isSafeToSpeculativelyExecute. The new method is a bit closer to what
the callers actually care about in that it rejects more things callers
don't want. It also adds more precise handling for integer
division, and unifies code for analyzing the legality of a speculative
load.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76150 91177308-0d34-0410-b5e6-96231b3b80d8