Add --noclever-optimizations to disable some things that have

caused trouble in the past.
Review URL: http://codereview.chromium.org/8229005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9579 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

@@ -4500,6 +4500,7 @@ bool v8::String::MakeExternal(
 
 
 bool v8::String::CanMakeExternal() {
+  if (!internal::FLAG_clever_optimizations) return false;
   i::Handle<i::String> obj = Utils::OpenHandle(this);
   i::Isolate* isolate = obj->GetIsolate();
   if (IsDeadCheck(isolate, "v8::String::CanMakeExternal()")) return false;

src/builtins.cc

@@ -435,6 +435,7 @@ static inline MaybeObject* EnsureJSArrayWithWritableFastElements(
 
 static inline bool IsJSArrayFastElementMovingAllowed(Heap* heap,
                                                      JSArray* receiver) {
+  if (!FLAG_clever_optimizations) return false;
   Context* global_context = heap->isolate()->context()->global_context();
   JSObject* array_proto =
       JSObject::cast(global_context->array_function()->prototype());

src/flag-definitions.h

@@ -107,6 +107,10 @@ DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(smi_only_arrays, false, "tracks arrays with only smi values")
 DEFINE_bool(string_slices, false, "use string slices")
 
+DEFINE_bool(clever_optimizations,
+            true,
+            "Optimize object size, Array shift, DOM strings and string +")
+
 // Flags for Crankshaft.
 #ifdef V8_TARGET_ARCH_MIPS
   DEFINE_bool(crankshaft, false, "use crankshaft")

src/handles.cc

@@ -190,7 +190,11 @@ static int ExpectedNofPropertiesFromEstimate(int estimate) {
 
   // Inobject slack tracking will reclaim redundant inobject space later,
   // so we can afford to adjust the estimate generously.
-  return estimate + 8;
+  if (FLAG_clever_optimizations) {
+    return estimate + 8;
+  } else {
+    return estimate + 3;
+  }
 }
 
 

src/mark-compact.cc

@@ -716,6 +716,7 @@ static inline HeapObject* ShortCircuitConsString(Object** p) {
   // except the maps for the object and its possible substrings might be
   // marked.
   HeapObject* object = HeapObject::cast(*p);
+  if (!FLAG_clever_optimizations) return object;
   Map* map = object->map();
   InstanceType type = map->instance_type();
   if ((type & kShortcutTypeMask) != kShortcutTypeTag) return object;

src/objects.cc

@@ -7242,6 +7242,8 @@ bool SharedFunctionInfo::VerifyBailoutId(int id) {
 void SharedFunctionInfo::StartInobjectSlackTracking(Map* map) {
   ASSERT(!IsInobjectSlackTrackingInProgress());
 
+  if (!FLAG_clever_optimizations) return;
+
   // Only initiate the tracking the first time.
   if (live_objects_may_exist()) return;
   set_live_objects_may_exist(true);