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1 /*
2  * Copyright 2019 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SKVX_DEFINED
9 #define SKVX_DEFINED
10 
11 // skvx::Vec<N,T> are SIMD vectors of N T's, a v1.5 successor to SkNx<N,T>.
12 //
13 // This time we're leaning a bit less on platform-specific intrinsics and a bit
14 // more on Clang/GCC vector extensions, but still keeping the option open to
15 // drop in platform-specific intrinsics, actually more easily than before.
16 //
17 // We've also fixed a few of the caveats that used to make SkNx awkward to work
18 // with across translation units.  skvx::Vec<N,T> always has N*sizeof(T) size
19 // and alignment and is safe to use across translation units freely.
20 // (Ideally we'd only align to T, but that tanks ARMv7 NEON codegen.)
21 
22 #include "include/private/base/SkFeatures.h"
23 #include "src/base/SkUtils.h"
24 #include <algorithm>         // std::min, std::max
25 #include <cassert>           // assert()
26 #include <cmath>             // ceilf, floorf, truncf, roundf, sqrtf, etc.
27 #include <cstdint>           // intXX_t
28 #include <cstring>           // memcpy()
29 #include <initializer_list>  // std::initializer_list
30 #include <type_traits>
31 #include <utility>           // std::index_sequence
32 
33 // Users may disable SIMD with SKNX_NO_SIMD, which may be set via compiler flags.
34 // The gn build has no option which sets SKNX_NO_SIMD.
35 // Use SKVX_USE_SIMD internally to avoid confusing double negation.
36 // Do not use 'defined' in a macro expansion.
37 #if !defined(SKNX_NO_SIMD)
38     #define SKVX_USE_SIMD 1
39 #else
40     #define SKVX_USE_SIMD 0
41 #endif
42 
43 #if SKVX_USE_SIMD
44     #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
45         #include <immintrin.h>
46     #elif defined(SK_ARM_HAS_NEON)
47         #include <arm_neon.h>
48     #elif defined(__wasm_simd128__)
49         #include <wasm_simd128.h>
50     #elif SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LASX
51         #include <lasxintrin.h>
52         #include <lsxintrin.h>
53     #elif SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
54         #include <lsxintrin.h>
55     #endif
56 #endif
57 
58 // To avoid ODR violations, all methods must be force-inlined...
59 #if defined(_MSC_VER)
60     #define SKVX_ALWAYS_INLINE __forceinline
61 #else
62     #define SKVX_ALWAYS_INLINE __attribute__((always_inline))
63 #endif
64 
65 // ... and all standalone functions must be static.  Please use these helpers:
66 #define SI    static inline
67 #define SIT   template <       typename T> SI
68 #define SIN   template <int N            > SI
69 #define SINT  template <int N, typename T> SI
70 #define SINTU template <int N, typename T, typename U, \
71                         typename=std::enable_if_t<std::is_convertible<U,T>::value>> SI
72 
73 namespace skvx {
74 
75 template <int N, typename T>
76 struct alignas(N*sizeof(T)) Vec;
77 
78 template <int... Ix, int N, typename T>
79 SI Vec<sizeof...(Ix),T> shuffle(const Vec<N,T>&);
80 
81 // All Vec have the same simple memory layout, the same as `T vec[N]`.
82 template <int N, typename T>
83 struct alignas(N*sizeof(T)) Vec {
84     static_assert((N & (N-1)) == 0,        "N must be a power of 2.");
85     static_assert(sizeof(T) >= alignof(T), "What kind of unusual T is this?");
86 
87     // Methods belong here in the class declaration of Vec only if:
88     //   - they must be here, like constructors or operator[];
89     //   - they'll definitely never want a specialized implementation.
90     // Other operations on Vec should be defined outside the type.
91 
92     SKVX_ALWAYS_INLINE Vec() = default;
VecVec93     SKVX_ALWAYS_INLINE Vec(T s) : lo(s), hi(s) {}
94 
95     // NOTE: Vec{x} produces x000..., whereas Vec(x) produces xxxx.... since this constructor fills
96     // unspecified lanes with 0s, whereas the single T constructor fills all lanes with the value.
VecVec97     SKVX_ALWAYS_INLINE Vec(std::initializer_list<T> xs) {
98         T vals[N] = {0};
99         assert(xs.size() <= (size_t)N);
100         memcpy(vals, xs.begin(), std::min(xs.size(), (size_t)N)*sizeof(T));
101 
102         this->lo = Vec<N/2,T>::Load(vals +   0);
103         this->hi = Vec<N/2,T>::Load(vals + N/2);
104     }
105 
106     SKVX_ALWAYS_INLINE T  operator[](int i) const { return i<N/2 ? this->lo[i] : this->hi[i-N/2]; }
107     SKVX_ALWAYS_INLINE T& operator[](int i)       { return i<N/2 ? this->lo[i] : this->hi[i-N/2]; }
108 
LoadVec109     SKVX_ALWAYS_INLINE static Vec Load(const void* ptr) {
110         return sk_unaligned_load<Vec>(ptr);
111     }
storeVec112     SKVX_ALWAYS_INLINE void store(void* ptr) const {
113         // Note: Calling sk_unaligned_store produces slightly worse code here, for some reason
114         memcpy(ptr, this, sizeof(Vec));
115     }
116 
117     Vec<N/2,T> lo, hi;
118 };
119 
120 // We have specializations for N == 1 (the base-case), as well as 2 and 4, where we add helpful
121 // constructors and swizzle accessors.
122 template <typename T>
123 struct alignas(4*sizeof(T)) Vec<4,T> {
124     static_assert(sizeof(T) >= alignof(T), "What kind of unusual T is this?");
125 
126     SKVX_ALWAYS_INLINE Vec() = default;
127     SKVX_ALWAYS_INLINE Vec(T s) : lo(s), hi(s) {}
128     SKVX_ALWAYS_INLINE Vec(T x, T y, T z, T w) : lo(x,y), hi(z,w) {}
129     SKVX_ALWAYS_INLINE Vec(Vec<2,T> xy, T z, T w) : lo(xy), hi(z,w) {}
130     SKVX_ALWAYS_INLINE Vec(T x, T y, Vec<2,T> zw) : lo(x,y), hi(zw) {}
131     SKVX_ALWAYS_INLINE Vec(Vec<2,T> xy, Vec<2,T> zw) : lo(xy), hi(zw) {}
132 
133     SKVX_ALWAYS_INLINE Vec(std::initializer_list<T> xs) {
134         T vals[4] = {0};
135         assert(xs.size() <= (size_t)4);
136         memcpy(vals, xs.begin(), std::min(xs.size(), (size_t)4)*sizeof(T));
137 
138         this->lo = Vec<2,T>::Load(vals + 0);
139         this->hi = Vec<2,T>::Load(vals + 2);
140     }
141 
142     SKVX_ALWAYS_INLINE T  operator[](int i) const { return i<2 ? this->lo[i] : this->hi[i-2]; }
143     SKVX_ALWAYS_INLINE T& operator[](int i)       { return i<2 ? this->lo[i] : this->hi[i-2]; }
144 
145     SKVX_ALWAYS_INLINE static Vec Load(const void* ptr) {
146         return sk_unaligned_load<Vec>(ptr);
147     }
148     SKVX_ALWAYS_INLINE void store(void* ptr) const {
149         memcpy(ptr, this, sizeof(Vec));
150     }
151 
152     SKVX_ALWAYS_INLINE Vec<2,T>& xy() { return lo; }
153     SKVX_ALWAYS_INLINE Vec<2,T>& zw() { return hi; }
154     SKVX_ALWAYS_INLINE T& x() { return lo.lo.val; }
155     SKVX_ALWAYS_INLINE T& y() { return lo.hi.val; }
156     SKVX_ALWAYS_INLINE T& z() { return hi.lo.val; }
157     SKVX_ALWAYS_INLINE T& w() { return hi.hi.val; }
158 
159     SKVX_ALWAYS_INLINE Vec<2,T> xy() const { return lo; }
160     SKVX_ALWAYS_INLINE Vec<2,T> zw() const { return hi; }
161     SKVX_ALWAYS_INLINE T x() const { return lo.lo.val; }
162     SKVX_ALWAYS_INLINE T y() const { return lo.hi.val; }
163     SKVX_ALWAYS_INLINE T z() const { return hi.lo.val; }
164     SKVX_ALWAYS_INLINE T w() const { return hi.hi.val; }
165 
166     // Exchange-based swizzles. These should take 1 cycle on NEON and 3 (pipelined) cycles on SSE.
167     SKVX_ALWAYS_INLINE Vec<4,T> yxwz() const { return shuffle<1,0,3,2>(*this); }
168     SKVX_ALWAYS_INLINE Vec<4,T> zwxy() const { return shuffle<2,3,0,1>(*this); }
169 
170     Vec<2,T> lo, hi;
171 };
172 
173 template <typename T>
174 struct alignas(2*sizeof(T)) Vec<2,T> {
175     static_assert(sizeof(T) >= alignof(T), "What kind of unusual T is this?");
176 
177     SKVX_ALWAYS_INLINE Vec() = default;
178     SKVX_ALWAYS_INLINE Vec(T s) : lo(s), hi(s) {}
179     SKVX_ALWAYS_INLINE Vec(T x, T y) : lo(x), hi(y) {}
180 
181     SKVX_ALWAYS_INLINE Vec(std::initializer_list<T> xs) {
182         T vals[2] = {0};
183         assert(xs.size() <= (size_t)2);
184         memcpy(vals, xs.begin(), std::min(xs.size(), (size_t)2)*sizeof(T));
185 
186         this->lo = Vec<1,T>::Load(vals + 0);
187         this->hi = Vec<1,T>::Load(vals + 1);
188     }
189 
190     SKVX_ALWAYS_INLINE T  operator[](int i) const { return i<1 ? this->lo[i] : this->hi[i-1]; }
191     SKVX_ALWAYS_INLINE T& operator[](int i)       { return i<1 ? this->lo[i] : this->hi[i-1]; }
192 
193     SKVX_ALWAYS_INLINE static Vec Load(const void* ptr) {
194         return sk_unaligned_load<Vec>(ptr);
195     }
196     SKVX_ALWAYS_INLINE void store(void* ptr) const {
197         memcpy(ptr, this, sizeof(Vec));
198     }
199 
200     SKVX_ALWAYS_INLINE T& x() { return lo.val; }
201     SKVX_ALWAYS_INLINE T& y() { return hi.val; }
202 
203     SKVX_ALWAYS_INLINE T x() const { return lo.val; }
204     SKVX_ALWAYS_INLINE T y() const { return hi.val; }
205 
206     // This exchange-based swizzle should take 1 cycle on NEON and 3 (pipelined) cycles on SSE.
207     SKVX_ALWAYS_INLINE Vec<2,T> yx() const { return shuffle<1,0>(*this); }
208     SKVX_ALWAYS_INLINE Vec<4,T> xyxy() const { return Vec<4,T>(*this, *this); }
209 
210     Vec<1,T> lo, hi;
211 };
212 
213 template <typename T>
214 struct Vec<1,T> {
215     T val = {};
216 
217     SKVX_ALWAYS_INLINE Vec() = default;
218     SKVX_ALWAYS_INLINE Vec(T s) : val(s) {}
219 
220     SKVX_ALWAYS_INLINE Vec(std::initializer_list<T> xs) : val(xs.size() ? *xs.begin() : 0) {
221         assert(xs.size() <= (size_t)1);
222     }
223 
224     SKVX_ALWAYS_INLINE T  operator[](int i) const { assert(i == 0); return val; }
225     SKVX_ALWAYS_INLINE T& operator[](int i)       { assert(i == 0); return val; }
226 
227     SKVX_ALWAYS_INLINE static Vec Load(const void* ptr) {
228         return sk_unaligned_load<Vec>(ptr);
229     }
230     SKVX_ALWAYS_INLINE void store(void* ptr) const {
231         memcpy(ptr, this, sizeof(Vec));
232     }
233 };
234 
235 // Translate from a value type T to its corresponding Mask, the result of a comparison.
236 template <typename T> struct Mask { using type = T; };
237 template <> struct Mask<float > { using type = int32_t; };
238 template <> struct Mask<double> { using type = int64_t; };
239 template <typename T> using M = typename Mask<T>::type;
240 
241 // Join two Vec<N,T> into one Vec<2N,T>.
242 SINT Vec<2*N,T> join(const Vec<N,T>& lo, const Vec<N,T>& hi) {
243     Vec<2*N,T> v;
244     v.lo = lo;
245     v.hi = hi;
246     return v;
247 }
248 
249 // We have three strategies for implementing Vec operations:
250 //    1) lean on Clang/GCC vector extensions when available;
251 //    2) use map() to apply a scalar function lane-wise;
252 //    3) recurse on lo/hi to scalar portable implementations.
253 // We can slot in platform-specific implementations as overloads for particular Vec<N,T>,
254 // or often integrate them directly into the recursion of style 3), allowing fine control.
255 
256 #if SKVX_USE_SIMD && (defined(__clang__) || defined(__GNUC__))
257 
258     // VExt<N,T> types have the same size as Vec<N,T> and support most operations directly.
259     #if defined(__clang__)
260         template <int N, typename T>
261         using VExt = T __attribute__((ext_vector_type(N)));
262 
263     #elif defined(__GNUC__)
264         template <int N, typename T>
265         struct VExtHelper {
266             typedef T __attribute__((vector_size(N*sizeof(T)))) type;
267         };
268 
269         template <int N, typename T>
270         using VExt = typename VExtHelper<N,T>::type;
271 
272         // For some reason some (new!) versions of GCC cannot seem to deduce N in the generic
273         // to_vec<N,T>() below for N=4 and T=float.  This workaround seems to help...
274         SI Vec<4,float> to_vec(VExt<4,float> v) { return sk_bit_cast<Vec<4,float>>(v); }
275     #endif
276 
277     SINT VExt<N,T> to_vext(const Vec<N,T>& v) { return sk_bit_cast<VExt<N,T>>(v); }
278     SINT Vec <N,T> to_vec(const VExt<N,T>& v) { return sk_bit_cast<Vec <N,T>>(v); }
279 
280     SINT Vec<N,T> operator+(const Vec<N,T>& x, const Vec<N,T>& y) {
281         return to_vec<N,T>(to_vext(x) + to_vext(y));
282     }
283     SINT Vec<N,T> operator-(const Vec<N,T>& x, const Vec<N,T>& y) {
284         return to_vec<N,T>(to_vext(x) - to_vext(y));
285     }
286     SINT Vec<N,T> operator*(const Vec<N,T>& x, const Vec<N,T>& y) {
287         return to_vec<N,T>(to_vext(x) * to_vext(y));
288     }
289     SINT Vec<N,T> operator/(const Vec<N,T>& x, const Vec<N,T>& y) {
290         return to_vec<N,T>(to_vext(x) / to_vext(y));
291     }
292 
293     SINT Vec<N,T> operator^(const Vec<N,T>& x, const Vec<N,T>& y) {
294         return to_vec<N,T>(to_vext(x) ^ to_vext(y));
295     }
296     SINT Vec<N,T> operator&(const Vec<N,T>& x, const Vec<N,T>& y) {
297         return to_vec<N,T>(to_vext(x) & to_vext(y));
298     }
299     SINT Vec<N,T> operator|(const Vec<N,T>& x, const Vec<N,T>& y) {
300         return to_vec<N,T>(to_vext(x) | to_vext(y));
301     }
302 
303     SINT Vec<N,T> operator!(const Vec<N,T>& x) { return to_vec<N,T>(!to_vext(x)); }
304     SINT Vec<N,T> operator-(const Vec<N,T>& x) { return to_vec<N,T>(-to_vext(x)); }
305     SINT Vec<N,T> operator~(const Vec<N,T>& x) { return to_vec<N,T>(~to_vext(x)); }
306 
307     SINT Vec<N,T> operator<<(const Vec<N,T>& x, int k) { return to_vec<N,T>(to_vext(x) << k); }
308     SINT Vec<N,T> operator>>(const Vec<N,T>& x, int k) { return to_vec<N,T>(to_vext(x) >> k); }
309 
310     SINT Vec<N,M<T>> operator==(const Vec<N,T>& x, const Vec<N,T>& y) {
311         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) == to_vext(y));
312     }
313     SINT Vec<N,M<T>> operator!=(const Vec<N,T>& x, const Vec<N,T>& y) {
314         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) != to_vext(y));
315     }
316     SINT Vec<N,M<T>> operator<=(const Vec<N,T>& x, const Vec<N,T>& y) {
317         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) <= to_vext(y));
318     }
319     SINT Vec<N,M<T>> operator>=(const Vec<N,T>& x, const Vec<N,T>& y) {
320         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) >= to_vext(y));
321     }
322     SINT Vec<N,M<T>> operator< (const Vec<N,T>& x, const Vec<N,T>& y) {
323         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) <  to_vext(y));
324     }
325     SINT Vec<N,M<T>> operator> (const Vec<N,T>& x, const Vec<N,T>& y) {
326         return sk_bit_cast<Vec<N,M<T>>>(to_vext(x) >  to_vext(y));
327     }
328 
329 #else
330 
331     // Either SKNX_NO_SIMD is defined, or Clang/GCC vector extensions are not available.
332     // We'll implement things portably with N==1 scalar implementations and recursion onto them.
333 
334     // N == 1 scalar implementations.
335     SIT Vec<1,T> operator+(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val + y.val; }
336     SIT Vec<1,T> operator-(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val - y.val; }
337     SIT Vec<1,T> operator*(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val * y.val; }
338     SIT Vec<1,T> operator/(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val / y.val; }
339 
340     SIT Vec<1,T> operator^(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val ^ y.val; }
341     SIT Vec<1,T> operator&(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val & y.val; }
342     SIT Vec<1,T> operator|(const Vec<1,T>& x, const Vec<1,T>& y) { return x.val | y.val; }
343 
344     SIT Vec<1,T> operator!(const Vec<1,T>& x) { return !x.val; }
345     SIT Vec<1,T> operator-(const Vec<1,T>& x) { return -x.val; }
346     SIT Vec<1,T> operator~(const Vec<1,T>& x) { return ~x.val; }
347 
348     SIT Vec<1,T> operator<<(const Vec<1,T>& x, int k) { return x.val << k; }
349     SIT Vec<1,T> operator>>(const Vec<1,T>& x, int k) { return x.val >> k; }
350 
351     SIT Vec<1,M<T>> operator==(const Vec<1,T>& x, const Vec<1,T>& y) {
352         return x.val == y.val ? ~0 : 0;
353     }
354     SIT Vec<1,M<T>> operator!=(const Vec<1,T>& x, const Vec<1,T>& y) {
355         return x.val != y.val ? ~0 : 0;
356     }
357     SIT Vec<1,M<T>> operator<=(const Vec<1,T>& x, const Vec<1,T>& y) {
358         return x.val <= y.val ? ~0 : 0;
359     }
360     SIT Vec<1,M<T>> operator>=(const Vec<1,T>& x, const Vec<1,T>& y) {
361         return x.val >= y.val ? ~0 : 0;
362     }
363     SIT Vec<1,M<T>> operator< (const Vec<1,T>& x, const Vec<1,T>& y) {
364         return x.val <  y.val ? ~0 : 0;
365     }
366     SIT Vec<1,M<T>> operator> (const Vec<1,T>& x, const Vec<1,T>& y) {
367         return x.val >  y.val ? ~0 : 0;
368     }
369 
370     // Recurse on lo/hi down to N==1 scalar implementations.
371     SINT Vec<N,T> operator+(const Vec<N,T>& x, const Vec<N,T>& y) {
372         return join(x.lo + y.lo, x.hi + y.hi);
373     }
374     SINT Vec<N,T> operator-(const Vec<N,T>& x, const Vec<N,T>& y) {
375         return join(x.lo - y.lo, x.hi - y.hi);
376     }
377     SINT Vec<N,T> operator*(const Vec<N,T>& x, const Vec<N,T>& y) {
378         return join(x.lo * y.lo, x.hi * y.hi);
379     }
380     SINT Vec<N,T> operator/(const Vec<N,T>& x, const Vec<N,T>& y) {
381         return join(x.lo / y.lo, x.hi / y.hi);
382     }
383 
384     SINT Vec<N,T> operator^(const Vec<N,T>& x, const Vec<N,T>& y) {
385         return join(x.lo ^ y.lo, x.hi ^ y.hi);
386     }
387     SINT Vec<N,T> operator&(const Vec<N,T>& x, const Vec<N,T>& y) {
388         return join(x.lo & y.lo, x.hi & y.hi);
389     }
390     SINT Vec<N,T> operator|(const Vec<N,T>& x, const Vec<N,T>& y) {
391         return join(x.lo | y.lo, x.hi | y.hi);
392     }
393 
394     SINT Vec<N,T> operator!(const Vec<N,T>& x) { return join(!x.lo, !x.hi); }
395     SINT Vec<N,T> operator-(const Vec<N,T>& x) { return join(-x.lo, -x.hi); }
396     SINT Vec<N,T> operator~(const Vec<N,T>& x) { return join(~x.lo, ~x.hi); }
397 
398     SINT Vec<N,T> operator<<(const Vec<N,T>& x, int k) { return join(x.lo << k, x.hi << k); }
399     SINT Vec<N,T> operator>>(const Vec<N,T>& x, int k) { return join(x.lo >> k, x.hi >> k); }
400 
401     SINT Vec<N,M<T>> operator==(const Vec<N,T>& x, const Vec<N,T>& y) {
402         return join(x.lo == y.lo, x.hi == y.hi);
403     }
404     SINT Vec<N,M<T>> operator!=(const Vec<N,T>& x, const Vec<N,T>& y) {
405         return join(x.lo != y.lo, x.hi != y.hi);
406     }
407     SINT Vec<N,M<T>> operator<=(const Vec<N,T>& x, const Vec<N,T>& y) {
408         return join(x.lo <= y.lo, x.hi <= y.hi);
409     }
410     SINT Vec<N,M<T>> operator>=(const Vec<N,T>& x, const Vec<N,T>& y) {
411         return join(x.lo >= y.lo, x.hi >= y.hi);
412     }
413     SINT Vec<N,M<T>> operator< (const Vec<N,T>& x, const Vec<N,T>& y) {
414         return join(x.lo <  y.lo, x.hi <  y.hi);
415     }
416     SINT Vec<N,M<T>> operator> (const Vec<N,T>& x, const Vec<N,T>& y) {
417         return join(x.lo >  y.lo, x.hi >  y.hi);
418     }
419 #endif
420 
421 // Scalar/vector operations splat the scalar to a vector.
422 SINTU Vec<N,T>    operator+ (U x, const Vec<N,T>& y) { return Vec<N,T>(x) +  y; }
423 SINTU Vec<N,T>    operator- (U x, const Vec<N,T>& y) { return Vec<N,T>(x) -  y; }
424 SINTU Vec<N,T>    operator* (U x, const Vec<N,T>& y) { return Vec<N,T>(x) *  y; }
425 SINTU Vec<N,T>    operator/ (U x, const Vec<N,T>& y) { return Vec<N,T>(x) /  y; }
426 SINTU Vec<N,T>    operator^ (U x, const Vec<N,T>& y) { return Vec<N,T>(x) ^  y; }
427 SINTU Vec<N,T>    operator& (U x, const Vec<N,T>& y) { return Vec<N,T>(x) &  y; }
428 SINTU Vec<N,T>    operator| (U x, const Vec<N,T>& y) { return Vec<N,T>(x) |  y; }
429 SINTU Vec<N,M<T>> operator==(U x, const Vec<N,T>& y) { return Vec<N,T>(x) == y; }
430 SINTU Vec<N,M<T>> operator!=(U x, const Vec<N,T>& y) { return Vec<N,T>(x) != y; }
431 SINTU Vec<N,M<T>> operator<=(U x, const Vec<N,T>& y) { return Vec<N,T>(x) <= y; }
432 SINTU Vec<N,M<T>> operator>=(U x, const Vec<N,T>& y) { return Vec<N,T>(x) >= y; }
433 SINTU Vec<N,M<T>> operator< (U x, const Vec<N,T>& y) { return Vec<N,T>(x) <  y; }
434 SINTU Vec<N,M<T>> operator> (U x, const Vec<N,T>& y) { return Vec<N,T>(x) >  y; }
435 
436 SINTU Vec<N,T>    operator+ (const Vec<N,T>& x, U y) { return x +  Vec<N,T>(y); }
437 SINTU Vec<N,T>    operator- (const Vec<N,T>& x, U y) { return x -  Vec<N,T>(y); }
438 SINTU Vec<N,T>    operator* (const Vec<N,T>& x, U y) { return x *  Vec<N,T>(y); }
439 SINTU Vec<N,T>    operator/ (const Vec<N,T>& x, U y) { return x /  Vec<N,T>(y); }
440 SINTU Vec<N,T>    operator^ (const Vec<N,T>& x, U y) { return x ^  Vec<N,T>(y); }
441 SINTU Vec<N,T>    operator& (const Vec<N,T>& x, U y) { return x &  Vec<N,T>(y); }
442 SINTU Vec<N,T>    operator| (const Vec<N,T>& x, U y) { return x |  Vec<N,T>(y); }
443 SINTU Vec<N,M<T>> operator==(const Vec<N,T>& x, U y) { return x == Vec<N,T>(y); }
444 SINTU Vec<N,M<T>> operator!=(const Vec<N,T>& x, U y) { return x != Vec<N,T>(y); }
445 SINTU Vec<N,M<T>> operator<=(const Vec<N,T>& x, U y) { return x <= Vec<N,T>(y); }
446 SINTU Vec<N,M<T>> operator>=(const Vec<N,T>& x, U y) { return x >= Vec<N,T>(y); }
447 SINTU Vec<N,M<T>> operator< (const Vec<N,T>& x, U y) { return x <  Vec<N,T>(y); }
448 SINTU Vec<N,M<T>> operator> (const Vec<N,T>& x, U y) { return x >  Vec<N,T>(y); }
449 
450 SINT Vec<N,T>& operator+=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x + y); }
451 SINT Vec<N,T>& operator-=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x - y); }
452 SINT Vec<N,T>& operator*=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x * y); }
453 SINT Vec<N,T>& operator/=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x / y); }
454 SINT Vec<N,T>& operator^=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x ^ y); }
455 SINT Vec<N,T>& operator&=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x & y); }
456 SINT Vec<N,T>& operator|=(Vec<N,T>& x, const Vec<N,T>& y) { return (x = x | y); }
457 
458 SINTU Vec<N,T>& operator+=(Vec<N,T>& x, U y) { return (x = x + Vec<N,T>(y)); }
459 SINTU Vec<N,T>& operator-=(Vec<N,T>& x, U y) { return (x = x - Vec<N,T>(y)); }
460 SINTU Vec<N,T>& operator*=(Vec<N,T>& x, U y) { return (x = x * Vec<N,T>(y)); }
461 SINTU Vec<N,T>& operator/=(Vec<N,T>& x, U y) { return (x = x / Vec<N,T>(y)); }
462 SINTU Vec<N,T>& operator^=(Vec<N,T>& x, U y) { return (x = x ^ Vec<N,T>(y)); }
463 SINTU Vec<N,T>& operator&=(Vec<N,T>& x, U y) { return (x = x & Vec<N,T>(y)); }
464 SINTU Vec<N,T>& operator|=(Vec<N,T>& x, U y) { return (x = x | Vec<N,T>(y)); }
465 
466 SINT Vec<N,T>& operator<<=(Vec<N,T>& x, int bits) { return (x = x << bits); }
467 SINT Vec<N,T>& operator>>=(Vec<N,T>& x, int bits) { return (x = x >> bits); }
468 
469 // Some operations we want are not expressible with Clang/GCC vector extensions.
470 
471 // Clang can reason about naive_if_then_else() and optimize through it better
472 // than if_then_else(), so it's sometimes useful to call it directly when we
473 // think an entire expression should optimize away, e.g. min()/max().
474 SINT Vec<N,T> naive_if_then_else(const Vec<N,M<T>>& cond, const Vec<N,T>& t, const Vec<N,T>& e) {
475     return sk_bit_cast<Vec<N,T>>(( cond & sk_bit_cast<Vec<N, M<T>>>(t)) |
476                                  (~cond & sk_bit_cast<Vec<N, M<T>>>(e)) );
477 }
478 
479 SIT Vec<1,T> if_then_else(const Vec<1,M<T>>& cond, const Vec<1,T>& t, const Vec<1,T>& e) {
480     // In practice this scalar implementation is unlikely to be used.  See next if_then_else().
481     return sk_bit_cast<Vec<1,T>>(( cond & sk_bit_cast<Vec<1, M<T>>>(t)) |
482                                  (~cond & sk_bit_cast<Vec<1, M<T>>>(e)) );
483 }
484 SINT Vec<N,T> if_then_else(const Vec<N,M<T>>& cond, const Vec<N,T>& t, const Vec<N,T>& e) {
485     // Specializations inline here so they can generalize what types the apply to.
486 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX2
487     if constexpr (N*sizeof(T) == 32) {
488         return sk_bit_cast<Vec<N,T>>(_mm256_blendv_epi8(sk_bit_cast<__m256i>(e),
489                                                         sk_bit_cast<__m256i>(t),
490                                                         sk_bit_cast<__m256i>(cond)));
491     }
492 #endif
493 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
494     if constexpr (N*sizeof(T) == 16) {
495         return sk_bit_cast<Vec<N,T>>(_mm_blendv_epi8(sk_bit_cast<__m128i>(e),
496                                                      sk_bit_cast<__m128i>(t),
497                                                      sk_bit_cast<__m128i>(cond)));
498     }
499 #endif
500 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
501     if constexpr (N*sizeof(T) == 16) {
502         return sk_bit_cast<Vec<N,T>>(vbslq_u8(sk_bit_cast<uint8x16_t>(cond),
503                                               sk_bit_cast<uint8x16_t>(t),
504                                               sk_bit_cast<uint8x16_t>(e)));
505     }
506 #endif
507 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LASX
508     if constexpr (N*sizeof(T) == 32) {
509         return sk_bit_cast<Vec<N,T>>(__lasx_xvbitsel_v(sk_bit_cast<__m256i>(e),
510                                                        sk_bit_cast<__m256i>(t),
511                                                        sk_bit_cast<__m256i>(cond)));
512     }
513 #endif
514 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
515     if constexpr (N*sizeof(T) == 16) {
516         return sk_bit_cast<Vec<N,T>>(__lsx_vbitsel_v(sk_bit_cast<__m128i>(e),
517                                                      sk_bit_cast<__m128i>(t),
518                                                      sk_bit_cast<__m128i>(cond)));
519     }
520 #endif
521     // Recurse for large vectors to try to hit the specializations above.
522     if constexpr (N*sizeof(T) > 16) {
523         return join(if_then_else(cond.lo, t.lo, e.lo),
524                     if_then_else(cond.hi, t.hi, e.hi));
525     }
526     // This default can lead to better code than the recursing onto scalars.
527     return naive_if_then_else(cond, t, e);
528 }
529 
530 SIT  bool any(const Vec<1,T>& x) { return x.val != 0; }
531 SINT bool any(const Vec<N,T>& x) {
532     // For any(), the _mm_testz intrinsics are correct and don't require comparing 'x' to 0, so it's
533     // lower latency compared to _mm_movemask + _mm_compneq on plain SSE.
534 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX2
535     if constexpr (N*sizeof(T) == 32) {
536         return !_mm256_testz_si256(sk_bit_cast<__m256i>(x), _mm256_set1_epi32(-1));
537     }
538 #endif
539 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
540     if constexpr (N*sizeof(T) == 16) {
541         return !_mm_testz_si128(sk_bit_cast<__m128i>(x), _mm_set1_epi32(-1));
542     }
543 #endif
544 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
545     if constexpr (N*sizeof(T) == 16) {
546         // On SSE, movemask checks only the MSB in each lane, which is fine if the lanes were set
547         // directly from a comparison op (which sets all bits to 1 when true), but skvx::Vec<>
548         // treats any non-zero value as true, so we have to compare 'x' to 0 before calling movemask
549         return _mm_movemask_ps(_mm_cmpneq_ps(sk_bit_cast<__m128>(x), _mm_set1_ps(0))) != 0b0000;
550     }
551 #endif
552 #if SKVX_USE_SIMD && defined(__aarch64__)
553     // On 64-bit NEON, take the max across lanes, which will be non-zero if any lane was true.
554     // The specific lane-size doesn't really matter in this case since it's really any set bit
555     // that we're looking for.
556     if constexpr (N*sizeof(T) == 8 ) { return vmaxv_u8 (sk_bit_cast<uint8x8_t> (x)) > 0; }
557     if constexpr (N*sizeof(T) == 16) { return vmaxvq_u8(sk_bit_cast<uint8x16_t>(x)) > 0; }
558 #endif
559 #if SKVX_USE_SIMD && defined(__wasm_simd128__)
560     if constexpr (N == 4 && sizeof(T) == 4) {
561         return wasm_i32x4_any_true(sk_bit_cast<VExt<4,int>>(x));
562     }
563 #endif
564 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LASX
565     if constexpr (N*sizeof(T) == 32) {
566         v8i32 retv = (v8i32)__lasx_xvmskltz_w(__lasx_xvslt_wu(__lasx_xvldi(0),
567                                                               sk_bit_cast<__m256i>(x)));
568         return (retv[0] | retv[4]) != 0b0000;
569     }
570 #endif
571 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
572     if constexpr (N*sizeof(T) == 16) {
573         v4i32 retv = (v4i32)__lsx_vmskltz_w(__lsx_vslt_wu(__lsx_vldi(0),
574                                                           sk_bit_cast<__m128i>(x)));
575         return retv[0] != 0b0000;
576     }
577 #endif
578     return any(x.lo)
579         || any(x.hi);
580 }
581 
582 SIT  bool all(const Vec<1,T>& x) { return x.val != 0; }
583 SINT bool all(const Vec<N,T>& x) {
584 // Unlike any(), we have to respect the lane layout, or we'll miss cases where a
585 // true lane has a mix of 0 and 1 bits.
586 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
587     // Unfortunately, the _mm_testc intrinsics don't let us avoid the comparison to 0 for all()'s
588     // correctness, so always just use the plain SSE version.
589     if constexpr (N == 4 && sizeof(T) == 4) {
590         return _mm_movemask_ps(_mm_cmpneq_ps(sk_bit_cast<__m128>(x), _mm_set1_ps(0))) == 0b1111;
591     }
592 #endif
593 #if SKVX_USE_SIMD && defined(__aarch64__)
594     // On 64-bit NEON, take the min across the lanes, which will be non-zero if all lanes are != 0.
595     if constexpr (sizeof(T)==1 && N==8)  {return vminv_u8  (sk_bit_cast<uint8x8_t> (x)) > 0;}
596     if constexpr (sizeof(T)==1 && N==16) {return vminvq_u8 (sk_bit_cast<uint8x16_t>(x)) > 0;}
597     if constexpr (sizeof(T)==2 && N==4)  {return vminv_u16 (sk_bit_cast<uint16x4_t>(x)) > 0;}
598     if constexpr (sizeof(T)==2 && N==8)  {return vminvq_u16(sk_bit_cast<uint16x8_t>(x)) > 0;}
599     if constexpr (sizeof(T)==4 && N==2)  {return vminv_u32 (sk_bit_cast<uint32x2_t>(x)) > 0;}
600     if constexpr (sizeof(T)==4 && N==4)  {return vminvq_u32(sk_bit_cast<uint32x4_t>(x)) > 0;}
601 #endif
602 #if SKVX_USE_SIMD && defined(__wasm_simd128__)
603     if constexpr (N == 4 && sizeof(T) == 4) {
604         return wasm_i32x4_all_true(sk_bit_cast<VExt<4,int>>(x));
605     }
606 #endif
607 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LASX
608     if constexpr (N == 8 && sizeof(T) == 4) {
609         v8i32 retv = (v8i32)__lasx_xvmskltz_w(__lasx_xvslt_wu(__lasx_xvldi(0),
610                                                               sk_bit_cast<__m256i>(x)));
611         return (retv[0] & retv[4]) == 0b1111;
612     }
613 #endif
614 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
615     if constexpr (N == 4 && sizeof(T) == 4) {
616         v4i32 retv = (v4i32)__lsx_vmskltz_w(__lsx_vslt_wu(__lsx_vldi(0),
617                                                           sk_bit_cast<__m128i>(x)));
618         return retv[0] == 0b1111;
619     }
620 #endif
621     return all(x.lo)
622         && all(x.hi);
623 }
624 
625 // cast() Vec<N,S> to Vec<N,D>, as if applying a C-cast to each lane.
626 // TODO: implement with map()?
627 template <typename D, typename S>
628 SI Vec<1,D> cast(const Vec<1,S>& src) { return (D)src.val; }
629 
630 template <typename D, int N, typename S>
631 SI Vec<N,D> cast(const Vec<N,S>& src) {
632 #if SKVX_USE_SIMD && defined(__clang__)
633     return to_vec(__builtin_convertvector(to_vext(src), VExt<N,D>));
634 #else
635     return join(cast<D>(src.lo), cast<D>(src.hi));
636 #endif
637 }
638 
639 // min/max match logic of std::min/std::max, which is important when NaN is involved.
640 SIT  T min(const Vec<1,T>& x) { return x.val; }
641 SIT  T max(const Vec<1,T>& x) { return x.val; }
642 SINT T min(const Vec<N,T>& x) { return std::min(min(x.lo), min(x.hi)); }
643 SINT T max(const Vec<N,T>& x) { return std::max(max(x.lo), max(x.hi)); }
644 
645 SINT Vec<N,T> min(const Vec<N,T>& x, const Vec<N,T>& y) { return naive_if_then_else(y < x, y, x); }
646 SINT Vec<N,T> max(const Vec<N,T>& x, const Vec<N,T>& y) { return naive_if_then_else(x < y, y, x); }
647 
648 SINTU Vec<N,T> min(const Vec<N,T>& x, U y) { return min(x, Vec<N,T>(y)); }
649 SINTU Vec<N,T> max(const Vec<N,T>& x, U y) { return max(x, Vec<N,T>(y)); }
650 SINTU Vec<N,T> min(U x, const Vec<N,T>& y) { return min(Vec<N,T>(x), y); }
651 SINTU Vec<N,T> max(U x, const Vec<N,T>& y) { return max(Vec<N,T>(x), y); }
652 
653 // pin matches the logic of SkTPin, which is important when NaN is involved. It always returns
654 // values in the range lo..hi, and if x is NaN, it returns lo.
655 SINT Vec<N,T> pin(const Vec<N,T>& x, const Vec<N,T>& lo, const Vec<N,T>& hi) {
656     return max(lo, min(x, hi));
657 }
658 
659 // Shuffle values from a vector pretty arbitrarily:
660 //    skvx::Vec<4,float> rgba = {R,G,B,A};
661 //    shuffle<2,1,0,3>        (rgba) ~> {B,G,R,A}
662 //    shuffle<2,1>            (rgba) ~> {B,G}
663 //    shuffle<2,1,2,1,2,1,2,1>(rgba) ~> {B,G,B,G,B,G,B,G}
664 //    shuffle<3,3,3,3>        (rgba) ~> {A,A,A,A}
665 // The only real restriction is that the output also be a legal N=power-of-two sknx::Vec.
666 template <int... Ix, int N, typename T>
667 SI Vec<sizeof...(Ix),T> shuffle(const Vec<N,T>& x) {
668 #if SKVX_USE_SIMD && defined(__clang__)
669     // TODO: can we just always use { x[Ix]... }?
670     return to_vec<sizeof...(Ix),T>(__builtin_shufflevector(to_vext(x), to_vext(x), Ix...));
671 #else
672     return { x[Ix]... };
673 #endif
674 }
675 
676 // Call map(fn, x) for a vector with fn() applied to each lane of x, { fn(x[0]), fn(x[1]), ... },
677 // or map(fn, x,y) for a vector of fn(x[i], y[i]), etc.
678 
679 template <typename Fn, typename... Args, size_t... I>
680 SI auto map(std::index_sequence<I...>,
681             Fn&& fn, const Args&... args) -> skvx::Vec<sizeof...(I), decltype(fn(args[0]...))> {
682     auto lane = [&](size_t i)
683 #if defined(__clang__)
684     // CFI, specifically -fsanitize=cfi-icall, seems to give a false positive here,
685     // with errors like "control flow integrity check for type 'float (float)
686     // noexcept' failed during indirect function call... note: sqrtf.cfi_jt defined
687     // here".  But we can be quite sure fn is the right type: it's all inferred!
688     // So, stifle CFI in this function.
689     __attribute__((no_sanitize("cfi")))
690 #endif
691     { return fn(args[static_cast<int>(i)]...); };
692 
693     return { lane(I)... };
694 }
695 
696 template <typename Fn, int N, typename T, typename... Rest>
697 auto map(Fn&& fn, const Vec<N,T>& first, const Rest&... rest) {
698     // Derive an {0...N-1} index_sequence from the size of the first arg: N lanes in, N lanes out.
699     return map(std::make_index_sequence<N>{}, fn, first,rest...);
700 }
701 
702 SIN Vec<N,float>  ceil(const Vec<N,float>& x) { return map( ceilf, x); }
703 SIN Vec<N,float> floor(const Vec<N,float>& x) { return map(floorf, x); }
704 SIN Vec<N,float> trunc(const Vec<N,float>& x) { return map(truncf, x); }
705 SIN Vec<N,float> round(const Vec<N,float>& x) { return map(roundf, x); }
706 SIN Vec<N,float>  sqrt(const Vec<N,float>& x) { return map( sqrtf, x); }
707 SIN Vec<N,float>   abs(const Vec<N,float>& x) { return map( fabsf, x); }
708 SIN Vec<N,float>   fma(const Vec<N,float>& x,
709                        const Vec<N,float>& y,
710                        const Vec<N,float>& z) {
711     // I don't understand why Clang's codegen is terrible if we write map(fmaf, x,y,z) directly.
712     auto fn = [](float x, float y, float z) { return fmaf(x,y,z); };
713     return map(fn, x,y,z);
714 }
715 
716 SI Vec<1,int> lrint(const Vec<1,float>& x) {
717     return (int)lrintf(x.val);
718 }
719 SIN Vec<N,int> lrint(const Vec<N,float>& x) {
720 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX
721     if constexpr (N == 8) {
722         return sk_bit_cast<Vec<N,int>>(_mm256_cvtps_epi32(sk_bit_cast<__m256>(x)));
723     }
724 #endif
725 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
726     if constexpr (N == 4) {
727         return sk_bit_cast<Vec<N,int>>(_mm_cvtps_epi32(sk_bit_cast<__m128>(x)));
728     }
729 #endif
730 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LASX
731     if constexpr (N == 8) {
732         return sk_bit_cast<Vec<N,int>>(__lasx_xvftint_w_s(sk_bit_cast<__m256>(x)));
733     }
734 #endif
735 #if SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
736     if constexpr (N == 4) {
737         return sk_bit_cast<Vec<N,int>>(__lsx_vftint_w_s(sk_bit_cast<__m128>(x)));
738     }
739 #endif
740     return join(lrint(x.lo),
741                 lrint(x.hi));
742 }
743 
744 SIN Vec<N,float> fract(const Vec<N,float>& x) { return x - floor(x); }
745 
746 // Converts float to half, rounding to nearest even, and supporting de-normal f16 conversion,
747 // and overflow to f16 infinity. Should not be called with NaNs, since it can convert NaN->inf.
748 // KEEP IN SYNC with skcms' Half_from_F to ensure that f16 colors are computed consistently in both
749 // skcms and skvx.
750 SIN Vec<N,uint16_t> to_half(const Vec<N,float>& x) {
751     assert(all(x == x)); // No NaNs should reach this function
752 
753     // Intrinsics for float->half tend to operate on 4 lanes, and the default implementation has
754     // enough instructions that it's better to split and join on 128 bits groups vs.
755     // recursing for each min/max/shift/etc.
756     if constexpr (N > 4) {
757         return join(to_half(x.lo),
758                     to_half(x.hi));
759     }
760 
761 #if SKVX_USE_SIMD && defined(__aarch64__)
762     if constexpr (N == 4) {
763         return sk_bit_cast<Vec<N,uint16_t>>(vcvt_f16_f32(sk_bit_cast<float32x4_t>(x)));
764 
765     }
766 #endif
767 
768 #define I(x) sk_bit_cast<Vec<N,int32_t>>(x)
769 #define F(x) sk_bit_cast<Vec<N,float>>(x)
770     Vec<N,int32_t> sem = I(x),
771                    s   = sem & 0x8000'0000,
772                     em = min(sem ^ s, 0x4780'0000), // |x| clamped to f16 infinity
773                  // F(em)*8192 increases the exponent by 13, which when added back to em will shift
774                  // the mantissa bits 13 to the right. We clamp to 1/2 for subnormal values, which
775                  // automatically shifts the mantissa to match 2^-14 expected for a subnorm f16.
776                  magic = I(max(F(em) * 8192.f, 0.5f)) & (255 << 23),
777                rounded = I((F(em) + F(magic))), // shift mantissa with automatic round-to-even
778                    // Subtract 127 for f32 bias, subtract 13 to undo the *8192, subtract 1 to remove
779                    // the implicit leading 1., and add 15 to get the f16 biased exponent.
780                    exp = ((magic >> 13) - ((127-15+13+1)<<10)), // shift and re-bias exponent
781                    f16 = rounded + exp; // use + if 'rounded' rolled over into first exponent bit
782     return cast<uint16_t>((s>>16) | f16);
783 #undef I
784 #undef F
785 }
786 
787 // Converts from half to float, preserving NaN and +/- infinity.
788 // KEEP IN SYNC with skcms' F_from_Half to ensure that f16 colors are computed consistently in both
789 // skcms and skvx.
790 SIN Vec<N,float> from_half(const Vec<N,uint16_t>& x) {
791     if constexpr (N > 4) {
792         return join(from_half(x.lo),
793                     from_half(x.hi));
794     }
795 
796 #if SKVX_USE_SIMD && defined(__aarch64__)
797     if constexpr (N == 4) {
798         return sk_bit_cast<Vec<N,float>>(vcvt_f32_f16(sk_bit_cast<float16x4_t>(x)));
799     }
800 #endif
801 
802     Vec<N,int32_t> wide = cast<int32_t>(x),
803                       s  = wide & 0x8000,
804                       em = wide ^ s,
805               inf_or_nan =  (em >= (31 << 10)) & (255 << 23),  // Expands exponent to fill 8 bits
806                  is_norm =   em > 0x3ff,
807                      // subnormal f16's are 2^-14*0.[m0:9] == 2^-24*[m0:9].0
808                      sub = sk_bit_cast<Vec<N,int32_t>>((cast<float>(em) * (1.f/(1<<24)))),
809                     norm = ((em<<13) + ((127-15)<<23)), // Shifts mantissa, shifts + re-biases exp
810                   finite = (is_norm & norm) | (~is_norm & sub);
811     // If 'x' is f16 +/- infinity, inf_or_nan will be the filled 8-bit exponent but 'norm' will be
812     // all 0s since 'x's mantissa is 0. Thus norm | inf_or_nan becomes f32 infinity. However, if
813     // 'x' is an f16 NaN, some bits of 'norm' will be non-zero, so it stays an f32 NaN after the OR.
814     return sk_bit_cast<Vec<N,float>>((s<<16) | finite | inf_or_nan);
815 }
816 
817 // div255(x) = (x + 127) / 255 is a bit-exact rounding divide-by-255, packing down to 8-bit.
818 SIN Vec<N,uint8_t> div255(const Vec<N,uint16_t>& x) {
819     return cast<uint8_t>( (x+127)/255 );
820 }
821 
822 // approx_scale(x,y) approximates div255(cast<uint16_t>(x)*cast<uint16_t>(y)) within a bit,
823 // and is always perfect when x or y is 0 or 255.
824 SIN Vec<N,uint8_t> approx_scale(const Vec<N,uint8_t>& x, const Vec<N,uint8_t>& y) {
825     // All of (x*y+x)/256, (x*y+y)/256, and (x*y+255)/256 meet the criteria above.
826     // We happen to have historically picked (x*y+x)/256.
827     auto X = cast<uint16_t>(x),
828          Y = cast<uint16_t>(y);
829     return cast<uint8_t>( (X*Y+X)/256 );
830 }
831 
832 // saturated_add(x,y) sums values and clamps to the maximum value instead of overflowing.
833 SINT std::enable_if_t<std::is_unsigned_v<T>, Vec<N,T>> saturated_add(const Vec<N,T>& x,
834                                                                      const Vec<N,T>& y) {
835 #if SKVX_USE_SIMD && (SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1 || defined(SK_ARM_HAS_NEON) || \
836         SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX)
837     // Both SSE and ARM have 16-lane saturated adds, so use intrinsics for those and recurse down
838     // or join up to take advantage.
839     if constexpr (N == 16 && sizeof(T) == 1) {
840         #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
841         return sk_bit_cast<Vec<N,T>>(_mm_adds_epu8(sk_bit_cast<__m128i>(x),
842                                                    sk_bit_cast<__m128i>(y)));
843         #elif SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
844         return sk_bit_cast<Vec<N,T>>(__lsx_vsadd_bu(sk_bit_cast<__m128i>(x),
845                                                     sk_bit_cast<__m128i>(y)));
846         #else  // SK_ARM_HAS_NEON
847         return sk_bit_cast<Vec<N,T>>(vqaddq_u8(sk_bit_cast<uint8x16_t>(x),
848                                                sk_bit_cast<uint8x16_t>(y)));
849         #endif
850     } else if constexpr (N < 16 && sizeof(T) == 1) {
851         return saturated_add(join(x,x), join(y,y)).lo;
852     } else if constexpr (sizeof(T) == 1) {
853         return join(saturated_add(x.lo, y.lo), saturated_add(x.hi, y.hi));
854     }
855 #endif
856     // Otherwise saturate manually
857     auto sum = x + y;
858     return if_then_else(sum < x, Vec<N,T>(std::numeric_limits<T>::max()), sum);
859 }
860 
861 // The ScaledDividerU32 takes a divisor > 1, and creates a function divide(numerator) that
862 // calculates a numerator / denominator. For this to be rounded properly, numerator should have
863 // half added in:
864 // divide(numerator + half) == floor(numerator/denominator + 1/2).
865 //
866 // This gives an answer within +/- 1 from the true value.
867 //
868 // Derivation of half:
869 //    numerator/denominator + 1/2 = (numerator + half) / d
870 //    numerator + denominator / 2 = numerator + half
871 //    half = denominator / 2.
872 //
873 // Because half is divided by 2, that division must also be rounded.
874 //    half == denominator / 2 = (denominator + 1) / 2.
875 //
876 // The divisorFactor is just a scaled value:
877 //    divisorFactor = (1 / divisor) * 2 ^ 32.
878 // The maximum that can be divided and rounded is UINT_MAX - half.
879 class ScaledDividerU32 {
880 public:
881     explicit ScaledDividerU32(uint32_t divisor)
882             : fDivisorFactor{(uint32_t)(std::round((1.0 / divisor) * (1ull << 32)))}
883             , fHalf{(divisor + 1) >> 1} {
884         assert(divisor > 1);
885     }
886 
887     Vec<4, uint32_t> divide(const Vec<4, uint32_t>& numerator) const {
888 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
889         uint64x2_t hi = vmull_n_u32(vget_high_u32(to_vext(numerator)), fDivisorFactor);
890         uint64x2_t lo = vmull_n_u32(vget_low_u32(to_vext(numerator)),  fDivisorFactor);
891 
892         return to_vec<4, uint32_t>(vcombine_u32(vshrn_n_u64(lo,32), vshrn_n_u64(hi,32)));
893 #else
894         return cast<uint32_t>((cast<uint64_t>(numerator) * fDivisorFactor) >> 32);
895 #endif
896     }
897 
898     uint32_t half() const { return fHalf; }
899 
900 private:
901     const uint32_t fDivisorFactor;
902     const uint32_t fHalf;
903 };
904 
905 
906 SIN Vec<N,uint16_t> mull(const Vec<N,uint8_t>& x,
907                          const Vec<N,uint8_t>& y) {
908 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
909     // With NEON we can do eight u8*u8 -> u16 in one instruction, vmull_u8 (read, mul-long).
910     if constexpr (N == 8) {
911         return to_vec<8,uint16_t>(vmull_u8(to_vext(x), to_vext(y)));
912     } else if constexpr (N < 8) {
913         return mull(join(x,x), join(y,y)).lo;
914     } else { // N > 8
915         return join(mull(x.lo, y.lo), mull(x.hi, y.hi));
916     }
917 #else
918     return cast<uint16_t>(x) * cast<uint16_t>(y);
919 #endif
920 }
921 
922 SIN Vec<N,uint32_t> mull(const Vec<N,uint16_t>& x,
923                          const Vec<N,uint16_t>& y) {
924 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
925     // NEON can do four u16*u16 -> u32 in one instruction, vmull_u16
926     if constexpr (N == 4) {
927         return to_vec<4,uint32_t>(vmull_u16(to_vext(x), to_vext(y)));
928     } else if constexpr (N < 4) {
929         return mull(join(x,x), join(y,y)).lo;
930     } else { // N > 4
931         return join(mull(x.lo, y.lo), mull(x.hi, y.hi));
932     }
933 #else
934     return cast<uint32_t>(x) * cast<uint32_t>(y);
935 #endif
936 }
937 
938 SIN Vec<N,uint16_t> mulhi(const Vec<N,uint16_t>& x,
939                           const Vec<N,uint16_t>& y) {
940 #if SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
941     // Use _mm_mulhi_epu16 for 8xuint16_t and join or split to get there.
942     if constexpr (N == 8) {
943         return sk_bit_cast<Vec<8,uint16_t>>(_mm_mulhi_epu16(sk_bit_cast<__m128i>(x),
944                                                             sk_bit_cast<__m128i>(y)));
945     } else if constexpr (N < 8) {
946         return mulhi(join(x,x), join(y,y)).lo;
947     } else { // N > 8
948         return join(mulhi(x.lo, y.lo), mulhi(x.hi, y.hi));
949     }
950 #elif SKVX_USE_SIMD && SK_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
951     if constexpr (N == 8) {
952         return sk_bit_cast<Vec<8,uint16_t>>(__lsx_vmuh_hu(sk_bit_cast<__m128i>(x),
953                                                           sk_bit_cast<__m128i>(y)));
954     } else if constexpr (N < 8) {
955         return mulhi(join(x,x), join(y,y)).lo;
956     } else { // N > 8
957         return join(mulhi(x.lo, y.lo), mulhi(x.hi, y.hi));
958     }
959 #else
960     return skvx::cast<uint16_t>(mull(x, y) >> 16);
961 #endif
962 }
963 
964 SINT T dot(const Vec<N, T>& a, const Vec<N, T>& b) {
965     // While dot is a "horizontal" operation like any or all, it needs to remain
966     // in floating point and there aren't really any good SIMD instructions that make it faster.
967     // The constexpr cases remove the for loop in the only cases we realistically call.
968     auto ab = a*b;
969     if constexpr (N == 2) {
970         return ab[0] + ab[1];
971     } else if constexpr (N == 4) {
972         return ab[0] + ab[1] + ab[2] + ab[3];
973     } else {
974         T sum = ab[0];
975         for (int i = 1; i < N; ++i) {
976             sum += ab[i];
977         }
978         return sum;
979     }
980 }
981 
982 SIT T cross(const Vec<2, T>& a, const Vec<2, T>& b) {
983     auto x = a * shuffle<1,0>(b);
984     return x[0] - x[1];
985 }
986 
987 SIN float length(const Vec<N, float>& v) {
988     return std::sqrt(dot(v, v));
989 }
990 
991 SIN double length(const Vec<N, double>& v) {
992     return std::sqrt(dot(v, v));
993 }
994 
995 SIN Vec<N, float> normalize(const Vec<N, float>& v) {
996     return v / length(v);
997 }
998 
999 SIN Vec<N, double> normalize(const Vec<N, double>& v) {
1000     return v / length(v);
1001 }
1002 
1003 SINT bool isfinite(const Vec<N, T>& v) {
1004     // Multiply all values together with 0. If they were all finite, the output is
1005     // 0 (also finite). If any were not, we'll get nan.
1006     return SkIsFinite(dot(v, Vec<N, T>(0)));
1007 }
1008 
1009 // De-interleaving load of 4 vectors.
1010 //
1011 // WARNING: These are really only supported well on NEON. Consider restructuring your data before
1012 // resorting to these methods.
1013 SIT void strided_load4(const T* v,
1014                        Vec<1,T>& a,
1015                        Vec<1,T>& b,
1016                        Vec<1,T>& c,
1017                        Vec<1,T>& d) {
1018     a.val = v[0];
1019     b.val = v[1];
1020     c.val = v[2];
1021     d.val = v[3];
1022 }
1023 SINT void strided_load4(const T* v,
1024                         Vec<N,T>& a,
1025                         Vec<N,T>& b,
1026                         Vec<N,T>& c,
1027                         Vec<N,T>& d) {
1028     strided_load4(v, a.lo, b.lo, c.lo, d.lo);
1029     strided_load4(v + 4*(N/2), a.hi, b.hi, c.hi, d.hi);
1030 }
1031 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
1032 #define IMPL_LOAD4_TRANSPOSED(N, T, VLD) \
1033 SI void strided_load4(const T* v, \
1034                       Vec<N,T>& a, \
1035                       Vec<N,T>& b, \
1036                       Vec<N,T>& c, \
1037                       Vec<N,T>& d) { \
1038     auto mat = VLD(v); \
1039     a = sk_bit_cast<Vec<N,T>>(mat.val[0]); \
1040     b = sk_bit_cast<Vec<N,T>>(mat.val[1]); \
1041     c = sk_bit_cast<Vec<N,T>>(mat.val[2]); \
1042     d = sk_bit_cast<Vec<N,T>>(mat.val[3]); \
1043 }
1044 IMPL_LOAD4_TRANSPOSED(2, uint32_t, vld4_u32)
1045 IMPL_LOAD4_TRANSPOSED(4, uint16_t, vld4_u16)
1046 IMPL_LOAD4_TRANSPOSED(8, uint8_t, vld4_u8)
1047 IMPL_LOAD4_TRANSPOSED(2, int32_t, vld4_s32)
1048 IMPL_LOAD4_TRANSPOSED(4, int16_t, vld4_s16)
1049 IMPL_LOAD4_TRANSPOSED(8, int8_t, vld4_s8)
1050 IMPL_LOAD4_TRANSPOSED(2, float, vld4_f32)
1051 IMPL_LOAD4_TRANSPOSED(4, uint32_t, vld4q_u32)
1052 IMPL_LOAD4_TRANSPOSED(8, uint16_t, vld4q_u16)
1053 IMPL_LOAD4_TRANSPOSED(16, uint8_t, vld4q_u8)
1054 IMPL_LOAD4_TRANSPOSED(4, int32_t, vld4q_s32)
1055 IMPL_LOAD4_TRANSPOSED(8, int16_t, vld4q_s16)
1056 IMPL_LOAD4_TRANSPOSED(16, int8_t, vld4q_s8)
1057 IMPL_LOAD4_TRANSPOSED(4, float, vld4q_f32)
1058 #undef IMPL_LOAD4_TRANSPOSED
1059 
1060 #elif SKVX_USE_SIMD && SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
1061 
1062 SI void strided_load4(const float* v,
1063                       Vec<4,float>& a,
1064                       Vec<4,float>& b,
1065                       Vec<4,float>& c,
1066                       Vec<4,float>& d) {
1067     __m128 a_ = _mm_loadu_ps(v);
1068     __m128 b_ = _mm_loadu_ps(v+4);
1069     __m128 c_ = _mm_loadu_ps(v+8);
1070     __m128 d_ = _mm_loadu_ps(v+12);
1071     _MM_TRANSPOSE4_PS(a_, b_, c_, d_);
1072     a = sk_bit_cast<Vec<4,float>>(a_);
1073     b = sk_bit_cast<Vec<4,float>>(b_);
1074     c = sk_bit_cast<Vec<4,float>>(c_);
1075     d = sk_bit_cast<Vec<4,float>>(d_);
1076 }
1077 
1078 #elif SKVX_USE_SIMD && SKVX_CPU_LSX_LEVEL >= SK_CPU_LSX_LEVEL_LSX
1079 #define _LSX_TRANSPOSE4(row0, row1, row2, row3) \
1080 do {                                            \
1081     __m128i __t0 = __lsx_vilvl_w (row1, row0);  \
1082     __m128i __t1 = __lsx_vilvl_w (row3, row2);  \
1083     __m128i __t2 = __lsx_vilvh_w (row1, row0);  \
1084     __m128i __t3 = __lsx_vilvh_w (row3, row2);  \
1085     (row0) = __lsx_vilvl_d (__t1, __t0);        \
1086     (row1) = __lsx_vilvh_d (__t1, __t0);        \
1087     (row2) = __lsx_vilvl_d (__t3, __t2);        \
1088     (row3) = __lsx_vilvh_d (__t3, __t2);        \
1089 } while (0)
1090 
1091 SI void strided_load4(const int* v,
1092                       Vec<4,int>& a,
1093                       Vec<4,int>& b,
1094                       Vec<4,int>& c,
1095                       Vec<4,int>& d) {
1096     __m128i a_ = __lsx_vld(v, 0);
1097     __m128i b_ = __lsx_vld(v, 16);
1098     __m128i c_ = __lsx_vld(v, 32);
1099     __m128i d_ = __lsx_vld(v, 48);
1100     _LSX_TRANSPOSE4(a_, b_, c_, d_);
1101     a = sk_bit_cast<Vec<4,int>>(a_);
1102     b = sk_bit_cast<Vec<4,int>>(b_);
1103     c = sk_bit_cast<Vec<4,int>>(c_);
1104     d = sk_bit_cast<Vec<4,int>>(d_);
1105 }
1106 #endif
1107 
1108 // De-interleaving load of 2 vectors.
1109 //
1110 // WARNING: These are really only supported well on NEON. Consider restructuring your data before
1111 // resorting to these methods.
1112 SIT void strided_load2(const T* v, Vec<1,T>& a, Vec<1,T>& b) {
1113     a.val = v[0];
1114     b.val = v[1];
1115 }
1116 SINT void strided_load2(const T* v, Vec<N,T>& a, Vec<N,T>& b) {
1117     strided_load2(v, a.lo, b.lo);
1118     strided_load2(v + 2*(N/2), a.hi, b.hi);
1119 }
1120 #if SKVX_USE_SIMD && defined(SK_ARM_HAS_NEON)
1121 #define IMPL_LOAD2_TRANSPOSED(N, T, VLD) \
1122 SI void strided_load2(const T* v, Vec<N,T>& a, Vec<N,T>& b) { \
1123     auto mat = VLD(v); \
1124     a = sk_bit_cast<Vec<N,T>>(mat.val[0]); \
1125     b = sk_bit_cast<Vec<N,T>>(mat.val[1]); \
1126 }
1127 IMPL_LOAD2_TRANSPOSED(2, uint32_t, vld2_u32)
1128 IMPL_LOAD2_TRANSPOSED(4, uint16_t, vld2_u16)
1129 IMPL_LOAD2_TRANSPOSED(8, uint8_t, vld2_u8)
1130 IMPL_LOAD2_TRANSPOSED(2, int32_t, vld2_s32)
1131 IMPL_LOAD2_TRANSPOSED(4, int16_t, vld2_s16)
1132 IMPL_LOAD2_TRANSPOSED(8, int8_t, vld2_s8)
1133 IMPL_LOAD2_TRANSPOSED(2, float, vld2_f32)
1134 IMPL_LOAD2_TRANSPOSED(4, uint32_t, vld2q_u32)
1135 IMPL_LOAD2_TRANSPOSED(8, uint16_t, vld2q_u16)
1136 IMPL_LOAD2_TRANSPOSED(16, uint8_t, vld2q_u8)
1137 IMPL_LOAD2_TRANSPOSED(4, int32_t, vld2q_s32)
1138 IMPL_LOAD2_TRANSPOSED(8, int16_t, vld2q_s16)
1139 IMPL_LOAD2_TRANSPOSED(16, int8_t, vld2q_s8)
1140 IMPL_LOAD2_TRANSPOSED(4, float, vld2q_f32)
1141 #undef IMPL_LOAD2_TRANSPOSED
1142 #endif
1143 
1144 // Define commonly used aliases
1145 using float2  = Vec< 2, float>;
1146 using float4  = Vec< 4, float>;
1147 using float8  = Vec< 8, float>;
1148 
1149 using double2 = Vec< 2, double>;
1150 using double4 = Vec< 4, double>;
1151 using double8 = Vec< 8, double>;
1152 
1153 using byte2   = Vec< 2, uint8_t>;
1154 using byte4   = Vec< 4, uint8_t>;
1155 using byte8   = Vec< 8, uint8_t>;
1156 using byte16  = Vec<16, uint8_t>;
1157 
1158 using int2    = Vec< 2, int32_t>;
1159 using int4    = Vec< 4, int32_t>;
1160 using int8    = Vec< 8, int32_t>;
1161 
1162 using ushort2 = Vec< 2, uint16_t>;
1163 using ushort4 = Vec< 4, uint16_t>;
1164 using ushort8 = Vec< 8, uint16_t>;
1165 
1166 using uint2   = Vec< 2, uint32_t>;
1167 using uint4   = Vec< 4, uint32_t>;
1168 using uint8   = Vec< 8, uint32_t>;
1169 
1170 using long2   = Vec< 2, int64_t>;
1171 using long4   = Vec< 4, int64_t>;
1172 using long8   = Vec< 8, int64_t>;
1173 
1174 // Use with from_half and to_half to convert between floatX, and use these for storage.
1175 using half2   = Vec< 2, uint16_t>;
1176 using half4   = Vec< 4, uint16_t>;
1177 using half8   = Vec< 8, uint16_t>;
1178 
1179 }  // namespace skvx
1180 
1181 #undef SINTU
1182 #undef SINT
1183 #undef SIN
1184 #undef SIT
1185 #undef SI
1186 #undef SKVX_ALWAYS_INLINE
1187 #undef SKVX_USE_SIMD
1188 
1189 #endif//SKVX_DEFINED
1190