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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
}
var dwarfp []*sym.Symbol
/*
* 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.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_abbrev", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_line", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_frame", 0)
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
s = ctxt.Syms.Lookup(".debug_loc", 0)
if s.Sect != nil {
putelfsectionsym(ctxt.Out, s, s.Sect.Elfsect.(*ElfShdr).shnum)
}
s = ctxt.Syms.Lookup(".debug_ranges", 0)
if s.Sect != nil {
putelfsectionsym(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 []*sym.Symbol
}
supported := ctxt.IsELF || ctxt.HeadType == objabi.Hwindows || ctxt.HeadType == objabi.Hdarwin
if !ctxt.compressDWARF || !supported || ctxt.LinkMode != LinkInternal {
return
}
var start, compressedCount int
resChannel := make(chan compressedSect)
for i, s := range dwarfp {
// Find the boundaries between sections and compress
// the whole section once we've found the last of its
// symbols.
if i+1 >= len(dwarfp) || s.Sect != dwarfp[i+1].Sect {
go func(resIndex int, syms []*sym.Symbol) {
resChannel <- compressedSect{resIndex, compressSyms(ctxt, syms), syms}
}(compressedCount, dwarfp[start:i+1])
compressedCount++
start = i + 1
}
}
res := make([]compressedSect, compressedCount)
for ; compressedCount > 0; compressedCount-- {
r := <-resChannel
res[r.index] = r
}
var newDwarfp []*sym.Symbol
Segdwarf.Sections = Segdwarf.Sections[:0]
for _, z := range res {
s := z.syms[0]
if z.compressed == nil {
// Compression didn't help.
newDwarfp = append(newDwarfp, z.syms...)
Segdwarf.Sections = append(Segdwarf.Sections, s.Sect)
} else {
compressedSegName := ".zdebug_" + s.Sect.Name[len(".debug_"):]
sect := addsection(ctxt.Arch, &Segdwarf, compressedSegName, 04)
sect.Length = uint64(len(z.compressed))
newSym := ctxt.Syms.Lookup(compressedSegName, 0)
newSym.P = z.compressed
newSym.Size = int64(len(z.compressed))
newSym.Sect = sect
newDwarfp = append(newDwarfp, newSym)
}
}
dwarfp = 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 _, s := range dwarfp {
s.Value = int64(pos)
if s.Sect != prevSect {
s.Sect.Vaddr = uint64(s.Value)
prevSect = s.Sect
}
if s.Sub != nil {
log.Fatalf("%s: unexpected sub-symbols", s)
}
pos += uint64(s.Size)
if ctxt.HeadType == objabi.Hwindows {
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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