- Changed the initial size for HashTable....

src/objects.cc

 // Copyright 2006-2009 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 6886 matching lines @@
 
 template<typename Shape, typename Key>
 void HashTable<Shape, Key>::IterateElements(ObjectVisitor* v) {
   IteratePointers(v,
                   kElementsStartOffset,
                   kHeaderSize + length() * kPointerSize);
 }
 
 
 template<typename Shape, typename Key>
-Object* HashTable<Shape, Key>::Allocate(int at_least_space_for) {
-  int capacity = RoundUpToPowerOf2(at_least_space_for);
-  if (capacity < 4) {
-    capacity = 4;  // Guarantee min capacity.
+Object* HashTable<Shape, Key>::Allocate(int at_least_space_for,
+                                        PretenureFlag pretenure) {
+  int capacity = RoundUpToPowerOf2(at_least_space_for * 2);
+  if (capacity < 32) {
+    capacity = 32; // Guarantee min capacity.
   } else if (capacity > HashTable::kMaxCapacity) {
     return Failure::OutOfMemoryException();
   }
 
-  Object* obj = Heap::AllocateHashTable(EntryToIndex(capacity));
+  Object* obj = Heap::AllocateHashTable(EntryToIndex(capacity), pretenure);
   if (!obj->IsFailure()) {
     HashTable::cast(obj)->SetNumberOfElements(0);
     HashTable::cast(obj)->SetNumberOfDeletedElements(0);
     HashTable::cast(obj)->SetCapacity(capacity);
   }
   return obj;
 }
 
 
 // Find entry for key otherwise return kNotFound.
@@ skipping 12 matching lines @@
   return kNotFound;
 }
 
 
 template<typename Shape, typename Key>
 Object* HashTable<Shape, Key>::EnsureCapacity(int n, Key key) {
   int capacity = Capacity();
   int nof = NumberOfElements() + n;
   int nod = NumberOfDeletedElements();
   // Return if:
   //   25% is still free after adding n elements and

[Kasper Lund, 2010/03/03 16:01:06]

Update comment to reflect 50%.

[bak, 2010/03/03 16:18:26]

Done.

   //   at most 50% of the free elements are deleted elements.
-  if ((nof + (nof >> 2) <= capacity) &&
-      (nod <= (capacity - nof) >> 1)) return this;
+  if (nod <= (capacity - nof) >> 1) {
+    int needed_free = nof >> 1;
+    if (nof + needed_free <= capacity) return this;
+  }
 
-  Object* obj = Allocate(nof * 2);
+  const int kMinCapacityForPreTenure = 256;

[Kasper Lund, 2010/03/03 16:01:06]

PreTenure -> Pretenure (to match the rest of the code). Maybe this should be
kMaxCapacityForNonTenured? You can have pretenured hash tables with a smaller
capacity than this.

[bak, 2010/03/03 16:18:26]

I changed the uppercase issue.

+  bool pretenure =
+      (capacity > kMinCapacityForPreTenure) && !Heap::InNewSpace(this);
+  Object* obj = Allocate(nof * 2, pretenure ? TENURED : NOT_TENURED);
   if (obj->IsFailure()) return obj;
 
   AssertNoAllocation no_gc;
   HashTable* table = HashTable::cast(obj);
   WriteBarrierMode mode = table->GetWriteBarrierMode(no_gc);
 
   // Copy prefix to new array.
   for (int i = kPrefixStartIndex;
        i < kPrefixStartIndex + Shape::kPrefixSize;
        i++) {
@@ skipping 1398 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal