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 densemap::detail {
27// A bit mixer with very low latency using one multiplications and one
28// xor-shift. The constant is from splitmix64.
29inline uint64_t mix(uint64_t x) {
30 x *= 0xbf58476d1ce4e5b9u;
31 x ^= x >> 31;
32 return x;
33}
34} // namespace densemap::detail
35
36namespace detail {
37
38/// Simplistic combination of 32-bit hash values into 32-bit hash values.
39inline 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`.
51template<typename T, typename Enable = void>
52struct 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.
64template<typename T>
65struct 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 static inline T* getEmptyKey() {
73 uintptr_t Val = static_cast<uintptr_t>(-1);
74 Val <<= Log2MaxAlign;
75 return reinterpret_cast<T*>(Val);
76 }
77
78 static inline T* getTombstoneKey() {
79 uintptr_t Val = static_cast<uintptr_t>(-2);
80 Val <<= Log2MaxAlign;
81 return reinterpret_cast<T*>(Val);
82 }
83
84 static unsigned getHashValue(const T *PtrVal) {
85 return (unsigned((uintptr_t)PtrVal) >> 4) ^
86 (unsigned((uintptr_t)PtrVal) >> 9);
87 }
88
89 static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
90};
91
92// Provide DenseMapInfo for chars.
93template<> 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.
104template <> 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.
115template <> 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.
126template<> 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.
137template<> struct DenseMapInfo<unsigned long> {
138 static inline unsigned long getEmptyKey() { return ~0UL; }
139 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(x: Val);
146 }
147
148 static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
149 return LHS == RHS;
150 }
151};
152
153// Provide DenseMapInfo for unsigned long longs.
154template<> 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(x: 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.
169template <> 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.
177template<> 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.
188template<> 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.
205template<> 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.
220template<typename T, typename U>
221struct 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(a: FirstInfo::getHashValue(PairVal.first),
238 b: 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(a: FirstInfo::getHashValue(First),
246 b: 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.
256template <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 a: DenseMapInfo<EltType>::getHashValue(std::get<I>(values)),
273 b: 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.
306template <typename Enum>
307struct 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
326