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

src/compiler/interpreter-assembler.h

Index: src/compiler/interpreter-assembler.h
diff --git a/src/compiler/interpreter-assembler.h b/src/compiler/interpreter-assembler.h
index b5e93e7ef6b131976d642e8fa70cb6555fa16986..83dfc3d8c1c628084d81e2e874f57cd14b10dbf2 100644
--- a/src/compiler/interpreter-assembler.h
+++ b/src/compiler/interpreter-assembler.h
@@ -67,6 +67,9 @@ class InterpreterAssembler {
   Node* StoreRegister(Node* value, interpreter::Register reg);
   Node* StoreRegister(Node* value, Node* reg_index);
 
+  // Returns the next consecutive register.
+  Node* NextRegister(Node* reg_index);
+
   // Returns the location in memory of the register |reg_index| in the
   // interpreter register file.
   Node* RegisterLocation(Node* reg_index);
@@ -130,7 +133,10 @@ class InterpreterAssembler {
                Node* arg2, Node* arg3, Node* arg4, Node* arg5);
 
   // Call runtime function.
+  Node* CallRuntime(CallDescriptor* descriptor, Handle<Code> call_stub,
+                    Node* function_id, Node* first_arg, Node* arg_count);
   Node* CallRuntime(Node* function_id, Node* first_arg, Node* arg_count);

[Michael Starzinger, 2016/01/07 17:21:28]

suggestion: Likewise to code-factory, can we pass "result_size" as an additional
argument? Again, less code duplication.

[rmcilroy, 2016/01/08 14:15:07]

Done.

+  Node* CallRuntimePair(Node* function_id, Node* first_arg, Node* arg_count);
   Node* CallRuntime(Runtime::FunctionId function_id, Node* arg1);
   Node* CallRuntime(Runtime::FunctionId function_id, Node* arg1, Node* arg2);
   Node* CallRuntime(Runtime::FunctionId function_id, Node* arg1, Node* arg2,