Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 190 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/bytecode/DFGExitProfile.h b/Source/JavaScriptCore/bytecode/DFGExitProfile.h
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+++ b/Source/JavaScriptCore/bytecode/DFGExitProfile.h
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+/*
+ * Copyright (C) 2011 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. 
+ */
+
+#ifndef DFGExitProfile_h
+#define DFGExitProfile_h
+
+#include <wtf/HashSet.h>
+#include <wtf/OwnPtr.h>
+#include <wtf/Vector.h>
+
+namespace JSC { namespace DFG {
+
+enum ExitKind {
+    ExitKindUnset,
+    BadType, // We exited because a type prediction was wrong.
+    BadCache, // We exited because an inline cache was wrong.
+    Overflow, // We exited because of overflow.
+    NegativeZero, // We exited because we encountered negative zero.
+    Uncountable, // We exited for none of the above reasons, and we should not count it. Most uses of this should be viewed as a FIXME.
+};
+
+#ifndef NDEBUG
+inline const char* exitKindToString(ExitKind kind)
+{
+    switch (kind) {
+    case ExitKindUnset:
+        return "Unset";
+    case BadType:
+        return "BadType";
+    case BadCache:
+        return "BadCache";
+    case Overflow:
+        return "Overflow";
+    case NegativeZero:
+        return "NegativeZero";
+    default:
+        return "Unknown";
+    }
+}
+#endif
+
+inline bool exitKindIsCountable(ExitKind kind)
+{
+    switch (kind) {
+    case ExitKindUnset:
+        ASSERT_NOT_REACHED();
+    case BadType:
+    case Uncountable:
+        return false;
+    default:
+        return true;
+    }
+}
+
+class FrequentExitSite {
+public:
+    FrequentExitSite()
+        : m_bytecodeOffset(0) // 0 = empty value
+        , m_kind(ExitKindUnset)
+    {
+    }
+    
+    FrequentExitSite(WTF::HashTableDeletedValueType)
+        : m_bytecodeOffset(1) // 1 = deleted value
+        , m_kind(ExitKindUnset)
+    {
+    }
+    
+    explicit FrequentExitSite(unsigned bytecodeOffset, ExitKind kind)
+        : m_bytecodeOffset(bytecodeOffset)
+        , m_kind(kind)
+    {
+        ASSERT(exitKindIsCountable(kind));
+    }
+    
+    bool operator!() const
+    {
+        return m_kind == ExitKindUnset;
+    }
+    
+    bool operator==(const FrequentExitSite& other) const
+    {
+        return m_bytecodeOffset == other.m_bytecodeOffset
+            && m_kind == other.m_kind;
+    }
+    
+    unsigned hash() const
+    {
+        return WTF::intHash(m_bytecodeOffset) + m_kind;
+    }
+    
+    unsigned bytecodeOffset() const { return m_bytecodeOffset; }
+    ExitKind kind() const { return m_kind; }
+
+    bool isHashTableDeletedValue() const
+    {
+        return m_kind == ExitKindUnset && m_bytecodeOffset;
+    }
+
+private:
+    unsigned m_bytecodeOffset;
+    ExitKind m_kind;
+};
+
+struct FrequentExitSiteHash {
+    static unsigned hash(const FrequentExitSite& key) { return key.hash(); }
+    static bool equal(const FrequentExitSite& a, const FrequentExitSite& b) { return a == b; }
+    static const bool safeToCompareToEmptyOrDeleted = true;
+};
+
+} } // namespace JSC::DFG
+
+namespace WTF {
+
+template<typename T> struct DefaultHash;
+template<> struct DefaultHash<JSC::DFG::FrequentExitSite> {
+    typedef JSC::DFG::FrequentExitSiteHash Hash;
+};
+
+template<typename T> struct HashTraits;
+template<> struct HashTraits<JSC::DFG::FrequentExitSite> : SimpleClassHashTraits<JSC::DFG::FrequentExitSite> { };
+
+} // namespace WTF
+
+namespace JSC { namespace DFG {
+
+class QueryableExitProfile;
+
+class ExitProfile {
+public:
+    ExitProfile();
+    ~ExitProfile();
+    
+    // Add a new frequent exit site. Return true if this is a new one, or false
+    // if we already knew about it. This is an O(n) operation, because it errs
+    // on the side of keeping the data structure compact. Also, this will only
+    // be called a fixed number of times per recompilation. Recompilation is
+    // rare to begin with, and implies doing O(n) operations on the CodeBlock
+    // anyway.
+    bool add(const FrequentExitSite&);
+    
+private:
+    friend class QueryableExitProfile;
+    
+    OwnPtr<Vector<FrequentExitSite> > m_frequentExitSites;
+};
+
+class QueryableExitProfile {
+public:
+    explicit QueryableExitProfile(const ExitProfile&);
+    ~QueryableExitProfile();
+    
+    bool hasExitSite(const FrequentExitSite& site) const
+    {
+        return m_frequentExitSites.find(site) != m_frequentExitSites.end();
+    }
+    
+    bool hasExitSite(unsigned bytecodeIndex, ExitKind kind) const
+    {
+        return hasExitSite(FrequentExitSite(bytecodeIndex, kind));
+    }
+private:
+    HashSet<FrequentExitSite> m_frequentExitSites;
+};
+
+} } // namespace JSC::DFG
+
+#endif // DFGExitProfile_h