Add divide to Sk2x, use native vdiv and vsqrt on ARM 64.

src/opts/Sk2x_sse.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // It is important _not_ to put header guards here.
 // This file will be intentionally included three times.
 
@@ skipping 20 matching lines @@
 M(Sk2f&) operator=(const Sk2f& o) { fVec = o.fVec; return *this; }
 
 M(Sk2f) Load(const float vals[2]) {
     return _mm_castsi128_ps(_mm_loadl_epi64((const __m128i*)vals));
 }
 M(void) store(float vals[2]) const { _mm_storel_pi((__m64*)vals, fVec); }
 
 M(Sk2f)      add(const Sk2f& o) const { return _mm_add_ps(fVec, o.fVec); }
 M(Sk2f) subtract(const Sk2f& o) const { return _mm_sub_ps(fVec, o.fVec); }
 M(Sk2f) multiply(const Sk2f& o) const { return _mm_mul_ps(fVec, o.fVec); }
+M(Sk2f)   divide(const Sk2f& o) const { return _mm_div_ps(fVec, o.fVec); }
 
 M(Sk2f) Min(const Sk2f& a, const Sk2f& b) { return _mm_min_ps(a.fVec, b.fVec); }
 M(Sk2f) Max(const Sk2f& a, const Sk2f& b) { return _mm_max_ps(a.fVec, b.fVec); }
 
 M(Sk2f) rsqrt() const { return _mm_rsqrt_ps(fVec); }
 M(Sk2f)  sqrt() const { return _mm_sqrt_ps (fVec); }
 
 #undef M
 
 #define M(...) template <> inline __VA_ARGS__ Sk2x<double>::
 
 M() Sk2x() {}
 M() Sk2x(double val)         { fVec = _mm_set1_pd(val);    }
 M() Sk2x(double a, double b) { fVec = _mm_set_pd(b, a);    }
 M(Sk2d&) operator=(const Sk2d& o) { fVec = o.fVec; return *this; }
 
 M(Sk2d) Load(const double vals[2]) { return _mm_loadu_pd(vals); }
 M(void) store(double vals[2]) const { _mm_storeu_pd(vals, fVec); }
 
 M(Sk2d)      add(const Sk2d& o) const { return _mm_add_pd(fVec, o.fVec); }
 M(Sk2d) subtract(const Sk2d& o) const { return _mm_sub_pd(fVec, o.fVec); }
 M(Sk2d) multiply(const Sk2d& o) const { return _mm_mul_pd(fVec, o.fVec); }
+M(Sk2d)   divide(const Sk2d& o) const { return _mm_div_pd(fVec, o.fVec); }
 
 M(Sk2d) Min(const Sk2d& a, const Sk2d& b) { return _mm_min_pd(a.fVec, b.fVec); }
 M(Sk2d) Max(const Sk2d& a, const Sk2d& b) { return _mm_max_pd(a.fVec, b.fVec); }
 
 // There is no _mm_rsqrt_pd, so we do Sk2d::rsqrt() in floats.
 M(Sk2d) rsqrt() const { return _mm_cvtps_pd(_mm_rsqrt_ps(_mm_cvtpd_ps(fVec))); }
 M(Sk2d)  sqrt() const { return _mm_sqrt_pd(fVec); }
 
 #undef M
 
 #endif