On Tue, Oct 27, 2009 at 4:06 PM, Basile STARYNKEVITCH <bas...@starynkevitch.net> wrote: > Ian Lance Taylor wrote: >> >> Basile STARYNKEVITCH <bas...@starynkevitch.net> writes: >> >>> * propose a simple patch to add the PLUGIN_REGISTER_PRAGMA event now? >> >> Do this. > > Will do probably tommorow or this evening! >> >> On the other hand, skimming your list of hooks, I really question the >> need for, e.g., REPLACE_PASS_MANAGER. I would want to see a real use >> case there before adding such a hook. > > From several face to face discussions with ICI CTuning people (that it > Grigori Fursin, Albert Cohen, Zbignew Chamski; all 3 are in CC of this > reply) I understood that GCC ICI is exactly doing that: it has replaced GCC > pass manager by its own, which invokes all the existing GCC passes in some > better order (or better number of invocation) and produces better generated > code (the tuning is done by machine learning techniques; they did run their > modified GCC a large number of times and did build a database of measures.). > > I cannot explain more in details what GCC ICI is actually doing. I hope my > ICI friends will answer here. Perhaps even Zbignew's latest patches are > related to the answer.
The fix is not to add a hook to replace the pass manager but instead to make the GCC pass manager more flexible itself. Richard.
