Merging r339533:

Merging r339533:
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r339533 | ctopper | 2018-08-13 07:26:49 +0200 (Mon, 13 Aug 2018) | 5 lines

[SelectionDAG] In PromoteFloatRes_BITCAST, insert a bitcast before the fp16_to_fp in case the input type isn't an i16.

The bitcast can be further legalized as needed.

Fixes PR38533.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_70@339855 91177308-0d34-0410-b5e6-96231b3b80d8