Merging r321991:

Merging r321991:
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r321991 | sam_parker | 2018-01-08 05:21:24 -0800 (Mon, 08 Jan 2018) | 9 lines

[DAGCombine] Fix for PR35761

I had falsely assumed that constant operands would be operand(1) of
the bin ops that may need their constant operand to be masked.

Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=35761

Differential Revision: https://reviews.llvm.org/D41667

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@322670 91177308-0d34-0410-b5e6-96231b3b80d8