1// Copyright 2012 the V8 project authors. All rights reserved.
2// Redistribution and use in source and binary forms, with or without
3// modification, are permitted provided that the following conditions are
4// met:
5//
6//     * Redistributions of source code must retain the above copyright
7//       notice, this list of conditions and the following disclaimer.
8//     * Redistributions in binary form must reproduce the above
9//       copyright notice, this list of conditions and the following
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11//       with the distribution.
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13//       contributors may be used to endorse or promote products derived
14//       from this software without specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28#include "elements-kind.h"
29
30#include "api.h"
31#include "elements.h"
32#include "objects.h"
33
34namespace v8 {
35namespace internal {
36
37
38const char* ElementsKindToString(ElementsKind kind) {
39  ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
40  return accessor->name();
41}
42
43
44void PrintElementsKind(FILE* out, ElementsKind kind) {
45  PrintF(out, "%s", ElementsKindToString(kind));
46}
47
48
49ElementsKind GetInitialFastElementsKind() {
50  if (FLAG_packed_arrays) {
51    return FAST_SMI_ELEMENTS;
52  } else {
53    return FAST_HOLEY_SMI_ELEMENTS;
54  }
55}
56
57
58struct InitializeFastElementsKindSequence {
59  static void Construct(
60      ElementsKind** fast_elements_kind_sequence_ptr) {
61    ElementsKind* fast_elements_kind_sequence =
62        new ElementsKind[kFastElementsKindCount];
63    *fast_elements_kind_sequence_ptr = fast_elements_kind_sequence;
64    STATIC_ASSERT(FAST_SMI_ELEMENTS == FIRST_FAST_ELEMENTS_KIND);
65    fast_elements_kind_sequence[0] = FAST_SMI_ELEMENTS;
66    fast_elements_kind_sequence[1] = FAST_HOLEY_SMI_ELEMENTS;
67    fast_elements_kind_sequence[2] = FAST_DOUBLE_ELEMENTS;
68    fast_elements_kind_sequence[3] = FAST_HOLEY_DOUBLE_ELEMENTS;
69    fast_elements_kind_sequence[4] = FAST_ELEMENTS;
70    fast_elements_kind_sequence[5] = FAST_HOLEY_ELEMENTS;
71  }
72};
73
74
75static LazyInstance<ElementsKind*,
76                    InitializeFastElementsKindSequence>::type
77    fast_elements_kind_sequence = LAZY_INSTANCE_INITIALIZER;
78
79
80ElementsKind GetFastElementsKindFromSequenceIndex(int sequence_number) {
81  ASSERT(sequence_number >= 0 &&
82         sequence_number < kFastElementsKindCount);
83  return fast_elements_kind_sequence.Get()[sequence_number];
84}
85
86
87int GetSequenceIndexFromFastElementsKind(ElementsKind elements_kind) {
88  for (int i = 0; i < kFastElementsKindCount; ++i) {
89    if (fast_elements_kind_sequence.Get()[i] == elements_kind) {
90      return i;
91    }
92  }
93  UNREACHABLE();
94  return 0;
95}
96
97
98ElementsKind GetNextMoreGeneralFastElementsKind(ElementsKind elements_kind,
99                                                bool allow_only_packed) {
100  ASSERT(IsFastElementsKind(elements_kind));
101  ASSERT(elements_kind != TERMINAL_FAST_ELEMENTS_KIND);
102  while (true) {
103    int index =
104        GetSequenceIndexFromFastElementsKind(elements_kind) + 1;
105    elements_kind = GetFastElementsKindFromSequenceIndex(index);
106    if (!IsFastHoleyElementsKind(elements_kind) || !allow_only_packed) {
107      return elements_kind;
108    }
109  }
110  UNREACHABLE();
111  return TERMINAL_FAST_ELEMENTS_KIND;
112}
113
114
115bool IsMoreGeneralElementsKindTransition(ElementsKind from_kind,
116                                         ElementsKind to_kind) {
117  switch (from_kind) {
118    case FAST_SMI_ELEMENTS:
119      return to_kind != FAST_SMI_ELEMENTS;
120    case FAST_HOLEY_SMI_ELEMENTS:
121      return to_kind != FAST_SMI_ELEMENTS &&
122          to_kind != FAST_HOLEY_SMI_ELEMENTS;
123    case FAST_DOUBLE_ELEMENTS:
124      return to_kind != FAST_SMI_ELEMENTS &&
125          to_kind != FAST_HOLEY_SMI_ELEMENTS &&
126          to_kind != FAST_DOUBLE_ELEMENTS;
127    case FAST_HOLEY_DOUBLE_ELEMENTS:
128      return to_kind == FAST_ELEMENTS ||
129          to_kind == FAST_HOLEY_ELEMENTS;
130    case FAST_ELEMENTS:
131      return to_kind == FAST_HOLEY_ELEMENTS;
132    case FAST_HOLEY_ELEMENTS:
133      return false;
134    default:
135      return false;
136  }
137}
138
139
140} }  // namespace v8::internal
141