This patch is the first in a series of 6 patches that split https://reviews.llvm.org/D31240 into more manageable chunks as well as include some additional work that depends on the patch posted by Lei.
The first 4 are really just a split of the functionality in that patch. None of the functionality is turned on in those patches, so they include no test cases. Patches 5 and 6 add further functionality and turn on what the original patch provided. So those two patches are the ones that include the test cases.
This particular one, just provides some of the infrastructure that the others build on - none of the functions here transform any compare instructions.