Fix typo in comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218979 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Refactor the element insertion logic in the new vector shuffle
lowering to handle the potential mirroring of 2-element vectors (because
we can't reliably sort them one way) in the caller rather than in the
insertion logic.

This will simplify things considerably as more ways to fail to match the
insertion are added because now we have a nice try and retry point.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218980 91177308-0d34-0410-b5e6-96231b3b80d8
Revert 202433 - Provide a target override for the latest regalloc heuristic

That commit was introduced in order to help investigate a problem in ARM
codegen breaking from commit 202304 (Add a limit to the heuristic that register
allocates instructions in local order). Recent analisys indicated that the
problem no longer exists, so I'm reverting this change.

See PR18996.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218981 91177308-0d34-0410-b5e6-96231b3b80d8
[sphinx cleanup] Fix unexpected indentation warning introduced by r218937

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218982 91177308-0d34-0410-b5e6-96231b3b80d8