[Interpreter] Add support for calling runtime functions which return a pair.

src/interpreter/bytecode-generator.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-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
 #include "src/objects.h"
@@ skipping 1666 matching lines @@
     receiver = execution_result()->NextConsecutiveRegister();
     builder()->LoadUndefined().StoreAccumulatorInRegister(receiver);
   }
   // Evaluate all arguments to the runtime call.
   Register first_arg = VisitArguments(args);
 
   if (expr->is_jsruntime()) {
     DCHECK(args->length() == 0 || first_arg.index() == receiver.index() + 1);
     builder()->CallJSRuntime(expr->context_index(), receiver, args->length());
   } else {
-    // TODO(rmcilroy): support multiple return values.
-    DCHECK_LE(expr->function()->result_size, 1);
     Runtime::FunctionId function_id = expr->function()->function_id;
     builder()->CallRuntime(function_id, first_arg, args->length());
   }
   execution_result()->SetResultInAccumulator();
 }
 
 
 void BytecodeGenerator::VisitVoid(UnaryOperation* expr) {
   VisitForEffect(expr->expression());
   builder()->LoadUndefined();
@@ skipping 518 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8