GC constraint solving should be parallel
[WebKit-https.git] / Source / JavaScriptCore / heap / MarkingConstraint.cpp
1 /*
2  * Copyright (C) 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. AND ITS CONTRIBUTORS ``AS IS''
14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23  * THE POSSIBILITY OF SUCH DAMAGE.
24  */
25
26 #include "config.h"
27 #include "MarkingConstraint.h"
28
29 #include "JSCInlines.h"
30 #include "VisitCounter.h"
31
32 namespace JSC {
33
34 static constexpr bool verboseMarkingConstraint = false;
35
36 MarkingConstraint::MarkingConstraint(CString abbreviatedName, CString name, ConstraintVolatility volatility, ConstraintConcurrency concurrency, ConstraintParallelism parallelism)
37     : m_abbreviatedName(abbreviatedName)
38     , m_name(WTFMove(name))
39     , m_volatility(volatility)
40     , m_concurrency(concurrency)
41     , m_parallelism(parallelism)
42 {
43 }
44
45 MarkingConstraint::~MarkingConstraint()
46 {
47 }
48
49 void MarkingConstraint::resetStats()
50 {
51     m_lastVisitCount = 0;
52 }
53
54 ConstraintParallelism MarkingConstraint::execute(SlotVisitor& visitor)
55 {
56     VisitCounter visitCounter(visitor);
57     ConstraintParallelism result = executeImpl(visitor);
58     m_lastVisitCount += visitCounter.visitCount();
59     if (verboseMarkingConstraint && visitCounter.visitCount())
60         dataLog("(", abbreviatedName(), " visited ", visitCounter.visitCount(), " in execute)");
61     if (result == ConstraintParallelism::Parallel) {
62         // It's illegal to produce parallel work if you haven't advertised it upfront because the solver
63         // has optimizations for constraints that promise to never produce parallel work.
64         RELEASE_ASSERT(m_parallelism == ConstraintParallelism::Parallel);
65     }
66     return result;
67 }
68
69 double MarkingConstraint::quickWorkEstimate(SlotVisitor&)
70 {
71     return 0;
72 }
73
74 double MarkingConstraint::workEstimate(SlotVisitor& visitor)
75 {
76     return lastVisitCount() + quickWorkEstimate(visitor);
77 }
78
79 void MarkingConstraint::prepareToExecute(const AbstractLocker& constraintSolvingLocker, SlotVisitor& visitor)
80 {
81     if (Options::logGC())
82         dataLog(abbreviatedName());
83     VisitCounter visitCounter(visitor);
84     prepareToExecuteImpl(constraintSolvingLocker, visitor);
85     m_lastVisitCount = visitCounter.visitCount();
86     if (verboseMarkingConstraint && visitCounter.visitCount())
87         dataLog("(", abbreviatedName(), " visited ", visitCounter.visitCount(), " in prepareToExecute)");
88 }
89
90 void MarkingConstraint::doParallelWork(SlotVisitor& visitor)
91 {
92     VisitCounter visitCounter(visitor);
93     doParallelWorkImpl(visitor);
94     if (verboseMarkingConstraint && visitCounter.visitCount())
95         dataLog("(", abbreviatedName(), " visited ", visitCounter.visitCount(), " in doParallelWork)");
96     {
97         auto locker = holdLock(m_lock);
98         m_lastVisitCount += visitCounter.visitCount();
99     }
100 }
101
102 void MarkingConstraint::finishParallelWork(SlotVisitor& visitor)
103 {
104     VisitCounter visitCounter(visitor);
105     finishParallelWorkImpl(visitor);
106     m_lastVisitCount += visitCounter.visitCount();
107     if (verboseMarkingConstraint && visitCounter.visitCount())
108         dataLog("(", abbreviatedName(), " visited ", visitCounter.visitCount(), " in finishParallelWork)");
109 }
110
111 void MarkingConstraint::prepareToExecuteImpl(const AbstractLocker&, SlotVisitor&)
112 {
113 }
114
115 void MarkingConstraint::doParallelWorkImpl(SlotVisitor&)
116 {
117     UNREACHABLE_FOR_PLATFORM();
118 }
119
120 void MarkingConstraint::finishParallelWorkImpl(SlotVisitor&)
121 {
122 }
123
124 } // namespace JSC
125