Comment 6 for bug 1836203

Yes, the "assuming the target has no FPU and then failing to follow the ABI" issue does seem to be specific to llvm 7. llvm 6 doesn't suffer from it and I have a llvm 8 build locally (which I may or may not upload) which also doesn't suffer from it.

rust seems to be overriding the defaults from llvm, so it's only subject to secondary miscompilations, not the primary one.

I'm hoping I can fix this issue llvm 7, failing that it would be possible to flip the default llvm to a different version, but i'm not sure if the risks of that justify the benefits.