- Adjust the number to string cache based on the max semispace size....

src/heap.cc

 // Copyright 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 558 matching lines @@
   // At any old GC clear the keyed lookup cache to enable collection of unused
   // maps.
   KeyedLookupCache::Clear();
   ContextSlotCache::Clear();
   DescriptorLookupCache::Clear();
 
   CompilationCache::MarkCompactPrologue();
 
   Top::MarkCompactPrologue(is_compacting);
   ThreadManager::MarkCompactPrologue(is_compacting);
+
+  if (is_compacting) FlushNumberStringCache();
 }
 
 
 void Heap::MarkCompactEpilogue(bool is_compacting) {
   Top::MarkCompactEpilogue(is_compacting);
   ThreadManager::MarkCompactEpilogue(is_compacting);
 }
 
 
 Object* Heap::FindCodeObject(Address a) {
@@ skipping 977 matching lines @@
   set_code_stubs(NumberDictionary::cast(obj));
 
   // Allocate the non_monomorphic_cache used in stub-cache.cc. The initial size
   // is set to avoid expanding the dictionary during bootstrapping.
   obj = NumberDictionary::Allocate(64);
   if (obj->IsFailure()) return false;
   set_non_monomorphic_cache(NumberDictionary::cast(obj));
 
   CreateFixedStubs();
 
-  // Allocate the number->string conversion cache
-  obj = AllocateFixedArray(kNumberStringCacheSize * 2);
-  if (obj->IsFailure()) return false;
-  set_number_string_cache(FixedArray::cast(obj));
+  if (InitializeNumberStringCache()->IsFailure()) return false;
 
   // Allocate cache for single character strings.
   obj = AllocateFixedArray(String::kMaxAsciiCharCode+1);
   if (obj->IsFailure()) return false;
   set_single_character_string_cache(FixedArray::cast(obj));
 
   // Allocate cache for external strings pointing to native source code.
   obj = AllocateFixedArray(Natives::GetBuiltinsCount());
   if (obj->IsFailure()) return false;
   set_natives_source_cache(FixedArray::cast(obj));
@@ skipping 10 matching lines @@
   // Initialize descriptor cache.
   DescriptorLookupCache::Clear();
 
   // Initialize compilation cache.
   CompilationCache::Clear();
 
   return true;
 }
 
 
+Object* Heap::InitializeNumberStringCache() {
+  // Compute the size of the number string cache based on the max heap size.
+  // max_semispace_size_ == 512 KB => number_string_cache_size = 16.

[Mads Ager (chromium), 2010/01/06 11:16:00]

32?

Also, the logic seems different from what the comment suggests.  Update the
comment?

+  // max_semispace_size_ ==   8 MB => number_string_cache_size = 16KB.
+  int number_string_cache_size = max_semispace_size_ / 512;
+  number_string_cache_size = Max(32, Min(16*KB, number_string_cache_size));
+  Object* obj = AllocateFixedArray(number_string_cache_size * 2);
+  if (!obj->IsFailure()) set_number_string_cache(FixedArray::cast(obj));
+  return obj;
+}
+
+
+void Heap::FlushNumberStringCache() {
+  // Flush the number to string cache.
+  int len = number_string_cache()->length();
+  for (int i = 0; i < len; i++) {
+    number_string_cache()->set_undefined(i);
+  }
+}
+
+
 static inline int double_get_hash(double d) {
   DoubleRepresentation rep(d);
-  return ((static_cast<int>(rep.bits) ^ static_cast<int>(rep.bits >> 32)) &
-          (Heap::kNumberStringCacheSize - 1));
+  return static_cast<int>(rep.bits) ^ static_cast<int>(rep.bits >> 32);
 }
 
 
 static inline int smi_get_hash(Smi* smi) {
-  return (smi->value() & (Heap::kNumberStringCacheSize - 1));
+  return smi->value();
 }
 
 
-
 Object* Heap::GetNumberStringCache(Object* number) {
   int hash;
+  int mask = (number_string_cache()->length() >> 1) - 1;
   if (number->IsSmi()) {
-    hash = smi_get_hash(Smi::cast(number));
+    hash = smi_get_hash(Smi::cast(number)) & mask;
   } else {
-    hash = double_get_hash(number->Number());
+    hash = double_get_hash(number->Number()) & mask;
   }
   Object* key = number_string_cache()->get(hash * 2);
   if (key == number) {
     return String::cast(number_string_cache()->get(hash * 2 + 1));
   } else if (key->IsHeapNumber() &&
              number->IsHeapNumber() &&
              key->Number() == number->Number()) {
     return String::cast(number_string_cache()->get(hash * 2 + 1));
   }
   return undefined_value();
 }
 
 
 void Heap::SetNumberStringCache(Object* number, String* string) {
   int hash;
+  int mask = (number_string_cache()->length() >> 1) - 1;
   if (number->IsSmi()) {
-    hash = smi_get_hash(Smi::cast(number));
+    hash = smi_get_hash(Smi::cast(number)) & mask;
     number_string_cache()->set(hash * 2, number, SKIP_WRITE_BARRIER);
   } else {
-    hash = double_get_hash(number->Number());
+    hash = double_get_hash(number->Number()) & mask;
     number_string_cache()->set(hash * 2, number);
   }
   number_string_cache()->set(hash * 2 + 1, string);
 }
 
 
 Object* Heap::SmiOrNumberFromDouble(double value,
                                     bool new_object,
                                     PretenureFlag pretenure) {
   // We need to distinguish the minus zero value and this cannot be
@@ skipping 2422 matching lines @@
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 List<Object*> ExternalStringTable::new_space_strings_;
 List<Object*> ExternalStringTable::old_space_strings_;
 
 } }  // namespace v8::internal