Re: [Gomp-discuss] Somethings to think about ....

[Steven Bosscher]

On Tue 11-03-2003  10:42  Lars Segerlund took OT to the next level:
>   In the discussion on the gcc mailing list a while ago someone 
> suggested that the tree structures should be restructured in a way as to 
> prevent duplication of information when lowering, ( thus lowering would 
> mainly consist of adding nodes to the tree and perhaps some infor 
> mation), and this would give a representation which could keep the 
> higher level constructs all the way to the RTL ( since the RTL could be 
> attached to the tree ).

[ OT:  Frankly this is one of the biggest problems in GCC: It
  does not have an IR that can be "lowered" in the traditional
  meaning of the word.  The only "real" lowering we do is
  GENERIC->GIMPLE, everything else is a complete rewrite.  When
  GCC lowers from trees to RTL, it basically duplicates the
  whole tree in a completely new representation (adding cruft
  and magic all over in the process). ]

[ OT^2: Diego, do you plan to lower GIMPLE even further?
  The closer you'd bring it to RTL, the easier (hence
  faster, less bloated) the tree->RTL expanders could be... ]

OK, now lets try to get back ON topic...  What does this discussion mean
for our project?

Seb. said that CIL is concurrency-aware.  Maybe somebody can explain a
bit how it represents concurrency, e.g.:  Which constructs does it have
to support concurrency, and how does it handle data in those constructs
(i.e. what is thread private, what is a semaphore, etc.).  Is it enough
to support everything we need for OpenMP?  And, is it reasonably small?

If so, we could model our GENERIC concurrency-awareness tree
representation to what CIL does.  We could then define a superset of
these trees that can represent OpenMP pragmas in the parser, and lower
the superset to the stuff we'd have in GENERIC in the pass than
translates the C/C++ parse tree to GENERIC.

Greetz
Steevn