1 //===- llvm/ADT/PointerIntPair.h - Pair for pointer and int -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PointerIntPair class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ADT_POINTERINTPAIR_H
15 #define LLVM_ADT_POINTERINTPAIR_H
17 #include "llvm/Support/PointerLikeTypeTraits.h"
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
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.
39 template <typename PointerTy, unsigned IntBits, typename IntType=unsigned,
40 typename PtrTraits = PointerLikeTypeTraits<PointerTy> >
41 class PointerIntPair {
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
48 IntShift = PtrTraits::NumLowBitsAvailable-IntBits,
50 /// IntMask - This is the unshifted mask for valid bits of the int type.
51 IntMask = ((intptr_t)1 << IntBits)-1,
53 // ShiftedIntMask - This is the bits for the integer shifted in place.
54 ShiftedIntMask = IntMask << IntShift
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");
65 PointerTy getPointer() const {
66 return reinterpret_cast<PointerTy>(Value & PointerBitMask);
69 IntType getInt() const {
70 return (IntType)((Value >> IntShift) & IntMask);
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);
81 void setInt(IntType Int) {
82 intptr_t IntVal = Int;
83 assert(IntVal < (1 << IntBits) && "Integer too large for field");
85 // Preserve all bits other than the ones we are updating.
86 Value &= ~ShiftedIntMask; // Remove integer field.
87 Value |= IntVal << IntShift; // Set new integer.
90 void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
91 void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
93 static PointerIntPair getFromOpaqueValue(void *V) {
94 PointerIntPair P; P.setFromOpaqueValue(V); return P;
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;}
105 // Provide specialization of DenseMapInfo for PointerIntPair.
106 template<typename PointerTy, unsigned IntBits, typename IntType>
107 struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > {
108 typedef PointerIntPair<PointerTy, IntBits, IntType> Ty;
109 static Ty getEmptyKey() {
111 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
112 return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1));
114 static Ty getTombstoneKey() {
116 Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
117 return Ty(reinterpret_cast<PointerTy>(Val), IntType(0));
119 static unsigned getHashValue(Ty V) {
120 uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
121 return unsigned(IV) ^ unsigned(IV >> 9);
123 static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
124 static bool isPod() { return true; }
127 // Teach SmallPtrSet that PointerIntPair is "basically a pointer".
128 template<typename PointerTy, unsigned IntBits, typename IntType>
129 class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType> > {
132 getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
133 return P.getOpaqueValue();
135 static inline PointerIntPair<PointerTy, IntBits, IntType>
136 getFromVoidPointer(void *P) {
137 return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
140 NumLowBitsAvailable =
141 PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable - IntBits
145 } // end namespace llvm