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 66 public: 67 PointerIntPair() : Value(0) {} 68 PointerIntPair(PointerTy PtrVal, IntType IntVal) { 69 setPointerAndInt(PtrVal, IntVal); 70 } 71 explicit PointerIntPair(PointerTy PtrVal) { 72 initWithPointer(PtrVal); 73 } 74 75 PointerTy getPointer() const { 76 return PtrTraits::getFromVoidPointer( 77 reinterpret_cast<void*>(Value & PointerBitMask)); 78 } 79 80 IntType getInt() const { 81 return (IntType)((Value >> IntShift) & IntMask); 82 } 83 84 void setPointer(PointerTy PtrVal) { 85 intptr_t PtrWord 86 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 87 assert((PtrWord & ~PointerBitMask) == 0 && 88 "Pointer is not sufficiently aligned"); 89 // Preserve all low bits, just update the pointer. 90 Value = PtrWord | (Value & ~PointerBitMask); 91 } 92 93 void setInt(IntType IntVal) { 94 intptr_t IntWord = static_cast<intptr_t>(IntVal); 95 assert((IntWord & ~IntMask) == 0 && "Integer too large for field"); 96 97 // Preserve all bits other than the ones we are updating. 98 Value &= ~ShiftedIntMask; // Remove integer field. 99 Value |= IntWord << IntShift; // Set new integer. 100 } 101 102 void initWithPointer(PointerTy PtrVal) { 103 intptr_t PtrWord 104 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 105 assert((PtrWord & ~PointerBitMask) == 0 && 106 "Pointer is not sufficiently aligned"); 107 Value = PtrWord; 108 } 109 110 void setPointerAndInt(PointerTy PtrVal, IntType IntVal) { 111 intptr_t PtrWord 112 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 113 assert((PtrWord & ~PointerBitMask) == 0 && 114 "Pointer is not sufficiently aligned"); 115 intptr_t IntWord = static_cast<intptr_t>(IntVal); 116 assert((IntWord & ~IntMask) == 0 && "Integer too large for field"); 117 118 Value = PtrWord | (IntWord << IntShift); 119 } 120 121 PointerTy const *getAddrOfPointer() const { 122 return const_cast<PointerIntPair *>(this)->getAddrOfPointer(); 123 } 124 125 PointerTy *getAddrOfPointer() { 126 assert(Value == reinterpret_cast<intptr_t>(getPointer()) && 127 "Can only return the address if IntBits is cleared and " 128 "PtrTraits doesn't change the pointer"); 129 return reinterpret_cast<PointerTy *>(&Value); 130 } 131 132 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); } 133 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);} 134 135 static PointerIntPair getFromOpaqueValue(void *V) { 136 PointerIntPair P; 137 P.setFromOpaqueValue(V); 138 return P; 139 } 140 141 // Allow PointerIntPairs to be created from const void * if and only if the 142 // pointer type could be created from a const void *. 143 static PointerIntPair getFromOpaqueValue(const void *V) { 144 (void)PtrTraits::getFromVoidPointer(V); 145 return getFromOpaqueValue(const_cast<void *>(V)); 146 } 147 148 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 bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;} 152 bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;} 153 bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;} 154 }; 155 156 template <typename T> struct isPodLike; 157 template<typename PointerTy, unsigned IntBits, typename IntType> 158 struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType> > { 159 static const bool value = true; 160 }; 161 162 // Provide specialization of DenseMapInfo for PointerIntPair. 163 template<typename PointerTy, unsigned IntBits, typename IntType> 164 struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > { 165 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty; 166 static Ty getEmptyKey() { 167 uintptr_t Val = static_cast<uintptr_t>(-1); 168 Val <<= PointerLikeTypeTraits<Ty>::NumLowBitsAvailable; 169 return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val)); 170 } 171 static Ty getTombstoneKey() { 172 uintptr_t Val = static_cast<uintptr_t>(-2); 173 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 174 return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val)); 175 } 176 static unsigned getHashValue(Ty V) { 177 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue()); 178 return unsigned(IV) ^ unsigned(IV >> 9); 179 } 180 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; } 181 }; 182 183 // Teach SmallPtrSet that PointerIntPair is "basically a pointer". 184 template<typename PointerTy, unsigned IntBits, typename IntType, 185 typename PtrTraits> 186 class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType, 187 PtrTraits> > { 188 public: 189 static inline void * 190 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) { 191 return P.getOpaqueValue(); 192 } 193 static inline PointerIntPair<PointerTy, IntBits, IntType> 194 getFromVoidPointer(void *P) { 195 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 196 } 197 static inline PointerIntPair<PointerTy, IntBits, IntType> 198 getFromVoidPointer(const void *P) { 199 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 200 } 201 enum { 202 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits 203 }; 204 }; 205 206 } // end namespace llvm 207 #endif 208
