Lift the spill at each irreducible loop block restriction.

It was not intended to have it this way anyway. This also
required to fix GetSiblingAt, to take into account interval
holes, and ConnectSplitSibling to re-materialize a constant
or a method.

Change-Id: Ia5534a93a5413cd0458a251c022d0b655369502b
6 files changed