Refactor LiveIntervals::renameDisconnectedComponents() to be a pass.
Also change the name to "RenameIndependentSubregs":
- renameDisconnectedComponents() worked on a MachineFunction at a time
so it is a natural candidate for a machine function pass.
- The algorithm is testable with a .mir test now.
- This also fixes a problem where the lazy renaming as part of the
MachineScheduler introduced IMPLICIT_DEF instructions after the number
of a nodes in a region were counted leading to a mismatch.
Differential Revision: http://reviews.llvm.org/D20507
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271345 91177308-0d34-0410-b5e6-96231b3b80d8
