1/*
2 * Copyright (C) 2012, 2013 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 "IndexingType.h"
29#include "JSArray.h"
30
31namespace JSC {
32
33class ArrayAllocationProfile {
34public:
35 ArrayAllocationProfile() = default;
36
37 ArrayAllocationProfile(IndexingType recommendedIndexingMode)
38 {
39 initializeIndexingMode(recommendedIndexingMode);
40 }
41
42 IndexingType selectIndexingType()
43 {
44 JSArray* lastArray = m_lastArray;
45 if (lastArray && UNLIKELY(lastArray->indexingType() != m_currentIndexingType))
46 updateProfile();
47 return m_currentIndexingType;
48 }
49
50 // vector length hint becomes [0, BASE_CONTIGUOUS_VECTOR_LEN_MAX].
51 unsigned vectorLengthHint()
52 {
53 JSArray* lastArray = m_lastArray;
54 if (lastArray && (m_largestSeenVectorLength != BASE_CONTIGUOUS_VECTOR_LEN_MAX) && UNLIKELY(lastArray->getVectorLength() > m_largestSeenVectorLength))
55 updateProfile();
56 return m_largestSeenVectorLength;
57 }
58
59 JSArray* updateLastAllocation(JSArray* lastArray)
60 {
61 m_lastArray = lastArray;
62 return lastArray;
63 }
64
65 JS_EXPORT_PRIVATE void updateProfile();
66
67 static IndexingType selectIndexingTypeFor(ArrayAllocationProfile* profile)
68 {
69 if (!profile)
70 return ArrayWithUndecided;
71 return profile->selectIndexingType();
72 }
73
74 static JSArray* updateLastAllocationFor(ArrayAllocationProfile* profile, JSArray* lastArray)
75 {
76 if (profile)
77 profile->updateLastAllocation(lastArray);
78 return lastArray;
79 }
80
81 void initializeIndexingMode(IndexingType recommendedIndexingMode) { m_currentIndexingType = recommendedIndexingMode; }
82
83private:
84
85 IndexingType m_currentIndexingType { ArrayWithUndecided };
86 unsigned m_largestSeenVectorLength { 0 };
87 JSArray* m_lastArray { nullptr };
88};
89
90} // namespace JSC
91