JavaScriptCore-7600.1.4.11.8.tar.gz

[apple/javascriptcore.git] / runtime / SmallStrings.cpp

diff --git a/runtime/SmallStrings.cpp b/runtime/SmallStrings.cpp
index 0f5df4a23884bfe40f651fc335dda7a1f13ecfeb..a4bdb0c9e3cbfbacf58ed281957f0adf6a8794b1 100644 (file)
--- a/runtime/SmallStrings.cpp
+++ b/runtime/SmallStrings.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 Apple Inc. All Rights Reserved.
+ * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -26,116 +26,108 @@
 #include "config.h"
 #include "SmallStrings.h"
 
+#include "HeapRootVisitor.h"
 #include "JSGlobalObject.h"
 #include "JSString.h"
-
+#include "JSCInlines.h"
 #include <wtf/Noncopyable.h>
+#include <wtf/PassOwnPtr.h>
+#include <wtf/text/StringImpl.h>
 
 namespace JSC {
-static const unsigned numCharactersToStore = 0x100;
 
-static inline bool isMarked(JSString* string)
-{
-    return string && Heap::isCellMarked(string);
-}
-
-class SmallStringsStorage : public Noncopyable {
+class SmallStringsStorage {
+    WTF_MAKE_NONCOPYABLE(SmallStringsStorage); WTF_MAKE_FAST_ALLOCATED;
 public:
     SmallStringsStorage();
 
-    UString::Rep* rep(unsigned char character) { return m_reps[character].get(); }
+    StringImpl* rep(unsigned char character)
+    {
+        return m_reps[character].get();
+    }
 
 private:
-    RefPtr<UString::Rep> m_reps[numCharactersToStore];
+    static const unsigned singleCharacterStringCount = maxSingleCharacterString + 1;
+
+    RefPtr<StringImpl> m_reps[singleCharacterStringCount];
 };
 
 SmallStringsStorage::SmallStringsStorage()
 {
-    UChar* characterBuffer = 0;
-    RefPtr<UStringImpl> baseString = UStringImpl::createUninitialized(numCharactersToStore, characterBuffer);
-    for (unsigned i = 0; i < numCharactersToStore; ++i) {
+    LChar* characterBuffer = 0;
+    RefPtr<StringImpl> baseString = StringImpl::createUninitialized(singleCharacterStringCount, characterBuffer);
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
         characterBuffer[i] = i;
-        m_reps[i] = UStringImpl::create(baseString, i, 1);
+        m_reps[i] = AtomicString::add(PassRefPtr<StringImpl>(StringImpl::createSubstringSharingImpl(baseString, i, 1)).get());
     }
 }
 
 SmallStrings::SmallStrings()
+    : m_emptyString(0)
+#define JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE(name) , m_##name(0)
+    JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE)
+#undef JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE
+    , m_nullObjectString(nullptr)
+    , m_undefinedObjectString(nullptr)
 {
-    COMPILE_ASSERT(numCharactersToStore == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
-    clear();
-}
+    COMPILE_ASSERT(singleCharacterStringCount == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
 
-SmallStrings::~SmallStrings()
-{
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i)
+        m_singleCharacterStrings[i] = 0;
 }
 
-void SmallStrings::markChildren(MarkStack& markStack)
+void SmallStrings::initializeCommonStrings(VM& vm)
 {
-    /*
-       Our hypothesis is that small strings are very common. So, we cache them
-       to avoid GC churn. However, in cases where this hypothesis turns out to
-       be false -- including the degenerate case where all JavaScript execution
-       has terminated -- we don't want to waste memory.
-
-       To test our hypothesis, we check if any small string has been marked. If
-       so, it's probably reasonable to mark the rest. If not, we clear the cache.
-     */
-
-    bool isAnyStringMarked = isMarked(m_emptyString);
-    for (unsigned i = 0; i < numCharactersToStore && !isAnyStringMarked; ++i)
-        isAnyStringMarked = isMarked(m_singleCharacterStrings[i]);
-    
-    if (!isAnyStringMarked) {
-        clear();
-        return;
-    }
-    
-    if (m_emptyString)
-        markStack.append(m_emptyString);
-    for (unsigned i = 0; i < numCharactersToStore; ++i) {
-        if (m_singleCharacterStrings[i])
-            markStack.append(m_singleCharacterStrings[i]);
-    }
+    createEmptyString(&vm);
+    for (unsigned i = 0; i <= maxSingleCharacterString; ++i)
+        createSingleCharacterString(&vm, i);
+#define JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE(name) initialize(&vm, m_##name, #name);
+    JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE)
+#undef JSC_COMMON_STRINGS_ATTRIBUTE_INITIALIZE
+    initialize(&vm, m_nullObjectString, "[object Null]");
+    initialize(&vm, m_undefinedObjectString, "[object Undefined]");
 }
 
-void SmallStrings::clear()
+void SmallStrings::visitStrongReferences(SlotVisitor& visitor)
 {
-    m_emptyString = 0;
-    for (unsigned i = 0; i < numCharactersToStore; ++i)
-        m_singleCharacterStrings[i] = 0;
+    visitor.appendUnbarrieredPointer(&m_emptyString);
+    for (unsigned i = 0; i <= maxSingleCharacterString; ++i)
+        visitor.appendUnbarrieredPointer(m_singleCharacterStrings + i);
+#define JSC_COMMON_STRINGS_ATTRIBUTE_VISIT(name) visitor.appendUnbarrieredPointer(&m_##name);
+    JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ATTRIBUTE_VISIT)
+#undef JSC_COMMON_STRINGS_ATTRIBUTE_VISIT
+    visitor.appendUnbarrieredPointer(&m_nullObjectString);
+    visitor.appendUnbarrieredPointer(&m_undefinedObjectString);
 }
 
-unsigned SmallStrings::count() const
+SmallStrings::~SmallStrings()
 {
-    unsigned count = 0;
-    if (m_emptyString)
-        ++count;
-    for (unsigned i = 0; i < numCharactersToStore; ++i) {
-        if (m_singleCharacterStrings[i])
-            ++count;
-    }
-    return count;
 }
 
-void SmallStrings::createEmptyString(JSGlobalData* globalData)
+void SmallStrings::createEmptyString(VM* vm)
 {
     ASSERT(!m_emptyString);
-    m_emptyString = new (globalData) JSString(globalData, "", JSString::HasOtherOwner);
+    m_emptyString = JSString::createHasOtherOwner(*vm, StringImpl::empty());
 }
 
-void SmallStrings::createSingleCharacterString(JSGlobalData* globalData, unsigned char character)
+void SmallStrings::createSingleCharacterString(VM* vm, unsigned char character)
 {
     if (!m_storage)
-        m_storage.set(new SmallStringsStorage);
+        m_storage = adoptPtr(new SmallStringsStorage);
     ASSERT(!m_singleCharacterStrings[character]);
-    m_singleCharacterStrings[character] = new (globalData) JSString(globalData, m_storage->rep(character), JSString::HasOtherOwner);
+    m_singleCharacterStrings[character] = JSString::createHasOtherOwner(*vm, PassRefPtr<StringImpl>(m_storage->rep(character)));
 }
 
-UString::Rep* SmallStrings::singleCharacterStringRep(unsigned char character)
+StringImpl* SmallStrings::singleCharacterStringRep(unsigned char character)
 {
     if (!m_storage)
-        m_storage.set(new SmallStringsStorage);
+        m_storage = adoptPtr(new SmallStringsStorage);
     return m_storage->rep(character);
 }
 
+void SmallStrings::initialize(VM* vm, JSString*& string, const char* value) const
+{
+    string = JSString::create(*vm, StringImpl::create(value));
+}
+
 } // namespace JSC