"Joseph S. Myers" <[email protected]> writes:
> On Mon, 6 Jun 2011, Rainer Orth wrote:
>
>> Paolo Bonzini <[email protected]> writes:
>>
>> >> * Except for Darwin, the code uses TRAMPOLINE_SIZE. This only exists in
>> >> the backend headers. While it could be duplicated somewhere in the
>> >> libgcc configury, I'd rather propose that gcc define
>> >> __TRAMPOLINE_SIZE__ (in gcc/c-family/c-cppbuiltin.c (c_cpp_builtins)
>> >> to avoid this. On PowerPC Darwin, one cannot use TRAMPOLINE_SIZE
>> >> definition right now since the macro calls the rs6000_trampoline_size
>> >> function in rs6000/rs6000.c. This would be solved nicely by
>> >> __TRAMPOLINE_SIZE__.
>> >
>> > Good idea.
>>
>> Included in the revised patch below. This part will need Joseph's approval.
>
> Is this definition ever going to be of use to user code, or even to system
> headers? It looks purely like an implementation detail rather than
> something meaningful for users. That would tend to suggest conditioning
> it on the proposed new -fbuilding-libgcc option that I suggested in
> <http://gcc.gnu.org/ml/gcc-patches/2010-10/msg01206.html>. (There are a
> *lot* of target macros that are in a similar position - see the list under
> "used by the compiler itself and libgcc" in
> <http://gcc.gnu.org/wiki/Top-Level_Libgcc_Migration>. Even if we could
> define and document public semantics for corresponding predefined macros,
> I don't think they would be of practical use to users of GCC, so for most
> of them I expect defining __LIBGCC_<macro>, only if -fbuilding-libgcc, is
> the best way of eliminating the dependence on host tm.h without making
> implementation details visible to users of GCC.)
>
> So my view is that you should define __LIBGCC_TRAMPOLINE_SIZE__, only if
> -fbuilding-libgcc.
I can give it a try if I can figure out how to define -fbuilding-libgcc
via the option handling machinery. I just want to avoid having to
implement too many unrelated cleanups, otherwise it will take a year to
get this single patch done.
Rainer
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Rainer Orth, Center for Biotechnology, Bielefeld University
