for promoted integer types, eg: i16 on ppc-32, or
i24 on any platform. Complete support for arbitrary
precision integers would require handling expanded
integer types, eg: i128, but I couldn't be bothered.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60834 91177308-0d34-0410-b5e6-96231b3b80d8
