Re: [PATCH] g++: Add require-effective-target to multi-input file testcase pr95401.cc

[Jeff Law <jeffreyalaw@gmail.com>]

On 11/10/23 11:00, Patrick O'Neill wrote:
> 
> On 11/9/23 17:34, Jeff Law wrote:
>>
>>
>> On 11/3/23 00:18, Patrick O'Neill wrote:
>>> On non-vector targets dejagnu attempts dg-do compile for pr95401.cc.
>>> This produces a command like this:
>>> g++ pr95401.cc pr95401a.cc -S -o pr95401.s
>>>
>>> which isn't valid (gcc does not accept multiple input files when using
>>> -S with -o).
>>>
>>> This patch adds require-effective-target vect_int to avoid the case
>>> where the testcase is invoked with dg-do compile.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>>     * g++.dg/vect/pr95401.cc: Add require-effective-target vect_int.
>> Sorry, I must be missing something here.  I fail to see how adding an 
>> effective target check would/should impact the problem you've 
>> described above with the dg-additional-sources interaction with -S.
> 
> It's not intuitive (& probably not the cleanest way of solving it).
> 
> pr95401.cc is an invalid testcase when run with dg-do compile (for the 
> reasons above).
> 
> pr95401.cc 
> <https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/vect/pr95401.cc;h=6a56dab095722b01d912416352df17f0d91dfd27;hb=HEAD> does not define a dg-do, which means it uses the testcase uses dg-do-what-default <https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/vect/vect.exp;h=fc77120a83173c65ad147e8bb7c29ac82f06bb6d;hb=HEAD#l30> to determine what to do.
> dg-do-what-default is set by target-supports.exp 
> <https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/lib/target-supports.exp;h=1a7bea96c1e4ccb8ef30ac7012c04e8d44c5ad01;hb=HEAD#l11532>.
> 
> The two options here are set dg-do-what-default run or compile.
> On non-vector targets the pr95401 is set to compile (which is invalid).
> 
> Ideally we would say if dg-do-what-default == compile don't run, but 
> AFAIK that isn't possible.
> I didn't want to duplicate the check_vect_support_and_set_flags logic to 
> return true/false since that'll probably get out of sync.
> 
> I used require-effective-target vect_int as a proxy for 
> check_vect_support_and_set_flags (also since the testcase only contains 
> integer arrays).
> 
> That way we do this now:
> dg-do-what-default run -> run
> dg-do-what-default compile -> skip test
> 
> If there's a cleaner/better approach I'm happy to revise.
Another approach would be to make this a run test -- without actually 
running the vector bits.  ie, set it up so that it can safely run on any 
target.

volatile bool x = false;

main()
{
   if (x)
     call the vector function that already exists
   exit (0);
}

Though that may run afoul of other issues.

So if you want to go forward with your patch, that's fine, just add a 
comment about how adding the effective-target test works around the problem.

Thanks for the detailed explanation,

jeff