Summary:
This PR contains the initial version of Vulkan (GPU) Backend integration.
The primary target environment is Android, but the desktop build is also supported.
## CMake
Introducing three cmake options:
USE_VULKAN:
The main switch, if it is off, all other options do not affect.
USE_VULKAN_WRAPPER:
ON - Vulkan will be used loading it at runtime as "libvulkan.so" using libdl, every function call is wrapped in vulkan_wrapper.h.
OFF - linking with libvulkan.so directly
USE_VULKAN_SHADERC_RUNTIME:
ON - Shader compilation library will be linked, and shaders will be compiled runtime.
OFF - Shaders will be precompiled and shader compilation library is not included.
## Codegen
if `USE_VULKAN_SHADERC_RUNTIME` is ON:
Shaders precompilation () starts in cmake/VulkanCodegen.cmake, which calls `aten/src/ATen/native/vulkan/gen_glsl.py` or `aten/src/ATen/native/vulkan/gen_spv.py` to include shaders source or SPIR-V bytecode inside binary as uint32_t array in spv.h,spv.cpp.
if `USE_VULKAN_SHADERC_RUNTIME` is OFF:
The source of shaders is included as `glsl.h`,`glsl.cpp`.
All codegen results happen in the build directory.
## Build dependencies
cmake/Dependencies.cmake
If the target platform is Android - vulkan library, headers, Vulkan wrapper will be used from ANDROID_NDK.
Desktop build requires the VULKAN_SDK environment variable, and all vulkan dependencies will be used from it.
(Desktop build was tested only on Linux).
## Pytorch integration:
Adding 'Vulkan" as new Backend, DispatchKey, DeviceType.
We are using Strided layout without supporting strides at the moment, but we plan to support them in the future.
Using OpaqueTensorImpl where OpaqueHandle is copyable VulkanTensor,
more details in comments in `aten/src/ATen/native/vulkan/Vulkan.h`
Main code location: `aten/src/ATen/native/vulkan`
`aten/src/ATen/native/vulkan/VulkanAten.cpp` - connection link between ATen and Vulkan api (Vulkan.h) that converts at::Tensor to VulkanTensor.
`aten/src/ATen/native/Vulkan/Vulkan.h` - Vulkan API that contains VulkanTensor representation and functions to work with it. Plan to expose it for clients to be able to write their own Vulkan Ops.
`aten/src/ATen/native/vulkan/VulkanOps.cpp` - Vulkan Operations Implementations that uses Vulkan.h API
## GLSL shaders
Located in `aten/src/ATen/native/vulkan/glsl` as *.glsl files.
All shaders use Vulkan specialized constants for workgroup sizes with ids 1, 2, 3
## Supported operations
Code point:
conv2d no-groups
conv2d depthwise
addmm
upsample nearest 2d
clamp
hardtanh
## Testing
`aten/src/ATen/test/vulkan_test.cpp` - contains tests for
copy from CPU to Vulkan and back
all supported operations
Desktop builds supported, and testing can be done on a desktop that has Vulkan supported GPU or with installed software implementation of Vulkan, like https://github.com/google/swiftshader
## Vulkan execution
The initial implementation is trivial and waits every operator's execution.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36491
Differential Revision: D21696709
Pulled By: IvanKobzarev
fbshipit-source-id: da3e5a770b1a1995e9465d7e81963e7de56217fa
