This class is meant to be the primary interface for examining a live
range in the vicinity on a given instruction. It avoids all the messy
dealings with iterators and early clobbers.
This is a more abstract interface to live ranges, hiding the
implementation as a vector of segments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157141 91177308-0d34-0410-b5e6-96231b3b80d8