1/* 2 * Copyright (C) 2012 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26#ifndef ExecutionCounter_h 27#define ExecutionCounter_h 28 29#include "JSGlobalObject.h" 30#include "Options.h" 31#include <wtf/PrintStream.h> 32#include <wtf/SimpleStats.h> 33 34namespace JSC { 35 36class CodeBlock; 37 38class ExecutionCounter { 39public: 40 ExecutionCounter(); 41 bool checkIfThresholdCrossedAndSet(CodeBlock*); 42 void setNewThreshold(int32_t threshold, CodeBlock*); 43 void deferIndefinitely(); 44 double count() const { return static_cast<double>(m_totalCount) + m_counter; } 45 void dump(PrintStream&) const; 46 static double applyMemoryUsageHeuristics(int32_t value, CodeBlock*); 47 static int32_t applyMemoryUsageHeuristicsAndConvertToInt(int32_t value, CodeBlock*); 48 template<typename T> 49 static T clippedThreshold(JSGlobalObject* globalObject, T threshold) 50 { 51 int32_t maxThreshold; 52 if (Options::randomizeExecutionCountsBetweenCheckpoints()) 53 maxThreshold = globalObject->weakRandomInteger() % Options::maximumExecutionCountsBetweenCheckpoints(); 54 else 55 maxThreshold = Options::maximumExecutionCountsBetweenCheckpoints(); 56 if (threshold > maxThreshold) 57 threshold = maxThreshold; 58 return threshold; 59 } 60 61 static int32_t formattedTotalCount(float value) 62 { 63 union { 64 int32_t i; 65 float f; 66 } u; 67 u.f = value; 68 return u.i; 69 } 70 71private: 72 bool hasCrossedThreshold(CodeBlock*) const; 73 bool setThreshold(CodeBlock*); 74 void reset(); 75 76public: 77 78 // NB. These are intentionally public because it will be modified from machine code. 79 80 // This counter is incremented by the JIT or LLInt. It starts out negative and is 81 // counted up until it becomes non-negative. At the start of a counting period, 82 // the threshold we wish to reach is m_totalCount + m_counter, in the sense that 83 // we will add X to m_totalCount and subtract X from m_counter. 84 int32_t m_counter; 85 86 // Counts the total number of executions we have seen plus the ones we've set a 87 // threshold for in m_counter. Because m_counter's threshold is negative, the 88 // total number of actual executions can always be computed as m_totalCount + 89 // m_counter. 90 float m_totalCount; 91 92 // This is the threshold we were originally targetting, without any correction for 93 // the memory usage heuristics. 94 int32_t m_activeThreshold; 95}; 96 97} // namespace JSC 98 99#endif // ExecutionCounter_h 100 101