Re: [Patch testsuite] Skip gcc.dg/ifcvt-4.c for targets on which it may not work

["Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>]

On 21/12/15 19:38, Jeff Law wrote:
> On 12/18/2015 02:55 AM, James Greenhalgh wrote:
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>>
>> Hi,
>>
>> PR68232 is a testsuite failure for targets with very low branch costs.
>> As the test is looking for if-conversion, it will fail for any subtarget
>> for which the cost of a branch is sufficiently low that if-conversion
>> looks
>> more expensive.
>>
>> In the current implementation this will be any subtarget with an
>> unpredictable
>>   branch cost of 0 or 1. I had thought this would be very few targets,
>> but
>> at least powerpc64le and arm can trigger this for particular tuning
>> targets.
>>
>> This patch skips the test on those targets.
>>
>> OK?
>>
>> Thanks,
>> James
>>
>> ---
>> 2015-12-17  James Greenhalgh  <james.greenhalgh@arm.com>
>>
>>     PR testsuite/68232
>>     * gcc.dg/ifcvt-4.c: Skip for arm*-*-* and powerpc64le*-*-*.
> OK.
> 
> FWIW, I'd really like to see someone cleanly tweak config-list.mk so
> that we can use it to test this kind of stuff.
> 
> In theory what I want to be able to do is build all the listed targets
> and run a single test on them so that we can build these skip/xfail
> lists much easier.
> 
> I've done it a few times by hand and it seems like it's something we
> ought to be able to do much more easily.
> 
> Jeff
> 

The bigger problem here is that branch costs are a property of a
specific CPU, not the target architecture.  So deciding whether or not
we should skip this test (and perhaps others like it) is impossible
given that we can't know what the default CPU for the compiler is (and
even if we did know, maintaining such a list would be almost impossible).

R.