1/*
2 * Copyright (C) 2012-2017 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#pragma once
27
28#include "JSGlobalObject.h"
29#include "Options.h"
30#include <wtf/PrintStream.h>
31
32namespace JSC {
33
34class CodeBlock;
35
36enum CountingVariant {
37 CountingForBaseline,
38 CountingForUpperTiers
39};
40
41double applyMemoryUsageHeuristics(int32_t value, CodeBlock*);
42int32_t applyMemoryUsageHeuristicsAndConvertToInt(int32_t value, CodeBlock*);
43
44inline int32_t formattedTotalExecutionCount(float value)
45{
46 union {
47 int32_t i;
48 float f;
49 } u;
50 u.f = value;
51 return u.i;
52}
53
54template<CountingVariant countingVariant>
55class ExecutionCounter {
56 WTF_MAKE_FAST_ALLOCATED;
57 WTF_MAKE_NONMOVABLE(ExecutionCounter);
58public:
59 ExecutionCounter();
60 void forceSlowPathConcurrently(); // If you use this, checkIfThresholdCrossedAndSet() may still return false.
61 bool checkIfThresholdCrossedAndSet(CodeBlock*);
62 bool hasCrossedThreshold() const { return m_counter >= 0; }
63 void setNewThreshold(int32_t threshold, CodeBlock*);
64 void deferIndefinitely();
65 double count() const { return static_cast<double>(m_totalCount) + m_counter; }
66 void dump(PrintStream&) const;
67
68 void setNewThresholdForOSRExit(uint32_t activeThreshold, double memoryUsageAdjustedThreshold)
69 {
70 m_activeThreshold = activeThreshold;
71 m_counter = static_cast<int32_t>(-memoryUsageAdjustedThreshold);
72 m_totalCount = memoryUsageAdjustedThreshold;
73 }
74
75 static int32_t maximumExecutionCountsBetweenCheckpoints()
76 {
77 switch (countingVariant) {
78 case CountingForBaseline:
79 return Options::maximumExecutionCountsBetweenCheckpointsForBaseline();
80 case CountingForUpperTiers:
81 return Options::maximumExecutionCountsBetweenCheckpointsForUpperTiers();
82 default:
83 RELEASE_ASSERT_NOT_REACHED();
84 return 0;
85 }
86 }
87
88 template<typename T>
89 static T clippedThreshold(JSGlobalObject* globalObject, T threshold)
90 {
91 int32_t maxThreshold;
92 if (Options::randomizeExecutionCountsBetweenCheckpoints() && globalObject)
93 maxThreshold = globalObject->weakRandomInteger() % maximumExecutionCountsBetweenCheckpoints();
94 else
95 maxThreshold = maximumExecutionCountsBetweenCheckpoints();
96 if (threshold > maxThreshold)
97 threshold = maxThreshold;
98 return threshold;
99 }
100
101private:
102 bool hasCrossedThreshold(CodeBlock*) const;
103 bool setThreshold(CodeBlock*);
104 void reset();
105
106public:
107 // NB. These are intentionally public because it will be modified from machine code.
108
109 // This counter is incremented by the JIT or LLInt. It starts out negative and is
110 // counted up until it becomes non-negative. At the start of a counting period,
111 // the threshold we wish to reach is m_totalCount + m_counter, in the sense that
112 // we will add X to m_totalCount and subtract X from m_counter.
113 int32_t m_counter;
114
115 // Counts the total number of executions we have seen plus the ones we've set a
116 // threshold for in m_counter. Because m_counter's threshold is negative, the
117 // total number of actual executions can always be computed as m_totalCount +
118 // m_counter.
119 float m_totalCount;
120
121 // This is the threshold we were originally targeting, without any correction for
122 // the memory usage heuristics.
123 int32_t m_activeThreshold;
124};
125
126typedef ExecutionCounter<CountingForBaseline> BaselineExecutionCounter;
127typedef ExecutionCounter<CountingForUpperTiers> UpperTierExecutionCounter;
128
129} // namespace JSC
130