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/Compiler.h"
18 #include "llvm/Support/PointerLikeTypeTraits.h"
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
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.
41 template <typename PointerTy, unsigned IntBits, typename IntType=unsigned,
42 typename PtrTraits = PointerLikeTypeTraits<PointerTy> >
43 class PointerIntPair {
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");
51 /// PointerBitMask - The bits that come from the pointer.
53 ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1),
55 /// IntShift - The number of low bits that we reserve for other uses, and
57 IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable-IntBits,
59 /// IntMask - This is the unshifted mask for valid bits of the int type.
60 IntMask = (uintptr_t)(((intptr_t)1 << IntBits)-1),
62 // ShiftedIntMask - This is the bits for the integer shifted in place.
63 ShiftedIntMask = (uintptr_t)(IntMask << IntShift)
66 PointerIntPair() : Value(0) {}
67 PointerIntPair(PointerTy PtrVal, IntType IntVal) {
68 setPointerAndInt(PtrVal, IntVal);
70 explicit PointerIntPair(PointerTy PtrVal) {
71 initWithPointer(PtrVal);
74 PointerTy getPointer() const {
75 return PtrTraits::getFromVoidPointer(
76 reinterpret_cast<void*>(Value & PointerBitMask));
79 IntType getInt() const {
80 return (IntType)((Value >> IntShift) & IntMask);
83 void setPointer(PointerTy PtrVal) {
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);
92 void setInt(IntType IntVal) {
93 intptr_t IntWord = static_cast<intptr_t>(IntVal);
94 assert((IntWord & ~IntMask) == 0 && "Integer too large for field");
96 // Preserve all bits other than the ones we are updating.
97 Value &= ~ShiftedIntMask; // Remove integer field.
98 Value |= IntWord << IntShift; // Set new integer.
101 void initWithPointer(PointerTy PtrVal) {
103 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal));
104 assert((PtrWord & ~PointerBitMask) == 0 &&
105 "Pointer is not sufficiently aligned");
109 void setPointerAndInt(PointerTy PtrVal, IntType IntVal) {
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");
117 Value = PtrWord | (IntWord << IntShift);
120 PointerTy const *getAddrOfPointer() const {
121 return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
124 PointerTy *getAddrOfPointer() {
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);
131 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
132 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
134 static PointerIntPair getFromOpaqueValue(void *V) {
135 PointerIntPair P; P.setFromOpaqueValue(V); return P;
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));
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;}
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;
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));
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));
173 static unsigned getHashValue(Ty V) {
174 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
175 return unsigned(IV) ^ unsigned(IV >> 9);
177 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
180 // Teach SmallPtrSet that PointerIntPair is "basically a pointer".
181 template<typename PointerTy, unsigned IntBits, typename IntType,
183 class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType,
187 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
188 return P.getOpaqueValue();
190 static inline PointerIntPair<PointerTy, IntBits, IntType>
191 getFromVoidPointer(void *P) {
192 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
194 static inline PointerIntPair<PointerTy, IntBits, IntType>
195 getFromVoidPointer(const void *P) {
196 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
199 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits
203 } // end namespace llvm