On Sun, Aug 28, 2011 at 2:10 PM, leif <[email protected]> wrote:
> On 28 Aug., 19:44, Martin Albrecht <[email protected]>
> wrote:
>> > If 'configure' determined the machine supports SSE2, __M4RI_HAVE_SSE2
>> > is set to 1, but even if that's the case, you should still also test
>> > __SSE2__ when compiling code later (including code *using* the
>> > library).
>>
>> Why? I want that whoever links against M4RI lives in the same world as M4RI.
>
> I'd add something like
>
> #if defined(__M4RI_HAVE_SSE2) && __M4RI_HAVE_SSE2
> #   if !defined(__SSE2__) || !__SSE2__
> #       error Your current compiler and / or CFLAGS setting doesn't
> allow SSE2 code. Please change that or these to the setting(s) you
> used when compiling M4RI.
> #   endif
> #endif
>
> since $CC and $CFLAGS, and hence also the necessity to add some
> compiler flags (as determined at *configure* or build time of the M4RI
> library *itself*) aren't invariants, at least not over the typical
> lifetime of a Sage installation.
>
> Any (manual or automatically triggered) './sage -b' might recompile
> also modules *using* libm4ri, with settings potentially different to
> those at the time M4RI was built, and $SAGE_LOCAL/include/m4ri/
> m4ri_config.h created (which defines __M4RI_HAVE_SSE2) .
>
>
> For more, the interested reader is referred to
>
> http://trac.sagemath.org/sage_trac/ticket/11574#comment:49 ff.
>
> ;-)
>
>> In the spirit of William's "post more" encouragement shouldn't we keep
>> this on list? :)
>
> (Sorry, William, but I think the number of postings has already grown
> again recently.)

You're right --  August numbers for sage-devel are already up nearly
50% over July.

Still, lots of public discussion is good, imho.

William

>
>
> -leif
>
> --
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-- 
William Stein
Professor of Mathematics
University of Washington
http://wstein.org

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