Hi Segher,
> On Sat, Apr 11, 2020 at 03:46:18PM +0100, Iain Sandoe wrote:
>> Unfortunately, several targets have ABI constraints that prevent
>> an indirect tail-call, which results in the PRs compile error.
>
>> diff --git
>> a/gcc/testsuite/g++.dg/coroutines/torture/symmetric-transfer-00-basic.C
>> b/gcc/testsuite/g++.dg/coroutines/torture/symmetric-transfer-00-basic.C
>> index 864846e365c..8211e8250ff 100644
>> --- a/gcc/testsuite/g++.dg/coroutines/torture/symmetric-transfer-00-basic.C
>> +++ b/gcc/testsuite/g++.dg/coroutines/torture/symmetric-transfer-00-basic.C
>> @@ -1,4 +1,5 @@
>> -// { dg-do run }
>> +// { dg-do run }
>> +// { dg-xfail-run-if "no indirect tailcall" { { lp64 && {
>> powerpc64*-linux-gnu } } || { *-*-solaris2* *-*-aix* } } }
>
> lp64 && powerpc*-*-linux (we have biarch compilers :-) )
>
> The problem is not that there is no indirect tailcall; the problem is
> that no tailcall can be done to a routine that (potentially) has a
> different TOC.
>
> From rs6000_function_ok_for_sibcall:
> Under the AIX or ELFv2 ABIs we can't allow calls to non-local
> functions, because the callee may have a different TOC pointer to
> the caller and there's no way to ensure we restore the TOC when
> we return.
so shouldn't the above be
lp64 && powerpc*-*-*
instead to cover AIX, too? Or are there other PowerPC ABIs that don't
have this issue?
Rainer
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Rainer Orth, Center for Biotechnology, Bielefeld University
