[BPI] Consider deoptimize calls as "unreachable"

Summary:
Calls to @llvm.experimental.deoptimize are expected to "never execute",
so optimize them as such.

Reviewers: chandlerc

Subscribers: junbuml, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D19095

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266654 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed