src/cmd/internal/obj/sym.go - go - Git at Google

 // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
 // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/obj.c
 // https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/span.c
 //
 //	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 obj

 import (
 	"cmd/internal/goobj2"
 	"cmd/internal/objabi"
 	"fmt"
 	"log"
 	"math"
 	"sort"
 )

 func Linknew(arch *LinkArch) *Link {
 	ctxt := new(Link)
 	ctxt.hash = make(map[string]*LSym)
 	ctxt.funchash = make(map[string]*LSym)
 	ctxt.statichash = make(map[string]*LSym)
 	ctxt.Arch = arch
 	ctxt.Pathname = objabi.WorkingDir()

 	if err := ctxt.Headtype.Set(objabi.GOOS); err != nil {
 		log.Fatalf("unknown goos %s", objabi.GOOS)
 	}

 	ctxt.Flag_optimize = true
 	ctxt.Framepointer_enabled = objabi.Framepointer_enabled(objabi.GOOS, arch.Name)
 	return ctxt
 }

 // LookupDerived looks up or creates the symbol with name name derived from symbol s.
 // The resulting symbol will be static iff s is.
 func (ctxt *Link) LookupDerived(s *LSym, name string) *LSym {
 	if s.Static() {
 		return ctxt.LookupStatic(name)
 	}
 	return ctxt.Lookup(name)
 }

 // LookupStatic looks up the static symbol with name name.
 // If it does not exist, it creates it.
 func (ctxt *Link) LookupStatic(name string) *LSym {
 	s := ctxt.statichash[name]
 	if s == nil {
 		s = &LSym{Name: name, Attribute: AttrStatic}
 		ctxt.statichash[name] = s
 	}
 	return s
 }

 // LookupABI looks up a symbol with the given ABI.
 // If it does not exist, it creates it.
 func (ctxt *Link) LookupABI(name string, abi ABI) *LSym {
 	return ctxt.LookupABIInit(name, abi, nil)
 }

 // LookupABI looks up a symbol with the given ABI.
 // If it does not exist, it creates it and
 // passes it to init for one-time initialization.
 func (ctxt *Link) LookupABIInit(name string, abi ABI, init func(s *LSym)) *LSym {
 	var hash map[string]*LSym
 	switch abi {
 	case ABI0:
 		hash = ctxt.hash
 	case ABIInternal:
 		hash = ctxt.funchash
 	default:
 		panic("unknown ABI")
 	}

 	ctxt.hashmu.Lock()
 	s := hash[name]
 	if s == nil {
 		s = &LSym{Name: name}
 		s.SetABI(abi)
 		hash[name] = s
 		if init != nil {
 			init(s)
 		}
 	}
 	ctxt.hashmu.Unlock()
 	return s
 }

 // Lookup looks up the symbol with name name.
 // If it does not exist, it creates it.
 func (ctxt *Link) Lookup(name string) *LSym {
 	return ctxt.LookupInit(name, nil)
 }

 // LookupInit looks up the symbol with name name.
 // If it does not exist, it creates it and
 // passes it to init for one-time initialization.
 func (ctxt *Link) LookupInit(name string, init func(s *LSym)) *LSym {
 	ctxt.hashmu.Lock()
 	s := ctxt.hash[name]
 	if s == nil {
 		s = &LSym{Name: name}
 		ctxt.hash[name] = s
 		if init != nil {
 			init(s)
 		}
 	}
 	ctxt.hashmu.Unlock()
 	return s
 }

 func (ctxt *Link) Float32Sym(f float32) *LSym {
 	i := math.Float32bits(f)
 	name := fmt.Sprintf("$f32.%08x", i)
 	return ctxt.LookupInit(name, func(s *LSym) {
 		s.Size = 4
 		s.Set(AttrLocal, true)
 	})
 }

 func (ctxt *Link) Float64Sym(f float64) *LSym {
 	i := math.Float64bits(f)
 	name := fmt.Sprintf("$f64.%016x", i)
 	return ctxt.LookupInit(name, func(s *LSym) {
 		s.Size = 8
 		s.Set(AttrLocal, true)
 	})
 }

 func (ctxt *Link) Int64Sym(i int64) *LSym {
 	name := fmt.Sprintf("$i64.%016x", uint64(i))
 	return ctxt.LookupInit(name, func(s *LSym) {
 		s.Size = 8
 		s.Set(AttrLocal, true)
 	})
 }

 // Assign index to symbols.
 // asm is set to true if this is called by the assembler (i.e. not the compiler),
 // in which case all the symbols are non-package (for now).
 func (ctxt *Link) NumberSyms(asm bool) {
 	if !ctxt.Flag_newobj {
 		return
 	}

 	if ctxt.Headtype == objabi.Haix {
 		// Data must be sorted to keep a constant order in TOC symbols.
 		// As they are created during Progedit, two symbols can be switched between
 		// two different compilations. Therefore, BuildID will be different.
 		// TODO: find a better place and optimize to only sort TOC symbols
 		sort.Slice(ctxt.Data, func(i, j int) bool {
 			return ctxt.Data[i].Name < ctxt.Data[j].Name
 		})
 	}

 	ctxt.pkgIdx = make(map[string]int32)
 	ctxt.defs = []*LSym{}
 	ctxt.nonpkgdefs = []*LSym{}

 	var idx, nonpkgidx int32 = 0, 0
 	ctxt.traverseSyms(traverseDefs, func(s *LSym) {
 		if isNonPkgSym(ctxt, asm, s) {
 			s.PkgIdx = goobj2.PkgIdxNone
 			s.SymIdx = nonpkgidx
 			if nonpkgidx != int32(len(ctxt.nonpkgdefs)) {
 				panic("bad index")
 			}
 			ctxt.nonpkgdefs = append(ctxt.nonpkgdefs, s)
 			nonpkgidx++
 		} else {
 			s.PkgIdx = goobj2.PkgIdxSelf
 			s.SymIdx = idx
 			if idx != int32(len(ctxt.defs)) {
 				panic("bad index")
 			}
 			ctxt.defs = append(ctxt.defs, s)
 			idx++
 		}
 		s.Set(AttrIndexed, true)
 	})

 	ipkg := int32(1) // 0 is invalid index
 	nonpkgdef := nonpkgidx
 	ctxt.traverseSyms(traverseRefs|traverseAux, func(rs *LSym) {
 		if rs.PkgIdx != goobj2.PkgIdxInvalid {
 			return
 		}
 		if !ctxt.Flag_linkshared {
 			// Assign special index for builtin symbols.
 			// Don't do it when linking against shared libraries, as the runtime
 			// may be in a different library.
 			if i := goobj2.BuiltinIdx(rs.Name, int(rs.ABI())); i != -1 {
 				rs.PkgIdx = goobj2.PkgIdxBuiltin
 				rs.SymIdx = int32(i)
 				rs.Set(AttrIndexed, true)
 				return
 			}
 		}
 		pkg := rs.Pkg
 		if pkg == "" || pkg == "\"\"" || pkg == "_" || !rs.Indexed() {
 			rs.PkgIdx = goobj2.PkgIdxNone
 			rs.SymIdx = nonpkgidx
 			rs.Set(AttrIndexed, true)
 			if nonpkgidx != nonpkgdef+int32(len(ctxt.nonpkgrefs)) {
 				panic("bad index")
 			}
 			ctxt.nonpkgrefs = append(ctxt.nonpkgrefs, rs)
 			nonpkgidx++
 			return
 		}
 		if k, ok := ctxt.pkgIdx[pkg]; ok {
 			rs.PkgIdx = k
 			return
 		}
 		rs.PkgIdx = ipkg
 		ctxt.pkgIdx[pkg] = ipkg
 		ipkg++
 	})
 }

 // Returns whether s is a non-package symbol, which needs to be referenced
 // by name instead of by index.
 func isNonPkgSym(ctxt *Link, asm bool, s *LSym) bool {
 	if asm && !s.Static() {
 		// asm symbols are referenced by name only, except static symbols
 		// which are file-local and can be referenced by index.
 		return true
 	}
 	if ctxt.Flag_linkshared {
 		// The referenced symbol may be in a different shared library so
 		// the linker cannot see its index.
 		return true
 	}
 	if s.Pkg == "_" {
 		// The frontend uses package "_" to mark symbols that should not
 		// be referenced by index, e.g. linkname'd symbols.
 		return true
 	}
 	if s.DuplicateOK() {
 		// Dupok symbol needs to be dedup'd by name.
 		return true
 	}
 	return false
 }

 type traverseFlag uint32

 const (
 	traverseDefs traverseFlag = 1 << iota
 	traverseRefs
 	traverseAux

 	traverseAll = traverseDefs | traverseRefs | traverseAux
 )

 // Traverse symbols based on flag, call fn for each symbol.
 func (ctxt *Link) traverseSyms(flag traverseFlag, fn func(*LSym)) {
 	lists := [][]*LSym{ctxt.Text, ctxt.Data, ctxt.ABIAliases}
 	for _, list := range lists {
 		for _, s := range list {
 			if flag&traverseDefs != 0 {
 				fn(s)
 			}
 			if flag&traverseRefs != 0 {
 				for _, r := range s.R {
 					if r.Sym != nil {
 						fn(r.Sym)
 					}
 				}
 			}
 			if flag&traverseAux != 0 {
 				if s.Gotype != nil {
 					fn(s.Gotype)
 				}
 				if s.Type == objabi.STEXT {
 					pc := &s.Func.Pcln
 					for _, d := range pc.Funcdata {
 						if d != nil {
 							fn(d)
 						}
 					}
 					for _, f := range pc.File {
 						if fsym := ctxt.Lookup(f); fsym != nil {
 							fn(fsym)
 						}
 					}
 					for _, call := range pc.InlTree.nodes {
 						if call.Func != nil {
 							fn(call.Func)
 						}
 						f, _ := linkgetlineFromPos(ctxt, call.Pos)
 						if fsym := ctxt.Lookup(f); fsym != nil {
 							fn(fsym)
 						}
 					}
 				}
 			}
 		}
 	}
 }
	// Derived from Inferno utils/6l/obj.c and utils/6l/span.c
	// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/obj.c
	// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/span.c
	//
	// 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 obj

	import (
	"cmd/internal/goobj2"
	"cmd/internal/objabi"
	"fmt"
	"log"
	"math"
	"sort"
	)

	func Linknew(arch LinkArch) Link {
	ctxt := new(Link)
	ctxt.hash = make(map[string]*LSym)
	ctxt.funchash = make(map[string]*LSym)
	ctxt.statichash = make(map[string]*LSym)
	ctxt.Arch = arch
	ctxt.Pathname = objabi.WorkingDir()

	if err := ctxt.Headtype.Set(objabi.GOOS); err != nil {
	log.Fatalf("unknown goos %s", objabi.GOOS)
	}

	ctxt.Flag_optimize = true
	ctxt.Framepointer_enabled = objabi.Framepointer_enabled(objabi.GOOS, arch.Name)
	return ctxt
	}

	// LookupDerived looks up or creates the symbol with name name derived from symbol s.
	// The resulting symbol will be static iff s is.
	func (ctxt Link) LookupDerived(s LSym, name string) *LSym {
	if s.Static() {
	return ctxt.LookupStatic(name)
	}
	return ctxt.Lookup(name)
	}

	// LookupStatic looks up the static symbol with name name.
	// If it does not exist, it creates it.
	func (ctxt Link) LookupStatic(name string) LSym {
	s := ctxt.statichash[name]
	if s == nil {
	s = &LSym{Name: name, Attribute: AttrStatic}
	ctxt.statichash[name] = s
	}
	return s
	}

	// LookupABI looks up a symbol with the given ABI.
	// If it does not exist, it creates it.
	func (ctxt Link) LookupABI(name string, abi ABI) LSym {
	return ctxt.LookupABIInit(name, abi, nil)
	}

	// LookupABI looks up a symbol with the given ABI.
	// If it does not exist, it creates it and
	// passes it to init for one-time initialization.
	func (ctxt Link) LookupABIInit(name string, abi ABI, init func(s LSym)) *LSym {
	var hash map[string]*LSym
	switch abi {
	case ABI0:
	hash = ctxt.hash
	case ABIInternal:
	hash = ctxt.funchash
	default:
	panic("unknown ABI")
	}

	ctxt.hashmu.Lock()
	s := hash[name]
	if s == nil {
	s = &LSym{Name: name}
	s.SetABI(abi)
	hash[name] = s
	if init != nil {
	init(s)
	}
	}
	ctxt.hashmu.Unlock()
	return s
	}

	// Lookup looks up the symbol with name name.
	// If it does not exist, it creates it.
	func (ctxt Link) Lookup(name string) LSym {
	return ctxt.LookupInit(name, nil)
	}

	// LookupInit looks up the symbol with name name.
	// If it does not exist, it creates it and
	// passes it to init for one-time initialization.
	func (ctxt Link) LookupInit(name string, init func(s LSym)) *LSym {
	ctxt.hashmu.Lock()
	s := ctxt.hash[name]
	if s == nil {
	s = &LSym{Name: name}
	ctxt.hash[name] = s
	if init != nil {
	init(s)
	}
	}
	ctxt.hashmu.Unlock()
	return s
	}

	func (ctxt Link) Float32Sym(f float32) LSym {
	i := math.Float32bits(f)
	name := fmt.Sprintf("$f32.%08x", i)
	return ctxt.LookupInit(name, func(s *LSym) {
	s.Size = 4
	s.Set(AttrLocal, true)
	})
	}

	func (ctxt Link) Float64Sym(f float64) LSym {
	i := math.Float64bits(f)
	name := fmt.Sprintf("$f64.%016x", i)
	return ctxt.LookupInit(name, func(s *LSym) {
	s.Size = 8
	s.Set(AttrLocal, true)
	})
	}

	func (ctxt Link) Int64Sym(i int64) LSym {
	name := fmt.Sprintf("$i64.%016x", uint64(i))
	return ctxt.LookupInit(name, func(s *LSym) {
	s.Size = 8
	s.Set(AttrLocal, true)
	})
	}

	// Assign index to symbols.
	// asm is set to true if this is called by the assembler (i.e. not the compiler),
	// in which case all the symbols are non-package (for now).
	func (ctxt *Link) NumberSyms(asm bool) {
	if !ctxt.Flag_newobj {
	return
	}

	if ctxt.Headtype == objabi.Haix {
	// Data must be sorted to keep a constant order in TOC symbols.
	// As they are created during Progedit, two symbols can be switched between
	// two different compilations. Therefore, BuildID will be different.
	// TODO: find a better place and optimize to only sort TOC symbols
	sort.Slice(ctxt.Data, func(i, j int) bool {
	return ctxt.Data[i].Name < ctxt.Data[j].Name
	})
	}

	ctxt.pkgIdx = make(map[string]int32)
	ctxt.defs = []*LSym{}
	ctxt.nonpkgdefs = []*LSym{}

	var idx, nonpkgidx int32 = 0, 0
	ctxt.traverseSyms(traverseDefs, func(s *LSym) {
	if isNonPkgSym(ctxt, asm, s) {
	s.PkgIdx = goobj2.PkgIdxNone
	s.SymIdx = nonpkgidx
	if nonpkgidx != int32(len(ctxt.nonpkgdefs)) {
	panic("bad index")
	}
	ctxt.nonpkgdefs = append(ctxt.nonpkgdefs, s)
	nonpkgidx++
	} else {
	s.PkgIdx = goobj2.PkgIdxSelf
	s.SymIdx = idx
	if idx != int32(len(ctxt.defs)) {
	panic("bad index")
	}
	ctxt.defs = append(ctxt.defs, s)
	idx++
	}
	s.Set(AttrIndexed, true)
	})

	ipkg := int32(1) // 0 is invalid index
	nonpkgdef := nonpkgidx
	ctxt.traverseSyms(traverseRefs\|traverseAux, func(rs *LSym) {
	if rs.PkgIdx != goobj2.PkgIdxInvalid {
	return
	}
	if !ctxt.Flag_linkshared {
	// Assign special index for builtin symbols.
	// Don't do it when linking against shared libraries, as the runtime
	// may be in a different library.
	if i := goobj2.BuiltinIdx(rs.Name, int(rs.ABI())); i != -1 {
	rs.PkgIdx = goobj2.PkgIdxBuiltin
	rs.SymIdx = int32(i)
	rs.Set(AttrIndexed, true)
	return
	}
	}
	pkg := rs.Pkg
	if pkg == "" \|\| pkg == "\"\"" \|\| pkg == "_" \|\| !rs.Indexed() {
	rs.PkgIdx = goobj2.PkgIdxNone
	rs.SymIdx = nonpkgidx
	rs.Set(AttrIndexed, true)
	if nonpkgidx != nonpkgdef+int32(len(ctxt.nonpkgrefs)) {
	panic("bad index")
	}
	ctxt.nonpkgrefs = append(ctxt.nonpkgrefs, rs)
	nonpkgidx++
	return
	}
	if k, ok := ctxt.pkgIdx[pkg]; ok {
	rs.PkgIdx = k
	return
	}
	rs.PkgIdx = ipkg
	ctxt.pkgIdx[pkg] = ipkg
	ipkg++
	})
	}

	// Returns whether s is a non-package symbol, which needs to be referenced
	// by name instead of by index.
	func isNonPkgSym(ctxt Link, asm bool, s LSym) bool {
	if asm && !s.Static() {
	// asm symbols are referenced by name only, except static symbols
	// which are file-local and can be referenced by index.
	return true
	}
	if ctxt.Flag_linkshared {
	// The referenced symbol may be in a different shared library so
	// the linker cannot see its index.
	return true
	}
	if s.Pkg == "_" {
	// The frontend uses package "_" to mark symbols that should not
	// be referenced by index, e.g. linkname'd symbols.
	return true
	}
	if s.DuplicateOK() {
	// Dupok symbol needs to be dedup'd by name.
	return true
	}
	return false
	}

	type traverseFlag uint32

	const (
	traverseDefs traverseFlag = 1 << iota
	traverseRefs
	traverseAux

	traverseAll = traverseDefs \| traverseRefs \| traverseAux
	)

	// Traverse symbols based on flag, call fn for each symbol.
	func (ctxt Link) traverseSyms(flag traverseFlag, fn func(LSym)) {
	lists := [][]*LSym{ctxt.Text, ctxt.Data, ctxt.ABIAliases}
	for _, list := range lists {
	for _, s := range list {
	if flag&traverseDefs != 0 {
	fn(s)
	}
	if flag&traverseRefs != 0 {
	for _, r := range s.R {
	if r.Sym != nil {
	fn(r.Sym)
	}
	}
	}
	if flag&traverseAux != 0 {
	if s.Gotype != nil {
	fn(s.Gotype)
	}
	if s.Type == objabi.STEXT {
	pc := &s.Func.Pcln
	for _, d := range pc.Funcdata {
	if d != nil {
	fn(d)
	}
	}
	for _, f := range pc.File {
	if fsym := ctxt.Lookup(f); fsym != nil {
	fn(fsym)
	}
	}
	for _, call := range pc.InlTree.nodes {
	if call.Func != nil {
	fn(call.Func)
	}
	f, _ := linkgetlineFromPos(ctxt, call.Pos)
	if fsym := ctxt.Lookup(f); fsym != nil {
	fn(fsym)
	}
	}
	}
	}
	}
	}
	}