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// Copyright 2010 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.
// TODO/NICETOHAVE:
// - eliminate DW_CLS_ if not used
// - package info in compilation units
// - assign types to their packages
// - gdb uses c syntax, meaning clumsy quoting is needed for go identifiers. eg
// ptype struct '[]uint8' and qualifiers need to be quoted away
// - file:line info for variables
// - make strings a typedef so prettyprinters can see the underlying string type
package ld
import (
"cmd/internal/objabi"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"log"
)
func isDwarf64(ctxt *Link) bool {
return ctxt.HeadType == objabi.Haix
}
// dwarfSecInfo2 is a replica of the dwarfSecInfo struct but with
// *sym.Symbol content instead of loader.Sym content.
type dwarfSecInfo2 struct {
syms []*sym.Symbol
}
func (dsi *dwarfSecInfo2) secSym() *sym.Symbol {
if len(dsi.syms) == 0 {
return nil
}
return dsi.syms[0]
}
func (dsi *dwarfSecInfo2) subSyms() []*sym.Symbol {
if len(dsi.syms) == 0 {
return []*sym.Symbol{}
}
return dsi.syms[1:]
}
var dwarfp []dwarfSecInfo2
/*
* Elf.
*/
func dwarfaddshstrings(ctxt *Link, shstrtab *loader.SymbolBuilder) {
if *FlagW { // disable dwarf
return
}
secs := []string{"abbrev", "frame", "info", "loc", "line", "pubnames", "pubtypes", "gdb_scripts", "ranges"}
for _, sec := range secs {
shstrtab.Addstring(".debug_" + sec)
if ctxt.IsExternal() {
shstrtab.Addstring(elfRelType + ".debug_" + sec)
} else {
shstrtab.Addstring(".zdebug_" + sec)
}
}
}
// Add section symbols for DWARF debug info. This is called before
// dwarfaddelfheaders.
func dwarfaddelfsectionsyms(ctxt *Link) {
if *FlagW { // disable dwarf
return
}
if ctxt.LinkMode != LinkExternal {
return
}
s := ctxt.Syms.Lookup(".debug_info", 0)
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_abbrev", 0)
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_line", 0)
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_frame", 0)
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_loc", 0)
if s.Sect != nil {
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
}
s = ctxt.Syms.Lookup(".debug_ranges", 0)
if s.Sect != nil {
putelfsectionsym(ctxt, ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
}
}
// dwarfcompress compresses the DWARF sections. Relocations are applied
// on the fly. After this, dwarfp will contain a different (new) set of
// symbols, and sections may have been replaced.
func dwarfcompress(ctxt *Link) {
// compressedSect is a helper type for parallelizing compression.
type compressedSect struct {
index int
compressed []byte
syms []loader.Sym
}
supported := ctxt.IsELF || ctxt.IsWindows() || ctxt.IsDarwin()
if !ctxt.compressDWARF || !supported || ctxt.IsExternal() {
return
}
var compressedCount int
resChannel := make(chan compressedSect)
for i := range dwarfp2 {
go func(resIndex int, syms []loader.Sym) {
resChannel <- compressedSect{resIndex, compressSyms(ctxt, syms), syms}
}(compressedCount, dwarfp2[i].syms)
compressedCount++
}
res := make([]compressedSect, compressedCount)
for ; compressedCount > 0; compressedCount-- {
r := <-resChannel
res[r.index] = r
}
ldr := ctxt.loader
var newDwarfp []dwarfSecInfo
Segdwarf.Sections = Segdwarf.Sections[:0]
for _, z := range res {
s := z.syms[0]
if z.compressed == nil {
// Compression didn't help.
ds := dwarfSecInfo{syms: z.syms}
newDwarfp = append(newDwarfp, ds)
Segdwarf.Sections = append(Segdwarf.Sections, ldr.SymSect(s))
} else {
compressedSegName := ".zdebug_" + ldr.SymSect(s).Name[len(".debug_"):]
sect := addsection(ctxt.loader, ctxt.Arch, &Segdwarf, compressedSegName, 04)
sect.Align = 1
sect.Length = uint64(len(z.compressed))
newSym := ldr.CreateSymForUpdate(compressedSegName, 0)
newSym.SetReachable(true)
newSym.SetData(z.compressed)
newSym.SetSize(int64(len(z.compressed)))
ldr.SetSymSect(newSym.Sym(), sect)
ds := dwarfSecInfo{syms: []loader.Sym{newSym.Sym()}}
newDwarfp = append(newDwarfp, ds)
// compressed symbols are no longer needed.
for _, s := range z.syms {
ldr.SetAttrReachable(s, false)
ldr.FreeSym(s)
}
}
}
dwarfp2 = newDwarfp
// Re-compute the locations of the compressed DWARF symbols
// and sections, since the layout of these within the file is
// based on Section.Vaddr and Symbol.Value.
pos := Segdwarf.Vaddr
var prevSect *sym.Section
for _, si := range dwarfp2 {
for _, s := range si.syms {
ldr.SetSymValue(s, int64(pos))
sect := ldr.SymSect(s)
if sect != prevSect {
sect.Vaddr = uint64(pos)
prevSect = sect
}
if ldr.SubSym(s) != 0 {
log.Fatalf("%s: unexpected sub-symbols", ldr.SymName(s))
}
pos += uint64(ldr.SymSize(s))
if ctxt.IsWindows() {
pos = uint64(Rnd(int64(pos), PEFILEALIGN))
}
}
}
Segdwarf.Length = pos - Segdwarf.Vaddr
}
type compilationUnitByStartPC []*sym.CompilationUnit
func (v compilationUnitByStartPC) Len() int { return len(v) }
func (v compilationUnitByStartPC) Swap(i, j int) { v[i], v[j] = v[j], v[i] }
func (v compilationUnitByStartPC) Less(i, j int) bool {
switch {
case len(v[i].Textp2) == 0 && len(v[j].Textp2) == 0:
return v[i].Lib.Pkg < v[j].Lib.Pkg
case len(v[i].Textp2) != 0 && len(v[j].Textp2) == 0:
return true
case len(v[i].Textp2) == 0 && len(v[j].Textp2) != 0:
return false
default:
return v[i].PCs[0].Start < v[j].PCs[0].Start
}
}
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