Re: gcc 4.0 front-end infrastructure for C dialects - plans?

["Giovanni Bajo" <giovannibajo at libero dot it>]

Gary Funck <gary@intrepid.com> wrote:

> The recent discussion titled "gcc integration" has me wondering if our
> project (implementing an experimental dialect of C used primarily in
> a distributed shared memory context) should be moving to
> GCC 4.0 rather the our current focus (gcc 3.4)?

You did not give us the most basic piece of information: are you planning to
contribute this to GCC or not?

> 1) Will the current yacc-based parser remain for C dialects in 4.0?

4.0 is a fixed codebase, we are just fixing bugs at this point. So the answer
is yes, *BUT* there is already a recursive descendent parser for C ready for
4.1 (the last posted version is here:
http://gcc.gnu.org/ml/gcc-patches/2004-10/msg02409.html). Instead of worrying
about keeping things in sync with this, why don't you just try? You are in a
good position with respect to time: you can work on the 4.1 parser even before
the 4.0 is out.

> 2) Are the 4.0 source files such as c-decl.c, c-typeck.c, and expr.c
>    sufficiently stable at this point to support changes required by
>    a C dialect, without more than the usual amount of heartburn?
>    (the bump from 3.3 to 3.4 was actually quite extensive, but
>    manageable and understandable).

Between the c-* files and expr.c, there is now the big and extensive tree-ssa
infrastructure with dozen and dozen of new optimization passes. You did not
mention what kind of patches to expr.c you did and why they were needed (bugs?
new features?), so I cannot help there. c-decl.c and c-typeck.c should have not
changed too much IIRC, the biggest bump was between 3.3 and 3.4 when Zack
rewrote the whole declaration machinery.

If you are not going to contribute UPC to GCC *and* it is a short-lived
project, you can probably stay with 3.4. The 3.4 branch will be probably
discontinued by the end of 2005 (depends on how good 4.0 turns out to be), and
after that you are left alone with what you have. If you are willing to
contribute UPC to GCC, the best move is to always keep it in sync with CVS
HEAD, so that when you are eventually ready to submit it, at least it meets our
most basic criteria (remember: GCC is not going to accept any new feature in
release branches).

Giovanni Bajo