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 {
56public:
57 ExecutionCounter();
58 void forceSlowPathConcurrently(); // If you use this, checkIfThresholdCrossedAndSet() may still return false.
59 bool checkIfThresholdCrossedAndSet(CodeBlock*);
60 bool hasCrossedThreshold() const { return m_counter >= 0; }
61 void setNewThreshold(int32_t threshold, CodeBlock*);
62 void deferIndefinitely();
63 double count() const { return static_cast<double>(m_totalCount) + m_counter; }
64 void dump(PrintStream&) const;
65
66 void setNewThresholdForOSRExit(uint32_t activeThreshold, double memoryUsageAdjustedThreshold)
67 {
68 m_activeThreshold = activeThreshold;
69 m_counter = static_cast<int32_t>(-memoryUsageAdjustedThreshold);
70 m_totalCount = memoryUsageAdjustedThreshold;
71 }
72
73 static int32_t maximumExecutionCountsBetweenCheckpoints()
74 {
75 switch (countingVariant) {
76 case CountingForBaseline:
77 return Options::maximumExecutionCountsBetweenCheckpointsForBaseline();
78 case CountingForUpperTiers:
79 return Options::maximumExecutionCountsBetweenCheckpointsForUpperTiers();
80 default:
81 RELEASE_ASSERT_NOT_REACHED();
82 return 0;
83 }
84 }
85
86 template<typename T>
87 static T clippedThreshold(JSGlobalObject* globalObject, T threshold)
88 {
89 int32_t maxThreshold;
90 if (Options::randomizeExecutionCountsBetweenCheckpoints())
91 maxThreshold = globalObject->weakRandomInteger() % maximumExecutionCountsBetweenCheckpoints();
92 else
93 maxThreshold = maximumExecutionCountsBetweenCheckpoints();
94 if (threshold > maxThreshold)
95 threshold = maxThreshold;
96 return threshold;
97 }
98
99private:
100 bool hasCrossedThreshold(CodeBlock*) const;
101 bool setThreshold(CodeBlock*);
102 void reset();
103
104public:
105 // NB. These are intentionally public because it will be modified from machine code.
106
107 // This counter is incremented by the JIT or LLInt. It starts out negative and is
108 // counted up until it becomes non-negative. At the start of a counting period,
109 // the threshold we wish to reach is m_totalCount + m_counter, in the sense that
110 // we will add X to m_totalCount and subtract X from m_counter.
111 int32_t m_counter;
112
113 // Counts the total number of executions we have seen plus the ones we've set a
114 // threshold for in m_counter. Because m_counter's threshold is negative, the
115 // total number of actual executions can always be computed as m_totalCount +
116 // m_counter.
117 float m_totalCount;
118
119 // This is the threshold we were originally targeting, without any correction for
120 // the memory usage heuristics.
121 int32_t m_activeThreshold;
122};
123
124typedef ExecutionCounter<CountingForBaseline> BaselineExecutionCounter;
125typedef ExecutionCounter<CountingForUpperTiers> UpperTierExecutionCounter;
126
127} // namespace JSC
128