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