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
24namespace llvm {
25
26namespace detail {
27
28/// Simplistic combination of 32-bit hash values into 32-bit hash values.
29static inline unsigned combineHashValue(unsigned a, unsigned b) {
30 uint64_t key = (uint64_t)a << 32 | (uint64_t)b;
31 key += ~(key << 32);
32 key ^= (key >> 22);
33 key += ~(key << 13);
34 key ^= (key >> 8);
35 key += (key << 3);
36 key ^= (key >> 15);
37 key += ~(key << 27);
38 key ^= (key >> 31);
39 return (unsigned)key;
40}
41
42} // end namespace detail
43
44/// An information struct used to provide DenseMap with the various necessary
45/// components for a given value type `T`. `Enable` is an optional additional
46/// parameter that is used to support SFINAE (generally using std::enable_if_t)
47/// in derived DenseMapInfo specializations; in non-SFINAE use cases this should
48/// just be `void`.
49template<typename T, typename Enable = void>
50struct DenseMapInfo {
51 //static inline T getEmptyKey();
52 //static inline T getTombstoneKey();
53 //static unsigned getHashValue(const T &Val);
54 //static bool isEqual(const T &LHS, const T &RHS);
55};
56
57// Provide DenseMapInfo for all pointers. Come up with sentinel pointer values
58// that are aligned to alignof(T) bytes, but try to avoid requiring T to be
59// complete. This allows clients to instantiate DenseMap<T*, ...> with forward
60// declared key types. Assume that no pointer key type requires more than 4096
61// bytes of alignment.
62template<typename T>
63struct DenseMapInfo<T*> {
64 // The following should hold, but it would require T to be complete:
65 // static_assert(alignof(T) <= (1 << Log2MaxAlign),
66 // "DenseMap does not support pointer keys requiring more than "
67 // "Log2MaxAlign bits of alignment");
68 static constexpr uintptr_t Log2MaxAlign = 12;
69
70 static inline T* getEmptyKey() {
71 uintptr_t Val = static_cast<uintptr_t>(-1);
72 Val <<= Log2MaxAlign;
73 return reinterpret_cast<T*>(Val);
74 }
75
76 static inline T* getTombstoneKey() {
77 uintptr_t Val = static_cast<uintptr_t>(-2);
78 Val <<= Log2MaxAlign;
79 return reinterpret_cast<T*>(Val);
80 }
81
82 static unsigned getHashValue(const T *PtrVal) {
83 return (unsigned((uintptr_t)PtrVal) >> 4) ^
84 (unsigned((uintptr_t)PtrVal) >> 9);
85 }
86
87 static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
88};
89
90// Provide DenseMapInfo for chars.
91template<> struct DenseMapInfo<char> {
92 static inline char getEmptyKey() { return ~0; }
93 static inline char getTombstoneKey() { return ~0 - 1; }
94 static unsigned getHashValue(const char& Val) { return Val * 37U; }
95
96 static bool isEqual(const char &LHS, const char &RHS) {
97 return LHS == RHS;
98 }
99};
100
101// Provide DenseMapInfo for unsigned chars.
102template <> struct DenseMapInfo<unsigned char> {
103 static inline unsigned char getEmptyKey() { return ~0; }
104 static inline unsigned char getTombstoneKey() { return ~0 - 1; }
105 static unsigned getHashValue(const unsigned char &Val) { return Val * 37U; }
106
107 static bool isEqual(const unsigned char &LHS, const unsigned char &RHS) {
108 return LHS == RHS;
109 }
110};
111
112// Provide DenseMapInfo for unsigned shorts.
113template <> struct DenseMapInfo<unsigned short> {
114 static inline unsigned short getEmptyKey() { return 0xFFFF; }
115 static inline unsigned short getTombstoneKey() { return 0xFFFF - 1; }
116 static unsigned getHashValue(const unsigned short &Val) { return Val * 37U; }
117
118 static bool isEqual(const unsigned short &LHS, const unsigned short &RHS) {
119 return LHS == RHS;
120 }
121};
122
123// Provide DenseMapInfo for unsigned ints.
124template<> struct DenseMapInfo<unsigned> {
125 static inline unsigned getEmptyKey() { return ~0U; }
126 static inline unsigned getTombstoneKey() { return ~0U - 1; }
127 static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
128
129 static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
130 return LHS == RHS;
131 }
132};
133
134// Provide DenseMapInfo for unsigned longs.
135template<> struct DenseMapInfo<unsigned long> {
136 static inline unsigned long getEmptyKey() { return ~0UL; }
137 static inline unsigned long getTombstoneKey() { return ~0UL - 1L; }
138
139 static unsigned getHashValue(const unsigned long& Val) {
140 return (unsigned)(Val * 37UL);
141 }
142
143 static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
144 return LHS == RHS;
145 }
146};
147
148// Provide DenseMapInfo for unsigned long longs.
149template<> struct DenseMapInfo<unsigned long long> {
150 static inline unsigned long long getEmptyKey() { return ~0ULL; }
151 static inline unsigned long long getTombstoneKey() { return ~0ULL - 1ULL; }
152
153 static unsigned getHashValue(const unsigned long long& Val) {
154 return (unsigned)(Val * 37ULL);
155 }
156
157 static bool isEqual(const unsigned long long& LHS,
158 const unsigned long long& RHS) {
159 return LHS == RHS;
160 }
161};
162
163// Provide DenseMapInfo for shorts.
164template <> struct DenseMapInfo<short> {
165 static inline short getEmptyKey() { return 0x7FFF; }
166 static inline short getTombstoneKey() { return -0x7FFF - 1; }
167 static unsigned getHashValue(const short &Val) { return Val * 37U; }
168 static bool isEqual(const short &LHS, const short &RHS) { return LHS == RHS; }
169};
170
171// Provide DenseMapInfo for ints.
172template<> struct DenseMapInfo<int> {
173 static inline int getEmptyKey() { return 0x7fffffff; }
174 static inline int getTombstoneKey() { return -0x7fffffff - 1; }
175 static unsigned getHashValue(const int& Val) { return (unsigned)(Val * 37U); }
176
177 static bool isEqual(const int& LHS, const int& RHS) {
178 return LHS == RHS;
179 }
180};
181
182// Provide DenseMapInfo for longs.
183template<> struct DenseMapInfo<long> {
184 static inline long getEmptyKey() {
185 return (1UL << (sizeof(long) * 8 - 1)) - 1UL;
186 }
187
188 static inline long getTombstoneKey() { return getEmptyKey() - 1L; }
189
190 static unsigned getHashValue(const long& Val) {
191 return (unsigned)(Val * 37UL);
192 }
193
194 static bool isEqual(const long& LHS, const long& RHS) {
195 return LHS == RHS;
196 }
197};
198
199// Provide DenseMapInfo for long longs.
200template<> struct DenseMapInfo<long long> {
201 static inline long long getEmptyKey() { return 0x7fffffffffffffffLL; }
202 static inline long long getTombstoneKey() { return -0x7fffffffffffffffLL-1; }
203
204 static unsigned getHashValue(const long long& Val) {
205 return (unsigned)(Val * 37ULL);
206 }
207
208 static bool isEqual(const long long& LHS,
209 const long long& RHS) {
210 return LHS == RHS;
211 }
212};
213
214// Provide DenseMapInfo for all pairs whose members have info.
215template<typename T, typename U>
216struct DenseMapInfo<std::pair<T, U>> {
217 using Pair = std::pair<T, U>;
218 using FirstInfo = DenseMapInfo<T>;
219 using SecondInfo = DenseMapInfo<U>;
220
221 static inline Pair getEmptyKey() {
222 return std::make_pair(FirstInfo::getEmptyKey(),
223 SecondInfo::getEmptyKey());
224 }
225
226 static inline Pair getTombstoneKey() {
227 return std::make_pair(FirstInfo::getTombstoneKey(),
228 SecondInfo::getTombstoneKey());
229 }
230
231 static unsigned getHashValue(const Pair& PairVal) {
232 return detail::combineHashValue(a: FirstInfo::getHashValue(PairVal.first),
233 b: SecondInfo::getHashValue(PairVal.second));
234 }
235
236 // Expose an additional function intended to be used by other
237 // specializations of DenseMapInfo without needing to know how
238 // to combine hash values manually
239 static unsigned getHashValuePiecewise(const T &First, const U &Second) {
240 return detail::combineHashValue(a: FirstInfo::getHashValue(First),
241 b: SecondInfo::getHashValue(Second));
242 }
243
244 static bool isEqual(const Pair &LHS, const Pair &RHS) {
245 return FirstInfo::isEqual(LHS.first, RHS.first) &&
246 SecondInfo::isEqual(LHS.second, RHS.second);
247 }
248};
249
250// Provide DenseMapInfo for all tuples whose members have info.
251template <typename... Ts> struct DenseMapInfo<std::tuple<Ts...>> {
252 using Tuple = std::tuple<Ts...>;
253
254 static inline Tuple getEmptyKey() {
255 return Tuple(DenseMapInfo<Ts>::getEmptyKey()...);
256 }
257
258 static inline Tuple getTombstoneKey() {
259 return Tuple(DenseMapInfo<Ts>::getTombstoneKey()...);
260 }
261
262 template <unsigned I>
263 static unsigned getHashValueImpl(const Tuple &values, std::false_type) {
264 using EltType = std::tuple_element_t<I, Tuple>;
265 std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
266 return detail::combineHashValue(
267 a: DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
268 b: getHashValueImpl<I + 1>(values, atEnd));
269 }
270
271 template <unsigned I>
272 static unsigned getHashValueImpl(const Tuple &, std::true_type) {
273 return 0;
274 }
275
276 static unsigned getHashValue(const std::tuple<Ts...> &values) {
277 std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
278 return getHashValueImpl<0>(values, atEnd);
279 }
280
281 template <unsigned I>
282 static bool isEqualImpl(const Tuple &lhs, const Tuple &rhs, std::false_type) {
283 using EltType = std::tuple_element_t<I, Tuple>;
284 std::integral_constant<bool, I + 1 == sizeof...(Ts)> atEnd;
285 return DenseMapInfo<EltType>::isEqual(std::get<I>(lhs), std::get<I>(rhs)) &&
286 isEqualImpl<I + 1>(lhs, rhs, atEnd);
287 }
288
289 template <unsigned I>
290 static bool isEqualImpl(const Tuple &, const Tuple &, std::true_type) {
291 return true;
292 }
293
294 static bool isEqual(const Tuple &lhs, const Tuple &rhs) {
295 std::integral_constant<bool, 0 == sizeof...(Ts)> atEnd;
296 return isEqualImpl<0>(lhs, rhs, atEnd);
297 }
298};
299
300} // end namespace llvm
301
302#endif // LLVM_ADT_DENSEMAPINFO_H
303

source code of include/llvm-17/llvm/ADT/DenseMapInfo.h