The IR verifier currently supports the constrained floating point intrinsics,

but the implementation is hard to extend. It doesn't currently have an
easy way to support intrinsics that, for example, lack a rounding mode.
This will be needed for impending new constrained intrinsics.

This code is split out of D55897 <https://reviews.llvm.org/D55897>, which
itself was split out of D43515 <https://reviews.llvm.org/D43515>.

Reviewed by:	arsenm
Differential Revision:	http://reviews.llvm.org/D59830

llvm-svn: 357065