/home/arjun/llvm-project/llvm/include/llvm/Support/Alignment.h
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1 | | //===-- llvm/Support/Alignment.h - Useful alignment functions ---*- 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 contains types to represent alignments. |
10 | | // They are instrumented to guarantee some invariants are preserved and prevent |
11 | | // invalid manipulations. |
12 | | // |
13 | | // - Align represents an alignment in bytes, it is always set and always a valid |
14 | | // power of two, its minimum value is 1 which means no alignment requirements. |
15 | | // |
16 | | // - MaybeAlign is an optional type, it may be undefined or set. When it's set |
17 | | // you can get the underlying Align type by using the getValue() method. |
18 | | // |
19 | | //===----------------------------------------------------------------------===// |
20 | | |
21 | | #ifndef LLVM_SUPPORT_ALIGNMENT_H_ |
22 | | #define LLVM_SUPPORT_ALIGNMENT_H_ |
23 | | |
24 | | #include "llvm/ADT/Optional.h" |
25 | | #include "llvm/Support/MathExtras.h" |
26 | | #include <cassert> |
27 | | #ifndef NDEBUG |
28 | | #include <string> |
29 | | #endif // NDEBUG |
30 | | |
31 | | namespace llvm { |
32 | | |
33 | | #define ALIGN_CHECK_ISPOSITIVE(decl) \ |
34 | | assert(decl > 0 && (#decl " should be defined")) |
35 | | |
36 | | /// This struct is a compact representation of a valid (non-zero power of two) |
37 | | /// alignment. |
38 | | /// It is suitable for use as static global constants. |
39 | | struct Align { |
40 | | private: |
41 | | uint8_t ShiftValue = 0; /// The log2 of the required alignment. |
42 | | /// ShiftValue is less than 64 by construction. |
43 | | |
44 | | friend struct MaybeAlign; |
45 | | friend unsigned Log2(Align); |
46 | | friend bool operator==(Align Lhs, Align Rhs); |
47 | | friend bool operator!=(Align Lhs, Align Rhs); |
48 | | friend bool operator<=(Align Lhs, Align Rhs); |
49 | | friend bool operator>=(Align Lhs, Align Rhs); |
50 | | friend bool operator<(Align Lhs, Align Rhs); |
51 | | friend bool operator>(Align Lhs, Align Rhs); |
52 | | friend unsigned encode(struct MaybeAlign A); |
53 | | friend struct MaybeAlign decodeMaybeAlign(unsigned Value); |
54 | | |
55 | | /// A trivial type to allow construction of constexpr Align. |
56 | | /// This is currently needed to workaround a bug in GCC 5.3 which prevents |
57 | | /// definition of constexpr assign operators. |
58 | | /// https://stackoverflow.com/questions/46756288/explicitly-defaulted-function-cannot-be-declared-as-constexpr-because-the-implic |
59 | | /// FIXME: Remove this, make all assign operators constexpr and introduce user |
60 | | /// defined literals when we don't have to support GCC 5.3 anymore. |
61 | | /// https://llvm.org/docs/GettingStarted.html#getting-a-modern-host-c-toolchain |
62 | | struct LogValue { |
63 | | uint8_t Log; |
64 | | }; |
65 | | |
66 | | public: |
67 | | /// Default is byte-aligned. |
68 | | constexpr Align() = default; |
69 | | /// Do not perform checks in case of copy/move construct/assign, because the |
70 | | /// checks have been performed when building `Other`. |
71 | | constexpr Align(const Align &Other) = default; |
72 | | constexpr Align(Align &&Other) = default; |
73 | | Align &operator=(const Align &Other) = default; |
74 | | Align &operator=(Align &&Other) = default; |
75 | | |
76 | 0 | explicit Align(uint64_t Value) { |
77 | 0 | assert(Value > 0 && "Value must not be 0"); |
78 | 0 | assert(llvm::isPowerOf2_64(Value) && "Alignment is not a power of 2"); |
79 | 0 | ShiftValue = Log2_64(Value); |
80 | 0 | assert(ShiftValue < 64 && "Broken invariant"); |
81 | 0 | } |
82 | | |
83 | | /// This is a hole in the type system and should not be abused. |
84 | | /// Needed to interact with C for instance. |
85 | 0 | uint64_t value() const { return uint64_t(1) << ShiftValue; } |
86 | | |
87 | | /// Returns a default constructed Align which corresponds to no alignment. |
88 | | /// It was decided to deprecate Align::None because it's too close to |
89 | | /// llvm::None which can be used to initialize `MaybeAlign`. |
90 | | /// MaybeAlign = llvm::None means unspecified alignment, |
91 | | /// Align = Align::None() means alignment of one byte. |
92 | | LLVM_ATTRIBUTE_DEPRECATED(constexpr static const Align None(), |
93 | 0 | "Use Align() or Align(1) instead") { |
94 | 0 | return Align(); |
95 | 0 | } |
96 | | |
97 | | /// Allow constructions of constexpr Align. |
98 | 0 | template <size_t kValue> constexpr static LogValue Constant() { |
99 | 0 | return LogValue{static_cast<uint8_t>(CTLog2<kValue>())}; |
100 | 0 | } |
101 | | |
102 | | /// Allow constructions of constexpr Align from types. |
103 | | /// Compile time equivalent to Align(alignof(T)). |
104 | 0 | template <typename T> constexpr static LogValue Of() { |
105 | 0 | return Constant<std::alignment_of<T>::value>(); |
106 | 0 | } Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir9OpOperandEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir6RegionEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir12BlockOperandEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir6detail16TrailingOpResultEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir6detail14InLineOpResultEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir6detail14OperandStorageEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfISt4pairIN4mlir10IdentifierENS3_9AttributeEEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfImEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir17FlatSymbolRefAttrEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir8LocationEEENS0_8LogValueEv Unexecuted instantiation: _ZN4llvm5Align2OfIN4mlir4TypeEEENS0_8LogValueEv |
107 | | |
108 | | /// Constexpr constructor from LogValue type. |
109 | 0 | constexpr Align(LogValue CA) : ShiftValue(CA.Log) {} |
110 | | }; |
111 | | |
112 | | /// Treats the value 0 as a 1, so Align is always at least 1. |
113 | 0 | inline Align assumeAligned(uint64_t Value) { |
114 | 0 | return Value ? Align(Value) : Align(); |
115 | 0 | } |
116 | | |
117 | | /// This struct is a compact representation of a valid (power of two) or |
118 | | /// undefined (0) alignment. |
119 | | struct MaybeAlign : public llvm::Optional<Align> { |
120 | | private: |
121 | | using UP = llvm::Optional<Align>; |
122 | | |
123 | | public: |
124 | | /// Default is undefined. |
125 | | MaybeAlign() = default; |
126 | | /// Do not perform checks in case of copy/move construct/assign, because the |
127 | | /// checks have been performed when building `Other`. |
128 | | MaybeAlign(const MaybeAlign &Other) = default; |
129 | | MaybeAlign &operator=(const MaybeAlign &Other) = default; |
130 | | MaybeAlign(MaybeAlign &&Other) = default; |
131 | | MaybeAlign &operator=(MaybeAlign &&Other) = default; |
132 | | |
133 | | /// Use llvm::Optional<Align> constructor. |
134 | | using UP::UP; |
135 | | |
136 | 0 | explicit MaybeAlign(uint64_t Value) { |
137 | 0 | assert((Value == 0 || llvm::isPowerOf2_64(Value)) && |
138 | 0 | "Alignment is neither 0 nor a power of 2"); |
139 | 0 | if (Value) |
140 | 0 | emplace(Value); |
141 | 0 | } |
142 | | |
143 | | /// For convenience, returns a valid alignment or 1 if undefined. |
144 | 0 | Align valueOrOne() const { return hasValue() ? getValue() : Align(); } |
145 | | }; |
146 | | |
147 | | /// Checks that SizeInBytes is a multiple of the alignment. |
148 | 0 | inline bool isAligned(Align Lhs, uint64_t SizeInBytes) { |
149 | 0 | return SizeInBytes % Lhs.value() == 0; |
150 | 0 | } |
151 | | |
152 | | /// Checks that Addr is a multiple of the alignment. |
153 | 0 | inline bool isAddrAligned(Align Lhs, const void *Addr) { |
154 | 0 | return isAligned(Lhs, reinterpret_cast<uintptr_t>(Addr)); |
155 | 0 | } |
156 | | |
157 | | /// Returns a multiple of A needed to store `Size` bytes. |
158 | 0 | inline uint64_t alignTo(uint64_t Size, Align A) { |
159 | 0 | const uint64_t Value = A.value(); |
160 | 0 | // The following line is equivalent to `(Size + Value - 1) / Value * Value`. |
161 | 0 |
|
162 | 0 | // The division followed by a multiplication can be thought of as a right |
163 | 0 | // shift followed by a left shift which zeros out the extra bits produced in |
164 | 0 | // the bump; `~(Value - 1)` is a mask where all those bits being zeroed out |
165 | 0 | // are just zero. |
166 | 0 |
|
167 | 0 | // Most compilers can generate this code but the pattern may be missed when |
168 | 0 | // multiple functions gets inlined. |
169 | 0 | return (Size + Value - 1) & ~(Value - 1U); |
170 | 0 | } |
171 | | |
172 | | /// If non-zero \p Skew is specified, the return value will be a minimal integer |
173 | | /// that is greater than or equal to \p Size and equal to \p A * N + \p Skew for |
174 | | /// some integer N. If \p Skew is larger than \p A, its value is adjusted to '\p |
175 | | /// Skew mod \p A'. |
176 | | /// |
177 | | /// Examples: |
178 | | /// \code |
179 | | /// alignTo(5, Align(8), 7) = 7 |
180 | | /// alignTo(17, Align(8), 1) = 17 |
181 | | /// alignTo(~0LL, Align(8), 3) = 3 |
182 | | /// \endcode |
183 | 0 | inline uint64_t alignTo(uint64_t Size, Align A, uint64_t Skew) { |
184 | 0 | const uint64_t Value = A.value(); |
185 | 0 | Skew %= Value; |
186 | 0 | return ((Size + Value - 1 - Skew) & ~(Value - 1U)) + Skew; |
187 | 0 | } |
188 | | |
189 | | /// Returns a multiple of A needed to store `Size` bytes. |
190 | | /// Returns `Size` if current alignment is undefined. |
191 | 0 | inline uint64_t alignTo(uint64_t Size, MaybeAlign A) { |
192 | 0 | return A ? alignTo(Size, A.getValue()) : Size; |
193 | 0 | } |
194 | | |
195 | | /// Aligns `Addr` to `Alignment` bytes, rounding up. |
196 | 0 | inline uintptr_t alignAddr(const void *Addr, Align Alignment) { |
197 | 0 | uintptr_t ArithAddr = reinterpret_cast<uintptr_t>(Addr); |
198 | 0 | assert(static_cast<uintptr_t>(ArithAddr + Alignment.value() - 1) >= |
199 | 0 | ArithAddr && |
200 | 0 | "Overflow"); |
201 | 0 | return alignTo(ArithAddr, Alignment); |
202 | 0 | } |
203 | | |
204 | | /// Returns the offset to the next integer (mod 2**64) that is greater than |
205 | | /// or equal to \p Value and is a multiple of \p Align. |
206 | 0 | inline uint64_t offsetToAlignment(uint64_t Value, Align Alignment) { |
207 | 0 | return alignTo(Value, Alignment) - Value; |
208 | 0 | } |
209 | | |
210 | | /// Returns the necessary adjustment for aligning `Addr` to `Alignment` |
211 | | /// bytes, rounding up. |
212 | 0 | inline uint64_t offsetToAlignedAddr(const void *Addr, Align Alignment) { |
213 | 0 | return offsetToAlignment(reinterpret_cast<uintptr_t>(Addr), Alignment); |
214 | 0 | } |
215 | | |
216 | | /// Returns the log2 of the alignment. |
217 | 0 | inline unsigned Log2(Align A) { return A.ShiftValue; } |
218 | | |
219 | | /// Returns the alignment that satisfies both alignments. |
220 | | /// Same semantic as MinAlign. |
221 | 0 | inline Align commonAlignment(Align A, Align B) { return std::min(A, B); } |
222 | | |
223 | | /// Returns the alignment that satisfies both alignments. |
224 | | /// Same semantic as MinAlign. |
225 | 0 | inline Align commonAlignment(Align A, uint64_t Offset) { |
226 | 0 | return Align(MinAlign(A.value(), Offset)); |
227 | 0 | } |
228 | | |
229 | | /// Returns the alignment that satisfies both alignments. |
230 | | /// Same semantic as MinAlign. |
231 | 0 | inline MaybeAlign commonAlignment(MaybeAlign A, MaybeAlign B) { |
232 | 0 | return A && B ? commonAlignment(*A, *B) : A ? A : B; |
233 | 0 | } |
234 | | |
235 | | /// Returns the alignment that satisfies both alignments. |
236 | | /// Same semantic as MinAlign. |
237 | 0 | inline MaybeAlign commonAlignment(MaybeAlign A, uint64_t Offset) { |
238 | 0 | return MaybeAlign(MinAlign((*A).value(), Offset)); |
239 | 0 | } |
240 | | |
241 | | /// Returns a representation of the alignment that encodes undefined as 0. |
242 | 0 | inline unsigned encode(MaybeAlign A) { return A ? A->ShiftValue + 1 : 0; } |
243 | | |
244 | | /// Dual operation of the encode function above. |
245 | 0 | inline MaybeAlign decodeMaybeAlign(unsigned Value) { |
246 | 0 | if (Value == 0) |
247 | 0 | return MaybeAlign(); |
248 | 0 | Align Out; |
249 | 0 | Out.ShiftValue = Value - 1; |
250 | 0 | return Out; |
251 | 0 | } |
252 | | |
253 | | /// Returns a representation of the alignment, the encoded value is positive by |
254 | | /// definition. |
255 | 0 | inline unsigned encode(Align A) { return encode(MaybeAlign(A)); } |
256 | | |
257 | | /// Comparisons between Align and scalars. Rhs must be positive. |
258 | 0 | inline bool operator==(Align Lhs, uint64_t Rhs) { |
259 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
260 | 0 | return Lhs.value() == Rhs; |
261 | 0 | } |
262 | 0 | inline bool operator!=(Align Lhs, uint64_t Rhs) { |
263 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
264 | 0 | return Lhs.value() != Rhs; |
265 | 0 | } |
266 | 0 | inline bool operator<=(Align Lhs, uint64_t Rhs) { |
267 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
268 | 0 | return Lhs.value() <= Rhs; |
269 | 0 | } |
270 | 0 | inline bool operator>=(Align Lhs, uint64_t Rhs) { |
271 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
272 | 0 | return Lhs.value() >= Rhs; |
273 | 0 | } |
274 | 0 | inline bool operator<(Align Lhs, uint64_t Rhs) { |
275 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
276 | 0 | return Lhs.value() < Rhs; |
277 | 0 | } |
278 | 0 | inline bool operator>(Align Lhs, uint64_t Rhs) { |
279 | 0 | ALIGN_CHECK_ISPOSITIVE(Rhs); |
280 | 0 | return Lhs.value() > Rhs; |
281 | 0 | } |
282 | | |
283 | | /// Comparisons between MaybeAlign and scalars. |
284 | 0 | inline bool operator==(MaybeAlign Lhs, uint64_t Rhs) { |
285 | 0 | return Lhs ? (*Lhs).value() == Rhs : Rhs == 0; |
286 | 0 | } |
287 | 0 | inline bool operator!=(MaybeAlign Lhs, uint64_t Rhs) { |
288 | 0 | return Lhs ? (*Lhs).value() != Rhs : Rhs != 0; |
289 | 0 | } |
290 | | |
291 | | /// Comparisons operators between Align. |
292 | 0 | inline bool operator==(Align Lhs, Align Rhs) { |
293 | 0 | return Lhs.ShiftValue == Rhs.ShiftValue; |
294 | 0 | } |
295 | 0 | inline bool operator!=(Align Lhs, Align Rhs) { |
296 | 0 | return Lhs.ShiftValue != Rhs.ShiftValue; |
297 | 0 | } |
298 | 0 | inline bool operator<=(Align Lhs, Align Rhs) { |
299 | 0 | return Lhs.ShiftValue <= Rhs.ShiftValue; |
300 | 0 | } |
301 | 0 | inline bool operator>=(Align Lhs, Align Rhs) { |
302 | 0 | return Lhs.ShiftValue >= Rhs.ShiftValue; |
303 | 0 | } |
304 | 0 | inline bool operator<(Align Lhs, Align Rhs) { |
305 | 0 | return Lhs.ShiftValue < Rhs.ShiftValue; |
306 | 0 | } |
307 | 0 | inline bool operator>(Align Lhs, Align Rhs) { |
308 | 0 | return Lhs.ShiftValue > Rhs.ShiftValue; |
309 | 0 | } |
310 | | |
311 | | // Don't allow relational comparisons with MaybeAlign. |
312 | | bool operator<=(Align Lhs, MaybeAlign Rhs) = delete; |
313 | | bool operator>=(Align Lhs, MaybeAlign Rhs) = delete; |
314 | | bool operator<(Align Lhs, MaybeAlign Rhs) = delete; |
315 | | bool operator>(Align Lhs, MaybeAlign Rhs) = delete; |
316 | | |
317 | | bool operator<=(MaybeAlign Lhs, Align Rhs) = delete; |
318 | | bool operator>=(MaybeAlign Lhs, Align Rhs) = delete; |
319 | | bool operator<(MaybeAlign Lhs, Align Rhs) = delete; |
320 | | bool operator>(MaybeAlign Lhs, Align Rhs) = delete; |
321 | | |
322 | | bool operator<=(MaybeAlign Lhs, MaybeAlign Rhs) = delete; |
323 | | bool operator>=(MaybeAlign Lhs, MaybeAlign Rhs) = delete; |
324 | | bool operator<(MaybeAlign Lhs, MaybeAlign Rhs) = delete; |
325 | | bool operator>(MaybeAlign Lhs, MaybeAlign Rhs) = delete; |
326 | | |
327 | 0 | inline Align operator*(Align Lhs, uint64_t Rhs) { |
328 | 0 | assert(Rhs > 0 && "Rhs must be positive"); |
329 | 0 | return Align(Lhs.value() * Rhs); |
330 | 0 | } |
331 | | |
332 | 0 | inline MaybeAlign operator*(MaybeAlign Lhs, uint64_t Rhs) { |
333 | 0 | assert(Rhs > 0 && "Rhs must be positive"); |
334 | 0 | return Lhs ? Lhs.getValue() * Rhs : MaybeAlign(); |
335 | 0 | } |
336 | | |
337 | 0 | inline Align operator/(Align Lhs, uint64_t Divisor) { |
338 | 0 | assert(llvm::isPowerOf2_64(Divisor) && |
339 | 0 | "Divisor must be positive and a power of 2"); |
340 | 0 | assert(Lhs != 1 && "Can't halve byte alignment"); |
341 | 0 | return Align(Lhs.value() / Divisor); |
342 | 0 | } |
343 | | |
344 | 0 | inline MaybeAlign operator/(MaybeAlign Lhs, uint64_t Divisor) { |
345 | 0 | assert(llvm::isPowerOf2_64(Divisor) && |
346 | 0 | "Divisor must be positive and a power of 2"); |
347 | 0 | return Lhs ? Lhs.getValue() / Divisor : MaybeAlign(); |
348 | 0 | } |
349 | | |
350 | 0 | inline Align max(MaybeAlign Lhs, Align Rhs) { |
351 | 0 | return Lhs && *Lhs > Rhs ? *Lhs : Rhs; |
352 | 0 | } |
353 | | |
354 | 0 | inline Align max(Align Lhs, MaybeAlign Rhs) { |
355 | 0 | return Rhs && *Rhs > Lhs ? *Rhs : Lhs; |
356 | 0 | } |
357 | | |
358 | | #ifndef NDEBUG |
359 | | // For usage in LLVM_DEBUG macros. |
360 | 0 | inline std::string DebugStr(const Align &A) { |
361 | 0 | return std::to_string(A.value()); |
362 | 0 | } |
363 | | // For usage in LLVM_DEBUG macros. |
364 | 0 | inline std::string DebugStr(const MaybeAlign &MA) { |
365 | 0 | if (MA) |
366 | 0 | return std::to_string(MA->value()); |
367 | 0 | return "None"; |
368 | 0 | } |
369 | | #endif // NDEBUG |
370 | | |
371 | | #undef ALIGN_CHECK_ISPOSITIVE |
372 | | |
373 | | } // namespace llvm |
374 | | |
375 | | #endif // LLVM_SUPPORT_ALIGNMENT_H_ |