src/gpu/glsl/GrGLSLProgramBuilder.cpp - third_party/skia - Git at Google

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "glsl/GrGLSLProgramBuilder.h"

 #include "GrPipeline.h"
 #include "GrTexturePriv.h"
 #include "glsl/GrGLSLFragmentProcessor.h"
 #include "glsl/GrGLSLGeometryProcessor.h"
 #include "glsl/GrGLSLVarying.h"
 #include "glsl/GrGLSLXferProcessor.h"

 const int GrGLSLProgramBuilder::kVarsPerBlock = 8;

 GrGLSLProgramBuilder::GrGLSLProgramBuilder(const GrPipeline& pipeline,
                                            const GrPrimitiveProcessor& primProc,
                                            const GrProgramDesc& desc)
     : fVS(this)
     , fGS(this)
     , fFS(this)
     , fStageIndex(-1)
     , fPipeline(pipeline)
     , fPrimProc(primProc)
     , fDesc(desc)
     , fGeometryProcessor(nullptr)
     , fXferProcessor(nullptr)
     , fNumVertexSamplers(0)
     , fNumGeometrySamplers(0)
     , fNumFragmentSamplers(0) {
 }

 void GrGLSLProgramBuilder::addFeature(GrShaderFlags shaders,
                                       uint32_t featureBit,
                                       const char* extensionName) {
     if (shaders & kVertex_GrShaderFlag) {
         fVS.addFeature(featureBit, extensionName);
     }
     if (shaders & kGeometry_GrShaderFlag) {
         SkASSERT(this->glslCaps()->geometryShaderSupport());
         fGS.addFeature(featureBit, extensionName);
     }
     if (shaders & kFragment_GrShaderFlag) {
         fFS.addFeature(featureBit, extensionName);
     }
 }

 bool GrGLSLProgramBuilder::emitAndInstallProcs(GrGLSLExpr4* inputColor,
                                                GrGLSLExpr4* inputCoverage) {
     // First we loop over all of the installed processors and collect coord transforms.  These will
     // be sent to the GrGLSLPrimitiveProcessor in its emitCode function
     const GrPrimitiveProcessor& primProc = this->primitiveProcessor();

     this->emitAndInstallPrimProc(primProc, inputColor, inputCoverage);

     this->emitAndInstallFragProcs(inputColor, inputCoverage);
     if (primProc.getPixelLocalStorageState() !=
         GrPixelLocalStorageState::kDraw_GrPixelLocalStorageState) {
         this->emitAndInstallXferProc(this->pipeline().getXferProcessor(), *inputColor,
                                      *inputCoverage, this->pipeline().ignoresCoverage(),
                                      primProc.getPixelLocalStorageState());
         this->emitFSOutputSwizzle(this->pipeline().getXferProcessor().hasSecondaryOutput());
     }

     return this->checkSamplerCounts();
 }

 void GrGLSLProgramBuilder::emitAndInstallPrimProc(const GrPrimitiveProcessor& proc,
                                                   GrGLSLExpr4* outputColor,
                                                   GrGLSLExpr4* outputCoverage) {
     // Program builders have a bit of state we need to clear with each effect
     AutoStageAdvance adv(this);
     this->nameExpression(outputColor, "outputColor");
     this->nameExpression(outputCoverage, "outputCoverage");

     const char* distanceVectorName = nullptr;
     if (this->fPipeline.usesDistanceVectorField() && proc.implementsDistanceVector()) {
         // Each individual user (FP) of the distance vector must be able to handle having this
         // variable be undeclared. There is no single default value that will yield a reasonable
         // result for all users.
         distanceVectorName = fFS.distanceVectorName();
         fFS.codeAppend( "// Normalized vector to the closest geometric edge (in device space)\n");
         fFS.codeAppend( "// Distance to the edge encoded in the z-component\n");
         fFS.codeAppendf("vec4 %s;", distanceVectorName);
     }

     // Enclose custom code in a block to avoid namespace conflicts
     SkString openBrace;
     openBrace.printf("{ // Stage %d, %s\n", fStageIndex, proc.name());
     fFS.codeAppend(openBrace.c_str());
     fVS.codeAppendf("// Primitive Processor %s\n", proc.name());

     SkASSERT(!fGeometryProcessor);
     fGeometryProcessor = proc.createGLSLInstance(*this->glslCaps());

     SkSTArray<4, SamplerHandle> texSamplers(proc.numTextureSamplers());
     SkSTArray<2, SamplerHandle> bufferSamplers(proc.numBuffers());
     this->emitSamplers(proc, &texSamplers, &bufferSamplers);

     GrGLSLPrimitiveProcessor::FPCoordTransformHandler transformHandler(fPipeline,
                                                                        &fTransformedCoordVars);
     GrGLSLGeometryProcessor::EmitArgs args(&fVS,
                                            &fFS,
                                            this->varyingHandler(),
                                            this->uniformHandler(),
                                            this->glslCaps(),
                                            proc,
                                            outputColor->c_str(),
                                            outputCoverage->c_str(),
                                            distanceVectorName,
                                            texSamplers.begin(),
                                            bufferSamplers.begin(),
                                            &transformHandler);
     fGeometryProcessor->emitCode(args);

     // We have to check that effects and the code they emit are consistent, ie if an effect
     // asks for dst color, then the emit code needs to follow suit
     SkDEBUGCODE(verify(proc);)

     fFS.codeAppend("}");
 }

 void GrGLSLProgramBuilder::emitAndInstallFragProcs(GrGLSLExpr4* color, GrGLSLExpr4* coverage) {
     int transformedCoordVarsIdx = 0;
     GrGLSLExpr4** inOut = &color;
     for (int i = 0; i < this->pipeline().numFragmentProcessors(); ++i) {
         if (i == this->pipeline().numColorFragmentProcessors()) {
             inOut = &coverage;
         }
         GrGLSLExpr4 output;
         const GrFragmentProcessor& fp = this->pipeline().getFragmentProcessor(i);
         this->emitAndInstallFragProc(fp, i, transformedCoordVarsIdx, **inOut, &output);
         GrFragmentProcessor::Iter iter(&fp);
         while (const GrFragmentProcessor* fp = iter.next()) {
             transformedCoordVarsIdx += fp->numCoordTransforms();
         }
         **inOut = output;
     }
 }

 // TODO Processors cannot output zeros because an empty string is all 1s
 // the fix is to allow effects to take the GrGLSLExpr4 directly
 void GrGLSLProgramBuilder::emitAndInstallFragProc(const GrFragmentProcessor& fp,
                                                   int index,
                                                   int transformedCoordVarsIdx,
                                                   const GrGLSLExpr4& input,
                                                   GrGLSLExpr4* output) {
     // Program builders have a bit of state we need to clear with each effect
     AutoStageAdvance adv(this);
     this->nameExpression(output, "output");

     // Enclose custom code in a block to avoid namespace conflicts
     SkString openBrace;
     openBrace.printf("{ // Stage %d, %s\n", fStageIndex, fp.name());
     fFS.codeAppend(openBrace.c_str());

     GrGLSLFragmentProcessor* fragProc = fp.createGLSLInstance();

     SkSTArray<4, SamplerHandle> textureSamplerArray(fp.numTextureSamplers());
     SkSTArray<2, SamplerHandle> bufferSamplerArray(fp.numBuffers());
     GrFragmentProcessor::Iter iter(&fp);
     while (const GrFragmentProcessor* subFP = iter.next()) {
         this->emitSamplers(*subFP, &textureSamplerArray, &bufferSamplerArray);
     }

     const GrShaderVar* coordVars = fTransformedCoordVars.begin() + transformedCoordVarsIdx;
     GrGLSLFragmentProcessor::TransformedCoordVars coords(&fp, coordVars);
     GrGLSLFragmentProcessor::TextureSamplers textureSamplers(&fp, textureSamplerArray.begin());
     GrGLSLFragmentProcessor::BufferSamplers bufferSamplers(&fp, bufferSamplerArray.begin());
     GrGLSLFragmentProcessor::EmitArgs args(&fFS,
                                            this->uniformHandler(),
                                            this->glslCaps(),
                                            fp,
                                            output->c_str(),
                                            input.isOnes() ? nullptr : input.c_str(),
                                            coords,
                                            textureSamplers,
                                            bufferSamplers,
                                            this->primitiveProcessor().implementsDistanceVector());

     fragProc->emitCode(args);

     // We have to check that effects and the code they emit are consistent, ie if an effect
     // asks for dst color, then the emit code needs to follow suit
     SkDEBUGCODE(verify(fp);)
     fFragmentProcessors.push_back(fragProc);

     fFS.codeAppend("}");
 }

 void GrGLSLProgramBuilder::emitAndInstallXferProc(const GrXferProcessor& xp,
                                                   const GrGLSLExpr4& colorIn,
                                                   const GrGLSLExpr4& coverageIn,
                                                   bool ignoresCoverage,
                                                   GrPixelLocalStorageState plsState) {
     // Program builders have a bit of state we need to clear with each effect
     AutoStageAdvance adv(this);

     SkASSERT(!fXferProcessor);
     fXferProcessor = xp.createGLSLInstance();

     // Enable dual source secondary output if we have one
     if (xp.hasSecondaryOutput()) {
         fFS.enableSecondaryOutput();
     }

     if (this->glslCaps()->mustDeclareFragmentShaderOutput()) {
         fFS.enableCustomOutput();
     }

     SkString openBrace;
     openBrace.printf("{ // Xfer Processor: %s\n", xp.name());
     fFS.codeAppend(openBrace.c_str());

     SkSTArray<4, SamplerHandle> texSamplers(xp.numTextureSamplers());
     SkSTArray<2, SamplerHandle> bufferSamplers(xp.numBuffers());
     this->emitSamplers(xp, &texSamplers, &bufferSamplers);

     bool usePLSDstRead = (plsState == GrPixelLocalStorageState::kFinish_GrPixelLocalStorageState);
     GrGLSLXferProcessor::EmitArgs args(&fFS,
                                        this->uniformHandler(),
                                        this->glslCaps(),
                                        xp, colorIn.c_str(),
                                        ignoresCoverage ? nullptr : coverageIn.c_str(),
                                        fFS.getPrimaryColorOutputName(),
                                        fFS.getSecondaryColorOutputName(),
                                        texSamplers.begin(),
                                        bufferSamplers.begin(),
                                        usePLSDstRead);
     fXferProcessor->emitCode(args);

     // We have to check that effects and the code they emit are consistent, ie if an effect
     // asks for dst color, then the emit code needs to follow suit
     SkDEBUGCODE(verify(xp);)
     fFS.codeAppend("}");
 }

 void GrGLSLProgramBuilder::emitSamplers(const GrProcessor& processor,
                                         SkTArray<SamplerHandle>* outTexSamplers,
                                         SkTArray<SamplerHandle>* outBufferSamplers) {
     SkString name;
     int numTextureSamplers = processor.numTextureSamplers();
     for (int t = 0; t < numTextureSamplers; ++t) {
         const GrProcessor::TextureSampler& sampler = processor.textureSampler(t);
         GrSLType samplerType = sampler.getTexture()->texturePriv().samplerType();
         if (kTextureExternalSampler_GrSLType == samplerType) {
             const char* externalFeatureString = this->glslCaps()->externalTextureExtensionString();
             // We shouldn't ever create a GrGLTexture that requires external sampler type
             SkASSERT(externalFeatureString);
             this->addFeature(sampler.getVisibility(),
                              1 << GrGLSLShaderBuilder::kExternalTexture_GLSLPrivateFeature,
                              externalFeatureString);
         }
         name.printf("TextureSampler_%d", outTexSamplers->count());
         this->emitSampler(samplerType, sampler.getTexture()->config(),
                           name.c_str(), sampler.getVisibility(), outTexSamplers);
     }

     if (int numBuffers = processor.numBuffers()) {
         SkASSERT(this->glslCaps()->texelBufferSupport());
         GrShaderFlags texelBufferVisibility = kNone_GrShaderFlags;

         for (int b = 0; b < numBuffers; ++b) {
             const GrBufferAccess& access = processor.bufferAccess(b);
             name.printf("BufferSampler_%d", outBufferSamplers->count());
             this->emitSampler(kBufferSampler_GrSLType, access.texelConfig(), name.c_str(),
                               access.visibility(), outBufferSamplers);
             texelBufferVisibility |= access.visibility();
         }

         if (const char* extension = this->glslCaps()->texelBufferExtensionString()) {
             this->addFeature(texelBufferVisibility,
                              1 << GrGLSLShaderBuilder::kTexelBuffer_GLSLPrivateFeature,
                              extension);
         }
     }
 }

 void GrGLSLProgramBuilder::emitSampler(GrSLType samplerType,
                                        GrPixelConfig config,
                                        const char* name,
                                        GrShaderFlags visibility,
                                        SkTArray<SamplerHandle>* outSamplers) {
     if (visibility & kVertex_GrShaderFlag) {
         ++fNumVertexSamplers;
     }
     if (visibility & kGeometry_GrShaderFlag) {
         SkASSERT(this->primitiveProcessor().willUseGeoShader());
         ++fNumGeometrySamplers;
     }
     if (visibility & kFragment_GrShaderFlag) {
         ++fNumFragmentSamplers;
     }
     GrSLPrecision precision = this->glslCaps()->samplerPrecision(config, visibility);
     SamplerHandle handle = this->uniformHandler()->addSampler(visibility,
                                                               config,
                                                               samplerType,
                                                               precision,
                                                               name);
     outSamplers->emplace_back(handle);
 }

 void GrGLSLProgramBuilder::emitFSOutputSwizzle(bool hasSecondaryOutput) {
     // Swizzle the fragment shader outputs if necessary.
     GrSwizzle swizzle;
     swizzle.setFromKey(this->desc().header().fOutputSwizzle);
     if (swizzle != GrSwizzle::RGBA()) {
         fFS.codeAppendf("%s = %s.%s;", fFS.getPrimaryColorOutputName(),
                         fFS.getPrimaryColorOutputName(),
                         swizzle.c_str());
         if (hasSecondaryOutput) {
             fFS.codeAppendf("%s = %s.%s;", fFS.getSecondaryColorOutputName(),
                             fFS.getSecondaryColorOutputName(),
                             swizzle.c_str());
         }
     }
 }

 bool GrGLSLProgramBuilder::checkSamplerCounts() {
     const GrGLSLCaps& glslCaps = *this->glslCaps();
     if (fNumVertexSamplers > glslCaps.maxVertexSamplers()) {
         GrCapsDebugf(this->caps(), "Program would use too many vertex samplers\n");
         return false;
     }
     if (fNumGeometrySamplers > glslCaps.maxGeometrySamplers()) {
         GrCapsDebugf(this->caps(), "Program would use too many geometry samplers\n");
         return false;
     }
     if (fNumFragmentSamplers > glslCaps.maxFragmentSamplers()) {
         GrCapsDebugf(this->caps(), "Program would use too many fragment samplers\n");
         return false;
     }
     // If the same sampler is used in two different shaders, it counts as two combined samplers.
     int numCombinedSamplers = fNumVertexSamplers + fNumGeometrySamplers + fNumFragmentSamplers;
     if (numCombinedSamplers > glslCaps.maxCombinedSamplers()) {
         GrCapsDebugf(this->caps(), "Program would use too many combined samplers\n");
         return false;
     }
     return true;
 }

 #ifdef SK_DEBUG
 void GrGLSLProgramBuilder::verify(const GrPrimitiveProcessor& gp) {
     SkASSERT(fFS.usedProcessorFeatures() == gp.requiredFeatures());
 }

 void GrGLSLProgramBuilder::verify(const GrXferProcessor& xp) {
     SkASSERT(fFS.usedProcessorFeatures() == xp.requiredFeatures());
     SkASSERT(fFS.hasReadDstColor() == xp.willReadDstColor());
 }

 void GrGLSLProgramBuilder::verify(const GrFragmentProcessor& fp) {
     SkASSERT(fFS.usedProcessorFeatures() == fp.requiredFeatures());
 }
 #endif

 void GrGLSLProgramBuilder::nameVariable(SkString* out, char prefix, const char* name, bool mangle) {
     if ('\0' == prefix) {
         *out = name;
     } else {
         out->printf("%c%s", prefix, name);
     }
     if (mangle) {
         if (out->endsWith('_')) {
             // Names containing "__" are reserved.
             out->append("x");
         }
         out->appendf("_Stage%d%s", fStageIndex, fFS.getMangleString().c_str());
     }
 }

 void GrGLSLProgramBuilder::nameExpression(GrGLSLExpr4* output, const char* baseName) {
     // create var to hold stage result.  If we already have a valid output name, just use that
     // otherwise create a new mangled one.  This name is only valid if we are reordering stages
     // and have to tell stage exactly where to put its output.
     SkString outName;
     if (output->isValid()) {
         outName = output->c_str();
     } else {
         this->nameVariable(&outName, '\0', baseName);
     }
     fFS.codeAppendf("vec4 %s;", outName.c_str());
     *output = outName;
 }

 void GrGLSLProgramBuilder::appendUniformDecls(GrShaderFlags visibility, SkString* out) const {
     this->uniformHandler()->appendUniformDecls(visibility, out);
 }

 const GrGLSLSampler& GrGLSLProgramBuilder::getSampler(SamplerHandle handle) const {
     return this->uniformHandler()->getSampler(handle);
 }

 void GrGLSLProgramBuilder::addRTAdjustmentUniform(GrSLPrecision precision,
                                                   const char* name,
                                                   const char** outName) {
         SkASSERT(!fUniformHandles.fRTAdjustmentUni.isValid());
         fUniformHandles.fRTAdjustmentUni =
             this->uniformHandler()->addUniform(kVertex_GrShaderFlag,
                                                kVec4f_GrSLType,
                                                precision,
                                                name,
                                                outName);
 }

 void GrGLSLProgramBuilder::addRTHeightUniform(const char* name, const char** outName) {
         SkASSERT(!fUniformHandles.fRTHeightUni.isValid());
         GrGLSLUniformHandler* uniformHandler = this->uniformHandler();
         fUniformHandles.fRTHeightUni =
             uniformHandler->internalAddUniformArray(kFragment_GrShaderFlag,
                                                     kFloat_GrSLType, kDefault_GrSLPrecision,
                                                     name, false, 0, outName);
 }

 void GrGLSLProgramBuilder::cleanupFragmentProcessors() {
     for (int i = 0; i < fFragmentProcessors.count(); ++i) {
         delete fFragmentProcessors[i];
     }
 }

 void GrGLSLProgramBuilder::finalizeShaders() {
     this->varyingHandler()->finalize();
     fVS.finalize(kVertex_GrShaderFlag);
     fFS.finalize(kFragment_GrShaderFlag);
 }
	/*
	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "glsl/GrGLSLProgramBuilder.h"

	#include "GrPipeline.h"
	#include "GrTexturePriv.h"
	#include "glsl/GrGLSLFragmentProcessor.h"
	#include "glsl/GrGLSLGeometryProcessor.h"
	#include "glsl/GrGLSLVarying.h"
	#include "glsl/GrGLSLXferProcessor.h"

	const int GrGLSLProgramBuilder::kVarsPerBlock = 8;

	GrGLSLProgramBuilder::GrGLSLProgramBuilder(const GrPipeline& pipeline,
	const GrPrimitiveProcessor& primProc,
	const GrProgramDesc& desc)
	: fVS(this)
	, fGS(this)
	, fFS(this)
	, fStageIndex(-1)
	, fPipeline(pipeline)
	, fPrimProc(primProc)
	, fDesc(desc)
	, fGeometryProcessor(nullptr)
	, fXferProcessor(nullptr)
	, fNumVertexSamplers(0)
	, fNumGeometrySamplers(0)
	, fNumFragmentSamplers(0) {
	}

	void GrGLSLProgramBuilder::addFeature(GrShaderFlags shaders,
	uint32_t featureBit,
	const char* extensionName) {
	if (shaders & kVertex_GrShaderFlag) {
	fVS.addFeature(featureBit, extensionName);
	}
	if (shaders & kGeometry_GrShaderFlag) {
	SkASSERT(this->glslCaps()->geometryShaderSupport());
	fGS.addFeature(featureBit, extensionName);
	}
	if (shaders & kFragment_GrShaderFlag) {
	fFS.addFeature(featureBit, extensionName);
	}
	}

	bool GrGLSLProgramBuilder::emitAndInstallProcs(GrGLSLExpr4* inputColor,
	GrGLSLExpr4* inputCoverage) {
	// First we loop over all of the installed processors and collect coord transforms. These will
	// be sent to the GrGLSLPrimitiveProcessor in its emitCode function
	const GrPrimitiveProcessor& primProc = this->primitiveProcessor();

	this->emitAndInstallPrimProc(primProc, inputColor, inputCoverage);

	this->emitAndInstallFragProcs(inputColor, inputCoverage);
	if (primProc.getPixelLocalStorageState() !=
	GrPixelLocalStorageState::kDraw_GrPixelLocalStorageState) {
	this->emitAndInstallXferProc(this->pipeline().getXferProcessor(), *inputColor,
	*inputCoverage, this->pipeline().ignoresCoverage(),
	primProc.getPixelLocalStorageState());
	this->emitFSOutputSwizzle(this->pipeline().getXferProcessor().hasSecondaryOutput());
	}

	return this->checkSamplerCounts();
	}

	void GrGLSLProgramBuilder::emitAndInstallPrimProc(const GrPrimitiveProcessor& proc,
	GrGLSLExpr4* outputColor,
	GrGLSLExpr4* outputCoverage) {
	// Program builders have a bit of state we need to clear with each effect
	AutoStageAdvance adv(this);
	this->nameExpression(outputColor, "outputColor");
	this->nameExpression(outputCoverage, "outputCoverage");

	const char* distanceVectorName = nullptr;
	if (this->fPipeline.usesDistanceVectorField() && proc.implementsDistanceVector()) {
	// Each individual user (FP) of the distance vector must be able to handle having this
	// variable be undeclared. There is no single default value that will yield a reasonable
	// result for all users.
	distanceVectorName = fFS.distanceVectorName();
	fFS.codeAppend( "// Normalized vector to the closest geometric edge (in device space)\n");
	fFS.codeAppend( "// Distance to the edge encoded in the z-component\n");
	fFS.codeAppendf("vec4 %s;", distanceVectorName);
	}

	// Enclose custom code in a block to avoid namespace conflicts
	SkString openBrace;
	openBrace.printf("{ // Stage %d, %s\n", fStageIndex, proc.name());
	fFS.codeAppend(openBrace.c_str());
	fVS.codeAppendf("// Primitive Processor %s\n", proc.name());

	SkASSERT(!fGeometryProcessor);
	fGeometryProcessor = proc.createGLSLInstance(*this->glslCaps());

	SkSTArray<4, SamplerHandle> texSamplers(proc.numTextureSamplers());
	SkSTArray<2, SamplerHandle> bufferSamplers(proc.numBuffers());
	this->emitSamplers(proc, &texSamplers, &bufferSamplers);

	GrGLSLPrimitiveProcessor::FPCoordTransformHandler transformHandler(fPipeline,
	&fTransformedCoordVars);
	GrGLSLGeometryProcessor::EmitArgs args(&fVS,
	&fFS,
	this->varyingHandler(),
	this->uniformHandler(),
	this->glslCaps(),
	proc,
	outputColor->c_str(),
	outputCoverage->c_str(),
	distanceVectorName,
	texSamplers.begin(),
	bufferSamplers.begin(),
	&transformHandler);
	fGeometryProcessor->emitCode(args);

	// We have to check that effects and the code they emit are consistent, ie if an effect
	// asks for dst color, then the emit code needs to follow suit
	SkDEBUGCODE(verify(proc);)

	fFS.codeAppend("}");
	}

	void GrGLSLProgramBuilder::emitAndInstallFragProcs(GrGLSLExpr4* color, GrGLSLExpr4* coverage) {
	int transformedCoordVarsIdx = 0;
	GrGLSLExpr4** inOut = &color;
	for (int i = 0; i < this->pipeline().numFragmentProcessors(); ++i) {
	if (i == this->pipeline().numColorFragmentProcessors()) {
	inOut = &coverage;
	}
	GrGLSLExpr4 output;
	const GrFragmentProcessor& fp = this->pipeline().getFragmentProcessor(i);
	this->emitAndInstallFragProc(fp, i, transformedCoordVarsIdx, **inOut, &output);
	GrFragmentProcessor::Iter iter(&fp);
	while (const GrFragmentProcessor* fp = iter.next()) {
	transformedCoordVarsIdx += fp->numCoordTransforms();
	}
	**inOut = output;
	}
	}

	// TODO Processors cannot output zeros because an empty string is all 1s
	// the fix is to allow effects to take the GrGLSLExpr4 directly
	void GrGLSLProgramBuilder::emitAndInstallFragProc(const GrFragmentProcessor& fp,
	int index,
	int transformedCoordVarsIdx,
	const GrGLSLExpr4& input,
	GrGLSLExpr4* output) {
	// Program builders have a bit of state we need to clear with each effect
	AutoStageAdvance adv(this);
	this->nameExpression(output, "output");

	// Enclose custom code in a block to avoid namespace conflicts
	SkString openBrace;
	openBrace.printf("{ // Stage %d, %s\n", fStageIndex, fp.name());
	fFS.codeAppend(openBrace.c_str());

	GrGLSLFragmentProcessor* fragProc = fp.createGLSLInstance();

	SkSTArray<4, SamplerHandle> textureSamplerArray(fp.numTextureSamplers());
	SkSTArray<2, SamplerHandle> bufferSamplerArray(fp.numBuffers());
	GrFragmentProcessor::Iter iter(&fp);
	while (const GrFragmentProcessor* subFP = iter.next()) {
	this->emitSamplers(*subFP, &textureSamplerArray, &bufferSamplerArray);
	}

	const GrShaderVar* coordVars = fTransformedCoordVars.begin() + transformedCoordVarsIdx;
	GrGLSLFragmentProcessor::TransformedCoordVars coords(&fp, coordVars);
	GrGLSLFragmentProcessor::TextureSamplers textureSamplers(&fp, textureSamplerArray.begin());
	GrGLSLFragmentProcessor::BufferSamplers bufferSamplers(&fp, bufferSamplerArray.begin());
	GrGLSLFragmentProcessor::EmitArgs args(&fFS,
	this->uniformHandler(),
	this->glslCaps(),
	fp,
	output->c_str(),
	input.isOnes() ? nullptr : input.c_str(),
	coords,
	textureSamplers,
	bufferSamplers,
	this->primitiveProcessor().implementsDistanceVector());

	fragProc->emitCode(args);

	// We have to check that effects and the code they emit are consistent, ie if an effect
	// asks for dst color, then the emit code needs to follow suit
	SkDEBUGCODE(verify(fp);)
	fFragmentProcessors.push_back(fragProc);

	fFS.codeAppend("}");
	}

	void GrGLSLProgramBuilder::emitAndInstallXferProc(const GrXferProcessor& xp,
	const GrGLSLExpr4& colorIn,
	const GrGLSLExpr4& coverageIn,
	bool ignoresCoverage,
	GrPixelLocalStorageState plsState) {
	// Program builders have a bit of state we need to clear with each effect
	AutoStageAdvance adv(this);

	SkASSERT(!fXferProcessor);
	fXferProcessor = xp.createGLSLInstance();

	// Enable dual source secondary output if we have one
	if (xp.hasSecondaryOutput()) {
	fFS.enableSecondaryOutput();
	}

	if (this->glslCaps()->mustDeclareFragmentShaderOutput()) {
	fFS.enableCustomOutput();
	}

	SkString openBrace;
	openBrace.printf("{ // Xfer Processor: %s\n", xp.name());
	fFS.codeAppend(openBrace.c_str());

	SkSTArray<4, SamplerHandle> texSamplers(xp.numTextureSamplers());
	SkSTArray<2, SamplerHandle> bufferSamplers(xp.numBuffers());
	this->emitSamplers(xp, &texSamplers, &bufferSamplers);

	bool usePLSDstRead = (plsState == GrPixelLocalStorageState::kFinish_GrPixelLocalStorageState);
	GrGLSLXferProcessor::EmitArgs args(&fFS,
	this->uniformHandler(),
	this->glslCaps(),
	xp, colorIn.c_str(),
	ignoresCoverage ? nullptr : coverageIn.c_str(),
	fFS.getPrimaryColorOutputName(),
	fFS.getSecondaryColorOutputName(),
	texSamplers.begin(),
	bufferSamplers.begin(),
	usePLSDstRead);
	fXferProcessor->emitCode(args);

	// We have to check that effects and the code they emit are consistent, ie if an effect
	// asks for dst color, then the emit code needs to follow suit
	SkDEBUGCODE(verify(xp);)
	fFS.codeAppend("}");
	}

	void GrGLSLProgramBuilder::emitSamplers(const GrProcessor& processor,
	SkTArray<SamplerHandle>* outTexSamplers,
	SkTArray<SamplerHandle>* outBufferSamplers) {
	SkString name;
	int numTextureSamplers = processor.numTextureSamplers();
	for (int t = 0; t < numTextureSamplers; ++t) {
	const GrProcessor::TextureSampler& sampler = processor.textureSampler(t);
	GrSLType samplerType = sampler.getTexture()->texturePriv().samplerType();
	if (kTextureExternalSampler_GrSLType == samplerType) {
	const char* externalFeatureString = this->glslCaps()->externalTextureExtensionString();
	// We shouldn't ever create a GrGLTexture that requires external sampler type
	SkASSERT(externalFeatureString);
	this->addFeature(sampler.getVisibility(),
	1 << GrGLSLShaderBuilder::kExternalTexture_GLSLPrivateFeature,
	externalFeatureString);
	}
	name.printf("TextureSampler_%d", outTexSamplers->count());
	this->emitSampler(samplerType, sampler.getTexture()->config(),
	name.c_str(), sampler.getVisibility(), outTexSamplers);
	}

	if (int numBuffers = processor.numBuffers()) {
	SkASSERT(this->glslCaps()->texelBufferSupport());
	GrShaderFlags texelBufferVisibility = kNone_GrShaderFlags;

	for (int b = 0; b < numBuffers; ++b) {
	const GrBufferAccess& access = processor.bufferAccess(b);
	name.printf("BufferSampler_%d", outBufferSamplers->count());
	this->emitSampler(kBufferSampler_GrSLType, access.texelConfig(), name.c_str(),
	access.visibility(), outBufferSamplers);
	texelBufferVisibility \|= access.visibility();
	}

	if (const char* extension = this->glslCaps()->texelBufferExtensionString()) {
	this->addFeature(texelBufferVisibility,
	1 << GrGLSLShaderBuilder::kTexelBuffer_GLSLPrivateFeature,
	extension);
	}
	}
	}

	void GrGLSLProgramBuilder::emitSampler(GrSLType samplerType,
	GrPixelConfig config,
	const char* name,
	GrShaderFlags visibility,
	SkTArray<SamplerHandle>* outSamplers) {
	if (visibility & kVertex_GrShaderFlag) {
	++fNumVertexSamplers;
	}
	if (visibility & kGeometry_GrShaderFlag) {
	SkASSERT(this->primitiveProcessor().willUseGeoShader());
	++fNumGeometrySamplers;
	}
	if (visibility & kFragment_GrShaderFlag) {
	++fNumFragmentSamplers;
	}
	GrSLPrecision precision = this->glslCaps()->samplerPrecision(config, visibility);
	SamplerHandle handle = this->uniformHandler()->addSampler(visibility,
	config,
	samplerType,
	precision,
	name);
	outSamplers->emplace_back(handle);
	}

	void GrGLSLProgramBuilder::emitFSOutputSwizzle(bool hasSecondaryOutput) {
	// Swizzle the fragment shader outputs if necessary.
	GrSwizzle swizzle;
	swizzle.setFromKey(this->desc().header().fOutputSwizzle);
	if (swizzle != GrSwizzle::RGBA()) {
	fFS.codeAppendf("%s = %s.%s;", fFS.getPrimaryColorOutputName(),
	fFS.getPrimaryColorOutputName(),
	swizzle.c_str());
	if (hasSecondaryOutput) {
	fFS.codeAppendf("%s = %s.%s;", fFS.getSecondaryColorOutputName(),
	fFS.getSecondaryColorOutputName(),
	swizzle.c_str());
	}
	}
	}

	bool GrGLSLProgramBuilder::checkSamplerCounts() {
	const GrGLSLCaps& glslCaps = *this->glslCaps();
	if (fNumVertexSamplers > glslCaps.maxVertexSamplers()) {
	GrCapsDebugf(this->caps(), "Program would use too many vertex samplers\n");
	return false;
	}
	if (fNumGeometrySamplers > glslCaps.maxGeometrySamplers()) {
	GrCapsDebugf(this->caps(), "Program would use too many geometry samplers\n");
	return false;
	}
	if (fNumFragmentSamplers > glslCaps.maxFragmentSamplers()) {
	GrCapsDebugf(this->caps(), "Program would use too many fragment samplers\n");
	return false;
	}
	// If the same sampler is used in two different shaders, it counts as two combined samplers.
	int numCombinedSamplers = fNumVertexSamplers + fNumGeometrySamplers + fNumFragmentSamplers;
	if (numCombinedSamplers > glslCaps.maxCombinedSamplers()) {
	GrCapsDebugf(this->caps(), "Program would use too many combined samplers\n");
	return false;
	}
	return true;
	}

	#ifdef SK_DEBUG
	void GrGLSLProgramBuilder::verify(const GrPrimitiveProcessor& gp) {
	SkASSERT(fFS.usedProcessorFeatures() == gp.requiredFeatures());
	}

	void GrGLSLProgramBuilder::verify(const GrXferProcessor& xp) {
	SkASSERT(fFS.usedProcessorFeatures() == xp.requiredFeatures());
	SkASSERT(fFS.hasReadDstColor() == xp.willReadDstColor());
	}

	void GrGLSLProgramBuilder::verify(const GrFragmentProcessor& fp) {
	SkASSERT(fFS.usedProcessorFeatures() == fp.requiredFeatures());
	}
	#endif

	void GrGLSLProgramBuilder::nameVariable(SkString* out, char prefix, const char* name, bool mangle) {
	if ('\0' == prefix) {
	*out = name;
	} else {
	out->printf("%c%s", prefix, name);
	}
	if (mangle) {
	if (out->endsWith('_')) {
	// Names containing "__" are reserved.
	out->append("x");
	}
	out->appendf("_Stage%d%s", fStageIndex, fFS.getMangleString().c_str());
	}
	}

	void GrGLSLProgramBuilder::nameExpression(GrGLSLExpr4* output, const char* baseName) {
	// create var to hold stage result. If we already have a valid output name, just use that
	// otherwise create a new mangled one. This name is only valid if we are reordering stages
	// and have to tell stage exactly where to put its output.
	SkString outName;
	if (output->isValid()) {
	outName = output->c_str();
	} else {
	this->nameVariable(&outName, '\0', baseName);
	}
	fFS.codeAppendf("vec4 %s;", outName.c_str());
	*output = outName;
	}

	void GrGLSLProgramBuilder::appendUniformDecls(GrShaderFlags visibility, SkString* out) const {
	this->uniformHandler()->appendUniformDecls(visibility, out);
	}

	const GrGLSLSampler& GrGLSLProgramBuilder::getSampler(SamplerHandle handle) const {
	return this->uniformHandler()->getSampler(handle);
	}

	void GrGLSLProgramBuilder::addRTAdjustmentUniform(GrSLPrecision precision,
	const char* name,
	const char** outName) {
	SkASSERT(!fUniformHandles.fRTAdjustmentUni.isValid());
	fUniformHandles.fRTAdjustmentUni =
	this->uniformHandler()->addUniform(kVertex_GrShaderFlag,
	kVec4f_GrSLType,
	precision,
	name,
	outName);
	}

	void GrGLSLProgramBuilder::addRTHeightUniform(const char* name, const char** outName) {
	SkASSERT(!fUniformHandles.fRTHeightUni.isValid());
	GrGLSLUniformHandler* uniformHandler = this->uniformHandler();
	fUniformHandles.fRTHeightUni =
	uniformHandler->internalAddUniformArray(kFragment_GrShaderFlag,
	kFloat_GrSLType, kDefault_GrSLPrecision,
	name, false, 0, outName);
	}

	void GrGLSLProgramBuilder::cleanupFragmentProcessors() {
	for (int i = 0; i < fFragmentProcessors.count(); ++i) {
	delete fFragmentProcessors[i];
	}
	}

	void GrGLSLProgramBuilder::finalizeShaders() {
	this->varyingHandler()->finalize();
	fVS.finalize(kVertex_GrShaderFlag);
	fFS.finalize(kFragment_GrShaderFlag);
	}