Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2012 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/elements-kind.h" |
| 6 | |
| 7 | #include "src/api.h" |
| 8 | #include "src/base/lazy-instance.h" |
| 9 | #include "src/elements.h" |
| 10 | #include "src/objects.h" |
| 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | |
| 15 | |
| 16 | int ElementsKindToShiftSize(ElementsKind elements_kind) { |
| 17 | switch (elements_kind) { |
| 18 | case EXTERNAL_INT8_ELEMENTS: |
| 19 | case EXTERNAL_UINT8_CLAMPED_ELEMENTS: |
| 20 | case EXTERNAL_UINT8_ELEMENTS: |
| 21 | case UINT8_ELEMENTS: |
| 22 | case INT8_ELEMENTS: |
| 23 | case UINT8_CLAMPED_ELEMENTS: |
| 24 | return 0; |
| 25 | case EXTERNAL_INT16_ELEMENTS: |
| 26 | case EXTERNAL_UINT16_ELEMENTS: |
| 27 | case UINT16_ELEMENTS: |
| 28 | case INT16_ELEMENTS: |
| 29 | return 1; |
| 30 | case EXTERNAL_INT32_ELEMENTS: |
| 31 | case EXTERNAL_UINT32_ELEMENTS: |
| 32 | case EXTERNAL_FLOAT32_ELEMENTS: |
| 33 | case UINT32_ELEMENTS: |
| 34 | case INT32_ELEMENTS: |
| 35 | case FLOAT32_ELEMENTS: |
| 36 | return 2; |
| 37 | case EXTERNAL_FLOAT64_ELEMENTS: |
| 38 | case FAST_DOUBLE_ELEMENTS: |
| 39 | case FAST_HOLEY_DOUBLE_ELEMENTS: |
| 40 | case FLOAT64_ELEMENTS: |
| 41 | return 3; |
| 42 | case FAST_SMI_ELEMENTS: |
| 43 | case FAST_ELEMENTS: |
| 44 | case FAST_HOLEY_SMI_ELEMENTS: |
| 45 | case FAST_HOLEY_ELEMENTS: |
| 46 | case DICTIONARY_ELEMENTS: |
| 47 | case SLOPPY_ARGUMENTS_ELEMENTS: |
| 48 | return kPointerSizeLog2; |
| 49 | } |
| 50 | UNREACHABLE(); |
| 51 | return 0; |
| 52 | } |
| 53 | |
| 54 | |
| 55 | int GetDefaultHeaderSizeForElementsKind(ElementsKind elements_kind) { |
| 56 | STATIC_ASSERT(FixedArray::kHeaderSize == FixedDoubleArray::kHeaderSize); |
| 57 | return IsExternalArrayElementsKind(elements_kind) |
| 58 | ? 0 : (FixedArray::kHeaderSize - kHeapObjectTag); |
| 59 | } |
| 60 | |
| 61 | |
| 62 | const char* ElementsKindToString(ElementsKind kind) { |
| 63 | ElementsAccessor* accessor = ElementsAccessor::ForKind(kind); |
| 64 | return accessor->name(); |
| 65 | } |
| 66 | |
| 67 | |
| 68 | struct InitializeFastElementsKindSequence { |
| 69 | static void Construct( |
| 70 | ElementsKind** fast_elements_kind_sequence_ptr) { |
| 71 | ElementsKind* fast_elements_kind_sequence = |
| 72 | new ElementsKind[kFastElementsKindCount]; |
| 73 | *fast_elements_kind_sequence_ptr = fast_elements_kind_sequence; |
| 74 | STATIC_ASSERT(FAST_SMI_ELEMENTS == FIRST_FAST_ELEMENTS_KIND); |
| 75 | fast_elements_kind_sequence[0] = FAST_SMI_ELEMENTS; |
| 76 | fast_elements_kind_sequence[1] = FAST_HOLEY_SMI_ELEMENTS; |
| 77 | fast_elements_kind_sequence[2] = FAST_DOUBLE_ELEMENTS; |
| 78 | fast_elements_kind_sequence[3] = FAST_HOLEY_DOUBLE_ELEMENTS; |
| 79 | fast_elements_kind_sequence[4] = FAST_ELEMENTS; |
| 80 | fast_elements_kind_sequence[5] = FAST_HOLEY_ELEMENTS; |
| 81 | |
| 82 | // Verify that kFastElementsKindPackedToHoley is correct. |
| 83 | STATIC_ASSERT(FAST_SMI_ELEMENTS + kFastElementsKindPackedToHoley == |
| 84 | FAST_HOLEY_SMI_ELEMENTS); |
| 85 | STATIC_ASSERT(FAST_DOUBLE_ELEMENTS + kFastElementsKindPackedToHoley == |
| 86 | FAST_HOLEY_DOUBLE_ELEMENTS); |
| 87 | STATIC_ASSERT(FAST_ELEMENTS + kFastElementsKindPackedToHoley == |
| 88 | FAST_HOLEY_ELEMENTS); |
| 89 | } |
| 90 | }; |
| 91 | |
| 92 | |
| 93 | static base::LazyInstance<ElementsKind*, |
| 94 | InitializeFastElementsKindSequence>::type |
| 95 | fast_elements_kind_sequence = LAZY_INSTANCE_INITIALIZER; |
| 96 | |
| 97 | |
| 98 | ElementsKind GetFastElementsKindFromSequenceIndex(int sequence_number) { |
| 99 | DCHECK(sequence_number >= 0 && |
| 100 | sequence_number < kFastElementsKindCount); |
| 101 | return fast_elements_kind_sequence.Get()[sequence_number]; |
| 102 | } |
| 103 | |
| 104 | |
| 105 | int GetSequenceIndexFromFastElementsKind(ElementsKind elements_kind) { |
| 106 | for (int i = 0; i < kFastElementsKindCount; ++i) { |
| 107 | if (fast_elements_kind_sequence.Get()[i] == elements_kind) { |
| 108 | return i; |
| 109 | } |
| 110 | } |
| 111 | UNREACHABLE(); |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | |
| 116 | ElementsKind GetNextTransitionElementsKind(ElementsKind kind) { |
| 117 | switch (kind) { |
| 118 | #define FIXED_TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size) \ |
| 119 | case TYPE##_ELEMENTS: return EXTERNAL_##TYPE##_ELEMENTS; |
| 120 | |
| 121 | TYPED_ARRAYS(FIXED_TYPED_ARRAY_CASE) |
| 122 | #undef FIXED_TYPED_ARRAY_CASE |
| 123 | default: { |
| 124 | int index = GetSequenceIndexFromFastElementsKind(kind); |
| 125 | return GetFastElementsKindFromSequenceIndex(index + 1); |
| 126 | } |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | |
| 131 | ElementsKind GetNextMoreGeneralFastElementsKind(ElementsKind elements_kind, |
| 132 | bool allow_only_packed) { |
| 133 | DCHECK(IsFastElementsKind(elements_kind)); |
| 134 | DCHECK(elements_kind != TERMINAL_FAST_ELEMENTS_KIND); |
| 135 | while (true) { |
| 136 | elements_kind = GetNextTransitionElementsKind(elements_kind); |
| 137 | if (!IsFastHoleyElementsKind(elements_kind) || !allow_only_packed) { |
| 138 | return elements_kind; |
| 139 | } |
| 140 | } |
| 141 | UNREACHABLE(); |
| 142 | return TERMINAL_FAST_ELEMENTS_KIND; |
| 143 | } |
| 144 | |
| 145 | |
| 146 | static bool IsTypedArrayElementsKind(ElementsKind elements_kind) { |
| 147 | return IsFixedTypedArrayElementsKind(elements_kind) || |
| 148 | IsExternalArrayElementsKind(elements_kind); |
| 149 | } |
| 150 | |
| 151 | |
| 152 | static inline bool IsFastTransitionTarget(ElementsKind elements_kind) { |
| 153 | return IsFastElementsKind(elements_kind) || |
| 154 | elements_kind == DICTIONARY_ELEMENTS; |
| 155 | } |
| 156 | |
| 157 | bool IsMoreGeneralElementsKindTransition(ElementsKind from_kind, |
| 158 | ElementsKind to_kind) { |
| 159 | if (IsTypedArrayElementsKind(from_kind) || |
| 160 | IsTypedArrayElementsKind(to_kind)) { |
| 161 | switch (from_kind) { |
| 162 | #define FIXED_TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size) \ |
| 163 | case TYPE##_ELEMENTS: \ |
| 164 | return to_kind == EXTERNAL_##TYPE##_ELEMENTS; |
| 165 | |
| 166 | TYPED_ARRAYS(FIXED_TYPED_ARRAY_CASE); |
| 167 | #undef FIXED_TYPED_ARRAY_CASE |
| 168 | default: |
| 169 | return false; |
| 170 | } |
| 171 | } |
| 172 | if (IsFastElementsKind(from_kind) && IsFastTransitionTarget(to_kind)) { |
| 173 | switch (from_kind) { |
| 174 | case FAST_SMI_ELEMENTS: |
| 175 | return to_kind != FAST_SMI_ELEMENTS; |
| 176 | case FAST_HOLEY_SMI_ELEMENTS: |
| 177 | return to_kind != FAST_SMI_ELEMENTS && |
| 178 | to_kind != FAST_HOLEY_SMI_ELEMENTS; |
| 179 | case FAST_DOUBLE_ELEMENTS: |
| 180 | return to_kind != FAST_SMI_ELEMENTS && |
| 181 | to_kind != FAST_HOLEY_SMI_ELEMENTS && |
| 182 | to_kind != FAST_DOUBLE_ELEMENTS; |
| 183 | case FAST_HOLEY_DOUBLE_ELEMENTS: |
| 184 | return to_kind == FAST_ELEMENTS || |
| 185 | to_kind == FAST_HOLEY_ELEMENTS; |
| 186 | case FAST_ELEMENTS: |
| 187 | return to_kind == FAST_HOLEY_ELEMENTS; |
| 188 | case FAST_HOLEY_ELEMENTS: |
| 189 | return false; |
| 190 | default: |
| 191 | return false; |
| 192 | } |
| 193 | } |
| 194 | return false; |
| 195 | } |
| 196 | |
| 197 | |
| 198 | } } // namespace v8::internal |