On Wed, Nov 13, 2013 at 11:37 AM, Steven Bosscher <stevenb....@gmail.com> wrote: > On Wed, Nov 13, 2013 at 11:10 AM, Richard Biener wrote: >> Well, he doesn't even consider that the exact same "tree rant" applies >> to frontend code. > > That's not entirely true, either. Most front ends already use their > own IL in the parser (only C++ uses 'tree' for everything). > > What worries me most, is that we may end up with: > > FE-IL => 'tree' => gimple > > where 'tree' is just a memory-consuming, complicated intermediate step > between the front ends and the middle end. I don't think that's the > interface we want.
True. The above applies to Fortran and Ada, and maybe also to Go and Java. But yes, as far as I understand Andrews plan we'd still require FE-IL => GENERIC => gimple where GENERIC is 'tree' based and for the C-family frontends FE-IL is already GENERIC with some added tree codes that are lowered during GENERICIZATION (well, not entirely true - the gimplifier is fed not with GENERIC but with GENERIC+ and uses langhooks to handle the '+' part ... ugh). > Really the best place to start IMHO would be to evict 'tree' from the > front ends. That would really be a step towards making the front ends > independent of the rest of the compiler, and it would simplify changes > towards static 'tree' types. Right. The question is what we'd like the end result to look like? FE-IL => GIMPLE I suppose. That means "gimplification" will be the frontends job. The current hand-off point for IL - cgraph_finalize_function - would get a function with GIMPLE IL already. It would be reasonably easy to support both - GENERIC and GIMPLE IL at this point but I'm not sure how difficult converting a frontend to have its own "gimplifier" would be. If anybody is eager to try I'd try on Fortran ;) Note that this would somewhat break the fact that now frontends see all of the TUs IL before gimplification starts, so we could also get the GIMPLE IL at finalize_compilation_unit time, making "gimplification" a langhook that gets us at the IL. Eric, would emitting GIMPLE from gigi make that a lot more complicated? That is, would you prefer to have an even higher-level early GIMPLE (considering stuff like TARGET_EXPR and WITH_CLEANUP_EXPR, etc.)? Richard. > Ciao! > Steven
