Am 16.06.2021 um 19:19 schrieb Joseph Myers:
> On Wed, 16 Jun 2021, Julian Brown wrote:
>
>>> +    if test x$gcc_cv_as_gcn_global_load_fixed = xyes; then
>>> +      AC_DEFINE(HAVE_GCN_ASM_GLOBAL_LOAD_FIXED, 1, [Define if your
>>> assembler has fixed global_load functions.])
>>> +    else
>>> +      AC_DEFINE(HAVE_GCN_ASM_GLOBAL_LOAD_FIXED, 0, [Define if your
>>> assembler has fixed global_load functions.])
>>> +    fi
>>> +    AC_MSG_RESULT($gcc_cv_as_gcn_global_load_fixed)
>>> +    ;;
>>> +esac
>>
>> I think the more-common idiom seems to be just having a single
>> AC_DEFINE if the feature is present -- like (as a random example)
>> HAVE_AS_IX86_REP_LOCK_PREFIX, which omits the "define ... 0" case you
>> have here. (You'd use "#ifdef ..." instead of "#if ... == 1" to check
>> the feature then, of course).
>
> Actually I think what's preferable is the approach used with e.g.
> GATHER_STATISTICS - define to 0 or 1 using a single AC_DEFINE_UNQUOTED
> call (via a shell variable that's set to 0 or 1 as appropriate), then test
> in "if" conditions, not #if, as far as possible, so that both alternatives
> in the conditional code always get syntax-checked when compiling GCC (for
> this target).
>

Thank you for your proposals. I adapted configure.ac and gcn.c
accordingly (similar to the GATHER_STATISTICS example).

Marcel
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