[DAGCombine] (add/uaddo X, Carry) -> (addcarry X, 0, Carry)

Summary:
This enables further transforms.

Depends on D32916

Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D32925

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304401 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed