llvm/mlir/include/mlir/Dialect/SPIRV/Utils/LayoutUtils.h

//===-- LayoutUtils.h - Vulkan Layout Util functions ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines utilities used to get alignment and layout information for
// types in SPIR-V dialect.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_DIALECT_SPIRV_UTILS_LAYOUTUTILS_H_
#define MLIR_DIALECT_SPIRV_UTILS_LAYOUTUTILS_H_

#include <cstdint>

namespace mlir {
class Type;
class VectorType;

namespace spirv {
class ArrayType;
class RuntimeArrayType;
class StructType;
} // namespace spirv

/// According to the Vulkan spec "15.6.4. Offset and Stride Assignment":
/// "There are different alignment requirements depending on the specific
/// resources and on the features enabled on the device."
///
/// There are 3 types of alignment: scalar, base, extended.
/// See the spec for details.
///
/// Note: Even if scalar alignment is supported, it is generally more
/// performant to use the base alignment. So here the calculation is based on
/// base alignment.
///
/// The memory layout must obey the following rules:
/// 1. The Offset decoration of any member must be a multiple of its alignment.
/// 2. Any ArrayStride or MatrixStride decoration must be a multiple of the
/// alignment of the array or matrix as defined above.
///
/// According to the SPIR-V spec:
/// "The ArrayStride, MatrixStride, and Offset decorations must be large
/// enough to hold the size of the objects they affect (that is, specifying
/// overlap is invalid)."
class VulkanLayoutUtils { … };

} // namespace mlir

#endif // MLIR_DIALECT_SPIRV_UTILS_LAYOUTUTILS_H_