[ADT] IntervalMap: add overlaps(a, b) method

Summary:
This function checks whether the mappings in the interval map overlap
with the given range [a;b]. The motivation is to enable checking for
overlap before inserting a new interval into the map.

Reviewers: vsk, dblaikie

Subscribers: dexonsmith, kristina, llvm-commits

Differential Revision: https://reviews.llvm.org/D55760

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349898 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed