PointerIntPair.h revision c6a4b6b78b9262ad6a343a4edae88611ef970669
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 = ~(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1), 46 /// IntShift - The number of low bits that we reserve for other uses, and 47 /// keep zero. 48 IntShift = PtrTraits::NumLowBitsAvailable-IntBits, 49 50 /// IntMask - This is the unshifted mask for valid bits of the int type. 51 IntMask = ((intptr_t)1 << IntBits)-1, 52 53 // ShiftedIntMask - This is the bits for the integer shifted in place. 54 ShiftedIntMask = IntMask << IntShift 55 }; 56public: 57 PointerIntPair() : Value(0) {} 58 PointerIntPair(PointerTy Ptr, IntType Int) : Value(0) { 59 assert(IntBits <= PtrTraits::NumLowBitsAvailable && 60 "PointerIntPair formed with integer size too large for pointer"); 61 setPointer(Ptr); 62 setInt(Int); 63 } 64 65 PointerTy getPointer() const { 66 return reinterpret_cast<PointerTy>(Value & PointerBitMask); 67 } 68 69 IntType getInt() const { 70 return (IntType)((Value >> IntShift) & IntMask); 71 } 72 73 void setPointer(PointerTy Ptr) { 74 intptr_t PtrVal = reinterpret_cast<intptr_t>(Ptr); 75 assert((PtrVal & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 && 76 "Pointer is not sufficiently aligned"); 77 // Preserve all low bits, just update the pointer. 78 Value = PtrVal | (Value & ~PointerBitMask); 79 } 80 81 void setInt(IntType Int) { 82 intptr_t IntVal = Int; 83 assert(IntVal < (1 << IntBits) && "Integer too large for field"); 84 85 // Preserve all bits other than the ones we are updating. 86 Value &= ~ShiftedIntMask; // Remove integer field. 87 Value |= IntVal << IntShift; // Set new integer. 88 } 89 90 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); } 91 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);} 92 93 static PointerIntPair getFromOpaqueValue(void *V) { 94 PointerIntPair P; P.setFromOpaqueValue(V); return P; 95 } 96 97 bool operator==(const PointerIntPair &RHS) const {return Value == RHS.Value;} 98 bool operator!=(const PointerIntPair &RHS) const {return Value != RHS.Value;} 99 bool operator<(const PointerIntPair &RHS) const {return Value < RHS.Value;} 100 bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;} 101 bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;} 102 bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;} 103}; 104 105// Provide specialization of DenseMapInfo for PointerIntPair. 106template<typename PointerTy, unsigned IntBits, typename IntType> 107struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > { 108 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty; 109 static Ty getEmptyKey() { 110 intptr_t Val = -1; 111 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 112 return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1)); 113 } 114 static Ty getTombstoneKey() { 115 intptr_t Val = -2; 116 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable; 117 return Ty(reinterpret_cast<PointerTy>(Val), IntType(0)); 118 } 119 static unsigned getHashValue(Ty V) { 120 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue()); 121 return unsigned(IV) ^ unsigned(IV >> 9); 122 } 123 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; } 124 static bool isPod() { return true; } 125}; 126 127// Teach SmallPtrSet that PointerIntPair is "basically a pointer". 128template<typename PointerTy, unsigned IntBits, typename IntType, 129 typename PtrTraits> 130class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType, 131 PtrTraits> > { 132public: 133 static inline void * 134 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) { 135 return P.getOpaqueValue(); 136 } 137 static inline PointerIntPair<PointerTy, IntBits, IntType> 138 getFromVoidPointer(void *P) { 139 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P); 140 } 141 enum { 142 NumLowBitsAvailable = 143 PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable - IntBits 144 }; 145}; 146 147} // end namespace llvm 148#endif 149