1//===--- CharUnits.h - Character units for sizes and offsets ----*- 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// This file defines the CharUnits class
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_AST_CHARUNITS_H
14#define LLVM_CLANG_AST_CHARUNITS_H
15
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/Support/Alignment.h"
18#include "llvm/Support/DataTypes.h"
19#include "llvm/Support/MathExtras.h"
20
21namespace clang {
22
23 /// CharUnits - This is an opaque type for sizes expressed in character units.
24 /// Instances of this type represent a quantity as a multiple of the size
25 /// of the standard C type, char, on the target architecture. As an opaque
26 /// type, CharUnits protects you from accidentally combining operations on
27 /// quantities in bit units and character units.
28 ///
29 /// In both C and C++, an object of type 'char', 'signed char', or 'unsigned
30 /// char' occupies exactly one byte, so 'character unit' and 'byte' refer to
31 /// the same quantity of storage. However, we use the term 'character unit'
32 /// rather than 'byte' to avoid an implication that a character unit is
33 /// exactly 8 bits.
34 ///
35 /// For portability, never assume that a target character is 8 bits wide. Use
36 /// CharUnit values wherever you calculate sizes, offsets, or alignments
37 /// in character units.
38 class CharUnits {
39 public:
40 typedef int64_t QuantityType;
41
42 private:
43 QuantityType Quantity = 0;
44
45 explicit CharUnits(QuantityType C) : Quantity(C) {}
46
47 public:
48
49 /// CharUnits - A default constructor.
50 CharUnits() = default;
51
52 /// Zero - Construct a CharUnits quantity of zero.
53 static CharUnits Zero() {
54 return CharUnits(0);
55 }
56
57 /// One - Construct a CharUnits quantity of one.
58 static CharUnits One() {
59 return CharUnits(1);
60 }
61
62 /// fromQuantity - Construct a CharUnits quantity from a raw integer type.
63 static CharUnits fromQuantity(QuantityType Quantity) {
64 return CharUnits(Quantity);
65 }
66
67 /// fromQuantity - Construct a CharUnits quantity from an llvm::Align
68 /// quantity.
69 static CharUnits fromQuantity(llvm::Align Quantity) {
70 return CharUnits(Quantity.value());
71 }
72
73 // Compound assignment.
74 CharUnits& operator+= (const CharUnits &Other) {
75 Quantity += Other.Quantity;
76 return *this;
77 }
78 CharUnits& operator++ () {
79 ++Quantity;
80 return *this;
81 }
82 CharUnits operator++ (int) {
83 return CharUnits(Quantity++);
84 }
85 CharUnits& operator-= (const CharUnits &Other) {
86 Quantity -= Other.Quantity;
87 return *this;
88 }
89 CharUnits& operator-- () {
90 --Quantity;
91 return *this;
92 }
93 CharUnits operator-- (int) {
94 return CharUnits(Quantity--);
95 }
96
97 // Comparison operators.
98 bool operator== (const CharUnits &Other) const {
99 return Quantity == Other.Quantity;
100 }
101 bool operator!= (const CharUnits &Other) const {
102 return Quantity != Other.Quantity;
103 }
104
105 // Relational operators.
106 bool operator< (const CharUnits &Other) const {
107 return Quantity < Other.Quantity;
108 }
109 bool operator<= (const CharUnits &Other) const {
110 return Quantity <= Other.Quantity;
111 }
112 bool operator> (const CharUnits &Other) const {
113 return Quantity > Other.Quantity;
114 }
115 bool operator>= (const CharUnits &Other) const {
116 return Quantity >= Other.Quantity;
117 }
118
119 // Other predicates.
120
121 /// isZero - Test whether the quantity equals zero.
122 bool isZero() const { return Quantity == 0; }
123
124 /// isOne - Test whether the quantity equals one.
125 bool isOne() const { return Quantity == 1; }
126
127 /// isPositive - Test whether the quantity is greater than zero.
128 bool isPositive() const { return Quantity > 0; }
129
130 /// isNegative - Test whether the quantity is less than zero.
131 bool isNegative() const { return Quantity < 0; }
132
133 /// isPowerOfTwo - Test whether the quantity is a power of two.
134 /// Zero is not a power of two.
135 bool isPowerOfTwo() const {
136 return (Quantity & -Quantity) == Quantity;
137 }
138
139 /// Test whether this is a multiple of the other value.
140 ///
141 /// Among other things, this promises that
142 /// self.alignTo(N) will just return self.
143 bool isMultipleOf(CharUnits N) const {
144 return (*this % N) == 0;
145 }
146
147 // Arithmetic operators.
148 CharUnits operator* (QuantityType N) const {
149 return CharUnits(Quantity * N);
150 }
151 CharUnits &operator*= (QuantityType N) {
152 Quantity *= N;
153 return *this;
154 }
155 CharUnits operator/ (QuantityType N) const {
156 return CharUnits(Quantity / N);
157 }
158 CharUnits &operator/= (QuantityType N) {
159 Quantity /= N;
160 return *this;
161 }
162 QuantityType operator/ (const CharUnits &Other) const {
163 return Quantity / Other.Quantity;
164 }
165 CharUnits operator% (QuantityType N) const {
166 return CharUnits(Quantity % N);
167 }
168 QuantityType operator% (const CharUnits &Other) const {
169 return Quantity % Other.Quantity;
170 }
171 CharUnits operator+ (const CharUnits &Other) const {
172 return CharUnits(Quantity + Other.Quantity);
173 }
174 CharUnits operator- (const CharUnits &Other) const {
175 return CharUnits(Quantity - Other.Quantity);
176 }
177 CharUnits operator- () const {
178 return CharUnits(-Quantity);
179 }
180
181
182 // Conversions.
183
184 /// getQuantity - Get the raw integer representation of this quantity.
185 QuantityType getQuantity() const { return Quantity; }
186
187 /// getAsAlign - Returns Quantity as a valid llvm::Align,
188 /// Beware llvm::Align assumes power of two 8-bit bytes.
189 llvm::Align getAsAlign() const { return llvm::Align(Quantity); }
190
191 /// getAsMaybeAlign - Returns Quantity as a valid llvm::Align or
192 /// std::nullopt, Beware llvm::MaybeAlign assumes power of two 8-bit
193 /// bytes.
194 llvm::MaybeAlign getAsMaybeAlign() const {
195 return llvm::MaybeAlign(Quantity);
196 }
197
198 /// alignTo - Returns the next integer (mod 2**64) that is
199 /// greater than or equal to this quantity and is a multiple of \p Align.
200 /// Align must be non-zero.
201 CharUnits alignTo(const CharUnits &Align) const {
202 return CharUnits(llvm::alignTo(Value: Quantity, Align: Align.Quantity));
203 }
204
205 /// Given that this is a non-zero alignment value, what is the
206 /// alignment at the given offset?
207 CharUnits alignmentAtOffset(CharUnits offset) const {
208 assert(Quantity != 0 && "offsetting from unknown alignment?");
209 return CharUnits(llvm::MinAlign(A: Quantity, B: offset.Quantity));
210 }
211
212 /// Given that this is the alignment of the first element of an
213 /// array, return the minimum alignment of any element in the array.
214 CharUnits alignmentOfArrayElement(CharUnits elementSize) const {
215 // Since we don't track offsetted alignments, the alignment of
216 // the second element (or any odd element) will be minimally
217 // aligned.
218 return alignmentAtOffset(offset: elementSize);
219 }
220
221
222 }; // class CharUnit
223} // namespace clang
224
225inline clang::CharUnits operator* (clang::CharUnits::QuantityType Scale,
226 const clang::CharUnits &CU) {
227 return CU * Scale;
228}
229
230namespace llvm {
231
232template<> struct DenseMapInfo<clang::CharUnits> {
233 static clang::CharUnits getEmptyKey() {
234 clang::CharUnits::QuantityType Quantity =
235 DenseMapInfo<clang::CharUnits::QuantityType>::getEmptyKey();
236
237 return clang::CharUnits::fromQuantity(Quantity);
238 }
239
240 static clang::CharUnits getTombstoneKey() {
241 clang::CharUnits::QuantityType Quantity =
242 DenseMapInfo<clang::CharUnits::QuantityType>::getTombstoneKey();
243
244 return clang::CharUnits::fromQuantity(Quantity);
245 }
246
247 static unsigned getHashValue(const clang::CharUnits &CU) {
248 clang::CharUnits::QuantityType Quantity = CU.getQuantity();
249 return DenseMapInfo<clang::CharUnits::QuantityType>::getHashValue(Val: Quantity);
250 }
251
252 static bool isEqual(const clang::CharUnits &LHS,
253 const clang::CharUnits &RHS) {
254 return LHS == RHS;
255 }
256};
257
258} // end namespace llvm
259
260#endif // LLVM_CLANG_AST_CHARUNITS_H
261

source code of clang/include/clang/AST/CharUnits.h