Add SkNx_cast().

src/opts/SkNx_avx.h

Index: src/opts/SkNx_avx.h
diff --git a/src/opts/SkNx_avx.h b/src/opts/SkNx_avx.h
index 86caac20b659bafe61e97cc7522d1f3d97c67207..9697303e37bcc9000c293fd8cb86387556fa7f4b 100644
--- a/src/opts/SkNx_avx.h
+++ b/src/opts/SkNx_avx.h
@@ -16,15 +16,15 @@
 namespace {  // See SkNx.h
 
 template <>
-class SkNf<8> {
+class SkNx<8, float> {
 public:
-    SkNf(const __m256& vec) : fVec(vec) {}
+    SkNx(const __m256& vec) : fVec(vec) {}
 
-    SkNf() {}
-    SkNf(float val) : fVec(_mm256_set1_ps(val)) {}
-    static SkNf Load(const float vals[8]) { return _mm256_loadu_ps(vals); }
+    SkNx() {}
+    SkNx(float val) : fVec(_mm256_set1_ps(val)) {}
+    static SkNx Load(const float vals[8]) { return _mm256_loadu_ps(vals); }
 
-    static SkNf FromBytes(const uint8_t bytes[8]) {
+    static SkNx FromBytes(const uint8_t bytes[8]) {
         __m128i fix8  = _mm_loadl_epi64((const __m128i*)bytes),
                 fix16 = _mm_unpacklo_epi8 (fix8 , _mm_setzero_si128()),
                  lo32 = _mm_unpacklo_epi16(fix16, _mm_setzero_si128()),
@@ -33,7 +33,7 @@ public:
         return _mm256_cvtepi32_ps(fix32);
     }
 
-    SkNf(float a, float b, float c, float d,
+    SkNx(float a, float b, float c, float d,
          float e, float f, float g, float h) : fVec(_mm256_setr_ps(a,b,c,d,e,f,g,h)) {}
 
     void store(float vals[8]) const { _mm256_storeu_ps(vals, fVec); }
@@ -46,28 +46,28 @@ public:
         _mm_storel_epi64((__m128i*)bytes, fix8);
     }
 
-    SkNf operator + (const SkNf& o) const { return _mm256_add_ps(fVec, o.fVec); }
-    SkNf operator - (const SkNf& o) const { return _mm256_sub_ps(fVec, o.fVec); }
-    SkNf operator * (const SkNf& o) const { return _mm256_mul_ps(fVec, o.fVec); }
-    SkNf operator / (const SkNf& o) const { return _mm256_div_ps(fVec, o.fVec); }
+    SkNx operator + (const SkNx& o) const { return _mm256_add_ps(fVec, o.fVec); }
+    SkNx operator - (const SkNx& o) const { return _mm256_sub_ps(fVec, o.fVec); }
+    SkNx operator * (const SkNx& o) const { return _mm256_mul_ps(fVec, o.fVec); }
+    SkNx operator / (const SkNx& o) const { return _mm256_div_ps(fVec, o.fVec); }
 
-    SkNf operator == (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_EQ_OQ); }
-    SkNf operator != (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_NEQ_OQ); }
-    SkNf operator  < (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_LT_OQ); }
-    SkNf operator  > (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_GT_OQ); }
-    SkNf operator <= (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_LE_OQ); }
-    SkNf operator >= (const SkNf& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_GE_OQ); }
+    SkNx operator == (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_EQ_OQ); }
+    SkNx operator != (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_NEQ_OQ); }
+    SkNx operator  < (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_LT_OQ); }
+    SkNx operator  > (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_GT_OQ); }
+    SkNx operator <= (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_LE_OQ); }
+    SkNx operator >= (const SkNx& o) const { return _mm256_cmp_ps(fVec, o.fVec, _CMP_GE_OQ); }
 
-    static SkNf Min(const SkNf& l, const SkNf& r) { return _mm256_min_ps(l.fVec, r.fVec); }
-    static SkNf Max(const SkNf& l, const SkNf& r) { return _mm256_max_ps(l.fVec, r.fVec); }
+    static SkNx Min(const SkNx& l, const SkNx& r) { return _mm256_min_ps(l.fVec, r.fVec); }
+    static SkNx Max(const SkNx& l, const SkNx& r) { return _mm256_max_ps(l.fVec, r.fVec); }
 
-    SkNf  sqrt() const { return _mm256_sqrt_ps (fVec);  }
-    SkNf rsqrt0() const { return _mm256_rsqrt_ps(fVec); }
-    SkNf rsqrt1() const { return this->rsqrt0(); }
-    SkNf rsqrt2() const { return this->rsqrt1(); }
+    SkNx  sqrt() const { return _mm256_sqrt_ps (fVec);  }
+    SkNx rsqrt0() const { return _mm256_rsqrt_ps(fVec); }
+    SkNx rsqrt1() const { return this->rsqrt0(); }
+    SkNx rsqrt2() const { return this->rsqrt1(); }
 
-    SkNf       invert() const { return SkNf(1) / *this; }
-    SkNf approxInvert() const { return _mm256_rcp_ps(fVec); }
+    SkNx       invert() const { return SkNx(1) / *this; }
+    SkNx approxInvert() const { return _mm256_rcp_ps(fVec); }
 
     template <int k> float kth() const {
         SkASSERT(0 <= k && k < 8);
@@ -78,7 +78,7 @@ public:
     bool allTrue() const { return 0xff == _mm256_movemask_ps(fVec); }
     bool anyTrue() const { return 0x00 != _mm256_movemask_ps(fVec); }
 
-    SkNf thenElse(const SkNf& t, const SkNf& e) const {
+    SkNx thenElse(const SkNx& t, const SkNx& e) const {
         return _mm256_blendv_ps(e.fVec, t.fVec, fVec);
     }