[X86][SSE] Add support for combining target shuffles to binary BLEND

We already had support for 1-input BLEND with zero - this adds support for 2-input BLEND as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283040 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed