[heap] Use HashMap as scratchpad backing store

src/heap/heap-inl.h

 // Copyright 2012 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.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 489 matching lines @@
          memento_address + HeapObject::kHeaderSize <= top ||
          !NewSpacePage::OnSamePage(memento_address, top - 1));
   if (memento_address == top) return NULL;
 
   AllocationMemento* memento = AllocationMemento::cast(candidate);
   if (!memento->IsValid()) return NULL;
   return memento;
 }
 
 
-void Heap::UpdateAllocationSiteFeedback(HeapObject* object,
-                                        ScratchpadSlotMode mode) {
-  Heap* heap = object->GetHeap();
-  DCHECK(heap->InFromSpace(object));
-
+void Heap::UpdateAllocationSite(HeapObject* object,
+                                HashMap* pretenuring_feedback) {
+  DCHECK(InFromSpace(object));
   if (!FLAG_allocation_site_pretenuring ||
       !AllocationSite::CanTrack(object->map()->instance_type()))
     return;
+  AllocationMemento* memento = FindAllocationMemento(object);
+  if (memento == nullptr) return;
 
-  AllocationMemento* memento = heap->FindAllocationMemento(object);
-  if (memento == NULL) return;
+  AllocationSite* key = memento->GetAllocationSite();
+  DCHECK(!key->IsZombie());
 
-  if (memento->GetAllocationSite()->IncrementMementoFoundCount()) {
-    heap->AddAllocationSiteToScratchpad(memento->GetAllocationSite(), mode);
+  if (pretenuring_feedback == global_pretenuring_feedback_) {
+    // For inserting in the global pretenuring storage we need to first
+    // increment the memento found count on the allocation site.
+    if (key->IncrementMementoFoundCount()) {
+      global_pretenuring_feedback_->LookupOrInsert(
+          key, static_cast<uint32_t>(bit_cast<uintptr_t>(key)));
+    }
+  } else {
+    // Any other pretenuring storage than the global one is used as a cache,
+    // where the count is later on merge in the allocation site.
+    HashMap::Entry* e = pretenuring_feedback->LookupOrInsert(
+        key, static_cast<uint32_t>(bit_cast<uintptr_t>(key)));
+    DCHECK(e != nullptr);
+    (*bit_cast<intptr_t*>(&e->value))++;
   }
 }
 
 
+void Heap::RemoveAllocationSitePretenuringFeedback(AllocationSite* site) {
+  global_pretenuring_feedback_->Remove(
+      site, static_cast<uint32_t>(bit_cast<uintptr_t>(site)));
+}
+
+
 bool Heap::CollectGarbage(AllocationSpace space, const char* gc_reason,
                           const v8::GCCallbackFlags callbackFlags) {
   const char* collector_reason = NULL;
   GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
   return CollectGarbage(collector, gc_reason, collector_reason, callbackFlags);
 }
 
 
 Isolate* Heap::isolate() {
   return reinterpret_cast<Isolate*>(
@@ skipping 163 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_INL_H_