Hello All,
This is motivated by MELT, but I believe it would be useful to every GCC
plugin which tries to be
compilable both for GCC 5 & GCC 6.
The technical issue described in
https://gcc.gnu.org/ml/gcc/2016-02/msg00149.html is that the gimple
identifier in plugins has changed from pointer (in GCC 5 and earlier) to
class.
I feel that is a very major change w.r.t. plugins. Most (and probably
all) GCC plugins will be affected.
(A cosmetic patch might be to name gimpleinstance what is today gimple)
A tempting way might be
#if GCCPLUGIN_VERSION >= 6000
typedef gimple* melt_gimpleptr_t;
#else
typedef gimple melt_gimpleptr_t;
#endif /* GCC 6 */
unfortunately, that does not work today, because gengtype does not get
preprocessed input (and does not invoke the preprocessor).
Perhaps we should consider patching gengtype to enable conditional GTY-s
at least for typedefs.
I am tempted to try implementing a conditional GTY, perhaps
typedef GTY((when(WANTPOINTER)) gimple* melt_gimpleptr_t;
and
typedef GTY((unless(WANTPOINTER)) gimple melt_gimpleptr_t;
then, add a condition argument to gengtype processor, perhaps invoking
it as
gengtype -CWANTPOINTER ....
or
gengtype --condition WANTPOINTER
but this makes sense only if such a gengtype patch would go both into
GCC 6 and into the next microrelease of GCC 5, i.e. GCC 5.4
I'm afraid that the current stage rules forbid that. Or, could such a
patch be considered as a bug fix?
Opinions are welcome!
Regards.
PS. The very dirty alternative would be to feed gengtype with different
variants of inputs. That is ugly.
--
Basile STARYNKEVITCH http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
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*** opinions {are only mine, sont seulement les miennes} ***
