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

[Ximin Luo]

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
> 
> -- System Information:
> Debian Release: stretch/sid
>   APT prefers testing
>   APT policy: (990, 'testing'), (500, 'stable'), (300, 'unstable'), (200, 'experimental')
> Architecture: amd64 (x86_64)
> Foreign Architectures: i386
> 
> Kernel: Linux 4.6.0-1-amd64 (SMP w/4 CPU cores)
> Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> Init: systemd (via /run/systemd/system)
> 
> Versions of packages fflas-ffpack depends on:
> ii  fflas-ffpack-common  2.2.1-1
> 
> fflas-ffpack recommends no packages.
> 
> Versions of packages fflas-ffpack suggests:
> pn  fflas-ffpack-dev-doc   <none>
> pn  fflas-ffpack-user-doc  <none>
> 
> -- no debconf information
> 


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