[IR] Introduce a non-integral pointer type
Summary:
This change adds a `ni` specifier in the `datalayout` string to denote
pointers in some given address spaces as "non-integral", and adds some
typing rules around these special pointers.
Reviewers: majnemer, chandlerc, atrick, dberlin, eli.friedman, tstellarAMD, arsenm
Subscribers: arsenm, mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D22488
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277085
91177308-0d34-0410-b5e6-
96231b3b80d8