[PATCH] SubRegister liveness tracking

[Andrew Trick]

On Oct 7, 2013, at 2:03 PM, Matthias Braun <mbraun at apple.com> wrote:

> Here is the full patchset to enable subregister liveness tracking in llvm. I did not split all these patches into separate mails because they have to be applied in order and they only really make sense when applied together. For a high-level discussion of the changes, see the mail I sent to the llvmdev mailing list.
> The patches have to be applied after applying the set of cleanups here: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130902/187212.html
> and the last two small patches for ‘covers’ and ‘advanceTo’.

Matthias, this is a really amazing improvement to the infrastructure. I know people working on schedulers have been waiting for it for a long time.

Huge thanks to Renato, Sean, and Vincent for reviewing!

I've reviewed this offline and would like to continue making incremental improvements on trunk rather than blocking the infrastructure. So after addressing Renato's suggestions, whenver you're comfortable with it, I suggest checking this in under a flag so we can work on getting it enabled. AFAIK, the only thing blocking us from enabling it is retrofitting ARM's VMOV widening to use your new liveness utility.

I'd also appreciate it if you can push in your scheduler changes under a flag when you have a chance. The only thing blocking us from doing that is allowing the uber-liverange to be thrown away after coalescing. I want to be able to experiment with that.

-Andy