On 9 October 2010 21:34, Jakub Jelinek <ja...@redhat.com> wrote: > On Sat, Oct 09, 2010 at 09:22:42PM +0200, Manuel L?pez-Ib??ez wrote: >> My intention by answering Gary is to point out that if he is thinking >> about working on this problem, he should consider building a cheap >> FE-specific CFG, rather than try to share the current infrastructure >> between FE and middle-end. I would like to see this implemented, so > > I don't think that's a good idea. Much better would be just to > not emit diagnostics, which shouldn't be emitted for dead code, right away, > but instead of that queue it into the IL (in a form of something > like __builtin_diagnostics, or something similar). Then after cfg cleanup + > DCE > has been run (or at expansion time?) we could issue diagnostics for the > __builtin_diagnostics left in the IL afterwards. For -O0 if no DCE happens > at all we could have some cheap pass that would just nuke obviously > unreachable > __builtin_diagnostics and don't modify the IL otherwise (of course gated on > whether there are any in the IL).
That doesn't solve the problem of diagnostics changing at different optimization levels. But I don't care much about that, so I wouldn't complain if anyone implemented either option. Cheers, Manuel.
