Revert "Simplify a variable type by using StringRef instead of CachedHashStringRef."

This reverts commit r303787.

It caused a slowdown in fast links. That is, links with no debug info
or optimizations.

llvm-svn: 303925

lld/ELF/InputFiles.cpp

@@ -192,7 +192,7 @@ ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getSymbols() {
 }
 
 template <class ELFT>
-void elf::ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
+void elf::ObjectFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
   // Read section and symbol tables.
   initializeSections(ComdatGroups);
   initializeSymbols();
@@ -280,7 +280,7 @@ bool elf::ObjectFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
 
 template <class ELFT>
 void elf::ObjectFile<ELFT>::initializeSections(
-    DenseSet<StringRef> &ComdatGroups) {
+    DenseSet<CachedHashStringRef> &ComdatGroups) {
   ArrayRef<Elf_Shdr> ObjSections =
       check(this->getObj().sections(), toString(this));
   const ELFFile<ELFT> &Obj = this->getObj();
@@ -305,7 +305,10 @@ void elf::ObjectFile<ELFT>::initializeSections(
     switch (Sec.sh_type) {
     case SHT_GROUP:
       this->Sections[I] = &InputSection::Discarded;
-      if (ComdatGroups.insert(getShtGroupSignature(ObjSections, Sec)).second)
+      if (ComdatGroups
+              .insert(
+                  CachedHashStringRef(getShtGroupSignature(ObjSections, Sec)))
+              .second)
         continue;
       for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
         if (SecIndex >= Size)
@@ -873,10 +876,10 @@ static Symbol *createBitcodeSymbol(const std::vector<bool> &KeptComdats,
 }
 
 template <class ELFT>
-void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
+void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
   std::vector<bool> KeptComdats;
   for (StringRef S : Obj->getComdatTable())
-    KeptComdats.push_back(ComdatGroups.insert(StringRef(S)).second);
+    KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(S)).second);
 
   for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
     Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, this));
@@ -1045,10 +1048,10 @@ template void ArchiveFile::parse<ELF32BE>();
 template void ArchiveFile::parse<ELF64LE>();
 template void ArchiveFile::parse<ELF64BE>();
 
-template void BitcodeFile::parse<ELF32LE>(DenseSet<StringRef> &);
-template void BitcodeFile::parse<ELF32BE>(DenseSet<StringRef> &);
-template void BitcodeFile::parse<ELF64LE>(DenseSet<StringRef> &);
-template void BitcodeFile::parse<ELF64BE>(DenseSet<StringRef> &);
+template void BitcodeFile::parse<ELF32LE>(DenseSet<CachedHashStringRef> &);
+template void BitcodeFile::parse<ELF32BE>(DenseSet<CachedHashStringRef> &);
+template void BitcodeFile::parse<ELF64LE>(DenseSet<CachedHashStringRef> &);
+template void BitcodeFile::parse<ELF64BE>(DenseSet<CachedHashStringRef> &);
 
 template void LazyObjectFile::parse<ELF32LE>();
 template void LazyObjectFile::parse<ELF32BE>();

lld/ELF/InputFiles.h

@@ -17,6 +17,7 @@
 
 #include "lld/Core/LLVM.h"
 #include "lld/Core/Reproduce.h"
+#include "llvm/ADT/CachedHashString.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/IR/Comdat.h"
@@ -156,7 +157,7 @@ public:
   ArrayRef<SymbolBody *> getLocalSymbols();
 
   ObjectFile(MemoryBufferRef M, StringRef ArchiveName);
-  void parse(llvm::DenseSet<StringRef> &ComdatGroups);
+  void parse(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
 
   InputSectionBase *getSection(const Elf_Sym &Sym) const;
 
@@ -188,7 +189,8 @@ public:
   StringRef SourceFile;
 
 private:
-  void initializeSections(llvm::DenseSet<StringRef> &ComdatGroups);
+  void
+  initializeSections(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
   void initializeSymbols();
   void initializeDwarfLine();
   InputSectionBase *getRelocTarget(const Elf_Shdr &Sec);
@@ -263,7 +265,8 @@ public:
   BitcodeFile(MemoryBufferRef M, StringRef ArchiveName,
               uint64_t OffsetInArchive);
   static bool classof(const InputFile *F) { return F->kind() == BitcodeKind; }
-  template <class ELFT> void parse(llvm::DenseSet<StringRef> &ComdatGroups);
+  template <class ELFT>
+  void parse(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
   ArrayRef<Symbol *> getSymbols() { return Symbols; }
   std::unique_ptr<llvm::lto::InputFile> Obj;
 

lld/ELF/SymbolTable.cpp

@@ -122,7 +122,7 @@ template <class ELFT> void SymbolTable<ELFT>::addCombinedLTOObject() {
 
   for (InputFile *File : LTO->compile()) {
     ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(File);
-    DenseSet<StringRef> DummyGroups;
+    DenseSet<CachedHashStringRef> DummyGroups;
     Obj->parse(DummyGroups);
     ObjectFiles.push_back(Obj);
   }

lld/ELF/SymbolTable.h

@@ -117,7 +117,7 @@ private:
   // Comdat groups define "link once" sections. If two comdat groups have the
   // same name, only one of them is linked, and the other is ignored. This set
   // is used to uniquify them.
-  llvm::DenseSet<StringRef> ComdatGroups;
+  llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
 
   std::vector<ObjectFile<ELFT> *> ObjectFiles;
   std::vector<SharedFile<ELFT> *> SharedFiles;