[FastIsel][X86] Add support for lowering the first 8 floating-point arguments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210719 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][X86] Add support for the sqrt intrinsic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210720 91177308-0d34-0410-b5e6-96231b3b80d8