[BOLT] Use NameResolver class for local symbols

Summary: NameResolver class is used to assign unique names to local symbols.

(cherry picked from FBD18277131)

bolt/src/BinaryContext.h

@@ -173,25 +173,11 @@ class BinaryContext {
   /// with size won't overflow
   uint32_t DuplicatedJumpTables{0x10000000};
 
-  /// Map used for disambiguation of local symbols.
-  StringMap<uint64_t> LocalSymbols;
-
 public:
   /// [name] -> [BinaryData*] map used for global symbol resolution.
   using SymbolMapType = StringMap<BinaryData *>;
   SymbolMapType GlobalSymbols;
 
-  /// Return unique version of a symbol name in the form "<name>/<number>".
-  std::string uniquifySymbolName(const std::string &Name) {
-    const auto ID = ++LocalSymbols[Name];
-    return Name + '/' + std::to_string(ID);
-  }
-
-  /// Release memory used for disambiguation of local symbols.
-  void freeLocalSymbols() {
-    clearList(LocalSymbols);
-  }
-
   /// [address] -> [BinaryData], ...
   /// Addresses never change.
   /// Note: it is important that clients do not hold on to instances of

bolt/src/RewriteInstance.cpp

@@ -1093,11 +1093,13 @@ void RewriteInstance::run() {
 void RewriteInstance::discoverFileObjects() {
   NamedRegionTimer T("discoverFileObjects", "discover file objects",
                      TimerGroupName, TimerGroupDesc, opts::TimeRewrite);
+  NameResolver NR;
 
   FileSymRefs.clear();
   BC->getBinaryFunctions().clear();
   BC->clearBinaryData();
 
+
   // For local symbols we want to keep track of associated FILE symbol name for
   // disambiguation by combined name.
   StringRef  FileSymbolName;
@@ -1291,9 +1293,9 @@ void RewriteInstance::discoverFileObjects() {
         AltPrefix = Name + "/" + std::string(SFI->second);
       }
 
-      UniqueName = BC->uniquifySymbolName(Name);
+      UniqueName = NR.uniquifySymbolName(Name);
       if (!AltPrefix.empty())
-        AlternativeName = BC->uniquifySymbolName(AltPrefix);
+        AlternativeName = NR.uniquifySymbolName(AltPrefix);
     }
 
     uint64_t SymbolSize = ELFSymbolRef(Symbol).getSize();
@@ -1558,9 +1560,7 @@ void RewriteInstance::discoverFileObjects() {
                    });
 
   for (const auto &Section : RelocationSections)
-    readRelocations(Section);
-
-  BC->freeLocalSymbols();
+    readRelocations(Section, NR);
 }
 
 void RewriteInstance::disassemblePLT() {
@@ -2120,7 +2120,8 @@ bool RewriteInstance::analyzeRelocation(const RelocationRef &Rel,
   return true;
 }
 
-void RewriteInstance::readRelocations(const SectionRef &Section) {
+void RewriteInstance::readRelocations(const SectionRef &Section,
+                                      NameResolver &NR) {
   StringRef SectionName;
   Section.getName(SectionName);
   DEBUG(dbgs() << "BOLT-DEBUG: reading relocations for section "
@@ -2519,9 +2520,9 @@ void RewriteInstance::readRelocations(const SectionRef &Section) {
           } else {
             if (StringRef(SymbolName).startswith(
                   BC->AsmInfo->getPrivateGlobalPrefix())) {
-              Name = BC->uniquifySymbolName("PG" + SymbolName);
+              Name = NR.uniquifySymbolName("PG" + SymbolName);
             } else {
-              Name = BC->uniquifySymbolName(SymbolName);
+              Name = NR.uniquifySymbolName(SymbolName);
             }
           }
           ReferencedSymbol = BC->registerNameAtAddress(Name,

bolt/src/RewriteInstance.h

@@ -45,6 +45,21 @@ class RewriteInstanceDiff;
 /// optimizations) and rewriting. It also has the logic to coordinate such
 /// events.
 class RewriteInstance {
+private:
+  /// Class used for assigning unique names to local symbols.
+  class NameResolver {
+  private:
+    /// Track the number of duplicate names.
+    StringMap<uint64_t> LocalSymbols;
+
+  public:
+    /// Return unique version of a symbol name in the form "<name>/<number>".
+    std::string uniquifySymbolName(const std::string &Name) {
+      const auto ID = ++LocalSymbols[Name];
+      return Name + '/' + std::to_string(ID);
+    }
+  };
+
 public:
   RewriteInstance(llvm::object::ELFObjectFileBase *File, DataReader &DR,
                   DataAggregator &DA, const int Argc, const char *const *Argv,
@@ -70,7 +85,7 @@ public:
   void adjustCommandLineOptions();
 
   /// Read relocations from a given section.
-  void readRelocations(const object::SectionRef &Section);
+  void readRelocations(const object::SectionRef &Section, NameResolver &NR);
 
   /// Read information from debug sections.
   void readDebugInfo();