store operation on a truncated memory (load) of vXi1 is poorly supported by LLVM and most of the time end with an assertion.
This patch fixes this issue.
Differential Revision: https://reviews.llvm.org/D39547
Change-Id: Ida5523dd09c1ad384acc0a27e9e59273d28cbdc9
llvm-svn: 320691
Michael Zuckerman