StringTable::Lookup*IfExist() handlified.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/265553003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@21100 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/factory.cc

@@ -376,10 +376,10 @@ static inline Handle<String> MakeOrFindTwoCharacterString(Isolate* isolate,
   // Numeric strings have a different hash algorithm not known by
   // LookupTwoCharsStringIfExists, so we skip this step for such strings.
   if (!Between(c1, '0', '9') || !Between(c2, '0', '9')) {
-    String* result;
-    StringTable* table = isolate->heap()->string_table();
-    if (table->LookupTwoCharsStringIfExists(c1, c2, &result)) {
-      return handle(result);
+    Handle<String> result;
+    if (StringTable::LookupTwoCharsStringIfExists(isolate, c1, c2).
+        ToHandle(&result)) {
+      return result;
     }
   }
 

src/heap.cc

@@ -4656,15 +4656,6 @@ void Heap::Verify() {
 #endif
 
 
-bool Heap::InternalizeStringIfExists(String* string, String** result) {
-  if (string->IsInternalizedString()) {
-    *result = string;
-    return true;
-  }
-  return string_table()->LookupStringIfExists(string, result);
-}
-
-
 void Heap::ZapFromSpace() {
   NewSpacePageIterator it(new_space_.FromSpaceStart(),
                           new_space_.FromSpaceEnd());
@@ -6246,12 +6237,11 @@ void KeyedLookupCache::Update(Handle<Map> map,
                               int field_offset) {
   DisallowHeapAllocation no_gc;
   if (!name->IsUniqueName()) {
-    String* internalized_string;
-    if (!map->GetIsolate()->heap()->InternalizeStringIfExists(
-            String::cast(*name), &internalized_string)) {
+    if (!StringTable::InternalizeStringIfExists(name->GetIsolate(),
+                                                Handle<String>::cast(name)).
+        ToHandle(&name)) {
       return;
     }
-    name = handle(internalized_string);
   }
   // This cache is cleared only between mark compact passes, so we expect the
   // cache to only contain old space names.

src/heap.h

@@ -730,8 +730,6 @@ class Heap {
   // Maintain marking consistency for IncrementalMarking.
   void AdjustLiveBytes(Address address, int by, InvocationMode mode);
 
-  bool InternalizeStringIfExists(String* str, String** result);
-
   // Converts the given boolean condition to JavaScript boolean value.
   inline Object* ToBoolean(bool condition);
 

src/objects.cc

@@ -15416,35 +15416,45 @@ class TwoCharHashTableKey : public HashTableKey {
 };
 
 
-bool StringTable::LookupStringIfExists(String* string, String** result) {
-  SLOW_ASSERT(this == HeapObject::cast(this)->GetHeap()->string_table());
-  DisallowHeapAllocation no_alloc;
-  // TODO(ishell): Handlify all the callers and remove this scope.
-  HandleScope scope(GetIsolate());
-  InternalizedStringKey key(handle(string));
-  int entry = FindEntry(&key);
+MaybeHandle<String> StringTable::InternalizeStringIfExists(
+    Isolate* isolate,
+    Handle<String> string) {
+  if (string->IsInternalizedString()) {
+    return string;
+  }
+  return LookupStringIfExists(isolate, string);
+}
+
+
+MaybeHandle<String> StringTable::LookupStringIfExists(
+    Isolate* isolate,
+    Handle<String> string) {
+  Handle<StringTable> string_table = isolate->factory()->string_table();
+  InternalizedStringKey key(string);
+  int entry = string_table->FindEntry(&key);
   if (entry == kNotFound) {
-    return false;
+    return MaybeHandle<String>();
   } else {
-    *result = String::cast(KeyAt(entry));
+    Handle<String> result(String::cast(string_table->KeyAt(entry)), isolate);
     ASSERT(StringShape(*result).IsInternalized());
-    return true;
+    return result;
   }
 }
 
 
-bool StringTable::LookupTwoCharsStringIfExists(uint16_t c1,
-                                               uint16_t c2,
-                                               String** result) {
-  SLOW_ASSERT(this == HeapObject::cast(this)->GetHeap()->string_table());
-  TwoCharHashTableKey key(c1, c2, GetHeap()->HashSeed());
-  int entry = FindEntry(&key);
+MaybeHandle<String> StringTable::LookupTwoCharsStringIfExists(
+    Isolate* isolate,
+    uint16_t c1,
+    uint16_t c2) {
+  Handle<StringTable> string_table = isolate->factory()->string_table();
+  TwoCharHashTableKey key(c1, c2, isolate->heap()->HashSeed());
+  int entry = string_table->FindEntry(&key);
   if (entry == kNotFound) {
-    return false;
+    return MaybeHandle<String>();
   } else {
-    *result = String::cast(KeyAt(entry));
+    Handle<String> result(String::cast(string_table->KeyAt(entry)), isolate);
     ASSERT(StringShape(*result).IsInternalized());
-    return true;
+    return result;
   }
 }
 

src/objects.h

@@ -3741,8 +3741,6 @@ class SeqOneByteString;
 //
 // No special elements in the prefix and the element size is 1
 // because only the string itself (the key) needs to be stored.
-// TODO(ishell): Make StringTable a singleton class and move
-//   Heap::InternalizeStringXX() methods here.
 class StringTable: public HashTable<StringTable,
                                     StringTableShape,
                                     HashTableKey*> {
@@ -3752,11 +3750,21 @@ class StringTable: public HashTable<StringTable,
   static Handle<String> LookupString(Isolate* isolate, Handle<String> key);
   static Handle<String> LookupKey(Isolate* isolate, HashTableKey* key);
 
+  // Tries to internalize given string and returns string handle on success
+  // or an empty handle otherwise.
+  MUST_USE_RESULT static MaybeHandle<String> InternalizeStringIfExists(
+      Isolate* isolate,
+      Handle<String> string);
+
   // Looks up a string that is equal to the given string and returns
-  // true if it is found, assigning the string to the given output
-  // parameter.
-  bool LookupStringIfExists(String* str, String** result);
-  bool LookupTwoCharsStringIfExists(uint16_t c1, uint16_t c2, String** result);
+  // string handle if it is found, or an empty handle otherwise.
+  MUST_USE_RESULT static MaybeHandle<String> LookupStringIfExists(
+      Isolate* isolate,
+      Handle<String> str);
+  MUST_USE_RESULT static MaybeHandle<String> LookupTwoCharsStringIfExists(
+      Isolate* isolate,
+      uint16_t c1,
+      uint16_t c2);
 
   // Casting.
   static inline StringTable* cast(Object* obj);

src/scopeinfo.cc

@@ -437,14 +437,14 @@ void ContextSlotCache::Update(Handle<Object> data,
                               InitializationFlag init_flag,
                               int slot_index) {
   DisallowHeapAllocation no_gc;
-  String* internalized_name;
+  Handle<String> internalized_name;
   ASSERT(slot_index > kNotFound);
-  if (name->GetIsolate()->heap()->InternalizeStringIfExists(
-          *name, &internalized_name)) {
-    int index = Hash(*data, internalized_name);
+  if (StringTable::InternalizeStringIfExists(name->GetIsolate(), name).
+      ToHandle(&internalized_name)) {
+    int index = Hash(*data, *internalized_name);
     Key& key = keys_[index];
     key.data = *data;
-    key.name = internalized_name;
+    key.name = *internalized_name;
     // Please note value only takes a uint as index.
     values_[index] = Value(mode, init_flag, slot_index - kNotFound).raw();
 #ifdef DEBUG
@@ -467,9 +467,9 @@ void ContextSlotCache::ValidateEntry(Handle<Object> data,
                                      InitializationFlag init_flag,
                                      int slot_index) {
   DisallowHeapAllocation no_gc;
-  String* internalized_name;
-  if (name->GetIsolate()->heap()->InternalizeStringIfExists(
-          *name, &internalized_name)) {
+  Handle<String> internalized_name;
+  if (StringTable::InternalizeStringIfExists(name->GetIsolate(), name).
+      ToHandle(&internalized_name)) {
     int index = Hash(*data, *name);
     Key& key = keys_[index];
     ASSERT(key.data == *data);