src/third_party/skia/src/gpu/gl/GrGLProgramDesc.cpp - cobalt - Git at Google

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "gl/builders/GrGLProgramBuilder.h"
 #include "GrGLProgramDesc.h"
 #include "GrBackendProcessorFactory.h"
 #include "GrProcessor.h"
 #include "GrGpuGL.h"
 #include "GrOptDrawState.h"

 #include "SkChecksum.h"

 /**
  * The key for an individual coord transform is made up of a matrix type and a bit that
  * indicates the source of the input coords.
  */
 enum {
     kMatrixTypeKeyBits   = 1,
     kMatrixTypeKeyMask   = (1 << kMatrixTypeKeyBits) - 1,
     kPositionCoords_Flag = (1 << kMatrixTypeKeyBits),
     kTransformKeyBits    = kMatrixTypeKeyBits + 1,
 };

 /**
  * We specialize the vertex code for each of these matrix types.
  */
 enum MatrixType {
     kNoPersp_MatrixType  = 0,
     kGeneral_MatrixType  = 1,
 };

 /**
  * Do we need to either map r,g,b->a or a->r. configComponentMask indicates which channels are
  * present in the texture's config. swizzleComponentMask indicates the channels present in the
  * shader swizzle.
  */
 static bool swizzle_requires_alpha_remapping(const GrGLCaps& caps,
                                              uint32_t configComponentMask,
                                              uint32_t swizzleComponentMask) {
     if (caps.textureSwizzleSupport()) {
         // Any remapping is handled using texture swizzling not shader modifications.
         return false;
     }
     // check if the texture is alpha-only
     if (kA_GrColorComponentFlag == configComponentMask) {
         if (caps.textureRedSupport() && (kA_GrColorComponentFlag & swizzleComponentMask)) {
             // we must map the swizzle 'a's to 'r'.
             return true;
         }
         if (kRGB_GrColorComponentFlags & swizzleComponentMask) {
             // The 'r', 'g', and/or 'b's must be mapped to 'a' according to our semantics that
             // alpha-only textures smear alpha across all four channels when read.
             return true;
         }
     }
     return false;
 }

 static uint32_t gen_attrib_key(const GrGeometryProcessor* effect) {
     uint32_t key = 0;

     const GrGeometryProcessor::VertexAttribArray& vars = effect->getVertexAttribs();
     int numAttributes = vars.count();
     SkASSERT(numAttributes <= 2);
     for (int a = 0; a < numAttributes; ++a) {
         uint32_t value = 1 << a;
         key |= value;
     }
     return key;
 }

 static uint32_t gen_transform_key(const GrProcessorStage& effectStage,
                                   bool useExplicitLocalCoords) {
     uint32_t totalKey = 0;
     int numTransforms = effectStage.getProcessor()->numTransforms();
     for (int t = 0; t < numTransforms; ++t) {
         uint32_t key = 0;
         if (effectStage.isPerspectiveCoordTransform(t, useExplicitLocalCoords)) {
             key |= kGeneral_MatrixType;
         } else {
             key |= kNoPersp_MatrixType;
         }

         const GrCoordTransform& coordTransform = effectStage.getProcessor()->coordTransform(t);
         if (kLocal_GrCoordSet != coordTransform.sourceCoords() && useExplicitLocalCoords) {
             key |= kPositionCoords_Flag;
         }
         key <<= kTransformKeyBits * t;
         SkASSERT(0 == (totalKey & key)); // keys for each transform ought not to overlap
         totalKey |= key;
     }
     return totalKey;
 }

 static uint32_t gen_texture_key(const GrProcessor* effect, const GrGLCaps& caps) {
     uint32_t key = 0;
     int numTextures = effect->numTextures();
     for (int t = 0; t < numTextures; ++t) {
         const GrTextureAccess& access = effect->textureAccess(t);
         uint32_t configComponentMask = GrPixelConfigComponentMask(access.getTexture()->config());
         if (swizzle_requires_alpha_remapping(caps, configComponentMask, access.swizzleMask())) {
             key |= 1 << t;
         }
     }
     return key;
 }

 /**
  * A function which emits a meta key into the key builder.  This is required because shader code may
  * be dependent on properties of the effect that the effect itself doesn't use
  * in its key (e.g. the pixel format of textures used). So we create a meta-key for
  * every effect using this function. It is also responsible for inserting the effect's class ID
  * which must be different for every GrProcessor subclass. It can fail if an effect uses too many
  * textures, transforms, etc, for the space allotted in the meta-key.
  */

 static uint32_t* get_processor_meta_key(const GrProcessorStage& processorStage,
                                         bool useExplicitLocalCoords,
                                         const GrGLCaps& caps,
                                         GrProcessorKeyBuilder* b) {

     uint32_t textureKey = gen_texture_key(processorStage.getProcessor(), caps);
     uint32_t transformKey = gen_transform_key(processorStage,useExplicitLocalCoords);
     uint32_t classID = processorStage.getProcessor()->getFactory().effectClassID();

     // Currently we allow 16 bits for each of the above portions of the meta-key. Fail if they
     // don't fit.
     static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
     if ((textureKey | transformKey | classID) & kMetaKeyInvalidMask) {
         return NULL;
     }

     uint32_t* key = b->add32n(2);
     key[0] = (textureKey << 16 | transformKey);
     key[1] = (classID << 16);
     return key;
 }

 bool GrGLProgramDesc::GetProcessorKey(const GrProcessorStage& stage,
                                       const GrGLCaps& caps,
                                       bool useExplicitLocalCoords,
                                       GrProcessorKeyBuilder* b,
                                       uint16_t* processorKeySize) {
     const GrProcessor& effect = *stage.getProcessor();
     const GrBackendProcessorFactory& factory = effect.getFactory();
     factory.getGLProcessorKey(effect, caps, b);
     size_t size = b->size();
     if (size > SK_MaxU16) {
         *processorKeySize = 0; // suppresses a warning.
         return false;
     }
     *processorKeySize = SkToU16(size);
     if (NULL == get_processor_meta_key(stage, useExplicitLocalCoords, caps, b)) {
         return false;
     }
     return true;
 }

 bool GrGLProgramDesc::GetGeometryProcessorKey(const GrGeometryStage& stage,
                                               const GrGLCaps& caps,
                                               bool useExplicitLocalCoords,
                                               GrProcessorKeyBuilder* b,
                                               uint16_t* processorKeySize) {
     const GrProcessor& effect = *stage.getProcessor();
     const GrBackendProcessorFactory& factory = effect.getFactory();
     factory.getGLProcessorKey(effect, caps, b);
     size_t size = b->size();
     if (size > SK_MaxU16) {
         *processorKeySize = 0; // suppresses a warning.
         return false;
     }
     *processorKeySize = SkToU16(size);
     uint32_t* key = get_processor_meta_key(stage, useExplicitLocalCoords, caps, b);
     if (NULL == key) {
         return false;
     }
     uint32_t attribKey = gen_attrib_key(stage.getGeometryProcessor());

     // Currently we allow 16 bits for each of the above portions of the meta-key. Fail if they
     // don't fit.
     static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
     if ((attribKey) & kMetaKeyInvalidMask) {
        return false;
     }

     key[1] |= attribKey;
     return true;
 }


 bool GrGLProgramDesc::Build(const GrOptDrawState& optState,
                             GrGpu::DrawType drawType,
                             GrBlendCoeff srcCoeff,
                             GrBlendCoeff dstCoeff,
                             GrGpuGL* gpu,
                             const GrDeviceCoordTexture* dstCopy,
                             const GrGeometryStage** geometryProcessor,
                             SkTArray<const GrFragmentStage*, true>* colorStages,
                             SkTArray<const GrFragmentStage*, true>* coverageStages,
                             GrGLProgramDesc* desc) {
     colorStages->reset();
     coverageStages->reset();

     bool inputColorIsUsed = optState.inputColorIsUsed();
     bool inputCoverageIsUsed = optState.inputCoverageIsUsed();

     // The descriptor is used as a cache key. Thus when a field of the
     // descriptor will not affect program generation (because of the attribute
     // bindings in use or other descriptor field settings) it should be set
     // to a canonical value to avoid duplicate programs with different keys.

     bool requiresLocalCoordAttrib = optState.requiresLocalCoordAttrib();

     int numStages = optState.numTotalStages();

     GR_STATIC_ASSERT(0 == kEffectKeyOffsetsAndLengthOffset % sizeof(uint32_t));
     // Make room for everything up to and including the array of offsets to effect keys.
     desc->fKey.reset();
     desc->fKey.push_back_n(kEffectKeyOffsetsAndLengthOffset + 2 * sizeof(uint16_t) * numStages);

     int offsetAndSizeIndex = 0;

     KeyHeader* header = desc->header();
     // make sure any padding in the header is zeroed.
     memset(desc->header(), 0, kHeaderSize);

     // We can only have one effect which touches the vertex shader
     if (optState.hasGeometryProcessor()) {
         uint16_t* offsetAndSize =
                 reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
                                             offsetAndSizeIndex * 2 * sizeof(uint16_t));

         GrProcessorKeyBuilder b(&desc->fKey);
         uint16_t processorKeySize;
         uint32_t processorOffset = desc->fKey.count();
         const GrGeometryStage& gpStage = *optState.getGeometryProcessor();
         if (processorOffset > SK_MaxU16 ||
                 !GetGeometryProcessorKey(gpStage, gpu->glCaps(), requiresLocalCoordAttrib, &b,
                                          &processorKeySize)) {
             desc->fKey.reset();
             return false;
         }

         offsetAndSize[0] = SkToU16(processorOffset);
         offsetAndSize[1] = processorKeySize;
         ++offsetAndSizeIndex;
         *geometryProcessor = &gpStage;
         header->fHasGeometryProcessor = true;
     }

     for (int s = 0; s < optState.numColorStages(); ++s) {
         uint16_t* offsetAndSize =
             reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
                                         offsetAndSizeIndex * 2 * sizeof(uint16_t));

         GrProcessorKeyBuilder b(&desc->fKey);
         uint16_t processorKeySize;
         uint32_t processorOffset = desc->fKey.count();
         if (processorOffset > SK_MaxU16 ||
                 !GetProcessorKey(optState.getColorStage(s), gpu->glCaps(),
                                  requiresLocalCoordAttrib, &b, &processorKeySize)) {
             desc->fKey.reset();
             return false;
         }

         offsetAndSize[0] = SkToU16(processorOffset);
         offsetAndSize[1] = processorKeySize;
         ++offsetAndSizeIndex;
     }

     for (int s = 0; s < optState.numCoverageStages(); ++s) {
         uint16_t* offsetAndSize =
             reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
                                         offsetAndSizeIndex * 2 * sizeof(uint16_t));

         GrProcessorKeyBuilder b(&desc->fKey);
         uint16_t processorKeySize;
         uint32_t processorOffset = desc->fKey.count();
         if (processorOffset > SK_MaxU16 ||
                 !GetProcessorKey(optState.getCoverageStage(s), gpu->glCaps(),
                                  requiresLocalCoordAttrib, &b, &processorKeySize)) {
             desc->fKey.reset();
             return false;
         }

         offsetAndSize[0] = SkToU16(processorOffset);
         offsetAndSize[1] = processorKeySize;
         ++offsetAndSizeIndex;
     }

     // Because header is a pointer into the dynamic array, we can't push any new data into the key
     // below here.


     header->fEmitsPointSize = GrGpu::kDrawPoints_DrawType == drawType;

     // Currently the experimental GS will only work with triangle prims (and it doesn't do anything
     // other than pass through values from the VS to the FS anyway).
 #if GR_GL_EXPERIMENTAL_GS
 #if 0
     header->fExperimentalGS = gpu->caps().geometryShaderSupport();
 #else
     header->fExperimentalGS = false;
 #endif
 #endif

     if (gpu->caps()->pathRenderingSupport() &&
         GrGpu::IsPathRenderingDrawType(drawType) &&
         gpu->glPathRendering()->texturingMode() == GrGLPathRendering::FixedFunction_TexturingMode) {
         header->fUseFragShaderOnly = true;
         SkASSERT(!optState.hasGeometryProcessor());
     } else {
         header->fUseFragShaderOnly = false;
     }

     bool defaultToUniformInputs = GrGpu::IsPathRenderingDrawType(drawType) ||
                                   GR_GL_NO_CONSTANT_ATTRIBUTES;

     if (!inputColorIsUsed) {
         header->fColorInput = kAllOnes_ColorInput;
     } else if (defaultToUniformInputs && !optState.hasColorVertexAttribute()) {
         header->fColorInput = kUniform_ColorInput;
     } else {
         header->fColorInput = kAttribute_ColorInput;
         SkASSERT(!header->fUseFragShaderOnly);
     }

     bool covIsSolidWhite = !optState.hasCoverageVertexAttribute() &&
                            0xffffffff == optState.getCoverageColor();

     if (covIsSolidWhite || !inputCoverageIsUsed) {
         header->fCoverageInput = kAllOnes_ColorInput;
     } else if (defaultToUniformInputs && !optState.hasCoverageVertexAttribute()) {
         header->fCoverageInput = kUniform_ColorInput;
     } else {
         header->fCoverageInput = kAttribute_ColorInput;
         SkASSERT(!header->fUseFragShaderOnly);
     }

     if (optState.readsDst()) {
         SkASSERT(dstCopy || gpu->caps()->dstReadInShaderSupport());
         const GrTexture* dstCopyTexture = NULL;
         if (dstCopy) {
             dstCopyTexture = dstCopy->texture();
         }
         header->fDstReadKey = GrGLFragmentShaderBuilder::KeyForDstRead(dstCopyTexture,
                 gpu->glCaps());
         SkASSERT(0 != header->fDstReadKey);
     } else {
         header->fDstReadKey = 0;
     }

     if (optState.readsFragPosition()) {
         header->fFragPosKey = GrGLFragmentShaderBuilder::KeyForFragmentPosition(
                 optState.getRenderTarget(), gpu->glCaps());
     } else {
         header->fFragPosKey = 0;
     }

     // Record attribute indices
     header->fPositionAttributeIndex = optState.positionAttributeIndex();
     header->fLocalCoordAttributeIndex = optState.localCoordAttributeIndex();

     // For constant color and coverage we need an attribute with an index beyond those already set
     int availableAttributeIndex = optState.getVertexAttribCount();
     if (optState.hasColorVertexAttribute()) {
         header->fColorAttributeIndex = optState.colorVertexAttributeIndex();
     } else if (GrGLProgramDesc::kAttribute_ColorInput == header->fColorInput) {
         SkASSERT(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
         header->fColorAttributeIndex = availableAttributeIndex;
         availableAttributeIndex++;
     } else {
         header->fColorAttributeIndex = -1;
     }

     if (optState.hasCoverageVertexAttribute()) {
         header->fCoverageAttributeIndex = optState.coverageVertexAttributeIndex();
     } else if (GrGLProgramDesc::kAttribute_ColorInput == header->fCoverageInput) {
         SkASSERT(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
         header->fCoverageAttributeIndex = availableAttributeIndex;
     } else {
         header->fCoverageAttributeIndex = -1;
     }

     header->fPrimaryOutputType = optState.getPrimaryOutputType();
     header->fSecondaryOutputType = optState.getSecondaryOutputType();

     for (int s = 0; s < optState.numColorStages(); ++s) {
         colorStages->push_back(&optState.getColorStage(s));
     }
     for (int s = 0; s < optState.numCoverageStages(); ++s) {
         coverageStages->push_back(&optState.getCoverageStage(s));
     }

     header->fColorEffectCnt = colorStages->count();
     header->fCoverageEffectCnt = coverageStages->count();

     desc->finalize();
     return true;
 }

 void GrGLProgramDesc::finalize() {
     int keyLength = fKey.count();
     SkASSERT(0 == (keyLength % 4));
     *this->atOffset<uint32_t, kLengthOffset>() = SkToU32(keyLength);

     uint32_t* checksum = this->atOffset<uint32_t, kChecksumOffset>();
     *checksum = 0;
     *checksum = SkChecksum::Compute(reinterpret_cast<uint32_t*>(fKey.begin()), keyLength);
 }

 GrGLProgramDesc& GrGLProgramDesc::operator= (const GrGLProgramDesc& other) {
     size_t keyLength = other.keyLength();
     fKey.reset(keyLength);
     memcpy(fKey.begin(), other.fKey.begin(), keyLength);
     return *this;
 }
	/*
	* Copyright 2013 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "gl/builders/GrGLProgramBuilder.h"
	#include "GrGLProgramDesc.h"
	#include "GrBackendProcessorFactory.h"
	#include "GrProcessor.h"
	#include "GrGpuGL.h"
	#include "GrOptDrawState.h"

	#include "SkChecksum.h"

	/**
	* The key for an individual coord transform is made up of a matrix type and a bit that
	* indicates the source of the input coords.
	*/
	enum {
	kMatrixTypeKeyBits = 1,
	kMatrixTypeKeyMask = (1 << kMatrixTypeKeyBits) - 1,
	kPositionCoords_Flag = (1 << kMatrixTypeKeyBits),
	kTransformKeyBits = kMatrixTypeKeyBits + 1,
	};

	/**
	* We specialize the vertex code for each of these matrix types.
	*/
	enum MatrixType {
	kNoPersp_MatrixType = 0,
	kGeneral_MatrixType = 1,
	};

	/**
	* Do we need to either map r,g,b->a or a->r. configComponentMask indicates which channels are
	* present in the texture's config. swizzleComponentMask indicates the channels present in the
	* shader swizzle.
	*/
	static bool swizzle_requires_alpha_remapping(const GrGLCaps& caps,
	uint32_t configComponentMask,
	uint32_t swizzleComponentMask) {
	if (caps.textureSwizzleSupport()) {
	// Any remapping is handled using texture swizzling not shader modifications.
	return false;
	}
	// check if the texture is alpha-only
	if (kA_GrColorComponentFlag == configComponentMask) {
	if (caps.textureRedSupport() && (kA_GrColorComponentFlag & swizzleComponentMask)) {
	// we must map the swizzle 'a's to 'r'.
	return true;
	}
	if (kRGB_GrColorComponentFlags & swizzleComponentMask) {
	// The 'r', 'g', and/or 'b's must be mapped to 'a' according to our semantics that
	// alpha-only textures smear alpha across all four channels when read.
	return true;
	}
	}
	return false;
	}

	static uint32_t gen_attrib_key(const GrGeometryProcessor* effect) {
	uint32_t key = 0;

	const GrGeometryProcessor::VertexAttribArray& vars = effect->getVertexAttribs();
	int numAttributes = vars.count();
	SkASSERT(numAttributes <= 2);
	for (int a = 0; a < numAttributes; ++a) {
	uint32_t value = 1 << a;
	key \|= value;
	}
	return key;
	}

	static uint32_t gen_transform_key(const GrProcessorStage& effectStage,
	bool useExplicitLocalCoords) {
	uint32_t totalKey = 0;
	int numTransforms = effectStage.getProcessor()->numTransforms();
	for (int t = 0; t < numTransforms; ++t) {
	uint32_t key = 0;
	if (effectStage.isPerspectiveCoordTransform(t, useExplicitLocalCoords)) {
	key \|= kGeneral_MatrixType;
	} else {
	key \|= kNoPersp_MatrixType;
	}

	const GrCoordTransform& coordTransform = effectStage.getProcessor()->coordTransform(t);
	if (kLocal_GrCoordSet != coordTransform.sourceCoords() && useExplicitLocalCoords) {
	key \|= kPositionCoords_Flag;
	}
	key <<= kTransformKeyBits * t;
	SkASSERT(0 == (totalKey & key)); // keys for each transform ought not to overlap
	totalKey \|= key;
	}
	return totalKey;
	}

	static uint32_t gen_texture_key(const GrProcessor* effect, const GrGLCaps& caps) {
	uint32_t key = 0;
	int numTextures = effect->numTextures();
	for (int t = 0; t < numTextures; ++t) {
	const GrTextureAccess& access = effect->textureAccess(t);
	uint32_t configComponentMask = GrPixelConfigComponentMask(access.getTexture()->config());
	if (swizzle_requires_alpha_remapping(caps, configComponentMask, access.swizzleMask())) {
	key \|= 1 << t;
	}
	}
	return key;
	}

	/**
	* A function which emits a meta key into the key builder. This is required because shader code may
	* be dependent on properties of the effect that the effect itself doesn't use
	* in its key (e.g. the pixel format of textures used). So we create a meta-key for
	* every effect using this function. It is also responsible for inserting the effect's class ID
	* which must be different for every GrProcessor subclass. It can fail if an effect uses too many
	* textures, transforms, etc, for the space allotted in the meta-key.
	*/

	static uint32_t* get_processor_meta_key(const GrProcessorStage& processorStage,
	bool useExplicitLocalCoords,
	const GrGLCaps& caps,
	GrProcessorKeyBuilder* b) {

	uint32_t textureKey = gen_texture_key(processorStage.getProcessor(), caps);
	uint32_t transformKey = gen_transform_key(processorStage,useExplicitLocalCoords);
	uint32_t classID = processorStage.getProcessor()->getFactory().effectClassID();

	// Currently we allow 16 bits for each of the above portions of the meta-key. Fail if they
	// don't fit.
	static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
	if ((textureKey \| transformKey \| classID) & kMetaKeyInvalidMask) {
	return NULL;
	}

	uint32_t* key = b->add32n(2);
	key[0] = (textureKey << 16 \| transformKey);
	key[1] = (classID << 16);
	return key;
	}

	bool GrGLProgramDesc::GetProcessorKey(const GrProcessorStage& stage,
	const GrGLCaps& caps,
	bool useExplicitLocalCoords,
	GrProcessorKeyBuilder* b,
	uint16_t* processorKeySize) {
	const GrProcessor& effect = *stage.getProcessor();
	const GrBackendProcessorFactory& factory = effect.getFactory();
	factory.getGLProcessorKey(effect, caps, b);
	size_t size = b->size();
	if (size > SK_MaxU16) {
	*processorKeySize = 0; // suppresses a warning.
	return false;
	}
	*processorKeySize = SkToU16(size);
	if (NULL == get_processor_meta_key(stage, useExplicitLocalCoords, caps, b)) {
	return false;
	}
	return true;
	}

	bool GrGLProgramDesc::GetGeometryProcessorKey(const GrGeometryStage& stage,
	const GrGLCaps& caps,
	bool useExplicitLocalCoords,
	GrProcessorKeyBuilder* b,
	uint16_t* processorKeySize) {
	const GrProcessor& effect = *stage.getProcessor();
	const GrBackendProcessorFactory& factory = effect.getFactory();
	factory.getGLProcessorKey(effect, caps, b);
	size_t size = b->size();
	if (size > SK_MaxU16) {
	*processorKeySize = 0; // suppresses a warning.
	return false;
	}
	*processorKeySize = SkToU16(size);
	uint32_t* key = get_processor_meta_key(stage, useExplicitLocalCoords, caps, b);
	if (NULL == key) {
	return false;
	}
	uint32_t attribKey = gen_attrib_key(stage.getGeometryProcessor());

	// Currently we allow 16 bits for each of the above portions of the meta-key. Fail if they
	// don't fit.
	static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
	if ((attribKey) & kMetaKeyInvalidMask) {
	return false;
	}

	key[1] \|= attribKey;
	return true;
	}


	bool GrGLProgramDesc::Build(const GrOptDrawState& optState,
	GrGpu::DrawType drawType,
	GrBlendCoeff srcCoeff,
	GrBlendCoeff dstCoeff,
	GrGpuGL* gpu,
	const GrDeviceCoordTexture* dstCopy,
	const GrGeometryStage** geometryProcessor,
	SkTArray<const GrFragmentStage, true> colorStages,
	SkTArray<const GrFragmentStage, true> coverageStages,
	GrGLProgramDesc* desc) {
	colorStages->reset();
	coverageStages->reset();

	bool inputColorIsUsed = optState.inputColorIsUsed();
	bool inputCoverageIsUsed = optState.inputCoverageIsUsed();

	// The descriptor is used as a cache key. Thus when a field of the
	// descriptor will not affect program generation (because of the attribute
	// bindings in use or other descriptor field settings) it should be set
	// to a canonical value to avoid duplicate programs with different keys.

	bool requiresLocalCoordAttrib = optState.requiresLocalCoordAttrib();

	int numStages = optState.numTotalStages();

	GR_STATIC_ASSERT(0 == kEffectKeyOffsetsAndLengthOffset % sizeof(uint32_t));
	// Make room for everything up to and including the array of offsets to effect keys.
	desc->fKey.reset();
	desc->fKey.push_back_n(kEffectKeyOffsetsAndLengthOffset + 2 * sizeof(uint16_t) * numStages);

	int offsetAndSizeIndex = 0;

	KeyHeader* header = desc->header();
	// make sure any padding in the header is zeroed.
	memset(desc->header(), 0, kHeaderSize);

	// We can only have one effect which touches the vertex shader
	if (optState.hasGeometryProcessor()) {
	uint16_t* offsetAndSize =
	reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
	offsetAndSizeIndex * 2 * sizeof(uint16_t));

	GrProcessorKeyBuilder b(&desc->fKey);
	uint16_t processorKeySize;
	uint32_t processorOffset = desc->fKey.count();
	const GrGeometryStage& gpStage = *optState.getGeometryProcessor();
	if (processorOffset > SK_MaxU16 \|\|
	!GetGeometryProcessorKey(gpStage, gpu->glCaps(), requiresLocalCoordAttrib, &b,
	&processorKeySize)) {
	desc->fKey.reset();
	return false;
	}

	offsetAndSize[0] = SkToU16(processorOffset);
	offsetAndSize[1] = processorKeySize;
	++offsetAndSizeIndex;
	*geometryProcessor = &gpStage;
	header->fHasGeometryProcessor = true;
	}

	for (int s = 0; s < optState.numColorStages(); ++s) {
	uint16_t* offsetAndSize =
	reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
	offsetAndSizeIndex * 2 * sizeof(uint16_t));

	GrProcessorKeyBuilder b(&desc->fKey);
	uint16_t processorKeySize;
	uint32_t processorOffset = desc->fKey.count();
	if (processorOffset > SK_MaxU16 \|\|
	!GetProcessorKey(optState.getColorStage(s), gpu->glCaps(),
	requiresLocalCoordAttrib, &b, &processorKeySize)) {
	desc->fKey.reset();
	return false;
	}

	offsetAndSize[0] = SkToU16(processorOffset);
	offsetAndSize[1] = processorKeySize;
	++offsetAndSizeIndex;
	}

	for (int s = 0; s < optState.numCoverageStages(); ++s) {
	uint16_t* offsetAndSize =
	reinterpret_cast<uint16_t*>(desc->fKey.begin() + kEffectKeyOffsetsAndLengthOffset +
	offsetAndSizeIndex * 2 * sizeof(uint16_t));

	GrProcessorKeyBuilder b(&desc->fKey);
	uint16_t processorKeySize;
	uint32_t processorOffset = desc->fKey.count();
	if (processorOffset > SK_MaxU16 \|\|
	!GetProcessorKey(optState.getCoverageStage(s), gpu->glCaps(),
	requiresLocalCoordAttrib, &b, &processorKeySize)) {
	desc->fKey.reset();
	return false;
	}

	offsetAndSize[0] = SkToU16(processorOffset);
	offsetAndSize[1] = processorKeySize;
	++offsetAndSizeIndex;
	}

	// Because header is a pointer into the dynamic array, we can't push any new data into the key
	// below here.


	header->fEmitsPointSize = GrGpu::kDrawPoints_DrawType == drawType;

	// Currently the experimental GS will only work with triangle prims (and it doesn't do anything
	// other than pass through values from the VS to the FS anyway).
	#if GR_GL_EXPERIMENTAL_GS
	#if 0
	header->fExperimentalGS = gpu->caps().geometryShaderSupport();
	#else
	header->fExperimentalGS = false;
	#endif
	#endif

	if (gpu->caps()->pathRenderingSupport() &&
	GrGpu::IsPathRenderingDrawType(drawType) &&
	gpu->glPathRendering()->texturingMode() == GrGLPathRendering::FixedFunction_TexturingMode) {
	header->fUseFragShaderOnly = true;
	SkASSERT(!optState.hasGeometryProcessor());
	} else {
	header->fUseFragShaderOnly = false;
	}

	bool defaultToUniformInputs = GrGpu::IsPathRenderingDrawType(drawType) \|\|
	GR_GL_NO_CONSTANT_ATTRIBUTES;

	if (!inputColorIsUsed) {
	header->fColorInput = kAllOnes_ColorInput;
	} else if (defaultToUniformInputs && !optState.hasColorVertexAttribute()) {
	header->fColorInput = kUniform_ColorInput;
	} else {
	header->fColorInput = kAttribute_ColorInput;
	SkASSERT(!header->fUseFragShaderOnly);
	}

	bool covIsSolidWhite = !optState.hasCoverageVertexAttribute() &&
	0xffffffff == optState.getCoverageColor();

	if (covIsSolidWhite \|\| !inputCoverageIsUsed) {
	header->fCoverageInput = kAllOnes_ColorInput;
	} else if (defaultToUniformInputs && !optState.hasCoverageVertexAttribute()) {
	header->fCoverageInput = kUniform_ColorInput;
	} else {
	header->fCoverageInput = kAttribute_ColorInput;
	SkASSERT(!header->fUseFragShaderOnly);
	}

	if (optState.readsDst()) {
	SkASSERT(dstCopy \|\| gpu->caps()->dstReadInShaderSupport());
	const GrTexture* dstCopyTexture = NULL;
	if (dstCopy) {
	dstCopyTexture = dstCopy->texture();
	}
	header->fDstReadKey = GrGLFragmentShaderBuilder::KeyForDstRead(dstCopyTexture,
	gpu->glCaps());
	SkASSERT(0 != header->fDstReadKey);
	} else {
	header->fDstReadKey = 0;
	}

	if (optState.readsFragPosition()) {
	header->fFragPosKey = GrGLFragmentShaderBuilder::KeyForFragmentPosition(
	optState.getRenderTarget(), gpu->glCaps());
	} else {
	header->fFragPosKey = 0;
	}

	// Record attribute indices
	header->fPositionAttributeIndex = optState.positionAttributeIndex();
	header->fLocalCoordAttributeIndex = optState.localCoordAttributeIndex();

	// For constant color and coverage we need an attribute with an index beyond those already set
	int availableAttributeIndex = optState.getVertexAttribCount();
	if (optState.hasColorVertexAttribute()) {
	header->fColorAttributeIndex = optState.colorVertexAttributeIndex();
	} else if (GrGLProgramDesc::kAttribute_ColorInput == header->fColorInput) {
	SkASSERT(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
	header->fColorAttributeIndex = availableAttributeIndex;
	availableAttributeIndex++;
	} else {
	header->fColorAttributeIndex = -1;
	}

	if (optState.hasCoverageVertexAttribute()) {
	header->fCoverageAttributeIndex = optState.coverageVertexAttributeIndex();
	} else if (GrGLProgramDesc::kAttribute_ColorInput == header->fCoverageInput) {
	SkASSERT(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
	header->fCoverageAttributeIndex = availableAttributeIndex;
	} else {
	header->fCoverageAttributeIndex = -1;
	}

	header->fPrimaryOutputType = optState.getPrimaryOutputType();
	header->fSecondaryOutputType = optState.getSecondaryOutputType();

	for (int s = 0; s < optState.numColorStages(); ++s) {
	colorStages->push_back(&optState.getColorStage(s));
	}
	for (int s = 0; s < optState.numCoverageStages(); ++s) {
	coverageStages->push_back(&optState.getCoverageStage(s));
	}

	header->fColorEffectCnt = colorStages->count();
	header->fCoverageEffectCnt = coverageStages->count();

	desc->finalize();
	return true;
	}

	void GrGLProgramDesc::finalize() {
	int keyLength = fKey.count();
	SkASSERT(0 == (keyLength % 4));
	*this->atOffset<uint32_t, kLengthOffset>() = SkToU32(keyLength);

	uint32_t* checksum = this->atOffset<uint32_t, kChecksumOffset>();
	*checksum = 0;
	checksum = SkChecksum::Compute(reinterpret_cast<uint32_t>(fKey.begin()), keyLength);
	}

	GrGLProgramDesc& GrGLProgramDesc::operator= (const GrGLProgramDesc& other) {
	size_t keyLength = other.keyLength();
	fKey.reset(keyLength);
	memcpy(fKey.begin(), other.fKey.begin(), keyLength);
	return *this;
	}