50f534e21c
This commit is using the same mechanism as vk::ext_builtin_input to implement the SV_Position semantic input. The HLSL signature is not yet ready for DXIL, hence this commit only implements the SPIR-V side. This is incomplete as it doesn't allow the semantic on hull/domain and other shaders, but it's a first step to validate the overall input/output semantic logic. Fixes https://github.com/llvm/llvm-project/issues/136969