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 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. 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 Ptr, IntType Int) : Value(0) { 61 assert(IntBits <= PtrTraits::NumLowBitsAvailable && 62 "PointerIntPair formed with integer size too large for pointer"); 63 setPointer(Ptr); 64 setInt(Int); 65 } 66 67 PointerTy getPointer() const { 68 return PtrTraits::getFromVoidPointer( 69 reinterpret_cast<void*>(Value & PointerBitMask)); 70 } 71 72 IntType getInt() const { 73 return (IntType)((Value >> IntShift) & IntMask); 74 } 75 76 void setPointer(PointerTy Ptr) { 77 intptr_t PtrVal 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); 83 } 84 85 void setInt(IntType Int) { 86 intptr_t IntVal = Int; 87 assert(IntVal < (1 << IntBits) && "Integer too large for field"); 88 89 // Preserve all bits other than the ones we are updating. 90 Value &= ~ShiftedIntMask; // Remove integer field. 91 Value |= IntVal << IntShift; // Set new integer. 92 } 93 94 PointerTy const *getAddrOfPointer() const { 95 return const_cast<PointerIntPair *>(this)->getAddrOfPointer(); 96 } 97 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); 103 } 104 105 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); } 106 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);} 107 108 static PointerIntPair getFromOpaqueValue(void *V) { 109 PointerIntPair P; P.setFromOpaqueValue(V); return P; 110 } 111 112 // 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)); 117 } 118 119 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;} 125}; 126 127template <typename T> struct isPodLike; 128template<typename PointerTy, unsigned IntBits, typename IntType> 129struct isPodLike<PointerIntPair<PointerTy, IntBits, IntType> > { 130 static const bool value = true; 131}; 132 133// Provide specialization of DenseMapInfo for PointerIntPair. 134template<typename PointerTy, unsigned IntBits, typename IntType> 135struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > { 136 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty; 137 static Ty getEmptyKey() { 138 uintptr_t Val = static_cast<uintptr_t>(-1); 139 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 140 return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1)); 141 } 142 static Ty getTombstoneKey() { 143 uintptr_t Val = static_cast<uintptr_t>(-2); 144 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 145 return Ty(reinterpret_cast<PointerTy>(Val), IntType(0)); 146 } 147 static unsigned getHashValue(Ty V) { 148 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue()); 149 return unsigned(IV) ^ unsigned(IV >> 9); 150 } 151 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; } 152}; 153 154// Teach SmallPtrSet that PointerIntPair is "basically a pointer". 155template<typename PointerTy, unsigned IntBits, typename IntType, 156 typename PtrTraits> 157class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType, 158 PtrTraits> > { 159public: 160 static inline void * 161 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) { 162 return P.getOpaqueValue(); 163 } 164 static inline PointerIntPair<PointerTy, IntBits, IntType> 165 getFromVoidPointer(void *P) { 166 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 167 } 168 static inline PointerIntPair<PointerTy, IntBits, IntType> 169 getFromVoidPointer(const void *P) { 170 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 171 } 172 enum { 173 NumLowBitsAvailable = PtrTraits::NumLowBitsAvailable - IntBits 174 }; 175}; 176 177} // end namespace llvm 178#endif 179