1 //===- llvm/ADT/PointerIntPair.h - Pair for pointer and int -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PointerIntPair class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_POINTERINTPAIR_H
15 #define LLVM_ADT_POINTERINTPAIR_H
17 #include "llvm/Support/PointerLikeTypeTraits.h"
24 template <typename T> struct DenseMapInfo;
25 template <typename PointerT, unsigned IntBits, typename PtrTraits>
26 struct PointerIntPairInfo;
28 /// PointerIntPair - This class implements a pair of a pointer and small
29 /// integer. It is designed to represent this in the space required by one
30 /// pointer by bitmangling the integer into the low part of the pointer. This
31 /// can only be done for small integers: typically up to 3 bits, but it depends
32 /// on the number of bits available according to PointerLikeTypeTraits for the
35 /// Note that PointerIntPair always puts the IntVal part in the highest bits
36 /// possible. For example, PointerIntPair<void*, 1, bool> will put the bit for
37 /// the bool into bit #2, not bit #0, which allows the low two bits to be used
38 /// for something else. For example, this allows:
39 /// PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>
40 /// ... and the two bools will land in different bits.
41 template <typename PointerTy, unsigned IntBits, typename IntType = unsigned,
42 typename PtrTraits = PointerLikeTypeTraits<PointerTy>,
43 typename Info = PointerIntPairInfo<PointerTy, IntBits, PtrTraits>>
44 class PointerIntPair {
45 // Used by MSVC visualizer and generally helpful for debugging/visualizing.
50 constexpr PointerIntPair() = default;
52 PointerIntPair(PointerTy PtrVal, IntType IntVal) {
53 setPointerAndInt(PtrVal, IntVal);
56 explicit PointerIntPair(PointerTy PtrVal) { initWithPointer(PtrVal); }
58 PointerTy getPointer() const { return Info::getPointer(Value); }
60 IntType getInt() const { return (IntType)Info::getInt(Value); }
62 void setPointer(PointerTy PtrVal) {
63 Value = Info::updatePointer(Value, PtrVal);
66 void setInt(IntType IntVal) {
67 Value = Info::updateInt(Value, static_cast<intptr_t>(IntVal));
70 void initWithPointer(PointerTy PtrVal) {
71 Value = Info::updatePointer(0, PtrVal);
74 void setPointerAndInt(PointerTy PtrVal, IntType IntVal) {
75 Value = Info::updateInt(Info::updatePointer(0, PtrVal),
76 static_cast<intptr_t>(IntVal));
79 PointerTy const *getAddrOfPointer() const {
80 return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
83 PointerTy *getAddrOfPointer() {
84 assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&
85 "Can only return the address if IntBits is cleared and "
86 "PtrTraits doesn't change the pointer");
87 return reinterpret_cast<PointerTy *>(&Value);
90 void *getOpaqueValue() const { return reinterpret_cast<void *>(Value); }
92 void setFromOpaqueValue(void *Val) {
93 Value = reinterpret_cast<intptr_t>(Val);
96 static PointerIntPair getFromOpaqueValue(void *V) {
98 P.setFromOpaqueValue(V);
102 // Allow PointerIntPairs to be created from const void * if and only if the
103 // pointer type could be created from a const void *.
104 static PointerIntPair getFromOpaqueValue(const void *V) {
105 (void)PtrTraits::getFromVoidPointer(V);
106 return getFromOpaqueValue(const_cast<void *>(V));
109 bool operator==(const PointerIntPair &RHS) const {
110 return Value == RHS.Value;
113 bool operator!=(const PointerIntPair &RHS) const {
114 return Value != RHS.Value;
117 bool operator<(const PointerIntPair &RHS) const { return Value < RHS.Value; }
118 bool operator>(const PointerIntPair &RHS) const { return Value > RHS.Value; }
120 bool operator<=(const PointerIntPair &RHS) const {
121 return Value <= RHS.Value;
124 bool operator>=(const PointerIntPair &RHS) const {
125 return Value >= RHS.Value;
129 template <typename PointerT, unsigned IntBits, typename PtrTraits>
130 struct PointerIntPairInfo {
131 static_assert(PtrTraits::NumLowBitsAvailable <
132 std::numeric_limits<uintptr_t>::digits,
133 "cannot use a pointer type that has all bits free");
134 static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
135 "PointerIntPair with integer size too large for pointer");
137 /// PointerBitMask - The bits that come from the pointer.
139 ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable) - 1),
141 /// IntShift - The number of low bits that we reserve for other uses, and
143 IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable - IntBits,
145 /// IntMask - This is the unshifted mask for valid bits of the int type.
146 IntMask = (uintptr_t)(((intptr_t)1 << IntBits) - 1),
148 // ShiftedIntMask - This is the bits for the integer shifted in place.
149 ShiftedIntMask = (uintptr_t)(IntMask << IntShift)
152 static PointerT getPointer(intptr_t Value) {
153 return PtrTraits::getFromVoidPointer(
154 reinterpret_cast<void *>(Value & PointerBitMask));
157 static intptr_t getInt(intptr_t Value) {
158 return (Value >> IntShift) & IntMask;
161 static intptr_t updatePointer(intptr_t OrigValue, PointerT Ptr) {
163 reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(Ptr));
164 assert((PtrWord & ~PointerBitMask) == 0 &&
165 "Pointer is not sufficiently aligned");
166 // Preserve all low bits, just update the pointer.
167 return PtrWord | (OrigValue & ~PointerBitMask);
170 static intptr_t updateInt(intptr_t OrigValue, intptr_t Int) {
171 intptr_t IntWord = static_cast<intptr_t>(Int);
172 assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
174 // Preserve all bits other than the ones we are updating.
175 return (OrigValue & ~ShiftedIntMask) | IntWord << IntShift;
179 template <typename T> struct isPodLike;
180 template <typename PointerTy, unsigned IntBits, typename IntType>
181 struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType>> {
182 static const bool value = true;
185 // Provide specialization of DenseMapInfo for PointerIntPair.
186 template <typename PointerTy, unsigned IntBits, typename IntType>
187 struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType>> {
188 using Ty = PointerIntPair<PointerTy, IntBits, IntType>;
190 static Ty getEmptyKey() {
191 uintptr_t Val = static_cast<uintptr_t>(-1);
192 Val <<= PointerLikeTypeTraits<Ty>::NumLowBitsAvailable;
193 return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
196 static Ty getTombstoneKey() {
197 uintptr_t Val = static_cast<uintptr_t>(-2);
198 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
199 return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));
202 static unsigned getHashValue(Ty V) {
203 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
204 return unsigned(IV) ^ unsigned(IV >> 9);
207 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
210 // Teach SmallPtrSet that PointerIntPair is "basically a pointer".
211 template <typename PointerTy, unsigned IntBits, typename IntType,
213 struct PointerLikeTypeTraits<
214 PointerIntPair<PointerTy, IntBits, IntType, PtrTraits>> {
216 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
217 return P.getOpaqueValue();
220 static inline PointerIntPair<PointerTy, IntBits, IntType>
221 getFromVoidPointer(void *P) {
222 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
225 static inline PointerIntPair<PointerTy, IntBits, IntType>
226 getFromVoidPointer(const void *P) {
227 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
230 enum { NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits };
233 } // end namespace llvm
235 #endif // LLVM_ADT_POINTERINTPAIR_H