another tree access question

["Jeffrey Richardson" <jlrichardson at link dot com>]

Pop,

I still have the question I asked in my original email:  if I have a new function
to print out  tree information (or for that matter wanted to use an existing
function such as debug_tree or print_node), and I want to find a single place in
the gcc code to call this function and access the entire tree for the program unit
currently being compiled, where would I place the call to the function?

In other words, is there any place in the code where I can get an address of a tree
which represents the entire program unit?  If so, where is it?

As before, any examples would be greatly appreciated.

Also, you mentioned that there was no documentation describing how to use gdb on
the gcc code, and make use of your tree-browser.  Is there any documentation now?

Thanks again,

Jeff Richardson
jlrichardson at link dot com

Pop Sébastian wrote:

> Hi,
>
> On Fri, Dec 06, 2002 at 11:43:32AM -0500, Jeffrey Richardson wrote:
> > > >
> > > > I am interested in developing a combination "intelligent editor" and
> > > > source browser using the tree structure created internally by GCC, as
> > > > described in the article on trees in the GCC Internals manual.
> > > >
> Have a look at http://gcc.gnu.org/projects/tree-ssa/tree-browser.html
> This is (for the moment) just a debugging tool, but it could be extended
> into an interactive source browsing/editing tool.
>
> > > > My question is this:  if I write my own version of "precess_stmt" which
> > > > uses the macros to access various tree information and write it out to a
> > > > file, where is the best place to call my function?  Can it be called
> > > > from a single location (such as finish_function), and still have access
> > > > to the full tree structure?
> > > >
> Yes.
> You can use TB for experimenting during a gdb session and see what information
> is available at a given point of the compiler.
>
> Ouch... I just realised that there's no link to a page explaining how to
> debug GCC using GDB.  Is there any page that contains these bits?
> Otherwise I'll write one from scratch.
>
> > > > Also, what is the "permanence" of the tree structure.
> For the moment in tree-ssa branch you cannot store tree structures into a file.
> However this operation was implemented in pch-branch, and thus it could be
> included in tree-ssa-branch once pch-branch stabilize.
>
> > > > As a source file
> > > > is parsed, and the tree structure is constructed, is there a point at
> > > > which branches of the tree are discarded because they are no longer
> > > > needed (e.g. when a function has been completed),
> yes, once trees were translated into RTL garbage collector is called and
> tree structures for function's body are freed.
>
> I think that there's a possiblilty to make GCC keep all functions from a
> compilation unit in memory simply by avoiding to go into rest_of_compilation.
>
> For handling projects with multiple files we'll need a load_tree operation
> (already implemented in pch-branch I think).
>
> A source editing tool working on top of GCC could improve development style,
> productivity, and code understandability (for example class hierarchy, call-
> graph,... are for free when you work with ASTs).  Moreover the programmer
> could focus on a small part of the code and optimize it locally.  One could
> even imagine more interaction when the compiler could extract information by
> questioning directly the programmer.
>
> > > > or is there a point at
> > > > which a complete tree exists for the entire source file, which would
> > > > therefore be the best time to call a function to output a "snapshot" of
> > > > the tree?  (I guess this is actually a re-statement of my first
> > > > question.)
> > > >
> just before genrtl_ expanders (expr.c).
>
> > > > If there are any examples or code fragments of similar applications that
> > > > you can share with me, I would very much appreciate it.
>
> Yes, two weeks ago I contributed tree-browser.c in tree-ssa branch.
>
> For checking this branch out, have a look at the instructions:
> http://gcc.gnu.org/projects/tree-ssa/index.html
>
> Sebastian