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Diffstat (limited to 'llvm/docs/DirectX/DXILResources.rst')
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diff --git a/llvm/docs/DirectX/DXILResources.rst b/llvm/docs/DirectX/DXILResources.rst index 91dcd5c8..f253e02f 100644 --- a/llvm/docs/DirectX/DXILResources.rst +++ b/llvm/docs/DirectX/DXILResources.rst @@ -746,3 +746,92 @@ Examples: @llvm.dx.resource.load.cbufferrow.8( target("dx.CBuffer", target("dx.Layout", {i16}, 2, 0)) %buffer, i32 %index) + +Resource dimensions +------------------- + +*relevant types: Textures and Buffer* + +The `getDimensions`_ DXIL operation returns the dimensions of a texture or +buffer resource. It returns a `Dimensions`_ type, which is a struct +containing four ``i32`` values. The values in the struct represent the size +of each dimension of the resource, and when aplicable the number of array +elements or number of samples. The mapping is defined in the +`getDimensions`_ documentation. + +The LLVM IR representation of this operation has several forms +depending on the resource type and the specific ``getDimensions`` query. +The intrinsics return a scalar or anonymous struct with up to 4 `i32` +elements. The intrinsic names include suffixes to indicate the number of +elements in the return value. The suffix `.x` indicates a single `i32` +return value, `.xy` indicates a struct with two `i32` values, and `.xyz` +indicates a struct with three `i32` values. + +Intrinsics representing queries on multisampled texture resources include +`.ms.` in their name and their return value includes an additional `i32` for +the number of samples. + +Intrinsics with `mip_level` argument and `.levels.` in their name are used +for texture resources with multiple MIP levels. Their return +struct includes an additional `i32` for the number of levels the resource has. + +.. code-block:: llvm + + i32 @llvm.dx.resource.getdimensions.x( target("dx.*") handle ) + {i32, i32} @llvm.dx.resource.getdimensions.xy( target("dx.*") handle ) + {i32, i32, i32} @llvm.dx.resource.getdimensions.xyz( target("dx.*") handle ) + {i32, i32} @llvm.dx.resource.getdimensions.levels.x( target("dx.*") handle, i32 mip_level ) + {i32, i32, i32} @llvm.dx.resource.getdimensions.levels.xy( target("dx.*") handle, i32 mip_level ) + {i32, i32, i32, i32} @llvm.dx.resource.getdimensions.levels.xyz( target("dx.*") handle, i32 mip_level ) + {i32, i32, i32} @llvm.dx.resource.getdimensions.ms.xy( target("dx.*") handle ) + {i32, i32, i32, i32} @llvm.dx.resource.getdimensions.ms.xyz( target("dx.*") handle ) + +.. list-table:: ``@llvm.dx.resource.getdimensions.*`` + :header-rows: 1 + + * - Argument + - + - Type + - Description + * - Return value + - + - `i32`, `{i32, i32}`, `{i32, i32, i32}`, or `{i32, i32, i32, i32}` + - Width, height, and depth of the resource (based on the specific suffix), and a number of levels or samples where aplicable. + * - ``%handle`` + - 0 + - ``target(dx.*)`` + - Resource handle + * - ``%mip_level`` + - 1 + - ``i32`` + - MIP level for the requested dimensions. + +Examples: + +.. code-block:: llvm + + ; RWBuffer<float4> + %dim = call i32 @llvm.dx.resource.getdimensions.x(target("dx.TypedBuffer", <4 x float>, 1, 0, 0) %handle) + + ; Texture2D + %0 = call {i32, i32} @llvm.dx.resource.getdimensions.xy(target("dx.Texture", ...) %tex2d) + %tex2d_width = extractvalue {i32, i32} %0, 0 + %tex2d_height = extractvalue {i32, i32} %0, 1 + + ; Texture2DArray with levels + %1 = call {i32, i32, i32, i32} @llvm.dx.resource.getdimensions.levels.xyz( + target("dx.Texture", ...) %tex2darray, i32 1) + %tex2darray_width = extractvalue {i32, i32, i32, i32} %1, 0 + %tex2darray_height = extractvalue {i32, i32, i32, i32} %1, 1 + %tex2darray_elem_count = extractvalue {i32, i32, i32, i32} %1, 2 + %tex2darray_levels_count = extractvalue {i32, i32, i32, i32} %1, 3 + + ; Texture2DMS + %2 = call {i32, i32, i32} @llvm.dx.resource.getdimensions.ms.xy( + target("dx.Texture", ...) %tex2dms) + %tex2dms_width = extractvalue {i32, i32, i32} %2, 0 + %tex2dms_height = extractvalue {i32, i32, i32} %2, 1 + %tex2dms_samples_count = extractvalue {i32, i32, i32} %2, 2 + +.. _Dimensions: https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/DXIL.rst#resource-operation-return-types +.. _getDimensions: https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/DXIL.rst#getdimensions |