JavaScriptCore-7600.1.4.9.tar.gz

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

diff --git a/runtime/StructureIDTable.cpp b/runtime/StructureIDTable.cpp
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+/*
+ * Copyright (C) 2013 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. AND ITS CONTRIBUTORS ``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 ITS 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.
+ */
+
+#include "config.h"
+#include "StructureIDTable.h"
+
+#include <limits.h>
+#include <wtf/Atomics.h>
+#include <wtf/DataLog.h>
+#include <wtf/PassOwnPtr.h>
+
+namespace JSC {
+
+StructureIDTable::StructureIDTable()
+    : m_firstFreeOffset(0)
+    , m_table(adoptPtr(new StructureOrOffset[s_initialSize]))
+    , m_size(0)
+    , m_capacity(s_initialSize)
+{
+    // We pre-allocate the first offset so that the null Structure
+    // can still be represented as the StructureID '0'.
+    allocateID(0);
+}
+
+void StructureIDTable::resize(size_t newCapacity)
+{
+    // Create the new table.
+    OwnPtr<StructureOrOffset> newTable = adoptPtr(new StructureOrOffset[newCapacity]);
+
+    // Copy the contents of the old table to the new table.
+    memcpy(newTable.get(), table(), m_capacity * sizeof(StructureOrOffset));
+
+    // Store fence to make sure we've copied everything before doing the swap.
+    WTF::storeStoreFence();
+
+    // Swap the old and new tables.
+    swap(m_table, newTable);
+
+    // Put the old table (now labeled as new) into the list of old tables.
+    m_oldTables.append(newTable.release());
+
+    // Update the capacity.
+    m_capacity = newCapacity;
+}
+
+void StructureIDTable::flushOldTables()
+{
+    m_oldTables.clear();
+}
+
+StructureID StructureIDTable::allocateID(Structure* structure)
+{
+#if USE(JSVALUE64)
+    if (!m_firstFreeOffset) {
+        RELEASE_ASSERT(m_capacity <= UINT_MAX);
+        if (m_size == m_capacity)
+            resize(m_capacity * 2);
+        ASSERT(m_size < m_capacity);
+
+        StructureOrOffset newEntry;
+        newEntry.structure = structure;
+
+        if (m_size == s_unusedID) {
+            m_size++;
+            return allocateID(structure);
+        }
+
+        StructureID result = m_size;
+        table()[result] = newEntry;
+        m_size++;
+        return result;
+    }
+
+    ASSERT(m_firstFreeOffset != s_unusedID);
+
+    StructureID result = m_firstFreeOffset;
+    m_firstFreeOffset = table()[m_firstFreeOffset].offset;
+    table()[result].structure = structure;
+    return result;
+#else
+    return structure;
+#endif
+}
+
+void StructureIDTable::deallocateID(Structure* structure, StructureID structureID)
+{
+#if USE(JSVALUE64)
+    ASSERT(structureID != s_unusedID);
+    RELEASE_ASSERT(table()[structureID].structure == structure);
+    table()[structureID].offset = m_firstFreeOffset;
+    m_firstFreeOffset = structureID;
+#else
+    UNUSED_PARAM(structure);
+    UNUSED_PARAM(structureID);
+#endif
+}
+
+} // namespace JSC