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allow the traits to be specified as well. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68055 91177308-0d34-0410-b5e6-96231b3b80d8
149 lines
5.6 KiB
C++
149 lines
5.6 KiB
C++
//===- llvm/ADT/PointerIntPair.h - Pair for pointer and int -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the PointerIntPair class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_POINTERINTPAIR_H
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#define LLVM_ADT_POINTERINTPAIR_H
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#include "llvm/Support/PointerLikeTypeTraits.h"
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#include <cassert>
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namespace llvm {
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template<typename T>
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struct DenseMapInfo;
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/// PointerIntPair - This class implements a pair of a pointer and small
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/// integer. It is designed to represent this in the space required by one
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/// pointer by bitmangling the integer into the low part of the pointer. This
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/// can only be done for small integers: typically up to 3 bits, but it depends
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/// on the number of bits available according to PointerLikeTypeTraits for the
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/// type.
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///
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/// Note that PointerIntPair always puts the Int part in the highest bits
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/// possible. For example, PointerIntPair<void*, 1, bool> will put the bit for
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/// the bool into bit #2, not bit #0, which allows the low two bits to be used
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/// for something else. For example, this allows:
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/// PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>
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/// ... and the two bools will land in different bits.
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///
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template <typename PointerTy, unsigned IntBits, typename IntType=unsigned,
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typename PtrTraits = PointerLikeTypeTraits<PointerTy> >
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class PointerIntPair {
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intptr_t Value;
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enum {
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/// PointerBitMask - The bits that come from the pointer.
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PointerBitMask = ~(((intptr_t)1 << PtrTraits::NumLowBitsAvailable)-1),
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/// IntShift - The number of low bits that we reserve for other uses, and
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/// keep zero.
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IntShift = PtrTraits::NumLowBitsAvailable-IntBits,
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/// IntMask - This is the unshifted mask for valid bits of the int type.
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IntMask = ((intptr_t)1 << IntBits)-1,
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// ShiftedIntMask - This is the bits for the integer shifted in place.
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ShiftedIntMask = IntMask << IntShift
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};
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public:
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PointerIntPair() : Value(0) {}
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PointerIntPair(PointerTy Ptr, IntType Int) : Value(0) {
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assert(IntBits <= PtrTraits::NumLowBitsAvailable &&
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"PointerIntPair formed with integer size too large for pointer");
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setPointer(Ptr);
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setInt(Int);
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}
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PointerTy getPointer() const {
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return reinterpret_cast<PointerTy>(Value & PointerBitMask);
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}
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IntType getInt() const {
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return (IntType)((Value >> IntShift) & IntMask);
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}
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void setPointer(PointerTy Ptr) {
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intptr_t PtrVal = reinterpret_cast<intptr_t>(Ptr);
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assert((PtrVal & ((1 << PtrTraits::NumLowBitsAvailable)-1)) == 0 &&
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"Pointer is not sufficiently aligned");
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// Preserve all low bits, just update the pointer.
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Value = PtrVal | (Value & ~PointerBitMask);
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}
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void setInt(IntType Int) {
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intptr_t IntVal = Int;
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assert(IntVal < (1 << IntBits) && "Integer too large for field");
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// Preserve all bits other than the ones we are updating.
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Value &= ~ShiftedIntMask; // Remove integer field.
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Value |= IntVal << IntShift; // Set new integer.
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}
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void *getOpaqueValue() const { return reinterpret_cast<void*>(Value); }
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void setFromOpaqueValue(void *Val) { Value = reinterpret_cast<intptr_t>(Val);}
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static PointerIntPair getFromOpaqueValue(void *V) {
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PointerIntPair P; P.setFromOpaqueValue(V); return P;
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}
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bool operator==(const PointerIntPair &RHS) const {return Value == RHS.Value;}
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bool operator!=(const PointerIntPair &RHS) const {return Value != RHS.Value;}
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bool operator<(const PointerIntPair &RHS) const {return Value < RHS.Value;}
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bool operator>(const PointerIntPair &RHS) const {return Value > RHS.Value;}
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bool operator<=(const PointerIntPair &RHS) const {return Value <= RHS.Value;}
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bool operator>=(const PointerIntPair &RHS) const {return Value >= RHS.Value;}
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};
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// Provide specialization of DenseMapInfo for PointerIntPair.
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template<typename PointerTy, unsigned IntBits, typename IntType>
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struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType> > {
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typedef PointerIntPair<PointerTy, IntBits, IntType> Ty;
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static Ty getEmptyKey() {
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intptr_t Val = -1;
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Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
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return Ty(reinterpret_cast<PointerTy>(Val), IntType((1 << IntBits)-1));
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}
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static Ty getTombstoneKey() {
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intptr_t Val = -2;
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Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;
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return Ty(reinterpret_cast<PointerTy>(Val), IntType(0));
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}
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static unsigned getHashValue(Ty V) {
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uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());
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return unsigned(IV) ^ unsigned(IV >> 9);
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}
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static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }
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static bool isPod() { return true; }
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};
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// Teach SmallPtrSet that PointerIntPair is "basically a pointer".
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template<typename PointerTy, unsigned IntBits, typename IntType,
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typename PtrTraits>
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class PointerLikeTypeTraits<PointerIntPair<PointerTy, IntBits, IntType,
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PtrTraits> > {
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public:
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static inline void *
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getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {
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return P.getOpaqueValue();
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}
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static inline PointerIntPair<PointerTy, IntBits, IntType>
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getFromVoidPointer(void *P) {
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return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);
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}
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enum {
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NumLowBitsAvailable =
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PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable - IntBits
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};
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};
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} // end namespace llvm
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#endif
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