[SystemZ] Avoid inserting same value after replication

A minor improvement of buildVector() that skips creating an
INSERT_VECTOR_ELT for a Value which has already been used for the
REPLICATE.

Review: Ulrich Weigand
https://reviews.llvm.org/D54315

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346504 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed