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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 : /// \file
10 : /// This file defines DenseMapInfo traits for DenseMap.
11 : ///
12 : //===----------------------------------------------------------------------===//
13 :
14 : #ifndef LLVM_ADT_DENSEMAPINFO_H
15 : #define LLVM_ADT_DENSEMAPINFO_H
16 :
17 : #include <cassert>
18 : #include <cstddef>
19 : #include <cstdint>
20 : #include <tuple>
21 : #include <type_traits>
22 : #include <utility>
23 :
24 : namespace llvm {
25 :
26 : namespace densemap::detail {
27 : // A bit mixer with very low latency using one multiplications and one
28 : // xor-shift. The constant is from splitmix64.
29 : inline uint64_t mix(uint64_t x) {
30 : x *= 0xbf58476d1ce4e5b9u;
31 : x ^= x >> 31;
32 : return x;
33 : }
34 : } // namespace densemap::detail
35 :
36 : namespace detail {
37 :
38 : /// Simplistic combination of 32-bit hash values into 32-bit hash values.
39 : inline unsigned combineHashValue(unsigned a, unsigned b) {
40 : uint64_t x = (uint64_t)a << 32 | (uint64_t)b;
41 : return (unsigned)densemap::detail::mix(x);
42 : }
43 :
44 : } // end namespace detail
45 :
46 : /// An information struct used to provide DenseMap with the various necessary
47 : /// components for a given value type `T`. `Enable` is an optional additional
48 : /// parameter that is used to support SFINAE (generally using std::enable_if_t)
49 : /// in derived DenseMapInfo specializations; in non-SFINAE use cases this should
50 : /// just be `void`.
51 : template<typename T, typename Enable = void>
52 : struct DenseMapInfo {
53 : //static inline T getEmptyKey();
54 : //static inline T getTombstoneKey();
55 : //static unsigned getHashValue(const T &Val);
56 : //static bool isEqual(const T &LHS, const T &RHS);
57 : };
58 :
59 : // Provide DenseMapInfo for all pointers. Come up with sentinel pointer values
60 : // that are aligned to alignof(T) bytes, but try to avoid requiring T to be
61 : // complete. This allows clients to instantiate DenseMap<T*, ...> with forward
62 : // declared key types. Assume that no pointer key type requires more than 4096
63 : // bytes of alignment.
64 : template<typename T>
65 : struct DenseMapInfo<T*> {
66 : // The following should hold, but it would require T to be complete:
67 : // static_assert(alignof(T) <= (1 << Log2MaxAlign),
68 : // "DenseMap does not support pointer keys requiring more than "
69 : // "Log2MaxAlign bits of alignment");
70 : static constexpr uintptr_t Log2MaxAlign = 12;
71 :
72 6368 : static inline T* getEmptyKey() {
73 6368 : uintptr_t Val = static_cast<uintptr_t>(-1);
74 6368 : Val <<= Log2MaxAlign;
75 6368 : return reinterpret_cast<T*>(Val);
76 : }
77 :
78 3238 : static inline T* getTombstoneKey() {
79 3238 : uintptr_t Val = static_cast<uintptr_t>(-2);
80 3238 : Val <<= Log2MaxAlign;
81 3238 : return reinterpret_cast<T*>(Val);
82 : }
83 :
84 2132 : static unsigned getHashValue(const T *PtrVal) {
85 2132 : return (unsigned((uintptr_t)PtrVal) >> 4) ^
86 2132 : (unsigned((uintptr_t)PtrVal) >> 9);
87 : }
88 :
89 84429 : static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
90 : };
91 :
92 : // Provide DenseMapInfo for chars.
93 : template<> struct DenseMapInfo<char> {
94 : static inline char getEmptyKey() { return ~0; }
95 : static inline char getTombstoneKey() { return ~0 - 1; }
96 : static unsigned getHashValue(const char& Val) { return Val * 37U; }
97 :
98 : static bool isEqual(const char &LHS, const char &RHS) {
99 : return LHS == RHS;
100 : }
101 : };
102 :
103 : // Provide DenseMapInfo for unsigned chars.
104 : template <> struct DenseMapInfo<unsigned char> {
105 : static inline unsigned char getEmptyKey() { return ~0; }
106 : static inline unsigned char getTombstoneKey() { return ~0 - 1; }
107 : static unsigned getHashValue(const unsigned char &Val) { return Val * 37U; }
108 :
109 : static bool isEqual(const unsigned char &LHS, const unsigned char &RHS) {
110 : return LHS == RHS;
111 : }
112 : };
113 :
114 : // Provide DenseMapInfo for unsigned shorts.
115 : template <> struct DenseMapInfo<unsigned short> {
116 : static inline unsigned short getEmptyKey() { return 0xFFFF; }
117 : static inline unsigned short getTombstoneKey() { return 0xFFFF - 1; }
118 : static unsigned getHashValue(const unsigned short &Val) { return Val * 37U; }
119 :
120 : static bool isEqual(const unsigned short &LHS, const unsigned short &RHS) {
121 : return LHS == RHS;
122 : }
123 : };
124 :
125 : // Provide DenseMapInfo for unsigned ints.
126 : template<> struct DenseMapInfo<unsigned> {
127 : static inline unsigned getEmptyKey() { return ~0U; }
128 : static inline unsigned getTombstoneKey() { return ~0U - 1; }
129 : static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
130 :
131 : static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
132 : return LHS == RHS;
133 : }
134 : };
135 :
136 : // Provide DenseMapInfo for unsigned longs.
137 : template<> struct DenseMapInfo<unsigned long> {
138 0 : static inline unsigned long getEmptyKey() { return ~0UL; }
139 0 : static inline unsigned long getTombstoneKey() { return ~0UL - 1L; }
140 :
141 : static unsigned getHashValue(const unsigned long& Val) {
142 : if constexpr (sizeof(Val) == 4)
143 : return DenseMapInfo<unsigned>::getHashValue(Val);
144 : else
145 : return densemap::detail::mix(Val);
146 : }
147 :
148 0 : static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
149 0 : return LHS == RHS;
150 : }
151 : };
152 :
153 : // Provide DenseMapInfo for unsigned long longs.
154 : template<> struct DenseMapInfo<unsigned long long> {
155 : static inline unsigned long long getEmptyKey() { return ~0ULL; }
156 : static inline unsigned long long getTombstoneKey() { return ~0ULL - 1ULL; }
157 :
158 : static unsigned getHashValue(const unsigned long long& Val) {
159 : return densemap::detail::mix(Val);
160 : }
161 :
162 : static bool isEqual(const unsigned long long& LHS,
163 : const unsigned long long& RHS) {
164 : return LHS == RHS;
165 : }
166 : };
167 :
168 : // Provide DenseMapInfo for shorts.
169 : template <> struct DenseMapInfo<short> {
170 : static inline short getEmptyKey() { return 0x7FFF; }
171 : static inline short getTombstoneKey() { return -0x7FFF - 1; }
172 : static unsigned getHashValue(const short &Val) { return Val * 37U; }
173 : static bool isEqual(const short &LHS, const short &RHS) { return LHS == RHS; }
174 : };
175 :
176 : // Provide DenseMapInfo for ints.
177 : template<> struct DenseMapInfo<int> {
178 : static inline int getEmptyKey() { return 0x7fffffff; }
179 : static inline int getTombstoneKey() { return -0x7fffffff - 1; }
180 : static unsigned getHashValue(const int& Val) { return (unsigned)(Val * 37U); }
181 :
182 : static bool isEqual(const int& LHS, const int& RHS) {
183 : return LHS == RHS;
184 : }
185 : };
186 :
187 : // Provide DenseMapInfo for longs.
188 : template<> struct DenseMapInfo<long> {
189 : static inline long getEmptyKey() {
190 : return (1UL << (sizeof(long) * 8 - 1)) - 1UL;
191 : }
192 :
193 : static inline long getTombstoneKey() { return getEmptyKey() - 1L; }
194 :
195 : static unsigned getHashValue(const long& Val) {
196 : return (unsigned)(Val * 37UL);
197 : }
198 :
199 : static bool isEqual(const long& LHS, const long& RHS) {
200 : return LHS == RHS;
201 : }
202 : };
203 :
204 : // Provide DenseMapInfo for long longs.
205 : template<> struct DenseMapInfo<long long> {
206 : static inline long long getEmptyKey() { return 0x7fffffffffffffffLL; }
207 : static inline long long getTombstoneKey() { return -0x7fffffffffffffffLL-1; }
208 :
209 : static unsigned getHashValue(const long long& Val) {
210 : return (unsigned)(Val * 37ULL);
211 : }
212 :
213 : static bool isEqual(const long long& LHS,
214 : const long long& RHS) {
215 : return LHS == RHS;
216 : }
217 : };
218 :
219 : // Provide DenseMapInfo for all pairs whose members have info.
220 : template<typename T, typename U>
221 : struct DenseMapInfo<std::pair<T, U>> {
222 : using Pair = std::pair<T, U>;
223 : using FirstInfo = DenseMapInfo<T>;
224 : using SecondInfo = DenseMapInfo<U>;
225 :
226 : static inline Pair getEmptyKey() {
227 : return std::make_pair(FirstInfo::getEmptyKey(),
228 : SecondInfo::getEmptyKey());
229 : }
230 :
231 : static inline Pair getTombstoneKey() {
232 : return std::make_pair(FirstInfo::getTombstoneKey(),
233 : SecondInfo::getTombstoneKey());
234 : }
235 :
236 : static unsigned getHashValue(const Pair& PairVal) {
237 : return detail::combineHashValue(FirstInfo::getHashValue(PairVal.first),
238 : SecondInfo::getHashValue(PairVal.second));
239 : }
240 :
241 : // Expose an additional function intended to be used by other
242 : // specializations of DenseMapInfo without needing to know how
243 : // to combine hash values manually
244 : static unsigned getHashValuePiecewise(const T &First, const U &Second) {
245 : return detail::combineHashValue(FirstInfo::getHashValue(First),
246 : SecondInfo::getHashValue(Second));
247 : }
248 :
249 : static bool isEqual(const Pair &LHS, const Pair &RHS) {
250 : return FirstInfo::isEqual(LHS.first, RHS.first) &&
251 : SecondInfo::isEqual(LHS.second, RHS.second);
252 : }
253 : };
254 :
255 : // Provide DenseMapInfo for all tuples whose members have info.
256 : template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
257 : using Tuple = std::tuple<Ts...>;
258 :
259 : static inline Tuple getEmptyKey() {
260 : return Tuple(DenseMapInfo<Ts>::getEmptyKey()...);
261 : }
262 :
263 : static inline Tuple getTombstoneKey() {
264 : return Tuple(DenseMapInfo<Ts>::getTombstoneKey()...);
265 : }
266 :
267 : template <unsigned I>
268 : static unsigned getHashValueImpl(const Tuple &values, std::false_type) {
269 : using EltType = std::tuple_element_t<I, Tuple>;
270 : std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
271 : return detail::combineHashValue(
272 : DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
273 : getHashValueImpl<I + 1>(values, atEnd));
274 : }
275 :
276 : template <unsigned I>
277 : static unsigned getHashValueImpl(const Tuple &, std::true_type) {
278 : return 0;
279 : }
280 :
281 : static unsigned getHashValue(const std::tuple<Ts...> &values) {
282 : std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
283 : return getHashValueImpl<0>(values, atEnd);
284 : }
285 :
286 : template <unsigned I>
287 : static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::false_type) {
288 : using EltType = std::tuple_element_t<I, Tuple>;
289 : std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
290 : return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs), std::get<I>(rhs)) &&
291 : isEqualImpl<I + 1>(lhs, rhs, atEnd);
292 : }
293 :
294 : template <unsigned I>
295 : static bool isEqualImpl(const Tuple &, const Tuple &, std::true_type) {
296 : return true;
297 : }
298 :
299 : static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
300 : std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
301 : return isEqualImpl<0>(lhs, rhs, atEnd);
302 : }
303 : };
304 :
305 : // Provide DenseMapInfo for enum classes.
306 : template <typename Enum>
307 : struct DenseMapInfo<Enum, std::enable_if_t<std::is_enum_v<Enum>>> {
308 : using UnderlyingType = std::underlying_type_t<Enum>;
309 : using Info = DenseMapInfo<UnderlyingType>;
310 :
311 : static Enum getEmptyKey() { return static_cast<Enum>(Info::getEmptyKey()); }
312 :
313 : static Enum getTombstoneKey() {
314 : return static_cast<Enum>(Info::getTombstoneKey());
315 : }
316 :
317 : static unsigned getHashValue(const Enum &Val) {
318 : return Info::getHashValue(static_cast<UnderlyingType>(Val));
319 : }
320 :
321 : static bool isEqual(const Enum &LHS, const Enum &RHS) { return LHS == RHS; }
322 : };
323 : } // end namespace llvm
324 :
325 : #endif // LLVM_ADT_DENSEMAPINFO_H
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