guard fsqrt with fmf sub flags

Summary:
This change uses fmf subflags to guard optimizations as well as unsafe. These changes originated from D46483.
It contains only context for fsqrt.


Reviewers: spatel, hfinkel, arsenm

Reviewed By: spatel

Subscribers: hfinkel, wdng, andrew.w.kaylor, wristow, efriedma, nemanjai

Differential Revision: https://reviews.llvm.org/D47749

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334113 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed