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 21 namespace 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(Quantity, 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(Quantity, 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(elementSize); 219 } 220 221 222 }; // class CharUnit 223 } // namespace clang 224 225 inline clang::CharUnits operator* (clang::CharUnits::QuantityType Scale, 226 const clang::CharUnits &CU) { 227 return CU * Scale; 228 } 229 230 namespace llvm { 231 232 template<> 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(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