added support for PLS path rendering

src/gpu/effects/GrCoverageSetOpXP.cpp

Index: src/gpu/effects/GrCoverageSetOpXP.cpp
diff --git a/src/gpu/effects/GrCoverageSetOpXP.cpp b/src/gpu/effects/GrCoverageSetOpXP.cpp
index 7761a6445ac14f91c2fda6984a387cc916ec2a27..abf4be0aa09de43d7879a9f4cc944fad475b954f 100644
--- a/src/gpu/effects/GrCoverageSetOpXP.cpp
+++ b/src/gpu/effects/GrCoverageSetOpXP.cpp
@@ -9,6 +9,7 @@
 #include "effects/GrCoverageSetOpXP.h"
 #include "GrCaps.h"
 #include "GrColor.h"
+#include "GrPipeline.h"
 #include "GrProcessor.h"
 #include "GrProcOptInfo.h"
 #include "glsl/GrGLSLBlend.h"
@@ -151,7 +152,6 @@ class ShaderCSOXferProcessor : public GrXferProcessor {
 public:
     ShaderCSOXferProcessor(const DstTexture* dstTexture,
                            bool hasMixedSamples,
-                           SkXfermode::Mode xfermode,
                            SkRegion::Op regionOp,
                            bool invertCoverage)
         : INHERITED(dstTexture, true, hasMixedSamples)
@@ -310,11 +310,17 @@ GrXPFactory* GrCoverageSetOpXPFactory::Create(SkRegion::Op regionOp, bool invert
     }
 }
 
+bool GrCoverageSetOpXPFactory::willReadDstColor(const GrCaps& caps,
+                                                const GrPipelineOptimizations& optimizations,
+                                                bool hasMixedSamples) const {
+    return optimizations.fOverrides.fUsePLSDstRead;

[egdaniel, 2016/01/13 21:47:19]

I am slightly worried about the need to check PLS in each XPFs willReadDst since
it is not an obvious thing to need to check for if we ever make a new XP.
However it can't really go in the base class since each XP does handle it
slightly different.

Maybe at least on the base class virtual lets add or update the comment to make
it clear the subclass needs to respect the optimizations, specifically pls.

+}
+
 GrXferProcessor*
 GrCoverageSetOpXPFactory::onCreateXferProcessor(const GrCaps& caps,
                                                 const GrPipelineOptimizations& optimizations,
                                                 bool hasMixedSamples,
-                                                const DstTexture* dst) const {
+                                                const DstTexture* dst) const {    

[egdaniel, 2016/01/13 21:47:19]

extra spaces

     // We don't support inverting coverage with mixed samples. We don't expect to ever want this in
     // the future, however we could at some point make this work using an inverted coverage
     // modulation table. Note that an inverted table still won't work if there are coverage procs.
@@ -323,6 +329,9 @@ GrCoverageSetOpXPFactory::onCreateXferProcessor(const GrCaps& caps,
         return nullptr;
     }
 
+    if (optimizations.fOverrides.fUsePLSDstRead) {
+        return new ShaderCSOXferProcessor(dst, hasMixedSamples, fRegionOp, fInvertCoverage);
+    }
     return CoverageSetOpXP::Create(fRegionOp, fInvertCoverage);
 }