Bug#833846: fflas-ffpack: don't generate optimised code based on the build machine

[Doug Torrance]

Control: tags -1 pending

On 08/09/2016 07:53 AM, Ximin Luo wrote:
> Control: severity -1 serious
>
> I was recommended by multiple people to bump the severity of this bug. Also to clarify that i386 should have no optimisation flags, and not "-msse -msse2". My earlier comment was based on a misunderstanding of what "i386 doesn't have mmx" meant; sse and sse2 build on top of mmx.
>
> X
>
> Ximin Luo:
>> Package: fflas-ffpack
>> Version: 2.2.1-1
>> Severity: important
>>
>> Dear Maintainer,
>>
>> fflas-ffpack on amd64 was built with "-msse4.1 -mfma -mavx2" as can be seen
>> from the output of `pkg-config --cflags fflas-ffpack`. This unfortunately makes
>> it crash on amd64 machines that don't support these instructions, and we are
>> running into this issue whilst testing SageMath.
>>
>> Please disable any build options that set optimisations based on autodetection
>> of the CPU features of the build machine.
>>
>> It should be OK to hard-code "-mmmx -msse -msse2" for amd64 and "-msse -msse2"
>> for i386, according to wRAR on #debian-devel. This is somewhat based on
>> information from [1]. There might be other optimisations you can make, but I
>> haven't yet done the detailed research for that.
>>
>> X
>>
>> [1] https://lists.debian.org/debian-devel-announce/2016/05/msg00001.html

Thanks for your report!  I had figured that there was an issue like 
this, as both the CI and reproducible build tasks have been failing.

I've disabled the use of these extensions and a new version is in git 
[1] awaiting sponsorship.

Doug

[1] 
https://anonscm.debian.org/cgit/debian-science/packages/fflas-ffpack.git/commit/?id=88c339f745dc54351d4c437eedd38a5b83dca993