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 public: 66 PointerIntPair() : Value(0) {} 67 PointerIntPair(PointerTy PtrVal, IntType IntVal) { 68 setPointerAndInt(PtrVal, IntVal); 69 } 70 explicit PointerIntPair(PointerTy PtrVal) { 71 initWithPointer(PtrVal); 72 } 73 74 PointerTy getPointer() const { 75 return PtrTraits::getFromVoidPointer( 76 reinterpret_cast<void*>(Value & PointerBitMask)); 77 } 78 79 IntType getInt() const { 80 return (IntType)((Value >> IntShift) & IntMask); 81 } 82 83 void setPointer(PointerTy PtrVal) { 84 intptr_t PtrWord 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); 90 } 91 92 void setInt(IntType IntVal) { 93 intptr_t IntWord = static_cast<intptr_t>(IntVal); 94 assert((IntWord & ~IntMask) == 0 && "Integer too large for field"); 95 96 // Preserve all bits other than the ones we are updating. 97 Value &= ~ShiftedIntMask; // Remove integer field. 98 Value |= IntWord << IntShift; // Set new integer. 99 } 100 101 void initWithPointer(PointerTy PtrVal) { 102 intptr_t PtrWord 103 = reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(PtrVal)); 104 assert((PtrWord & ~PointerBitMask) == 0 && 105 "Pointer is not sufficiently aligned"); 106 Value = PtrWord; 107 } 108 109 void setPointerAndInt(PointerTy PtrVal, IntType IntVal) { 110 intptr_t PtrWord 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"); 116 117 Value = PtrWord | (IntWord << IntShift); 118 } 119 120 PointerTy const *getAddrOfPointer() const { 121 return const_cast<PointerIntPair *>(this)->getAddrOfPointer(); 122 } 123 124 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); 129 } 130 131 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); } 132 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);} 133 134 static PointerIntPair getFromOpaqueValue(void *V) { 135 PointerIntPair P; P.setFromOpaqueValue(V); return P; 136 } 137 138 // 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)); 143 } 144 145 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;} 151 }; 152 153 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; 157 }; 158 159 // 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)); 167 } 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)); 172 } 173 static unsigned getHashValue(Ty V) { 174 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue()); 175 return unsigned(IV) ^ unsigned(IV >> 9); 176 } 177 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; } 178 }; 179 180 // Teach SmallPtrSet that PointerIntPair is "basically a pointer". 181 template<typename PointerTy, unsigned IntBits, typename IntType, 182 typename PtrTraits> 183 class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType, 184 PtrTraits> > { 185 public: 186 static inline void * 187 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) { 188 return P.getOpaqueValue(); 189 } 190 static inline PointerIntPair<PointerTy, IntBits, IntType> 191 getFromVoidPointer(void *P) { 192 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 193 } 194 static inline PointerIntPair<PointerTy, IntBits, IntType> 195 getFromVoidPointer(const void *P) { 196 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 197 } 198 enum { 199 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits 200 }; 201 }; 202 203 } // end namespace llvm 204 #endif 205
