SROA: Generate selects instead of shuffles when blending values because this is the cannonical form.
Shuffles are more difficult to lower and we usually don't touch them, while we do optimize selects more often.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180875 91177308-0d34-0410-b5e6-96231b3b80d8