[llvm-dev] multiprecision add/sub

[Mehdi Amini via llvm-dev]

> On Feb 21, 2017, at 9:54 PM, Nemanja Ivanovic via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> I believe that providing additional intrinsics that would directly produce the ISD::ADDC/ISD::SUBC nodes would provide the additional advantage of being able to directly produce these nodes for code that doesn't have anything to do with multiprecision addition/subtraction. I am not aware of any way currently available to produce IR that will generate these nodes directly.

But what is the use case? What IR pattern it would replace? 

— 
Mehdi




> 
> On Fri, Feb 17, 2017 at 8:52 PM, Bagel via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> On 02/16/2017 12:08 PM, Stephen Canon wrote:
> >> On Feb 16, 2017, at 9:12 AM, Bagel <bagel99 at gmail.com <mailto:bagel99 at gmail.com>
> >> <mailto:bagel99 at gmail.com <mailto:bagel99 at gmail.com>>> wrote:
> >>
> >> I figured that the optimization of this would bedifficult (else it would
> >> have already been done :-))
> >
> > Don’t make this assumption. There’s lots of opportunities for optimization
> > scattered around. Some of them are left because they’re genuinely difficult,
> > but most either simply haven’t been noticed by anyone, or are known but simply
> > haven’t been done because no one has pushed for them (I’m fairly sure that this
> > particular optimization falls into that category—folks have known the codegen
> > wasn't great since these intrinsics were added, but no one has really
> > complained about it, so people have worked on higher-impact stuff).
> 
> But I am still curious as to whether the optimization is architecture
> independent or must be done again for each backend?
> 
> bagel
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170306/d0934382/attachment.html>