Added %_Likely/%_Unlikely intrinsics (special cases of GCC's __builin_expect).

src/runtime/runtime-internal.cc

 // Copyright 2014 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/v8.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/messages.h"
@@ skipping 312 matching lines @@
 RUNTIME_FUNCTION(Runtime_IncrementStatsCounter) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(String, name, 0);
 
   if (FLAG_native_code_counters) {
     StatsCounter(isolate, name->ToCString().get()).Increment();
   }
   return isolate->heap()->undefined_value();
 }
+
+
+RUNTIME_FUNCTION(Runtime_Likely) {
+  DCHECK(args.length() == 1);
+  return args[0];
+}
+
+
+RUNTIME_FUNCTION(Runtime_Unlikely) {
+  DCHECK(args.length() == 1);
+  return args[0];
+}
 }
 }  // namespace v8::internal