Re: [RFC][PATCH 3/3] math128, x86_64: Implement {mult,add}_u128 in64bit asm

From: H. Peter Anvin
Date: Tue Apr 24 2012 - 13:17:33 EST


On 04/24/2012 09:36 AM, Peter Zijlstra wrote:
> On Tue, 2012-04-24 at 09:34 -0700, H. Peter Anvin wrote:
>> On 04/24/2012 09:10 AM, Peter Zijlstra wrote:
>>
>> Are you sure that gcc won't simply generate this code already if given
>> "unsigned __int128"?
>
> It might, but I've been told some GCC versions had issues, also lots of
> archs fall back to libgcc functions.
>

Yes, but this is specific to x86-64. If gcc can generate the code it
can also schedule the code, which it can't for assembly...

-hpa


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