I've committed the cut-down version of the gimple statement subclasses work to svn trunk [specifically the gimple-classes-v2-option-3 git branch, having bootstrapped®rested it on x86_64-unknown-linux-gnu (Fedora 20)].
This is the the 89-patch kit from https://gcc.gnu.org/ml/gcc-patches/2014-04/msg01148.html with various fixups, reviewed by Jeff and Richi. This strengthens the type requirements on numerous places in the middle end. For example, the callgraph now works on gcall * rather than plain gimple, capturing the GIMPLE_CALL requirement and checking that at compile-time. This gives us earlier failures when bugs occur, closer to the failure point, and (I hope) more readable code (since the assumptions made become clearer). It converts about half of the gimple_foo_ accessors, so that they take a gimple subclass pointer. [In theory we could add a gimple-compat.h that adds back overloads for these if you have out-of-tree code that uses the accessors with a plain "gimple"]. I've dropped about 80 followup patches where I attempted to convert the rest of the accessors, which led to contorted and overly-verbose C++isms in the code. Discussion on IRC indicates unhappiness with the cut-down version, a feeling that it's still too verbose. I'm sorry about that. There may be ways of shortening the API (if that's acceptable at this dev stage). Two common patterns relating to gimple_statement_iterator: (A) after detecting a particular kind of statement currently visited by a gsi, call some function, passing it the gsi, where the callee has something like this (in what I merged): - gimple stmt = gsi_stmt (*gsi); + greturn *stmt = as_a <greturn *> (gsi_stmt (*gsi)); i.e. where we then rely on it being a GIMPLE_RETURN in the callee. Would it be useful to have a less verbose spelling of, say: as_a <greturn *> (gsi_stmt (*gsi)); ? (B) a check for a particular gimple code on the gsi_stmt e.g. like this in what I merged: - if (gimple_code (stmt) != GIMPLE_CALL) + stmt = dyn_cast <gcall *> (gsi_stmt (*gsi)); + if (!stmt) return; Should we add a less verbose spelling of: dyn_cast <gcall *> (gsi_stmt (*gsi)); ? It's important to have a clear distinction between the as_a<> and dyn_cast<> cases: the former is a simple cast in a release build, whereas the latter is a conditional that could return NULL (in both debug and release builds). If we're going for minimal typing, then a method is shorter than a function, since we wouldn't need to spell out the "gsi" twice e.g.: (A) could become: greturn *stmt = gsi->as_a_greturn (); (B) could become: stmt = gsi->dyn_cast <gcall *> (); if (!stmt) or: stmt = gsi->dyn_cast_gcall (); if (!stmt) or maybe: stmt = gsi->is_a_gcall (); if (!stmt) An earlier version of my patches had casting methods within the gimple_statement_base class, which were rejected; the above proposals would instead put them within gimple_stmt_iterator. Dave
