LLVM  3.7.0
PointerIntPair.h
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1 //===- llvm/ADT/PointerIntPair.h - Pair for pointer and int -----*- 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 the PointerIntPair class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_ADT_POINTERINTPAIR_H
15 #define LLVM_ADT_POINTERINTPAIR_H
16 
17 #include "llvm/Support/Compiler.h"
19 #include <cassert>
20 #include <limits>
21 
22 namespace llvm {
23 
24 template<typename T>
25 struct DenseMapInfo;
26 
27 /// PointerIntPair - This class implements a pair of a pointer and small
28 /// integer. It is designed to represent this in the space required by one
29 /// pointer by bitmangling the integer into the low part of the pointer. This
30 /// can only be done for small integers: typically up to 3 bits, but it depends
31 /// on the number of bits available according to PointerLikeTypeTraits for the
32 /// type.
33 ///
34 /// Note that PointerIntPair always puts the IntVal part in the highest bits
35 /// possible. For example, PointerIntPair<void*, 1, bool> will put the bit for
36 /// the bool into bit #2, not bit #0, which allows the low two bits to be used
37 /// for something else. For example, this allows:
38 /// PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>
39 /// ... and the two bools will land in different bits.
40 ///
41 template <typename PointerTy, unsigned IntBits, typename IntType=unsigned,
42  typename PtrTraits = PointerLikeTypeTraits<PointerTy> >
45  static_assert(PtrTraits::NumLowBitsAvailable <
46  std::numeric_limits<uintptr_t>::digits,
47  "cannot use a pointer type that has all bits free");
48  static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
49  "PointerIntPair with integer size too large for pointer");
50  enum : uintptr_t {
51  /// PointerBitMask - The bits that come from the pointer.
52  PointerBitMask =
53  ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1),
54 
55  /// IntShift - The number of low bits that we reserve for other uses, and
56  /// keep zero.
57  IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable-IntBits,
58 
59  /// IntMask - This is the unshifted mask for valid bits of the int type.
60  IntMask = (uintptr_t)(((intptr_t)1 << IntBits)-1),
61 
62  // ShiftedIntMask - This is the bits for the integer shifted in place.
63  ShiftedIntMask = (uintptr_t)(IntMask << IntShift)
64  };
65 public:
67  PointerIntPair(PointerTy PtrVal, IntType IntVal) {
68  setPointerAndInt(PtrVal, IntVal);
69  }
70  explicit PointerIntPair(PointerTy PtrVal) {
71  initWithPointer(PtrVal);
72  }
73 
75  return PtrTraits::getFromVoidPointer(
76  reinterpret_cast<void*>(Value & PointerBitMask));
77  }
78 
79  IntType getInt() const {
80  return (IntType)((Value >> IntShift) & IntMask);
81  }
82 
83  void setPointer(PointerTy PtrVal) {
84  intptr_t PtrWord
85  = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
86  assert((PtrWord & ~PointerBitMask) == 0 &&
87  "Pointer is not sufficiently aligned");
88  // Preserve all low bits, just update the pointer.
89  Value = PtrWord | (Value & ~PointerBitMask);
90  }
91 
92  void setInt(IntType IntVal) {
93  intptr_t IntWord = static_cast<intptr_t>(IntVal);
94  assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
95 
96  // Preserve all bits other than the ones we are updating.
97  Value &= ~ShiftedIntMask; // Remove integer field.
98  Value |= IntWord << IntShift; // Set new integer.
99  }
100 
101  void initWithPointer(PointerTy PtrVal) {
102  intptr_t PtrWord
103  = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
104  assert((PtrWord & ~PointerBitMask) == 0 &&
105  "Pointer is not sufficiently aligned");
106  Value = PtrWord;
107  }
108 
109  void setPointerAndInt(PointerTy PtrVal, IntType IntVal) {
110  intptr_t PtrWord
111  = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
112  assert((PtrWord & ~PointerBitMask) == 0 &&
113  "Pointer is not sufficiently aligned");
114  intptr_t IntWord = static_cast<intptr_t>(IntVal);
115  assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
116 
117  Value = PtrWord | (IntWord << IntShift);
118  }
119 
120  PointerTy const *getAddrOfPointer() const {
121  return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
122  }
123 
125  assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&
126  "Can only return the address if IntBits is cleared and "
127  "PtrTraits doesn't change the pointer");
128  return reinterpret_cast<PointerTy *>(&Value);
129  }
130 
131  void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
132  void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
133 
135  PointerIntPair P; P.setFromOpaqueValue(V); return P;
136  }
137 
138  // Allow PointerIntPairs to be created from const void * if and only if the
139  // pointer type could be created from a const void *.
140  static PointerIntPair getFromOpaqueValue(const void *V) {
141  (void)PtrTraits::getFromVoidPointer(V);
142  return getFromOpaqueValue(const_cast<void *>(V));
143  }
144 
145  bool operator==(const PointerIntPair &RHS) const {return Value == RHS.Value;}
146  bool operator!=(const PointerIntPair &RHS) const {return Value != RHS.Value;}
147  bool operator<(const PointerIntPair &RHS) const {return Value < RHS.Value;}
148  bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;}
149  bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;}
150  bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;}
151 };
152 
153 template <typename T> struct isPodLike;
154 template<typename PointerTy, unsigned IntBits, typename IntType>
155 struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType> > {
156  static const bool value = true;
157 };
158 
159 // Provide specialization of DenseMapInfo for PointerIntPair.
160 template<typename PointerTy, unsigned IntBits, typename IntType>
161 struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > {
163  static Ty getEmptyKey() {
164  uintptr_t Val = static_cast<uintptr_t>(-1);
165  Val <<= PointerLikeTypeTraits<Ty>::NumLowBitsAvailable;
166  return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
167  }
168  static Ty getTombstoneKey() {
169  uintptr_t Val = static_cast<uintptr_t>(-2);
170  Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
171  return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
172  }
173  static unsigned getHashValue(Ty V) {
174  uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
175  return unsigned(IV) ^ unsigned(IV >> 9);
176  }
177  static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
178 };
179 
180 // Teach SmallPtrSet that PointerIntPair is "basically a pointer".
181 template<typename PointerTy, unsigned IntBits, typename IntType,
182  typename PtrTraits>
184  PtrTraits> > {
185 public:
186  static inline void *
188  return P.getOpaqueValue();
189  }
193  }
195  getFromVoidPointer(const void *P) {
197  }
198  enum {
199  NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits
200  };
201 };
202 
203 } // end namespace llvm
204 #endif
bool operator<=(const PointerIntPair &RHS) const
PointerIntPair(PointerTy PtrVal, IntType IntVal)
void setFromOpaqueValue(void *Val)
bool operator==(const PointerIntPair &RHS) const
static const bool value
Definition: type_traits.h:46
PointerLikeTypeTraits - This is a traits object that is used to handle pointer types and things that ...
void setPointer(PointerTy PtrVal)
void setPointerAndInt(PointerTy PtrVal, IntType IntVal)
PointerTy * getAddrOfPointer()
void initWithPointer(PointerTy PtrVal)
void setInt(IntType IntVal)
bool operator>(const PointerIntPair &RHS) const
#define P(N)
PointerIntPair - This class implements a pair of a pointer and small integer.
bool operator>=(const PointerIntPair &RHS) const
bool operator!=(const PointerIntPair &RHS) const
IntType getInt() const
static PointerIntPair getFromOpaqueValue(void *V)
PointerTy getPointer() const
isPodLike - This is a type trait that is used to determine whether a given type can be copied around ...
Definition: ArrayRef.h:365
void * getOpaqueValue() const
bool operator<(const PointerIntPair &RHS) const
PointerIntPair(PointerTy PtrVal)
static PointerIntPair< PointerTy, IntBits, IntType > getFromVoidPointer(void *P)
static PointerIntPair getFromOpaqueValue(const void *V)
void * PointerTy
Definition: GenericValue.h:23
LLVM Value Representation.
Definition: Value.h:69
static void * getAsVoidPointer(const PointerIntPair< PointerTy, IntBits, IntType > &P)
PointerTy const * getAddrOfPointer() const
static PointerIntPair< PointerTy, IntBits, IntType > getFromVoidPointer(const void *P)