Well we already still have a similar CPU-based renderer which is the Mesa LLVM-pipe software renderer that also uses the CPU and LLVM to render OpenGL graphics in software.
It appears that SwiftShader is no different here expect that it interestingly comes with a Vulkan software implementation, but I’m not sure if it is faster than LLVM-pipe. I remember another one which is OpenSWR from Intel but this one uses and requires advanced CPU features such as AVX instructions and probably has Intel specific quirks which may exclude some older CPUs.
Unless there are some benchmarks to suggest whether if SwiftShader it is faster or if its a good fit for Haiku, we would probably stick with LLVM-pipe. But for those who want ‘Vulkan’ or ‘Chromium’ on Haiku would probably go for porting SwiftShader anyway.