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/PointerLikeTypeTraits.h" 18#include <cassert> 19 20namespace llvm { 21 22template<typename T> 23struct DenseMapInfo; 24 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 30/// type. 31/// 32/// Note that PointerIntPair always puts the IntVal 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. 38/// 39template <typename PointerTy, unsigned IntBits, typename IntType=unsigned, 40 typename PtrTraits = PointerLikeTypeTraits<PointerTy> > 41class PointerIntPair { 42 intptr_t Value; 43 enum { 44 /// PointerBitMask - The bits that come from the pointer. 45 PointerBitMask = 46 ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1), 47 48 /// IntShift - The number of low bits that we reserve for other uses, and 49 /// keep zero. 50 IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable-IntBits, 51 52 /// IntMask - This is the unshifted mask for valid bits of the int type. 53 IntMask = (uintptr_t)(((intptr_t)1 << IntBits)-1), 54 55 // ShiftedIntMask - This is the bits for the integer shifted in place. 56 ShiftedIntMask = (uintptr_t)(IntMask << IntShift) 57 }; 58public: 59 PointerIntPair() : Value(0) {} 60 PointerIntPair(PointerTy PtrVal, IntType IntVal) { 61 assert(IntBits <= PtrTraits::NumLowBitsAvailable && 62 "PointerIntPair formed with integer size too large for pointer"); 63 setPointerAndInt(PtrVal, IntVal); 64 } 65 explicit PointerIntPair(PointerTy PtrVal) { 66 initWithPointer(PtrVal); 67 } 68 69 PointerTy getPointer() const { 70 return PtrTraits::getFromVoidPointer( 71 reinterpret_cast<void*>(Value & PointerBitMask)); 72 } 73 74 IntType getInt() const { 75 return (IntType)((Value >> IntShift) & IntMask); 76 } 77 78 void setPointer(PointerTy PtrVal) { 79 intptr_t PtrWord 80 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 81 assert((PtrWord & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 && 82 "Pointer is not sufficiently aligned"); 83 // Preserve all low bits, just update the pointer. 84 Value = PtrWord | (Value & ~PointerBitMask); 85 } 86 87 void setInt(IntType IntVal) { 88 intptr_t IntWord = static_cast<intptr_t>(IntVal); 89 assert(IntWord < (1 << IntBits) && "Integer too large for field"); 90 91 // Preserve all bits other than the ones we are updating. 92 Value &= ~ShiftedIntMask; // Remove integer field. 93 Value |= IntWord << IntShift; // Set new integer. 94 } 95 96 void initWithPointer(PointerTy PtrVal) { 97 intptr_t PtrWord 98 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 99 assert((PtrWord & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 && 100 "Pointer is not sufficiently aligned"); 101 Value = PtrWord; 102 } 103 104 void setPointerAndInt(PointerTy PtrVal, IntType IntVal) { 105 intptr_t PtrWord 106 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 107 assert((PtrWord & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 && 108 "Pointer is not sufficiently aligned"); 109 intptr_t IntWord = static_cast<intptr_t>(IntVal); 110 assert(IntWord < (1 << IntBits) && "Integer too large for field"); 111 112 Value = PtrWord | (IntWord << IntShift); 113 } 114 115 PointerTy const *getAddrOfPointer() const { 116 return const_cast<PointerIntPair *>(this)->getAddrOfPointer(); 117 } 118 119 PointerTy *getAddrOfPointer() { 120 assert(Value == reinterpret_cast<intptr_t>(getPointer()) && 121 "Can only return the address if IntBits is cleared and " 122 "PtrTraits doesn't change the pointer"); 123 return reinterpret_cast<PointerTy *>(&Value); 124 } 125 126 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); } 127 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);} 128 129 static PointerIntPair getFromOpaqueValue(void *V) { 130 PointerIntPair P; P.setFromOpaqueValue(V); return P; 131 } 132 133 // Allow PointerIntPairs to be created from const void * if and only if the 134 // pointer type could be created from a const void *. 135 static PointerIntPair getFromOpaqueValue(const void *V) { 136 (void)PtrTraits::getFromVoidPointer(V); 137 return getFromOpaqueValue(const_cast<void *>(V)); 138 } 139 140 bool operator==(const PointerIntPair &RHS) const {return Value == RHS.Value;} 141 bool operator!=(const PointerIntPair &RHS) const {return Value != RHS.Value;} 142 bool operator<(const PointerIntPair &RHS) const {return Value < RHS.Value;} 143 bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;} 144 bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;} 145 bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;} 146}; 147 148template <typename T> struct isPodLike; 149template<typename PointerTy, unsigned IntBits, typename IntType> 150struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType> > { 151 static const bool value = true; 152}; 153 154// Provide specialization of DenseMapInfo for PointerIntPair. 155template<typename PointerTy, unsigned IntBits, typename IntType> 156struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > { 157 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty; 158 static Ty getEmptyKey() { 159 uintptr_t Val = static_cast<uintptr_t>(-1); 160 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 161 return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1)); 162 } 163 static Ty getTombstoneKey() { 164 uintptr_t Val = static_cast<uintptr_t>(-2); 165 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 166 return Ty(reinterpret_cast<PointerTy>(Val), IntType(0)); 167 } 168 static unsigned getHashValue(Ty V) { 169 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue()); 170 return unsigned(IV) ^ unsigned(IV >> 9); 171 } 172 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; } 173}; 174 175// Teach SmallPtrSet that PointerIntPair is "basically a pointer". 176template<typename PointerTy, unsigned IntBits, typename IntType, 177 typename PtrTraits> 178class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType, 179 PtrTraits> > { 180public: 181 static inline void * 182 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) { 183 return P.getOpaqueValue(); 184 } 185 static inline PointerIntPair<PointerTy, IntBits, IntType> 186 getFromVoidPointer(void *P) { 187 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 188 } 189 static inline PointerIntPair<PointerTy, IntBits, IntType> 190 getFromVoidPointer(const void *P) { 191 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 192 } 193 enum { 194 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits 195 }; 196}; 197 198} // end namespace llvm 199#endif 200