Merging r275869:

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r275869 | arsenm | 2016-07-18 11:34:53 -0700 (Mon, 18 Jul 2016) | 7 lines

AMDGPU: Remove dead check in AMDGPUPromoteAlloca

This is currently only called with GEP users. A direct
alloca would only happen with current typed pointers
for arrays which are a perverse case.

Also fix crashes on 0 x and 1 x arrays.
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llvm-svn: 277077