On Fri, Mar 25, 2011 at 8:37 AM, Basile Starynkevitch <bas...@starynkevitch.net> wrote: > Hello All, > > Let's imagine someone is writing a plugin (or a MELT extension...) which > computes some complex information around gimple in a pass before LTO > serialization and re-uses that information in a later pass after LTO > serialization. A possible way to associate data inside a plugin to some > gimples would be to have hash tables (keys being Gimple, associated value > being some complex information specific to the plugin). The the plugin would > compute & serialize [i.e. write or output] data in a pass before LTO and > deserialize [re-read or input] that data at LTO time. > > The writing happens in the write_summary and write_optimization_summary hooks > of struct ipa_opt_pass_d of file tree-pass.h. The reading happens in > read_summary & read_optimization_summary hooks. > > But what I cannot understand is how can such a plugin know what are the > gimple involved. Since the plugin needs to persist (i.e. serialize into LTO > stream & de-serialize) an hash table mapping some gimples to its data, the > plugin need to know what gimples are serialized & deserialized, to restore at > LTO streaming read the common gimple pointers (the same gimple pointer should > appear in the function & the hash table).... > > I would imagine gcc/lto-streamer-out.c would have a plugin hook inside > output_gimple_stmt but this is not the case... > > I admit I don't have a clear picture of LTO streams usage (& customization) > from plugins. > Or perhaps it is not possible yet???
You are not allowed to piggy-back on statements but only global things like cgraph and varpool. There is no way to transition data from before LTO to after associated with statements. And there never will be. Richard. > Regards. > -- > 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 mine, sont seulement les miennes} *** >
