Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 1 | // Copyright 2011 the V8 project authors. All rights reserved. |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 4 | |
| 5 | #ifndef V8_SMALL_POINTER_LIST_H_ |
| 6 | #define V8_SMALL_POINTER_LIST_H_ |
| 7 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 8 | #include "src/base/logging.h" |
| 9 | #include "src/globals.h" |
| 10 | #include "src/zone.h" |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | |
| 15 | // SmallPointerList is a list optimized for storing no or just a |
| 16 | // single value. When more values are given it falls back to ZoneList. |
| 17 | // |
| 18 | // The interface tries to be as close to List from list.h as possible. |
| 19 | template <typename T> |
| 20 | class SmallPointerList { |
| 21 | public: |
| 22 | SmallPointerList() : data_(kEmptyTag) {} |
| 23 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 24 | SmallPointerList(int capacity, Zone* zone) : data_(kEmptyTag) { |
| 25 | Reserve(capacity, zone); |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 26 | } |
| 27 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 28 | void Reserve(int capacity, Zone* zone) { |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 29 | if (capacity < 2) return; |
| 30 | if ((data_ & kTagMask) == kListTag) { |
| 31 | if (list()->capacity() >= capacity) return; |
| 32 | int old_length = list()->length(); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 33 | list()->AddBlock(NULL, capacity - list()->capacity(), zone); |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 34 | list()->Rewind(old_length); |
| 35 | return; |
| 36 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 37 | PointerList* list = new(zone) PointerList(capacity, zone); |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 38 | if ((data_ & kTagMask) == kSingletonTag) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 39 | list->Add(single_value(), zone); |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 40 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 41 | DCHECK(IsAligned(reinterpret_cast<intptr_t>(list), kPointerAlignment)); |
Ben Murdoch | 69a99ed | 2011-11-30 16:03:39 +0000 | [diff] [blame] | 42 | data_ = reinterpret_cast<intptr_t>(list) | kListTag; |
| 43 | } |
| 44 | |
| 45 | void Clear() { |
| 46 | data_ = kEmptyTag; |
| 47 | } |
| 48 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 49 | void Sort() { |
| 50 | if ((data_ & kTagMask) == kListTag) { |
| 51 | list()->Sort(compare_value); |
| 52 | } |
| 53 | } |
| 54 | |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 55 | bool is_empty() const { return length() == 0; } |
| 56 | |
| 57 | int length() const { |
| 58 | if ((data_ & kTagMask) == kEmptyTag) return 0; |
| 59 | if ((data_ & kTagMask) == kSingletonTag) return 1; |
| 60 | return list()->length(); |
| 61 | } |
| 62 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 63 | void Add(T* pointer, Zone* zone) { |
| 64 | DCHECK(IsAligned(reinterpret_cast<intptr_t>(pointer), kPointerAlignment)); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 65 | if ((data_ & kTagMask) == kEmptyTag) { |
| 66 | data_ = reinterpret_cast<intptr_t>(pointer) | kSingletonTag; |
| 67 | return; |
| 68 | } |
| 69 | if ((data_ & kTagMask) == kSingletonTag) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 70 | PointerList* list = new(zone) PointerList(2, zone); |
| 71 | list->Add(single_value(), zone); |
| 72 | list->Add(pointer, zone); |
| 73 | DCHECK(IsAligned(reinterpret_cast<intptr_t>(list), kPointerAlignment)); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 74 | data_ = reinterpret_cast<intptr_t>(list) | kListTag; |
| 75 | return; |
| 76 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 77 | list()->Add(pointer, zone); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 78 | } |
| 79 | |
| 80 | // Note: returns T* and not T*& (unlike List from list.h). |
| 81 | // This makes the implementation simpler and more const correct. |
| 82 | T* at(int i) const { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 83 | DCHECK((data_ & kTagMask) != kEmptyTag); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 84 | if ((data_ & kTagMask) == kSingletonTag) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 85 | DCHECK(i == 0); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 86 | return single_value(); |
| 87 | } |
| 88 | return list()->at(i); |
| 89 | } |
| 90 | |
| 91 | // See the note above. |
| 92 | T* operator[](int i) const { return at(i); } |
| 93 | |
| 94 | // Remove the given element from the list (if present). |
| 95 | void RemoveElement(T* pointer) { |
| 96 | if ((data_ & kTagMask) == kEmptyTag) return; |
| 97 | if ((data_ & kTagMask) == kSingletonTag) { |
| 98 | if (pointer == single_value()) { |
| 99 | data_ = kEmptyTag; |
| 100 | } |
| 101 | return; |
| 102 | } |
| 103 | list()->RemoveElement(pointer); |
| 104 | } |
| 105 | |
| 106 | T* RemoveLast() { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 107 | DCHECK((data_ & kTagMask) != kEmptyTag); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 108 | if ((data_ & kTagMask) == kSingletonTag) { |
| 109 | T* result = single_value(); |
| 110 | data_ = kEmptyTag; |
| 111 | return result; |
| 112 | } |
| 113 | return list()->RemoveLast(); |
| 114 | } |
| 115 | |
| 116 | void Rewind(int pos) { |
| 117 | if ((data_ & kTagMask) == kEmptyTag) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 118 | DCHECK(pos == 0); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 119 | return; |
| 120 | } |
| 121 | if ((data_ & kTagMask) == kSingletonTag) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 122 | DCHECK(pos == 0 || pos == 1); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 123 | if (pos == 0) { |
| 124 | data_ = kEmptyTag; |
| 125 | } |
| 126 | return; |
| 127 | } |
| 128 | list()->Rewind(pos); |
| 129 | } |
| 130 | |
| 131 | int CountOccurrences(T* pointer, int start, int end) const { |
| 132 | if ((data_ & kTagMask) == kEmptyTag) return 0; |
| 133 | if ((data_ & kTagMask) == kSingletonTag) { |
| 134 | if (start == 0 && end >= 0) { |
| 135 | return (single_value() == pointer) ? 1 : 0; |
| 136 | } |
| 137 | return 0; |
| 138 | } |
| 139 | return list()->CountOccurrences(pointer, start, end); |
| 140 | } |
| 141 | |
| 142 | private: |
| 143 | typedef ZoneList<T*> PointerList; |
| 144 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 145 | static int compare_value(T* const* a, T* const* b) { |
| 146 | return Compare<T>(**a, **b); |
| 147 | } |
| 148 | |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 149 | static const intptr_t kEmptyTag = 1; |
| 150 | static const intptr_t kSingletonTag = 0; |
| 151 | static const intptr_t kListTag = 2; |
| 152 | static const intptr_t kTagMask = 3; |
| 153 | static const intptr_t kValueMask = ~kTagMask; |
| 154 | |
| 155 | STATIC_ASSERT(kTagMask + 1 <= kPointerAlignment); |
| 156 | |
| 157 | T* single_value() const { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 158 | DCHECK((data_ & kTagMask) == kSingletonTag); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 159 | STATIC_ASSERT(kSingletonTag == 0); |
| 160 | return reinterpret_cast<T*>(data_); |
| 161 | } |
| 162 | |
| 163 | PointerList* list() const { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 164 | DCHECK((data_ & kTagMask) == kListTag); |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 165 | return reinterpret_cast<PointerList*>(data_ & kValueMask); |
| 166 | } |
| 167 | |
| 168 | intptr_t data_; |
| 169 | |
| 170 | DISALLOW_COPY_AND_ASSIGN(SmallPointerList); |
| 171 | }; |
| 172 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 173 | } // namespace internal |
| 174 | } // namespace v8 |
Steve Block | 44f0eee | 2011-05-26 01:26:41 +0100 | [diff] [blame] | 175 | |
| 176 | #endif // V8_SMALL_POINTER_LIST_H_ |