[HardwareLoops] Optimisation remarks

Authored by SjoerdMeijer on Wed, Oct 16, 2:09 AM.


[HardwareLoops] Optimisation remarks

This adds the initial plumbing to support optimisation remarks in
the IR hardware-loop pass.

I have left a todo in a comment where we can improve the reporting,
and will iterate on that now that we have this initial support in.

Differential Revision: https://reviews.llvm.org/D68579

llvm-svn: 374980