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// Derived from Inferno utils/6l/obj.c and utils/6l/span.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/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/goobj"
"cmd/internal/objabi"
"fmt"
"log"
"math"
"sort"
"strings"
)
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
return ctxt
}
// LookupDerived looks up or creates the symbol with 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("$f32.%08x", i)
return ctxt.LookupInit(name, func(s *LSym) {
s.Size = 4
s.WriteFloat32(ctxt, 0, f)
s.Type = objabi.SRODATA
s.Set(AttrLocal, true)
s.Set(AttrContentAddressable, true)
ctxt.constSyms = append(ctxt.constSyms, s)
})
}
func (ctxt *Link) Float64Sym(f float64) *LSym {
i := math.Float64bits(f)
name := fmt.Sprintf("$f64.%016x", i)
return ctxt.LookupInit(name, func(s *LSym) {
s.Size = 8
s.WriteFloat64(ctxt, 0, f)
s.Type = objabi.SRODATA
s.Set(AttrLocal, true)
s.Set(AttrContentAddressable, true)
ctxt.constSyms = append(ctxt.constSyms, s)
})
}
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.WriteInt(ctxt, 0, 8, i)
s.Type = objabi.SRODATA
s.Set(AttrLocal, true)
s.Set(AttrContentAddressable, true)
ctxt.constSyms = append(ctxt.constSyms, s)
})
}
// 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() {
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
})
}
// Constant symbols are created late in the concurrent phase. Sort them
// to ensure a deterministic order.
sort.Slice(ctxt.constSyms, func(i, j int) bool {
return ctxt.constSyms[i].Name < ctxt.constSyms[j].Name
})
ctxt.Data = append(ctxt.Data, ctxt.constSyms...)
ctxt.constSyms = nil
ctxt.pkgIdx = make(map[string]int32)
ctxt.defs = []*LSym{}
ctxt.hashed64defs = []*LSym{}
ctxt.hasheddefs = []*LSym{}
ctxt.nonpkgdefs = []*LSym{}
var idx, hashedidx, hashed64idx, nonpkgidx int32
ctxt.traverseSyms(traverseDefs, func(s *LSym) {
// if Pkgpath is unknown, cannot hash symbols with relocations, as it
// may reference named symbols whose names are not fully expanded.
if s.ContentAddressable() && (ctxt.Pkgpath != "" || len(s.R) == 0) {
if s.Size <= 8 && len(s.R) == 0 && !strings.HasPrefix(s.Name, "type.") {
// We can use short hash only for symbols without relocations.
// Don't use short hash for type symbols, as they need special handling.
s.PkgIdx = goobj.PkgIdxHashed64
s.SymIdx = hashed64idx
if hashed64idx != int32(len(ctxt.hashed64defs)) {
panic("bad index")
}
ctxt.hashed64defs = append(ctxt.hashed64defs, s)
hashed64idx++
} else {
s.PkgIdx = goobj.PkgIdxHashed
s.SymIdx = hashedidx
if hashedidx != int32(len(ctxt.hasheddefs)) {
panic("bad index")
}
ctxt.hasheddefs = append(ctxt.hasheddefs, s)
hashedidx++
}
} else if isNonPkgSym(ctxt, s) {
s.PkgIdx = goobj.PkgIdxNone
s.SymIdx = nonpkgidx
if nonpkgidx != int32(len(ctxt.nonpkgdefs)) {
panic("bad index")
}
ctxt.nonpkgdefs = append(ctxt.nonpkgdefs, s)
nonpkgidx++
} else {
s.PkgIdx = goobj.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 != goobj.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 := goobj.BuiltinIdx(rs.Name, int(rs.ABI())); i != -1 {
rs.PkgIdx = goobj.PkgIdxBuiltin
rs.SymIdx = int32(i)
rs.Set(AttrIndexed, true)
return
}
}
pkg := rs.Pkg
if rs.ContentAddressable() {
// for now, only support content-addressable symbols that are always locally defined.
panic("hashed refs unsupported for now")
}
if pkg == "" || pkg == "\"\"" || pkg == "_" || !rs.Indexed() {
rs.PkgIdx = goobj.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, s *LSym) bool {
if ctxt.IsAsm && !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
}
// StaticNamePref is the prefix the front end applies to static temporary
// variables. When turned into LSyms, these can be tagged as static so
// as to avoid inserting them into the linker's name lookup tables.
const StaticNamePref = ".stmp_"
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 {
f := func(parent *LSym, aux *LSym) {
fn(aux)
}
ctxt.traverseFuncAux(flag, s, f)
}
}
}
}
}
func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent *LSym, aux *LSym)) {
fninfo := fsym.Func()
pc := &fninfo.Pcln
if flag&traverseAux == 0 {
// NB: should it become necessary to walk aux sym reloc references
// without walking the aux syms themselves, this can be changed.
panic("should not be here")
}
for _, d := range pc.Funcdata {
if d != nil {
fn(fsym, d)
}
}
files := ctxt.PosTable.FileTable()
usedFiles := make([]goobj.CUFileIndex, 0, len(pc.UsedFiles))
for f := range pc.UsedFiles {
usedFiles = append(usedFiles, f)
}
sort.Slice(usedFiles, func(i, j int) bool { return usedFiles[i] < usedFiles[j] })
for _, f := range usedFiles {
if filesym := ctxt.Lookup(files[f]); filesym != nil {
fn(fsym, filesym)
}
}
for _, call := range pc.InlTree.nodes {
if call.Func != nil {
fn(fsym, call.Func)
}
f, _ := linkgetlineFromPos(ctxt, call.Pos)
if filesym := ctxt.Lookup(f); filesym != nil {
fn(fsym, filesym)
}
}
dwsyms := []*LSym{fninfo.dwarfRangesSym, fninfo.dwarfLocSym, fninfo.dwarfDebugLinesSym, fninfo.dwarfInfoSym}
for _, dws := range dwsyms {
if dws == nil || dws.Size == 0 {
continue
}
fn(fsym, dws)
if flag&traverseRefs != 0 {
for _, r := range dws.R {
if r.Sym != nil {
fn(dws, r.Sym)
}
}
}
}
}
// Traverse aux symbols, calling fn for each sym/aux pair.
func (ctxt *Link) traverseAuxSyms(flag traverseFlag, fn func(parent *LSym, aux *LSym)) {
lists := [][]*LSym{ctxt.Text, ctxt.Data, ctxt.ABIAliases}
for _, list := range lists {
for _, s := range list {
if s.Gotype != nil {
if flag&traverseDefs != 0 {
fn(s, s.Gotype)
}
}
if s.Type != objabi.STEXT {
continue
}
ctxt.traverseFuncAux(flag, s, fn)
}
}
}