libstdc++: simd_neon.h Source File

libstdc++

simd_neon.h
1// Simd NEON specific implementations -*- C++ -*-
2
3// Copyright (C) 2020-2026 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25#ifndef _GLIBCXX_EXPERIMENTAL_SIMD_NEON_H_
26#define _GLIBCXX_EXPERIMENTAL_SIMD_NEON_H_
27
28#if __cplusplus >= 201703L
29
30#if !_GLIBCXX_SIMD_HAVE_NEON
31#error "simd_neon.h may only be included when NEON on ARM is available"
32#endif
33
34_GLIBCXX_SIMD_BEGIN_NAMESPACE
35
36// _CommonImplNeon {{{
37struct _CommonImplNeon : _CommonImplBuiltin
38{
39 // _S_store {{{
40 using _CommonImplBuiltin::_S_store;
41
42 // }}}
43};
44
45// }}}
46// _SimdImplNeon {{{
47template <typename _Abi, typename>
48 struct _SimdImplNeon : _SimdImplBuiltin<_Abi>
49 {
50 using _Base = _SimdImplBuiltin<_Abi>;
51
52 template <typename _Tp>
53 using _MaskMember = typename _Base::template _MaskMember<_Tp>;
54
55 template <typename _Tp>
56 static constexpr size_t _S_max_store_size = 16;
57
58 // _S_masked_load {{{
59 template <typename _Tp, size_t _Np, typename _Up>
60 static inline _SimdWrapper<_Tp, _Np>
61 _S_masked_load(_SimdWrapper<_Tp, _Np> __merge, _MaskMember<_Tp> __k,
62 const _Up* __mem) noexcept
63 {
64 __execute_n_times<_Np>([&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
65 if (__k[__i] != 0)
66 __merge._M_set(__i, static_cast<_Tp>(__mem[__i]));
67 });
68 return __merge;
69 }
70
71 // }}}
72 // _S_masked_store_nocvt {{{
73 template <typename _Tp, size_t _Np>
74 _GLIBCXX_SIMD_INTRINSIC static void
75 _S_masked_store_nocvt(_SimdWrapper<_Tp, _Np> __v, _Tp* __mem,
76 _MaskMember<_Tp> __k)
77 {
78 __execute_n_times<_Np>([&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
79 if (__k[__i] != 0)
80 __mem[__i] = __v[__i];
81 });
82 }
83
84 // }}}
85 // _S_reduce {{{
86 template <typename _Tp, typename _BinaryOperation>
87 _GLIBCXX_SIMD_INTRINSIC static constexpr _Tp
88 _S_reduce(simd<_Tp, _Abi> __x, _BinaryOperation&& __binary_op)
89 {
90 if (not __builtin_is_constant_evaluated())
91 {
92 constexpr size_t _Np = __x.size();
93 if constexpr (sizeof(__x) == 16 && _Np >= 4
94 && !_Abi::template _S_is_partial<_Tp>)
95 {
96 const auto __halves = split<simd<_Tp, simd_abi::_Neon<8>>>(__x);
97 const auto __y = __binary_op(__halves[0], __halves[1]);
98 return _SimdImplNeon<simd_abi::_Neon<8>>::_S_reduce(
99 __y, static_cast<_BinaryOperation&&>(__binary_op));
100 }
101 else if constexpr (_Np == 8)
102 {
103 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
104 __vector_permute<1, 0, 3, 2, 5, 4, 7, 6>(__x._M_data)));
105 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
106 __vector_permute<3, 2, 1, 0, 7, 6, 5, 4>(__x._M_data)));
107 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
108 __vector_permute<7, 6, 5, 4, 3, 2, 1, 0>(__x._M_data)));
109 return __x[0];
110 }
111 else if constexpr (_Np == 4)
112 {
113 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
114 __vector_permute<1, 0, 3, 2>(__x._M_data)));
115 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
116 __vector_permute<3, 2, 1, 0>(__x._M_data)));
117 return __x[0];
118 }
119 else if constexpr (_Np == 2)
120 {
121 __x = __binary_op(__x, _Base::template _M_make_simd<_Tp, _Np>(
122 __vector_permute<1, 0>(__x._M_data)));
123 return __x[0];
124 }
125 }
126 return _Base::_S_reduce(__x, static_cast<_BinaryOperation&&>(__binary_op));
127 }
128
129 // }}}
130 // math {{{
131 // _S_sqrt {{{
132 template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
133 _GLIBCXX_SIMD_INTRINSIC static _Tp
134 _S_sqrt(_Tp __x)
135 {
136 if constexpr (__have_neon_a64)
137 {
138 const auto __intrin = __to_intrin(__x);
139 if constexpr (_TVT::template _S_is<float, 2>)
140 return vsqrt_f32(__intrin);
141 else if constexpr (_TVT::template _S_is<float, 4>)
142 return vsqrtq_f32(__intrin);
143 else if constexpr (_TVT::template _S_is<double, 1>)
144 return vsqrt_f64(__intrin);
145 else if constexpr (_TVT::template _S_is<double, 2>)
146 return vsqrtq_f64(__intrin);
147 else
148 __assert_unreachable<_Tp>();
149 }
150 else
151 return _Base::_S_sqrt(__x);
152 }
153
154 // }}}
155 // _S_trunc {{{
156 template <typename _TW, typename _TVT = _VectorTraits<_TW>>
157 _GLIBCXX_SIMD_INTRINSIC static _TW
158 _S_trunc(_TW __x)
159 {
160 using _Tp = typename _TVT::value_type;
161 if constexpr (__have_neon_a32)
162 {
163 const auto __intrin = __to_intrin(__x);
164 if constexpr (_TVT::template _S_is<float, 2>)
165 return vrnd_f32(__intrin);
166 else if constexpr (_TVT::template _S_is<float, 4>)
167 return vrndq_f32(__intrin);
168 else if constexpr (_TVT::template _S_is<double, 1>)
169 return vrnd_f64(__intrin);
170 else if constexpr (_TVT::template _S_is<double, 2>)
171 return vrndq_f64(__intrin);
172 else
173 __assert_unreachable<_Tp>();
174 }
175 else if constexpr (is_same_v<_Tp, float>)
176 {
177 auto __intrin = __to_intrin(__x);
178 if constexpr (sizeof(__x) == 16)
179 __intrin = vcvtq_f32_s32(vcvtq_s32_f32(__intrin));
180 else
181 __intrin = vcvt_f32_s32(vcvt_s32_f32(__intrin));
182 return _Base::_S_abs(__x)._M_data < 0x1p23f
183 ? __vector_bitcast<float>(__intrin)
184 : __x._M_data;
185 }
186 else
187 return _Base::_S_trunc(__x);
188 }
189
190 // }}}
191 // _S_round {{{
192 template <typename _Tp, size_t _Np>
193 _GLIBCXX_SIMD_INTRINSIC static _SimdWrapper<_Tp, _Np>
194 _S_round(_SimdWrapper<_Tp, _Np> __x)
195 {
196 if constexpr (__have_neon_a32)
197 {
198 const auto __intrin = __to_intrin(__x);
199 if constexpr (sizeof(_Tp) == 4 && sizeof(__x) == 8)
200 return vrnda_f32(__intrin);
201 else if constexpr (sizeof(_Tp) == 4 && sizeof(__x) == 16)
202 return vrndaq_f32(__intrin);
203 else if constexpr (sizeof(_Tp) == 8 && sizeof(__x) == 8)
204 return vrnda_f64(__intrin);
205 else if constexpr (sizeof(_Tp) == 8 && sizeof(__x) == 16)
206 return vrndaq_f64(__intrin);
207 else
208 __assert_unreachable<_Tp>();
209 }
210 else
211 return _Base::_S_round(__x);
212 }
213
214 // }}}
215 // _S_floor {{{
216 template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
217 _GLIBCXX_SIMD_INTRINSIC static _Tp
218 _S_floor(_Tp __x)
219 {
220 if constexpr (__have_neon_a32)
221 {
222 const auto __intrin = __to_intrin(__x);
223 if constexpr (_TVT::template _S_is<float, 2>)
224 return vrndm_f32(__intrin);
225 else if constexpr (_TVT::template _S_is<float, 4>)
226 return vrndmq_f32(__intrin);
227 else if constexpr (_TVT::template _S_is<double, 1>)
228 return vrndm_f64(__intrin);
229 else if constexpr (_TVT::template _S_is<double, 2>)
230 return vrndmq_f64(__intrin);
231 else
232 __assert_unreachable<_Tp>();
233 }
234 else
235 return _Base::_S_floor(__x);
236 }
237
238 // }}}
239 // _S_ceil {{{
240 template <typename _Tp, typename _TVT = _VectorTraits<_Tp>>
241 _GLIBCXX_SIMD_INTRINSIC static _Tp
242 _S_ceil(_Tp __x)
243 {
244 if constexpr (__have_neon_a32)
245 {
246 const auto __intrin = __to_intrin(__x);
247 if constexpr (_TVT::template _S_is<float, 2>)
248 return vrndp_f32(__intrin);
249 else if constexpr (_TVT::template _S_is<float, 4>)
250 return vrndpq_f32(__intrin);
251 else if constexpr (_TVT::template _S_is<double, 1>)
252 return vrndp_f64(__intrin);
253 else if constexpr (_TVT::template _S_is<double, 2>)
254 return vrndpq_f64(__intrin);
255 else
256 __assert_unreachable<_Tp>();
257 }
258 else
259 return _Base::_S_ceil(__x);
260 }
261
262 //}}} }}}
263 }; // }}}
264// _MaskImplNeonMixin {{{
265struct _MaskImplNeonMixin
266{
267 using _Base = _MaskImplBuiltinMixin;
268
269 template <typename _Tp, size_t _Np>
270 _GLIBCXX_SIMD_INTRINSIC static constexpr _SanitizedBitMask<_Np>
271 _S_to_bits(_SimdWrapper<_Tp, _Np> __x)
272 {
273 if (__builtin_is_constant_evaluated())
274 return _Base::_S_to_bits(__x);
275
276 using _I = __int_for_sizeof_t<_Tp>;
277 if constexpr (sizeof(__x) == 16)
278 {
279 auto __asint = __vector_bitcast<_I>(__x);
280#ifdef __aarch64__
281 [[maybe_unused]] constexpr auto __zero = decltype(__asint)();
282#else
283 [[maybe_unused]] constexpr auto __zero = decltype(__lo64(__asint))();
284#endif
285 if constexpr (sizeof(_Tp) == 1)
286 {
287 constexpr auto __bitsel
288 = __generate_from_n_evaluations<16, __vector_type_t<_I, 16>>(
289 [&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
290 return static_cast<_I>(
291 __i < _Np ? (__i < 8 ? 1 << __i : 1 << (__i - 8)) : 0);
292 });
293 __asint &= __bitsel;
294#ifdef __aarch64__
295 return __vector_bitcast<_UShort>(
296 vpaddq_s8(vpaddq_s8(vpaddq_s8(__asint, __zero), __zero),
297 __zero))[0];
298#else
299 return __vector_bitcast<_UShort>(
300 vpadd_s8(vpadd_s8(vpadd_s8(__lo64(__asint), __hi64(__asint)),
301 __zero),
302 __zero))[0];
303#endif
304 }
305 else if constexpr (sizeof(_Tp) == 2)
306 {
307 constexpr auto __bitsel
308 = __generate_from_n_evaluations<8, __vector_type_t<_I, 8>>(
309 [&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
310 return static_cast<_I>(__i < _Np ? 1 << __i : 0);
311 });
312 __asint &= __bitsel;
313#ifdef __aarch64__
314 return vaddvq_s16(__asint);
315#else
316 return vpadd_s16(
317 vpadd_s16(vpadd_s16(__lo64(__asint), __hi64(__asint)), __zero),
318 __zero)[0];
319#endif
320 }
321 else if constexpr (sizeof(_Tp) == 4)
322 {
323 constexpr auto __bitsel
324 = __generate_from_n_evaluations<4, __vector_type_t<_I, 4>>(
325 [&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
326 return static_cast<_I>(__i < _Np ? 1 << __i : 0);
327 });
328 __asint &= __bitsel;
329#ifdef __aarch64__
330 return vaddvq_s32(__asint);
331#else
332 return vpadd_s32(vpadd_s32(__lo64(__asint), __hi64(__asint)),
333 __zero)[0];
334#endif
335 }
336 else if constexpr (sizeof(_Tp) == 8)
337 return (__asint[0] & 1) | (__asint[1] & 2);
338 else
339 __assert_unreachable<_Tp>();
340 }
341 else if constexpr (sizeof(__x) == 8)
342 {
343 auto __asint = __vector_bitcast<_I>(__x);
344 [[maybe_unused]] constexpr auto __zero = decltype(__asint)();
345 if constexpr (sizeof(_Tp) == 1)
346 {
347 constexpr auto __bitsel
348 = __generate_from_n_evaluations<8, __vector_type_t<_I, 8>>(
349 [&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
350 return static_cast<_I>(__i < _Np ? 1 << __i : 0);
351 });
352 __asint &= __bitsel;
353#ifdef __aarch64__
354 return vaddv_s8(__asint);
355#else
356 return vpadd_s8(vpadd_s8(vpadd_s8(__asint, __zero), __zero),
357 __zero)[0];
358#endif
359 }
360 else if constexpr (sizeof(_Tp) == 2)
361 {
362 constexpr auto __bitsel
363 = __generate_from_n_evaluations<4, __vector_type_t<_I, 4>>(
364 [&](auto __i) _GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA {
365 return static_cast<_I>(__i < _Np ? 1 << __i : 0);
366 });
367 __asint &= __bitsel;
368#ifdef __aarch64__
369 return vaddv_s16(__asint);
370#else
371 return vpadd_s16(vpadd_s16(__asint, __zero), __zero)[0];
372#endif
373 }
374 else if constexpr (sizeof(_Tp) == 4)
375 {
376 __asint &= __make_vector<_I>(0x1, 0x2);
377#ifdef __aarch64__
378 return vaddv_s32(__asint);
379#else
380 return vpadd_s32(__asint, __zero)[0];
381#endif
382 }
383 else
384 __assert_unreachable<_Tp>();
385 }
386 else
387 return _Base::_S_to_bits(__x);
388 }
389};
390
391// }}}
392// _MaskImplNeon {{{
393template <typename _Abi, typename>
394 struct _MaskImplNeon : _MaskImplNeonMixin, _MaskImplBuiltin<_Abi>
395 {
396 using _MaskImplBuiltinMixin::_S_to_maskvector;
397 using _MaskImplNeonMixin::_S_to_bits;
398 using _Base = _MaskImplBuiltin<_Abi>;
399 using _Base::_S_convert;
400
401 // _S_all_of {{{
402 template <typename _Tp>
403 _GLIBCXX_SIMD_INTRINSIC static bool
404 _S_all_of(simd_mask<_Tp, _Abi> __k)
405 {
406 const auto __kk
407 = __vector_bitcast<char>(__k._M_data)
408 | ~__vector_bitcast<char>(_Abi::template _S_implicit_mask<_Tp>());
409 if constexpr (sizeof(__k) == 16)
410 {
411 const auto __x = __vector_bitcast<long long>(__kk);
412 return __x[0] + __x[1] == -2;
413 }
414 else if constexpr (sizeof(__k) <= 8)
415 return __bit_cast<__int_for_sizeof_t<decltype(__kk)>>(__kk) == -1;
416 else
417 __assert_unreachable<_Tp>();
418 }
419
420 // }}}
421 // _S_any_of {{{
422 template <typename _Tp>
423 _GLIBCXX_SIMD_INTRINSIC static bool
424 _S_any_of(simd_mask<_Tp, _Abi> __k)
425 {
426 const auto __kk
427 = __vector_bitcast<char>(__k._M_data)
428 | ~__vector_bitcast<char>(_Abi::template _S_implicit_mask<_Tp>());
429 if constexpr (sizeof(__k) == 16)
430 {
431 const auto __x = __vector_bitcast<long long>(__kk);
432 return (__x[0] | __x[1]) != 0;
433 }
434 else if constexpr (sizeof(__k) <= 8)
435 return __bit_cast<__int_for_sizeof_t<decltype(__kk)>>(__kk) != 0;
436 else
437 __assert_unreachable<_Tp>();
438 }
439
440 // }}}
441 // _S_none_of {{{
442 template <typename _Tp>
443 _GLIBCXX_SIMD_INTRINSIC static bool
444 _S_none_of(simd_mask<_Tp, _Abi> __k)
445 {
446 const auto __kk = _Abi::_S_masked(__k._M_data);
447 if constexpr (sizeof(__k) == 16)
448 {
449 const auto __x = __vector_bitcast<long long>(__kk);
450 return (__x[0] | __x[1]) == 0;
451 }
452 else if constexpr (sizeof(__k) <= 8)
453 return __bit_cast<__int_for_sizeof_t<decltype(__kk)>>(__kk) == 0;
454 else
455 __assert_unreachable<_Tp>();
456 }
457
458 // }}}
459 // _S_some_of {{{
460 template <typename _Tp>
461 _GLIBCXX_SIMD_INTRINSIC static bool _S_some_of(simd_mask<_Tp, _Abi> __k)
462 {
463 if constexpr (sizeof(__k) <= 8)
464 {
465 const auto __kk = __vector_bitcast<char>(__k._M_data)
466 | ~__vector_bitcast<char>(
467 _Abi::template _S_implicit_mask<_Tp>());
468 using _Up = make_unsigned_t<__int_for_sizeof_t<decltype(__kk)>>;
469 return __bit_cast<_Up>(__kk) + 1 > 1;
470 }
471 else
472 return _Base::_S_some_of(__k);
473 }
474
475 // }}}
476 // _S_popcount {{{
477 template <typename _Tp>
478 _GLIBCXX_SIMD_INTRINSIC static int
479 _S_popcount(simd_mask<_Tp, _Abi> __k)
480 {
481 if constexpr (sizeof(_Tp) == 1)
482 {
483 const auto __s8 = __vector_bitcast<_SChar>(__k._M_data);
484 int8x8_t __tmp = __lo64(__s8) + __hi64z(__s8);
485 return -vpadd_s8(vpadd_s8(vpadd_s8(__tmp, int8x8_t()), int8x8_t()),
486 int8x8_t())[0];
487 }
488 else if constexpr (sizeof(_Tp) == 2)
489 {
490 const auto __s16 = __vector_bitcast<short>(__k._M_data);
491 int16x4_t __tmp = __lo64(__s16) + __hi64z(__s16);
492 return -vpadd_s16(vpadd_s16(__tmp, int16x4_t()), int16x4_t())[0];
493 }
494 else if constexpr (sizeof(_Tp) == 4)
495 {
496 const auto __s32 = __vector_bitcast<int>(__k._M_data);
497 int32x2_t __tmp = __lo64(__s32) + __hi64z(__s32);
498 return -vpadd_s32(__tmp, int32x2_t())[0];
499 }
500 else if constexpr (sizeof(_Tp) == 8)
501 {
502 static_assert(sizeof(__k) == 16);
503 const auto __s64 = __vector_bitcast<long>(__k._M_data);
504 return -(__s64[0] + __s64[1]);
505 }
506 }
507
508 // }}}
509 // _S_find_first_set {{{
510 template <typename _Tp>
511 _GLIBCXX_SIMD_INTRINSIC static int
512 _S_find_first_set(simd_mask<_Tp, _Abi> __k)
513 {
514 // TODO: the _Base implementation is not optimal for NEON
515 return _Base::_S_find_first_set(__k);
516 }
517
518 // }}}
519 // _S_find_last_set {{{
520 template <typename _Tp>
521 _GLIBCXX_SIMD_INTRINSIC static int
522 _S_find_last_set(simd_mask<_Tp, _Abi> __k)
523 {
524 // TODO: the _Base implementation is not optimal for NEON
525 return _Base::_S_find_last_set(__k);
526 }
527
528 // }}}
529 }; // }}}
530
531_GLIBCXX_SIMD_END_NAMESPACE
532#endif // __cplusplus >= 201703L
533#endif // _GLIBCXX_EXPERIMENTAL_SIMD_NEON_H_
534// vim: foldmethod=marker sw=2 noet ts=8 sts=2 tw=80
std::make_unsigned_t
typename make_unsigned< _Tp >::type make_unsigned_t
Alias template for make_unsigned.
Definition type_traits:2273