[RFC] decay vect tests from run to link for pr95401

[Richard Biener]

On Thu, Mar 11, 2021 at 9:03 AM Alexandre Oliva <oliva@adacore.com> wrote:
>
>
> When vect.exp finds our configuration disables altivec by default, it
> disables the execution of vectorization tests, assuming the test
> hardware doesn't support it.
>
> Tests become just compile tests, but compile tests won't work
> correctly when additional sources are named, e.g. pr95401.cc, because
> GCC refuses to compile multiple files into the same asm output.
>
> With this patch, the default for when execution is not possible
> becomes link.
>
>
> This was regstrapped on x86_64-linux-gnu and ppc64-linux-gnu, and tested
> with a cross to a ppc64-vxworks7r2 with altivec disabled by default.  I
> found fixing the handling of additional sources to e.g. compile each one
> separately, or perhaps just discard or reject additional sources for
> compile tests, to be a little too involved.
>
> So I'm leaning towards this proposed change, just extended to other
> platforms that also decay from run to compile rather than link, and thus
> run into this problem in g++.dg/vect/pr95401.cc.  Would this be
> acceptable?

I think that's OK.  It's probably difficult to make the test UNSUPPORTED
when dg-additional-sources is discovered with a dg-do compile test?

Richard.

>
> for  gcc/testsuite/ChangeLog
>
>         * lib/target-supports.exp (check_vect_support_and_set_flags):
>         Decay to link rather than compile.
> ---
>  gcc/testsuite/lib/target-supports.exp |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
> index 52d3d036d3c5c..23d532fb2b963 100644
> --- a/gcc/testsuite/lib/target-supports.exp
> +++ b/gcc/testsuite/lib/target-supports.exp
> @@ -9656,7 +9656,7 @@ proc check_vect_support_and_set_flags { } {
>                  # Specify a cpu that supports VMX for compile-only tests.
>                  lappend DEFAULT_VECTCFLAGS "-mcpu=970"
>              }
> -            set dg-do-what-default compile
> +            set dg-do-what-default link
>          }
>      } elseif { [istarget i?86-*-*] || [istarget x86_64-*-*] } {
>          lappend DEFAULT_VECTCFLAGS "-msse2"
>
> --
> Alexandre Oliva, happy hacker  https://FSFLA.org/blogs/lxo/
>    Free Software Activist         GNU Toolchain Engineer
>         Vim, Vi, Voltei pro Emacs -- GNUlius Caesar