schema.fbs

// Copyright (c) Meta Platforms, Inc. and affiliates.

namespace vkgraph;

// Update after any BC breaking changes.
file_identifier "VK00";

table OperatorCall {
  node_id:uint;
  name:string;
  args:[int];
}

enum VkDataType : byte {
  BOOL = 0,
  UINT8 = 1,
  INT8 = 2,
  INT32 = 3,
  FLOAT16 = 4,
  FLOAT32 = 5,
  FLOAT64 = 6,
  INT64 = 7,
  UNSET = 127,
}

// Describes what kind of GPU resource should be used to represent a tensor. The
// int values assigned to each entry must match the corresponding entry in
// api::StorageType.
enum VkStorageType : ubyte {
  BUFFER = 0,
  TEXTURE_3D = 1,
  TEXTURE_2D = 2,
  DEFAULT_STORAGE = 255,
}

// Describes how memory should be laid out in GPU memory. See the GPUMemoryLayout
// enum class in PyTorch Vulkan for more details. The int values assigned to each
// entry must match the corresponding entry in utils::GPUMemoryLayout.
enum VkMemoryLayout : ubyte {
  TENSOR_WIDTH_PACKED = 0,
  TENSOR_HEIGHT_PACKED = 1,
  TENSOR_CHANNELS_PACKED = 2,
  PACKED_INT8_4W4C = 3,
  PACKED_INT8_4H4W = 4,
  PACKED_INT8_4C1W = 8,
  DEFAULT_LAYOUT = 255,
}

table VkTensor {
  // Type of the tensor elements.
  datatype:VkDataType;
  // Shape dimensions.
  dims:[uint];
  // Index to the program's constant data. Negative indicates tensor is non-constant.
  constant_id:int;
  // Index to the shared memory object. Negative indicates the tensor doesn't share memory.
  mem_obj_id:int;
  // Storage type that should be used to represent this tensor
  storage_type:VkStorageType = DEFAULT_STORAGE;
  // Memory layout that should be used to represent this tensor
  memory_layout:VkMemoryLayout = DEFAULT_LAYOUT;
  // dtype to use for staging buffer. This may be different from the tensor's datatype
  // if force_fp16 is enabled to force all float tensors to be represented as fp16.
  staging_datatype:VkDataType = UNSET;
}

table Null {}

table Int {
  int_val:long;
}

table Bool {
  bool_val:bool;
}

table Double {
  double_val:double;
}

table String {
  string_val:string;
}

table IntList {
  items:[long];
}

table DoubleList {
  items:[double];
}

table BoolList {
  items:[bool];
}

table ValueList {
  items:[int];
}

table SymInt {
  value:int;
}

union GraphTypes {
  Null,
  Int,
  Double,
  Bool,
  VkTensor,
  IntList,
  DoubleList,
  BoolList,
  ValueList,
  String,
  SymInt,
}

table VkValue {
  value:GraphTypes;
}

// Abstraction to represent a region of bytes in a raw data buffer. Useful for referencing raw data
// serialized outside of the flatbuffer.
table VkBytes {
  offset:ulong;
  length:ulong;
  named_key:string;
}

table VkGraph {
  // Schema version.
  version:string;

  // Objects
  chain:[OperatorCall];
  values:[VkValue];

  // Indices
  input_ids:[uint];
  output_ids:[uint];

  // Raw Objects (e.g. weight tensors and custom shaders)
  constants:[VkBytes];
  shaders:[VkBytes];

  // Graph configuration
  // As per flatbuffer BC/FC policy, new fields can be freely added to this
  // section. It is recommended to provide default values, since older blobs
  // without the field will be deserialized with the default value.

  // Sets an override for the storage type and memory layout that will be used
  // to represent a VkTensor if the VkTensor is not serialized with a particular
  // storage type or memory layout setting
  storage_type_override:VkStorageType = DEFAULT_STORAGE;
  memory_layout_override:VkMemoryLayout = DEFAULT_LAYOUT;
}

root_type VkGraph;