[lld] r303787 - Simplify a variable type by using StringRef instead of CachedHashStringRef.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Wed May 24 13:22:27 2017
New Revision: 303787

URL: http://llvm.org/viewvc/llvm-project?rev=303787&view=rev
Log:
Simplify a variable type by using StringRef instead of CachedHashStringRef.

A variable `ComdatGroup` is not supposed to contain a large number of
items. Even when linking clang, it ends up having only 300K strings.
It doesn't make sense to use CachedHashStringRef for this hash table.
This patch has neutral or slightly positive impact on performance while
reducing code complexity.

Modified:
    lld/trunk/ELF/InputFiles.cpp
    lld/trunk/ELF/InputFiles.h
    lld/trunk/ELF/SymbolTable.cpp
    lld/trunk/ELF/SymbolTable.h

Modified: lld/trunk/ELF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=303787&r1=303786&r2=303787&view=diff
==============================================================================
--- lld/trunk/ELF/InputFiles.cpp (original)
+++ lld/trunk/ELF/InputFiles.cpp Wed May 24 13:22:27 2017
@@ -192,7 +192,7 @@ ArrayRef<SymbolBody *> elf::ObjectFile<E
 }
 
 template <class ELFT>
-void elf::ObjectFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
+void elf::ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
   // Read section and symbol tables.
   initializeSections(ComdatGroups);
   initializeSymbols();
@@ -280,7 +280,7 @@ bool elf::ObjectFile<ELFT>::shouldMerge(
 
 template <class ELFT>
 void elf::ObjectFile<ELFT>::initializeSections(
-    DenseSet<CachedHashStringRef> &ComdatGroups) {
+    DenseSet<StringRef> &ComdatGroups) {
   ArrayRef<Elf_Shdr> ObjSections =
       check(this->getObj().sections(), toString(this));
   const ELFFile<ELFT> &Obj = this->getObj();
@@ -305,10 +305,7 @@ void elf::ObjectFile<ELFT>::initializeSe
     switch (Sec.sh_type) {
     case SHT_GROUP:
       this->Sections[I] = &InputSection::Discarded;
-      if (ComdatGroups
-              .insert(
-                  CachedHashStringRef(getShtGroupSignature(ObjSections, Sec)))
-              .second)
+      if (ComdatGroups.insert(getShtGroupSignature(ObjSections, Sec)).second)
         continue;
       for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
         if (SecIndex >= Size)
@@ -876,10 +873,10 @@ static Symbol *createBitcodeSymbol(const
 }
 
 template <class ELFT>
-void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
+void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
   std::vector<bool> KeptComdats;
   for (StringRef S : Obj->getComdatTable())
-    KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(S)).second);
+    KeptComdats.push_back(ComdatGroups.insert(StringRef(S)).second);
 
   for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
     Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, this));
@@ -1048,10 +1045,10 @@ template void ArchiveFile::parse<ELF32BE
 template void ArchiveFile::parse<ELF64LE>();
 template void ArchiveFile::parse<ELF64BE>();
 
-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 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 LazyObjectFile::parse<ELF32LE>();
 template void LazyObjectFile::parse<ELF32BE>();

Modified: lld/trunk/ELF/InputFiles.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.h?rev=303787&r1=303786&r2=303787&view=diff
==============================================================================
--- lld/trunk/ELF/InputFiles.h (original)
+++ lld/trunk/ELF/InputFiles.h Wed May 24 13:22:27 2017
@@ -17,7 +17,6 @@
 
 #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"
@@ -157,7 +156,7 @@ public:
   ArrayRef<SymbolBody *> getLocalSymbols();
 
   ObjectFile(MemoryBufferRef M, StringRef ArchiveName);
-  void parse(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
+  void parse(llvm::DenseSet<StringRef> &ComdatGroups);
 
   InputSectionBase *getSection(const Elf_Sym &Sym) const;
 
@@ -189,8 +188,7 @@ public:
   StringRef SourceFile;
 
 private:
-  void
-  initializeSections(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
+  void initializeSections(llvm::DenseSet<StringRef> &ComdatGroups);
   void initializeSymbols();
   void initializeDwarfLine();
   InputSectionBase *getRelocTarget(const Elf_Shdr &Sec);
@@ -265,8 +263,7 @@ 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<llvm::CachedHashStringRef> &ComdatGroups);
+  template <class ELFT> void parse(llvm::DenseSet<StringRef> &ComdatGroups);
   ArrayRef<Symbol *> getSymbols() { return Symbols; }
   std::unique_ptr<llvm::lto::InputFile> Obj;
 

Modified: lld/trunk/ELF/SymbolTable.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=303787&r1=303786&r2=303787&view=diff
==============================================================================
--- lld/trunk/ELF/SymbolTable.cpp (original)
+++ lld/trunk/ELF/SymbolTable.cpp Wed May 24 13:22:27 2017
@@ -122,7 +122,7 @@ template <class ELFT> void SymbolTable<E
 
   for (InputFile *File : LTO->compile()) {
     ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(File);
-    DenseSet<CachedHashStringRef> DummyGroups;
+    DenseSet<StringRef> DummyGroups;
     Obj->parse(DummyGroups);
     ObjectFiles.push_back(Obj);
   }

Modified: lld/trunk/ELF/SymbolTable.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.h?rev=303787&r1=303786&r2=303787&view=diff
==============================================================================
--- lld/trunk/ELF/SymbolTable.h (original)
+++ lld/trunk/ELF/SymbolTable.h Wed May 24 13:22:27 2017
@@ -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<llvm::CachedHashStringRef> ComdatGroups;
+  llvm::DenseSet<StringRef> ComdatGroups;
 
   std::vector<ObjectFile<ELFT> *> ObjectFiles;
   std::vector<SharedFile<ELFT> *> SharedFiles;