Speed up access to global variables from eval scopes. Traverse the...

src/objects.cc

 // Copyright 2006-2008 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 5832 matching lines @@
   return counter;
 }
 
 
 int JSObject::GetEnumElementKeys(FixedArray* storage) {
   return GetLocalElementKeys(storage,
                              static_cast<PropertyAttributes>(DONT_ENUM));
 }
 
 
+// Thomas Wang, Integer Hash Functions.
+// http://www.concentric.net/~Ttwang/tech/inthash.htm
+static uint32_t ComputeIntegerHash(uint32_t key) {
+  uint32_t hash = key;
+  hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
+  hash = hash ^ (hash >> 12);
+  hash = hash + (hash << 2);
+  hash = hash ^ (hash >> 4);
+  hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
+  hash = hash ^ (hash >> 16);
+  return hash;
+}
+
+
 // The NumberKey uses carries the uint32_t as key.
 // This avoids allocation in HasProperty.
 class NumberKey : public HashTableKey {
  public:
   explicit NumberKey(uint32_t number) : number_(number) { }
 
  private:
   bool IsMatch(Object* number) {
     return number_ == ToUint32(number);
   }
 
-  // Thomas Wang, Integer Hash Functions.
-  // http://www.concentric.net/~Ttwang/tech/inthash.htm
-  static uint32_t ComputeHash(uint32_t key) {
-    uint32_t hash = key;
-    hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
-    hash = hash ^ (hash >> 12);
-    hash = hash + (hash << 2);
-    hash = hash ^ (hash >> 4);
-    hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
-    hash = hash ^ (hash >> 16);
-    return hash;
-  }
-
-  uint32_t Hash() { return ComputeHash(number_); }
+  uint32_t Hash() { return ComputeIntegerHash(number_); }
 
   HashFunction GetHashFunction() { return NumberHash; }
 
   Object* GetObject() {
     return Heap::NumberFromDouble(number_);
   }
 
   static uint32_t NumberHash(Object* obj) {
-    return ComputeHash(ToUint32(obj));
+    return ComputeIntegerHash(ToUint32(obj));
   }
 
   static uint32_t ToUint32(Object* obj) {
     ASSERT(obj->IsNumber());
     return static_cast<uint32_t>(obj->Number());
   }
 
   bool IsStringKey() { return false; }
 
   uint32_t number_;
@@ skipping 17 matching lines @@
 
   static uint32_t StringHash(Object* obj) {
     return String::cast(obj)->Hash();
   }
 
   bool IsStringKey() { return true; }
 
   String* string_;
 };
 
+
+// StringSharedKeys are used as keys in the eval cache.
+class StringSharedKey : public HashTableKey {
+ public:
+  StringSharedKey(String* source, SharedFunctionInfo* shared)
+      : source_(source), shared_(shared) { }
+
+  bool IsMatch(Object* other) {
+    if (!other->IsFixedArray()) return false;
+    FixedArray* pair = FixedArray::cast(other);
+    SharedFunctionInfo* shared = SharedFunctionInfo::cast(pair->get(0));
+    if (shared != shared_) return false;
+    String* source = String::cast(pair->get(1));
+    return source->Equals(source_);
+  }
+
+  typedef uint32_t (*HashFunction)(Object* obj);
+
+  virtual HashFunction GetHashFunction() { return StringSharedHash; }
+
+  static uint32_t StringSharedHashHelper(String* source,
+                                         SharedFunctionInfo* shared) {
+    uint32_t hash = source->Hash();
+    if (shared->HasSourceCode()) {
+      // Instead of using the SharedFunctionInfo pointer in the hash
+      // code computation, we use a combination of the hash of the
+      // script source code and the start and end positions.  We do
+      // this to ensure that the cache entries can survive garbage
+      // collection.
+      Script* script = Script::cast(shared->script());
+      hash ^= String::cast(script->source())->Hash();

[Kasper Lund, 2009/02/24 11:21:08]

It's not clear that this is a great way of mixing the bits.

+      hash ^= ((shared->start_position() << 16) | shared->end_position());
+    }
+    return hash;
+  }
+
+  static uint32_t StringSharedHash(Object* obj) {
+    FixedArray* pair = FixedArray::cast(obj);
+    SharedFunctionInfo* shared = SharedFunctionInfo::cast(pair->get(0));
+    String* source = String::cast(pair->get(1));
+    return StringSharedHashHelper(source, shared);
+  }
+
+  virtual uint32_t Hash() {
+    return StringSharedHashHelper(source_, shared_);
+  }
+
+  virtual Object* GetObject() {
+    Object* obj = Heap::AllocateFixedArray(2);
+    if (obj->IsFailure()) return obj;
+    FixedArray* pair = FixedArray::cast(obj);
+    pair->set(0, shared_);
+    pair->set(1, source_);
+    return pair;
+  }
+
+  virtual bool IsStringKey() { return false; }
+
+ private:
+  String* source_;
+  SharedFunctionInfo* shared_;
+};
+
+
 // RegExpKey carries the source and flags of a regular expression as key.
 class RegExpKey : public HashTableKey {
  public:
   RegExpKey(String* string, JSRegExp::Flags flags)
       : string_(string),
         flags_(Smi::FromInt(flags.value())) { }
 
   bool IsMatch(Object* obj) {
     FixedArray* val = FixedArray::cast(obj);
     return string_->Equals(String::cast(val->get(JSRegExp::kSourceIndex)))
@@ skipping 293 matching lines @@
 
 
 Object* CompilationCacheTable::Lookup(String* src) {
   StringKey key(src);
   int entry = FindEntry(&key);
   if (entry == -1) return Heap::undefined_value();
   return get(EntryToIndex(entry) + 1);
 }
 
 
+Object* CompilationCacheTable::LookupEval(String* src, Context* context) {
+  StringSharedKey key(src, context->closure()->shared());
+  int entry = FindEntry(&key);
+  if (entry == -1) return Heap::undefined_value();
+  return get(EntryToIndex(entry) + 1);
+}
+
+
 Object* CompilationCacheTable::LookupRegExp(String* src,
                                             JSRegExp::Flags flags) {
   RegExpKey key(src, flags);
   int entry = FindEntry(&key);
   if (entry == -1) return Heap::undefined_value();
   return get(EntryToIndex(entry) + 1);
 }
 
 
 Object* CompilationCacheTable::Put(String* src, Object* value) {
   StringKey key(src);
   Object* obj = EnsureCapacity(1, &key);
   if (obj->IsFailure()) return obj;
 
   CompilationCacheTable* cache =
       reinterpret_cast<CompilationCacheTable*>(obj);
   int entry = cache->FindInsertionEntry(src, key.Hash());
   cache->set(EntryToIndex(entry), src);
   cache->set(EntryToIndex(entry) + 1, value);
   cache->ElementAdded();
   return cache;
 }
 
 
+Object* CompilationCacheTable::PutEval(String* src,
+                                       Context* context,
+                                       Object* value) {
+  StringSharedKey key(src, context->closure()->shared());
+  Object* obj = EnsureCapacity(1, &key);
+  if (obj->IsFailure()) return obj;
+
+  CompilationCacheTable* cache =
+      reinterpret_cast<CompilationCacheTable*>(obj);
+  int entry = cache->FindInsertionEntry(src, key.Hash());
+
+  Object* k = key.GetObject();
+  if (k->IsFailure()) return k;
+
+  cache->set(EntryToIndex(entry), k);
+  cache->set(EntryToIndex(entry) + 1, value);
+  cache->ElementAdded();
+  return cache;
+}
+
+
 Object* CompilationCacheTable::PutRegExp(String* src,
                                          JSRegExp::Flags flags,
                                          FixedArray* value) {
   RegExpKey key(src, flags);
   Object* obj = EnsureCapacity(1, &key);
   if (obj->IsFailure()) return obj;
 
   CompilationCacheTable* cache =
       reinterpret_cast<CompilationCacheTable*>(obj);
   int entry = cache->FindInsertionEntry(value, key.Hash());
@@ skipping 886 matching lines @@
   // No break point.
   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();
 }
 
 
 } }  // namespace v8::internal