Is eholk no longer active in Rust-land? I remember reading his post [1] about compiling Rust for GPUs (i.e. app code + OpenCL kernels from a single source) back in 2012 and getting quite excited. Presumably generating SPIR-V wouldn't be vastly different in principle.
[1] http://blog.theincredibleholk.org/blog/2012/12/05/compiling-...