Recommit "[GlobalISel] Introduce a generic floating point floor opcode, G_FFLOOR""

After r353586, we won't fail on the AMDGPU floor pattern that was killing the
importer before.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353589 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed