reflector.h

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef FLUTTER_IMPELLER_COMPILER_REFLECTOR_H_
#define FLUTTER_IMPELLER_COMPILER_REFLECTOR_H_
 
#include <cstdint>
#include <memory>
#include <optional>
 
#include "flutter/fml/mapping.h"
#include "fml/logging.h"
#include "impeller/compiler/compiler_backend.h"
#include "impeller/compiler/runtime_stage_data.h"
#include "impeller/compiler/shader_bundle_data.h"
#include "inja/inja.hpp"
#include "spirv_common.hpp"
#include "spirv_msl.hpp"
#include "spirv_parser.hpp"
 
namespace impeller {
namespace compiler {
 
struct StructMember {
  // Runtime stages on Vulkan use this information to validate that a struct
  // only contains floats and encode where padding gets inserted.
  enum class UnderlyingType {
    kPadding,
    kFloat,
    kOther,
  };
 
  std::string type;
  spirv_cross::SPIRType::BaseType base_type;
  std::string name;
  size_t offset = 0u;
  size_t size = 0u;
  size_t byte_length = 0u;
  std::optional<size_t> array_elements = std::nullopt;
  size_t element_padding = 0u;
  UnderlyingType underlying_type = UnderlyingType::kOther;
 
  static std::string BaseTypeToString(spirv_cross::SPIRType::BaseType type) {
    using Type = spirv_cross::SPIRType::BaseType;
    switch (type) {
      case Type::Void:
        return "ShaderType::kVoid";
      case Type::Boolean:
        return "ShaderType::kBoolean";
      case Type::SByte:
        return "ShaderType::kSignedByte";
      case Type::UByte:
        return "ShaderType::kUnsignedByte";
      case Type::Short:
        return "ShaderType::kSignedShort";
      case Type::UShort:
        return "ShaderType::kUnsignedShort";
      case Type::Int:
        return "ShaderType::kSignedInt";
      case Type::UInt:
        return "ShaderType::kUnsignedInt";
      case Type::Int64:
        return "ShaderType::kSignedInt64";
      case Type::UInt64:
        return "ShaderType::kUnsignedInt64";
      case Type::AtomicCounter:
        return "ShaderType::kAtomicCounter";
      case Type::Half:
        return "ShaderType::kHalfFloat";
      case Type::Float:
        return "ShaderType::kFloat";
      case Type::Double:
        return "ShaderType::kDouble";
      case Type::Struct:
        return "ShaderType::kStruct";
      case Type::Image:
        return "ShaderType::kImage";
      case Type::SampledImage:
        return "ShaderType::kSampledImage";
      case Type::Sampler:
        return "ShaderType::kSampler";
      default:
        return "ShaderType::kUnknown";
    }
    FML_UNREACHABLE();
  }
 
  static UnderlyingType DetermineUnderlyingType(
      spirv_cross::SPIRType::BaseType type) {
    switch (type) {
      case spirv_cross::SPIRType::Void:
        return UnderlyingType::kPadding;
      case spirv_cross::SPIRType::Float:
        return UnderlyingType::kFloat;
      case spirv_cross::SPIRType::Unknown:
      case spirv_cross::SPIRType::Boolean:
      case spirv_cross::SPIRType::SByte:
      case spirv_cross::SPIRType::UByte:
      case spirv_cross::SPIRType::Short:
      case spirv_cross::SPIRType::UShort:
      case spirv_cross::SPIRType::Int:
      case spirv_cross::SPIRType::UInt:
      case spirv_cross::SPIRType::Int64:
      case spirv_cross::SPIRType::UInt64:
      case spirv_cross::SPIRType::AtomicCounter:
      case spirv_cross::SPIRType::Half:
      case spirv_cross::SPIRType::Double:
      case spirv_cross::SPIRType::Struct:
      case spirv_cross::SPIRType::Image:
      case spirv_cross::SPIRType::SampledImage:
      case spirv_cross::SPIRType::Sampler:
      case spirv_cross::SPIRType::AccelerationStructure:
      case spirv_cross::SPIRType::RayQuery:
      case spirv_cross::SPIRType::ControlPointArray:
      case spirv_cross::SPIRType::Interpolant:
      case spirv_cross::SPIRType::Char:
      default:
        return UnderlyingType::kOther;
    }
    FML_UNREACHABLE();
  }
 
  /// @brief Constructs a new StructMember.
  ///
  /// @param p_type The string type name (e.g. "float", "Point", "Matrix").
  /// @param p_base_type The SPIR-V base type.
  /// @param p_name The name of the struct member.
  /// @param p_offset The offset in bytes from the start of the parent struct.
  /// @param p_size The size in bytes of a single element of this type
  /// (ignoring padding/stride).
  /// @param p_byte_length The total size in bytes this member occupies in
  /// the struct, including all array elements and padding.
  /// @param p_array_elements The number of array elements. For matrices
  /// treated as arrays of columns, this includes the column count.
  /// @param p_element_padding The padding in bytes after each array
  /// element to satisfy alignment requirements (stride - size).
  /// @param p_underlying_type The underlying type category, used for
  /// runtime validation.
  StructMember(std::string p_type,
               spirv_cross::SPIRType::BaseType p_base_type,
               std::string p_name,
               size_t p_offset,
               size_t p_size,
               size_t p_byte_length,
               std::optional<size_t> p_array_elements,
               size_t p_element_padding,
               UnderlyingType p_underlying_type = UnderlyingType::kOther)
      : type(std::move(p_type)),
        base_type(p_base_type),
        name(std::move(p_name)),
        offset(p_offset),
        size(p_size),
        byte_length(p_byte_length),
        array_elements(p_array_elements),
        element_padding(p_element_padding),
        underlying_type(DetermineUnderlyingType(p_base_type)) {}
};
 
class Reflector {
 public:
  struct Options {
    TargetPlatform target_platform = TargetPlatform::kUnknown;
    std::string entry_point_name;
    std::string shader_name;
    std::string header_file_name;
  };
 
  Reflector(Options options,
            const std::shared_ptr<const spirv_cross::ParsedIR>& ir,
            const std::shared_ptr<fml::Mapping>& shader_data,
            const CompilerBackend& compiler);
 
  ~Reflector();
 
  bool IsValid() const;
 
  std::shared_ptr<fml::Mapping> GetReflectionJSON() const;
 
  std::shared_ptr<fml::Mapping> GetReflectionHeader() const;
 
  std::shared_ptr<fml::Mapping> GetReflectionCC() const;
 
  std::shared_ptr<RuntimeStageData::Shader> GetRuntimeStageShaderData() const;
 
  std::shared_ptr<ShaderBundleData> GetShaderBundleData() const;
 
 private:
  struct StructDefinition {
    std::string name;
    size_t byte_length = 0u;
    std::vector<StructMember> members;
  };
 
  struct BindPrototypeArgument {
    std::string type_name;
    std::string argument_name;
  };
 
  struct BindPrototype {
    std::string name;
    std::string return_type;
    std::string docstring;
    std::string descriptor_type = "";
    std::vector<BindPrototypeArgument> args;
  };
 
  const Options options_;
  const std::shared_ptr<const spirv_cross::ParsedIR> ir_;
  const std::shared_ptr<fml::Mapping> shader_data_;
  const CompilerBackend compiler_;
  std::unique_ptr<const nlohmann::json> template_arguments_;
  std::shared_ptr<fml::Mapping> reflection_header_;
  std::shared_ptr<fml::Mapping> reflection_cc_;
  std::shared_ptr<RuntimeStageData::Shader> runtime_stage_shader_;
  std::shared_ptr<ShaderBundleData> shader_bundle_data_;
  bool is_valid_ = false;
 
  std::optional<nlohmann::json> GenerateTemplateArguments() const;
 
  std::shared_ptr<fml::Mapping> GenerateReflectionHeader() const;
 
  std::shared_ptr<fml::Mapping> GenerateReflectionCC() const;
 
  std::shared_ptr<RuntimeStageData::Shader> GenerateRuntimeStageData() const;
 
  std::shared_ptr<ShaderBundleData> GenerateShaderBundleData() const;
 
  std::shared_ptr<fml::Mapping> InflateTemplate(std::string_view tmpl) const;
 
  std::optional<nlohmann::json::object_t> ReflectResource(
      const spirv_cross::Resource& resource,
      std::optional<size_t> offset) const;
 
  std::optional<nlohmann::json::array_t> ReflectResources(
      const spirv_cross::SmallVector<spirv_cross::Resource>& resources,
      bool compute_offsets = false) const;
 
  std::vector<size_t> ComputeOffsets(
      const spirv_cross::SmallVector<spirv_cross::Resource>& resources) const;
 
  std::optional<size_t> GetOffset(spirv_cross::ID id,
                                  const std::vector<size_t>& offsets) const;
 
  std::optional<nlohmann::json::object_t> ReflectType(
      const spirv_cross::TypeID& type_id) const;
 
  nlohmann::json::object_t EmitStructDefinition(
      std::optional<Reflector::StructDefinition> struc) const;
 
  std::optional<StructDefinition> ReflectStructDefinition(
      const spirv_cross::TypeID& type_id) const;
 
  std::vector<BindPrototype> ReflectBindPrototypes(
      const spirv_cross::ShaderResources& resources,
      spv::ExecutionModel execution_model) const;
 
  nlohmann::json::array_t EmitBindPrototypes(
      const spirv_cross::ShaderResources& resources,
      spv::ExecutionModel execution_model) const;
 
  std::optional<StructDefinition> ReflectPerVertexStructDefinition(
      const spirv_cross::SmallVector<spirv_cross::Resource>& stage_inputs)
      const;
 
  std::optional<std::string> GetMemberNameAtIndexIfExists(
      const spirv_cross::SPIRType& parent_type,
      size_t index) const;
 
  std::string GetMemberNameAtIndex(const spirv_cross::SPIRType& parent_type,
                                   size_t index,
                                   std::string suffix = "") const;
 
  std::vector<StructMember> ReadStructMembers(
      const spirv_cross::TypeID& type_id) const;
 
  std::optional<uint32_t> GetArrayElements(
      const spirv_cross::SPIRType& type) const;
 
  template <uint32_t Size>
  uint32_t GetArrayStride(const spirv_cross::SPIRType& struct_type,
                          const spirv_cross::SPIRType& member_type,
                          uint32_t index) const {
    auto element_count = GetArrayElements(member_type).value_or(1);
    if (element_count <= 1) {
      return Size;
    }
    return compiler_->type_struct_member_array_stride(struct_type, index);
  };
 
  Reflector(const Reflector&) = delete;
 
  Reflector& operator=(const Reflector&) = delete;
};
 
}  // namespace compiler
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_COMPILER_REFLECTOR_H_