[ELF] - Make few members of Writer to be global and export them for reuse

[grimar]

Summary

Creating sections on linkerscript side requires some methods
that can be reused if are exported from writer.
D19976 already uses these three.

In combination with D19977 and D19981, this one can help
to remove the noise from D19976 patch.

[grimar]

• Rebased
• Moved isDiscarded() definition to InputSections.h

[ruiu]

LGTM

ELF/Writer.cpp

124

While you are here, please remove llvm::.

ELF/InputSection.h

 #include "lld/Core/LLVM.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Object/ELF.h"
 
 namespace lld {
 namespace elf {
 
+template <class ELFT> bool isDiscarded(InputSectionBase<ELFT> *S);
+
 class SymbolBody;
 
 template <class ELFT> class ICF;
 template <class ELFT> class DefinedRegular;
 template <class ELFT> class ObjectFile;
 template <class ELFT> class OutputSection;
 template <class ELFT> class OutputSectionBase;
 

ELF/InputSection.cpp

 //===- InputSection.cpp ---------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "InputSection.h"
 #include "Config.h"
 #include "EhFrame.h"
 #include "Error.h"
 #include "InputFiles.h"
+#include "LinkerScript.h"
 #include "OutputSections.h"
 #include "Target.h"
 #include "Thunks.h"
 
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/Endian.h"
 
 using namespace llvm;
 using namespace llvm::ELF;
 using namespace llvm::object;
 using namespace llvm::support::endian;
 
 using namespace lld;
 using namespace lld::elf;
 
+template <class ELFT> bool elf::isDiscarded(InputSectionBase<ELFT> *S) {
+  return !S || S == &InputSection<ELFT>::Discarded || !S->Live ||
+         Script<ELFT>::X->isDiscarded(S);
+}
+
 template <class ELFT>
 InputSectionBase<ELFT>::InputSectionBase(elf::ObjectFile<ELFT> *File,
                                          const Elf_Shdr *Header,
                                          Kind SectionKind)
     : Header(Header), File(File), SectionKind(SectionKind), Repl(this),
       Compressed(Header->sh_flags & SHF_COMPRESSED) {
   // The garbage collector sets sections' Live bits.
   // If GC is disabled, all sections are considered live by default.
MipsOptionsInputSection<ELFT>::MipsOptionsInputSection(elf::ObjectFile<ELFT> *F,
   }
 }
 
 template <class ELFT>
 bool MipsOptionsInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
   return S->SectionKind == InputSectionBase<ELFT>::MipsOptions;
 }
 
+template bool elf::isDiscarded<ELF32LE>(InputSectionBase<ELF32LE> *);
+template bool elf::isDiscarded<ELF32BE>(InputSectionBase<ELF32BE> *);
+template bool elf::isDiscarded<ELF64LE>(InputSectionBase<ELF64LE> *);
+template bool elf::isDiscarded<ELF64BE>(InputSectionBase<ELF64BE> *);
+
 template class elf::InputSectionBase<ELF32LE>;
 template class elf::InputSectionBase<ELF32BE>;
 template class elf::InputSectionBase<ELF64LE>;
 template class elf::InputSectionBase<ELF64BE>;
 
 template class elf::InputSection<ELF32LE>;
 template class elf::InputSection<ELF32BE>;
 template class elf::InputSection<ELF64LE>;

ELF/Writer.h

 //===- Writer.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_WRITER_H
 #define LLD_ELF_WRITER_H
 
+#include <memory>
+
+namespace llvm {
+  class StringRef;
+}
+
 namespace lld {
 namespace elf {
-
+template <class ELFT> class InputSectionBase;
+template <class ELFT> class ObjectFile;
 template <class ELFT> class SymbolTable;
 
 template <class ELFT> void writeResult(SymbolTable<ELFT> *Symtab);
 
 template <class ELFT> void markLive();
+
+template <class ELFT>
+llvm::StringRef getOutputSectionName(InputSectionBase<ELFT> *S);
+
+template <class ELFT>
+void reportDiscarded(InputSectionBase<ELFT> *IS,
+                     const std::unique_ptr<elf::ObjectFile<ELFT>> &File);
 }
 }
 
 #endif

ELF/Writer.cpp

private:
   void setPhdrs();
   void fixHeaders();
   void fixSectionAlignments();
   void fixAbsoluteSymbols();
   void openFile();
   void writeHeader();
   void writeSections();
   void writeBuildId();
-  bool isDiscarded(InputSectionBase<ELFT> *IS) const;
-  StringRef getOutputSectionName(InputSectionBase<ELFT> *S) const;
   bool needsInterpSection() const {
     return !Symtab.getSharedFiles().empty() && !Config->DynamicLinker.empty();
   }
   bool isOutputDynamic() const {
     return !Symtab.getSharedFiles().empty() || Config->Pic;
   }
 
   void addCommonSymbols(std::vector<DefinedCommon *> &Syms);
private:
   SymbolTable<ELFT> &Symtab;
   std::vector<Phdr> Phdrs;
 
   uintX_t FileSize;
   uintX_t SectionHeaderOff;
 };
 } // anonymous namespace
 
+template <class ELFT>
+StringRef elf::getOutputSectionName(InputSectionBase<ELFT> *S) {
+  StringRef Dest = Script<ELFT>::X->getOutputSection(S);
+  if (!Dest.empty())
+    return Dest;
+
+  StringRef Name = S->getSectionName();
+  for (StringRef V : {".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.",
+                      ".init_array.", ".fini_array.", ".ctors.", ".dtors.",
+                      ".tbss.", ".gcc_except_table.", ".tdata."})
+    if (Name.startswith(V))
+      return V.drop_back();
+  return Name;
+}
+
+template <class ELFT>
+void elf::reportDiscarded(InputSectionBase<ELFT> *IS,
+                          const std::unique_ptr<elf::ObjectFile<ELFT>> &File) {
+  if (!Config->PrintGcSections || !IS || IS->Live)
+    return;
+  llvm::errs() << "removing unused section from '" << IS->getSectionName()
+               << "' in file '" << File->getName() << "'\n";
+}
+
 template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
   typedef typename ELFT::uint uintX_t;
   typedef typename ELFT::Ehdr Elf_Ehdr;
 
   // Create singleton output sections.
   OutputSection<ELFT> Bss(".bss", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
   DynamicSection<ELFT> Dynamic;
   EhOutputSection<ELFT> EhFrame;
for (DefinedCommon *C : Syms) {
     C->OffsetInBss = Off;
     Off += C->Size;
   }
 
   Out<ELFT>::Bss->setSize(Off);
 }
 
 template <class ELFT>
-StringRef Writer<ELFT>::getOutputSectionName(InputSectionBase<ELFT> *S) const {
-  StringRef Dest = Script<ELFT>::X->getOutputSection(S);
-  if (!Dest.empty())
-    return Dest;
-
-  StringRef Name = S->getSectionName();
-  for (StringRef V : {".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.",
-                      ".init_array.", ".fini_array.", ".ctors.", ".dtors.",
-                      ".tbss.", ".gcc_except_table.", ".tdata."})
-    if (Name.startswith(V))
-      return V.drop_back();
-  return Name;
-}
-
-template <class ELFT>
-void reportDiscarded(InputSectionBase<ELFT> *IS,
-                     const std::unique_ptr<elf::ObjectFile<ELFT>> &File) {
-  if (!Config->PrintGcSections || !IS || IS->Live)
-    return;
-  llvm::errs() << "removing unused section from '" << IS->getSectionName()
-               << "' in file '" << File->getName() << "'\n";
-}
-
-template <class ELFT>
-bool Writer<ELFT>::isDiscarded(InputSectionBase<ELFT> *S) const {
-  return !S || S == &InputSection<ELFT>::Discarded || !S->Live ||
-         Script<ELFT>::X->isDiscarded(S);
-}
-
-template <class ELFT>
 static Symbol *addOptionalSynthetic(SymbolTable<ELFT> &Table, StringRef Name,
                                     OutputSectionBase<ELFT> *Sec,
                                     typename ELFT::uint Val) {
   SymbolBody *S = Table.find(Name);
   if (!S)
     return nullptr;
   if (!S->isUndefined() && !S->isShared())
     return S->symbol();