[LSV] Use the original loads' names for the extractelement instructions.

Summary:
LSV replaces multiple adjacent loads with one vectorized load and a
bunch of extractelement instructions.  This patch makes the
extractelement instructions' names match those of the original loads,
for (hopefully) improved readability.

Reviewers: asbirlea, tstellarAMD

Subscribers: arsenm, mzolotukhin

Differential Revision: https://reviews.llvm.org/D23748

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280818 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed