The allocation sites scratchpad becomes a heap data structure.

BUG=
R=mstarzinger@chromium.org, mvstanton@chromium.org

Review URL: https://codereview.chromium.org/143153008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19189 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -5398,7 +5398,7 @@ class Internals {
   static const int kNullValueRootIndex = 7;
   static const int kTrueValueRootIndex = 8;
   static const int kFalseValueRootIndex = 9;
-  static const int kEmptyStringRootIndex = 146;
+  static const int kEmptyStringRootIndex = 147;
 
   static const int kNodeClassIdOffset = 1 * kApiPointerSize;
   static const int kNodeFlagsOffset = 1 * kApiPointerSize + 3;

src/heap-inl.h

@@ -517,12 +517,8 @@ void Heap::UpdateAllocationSiteFeedback(HeapObject* object) {
   AllocationMemento* memento = AllocationMemento::cast(candidate);
   if (!memento->IsValid()) return;
 
-  if (memento->GetAllocationSite()->IncrementMementoFoundCount() &&
-      heap->allocation_sites_scratchpad_length <
-      kAllocationSiteScratchpadSize) {
-    heap->allocation_sites_scratchpad[
-        heap->allocation_sites_scratchpad_length++] =
-        memento->GetAllocationSite();
+  if (memento->GetAllocationSite()->IncrementMementoFoundCount()) {
+    heap->AddAllocationSiteToScratchpad(memento->GetAllocationSite());
   }
 }
 

src/heap.cc

@@ -150,7 +150,7 @@ Heap::Heap()
 #ifdef VERIFY_HEAP
       no_weak_object_verification_scope_depth_(0),
 #endif
-      allocation_sites_scratchpad_length(0),
+      allocation_sites_scratchpad_length_(0),
       promotion_queue_(this),
       configured_(false),
       external_string_table_(this),
@@ -516,16 +516,17 @@ void Heap::ProcessPretenuringFeedback() {
     // If the scratchpad overflowed, we have to iterate over the allocation
     // sites list.
     bool use_scratchpad =
-        allocation_sites_scratchpad_length < kAllocationSiteScratchpadSize;
+        allocation_sites_scratchpad_length_ < kAllocationSiteScratchpadSize;
 
     int i = 0;
     Object* list_element = allocation_sites_list();
     bool trigger_deoptimization = false;
     while (use_scratchpad ?
-              i < allocation_sites_scratchpad_length :
+              i < allocation_sites_scratchpad_length_ :
               list_element->IsAllocationSite()) {
       AllocationSite* site = use_scratchpad ?
-        allocation_sites_scratchpad[i] : AllocationSite::cast(list_element);
+          AllocationSite::cast(allocation_sites_scratchpad()->get(i)) :
+          AllocationSite::cast(list_element);
       allocation_mementos_found += site->memento_found_count();
       if (site->memento_found_count() > 0) {
         active_allocation_sites++;
@@ -546,7 +547,7 @@ void Heap::ProcessPretenuringFeedback() {
 
     if (trigger_deoptimization) isolate_->stack_guard()->DeoptMarkedCode();
 
-    allocation_sites_scratchpad_length = 0;
+    FlushAllocationSitesScratchpad();
 
     if (FLAG_trace_pretenuring_statistics &&
         (allocation_mementos_found > 0 ||
@@ -3300,6 +3301,12 @@ bool Heap::CreateInitialObjects() {
   // Handling of script id generation is in Factory::NewScript.
   set_last_script_id(Smi::FromInt(v8::Script::kNoScriptId));
 
+  { MaybeObject* maybe_obj = AllocateAllocationSitesScratchpad();
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  set_allocation_sites_scratchpad(FixedArray::cast(obj));
+  InitializeAllocationSitesScratchpad();
+
   // Initialize keyed lookup cache.
   isolate_->keyed_lookup_cache()->Clear();
 
@@ -3589,6 +3596,39 @@ MaybeObject* Heap::Uint32ToString(uint32_t value,
 }
 
 
+MaybeObject* Heap::AllocateAllocationSitesScratchpad() {
+  MaybeObject* maybe_obj =
+      AllocateFixedArray(kAllocationSiteScratchpadSize, TENURED);
+  return maybe_obj;
+}
+
+
+void Heap::FlushAllocationSitesScratchpad() {
+  for (int i = 0; i < allocation_sites_scratchpad_length_; i++) {
+    allocation_sites_scratchpad()->set_undefined(i);
+  }
+  allocation_sites_scratchpad_length_ = 0;
+}
+
+
+void Heap::InitializeAllocationSitesScratchpad() {
+  ASSERT(allocation_sites_scratchpad()->length() ==
+         kAllocationSiteScratchpadSize);
+  for (int i = 0; i < kAllocationSiteScratchpadSize; i++) {
+    allocation_sites_scratchpad()->set_undefined(i);
+  }
+}
+
+
+void Heap::AddAllocationSiteToScratchpad(AllocationSite* site) {
+  if (allocation_sites_scratchpad_length_ < kAllocationSiteScratchpadSize) {
+    allocation_sites_scratchpad()->set(
+        allocation_sites_scratchpad_length_, site);
+    allocation_sites_scratchpad_length_++;
+  }
+}
+
+
 Map* Heap::MapForExternalArrayType(ExternalArrayType array_type) {
   return Map::cast(roots_[RootIndexForExternalArrayType(array_type)]);
 }

src/heap.h

@@ -202,7 +202,8 @@ namespace internal {
   V(SeededNumberDictionary, empty_slow_element_dictionary,                     \
       EmptySlowElementDictionary)                                              \
   V(Symbol, observed_symbol, ObservedSymbol)                                   \
-  V(FixedArray, materialized_objects, MaterializedObjects)
+  V(FixedArray, materialized_objects, MaterializedObjects)                     \
+  V(FixedArray, allocation_sites_scratchpad, AllocationSitesScratchpad)
 
 #define ROOT_LIST(V)                                  \
   STRONG_ROOT_LIST(V)                                 \
@@ -2285,6 +2286,18 @@ class Heap {
   // Flush the number to string cache.
   void FlushNumberStringCache();
 
+  // Allocates a fixed-size allocation sites scratchpad.
+  MUST_USE_RESULT MaybeObject* AllocateAllocationSitesScratchpad();
+
+  // Sets used allocation sites entries to undefined.
+  void FlushAllocationSitesScratchpad();
+
+  // Initializes the allocation sites scratchpad with undefined values.
+  void InitializeAllocationSitesScratchpad();
+
+  // Adds an allocation site to the scratchpad if there is space left.
+  void AddAllocationSiteToScratchpad(AllocationSite* site);
+
   void UpdateSurvivalRateTrend(int start_new_space_size);
 
   enum SurvivalRateTrend { INCREASING, STABLE, DECREASING, FLUCTUATING };
@@ -2457,10 +2470,8 @@ class Heap {
   int no_weak_object_verification_scope_depth_;
 #endif
 
-
   static const int kAllocationSiteScratchpadSize = 256;
-  int allocation_sites_scratchpad_length;
-  AllocationSite* allocation_sites_scratchpad[kAllocationSiteScratchpadSize];
+  int allocation_sites_scratchpad_length_;
 
   static const int kMaxMarkSweepsInIdleRound = 7;
   static const int kIdleScavengeThreshold = 5;