Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * simd.h
4 : * Support for platform-specific vector operations.
5 : *
6 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : * src/include/port/simd.h
10 : *
11 : * NOTES
12 : * - VectorN in this file refers to a register where the element operands
13 : * are N bits wide. The vector width is platform-specific, so users that care
14 : * about that will need to inspect "sizeof(VectorN)".
15 : *
16 : *-------------------------------------------------------------------------
17 : */
18 : #ifndef SIMD_H
19 : #define SIMD_H
20 :
21 : #if (defined(__x86_64__) || defined(_M_AMD64))
22 : /*
23 : * SSE2 instructions are part of the spec for the 64-bit x86 ISA. We assume
24 : * that compilers targeting this architecture understand SSE2 intrinsics.
25 : *
26 : * We use emmintrin.h rather than the comprehensive header immintrin.h in
27 : * order to exclude extensions beyond SSE2. This is because MSVC, at least,
28 : * will allow the use of intrinsics that haven't been enabled at compile
29 : * time.
30 : */
31 : #include <emmintrin.h>
32 : #define USE_SSE2
33 : typedef __m128i Vector8;
34 : typedef __m128i Vector32;
35 :
36 : #elif defined(__aarch64__) && defined(__ARM_NEON)
37 : /*
38 : * We use the Neon instructions if the compiler provides access to them (as
39 : * indicated by __ARM_NEON) and we are on aarch64. While Neon support is
40 : * technically optional for aarch64, it appears that all available 64-bit
41 : * hardware does have it. Neon exists in some 32-bit hardware too, but we
42 : * could not realistically use it there without a run-time check, which seems
43 : * not worth the trouble for now.
44 : */
45 : #include <arm_neon.h>
46 : #define USE_NEON
47 : typedef uint8x16_t Vector8;
48 : typedef uint32x4_t Vector32;
49 :
50 : #else
51 : /*
52 : * If no SIMD instructions are available, we can in some cases emulate vector
53 : * operations using bitwise operations on unsigned integers. Note that many
54 : * of the functions in this file presently do not have non-SIMD
55 : * implementations. In particular, none of the functions involving Vector32
56 : * are implemented without SIMD since it's likely not worthwhile to represent
57 : * two 32-bit integers using a uint64.
58 : */
59 : #define USE_NO_SIMD
60 : typedef uint64 Vector8;
61 : #endif
62 :
63 : /* load/store operations */
64 : static inline void vector8_load(Vector8 *v, const uint8 *s);
65 : #ifndef USE_NO_SIMD
66 : static inline void vector32_load(Vector32 *v, const uint32 *s);
67 : #endif
68 :
69 : /* assignment operations */
70 : static inline Vector8 vector8_broadcast(const uint8 c);
71 : #ifndef USE_NO_SIMD
72 : static inline Vector32 vector32_broadcast(const uint32 c);
73 : #endif
74 :
75 : /* element-wise comparisons to a scalar */
76 : static inline bool vector8_has(const Vector8 v, const uint8 c);
77 : static inline bool vector8_has_zero(const Vector8 v);
78 : static inline bool vector8_has_le(const Vector8 v, const uint8 c);
79 : static inline bool vector8_is_highbit_set(const Vector8 v);
80 : #ifndef USE_NO_SIMD
81 : static inline bool vector32_is_highbit_set(const Vector32 v);
82 : static inline uint32 vector8_highbit_mask(const Vector8 v);
83 : #endif
84 :
85 : /* arithmetic operations */
86 : static inline Vector8 vector8_or(const Vector8 v1, const Vector8 v2);
87 : #ifndef USE_NO_SIMD
88 : static inline Vector32 vector32_or(const Vector32 v1, const Vector32 v2);
89 : #endif
90 :
91 : /*
92 : * comparisons between vectors
93 : *
94 : * Note: These return a vector rather than boolean, which is why we don't
95 : * have non-SIMD implementations.
96 : */
97 : #ifndef USE_NO_SIMD
98 : static inline Vector8 vector8_eq(const Vector8 v1, const Vector8 v2);
99 : static inline Vector8 vector8_min(const Vector8 v1, const Vector8 v2);
100 : static inline Vector32 vector32_eq(const Vector32 v1, const Vector32 v2);
101 : #endif
102 :
103 : /*
104 : * Load a chunk of memory into the given vector.
105 : */
106 : static inline void
107 29456944 : vector8_load(Vector8 *v, const uint8 *s)
108 : {
109 : #if defined(USE_SSE2)
110 29456944 : *v = _mm_loadu_si128((const __m128i *) s);
111 : #elif defined(USE_NEON)
112 : *v = vld1q_u8(s);
113 : #else
114 : memcpy(v, s, sizeof(Vector8));
115 : #endif
116 29456944 : }
117 :
118 : #ifndef USE_NO_SIMD
119 : static inline void
120 3168 : vector32_load(Vector32 *v, const uint32 *s)
121 : {
122 : #ifdef USE_SSE2
123 3168 : *v = _mm_loadu_si128((const __m128i *) s);
124 : #elif defined(USE_NEON)
125 : *v = vld1q_u32(s);
126 : #endif
127 3168 : }
128 : #endif /* ! USE_NO_SIMD */
129 :
130 : /*
131 : * Store a vector into the given memory address.
132 : */
133 : #ifndef USE_NO_SIMD
134 : static inline void
135 4635724 : vector8_store(uint8 *s, Vector8 v)
136 : {
137 : #ifdef USE_SSE2
138 : _mm_storeu_si128((Vector8 *) s, v);
139 : #elif defined(USE_NEON)
140 : vst1q_u8(s, v);
141 : #endif
142 4635724 : }
143 : #endif /* ! USE_NO_SIMD */
144 :
145 : /*
146 : * Create a vector with all elements set to the same value.
147 : */
148 : static inline Vector8
149 47569098 : vector8_broadcast(const uint8 c)
150 : {
151 : #if defined(USE_SSE2)
152 95138196 : return _mm_set1_epi8(c);
153 : #elif defined(USE_NEON)
154 : return vdupq_n_u8(c);
155 : #else
156 : return ~UINT64CONST(0) / 0xFF * c;
157 : #endif
158 : }
159 :
160 : #ifndef USE_NO_SIMD
161 : static inline Vector32
162 17624852 : vector32_broadcast(const uint32 c)
163 : {
164 : #ifdef USE_SSE2
165 35249704 : return _mm_set1_epi32(c);
166 : #elif defined(USE_NEON)
167 : return vdupq_n_u32(c);
168 : #endif
169 : }
170 : #endif /* ! USE_NO_SIMD */
171 :
172 : /*
173 : * Return true if any elements in the vector are equal to the given scalar.
174 : */
175 : static inline bool
176 6630024 : vector8_has(const Vector8 v, const uint8 c)
177 : {
178 : bool result;
179 :
180 : /* pre-compute the result for assert checking */
181 : #ifdef USE_ASSERT_CHECKING
182 : bool assert_result = false;
183 :
184 : for (Size i = 0; i < sizeof(Vector8); i++)
185 : {
186 : if (((const uint8 *) &v)[i] == c)
187 : {
188 : assert_result = true;
189 : break;
190 : }
191 : }
192 : #endif /* USE_ASSERT_CHECKING */
193 :
194 : #if defined(USE_NO_SIMD)
195 : /* any bytes in v equal to c will evaluate to zero via XOR */
196 : result = vector8_has_zero(v ^ vector8_broadcast(c));
197 : #else
198 6630024 : result = vector8_is_highbit_set(vector8_eq(v, vector8_broadcast(c)));
199 : #endif
200 :
201 : Assert(assert_result == result);
202 6630024 : return result;
203 : }
204 :
205 : /*
206 : * Convenience function equivalent to vector8_has(v, 0)
207 : */
208 : static inline bool
209 : vector8_has_zero(const Vector8 v)
210 : {
211 : #if defined(USE_NO_SIMD)
212 : /*
213 : * We cannot call vector8_has() here, because that would lead to a
214 : * circular definition.
215 : */
216 : return vector8_has_le(v, 0);
217 : #else
218 : return vector8_has(v, 0);
219 : #endif
220 : }
221 :
222 : /*
223 : * Return true if any elements in the vector are less than or equal to the
224 : * given scalar.
225 : */
226 : static inline bool
227 820430 : vector8_has_le(const Vector8 v, const uint8 c)
228 : {
229 820430 : bool result = false;
230 : #ifdef USE_SSE2
231 : Vector8 umin;
232 : Vector8 cmpe;
233 : #endif
234 :
235 : /* pre-compute the result for assert checking */
236 : #ifdef USE_ASSERT_CHECKING
237 : bool assert_result = false;
238 :
239 : for (Size i = 0; i < sizeof(Vector8); i++)
240 : {
241 : if (((const uint8 *) &v)[i] <= c)
242 : {
243 : assert_result = true;
244 : break;
245 : }
246 : }
247 : #endif /* USE_ASSERT_CHECKING */
248 :
249 : #if defined(USE_NO_SIMD)
250 :
251 : /*
252 : * To find bytes <= c, we can use bitwise operations to find bytes < c+1,
253 : * but it only works if c+1 <= 128 and if the highest bit in v is not set.
254 : * Adapted from
255 : * https://graphics.stanford.edu/~seander/bithacks.html#HasLessInWord
256 : */
257 : if ((int64) v >= 0 && c < 0x80)
258 : result = (v - vector8_broadcast(c + 1)) & ~v & vector8_broadcast(0x80);
259 : else
260 : {
261 : /* one byte at a time */
262 : for (Size i = 0; i < sizeof(Vector8); i++)
263 : {
264 : if (((const uint8 *) &v)[i] <= c)
265 : {
266 : result = true;
267 : break;
268 : }
269 : }
270 : }
271 : #elif defined(USE_SSE2)
272 820430 : umin = vector8_min(v, vector8_broadcast(c));
273 820430 : cmpe = vector8_eq(umin, v);
274 820430 : result = vector8_is_highbit_set(cmpe);
275 : #elif defined(USE_NEON)
276 : result = vminvq_u8(v) <= c;
277 : #endif
278 :
279 : Assert(assert_result == result);
280 820430 : return result;
281 : }
282 :
283 : /*
284 : * Returns true if any elements in the vector are greater than or equal to the
285 : * given scalar.
286 : */
287 : #ifndef USE_NO_SIMD
288 : static inline bool
289 492216 : vector8_has_ge(const Vector8 v, const uint8 c)
290 : {
291 : #ifdef USE_SSE2
292 492216 : Vector8 umax = _mm_max_epu8(v, vector8_broadcast(c));
293 492216 : Vector8 cmpe = vector8_eq(umax, v);
294 :
295 492216 : return vector8_is_highbit_set(cmpe);
296 : #elif defined(USE_NEON)
297 : return vmaxvq_u8(v) >= c;
298 : #endif
299 : }
300 : #endif /* ! USE_NO_SIMD */
301 :
302 : /*
303 : * Return true if the high bit of any element is set
304 : */
305 : static inline bool
306 11425668 : vector8_is_highbit_set(const Vector8 v)
307 : {
308 : #ifdef USE_SSE2
309 11425668 : return _mm_movemask_epi8(v) != 0;
310 : #elif defined(USE_NEON)
311 : return vmaxvq_u8(v) > 0x7F;
312 : #else
313 : return v & vector8_broadcast(0x80);
314 : #endif
315 : }
316 :
317 : /*
318 : * Exactly like vector8_is_highbit_set except for the input type, so it
319 : * looks at each byte separately.
320 : *
321 : * XXX x86 uses the same underlying type for 8-bit, 16-bit, and 32-bit
322 : * integer elements, but Arm does not, hence the need for a separate
323 : * function. We could instead adopt the behavior of Arm's vmaxvq_u32(), i.e.
324 : * check each 32-bit element, but that would require an additional mask
325 : * operation on x86.
326 : */
327 : #ifndef USE_NO_SIMD
328 : static inline bool
329 792 : vector32_is_highbit_set(const Vector32 v)
330 : {
331 : #if defined(USE_NEON)
332 : return vector8_is_highbit_set((Vector8) v);
333 : #else
334 792 : return vector8_is_highbit_set(v);
335 : #endif
336 : }
337 : #endif /* ! USE_NO_SIMD */
338 :
339 : /*
340 : * Return a bitmask formed from the high-bit of each element.
341 : */
342 : #ifndef USE_NO_SIMD
343 : static inline uint32
344 12413940 : vector8_highbit_mask(const Vector8 v)
345 : {
346 : #ifdef USE_SSE2
347 12413940 : return (uint32) _mm_movemask_epi8(v);
348 : #elif defined(USE_NEON)
349 : /*
350 : * Note: It would be faster to use vget_lane_u64 and vshrn_n_u16, but that
351 : * returns a uint64, making it inconvenient to combine mask values from
352 : * multiple vectors.
353 : */
354 : static const uint8 mask[16] = {
355 : 1 << 0, 1 << 1, 1 << 2, 1 << 3,
356 : 1 << 4, 1 << 5, 1 << 6, 1 << 7,
357 : 1 << 0, 1 << 1, 1 << 2, 1 << 3,
358 : 1 << 4, 1 << 5, 1 << 6, 1 << 7,
359 : };
360 :
361 : uint8x16_t masked = vandq_u8(vld1q_u8(mask), (uint8x16_t) vshrq_n_s8((int8x16_t) v, 7));
362 : uint8x16_t maskedhi = vextq_u8(masked, masked, 8);
363 :
364 : return (uint32) vaddvq_u16((uint16x8_t) vzip1q_u8(masked, maskedhi));
365 : #endif
366 : }
367 : #endif /* ! USE_NO_SIMD */
368 :
369 : /*
370 : * Return the bitwise OR of the inputs
371 : */
372 : static inline Vector8
373 14421040 : vector8_or(const Vector8 v1, const Vector8 v2)
374 : {
375 : #ifdef USE_SSE2
376 14421040 : return _mm_or_si128(v1, v2);
377 : #elif defined(USE_NEON)
378 : return vorrq_u8(v1, v2);
379 : #else
380 : return v1 | v2;
381 : #endif
382 : }
383 :
384 : #ifndef USE_NO_SIMD
385 : static inline Vector32
386 2376 : vector32_or(const Vector32 v1, const Vector32 v2)
387 : {
388 : #ifdef USE_SSE2
389 2376 : return _mm_or_si128(v1, v2);
390 : #elif defined(USE_NEON)
391 : return vorrq_u32(v1, v2);
392 : #endif
393 : }
394 : #endif /* ! USE_NO_SIMD */
395 :
396 : /*
397 : * Return the bitwise AND of the inputs.
398 : */
399 : #ifndef USE_NO_SIMD
400 : static inline Vector8
401 11240312 : vector8_and(const Vector8 v1, const Vector8 v2)
402 : {
403 : #ifdef USE_SSE2
404 11240312 : return _mm_and_si128(v1, v2);
405 : #elif defined(USE_NEON)
406 : return vandq_u8(v1, v2);
407 : #endif
408 : }
409 : #endif /* ! USE_NO_SIMD */
410 :
411 : /*
412 : * Return the result of adding the respective elements of the input vectors.
413 : */
414 : #ifndef USE_NO_SIMD
415 : static inline Vector8
416 9763664 : vector8_add(const Vector8 v1, const Vector8 v2)
417 : {
418 : #ifdef USE_SSE2
419 9763664 : return _mm_add_epi8(v1, v2);
420 : #elif defined(USE_NEON)
421 : return vaddq_u8(v1, v2);
422 : #endif
423 : }
424 : #endif /* ! USE_NO_SIMD */
425 :
426 : /*
427 : * Return the result of subtracting the respective elements of the input
428 : * vectors using signed saturation (i.e., if the operation would yield a value
429 : * less than -128, -128 is returned instead). For more information on
430 : * saturation arithmetic, see
431 : * https://en.wikipedia.org/wiki/Saturation_arithmetic
432 : */
433 : #ifndef USE_NO_SIMD
434 : static inline Vector8
435 492216 : vector8_issub(const Vector8 v1, const Vector8 v2)
436 : {
437 : #ifdef USE_SSE2
438 492216 : return _mm_subs_epi8(v1, v2);
439 : #elif defined(USE_NEON)
440 : return (Vector8) vqsubq_s8((int8x16_t) v1, (int8x16_t) v2);
441 : #endif
442 : }
443 : #endif /* ! USE_NO_SIMD */
444 :
445 : /*
446 : * Return a vector with all bits set in each lane where the corresponding
447 : * lanes in the inputs are equal.
448 : */
449 : #ifndef USE_NO_SIMD
450 : static inline Vector8
451 27321022 : vector8_eq(const Vector8 v1, const Vector8 v2)
452 : {
453 : #ifdef USE_SSE2
454 27321022 : return _mm_cmpeq_epi8(v1, v2);
455 : #elif defined(USE_NEON)
456 : return vceqq_u8(v1, v2);
457 : #endif
458 : }
459 : #endif /* ! USE_NO_SIMD */
460 :
461 : #ifndef USE_NO_SIMD
462 : static inline Vector32
463 3168 : vector32_eq(const Vector32 v1, const Vector32 v2)
464 : {
465 : #ifdef USE_SSE2
466 3168 : return _mm_cmpeq_epi32(v1, v2);
467 : #elif defined(USE_NEON)
468 : return vceqq_u32(v1, v2);
469 : #endif
470 : }
471 : #endif /* ! USE_NO_SIMD */
472 :
473 : /*
474 : * Return a vector with all bits set for each lane of v1 that is greater than
475 : * the corresponding lane of v2. NB: The comparison treats the elements as
476 : * signed.
477 : */
478 : #ifndef USE_NO_SIMD
479 : static inline Vector8
480 5866264 : vector8_gt(const Vector8 v1, const Vector8 v2)
481 : {
482 : #ifdef USE_SSE2
483 5866264 : return _mm_cmpgt_epi8(v1, v2);
484 : #elif defined(USE_NEON)
485 : return vcgtq_s8((int8x16_t) v1, (int8x16_t) v2);
486 : #endif
487 : }
488 : #endif /* ! USE_NO_SIMD */
489 :
490 : /*
491 : * Given two vectors, return a vector with the minimum element of each.
492 : */
493 : #ifndef USE_NO_SIMD
494 : static inline Vector8
495 1029810 : vector8_min(const Vector8 v1, const Vector8 v2)
496 : {
497 : #ifdef USE_SSE2
498 1029810 : return _mm_min_epu8(v1, v2);
499 : #elif defined(USE_NEON)
500 : return vminq_u8(v1, v2);
501 : #endif
502 : }
503 : #endif /* ! USE_NO_SIMD */
504 :
505 : /*
506 : * Interleave elements of low halves (e.g., for SSE2, bits 0-63) of given
507 : * vectors. Bytes 0, 2, 4, etc. use v1, and bytes 1, 3, 5, etc. use v2.
508 : */
509 : #ifndef USE_NO_SIMD
510 : static inline Vector8
511 3425348 : vector8_interleave_low(const Vector8 v1, const Vector8 v2)
512 : {
513 : #ifdef USE_SSE2
514 3425348 : return _mm_unpacklo_epi8(v1, v2);
515 : #elif defined(USE_NEON)
516 : return vzip1q_u8(v1, v2);
517 : #endif
518 : }
519 : #endif /* ! USE_NO_SIMD */
520 :
521 : /*
522 : * Interleave elements of high halves (e.g., for SSE2, bits 64-127) of given
523 : * vectors. Bytes 0, 2, 4, etc. use v1, and bytes 1, 3, 5, etc. use v2.
524 : */
525 : #ifndef USE_NO_SIMD
526 : static inline Vector8
527 2194808 : vector8_interleave_high(const Vector8 v1, const Vector8 v2)
528 : {
529 : #ifdef USE_SSE2
530 2194808 : return _mm_unpackhi_epi8(v1, v2);
531 : #elif defined(USE_NEON)
532 : return vzip2q_u8(v1, v2);
533 : #endif
534 : }
535 : #endif /* ! USE_NO_SIMD */
536 :
537 : /*
538 : * Pack 16-bit elements in the given vectors into a single vector of 8-bit
539 : * elements. The first half of the return vector (e.g., for SSE2, bits 0-63)
540 : * uses v1, and the second half (e.g., for SSE2, bits 64-127) uses v2.
541 : *
542 : * NB: The upper 8-bits of each 16-bit element must be zeros, else this will
543 : * produce different results on different architectures.
544 : */
545 : #ifndef USE_NO_SIMD
546 : static inline Vector8
547 246108 : vector8_pack_16(const Vector8 v1, const Vector8 v2)
548 : {
549 : Vector8 mask PG_USED_FOR_ASSERTS_ONLY;
550 :
551 246108 : mask = vector8_interleave_low(vector8_broadcast(0), vector8_broadcast(0xff));
552 : Assert(!vector8_has_ge(vector8_and(v1, mask), 1));
553 : Assert(!vector8_has_ge(vector8_and(v2, mask), 1));
554 : #ifdef USE_SSE2
555 246108 : return _mm_packus_epi16(v1, v2);
556 : #elif defined(USE_NEON)
557 : return vuzp1q_u8(v1, v2);
558 : #endif
559 : }
560 : #endif /* ! USE_NO_SIMD */
561 :
562 : /*
563 : * Unsigned shift left of each 32-bit element in the vector by "i" bits.
564 : *
565 : * XXX AArch64 requires an integer literal, so we have to list all expected
566 : * values of "i" from all callers in a switch statement. If you add a new
567 : * caller, be sure your expected values of "i" are handled.
568 : */
569 : #ifndef USE_NO_SIMD
570 : static inline Vector8
571 492216 : vector8_shift_left(const Vector8 v1, int i)
572 : {
573 : #ifdef USE_SSE2
574 492216 : return _mm_slli_epi32(v1, i);
575 : #elif defined(USE_NEON)
576 : switch (i)
577 : {
578 : case 4:
579 : return (Vector8) vshlq_n_u32((Vector32) v1, 4);
580 : default:
581 : Assert(false);
582 : return vector8_broadcast(0);
583 : }
584 : #endif
585 : }
586 : #endif /* ! USE_NO_SIMD */
587 :
588 : /*
589 : * Unsigned shift right of each 32-bit element in the vector by "i" bits.
590 : *
591 : * XXX AArch64 requires an integer literal, so we have to list all expected
592 : * values of "i" from all callers in a switch statement. If you add a new
593 : * caller, be sure your expected values of "i" are handled.
594 : */
595 : #ifndef USE_NO_SIMD
596 : static inline Vector8
597 2687024 : vector8_shift_right(const Vector8 v1, int i)
598 : {
599 : #ifdef USE_SSE2
600 2687024 : return _mm_srli_epi32(v1, i);
601 : #elif defined(USE_NEON)
602 : switch (i)
603 : {
604 : case 4:
605 : return (Vector8) vshrq_n_u32((Vector32) v1, 4);
606 : case 8:
607 : return (Vector8) vshrq_n_u32((Vector32) v1, 8);
608 : default:
609 : Assert(false);
610 : return vector8_broadcast(0);
611 : }
612 : #endif
613 : }
614 : #endif /* ! USE_NO_SIMD */
615 :
616 : #endif /* SIMD_H */
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