[PATCHES] PR18303: Use appropriate Feature flags for encoding instructions

[David Peixotto]

> Updated again at http://git.infradead.org/users/dwmw2/llvm.git — after
> all, I was responsible for a reasonable proportion of the breakage when
> you try to apply it to today's tree, since I've been messing with the
> X86 target.

Wow, thanks for that! I'm afraid we could be stuck in this rebasing loop for a while unless we can build consensus that this is the approach we want to take and get it committed. I'm not really sure how to make that happen.

> In doing so, I note that you didn't change the EmitInstruction() method
> of the AsmPrinter classes to take the additional MCSubtargetInfo& as an
> argument. Is that something we might want to do, even if only for
> symmetry?

Yes that might be a good idea. Right now, I think I grab it from the TargetMachine, but it would probably be more consistent to pass it through EmitInstruction. I'm not sure if that would be sufficient to get it everywhere it needs to be or if we would need to thread it through more places in the AsmPrinter subclasses.