Now register parameters that aren't saved to the stack or CSRs are
considered dead after the first call. Previously the debugger would show
whatever was in the register.
Fixes PR26589
Reviewers: aprantl
Differential Revision: http://reviews.llvm.org/D17211
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264429 91177308-0d34-0410-b5e6-96231b3b80d8