skrpb: evaluate color filters for constant shaders once.

src/opts/SkRasterPipeline_opts.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkRasterPipeline_opts_DEFINED
 #define SkRasterPipeline_opts_DEFINED
 
 #include "SkColorPriv.h"
 #include "SkHalf.h"
 #include "SkPM4f.h"
 #include "SkRasterPipeline.h"
 #include "SkSRGB.h"
 #include <utility>
 
 namespace {
 
 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_AVX2
     static constexpr int N = 8;
 #else
     static constexpr int N = 4;
 #endif
 
-using SkNf = SkNx<N, float>;
-using SkNi = SkNx<N, int>;
-using SkNh = SkNx<N, uint16_t>;
+    using SkNf = SkNx<N, float>;
+    using SkNi = SkNx<N, int>;
+    using SkNh = SkNx<N, uint16_t>;
 
     struct BodyStage;
     struct TailStage;
 
     using Body = void(SK_VECTORCALL *)(BodyStage*, size_t,         SkNf,SkNf,SkNf,SkNf,
                                                                    SkNf,SkNf,SkNf,SkNf);
     using Tail = void(SK_VECTORCALL *)(TailStage*, size_t, size_t, SkNf,SkNf,SkNf,SkNf,
                                                                    SkNf,SkNf,SkNf,SkNf);
     struct BodyStage { Body next; void* ctx; };
     struct TailStage { Tail next; void* ctx; };
@@ skipping 333 matching lines @@
             case 6: ptr[5] = buf[5];
             case 5: ptr[4] = buf[4];
             case 4: ptr[3] = buf[3];
             case 3: ptr[2] = buf[2];
             case 2: ptr[1] = buf[1];
         }
         ptr[0] = buf[0];
     }
 }
 
+STAGE(store_f32, false) {
+    auto ptr = *(SkPM4f**)ctx + x;
+
+    SkPM4f buf[8];
+    SkNf::Store4(kIsTail ? buf : ptr, r,g,b,a);
+    if (kIsTail) {
+        switch (tail & (N-1)) {
+            case 7: ptr[6] = buf[6];
+            case 6: ptr[5] = buf[5];
+            case 5: ptr[4] = buf[4];
+            case 4: ptr[3] = buf[3];
+            case 3: ptr[2] = buf[2];
+            case 2: ptr[1] = buf[1];
+        }
+        ptr[0] = buf[0];
+    }
+}
+
 
 // Load 8-bit SkPMColor-order sRGB.
 STAGE(load_d_srgb, true) {
     auto ptr = *(const uint32_t**)ctx + x;
 
     auto px = load<kIsTail>(tail, ptr);
     auto to_int = [](const SkNx<N, uint32_t>& v) { return SkNi::Load(&v); };
     dr =    sk_linear_from_srgb_math(to_int((px >> SK_R32_SHIFT) & 0xff));
     dg =    sk_linear_from_srgb_math(to_int((px >> SK_G32_SHIFT) & 0xff));
     db =    sk_linear_from_srgb_math(to_int((px >> SK_B32_SHIFT) & 0xff));
@@ skipping 149 matching lines @@
     }
 
 }  // namespace SK_OPTS_NS
 
 #undef SI
 #undef STAGE
 #undef RGBA_XFERMODE
 #undef RGB_XFERMODE
 
 #endif//SkRasterPipeline_opts_DEFINED