webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

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diff --git a/Source/JavaScriptCore/heap/CellState.h b/Source/JavaScriptCore/heap/CellState.h
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+/*
+ * Copyright (C) 2015-2017 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.
+ */
+
+#pragma once
+
+#include <wtf/Assertions.h>
+
+namespace JSC {
+
+// The CellState of a cell is a kind of hint about what the state of the cell is.
+enum class CellState : uint8_t {
+    // The object is either currently being scanned, or it has finished being scanned, or this
+    // is a full collection and it's actually a white object (you'd know because its mark bit
+    // would be clear).
+    PossiblyBlack = 0,
+    
+    // The object is in eden. During GC, this means that the object has not been marked yet.
+    DefinitelyWhite = 1,
+
+    // This sorta means that the object is grey - i.e. it will be scanned. Or it could be white
+    // during a full collection if its mark bit is clear. That would happen if it had been black,
+    // got barriered, and we did a full collection.
+    PossiblyGrey = 2
+};
+
+static const unsigned blackThreshold = 0; // x <= blackThreshold means x is PossiblyOldOrBlack.
+static const unsigned tautologicalThreshold = 100; // x <= tautologicalThreshold is always true.
+
+inline bool isWithinThreshold(CellState cellState, unsigned threshold)
+{
+    return static_cast<unsigned>(cellState) <= threshold;
+}
+
+} // namespace JSC