Add 64-bit stubs to call into the runtime and to call native functions.

runtime/vm/runtime_entry_x64.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/runtime_entry.h"
 
+#include "vm/assembler.h"
+#include "vm/stub_code.h"
+
 namespace dart {
 
+#define __ assembler->
+
+
+// Generate code to call into the stub which will call the runtime
+// function. Input for the stub is as follows:
+//   RSP : points to the arguments and return value array.
+//   RBX : address of the runtime function to call.
+//   R10 : number of arguments to the call.
 void RuntimeEntry::CallFromDart(Assembler* assembler) const {
-  UNIMPLEMENTED();
+  __ movq(RBX, Immediate(GetEntryPoint()));
+  __ movq(R10, Immediate(argument_count()));
+  __ call(&StubCode::DartCallToRuntimeLabel());
 }
 
+
+// Generate code to call into the stub which will call the runtime
+// function. Input for the stub is as follows:
+//   RSP : points to the arguments and return value array.
+//   RBX : address of the runtime function to call.
+//   R10 : number of arguments to the call.
 void RuntimeEntry::CallFromStub(Assembler* assembler) const {
-  UNIMPLEMENTED();
+  __ movq(RBX, Immediate(GetEntryPoint()));
+  __ movq(R10, Immediate(argument_count()));
+  __ call(&StubCode::StubCallToRuntimeLabel());
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64