[PATH] Add sub.ovf/mul.ovf intrinsics


The attached patch implements sub.ovf/mul.ovf intrinsics similarly to
the recently added add.ovf intrinsics. These are useful for
implementing some vm instructions like sub.ovf/mul.ovf in .NET IL
efficiently. sub.ovf is supported in target independent lowering and
on x86, while mul.ovf is only supported in the x86 backend.

                                        Please review


llvm-ovf.diff (35.6 KB)

Hi Zoltan,

Thanks for the patch. A few comments:

Index: include/llvm/CodeGen/SelectionDAGNodes.h