I've been working on a SPIR-V virtual machine to get familiar with the spec (and to satisfy my Vulkan related curiosity).

It's very much a work in progress, but it already runs most simple programs. I'm currently working on extended instruction set support (via dlls).

Something that might be useful for others is the SpecParser tool. It downloads the latest HTML version of the spec and generates a lot of definitions from it (more than what is defined in spirv.h)