This is the initial checkin of the basic-block autovectorization pass along with some supporting vectorization infrastructure.
Special thanks to everyone who helped review this code over the last several months (especially Tobias Grosser).

llvm-svn: 149468

subdirectories to traverse into.
 - Originally I wanted to avoid this and just autoscan, but this has one key
   flaw in that new subdirectories can not automatically trigger a rerun of the
   llvm-build tool. This is particularly a pain when switching back and forth
   between trees where one has added a subdirectory, as the dependencies will
   tend to be wrong. This will also eliminates FIXME implicitly.

llvm-svn: 146436

llvm-svn: 146409

llvm-svn: 143634