[RS6000] PR96493, powerpc local call linkage failure

Segher Boessenkool segher@kernel.crashing.org
Tue Aug 11 18:30:36 GMT 2020

On Tue, Aug 11, 2020 at 12:36:28PM -0500, Peter Bergner wrote:
> On 8/11/20 11:35 AM, Segher Boessenkool wrote:
> > Hi Alan,
> > 
> > On Tue, Aug 11, 2020 at 06:38:53PM +0930, Alan Modra wrote:
> >> This fixes a fail when power10 isn't supported by binutils, and
> >> ensures the test isn't run without power10 hardware or simulation on
> >> the off chance that power10 insns are emitted in the future for this
> >> testcase.
> > 
> > The testcases said it wanted power8, so why did it fail?  GCC shouldn't
> > use anything that requires p10 support in binutils then, or what do I
> > miss here?
> It failed with an assembler error because one of the functions in the
> test uses an attribute target power10 and GCC emits a ".machine power10"
> assembler directive in case we do generate a power10 instruction(s).
> The old binutils Bill used doesn't know about power10, so boom.
> That is what requires the dg-require-effective-target power10_ok.

Ah, okay.

> Now given the power10 function is so small (just a call to a p8
> function), the chance we'll generate a p10 instruction is low (zero?),
> so we could just keep the dg-do run as is (ie, always run), but
> might that change one day?

On a non-p10 it will just use the generated non-p10 code, and that will
just work, now and for forever (yeah right :-) )

Either always running or what this patch does will work.  But please add
comments what the test case wants to test, and for the tricky bits.


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