Flush denorm half floats to zero.

src/core/SkSpanProcs.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 "SkColorFilter.h"
 #include "SkHalf.h"
 #include "SkNx.h"
@@ skipping 24 matching lines @@
         swizzle_rb_if_bgra(Sk4f_fromS32(addr[i])).store(span[i].fVec);
     }
 }
 
 static void load_f16(const SkPixmap& src, int x, int y, SkPM4f span[], int count) {
     SkASSERT(count > 0);
     const uint64_t* addr = src.addr64(x, y);
     SkASSERT(src.addr64(x + count - 1, y));
 
     for (int i = 0; i < count; ++i) {
-        SkHalfToFloat_finite(addr[i]).store(span[i].fVec);
+        SkHalfToFloat_finite_ftz(addr[i]).store(span[i].fVec);
     }
 }
 
 SkLoadSpanProc SkLoadSpanProc_Choose(const SkImageInfo& info) {
     switch (info.colorType()) {
         case kN32_SkColorType:
             return info.gammaCloseToSRGB() ? load_s32 : load_l32;
         case kRGBA_F16_SkColorType:
             return load_f16;
         default:
@@ skipping 30 matching lines @@
     paint.getColorFilter()->filterSpan4f(span, count, span);
 }
 
 SkFilterSpanProc SkFilterSpanProc_Choose(const SkPaint& paint) {
     if (paint.getColorFilter()) {
         return 0xFF == paint.getAlpha() ? colorfilter_filterspan : colorfilter_alpha_filterspan;
     } else {
         return 0xFF == paint.getAlpha() ? noop_filterspan : alpha_filterspan;
     }
 }