Only discard for XP dstCopies if we have a coverage value.

src/effects/SkArithmeticMode_gpu.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkArithmeticMode_gpu.h"
 
 #if SK_SUPPORT_GPU
@@ skipping 157 matching lines @@
     }
 
     ~ArithmeticXP() override {};
 
     const char* name() const override { return "Arithmetic"; }
 
     GrGLXferProcessor* createGLInstance() const override;
 
     bool hasSecondaryOutput() const override { return false; }
 
-    GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
-                                               const GrProcOptInfo& coveragePOI,
-                                               bool doesStencilWrite,
-                                               GrColor* overrideColor,
-                                               const GrDrawTargetCaps& caps) override;
-
     float k1() const { return fK1; }
     float k2() const { return fK2; }
     float k3() const { return fK3; }
     float k4() const { return fK4; }
     bool enforcePMColor() const { return fEnforcePMColor; }
 
 private:
     ArithmeticXP(float k1, float k2, float k3, float k4, bool enforcePMColor,
                    const GrDeviceCoordTexture* dstCopy, bool willReadDstColor);
 
+    GrXferProcessor::OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
+                                                 const GrProcOptInfo& coveragePOI,
+                                                 bool doesStencilWrite,
+                                                 GrColor* overrideColor,
+                                                 const GrDrawTargetCaps& caps) override;
+
     void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
 
     bool onIsEqual(const GrXferProcessor& xpBase) const override {
         const ArithmeticXP& xp = xpBase.cast<ArithmeticXP>();
         if (fK1 != xp.fK1 ||
             fK2 != xp.fK2 ||
             fK3 != xp.fK3 ||
             fK4 != xp.fK4 ||
             fEnforcePMColor != xp.fEnforcePMColor) {
             return false;
@@ skipping 70 matching lines @@
 }
 
 void ArithmeticXP::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
     GLArithmeticXP::GenKey(*this, caps, b);
 }
 
 GrGLXferProcessor* ArithmeticXP::createGLInstance() const {
     return SkNEW_ARGS(GLArithmeticXP, (*this));
 }
 
-GrXferProcessor::OptFlags ArithmeticXP::getOptimizations(const GrProcOptInfo& colorPOI,
-                                                         const GrProcOptInfo& coveragePOI,
-                                                         bool doesStencilWrite,
-                                                         GrColor* overrideColor,
-                                                         const GrDrawTargetCaps& caps) {
+GrXferProcessor::OptFlags ArithmeticXP::onGetOptimizations(const GrProcOptInfo& colorPOI,
+                                                           const GrProcOptInfo& coveragePOI,
+                                                           bool doesStencilWrite,
+                                                           GrColor* overrideColor,
+                                                           const GrDrawTargetCaps& caps) {
    return GrXferProcessor::kNone_Opt;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 GrArithmeticXPFactory::GrArithmeticXPFactory(float k1, float k2, float k3, float k4,
                                              bool enforcePMColor) 
     : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fEnforcePMColor(enforcePMColor) {
     this->initClassID<GrArithmeticXPFactory>();
 }
@@ skipping 28 matching lines @@
     float k1 = random->nextF();
     float k2 = random->nextF();
     float k3 = random->nextF();
     float k4 = random->nextF();
     bool enforcePMColor = random->nextBool();
 
     return GrArithmeticXPFactory::Create(k1, k2, k3, k4, enforcePMColor);
 }
 
 #endif