This allows targets to make more decisions about reserved registers
after isel. For example, now it should be certain there are calls or
stack objects in the frame or not, which could have been introduced by
legalization.
Patch by Matthias Braun
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363757 91177308-0d34-0410-b5e6-96231b3b80d8
