Subject: [PATCH] [CodeGen] Add pass to combine interleaved loads.

This patch defines an interleaved-load-combine pass. The pass searches
for ShuffleVector instructions that represent interleaved loads. Matches are
converted such that they will be captured by the InterleavedAccessPass.

The pass extends LLVMs capabilities to use target specific instruction
selection of interleaved load patterns (e.g.: ld4 on Aarch64
architectures).

Differential Revision: https://reviews.llvm.org/D52653

llvm-svn: 347208