[PATCH] critical-anti-dependency breaker: don't use reg def info from kill insts (PR20308)

[Sanjay Patel]

Thanks for the prompt review, Andy. I've added Will Schmidt as a reviewer.

I agree that the output of MachineCopyPropagation looks wrong; yesterday was my first look at that code, so I didn't want to hold up this patch while investigating that. At the least, this patch makes PostRA slightly more efficient by not spending time processing kills.

If it's ok with everyone, I'll add a fixme comment in MachineCopyPropagation, open a new bug, and take a look. If anyone more familiar with that code can help, I'd certainly appreciate it.

http://reviews.llvm.org/D4977