Reapply [FastISel][X86] Use XOR to materialize the "0" value (r215594).

Note: This was originally reverted to track down a buildbot error. Reapply
without any modifications.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216011 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed