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"
25 /// PointerIntPair - This class implements a pair of a pointer and small
26 /// integer. It is designed to represent this in the space required by one
27 /// pointer by bitmangling the integer into the low part of the pointer. This
28 /// can only be done for small integers: typically up to 3 bits, but it depends
29 /// on the number of bits available according to PointerLikeTypeTraits for the
32 /// Note that PointerIntPair always puts the Int part in the highest bits
33 /// possible. For example, PointerIntPair<void*, 1, bool> will put the bit for
34 /// the bool into bit #2, not bit #0, which allows the low two bits to be used
35 /// for something else. For example, this allows:
36 /// PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>
37 /// ... and the two bools will land in different bits.
39 template <typename PointerTy, unsigned IntBits, typename IntType=unsigned,
40 typename PtrTraits = PointerLikeTypeTraits<PointerTy> >
41 class PointerIntPair {
44 /// PointerBitMask - The bits that come from the pointer.
46 ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1),
48 /// IntShift - The number of low bits that we reserve for other uses, and
50 IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable-IntBits,
52 /// IntMask - This is the unshifted mask for valid bits of the int type.
53 IntMask = (uintptr_t)(((intptr_t)1 << IntBits)-1),
55 // ShiftedIntMask - This is the bits for the integer shifted in place.
56 ShiftedIntMask = (uintptr_t)(IntMask << IntShift)
59 PointerIntPair() : Value(0) {}
60 PointerIntPair(PointerTy Ptr, IntType Int) : Value(0) {
61 assert(IntBits <= PtrTraits::NumLowBitsAvailable &&
62 "PointerIntPair formed with integer size too large for pointer");
67 PointerTy getPointer() const {
68 return PtrTraits::getFromVoidPointer(
69 reinterpret_cast<void*>(Value & PointerBitMask));
72 IntType getInt() const {
73 return (IntType)((Value >> IntShift) & IntMask);
76 void setPointer(PointerTy Ptr) {
78 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(Ptr));
79 assert((PtrVal & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 &&
80 "Pointer is not sufficiently aligned");
81 // Preserve all low bits, just update the pointer.
82 Value = PtrVal | (Value & ~PointerBitMask);
85 void setInt(IntType Int) {
86 intptr_t IntVal = Int;
87 assert(IntVal < (1 << IntBits) && "Integer too large for field");
89 // Preserve all bits other than the ones we are updating.
90 Value &= ~ShiftedIntMask; // Remove integer field.
91 Value |= IntVal << IntShift; // Set new integer.
94 PointerTy const *getAddrOfPointer() const {
95 return const_cast<PointerIntPair *>(this)->getAddrOfPointer();
98 PointerTy *getAddrOfPointer() {
99 assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&
100 "Can only return the address if IntBits is cleared and "
101 "PtrTraits doesn't change the pointer");
102 return reinterpret_cast<PointerTy *>(&Value);
105 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
106 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
108 static PointerIntPair getFromOpaqueValue(void *V) {
109 PointerIntPair P; P.setFromOpaqueValue(V); return P;
112 // Allow PointerIntPairs to be created from const void * if and only if the
113 // pointer type could be created from a const void *.
114 static PointerIntPair getFromOpaqueValue(const void *V) {
115 (void)PtrTraits::getFromVoidPointer(V);
116 return getFromOpaqueValue(const_cast<void *>(V));
119 bool operator==(const PointerIntPair &RHS) const {return Value == RHS.Value;}
120 bool operator!=(const PointerIntPair &RHS) const {return Value != RHS.Value;}
121 bool operator<(const PointerIntPair &RHS) const {return Value < RHS.Value;}
122 bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;}
123 bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;}
124 bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;}
127 template <typename T> struct isPodLike;
128 template<typename PointerTy, unsigned IntBits, typename IntType>
129 struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType> > {
130 static const bool value = true;
133 // Provide specialization of DenseMapInfo for PointerIntPair.
134 template<typename PointerTy, unsigned IntBits, typename IntType>
135 struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > {
136 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty;
137 static Ty getEmptyKey() {
139 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
140 return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1));
142 static Ty getTombstoneKey() {
144 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
145 return Ty(reinterpret_cast<PointerTy>(Val), IntType(0));
147 static unsigned getHashValue(Ty V) {
148 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
149 return unsigned(IV) ^ unsigned(IV >> 9);
151 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
154 // Teach SmallPtrSet that PointerIntPair is "basically a pointer".
155 template<typename PointerTy, unsigned IntBits, typename IntType,
157 class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType,
161 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
162 return P.getOpaqueValue();
164 static inline PointerIntPair<PointerTy, IntBits, IntType>
165 getFromVoidPointer(void *P) {
166 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
168 static inline PointerIntPair<PointerTy, IntBits, IntType>
169 getFromVoidPointer(const void *P) {
170 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
173 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits
177 } // end namespace llvm