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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130642 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 1 deletions

diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index 2cb554902e..1227b4c1b2 100644
--- a/lib/CodeGen/CGClass.cpp
+++ b/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,