1//===- llvm/ADT/PackedVector.h - Packed values vector -----------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file implements the PackedVector class.
11///
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_PACKEDVECTOR_H
15#define LLVM_ADT_PACKEDVECTOR_H
16
17#include "llvm/ADT/BitVector.h"
18#include <cassert>
19#include <limits>
20
21namespace llvm {
22
23template <typename T, unsigned BitNum, typename BitVectorTy, bool isSigned>
24class PackedVectorBase;
25
26// This won't be necessary if we can specialize members without specializing
27// the parent template.
28template <typename T, unsigned BitNum, typename BitVectorTy>
29class PackedVectorBase<T, BitNum, BitVectorTy, false> {
30protected:
31 static T getValue(const BitVectorTy &Bits, unsigned Idx) {
32 T val = T();
33 for (unsigned i = 0; i != BitNum; ++i)
34 val = T(val | ((Bits[(Idx << (BitNum-1)) + i] ? 1UL : 0UL) << i));
35 return val;
36 }
37
38 static void setValue(BitVectorTy &Bits, unsigned Idx, T val) {
39 assert((val >> BitNum) == 0 && "value is too big");
40 for (unsigned i = 0; i != BitNum; ++i)
41 Bits[(Idx << (BitNum-1)) + i] = val & (T(1) << i);
42 }
43};
44
45template <typename T, unsigned BitNum, typename BitVectorTy>
46class PackedVectorBase<T, BitNum, BitVectorTy, true> {
47protected:
48 static T getValue(const BitVectorTy &Bits, unsigned Idx) {
49 T val = T();
50 for (unsigned i = 0; i != BitNum-1; ++i)
51 val = T(val | ((Bits[(Idx << (BitNum-1)) + i] ? 1UL : 0UL) << i));
52 if (Bits[(Idx << (BitNum-1)) + BitNum-1])
53 val = ~val;
54 return val;
55 }
56
57 static void setValue(BitVectorTy &Bits, unsigned Idx, T val) {
58 if (val < 0) {
59 val = ~val;
60 Bits.set((Idx << (BitNum-1)) + BitNum-1);
61 }
62 assert((val >> (BitNum-1)) == 0 && "value is too big");
63 for (unsigned i = 0; i != BitNum-1; ++i)
64 Bits[(Idx << (BitNum-1)) + i] = val & (T(1) << i);
65 }
66};
67
68/// Store a vector of values using a specific number of bits for each
69/// value. Both signed and unsigned types can be used, e.g
70/// @code
71/// PackedVector<signed, 2> vec;
72/// @endcode
73/// will create a vector accepting values -2, -1, 0, 1. Any other value will hit
74/// an assertion.
75template <typename T, unsigned BitNum, typename BitVectorTy = BitVector>
76class PackedVector : public PackedVectorBase<T, BitNum, BitVectorTy,
77 std::numeric_limits<T>::is_signed> {
78 BitVectorTy Bits;
79 using base = PackedVectorBase<T, BitNum, BitVectorTy,
80 std::numeric_limits<T>::is_signed>;
81
82public:
83 class reference {
84 PackedVector &Vec;
85 const unsigned Idx;
86
87 public:
88 reference() = delete;
89 reference(PackedVector &vec, unsigned idx) : Vec(vec), Idx(idx) {}
90
91 reference &operator=(T val) {
92 Vec.setValue(Vec.Bits, Idx, val);
93 return *this;
94 }
95
96 operator T() const {
97 return Vec.getValue(Vec.Bits, Idx);
98 }
99 };
100
101 PackedVector() = default;
102 explicit PackedVector(unsigned size) : Bits(size << (BitNum-1)) {}
103
104 bool empty() const { return Bits.empty(); }
105
106 unsigned size() const { return Bits.size() >> (BitNum - 1); }
107
108 void clear() { Bits.clear(); }
109
110 void resize(unsigned N) { Bits.resize(N << (BitNum - 1)); }
111
112 void reserve(unsigned N) { Bits.reserve(N << (BitNum-1)); }
113
114 PackedVector &reset() {
115 Bits.reset();
116 return *this;
117 }
118
119 void push_back(T val) {
120 resize(N: size()+1);
121 (*this)[size()-1] = val;
122 }
123
124 reference operator[](unsigned Idx) {
125 return reference(*this, Idx);
126 }
127
128 T operator[](unsigned Idx) const {
129 return base::getValue(Bits, Idx);
130 }
131
132 bool operator==(const PackedVector &RHS) const {
133 return Bits == RHS.Bits;
134 }
135
136 bool operator!=(const PackedVector &RHS) const {
137 return Bits != RHS.Bits;
138 }
139
140 PackedVector &operator|=(const PackedVector &RHS) {
141 Bits |= RHS.Bits;
142 return *this;
143 }
144};
145
146// Leave BitNum=0 undefined.
147template <typename T> class PackedVector<T, 0>;
148
149} // end namespace llvm
150
151#endif // LLVM_ADT_PACKEDVECTOR_H
152

source code of llvm/include/llvm/ADT/PackedVector.h