// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Writing of Go object files.
package obj
import (
"bufio"
"cmd/internal/dwarf"
"cmd/internal/objabi"
"cmd/internal/sys"
"fmt"
"log"
"path/filepath"
"sort"
"sync"
)
// objWriter writes Go object files.
type objWriter struct {
wr *bufio.Writer
ctxt *Link
// Temporary buffer for zigzag int writing.
varintbuf [10]uint8
// Provide the index of a symbol reference by symbol name.
// One map for versioned symbols and one for unversioned symbols.
// Used for deduplicating the symbol reference list.
refIdx map[string]int
vrefIdx map[string]int
// Number of objects written of each type.
nRefs int
nData int
nReloc int
nPcdata int
nAutom int
nFuncdata int
nFile int
}
func (w *objWriter) addLengths(s *LSym) {
w.nData += len(s.P)
w.nReloc += len(s.R)
if s.Type != objabi.STEXT {
return
}
pc := &s.Func.Pcln
data := 0
data += len(pc.Pcsp.P)
data += len(pc.Pcfile.P)
data += len(pc.Pcline.P)
data += len(pc.Pcinline.P)
for i := 0; i < len(pc.Pcdata); i++ {
data += len(pc.Pcdata[i].P)
}
w.nData += data
w.nPcdata += len(pc.Pcdata)
w.nAutom += len(s.Func.Autom)
w.nFuncdata += len(pc.Funcdataoff)
w.nFile += len(pc.File)
}
func (w *objWriter) writeLengths() {
w.writeInt(int64(w.nData))
w.writeInt(int64(w.nReloc))
w.writeInt(int64(w.nPcdata))
w.writeInt(int64(w.nAutom))
w.writeInt(int64(w.nFuncdata))
w.writeInt(int64(w.nFile))
}
func newObjWriter(ctxt *Link, b *bufio.Writer) *objWriter {
return &objWriter{
ctxt: ctxt,
wr: b,
vrefIdx: make(map[string]int),
refIdx: make(map[string]int),
}
}
func WriteObjFile(ctxt *Link, b *bufio.Writer) {
w := newObjWriter(ctxt, b)
// Magic header
w.wr.WriteString("\x00\x00go19ld")
// Version
w.wr.WriteByte(1)
// Autolib
for _, pkg := range ctxt.Imports {
w.writeString(pkg)
}
w.writeString("")
// Symbol references
for _, s := range ctxt.Text {
w.writeRefs(s)
w.addLengths(s)
}
for _, s := range ctxt.Data {
w.writeRefs(s)
w.addLengths(s)
}
// End symbol references
w.wr.WriteByte(0xff)
// Lengths
w.writeLengths()
// Data block
for _, s := range ctxt.Text {
w.wr.Write(s.P)
pc := &s.Func.Pcln
w.wr.Write(pc.Pcsp.P)
w.wr.Write(pc.Pcfile.P)
w.wr.Write(pc.Pcline.P)
w.wr.Write(pc.Pcinline.P)
for i := 0; i < len(pc.Pcdata); i++ {
w.wr.Write(pc.Pcdata[i].P)
}
}
for _, s := range ctxt.Data {
if len(s.P) > 0 {
switch s.Type {
case objabi.SBSS, objabi.SNOPTRBSS, objabi.STLSBSS:
ctxt.Diag("cannot provide data for %v sym %v", s.Type, s.Name)
}
}
w.wr.Write(s.P)
}
// Symbols
for _, s := range ctxt.Text {
w.writeSym(s)
}
for _, s := range ctxt.Data {
w.writeSym(s)
}
// Magic footer
w.wr.WriteString("\xff\xffgo19ld")
}
// Symbols are prefixed so their content doesn't get confused with the magic footer.
const symPrefix = 0xfe
func (w *objWriter) writeRef(s *LSym, isPath bool) {
if s == nil || s.RefIdx != 0 {
return
}
var m map[string]int
if !s.Static() {
m = w.refIdx
} else {
m = w.vrefIdx
}
if idx := m[s.Name]; idx != 0 {
s.RefIdx = idx
return
}
w.wr.WriteByte(symPrefix)
if isPath {
w.writeString(filepath.ToSlash(s.Name))
} else {
w.writeString(s.Name)
}
// Write "version".
if s.Static() {
w.writeInt(1)
} else {
w.writeInt(0)
}
w.nRefs++
s.RefIdx = w.nRefs
m[s.Name] = w.nRefs
}
func (w *objWriter) writeRefs(s *LSym) {
w.writeRef(s, false)
w.writeRef(s.Gotype, false)
for i := range s.R {
w.writeRef(s.R[i].Sym, false)
}
if s.Type == objabi.STEXT {
for _, a := range s.Func.Autom {
w.writeRef(a.Asym, false)
w.writeRef(a.Gotype, false)
}
pc := &s.Func.Pcln
for _, d := range pc.Funcdata {
w.writeRef(d, false)
}
for _, f := range pc.File {
fsym := w.ctxt.Lookup(f)
w.writeRef(fsym, true)
}
for _, call := range pc.InlTree.nodes {
w.writeRef(call.Func, false)
f, _ := linkgetlineFromPos(w.ctxt, call.Pos)
fsym := w.ctxt.Lookup(f)
w.writeRef(fsym, true)
}
}
}
func (w *objWriter) writeSymDebug(s *LSym) {
ctxt := w.ctxt
fmt.Fprintf(ctxt.Bso, "%s ", s.Name)
if s.Type != 0 {
fmt.Fprintf(ctxt.Bso, "%v ", s.Type)
}
if s.Static() {
fmt.Fprint(ctxt.Bso, "static ")
}
if s.DuplicateOK() {
fmt.Fprintf(ctxt.Bso, "dupok ")
}
if s.CFunc() {
fmt.Fprintf(ctxt.Bso, "cfunc ")
}
if s.NoSplit() {
fmt.Fprintf(ctxt.Bso, "nosplit ")
}
fmt.Fprintf(ctxt.Bso, "size=%d", s.Size)
if s.Type == objabi.STEXT {
fmt.Fprintf(ctxt.Bso, " args=%#x locals=%#x", uint64(s.Func.Args), uint64(s.Func.Locals))
if s.Leaf() {
fmt.Fprintf(ctxt.Bso, " leaf")
}
}
fmt.Fprintf(ctxt.Bso, "\n")
if s.Type == objabi.STEXT {
for p := s.Func.Text; p != nil; p = p.Link {
fmt.Fprintf(ctxt.Bso, "\t%#04x %v\n", uint(int(p.Pc)), p)
}
}
for i := 0; i < len(s.P); i += 16 {
fmt.Fprintf(ctxt.Bso, "\t%#04x", uint(i))
j := i
for j = i; j < i+16 && j < len(s.P); j++ {
fmt.Fprintf(ctxt.Bso, " %02x", s.P[j])
}
for ; j < i+16; j++ {
fmt.Fprintf(ctxt.Bso, " ")
}
fmt.Fprintf(ctxt.Bso, " ")
for j = i; j < i+16 && j < len(s.P); j++ {
c := int(s.P[j])
if ' ' <= c && c <= 0x7e {
fmt.Fprintf(ctxt.Bso, "%c", c)
} else {
fmt.Fprintf(ctxt.Bso, ".")
}
}
fmt.Fprintf(ctxt.Bso, "\n")
}
sort.Sort(relocByOff(s.R)) // generate stable output
for _, r := range s.R {
name := ""
if r.Sym != nil {
name = r.Sym.Name
} else if r.Type == objabi.R_TLS_LE {
name = "TLS"
}
if ctxt.Arch.InFamily(sys.ARM, sys.PPC64) {
fmt.Fprintf(ctxt.Bso, "\trel %d+%d t=%d %s+%x\n", int(r.Off), r.Siz, r.Type, name, uint64(r.Add))
} else {
fmt.Fprintf(ctxt.Bso, "\trel %d+%d t=%d %s+%d\n", int(r.Off), r.Siz, r.Type, name, r.Add)
}
}
}
func (w *objWriter) writeSym(s *LSym) {
ctxt := w.ctxt
if ctxt.Debugasm {
w.writeSymDebug(s)
}
w.wr.WriteByte(symPrefix)
w.wr.WriteByte(byte(s.Type))
w.writeRefIndex(s)
flags := int64(0)
if s.DuplicateOK() {
flags |= 1
}
if s.Local() {
flags |= 1 << 1
}
if s.MakeTypelink() {
flags |= 1 << 2
}
w.writeInt(flags)
w.writeInt(s.Size)
w.writeRefIndex(s.Gotype)
w.writeInt(int64(len(s.P)))
w.writeInt(int64(len(s.R)))
var r *Reloc
for i := 0; i < len(s.R); i++ {
r = &s.R[i]
w.writeInt(int64(r.Off))
w.writeInt(int64(r.Siz))
w.writeInt(int64(r.Type))
w.writeInt(r.Add)
w.writeRefIndex(r.Sym)
}
if s.Type != objabi.STEXT {
return
}
w.writeInt(int64(s.Func.Args))
w.writeInt(int64(s.Func.Locals))
if s.NoSplit() {
w.writeInt(1)
} else {
w.writeInt(0)
}
flags = int64(0)
if s.Leaf() {
flags |= 1
}
if s.CFunc() {
flags |= 1 << 1
}
if s.ReflectMethod() {
flags |= 1 << 2
}
if ctxt.Flag_shared {
flags |= 1 << 3
}
w.writeInt(flags)
w.writeInt(int64(len(s.Func.Autom)))
for _, a := range s.Func.Autom {
w.writeRefIndex(a.Asym)
w.writeInt(int64(a.Aoffset))
if a.Name == NAME_AUTO {
w.writeInt(objabi.A_AUTO)
} else if a.Name == NAME_PARAM {
w.writeInt(objabi.A_PARAM)
} else if a.Name == NAME_DELETED_AUTO {
w.writeInt(objabi.A_DELETED_AUTO)
} else {
log.Fatalf("%s: invalid local variable type %d", s.Name, a.Name)
}
w.writeRefIndex(a.Gotype)
}
pc := &s.Func.Pcln
w.writeInt(int64(len(pc.Pcsp.P)))
w.writeInt(int64(len(pc.Pcfile.P)))
w.writeInt(int64(len(pc.Pcline.P)))
w.writeInt(int64(len(pc.Pcinline.P)))
w.writeInt(int64(len(pc.Pcdata)))
for i := 0; i < len(pc.Pcdata); i++ {
w.writeInt(int64(len(pc.Pcdata[i].P)))
}
w.writeInt(int64(len(pc.Funcdataoff)))
for i := 0; i < len(pc.Funcdataoff); i++ {
w.writeRefIndex(pc.Funcdata[i])
}
for i := 0; i < len(pc.Funcdataoff); i++ {
w.writeInt(pc.Funcdataoff[i])
}
w.writeInt(int64(len(pc.File)))
for _, f := range pc.File {
fsym := ctxt.Lookup(f)
w.writeRefIndex(fsym)
}
w.writeInt(int64(len(pc.InlTree.nodes)))
for _, call := range pc.InlTree.nodes {
w.writeInt(int64(call.Parent))
f, l := linkgetlineFromPos(w.ctxt, call.Pos)
fsym := ctxt.Lookup(f)
w.writeRefIndex(fsym)
w.writeInt(int64(l))
w.writeRefIndex(call.Func)
}
}
func (w *objWriter) writeInt(sval int64) {
var v uint64
uv := (uint64(sval) << 1) ^ uint64(sval>>63)
p := w.varintbuf[:]
for v = uv; v >= 0x80; v >>= 7 {
p[0] = uint8(v | 0x80)
p = p[1:]
}
p[0] = uint8(v)
p = p[1:]
w.wr.Write(w.varintbuf[:len(w.varintbuf)-len(p)])
}
func (w *objWriter) writeString(s string) {
w.writeInt(int64(len(s)))
w.wr.WriteString(s)
}
func (w *objWriter) writeRefIndex(s *LSym) {
if s == nil {
w.writeInt(0)
return
}
if s.RefIdx == 0 {
log.Fatalln("writing an unreferenced symbol", s.Name)
}
w.writeInt(int64(s.RefIdx))
}
// relocByOff sorts relocations by their offsets.
type relocByOff []Reloc
func (x relocByOff) Len() int { return len(x) }
func (x relocByOff) Less(i, j int) bool { return x[i].Off < x[j].Off }
func (x relocByOff) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
// implement dwarf.Context
type dwCtxt struct{ *Link }
func (c dwCtxt) PtrSize() int {
return c.Arch.PtrSize
}
func (c dwCtxt) AddInt(s dwarf.Sym, size int, i int64) {
ls := s.(*LSym)
ls.WriteInt(c.Link, ls.Size, size, i)
}
func (c dwCtxt) AddBytes(s dwarf.Sym, b []byte) {
ls := s.(*LSym)
ls.WriteBytes(c.Link, ls.Size, b)
}
func (c dwCtxt) AddString(s dwarf.Sym, v string) {
ls := s.(*LSym)
ls.WriteString(c.Link, ls.Size, len(v), v)
ls.WriteInt(c.Link, ls.Size, 1, 0)
}
func (c dwCtxt) AddAddress(s dwarf.Sym, data interface{}, value int64) {
ls := s.(*LSym)
size := c.PtrSize()
if data != nil {
rsym := data.(*LSym)
ls.WriteAddr(c.Link, ls.Size, size, rsym, value)
} else {
ls.WriteInt(c.Link, ls.Size, size, value)
}
}
func (c dwCtxt) AddCURelativeAddress(s dwarf.Sym, data interface{}, value int64) {
ls := s.(*LSym)
rsym := data.(*LSym)
ls.WriteCURelativeAddr(c.Link, ls.Size, rsym, value)
}
func (c dwCtxt) AddSectionOffset(s dwarf.Sym, size int, t interface{}, ofs int64) {
ls := s.(*LSym)
rsym := t.(*LSym)
ls.WriteAddr(c.Link, ls.Size, size, rsym, ofs)
r := &ls.R[len(ls.R)-1]
r.Type = objabi.R_DWARFSECREF
}
func (c dwCtxt) AddFileRef(s dwarf.Sym, f interface{}) {
ls := s.(*LSym)
rsym := f.(*LSym)
ls.WriteAddr(c.Link, ls.Size, 4, rsym, 0)
r := &ls.R[len(ls.R)-1]
r.Type = objabi.R_DWARFFILEREF
}
func (c dwCtxt) CurrentOffset(s dwarf.Sym) int64 {
ls := s.(*LSym)
return ls.Size
}
// Here "from" is a symbol corresponding to an inlined or concrete
// function, "to" is the symbol for the corresponding abstract
// function, and "dclIdx" is the index of the symbol of interest with
// respect to the Dcl slice of the original pre-optimization version
// of the inlined function.
func (c dwCtxt) RecordDclReference(from dwarf.Sym, to dwarf.Sym, dclIdx int, inlIndex int) {
ls := from.(*LSym)
tls := to.(*LSym)
ridx := len(ls.R) - 1
c.Link.DwFixups.ReferenceChildDIE(ls, ridx, tls, dclIdx, inlIndex)
}
func (c dwCtxt) RecordChildDieOffsets(s dwarf.Sym, vars []*dwarf.Var, offsets []int32) {
ls := s.(*LSym)
c.Link.DwFixups.RegisterChildDIEOffsets(ls, vars, offsets)
}
func (c dwCtxt) Logf(format string, args ...interface{}) {
c.Link.Logf(format, args...)
}
func (ctxt *Link) dwarfSym(s *LSym) (dwarfInfoSym, dwarfLocSym, dwarfRangesSym, dwarfAbsFnSym *LSym) {
if s.Type != objabi.STEXT {
ctxt.Diag("dwarfSym of non-TEXT %v", s)
}
if s.Func.dwarfInfoSym == nil {
s.Func.dwarfInfoSym = ctxt.LookupDerived(s, dwarf.InfoPrefix+s.Name)
if ctxt.Flag_locationlists {
s.Func.dwarfLocSym = ctxt.LookupDerived(s, dwarf.LocPrefix+s.Name)
}
s.Func.dwarfRangesSym = ctxt.LookupDerived(s, dwarf.RangePrefix+s.Name)
if s.WasInlined() {
s.Func.dwarfAbsFnSym = ctxt.DwFixups.AbsFuncDwarfSym(s)
}
}
return s.Func.dwarfInfoSym, s.Func.dwarfLocSym, s.Func.dwarfRangesSym, s.Func.dwarfAbsFnSym
}
func (s *LSym) Len() int64 {
return s.Size
}
// fileSymbol returns a symbol corresponding to the source file of the
// first instruction (prog) of the specified function. This will
// presumably be the file in which the function is defined.
func (ctxt *Link) fileSymbol(fn *LSym) *LSym {
p := fn.Func.Text
if p != nil {
f, _ := linkgetlineFromPos(ctxt, p.Pos)
fsym := ctxt.Lookup(f)
return fsym
}
return nil
}
// populateDWARF fills in the DWARF Debugging Information Entries for
// TEXT symbol 's'. The various DWARF symbols must already have been
// initialized in InitTextSym.
func (ctxt *Link) populateDWARF(curfn interface{}, s *LSym, myimportpath string) {
info, loc, ranges, absfunc := ctxt.dwarfSym(s)
if info.Size != 0 {
ctxt.Diag("makeFuncDebugEntry double process %v", s)
}
var scopes []dwarf.Scope
var inlcalls dwarf.InlCalls
if ctxt.DebugInfo != nil {
scopes, inlcalls = ctxt.DebugInfo(s, curfn)
}
var err error
dwctxt := dwCtxt{ctxt}
filesym := ctxt.fileSymbol(s)
fnstate := &dwarf.FnState{
Name: s.Name,
Importpath: myimportpath,
Info: info,
Filesym: filesym,
Loc: loc,
Ranges: ranges,
Absfn: absfunc,
StartPC: s,
Size: s.Size,
External: !s.Static(),
Scopes: scopes,
InlCalls: inlcalls,
}
if absfunc != nil {
err = dwarf.PutAbstractFunc(dwctxt, fnstate)
if err != nil {
ctxt.Diag("emitting DWARF for %s failed: %v", s.Name, err)
}
err = dwarf.PutConcreteFunc(dwctxt, fnstate)
} else {
err = dwarf.PutDefaultFunc(dwctxt, fnstate)
}
if err != nil {
ctxt.Diag("emitting DWARF for %s failed: %v", s.Name, err)
}
}
// DwarfIntConst creates a link symbol for an integer constant with the
// given name, type and value.
func (ctxt *Link) DwarfIntConst(myimportpath, name, typename string, val int64) {
if myimportpath == "" {
return
}
s := ctxt.LookupInit(dwarf.ConstInfoPrefix+myimportpath, func(s *LSym) {
s.Type = objabi.SDWARFINFO
ctxt.Data = append(ctxt.Data, s)
})
dwarf.PutIntConst(dwCtxt{ctxt}, s, ctxt.Lookup(dwarf.InfoPrefix+typename), myimportpath+"."+name, val)
}
func (ctxt *Link) DwarfAbstractFunc(curfn interface{}, s *LSym, myimportpath string) {
absfn := ctxt.DwFixups.AbsFuncDwarfSym(s)
if absfn.Size != 0 {
ctxt.Diag("internal error: DwarfAbstractFunc double process %v", s)
}
if s.Func == nil {
s.Func = new(FuncInfo)
}
scopes, _ := ctxt.DebugInfo(s, curfn)
dwctxt := dwCtxt{ctxt}
filesym := ctxt.fileSymbol(s)
fnstate := dwarf.FnState{
Name: s.Name,
Importpath: myimportpath,
Info: absfn,
Filesym: filesym,
Absfn: absfn,
External: !s.Static(),
Scopes: scopes,
}
if err := dwarf.PutAbstractFunc(dwctxt, &fnstate); err != nil {
ctxt.Diag("emitting DWARF for %s failed: %v", s.Name, err)
}
}
// This table is designed to aid in the creation of references betweeen
// DWARF subprogram DIEs.
//
// In most cases when one DWARF DIE has to refer to another DWARF DIE,
// the target of the reference has an LSym, which makes it easy to use
// the existing relocation mechanism. For DWARF inlined routine DIEs,
// however, the subprogram DIE has to refer to a child
// parameter/variable DIE of the abstract subprogram. This child DIE
// doesn't have an LSym, and also of interest is the fact that when
// DWARF generation is happening for inlined function F within caller
// G, it's possible that DWARF generation hasn't happened yet for F,
// so there is no way to know the offset of a child DIE within F's
// abstract function. Making matters more complex, each inlined
// instance of F may refer to a subset of the original F's variables
// (depending on what happens with optimization, some vars may be
// eliminated).
//
// The fixup table below helps overcome this hurdle. At the point
// where a parameter/variable reference is made (via a call to
// "ReferenceChildDIE"), a fixup record is generate that records
// the relocation that is targeting that child variable. At a later
// point when the abstract function DIE is emitted, there will be
// a call to "RegisterChildDIEOffsets", at which point the offsets
// needed to apply fixups are captured. Finally, once the parallel
// portion of the compilation is done, fixups can actually be applied
// during the "Finalize" method (this can't be done during the
// parallel portion of the compile due to the possibility of data
// races).
//
// This table is also used to record the "precursor" function node for
// each function that is the target of an inline -- child DIE references
// have to be made with respect to the original pre-optimization
// version of the function (to allow for the fact that each inlined
// body may be optimized differently).
type DwarfFixupTable struct {
ctxt *Link
mu sync.Mutex
symtab map[*LSym]int // maps abstract fn LSYM to index in svec
svec []symFixups
precursor map[*LSym]fnState // maps fn Lsym to precursor Node, absfn sym
}
type symFixups struct {
fixups []relFixup
doffsets []declOffset
inlIndex int32
defseen bool
}
type declOffset struct {
// Index of variable within DCL list of pre-optimization function
dclIdx int32
// Offset of var's child DIE with respect to containing subprogram DIE
offset int32
}
type relFixup struct {
refsym *LSym
relidx int32
dclidx int32
}
type fnState struct {
// precursor function (really *gc.Node)
precursor interface{}
// abstract function symbol
absfn *LSym
}
func NewDwarfFixupTable(ctxt *Link) *DwarfFixupTable {
return &DwarfFixupTable{
ctxt: ctxt,
symtab: make(map[*LSym]int),
precursor: make(map[*LSym]fnState),
}
}
func (ft *DwarfFixupTable) GetPrecursorFunc(s *LSym) interface{} {
if fnstate, found := ft.precursor[s]; found {
return fnstate.precursor
}
return nil
}
func (ft *DwarfFixupTable) SetPrecursorFunc(s *LSym, fn interface{}) {
if _, found := ft.precursor[s]; found {
ft.ctxt.Diag("internal error: DwarfFixupTable.SetPrecursorFunc double call on %v", s)
}
// initialize abstract function symbol now. This is done here so
// as to avoid data races later on during the parallel portion of
// the back end.
absfn := ft.ctxt.LookupDerived(s, dwarf.InfoPrefix+s.Name+dwarf.AbstractFuncSuffix)
absfn.Set(AttrDuplicateOK, true)
absfn.Type = objabi.SDWARFINFO
ft.ctxt.Data = append(ft.ctxt.Data, absfn)
ft.precursor[s] = fnState{precursor: fn, absfn: absfn}
}
// Make a note of a child DIE reference: relocation 'ridx' within symbol 's'
// is targeting child 'c' of DIE with symbol 'tgt'.
func (ft *DwarfFixupTable) ReferenceChildDIE(s *LSym, ridx int, tgt *LSym, dclidx int, inlIndex int) {
// Protect against concurrent access if multiple backend workers
ft.mu.Lock()
defer ft.mu.Unlock()
// Create entry for symbol if not already present.
idx, found := ft.symtab[tgt]
if !found {
ft.svec = append(ft.svec, symFixups{inlIndex: int32(inlIndex)})
idx = len(ft.svec) - 1
ft.symtab[tgt] = idx
}
// Do we have child DIE offsets available? If so, then apply them,
// otherwise create a fixup record.
sf := &ft.svec[idx]
if len(sf.doffsets) > 0 {
found := false
for _, do := range sf.doffsets {
if do.dclIdx == int32(dclidx) {
off := do.offset
s.R[ridx].Add += int64(off)
found = true
break
}
}
if !found {
ft.ctxt.Diag("internal error: DwarfFixupTable.ReferenceChildDIE unable to locate child DIE offset for dclIdx=%d src=%v tgt=%v", dclidx, s, tgt)
}
} else {
sf.fixups = append(sf.fixups, relFixup{s, int32(ridx), int32(dclidx)})
}
}
// Called once DWARF generation is complete for a given abstract function,
// whose children might have been referenced via a call above. Stores
// the offsets for any child DIEs (vars, params) so that they can be
// consumed later in on DwarfFixupTable.Finalize, which applies any
// outstanding fixups.
func (ft *DwarfFixupTable) RegisterChildDIEOffsets(s *LSym, vars []*dwarf.Var, coffsets []int32) {
// Length of these two slices should agree
if len(vars) != len(coffsets) {
ft.ctxt.Diag("internal error: RegisterChildDIEOffsets vars/offsets length mismatch")
return
}
// Generate the slice of declOffset's based in vars/coffsets
doffsets := make([]declOffset, len(coffsets))
for i := 0; i < len(coffsets); i++ {
doffsets[i].dclIdx = vars[i].ChildIndex
doffsets[i].offset = coffsets[i]
}
ft.mu.Lock()
defer ft.mu.Unlock()
// Store offsets for this symbol.
idx, found := ft.symtab[s]
if !found {
sf := symFixups{inlIndex: -1, defseen: true, doffsets: doffsets}
ft.svec = append(ft.svec, sf)
ft.symtab[s] = len(ft.svec) - 1
} else {
sf := &ft.svec[idx]
sf.doffsets = doffsets
sf.defseen = true
}
}
func (ft *DwarfFixupTable) processFixups(slot int, s *LSym) {
sf := &ft.svec[slot]
for _, f := range sf.fixups {
dfound := false
for i := 0; i < len(sf.doffsets); i++ {
if sf.doffsets[i].dclIdx == f.dclidx {
f.refsym.R[f.relidx].Add += int64(sf.doffsets[i].offset)
dfound = true
break
}
}
if !dfound {
ft.ctxt.Diag("internal error: DwarfFixupTable has orphaned fixup on %v targeting %v relidx=%d dclidx=%d", f.refsym, s, f.relidx, f.dclidx)
}
}
}
// return the LSym corresponding to the 'abstract subprogram' DWARF
// info entry for a function.
func (ft *DwarfFixupTable) AbsFuncDwarfSym(fnsym *LSym) *LSym {
// Protect against concurrent access if multiple backend workers
ft.mu.Lock()
defer ft.mu.Unlock()
if fnstate, found := ft.precursor[fnsym]; found {
return fnstate.absfn
}
ft.ctxt.Diag("internal error: AbsFuncDwarfSym requested for %v, not seen during inlining", fnsym)
return nil
}
// Called after all functions have been compiled; the main job of this
// function is to identify cases where there are outstanding fixups.
// This scenario crops up when we have references to variables of an
// inlined routine, but that routine is defined in some other package.
// This helper walks through and locate these fixups, then invokes a
// helper to create an abstract subprogram DIE for each one.
func (ft *DwarfFixupTable) Finalize(myimportpath string, trace bool) {
if trace {
ft.ctxt.Logf("DwarfFixupTable.Finalize invoked for %s\n", myimportpath)
}
// Collect up the keys from the precursor map, then sort the
// resulting list (don't want to rely on map ordering here).
fns := make([]*LSym, len(ft.precursor))
idx := 0
for fn, _ := range ft.precursor {
fns[idx] = fn
idx++
}
sort.Sort(bySymName(fns))
// Should not be called during parallel portion of compilation.
if ft.ctxt.InParallel {
ft.ctxt.Diag("internal error: DwarfFixupTable.Finalize call during parallel backend")
}
// Generate any missing abstract functions.
for i := 0; i < len(fns); i++ {
s := fns[i]
absfn := ft.AbsFuncDwarfSym(s)
slot, found := ft.symtab[absfn]
if !found || !ft.svec[slot].defseen {
ft.ctxt.GenAbstractFunc(s)
}
}
// Apply fixups.
for i := 0; i < len(fns); i++ {
s := fns[i]
absfn := ft.AbsFuncDwarfSym(s)
slot, found := ft.symtab[absfn]
if !found {
ft.ctxt.Diag("internal error: DwarfFixupTable.Finalize orphan abstract function for %v", s)
} else {
ft.processFixups(slot, s)
}
}
}
type bySymName []*LSym
func (s bySymName) Len() int { return len(s) }
func (s bySymName) Less(i, j int) bool { return s[i].Name < s[j].Name }
func (s bySymName) Swap(i, j int) { s[i], s[j] = s[j], s[i] }