Re: [PATCH] S/390: Run md tests with -march=native instead of -march=z13.

[Jakub Jelinek <jakub at redhat dot com>]

On Tue, Dec 13, 2016 at 10:28:29AM +0100, Dominik Vogt wrote:
> The attached patch fixes an md test execution problem on S/390.
> The tests would be built with -march=z13 but executed even on
> older machines.  Build with -march=native instead, so executing
> the tests should work on any machine generation.
> 
> Tested on s390x biarch, but not bootstrapped or regression tested.

I think this isn't a very good idea.  Then the testresults from one
box to another one will mean something different.
IMHO you want something like x86 avx_runtime effective target
(z13_runtime?), which would stand for running on z13 capable hw and
with z13 assembler support.
Or choose what options to include based on such effective target tests,
and perhaps also select a default action, like we do on some targets e.g. in
the vectorizer.  Some tests are dg-do run by default if the hw supports
the needed ISA, or dg-do assemble, if the hw doesn't support that, but
at least the assembler can assemble those, otherwise dg-do compile or
something similar.

With -march=native, you find some results in gcc-testresults and the exact
underlying hw will be part of the needed info to see what you've actually
tested.  While usually just some tests are UNSUPPORTED if hw or assembler
doesn't have the needed features.

	Jakub