[DAGCombiner] Don't add volatile or indexed stores to ChainedStores

Summary:
findBetterNeighborChains does not handle volatile or indexed stores.
However, it did not check when adding stores to ChainedStores.

Reviewers: arsenm

Differential Revision: http://reviews.llvm.org/D16463


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259024 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed