AST: Mangle reference temporaries reliably

Summary:
Previously, we would generate a single name for all reference
temporaries and allow LLVM to rename them for us.  Instead, number the
reference temporaries as we build them in Sema.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D3554

llvm-svn: 207776

1 files changed, 54 insertions, 50 deletions

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 2cf55985811..68f0cc38301 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -5311,25 +5311,25 @@ InitializedEntityOutlivesFullExpression(const InitializedEntity &Entity) {
 /// Determine the declaration which an initialized entity ultimately refers to,
 /// for the purpose of lifetime-extending a temporary bound to a reference in
 /// the initialization of \p Entity.
-static const ValueDecl *
-getDeclForTemporaryLifetimeExtension(const InitializedEntity &Entity,
-                                     const ValueDecl *FallbackDecl = 0) {
+static const InitializedEntity *getEntityForTemporaryLifetimeExtension(
+    const InitializedEntity *Entity,
+    const InitializedEntity *FallbackDecl = 0) {
   // C++11 [class.temporary]p5:
-  switch (Entity.getKind()) {
+  switch (Entity->getKind()) {
   case InitializedEntity::EK_Variable:
     //   The temporary [...] persists for the lifetime of the reference
-    return Entity.getDecl();
+    return Entity;
 
   case InitializedEntity::EK_Member:
     // For subobjects, we look at the complete object.
-    if (Entity.getParent())
-      return getDeclForTemporaryLifetimeExtension(*Entity.getParent(),
-                                                  Entity.getDecl());
+    if (Entity->getParent())
+      return getEntityForTemporaryLifetimeExtension(Entity->getParent(),
+                                                    Entity);
 
     //   except:
     //   -- A temporary bound to a reference member in a constructor's
     //      ctor-initializer persists until the constructor exits.
-    return Entity.getDecl();
+    return Entity;
 
   case InitializedEntity::EK_Parameter:
   case InitializedEntity::EK_Parameter_CF_Audited:
@@ -5344,7 +5344,7 @@ getDeclForTemporaryLifetimeExtension(const InitializedEntity &Entity,
     //   -- A temporary bound to a reference in a new-initializer persists
     //      until the completion of the full-expression containing the
     //      new-initializer.
-    return 0;
+    return nullptr;
 
   case InitializedEntity::EK_Temporary:
   case InitializedEntity::EK_CompoundLiteralInit:
@@ -5352,12 +5352,12 @@ getDeclForTemporaryLifetimeExtension(const InitializedEntity &Entity,
     // We don't yet know the storage duration of the surrounding temporary.
     // Assume it's got full-expression duration for now, it will patch up our
     // storage duration if that's not correct.
-    return 0;
+    return nullptr;
 
   case InitializedEntity::EK_ArrayElement:
     // For subobjects, we look at the complete object.
-    return getDeclForTemporaryLifetimeExtension(*Entity.getParent(),
-                                                FallbackDecl);
+    return getEntityForTemporaryLifetimeExtension(Entity->getParent(),
+                                                  FallbackDecl);
 
   case InitializedEntity::EK_Base:
   case InitializedEntity::EK_Delegating:
@@ -5372,17 +5372,20 @@ getDeclForTemporaryLifetimeExtension(const InitializedEntity &Entity,
   case InitializedEntity::EK_Exception:
   case InitializedEntity::EK_VectorElement:
   case InitializedEntity::EK_ComplexElement:
-    return 0;
+    return nullptr;
   }
   llvm_unreachable("unknown entity kind");
 }
 
-static void performLifetimeExtension(Expr *Init, const ValueDecl *ExtendingD);
+static void performLifetimeExtension(Expr *Init,
+                                     const InitializedEntity *ExtendingEntity);
 
 /// Update a glvalue expression that is used as the initializer of a reference
 /// to note that its lifetime is extended.
 /// \return \c true if any temporary had its lifetime extended.
-static bool performReferenceExtension(Expr *Init, const ValueDecl *ExtendingD) {
+static bool
+performReferenceExtension(Expr *Init,
+                          const InitializedEntity *ExtendingEntity) {
   if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
     if (ILE->getNumInits() == 1 && ILE->isGLValue()) {
       // This is just redundant braces around an initializer. Step over it.
@@ -5416,8 +5419,9 @@ static bool performReferenceExtension(Expr *Init, const ValueDecl *ExtendingD) {
   if (MaterializeTemporaryExpr *ME = dyn_cast<MaterializeTemporaryExpr>(Init)) {
     // Update the storage duration of the materialized temporary.
     // FIXME: Rebuild the expression instead of mutating it.
-    ME->setExtendingDecl(ExtendingD);
-    performLifetimeExtension(ME->GetTemporaryExpr(), ExtendingD);
+    ME->setExtendingDecl(ExtendingEntity->getDecl(),
+                         ExtendingEntity->allocateManglingNumber());
+    performLifetimeExtension(ME->GetTemporaryExpr(), ExtendingEntity);
     return true;
   }
 
@@ -5426,7 +5430,8 @@ static bool performReferenceExtension(Expr *Init, const ValueDecl *ExtendingD) {
 
 /// Update a prvalue expression that is going to be materialized as a
 /// lifetime-extended temporary.
-static void performLifetimeExtension(Expr *Init, const ValueDecl *ExtendingD) {
+static void performLifetimeExtension(Expr *Init,
+                                     const InitializedEntity *ExtendingEntity) {
   // Dig out the expression which constructs the extended temporary.
   SmallVector<const Expr *, 2> CommaLHSs;
   SmallVector<SubobjectAdjustment, 2> Adjustments;
@@ -5438,14 +5443,14 @@ static void performLifetimeExtension(Expr *Init, const ValueDecl *ExtendingD) {
 
   if (CXXStdInitializerListExpr *ILE =
           dyn_cast<CXXStdInitializerListExpr>(Init)) {
-    performReferenceExtension(ILE->getSubExpr(), ExtendingD);
+    performReferenceExtension(ILE->getSubExpr(), ExtendingEntity);
     return;
   }
 
   if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
     if (ILE->getType()->isArrayType()) {
       for (unsigned I = 0, N = ILE->getNumInits(); I != N; ++I)
-        performLifetimeExtension(ILE->getInit(I), ExtendingD);
+        performLifetimeExtension(ILE->getInit(I), ExtendingEntity);
       return;
     }
 
@@ -5457,7 +5462,7 @@ static void performLifetimeExtension(Expr *Init, const ValueDecl *ExtendingD) {
       // bound to temporaries, those temporaries are also lifetime-extended.
       if (RD->isUnion() && ILE->getInitializedFieldInUnion() &&
           ILE->getInitializedFieldInUnion()->getType()->isReferenceType())
-        performReferenceExtension(ILE->getInit(0), ExtendingD);
+        performReferenceExtension(ILE->getInit(0), ExtendingEntity);
       else {
         unsigned Index = 0;
         for (const auto *I : RD->fields()) {
@@ -5467,13 +5472,13 @@ static void performLifetimeExtension(Expr *Init, const ValueDecl *ExtendingD) {
             continue;
           Expr *SubInit = ILE->getInit(Index);
           if (I->getType()->isReferenceType())
-            performReferenceExtension(SubInit, ExtendingD);
+            performReferenceExtension(SubInit, ExtendingEntity);
           else if (isa<InitListExpr>(SubInit) ||
                    isa<CXXStdInitializerListExpr>(SubInit))
             // This may be either aggregate-initialization of a member or
             // initialization of a std::initializer_list object. Either way,
             // we should recursively lifetime-extend that initializer.
-            performLifetimeExtension(SubInit, ExtendingD);
+            performLifetimeExtension(SubInit, ExtendingEntity);
           ++Index;
         }
       }
@@ -5759,12 +5764,12 @@ InitializationSequence::Perform(Sema &S,
       // Even though we didn't materialize a temporary, the binding may still
       // extend the lifetime of a temporary. This happens if we bind a reference
       // to the result of a cast to reference type.
-      if (const ValueDecl *ExtendingDecl =
-              getDeclForTemporaryLifetimeExtension(Entity)) {
-        if (performReferenceExtension(CurInit.get(), ExtendingDecl))
-          warnOnLifetimeExtension(S, Entity, CurInit.get(), false,
-                                  ExtendingDecl);
-      }
+      if (const InitializedEntity *ExtendingEntity =
+              getEntityForTemporaryLifetimeExtension(&Entity))
+        if (performReferenceExtension(CurInit.get(), ExtendingEntity))
+          warnOnLifetimeExtension(S, Entity, CurInit.get(),
+                                  /*IsInitializerList=*/false,
+                                  ExtendingEntity->getDecl());
 
       break;
 
@@ -5776,19 +5781,18 @@ InitializationSequence::Perform(Sema &S,
       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
         return ExprError();
 
-      // Maybe lifetime-extend the temporary's subobjects to match the
-      // entity's lifetime.
-      const ValueDecl *ExtendingDecl =
-          getDeclForTemporaryLifetimeExtension(Entity);
-      if (ExtendingDecl) {
-        performLifetimeExtension(CurInit.get(), ExtendingDecl);
-        warnOnLifetimeExtension(S, Entity, CurInit.get(), false, ExtendingDecl);
-      }
-
       // Materialize the temporary into memory.
       MaterializeTemporaryExpr *MTE = new (S.Context) MaterializeTemporaryExpr(
           Entity.getType().getNonReferenceType(), CurInit.get(),
-          Entity.getType()->isLValueReferenceType(), ExtendingDecl);
+          Entity.getType()->isLValueReferenceType());
+
+      // Maybe lifetime-extend the temporary's subobjects to match the
+      // entity's lifetime.
+      if (const InitializedEntity *ExtendingEntity =
+              getEntityForTemporaryLifetimeExtension(&Entity))
+        if (performReferenceExtension(MTE, ExtendingEntity))
+          warnOnLifetimeExtension(S, Entity, CurInit.get(), /*IsInitializerList=*/false,
+                                  ExtendingEntity->getDecl());
 
       // If we're binding to an Objective-C object that has lifetime, we
       // need cleanups. Likewise if we're extending this temporary to automatic
@@ -6176,19 +6180,19 @@ InitializationSequence::Perform(Sema &S,
              diag::warn_cxx98_compat_initializer_list_init)
         << CurInit.get()->getSourceRange();
 
-      // Maybe lifetime-extend the array temporary's subobjects to match the
-      // entity's lifetime.
-      const ValueDecl *ExtendingDecl =
-          getDeclForTemporaryLifetimeExtension(Entity);
-      if (ExtendingDecl) {
-        performLifetimeExtension(CurInit.get(), ExtendingDecl);
-        warnOnLifetimeExtension(S, Entity, CurInit.get(), true, ExtendingDecl);
-      }
-
       // Materialize the temporary into memory.
       MaterializeTemporaryExpr *MTE = new (S.Context)
           MaterializeTemporaryExpr(CurInit.get()->getType(), CurInit.get(),
-                                   /*lvalue reference*/ false, ExtendingDecl);
+                                   /*BoundToLvalueReference=*/false);
+
+      // Maybe lifetime-extend the array temporary's subobjects to match the
+      // entity's lifetime.
+      if (const InitializedEntity *ExtendingEntity =
+              getEntityForTemporaryLifetimeExtension(&Entity))
+        if (performReferenceExtension(MTE, ExtendingEntity))
+          warnOnLifetimeExtension(S, Entity, CurInit.get(),
+                                  /*IsInitializerList=*/true,
+                                  ExtendingEntity->getDecl());
 
       // Wrap it in a construction of a std::initializer_list<T>.
       CurInit = S.Owned(