LegalizeDAG: Try to use Overflow operations when expanding ADD/SUB

v2: consider BooleanContents when processing overflow

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewers: resistor, jholewinsky (nvidia parts)
Differential Revision: http://reviews.llvm.org/D6340

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234755 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed