From bafb105aa4c754679262cee323295d7b30462d22 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Sun, 8 Jun 2014 04:51:13 +0000
Subject: [PATCH] MS ABI: Simplify microsoft mangling of template
 instantiations
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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.

Patch by Agustín Bergé!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210416 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/MicrosoftMangle.cpp | 46 +++++++++++++++----------------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp
index 2cc1e5f46c..22d4f343a1 100644
--- a/lib/AST/MicrosoftMangle.cpp
+++ b/lib/AST/MicrosoftMangle.cpp
@@ -193,7 +193,6 @@ class MicrosoftCXXNameMangler {
 
   typedef llvm::StringMap<unsigned> BackRefMap;
   BackRefMap NameBackReferences;
-  bool UseNameBackReferences;
 
   typedef llvm::DenseMap<void *, unsigned> ArgBackRefMap;
   ArgBackRefMap TypeBackReferences;
@@ -209,14 +208,12 @@ public:
 
   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 @@ public:
   void mangleNestedName(const NamedDecl *ND);
 
 private:
-  void disableBackReferences() { UseNameBackReferences = false; }
   void mangleUnqualifiedName(const NamedDecl *ND) {
     mangleUnqualifiedName(ND, ND->getDeclName());
   }
@@ -667,26 +663,22 @@ void MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
     //   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.
-
-    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) {
+    // 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 TemplateMangling;
+    llvm::raw_string_ostream Stream(TemplateMangling);
+    MicrosoftCXXNameMangler Extra(Context, Stream);
+    Extra.mangleTemplateInstantiationName(TD, *TemplateArgs);
+    Stream.flush();
+
+    BackRefMap::iterator Found = NameBackReferences.find(TemplateMangling);
+    if (Found == NameBackReferences.end()) {
+      Out << TemplateMangling;
+      if (NameBackReferences.size() < 10) {
         size_t Size = NameBackReferences.size();
-        NameBackReferences[BackReferenceKey] = Size;
+        NameBackReferences[TemplateMangling] = Size;
       }
     } else {
       Out << Found->second;
@@ -1009,12 +1001,10 @@ void MicrosoftCXXNameMangler::mangleOperatorName(OverloadedOperatorKind OO,
 
 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;
     }
-- 
2.40.0