GlobalISel: fix legalization of G_INSERT

We were calculating incorrect extract/insert offsets by trying to be too
tricksy with min/max. It's clearer to just split the logic up into "register
starts before this segment" vs "after".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297226 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed