIT
			p.From.Type = obj.TYPE_MEM
			p.From.Offset = int64(autosize)
			p.From.Reg = REGSP
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REGPC

			// If there are instructions following
			// this ARET, they come from a branch
			// with the same stackframe, so no spadj.
			if p.To.Sym != nil { // retjmp
				p.To.Reg = REGLINK
				q2 = obj.Appendp(ctxt, p)
				q2.As = AB
				q2.To.Type = obj.TYPE_BRANCH
				q2.To.Sym = p.To.Sym
				p.To.Sym = nil
				p = q2
			}

		case AADD:
			if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
				p.Spadj = int32(-p.From.Offset)
			}

		case ASUB:
			if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
				p.Spadj = int32(p.From.Offset)
			}

		case ADIV, ADIVU, AMOD, AMODU:
			if cursym.Text.From3.Offset&obj.NOSPLIT != 0 {
				ctxt.Diag("cannot divide in NOSPLIT function")
			}
			if ctxt.Debugdivmod != 0 {
				break
			}
			if p.From.Type != obj.TYPE_REG {
				break
			}
			if p.To.Type != obj.TYPE_REG {
				break
			}

			// Make copy because we overwrite p below.
			q1 := *p
			if q1.Reg == REGTMP || q1.Reg == 0 && q1.To.Reg == REGTMP {
				ctxt.Diag("div already using REGTMP: %v", p)
			}

			/* MOV m(g),REGTMP */
			p.As = AMOVW
			p.Lineno = q1.Lineno
			p.From.Type = obj.TYPE_MEM
			p.From.Reg = REGG
			p.From.Offset = 6 * 4 // offset of g.m
			p.Reg = 0
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REGTMP

			/* MOV a,m_divmod(REGTMP) */
			p = obj.Appendp(ctxt, p)
			p.As = AMOVW
			p.Lineno = q1.Lineno
			p.From.Type = obj.TYPE_REG

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
		}
	}
}

// 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
		//     MOVD [email protected], R12
		//     ADD $offset, R12
		//     MOVD R12, CTR
		//     BL (CTR)
		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 = AMOVD
		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_R12
		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_R12
		p2 := obj.Appendp(ctxt, p1)
		p2.As = AMOVD
		p2.From.Type = obj.TYPE_REG
		p2.From.Reg = REG_R12
		p2.To.Type = obj.TYPE_REG
		p2.To.Reg = REG_CTR
		p3 := obj.Appendp(ctxt, p2)
		p3.As = obj.ACALL
		p3.From.Type = obj.TYPE_REG
		p3.From.Reg = REG_R12
		p3.To.Type = obj.TYPE_REG
		p3.To.Reg = REG_CTR
	}

	// 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 {
		// MOVD $sym, Rx becomes MOVD [email protected], Rx
		// MOVD $sym+<off>, Rx becomes MOVD [email protected], Rx; ADD <off>, Rx
		if p.As != AMOVD {
			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 MOVD [email protected], REGTMP; MOVx (REGTMP), Ry
	// MOVx Ry, sym becomes MOVD [email protected], REGTMP; MOVx Ry, (REGTMP)
	// 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 = AMOVD
	p1.From.Type = obj.TYPE_MEM
	p1.From.Sym = source.Sym
//.........这里部分代码省略.........

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

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

	p := cursym.Text
	textstksiz := p.To.Offset
	if textstksiz == -8 {
		// Compatibility hack.
		p.From3.Offset |= obj.NOFRAME
		textstksiz = 0
	}
	if textstksiz%8 != 0 {
		ctxt.Diag("frame size %d not a multiple of 8", textstksiz)
	}
	if p.From3.Offset&obj.NOFRAME != 0 {
		if textstksiz != 0 {
			ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", textstksiz)
		}
	}

	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
			}

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

		case ALWAR,
			ASTWCCC,
			AECIWX,
			AECOWX,
			AEIEIO,
			AICBI,
			AISYNC,
			ATLBIE,
			ATLBIEL,
			ASLBIA,
			ASLBIE,
			ASLBMFEE,
			ASLBMFEV,
			ASLBMTE,
			ADCBF,
			ADCBI,
			ADCBST,
			ADCBT,
			ADCBTST,
			ADCBZ,
			ASYNC,
			ATLBSYNC,
			APTESYNC,
			ATW,
			AWORD,
			ARFI,
			ARFCI,
			ARFID,
			AHRFID:
			q = p
			p.Mark |= LABEL | SYNC
			continue

		case AMOVW, AMOVWZ, AMOVD:
			q = p
			if p.From.Reg >= REG_SPECIAL || p.To.Reg >= REG_SPECIAL {
				p.Mark |= LABEL | SYNC
			}
			continue

		case AFABS,
//.........这里部分代码省略.........

// Rewrite p, if necessary, to access global data via the global offset table.
func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
	// At the moment EXRL instructions are not emitted by the compiler and only reference local symbols in
	// assembly code.
	if p.As == AEXRL {
		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 {
		// MOVD $sym, Rx becomes MOVD [email protected], Rx
		// MOVD $sym+<off>, Rx becomes MOVD [email protected], Rx; ADD <off>, Rx
		if p.To.Type != obj.TYPE_REG || p.As != AMOVD {
			ctxt.Diag("do not know how to handle LEA-type insn to non-register in %v with -dynlink", p)
		}
		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 = 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
	// MOVD sym, Ry becomes MOVD [email protected], REGTMP; MOVD (REGTMP), Ry
	// MOVD Ry, sym becomes MOVD [email protected], REGTMP; MOVD Ry, (REGTMP)
	// 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 = AMOVD
	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 = REGTMP

	p2.As = p.As
	p2.From = p.From
	p2.To = p.To
	if p.From.Name == obj.NAME_EXTERN {
		p2.From.Reg = REGTMP
		p2.From.Name = obj.NAME_NONE
		p2.From.Sym = nil
	} else if p.To.Name == obj.NAME_EXTERN {
		p2.To.Reg = REGTMP
		p2.To.Name = obj.NAME_NONE
		p2.To.Sym = nil
	} else {
		return
	}
	obj.Nopout(p)
}

//.........这里部分代码省略.........
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R5

				q = obj.Appendp(ctxt, q)
				q.As = ABNE
				q.To.Type = obj.TYPE_BRANCH
				p2 = q

				q = obj.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = 8
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R6

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R6
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REG_R3
				q.To.Offset = 0 // Panic.argp

				q = obj.Appendp(ctxt, q)

				q.As = obj.ANOP
				p1.Pcond = q
				p2.Pcond = q
			}

		case ARETURN:
			if p.From.Type == obj.TYPE_CONST {
				ctxt.Diag("using BECOME (%v) is not supported!", p)
				break
			}

			if p.To.Sym != nil { // retjmp
				p.As = ABR
				p.To.Type = obj.TYPE_BRANCH
				break
			}

			if cursym.Text.Mark&LEAF != 0 {
				if autosize == 0 {
					p.As = ABR
					p.From = obj.Addr{}
					p.To.Type = obj.TYPE_REG
					p.To.Reg = REG_LR
					p.Mark |= BRANCH
					break
				}

				p.As = AADD
				p.From.Type = obj.TYPE_CONST
				p.From.Offset = int64(autosize)
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGSP
				p.Spadj = -autosize

				q = ctxt.NewProg()
				q.As = ABR
				q.Lineno = p.Lineno
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_LR
				q.Mark |= BRANCH

//.........这里部分代码省略.........
	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:
		return FPF(1, 1)
	case ATRUNCDV:
		return FPD(1, 1)
	case ATRUNCFW:
		return FPF(1, 5)
	case ATRUNCDW:
		return FPD(1, 5)
	case AMOVFV:
		return FPF(4, 5)
	case AMOVDV:
		return FPD(4, 5)
	case AMOVVF:
		return FPV(4, 0)
	case AMOVVD:
		return FPV(4, 1)
	case AMOVFW:
		return FPF(4, 4)
	case AMOVDW:
		return FPD(4, 4)
	case AMOVWF:
		return FPW(4, 0)
	case AMOVDF:
		return FPD(4, 0)
	case AMOVWD:
		return FPW(4, 1)
	case AMOVFD:
		return FPF(4, 1)
	case AABSF:
		return FPF(0, 5)
	case AABSD:
		return FPD(0, 5)
	case AMOVF:
		return FPF(0, 6)
	case AMOVD:
		return FPD(0, 6)
	case ANEGF:
		return FPF(0, 7)
	case ANEGD:
		return FPD(0, 7)
	case ACMPEQF:
		return FPF(6, 2)
	case ACMPEQD:
		return FPD(6, 2)
	case ACMPGTF:
		return FPF(7, 4)
	case ACMPGTD:
		return FPD(7, 4)
	case ACMPGEF:
		return FPF(7, 6)
	case ACMPGED:
		return FPD(7, 6)
	}

	if a >= ALAST {
		ctxt.Diag("bad rrr opcode %v+ALAST", obj.Aconv(a-ALAST))
	} else {
		ctxt.Diag("bad rrr opcode %v", obj.Aconv(a))
	}
	return 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.........

//.........这里部分代码省略.........
				q.As = ABNE
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.Reg = REG_R3
				q.To.Type = obj.TYPE_BRANCH
				q.Mark |= BRANCH
				p2 = q

				q = obj.Appendp(ctxt, q)
				q.As = add
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = ctxt.FixedFrameSize()
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R2

				q = obj.Appendp(ctxt, q)
				q.As = mov
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REG_R1
				q.To.Offset = 0 // Panic.argp

				q = obj.Appendp(ctxt, q)

				q.As = obj.ANOP
				p1.Pcond = q
				p2.Pcond = q
			}

		case ARET:
			if p.From.Type == obj.TYPE_CONST {
				ctxt.Diag("using BECOME (%v) is not supported!", p)
				break
			}

			retSym := p.To.Sym
			p.To.Name = obj.NAME_NONE // clear fields as we may modify p to other instruction
			p.To.Sym = nil

			if cursym.Text.Mark&LEAF != 0 {
				if autosize == 0 {
					p.As = AJMP
					p.From = obj.Addr{}
					if retSym != nil { // retjmp
						p.To.Type = obj.TYPE_BRANCH
						p.To.Name = obj.NAME_EXTERN
						p.To.Sym = retSym
					} else {
						p.To.Type = obj.TYPE_MEM
						p.To.Reg = REGLINK
						p.To.Offset = 0
					}
					p.Mark |= BRANCH
					break
				}

				p.As = add
				p.From.Type = obj.TYPE_CONST
				p.From.Offset = int64(autosize)
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGSP
				p.Spadj = -autosize

				q = ctxt.NewProg()

func progedit(ctxt *obj.Link, p *obj.Prog) {
	// Maintain information about code generation mode.
	if ctxt.Mode == 0 {
		switch ctxt.Arch.Family {
		default:
			ctxt.Diag("unsupported arch family")
		case sys.MIPS:
			ctxt.Mode = Mips32
		case sys.MIPS64:
			ctxt.Mode = Mips64
		}
	}

	p.From.Class = 0
	p.To.Class = 0

	// Rewrite JMP/JAL to symbol as TYPE_BRANCH.
	switch p.As {
	case AJMP,
		AJAL,
		ARET,
		obj.ADUFFZERO,
		obj.ADUFFCOPY:
		if p.To.Sym != nil {
			p.To.Type = obj.TYPE_BRANCH
		}
	}

	// Rewrite float constants to values stored in memory.
	switch p.As {
	case AMOVF:
		if p.From.Type == obj.TYPE_FCONST {
			f32 := float32(p.From.Val.(float64))
			i32 := math.Float32bits(f32)
			if i32 == 0 {
				p.As = AMOVW
				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGZERO
				break
			}
			literal := fmt.Sprintf("$f32.%08x", i32)
			s := obj.Linklookup(ctxt, literal, 0)
			s.Size = 4
			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 {
			i64 := math.Float64bits(p.From.Val.(float64))
			if i64 == 0 && ctxt.Mode&Mips64 != 0 {
				p.As = AMOVV
				p.From.Type = obj.TYPE_REG
				p.From.Reg = REGZERO
				break
			}
			literal := fmt.Sprintf("$f64.%016x", i64)
			s := obj.Linklookup(ctxt, literal, 0)
			s.Size = 8
			p.From.Type = obj.TYPE_MEM
			p.From.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}

		// Put >32-bit constants in memory and load them
	case AMOVV:
		if p.From.Type == obj.TYPE_CONST && p.From.Name == obj.NAME_NONE && p.From.Reg == 0 && int64(int32(p.From.Offset)) != p.From.Offset {
			literal := fmt.Sprintf("$i64.%016x", uint64(p.From.Offset))
			s := obj.Linklookup(ctxt, literal, 0)
			s.Size = 8
			p.From.Type = obj.TYPE_MEM
			p.From.Sym = s
			p.From.Name = obj.NAME_EXTERN
			p.From.Offset = 0
		}
	}

	// Rewrite SUB constants into ADD.
	switch p.As {
	case ASUB:
		if p.From.Type == obj.TYPE_CONST {
			p.From.Offset = -p.From.Offset
			p.As = AADD
		}

	case ASUBU:
		if p.From.Type == obj.TYPE_CONST {
			p.From.Offset = -p.From.Offset
			p.As = AADDU
		}

	case ASUBV:
		if p.From.Type == obj.TYPE_CONST {
			p.From.Offset = -p.From.Offset
			p.As = AADDV
		}

//.........这里部分代码省略.........

func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	if ctxt.Headtype == obj.Hplan9 && ctxt.Plan9privates == nil {
		ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
	}

	ctxt.Cursym = cursym

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

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

	var bpsize int
	if p.Mode == 64 && ctxt.Framepointer_enabled && autoffset > 0 && p.From3.Offset&obj.NOFRAME == 0 {
		// Make room for to save a base pointer. If autoffset == 0,
		// this might do something special like a tail jump to
		// another function, so in that case we omit this.
		bpsize = ctxt.Arch.PtrSize
		autoffset += int32(bpsize)
		p.To.Offset += int64(bpsize)
	} else {
		bpsize = 0
	}

	textarg := int64(p.To.Val.(int32))
	cursym.Args = int32(textarg)
	cursym.Locals = int32(p.To.Offset)

	// TODO(rsc): Remove.
	if p.Mode == 32 && cursym.Locals < 0 {
		cursym.Locals = 0
	}

	// TODO(rsc): Remove 'p.Mode == 64 &&'.
	if p.Mode == 64 && autoffset < obj.StackSmall && p.From3Offset()&obj.NOSPLIT == 0 {
		leaf := true
	LeafSearch:
		for q := p; q != nil; q = q.Link {
			switch q.As {
			case obj.ACALL:
				// Treat common runtime calls that take no arguments
				// the same as duffcopy and duffzero.
				if !isZeroArgRuntimeCall(q.To.Sym) {
					leaf = false
					break LeafSearch
				}
				fallthrough
			case obj.ADUFFCOPY, obj.ADUFFZERO:
				if autoffset >= obj.StackSmall-8 {
					leaf = false
					break LeafSearch
				}
			}
		}

		if leaf {
			p.From3.Offset |= obj.NOSPLIT
		}
	}

	if p.From3Offset()&obj.NOSPLIT == 0 || p.From3Offset()&obj.WRAPPER != 0 {
		p = obj.Appendp(ctxt, p)
		p = load_g_cx(ctxt, p) // load g into CX
	}

	if cursym.Text.From3Offset()&obj.NOSPLIT == 0 {
		p = stacksplit(ctxt, p, autoffset, int32(textarg)) // emit split check
	}

	if autoffset != 0 {
		if autoffset%int32(ctxt.Arch.RegSize) != 0 {
			ctxt.Diag("unaligned stack size %d", autoffset)
		}
		p = obj.Appendp(ctxt, p)
		p.As = AADJSP
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = int64(autoffset)
		p.Spadj = autoffset
	}

	deltasp := autoffset

	if bpsize > 0 {
		// Save caller's BP
		p = obj.Appendp(ctxt, p)

		p.As = AMOVQ
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_BP
		p.To.Type = obj.TYPE_MEM
		p.To.Reg = REG_SP
		p.To.Scale = 1
		p.To.Offset = int64(autoffset) - int64(bpsize)

		// Move current frame to BP
//.........这里部分代码省略.........