On Mon, Apr 20, 2015 at 3:02 PM, Martin Jambor <mjam...@suse.cz> wrote: > Hi, > > because I really dislike the hassle our (almost) flattened header > files cause quite often, I have made a very simple experiment to find > out how the header files really depend on each other. Some results, > together with a dozen of short paragraphs of relevant text are here: > > http://labs.suse.cz/mjambor/150417-headers_in_gcc/headers_in_gcc.html > > Short summary: I wrote a script removing an include at a time and > parsing errors and recording such discovered "dependencies." The page > has text-file reports showing what needs to be included before what, > in which files and because of which error messages. I have also > plotted a few graphs from these "dependencies." The pictures look > interesting, I am not sure if they are in any way useful, but have > a look and judge for yourself. > > Regardless of whether or not this experiment had any value. Do we > plan to do un-flattening of header files in the course of the next > release or two? The pain the flat header files is real and enduring > it for much longer or indefinitely seems unhealthy to me.
The goal was to end up with a few aggregating includes so you just include sth like ssa-pass.h from a tree pass that works on SSA form. Or gimple.h for anything that only needs to look at GIMPLE stmts. The first step was the flattening to see what dependencies we have (ok, it's not really good at that...) and to move stuff (mostly prototypes) between files to reduce dependencies. It's easy to create a ssa-pass.h file, but it's hard to determine the minimum stuff that should be in there (no rtl.h for example). For Andrews project (that tree stuff) the most important thing is to not have tree(-core?).h leak into files that only use GIMPLE (and thus the "valid" parts of tree). Richard. > Thanks, > > Martin
