I prefer `vsil_instruction` to avoid, as Zeb said, the implication it mainly contains Vulkan objects.
Are there differences between 'intermediate language' and 'intermediate representation' that favour using IL here?
I don't think so—Henri said on IRC it was mostly for similarity with وکیل, to appeal to my interest in puns and non-utilitarian names, but I didn't catch it because I don't actually know Semitic languages (just 'vizier') Of course, for that matter there's also وصل (wṣl / vasl, "unite/connect").
But yeah, realistically something like vsir/vsil is probably the best/clearest option.