OptState owns program descriptor

src/gpu/GrProgramDesc.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrProgramDesc_DEFINED
+#define GrProgramDesc_DEFINED
+
+#include "GrBackendProcessorFactory.h"
+#include "GrColor.h"
+#include "GrTypesPriv.h"
+#include "SkChecksum.h"
+
+class GrGpuGL;
+
+/** This class describes a program to generate. It also serves as a program cache key. Very little
+    of this is GL-specific. The GL-specific parts could be factored out into a subclass. */
+class GrProgramDesc {
+public:
+    // Creates an uninitialized key that must be populated by GrGpu::buildProgramDesc()
+    GrProgramDesc() {}
+
+    // Returns this as a uint32_t array to be used as a key in the program cache.
+    const uint32_t* asKey() const {
+        return reinterpret_cast<const uint32_t*>(fKey.begin());
+    }
+
+    // Gets the number of bytes in asKey(). It will be a 4-byte aligned value. When comparing two
+    // keys the size of either key can be used with memcmp() since the lengths themselves begin the
+    // keys and thus the memcmp will exit early if the keys are of different lengths.
+    uint32_t keyLength() const { return *this->atOffset<uint32_t, kLengthOffset>(); }
+
+    // Gets the a checksum of the key. Can be used as a hash value for a fast lookup in a cache.
+    uint32_t getChecksum() const { return *this->atOffset<uint32_t, kChecksumOffset>(); }
+
+    GrProgramDesc& operator= (const GrProgramDesc& other) {
+        size_t keyLength = other.keyLength();
+        fKey.reset(keyLength);
+        memcpy(fKey.begin(), other.fKey.begin(), keyLength);
+        return *this;
+    }
+
+    bool operator== (const GrProgramDesc& other) const {
+        // The length is masked as a hint to the compiler that the address will be 4 byte aligned.
+        return 0 == memcmp(this->asKey(), other.asKey(), this->keyLength() & ~0x3);
+    }
+
+    bool operator!= (const GrProgramDesc& other) const {
+        return !(*this == other);
+    }
+
+    static bool Less(const GrProgramDesc& a, const GrProgramDesc& b) {
+        return memcmp(a.asKey(), b.asKey(), a.keyLength() & ~0x3) < 0;
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// @name Stage Output Types
+    ////
+
+    enum PrimaryOutputType {
+        // Modulate color and coverage, write result as the color output.
+        kModulate_PrimaryOutputType,
+        // Combines the coverage, dst, and color as coverage * color + (1 - coverage) * dst. This
+        // can only be set if fDstReadKey is non-zero.
+        kCombineWithDst_PrimaryOutputType,
+
+        kPrimaryOutputTypeCnt,
+    };
+
+    enum SecondaryOutputType {
+        // There is no secondary output
+        kNone_SecondaryOutputType,
+        // Writes coverage as the secondary output. Only set if dual source blending is supported
+        // and primary output is kModulate.
+        kCoverage_SecondaryOutputType,
+        // Writes coverage * (1 - colorA) as the secondary output. Only set if dual source blending
+        // is supported and primary output is kModulate.
+        kCoverageISA_SecondaryOutputType,
+        // Writes coverage * (1 - colorRGBA) as the secondary output. Only set if dual source
+        // blending is supported and primary output is kModulate.
+        kCoverageISC_SecondaryOutputType,
+
+        kSecondaryOutputTypeCnt,
+    };
+
+    // Specifies where the initial color comes from before the stages are applied.
+    enum ColorInput {
+        kAllOnes_ColorInput,
+        kAttribute_ColorInput,
+        kUniform_ColorInput,
+
+        kColorInputCnt
+    };
+
+    struct KeyHeader {
+        uint8_t                     fDstReadKey;   // set by GrGLShaderBuilder if there
+                                                   // are effects that must read the dst.
+                                                   // Otherwise, 0.
+        uint8_t                     fFragPosKey;   // set by GrGLShaderBuilder if there are
+                                                   // effects that read the fragment position.
+                                                   // Otherwise, 0.
+
+        SkBool8                     fEmitsPointSize;
+
+        ColorInput                  fColorInput : 8;
+        ColorInput                  fCoverageInput : 8;
+
+        PrimaryOutputType           fPrimaryOutputType : 8;
+        SecondaryOutputType         fSecondaryOutputType : 8;
+
+        int8_t                      fPositionAttributeIndex;
+        int8_t                      fLocalCoordAttributeIndex;
+        int8_t                      fColorAttributeIndex;
+        int8_t                      fCoverageAttributeIndex;
+
+        SkBool8                     fHasGeometryProcessor;
+        int8_t                      fColorEffectCnt;
+        int8_t                      fCoverageEffectCnt;
+    };
+
+
+    bool hasGeometryProcessor() const {
+        return SkToBool(this->header().fHasGeometryProcessor);
+    }
+
+    int numColorEffects() const {
+        return this->header().fColorEffectCnt;
+    }
+
+    int numCoverageEffects() const {
+        return this->header().fCoverageEffectCnt;
+    }
+
+    int numTotalEffects() const { return this->numColorEffects() + this->numCoverageEffects(); }
+
+    // This should really only be used internally, base classes should return their own headers
+    const KeyHeader& header() const { return *this->atOffset<KeyHeader, kHeaderOffset>(); }
+
+    /** Used to provide effects' keys to their emitCode() function. */
+    class ProcKeyProvider {
+    public:
+        enum ProcessorType {
+            kGeometry_ProcessorType,
+            kFragment_ProcessorType,
+        };
+
+        ProcKeyProvider(const GrProgramDesc* desc, ProcessorType type, int effectOffset)
+            : fDesc(desc), fBaseIndex(0), fEffectOffset(effectOffset) {
+            switch (type) {
+                case kGeometry_ProcessorType:
+                    // there can be only one
+                    fBaseIndex = 0;
+                    break;
+                case kFragment_ProcessorType:
+                    fBaseIndex = desc->hasGeometryProcessor() ? 1 : 0;
+                    break;
+            }
+        }
+
+        GrProcessorKey get(int index) const {
+            const uint16_t* offsetsAndLengths = reinterpret_cast<const uint16_t*>(
+                fDesc->fKey.begin() + fEffectOffset);
+            // We store two uint16_ts per effect, one for the offset to the effect's key and one for
+            // its length. Here we just need the offset.
+            uint16_t offset = offsetsAndLengths[2 * (fBaseIndex + index) + 0];
+            uint16_t length = offsetsAndLengths[2 * (fBaseIndex + index) + 1];
+            // Currently effects must add to the key in units of uint32_t.
+            SkASSERT(0 == (length % sizeof(uint32_t)));
+            return GrProcessorKey(reinterpret_cast<const uint32_t*>(fDesc->fKey.begin() + offset),
+                               length / sizeof(uint32_t));
+        }
+    private:
+        const GrProgramDesc*  fDesc;
+        int                   fBaseIndex;
+        int                   fEffectOffset;
+    };
+
+    // A struct to communicate descriptor information to the program descriptor builder
+    struct DescInfo {
+        int positionAttributeIndex() const {
+            return fFixedFunctionVertexAttribIndices[kPosition_GrVertexAttribBinding];
+        }
+        int localCoordAttributeIndex() const {
+            return fFixedFunctionVertexAttribIndices[kLocalCoord_GrVertexAttribBinding];
+        }
+        int colorVertexAttributeIndex() const {
+            return fFixedFunctionVertexAttribIndices[kColor_GrVertexAttribBinding];
+        }
+        int coverageVertexAttributeIndex() const {
+            return fFixedFunctionVertexAttribIndices[kCoverage_GrVertexAttribBinding];
+        }
+        bool hasLocalCoordAttribute() const {
+            return -1 != fFixedFunctionVertexAttribIndices[kLocalCoord_GrVertexAttribBinding];
+        }
+        bool hasColorVertexAttribute() const {
+            return -1 != fFixedFunctionVertexAttribIndices[kColor_GrVertexAttribBinding];
+        }
+        bool hasCoverageVertexAttribute() const {
+            return -1 != fFixedFunctionVertexAttribIndices[kCoverage_GrVertexAttribBinding];
+        }
+
+        int fFixedFunctionVertexAttribIndices[kGrFixedFunctionVertexAttribBindingCnt];
+
+        // These flags are needed to protect the code from creating an unused uniform color/coverage
+        // which will cause shader compiler errors.
+        bool            fInputColorIsUsed;
+        bool            fInputCoverageIsUsed;
+
+        // These flags give aggregated info on the processor stages that are used when building
+        // programs.
+        bool            fReadsDst;
+        bool            fReadsFragPosition;
+        bool            fRequiresLocalCoordAttrib;
+
+        // Fragment shader color outputs
+        GrProgramDesc::PrimaryOutputType  fPrimaryOutputType : 8;
+        GrProgramDesc::SecondaryOutputType  fSecondaryOutputType : 8;
+    };
+
+private:
+    template<typename T, size_t OFFSET> T* atOffset() {
+        return reinterpret_cast<T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
+    }
+
+    template<typename T, size_t OFFSET> const T* atOffset() const {
+        return reinterpret_cast<const T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
+    }
+
+    void finalize() {
+        int keyLength = fKey.count();
+        SkASSERT(0 == (keyLength % 4));
+        *(this->atOffset<uint32_t, GrProgramDesc::kLengthOffset>()) = SkToU32(keyLength);
+
+        uint32_t* checksum = this->atOffset<uint32_t, GrProgramDesc::kChecksumOffset>();
+        *checksum = 0;
+        *checksum = SkChecksum::Compute(reinterpret_cast<uint32_t*>(fKey.begin()), keyLength);
+    }
+
+    // The key, stored in fKey, is composed of four parts:
+    // 1. uint32_t for total key length.
+    // 2. uint32_t for a checksum.
+    // 3. Header struct defined above.  Also room for extensions to the header
+    // 4. A Backend specific payload.  Room is preallocated for this
+    enum KeyOffsets {
+        // Part 1.
+        kLengthOffset = 0,
+        // Part 2.
+        kChecksumOffset = kLengthOffset + sizeof(uint32_t),
+        // Part 3.
+        kHeaderOffset = kChecksumOffset + sizeof(uint32_t),
+        kHeaderSize = SkAlign4(2 * sizeof(KeyHeader)),
+    };
+
+    enum {
+        kMaxPreallocProcessors = 8,
+        kIntsPerProcessor      = 4,    // This is an overestimate of the average effect key size.
+        kPreAllocSize = kHeaderOffset + kHeaderSize +
+                        kMaxPreallocProcessors * sizeof(uint32_t) * kIntsPerProcessor,
+    };
+
+    SkSTArray<kPreAllocSize, uint8_t, true> fKey;
+
+    friend class GrGLProgramDescBuilder;
+};
+
+#endif