Fully implement delegating constructors!

As far as I know, this implementation is complete but might be missing a
few optimizations. Exceptions and virtual bases are handled correctly.

Because I'm an optimist, the web page has appropriately been updated. If
I'm wrong, feel free to downgrade its support categories.

llvm-svn: 130642

3 files changed, 39 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 2cb554902e1..1227b4c1b24 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -658,6 +658,10 @@ static bool IsConstructorDelegationValid(const CXXConstructorDecl *Ctor) {
   if (Ctor->getType()->getAs<FunctionProtoType>()->isVariadic())
     return false;
 
+  // FIXME: Decide if we can do a delegation of a delegating constructor.
+  if (Ctor->isDelegatingConstructor())
+    return false;
+
   return true;
 }
 
@@ -710,6 +714,9 @@ void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
 void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
                                        CXXCtorType CtorType,
                                        FunctionArgList &Args) {
+  if (CD->isDelegatingConstructor())
+    return EmitDelegatingCXXConstructorCall(CD, Args);
+
   const CXXRecordDecl *ClassDecl = CD->getParent();
 
   llvm::SmallVector<CXXCtorInitializer *, 8> MemberInitializers;
@@ -721,8 +728,10 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
     
     if (Member->isBaseInitializer())
       EmitBaseInitializer(*this, ClassDecl, Member, CtorType);
-    else
+    else if (Member->isAnyMemberInitializer())
       MemberInitializers.push_back(Member);
+    else
+      llvm_unreachable("Delegating initializer on non-delegating constructor");
   }
 
   InitializeVTablePointers(ClassDecl);
@@ -1262,6 +1271,19 @@ CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
            ReturnValueSlot(), DelegateArgs, Ctor);
 }
 
+void
+CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
+                                                  const FunctionArgList &Args) {
+  assert(Ctor->isDelegatingConstructor());
+
+  llvm::Value *ThisPtr = LoadCXXThis();
+
+  AggValueSlot AggSlot = AggValueSlot::forAddr(ThisPtr, false, /*Lifetime*/ true);
+
+  EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
+}
+
+
 void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
                                             CXXDtorType Type,
                                             bool ForVirtualBase,
diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 2f3e4680a79..e66afc6290c 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -404,9 +404,16 @@ CodeGenFunction::EmitCXXConstructExpr(const CXXConstructExpr *E,
                                E->arg_begin(), E->arg_end());
   }
   else {
-    CXXCtorType Type = 
-      (E->getConstructionKind() == CXXConstructExpr::CK_Complete) 
-      ? Ctor_Complete : Ctor_Base;
+    CXXCtorType Type;
+    CXXConstructExpr::ConstructionKind K = E->getConstructionKind();
+    if (K == CXXConstructExpr::CK_Delegating) {
+      // We should be emitting a constructor; GlobalDecl will assert this
+      Type = CurGD.getCtorType();
+    } else {
+      Type = (E->getConstructionKind() == CXXConstructExpr::CK_Complete)
+             ? Ctor_Complete : Ctor_Base;
+    }
+
     bool ForVirtualBase = 
       E->getConstructionKind() == CXXConstructExpr::CK_VirtualBase;
     
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 913b5dfa7d5..169c576f1a0 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1496,6 +1496,12 @@ public:
   void EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
                                       CXXCtorType CtorType,
                                       const FunctionArgList &Args);
+  // It's important not to confuse this and the previous function. Delegating
+  // constructors are the C++0x feature. The constructor delegate optimization
+  // is used to reduce duplication in the base and complete consturctors where
+  // they are substantially the same.
+  void EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
+                                        const FunctionArgList &Args);
   void EmitCXXConstructorCall(const CXXConstructorDecl *D, CXXCtorType Type,
                               bool ForVirtualBase, llvm::Value *This,
                               CallExpr::const_arg_iterator ArgBeg,