Convert a few getName() methods to return a const string ref.

src/IceELFObjectWriter.cpp

@@ -541,7 +541,7 @@ void ELFObjectWriter::writeAllRelocationSections(bool IsELF64) {
 void ELFObjectWriter::setUndefinedSyms(const ConstantList &UndefSyms) {
   for (const Constant *S : UndefSyms) {
     const auto Sym = llvm::cast<ConstantRelocatable>(S);
-    IceString Name = Sym->getName();
+    const IceString &Name = Sym->getName();
     assert(Sym->getOffset() == 0);
     assert(Sym->getSuppressMangling());
     SymTab->noteUndefinedSym(Name, NullSection);

src/IceELFSection.h

@@ -66,7 +66,7 @@ public:
 
   void setNameStrIndex(Elf64_Word sh_name) { Header.sh_name = sh_name; }
 
-  IceString getName() const { return Name; }
+  const IceString &getName() const { return Name; }
 
   void setLinkNum(Elf64_Word sh_link) { Header.sh_link = sh_link; }
 
@@ -84,7 +84,7 @@ protected:
 
   // Name of the section in convenient string form (instead of a index
   // into the Section Header String Table, which is not known till later).
-  IceString Name;
+  const IceString Name;
 
   // The fields of the header. May only be partially initialized, but should
   // be fully initialized before writing.

src/IceOperand.h

@@ -223,7 +223,7 @@ public:
   }
 
   RelocOffsetT getOffset() const { return Offset; }
-  IceString getName() const { return Name; }
+  const IceString &getName() const { return Name; }
   void setSuppressMangling(bool Value) { SuppressMangling = Value; }
   bool getSuppressMangling() const { return SuppressMangling; }
   using Constant::emit;

src/PNaClTranslator.cpp

@@ -294,7 +294,7 @@ public:
       const auto Var = llvm::cast<Ice::VariableDeclaration>(Decl);
       IsUndefined = !Var->hasInitializer();
     }
-    std::string Name;
+    Ice::IceString Name;
     bool SuppressMangling;
     if (Decl) {
       Name = Decl->getName();
@@ -1508,7 +1508,7 @@ private:
   }
 
   // Returns true if the Str begins with Prefix.
-  bool isStringPrefix(Ice::IceString &Str, Ice::IceString &Prefix) {
+  bool isStringPrefix(const Ice::IceString &Str, const Ice::IceString &Prefix) {
     const size_t PrefixSize = Prefix.size();
     if (Str.size() < PrefixSize)
       return false;
@@ -2446,7 +2446,7 @@ void FunctionParser::ProcessRecord() {
 
       // Check if this direct call is to an Intrinsic (starts with "llvm.")
       static Ice::IceString LLVMPrefix("llvm.");
-      Ice::IceString Name = Fcn->getName();
+      const Ice::IceString &Name = Fcn->getName();
       if (isStringPrefix(Name, LLVMPrefix)) {
         Ice::IceString Suffix = Name.substr(LLVMPrefix.size());
         IntrinsicInfo =