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DFGExitProfile.h
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/*
* Copyright (C) 2011, 2012, 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. ``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 "ConcurrentJITLock.h"
#include "ExitKind.h"
#include <wtf/HashSet.h>
#include <wtf/OwnPtr.h>
#include <wtf/Vector.h>
namespace JSC { namespace DFG {
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)
{
if (m_kind == ArgumentsEscaped) {
// Count this one globally. It doesn't matter where in the code block the arguments excaped;
// the fact that they did is not associated with any particular instruction.
m_bytecodeOffset = 0;
}
}
// Use this constructor if you wish for the exit site to be counted globally within its
// code block.
explicit FrequentExitSite(ExitKind kind)
: m_bytecodeOffset(0)
, m_kind(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 ConcurrentJITLocker&, const FrequentExitSite&);
// Get the frequent exit sites for a bytecode index. This is O(n), and is
// meant to only be used from debugging/profiling code.
Vector<FrequentExitSite> exitSitesFor(unsigned bytecodeIndex);
// This is O(n) and should be called on less-frequently executed code paths
// in the compiler. It should be strictly cheaper than building a
// QueryableExitProfile, if you really expect this to be called infrequently
// and you believe that there are few exit sites.
bool hasExitSite(const ConcurrentJITLocker&, const FrequentExitSite&) const;
bool hasExitSite(const ConcurrentJITLocker& locker, ExitKind kind) const
{
return hasExitSite(locker, FrequentExitSite(kind));
}
bool hasExitSite(const ConcurrentJITLocker& locker, unsigned bytecodeIndex, ExitKind kind) const
{
return hasExitSite(locker, FrequentExitSite(bytecodeIndex, kind));
}
private:
friend class QueryableExitProfile;
OwnPtr<Vector<FrequentExitSite>> m_frequentExitSites;
};
class QueryableExitProfile {
public:
QueryableExitProfile();
~QueryableExitProfile();
void initialize(const ConcurrentJITLocker&, const ExitProfile&);
bool hasExitSite(const FrequentExitSite& site) const
{
return m_frequentExitSites.find(site) != m_frequentExitSites.end();
}
bool hasExitSite(ExitKind kind) const
{
return hasExitSite(FrequentExitSite(kind));
}
bool hasExitSite(unsigned bytecodeIndex, ExitKind kind) const
{
return hasExitSite(FrequentExitSite(bytecodeIndex, kind));
}
private:
HashSet<FrequentExitSite> m_frequentExitSites;
};
} } // namespace JSC::DFG
#endif // DFGExitProfile_h