Start of rewrite of GrFragmentProcessor optimizations.

This adds a replacement for computeInvariantOutput buts does not use it yet. The replacement allows for three types of optimizations:

* known input color -> known output color for GrFP elimination
* tracking of whether all color processors modulate their input for the "tweak alpha" optimziation
* opaqueness tracking

This loses some of the generality of computInvariantOutput. It does not track the known output status of individual color components (other than opaque alpha). It does not track whether GrFragmentProcessors read their input color. It doesn't allow a processor that will receive non-constant output to advertise that it produces a constant output. These could probably be added back in the unlikely case that they prove valuable.

Unlike computeInvariantOutput the optimizations are decided at instantiation time and constant colors are expressed as GrColor4f rather than GrColor.

Change-Id: I684d3f9050693dde2d28154fa695e049ed8cf61a
Reviewed-on: https://skia-review.googlesource.com/7481
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

1 files changed, 70 insertions, 9 deletions

diff --git a/src/gpu/GrFragmentProcessor.cpp b/src/gpu/GrFragmentProcessor.cpp
index 0ad144a3be..f294ac646d 100644
--- a/src/gpu/GrFragmentProcessor.cpp
+++ b/src/gpu/GrFragmentProcessor.cpp
@@ -58,7 +58,7 @@ GrGLSLFragmentProcessor* GrFragmentProcessor::createGLSLInstance() const {
 
 void GrFragmentProcessor::addCoordTransform(const GrCoordTransform* transform) {
     fCoordTransforms.push_back(transform);
-    fUsesLocalCoords = true;
+    fFlags |= kUsesLocalCoords_Flag;
     SkDEBUGCODE(transform->setInProcessor();)
 }
 
@@ -66,10 +66,10 @@ int GrFragmentProcessor::registerChildProcessor(sk_sp<GrFragmentProcessor> child
     this->combineRequiredFeatures(*child);
 
     if (child->usesLocalCoords()) {
-        fUsesLocalCoords = true;
+        fFlags |= kUsesLocalCoords_Flag;
     }
     if (child->usesDistanceVectorField()) {
-        fUsesDistanceVectorField = true;
+        fFlags |= kUsesDistanceVectorField_Flag;
     }
 
     int index = fChildProcessors.count();
@@ -111,12 +111,13 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::PremulInput(sk_sp<GrFragmentProc
 
     class PremulInputFragmentProcessor : public GrFragmentProcessor {
     public:
-        PremulInputFragmentProcessor() {
+        PremulInputFragmentProcessor()
+                : INHERITED(kPreservesOpaqueInput_OptimizationFlag |
+                            kConstantOutputForConstantInput_OptimizationFlag) {
             this->initClassID<PremulInputFragmentProcessor>();
         }
 
         const char* name() const override { return "PremultiplyInput"; }
-
     private:
         GrGLSLFragmentProcessor* onCreateGLSLInstance() const override {
             class GLFP : public GrGLSLFragmentProcessor {
@@ -139,6 +140,11 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::PremulInput(sk_sp<GrFragmentProc
         void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
             inout->premulFourChannelColor();
         }
+        GrColor4f constantOutputForConstantInput(GrColor4f input) const override {
+            return input.premul();
+        }
+
+        typedef GrFragmentProcessor INHERITED;
     };
     if (!fp) {
         return nullptr;
@@ -152,7 +158,8 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::MulOutputByInputUnpremulColor(
 
     class PremulFragmentProcessor : public GrFragmentProcessor {
     public:
-        PremulFragmentProcessor(sk_sp<GrFragmentProcessor> processor) {
+        PremulFragmentProcessor(sk_sp<GrFragmentProcessor> processor)
+                : INHERITED(OptFlags(processor.get())) {
             this->initClassID<PremulFragmentProcessor>();
             this->registerChildProcessor(processor);
         }
@@ -178,6 +185,16 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::MulOutputByInputUnpremulColor(
 
         bool onIsEqual(const GrFragmentProcessor&) const override { return true; }
 
+        static OptimizationFlags OptFlags(const GrFragmentProcessor* inner) {
+            OptimizationFlags flags = kNone_OptimizationFlags;
+            if (inner->preservesOpaqueInput()) {
+                flags |= kPreservesOpaqueInput_OptimizationFlag;
+            }
+            if (inner->hasConstantOutputForConstantInput()) {
+                flags |= kConstantOutputForConstantInput_OptimizationFlag;
+            }
+            return flags;
+        }
         void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
             // TODO: Add a helper to GrInvariantOutput that handles multiplying by color with flags?
             if (!(inout->validFlags() & kA_GrColorComponentFlag)) {
@@ -210,6 +227,16 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::MulOutputByInputUnpremulColor(
             }
             inout->setToOther(commonFlags, color);
         }
+        GrColor4f constantOutputForConstantInput(GrColor4f input) const override {
+            GrColor4f childColor = ConstantOutputForConstantInput(this->childProcessor(0),
+                                                                  GrColor4f::OpaqueWhite());
+            return GrColor4f(input.fRGBA[3] * input.fRGBA[0] * childColor.fRGBA[0],
+                             input.fRGBA[3] * input.fRGBA[1] * childColor.fRGBA[1],
+                             input.fRGBA[3] * input.fRGBA[2] * childColor.fRGBA[2],
+                             input.fRGBA[3] * childColor.fRGBA[3]);
+        }
+
+        typedef GrFragmentProcessor INHERITED;
     };
     if (!fp) {
         return nullptr;
@@ -224,7 +251,7 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(sk_sp<GrFragmentPr
     class ReplaceInputFragmentProcessor : public GrFragmentProcessor {
     public:
         ReplaceInputFragmentProcessor(sk_sp<GrFragmentProcessor> child, GrColor4f color)
-            : fColor(color) {
+                : INHERITED(OptFlags(child.get(), color)), fColor(color) {
             this->initClassID<ReplaceInputFragmentProcessor>();
             this->registerChildProcessor(std::move(child));
         }
@@ -264,6 +291,18 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(sk_sp<GrFragmentPr
         }
 
     private:
+        static OptimizationFlags OptFlags(const GrFragmentProcessor* child, GrColor4f color) {
+            OptimizationFlags childFlags = child->optimizationFlags();
+            OptimizationFlags flags = kNone_OptimizationFlags;
+            if (childFlags & kConstantOutputForConstantInput_OptimizationFlag) {
+                flags |= kConstantOutputForConstantInput_OptimizationFlag;
+            }
+            if ((childFlags & kPreservesOpaqueInput_OptimizationFlag) && color.isOpaque()) {
+                flags |= kPreservesOpaqueInput_OptimizationFlag;
+            }
+            return flags;
+        }
+
         void onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override
         {}
 
@@ -276,7 +315,13 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::OverrideInput(sk_sp<GrFragmentPr
             this->childProcessor(0).computeInvariantOutput(inout);
         }
 
+        GrColor4f constantOutputForConstantInput(GrColor4f) const override {
+            return ConstantOutputForConstantInput(this->childProcessor(0), fColor);
+        }
+
         GrColor4f fColor;
+
+        typedef GrFragmentProcessor INHERITED;
     };
 
     GrInvariantOutput childOut(0x0, kNone_GrColorComponentFlags);
@@ -288,7 +333,8 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::RunInSeries(sk_sp<GrFragmentProc
                                                             int cnt) {
     class SeriesFragmentProcessor : public GrFragmentProcessor {
     public:
-        SeriesFragmentProcessor(sk_sp<GrFragmentProcessor>* children, int cnt){
+        SeriesFragmentProcessor(sk_sp<GrFragmentProcessor>* children, int cnt)
+                : INHERITED(OptFlags(children, cnt)) {
             SkASSERT(cnt > 1);
             this->initClassID<SeriesFragmentProcessor>();
             for (int i = 0; i < cnt; ++i) {
@@ -317,8 +363,14 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::RunInSeries(sk_sp<GrFragmentProc
             };
             return new GLFP;
         }
-
     private:
+        static OptimizationFlags OptFlags(sk_sp<GrFragmentProcessor>* children, int cnt) {
+            OptimizationFlags flags = kAll_OptimizationFlags;
+            for (int i = 0; i < cnt && flags != kNone_OptimizationFlags; ++i) {
+                flags &= children[i]->optimizationFlags();
+            }
+            return flags;
+        }
         void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override {}
 
         bool onIsEqual(const GrFragmentProcessor&) const override { return true; }
@@ -328,6 +380,15 @@ sk_sp<GrFragmentProcessor> GrFragmentProcessor::RunInSeries(sk_sp<GrFragmentProc
                 this->childProcessor(i).computeInvariantOutput(inout);
             }
         }
+        GrColor4f constantOutputForConstantInput(GrColor4f color) const override {
+            int childCnt = this->numChildProcessors();
+            for (int i = 0; i < childCnt; ++i) {
+                color = ConstantOutputForConstantInput(this->childProcessor(i), color);
+            }
+            return color;
+        }
+
+        typedef GrFragmentProcessor INHERITED;
     };
 
     if (!cnt) {