Golang Prog.Link方法代码示例

func follow(ctxt *liblink.Link, s *liblink.LSym) {
	var firstp *liblink.Prog
	var lastp *liblink.Prog
	ctxt.Cursym = s
	firstp = ctxt.Prg()
	lastp = firstp
	xfol(ctxt, s.Text, &lastp)
	lastp.Link = nil
	s.Text = firstp.Link
}

func readprog(b *bufio.Reader, p *liblink.Prog) {
	if !undef[p] {
		panic("double-def")
	}
	delete(undef, p)
	p.Pc = rdint(b)
	p.Lineno = int(rdint(b))
	p.Link = rdprog(b)
	p.As = int(rdint(b))
	p.Reg = int(rdint(b))
	p.Scond = int(rdint(b))
	p.Width = int8(rdint(b))
	readaddr(b, &p.From)
	readaddr(b, &p.To)
}

func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
	var p *liblink.Prog
	var q *liblink.Prog
	var q1 *liblink.Prog
	var autoffset int64
	var deltasp int64
	var a int
	var pcsize int
	var i uint32
	var textstksiz int64
	var textarg int64
	if ctxt.Tlsg == nil {
		ctxt.Tlsg = liblink.Linklookup(ctxt, "runtime.tlsg", 0)
	}
	if ctxt.Symmorestack[0] == nil {
		if len(morename) > len(ctxt.Symmorestack) {
			log.Fatalf("Link.symmorestack needs at least %d elements", len(morename))
		}
		for i = 0; i < uint32(len(morename)); i++ {
			ctxt.Symmorestack[i] = liblink.Linklookup(ctxt, morename[i], 0)
		}
	}
	if ctxt.Headtype == liblink.Hplan9 && ctxt.Plan9privates == nil {
		ctxt.Plan9privates = liblink.Linklookup(ctxt, "_privates", 0)
	}
	ctxt.Cursym = cursym
	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}
	p = cursym.Text
	parsetextconst(p.To.Offset, &textstksiz, &textarg)
	autoffset = textstksiz
	if autoffset < 0 {
		autoffset = 0
	}
	cursym.Args = int(p.To.Offset >> 32)
	cursym.Locals = textstksiz
	if autoffset < liblink.StackSmall && p.From.Scale&liblink.NOSPLIT == 0 {
		for q = p; q != nil; q = q.Link {
			if q.As == ACALL {
				goto noleaf
			}
			if (q.As == ADUFFCOPY || q.As == ADUFFZERO) && autoffset >= liblink.StackSmall-8 {
				goto noleaf
			}
		}
		p.From.Scale |= liblink.NOSPLIT
	noleaf:
	}
	q = nil
	if p.From.Scale&liblink.NOSPLIT == 0 || (p.From.Scale&liblink.WRAPPER != 0) {
		p = liblink.Appendp(ctxt, p)
		p = load_g_cx(ctxt, p) // load g into CX
	}
	if cursym.Text.From.Scale&liblink.NOSPLIT == 0 {
		p = stacksplit(ctxt, p, autoffset, textarg, bool2int(cursym.Text.From.Scale&liblink.NEEDCTXT == 0), &q) // emit split check
	}
	if autoffset != 0 {
		if autoffset%int64(ctxt.Arch.Regsize) != 0 {
			ctxt.Diag("unaligned stack size %d", autoffset)
		}
		p = liblink.Appendp(ctxt, p)
		p.As = AADJSP
		p.From.Typ = D_CONST
		p.From.Offset = autoffset
		p.Spadj = autoffset
	} else {
		// zero-byte stack adjustment.
		// Insert a fake non-zero adjustment so that stkcheck can
		// recognize the end of the stack-splitting prolog.
		p = liblink.Appendp(ctxt, p)
		p.As = ANOP
		p.Spadj = -ctxt.Arch.Ptrsize
		p = liblink.Appendp(ctxt, p)
		p.As = ANOP
		p.Spadj = ctxt.Arch.Ptrsize
	}
	if q != nil {
		q.Pcond = p
	}
	deltasp = autoffset
	if cursym.Text.From.Scale&liblink.WRAPPER != 0 {
		// g->panicwrap += autoffset + ctxt->arch->regsize;
		p = liblink.Appendp(ctxt, p)
		p.As = AADDL
		p.From.Typ = D_CONST
		p.From.Offset = autoffset + int64(ctxt.Arch.Regsize)
		indir_cx(ctxt, &p.To)
		p.To.Offset = 2 * ctxt.Arch.Ptrsize
	}
	if ctxt.Debugstack > 1 && autoffset != 0 {
		// 6l -K -K means double-check for stack overflow
		// even after calling morestack and even if the
		// function is marked as nosplit.
		p = liblink.Appendp(ctxt, p)
		p.As = AMOVQ
		indir_cx(ctxt, &p.From)
		p.From.Offset = 0
		p.To.Typ = D_BX
		p = liblink.Appendp(ctxt, p)
//.........这里部分代码省略.........

func xfol(ctxt *liblink.Link, p *liblink.Prog, last **liblink.Prog) {
	var q *liblink.Prog
	var r *liblink.Prog
	var a int
	var i int
loop:
	if p == nil {
		return
	}
	a = p.As
	if a == AB {
		q = p.Pcond
		if q != nil && q.As != ATEXT {
			p.Mark |= FOLL
			p = q
			if p.Mark&FOLL == 0 {
				goto loop
			}
		}
	}
	if p.Mark&FOLL != 0 {
		i = 0
		q = p
		for ; i < 4; (func() { i++; q = q.Link })() {
			if q == *last || q == nil {
				break
			}
			a = q.As
			if a == ANOP {
				i--
				continue
			}
			if a == AB || (a == ARET && q.Scond == C_SCOND_NONE) || a == ARFE || a == AUNDEF {
				goto copy
			}
			if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
				continue
			}
			if a != ABEQ && a != ABNE {
				continue
			}
		copy:
			for {
				r = ctxt.Prg()
				*r = *p
				if r.Mark&FOLL == 0 {
					fmt.Printf("can't happen 1\n")
				}
				r.Mark |= FOLL
				if p != q {
					p = p.Link
					(*last).Link = r
					*last = r
					continue
				}
				(*last).Link = r
				*last = r
				if a == AB || (a == ARET && q.Scond == C_SCOND_NONE) || a == ARFE || a == AUNDEF {
					return
				}
				r.As = ABNE
				if a == ABNE {
					r.As = ABEQ
				}
				r.Pcond = p.Link
				r.Link = p.Pcond
				if r.Link.Mark&FOLL == 0 {
					xfol(ctxt, r.Link, last)
				}
				if r.Pcond.Mark&FOLL == 0 {
					fmt.Printf("can't happen 2\n")
				}
				return
			}
		}
		a = AB
		q = ctxt.Prg()
		q.As = a
		q.Lineno = p.Lineno
		q.To.Typ = D_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}
	p.Mark |= FOLL
	(*last).Link = p
	*last = p
	if a == AB || (a == ARET && p.Scond == C_SCOND_NONE) || a == ARFE || a == AUNDEF {
		return
	}
	if p.Pcond != nil {
		if a != ABL && a != ABX && p.Link != nil {
			q = liblink.Brchain(ctxt, p.Link)
			if a != ATEXT && a != ABCASE {
				if q != nil && (q.Mark&FOLL != 0) {
					p.As = relinv(a)
					p.Link = p.Pcond
					p.Pcond = q
				}
			}
//.........这里部分代码省略.........

func softfloat(ctxt *liblink.Link, cursym *liblink.LSym) {
	var p *liblink.Prog
	var next *liblink.Prog
	var symsfloat *liblink.LSym
	var wasfloat int
	if ctxt.Goarm > 5 {
		return
	}
	symsfloat = liblink.Linklookup(ctxt, "_sfloat", 0)
	wasfloat = 0
	for p = cursym.Text; p != nil; p = p.Link {
		if p.Pcond != nil {
			p.Pcond.Mark |= LABEL
		}
	}
	for p = cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case AMOVW:
			if p.To.Typ == D_FREG || p.From.Typ == D_FREG {
				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.Prg()
			*next = *p
			// BL _sfloat(SB)
			*p = zprg_obj5
			p.Ctxt = ctxt
			p.Link = next
			p.As = ABL
			p.To.Typ = D_BRANCH
			p.To.Sym = symsfloat
			p.Lineno = next.Lineno
			p = next
			wasfloat = 1
		}
		continue
	notsoft:
		wasfloat = 0
	}
}

func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
	var p *liblink.Prog
	var pl *liblink.Prog
	var q *liblink.Prog
	var q1 *liblink.Prog
	var q2 *liblink.Prog
	var o int
	var autosize int64
	var autoffset int64
	autosize = 0
	if ctxt.Symmorestack[0] == nil {
		ctxt.Symmorestack[0] = liblink.Linklookup(ctxt, "runtime.morestack", 0)
		ctxt.Symmorestack[1] = liblink.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
	}
	q = nil
	ctxt.Cursym = cursym
	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}
	softfloat(ctxt, cursym)
	p = cursym.Text
	autoffset = p.To.Offset
	if autoffset < 0 {
		autoffset = 0
	}
	cursym.Locals = autoffset
	cursym.Args = p.To.Offset2
	if ctxt.Debugzerostack != 0 {
		if autoffset != 0 && p.Reg&liblink.NOSPLIT == 0 {
			// MOVW $4(R13), R1
			p = liblink.Appendp(ctxt, p)
			p.As = AMOVW
			p.From.Typ = D_CONST
			p.From.Reg = 13
			p.From.Offset = 4
			p.To.Typ = D_REG
			p.To.Reg = 1
			// MOVW $n(R13), R2
			p = liblink.Appendp(ctxt, p)
			p.As = AMOVW
			p.From.Typ = D_CONST
			p.From.Reg = 13
			p.From.Offset = 4 + autoffset
			p.To.Typ = D_REG
			p.To.Reg = 2
			// MOVW $0, R3
			p = liblink.Appendp(ctxt, p)
			p.As = AMOVW
			p.From.Typ = D_CONST
			p.From.Offset = 0
			p.To.Typ = D_REG
			p.To.Reg = 3
			// L:
			//	MOVW.nil R3, 0(R1) +4
			//	CMP R1, R2
			//	BNE L
			pl = liblink.Appendp(ctxt, p)
			p = pl
			p.As = AMOVW
			p.From.Typ = D_REG
			p.From.Reg = 3
			p.To.Typ = D_OREG
			p.To.Reg = 1
			p.To.Offset = 4
			p.Scond |= C_PBIT
			p = liblink.Appendp(ctxt, p)
			p.As = ACMP
			p.From.Typ = D_REG
			p.From.Reg = 1
			p.Reg = 2
			p = liblink.Appendp(ctxt, p)
			p.As = ABNE
			p.To.Typ = D_BRANCH
			p.Pcond = pl
		}
	}
	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 * expand BECOME pseudo
	 */
	for p = cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case ACASE:
			if ctxt.Flag_shared != 0 {
				linkcase(p)
			}
		case ATEXT:
			p.Mark |= LEAF
		case ARET:
			break
		case ADIV,
			ADIVU,
			AMOD,
			AMODU:
			q = p
			if ctxt.Sym_div == nil {
				initdiv(ctxt)
			}
//.........这里部分代码省略.........

func xfol(ctxt *liblink.Link, p *liblink.Prog, last **liblink.Prog) {
	var q *liblink.Prog
	var i int
	var a int
loop:
	if p == nil {
		return
	}
	if p.As == AJMP {
		q = p.Pcond
		if q != nil && q.As != ATEXT {
			/* mark instruction as done and continue layout at target of jump */
			p.Mark = 1
			p = q
			if p.Mark == 0 {
				goto loop
			}
		}
	}
	if p.Mark != 0 {
		/*
		 * p goes here, but already used it elsewhere.
		 * copy up to 4 instructions or else branch to other copy.
		 */
		i = 0
		q = p
		for ; i < 4; (func() { i++; q = q.Link })() {
			if q == nil {
				break
			}
			if q == *last {
				break
			}
			a = q.As
			if a == ANOP {
				i--
				continue
			}
			if nofollow(a) || pushpop(a) != 0 {
				break // NOTE(rsc): arm does goto copy
			}
			if q.Pcond == nil || q.Pcond.Mark != 0 {
				continue
			}
			if a == ACALL || a == ALOOP {
				continue
			}
			for {
				if p.As == ANOP {
					p = p.Link
					continue
				}
				q = liblink.Copyp(ctxt, p)
				p = p.Link
				q.Mark = 1
				(*last).Link = q
				*last = q
				if q.As != a || q.Pcond == nil || q.Pcond.Mark != 0 {
					continue
				}
				q.As = relinv(q.As)
				p = q.Pcond
				q.Pcond = q.Link
				q.Link = p
				xfol(ctxt, q.Link, last)
				p = q.Link
				if p.Mark != 0 {
					return
				}
				goto loop /* */
			}
		}
		q = ctxt.Prg()
		q.As = AJMP
		q.Lineno = p.Lineno
		q.To.Typ = D_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}
	/* emit p */
	p.Mark = 1
	(*last).Link = p
	*last = p
	a = p.As
	/* continue loop with what comes after p */
	if nofollow(a) {
		return
	}
	if p.Pcond != nil && a != ACALL {
		/*
		 * some kind of conditional branch.
		 * recurse to follow one path.
		 * continue loop on the other.
		 */
		q = liblink.Brchain(ctxt, p.Pcond)
		if q != nil {
			p.Pcond = q
		}
		q = liblink.Brchain(ctxt, p.Link)
//.........这里部分代码省略.........