InterleaveAccessPass: Avoid constructing invalid shuffle masks

Fix a bug where we would construct shufflevector instructions addressing
invalid elements.

Differential Revision: https://reviews.llvm.org/D29313

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293673 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed