generated_code.md

Generated Code

There is a lot of code generated in layers/generated/. This is done to prevent errors forgetting to add support for new values when the Vulkan Headers or SPIR-V Grammer is updated.

How to generate the code:

PYTHONPATH=$PYTHONPATH:$PWD/external/Vulkan-Headers/registry python3 scripts/generate_source.py external/Vulkan-Headers/registry/ external/SPIRV-Headers/include/spirv/unified1/

When making change to the scripts/ folder, make sure to run generate_source.py and check in both the changes to scripts/ and layers/generated/ in any PR.

Note the addition of the Vulkan registry directory to PYTHONPATH. This is because the generation scripts depend on modules within the Vulkan registry.

Cmake helper

A helper CMake target VulkanVL_generated_source is also provided to simplify the invocation of scripts/generate_source.py from the build directory:

cmake --build . --target VulkanVL_generated_source

Using the cmake target will also set PYTHONPATH properly, assuming a standard cmake invokation was made.

How it works

generate_source.py sets up the environment and then calls into lvl_genvk.py where each file is generated at a time. Many of the generation scripts will generate both the .cpp source and .h header

The Vulkan code is generated from the vk.xml and uses the python helper functions in the Vulkan-Headers/registry folder.

The SPIR-V code is generated from the SPIR-V Grammer

Tips

If only dealing with a single file, comment out all the other file names in scripts/generate_source.py to speed up testing iterations.