freebsd-dev/include/llvm/ADT/PointerIntPair.h
2009-12-15 18:09:07 +00:00

157 lines
5.9 KiB
C++

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