Faster 4f gradient premul path

src/effects/gradients/Sk4fGradientBase.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Sk4fGradientBase.h"
 
 #include <functional>
@@ skipping 308 matching lines @@
     }
 }
 
 template<DstType dstType, ApplyPremul premul, SkShader::TileMode tileMode>
 void SkGradientShaderBase::
 GradientShaderBase4fContext::shadeSpanInternal(int x, int y,
                                                typename DstTraits<dstType, premul>::Type dst[],
                                                int count) const {
     static const int kBufSize = 128;
     SkScalar ts[kBufSize];
-    TSampler<dstType, tileMode> sampler(*this);
+    TSampler<dstType, premul, tileMode> sampler(*this);
 
     SkASSERT(count > 0);
     do {
         const int n = SkTMin(kBufSize, count);
         this->mapTs(x, y, ts, n);
         for (int i = 0; i < n; ++i) {
             const Sk4f c = sampler.sample(ts[i]);
             DstTraits<dstType, premul>::store(c, dst++);
         }
         x += n;
         count -= n;
     } while (count > 0);
 }
 
-template<DstType dstType, SkShader::TileMode tileMode>
+template<DstType dstType, ApplyPremul premul, SkShader::TileMode tileMode>
 class SkGradientShaderBase::GradientShaderBase4fContext::TSampler {
 public:
     TSampler(const GradientShaderBase4fContext& ctx)
         : fFirstInterval(ctx.fIntervals.begin())
         , fLastInterval(ctx.fIntervals.end() - 1)
         , fInterval(nullptr) {
         SkASSERT(fLastInterval >= fFirstInterval);
     }
 
     Sk4f sample(SkScalar t) {
@@ skipping 62 matching lines @@
                 if (i < fFirstInterval) {
                     i = fLastInterval;
                 }
             } while (tiled_t < i->fP0 || tiled_t >= i->fP1);
         }
 
         return i;
     }
 
     void loadIntervalData(const Interval* i) {
-        fCc = DstTraits<dstType>::load(i->fC0);
-        fDc = DstTraits<dstType>::load(i->fDc);
+        fCc = DstTraits<dstType, premul>::load(i->fC0);
+        fDc = DstTraits<dstType, premul>::load(i->fDc);
     }
 
     const Interval* fFirstInterval;
     const Interval* fLastInterval;
     const Interval* fInterval;
     SkScalar        fPrevT;
     Sk4f            fCc;
     Sk4f            fDc;
 };