[ELF] Convert GdbIndexSection to input section

[grimar]

For me - looks good.

[ruiu]

LGTM

ELF/OutputSections.h

 //===- OutputSections.h -----------------------------------------*- C++ -*-===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLD_ELF_OUTPUT_SECTIONS_H
 #define LLD_ELF_OUTPUT_SECTIONS_H
 
 #include "Config.h"
-#include "GdbIndex.h"
 #include "Relocations.h"
 
 #include "lld/Core/LLVM.h"
 #include "llvm/MC/StringTableBuilder.h"
 #include "llvm/Object/ELF.h"
 
 namespace lld {
 namespace elf {
public:
   uint64_t LMAOffset = 0;
   uint64_t Addr = 0;
   uint32_t ShName = 0;
   uint32_t Type = 0;
   uint32_t Info = 0;
   uint32_t Link = 0;
 };
 
-template <class ELFT> class GdbIndexSection final : public OutputSectionBase {
-  typedef typename ELFT::uint uintX_t;
-
-  const unsigned OffsetTypeSize = 4;
-  const unsigned CuListOffset = 6 * OffsetTypeSize;
-  const unsigned CompilationUnitSize = 16;
-  const unsigned AddressEntrySize = 16 + OffsetTypeSize;
-  const unsigned SymTabEntrySize = 2 * OffsetTypeSize;
-
-public:
-  GdbIndexSection();
-  void finalize() override;
-  void writeTo(uint8_t *Buf) override;
-
-  // Pairs of [CU Offset, CU length].
-  std::vector<std::pair<uintX_t, uintX_t>> CompilationUnits;
-
-private:
-  void parseDebugSections();
-  void readDwarf(InputSection<ELFT> *I);
-
-  uint32_t CuTypesOffset;
-};
-
 // For more information about .gnu.version and .gnu.version_r see:
 // https://www.akkadia.org/drepper/symbol-versioning
 
 // The .gnu.version_d section which has a section type of SHT_GNU_verdef shall
 // contain symbol version definitions. The number of entries in this section
 // shall be contained in the DT_VERDEFNUM entry of the .dynamic section.
 // The section shall contain an array of Elf_Verdef structures, optionally
 // followed by an array of Elf_Verdaux structures.

 // until Writer is initialized.
 template <class ELFT> struct Out {
   typedef typename ELFT::uint uintX_t;
   typedef typename ELFT::Phdr Elf_Phdr;
 
   static uint8_t First;
   static EhFrameHeader<ELFT> *EhFrameHdr;
   static EhOutputSection<ELFT> *EhFrame;
-  static GdbIndexSection<ELFT> *GdbIndex;
   static OutputSection<ELFT> *Bss;
   static OutputSection<ELFT> *MipsRldMap;
   static OutputSectionBase *Opd;
   static uint8_t *OpdBuf;
   static VersionDefinitionSection<ELFT> *VerDef;
   static VersionTableSection<ELFT> *VerSym;
   static VersionNeedSection<ELFT> *VerNeed;
   static Elf_Phdr *TlsPhdr;
template <class ELFT> uint64_t getHeaderSize() {
   if (Config->OFormatBinary)
     return 0;
   return Out<ELFT>::ElfHeader->Size + Out<ELFT>::ProgramHeaders->Size;
 }
 
 template <class ELFT> uint8_t Out<ELFT>::First;
 template <class ELFT> EhFrameHeader<ELFT> *Out<ELFT>::EhFrameHdr;
 template <class ELFT> EhOutputSection<ELFT> *Out<ELFT>::EhFrame;
-template <class ELFT> GdbIndexSection<ELFT> *Out<ELFT>::GdbIndex;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::MipsRldMap;
 template <class ELFT> OutputSectionBase *Out<ELFT>::Opd;
 template <class ELFT> uint8_t *Out<ELFT>::OpdBuf;
 template <class ELFT> VersionDefinitionSection<ELFT> *Out<ELFT>::VerDef;
 template <class ELFT> VersionTableSection<ELFT> *Out<ELFT>::VerSym;
 template <class ELFT> VersionNeedSection<ELFT> *Out<ELFT>::VerNeed;
 template <class ELFT> typename ELFT::Phdr *Out<ELFT>::TlsPhdr;

ELF/OutputSections.cpp

 //===- OutputSections.cpp -------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "OutputSections.h"
 #include "Config.h"
 #include "EhFrame.h"
-#include "GdbIndex.h"
 #include "LinkerScript.h"
 #include "Memory.h"
 #include "Strings.h"
 #include "SymbolListFile.h"
 #include "SymbolTable.h"
 #include "SyntheticSections.h"
 #include "Target.h"
 #include "lld/Core/Parallel.h"
void OutputSectionBase::writeHeaderTo(typename ELFT::Shdr *Shdr) {
   Shdr->sh_flags = Flags;
   Shdr->sh_info = Info;
   Shdr->sh_link = Link;
   Shdr->sh_addr = Addr;
   Shdr->sh_size = Size;
   Shdr->sh_name = ShName;
 }
 
-template <class ELFT>
-GdbIndexSection<ELFT>::GdbIndexSection()
-    : OutputSectionBase(".gdb_index", SHT_PROGBITS, 0) {}
-
-template <class ELFT> void GdbIndexSection<ELFT>::parseDebugSections() {
-  std::vector<InputSection<ELFT> *> &IS =
-      static_cast<OutputSection<ELFT> *>(Out<ELFT>::DebugInfo)->Sections;
-
-  for (InputSection<ELFT> *I : IS)
-    readDwarf(I);
-}
-
-template <class ELFT>
-void GdbIndexSection<ELFT>::readDwarf(InputSection<ELFT> *I) {
-  std::vector<std::pair<uintX_t, uintX_t>> CuList = readCuList(I);
-  CompilationUnits.insert(CompilationUnits.end(), CuList.begin(), CuList.end());
-}
-
-template <class ELFT> void GdbIndexSection<ELFT>::finalize() {
-  parseDebugSections();
-
-  // GdbIndex header consist from version fields
-  // and 5 more fields with different kinds of offsets.
-  CuTypesOffset = CuListOffset + CompilationUnits.size() * CompilationUnitSize;
-  this->Size = CuTypesOffset;
-}
-
-template <class ELFT> void GdbIndexSection<ELFT>::writeTo(uint8_t *Buf) {
-  write32le(Buf, 7);                  // Write Version
-  write32le(Buf + 4, CuListOffset);   // CU list offset
-  write32le(Buf + 8, CuTypesOffset);  // Types CU list offset
-  write32le(Buf + 12, CuTypesOffset); // Address area offset
-  write32le(Buf + 16, CuTypesOffset); // Symbol table offset
-  write32le(Buf + 20, CuTypesOffset); // Constant pool offset
-  Buf += 24;
-
-  // Write the CU list.
-  for (std::pair<uintX_t, uintX_t> CU : CompilationUnits) {
-    write64le(Buf, CU.first);
-    write64le(Buf + 8, CU.second);
-    Buf += 16;
-  }
-}
-
 // Returns the number of version definition entries. Because the first entry
 // is for the version definition itself, it is the number of versioned symbols
 // plus one. Note that we don't support multiple versions yet.
 static unsigned getVerDefNum() { return Config->VersionDefinitions.size() + 1; }
 
 template <class ELFT>
 EhFrameHeader<ELFT>::EhFrameHeader()
     : OutputSectionBase(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC) {}

 template class VersionNeedSection<ELF64LE>;
 template class VersionNeedSection<ELF64BE>;
 
 template class VersionDefinitionSection<ELF32LE>;
 template class VersionDefinitionSection<ELF32BE>;
 template class VersionDefinitionSection<ELF64LE>;
 template class VersionDefinitionSection<ELF64BE>;
 
-template class GdbIndexSection<ELF32LE>;
-template class GdbIndexSection<ELF32BE>;
-template class GdbIndexSection<ELF64LE>;
-template class GdbIndexSection<ELF64BE>;
-
 template class OutputSectionFactory<ELF32LE>;
 template class OutputSectionFactory<ELF32BE>;
 template class OutputSectionFactory<ELF64LE>;
 template class OutputSectionFactory<ELF64BE>;
 }
 }

ELF/SyntheticSections.h

 //===- SyntheticSection.h ---------------------------------------*- C++ -*-===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLD_ELF_SYNTHETIC_SECTION_H
 #define LLD_ELF_SYNTHETIC_SECTION_H
 
+#include "GdbIndex.h"
 #include "InputSection.h"
 #include "llvm/ADT/SmallPtrSet.h"
 
 namespace lld {
 namespace elf {
 
 // .MIPS.abiflags section.
 template <class ELFT>
public:
   size_t getSize() const override;
   void addEntry(SymbolBody &Sym);
   bool empty() const { return Entries.empty(); }
 
 private:
   std::vector<std::pair<const SymbolBody *, unsigned>> Entries;
 };
 
+template <class ELFT>
+class GdbIndexSection final : public SyntheticSection<ELFT> {
+  typedef typename ELFT::uint uintX_t;
+
+  const unsigned OffsetTypeSize = 4;
+  const unsigned CuListOffset = 6 * OffsetTypeSize;
+  const unsigned CompilationUnitSize = 16;
+  const unsigned AddressEntrySize = 16 + OffsetTypeSize;
+  const unsigned SymTabEntrySize = 2 * OffsetTypeSize;
+
+public:
+  GdbIndexSection();
+  void finalize() override;
+  void writeTo(uint8_t *Buf) override;
+  size_t getSize() const override { return CuTypesOffset; }
+
+  // Pairs of [CU Offset, CU length].
+  std::vector<std::pair<uintX_t, uintX_t>> CompilationUnits;
+
+private:
+  void parseDebugSections();
+  void readDwarf(InputSection<ELFT> *I);
+
+  uint32_t CuTypesOffset;
+};
+
 template <class ELFT> InputSection<ELFT> *createCommonSection();
 template <class ELFT> InputSection<ELFT> *createInterpSection();
 template <class ELFT> MergeInputSection<ELFT> *createCommentSection();
 
 // Linker generated sections which can be used as inputs.
 template <class ELFT> struct In {
   static BuildIdSection<ELFT> *BuildId;
   static InputSection<ELFT> *Common;
   static DynamicSection<ELFT> *Dynamic;
   static StringTableSection<ELFT> *DynStrTab;
   static SymbolTableSection<ELFT> *DynSymTab;
   static GnuHashTableSection<ELFT> *GnuHashTab;
+  static GdbIndexSection<ELFT> *GdbIndex;
   static GotSection<ELFT> *Got;
   static MipsGotSection<ELFT> *MipsGot;
   static GotPltSection<ELFT> *GotPlt;
   static HashTableSection<ELFT> *HashTab;
   static InputSection<ELFT> *Interp;
   static MipsAbiFlagsSection<ELFT> *MipsAbiFlags;
   static MipsOptionsSection<ELFT> *MipsOptions;
   static MipsReginfoSection<ELFT> *MipsReginfo;
   static PltSection<ELFT> *Plt;
   static RelocationSection<ELFT> *RelaDyn;
   static RelocationSection<ELFT> *RelaPlt;
   static StringTableSection<ELFT> *ShStrTab;
   static StringTableSection<ELFT> *StrTab;
   static SymbolTableSection<ELFT> *SymTab;
 };
 
 template <class ELFT> BuildIdSection<ELFT> *In<ELFT>::BuildId;
 template <class ELFT> InputSection<ELFT> *In<ELFT>::Common;
 template <class ELFT> DynamicSection<ELFT> *In<ELFT>::Dynamic;
 template <class ELFT> StringTableSection<ELFT> *In<ELFT>::DynStrTab;
 template <class ELFT> SymbolTableSection<ELFT> *In<ELFT>::DynSymTab;
+template <class ELFT> GdbIndexSection<ELFT> *In<ELFT>::GdbIndex;
 template <class ELFT> GnuHashTableSection<ELFT> *In<ELFT>::GnuHashTab;
 template <class ELFT> GotSection<ELFT> *In<ELFT>::Got;
 template <class ELFT> MipsGotSection<ELFT> *In<ELFT>::MipsGot;
 template <class ELFT> GotPltSection<ELFT> *In<ELFT>::GotPlt;
 template <class ELFT> HashTableSection<ELFT> *In<ELFT>::HashTab;
 template <class ELFT> InputSection<ELFT> *In<ELFT>::Interp;
 template <class ELFT> MipsAbiFlagsSection<ELFT> *In<ELFT>::MipsAbiFlags;
 template <class ELFT> MipsOptionsSection<ELFT> *In<ELFT>::MipsOptions;

ELF/SyntheticSections.cpp

template <class ELFT> void PltSection<ELFT>::addEntry(SymbolBody &Sym) {
   unsigned RelOff = In<ELFT>::RelaPlt->getRelocOffset();
   Entries.push_back(std::make_pair(&Sym, RelOff));
 }
 
 template <class ELFT> size_t PltSection<ELFT>::getSize() const {
   return Target->PltHeaderSize + Entries.size() * Target->PltEntrySize;
 }
 
+template <class ELFT>
+GdbIndexSection<ELFT>::GdbIndexSection()
+    : SyntheticSection<ELFT>(0, SHT_PROGBITS, 1, ".gdb_index") {}
+
+template <class ELFT> void GdbIndexSection<ELFT>::parseDebugSections() {
+  std::vector<InputSection<ELFT> *> &IS =
+      static_cast<OutputSection<ELFT> *>(Out<ELFT>::DebugInfo)->Sections;
+
+  for (InputSection<ELFT> *I : IS)
+    readDwarf(I);
+}
+
+template <class ELFT>
+void GdbIndexSection<ELFT>::readDwarf(InputSection<ELFT> *I) {
+  std::vector<std::pair<uintX_t, uintX_t>> CuList = readCuList(I);
+  CompilationUnits.insert(CompilationUnits.end(), CuList.begin(), CuList.end());
+}
+
+template <class ELFT> void GdbIndexSection<ELFT>::finalize() {
+  parseDebugSections();
+
+  // GdbIndex header consist from version fields
+  // and 5 more fields with different kinds of offsets.
+  CuTypesOffset = CuListOffset + CompilationUnits.size() * CompilationUnitSize;
+}
+
+template <class ELFT> void GdbIndexSection<ELFT>::writeTo(uint8_t *Buf) {
+  write32le(Buf, 7);                  // Write Version
+  write32le(Buf + 4, CuListOffset);   // CU list offset
+  write32le(Buf + 8, CuTypesOffset);  // Types CU list offset
+  write32le(Buf + 12, CuTypesOffset); // Address area offset
+  write32le(Buf + 16, CuTypesOffset); // Symbol table offset
+  write32le(Buf + 20, CuTypesOffset); // Constant pool offset
+  Buf += 24;
+
+  // Write the CU list.
+  for (std::pair<uintX_t, uintX_t> CU : CompilationUnits) {
+    write64le(Buf, CU.first);
+    write64le(Buf + 8, CU.second);
+    Buf += 16;
+  }
+}
+
 template InputSection<ELF32LE> *elf::createCommonSection();
 template InputSection<ELF32BE> *elf::createCommonSection();
 template InputSection<ELF64LE> *elf::createCommonSection();
 template InputSection<ELF64BE> *elf::createCommonSection();
 
 template InputSection<ELF32LE> *elf::createInterpSection();
 template InputSection<ELF32BE> *elf::createInterpSection();
 template InputSection<ELF64LE> *elf::createInterpSection();

 template class elf::HashTableSection<ELF32BE>;
 template class elf::HashTableSection<ELF64LE>;
 template class elf::HashTableSection<ELF64BE>;
 
 template class elf::PltSection<ELF32LE>;
 template class elf::PltSection<ELF32BE>;
 template class elf::PltSection<ELF64LE>;
 template class elf::PltSection<ELF64BE>;
+
+template class elf::GdbIndexSection<ELF32LE>;
+template class elf::GdbIndexSection<ELF32BE>;
+template class elf::GdbIndexSection<ELF64LE>;
+template class elf::GdbIndexSection<ELF64BE>;

ELF/Writer.cpp

template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
   if (Config->EhFrameHdr)
     Out<ELFT>::EhFrameHdr = make<EhFrameHeader<ELFT>>();
 
   if (Config->GnuHash)
     In<ELFT>::GnuHashTab = make<GnuHashTableSection<ELFT>>();
   if (Config->SysvHash)
     In<ELFT>::HashTab = make<HashTableSection<ELFT>>();
   if (Config->GdbIndex)
-    Out<ELFT>::GdbIndex = make<GdbIndexSection<ELFT>>();
+    In<ELFT>::GdbIndex = make<GdbIndexSection<ELFT>>();
 
   In<ELFT>::RelaPlt = make<RelocationSection<ELFT>>(
       Config->Rela ? ".rela.plt" : ".rel.plt", false /*Sort*/);
   if (Config->Strip != StripPolicy::All) {
     In<ELFT>::StrTab = make<StringTableSection<ELFT>>(".strtab", false);
     In<ELFT>::SymTab = make<SymbolTableSection<ELFT>>(*In<ELFT>::StrTab);
   }
 
template <class ELFT> void Writer<ELFT>::finalizeSections() {
   for (OutputSectionBase *Sec : OutputSections)
     Sec->finalize();
 
   // Dynamic section must be the last one in this list and dynamic
   // symbol table section (DynSymTab) must be the first one.
   finalizeSynthetic<ELFT>(
       {In<ELFT>::DynSymTab, In<ELFT>::GnuHashTab, In<ELFT>::HashTab,
        In<ELFT>::SymTab, In<ELFT>::ShStrTab, In<ELFT>::StrTab,
-       In<ELFT>::DynStrTab, In<ELFT>::Got, In<ELFT>::MipsGot, In<ELFT>::GotPlt,
-       In<ELFT>::RelaDyn, In<ELFT>::RelaPlt, In<ELFT>::Plt, In<ELFT>::Dynamic});
+       In<ELFT>::DynStrTab, In<ELFT>::GdbIndex, In<ELFT>::Got,
+       In<ELFT>::MipsGot, In<ELFT>::GotPlt, In<ELFT>::RelaDyn,
+       In<ELFT>::RelaPlt, In<ELFT>::Plt, In<ELFT>::Dynamic});
 }
 
 template <class ELFT> bool Writer<ELFT>::needsGot() {
   // We add the .got section to the result for dynamic MIPS target because
   // its address and properties are mentioned in the .dynamic section.
   if (Config->EMachine == EM_MIPS)
     return !Config->Relocatable;
 

 template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
   auto Add = [&](OutputSectionBase *OS) {
     if (OS)
       OutputSections.push_back(OS);
   };
 
   // This order is not the same as the final output order
   // because we sort the sections using their attributes below.
-  if (Out<ELFT>::GdbIndex && Out<ELFT>::DebugInfo)
-    Add(Out<ELFT>::GdbIndex);
+  if (In<ELFT>::GdbIndex && Out<ELFT>::DebugInfo)
+    addInputSec(In<ELFT>::GdbIndex);
   addInputSec(In<ELFT>::SymTab);
   addInputSec(In<ELFT>::ShStrTab);
   addInputSec(In<ELFT>::StrTab);
   if (In<ELFT>::DynSymTab) {
     addInputSec(In<ELFT>::DynSymTab);
 
     bool HasVerNeed = Out<ELFT>::VerNeed->getNeedNum() != 0;
     if (Out<ELFT>::VerDef || HasVerNeed)