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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"
18 : #include "llvm/Support/PointerLikeTypeTraits.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> >
43 : class PointerIntPair {
44 : intptr_t Value;
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:
66 948 : PointerIntPair() : Value(0) {}
67 : PointerIntPair(PointerTy PtrVal, IntType IntVal) {
68 7 : setPointerAndInt(PtrVal, IntVal);
69 7 : }
70 : explicit PointerIntPair(PointerTy PtrVal) {
71 7 : initWithPointer(PtrVal);
72 7 : }
73 :
74 : PointerTy getPointer() const {
75 722 : return PtrTraits::getFromVoidPointer(
76 722 : reinterpret_cast<void*>(Value & PointerBitMask));
77 : }
78 :
79 : IntType getInt() const {
80 642 : 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 7 : intptr_t PtrWord
103 7 : = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
104 14 : assert((PtrWord & ~PointerBitMask) == 0 &&
105 : "Pointer is not sufficiently aligned");
106 7 : Value = PtrWord;
107 7 : }
108 :
109 : void setPointerAndInt(PointerTy PtrVal, IntType IntVal) {
110 7 : intptr_t PtrWord
111 7 : = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
112 14 : assert((PtrWord & ~PointerBitMask) == 0 &&
113 : "Pointer is not sufficiently aligned");
114 7 : intptr_t IntWord = static_cast<intptr_t>(IntVal);
115 14 : assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
116 :
117 7 : Value = PtrWord | (IntWord << IntShift);
118 7 : }
119 :
120 : PointerTy const *getAddrOfPointer() const {
121 : return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
122 : }
123 :
124 : PointerTy *getAddrOfPointer() {
125 0 : 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 0 : return reinterpret_cast<PointerTy *>(&Value);
129 : }
130 :
131 231 : void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
132 620 : void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
133 :
134 : static PointerIntPair getFromOpaqueValue(void *V) {
135 328 : 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 0 : 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> > {
162 : typedef PointerIntPair<PointerTy, IntBits, IntType> Ty;
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>
183 : class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType,
184 : PtrTraits> > {
185 : public:
186 : static inline void *
187 : getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
188 : return P.getOpaqueValue();
189 : }
190 : static inline PointerIntPair<PointerTy, IntBits, IntType>
191 : getFromVoidPointer(void *P) {
192 : return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
193 : }
194 : static inline PointerIntPair<PointerTy, IntBits, IntType>
195 : getFromVoidPointer(const void *P) {
196 : return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
197 : }
198 : enum {
199 : NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits
200 : };
201 : };
202 :
203 : } // end namespace llvm
204 : #endif
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