[Interpreter] Ensure that implicit return undefined is generated.

src/interpreter/bytecode-array-builder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
@@ skipping 19 matching lines @@
 
 
 void BytecodeArrayBuilder::set_parameter_count(int number_of_parameters) {
   parameter_count_ = number_of_parameters;
 }
 
 
 int BytecodeArrayBuilder::parameter_count() const { return parameter_count_; }
 
 
+bool BytecodeArrayBuilder::HasExplicitReturn() {
+  // TODO(rmcilroy): When we have control flow we should return false here if
+  // there is an outstanding jump target, even if the last bytecode is kReturn.
+  return !bytecodes_.empty() &&
+         bytecodes_.back() == Bytecodes::ToByte(Bytecode::kReturn);
+}
+
+
 Register BytecodeArrayBuilder::Parameter(int parameter_index) {
   DCHECK_GE(parameter_index, 0);
   DCHECK_LT(parameter_index, parameter_count_);
   return Register::FromParameterIndex(parameter_index, parameter_count_);
 }
 
 
 Handle<BytecodeArray> BytecodeArrayBuilder::ToBytecodeArray() {
   DCHECK_EQ(bytecode_generated_, false);
   DCHECK_GE(parameter_count_, 0);
@@ skipping 276 matching lines @@
 
 Register TemporaryRegisterScope::NewRegister() {
   count_++;
   last_register_index_ = builder_->BorrowTemporaryRegister();
   return Register(last_register_index_);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8