Stop discarding in frag shader when coverage is zero and stencil writes are enabled

src/gpu/gl/GrGLProgramDesc.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLProgramDesc.h"
 #include "GrBackendEffectFactory.h"
 #include "GrDrawEffect.h"
@@ skipping 197 matching lines @@
         header->fCoverageAttributeIndex = drawState.coverageVertexAttributeIndex();
     } else if (GrGLProgramDesc::kAttribute_ColorInput == header->fCoverageInput) {
         SkASSERT(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
         header->fCoverageAttributeIndex = availableAttributeIndex;
     } else {
         header->fCoverageAttributeIndex = -1;
     }
 
     // Here we deal with whether/how we handle color and coverage separately.
 
-    // Set these defaults and then possibly change our mind if there is coverage.
-    header->fDiscardIfZeroCoverage = false;
+    // Set this default and then possibly change our mind if there is coverage.
     header->fCoverageOutput = kModulate_CoverageOutput;
 
     // If we do have coverage determine whether it matters.
     bool separateCoverageFromColor = false;
     if (!drawState.isCoverageDrawing() && !skipCoverage &&
         (drawState.numCoverageStages() > 0 || requiresCoverageAttrib)) {
 
-        // If we're stenciling then we want to discard samples that have zero coverage
-        if (drawState.getStencil().doesWrite()) {
-            header->fDiscardIfZeroCoverage = true;
-            separateCoverageFromColor = true;
-        }
-
         if (gpu->caps()->dualSourceBlendingSupport() &&
             !(blendOpts & (GrDrawState::kEmitCoverage_BlendOptFlag |
                            GrDrawState::kCoverageAsAlpha_BlendOptFlag))) {
             if (kZero_GrBlendCoeff == dstCoeff) {
                 // write the coverage value to second color
                 header->fCoverageOutput =  kSecondaryCoverage_CoverageOutput;
                 separateCoverageFromColor = true;
             } else if (kSA_GrBlendCoeff == dstCoeff) {
                 // SA dst coeff becomes 1-(1-SA)*coverage when dst is partially covered.
                 header->fCoverageOutput = kSecondaryCoverageISA_CoverageOutput;
@@ skipping 37 matching lines @@
 
 GrGLProgramDesc& GrGLProgramDesc::operator= (const GrGLProgramDesc& other) {
     fInitialized = other.fInitialized;
     if (fInitialized) {
         size_t keyLength = other.keyLength();
         fKey.reset(keyLength);
         memcpy(fKey.get(), other.fKey.get(), keyLength);
     }
     return *this;
 }