Golang LSym.Type_方法代码示例

func readsym(b *bufio.Reader, s *liblink.LSym) {
	if !undef[s] {
		panic("double-def")
	}
	delete(undef, s)
	s.Name = rdstring(b)
	s.Extname = rdstring(b)
	s.Type_ = int16(rdint(b))
	s.Version = int16(rdint(b))
	s.Dupok = uint8(rdint(b))
	s.External = uint8(rdint(b))
	s.Nosplit = uint8(rdint(b))
	s.Reachable = uint8(rdint(b))
	s.Cgoexport = uint8(rdint(b))
	s.Special = uint8(rdint(b))
	s.Stkcheck = uint8(rdint(b))
	s.Hide = uint8(rdint(b))
	s.Leaf = uint8(rdint(b))
	s.Fnptr = uint8(rdint(b))
	s.Seenglobl = uint8(rdint(b))
	s.Onlist = uint8(rdint(b))
	s.Symid = int16(rdint(b))
	s.Dynid = int32(rdint(b))
	s.Sig = int32(rdint(b))
	s.Plt = int32(rdint(b))
	s.Got = int32(rdint(b))
	s.Align = int32(rdint(b))
	s.Elfsym = int32(rdint(b))
	s.Args = int32(rdint(b))
	s.Locals = int32(rdint(b))
	s.Value = rdint(b)
	s.Size = rdint(b)
	hashed[rdsym(b)] = true
	s.Allsym = rdsym(b)
	s.Next = rdsym(b)
	s.Sub = rdsym(b)
	s.Outer = rdsym(b)
	s.Gotype = rdsym(b)
	s.Reachparent = rdsym(b)
	s.Queue = rdsym(b)
	s.File = rdstring(b)
	s.Dynimplib = rdstring(b)
	s.Dynimpvers = rdstring(b)
	s.Text = rdprog(b)
	s.Etext = rdprog(b)
	n := int(rdint(b))
	if n > 0 {
		s.P = make([]byte, n)
		io.ReadFull(b, s.P)
	}
	s.R = make([]liblink.Reloc, int(rdint(b)))
	for i := range s.R {
		r := &s.R[i]
		r.Off = int32(rdint(b))
		r.Siz = uint8(rdint(b))
		r.Done = uint8(rdint(b))
		r.Type_ = int32(rdint(b))
		r.Add = rdint(b)
		r.Xadd = rdint(b)
		r.Sym = rdsym(b)
		r.Xsym = rdsym(b)
	}
}

func progedit(ctxt *liblink.Link, p *liblink.Prog) {
	var literal string
	var s *liblink.LSym
	var q *liblink.Prog

	// See obj6.c for discussion of TLS.
	if canuselocaltls(ctxt) != 0 {

		// Reduce TLS initial exec model to TLS local exec model.
		// Sequences like
		//	MOVL TLS, BX
		//	... off(BX)(TLS*1) ...
		// become
		//	NOP
		//	... off(TLS) ...
		if p.As == AMOVL && p.From.Type_ == D_TLS && D_AX <= p.To.Type_ && p.To.Type_ <= D_DI {

			p.As = ANOP
			p.From.Type_ = D_NONE
			p.To.Type_ = D_NONE
		}

		if p.From.Index == D_TLS && D_INDIR+D_AX <= p.From.Type_ && p.From.Type_ <= D_INDIR+D_DI {
			p.From.Type_ = D_INDIR + D_TLS
			p.From.Scale = 0
			p.From.Index = D_NONE
		}

		if p.To.Index == D_TLS && D_INDIR+D_AX <= p.To.Type_ && p.To.Type_ <= D_INDIR+D_DI {
			p.To.Type_ = D_INDIR + D_TLS
			p.To.Scale = 0
			p.To.Index = D_NONE
		}
	} else {

		// As a courtesy to the C compilers, rewrite TLS local exec load as TLS initial exec load.
		// The instruction
		//	MOVL off(TLS), BX
		// becomes the sequence
		//	MOVL TLS, BX
		//	MOVL off(BX)(TLS*1), BX
		// This allows the C compilers to emit references to m and g using the direct off(TLS) form.
		if p.As == AMOVL && p.From.Type_ == D_INDIR+D_TLS && D_AX <= p.To.Type_ && p.To.Type_ <= D_DI {

			q = liblink.Appendp(ctxt, p)
			q.As = p.As
			q.From = p.From
			q.From.Type_ = D_INDIR + p.To.Type_
			q.From.Index = D_TLS
			q.From.Scale = 2 // TODO: use 1
			q.To = p.To
			p.From.Type_ = D_TLS
			p.From.Index = D_NONE
			p.From.Offset = 0
		}
	}

	// TODO: Remove.
	if ctxt.Headtype == liblink.Hplan9 {

		if p.From.Scale == 1 && p.From.Index == D_TLS {
			p.From.Scale = 2
		}
		if p.To.Scale == 1 && p.To.Index == D_TLS {
			p.To.Scale = 2
		}
	}

	// Rewrite CALL/JMP/RET to symbol as D_BRANCH.
	switch p.As {

	case ACALL,
		AJMP,
		ARET:
		if (p.To.Type_ == D_EXTERN || p.To.Type_ == D_STATIC) && p.To.Sym != nil {
			p.To.Type_ = D_BRANCH
		}
		break
	}

	// Rewrite float constants to values stored in memory.
	switch p.As {

	// Convert AMOVSS $(0), Xx to AXORPS Xx, Xx
	case AMOVSS:
		if p.From.Type_ == D_FCONST {

			if p.From.U.Dval == 0 {
				if p.To.Type_ >= D_X0 {
					if p.To.Type_ <= D_X7 {
						p.As = AXORPS
						p.From.Type_ = p.To.Type_
						p.From.Index = p.To.Index
						break
					}
				}
			}
		}
		fallthrough

//.........这里部分代码省略.........

func progedit(ctxt *liblink.Link, p *liblink.Prog) {
	var literal string
	var s *liblink.LSym
	var tlsfallback *liblink.LSym

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

	// Rewrite B/BL to symbol as D_BRANCH.
	switch p.As {

	case AB,
		ABL,
		ADUFFZERO,
		ADUFFCOPY:
		if p.To.Type_ == D_OREG && (p.To.Name == D_EXTERN || p.To.Name == D_STATIC) && p.To.Sym != nil {
			p.To.Type_ = D_BRANCH
		}
		break
	}

	// 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("%L: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Lineno)
			}

			if ctxt.Goarm < 7 {
				// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
				if tlsfallback == nil {

					tlsfallback = liblink.Linklookup(ctxt, "runtime.read_tls_fallback", 0)
				}

				// MOVW	LR, R11
				p.As = AMOVW

				p.From.Type_ = D_REG
				p.From.Reg = REGLINK
				p.To.Type_ = D_REG
				p.To.Reg = REGTMP

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

				p.As = ABL
				p.To.Type_ = D_BRANCH
				p.To.Sym = tlsfallback
				p.To.Offset = 0

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

				p.As = AMOVW
				p.From.Type_ = D_REG
				p.From.Reg = REGTMP
				p.To.Type_ = D_REG
				p.To.Reg = REGLINK
				break
			}
		}

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

		break
	}

	// Rewrite float constants to values stored in memory.
	switch p.As {

	case AMOVF:
		if p.From.Type_ == D_FCONST && chipfloat5(ctxt, p.From.U.Dval) < 0 && (chipzero5(ctxt, p.From.U.Dval) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
			var i32 uint32
			var f32 float32
			f32 = float32(p.From.U.Dval)
			i32 = math.Float32bits(f32)
			literal = fmt.Sprintf("$f32.%08x", i32)
			s = liblink.Linklookup(ctxt, literal, 0)
			if s.Type_ == 0 {
				s.Type_ = liblink.SRODATA
				liblink.Adduint32(ctxt, s, i32)
				s.Reachable = 0
			}

			p.From.Type_ = D_OREG
			p.From.Sym = s
			p.From.Name = D_EXTERN
			p.From.Offset = 0
		}

	case AMOVD:
//.........这里部分代码省略.........

func progedit(ctxt *liblink.Link, p *liblink.Prog) {
	var literal string
	var s *liblink.LSym
	var q *liblink.Prog

	// 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 8(AX)(TLS*1), CX // load m 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 8(TLS), CX // load m into CX
	//
	// The 2-instruction and 1-instruction forms correspond roughly to
	// ELF TLS initial exec mode and ELF TLS local exec mode, respectively.
	//
	// We applies this rewrite on systems that support the 1-instruction form.
	// The decision is made using only the operating system (and probably
	// the -shared flag, eventually), 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.

	if canuselocaltls(ctxt) != 0 {

		// Reduce TLS initial exec model to TLS local exec model.
		// 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_ == D_TLS && D_AX <= p.To.Type_ && p.To.Type_ <= D_R15 && ctxt.Headtype != liblink.Hsolaris {

			nopout(p)
		}
		if p.From.Index == D_TLS && D_INDIR+D_AX <= p.From.Type_ && p.From.Type_ <= D_INDIR+D_R15 {
			p.From.Type_ = D_INDIR + D_TLS
			p.From.Scale = 0
			p.From.Index = D_NONE
		}

		if p.To.Index == D_TLS && D_INDIR+D_AX <= p.To.Type_ && p.To.Type_ <= D_INDIR+D_R15 {
			p.To.Type_ = D_INDIR + D_TLS
			p.To.Scale = 0
			p.To.Index = D_NONE
		}
	} else {

		// As a courtesy to the C compilers, rewrite TLS local exec load as TLS initial exec load.
		// The instruction
		//	MOVQ off(TLS), BX
		// becomes the sequence
		//	MOVQ TLS, BX
		//	MOVQ off(BX)(TLS*1), BX
		// This allows the C compilers to emit references to m and g using the direct off(TLS) form.
		if (p.As == AMOVQ || p.As == AMOVL) && p.From.Type_ == D_INDIR+D_TLS && D_AX <= p.To.Type_ && p.To.Type_ <= D_R15 {

			q = liblink.Appendp(ctxt, p)
			q.As = p.As
			q.From = p.From
			q.From.Type_ = D_INDIR + p.To.Type_
			q.From.Index = D_TLS
			q.From.Scale = 2 // TODO: use 1
			q.To = p.To
			p.From.Type_ = D_TLS
			p.From.Index = D_NONE
			p.From.Offset = 0
		}
	}

	// TODO: Remove.
	if ctxt.Headtype == liblink.Hwindows || ctxt.Headtype == liblink.Hplan9 {

		if p.From.Scale == 1 && p.From.Index == D_TLS {
			p.From.Scale = 2
		}
		if p.To.Scale == 1 && p.To.Index == D_TLS {
			p.To.Scale = 2
		}
	}
//.........这里部分代码省略.........