Bilinear optimization for 1D convolution.

Splits GrGLConvolutionEffect into GrGLBilerpConvolutionEffect and
GrGLBoundedConvolutionEffect. When doing a non-bounded convolution we now
always use the GrGLBilerpConvolutionEffect which uses bilinear filtering to
perform half as many samples in the texture.

BUG=skia:3986

Committed: https://skia.googlesource.com/skia/+/91abe10af417148939548551e210c001022d3bda

Review URL: https://codereview.chromium.org/1216623003

2 files changed, 276 insertions, 85 deletions

diff --git a/src/gpu/effects/Gr1DKernelEffect.h b/src/gpu/effects/Gr1DKernelEffect.h
index 0aec4b1336..4fc52b1385 100644
--- a/src/gpu/effects/Gr1DKernelEffect.h
+++ b/src/gpu/effects/Gr1DKernelEffect.h
@@ -28,6 +28,8 @@ public:
         kY_Direction,
     };
 
+    // Constructor using default nearest-neighbor sampling for the input texture
+    // filter mode.
     Gr1DKernelEffect(GrProcessorDataManager* procDataManager,
                      GrTexture* texture,
                      Direction direction,
@@ -36,6 +38,18 @@ public:
         , fDirection(direction)
         , fRadius(radius) {}
 
+    Gr1DKernelEffect(GrProcessorDataManager* procDataManager,
+                     GrTexture* texture,
+                     Direction direction,
+                     int radius,
+                     GrTextureParams::FilterMode filterMode)
+        : INHERITED(procDataManager,
+                    texture,
+                    GrCoordTransform::MakeDivByTextureWHMatrix(texture),
+                    filterMode)
+        , fDirection(direction)
+        , fRadius(radius) {}
+
     virtual ~Gr1DKernelEffect() {};
 
     static int WidthFromRadius(int radius) { return 2 * radius + 1; }
diff --git a/src/gpu/effects/GrConvolutionEffect.cpp b/src/gpu/effects/GrConvolutionEffect.cpp
index f5b5e22ce1..1e1c477cd5 100644
--- a/src/gpu/effects/GrConvolutionEffect.cpp
+++ b/src/gpu/effects/GrConvolutionEffect.cpp
@@ -13,9 +13,73 @@
 // For brevity
 typedef GrGLProgramDataManager::UniformHandle UniformHandle;
 
+/**
+ * Base class with shared functionality for GrGLBoundedConvolutionEffect and
+ * GrGLLerpConvolutionEffect.
+ */
 class GrGLConvolutionEffect : public GrGLFragmentProcessor {
 public:
     GrGLConvolutionEffect(const GrProcessor&);
+    static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);
+
+protected:
+    int radius() const { return fRadius; }
+    int width() const { return Gr1DKernelEffect::WidthFromRadius(fRadius); }
+    Gr1DKernelEffect::Direction direction() const { return fDirection; }
+    void getImageIncrement(const GrConvolutionEffect&, float (*)[2]) const;
+
+private:
+    int fRadius;
+    Gr1DKernelEffect::Direction fDirection;
+
+    typedef GrGLFragmentProcessor INHERITED;
+};
+
+GrGLConvolutionEffect::GrGLConvolutionEffect(const GrProcessor& processor) {
+    const GrConvolutionEffect& c = processor.cast<GrConvolutionEffect>();
+    fRadius = c.radius();
+    fDirection = c.direction();
+}
+
+void GrGLConvolutionEffect::GenKey(const GrProcessor& processor,
+                                   const GrGLSLCaps&,
+                                   GrProcessorKeyBuilder* b) {
+    const GrConvolutionEffect& conv = processor.cast<GrConvolutionEffect>();
+    uint32_t key = conv.radius();
+    key <<= 2;
+    if (conv.useBounds()) {
+        key |= 0x2;
+        key |= GrConvolutionEffect::kY_Direction == conv.direction() ? 0x1 : 0x0;
+    }
+    b->add32(key);
+}
+
+void GrGLConvolutionEffect::getImageIncrement(const GrConvolutionEffect& conv,
+                                              float (*imageIncrement)[2]) const {
+    GrTexture& texture = *conv.texture(0);
+    (*imageIncrement)[0] = (*imageIncrement)[1] = 0;
+    float ySign = texture.origin() != kTopLeft_GrSurfaceOrigin ? 1.0f : -1.0f;
+    switch (conv.direction()) {
+        case Gr1DKernelEffect::kX_Direction:
+            (*imageIncrement)[0] = 1.0f / texture.width();
+            break;
+        case Gr1DKernelEffect::kY_Direction:
+            (*imageIncrement)[1] = ySign / texture.height();
+            break;
+        default:
+            SkFAIL("Unknown filter direction.");
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Applies a convolution effect which restricts samples to the provided bounds
+ * using shader logic.
+ */
+class GrGLBoundedConvolutionEffect : public GrGLConvolutionEffect {
+public:
+    GrGLBoundedConvolutionEffect(const GrProcessor& processor) : INHERITED(processor) {}
 
     virtual void emitCode(GrGLFPBuilder*,
                           const GrFragmentProcessor&,
@@ -26,58 +90,41 @@ public:
 
     void setData(const GrGLProgramDataManager& pdman, const GrProcessor&) override;
 
-    static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);
-
 private:
-    int width() const { return Gr1DKernelEffect::WidthFromRadius(fRadius); }
-    bool useBounds() const { return fUseBounds; }
-    Gr1DKernelEffect::Direction direction() const { return fDirection; }
-
-    int                 fRadius;
-    bool                fUseBounds;
-    Gr1DKernelEffect::Direction    fDirection;
     UniformHandle       fKernelUni;
     UniformHandle       fImageIncrementUni;
     UniformHandle       fBoundsUni;
 
-    typedef GrGLFragmentProcessor INHERITED;
+    typedef GrGLConvolutionEffect INHERITED;
 };
 
-GrGLConvolutionEffect::GrGLConvolutionEffect(const GrProcessor& processor) {
-    const GrConvolutionEffect& c = processor.cast<GrConvolutionEffect>();
-    fRadius = c.radius();
-    fUseBounds = c.useBounds();
-    fDirection = c.direction();
-}
+void GrGLBoundedConvolutionEffect::emitCode(GrGLFPBuilder* builder,
+                                            const GrFragmentProcessor& processor,
+                                            const char* outputColor,
+                                            const char* inputColor,
+                                            const TransformedCoordsArray& coords,
+                                            const TextureSamplerArray& samplers) {
+    fImageIncrementUni =
+        builder->addUniform(GrGLProgramBuilder::kFragment_Visibility, kVec2f_GrSLType,
+                            kDefault_GrSLPrecision, "ImageIncrement");
 
-void GrGLConvolutionEffect::emitCode(GrGLFPBuilder* builder,
-                                     const GrFragmentProcessor&,
-                                     const char* outputColor,
-                                     const char* inputColor,
-                                     const TransformedCoordsArray& coords,
-                                     const TextureSamplerArray& samplers) {
-    fImageIncrementUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
-                                             kVec2f_GrSLType, kDefault_GrSLPrecision,
-                                             "ImageIncrement");
-    if (this->useBounds()) {
-        fBoundsUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
-                                         kVec2f_GrSLType, kDefault_GrSLPrecision,
-                                         "Bounds");
-    }
-    fKernelUni = builder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility,
-                                          kFloat_GrSLType, kDefault_GrSLPrecision,
-                                          "Kernel", this->width());
+    fBoundsUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility, kVec2f_GrSLType,
+                                     kDefault_GrSLPrecision, "Bounds");
+
+    fKernelUni = builder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility, kFloat_GrSLType,
+                                          kDefault_GrSLPrecision, "Kernel", this->width());
 
     GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
     SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 0);
 
-    fsBuilder->codeAppendf("\t\t%s = vec4(0, 0, 0, 0);\n", outputColor);
+    fsBuilder->codeAppendf("%s = vec4(0, 0, 0, 0);\n", outputColor);
 
     int width = this->width();
     const GrGLShaderVar& kernel = builder->getUniformVariable(fKernelUni);
     const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
 
-    fsBuilder->codeAppendf("\t\tvec2 coord = %s - %d.0 * %s;\n", coords2D.c_str(), fRadius, imgInc);
+    fsBuilder->codeAppendf("vec2 coord = %s - %d.0 * %s;\n", coords2D.c_str(), this->radius(),
+                           imgInc);
 
     // Manually unroll loop because some drivers don't; yields 20-30% speedup.
     for (int i = 0; i < width; i++) {
@@ -85,23 +132,18 @@ void GrGLConvolutionEffect::emitCode(GrGLFPBuilder* builder,
         SkString kernelIndex;
         index.appendS32(i);
         kernel.appendArrayAccess(index.c_str(), &kernelIndex);
-
-        if (this->useBounds()) {
-            // We used to compute a bool indicating whether we're in bounds or not, cast it to a
-            // float, and then mul weight*texture_sample by the float. However, the Adreno 430 seems
-            // to have a bug that caused corruption.
-            const char* bounds = builder->getUniformCStr(fBoundsUni);
-            const char* component = this->direction() == Gr1DKernelEffect::kY_Direction ? "y" : "x";
-            fsBuilder->codeAppendf("if (coord.%s >= %s.x && coord.%s <= %s.y) {",
-                component, bounds, component, bounds);
-        }
-        fsBuilder->codeAppendf("\t\t%s += ", outputColor);
+        // We used to compute a bool indicating whether we're in bounds or not, cast it to a
+        // float, and then mul weight*texture_sample by the float. However, the Adreno 430 seems
+        // to have a bug that caused corruption.
+        const char* bounds = builder->getUniformCStr(fBoundsUni);
+        const char* component = this->direction() == Gr1DKernelEffect::kY_Direction ? "y" : "x";
+        fsBuilder->codeAppendf("if (coord.%s >= %s.x && coord.%s <= %s.y) {",
+            component, bounds, component, bounds);
+        fsBuilder->codeAppendf("%s += ", outputColor);
         fsBuilder->appendTextureLookup(samplers[0], "coord");
         fsBuilder->codeAppendf(" * %s;\n", kernelIndex.c_str());
-        if (this->useBounds()) {
-            fsBuilder->codeAppend("}");
-        }
-        fsBuilder->codeAppendf("\t\tcoord += %s;\n", imgInc);
+        fsBuilder->codeAppend("}");
+        fsBuilder->codeAppendf("coord += %s;\n", imgInc);
     }
 
     SkString modulate;
@@ -109,47 +151,162 @@ void GrGLConvolutionEffect::emitCode(GrGLFPBuilder* builder,
     fsBuilder->codeAppend(modulate.c_str());
 }
 
-void GrGLConvolutionEffect::setData(const GrGLProgramDataManager& pdman,
-                                    const GrProcessor& processor) {
+void GrGLBoundedConvolutionEffect::setData(const GrGLProgramDataManager& pdman,
+                                           const GrProcessor& processor) {
     const GrConvolutionEffect& conv = processor.cast<GrConvolutionEffect>();
-    GrTexture& texture = *conv.texture(0);
+
     // the code we generated was for a specific kernel radius
-    SkASSERT(conv.radius() == fRadius);
-    float imageIncrement[2] = { 0 };
-    float ySign = texture.origin() != kTopLeft_GrSurfaceOrigin ? 1.0f : -1.0f;
-    switch (conv.direction()) {
-        case Gr1DKernelEffect::kX_Direction:
-            imageIncrement[0] = 1.0f / texture.width();
-            break;
-        case Gr1DKernelEffect::kY_Direction:
-            imageIncrement[1] = ySign / texture.height();
-            break;
-        default:
-            SkFAIL("Unknown filter direction.");
-    }
+    SkASSERT(conv.radius() == this->radius());
+
+    // the code we generated was for a specific bounding mode.
+    SkASSERT(conv.useBounds());
+
+    GrTexture& texture = *conv.texture(0);
+    float imageIncrement[2];
+    getImageIncrement(conv, &imageIncrement);
     pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
-    if (conv.useBounds()) {
-        const float* bounds = conv.bounds();
-        if (Gr1DKernelEffect::kY_Direction == conv.direction() &&
-            texture.origin() != kTopLeft_GrSurfaceOrigin) {
-            pdman.set2f(fBoundsUni, 1.0f - bounds[1], 1.0f - bounds[0]);
-        } else {
-            pdman.set2f(fBoundsUni, bounds[0], bounds[1]);
-        }
+    const float* bounds = conv.bounds();
+    if (Gr1DKernelEffect::kY_Direction == conv.direction() &&
+        texture.origin() != kTopLeft_GrSurfaceOrigin) {
+        pdman.set2f(fBoundsUni, 1.0f - bounds[1], 1.0f - bounds[0]);
+    } else {
+        pdman.set2f(fBoundsUni, bounds[0], bounds[1]);
     }
     pdman.set1fv(fKernelUni, this->width(), conv.kernel());
 }
 
-void GrGLConvolutionEffect::GenKey(const GrProcessor& processor, const GrGLSLCaps&,
-                                   GrProcessorKeyBuilder* b) {
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * Applies a convolution effect which applies the convolution using a linear
+ * interpolation optimization to use half as many samples.
+ */
+class GrGLLerpConvolutionEffect : public GrGLConvolutionEffect {
+public:
+    GrGLLerpConvolutionEffect(const GrProcessor& processor) : INHERITED(processor) {}
+
+    virtual void emitCode(GrGLFPBuilder*,
+                          const GrFragmentProcessor&,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TransformedCoordsArray&,
+                          const TextureSamplerArray&) override;
+
+    void setData(const GrGLProgramDataManager& pdman, const GrProcessor&) override;
+
+private:
+    int bilerpSampleCount() const;
+
+    // Bounded uniforms
+    UniformHandle fSampleWeightUni;
+    UniformHandle fSampleOffsetUni;
+
+    typedef GrGLConvolutionEffect INHERITED;
+};
+
+void GrGLLerpConvolutionEffect::emitCode(GrGLFPBuilder* builder,
+                                         const GrFragmentProcessor& processor,
+                                         const char* outputColor,
+                                         const char* inputColor,
+                                         const TransformedCoordsArray& coords,
+                                         const TextureSamplerArray& samplers) {
+    int sampleCount = bilerpSampleCount();
+
+    // We use 2 * sampleCount uniforms. The maximum allowed by PS2.0 is 32, so
+    // ensure we don't exceed this. Note that it is currently impossible to
+    // exceed this as bilerpSampleCount = (kernelWidth + 1) / 2, and kernelWidth
+    // maxes out at 25, resulting in a max sampleCount of 26.
+    SkASSERT(sampleCount < 16);
+
+    fSampleOffsetUni =
+        builder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility, kVec2f_GrSLType,
+                                 kDefault_GrSLPrecision, "SampleOffset", sampleCount);
+    fSampleWeightUni =
+        builder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility, kFloat_GrSLType,
+                                 kDefault_GrSLPrecision, "SampleWeight", sampleCount);
+
+    GrGLFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
+    SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 0);
+
+    fsBuilder->codeAppendf("%s = vec4(0, 0, 0, 0);\n", outputColor);
+
+    const GrGLShaderVar& kernel = builder->getUniformVariable(fSampleWeightUni);
+    const GrGLShaderVar& imgInc = builder->getUniformVariable(fSampleOffsetUni);
+
+    fsBuilder->codeAppendf("vec2 coord; \n");
+
+    // Manually unroll loop because some drivers don't; yields 20-30% speedup.
+    for (int i = 0; i < sampleCount; i++) {
+        SkString index;
+        SkString weightIndex;
+        SkString offsetIndex;
+        index.appendS32(i);
+        kernel.appendArrayAccess(index.c_str(), &weightIndex);
+        imgInc.appendArrayAccess(index.c_str(), &offsetIndex);
+        fsBuilder->codeAppendf("coord = %s + %s;\n", coords2D.c_str(), offsetIndex.c_str());
+        fsBuilder->codeAppendf("%s += ", outputColor);
+        fsBuilder->appendTextureLookup(samplers[0], "coord");
+        fsBuilder->codeAppendf(" * %s;\n", weightIndex.c_str());
+    }
+
+    SkString modulate;
+    GrGLSLMulVarBy4f(&modulate, outputColor, inputColor);
+    fsBuilder->codeAppend(modulate.c_str());
+}
+
+void GrGLLerpConvolutionEffect::setData(const GrGLProgramDataManager& pdman,
+                                        const GrProcessor& processor) {
     const GrConvolutionEffect& conv = processor.cast<GrConvolutionEffect>();
-    uint32_t key = conv.radius();
-    key <<= 2;
-    if (conv.useBounds()) {
-        key |= 0x2;
-        key |= GrConvolutionEffect::kY_Direction == conv.direction() ? 0x1 : 0x0;
+
+    // the code we generated was for a specific kernel radius
+    SkASSERT(conv.radius() == this->radius());
+
+    // the code we generated was for a specific bounding mode.
+    SkASSERT(!conv.useBounds());
+
+    int sampleCount = bilerpSampleCount();
+    SkAutoTArray<float> imageIncrements(sampleCount * 2);  // X and Y floats per sample.
+    SkAutoTArray<float> kernel(sampleCount);
+
+    float baseImageIncrement[2];
+    getImageIncrement(conv, &baseImageIncrement);
+
+    for (int i = 0; i < sampleCount; i++) {
+        int sampleIndex1 = i * 2;
+        int sampleIndex2 = sampleIndex1 + 1;
+
+        // If we have an odd number of samples in our filter, the last sample won't use
+        // the linear interpolation optimization (it will be pixel aligned).
+        if (sampleIndex2 >= this->width()) {
+            sampleIndex2 = sampleIndex1;
+        }
+
+        float kernelWeight1 = conv.kernel()[sampleIndex1];
+        float kernelWeight2 = conv.kernel()[sampleIndex2];
+
+        float totalKernelWeight =
+            (sampleIndex1 == sampleIndex2) ? kernelWeight1 : (kernelWeight1 + kernelWeight2);
+
+        float sampleRatio =
+            (sampleIndex1 == sampleIndex2) ? 0 : kernelWeight2 / (kernelWeight1 + kernelWeight2);
+
+        imageIncrements[i * 2] = (-this->radius() + i * 2 + sampleRatio) * baseImageIncrement[0];
+        imageIncrements[i * 2 + 1] =
+            (-this->radius() + i * 2 + sampleRatio) * baseImageIncrement[1];
+
+        kernel[i] = totalKernelWeight;
     }
-    b->add32(key);
+    pdman.set2fv(fSampleOffsetUni, sampleCount, imageIncrements.get());
+    pdman.set1fv(fSampleWeightUni, sampleCount, kernel.get());
+}
+
+int GrGLLerpConvolutionEffect::bilerpSampleCount() const {
+    // We use a linear interpolation optimization to only sample once for each
+    // two pixel aligned samples in the kernel. If we have an odd number of
+    // samples, we will have to skip this optimization for the last sample.
+    // Because of this we always round up our sample count (by adding 1 before
+    // dividing).
+    return (this->width() + 1) / 2;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -161,7 +318,13 @@ GrConvolutionEffect::GrConvolutionEffect(GrProcessorDataManager* procDataManager
                                          const float* kernel,
                                          bool useBounds,
                                          float bounds[2])
-    : INHERITED(procDataManager, texture, direction, radius), fUseBounds(useBounds) {
+    : INHERITED(procDataManager,
+                texture,
+                direction,
+                radius,
+                useBounds ? GrTextureParams::FilterMode::kNone_FilterMode
+                          : GrTextureParams::FilterMode::kBilerp_FilterMode)
+    , fUseBounds(useBounds) {
     this->initClassID<GrConvolutionEffect>();
     SkASSERT(radius <= kMaxKernelRadius);
     SkASSERT(kernel);
@@ -179,7 +342,13 @@ GrConvolutionEffect::GrConvolutionEffect(GrProcessorDataManager* procDataManager
                                          float gaussianSigma,
                                          bool useBounds,
                                          float bounds[2])
-    : INHERITED(procDataManager, texture, direction, radius), fUseBounds(useBounds) {
+    : INHERITED(procDataManager,
+                texture,
+                direction,
+                radius,
+                useBounds ? GrTextureParams::FilterMode::kNone_FilterMode
+                          : GrTextureParams::FilterMode::kBilerp_FilterMode)
+    , fUseBounds(useBounds) {
     this->initClassID<GrConvolutionEffect>();
     SkASSERT(radius <= kMaxKernelRadius);
     int width = this->width();
@@ -210,7 +379,15 @@ void GrConvolutionEffect::getGLProcessorKey(const GrGLSLCaps& caps,
 }
 
 GrGLFragmentProcessor* GrConvolutionEffect::createGLInstance() const  {
-    return SkNEW_ARGS(GrGLConvolutionEffect, (*this));
+    // We support a linear interpolation optimization which (when feasible) uses
+    // half the number of samples to apply the kernel. This is not always
+    // applicable, as the linear interpolation optimization does not support
+    // bounded sampling.
+    if (this->useBounds()) {
+        return SkNEW_ARGS(GrGLBoundedConvolutionEffect, (*this));
+    } else {
+        return SkNEW_ARGS(GrGLLerpConvolutionEffect, (*this));
+    }
 }
 
 bool GrConvolutionEffect::onIsEqual(const GrFragmentProcessor& sBase) const {