[PATCH] Simplify microsoft mangling of template instantiations

[Agustín Bergé]

Use mangled template instantiation name as key for back references. Templates have their own context for back references, so their mangling is always the same regardless of context. This avoids mangling template instantiations twice.

http://reviews.llvm.org/D3983

Files:
  lib/AST/MicrosoftMangle.cpp

Index: lib/AST/MicrosoftMangle.cpp
===================================================================
--- lib/AST/MicrosoftMangle.cpp
+++ lib/AST/MicrosoftMangle.cpp
@@ -193,7 +193,6 @@
 
   typedef llvm::StringMap<unsigned> BackRefMap;
   BackRefMap NameBackReferences;
-  bool UseNameBackReferences;
 
   typedef llvm::DenseMap<void *, unsigned> ArgBackRefMap;
   ArgBackRefMap TypeBackReferences;
@@ -209,14 +208,12 @@
 
   MicrosoftCXXNameMangler(MicrosoftMangleContextImpl &C, raw_ostream &Out_)
       : Context(C), Out(Out_), Structor(nullptr), StructorType(-1),
-        UseNameBackReferences(true),
         PointersAre64Bit(C.getASTContext().getTargetInfo().getPointerWidth(0) ==
                          64) {}
 
   MicrosoftCXXNameMangler(MicrosoftMangleContextImpl &C, raw_ostream &Out_,
                           const CXXDestructorDecl *D, CXXDtorType Type)
       : Context(C), Out(Out_), Structor(getStructor(D)), StructorType(Type),
-        UseNameBackReferences(true),
         PointersAre64Bit(C.getASTContext().getTargetInfo().getPointerWidth(0) ==
                          64) {}
 
@@ -241,7 +238,6 @@
   void mangleNestedName(const NamedDecl *ND);
 
 private:
-  void disableBackReferences() { UseNameBackReferences = false; }
   void mangleUnqualifiedName(const NamedDecl *ND) {
     mangleUnqualifiedName(ND, ND->getDeclName());
   }
@@ -667,24 +663,20 @@
     //   type [ -> template-parameters]
     //      \-> namespace[s]
     // What we do is we create a new mangler, mangle the same type (without
-    // a namespace suffix) using the extra mangler with back references
-    // disabled (to avoid infinite recursion) and then use the mangled type
-    // name as a key to check the mangling of different types for aliasing.
+    // a namespace suffix) to a string using the extra mangler and then use 
+    // the mangled type name as a key to check the mangling of different types
+    // for aliasing.
 
     std::string BackReferenceKey;
-    BackRefMap::iterator Found;
-    if (UseNameBackReferences) {
-      llvm::raw_string_ostream Stream(BackReferenceKey);
-      MicrosoftCXXNameMangler Extra(Context, Stream);
-      Extra.disableBackReferences();
-      Extra.mangleUnqualifiedName(ND, Name);
-      Stream.flush();
-
-      Found = NameBackReferences.find(BackReferenceKey);
-    }
-    if (!UseNameBackReferences || Found == NameBackReferences.end()) {
-      mangleTemplateInstantiationName(TD, *TemplateArgs);
-      if (UseNameBackReferences && NameBackReferences.size() < 10) {
+    llvm::raw_string_ostream Stream(BackReferenceKey);
+    MicrosoftCXXNameMangler Extra(Context, Stream);
+    Extra.mangleTemplateInstantiationName(TD, *TemplateArgs);
+    Stream.flush();
+
+    BackRefMap::iterator Found = NameBackReferences.find(BackReferenceKey);
+    if (Found == NameBackReferences.end()) {
+      Out << BackReferenceKey;
+      if (NameBackReferences.size() < 10) {
         size_t Size = NameBackReferences.size();
         NameBackReferences[BackReferenceKey] = Size;
       }
@@ -1012,12 +1004,10 @@
 
 void MicrosoftCXXNameMangler::mangleSourceName(StringRef Name) {
   // <source name> ::= <identifier> @
-  BackRefMap::iterator Found;
-  if (UseNameBackReferences)
-    Found = NameBackReferences.find(Name);
-  if (!UseNameBackReferences || Found == NameBackReferences.end()) {
+  BackRefMap::iterator Found = NameBackReferences.find(Name);
+  if (Found == NameBackReferences.end()) {
     Out << Name << '@';
-    if (UseNameBackReferences && NameBackReferences.size() < 10) {
+    if (NameBackReferences.size() < 10) {
       size_t Size = NameBackReferences.size();
       NameBackReferences[Name] = Size;
     }
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