Merging r372480:

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r372480 | ssarda | 2019-09-21 11:16:37 -0700 (Sat, 21 Sep 2019) | 9 lines

SROA: Check Total Bits of vector type

While Promoting alloca instruction of Vector Type,
Check total size in bits of its slices too.
If they don't match, don't promote the alloca instruction.

Bug : https://bugs.llvm.org/show_bug.cgi?id=42585

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