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

Bill Wendling
Tue, 09 Dec 2008 20:58:04 -0000

On Tue, Dec 9, 2008 at 6:11 AM, Zoltan Varga <vargaz at gmail.com>
wrote:
> Hi,
>
>  Here is the next iteration of the patch. The only comment not
> addressed is this one:
>
Thanks! It's looking good.

>> It would be better to implement a target-independent check for
>> overflow for the "Legal" case (like how SADDO does).
Hacker's > Delight
>> has some hints on how to do this. It's not easy for the signed
case,
>> but is do-able.
>
> It can be lowered to a division + a branch, so it would be
> inefficient, plus it would
> be a lot of work to implement it correctly (for me at least).
>
Okay. It would be tricky. Please put a "FIXME" in there indicating
that it would be nice to have at some point. It's okay to submit this.

-bw