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This adds a new document about DXIL Resource Handling. I've attempted to describe here how we intend to use TargetExtTypes to represent resources in LLVM IR and the various intrinsics we'll need to lower these through LLVM to DXIL. For now this document is limited to the high level concepts and a few details on buffer types, and there are a number of TODOs in the document that we'll iterate on as we progress in the implementation.
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97 lines
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=================================
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User Guide for the DirectX Target
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=================================
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.. warning::
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Disclaimer: The DirectX backend is experimental and under active development.
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It is not yet feature complete or ready to be used outside of experimental or
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demonstration contexts.
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.. contents::
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:local:
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.. toctree::
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:hidden:
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DirectX/DXContainer
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DirectX/DXILArchitecture
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DirectX/DXILOpTableGenDesign
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DirectX/DXILResources
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Introduction
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============
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The DirectX target implements the DirectX programmability interfaces. These
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interfaces are documented in the `DirectX Specifications. <https://github.com/Microsoft/DirectX-Specs>`_
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Initially the backend is aimed at supporting DirectX 12, and support for DirectX
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11 is planned at a later date.
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The DirectX backend is currently experimental and is not shipped with any
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release builds of LLVM tools. To enable building the DirectX backend locally add
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``DirectX`` to the ``LLVM_EXPERIMENTAL_TARGETS_TO_BUILD`` CMake option. For more
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information on building LLVM see the :doc:`CMake` documentation.
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.. _dx-target-triples:
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Target Triples
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==============
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At present the DirectX target only supports the ``dxil`` architecture, which
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generates code for the
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`DirectX Intermediate Language. <https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/DXIL.rst>`_
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In addition to target architecture, the DirectX backend also needs to know the
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target runtime version and pipeline stage. These are expressed using the OS and
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Environment triple component.
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Presently the DirectX backend requires targeting the ``shadermodel`` OS, and
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supports versions 6.0+ (at time of writing the latest announced version is 6.7).
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.. table:: DirectX Environments
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================== ========================================================
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Environment Description
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================== ========================================================
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``pixel`` Pixel shader
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``vertex`` Vertex shader
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``geometry`` Geometry shader
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``hull`` Hull shader (tesselation)
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``domain`` Domain shader (tesselation)
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``compute`` Compute kernel
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``library`` Linkable ``dxil`` library
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``raygeneration`` Ray generation (ray tracing)
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``intersection`` Ray intersection (ray tracing)
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``anyhit`` Ray any collision (ray tracing)
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``closesthit`` Ray closest collision (ray tracing)
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``miss`` Ray miss (ray tracing)
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``callable`` Callable shader (ray tracing)
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``mesh`` Mesh shader
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``amplification`` Amplification shader
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================== ========================================================
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Output Binaries
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===============
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The DirectX runtime APIs read a file format based on the
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`DirectX Specification. <https://github.com/Microsoft/DirectX-Specs>`_. In
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different codebases the file format is referred to by different names
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(specifically ``DXBC`` and ``DXILContainer``). Since the format is used to store
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both ``DXBC`` and ``DXIL`` outputs, and the ultimate goal is to support both as
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code generation targets in LLVM, the LLVM codebase uses a more neutral name,
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``DXContainer``.
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The ``DXContainer`` format is sparsely documented in the functional
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specification, but a reference implementation exists in the
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`DirectXShaderCompiler. <https://github.com/microsoft/DirectXShaderCompiler>`_.
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The format is documented in the LLVM project docs as well (see
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:doc:`DirectX/DXContainer`).
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Support for generating ``DXContainer`` files in LLVM, is being added to the LLVM
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MC layer for object streamers and writers, and to the Object and ObjectYAML
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libraries for testing and object file tooling.
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For ``dxil`` targeting, bitcode emission into ``DXContainer`` files follows a
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similar model to the ``-fembed-bitcode`` flag supported by clang for other
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targets.
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