webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

1 files changed, 153 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/HasOwnPropertyCache.h b/Source/JavaScriptCore/runtime/HasOwnPropertyCache.h
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+++ b/Source/JavaScriptCore/runtime/HasOwnPropertyCache.h
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+/*
+ * Copyright (C) 2016 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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 with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#pragma once
+
+#include "JSProxy.h"
+#include "PropertySlot.h"
+#include "Structure.h"
+
+namespace JSC {
+
+class HasOwnPropertyCache {
+    static const uint32_t size = 2 * 1024;
+    static_assert(!(size & (size - 1)), "size should be a power of two.");
+public:
+    static const uint32_t mask = size - 1;
+
+    struct Entry {
+        static ptrdiff_t offsetOfStructureID() { return OBJECT_OFFSETOF(Entry, structureID); }
+        static ptrdiff_t offsetOfImpl() { return OBJECT_OFFSETOF(Entry, impl); }
+        static ptrdiff_t offsetOfResult() { return OBJECT_OFFSETOF(Entry, result); }
+
+        Entry() = default;
+
+        Entry(RefPtr<UniquedStringImpl>&& impl, StructureID structureID, bool result)
+            : impl(WTFMove(impl))
+            , structureID(structureID)
+            , result(result)
+        { }
+
+        Entry& operator=(Entry&& other)
+        {
+            impl = WTFMove(other.impl);
+            structureID = other.structureID;
+            result = other.result;
+            return *this;
+        }
+
+        RefPtr<UniquedStringImpl> impl { };
+        StructureID structureID { 0 };
+        bool result { false };
+    };
+
+    HasOwnPropertyCache() = delete;
+
+    void operator delete(void* cache)
+    {
+        static_cast<HasOwnPropertyCache*>(cache)->clear();
+        fastFree(cache);
+    }
+
+    static HasOwnPropertyCache* create()
+    {
+        size_t allocationSize = sizeof(Entry) * size;
+        HasOwnPropertyCache* result = static_cast<HasOwnPropertyCache*>(fastMalloc(allocationSize));
+        result->clearBuffer();
+        return result;
+    }
+
+    ALWAYS_INLINE static uint32_t hash(StructureID structureID, UniquedStringImpl* impl)
+    {
+        return bitwise_cast<uint32_t>(structureID) + impl->hash();
+    }
+
+    ALWAYS_INLINE std::optional<bool> get(Structure* structure, PropertyName propName)
+    {
+        UniquedStringImpl* impl = propName.uid();
+        StructureID id = structure->id();
+        uint32_t index = HasOwnPropertyCache::hash(id, impl) & mask;
+        Entry& entry = bitwise_cast<Entry*>(this)[index];
+        if (entry.structureID == id && entry.impl.get() == impl)
+            return entry.result;
+        return std::nullopt;
+    }
+
+    ALWAYS_INLINE void tryAdd(VM& vm, PropertySlot& slot, JSObject* object, PropertyName propName, bool result)
+    {
+        if (parseIndex(propName))
+            return;
+
+        if (!slot.isCacheable() && !slot.isUnset())
+            return;
+
+        if (object->type() == PureForwardingProxyType || object->type() == ImpureProxyType)
+            return;
+
+        Structure* structure = object->structure(vm);
+        if (!structure->typeInfo().prohibitsPropertyCaching()
+            && structure->propertyAccessesAreCacheable()
+            && (!slot.isUnset() || structure->propertyAccessesAreCacheableForAbsence())) {
+            if (structure->isDictionary()) {
+                // FIXME: We should be able to flatten a dictionary object again.
+                // https://bugs.webkit.org/show_bug.cgi?id=163092
+                return;
+            }
+
+            ASSERT(!result == slot.isUnset());
+
+            UniquedStringImpl* impl = propName.uid();
+            StructureID id = structure->id();
+            uint32_t index = HasOwnPropertyCache::hash(id, impl) & mask;
+            bitwise_cast<Entry*>(this)[index] = Entry { RefPtr<UniquedStringImpl>(impl), id, result };
+        }
+    }
+
+    void clear()
+    {
+        Entry* buffer = bitwise_cast<Entry*>(this);
+        for (uint32_t i = 0; i < size; ++i)
+            buffer[i].Entry::~Entry();
+
+        clearBuffer();
+    }
+
+private:
+    void clearBuffer()
+    {
+        Entry* buffer = bitwise_cast<Entry*>(this);
+        for (uint32_t i = 0; i < size; ++i)
+            new (&buffer[i]) Entry();
+    }
+};
+
+ALWAYS_INLINE HasOwnPropertyCache* VM::ensureHasOwnPropertyCache()
+{
+    if (UNLIKELY(!m_hasOwnPropertyCache))
+        m_hasOwnPropertyCache = std::unique_ptr<HasOwnPropertyCache>(HasOwnPropertyCache::create());
+    return m_hasOwnPropertyCache.get();
+}
+
+} // namespace JSC