Re: [patch 5/6] [RFD] timekeeping: Provide optional 128bit math

Chris Metcalf
2016-12-09T17:37:04Z

On 12/9/2016 5:18 AM, Peter Zijlstra wrote:
> On Fri, Dec 09, 2016 at 07:38:47AM +0100, Peter Zijlstra wrote:
>
>> Turns out using GCC-6.2.1 we have the same problem on i386, GCC doesn't
>> recognise the 32x32 mults and generates crap.
>>
>> This used to work :/
> I tried:
>
> gcc-4.4: good
> gcc-4.6, gcc-4.8, gcc-5.4, gcc-6.2: bad

I also found 4.4 was good on tilegx at recognizing the 32x32, and bad on
the later versions I tested; I don't recall which specific later versions I
tried, though.

--
Chris Metcalf, Mellanox Technologies