On Thu, Oct 20, 2011 at 11:28:40AM +0300, Laurynas Biveinis wrote: > 2011/10/19 Basile Starynkevitch <bas...@starynkevitch.net>: > > On Wed, Oct 19, 2011 at 04:31:48PM +0300, Laurynas Biveinis wrote: > >> In the end I believe that it is the patches that talk. Whatever > >> patches are going to be submitted, reviewed and accepted, that is > >> going to be GCC's future, be it memory management, or something els > > > > > > I was beginning to work on a patch to add finalizable (that is destroyable) > > objects to Ggc. So I understand you Laurynas suggest that it might be worth > > working on it (while I percieved most other emails, e.g. Ian's or Duncan's > > messages, as a hint to avoid losing my time). > > I'm not sure in this case. I think that C++ would reduce the need for > it, but you need the feature *now*, and GCC codebase is not C++ yet. I > agree with other suggestions that the safest option for you is to make > it MELT-specific. Or, you could use C++ in MELT. > > In any case I cannot offer much of opinion, should you work on this or > not. Sorry.
To be clear, I don't need finalized objects myself, and I don't need them in MELT neither. (MELT runtime has already ad-hoc finalization for some few MELT values, notably those boxing PPL stuff. That finalization uses the existing Ggc plugin hooks.). So, I am trying to add finalized objects in Ggc not for MELT (it does not need them, and it already has some finalization tricks which I could use when some GCC begins to use C++ objects), but for general use. I still don't grasp how a future GCC coded in C++ could realistically avoid Ggc, because nobody (amongst those advocating C++ smart or whatever _ptr-s) explained how he believes the current GCC GTY-ed representations (like tree, gimple, gimple_seq, edge, loop-s...) could be re-implemented in C++ using C++ tricks without Ggc, and what could be the transition from the current state of GCC to such a future state (C++--full, but Ggc-less) of GCC. I'm quite confident that if I continue working on MELT (which I hope to, and I believe I will) and if GCC is going entirely the C++ way (which I don't hope that much, but apparently it is the way it is going) I would be able to adapt MELT to whatever coding rules & styles GCC will require. But I don't understand how Ggc could be avoided (and I am not sure to understand how even LLVM can avoid any kind of garbage collection in the long run). What I do hope, is that when Gcc becomes written in C++, the coding rules and styles for manual memory management would be well documented. Apparently, adding finalization into Ggc seems quite easy (but until I did it, I can be wrong). And my feeling is that, together with some support for GTY-ed classes in gengtype, that could offer a realistic transition route to more C++ inside GCC. And be able to use more of PPL stuff inside plugins and passes seems to motivate & justify adding finalizers in Ggc (and later, C++ support in gengtype). I might be grossly wrong, but nobody explained -with concrete examples- us how the current major GCC representations could be done inside GCC with C++ but without Ggc. For instance, nobody explained what an hypothetical class Gimple or class Gimple_Seq could be. Cheers. -- Basile STARYNKEVITCH http://starynkevitch.net/Basile/ email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359 8, rue de la Faiencerie, 92340 Bourg La Reine, France *** opinions {are only mines, sont seulement les miennes} ***
