DenseMapInfo.h revision fb3af88ba75898896714d49c608b8daa4f106636 
1//===- llvm/ADT/DenseMapInfo.h - Type traits for DenseMap -------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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 "llvm/Support/PointerLikeTypeTraits.h"
18#include <utility>
19
20namespace llvm {
21
22template<typename T>
23struct DenseMapInfo {
24  //static inline T getEmptyKey();
25  //static inline T getTombstoneKey();
26  //static unsigned getHashValue(const T &Val);
27  //static bool isEqual(const T &LHS, const T &RHS);
28  //static bool isPod()
29};
30
31// Provide DenseMapInfo for all pointers.
32template<typename T>
33struct DenseMapInfo<T*> {
34  static inline T* getEmptyKey() {
35    intptr_t Val = -1;
36    Val <<= PointerLikeTypeTraits<T*>::NumLowBitsAvailable;
37    return reinterpret_cast<T*>(Val);
38  }
39  static inline T* getTombstoneKey() {
40    intptr_t Val = -2;
41    Val <<= PointerLikeTypeTraits<T*>::NumLowBitsAvailable;
42    return reinterpret_cast<T*>(Val);
43  }
44  static unsigned getHashValue(const T *PtrVal) {
45    return (unsigned((uintptr_t)PtrVal) >> 4) ^
46           (unsigned((uintptr_t)PtrVal) >> 9);
47  }
48  static bool isEqual(const T *LHS, const T *RHS) { return LHS == RHS; }
49  static bool isPod() { return true; }
50};
51
52// Provide DenseMapInfo for chars.
53template<> struct DenseMapInfo<char> {
54  static inline char getEmptyKey() { return ~0; }
55  static inline char getTombstoneKey() { return ~0 - 1; }
56  static unsigned getHashValue(const char& Val) { return Val * 37; }
57  static bool isPod() { return true; }
58  static bool isEqual(const char &LHS, const char &RHS) {
59    return LHS == RHS;
60  }
61};
62
63// Provide DenseMapInfo for unsigned ints.
64template<> struct DenseMapInfo<unsigned> {
65  static inline unsigned getEmptyKey() { return ~0; }
66  static inline unsigned getTombstoneKey() { return ~0 - 1; }
67  static unsigned getHashValue(const unsigned& Val) { return Val * 37; }
68  static bool isPod() { return true; }
69  static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
70  return LHS == RHS;
71  }
72};
73
74// Provide DenseMapInfo for unsigned longs.
75template<> struct DenseMapInfo<unsigned long> {
76  static inline unsigned long getEmptyKey() { return ~0L; }
77  static inline unsigned long getTombstoneKey() { return ~0L - 1L; }
78  static unsigned getHashValue(const unsigned long& Val) {
79    return (unsigned)(Val * 37L);
80  }
81  static bool isPod() { return true; }
82  static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {
83  return LHS == RHS;
84  }
85};
86
87// Provide DenseMapInfo for all pairs whose members have info.
88template<typename T, typename U>
89struct DenseMapInfo<std::pair<T, U> > {
90  typedef std::pair<T, U> Pair;
91  typedef DenseMapInfo<T> FirstInfo;
92  typedef DenseMapInfo<U> SecondInfo;
93
94  static inline Pair getEmptyKey() {
95    return std::make_pair(FirstInfo::getEmptyKey(),
96                          SecondInfo::getEmptyKey());
97  }
98  static inline Pair getTombstoneKey() {
99    return std::make_pair(FirstInfo::getTombstoneKey(),
100                            SecondInfo::getEmptyKey());
101  }
102  static unsigned getHashValue(const Pair& PairVal) {
103    uint64_t key = (uint64_t)FirstInfo::getHashValue(PairVal.first) << 32
104          | (uint64_t)SecondInfo::getHashValue(PairVal.second);
105    key += ~(key << 32);
106    key ^= (key >> 22);
107    key += ~(key << 13);
108    key ^= (key >> 8);
109    key += (key << 3);
110    key ^= (key >> 15);
111    key += ~(key << 27);
112    key ^= (key >> 31);
113    return (unsigned)key;
114  }
115  static bool isEqual(const Pair& LHS, const Pair& RHS) { return LHS == RHS; }
116  static bool isPod() { return FirstInfo::isPod() && SecondInfo::isPod(); }
117};
118
119} // end namespace llvm
120
121#endif
122