[Distutils] special compiler options for only one file

[Andrew Svetlov]

I guess utilize build_clib command to create static library with your
settings just for your file than build your extensions with linking
that library.

On Tue, Mar 19, 2013 at 4:54 PM, Andrew Dalke <dalke at dalkescientific.com> wrote:
> Hi all,
>
>   I have a Python extension which uses CPU-specific features,
> if available. This is done through a run-time check. If the
> hardware supports the POPCNT instruction then it selects one
> implementation of my inner loop, if SSSE3 is available then
> it selects another, otherwise it falls back to generic versions
> of my performance critical kernel. (Some 95%+ of the time is
> spent in this kernel.)
>
> Unfortunately, there's a failure mode I didn't expect. I
> use -mssse3 and -O3 to compile all of the C code, even though
> only one file needs that -mssse3 option.
>
> As a result, the other files are compiled with the expectation
> that SSSE3 will exist. This causes a segfault for the line
>
>      start_target_popcount = (int)(query_popcount * threshold);
>
> because the compiler used fisttpl, which is an SSSE-3 instruction.
> After all, I told it to assume that ssse3 exists.
>
> The Debian packager for my package recently ran into this problem,
> because the test machine has a gcc which understands -mssse3 but
> the machine itself has an older CPU without those instructions.
>
> I'm trying to come up with a solution that can be automated for
> the Debian distribution. I want a solution where the same binary
> can work on older machines and on newer ones
>
> Ideally I would like to say that only one file is compiled
> with the -mssse3 option. Since my selector code isn't part of this
> file, SSSE-3 code will never be executed unless the CPU supports is.
>
> However, I can't figure out any way to tell distutils that
> a set of compiler options are specific to a single file.
>
> Is that even possible?
>
> Cheers,
>
>                                 Andrew
>                                 dalke at dalkescientific.com
>
>
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-- 
Thanks,
Andrew Svetlov