Reorder operations to remove duplicated work.
Fix to leave floating-point types out of the optimization.
Add tests to predsimplify.ll for SwitchInst and SelectInst handling.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30055 91177308-0d34-0410-b5e6-96231b3b80d8