[llvm-dev] multiprecision add/sub

[Bagel via llvm-dev]

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>> 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