1 //===- llvm/ADT/DenseMapInfo.h - Type traits for DenseMap -------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines DenseMapInfo traits for DenseMap.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_ADT_DENSEMAPINFO_H
14 #define LLVM_ADT_DENSEMAPINFO_H
15
16 #include "llvm/ADT/Hashing.h"
17 #include <cassert>
18 #include <cstddef>
19 #include <cstdint>
20 #include <utility>
21
22 namespace llvm {
23
24 namespace detail {
25
26 /// Simplistic combination of 32-bit hash values into 32-bit hash values.
combineHashValue(unsigned a,unsigned b)27 static inline unsigned combineHashValue(unsigned a, unsigned b) {
28 uint64_t key = (uint64_t)a << 32 | (uint64_t)b;
29 key += ~(key << 32);
30 key ^= (key >> 22);
31 key += ~(key << 13);
32 key ^= (key >> 8);
33 key += (key << 3);
34 key ^= (key >> 15);
35 key += ~(key << 27);
36 key ^= (key >> 31);
37 return (unsigned)key;
38 }
39
40 } // end namespace detail
41
42 template<typename T>
43 struct DenseMapInfo {
44 //static inline T getEmptyKey();
45 //static inline T getTombstoneKey();
46 //static unsigned getHashValue(const T &Val);
47 //static bool isEqual(const T &LHS, const T &RHS);
48 };
49
50 // Provide DenseMapInfo for all pointers. Come up with sentinel pointer values
51 // that are aligned to alignof(T) bytes, but try to avoid requiring T to be
52 // complete. This allows clients to instantiate DenseMap<T*, ...> with forward
53 // declared key types. Assume that no pointer key type requires more than 4096
54 // bytes of alignment.
55 template<typename T>
56 struct DenseMapInfo<T*> {
57 // The following should hold, but it would require T to be complete:
58 // static_assert(alignof(T) <= (1 << Log2MaxAlign),
59 // "DenseMap does not support pointer keys requiring more than "
60 // "Log2MaxAlign bits of alignment");
61 static constexpr uintptr_t Log2MaxAlign = 12;
62
63 static inline T* getEmptyKey() {
64 uintptr_t Val = static_cast<uintptr_t>(-1);
65 Val <<= Log2MaxAlign;
66 return reinterpret_cast<T*>(Val);
67 }
68
69 static inline T* getTombstoneKey() {
70 uintptr_t Val = static_cast<uintptr_t>(-2);
71 Val <<= Log2MaxAlign;
72 return reinterpret_cast<T*>(Val);
73 }
74
75 static unsigned getHashValue(const T *PtrVal) {
76 return (unsigned((uintptr_t)PtrVal) >> 4) ^
77 (unsigned((uintptr_t)PtrVal) >> 9);
78 }
79
80 static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
81 };
82
83 // Provide DenseMapInfo for chars.
84 template<> struct DenseMapInfo<char> {
85 static inline char getEmptyKey() { return ~0; }
86 static inline char getTombstoneKey() { return ~0 - 1; }
87 static unsigned getHashValue(const char& Val) { return Val * 37U; }
88
89 static bool isEqual(const char &LHS, const char &RHS) {
90 return LHS == RHS;
91 }
92 };
93
94 // Provide DenseMapInfo for unsigned chars.
95 template <> struct DenseMapInfo<unsigned char> {
96 static inline unsigned char getEmptyKey() { return ~0; }
97 static inline unsigned char getTombstoneKey() { return ~0 - 1; }
98 static unsigned getHashValue(const unsigned char &Val) { return Val * 37U; }
99
100 static bool isEqual(const unsigned char &LHS, const unsigned char &RHS) {
101 return LHS == RHS;
102 }
103 };
104
105 // Provide DenseMapInfo for unsigned shorts.
106 template <> struct DenseMapInfo<unsigned short> {
107 static inline unsigned short getEmptyKey() { return 0xFFFF; }
108 static inline unsigned short getTombstoneKey() { return 0xFFFF - 1; }
109 static unsigned getHashValue(const unsigned short &Val) { return Val * 37U; }
110
111 static bool isEqual(const unsigned short &LHS, const unsigned short &RHS) {
112 return LHS == RHS;
113 }
114 };
115
116 // Provide DenseMapInfo for unsigned ints.
117 template<> struct DenseMapInfo<unsigned> {
118 static inline unsigned getEmptyKey() { return ~0U; }
119 static inline unsigned getTombstoneKey() { return ~0U - 1; }
120 static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
121
122 static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
123 return LHS == RHS;
124 }
125 };
126
127 // Provide DenseMapInfo for unsigned longs.
128 template<> struct DenseMapInfo<unsigned long> {
129 static inline unsigned long getEmptyKey() { return ~0UL; }
130 static inline unsigned long getTombstoneKey() { return ~0UL - 1L; }
131
132 static unsigned getHashValue(const unsigned long& Val) {
133 return (unsigned)(Val * 37UL);
134 }
135
136 static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
137 return LHS == RHS;
138 }
139 };
140
141 // Provide DenseMapInfo for unsigned long longs.
142 template<> struct DenseMapInfo<unsigned long long> {
143 static inline unsigned long long getEmptyKey() { return ~0ULL; }
144 static inline unsigned long long getTombstoneKey() { return ~0ULL - 1ULL; }
145
146 static unsigned getHashValue(const unsigned long long& Val) {
147 return (unsigned)(Val * 37ULL);
148 }
149
150 static bool isEqual(const unsigned long long& LHS,
151 const unsigned long long& RHS) {
152 return LHS == RHS;
153 }
154 };
155
156 // Provide DenseMapInfo for shorts.
157 template <> struct DenseMapInfo<short> {
158 static inline short getEmptyKey() { return 0x7FFF; }
159 static inline short getTombstoneKey() { return -0x7FFF - 1; }
160 static unsigned getHashValue(const short &Val) { return Val * 37U; }
161 static bool isEqual(const short &LHS, const short &RHS) { return LHS == RHS; }
162 };
163
164 // Provide DenseMapInfo for ints.
165 template<> struct DenseMapInfo<int> {
166 static inline int getEmptyKey() { return 0x7fffffff; }
167 static inline int getTombstoneKey() { return -0x7fffffff - 1; }
168 static unsigned getHashValue(const int& Val) { return (unsigned)(Val * 37U); }
169
170 static bool isEqual(const int& LHS, const int& RHS) {
171 return LHS == RHS;
172 }
173 };
174
175 // Provide DenseMapInfo for longs.
176 template<> struct DenseMapInfo<long> {
177 static inline long getEmptyKey() {
178 return (1UL << (sizeof(long) * 8 - 1)) - 1UL;
179 }
180
181 static inline long getTombstoneKey() { return getEmptyKey() - 1L; }
182
183 static unsigned getHashValue(const long& Val) {
184 return (unsigned)(Val * 37UL);
185 }
186
187 static bool isEqual(const long& LHS, const long& RHS) {
188 return LHS == RHS;
189 }
190 };
191
192 // Provide DenseMapInfo for long longs.
193 template<> struct DenseMapInfo<long long> {
194 static inline long long getEmptyKey() { return 0x7fffffffffffffffLL; }
195 static inline long long getTombstoneKey() { return -0x7fffffffffffffffLL-1; }
196
197 static unsigned getHashValue(const long long& Val) {
198 return (unsigned)(Val * 37ULL);
199 }
200
201 static bool isEqual(const long long& LHS,
202 const long long& RHS) {
203 return LHS == RHS;
204 }
205 };
206
207 // Provide DenseMapInfo for all pairs whose members have info.
208 template<typename T, typename U>
209 struct DenseMapInfo<std::pair<T, U>> {
210 using Pair = std::pair<T, U>;
211 using FirstInfo = DenseMapInfo<T>;
212 using SecondInfo = DenseMapInfo<U>;
213
214 static inline Pair getEmptyKey() {
215 return std::make_pair(FirstInfo::getEmptyKey(),
216 SecondInfo::getEmptyKey());
217 }
218
219 static inline Pair getTombstoneKey() {
220 return std::make_pair(FirstInfo::getTombstoneKey(),
221 SecondInfo::getTombstoneKey());
222 }
223
224 static unsigned getHashValue(const Pair& PairVal) {
225 return detail::combineHashValue(FirstInfo::getHashValue(PairVal.first),
226 SecondInfo::getHashValue(PairVal.second));
227 }
228
229 static bool isEqual(const Pair &LHS, const Pair &RHS) {
230 return FirstInfo::isEqual(LHS.first, RHS.first) &&
231 SecondInfo::isEqual(LHS.second, RHS.second);
232 }
233 };
234
235 // Provide DenseMapInfo for all tuples whose members have info.
236 template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
237 using Tuple = std::tuple<Ts...>;
238
239 static inline Tuple getEmptyKey() {
240 return Tuple(DenseMapInfo<Ts>::getEmptyKey()...);
241 }
242
243 static inline Tuple getTombstoneKey() {
244 return Tuple(DenseMapInfo<Ts>::getTombstoneKey()...);
245 }
246
247 template <unsigned I>
248 static unsigned getHashValueImpl(const Tuple &values, std::false_type) {
249 using EltType = typename std::tuple_element<I, Tuple>::type;
250 std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
251 return detail::combineHashValue(
252 DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
253 getHashValueImpl<I + 1>(values, atEnd));
254 }
255
256 template <unsigned I>
257 static unsigned getHashValueImpl(const Tuple &, std::true_type) {
258 return 0;
259 }
260
261 static unsigned getHashValue(const std::tuple<Ts...> &values) {
262 std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
263 return getHashValueImpl<0>(values, atEnd);
264 }
265
266 template <unsigned I>
267 static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::false_type) {
268 using EltType = typename std::tuple_element<I, Tuple>::type;
269 std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
270 return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs), std::get<I>(rhs)) &&
271 isEqualImpl<I + 1>(lhs, rhs, atEnd);
272 }
273
274 template <unsigned I>
275 static bool isEqualImpl(const Tuple &, const Tuple &, std::true_type) {
276 return true;
277 }
278
279 static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
280 std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
281 return isEqualImpl<0>(lhs, rhs, atEnd);
282 }
283 };
284
285 template <> struct DenseMapInfo<hash_code> {
286 static inline hash_code getEmptyKey() { return hash_code(-1); }
287 static inline hash_code getTombstoneKey() { return hash_code(-2); }
288 static unsigned getHashValue(hash_code val) { return val; }
289 static bool isEqual(hash_code LHS, hash_code RHS) { return LHS == RHS; }
290 };
291
292 } // end namespace llvm
293
294 #endif // LLVM_ADT_DENSEMAPINFO_H
295