[PATCH] [AArch64] Fix a build_vector pattern fail caused by defect in isBuildVectorAllZeros().

[Tim Northover]

Hi Kevin,

> So my suggestion is don't treat that node problematic, we should get our backend correctly handle that node as well.

Agreed. That's exactly what I meant. It could come up via some other route so we need to be able to handle it.

Cheers.

Tim.

http://reviews.llvm.org/D4228