Eliminate switch cases that can never match, for example removes all
negative switch cases if the branch condition is known to be positive.
Inspired by a recent improvement to GCC's VRP.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152405 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed