Summary:
To be used in `ConstantRange::shlWithNoOverflow()`,
may in future be useful for when saturating shift/mul ops are added.
Unlike `ConstantRange::shl()`, these are precise.
Reviewers: nikic, spatel, reames
Reviewed By: nikic
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69960