One of the big things we've been looking forward to with SPIR-V is the to/from LLVM IR pass in order to open up the possibilities for this new industry-standard intermediate representation to be used by Vulkan and OpenCL. Some code will soon be opened up, but it's not the end game.

For weeks there have been public talk by developers on the SPIR-V plans for LLVM. Today there is some fresh material after the involved developers have been communicating with The Khronos Group.

In their discussions they determined they need to create a "fully fledged" back-end that uses all of the LLVM machinery that target back-ends should use. They also determined they'd likely need to develop the SPIR-V to LLVM IR translator as a separate project, similar to Clang being technically separate from LLVM.

However, in wanting to get out SPIR-V code right now, they are going to open-source their current code shortly. This soon-to-be-opened code doesn't comply with the above criteria, but it's a start and will allow them to ship something soon. A full SPIR-V back-end to LLVM is then said to be revisited in the future.

Details via this mailing list post. The code is to appear on KhronosGroup GitHub.