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//===- llvm/ADT/PackedVector.h - Packed values vector -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the PackedVector class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_PACKEDVECTOR_H
#define LLVM_ADT_PACKEDVECTOR_H
#include "llvm/ADT/BitVector.h"
#include <cassert>
#include <limits>
namespace llvm {
template <typename T, unsigned BitNum, typename BitVectorTy, bool isSigned>
class PackedVectorBase;
// This won't be necessary if we can specialize members without specializing
// the parent template.
template <typename T, unsigned BitNum, typename BitVectorTy>
class PackedVectorBase<T, BitNum, BitVectorTy, false> {
protected:
static T getValue(const BitVectorTy &Bits, unsigned Idx) {
T val = T();
for (unsigned i = 0; i != BitNum; ++i)
val = T(val | ((Bits[(Idx << (BitNum-1)) + i] ? 1UL : 0UL) << i));
return val;
}
static void setValue(BitVectorTy &Bits, unsigned Idx, T val) {
assert((val >> BitNum) == 0 && "value is too big");
for (unsigned i = 0; i != BitNum; ++i)
Bits[(Idx << (BitNum-1)) + i] = val & (T(1) << i);
}
};
template <typename T, unsigned BitNum, typename BitVectorTy>
class PackedVectorBase<T, BitNum, BitVectorTy, true> {
protected:
static T getValue(const BitVectorTy &Bits, unsigned Idx) {
T val = T();
for (unsigned i = 0; i != BitNum-1; ++i)
val = T(val | ((Bits[(Idx << (BitNum-1)) + i] ? 1UL : 0UL) << i));
if (Bits[(Idx << (BitNum-1)) + BitNum-1])
val = ~val;
return val;
}
static void setValue(BitVectorTy &Bits, unsigned Idx, T val) {
if (val < 0) {
val = ~val;
Bits.set((Idx << (BitNum-1)) + BitNum-1);
}
assert((val >> (BitNum-1)) == 0 && "value is too big");
for (unsigned i = 0; i != BitNum-1; ++i)
Bits[(Idx << (BitNum-1)) + i] = val & (T(1) << i);
}
};
/// Store a vector of values using a specific number of bits for each
/// value. Both signed and unsigned types can be used, e.g
/// @code
/// PackedVector<signed, 2> vec;
/// @endcode
/// will create a vector accepting values -2, -1, 0, 1. Any other value will hit
/// an assertion.
template <typename T, unsigned BitNum, typename BitVectorTy = BitVector>
class PackedVector : public PackedVectorBase<T, BitNum, BitVectorTy,
std::numeric_limits<T>::is_signed> {
BitVectorTy Bits;
using base = PackedVectorBase<T, BitNum, BitVectorTy,
std::numeric_limits<T>::is_signed>;
public:
class reference {
PackedVector &Vec;
const unsigned Idx;
public:
reference() = delete;
reference(PackedVector &vec, unsigned idx) : Vec(vec), Idx(idx) {}
reference &operator=(T val) {
Vec.setValue(Vec.Bits, Idx, val);
return *this;
}
operator T() const {
return Vec.getValue(Vec.Bits, Idx);
}
};
PackedVector() = default;
explicit PackedVector(unsigned size) : Bits(size << (BitNum-1)) {}
bool empty() const { return Bits.empty(); }
unsigned size() const { return Bits.size() >> (BitNum - 1); }
void clear() { Bits.clear(); }
void resize(unsigned N) { Bits.resize(N << (BitNum - 1)); }
void reserve(unsigned N) { Bits.reserve(N << (BitNum-1)); }
PackedVector &reset() {
Bits.reset();
return *this;
}
void push_back(T val) {
resize(size()+1);
(*this)[size()-1] = val;
}
reference operator[](unsigned Idx) {
return reference(*this, Idx);
}
T operator[](unsigned Idx) const {
return base::getValue(Bits, Idx);
}
bool operator==(const PackedVector &RHS) const {
return Bits == RHS.Bits;
}
bool operator!=(const PackedVector &RHS) const {
return Bits != RHS.Bits;
}
PackedVector &operator|=(const PackedVector &RHS) {
Bits |= RHS.Bits;
return *this;
}
};
// Leave BitNum=0 undefined.
template <typename T> class PackedVector<T, 0>;
} // end namespace llvm
#endif // LLVM_ADT_PACKEDVECTOR_H
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