LLVM 17.0.0git
Hashing.h
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1//===-- llvm/ADT/Hashing.h - Utilities for hashing --------------*- 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 implements the newly proposed standard C++ interfaces for hashing
10// arbitrary data and building hash functions for user-defined types. This
11// interface was originally proposed in N3333[1] and is currently under review
12// for inclusion in a future TR and/or standard.
13//
14// The primary interfaces provide are comprised of one type and three functions:
15//
16// -- 'hash_code' class is an opaque type representing the hash code for some
17// data. It is the intended product of hashing, and can be used to implement
18// hash tables, checksumming, and other common uses of hashes. It is not an
19// integer type (although it can be converted to one) because it is risky
20// to assume much about the internals of a hash_code. In particular, each
21// execution of the program has a high probability of producing a different
22// hash_code for a given input. Thus their values are not stable to save or
23// persist, and should only be used during the execution for the
24// construction of hashing datastructures.
25//
26// -- 'hash_value' is a function designed to be overloaded for each
27// user-defined type which wishes to be used within a hashing context. It
28// should be overloaded within the user-defined type's namespace and found
29// via ADL. Overloads for primitive types are provided by this library.
30//
31// -- 'hash_combine' and 'hash_combine_range' are functions designed to aid
32// programmers in easily and intuitively combining a set of data into
33// a single hash_code for their object. They should only logically be used
34// within the implementation of a 'hash_value' routine or similar context.
35//
36// Note that 'hash_combine_range' contains very special logic for hashing
37// a contiguous array of integers or pointers. This logic is *extremely* fast,
38// on a modern Intel "Gainestown" Xeon (Nehalem uarch) @2.2 GHz, these were
39// benchmarked at over 6.5 GiB/s for large keys, and <20 cycles/hash for keys
40// under 32-bytes.
41//
42//===----------------------------------------------------------------------===//
43
44#ifndef LLVM_ADT_HASHING_H
45#define LLVM_ADT_HASHING_H
46
51#include <algorithm>
52#include <cassert>
53#include <cstring>
54#include <optional>
55#include <string>
56#include <tuple>
57#include <utility>
58
59namespace llvm {
60template <typename T, typename Enable> struct DenseMapInfo;
61
62/// An opaque object representing a hash code.
63///
64/// This object represents the result of hashing some entity. It is intended to
65/// be used to implement hashtables or other hashing-based data structures.
66/// While it wraps and exposes a numeric value, this value should not be
67/// trusted to be stable or predictable across processes or executions.
68///
69/// In order to obtain the hash_code for an object 'x':
70/// \code
71/// using llvm::hash_value;
72/// llvm::hash_code code = hash_value(x);
73/// \endcode
74class hash_code {
75 size_t value;
76
77public:
78 /// Default construct a hash_code.
79 /// Note that this leaves the value uninitialized.
80 hash_code() = default;
81
82 /// Form a hash code directly from a numerical value.
83 hash_code(size_t value) : value(value) {}
84
85 /// Convert the hash code to its numerical value for use.
86 /*explicit*/ operator size_t() const { return value; }
87
88 friend bool operator==(const hash_code &lhs, const hash_code &rhs) {
89 return lhs.value == rhs.value;
90 }
91 friend bool operator!=(const hash_code &lhs, const hash_code &rhs) {
92 return lhs.value != rhs.value;
93 }
94
95 /// Allow a hash_code to be directly run through hash_value.
96 friend size_t hash_value(const hash_code &code) { return code.value; }
97};
98
99/// Compute a hash_code for any integer value.
100///
101/// Note that this function is intended to compute the same hash_code for
102/// a particular value without regard to the pre-promotion type. This is in
103/// contrast to hash_combine which may produce different hash_codes for
104/// differing argument types even if they would implicit promote to a common
105/// type without changing the value.
106template <typename T>
107std::enable_if_t<is_integral_or_enum<T>::value, hash_code> hash_value(T value);
108
109/// Compute a hash_code for a pointer's address.
110///
111/// N.B.: This hashes the *address*. Not the value and not the type.
112template <typename T> hash_code hash_value(const T *ptr);
113
114/// Compute a hash_code for a pair of objects.
115template <typename T, typename U>
116hash_code hash_value(const std::pair<T, U> &arg);
117
118/// Compute a hash_code for a tuple.
119template <typename... Ts>
120hash_code hash_value(const std::tuple<Ts...> &arg);
121
122/// Compute a hash_code for a standard string.
123template <typename T>
124hash_code hash_value(const std::basic_string<T> &arg);
125
126/// Compute a hash_code for a standard string.
127template <typename T> hash_code hash_value(const std::optional<T> &arg);
128
129/// Override the execution seed with a fixed value.
130///
131/// This hashing library uses a per-execution seed designed to change on each
132/// run with high probability in order to ensure that the hash codes are not
133/// attackable and to ensure that output which is intended to be stable does
134/// not rely on the particulars of the hash codes produced.
135///
136/// That said, there are use cases where it is important to be able to
137/// reproduce *exactly* a specific behavior. To that end, we provide a function
138/// which will forcibly set the seed to a fixed value. This must be done at the
139/// start of the program, before any hashes are computed. Also, it cannot be
140/// undone. This makes it thread-hostile and very hard to use outside of
141/// immediately on start of a simple program designed for reproducible
142/// behavior.
144
145
146// All of the implementation details of actually computing the various hash
147// code values are held within this namespace. These routines are included in
148// the header file mainly to allow inlining and constant propagation.
149namespace hashing {
150namespace detail {
151
152inline uint64_t fetch64(const char *p) {
153 uint64_t result;
154 memcpy(&result, p, sizeof(result));
156 sys::swapByteOrder(result);
157 return result;
158}
159
160inline uint32_t fetch32(const char *p) {
161 uint32_t result;
162 memcpy(&result, p, sizeof(result));
164 sys::swapByteOrder(result);
165 return result;
166}
167
168/// Some primes between 2^63 and 2^64 for various uses.
169static constexpr uint64_t k0 = 0xc3a5c85c97cb3127ULL;
170static constexpr uint64_t k1 = 0xb492b66fbe98f273ULL;
171static constexpr uint64_t k2 = 0x9ae16a3b2f90404fULL;
172static constexpr uint64_t k3 = 0xc949d7c7509e6557ULL;
173
174/// Bitwise right rotate.
175/// Normally this will compile to a single instruction, especially if the
176/// shift is a manifest constant.
177inline uint64_t rotate(uint64_t val, size_t shift) {
178 // Avoid shifting by 64: doing so yields an undefined result.
179 return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));
180}
181
183 return val ^ (val >> 47);
184}
185
187 // Murmur-inspired hashing.
188 const uint64_t kMul = 0x9ddfea08eb382d69ULL;
189 uint64_t a = (low ^ high) * kMul;
190 a ^= (a >> 47);
191 uint64_t b = (high ^ a) * kMul;
192 b ^= (b >> 47);
193 b *= kMul;
194 return b;
195}
196
197inline uint64_t hash_1to3_bytes(const char *s, size_t len, uint64_t seed) {
198 uint8_t a = s[0];
199 uint8_t b = s[len >> 1];
200 uint8_t c = s[len - 1];
201 uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
202 uint32_t z = static_cast<uint32_t>(len) + (static_cast<uint32_t>(c) << 2);
203 return shift_mix(y * k2 ^ z * k3 ^ seed) * k2;
204}
205
206inline uint64_t hash_4to8_bytes(const char *s, size_t len, uint64_t seed) {
207 uint64_t a = fetch32(s);
208 return hash_16_bytes(len + (a << 3), seed ^ fetch32(s + len - 4));
209}
210
211inline uint64_t hash_9to16_bytes(const char *s, size_t len, uint64_t seed) {
212 uint64_t a = fetch64(s);
213 uint64_t b = fetch64(s + len - 8);
214 return hash_16_bytes(seed ^ a, rotate(b + len, len)) ^ b;
215}
216
217inline uint64_t hash_17to32_bytes(const char *s, size_t len, uint64_t seed) {
218 uint64_t a = fetch64(s) * k1;
219 uint64_t b = fetch64(s + 8);
220 uint64_t c = fetch64(s + len - 8) * k2;
221 uint64_t d = fetch64(s + len - 16) * k0;
222 return hash_16_bytes(rotate(a - b, 43) + rotate(c ^ seed, 30) + d,
223 a + rotate(b ^ k3, 20) - c + len + seed);
224}
225
226inline uint64_t hash_33to64_bytes(const char *s, size_t len, uint64_t seed) {
227 uint64_t z = fetch64(s + 24);
228 uint64_t a = fetch64(s) + (len + fetch64(s + len - 16)) * k0;
229 uint64_t b = rotate(a + z, 52);
230 uint64_t c = rotate(a, 37);
231 a += fetch64(s + 8);
232 c += rotate(a, 7);
233 a += fetch64(s + 16);
234 uint64_t vf = a + z;
235 uint64_t vs = b + rotate(a, 31) + c;
236 a = fetch64(s + 16) + fetch64(s + len - 32);
237 z = fetch64(s + len - 8);
238 b = rotate(a + z, 52);
239 c = rotate(a, 37);
240 a += fetch64(s + len - 24);
241 c += rotate(a, 7);
242 a += fetch64(s + len - 16);
243 uint64_t wf = a + z;
244 uint64_t ws = b + rotate(a, 31) + c;
245 uint64_t r = shift_mix((vf + ws) * k2 + (wf + vs) * k0);
246 return shift_mix((seed ^ (r * k0)) + vs) * k2;
247}
248
249inline uint64_t hash_short(const char *s, size_t length, uint64_t seed) {
250 if (length >= 4 && length <= 8)
251 return hash_4to8_bytes(s, length, seed);
252 if (length > 8 && length <= 16)
253 return hash_9to16_bytes(s, length, seed);
254 if (length > 16 && length <= 32)
255 return hash_17to32_bytes(s, length, seed);
256 if (length > 32)
257 return hash_33to64_bytes(s, length, seed);
258 if (length != 0)
259 return hash_1to3_bytes(s, length, seed);
260
261 return k2 ^ seed;
262}
263
264/// The intermediate state used during hashing.
265/// Currently, the algorithm for computing hash codes is based on CityHash and
266/// keeps 56 bytes of arbitrary state.
268 uint64_t h0 = 0, h1 = 0, h2 = 0, h3 = 0, h4 = 0, h5 = 0, h6 = 0;
269
270 /// Create a new hash_state structure and initialize it based on the
271 /// seed and the first 64-byte chunk.
272 /// This effectively performs the initial mix.
273 static hash_state create(const char *s, uint64_t seed) {
274 hash_state state = {
275 0, seed, hash_16_bytes(seed, k1), rotate(seed ^ k1, 49),
276 seed * k1, shift_mix(seed), 0 };
277 state.h6 = hash_16_bytes(state.h4, state.h5);
278 state.mix(s);
279 return state;
280 }
281
282 /// Mix 32-bytes from the input sequence into the 16-bytes of 'a'
283 /// and 'b', including whatever is already in 'a' and 'b'.
284 static void mix_32_bytes(const char *s, uint64_t &a, uint64_t &b) {
285 a += fetch64(s);
286 uint64_t c = fetch64(s + 24);
287 b = rotate(b + a + c, 21);
288 uint64_t d = a;
289 a += fetch64(s + 8) + fetch64(s + 16);
290 b += rotate(a, 44) + d;
291 a += c;
292 }
293
294 /// Mix in a 64-byte buffer of data.
295 /// We mix all 64 bytes even when the chunk length is smaller, but we
296 /// record the actual length.
297 void mix(const char *s) {
298 h0 = rotate(h0 + h1 + h3 + fetch64(s + 8), 37) * k1;
299 h1 = rotate(h1 + h4 + fetch64(s + 48), 42) * k1;
300 h0 ^= h6;
301 h1 += h3 + fetch64(s + 40);
302 h2 = rotate(h2 + h5, 33) * k1;
303 h3 = h4 * k1;
304 h4 = h0 + h5;
305 mix_32_bytes(s, h3, h4);
306 h5 = h2 + h6;
307 h6 = h1 + fetch64(s + 16);
308 mix_32_bytes(s + 32, h5, h6);
309 std::swap(h2, h0);
310 }
311
312 /// Compute the final 64-bit hash code value based on the current
313 /// state and the length of bytes hashed.
314 uint64_t finalize(size_t length) {
316 hash_16_bytes(h4, h6) + shift_mix(length) * k1 + h0);
317 }
318};
319
320
321/// A global, fixed seed-override variable.
322///
323/// This variable can be set using the \see llvm::set_fixed_execution_seed
324/// function. See that function for details. Do not, under any circumstances,
325/// set or read this variable.
327
329 // FIXME: This needs to be a per-execution seed. This is just a placeholder
330 // implementation. Switching to a per-execution seed is likely to flush out
331 // instability bugs and so will happen as its own commit.
332 //
333 // However, if there is a fixed seed override set the first time this is
334 // called, return that instead of the per-execution seed.
335 const uint64_t seed_prime = 0xff51afd7ed558ccdULL;
336 static uint64_t seed = fixed_seed_override ? fixed_seed_override : seed_prime;
337 return seed;
338}
339
340
341/// Trait to indicate whether a type's bits can be hashed directly.
342///
343/// A type trait which is true if we want to combine values for hashing by
344/// reading the underlying data. It is false if values of this type must
345/// first be passed to hash_value, and the resulting hash_codes combined.
346//
347// FIXME: We want to replace is_integral_or_enum and is_pointer here with
348// a predicate which asserts that comparing the underlying storage of two
349// values of the type for equality is equivalent to comparing the two values
350// for equality. For all the platforms we care about, this holds for integers
351// and pointers, but there are platforms where it doesn't and we would like to
352// support user-defined types which happen to satisfy this property.
353template <typename T> struct is_hashable_data
354 : std::integral_constant<bool, ((is_integral_or_enum<T>::value ||
355 std::is_pointer<T>::value) &&
356 64 % sizeof(T) == 0)> {};
357
358// Special case std::pair to detect when both types are viable and when there
359// is no alignment-derived padding in the pair. This is a bit of a lie because
360// std::pair isn't truly POD, but it's close enough in all reasonable
361// implementations for our use case of hashing the underlying data.
362template <typename T, typename U> struct is_hashable_data<std::pair<T, U> >
363 : std::integral_constant<bool, (is_hashable_data<T>::value &&
364 is_hashable_data<U>::value &&
365 (sizeof(T) + sizeof(U)) ==
366 sizeof(std::pair<T, U>))> {};
367
368/// Helper to get the hashable data representation for a type.
369/// This variant is enabled when the type itself can be used.
370template <typename T>
371std::enable_if_t<is_hashable_data<T>::value, T>
373 return value;
374}
375/// Helper to get the hashable data representation for a type.
376/// This variant is enabled when we must first call hash_value and use the
377/// result as our data.
378template <typename T>
379std::enable_if_t<!is_hashable_data<T>::value, size_t>
381 using ::llvm::hash_value;
382 return hash_value(value);
383}
384
385/// Helper to store data from a value into a buffer and advance the
386/// pointer into that buffer.
387///
388/// This routine first checks whether there is enough space in the provided
389/// buffer, and if not immediately returns false. If there is space, it
390/// copies the underlying bytes of value into the buffer, advances the
391/// buffer_ptr past the copied bytes, and returns true.
392template <typename T>
393bool store_and_advance(char *&buffer_ptr, char *buffer_end, const T& value,
394 size_t offset = 0) {
395 size_t store_size = sizeof(value) - offset;
396 if (buffer_ptr + store_size > buffer_end)
397 return false;
398 const char *value_data = reinterpret_cast<const char *>(&value);
399 memcpy(buffer_ptr, value_data + offset, store_size);
400 buffer_ptr += store_size;
401 return true;
402}
403
404/// Implement the combining of integral values into a hash_code.
405///
406/// This overload is selected when the value type of the iterator is
407/// integral. Rather than computing a hash_code for each object and then
408/// combining them, this (as an optimization) directly combines the integers.
409template <typename InputIteratorT>
410hash_code hash_combine_range_impl(InputIteratorT first, InputIteratorT last) {
411 const uint64_t seed = get_execution_seed();
412 char buffer[64], *buffer_ptr = buffer;
413 char *const buffer_end = std::end(buffer);
414 while (first != last && store_and_advance(buffer_ptr, buffer_end,
415 get_hashable_data(*first)))
416 ++first;
417 if (first == last)
418 return hash_short(buffer, buffer_ptr - buffer, seed);
419 assert(buffer_ptr == buffer_end);
420
421 hash_state state = state.create(buffer, seed);
422 size_t length = 64;
423 while (first != last) {
424 // Fill up the buffer. We don't clear it, which re-mixes the last round
425 // when only a partial 64-byte chunk is left.
426 buffer_ptr = buffer;
427 while (first != last && store_and_advance(buffer_ptr, buffer_end,
428 get_hashable_data(*first)))
429 ++first;
430
431 // Rotate the buffer if we did a partial fill in order to simulate doing
432 // a mix of the last 64-bytes. That is how the algorithm works when we
433 // have a contiguous byte sequence, and we want to emulate that here.
434 std::rotate(buffer, buffer_ptr, buffer_end);
435
436 // Mix this chunk into the current state.
437 state.mix(buffer);
438 length += buffer_ptr - buffer;
439 };
440
441 return state.finalize(length);
442}
443
444/// Implement the combining of integral values into a hash_code.
445///
446/// This overload is selected when the value type of the iterator is integral
447/// and when the input iterator is actually a pointer. Rather than computing
448/// a hash_code for each object and then combining them, this (as an
449/// optimization) directly combines the integers. Also, because the integers
450/// are stored in contiguous memory, this routine avoids copying each value
451/// and directly reads from the underlying memory.
452template <typename ValueT>
453std::enable_if_t<is_hashable_data<ValueT>::value, hash_code>
455 const uint64_t seed = get_execution_seed();
456 const char *s_begin = reinterpret_cast<const char *>(first);
457 const char *s_end = reinterpret_cast<const char *>(last);
458 const size_t length = std::distance(s_begin, s_end);
459 if (length <= 64)
460 return hash_short(s_begin, length, seed);
461
462 const char *s_aligned_end = s_begin + (length & ~63);
463 hash_state state = state.create(s_begin, seed);
464 s_begin += 64;
465 while (s_begin != s_aligned_end) {
466 state.mix(s_begin);
467 s_begin += 64;
468 }
469 if (length & 63)
470 state.mix(s_end - 64);
471
472 return state.finalize(length);
473}
474
475} // namespace detail
476} // namespace hashing
477
478
479/// Compute a hash_code for a sequence of values.
480///
481/// This hashes a sequence of values. It produces the same hash_code as
482/// 'hash_combine(a, b, c, ...)', but can run over arbitrary sized sequences
483/// and is significantly faster given pointers and types which can be hashed as
484/// a sequence of bytes.
485template <typename InputIteratorT>
486hash_code hash_combine_range(InputIteratorT first, InputIteratorT last) {
487 return ::llvm::hashing::detail::hash_combine_range_impl(first, last);
488}
489
490
491// Implementation details for hash_combine.
492namespace hashing {
493namespace detail {
494
495/// Helper class to manage the recursive combining of hash_combine
496/// arguments.
497///
498/// This class exists to manage the state and various calls involved in the
499/// recursive combining of arguments used in hash_combine. It is particularly
500/// useful at minimizing the code in the recursive calls to ease the pain
501/// caused by a lack of variadic functions.
503 char buffer[64] = {};
506
507public:
508 /// Construct a recursive hash combining helper.
509 ///
510 /// This sets up the state for a recursive hash combine, including getting
511 /// the seed and buffer setup.
514
515 /// Combine one chunk of data into the current in-flight hash.
516 ///
517 /// This merges one chunk of data into the hash. First it tries to buffer
518 /// the data. If the buffer is full, it hashes the buffer into its
519 /// hash_state, empties it, and then merges the new chunk in. This also
520 /// handles cases where the data straddles the end of the buffer.
521 template <typename T>
522 char *combine_data(size_t &length, char *buffer_ptr, char *buffer_end, T data) {
523 if (!store_and_advance(buffer_ptr, buffer_end, data)) {
524 // Check for skew which prevents the buffer from being packed, and do
525 // a partial store into the buffer to fill it. This is only a concern
526 // with the variadic combine because that formation can have varying
527 // argument types.
528 size_t partial_store_size = buffer_end - buffer_ptr;
529 memcpy(buffer_ptr, &data, partial_store_size);
530
531 // If the store fails, our buffer is full and ready to hash. We have to
532 // either initialize the hash state (on the first full buffer) or mix
533 // this buffer into the existing hash state. Length tracks the *hashed*
534 // length, not the buffered length.
535 if (length == 0) {
537 length = 64;
538 } else {
539 // Mix this chunk into the current state and bump length up by 64.
541 length += 64;
542 }
543 // Reset the buffer_ptr to the head of the buffer for the next chunk of
544 // data.
545 buffer_ptr = buffer;
546
547 // Try again to store into the buffer -- this cannot fail as we only
548 // store types smaller than the buffer.
549 if (!store_and_advance(buffer_ptr, buffer_end, data,
550 partial_store_size))
551 llvm_unreachable("buffer smaller than stored type");
552 }
553 return buffer_ptr;
554 }
555
556 /// Recursive, variadic combining method.
557 ///
558 /// This function recurses through each argument, combining that argument
559 /// into a single hash.
560 template <typename T, typename ...Ts>
561 hash_code combine(size_t length, char *buffer_ptr, char *buffer_end,
562 const T &arg, const Ts &...args) {
563 buffer_ptr = combine_data(length, buffer_ptr, buffer_end, get_hashable_data(arg));
564
565 // Recurse to the next argument.
566 return combine(length, buffer_ptr, buffer_end, args...);
567 }
568
569 /// Base case for recursive, variadic combining.
570 ///
571 /// The base case when combining arguments recursively is reached when all
572 /// arguments have been handled. It flushes the remaining buffer and
573 /// constructs a hash_code.
574 hash_code combine(size_t length, char *buffer_ptr, char *buffer_end) {
575 // Check whether the entire set of values fit in the buffer. If so, we'll
576 // use the optimized short hashing routine and skip state entirely.
577 if (length == 0)
578 return hash_short(buffer, buffer_ptr - buffer, seed);
579
580 // Mix the final buffer, rotating it if we did a partial fill in order to
581 // simulate doing a mix of the last 64-bytes. That is how the algorithm
582 // works when we have a contiguous byte sequence, and we want to emulate
583 // that here.
584 std::rotate(buffer, buffer_ptr, buffer_end);
585
586 // Mix this chunk into the current state.
588 length += buffer_ptr - buffer;
589
590 return state.finalize(length);
591 }
592};
593
594} // namespace detail
595} // namespace hashing
596
597/// Combine values into a single hash_code.
598///
599/// This routine accepts a varying number of arguments of any type. It will
600/// attempt to combine them into a single hash_code. For user-defined types it
601/// attempts to call a \see hash_value overload (via ADL) for the type. For
602/// integer and pointer types it directly combines their data into the
603/// resulting hash_code.
604///
605/// The result is suitable for returning from a user's hash_value
606/// *implementation* for their user-defined type. Consumers of a type should
607/// *not* call this routine, they should instead call 'hash_value'.
608template <typename ...Ts> hash_code hash_combine(const Ts &...args) {
609 // Recursively hash each argument using a helper class.
611 return helper.combine(0, helper.buffer, helper.buffer + 64, args...);
612}
613
614// Implementation details for implementations of hash_value overloads provided
615// here.
616namespace hashing {
617namespace detail {
618
619/// Helper to hash the value of a single integer.
620///
621/// Overloads for smaller integer types are not provided to ensure consistent
622/// behavior in the presence of integral promotions. Essentially,
623/// "hash_value('4')" and "hash_value('0' + 4)" should be the same.
625 // Similar to hash_4to8_bytes but using a seed instead of length.
626 const uint64_t seed = get_execution_seed();
627 const char *s = reinterpret_cast<const char *>(&value);
628 const uint64_t a = fetch32(s);
629 return hash_16_bytes(seed + (a << 3), fetch32(s + 4));
630}
631
632} // namespace detail
633} // namespace hashing
634
635// Declared and documented above, but defined here so that any of the hashing
636// infrastructure is available.
637template <typename T>
638std::enable_if_t<is_integral_or_enum<T>::value, hash_code> hash_value(T value) {
639 return ::llvm::hashing::detail::hash_integer_value(
640 static_cast<uint64_t>(value));
641}
642
643// Declared and documented above, but defined here so that any of the hashing
644// infrastructure is available.
645template <typename T> hash_code hash_value(const T *ptr) {
646 return ::llvm::hashing::detail::hash_integer_value(
647 reinterpret_cast<uintptr_t>(ptr));
648}
649
650// Declared and documented above, but defined here so that any of the hashing
651// infrastructure is available.
652template <typename T, typename U>
653hash_code hash_value(const std::pair<T, U> &arg) {
654 return hash_combine(arg.first, arg.second);
655}
656
657template <typename... Ts> hash_code hash_value(const std::tuple<Ts...> &arg) {
658 return std::apply([](const auto &...xs) { return hash_combine(xs...); }, arg);
659}
660
661// Declared and documented above, but defined here so that any of the hashing
662// infrastructure is available.
663template <typename T>
664hash_code hash_value(const std::basic_string<T> &arg) {
665 return hash_combine_range(arg.begin(), arg.end());
666}
667
668template <typename T> hash_code hash_value(const std::optional<T> &arg) {
669 return arg ? hash_combine(true, *arg) : hash_value(false);
670}
671
672template <> struct DenseMapInfo<hash_code, void> {
673 static inline hash_code getEmptyKey() { return hash_code(-1); }
674 static inline hash_code getTombstoneKey() { return hash_code(-2); }
675 static unsigned getHashValue(hash_code val) { return val; }
676 static bool isEqual(hash_code LHS, hash_code RHS) { return LHS == RHS; }
677};
678
679} // namespace llvm
680
681#endif
Given that RA is a live value
loop rotate
#define T
nvptx lower args
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
vector combine
Value * RHS
Value * LHS
An opaque object representing a hash code.
Definition: Hashing.h:74
friend size_t hash_value(const hash_code &code)
Allow a hash_code to be directly run through hash_value.
Definition: Hashing.h:96
friend bool operator==(const hash_code &lhs, const hash_code &rhs)
Definition: Hashing.h:88
friend bool operator!=(const hash_code &lhs, const hash_code &rhs)
Definition: Hashing.h:91
hash_code(size_t value)
Form a hash code directly from a numerical value.
Definition: Hashing.h:83
hash_code()=default
Default construct a hash_code.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
uint64_t hash_1to3_bytes(const char *s, size_t len, uint64_t seed)
Definition: Hashing.h:197
bool store_and_advance(char *&buffer_ptr, char *buffer_end, const T &value, size_t offset=0)
Helper to store data from a value into a buffer and advance the pointer into that buffer.
Definition: Hashing.h:393
uint64_t hash_9to16_bytes(const char *s, size_t len, uint64_t seed)
Definition: Hashing.h:211
uint64_t hash_4to8_bytes(const char *s, size_t len, uint64_t seed)
Definition: Hashing.h:206
hash_code hash_combine_range_impl(InputIteratorT first, InputIteratorT last)
Implement the combining of integral values into a hash_code.
Definition: Hashing.h:410
std::enable_if_t< is_hashable_data< T >::value, T > get_hashable_data(const T &value)
Helper to get the hashable data representation for a type.
Definition: Hashing.h:372
hash_code hash_integer_value(uint64_t value)
Helper to hash the value of a single integer.
Definition: Hashing.h:624
static constexpr uint64_t k2
Definition: Hashing.h:171
uint64_t fetch64(const char *p)
Definition: Hashing.h:152
uint64_t fixed_seed_override
A global, fixed seed-override variable.
Definition: Hashing.cpp:22
uint64_t hash_17to32_bytes(const char *s, size_t len, uint64_t seed)
Definition: Hashing.h:217
static constexpr uint64_t k1
Definition: Hashing.h:170
uint64_t get_execution_seed()
Definition: Hashing.h:328
uint32_t fetch32(const char *p)
Definition: Hashing.h:160
static constexpr uint64_t k3
Definition: Hashing.h:172
uint64_t hash_short(const char *s, size_t length, uint64_t seed)
Definition: Hashing.h:249
static constexpr uint64_t k0
Some primes between 2^63 and 2^64 for various uses.
Definition: Hashing.h:169
uint64_t shift_mix(uint64_t val)
Definition: Hashing.h:182
uint64_t hash_33to64_bytes(const char *s, size_t len, uint64_t seed)
Definition: Hashing.h:226
uint64_t hash_16_bytes(uint64_t low, uint64_t high)
Definition: Hashing.h:186
constexpr bool IsBigEndianHost
Definition: SwapByteOrder.h:64
void swapByteOrder(T &Value)
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
hash_code hash_value(const FixedPointSemantics &Val)
Definition: APFixedPoint.h:128
void set_fixed_execution_hash_seed(uint64_t fixed_value)
Override the execution seed with a fixed value.
Definition: Hashing.cpp:26
hash_code hash_combine(const Ts &...args)
Combine values into a single hash_code.
Definition: Hashing.h:608
hash_code hash_combine_range(InputIteratorT first, InputIteratorT last)
Compute a hash_code for a sequence of values.
Definition: Hashing.h:486
Definition: BitVector.h:851
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:853
static bool isEqual(hash_code LHS, hash_code RHS)
Definition: Hashing.h:676
static hash_code getEmptyKey()
Definition: Hashing.h:673
static unsigned getHashValue(hash_code val)
Definition: Hashing.h:675
static hash_code getTombstoneKey()
Definition: Hashing.h:674
An information struct used to provide DenseMap with the various necessary components for a given valu...
Definition: DenseMapInfo.h:51
Helper class to manage the recursive combining of hash_combine arguments.
Definition: Hashing.h:502
hash_code combine(size_t length, char *buffer_ptr, char *buffer_end)
Base case for recursive, variadic combining.
Definition: Hashing.h:574
char * combine_data(size_t &length, char *buffer_ptr, char *buffer_end, T data)
Combine one chunk of data into the current in-flight hash.
Definition: Hashing.h:522
hash_code combine(size_t length, char *buffer_ptr, char *buffer_end, const T &arg, const Ts &...args)
Recursive, variadic combining method.
Definition: Hashing.h:561
hash_combine_recursive_helper()
Construct a recursive hash combining helper.
Definition: Hashing.h:512
The intermediate state used during hashing.
Definition: Hashing.h:267
static hash_state create(const char *s, uint64_t seed)
Create a new hash_state structure and initialize it based on the seed and the first 64-byte chunk.
Definition: Hashing.h:273
uint64_t finalize(size_t length)
Compute the final 64-bit hash code value based on the current state and the length of bytes hashed.
Definition: Hashing.h:314
static void mix_32_bytes(const char *s, uint64_t &a, uint64_t &b)
Mix 32-bytes from the input sequence into the 16-bytes of 'a' and 'b', including whatever is already ...
Definition: Hashing.h:284
void mix(const char *s)
Mix in a 64-byte buffer of data.
Definition: Hashing.h:297
Trait to indicate whether a type's bits can be hashed directly.
Definition: Hashing.h:356