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Source file src/cmd/link/internal/ld/link.go

Documentation: cmd/link/internal/ld

  // Derived from Inferno utils/6l/l.h and related files.
  // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/l.h
  //
  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
  //	Portions Copyright © 1997-1999 Vita Nuova Limited
  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
  //	Portions Copyright © 2004,2006 Bruce Ellis
  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  
  package ld
  
  import (
  	"bufio"
  	"cmd/internal/objabi"
  	"cmd/internal/sys"
  	"cmd/link/internal/sym"
  	"debug/elf"
  	"fmt"
  )
  
  type Shlib struct {
  	Path            string
  	Hash            []byte
  	Deps            []string
  	File            *elf.File
  	gcdataAddresses map[*sym.Symbol]uint64
  }
  
  // Link holds the context for writing object code from a compiler
  // or for reading that input into the linker.
  type Link struct {
  	Out *OutBuf
  
  	Syms *sym.Symbols
  
  	Arch      *sys.Arch
  	Debugvlog int
  	Bso       *bufio.Writer
  
  	Loaded bool // set after all inputs have been loaded as symbols
  
  	IsELF    bool
  	HeadType objabi.HeadType
  
  	linkShared    bool // link against installed Go shared libraries
  	LinkMode      LinkMode
  	BuildMode     BuildMode
  	compressDWARF bool
  
  	Tlsg         *sym.Symbol
  	Libdir       []string
  	Library      []*sym.Library
  	LibraryByPkg map[string]*sym.Library
  	Shlibs       []Shlib
  	Tlsoffset    int
  	Textp        []*sym.Symbol
  	Filesyms     []*sym.Symbol
  	Moduledata   *sym.Symbol
  
  	PackageFile  map[string]string
  	PackageShlib map[string]string
  
  	tramps []*sym.Symbol // trampolines
  
  	// unresolvedSymSet is a set of erroneous unresolved references.
  	// Used to avoid duplicated error messages.
  	unresolvedSymSet map[unresolvedSymKey]bool
  
  	// Used to implement field tracking.
  	Reachparent map[*sym.Symbol]*sym.Symbol
  }
  
  type unresolvedSymKey struct {
  	from *sym.Symbol // Symbol that referenced unresolved "to"
  	to   *sym.Symbol // Unresolved symbol referenced by "from"
  }
  
  // ErrorUnresolved prints unresolved symbol error for r.Sym that is referenced from s.
  func (ctxt *Link) ErrorUnresolved(s *sym.Symbol, r *sym.Reloc) {
  	if ctxt.unresolvedSymSet == nil {
  		ctxt.unresolvedSymSet = make(map[unresolvedSymKey]bool)
  	}
  
  	k := unresolvedSymKey{from: s, to: r.Sym}
  	if !ctxt.unresolvedSymSet[k] {
  		ctxt.unresolvedSymSet[k] = true
  		// Give a special error message for main symbol (see #24809).
  		if r.Sym.Name == "main.main" {
  			Errorf(s, "function main is undeclared in the main package")
  		} else {
  			Errorf(s, "relocation target %s not defined", r.Sym.Name)
  		}
  	}
  }
  
  // The smallest possible offset from the hardware stack pointer to a local
  // variable on the stack. Architectures that use a link register save its value
  // on the stack in the function prologue and so always have a pointer between
  // the hardware stack pointer and the local variable area.
  func (ctxt *Link) FixedFrameSize() int64 {
  	switch ctxt.Arch.Family {
  	case sys.AMD64, sys.I386:
  		return 0
  	case sys.PPC64:
  		// PIC code on ppc64le requires 32 bytes of stack, and it's easier to
  		// just use that much stack always on ppc64x.
  		return int64(4 * ctxt.Arch.PtrSize)
  	default:
  		return int64(ctxt.Arch.PtrSize)
  	}
  }
  
  func (ctxt *Link) Logf(format string, args ...interface{}) {
  	fmt.Fprintf(ctxt.Bso, format, args...)
  	ctxt.Bso.Flush()
  }
  
  func addImports(ctxt *Link, l *sym.Library, pn string) {
  	pkg := objabi.PathToPrefix(l.Pkg)
  	for _, importStr := range l.ImportStrings {
  		lib := addlib(ctxt, pkg, pn, importStr)
  		if lib != nil {
  			l.Imports = append(l.Imports, lib)
  		}
  	}
  	l.ImportStrings = nil
  }
  
  type Pciter struct {
  	d       sym.Pcdata
  	p       []byte
  	pc      uint32
  	nextpc  uint32
  	pcscale uint32
  	value   int32
  	start   int
  	done    int
  }
  

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