[InstSimplify] fp_binop X, NaN --> NaN

We propagate the existing NaN value when possible.

Differential Revision: https://reviews.llvm.org/D44521



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328140 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed