the same allocation size but different primitive sizes(e.g., <3xi32> and
<4xi32>). When ScalarRepl promotes them, it can't use a bit cast but
should use a shuffle vector instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129472 91177308-0d34-0410-b5e6-96231b3b80d8
