Move code generators to codegen/ directory.

We are up to having seven distinct types of codegen, and will soon have
an 8th (DSL C++).

Change-Id: I6758328390c234ba1d5c30c118199dbc820af52a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/395817
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/sksl/codegen/SkSLSPIRVCodeGenerator.h b/src/sksl/codegen/SkSLSPIRVCodeGenerator.h
new file mode 100644
index 0000000..5cb2605
--- /dev/null
+++ b/src/sksl/codegen/SkSLSPIRVCodeGenerator.h
@@ -0,0 +1,508 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SKSL_SPIRVCODEGENERATOR
+#define SKSL_SPIRVCODEGENERATOR
+
+#include <stack>
+#include <tuple>
+#include <unordered_map>
+
+#include "include/private/SkSLModifiers.h"
+#include "include/private/SkSLProgramElement.h"
+#include "include/private/SkSLStatement.h"
+#include "src/core/SkOpts.h"
+#include "src/sksl/SkSLMemoryLayout.h"
+#include "src/sksl/SkSLStringStream.h"
+#include "src/sksl/codegen/SkSLCodeGenerator.h"
+#include "src/sksl/ir/SkSLBinaryExpression.h"
+#include "src/sksl/ir/SkSLBoolLiteral.h"
+#include "src/sksl/ir/SkSLConstructor.h"
+#include "src/sksl/ir/SkSLConstructorArray.h"
+#include "src/sksl/ir/SkSLConstructorCompound.h"
+#include "src/sksl/ir/SkSLConstructorCompoundCast.h"
+#include "src/sksl/ir/SkSLConstructorDiagonalMatrix.h"
+#include "src/sksl/ir/SkSLConstructorMatrixResize.h"
+#include "src/sksl/ir/SkSLConstructorScalarCast.h"
+#include "src/sksl/ir/SkSLConstructorSplat.h"
+#include "src/sksl/ir/SkSLConstructorStruct.h"
+#include "src/sksl/ir/SkSLDoStatement.h"
+#include "src/sksl/ir/SkSLFieldAccess.h"
+#include "src/sksl/ir/SkSLFloatLiteral.h"
+#include "src/sksl/ir/SkSLForStatement.h"
+#include "src/sksl/ir/SkSLFunctionCall.h"
+#include "src/sksl/ir/SkSLFunctionDeclaration.h"
+#include "src/sksl/ir/SkSLFunctionDefinition.h"
+#include "src/sksl/ir/SkSLIfStatement.h"
+#include "src/sksl/ir/SkSLIndexExpression.h"
+#include "src/sksl/ir/SkSLIntLiteral.h"
+#include "src/sksl/ir/SkSLInterfaceBlock.h"
+#include "src/sksl/ir/SkSLPostfixExpression.h"
+#include "src/sksl/ir/SkSLPrefixExpression.h"
+#include "src/sksl/ir/SkSLReturnStatement.h"
+#include "src/sksl/ir/SkSLSwitchStatement.h"
+#include "src/sksl/ir/SkSLSwizzle.h"
+#include "src/sksl/ir/SkSLTernaryExpression.h"
+#include "src/sksl/ir/SkSLVarDeclarations.h"
+#include "src/sksl/ir/SkSLVariableReference.h"
+#include "src/sksl/spirv.h"
+
+namespace SkSL {
+
+struct SPIRVNumberConstant {
+    bool operator==(const SPIRVNumberConstant& that) const {
+        return fValueBits == that.fValueBits &&
+               fKind      == that.fKind;
+    }
+    int64_t fValueBits;  // contains either an SKSL_INT or zero-padded bits from an SKSL_FLOAT
+    SkSL::Type::NumberKind fKind;
+};
+
+struct SPIRVVectorConstant {
+    bool operator==(const SPIRVVectorConstant& that) const {
+        return fTypeId     == that.fTypeId &&
+               fValueId[0] == that.fValueId[0] &&
+               fValueId[1] == that.fValueId[1] &&
+               fValueId[2] == that.fValueId[2] &&
+               fValueId[3] == that.fValueId[3];
+    }
+    SpvId fTypeId;
+    SpvId fValueId[4];
+};
+
+}  // namespace SkSL
+
+namespace std {
+
+template <>
+struct hash<SkSL::SPIRVNumberConstant> {
+    size_t operator()(const SkSL::SPIRVNumberConstant& key) const {
+        return key.fValueBits ^ (int)key.fKind;
+    }
+};
+
+template <>
+struct hash<SkSL::SPIRVVectorConstant> {
+    size_t operator()(const SkSL::SPIRVVectorConstant& key) const {
+        return SkOpts::hash(&key, sizeof(key));
+    }
+};
+
+}  // namespace std
+
+namespace SkSL {
+
+/**
+ * Converts a Program into a SPIR-V binary.
+ */
+class SPIRVCodeGenerator : public CodeGenerator {
+public:
+    class LValue {
+    public:
+        virtual ~LValue() {}
+
+        // returns a pointer to the lvalue, if possible. If the lvalue cannot be directly referenced
+        // by a pointer (e.g. vector swizzles), returns -1.
+        virtual SpvId getPointer() { return -1; }
+
+        // Returns true if a valid pointer returned by getPointer represents a memory object
+        // (see https://github.com/KhronosGroup/SPIRV-Tools/issues/2892). Has no meaning if
+        // getPointer() returns -1.
+        virtual bool isMemoryObjectPointer() const { return true; }
+
+        // Applies a swizzle to the components of the LValue, if possible. This is used to create
+        // LValues that are swizzes-of-swizzles. Non-swizzle LValues can just return false.
+        virtual bool applySwizzle(const ComponentArray& components, const Type& newType) {
+            return false;
+        }
+
+        virtual SpvId load(OutputStream& out) = 0;
+
+        virtual void store(SpvId value, OutputStream& out) = 0;
+    };
+
+    SPIRVCodeGenerator(const Context* context,
+                       const Program* program,
+                       ErrorReporter* errors,
+                       OutputStream* out)
+            : INHERITED(program, errors, out)
+            , fContext(*context)
+            , fDefaultLayout(MemoryLayout::k140_Standard)
+            , fCapabilities(0)
+            , fIdCount(1)
+            , fBoolTrue(0)
+            , fBoolFalse(0)
+            , fSetupFragPosition(false)
+            , fCurrentBlock(0)
+            , fSynthetics(errors, /*builtin=*/true) {
+        this->setupIntrinsics();
+    }
+
+    bool generateCode() override;
+
+private:
+    enum IntrinsicKind {
+        kGLSL_STD_450_IntrinsicKind,
+        kSPIRV_IntrinsicKind,
+        kSpecial_IntrinsicKind
+    };
+
+    enum SpecialIntrinsic {
+        kAtan_SpecialIntrinsic,
+        kClamp_SpecialIntrinsic,
+        kMatrixCompMult_SpecialIntrinsic,
+        kMax_SpecialIntrinsic,
+        kMin_SpecialIntrinsic,
+        kMix_SpecialIntrinsic,
+        kMod_SpecialIntrinsic,
+        kDFdy_SpecialIntrinsic,
+        kSaturate_SpecialIntrinsic,
+        kSampledImage_SpecialIntrinsic,
+        kSmoothStep_SpecialIntrinsic,
+        kStep_SpecialIntrinsic,
+        kSubpassLoad_SpecialIntrinsic,
+        kTexture_SpecialIntrinsic,
+    };
+
+    enum class Precision {
+        kDefault,
+        kRelaxed,
+    };
+
+    void setupIntrinsics();
+
+    /**
+     * Pass in the type to automatically add a RelaxedPrecision decoration for the id when
+     * appropriate, or null to never add one.
+     */
+    SpvId nextId(const Type* type);
+
+    SpvId nextId(Precision precision);
+
+    const Type& getActualType(const Type& type);
+
+    SpvId getType(const Type& type);
+
+    SpvId getType(const Type& type, const MemoryLayout& layout);
+
+    SpvId getImageType(const Type& type);
+
+    SpvId getFunctionType(const FunctionDeclaration& function);
+
+    SpvId getPointerType(const Type& type, SpvStorageClass_ storageClass);
+
+    SpvId getPointerType(const Type& type, const MemoryLayout& layout,
+                         SpvStorageClass_ storageClass);
+
+    std::vector<SpvId> getAccessChain(const Expression& expr, OutputStream& out);
+
+    void writeLayout(const Layout& layout, SpvId target);
+
+    void writeLayout(const Layout& layout, SpvId target, int member);
+
+    void writeStruct(const Type& type, const MemoryLayout& layout, SpvId resultId);
+
+    void writeProgramElement(const ProgramElement& pe, OutputStream& out);
+
+    SpvId writeInterfaceBlock(const InterfaceBlock& intf, bool appendRTHeight = true);
+
+    SpvId writeFunctionStart(const FunctionDeclaration& f, OutputStream& out);
+
+    SpvId writeFunctionDeclaration(const FunctionDeclaration& f, OutputStream& out);
+
+    SpvId writeFunction(const FunctionDefinition& f, OutputStream& out);
+
+    void writeGlobalVar(ProgramKind kind, const VarDeclaration& v);
+
+    void writeVarDeclaration(const VarDeclaration& var, OutputStream& out);
+
+    SpvId writeVariableReference(const VariableReference& ref, OutputStream& out);
+
+    int findUniformFieldIndex(const Variable& var) const;
+
+    std::unique_ptr<LValue> getLValue(const Expression& value, OutputStream& out);
+
+    SpvId writeExpression(const Expression& expr, OutputStream& out);
+
+    SpvId writeIntrinsicCall(const FunctionCall& c, OutputStream& out);
+
+    SpvId writeFunctionCall(const FunctionCall& c, OutputStream& out);
+
+
+    void writeGLSLExtendedInstruction(const Type& type, SpvId id, SpvId floatInst,
+                                      SpvId signedInst, SpvId unsignedInst,
+                                      const std::vector<SpvId>& args, OutputStream& out);
+
+    /**
+     * Given a list of potentially mixed scalars and vectors, promotes the scalars to match the
+     * size of the vectors and returns the ids of the written expressions. e.g. given (float, vec2),
+     * returns (vec2(float), vec2). It is an error to use mismatched vector sizes, e.g. (float,
+     * vec2, vec3).
+     */
+    std::vector<SpvId> vectorize(const ExpressionArray& args, OutputStream& out);
+
+    SpvId writeSpecialIntrinsic(const FunctionCall& c, SpecialIntrinsic kind, OutputStream& out);
+
+    SpvId writeConstantVector(const AnyConstructor& c);
+
+    SpvId writeFloatConstructor(const AnyConstructor& c, OutputStream& out);
+
+    SpvId castScalarToFloat(SpvId inputId, const Type& inputType, const Type& outputType,
+                            OutputStream& out);
+
+    SpvId writeIntConstructor(const AnyConstructor& c, OutputStream& out);
+
+    SpvId castScalarToSignedInt(SpvId inputId, const Type& inputType, const Type& outputType,
+                                OutputStream& out);
+
+    SpvId writeUIntConstructor(const AnyConstructor& c, OutputStream& out);
+
+    SpvId castScalarToUnsignedInt(SpvId inputId, const Type& inputType, const Type& outputType,
+                                  OutputStream& out);
+
+    SpvId writeBooleanConstructor(const AnyConstructor& c, OutputStream& out);
+
+    SpvId castScalarToBoolean(SpvId inputId, const Type& inputType, const Type& outputType,
+                              OutputStream& out);
+
+    SpvId castScalarToType(SpvId inputExprId, const Type& inputType, const Type& outputType,
+                           OutputStream& out);
+
+    /**
+     * Writes a matrix with the diagonal entries all equal to the provided expression, and all other
+     * entries equal to zero.
+     */
+    void writeUniformScaleMatrix(SpvId id, SpvId diagonal, const Type& type, OutputStream& out);
+
+    /**
+     * Writes a potentially-different-sized copy of a matrix. Entries which do not exist in the
+     * source matrix are filled with zero; entries which do not exist in the destination matrix are
+     * ignored.
+     */
+    SpvId writeMatrixCopy(SpvId src, const Type& srcType, const Type& dstType, OutputStream& out);
+
+    void addColumnEntry(SpvId columnType, Precision precision, std::vector<SpvId>* currentColumn,
+                        std::vector<SpvId>* columnIds, int* currentCount, int rows, SpvId entry,
+                        OutputStream& out);
+
+    SpvId writeConstructorCompound(const ConstructorCompound& c, OutputStream& out);
+
+    SpvId writeMatrixConstructor(const ConstructorCompound& c, OutputStream& out);
+
+    SpvId writeVectorConstructor(const ConstructorCompound& c, OutputStream& out);
+
+    SpvId writeCompositeConstructor(const AnyConstructor& c, OutputStream& out);
+
+    SpvId writeConstructorDiagonalMatrix(const ConstructorDiagonalMatrix& c, OutputStream& out);
+
+    SpvId writeConstructorMatrixResize(const ConstructorMatrixResize& c, OutputStream& out);
+
+    SpvId writeConstructorScalarCast(const ConstructorScalarCast& c, OutputStream& out);
+
+    SpvId writeConstructorSplat(const ConstructorSplat& c, OutputStream& out);
+
+    SpvId writeConstructorCompoundCast(const ConstructorCompoundCast& c, OutputStream& out);
+
+    SpvId writeComposite(const std::vector<SpvId>& arguments, const Type& type, OutputStream& out);
+
+    SpvId writeFieldAccess(const FieldAccess& f, OutputStream& out);
+
+    SpvId writeSwizzle(const Swizzle& swizzle, OutputStream& out);
+
+    /**
+     * Folds the potentially-vector result of a logical operation down to a single bool. If
+     * operandType is a vector type, assumes that the intermediate result in id is a bvec of the
+     * same dimensions, and applys all() to it to fold it down to a single bool value. Otherwise,
+     * returns the original id value.
+     */
+    SpvId foldToBool(SpvId id, const Type& operandType, SpvOp op, OutputStream& out);
+
+    SpvId writeMatrixComparison(const Type& operandType, SpvId lhs, SpvId rhs, SpvOp_ floatOperator,
+                                SpvOp_ intOperator, SpvOp_ vectorMergeOperator,
+                                SpvOp_ mergeOperator, OutputStream& out);
+
+    SpvId writeStructComparison(const Type& structType, SpvId lhs, Operator op, SpvId rhs,
+                                OutputStream& out);
+
+    SpvId writeArrayComparison(const Type& structType, SpvId lhs, Operator op, SpvId rhs,
+                               OutputStream& out);
+
+    // Used by writeStructComparison and writeArrayComparison to logically combine field-by-field
+    // comparisons into an overall comparison result.
+    // - `a.x == b.x` merged with `a.y == b.y` generates `(a.x == b.x) && (a.y == b.y)`
+    // - `a.x != b.x` merged with `a.y != b.y` generates `(a.x != b.x) || (a.y != b.y)`
+    SpvId mergeComparisons(SpvId comparison, SpvId allComparisons, Operator op, OutputStream& out);
+
+    SpvId writeComponentwiseMatrixBinary(const Type& operandType, SpvId lhs, SpvId rhs,
+                                         SpvOp_ floatOperator, SpvOp_ intOperator,
+                                         OutputStream& out);
+
+    SpvId writeBinaryOperation(const Type& resultType, const Type& operandType, SpvId lhs,
+                               SpvId rhs, SpvOp_ ifFloat, SpvOp_ ifInt, SpvOp_ ifUInt,
+                               SpvOp_ ifBool, OutputStream& out);
+
+    SpvId writeBinaryOperation(const BinaryExpression& expr, SpvOp_ ifFloat, SpvOp_ ifInt,
+                               SpvOp_ ifUInt, OutputStream& out);
+
+    SpvId writeReciprocal(const Type& type, SpvId value, OutputStream& out);
+
+    SpvId writeBinaryExpression(const Type& leftType, SpvId lhs, Operator op,
+                                const Type& rightType, SpvId rhs, const Type& resultType,
+                                OutputStream& out);
+
+    SpvId writeBinaryExpression(const BinaryExpression& b, OutputStream& out);
+
+    SpvId writeTernaryExpression(const TernaryExpression& t, OutputStream& out);
+
+    SpvId writeIndexExpression(const IndexExpression& expr, OutputStream& out);
+
+    SpvId writeLogicalAnd(const Expression& left, const Expression& right, OutputStream& out);
+
+    SpvId writeLogicalOr(const Expression& left, const Expression& right, OutputStream& out);
+
+    SpvId writePrefixExpression(const PrefixExpression& p, OutputStream& out);
+
+    SpvId writePostfixExpression(const PostfixExpression& p, OutputStream& out);
+
+    SpvId writeBoolLiteral(const BoolLiteral& b);
+
+    SpvId writeIntLiteral(const IntLiteral& i);
+
+    SpvId writeFloatLiteral(const FloatLiteral& f);
+
+    void writeStatement(const Statement& s, OutputStream& out);
+
+    void writeBlock(const Block& b, OutputStream& out);
+
+    void writeIfStatement(const IfStatement& stmt, OutputStream& out);
+
+    void writeForStatement(const ForStatement& f, OutputStream& out);
+
+    void writeDoStatement(const DoStatement& d, OutputStream& out);
+
+    void writeSwitchStatement(const SwitchStatement& s, OutputStream& out);
+
+    void writeReturnStatement(const ReturnStatement& r, OutputStream& out);
+
+    void writeCapabilities(OutputStream& out);
+
+    void writeInstructions(const Program& program, OutputStream& out);
+
+    void writeOpCode(SpvOp_ opCode, int length, OutputStream& out);
+
+    void writeWord(int32_t word, OutputStream& out);
+
+    void writeString(const char* string, size_t length, OutputStream& out);
+
+    void writeLabel(SpvId id, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, StringFragment string, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, StringFragment string, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, StringFragment string,
+                          OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3,
+                          OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3, int32_t word4,
+                          OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3, int32_t word4,
+                          int32_t word5, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3, int32_t word4,
+                          int32_t word5, int32_t word6, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3, int32_t word4,
+                          int32_t word5, int32_t word6, int32_t word7, OutputStream& out);
+
+    void writeInstruction(SpvOp_ opCode, int32_t word1, int32_t word2, int32_t word3, int32_t word4,
+                          int32_t word5, int32_t word6, int32_t word7, int32_t word8,
+                          OutputStream& out);
+
+    void writeGeometryShaderExecutionMode(SpvId entryPoint, OutputStream& out);
+
+    MemoryLayout memoryLayoutForVariable(const Variable&) const;
+
+    struct EntrypointAdapter {
+        std::unique_ptr<FunctionDefinition> entrypointDef;
+        std::unique_ptr<FunctionDeclaration> entrypointDecl;
+        Layout fLayout;
+        Modifiers fModifiers;
+    };
+
+    EntrypointAdapter writeEntrypointAdapter(const FunctionDeclaration& main);
+
+    struct UniformBuffer {
+        std::unique_ptr<InterfaceBlock> fInterfaceBlock;
+        std::unique_ptr<Variable> fInnerVariable;
+        std::unique_ptr<Type> fStruct;
+    };
+
+    void writeUniformBuffer(std::shared_ptr<SymbolTable> topLevelSymbolTable);
+
+    const Context& fContext;
+    const MemoryLayout fDefaultLayout;
+
+    uint64_t fCapabilities;
+    SpvId fIdCount;
+    SpvId fGLSLExtendedInstructions;
+    typedef std::tuple<IntrinsicKind, int32_t, int32_t, int32_t, int32_t> Intrinsic;
+    std::unordered_map<String, Intrinsic> fIntrinsicMap;
+    std::unordered_map<const FunctionDeclaration*, SpvId> fFunctionMap;
+    std::unordered_map<const Variable*, SpvId> fVariableMap;
+    std::unordered_map<const Variable*, int32_t> fInterfaceBlockMap;
+    std::unordered_map<String, SpvId> fImageTypeMap;
+    std::unordered_map<String, SpvId> fTypeMap;
+    StringStream fCapabilitiesBuffer;
+    StringStream fGlobalInitializersBuffer;
+    StringStream fConstantBuffer;
+    StringStream fExtraGlobalsBuffer;
+    StringStream fExternalFunctionsBuffer;
+    StringStream fVariableBuffer;
+    StringStream fNameBuffer;
+    StringStream fDecorationBuffer;
+
+    SpvId fBoolTrue;
+    SpvId fBoolFalse;
+    std::unordered_map<SPIRVNumberConstant, SpvId> fNumberConstants;
+    std::unordered_map<SPIRVVectorConstant, SpvId> fVectorConstants;
+    bool fSetupFragPosition;
+    // label of the current block, or 0 if we are not in a block
+    SpvId fCurrentBlock;
+    std::stack<SpvId> fBreakTarget;
+    std::stack<SpvId> fContinueTarget;
+    SpvId fRTHeightStructId = (SpvId) -1;
+    SpvId fRTHeightFieldIndex = (SpvId) -1;
+    SpvStorageClass_ fRTHeightStorageClass;
+    // holds variables synthesized during output, for lifetime purposes
+    SymbolTable fSynthetics;
+    int fSkInCount = 1;
+    // Holds a list of uniforms that were declared as globals at the top-level instead of in an
+    // interface block.
+    UniformBuffer fUniformBuffer;
+    std::vector<const VarDeclaration*> fTopLevelUniforms;
+    std::unordered_map<const Variable*, int> fTopLevelUniformMap; //<var, UniformBuffer field index>
+    SpvId fUniformBufferId = -1;
+
+    friend class PointerLValue;
+    friend class SwizzleLValue;
+
+    using INHERITED = CodeGenerator;
+};
+
+}  // namespace SkSL
+
+#endif