[LV] Pull creation of trip counts into a helper function.

... and do a tad of tidyup while we're at it. Because StartIdx must now be zero, there's no difference between Count and EndIdx.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246633 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed