Introduce DisallowDeoptimization scope.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 14565 matching lines @@
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
   if (!object->IsJSObject()) return Smi::FromInt(0);
   Handle<JSObject> js_object = Handle<JSObject>::cast(object);
   if (!js_object->map()->is_deprecated()) return Smi::FromInt(0);
   // This call must not cause lazy deopts, because it's called from deferred
   // code where we can't handle lazy deopts for lack of a suitable bailout
   // ID. So we just try migration and signal failure if necessary,
   // which will also trigger a deopt.
+  DisallowDeoptimization no_deoptimization(isolate);
   if (!JSObject::TryMigrateInstance(js_object)) return Smi::FromInt(0);

[Yang, 2014/04/28 06:38:38]

Isn't JSObject::TryMigrateInstance not supposed to cause deopts altogether? In
that case, moving the disallow scope inside it would be nicer. If not, ignore
this comment.

[Benedikt Meurer, 2014/04/28 06:44:36]

Done.

   return *object;
 }
 
 
 RUNTIME_FUNCTION(RuntimeHidden_GetFromCache) {
   SealHandleScope shs(isolate);
   // This is only called from codegen, so checks might be more lax.
   CONVERT_ARG_CHECKED(JSFunctionResultCache, cache, 0);
   CONVERT_ARG_CHECKED(Object, key, 1);
 
@@ skipping 547 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal