Merging r310604:

Merging r310604:
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r310604 | niravd | 2017-08-10 08:12:32 -0700 (Thu, 10 Aug 2017) | 13 lines

[X86] Keep dependencies when constructing loads in combineStore

Summary:
Preserve chain dependecies between old and new loads constructed to
prevent loads from reordering below later stores.

Fixes PR34088.

Reviewers: craig.topper, spatel, RKSimon, efriedma

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D36528
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_50@310678 91177308-0d34-0410-b5e6-96231b3b80d8