implement support for struct and complex returns.

llvm-svn: 39674

clang/CodeGen/CGStmt.cpp

@@ -266,10 +266,10 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
     RetVal = EmitConversion(RetVal, RV->getType(), FnRetTy);
     
     if (RetVal.isScalar()) {
-      // FIXME: Pass return loc in!
       Builder.CreateRet(RetVal.getVal());
     } else {
-      assert(0 && "FIXME: aggregate return unimp");
+      llvm::Value *SRetPtr = CurFn->arg_begin();
+      EmitStoreThroughLValue(RetVal, LValue::getAddr(SRetPtr), FnRetTy);
     }
   }
   

clang/CodeGen/CodeGenFunction.cpp

@@ -43,6 +43,11 @@ const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
   return CGM.getTypes().ConvertType(T);
 }
 
+bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
+  return !T->isRealType() && !T->isPointerType();
+}
+
+
 void CodeGenFunction::GenerateCode(const FunctionDecl *FD) {
   LLVMIntTy = ConvertType(getContext().IntTy);
   LLVMPointerWidth = Target.getPointerWidth(SourceLocation());
@@ -62,8 +67,15 @@ void CodeGenFunction::GenerateCode(const FunctionDecl *FD) {
   llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty);
   AllocaInsertPt = Builder.CreateBitCast(Undef,llvm::Type::Int32Ty, "allocapt");
   
-  // Emit allocs for param decls. 
+  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
   llvm::Function::arg_iterator AI = CurFn->arg_begin();
+  
+  // Name the struct return argument.
+  if (hasAggregateLLVMType(FD->getResultType())) {
+    AI->setName("agg.result");
+    ++AI;
+  }
+  
   for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i, ++AI) {
     assert(AI != CurFn->arg_end() && "Argument mismatch!");
     EmitParmDecl(*FD->getParamDecl(i), AI);

clang/CodeGen/CodeGenFunction.h

@@ -153,6 +153,10 @@ public:
   
   const llvm::Type *ConvertType(QualType T);
   
+  /// hasAggregateLLVMType - Return true if the specified AST type will map into
+  /// an aggregate LLVM type or is void.
+  static bool hasAggregateLLVMType(QualType T);
+  
   /// getBasicBlockForLabel - Return the LLVM basicblock that the specified
   /// label maps to.
   llvm::BasicBlock *getBasicBlockForLabel(const LabelStmt *S);

clang/CodeGen/CodeGenTypes.cpp

@@ -108,6 +108,13 @@ const llvm::Type *CodeGenTypes::ConvertType(QualType T) {
     // FIXME: Convert argument types.
     bool isVarArg;
     std::vector<const llvm::Type*> ArgTys;
+    
+    // Struct return passes the struct byref.
+    if (!ResultType->isFirstClassType()) {
+      ArgTys.push_back(llvm::PointerType::get(ResultType));
+      ResultType = llvm::Type::VoidTy;
+    }
+    
     if (const FunctionTypeProto *FTP = dyn_cast<FunctionTypeProto>(&FP)) {
       DecodeArgumentTypes(*FTP, ArgTys);
       isVarArg = FTP->isVariadic();