Optimize color xforms with 2.2 gammas for SSE2

src/core/SkColorSpaceXform.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 SkColorSpaceXform_DEFINED
 #define SkColorSpaceXform_DEFINED
 
@@ skipping 16 matching lines @@
     /**
      *  Apply the color conversion to a src buffer, storing the output in the dst buffer.
      *  The src is stored in RGBA_8888 and the dst is stored in 8888 platform format.
      *  The output is not premultiplied.
      */
     virtual void xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const = 0;
 
     virtual ~SkColorSpaceXform() {}
 };
 
-class SkGammaByValueXform : public SkColorSpaceXform {
+class Sk2Dot2Xform : public SkColorSpaceXform {
 public:
 
     void xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const override;
 
 private:
-    SkGammaByValueXform(float srcGammas[3], const SkMatrix44& srcToDst, float dstGammas[3]);
+    Sk2Dot2Xform(const SkMatrix44& srcToDst);
 
-    float            fSrcGammas[3];
-    const SkMatrix44 fSrcToDst;
-    float            fDstGammas[3];
+    float fSrcToDst[16];
 
     friend class SkColorSpaceXform;
 };
 
 /**
  *  Works for any valid src and dst profiles.
  */
 class SkDefaultXform : public SkColorSpaceXform {
 public:
 
     void xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const override;
 
 private:
     SkDefaultXform(const sk_sp<SkGammas>& srcGammas, const SkMatrix44& srcToDst,
                    const sk_sp<SkGammas>& dstGammas);
 
     sk_sp<SkGammas>  fSrcGammas;
     const SkMatrix44 fSrcToDst;
     sk_sp<SkGammas>  fDstGammas;
 
     friend class SkColorSpaceXform;
     friend class ColorSpaceXformTest;
 };
 
 #endif