[X86][AVX] Remove BROADCAST if we only need the 0'th element

We don't catch this with target shuffle simplification if the src/dst types are different.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347386 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed