Begin instanced rendering for simple shapes

src/gpu/instanced/InstanceProcessor.cpp

Index: src/gpu/instanced/InstanceProcessor.cpp
diff --git a/src/gpu/instanced/InstanceProcessor.cpp b/src/gpu/instanced/InstanceProcessor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..acad4c1e1b0e446d71de88e1411cd534759bef24
--- /dev/null
+++ b/src/gpu/instanced/InstanceProcessor.cpp
@@ -0,0 +1,2096 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "InstanceProcessor.h"
+
+#include "GrContext.h"
+#include "GrRenderTargetPriv.h"
+#include "GrResourceCache.h"
+#include "GrResourceProvider.h"
+#include "glsl/GrGLSLGeometryProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLProgramBuilder.h"
+#include "glsl/GrGLSLVarying.h"
+
+namespace gr_instanced {
+
+bool InstanceProcessor::IsSupported(const GrGLSLCaps& glslCaps, const GrCaps& caps,
+                                    AntialiasMode* lastSupportedAAMode) {
+    if (!glslCaps.canUseAnyFunctionInShader() ||
+        !glslCaps.flatInterpolationSupport() ||
+        !glslCaps.integerSupport() ||
+        0 == glslCaps.maxVertexSamplers() ||
+        !caps.shaderCaps()->texelBufferSupport() ||
+        caps.maxVertexAttributes() < kNumAttribs) {
+        return false;
+    }
+    if (caps.sampleLocationsSupport() &&
+        glslCaps.sampleVariablesSupport() &&
+        glslCaps.shaderDerivativeSupport()) {
+        if (0 != caps.maxRasterSamples() &&
+            glslCaps.sampleMaskOverrideCoverageSupport()) {
+            *lastSupportedAAMode = AntialiasMode::kMixedSamples;
+        } else {
+            *lastSupportedAAMode = AntialiasMode::kMSAA;
+        }
+    } else {
+        *lastSupportedAAMode = AntialiasMode::kCoverage;
+    }
+    return true;
+}
+
+InstanceProcessor::InstanceProcessor(BatchInfo batchInfo, GrBuffer* paramsBuffer)
+    : fBatchInfo(batchInfo) {
+    this->initClassID<InstanceProcessor>();
+
+    this->addVertexAttrib(Attribute("shapeCoords", kVec2f_GrVertexAttribType, kHigh_GrSLPrecision));
+    this->addVertexAttrib(Attribute("vertexAttrs", kInt_GrVertexAttribType));
+    this->addVertexAttrib(Attribute("instanceInfo", kUint_GrVertexAttribType));
+    this->addVertexAttrib(Attribute("shapeMatrixX", kVec3f_GrVertexAttribType,
+                                    kHigh_GrSLPrecision));
+    this->addVertexAttrib(Attribute("shapeMatrixY", kVec3f_GrVertexAttribType,
+                                    kHigh_GrSLPrecision));
+    this->addVertexAttrib(Attribute("color", kVec4f_GrVertexAttribType, kLow_GrSLPrecision));
+    this->addVertexAttrib(Attribute("localRect", kVec4f_GrVertexAttribType, kHigh_GrSLPrecision));
+
+    GR_STATIC_ASSERT(0 == (int)Attrib::kShapeCoords);
+    GR_STATIC_ASSERT(1 == (int)Attrib::kVertexAttrs);
+    GR_STATIC_ASSERT(2 == (int)Attrib::kInstanceInfo);
+    GR_STATIC_ASSERT(3 == (int)Attrib::kShapeMatrixX);
+    GR_STATIC_ASSERT(4 == (int)Attrib::kShapeMatrixY);
+    GR_STATIC_ASSERT(5 == (int)Attrib::kColor);
+    GR_STATIC_ASSERT(6 == (int)Attrib::kLocalRect);
+    GR_STATIC_ASSERT(7 == kNumAttribs);
+
+    if (fBatchInfo.fHasParams) {
+        SkASSERT(paramsBuffer);
+        fParamsAccess.reset(kRGBA_float_GrPixelConfig, paramsBuffer, kVertex_GrShaderFlag);
+        this->addBufferAccess(&fParamsAccess);
+    }
+
+    if (fBatchInfo.fAntialiasMode >= AntialiasMode::kMSAA) {
+        if (!fBatchInfo.isSimpleRects() ||
+            AntialiasMode::kMixedSamples == fBatchInfo.fAntialiasMode) {
+            this->setWillUseSampleLocations();
+        }
+    }
+}
+
+class GLSLInstanceProcessor : public GrGLSLGeometryProcessor {
+public:
+    void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override;
+
+private:
+    void setData(const GrGLSLProgramDataManager&, const GrPrimitiveProcessor&) override {}
+
+    class VertexInputs;
+    class Backend;
+    class BackendNonAA;
+    class BackendCoverage;
+    class BackendMultisample;
+
+    typedef GrGLSLGeometryProcessor INHERITED;
+};
+
+GrGLSLPrimitiveProcessor* InstanceProcessor::createGLSLInstance(const GrGLSLCaps&) const {
+    return new GLSLInstanceProcessor();
+}
+
+class GLSLInstanceProcessor::VertexInputs {
+public:
+    VertexInputs(const InstanceProcessor& instProc, GrGLSLVertexBuilder* vertexBuilder)
+        : fInstProc(instProc),
+          fVertexBuilder(vertexBuilder) {
+    }
+
+    void initParams(const SamplerHandle paramsBuffer) {
+        fParamsBuffer = paramsBuffer;
+        fVertexBuilder->definef("PARAMS_IDX_MASK", "0x%xu", kParamsIdx_InfoMask);
+        fVertexBuilder->appendPrecisionModifier(kHigh_GrSLPrecision);
+        fVertexBuilder->codeAppendf("int paramsIdx = int(%s & PARAMS_IDX_MASK);",
+                                    this->attr(Attrib::kInstanceInfo));
+    }
+
+    const char* attr(Attrib attr) const { return fInstProc.getAttrib((int)attr).fName; }
+
+    void fetchNextParam(GrSLType type = kVec4f_GrSLType) const {
+        SkASSERT(fParamsBuffer.isValid());
+        if (type != kVec4f_GrSLType) {
+            fVertexBuilder->codeAppendf("%s(", GrGLSLTypeString(type));
+        }
+        fVertexBuilder->appendTexelFetch(fParamsBuffer, "paramsIdx++");
+        if (type != kVec4f_GrSLType) {
+            fVertexBuilder->codeAppend(")");
+        }
+    }
+
+    void skipParams(unsigned n) const {
+        SkASSERT(fParamsBuffer.isValid());
+        fVertexBuilder->codeAppendf("paramsIdx += %u;", n);
+    }
+
+private:
+    const InstanceProcessor&     fInstProc;
+    GrGLSLVertexBuilder*         fVertexBuilder;
+    SamplerHandle                fParamsBuffer;
+};
+
+class GLSLInstanceProcessor::Backend {
+public:
+    static Backend* SK_WARN_UNUSED_RESULT Create(const GrPipeline&, BatchInfo, const VertexInputs&);
+    virtual ~Backend() {}
+
+    void init(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*);
+    virtual void setupRect(GrGLSLVertexBuilder*) = 0;
+    virtual void setupOval(GrGLSLVertexBuilder*) = 0;
+    void setupRRect(GrGLSLVertexBuilder*);
+
+    void initInnerShape(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*);
+    virtual void setupInnerRect(GrGLSLVertexBuilder*) = 0;
+    virtual void setupInnerOval(GrGLSLVertexBuilder*) = 0;
+    void setupInnerRRect(GrGLSLVertexBuilder*);
+
+    const char* outShapeCoords() {
+        return fModifiedShapeCoords ? fModifiedShapeCoords : fInputs.attr(Attrib::kShapeCoords);
+    }
+
+    void emitCode(GrGLSLVertexBuilder*, GrGLSLPPFragmentBuilder*, const char* outCoverage,
+                  const char* outColor);
+
+protected:
+    Backend(BatchInfo batchInfo, const VertexInputs& inputs)
+        : fBatchInfo(batchInfo),
+          fInputs(inputs),
+          fModifiesCoverage(false),
+          fModifiesColor(false),
+          fNeedsNeighborRadii(false),
+          fColor(kVec4f_GrSLType),
+          fTriangleIsArc(kInt_GrSLType),
+          fArcCoords(kVec2f_GrSLType),
+          fInnerShapeCoords(kVec2f_GrSLType),
+          fInnerRRect(kVec4f_GrSLType),
+          fModifiedShapeCoords(nullptr) {
+        if (fBatchInfo.fShapeTypes & kRRect_ShapesMask) {
+            fModifiedShapeCoords = "adjustedShapeCoords";
+        }
+    }
+
+    virtual void onInit(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) = 0;
+    virtual void adjustRRectVertices(GrGLSLVertexBuilder*);
+    virtual void onSetupRRect(GrGLSLVertexBuilder*) {}
+
+    virtual void onInitInnerShape(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) = 0;
+    virtual void onSetupInnerRRect(GrGLSLVertexBuilder*) = 0;
+
+    virtual void onEmitCode(GrGLSLVertexBuilder*, GrGLSLPPFragmentBuilder*,
+                            const char* outCoverage, const char* outColor) = 0;
+
+    void setupSimpleRadii(GrGLSLVertexBuilder*);
+    void setupNinePatchRadii(GrGLSLVertexBuilder*);
+    void setupComplexRadii(GrGLSLVertexBuilder*);
+
+    const BatchInfo       fBatchInfo;
+    const VertexInputs&   fInputs;
+    bool                  fModifiesCoverage;
+    bool                  fModifiesColor;
+    bool                  fNeedsNeighborRadii;
+    GrGLSLVertToFrag      fColor;
+    GrGLSLVertToFrag      fTriangleIsArc;
+    GrGLSLVertToFrag      fArcCoords;
+    GrGLSLVertToFrag      fInnerShapeCoords;
+    GrGLSLVertToFrag      fInnerRRect;
+    const char*           fModifiedShapeCoords;
+};
+
+void GLSLInstanceProcessor::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
+    const GrPipeline& pipeline = args.fVertBuilder->getProgramBuilder()->pipeline();
+    const InstanceProcessor& ip = args.fGP.cast<InstanceProcessor>();
+    GrGLSLUniformHandler* uniHandler = args.fUniformHandler;
+    GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
+    GrGLSLVertexBuilder* v = args.fVertBuilder;
+    GrGLSLPPFragmentBuilder* f = args.fFragBuilder;
+
+    varyingHandler->emitAttributes(ip);
+
+    VertexInputs inputs(ip, v);
+    if (ip.batchInfo().fHasParams) {
+        SkASSERT(1 == ip.numBuffers());
+        inputs.initParams(args.fBufferSamplers[0]);
+    }
+
+    if (!ip.batchInfo().fHasPerspective) {
+        v->codeAppendf("mat2x3 shapeMatrix = mat2x3(%s, %s);",
+                       inputs.attr(Attrib::kShapeMatrixX), inputs.attr(Attrib::kShapeMatrixY));
+    } else {
+        v->definef("PERSPECTIVE_FLAG", "0x%xu", kPerspective_InfoFlag);
+        v->codeAppendf("mat3 shapeMatrix = mat3(%s, %s, vec3(0, 0, 1));",
+                       inputs.attr(Attrib::kShapeMatrixX), inputs.attr(Attrib::kShapeMatrixY));
+        v->codeAppendf("if (0u != (%s & PERSPECTIVE_FLAG)) {",
+                       inputs.attr(Attrib::kInstanceInfo));
+        v->codeAppend (    "shapeMatrix[2] = ");
+        inputs.fetchNextParam(kVec3f_GrSLType);
+        v->codeAppend (    ";");
+        v->codeAppend ("}");
+    }
+
+    int usedShapeTypes = 0;
+
+    bool hasSingleShapeType = SkIsPow2(ip.batchInfo().fShapeTypes);
+    if (!hasSingleShapeType) {
+        usedShapeTypes |= ip.batchInfo().fShapeTypes;
+        v->define("SHAPE_TYPE_BIT", kShapeType_InfoBit);
+        v->codeAppendf("uint shapeType = %s >> SHAPE_TYPE_BIT;",
+                       inputs.attr(Attrib::kInstanceInfo));
+    }
+
+    SkAutoTDelete<Backend> backend(Backend::Create(pipeline, ip.batchInfo(), inputs));
+    backend->init(varyingHandler, v);
+
+    if (hasSingleShapeType) {
+        if (kRect_ShapeFlag == ip.batchInfo().fShapeTypes) {
+            backend->setupRect(v);
+        } else if (kOval_ShapeFlag == ip.batchInfo().fShapeTypes) {
+            backend->setupOval(v);
+        } else {
+            backend->setupRRect(v);
+        }
+    } else {
+        v->codeAppend ("switch (shapeType) {");
+        if (ip.batchInfo().fShapeTypes & kRect_ShapeFlag) {
+            v->codeAppend ("case RECT_SHAPE_TYPE: {");
+            backend->setupRect(v);
+            v->codeAppend ("} break;");
+        }
+        if (ip.batchInfo().fShapeTypes & kOval_ShapeFlag) {
+            v->codeAppend ("case OVAL_SHAPE_TYPE: {");
+            backend->setupOval(v);
+            v->codeAppend ("} break;");
+        }
+        if (ip.batchInfo().fShapeTypes & kRRect_ShapesMask) {
+            v->codeAppend ("default: {");
+            backend->setupRRect(v);
+            v->codeAppend ("} break;");
+        }
+        v->codeAppend ("}");
+    }
+
+    if (ip.batchInfo().fInnerShapeTypes) {
+        bool hasSingleInnerShapeType = SkIsPow2(ip.batchInfo().fInnerShapeTypes);
+        if (!hasSingleInnerShapeType) {
+            usedShapeTypes |= ip.batchInfo().fInnerShapeTypes;
+            v->definef("INNER_SHAPE_TYPE_MASK", "0x%xu", kInnerShapeType_InfoMask);
+            v->define("INNER_SHAPE_TYPE_BIT", kInnerShapeType_InfoBit);
+            v->codeAppendf("uint innerShapeType = ((%s & INNER_SHAPE_TYPE_MASK) >> "
+                                                  "INNER_SHAPE_TYPE_BIT);",
+                           inputs.attr(Attrib::kInstanceInfo));
+        }
+        // Here we take advantage of the fact that outerRect == localRect in recordDRRect.
+        v->codeAppendf("vec4 outer = %s;", inputs.attr(Attrib::kLocalRect));
+        v->codeAppend ("vec4 inner = ");
+        inputs.fetchNextParam();
+        v->codeAppend (";");
+        // outer2Inner is a transform from shape coords to inner shape coords:
+        // e.g. innerShapeCoords = shapeCoords * outer2Inner.xy + outer2Inner.zw
+        v->codeAppend ("vec4 outer2Inner = vec4(outer.zw - outer.xy, "
+                                               "outer.xy + outer.zw - inner.xy - inner.zw) / "
+                                               "(inner.zw - inner.xy).xyxy;");
+        v->codeAppendf("vec2 innerShapeCoords = %s * outer2Inner.xy + outer2Inner.zw;",
+                       backend->outShapeCoords());
+
+        backend->initInnerShape(varyingHandler, v);
+
+        if (hasSingleInnerShapeType) {
+            if (kRect_ShapeFlag == ip.batchInfo().fInnerShapeTypes) {
+                backend->setupInnerRect(v);
+            } else if (kOval_ShapeFlag == ip.batchInfo().fInnerShapeTypes) {
+                backend->setupInnerOval(v);
+            } else {
+                backend->setupInnerRRect(v);
+            }
+        } else {
+            v->codeAppend("switch (innerShapeType) {");
+            if (ip.batchInfo().fInnerShapeTypes & kRect_ShapeFlag) {
+                v->codeAppend("case RECT_SHAPE_TYPE: {");
+                backend->setupInnerRect(v);
+                v->codeAppend("} break;");
+            }
+            if (ip.batchInfo().fInnerShapeTypes & kOval_ShapeFlag) {
+                v->codeAppend("case OVAL_SHAPE_TYPE: {");
+                backend->setupInnerOval(v);
+                v->codeAppend("} break;");
+            }
+            if (ip.batchInfo().fInnerShapeTypes & kRRect_ShapesMask) {
+                v->codeAppend("default: {");
+                backend->setupInnerRRect(v);
+                v->codeAppend("} break;");
+            }
+            v->codeAppend("}");
+        }
+    }
+
+    if (usedShapeTypes & kRect_ShapeFlag) {
+        v->definef("RECT_SHAPE_TYPE", "%du", (int)ShapeType::kRect);
+    }
+    if (usedShapeTypes & kOval_ShapeFlag) {
+        v->definef("OVAL_SHAPE_TYPE", "%du", (int)ShapeType::kOval);
+    }
+
+    backend->emitCode(v, f, pipeline.ignoresCoverage() ? nullptr : args.fOutputCoverage,
+                      args.fOutputColor);
+
+    const char* localCoords = nullptr;
+    if (ip.batchInfo().fUsesLocalCoords) {
+        localCoords = "localCoords";
+        v->codeAppendf("vec2 t = 0.5 * (%s + vec2(1));", backend->outShapeCoords());
+        v->codeAppendf("vec2 localCoords = (1.0 - t) * %s.xy + t * %s.zw;",
+                       inputs.attr(Attrib::kLocalRect), inputs.attr(Attrib::kLocalRect));
+    }
+    if (ip.batchInfo().fHasLocalMatrix && ip.batchInfo().fHasParams) {
+        v->definef("LOCAL_MATRIX_FLAG", "0x%xu", kLocalMatrix_InfoFlag);
+        v->codeAppendf("if (0u != (%s & LOCAL_MATRIX_FLAG)) {",
+                       inputs.attr(Attrib::kInstanceInfo));
+        if (!ip.batchInfo().fUsesLocalCoords) {
+            inputs.skipParams(2);
+        } else {
+            v->codeAppendf(    "mat2x3 localMatrix;");
+            v->codeAppend (    "localMatrix[0] = ");
+            inputs.fetchNextParam(kVec3f_GrSLType);
+            v->codeAppend (    ";");
+            v->codeAppend (    "localMatrix[1] = ");
+            inputs.fetchNextParam(kVec3f_GrSLType);
+            v->codeAppend (    ";");
+            v->codeAppend (    "localCoords = (vec3(localCoords, 1) * localMatrix).xy;");
+        }
+        v->codeAppend("}");
+    }
+
+    GrSLType positionType = ip.batchInfo().fHasPerspective ? kVec3f_GrSLType : kVec2f_GrSLType;
+    v->codeAppendf("%s deviceCoords = vec3(%s, 1) * shapeMatrix;",
+                   GrGLSLTypeString(positionType), backend->outShapeCoords());
+    gpArgs->fPositionVar.set(positionType, "deviceCoords");
+
+    this->emitTransforms(v, varyingHandler, uniHandler, gpArgs->fPositionVar, localCoords,
+                         args.fTransformsIn, args.fTransformsOut);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void GLSLInstanceProcessor::Backend::init(GrGLSLVaryingHandler* varyingHandler,
+                                          GrGLSLVertexBuilder* v) {
+    if (fModifiedShapeCoords) {
+        v->codeAppendf("vec2 %s = %s;", fModifiedShapeCoords, fInputs.attr(Attrib::kShapeCoords));
+    }
+
+    this->onInit(varyingHandler, v);
+
+    if (!fColor.vsOut()) {
+        varyingHandler->addFlatVarying("color", &fColor, kLow_GrSLPrecision);
+        v->codeAppendf("%s = %s;", fColor.vsOut(), fInputs.attr(Attrib::kColor));
+    }
+}
+
+void GLSLInstanceProcessor::Backend::setupRRect(GrGLSLVertexBuilder* v) {
+    v->codeAppendf("uvec2 corner = uvec2(%s & 1, (%s >> 1) & 1);",
+                   fInputs.attr(Attrib::kVertexAttrs), fInputs.attr(Attrib::kVertexAttrs));
+    v->codeAppend ("vec2 cornerSign = vec2(corner) * 2.0 - 1.0;");
+    v->codeAppendf("vec2 radii%s;", fNeedsNeighborRadii ? ", neighborRadii" : "");
+    v->codeAppend ("mat2 p = ");
+    fInputs.fetchNextParam(kMat22f_GrSLType);
+    v->codeAppend (";");
+    uint8_t types = fBatchInfo.fShapeTypes & kRRect_ShapesMask;
+    if (0 == (types & (types - 1))) {
+        if (kSimpleRRect_ShapeFlag == types) {
+            this->setupSimpleRadii(v);
+        } else if (kNinePatch_ShapeFlag == types) {
+            this->setupNinePatchRadii(v);
+        } else if (kComplexRRect_ShapeFlag == types) {
+            this->setupComplexRadii(v);
+        }
+    } else {
+        v->codeAppend("switch (shapeType) {");
+        if (types & kSimpleRRect_ShapeFlag) {
+            v->definef("SIMPLE_R_RECT_SHAPE_TYPE", "%du", (int)ShapeType::kSimpleRRect);
+            v->codeAppend ("case SIMPLE_R_RECT_SHAPE_TYPE: {");
+            this->setupSimpleRadii(v);
+            v->codeAppend ("} break;");
+        }
+        if (types & kNinePatch_ShapeFlag) {
+            v->definef("NINE_PATCH_SHAPE_TYPE", "%du", (int)ShapeType::kNinePatch);
+            v->codeAppend ("case NINE_PATCH_SHAPE_TYPE: {");
+            this->setupNinePatchRadii(v);
+            v->codeAppend ("} break;");
+        }
+        if (types & kComplexRRect_ShapeFlag) {
+            v->codeAppend ("default: {");
+            this->setupComplexRadii(v);
+            v->codeAppend ("} break;");
+        }
+        v->codeAppend("}");
+    }
+
+    this->adjustRRectVertices(v);
+
+    if (fArcCoords.vsOut()) {
+        v->codeAppendf("%s = (cornerSign * %s + radii - vec2(1)) / radii;",
+                       fArcCoords.vsOut(), fModifiedShapeCoords);
+    }
+    if (fTriangleIsArc.vsOut()) {
+        v->codeAppendf("%s = int(all(equal(vec2(1), abs(%s))));",
+                       fTriangleIsArc.vsOut(), fInputs.attr(Attrib::kShapeCoords));
+    }
+
+    this->onSetupRRect(v);
+}
+
+void GLSLInstanceProcessor::Backend::setupSimpleRadii(GrGLSLVertexBuilder* v) {
+    if (fNeedsNeighborRadii) {
+        v->codeAppend ("neighborRadii = ");
+    }
+    v->codeAppend("radii = p[0] * 2.0 / p[1];");
+}
+
+void GLSLInstanceProcessor::Backend::setupNinePatchRadii(GrGLSLVertexBuilder* v) {
+    v->codeAppend("radii = vec2(p[0][corner.x], p[1][corner.y]);");
+    if (fNeedsNeighborRadii) {
+        v->codeAppend("neighborRadii = vec2(p[0][1u - corner.x], p[1][1u - corner.y]);");
+    }
+}
+
+void GLSLInstanceProcessor::Backend::setupComplexRadii(GrGLSLVertexBuilder* v) {
+    /**
+     * The x and y radii of each arc are stored in separate vectors,
+     * in the following order:
+     *
+     *        __x1 _ _ _ x3__
+     *
+     *    y1 |               | y2
+     *
+     *       |               |
+     *
+     *    y3 |__   _ _ _   __| y4
+     *          x2       x4
+     *
+     */
+    v->codeAppend("mat2 p2 = ");
+    fInputs.fetchNextParam(kMat22f_GrSLType);
+    v->codeAppend(";");
+    v->codeAppend("radii = vec2(p[corner.x][corner.y], p2[corner.y][corner.x]);");
+    if (fNeedsNeighborRadii) {
+        v->codeAppend("neighborRadii = vec2(p[1u - corner.x][corner.y], "
+                                           "p2[1u - corner.y][corner.x]);");
+    }
+}
+
+void GLSLInstanceProcessor::Backend::adjustRRectVertices(GrGLSLVertexBuilder* v) {
+    // Resize the 4 triangles that arcs are drawn into so they match their corresponding radii.
+    // 0.5 is a special value that indicates the edge of an arc triangle.
+    v->codeAppendf("if (abs(%s.x) == 0.5)"
+                       "%s.x = cornerSign.x * (1.0 - radii.x);",
+                       fInputs.attr(Attrib::kShapeCoords), fModifiedShapeCoords);
+    v->codeAppendf("if (abs(%s.y) == 0.5) "
+                       "%s.y = cornerSign.y * (1.0 - radii.y);",
+                       fInputs.attr(Attrib::kShapeCoords), fModifiedShapeCoords);
+}
+
+void GLSLInstanceProcessor::Backend::initInnerShape(GrGLSLVaryingHandler* varyingHandler,
+                                                    GrGLSLVertexBuilder* v) {
+    SkASSERT(!(fBatchInfo.fInnerShapeTypes & (kNinePatch_ShapeFlag | kComplexRRect_ShapeFlag)));
+
+    this->onInitInnerShape(varyingHandler, v);
+
+    if (fInnerShapeCoords.vsOut()) {
+        v->codeAppendf("%s = innerShapeCoords;", fInnerShapeCoords.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::Backend::setupInnerRRect(GrGLSLVertexBuilder* v) {
+    v->codeAppend("mat2 innerP = ");
+    fInputs.fetchNextParam(kMat22f_GrSLType);
+    v->codeAppend(";");
+    v->codeAppend("vec2 innerRadii = innerP[0] * 2.0 / innerP[1];");
+    this->onSetupInnerRRect(v);
+}
+
+void GLSLInstanceProcessor::Backend::emitCode(GrGLSLVertexBuilder* v, GrGLSLPPFragmentBuilder* f,
+                                              const char* outCoverage, const char* outColor) {
+    SkASSERT(!fModifiesCoverage || outCoverage);
+    this->onEmitCode(v, f, fModifiesCoverage ? outCoverage : nullptr,
+                     fModifiesColor ? outColor : nullptr);
+    if (outCoverage && !fModifiesCoverage) {
+        // Even though the subclass doesn't use coverage, we are expected to assign some value.
+        f->codeAppendf("%s = vec4(1);", outCoverage);
+    }
+    if (!fModifiesColor) {
+        // The subclass didn't assign a value to the output color.
+        f->codeAppendf("%s = %s;", outColor, fColor.fsIn());
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class GLSLInstanceProcessor::BackendNonAA : public Backend {
+public:
+    BackendNonAA(BatchInfo batchInfo, const VertexInputs& inputs)
+        : INHERITED(batchInfo, inputs) {
+        if (fBatchInfo.fCannotDiscard && !fBatchInfo.isSimpleRects()) {
+            fModifiesColor = !fBatchInfo.fCannotTweakAlphaForCoverage;
+            fModifiesCoverage = !fModifiesColor;
+        }
+    }
+
+private:
+    void onInit(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupRect(GrGLSLVertexBuilder*) override;
+    void setupOval(GrGLSLVertexBuilder*) override;
+
+    void onInitInnerShape(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupInnerRect(GrGLSLVertexBuilder*) override;
+    void setupInnerOval(GrGLSLVertexBuilder*) override;
+    void onSetupInnerRRect(GrGLSLVertexBuilder*) override;
+
+    void onEmitCode(GrGLSLVertexBuilder*, GrGLSLPPFragmentBuilder*, const char*,
+                    const char*) override;
+
+    typedef Backend INHERITED;
+};
+
+void GLSLInstanceProcessor::BackendNonAA::onInit(GrGLSLVaryingHandler* varyingHandler,
+                                                 GrGLSLVertexBuilder*) {
+    if (kRect_ShapeFlag != fBatchInfo.fShapeTypes) {
+        varyingHandler->addFlatVarying("triangleIsArc", &fTriangleIsArc, kHigh_GrSLPrecision);
+        varyingHandler->addVarying("arcCoords", &fArcCoords, kMedium_GrSLPrecision);
+    }
+}
+
+void GLSLInstanceProcessor::BackendNonAA::setupRect(GrGLSLVertexBuilder* v) {
+    if (fTriangleIsArc.vsOut()) {
+        v->codeAppendf("%s = 0;", fTriangleIsArc.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendNonAA::setupOval(GrGLSLVertexBuilder* v) {
+    SkASSERT(fArcCoords.vsOut());
+    SkASSERT(fTriangleIsArc.vsOut());
+    v->codeAppendf("%s = %s;", fArcCoords.vsOut(), this->outShapeCoords());
+    v->codeAppendf("%s = %s & 1;", fTriangleIsArc.vsOut(), fInputs.attr(Attrib::kVertexAttrs));
+}
+
+void GLSLInstanceProcessor::BackendNonAA::onInitInnerShape(GrGLSLVaryingHandler* varyingHandler,
+                                                           GrGLSLVertexBuilder*) {
+    varyingHandler->addVarying("innerShapeCoords", &fInnerShapeCoords, kMedium_GrSLPrecision);
+    if (kRect_ShapeFlag != fBatchInfo.fInnerShapeTypes &&
+        kOval_ShapeFlag != fBatchInfo.fInnerShapeTypes) {
+        varyingHandler->addFlatVarying("innerRRect", &fInnerRRect, kMedium_GrSLPrecision);
+    }
+}
+
+void GLSLInstanceProcessor::BackendNonAA::setupInnerRect(GrGLSLVertexBuilder* v) {
+    if (fInnerRRect.vsOut()) {
+        v->codeAppendf("%s = vec4(1);", fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendNonAA::setupInnerOval(GrGLSLVertexBuilder* v) {
+    if (fInnerRRect.vsOut()) {
+        v->codeAppendf("%s = vec4(0, 0, 1, 1);", fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendNonAA::onSetupInnerRRect(GrGLSLVertexBuilder* v) {
+    v->codeAppendf("%s = vec4(1.0 - innerRadii, 1.0 / innerRadii);", fInnerRRect.vsOut());
+}
+
+void GLSLInstanceProcessor::BackendNonAA::onEmitCode(GrGLSLVertexBuilder*,
+                                                     GrGLSLPPFragmentBuilder* f,
+                                                     const char* outCoverage,
+                                                     const char* outColor) {
+    const char* dropFragment = nullptr;
+    if (!fBatchInfo.fCannotDiscard) {
+        dropFragment = "discard";
+    } else if (fModifiesCoverage) {
+        f->appendPrecisionModifier(kLow_GrSLPrecision);
+        f->codeAppend ("float covered = 1.0;");
+        dropFragment = "covered = 0.0";
+    } else if (fModifiesColor) {
+        f->appendPrecisionModifier(kLow_GrSLPrecision);
+        f->codeAppendf("vec4 color = %s;", fColor.fsIn());
+        dropFragment = "color = vec4(0)";
+    }
+    if (fTriangleIsArc.fsIn()) {
+        SkASSERT(dropFragment);
+        f->codeAppendf("if (%s != 0 && dot(%s, %s) > 1.0) %s;",
+                       fTriangleIsArc.fsIn(), fArcCoords.fsIn(), fArcCoords.fsIn(), dropFragment);
+    }
+    if (fBatchInfo.fInnerShapeTypes) {
+        SkASSERT(dropFragment);
+        f->codeAppendf("// Inner shape.\n");
+        if (kRect_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+            f->codeAppendf("if (all(lessThanEqual(abs(%s), vec2(1)))) %s;",
+                           fInnerShapeCoords.fsIn(), dropFragment);
+        } else if (kOval_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+            f->codeAppendf("if ((dot(%s, %s) <= 1.0)) %s;",
+                           fInnerShapeCoords.fsIn(), fInnerShapeCoords.fsIn(), dropFragment);
+        } else {
+            f->codeAppendf("if (all(lessThan(abs(%s), vec2(1)))) {", fInnerShapeCoords.fsIn());
+            f->codeAppendf(    "vec2 distanceToArcEdge = abs(%s) - %s.xy;",
+                               fInnerShapeCoords.fsIn(), fInnerRRect.fsIn());
+            f->codeAppend (    "if (any(lessThan(distanceToArcEdge, vec2(0)))) {");
+            f->codeAppendf(        "%s;", dropFragment);
+            f->codeAppend (    "} else {");
+            f->codeAppendf(        "vec2 rrectCoords = distanceToArcEdge * %s.zw;",
+                                   fInnerRRect.fsIn());
+            f->codeAppend (        "if (dot(rrectCoords, rrectCoords) <= 1.0) {");
+            f->codeAppendf(            "%s;", dropFragment);
+            f->codeAppend (        "}");
+            f->codeAppend (    "}");
+            f->codeAppend ("}");
+        }
+    }
+    if (fModifiesCoverage) {
+        f->codeAppendf("%s = vec4(covered);", outCoverage);
+    } else if (fModifiesColor) {
+        f->codeAppendf("%s = color;", outColor);
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class GLSLInstanceProcessor::BackendCoverage : public Backend {
+public:
+    BackendCoverage(BatchInfo batchInfo, const VertexInputs& inputs)
+        : INHERITED(batchInfo, inputs),
+          fColorTimesRectCoverage(kVec4f_GrSLType),
+          fRectCoverage(kFloat_GrSLType),
+          fEllipseCoords(kVec2f_GrSLType),
+          fEllipseName(kVec2f_GrSLType),
+          fBloatedRadius(kFloat_GrSLType),
+          fDistanceToInnerEdge(kVec2f_GrSLType),
+          fInnerShapeBloatedHalfSize(kVec2f_GrSLType),
+          fInnerEllipseCoords(kVec2f_GrSLType),
+          fInnerEllipseName(kVec2f_GrSLType) {
+        fShapeIsCircle = !fBatchInfo.fNonSquare && !(fBatchInfo.fShapeTypes & kRRect_ShapesMask);
+        fTweakAlphaForCoverage = !fBatchInfo.fCannotTweakAlphaForCoverage &&
+                                 !fBatchInfo.fInnerShapeTypes;
+        fModifiesCoverage = !fTweakAlphaForCoverage;
+        fModifiesColor = fTweakAlphaForCoverage;
+        fModifiedShapeCoords = "bloatedShapeCoords";
+    }
+
+private:
+    void onInit(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupRect(GrGLSLVertexBuilder*) override;
+    void setupOval(GrGLSLVertexBuilder*) override;
+    void adjustRRectVertices(GrGLSLVertexBuilder*) override;
+    void onSetupRRect(GrGLSLVertexBuilder*) override;
+
+    void onInitInnerShape(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupInnerRect(GrGLSLVertexBuilder*) override;
+    void setupInnerOval(GrGLSLVertexBuilder*) override;
+    void onSetupInnerRRect(GrGLSLVertexBuilder*) override;
+
+    void onEmitCode(GrGLSLVertexBuilder*, GrGLSLPPFragmentBuilder*, const char* outCoverage,
+                    const char* outColor) override;
+
+    void emitRect(GrGLSLPPFragmentBuilder*, const char* outCoverage, const char* outColor);
+    void emitCircle(GrGLSLPPFragmentBuilder*, const char* outCoverage);
+    void emitArc(GrGLSLPPFragmentBuilder* f, const char* ellipseCoords, const char* ellipseName,
+                 bool ellipseCoordsNeedClamp, bool ellipseCoordsMayBeNegative,
+                 const char* outCoverage);
+    void emitInnerRect(GrGLSLPPFragmentBuilder*, const char* outCoverage);
+
+    GrGLSLVertToFrag   fColorTimesRectCoverage;
+    GrGLSLVertToFrag   fRectCoverage;
+    GrGLSLVertToFrag   fEllipseCoords;
+    GrGLSLVertToFrag   fEllipseName;
+    GrGLSLVertToFrag   fBloatedRadius;
+    GrGLSLVertToFrag   fDistanceToInnerEdge;
+    GrGLSLVertToFrag   fInnerShapeBloatedHalfSize;
+    GrGLSLVertToFrag   fInnerEllipseCoords;
+    GrGLSLVertToFrag   fInnerEllipseName;
+    bool               fShapeIsCircle;
+    bool               fTweakAlphaForCoverage;
+
+    typedef Backend INHERITED;
+};
+
+void GLSLInstanceProcessor::BackendCoverage::onInit(GrGLSLVaryingHandler* varyingHandler,
+                                                    GrGLSLVertexBuilder* v) {
+    v->codeAppend ("mat2 shapeTransposeMatrix = transpose(mat2(shapeMatrix));");
+    v->codeAppend ("vec2 shapeHalfSize = vec2(length(shapeTransposeMatrix[0]), "
+                                             "length(shapeTransposeMatrix[1]));");
+    v->codeAppend ("vec2 bloat = 0.5 / shapeHalfSize;");
+    v->codeAppendf("bloatedShapeCoords = %s * (1.0 + bloat);", fInputs.attr(Attrib::kShapeCoords));
+
+    if (kOval_ShapeFlag != fBatchInfo.fShapeTypes) {
+        if (fTweakAlphaForCoverage) {
+            varyingHandler->addVarying("colorTimesRectCoverage", &fColorTimesRectCoverage,
+                                       kLow_GrSLPrecision);
+            if (kRect_ShapeFlag == fBatchInfo.fShapeTypes) {
+                fColor = fColorTimesRectCoverage;
+            }
+        } else {
+            varyingHandler->addVarying("rectCoverage", &fRectCoverage, kLow_GrSLPrecision);
+        }
+        v->codeAppend("float rectCoverage = 0.0;");
+    }
+    if (kRect_ShapeFlag != fBatchInfo.fShapeTypes) {
+        varyingHandler->addFlatVarying("triangleIsArc", &fTriangleIsArc, kHigh_GrSLPrecision);
+        if (!fShapeIsCircle) {
+            varyingHandler->addVarying("ellipseCoords", &fEllipseCoords, kHigh_GrSLPrecision);
+            varyingHandler->addFlatVarying("ellipseName", &fEllipseName, kHigh_GrSLPrecision);
+        } else {
+            varyingHandler->addVarying("circleCoords", &fEllipseCoords, kMedium_GrSLPrecision);
+            varyingHandler->addFlatVarying("bloatedRadius", &fBloatedRadius, kMedium_GrSLPrecision);
+        }
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::setupRect(GrGLSLVertexBuilder* v) {
+    // Make the border one pixel wide. Inner vs outer is indicated by coordAttrs.
+    v->codeAppendf("vec2 rectBloat = (%s != 0) ? bloat : -bloat;",
+                   fInputs.attr(Attrib::kVertexAttrs));
+    // Here we use the absolute value, because when the rect is thinner than a pixel, this makes it
+    // mark the spot where pixel center is within half a pixel of the *opposite* edge. This,
+    // combined with the "maxCoverage" logic below gives us mathematically correct coverage even for
+    // subpixel rectangles.
+    v->codeAppendf("bloatedShapeCoords = %s * abs(vec2(1.0 + rectBloat));",
+                   fInputs.attr(Attrib::kShapeCoords));
+
+    // Determine coverage at the vertex. Coverage naturally ramps from 0 to 1 unless the rect is
+    // narrower than a pixel.
+    v->codeAppend ("float maxCoverage = 4.0 * min(0.5, shapeHalfSize.x) *"
+                                             "min(0.5, shapeHalfSize.y);");
+    v->codeAppendf("rectCoverage = (%s != 0) ? 0.0 : maxCoverage;",
+                   fInputs.attr(Attrib::kVertexAttrs));
+
+    if (fTriangleIsArc.vsOut()) {
+        v->codeAppendf("%s = 0;", fTriangleIsArc.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::setupOval(GrGLSLVertexBuilder* v) {
+    // Offset the inner and outer octagons by one pixel. Inner vs outer is indicated by coordAttrs.
+    v->codeAppendf("vec2 ovalBloat = (%s != 0) ? bloat : -bloat;",
+                   fInputs.attr(Attrib::kVertexAttrs));
+    v->codeAppendf("bloatedShapeCoords = %s * max(vec2(1.0 + ovalBloat), vec2(0));",
+                   fInputs.attr(Attrib::kShapeCoords));
+    v->codeAppendf("%s = bloatedShapeCoords * shapeHalfSize;", fEllipseCoords.vsOut());
+    if (fEllipseName.vsOut()) {
+        v->codeAppendf("%s = 1.0 / (shapeHalfSize * shapeHalfSize);", fEllipseName.vsOut());
+    }
+    if (fBloatedRadius.vsOut()) {
+        SkASSERT(fShapeIsCircle);
+        v->codeAppendf("%s = shapeHalfSize.x + 0.5;", fBloatedRadius.vsOut());
+    }
+    if (fTriangleIsArc.vsOut()) {
+        v->codeAppendf("%s = int(%s != 0);",
+                       fTriangleIsArc.vsOut(), fInputs.attr(Attrib::kVertexAttrs));
+    }
+    if (fColorTimesRectCoverage.vsOut() || fRectCoverage.vsOut()) {
+        v->codeAppendf("rectCoverage = 1.0;");
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::adjustRRectVertices(GrGLSLVertexBuilder* v) {
+    // We try to let the AA borders line up with the arc edges on their particular side, but we
+    // can't allow them to get closer than one half pixel to the edge or they might overlap with
+    // their neighboring border.
+    v->codeAppend("vec2 innerEdge = max(1.0 - bloat, vec2(0));");
+    v->codeAppend ("vec2 borderEdge = cornerSign * clamp(1.0 - radii, -innerEdge, innerEdge);");
+    // 0.5 is a special value that indicates this vertex is an arc edge.
+    v->codeAppendf("if (abs(%s.x) == 0.5)"
+                       "bloatedShapeCoords.x = borderEdge.x;", fInputs.attr(Attrib::kShapeCoords));
+    v->codeAppendf("if (abs(%s.y) == 0.5)"
+                       "bloatedShapeCoords.y = borderEdge.y;", fInputs.attr(Attrib::kShapeCoords));
+
+    // Adjust the interior border vertices to make the border one pixel wide. 0.75 is a special
+    // value to indicate these points.
+    v->codeAppendf("if (abs(%s.x) == 0.75) "
+                       "bloatedShapeCoords.x = cornerSign.x * innerEdge.x;",
+                       fInputs.attr(Attrib::kShapeCoords));
+    v->codeAppendf("if (abs(%s.y) == 0.75) "
+                       "bloatedShapeCoords.y = cornerSign.y * innerEdge.y;",
+                       fInputs.attr(Attrib::kShapeCoords));
+}
+
+void GLSLInstanceProcessor::BackendCoverage::onSetupRRect(GrGLSLVertexBuilder* v) {
+    // The geometry is laid out in such a way that rectCoverage will be 0 and 1 on the vertices, but
+    // we still need to recompute this value because when the rrect gets thinner than one pixel, the
+    // interior edge of the border will necessarily clamp, and we need to match the AA behavior of
+    // the arc segments (i.e. distance from bloated edge only; ignoring the fact that the pixel
+    // actully has less coverage because it's not completely inside the opposite edge.)
+    v->codeAppend("vec2 d = shapeHalfSize + 0.5 - abs(bloatedShapeCoords) * shapeHalfSize;");
+    v->codeAppend("rectCoverage = min(d.x, d.y);");
+
+    SkASSERT(!fShapeIsCircle);
+    // The AA border does not get closer than one half pixel to the edge of the rect, so to get a
+    // smooth transition from flat edge to arc, we don't allow the radii to be smaller than one half
+    // pixel. (We don't worry about the transition on the opposite side when a radius is so large
+    // that the border clamped on that side.)
+    v->codeAppendf("vec2 clampedRadii = max(radii, bloat);");
+    v->codeAppendf("%s = (cornerSign * bloatedShapeCoords + clampedRadii - vec2(1)) * "
+                        "shapeHalfSize;", fEllipseCoords.vsOut());
+    v->codeAppendf("%s = 1.0 / (clampedRadii * clampedRadii * shapeHalfSize * shapeHalfSize);",
+                   fEllipseName.vsOut());
+}
+
+void GLSLInstanceProcessor::BackendCoverage::onInitInnerShape(GrGLSLVaryingHandler* varyingHandler,
+                                                              GrGLSLVertexBuilder* v) {
+    v->codeAppend("vec2 innerShapeHalfSize = shapeHalfSize / outer2Inner.xy;");
+
+    if (kOval_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+        varyingHandler->addVarying("innerEllipseCoords", &fInnerEllipseCoords,
+                                   kMedium_GrSLPrecision);
+        varyingHandler->addFlatVarying("innerEllipseName", &fInnerEllipseName,
+                                       kMedium_GrSLPrecision);
+    } else {
+        varyingHandler->addVarying("distanceToInnerEdge", &fDistanceToInnerEdge,
+                                   kMedium_GrSLPrecision);
+        varyingHandler->addFlatVarying("innerShapeBloatedHalfSize", &fInnerShapeBloatedHalfSize,
+                                       kMedium_GrSLPrecision);
+        if (kRect_ShapeFlag != fBatchInfo.fInnerShapeTypes) {
+            varyingHandler->addVarying("innerShapeCoords", &fInnerShapeCoords, kHigh_GrSLPrecision);
+            varyingHandler->addFlatVarying("innerEllipseName", &fInnerEllipseName,
+                                           kMedium_GrSLPrecision);
+            varyingHandler->addFlatVarying("innerRRect", &fInnerRRect, kHigh_GrSLPrecision);
+        }
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::setupInnerRect(GrGLSLVertexBuilder* v) {
+    if (fInnerRRect.vsOut()) {
+        // The fragment shader will generalize every inner shape as a round rect. Since this one
+        // is a rect, we simply emit bogus parameters for the round rect (effectively negative
+        // radii) that ensure the fragment shader always takes the "emitRect" codepath.
+        v->codeAppendf("%s.xy = abs(outer2Inner.xy) * (1.0 + bloat) + abs(outer2Inner.zw);",
+                       fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::setupInnerOval(GrGLSLVertexBuilder* v) {
+    v->codeAppendf("%s = 1.0 / (innerShapeHalfSize * innerShapeHalfSize);",
+                   fInnerEllipseName.vsOut());
+    if (fInnerEllipseCoords.vsOut()) {
+        v->codeAppendf("%s = innerShapeCoords * innerShapeHalfSize;", fInnerEllipseCoords.vsOut());
+    }
+    if (fInnerRRect.vsOut()) {
+        v->codeAppendf("%s = vec4(0, 0, innerShapeHalfSize);", fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::onSetupInnerRRect(GrGLSLVertexBuilder* v) {
+    // The distance to ellipse formula doesn't work well when the radii are less than half a pixel.
+    v->codeAppend ("innerRadii = max(innerRadii, bloat);");
+    v->codeAppendf("%s = 1.0 / (innerRadii * innerRadii * innerShapeHalfSize * "
+                               "innerShapeHalfSize);",
+                   fInnerEllipseName.vsOut());
+    v->codeAppendf("%s = vec4(1.0 - innerRadii, innerShapeHalfSize);", fInnerRRect.vsOut());
+}
+
+void GLSLInstanceProcessor::BackendCoverage::onEmitCode(GrGLSLVertexBuilder* v,
+                                                        GrGLSLPPFragmentBuilder* f,
+                                                        const char* outCoverage,
+                                                        const char* outColor) {
+    if (fColorTimesRectCoverage.vsOut()) {
+        SkASSERT(!fRectCoverage.vsOut());
+        v->codeAppendf("%s = %s * rectCoverage;",
+                       fColorTimesRectCoverage.vsOut(), fInputs.attr(Attrib::kColor));
+    }
+    if (fRectCoverage.vsOut()) {
+        SkASSERT(!fColorTimesRectCoverage.vsOut());
+        v->codeAppendf("%s = rectCoverage;", fRectCoverage.vsOut());
+    }
+
+    SkString coverage("float coverage");
+    if (f->getProgramBuilder()->glslCaps()->usesPrecisionModifiers()) {
+        coverage.prependf("lowp ");
+    }
+    if (fBatchInfo.fInnerShapeTypes || (!fTweakAlphaForCoverage && fTriangleIsArc.fsIn())) {
+        f->codeAppendf("%s;", coverage.c_str());
+        coverage = "coverage";
+    }
+    if (fTriangleIsArc.fsIn()) {
+        f->codeAppendf("if (%s == 0) {", fTriangleIsArc.fsIn());
+        this->emitRect(f, coverage.c_str(), outColor);
+        f->codeAppend ("} else {");
+        if (fShapeIsCircle) {
+            this->emitCircle(f, coverage.c_str());
+        } else {
+            bool ellipseCoordsMayBeNegative = SkToBool(fBatchInfo.fShapeTypes & kOval_ShapeFlag);
+            this->emitArc(f, fEllipseCoords.fsIn(), fEllipseName.fsIn(),
+                          true /*ellipseCoordsNeedClamp*/, ellipseCoordsMayBeNegative,
+                          coverage.c_str());
+        }
+        if (fTweakAlphaForCoverage) {
+            f->codeAppendf("%s = %s * coverage;", outColor, fColor.fsIn());
+        }
+        f->codeAppend ("}");
+    } else {
+        this->emitRect(f, coverage.c_str(), outColor);
+    }
+
+    if (fBatchInfo.fInnerShapeTypes) {
+        f->codeAppendf("// Inner shape.\n");
+        SkString innerCoverageDecl("float innerCoverage");
+        if (f->getProgramBuilder()->glslCaps()->usesPrecisionModifiers()) {
+            innerCoverageDecl.prependf("lowp ");
+        }
+        if (kOval_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+            this->emitArc(f, fInnerEllipseCoords.fsIn(), fInnerEllipseName.fsIn(),
+                          true /*ellipseCoordsNeedClamp*/, true /*ellipseCoordsMayBeNegative*/,
+                          innerCoverageDecl.c_str());
+        } else {
+            v->codeAppendf("%s = innerShapeCoords * innerShapeHalfSize;",
+                           fDistanceToInnerEdge.vsOut());
+            v->codeAppendf("%s = innerShapeHalfSize + 0.5;", fInnerShapeBloatedHalfSize.vsOut());
+
+            if (kRect_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+                this->emitInnerRect(f, innerCoverageDecl.c_str());
+            } else {
+                f->codeAppendf("%s = 0.0;", innerCoverageDecl.c_str());
+                f->codeAppendf("vec2 distanceToArcEdge = abs(%s) - %s.xy;",
+                               fInnerShapeCoords.fsIn(), fInnerRRect.fsIn());
+                f->codeAppend ("if (any(lessThan(distanceToArcEdge, vec2(1e-5)))) {");
+                this->emitInnerRect(f, "innerCoverage");
+                f->codeAppend ("} else {");
+                f->codeAppendf(    "vec2 ellipseCoords = distanceToArcEdge * %s.zw;",
+                                   fInnerRRect.fsIn());
+                this->emitArc(f, "ellipseCoords", fInnerEllipseName.fsIn(),
+                              false /*ellipseCoordsNeedClamp*/,
+                              false /*ellipseCoordsMayBeNegative*/, "innerCoverage");
+                f->codeAppend ("}");
+            }
+        }
+        f->codeAppendf("%s = vec4(max(coverage - innerCoverage, 0.0));", outCoverage);
+    } else if (!fTweakAlphaForCoverage) {
+        f->codeAppendf("%s = vec4(coverage);", outCoverage);
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::emitRect(GrGLSLPPFragmentBuilder* f,
+                                                      const char* outCoverage,
+                                                      const char* outColor) {
+    if (fColorTimesRectCoverage.fsIn()) {
+        f->codeAppendf("%s = %s;", outColor, fColorTimesRectCoverage.fsIn());
+    } else if (fTweakAlphaForCoverage) {
+        // We are drawing just ovals. The interior rect always has 100% coverage.
+        f->codeAppendf("%s = %s;", outColor, fColor.fsIn());
+    } else if (fRectCoverage.fsIn()) {
+        f->codeAppendf("%s = %s;", outCoverage, fRectCoverage.fsIn());
+    } else {
+        f->codeAppendf("%s = 1.0;", outCoverage);
+    }
+}
+
+void GLSLInstanceProcessor::BackendCoverage::emitCircle(GrGLSLPPFragmentBuilder* f,
+                                                        const char* outCoverage) {
+    // TODO: circleCoords = max(circleCoords, 0) if we decide to do this optimization on rrects.
+    SkASSERT(!(kRRect_ShapesMask & fBatchInfo.fShapeTypes));
+    f->codeAppendf("float distanceToEdge = %s - length(%s);",
+                   fBloatedRadius.fsIn(), fEllipseCoords.fsIn());
+    f->codeAppendf("%s = clamp(distanceToEdge, 0.0, 1.0);", outCoverage);
+}
+
+void GLSLInstanceProcessor::BackendCoverage::emitArc(GrGLSLPPFragmentBuilder* f,
+                                                     const char* ellipseCoords,
+                                                     const char* ellipseName,
+                                                     bool ellipseCoordsNeedClamp,
+                                                     bool ellipseCoordsMayBeNegative,
+                                                     const char* outCoverage) {
+    SkASSERT(!ellipseCoordsMayBeNegative || ellipseCoordsNeedClamp);
+    if (ellipseCoordsNeedClamp) {
+        // This serves two purposes:
+        //  - To restrict the arcs of rounded rects to their positive quadrants.
+        //  - To avoid inversesqrt(0) in the ellipse formula.
+        if (ellipseCoordsMayBeNegative) {
+            f->codeAppendf("vec2 ellipseClampedCoords = max(abs(%s), vec2(1e-4));", ellipseCoords);
+        } else {
+            f->codeAppendf("vec2 ellipseClampedCoords = max(%s, vec2(1e-4));", ellipseCoords);
+        }
+        ellipseCoords = "ellipseClampedCoords";
+    }
+    // ellipseCoords are in pixel space and ellipseName is 1 / rx^2, 1 / ry^2.
+    f->codeAppendf("vec2 Z = %s * %s;", ellipseCoords, ellipseName);
+    // implicit is the evaluation of (x/rx)^2 + (y/ry)^2 - 1.
+    f->codeAppendf("float implicit = dot(Z, %s) - 1.0;", ellipseCoords);
+    // gradDot is the squared length of the gradient of the implicit.
+    f->codeAppendf("float gradDot = 4.0 * dot(Z, Z);");
+    f->appendPrecisionModifier(kLow_GrSLPrecision);
+    f->codeAppend ("float approxDist = implicit * inversesqrt(gradDot);");
+    f->codeAppendf("%s = clamp(0.5 - approxDist, 0.0, 1.0);", outCoverage);
+}
+
+void GLSLInstanceProcessor::BackendCoverage::emitInnerRect(GrGLSLPPFragmentBuilder* f,
+                                                           const char* outCoverage) {
+    f->appendPrecisionModifier(kLow_GrSLPrecision);
+    f->codeAppendf("vec2 c = %s - abs(%s);",
+                   fInnerShapeBloatedHalfSize.fsIn(), fDistanceToInnerEdge.fsIn());
+    f->codeAppendf("%s = clamp(min(c.x, c.y), 0.0, 1.0);", outCoverage);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class GLSLInstanceProcessor::BackendMultisample : public Backend {
+public:
+    BackendMultisample(BatchInfo batchInfo, const VertexInputs& inputs, int effectiveSampleCnt)
+        : INHERITED(batchInfo, inputs),
+          fEffectiveSampleCnt(effectiveSampleCnt),
+          fShapeCoords(kVec2f_GrSLType),
+          fShapeInverseMatrix(kMat22f_GrSLType),
+          fFragShapeHalfSpan(kVec2f_GrSLType),
+          fArcTest(kVec2f_GrSLType),
+          fArcInverseMatrix(kMat22f_GrSLType),
+          fFragArcHalfSpan(kVec2f_GrSLType),
+          fEarlyAccept(kInt_GrSLType),
+          fInnerShapeInverseMatrix(kMat22f_GrSLType),
+          fFragInnerShapeHalfSpan(kVec2f_GrSLType) {
+        fRectTrianglesMaySplit = fBatchInfo.fHasPerspective;
+        fNeedsNeighborRadii = this->isMixedSampled() && !fBatchInfo.fHasPerspective;
+    }
+
+private:
+    bool isMixedSampled() const { return AntialiasMode::kMixedSamples == fBatchInfo.fAntialiasMode; }
+
+    void onInit(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupRect(GrGLSLVertexBuilder*) override;
+    void setupOval(GrGLSLVertexBuilder*) override;
+    void adjustRRectVertices(GrGLSLVertexBuilder*) override;
+    void onSetupRRect(GrGLSLVertexBuilder*) override;
+
+    void onInitInnerShape(GrGLSLVaryingHandler*, GrGLSLVertexBuilder*) override;
+    void setupInnerRect(GrGLSLVertexBuilder*) override;
+    void setupInnerOval(GrGLSLVertexBuilder*) override;
+    void onSetupInnerRRect(GrGLSLVertexBuilder*) override;
+
+    void onEmitCode(GrGLSLVertexBuilder*, GrGLSLPPFragmentBuilder*, const char*,
+                    const char*) override;
+
+    struct EmitShapeCoords {
+        const GrGLSLVarying*   fVarying;
+        const char*            fInverseMatrix;
+        const char*            fFragHalfSpan;
+    };
+
+    struct EmitShapeOpts {
+        bool fIsTightGeometry;
+        bool fResolveMixedSamples;
+        bool fInvertCoverage;
+    };
+
+    void emitRect(GrGLSLPPFragmentBuilder*, const EmitShapeCoords&, const EmitShapeOpts&);
+    void emitArc(GrGLSLPPFragmentBuilder*, const EmitShapeCoords&, bool coordsMayBeNegative,
+                 bool clampCoords, const EmitShapeOpts&);
+    void emitSimpleRRect(GrGLSLPPFragmentBuilder*, const EmitShapeCoords&, const char* rrect,
+                         const EmitShapeOpts&);
+    void interpolateAtSample(GrGLSLPPFragmentBuilder*, const GrGLSLVarying&, const char* sampleIdx,
+                             const char* interpolationMatrix);
+    void acceptOrRejectWholeFragment(GrGLSLPPFragmentBuilder*, bool inside, const EmitShapeOpts&);
+    void acceptCoverageMask(GrGLSLPPFragmentBuilder*, const char* shapeMask, const EmitShapeOpts&,
+                            bool maybeSharedEdge = true);
+
+    int                fEffectiveSampleCnt;
+    bool               fRectTrianglesMaySplit;
+    GrGLSLVertToFrag   fShapeCoords;
+    GrGLSLVertToFrag   fShapeInverseMatrix;
+    GrGLSLVertToFrag   fFragShapeHalfSpan;
+    GrGLSLVertToFrag   fArcTest;
+    GrGLSLVertToFrag   fArcInverseMatrix;
+    GrGLSLVertToFrag   fFragArcHalfSpan;
+    GrGLSLVertToFrag   fEarlyAccept;
+    GrGLSLVertToFrag   fInnerShapeInverseMatrix;
+    GrGLSLVertToFrag   fFragInnerShapeHalfSpan;
+    SkString           fSquareFun;
+
+    typedef Backend INHERITED;
+};
+
+void GLSLInstanceProcessor::BackendMultisample::onInit(GrGLSLVaryingHandler* varyingHandler,
+                                                       GrGLSLVertexBuilder* v) {
+    if (!this->isMixedSampled()) {
+        if (kRect_ShapeFlag != fBatchInfo.fShapeTypes) {
+            varyingHandler->addFlatVarying("triangleIsArc", &fTriangleIsArc,
+                                           kHigh_GrSLPrecision);
+            varyingHandler->addVarying("arcCoords", &fArcCoords, kHigh_GrSLPrecision);
+            if (!fBatchInfo.fHasPerspective) {
+                varyingHandler->addFlatVarying("arcInverseMatrix", &fArcInverseMatrix,
+                                               kHigh_GrSLPrecision);
+                varyingHandler->addFlatVarying("fragArcHalfSpan", &fFragArcHalfSpan,
+                                               kHigh_GrSLPrecision);
+            }
+        } else if (!fBatchInfo.fInnerShapeTypes) {
+            return;
+        }
+    } else {
+        varyingHandler->addVarying("shapeCoords", &fShapeCoords, kHigh_GrSLPrecision);
+        if (!fBatchInfo.fHasPerspective) {
+            varyingHandler->addFlatVarying("shapeInverseMatrix", &fShapeInverseMatrix,
+                                           kHigh_GrSLPrecision);
+            varyingHandler->addFlatVarying("fragShapeHalfSpan", &fFragShapeHalfSpan,
+                                           kHigh_GrSLPrecision);
+        }
+        if (fBatchInfo.fShapeTypes & kRRect_ShapesMask) {
+            varyingHandler->addVarying("arcCoords", &fArcCoords, kHigh_GrSLPrecision);
+            varyingHandler->addVarying("arcTest", &fArcTest, kHigh_GrSLPrecision);
+            if (!fBatchInfo.fHasPerspective) {
+                varyingHandler->addFlatVarying("arcInverseMatrix", &fArcInverseMatrix,
+                                               kHigh_GrSLPrecision);
+                varyingHandler->addFlatVarying("fragArcHalfSpan", &fFragArcHalfSpan,
+                                               kHigh_GrSLPrecision);
+            }
+        } else if (fBatchInfo.fShapeTypes & kOval_ShapeFlag) {
+            fArcCoords = fShapeCoords;
+            fArcInverseMatrix = fShapeInverseMatrix;
+            fFragArcHalfSpan = fFragShapeHalfSpan;
+            if (fBatchInfo.fShapeTypes & kRect_ShapeFlag) {
+                varyingHandler->addFlatVarying("triangleIsArc", &fTriangleIsArc,
+                                               kHigh_GrSLPrecision);
+            }
+        }
+        if (kRect_ShapeFlag != fBatchInfo.fShapeTypes) {
+           v->definef("SAMPLE_MASK_ALL", "0x%x", (1 << fEffectiveSampleCnt) - 1);
+           varyingHandler->addFlatVarying("earlyAccept", &fEarlyAccept, kHigh_GrSLPrecision);
+        }
+    }
+    if (!fBatchInfo.fHasPerspective) {
+        v->codeAppend("mat2 shapeInverseMatrix = inverse(mat2(shapeMatrix));");
+        v->codeAppend("vec2 fragShapeSpan = abs(vec4(shapeInverseMatrix).xz) + "
+                                           "abs(vec4(shapeInverseMatrix).yw);");
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::setupRect(GrGLSLVertexBuilder* v) {
+    if (fShapeCoords.vsOut()) {
+        v->codeAppendf("%s = %s;", fShapeCoords.vsOut(), this->outShapeCoords());
+    }
+    if (fShapeInverseMatrix.vsOut()) {
+        v->codeAppendf("%s = shapeInverseMatrix;", fShapeInverseMatrix.vsOut());
+    }
+    if (fFragShapeHalfSpan.vsOut()) {
+        v->codeAppendf("%s = 0.5 * fragShapeSpan;", fFragShapeHalfSpan.vsOut());
+    }
+    if (fArcTest.vsOut()) {
+        // Pick a value that is not > 0.
+        v->codeAppendf("%s = vec2(0);", fArcTest.vsOut());
+    }
+    if (fTriangleIsArc.vsOut()) {
+        v->codeAppendf("%s = 0;", fTriangleIsArc.vsOut());
+    }
+    if (fEarlyAccept.vsOut()) {
+        v->codeAppendf("%s = SAMPLE_MASK_ALL;", fEarlyAccept.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::setupOval(GrGLSLVertexBuilder* v) {
+    v->codeAppendf("%s = abs(%s);", fArcCoords.vsOut(), this->outShapeCoords());
+    if (fArcInverseMatrix.vsOut()) {
+        v->codeAppendf("vec2 s = sign(%s);", this->outShapeCoords());
+        v->codeAppendf("%s = shapeInverseMatrix * mat2(s.x, 0, 0 , s.y);",
+                       fArcInverseMatrix.vsOut());
+    }
+    if (fFragArcHalfSpan.vsOut()) {
+        v->codeAppendf("%s = 0.5 * fragShapeSpan;", fFragArcHalfSpan.vsOut());
+    }
+    if (fArcTest.vsOut()) {
+        // Pick a value that is > 0.
+        v->codeAppendf("%s = vec2(1);", fArcTest.vsOut());
+    }
+    if (fTriangleIsArc.vsOut()) {
+        if (!this->isMixedSampled()) {
+            v->codeAppendf("%s = %s & 1;",
+                           fTriangleIsArc.vsOut(), fInputs.attr(Attrib::kVertexAttrs));
+        } else {
+            v->codeAppendf("%s = 1;", fTriangleIsArc.vsOut());
+        }
+    }
+    if (fEarlyAccept.vsOut()) {
+        v->codeAppendf("%s = ~%s & SAMPLE_MASK_ALL;",
+                       fEarlyAccept.vsOut(), fInputs.attr(Attrib::kVertexAttrs));
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::adjustRRectVertices(GrGLSLVertexBuilder* v) {
+    if (!this->isMixedSampled()) {
+        INHERITED::adjustRRectVertices(v);
+        return;
+    }
+
+    if (!fBatchInfo.fHasPerspective) {
+        // For the mixed samples algorithm it's best to bloat the corner triangles a bit so that
+        // more of the pixels that cross into the arc region are completely inside the shared edges.
+        // We also snap to a regular rect if the radii shrink smaller than a pixel.
+        v->codeAppend ("vec2 midpt = 0.5 * (neighborRadii - radii);");
+        v->codeAppend ("vec2 cornerSize = any(lessThan(radii, fragShapeSpan)) ? "
+                           "vec2(0) : min(radii + 0.5 * fragShapeSpan, 1.0 - midpt);");
+    } else {
+        // TODO: We could still bloat the corner triangle in the perspective case; we would just
+        // need to find the screen-space derivative of shape coords at this particular point.
+        v->codeAppend ("vec2 cornerSize = any(lessThan(radii, vec2(1e-3))) ? vec2(0) : radii;");
+    }
+
+    v->codeAppendf("if (abs(%s.x) == 0.5)"
+                       "%s.x = cornerSign.x * (1.0 - cornerSize.x);",
+                       fInputs.attr(Attrib::kShapeCoords), fModifiedShapeCoords);
+    v->codeAppendf("if (abs(%s.y) == 0.5)"
+                       "%s.y = cornerSign.y * (1.0 - cornerSize.y);",
+                       fInputs.attr(Attrib::kShapeCoords), fModifiedShapeCoords);
+}
+
+void GLSLInstanceProcessor::BackendMultisample::onSetupRRect(GrGLSLVertexBuilder* v) {
+    if (fShapeCoords.vsOut()) {
+        v->codeAppendf("%s = %s;", fShapeCoords.vsOut(), this->outShapeCoords());
+    }
+    if (fShapeInverseMatrix.vsOut()) {
+        v->codeAppendf("%s = shapeInverseMatrix;", fShapeInverseMatrix.vsOut());
+    }
+    if (fFragShapeHalfSpan.vsOut()) {
+        v->codeAppendf("%s = 0.5 * fragShapeSpan;", fFragShapeHalfSpan.vsOut());
+    }
+    if (fArcInverseMatrix.vsOut()) {
+        v->codeAppend ("vec2 s = cornerSign / radii;");
+        v->codeAppendf("%s = shapeInverseMatrix * mat2(s.x, 0, 0, s.y);",
+                       fArcInverseMatrix.vsOut());
+    }
+    if (fFragArcHalfSpan.vsOut()) {
+        v->codeAppendf("%s = 0.5 * (abs(vec4(%s).xz) + abs(vec4(%s).yw));",
+                       fFragArcHalfSpan.vsOut(), fArcInverseMatrix.vsOut(),
+                       fArcInverseMatrix.vsOut());
+    }
+    if (fArcTest.vsOut()) {
+        // The interior triangles are laid out as a fan. fArcTest is both distances from shared
+        // edges of a fan triangle to a point within that triangle. fArcTest is used to check if a
+        // fragment is too close to either shared edge, in which case we point sample the shape as a
+        // rect at that point in order to guarantee the mixed samples discard logic works correctly.
+        v->codeAppendf("%s = (cornerSize == vec2(0)) ? vec2(0) : "
+                       "cornerSign * %s * mat2(1, cornerSize.x - 1.0, cornerSize.y - 1.0, 1);",
+                       fArcTest.vsOut(), fModifiedShapeCoords);
+        if (!fBatchInfo.fHasPerspective) {
+            // Shift the point at which distances to edges are measured from the center of the pixel
+            // to the corner. This way the sign of fArcTest will quickly tell us whether a pixel
+            // is completely inside the shared edge. Perspective mode will accomplish this same task
+            // by finding the derivatives in the fragment shader.
+            v->codeAppendf("%s -= 0.5 * (fragShapeSpan.yx * abs(radii - 1.0) + fragShapeSpan);",
+                           fArcTest.vsOut());
+        }
+    }
+    if (fEarlyAccept.vsOut()) {
+        SkASSERT(this->isMixedSampled());
+        v->codeAppendf("%s = all(equal(vec2(1), abs(%s))) ? 0 : SAMPLE_MASK_ALL;",
+                       fEarlyAccept.vsOut(), fInputs.attr(Attrib::kShapeCoords));
+    }
+}
+
+void
+GLSLInstanceProcessor::BackendMultisample::onInitInnerShape(GrGLSLVaryingHandler* varyingHandler,
+                                                            GrGLSLVertexBuilder* v) {
+    varyingHandler->addVarying("innerShapeCoords", &fInnerShapeCoords, kHigh_GrSLPrecision);
+    if (kOval_ShapeFlag != fBatchInfo.fInnerShapeTypes &&
+        kRect_ShapeFlag != fBatchInfo.fInnerShapeTypes) {
+        varyingHandler->addFlatVarying("innerRRect", &fInnerRRect, kHigh_GrSLPrecision);
+    }
+    if (!fBatchInfo.fHasPerspective) {
+        varyingHandler->addFlatVarying("innerShapeInverseMatrix", &fInnerShapeInverseMatrix,
+                                       kHigh_GrSLPrecision);
+        v->codeAppendf("%s = shapeInverseMatrix * mat2(outer2Inner.x, 0, 0, outer2Inner.y);",
+                       fInnerShapeInverseMatrix.vsOut());
+        varyingHandler->addFlatVarying("fragInnerShapeHalfSpan", &fFragInnerShapeHalfSpan,
+                                       kHigh_GrSLPrecision);
+        v->codeAppendf("%s = 0.5 * fragShapeSpan * outer2Inner.xy;",
+                       fFragInnerShapeHalfSpan.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::setupInnerRect(GrGLSLVertexBuilder* v) {
+    if (fInnerRRect.vsOut()) {
+        // The fragment shader will generalize every inner shape as a round rect. Since this one
+        // is a rect, we simply emit bogus parameters for the round rect (negative radii) that
+        // ensure the fragment shader always takes the "sample as rect" codepath.
+        v->codeAppendf("%s = vec4(2.0 * (inner.zw - inner.xy) / (outer.zw - outer.xy), vec2(0));",
+                       fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::setupInnerOval(GrGLSLVertexBuilder* v) {
+    if (fInnerRRect.vsOut()) {
+        v->codeAppendf("%s = vec4(0, 0, 1, 1);", fInnerRRect.vsOut());
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::onSetupInnerRRect(GrGLSLVertexBuilder* v) {
+    // Avoid numeric instability by not allowing the inner radii to get smaller than 1/10th pixel.
+    if (fFragInnerShapeHalfSpan.vsOut()) {
+        v->codeAppendf("innerRadii = max(innerRadii, 2e-1 * %s);", fFragInnerShapeHalfSpan.vsOut());
+    } else {
+        v->codeAppend ("innerRadii = max(innerRadii, vec2(1e-4));");
+    }
+    v->codeAppendf("%s = vec4(1.0 - innerRadii, 1.0 / innerRadii);", fInnerRRect.vsOut());
+}
+
+void GLSLInstanceProcessor::BackendMultisample::onEmitCode(GrGLSLVertexBuilder*,
+                                                           GrGLSLPPFragmentBuilder* f,
+                                                           const char*, const char*) {
+    f->define("SAMPLE_COUNT", fEffectiveSampleCnt);
+    if (this->isMixedSampled()) {
+        f->definef("SAMPLE_MASK_ALL", "0x%x", (1 << fEffectiveSampleCnt) - 1);
+        f->definef("SAMPLE_MASK_MSB", "0x%x", 1 << (fEffectiveSampleCnt - 1));
+    }
+
+    if (kRect_ShapeFlag != (fBatchInfo.fShapeTypes | fBatchInfo.fInnerShapeTypes)) {
+        GrGLSLShaderVar x("x", kVec2f_GrSLType, GrGLSLShaderVar::kNonArray, kHigh_GrSLPrecision);
+        f->emitFunction(kFloat_GrSLType, "square", 1, &x, "return dot(x, x);", &fSquareFun);
+    }
+
+    EmitShapeCoords shapeCoords;
+    shapeCoords.fVarying = &fShapeCoords;
+    shapeCoords.fInverseMatrix = fShapeInverseMatrix.fsIn();
+    shapeCoords.fFragHalfSpan = fFragShapeHalfSpan.fsIn();
+
+    EmitShapeCoords arcCoords;
+    arcCoords.fVarying = &fArcCoords;
+    arcCoords.fInverseMatrix = fArcInverseMatrix.fsIn();
+    arcCoords.fFragHalfSpan = fFragArcHalfSpan.fsIn();
+    bool clampArcCoords = this->isMixedSampled() && (fBatchInfo.fShapeTypes & kRRect_ShapesMask);
+
+    EmitShapeOpts opts;
+    opts.fIsTightGeometry = true;
+    opts.fResolveMixedSamples = this->isMixedSampled();
+    opts.fInvertCoverage = false;
+
+    if (fBatchInfo.fHasPerspective && fBatchInfo.fInnerShapeTypes) {
+        // This determines if the fragment should consider the inner shape in its sample mask.
+        // We take the derivative early in case discards may occur before we get to the inner shape.
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf("vec2 fragInnerShapeApproxHalfSpan = 0.5 * fwidth(%s);",
+                       fInnerShapeCoords.fsIn());
+    }
+
+    if (!this->isMixedSampled()) {
+        SkASSERT(!fArcTest.fsIn());
+        if (fTriangleIsArc.fsIn()) {
+            f->codeAppendf("if (%s != 0) {", fTriangleIsArc.fsIn());
+            this->emitArc(f, arcCoords, false, clampArcCoords, opts);
+
+            f->codeAppend ("}");
+        }
+    } else {
+        const char* arcTest = fArcTest.fsIn();
+        SkASSERT(arcTest);
+        if (fBatchInfo.fHasPerspective) {
+            // The non-perspective version accounts for fwith() in the vertex shader.
+            // We make sure to take the derivative here, before a neighbor pixel may early accept.
+            f->enableFeature(GrGLSLPPFragmentBuilder::kStandardDerivatives_GLSLFeature);
+            f->appendPrecisionModifier(kHigh_GrSLPrecision);
+            f->codeAppendf("vec2 arcTest = %s - 0.5 * fwidth(%s);",
+                           fArcTest.fsIn(), fArcTest.fsIn());
+            arcTest = "arcTest";
+        }
+        const char* earlyAccept = fEarlyAccept.fsIn() ? fEarlyAccept.fsIn() : "SAMPLE_MASK_ALL";
+        f->codeAppendf("if (gl_SampleMaskIn[0] == %s) {", earlyAccept);
+        f->overrideSampleCoverage(earlyAccept);
+        f->codeAppend ("} else {");
+        if (arcTest) {
+            // At this point, if the sample mask is all set it means we are inside an arc triangle.
+            f->codeAppendf("if (gl_SampleMaskIn[0] == SAMPLE_MASK_ALL || "
+                               "all(greaterThan(%s, vec2(0)))) {", arcTest);
+            this->emitArc(f, arcCoords, false, clampArcCoords, opts);
+            f->codeAppend ("} else {");
+            this->emitRect(f, shapeCoords, opts);
+            f->codeAppend ("}");
+        } else if (fTriangleIsArc.fsIn()) {
+            f->codeAppendf("if (%s == 0) {", fTriangleIsArc.fsIn());
+            this->emitRect(f, shapeCoords, opts);
+            f->codeAppend ("} else {");
+            this->emitArc(f, arcCoords, false, clampArcCoords, opts);
+            f->codeAppend ("}");
+        } else if (fBatchInfo.fShapeTypes == kOval_ShapeFlag) {
+            this->emitArc(f, arcCoords, false, clampArcCoords, opts);
+        } else {
+            SkASSERT(fBatchInfo.fShapeTypes == kRect_ShapeFlag);
+            this->emitRect(f, shapeCoords, opts);
+        }
+        f->codeAppend ("}");
+    }
+
+    if (fBatchInfo.fInnerShapeTypes) {
+        f->codeAppendf("// Inner shape.\n");
+
+        EmitShapeCoords innerShapeCoords;
+        innerShapeCoords.fVarying = &fInnerShapeCoords;
+        if (!fBatchInfo.fHasPerspective) {
+            innerShapeCoords.fInverseMatrix = fInnerShapeInverseMatrix.fsIn();
+            innerShapeCoords.fFragHalfSpan = fFragInnerShapeHalfSpan.fsIn();
+        }
+
+        EmitShapeOpts innerOpts;
+        innerOpts.fIsTightGeometry = false;
+        innerOpts.fResolveMixedSamples = false; // Mixed samples are resolved in the outer shape.
+        innerOpts.fInvertCoverage = true;
+
+        if (kOval_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+            this->emitArc(f, innerShapeCoords, true, false, innerOpts);
+        } else {
+            f->codeAppendf("if (all(lessThan(abs(%s), 1.0 + %s))) {", fInnerShapeCoords.fsIn(),
+                           !fBatchInfo.fHasPerspective ? innerShapeCoords.fFragHalfSpan
+                                                       : "fragInnerShapeApproxHalfSpan"); // Above.
+            if (kRect_ShapeFlag == fBatchInfo.fInnerShapeTypes) {
+                this->emitRect(f, innerShapeCoords, innerOpts);
+            } else {
+                this->emitSimpleRRect(f, innerShapeCoords, fInnerRRect.fsIn(), innerOpts);
+            }
+            f->codeAppend ("}");
+        }
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::emitRect(GrGLSLPPFragmentBuilder* f,
+                                                         const EmitShapeCoords& coords,
+                                                         const EmitShapeOpts& opts) {
+    // Full MSAA doesn't need to do anything to draw a rect.
+    SkASSERT(!opts.fIsTightGeometry || opts.fResolveMixedSamples);
+    if (coords.fFragHalfSpan) {
+        f->codeAppendf("if (all(lessThanEqual(abs(%s), 1.0 - %s))) {",
+                       coords.fVarying->fsIn(), coords.fFragHalfSpan);
+        // The entire pixel is inside the rect.
+        this->acceptOrRejectWholeFragment(f, true, opts);
+        f->codeAppend ("} else ");
+        if (opts.fIsTightGeometry && !fRectTrianglesMaySplit) {
+            f->codeAppendf("if (any(lessThan(abs(%s), 1.0 - %s))) {",
+                           coords.fVarying->fsIn(), coords.fFragHalfSpan);
+            // The pixel falls on an edge of the rectangle and is known to not be on a shared edge.
+            this->acceptCoverageMask(f, "gl_SampleMaskIn[0]", opts, false);
+            f->codeAppend ("} else");
+        }
+        f->codeAppend ("{");
+    }
+    f->codeAppend ("int rectMask = 0;");
+    f->codeAppend ("for (int i = 0; i < SAMPLE_COUNT; i++) {");
+    f->appendPrecisionModifier(kHigh_GrSLPrecision);
+    f->codeAppend (    "vec2 pt = ");
+    this->interpolateAtSample(f, *coords.fVarying, "i", coords.fInverseMatrix);
+    f->codeAppend (    ";");
+    f->codeAppend (    "if (all(lessThan(abs(pt), vec2(1)))) rectMask |= (1 << i);");
+    f->codeAppend ("}");
+    this->acceptCoverageMask(f, "rectMask", opts);
+    if (coords.fFragHalfSpan) {
+        f->codeAppend ("}");
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::emitArc(GrGLSLPPFragmentBuilder* f,
+                                                        const EmitShapeCoords& coords,
+                                                        bool coordsMayBeNegative, bool clampCoords,
+                                                        const EmitShapeOpts& opts) {
+    if (coords.fFragHalfSpan) {
+        SkString absArcCoords;
+        absArcCoords.printf(coordsMayBeNegative ? "abs(%s)" : "%s", coords.fVarying->fsIn());
+        if (clampCoords) {
+            f->codeAppendf("if (%s(max(%s + %s, vec2(0))) < 1.0) {",
+                           fSquareFun.c_str(), absArcCoords.c_str(), coords.fFragHalfSpan);
+        } else {
+            f->codeAppendf("if (%s(%s + %s) < 1.0) {",
+                           fSquareFun.c_str(), absArcCoords.c_str(), coords.fFragHalfSpan);
+        }
+        // The entire pixel is inside the arc.
+        this->acceptOrRejectWholeFragment(f, true, opts);
+        f->codeAppendf("} else if (%s(max(%s - %s, vec2(0))) >= 1.0) {",
+                       fSquareFun.c_str(), absArcCoords.c_str(), coords.fFragHalfSpan);
+        // The entire pixel is outside the arc.
+        this->acceptOrRejectWholeFragment(f, false, opts);
+        f->codeAppend ("} else {");
+    }
+    f->codeAppend (    "int arcMask = 0;");
+    f->codeAppend (    "for (int i = 0; i < SAMPLE_COUNT; i++) {");
+    f->appendPrecisionModifier(kHigh_GrSLPrecision);
+    f->codeAppend (        "vec2 pt = ");
+    this->interpolateAtSample(f, *coords.fVarying, "i", coords.fInverseMatrix);
+    f->codeAppend (        ";");
+    if (clampCoords) {
+        SkASSERT(!coordsMayBeNegative);
+        f->codeAppend (    "pt = max(pt, vec2(0));");
+    }
+    f->codeAppendf(        "if (%s(pt) < 1.0) arcMask |= (1 << i);", fSquareFun.c_str());
+    f->codeAppend (    "}");
+    this->acceptCoverageMask(f, "arcMask", opts);
+    if (coords.fFragHalfSpan) {
+        f->codeAppend ("}");
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::emitSimpleRRect(GrGLSLPPFragmentBuilder* f,
+                                                                const EmitShapeCoords& coords,
+                                                                const char* rrect,
+                                                                const EmitShapeOpts& opts) {
+    f->appendPrecisionModifier(kHigh_GrSLPrecision);
+    f->codeAppendf("vec2 distanceToArcEdge = abs(%s) - %s.xy;", coords.fVarying->fsIn(), rrect);
+    f->codeAppend ("if (any(lessThan(distanceToArcEdge, vec2(0)))) {");
+    this->emitRect(f, coords, opts);
+    f->codeAppend ("} else {");
+    if (coords.fInverseMatrix && coords.fFragHalfSpan) {
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf("vec2 rrectCoords = distanceToArcEdge * %s.zw;", rrect);
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf("vec2 fragRRectHalfSpan = %s * %s.zw;", coords.fFragHalfSpan, rrect);
+        f->codeAppendf("if (%s(rrectCoords + fragRRectHalfSpan) <= 1.0) {", fSquareFun.c_str());
+        // The entire pixel is inside the round rect.
+        this->acceptOrRejectWholeFragment(f, true, opts);
+        f->codeAppendf("} else if (%s(max(rrectCoords - fragRRectHalfSpan, vec2(0))) >= 1.0) {",
+                       fSquareFun.c_str());
+        // The entire pixel is outside the round rect.
+        this->acceptOrRejectWholeFragment(f, false, opts);
+        f->codeAppend ("} else {");
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf(    "vec2 s = %s.zw * sign(%s);", rrect, coords.fVarying->fsIn());
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf(    "mat2 innerRRectInverseMatrix = %s * mat2(s.x, 0, 0, s.y);",
+                           coords.fInverseMatrix);
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppend (    "int rrectMask = 0;");
+        f->codeAppend (    "for (int i = 0; i < SAMPLE_COUNT; i++) {");
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppend (        "vec2 pt = rrectCoords + ");
+        f->appendOffsetToSample("i", GrGLSLFPFragmentBuilder::kSkiaDevice_Coordinates);
+        f->codeAppend (                  "* innerRRectInverseMatrix;");
+        f->codeAppendf(        "if (%s(max(pt, vec2(0))) < 1.0) rrectMask |= (1 << i);",
+                               fSquareFun.c_str());
+        f->codeAppend (    "}");
+        this->acceptCoverageMask(f, "rrectMask", opts);
+        f->codeAppend ("}");
+    } else {
+        f->codeAppend ("int rrectMask = 0;");
+        f->codeAppend ("for (int i = 0; i < SAMPLE_COUNT; i++) {");
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppend (    "vec2 shapePt = ");
+        this->interpolateAtSample(f, *coords.fVarying, "i", nullptr);
+        f->codeAppend (    ";");
+        f->appendPrecisionModifier(kHigh_GrSLPrecision);
+        f->codeAppendf(    "vec2 rrectPt = max(abs(shapePt) - %s.xy, vec2(0)) * %s.zw;",
+                           rrect, rrect);
+        f->codeAppendf(    "if (%s(rrectPt) < 1.0) rrectMask |= (1 << i);", fSquareFun.c_str());
+        f->codeAppend ("}");
+        this->acceptCoverageMask(f, "rrectMask", opts);
+    }
+    f->codeAppend ("}");
+}
+
+void GLSLInstanceProcessor::BackendMultisample::interpolateAtSample(GrGLSLPPFragmentBuilder* f,
+                                                                  const GrGLSLVarying& varying,
+                                                                  const char* sampleIdx,
+                                                                  const char* interpolationMatrix) {
+    if (interpolationMatrix) {
+        f->codeAppendf("(%s + ", varying.fsIn());
+        f->appendOffsetToSample(sampleIdx, GrGLSLFPFragmentBuilder::kSkiaDevice_Coordinates);
+        f->codeAppendf(" * %s)", interpolationMatrix);
+    } else {
+        SkAssertResult(
+            f->enableFeature(GrGLSLFragmentBuilder::kMultisampleInterpolation_GLSLFeature));
+        f->codeAppendf("interpolateAtOffset(%s, ", varying.fsIn());
+        f->appendOffsetToSample(sampleIdx, GrGLSLFPFragmentBuilder::kGLSLWindow_Coordinates);
+        f->codeAppend(")");
+    }
+}
+
+void
+GLSLInstanceProcessor::BackendMultisample::acceptOrRejectWholeFragment(GrGLSLPPFragmentBuilder* f,
+                                                                       bool inside,
+                                                                       const EmitShapeOpts& opts) {
+    if (inside != opts.fInvertCoverage) { // Accept the entire fragment.
+        if (opts.fResolveMixedSamples) {
+            // This is a mixed sampled fragment in the interior of the shape. Reassign 100% coverage
+            // to one fragment, and drop all other fragments that may fall on this same pixel. Since
+            // our geometry is water tight and non-overlapping, we can take advantage of the
+            // properties that (1) the incoming sample masks will be disjoint across fragments that
+            // fall on a common pixel, and (2) since the entire fragment is inside the shape, each
+            // sample's corresponding bit will be set in the incoming sample mask of exactly one
+            // fragment.
+            f->codeAppend("if ((gl_SampleMaskIn[0] & SAMPLE_MASK_MSB) == 0) {");
+            // Drop this fragment.
+            if (!fBatchInfo.fCannotDiscard) {
+                f->codeAppend("discard;");
+            } else {
+                f->overrideSampleCoverage("0");
+            }
+            f->codeAppend("} else {");
+            // Override the lone surviving fragment to full coverage.
+            f->overrideSampleCoverage("-1");
+            f->codeAppend("}");
+        }
+    } else { // Reject the entire fragment.
+        if (!fBatchInfo.fCannotDiscard) {
+            f->codeAppend("discard;");
+        } else if (opts.fResolveMixedSamples) {
+            f->overrideSampleCoverage("0");
+        } else {
+            f->maskSampleCoverage("0");
+        }
+    }
+}
+
+void GLSLInstanceProcessor::BackendMultisample::acceptCoverageMask(GrGLSLPPFragmentBuilder* f,
+                                                                   const char* shapeMask,
+                                                                   const EmitShapeOpts& opts,
+                                                                   bool maybeSharedEdge) {
+    if (opts.fResolveMixedSamples) {
+        if (maybeSharedEdge) {
+            // This is a mixed sampled fragment, potentially on the outer edge of the shape, with
+            // only partial shape coverage. Override the coverage of one fragment to "shapeMask",
+            // and drop all other fragments that may fall on this same pixel. Since our geometry is
+            // water tight, non-overlapping, and completely contains the shape, this means that each
+            // "on" bit from shapeMask is guaranteed to be set in the incoming sample mask of one,
+            // and only one, fragment that falls on this same pixel.
+            SkASSERT(!opts.fInvertCoverage);
+            f->codeAppendf("if ((gl_SampleMaskIn[0] & (1 << findMSB(%s))) == 0) {", shapeMask);
+            // Drop this fragment.
+            if (!fBatchInfo.fCannotDiscard) {
+                f->codeAppend ("discard;");
+            } else {
+                f->overrideSampleCoverage("0");
+            }
+            f->codeAppend ("} else {");
+            // Override the coverage of the lone surviving fragment to "shapeMask".
+            f->overrideSampleCoverage(shapeMask);
+            f->codeAppend ("}");
+        } else {
+            f->overrideSampleCoverage(shapeMask);
+        }
+    } else {
+        f->maskSampleCoverage(shapeMask, opts.fInvertCoverage);
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+GLSLInstanceProcessor::Backend*
+GLSLInstanceProcessor::Backend::Create(const GrPipeline& pipeline, BatchInfo batchInfo,
+                                       const VertexInputs& inputs) {
+    switch (batchInfo.fAntialiasMode) {
+        default:
+            SkFAIL("Unexpected antialias mode.");
+        case AntialiasMode::kNone:
+            return new BackendNonAA(batchInfo, inputs);
+        case AntialiasMode::kCoverage:
+            return new BackendCoverage(batchInfo, inputs);
+        case AntialiasMode::kMSAA:
+        case AntialiasMode::kMixedSamples: {
+            const GrRenderTargetPriv& rtp = pipeline.getRenderTarget()->renderTargetPriv();
+            const GrGpu::MultisampleSpecs& specs = rtp.getMultisampleSpecs(pipeline.getStencil());
+            return new BackendMultisample(batchInfo, inputs, specs.fEffectiveSampleCnt);
+        }
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const ShapeVertex kVertexData[] = {
+    // Rectangle.
+    {+1, +1, ~0},   /*0*/
+    {-1, +1, ~0},   /*1*/
+    {-1, -1, ~0},   /*2*/
+    {+1, -1, ~0},   /*3*/
+    // The next 4 are for the bordered version.
+    {+1, +1,  0},   /*4*/
+    {-1, +1,  0},   /*5*/
+    {-1, -1,  0},   /*6*/
+    {+1, -1,  0},   /*7*/
+
+    // Octagon that inscribes the unit circle, cut by an interior unit octagon.
+    {+1.000000f,  0.000000f,  0},   /* 8*/
+    {+1.000000f, +0.414214f, ~0},   /* 9*/
+    {+0.707106f, +0.707106f,  0},   /*10*/
+    {+0.414214f, +1.000000f, ~0},   /*11*/
+    { 0.000000f, +1.000000f,  0},   /*12*/
+    {-0.414214f, +1.000000f, ~0},   /*13*/
+    {-0.707106f, +0.707106f,  0},   /*14*/
+    {-1.000000f, +0.414214f, ~0},   /*15*/
+    {-1.000000f,  0.000000f,  0},   /*16*/
+    {-1.000000f, -0.414214f, ~0},   /*17*/
+    {-0.707106f, -0.707106f,  0},   /*18*/
+    {-0.414214f, -1.000000f, ~0},   /*19*/
+    { 0.000000f, -1.000000f,  0},   /*20*/
+    {+0.414214f, -1.000000f, ~0},   /*21*/
+    {+0.707106f, -0.707106f,  0},   /*22*/
+    {+1.000000f, -0.414214f, ~0},   /*23*/
+    // This vertex is for the fanned versions.
+    { 0.000000f,  0.000000f, ~0},   /*24*/
+
+    // Rectangle with disjoint corner segments.
+    {+1.0, +0.5,  0x3},   /*25*/
+    {+1.0, +1.0,  0x3},   /*26*/
+    {+0.5, +1.0,  0x3},   /*27*/
+    {-0.5, +1.0,  0x2},   /*28*/
+    {-1.0, +1.0,  0x2},   /*29*/
+    {-1.0, +0.5,  0x2},   /*30*/
+    {-1.0, -0.5,  0x0},   /*31*/
+    {-1.0, -1.0,  0x0},   /*32*/
+    {-0.5, -1.0,  0x0},   /*33*/
+    {+0.5, -1.0,  0x1},   /*34*/
+    {+1.0, -1.0,  0x1},   /*35*/
+    {+1.0, -0.5,  0x1},   /*36*/
+    // The next 4 are for the fanned version.
+    { 0.0,  0.0,  0x3},   /*37*/
+    { 0.0,  0.0,  0x2},   /*38*/
+    { 0.0,  0.0,  0x0},   /*39*/
+    { 0.0,  0.0,  0x1},   /*40*/
+    // The next 8 are for the bordered version.
+    {+0.75, +0.50,  0x3},   /*41*/
+    {+0.50, +0.75,  0x3},   /*42*/
+    {-0.50, +0.75,  0x2},   /*43*/
+    {-0.75, +0.50,  0x2},   /*44*/
+    {-0.75, -0.50,  0x0},   /*45*/
+    {-0.50, -0.75,  0x0},   /*46*/
+    {+0.50, -0.75,  0x1},   /*47*/
+    {+0.75, -0.50,  0x1},   /*48*/
+
+    // 16-gon that inscribes the unit circle, cut by an interior unit 16-gon.
+    {+1.000000f, +0.000000f,  0},   /*49*/
+    {+1.000000f, +0.198913f, ~0},   /*50*/
+    {+0.923879f, +0.382683f,  0},   /*51*/
+    {+0.847760f, +0.566455f, ~0},   /*52*/
+    {+0.707106f, +0.707106f,  0},   /*53*/
+    {+0.566455f, +0.847760f, ~0},   /*54*/
+    {+0.382683f, +0.923879f,  0},   /*55*/
+    {+0.198913f, +1.000000f, ~0},   /*56*/
+    {+0.000000f, +1.000000f,  0},   /*57*/
+    {-0.198913f, +1.000000f, ~0},   /*58*/
+    {-0.382683f, +0.923879f,  0},   /*59*/
+    {-0.566455f, +0.847760f, ~0},   /*60*/
+    {-0.707106f, +0.707106f,  0},   /*61*/
+    {-0.847760f, +0.566455f, ~0},   /*62*/
+    {-0.923879f, +0.382683f,  0},   /*63*/
+    {-1.000000f, +0.198913f, ~0},   /*64*/
+    {-1.000000f, +0.000000f,  0},   /*65*/
+    {-1.000000f, -0.198913f, ~0},   /*66*/
+    {-0.923879f, -0.382683f,  0},   /*67*/
+    {-0.847760f, -0.566455f, ~0},   /*68*/
+    {-0.707106f, -0.707106f,  0},   /*69*/
+    {-0.566455f, -0.847760f, ~0},   /*70*/
+    {-0.382683f, -0.923879f,  0},   /*71*/
+    {-0.198913f, -1.000000f, ~0},   /*72*/
+    {-0.000000f, -1.000000f,  0},   /*73*/
+    {+0.198913f, -1.000000f, ~0},   /*74*/
+    {+0.382683f, -0.923879f,  0},   /*75*/
+    {+0.566455f, -0.847760f, ~0},   /*76*/
+    {+0.707106f, -0.707106f,  0},   /*77*/
+    {+0.847760f, -0.566455f, ~0},   /*78*/
+    {+0.923879f, -0.382683f,  0},   /*79*/
+    {+1.000000f, -0.198913f, ~0},   /*80*/
+};
+
+const uint8_t kIndexData[] = {
+    // Rectangle.
+    0, 1, 2,
+    0, 2, 3,
+
+    // Rectangle with a border.
+    0, 1, 5,
+    5, 4, 0,
+    1, 2, 6,
+    6, 5, 1,
+    2, 3, 7,
+    7, 6, 2,
+    3, 0, 4,
+    4, 7, 3,
+    4, 5, 6,
+    6, 7, 4,
+
+    // Octagon that inscribes the unit circle, cut by an interior unit octagon.
+    10,  8,  9,
+    12, 10, 11,
+    14, 12, 13,
+    16, 14, 15,
+    18, 16, 17,
+    20, 18, 19,
+    22, 20, 21,
+     8, 22, 23,
+     8, 10, 12,
+    12, 14, 16,
+    16, 18, 20,
+    20, 22,  8,
+     8, 12, 16,
+    16, 20,  8,
+
+    // Same octagons, but with the interior arranged as a fan. Used by mixed samples.
+    10,  8,  9,
+    12, 10, 11,
+    14, 12, 13,
+    16, 14, 15,
+    18, 16, 17,
+    20, 18, 19,
+    22, 20, 21,
+     8, 22, 23,
+    24,  8, 10,
+    12, 24, 10,
+    24, 12, 14,
+    16, 24, 14,
+    24, 16, 18,
+    20, 24, 18,
+    24, 20, 22,
+     8, 24, 22,
+
+    // Same octagons, but with the inner and outer disjoint. Used by coverage AA.
+     8, 22, 23,
+     9,  8, 23,
+    10,  8,  9,
+    11, 10,  9,
+    12, 10, 11,
+    13, 12, 11,
+    14, 12, 13,
+    15, 14, 13,
+    16, 14, 15,
+    17, 16, 15,
+    18, 16, 17,
+    19, 18, 17,
+    20, 18, 19,
+    21, 20, 19,
+    22, 20, 21,
+    23, 22, 21,
+    22,  8, 10,
+    10, 12, 14,
+    14, 16, 18,
+    18, 20, 22,
+    22, 10, 14,
+    14, 18, 22,
+
+    // Rectangle with disjoint corner segments.
+    27, 25, 26,
+    30, 28, 29,
+    33, 31, 32,
+    36, 34, 35,
+    25, 27, 28,
+    28, 30, 31,
+    31, 33, 34,
+    34, 36, 25,
+    25, 28, 31,
+    31, 34, 25,
+
+    // Same rectangle with disjoint corners, but with the interior arranged as a fan. Used by
+    // mixed samples.
+    27, 25, 26,
+    30, 28, 29,
+    33, 31, 32,
+    36, 34, 35,
+    27, 37, 25,
+    28, 37, 27,
+    30, 38, 28,
+    31, 38, 30,
+    33, 39, 31,
+    34, 39, 33,
+    36, 40, 34,
+    25, 40, 36,
+
+    // Same rectangle with disjoint corners, with a border as well. Used by coverage AA.
+    41, 25, 26,
+    42, 41, 26,
+    27, 42, 26,
+    43, 28, 29,
+    44, 43, 29,
+    30, 44, 29,
+    45, 31, 32,
+    46, 45, 32,
+    33, 46, 32,
+    47, 34, 35,
+    48, 47, 35,
+    36, 48, 35,
+    27, 28, 42,
+    42, 28, 43,
+    30, 31, 44,
+    44, 31, 45,
+    33, 34, 46,
+    46, 34, 47,
+    36, 25, 48,
+    48, 25, 41,
+    41, 42, 43,
+    43, 44, 45,
+    45, 46, 47,
+    47, 48, 41,
+    41, 43, 45,
+    45, 47, 41,
+
+    // Same as the disjoint octagons, but with 16-gons instead. Used by coverage AA when the oval is
+    // sufficiently large.
+    49, 79, 80,
+    50, 49, 80,
+    51, 49, 50,
+    52, 51, 50,
+    53, 51, 52,
+    54, 53, 52,
+    55, 53, 54,
+    56, 55, 54,
+    57, 55, 56,
+    58, 57, 56,
+    59, 57, 58,
+    60, 59, 58,
+    61, 59, 60,
+    62, 61, 60,
+    63, 61, 62,
+    64, 63, 62,
+    65, 63, 64,
+    66, 65, 64,
+    67, 65, 66,
+    68, 67, 66,
+    69, 67, 68,
+    70, 69, 68,
+    71, 69, 70,
+    72, 71, 70,
+    73, 71, 72,
+    74, 73, 72,
+    75, 73, 74,
+    76, 75, 74,
+    77, 75, 76,
+    78, 77, 76,
+    79, 77, 78,
+    80, 79, 78,
+    49, 51, 53,
+    53, 55, 57,
+    57, 59, 61,
+    61, 63, 65,
+    65, 67, 69,
+    69, 71, 73,
+    73, 75, 77,
+    77, 79, 49,
+    49, 53, 57,
+    57, 61, 65,
+    65, 69, 73,
+    73, 77, 49,
+    49, 57, 65,
+    65, 73, 49,
+};
+
+enum {
+    kRect_FirstIndex = 0,
+    kRect_TriCount = 2,
+
+    kFramedRect_FirstIndex = 6,
+    kFramedRect_TriCount = 10,
+
+    kOctagons_FirstIndex = 36,
+    kOctagons_TriCount = 14,
+
+    kOctagonsFanned_FirstIndex = 78,
+    kOctagonsFanned_TriCount = 16,
+
+    kDisjointOctagons_FirstIndex = 126,
+    kDisjointOctagons_TriCount = 22,
+
+    kCorneredRect_FirstIndex = 192,
+    kCorneredRect_TriCount = 10,
+
+    kCorneredRectFanned_FirstIndex = 222,
+    kCorneredRectFanned_TriCount = 12,
+
+    kCorneredFramedRect_FirstIndex = 258,
+    kCorneredFramedRect_TriCount = 26,
+
+    kDisjoint16Gons_FirstIndex = 336,
+    kDisjoint16Gons_TriCount = 46,
+};
+
+GR_DECLARE_STATIC_UNIQUE_KEY(gShapeVertexBufferKey);
+
+const GrBuffer* InstanceProcessor::FindOrCreateVertexBuffer(GrGpu* gpu) {
+    GR_DEFINE_STATIC_UNIQUE_KEY(gShapeVertexBufferKey);
+    GrResourceCache* cache = gpu->getContext()->getResourceCache();
+    if (GrGpuResource* cached = cache->findAndRefUniqueResource(gShapeVertexBufferKey)) {
+        return static_cast<GrBuffer*>(cached);
+    }
+    if (GrBuffer* buffer = gpu->createBuffer(sizeof(kVertexData), kVertex_GrBufferType,
+                                             kStatic_GrAccessPattern, kVertexData)) {
+        buffer->resourcePriv().setUniqueKey(gShapeVertexBufferKey);
+        return buffer;
+    }
+    return nullptr;
+}
+
+GR_DECLARE_STATIC_UNIQUE_KEY(gShapeIndexBufferKey);
+
+const GrBuffer* InstanceProcessor::FindOrCreateIndex8Buffer(GrGpu* gpu) {
+    GR_DEFINE_STATIC_UNIQUE_KEY(gShapeIndexBufferKey);
+    GrResourceCache* cache = gpu->getContext()->getResourceCache();
+    if (GrGpuResource* cached = cache->findAndRefUniqueResource(gShapeIndexBufferKey)) {
+        return static_cast<GrBuffer*>(cached);
+    }
+    if (GrBuffer* buffer = gpu->createBuffer(sizeof(kIndexData), kIndex_GrBufferType,
+                                             kStatic_GrAccessPattern, kIndexData)) {
+        buffer->resourcePriv().setUniqueKey(gShapeIndexBufferKey);
+        return buffer;
+    }
+    return nullptr;
+}
+
+IndexRange InstanceProcessor::GetIndexRangeForRect(AntialiasMode aa) {
+    static constexpr IndexRange kRectRanges[kNumAntialiasModes] = {
+        {kRect_FirstIndex,        3 * kRect_TriCount},        // kNone
+        {kFramedRect_FirstIndex,  3 * kFramedRect_TriCount},  // kCoverage
+        {kRect_FirstIndex,        3 * kRect_TriCount},        // kMSAA
+        {kRect_FirstIndex,        3 * kRect_TriCount}         // kMixedSamples
+    };
+
+    SkASSERT(aa >= AntialiasMode::kNone && aa <= AntialiasMode::kMixedSamples);
+    return kRectRanges[(int)aa];
+
+    GR_STATIC_ASSERT(0 == (int)AntialiasMode::kNone);
+    GR_STATIC_ASSERT(1 == (int)AntialiasMode::kCoverage);
+    GR_STATIC_ASSERT(2 == (int)AntialiasMode::kMSAA);
+    GR_STATIC_ASSERT(3 == (int)AntialiasMode::kMixedSamples);
+}
+
+IndexRange InstanceProcessor::GetIndexRangeForOval(AntialiasMode aa, const SkRect& devBounds) {
+    if (AntialiasMode::kCoverage == aa && devBounds.height() * devBounds.width() >= 256 * 256) {
+        // This threshold was chosen quasi-scientifically on Tegra X1.
+        return {kDisjoint16Gons_FirstIndex, 3 * kDisjoint16Gons_TriCount};
+    }
+
+    static constexpr IndexRange kOvalRanges[kNumAntialiasModes] = {
+        {kOctagons_FirstIndex,          3 * kOctagons_TriCount},          // kNone
+        {kDisjointOctagons_FirstIndex,  3 * kDisjointOctagons_TriCount},  // kCoverage
+        {kOctagons_FirstIndex,          3 * kOctagons_TriCount},          // kMSAA
+        {kOctagonsFanned_FirstIndex,    3 * kOctagonsFanned_TriCount}     // kMixedSamples
+    };
+
+    SkASSERT(aa >= AntialiasMode::kNone && aa <= AntialiasMode::kMixedSamples);
+    return kOvalRanges[(int)aa];
+
+    GR_STATIC_ASSERT(0 == (int)AntialiasMode::kNone);
+    GR_STATIC_ASSERT(1 == (int)AntialiasMode::kCoverage);
+    GR_STATIC_ASSERT(2 == (int)AntialiasMode::kMSAA);
+    GR_STATIC_ASSERT(3 == (int)AntialiasMode::kMixedSamples);
+}
+
+IndexRange InstanceProcessor::GetIndexRangeForRRect(AntialiasMode aa) {
+    static constexpr IndexRange kRRectRanges[kNumAntialiasModes] = {
+        {kCorneredRect_FirstIndex,        3 * kCorneredRect_TriCount},        // kNone
+        {kCorneredFramedRect_FirstIndex,  3 * kCorneredFramedRect_TriCount},  // kCoverage
+        {kCorneredRect_FirstIndex,        3 * kCorneredRect_TriCount},        // kMSAA
+        {kCorneredRectFanned_FirstIndex,  3 * kCorneredRectFanned_TriCount}   // kMixedSamples
+    };
+
+    SkASSERT(aa >= AntialiasMode::kNone && aa <= AntialiasMode::kMixedSamples);
+    return kRRectRanges[(int)aa];
+
+    GR_STATIC_ASSERT(0 == (int)AntialiasMode::kNone);
+    GR_STATIC_ASSERT(1 == (int)AntialiasMode::kCoverage);
+    GR_STATIC_ASSERT(2 == (int)AntialiasMode::kMSAA);
+    GR_STATIC_ASSERT(3 == (int)AntialiasMode::kMixedSamples);
+}
+
+const char* InstanceProcessor::GetNameOfIndexRange(IndexRange range) {
+    switch (range.fStart) {
+        case kRect_FirstIndex: return "basic_rect";
+        case kFramedRect_FirstIndex: return "coverage_rect";
+
+        case kOctagons_FirstIndex: return "basic_oval";
+        case kDisjointOctagons_FirstIndex: return "coverage_oval";
+        case kDisjoint16Gons_FirstIndex: return "coverage_large_oval";
+        case kOctagonsFanned_FirstIndex: return "mixed_samples_oval";
+
+        case kCorneredRect_FirstIndex: return "basic_round_rect";
+        case kCorneredFramedRect_FirstIndex: return "coverage_round_rect";
+        case kCorneredRectFanned_FirstIndex: return "mixed_samples_round_rect";
+
+        default: return "unknown";
+    }
+}
+
+}