Refactor Sk2x<T> + Sk4x<T> into SkNf<N,T> and SkNi<N,T>

src/opts/SkPMFloat_SSE2.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.
  */
 
-inline SkPMFloat& SkPMFloat::operator=(const SkPMFloat& that) {
-    fColors = that.fColors;
-    return *this;
-}
-
 // For SkPMFloat(SkPMColor), we widen our 8 bit components (fix8) to 8-bit components in 16 bits
 // (fix8_16), then widen those to 8-bit-in-32-bits (fix8_32), and finally convert those to floats.
 
 // get() and clamped() do the opposite, working from floats to 8-bit-in-32-bit,
 // to 8-bit-in-16-bit, back down to 8-bit components.
 // _mm_packus_epi16() gives us clamping for free while narrowing.
 
 inline SkPMFloat::SkPMFloat(SkPMColor c) {
     SkPMColorAssert(c);
     __m128i fix8    = _mm_set_epi32(0,0,0,c),
             fix8_16 = _mm_unpacklo_epi8 (fix8,    _mm_setzero_si128()),
             fix8_32 = _mm_unpacklo_epi16(fix8_16, _mm_setzero_si128());
     fColors = _mm_cvtepi32_ps(fix8_32);
     SkASSERT(this->isValid());
 }
 
 inline SkPMColor SkPMFloat::get() const {
     SkASSERT(this->isValid());
     return this->clamped();  // Haven't beaten this yet.
 }
 
 inline SkPMColor SkPMFloat::clamped() const {
     // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
-    __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fColors)),
+    __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fColors.vec())),
             fix8_16 = _mm_packus_epi16(fix8_32, fix8_32),
             fix8    = _mm_packus_epi16(fix8_16, fix8_16);
     SkPMColor c = _mm_cvtsi128_si32(fix8);
     SkPMColorAssert(c);
     return c;
 }
 
 inline SkPMColor SkPMFloat::trunc() const {
     // Basically, same as clamped(), but no rounding.
-    __m128i fix8_32 = _mm_cvttps_epi32(fColors),
+    __m128i fix8_32 = _mm_cvttps_epi32(fColors.vec()),
             fix8_16 = _mm_packus_epi16(fix8_32, fix8_32),
             fix8    = _mm_packus_epi16(fix8_16, fix8_16);
     SkPMColor c = _mm_cvtsi128_si32(fix8);
     SkPMColorAssert(c);
     return c;
 }
 
 inline void SkPMFloat::From4PMColors(const SkPMColor colors[4],
                                      SkPMFloat* a, SkPMFloat* b, SkPMFloat* c, SkPMFloat* d) {
     // Haven't beaten this yet.
     *a = FromPMColor(colors[0]);
     *b = FromPMColor(colors[1]);
     *c = FromPMColor(colors[2]);
     *d = FromPMColor(colors[3]);
 }
 
 inline void SkPMFloat::To4PMColors(
         const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
         SkPMColor colors[4]) {
     // Haven't beaten this yet.
     ClampTo4PMColors(a,b,c,d, colors);
 }
 
 inline void SkPMFloat::ClampTo4PMColors(
         const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
         SkPMColor colors[4]) {
     // Same as _SSSE3.h's.  We use 3 _mm_packus_epi16() where the naive loop uses 8.
     // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
-    __m128i c0 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), a.fColors)),
-            c1 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), b.fColors)),
-            c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fColors)),
-            c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fColors));
+    __m128i c0 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), a.fColors.vec())),
+            c1 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), b.fColors.vec())),
+            c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fColors.vec())),
+            c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fColors.vec()));
     __m128i c3210 = _mm_packus_epi16(_mm_packus_epi16(c0, c1),
                                      _mm_packus_epi16(c2, c3));
     _mm_storeu_si128((__m128i*)colors, c3210);
     SkPMColorAssert(colors[0]);
     SkPMColorAssert(colors[1]);
     SkPMColorAssert(colors[2]);
     SkPMColorAssert(colors[3]);
 }