This is a follow up change for D37569.
Currently the transformation is limited to the case when:
* The loop has a single latch with the condition of the form: ++i <pred> latchLimit, where <pred> is u<, u<=, s<, or s<=.
* The step of the IV used in the latch condition is 1.
* The IV of the latch condition is the same as the post increment IV of the guard condition.
* The guard condition is of the form i u< guardLimit.
This patch enables the transform in the case when the latch is
latchStart + i <pred> latchLimit, where <pred> is u<, u<=, s<, or s<=.
And the guard is
guardStart + i u< guardLimit
Reviewed By: anna
Differential Revision: https://reviews.llvm.org/D39097
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316768 91177308-0d34-0410-b5e6-96231b3b80d8
Artur Pilipenko
c35c11558b