Re: OpenMP, HPC, and the future of GCC

[Neil Booth <neil at daikokuya dot co dot uk>]

Per Bothner wrote:-

> To emphasize:  efforts to make Gcc better for "computational"
> domains is very welcome.  It is just that any design needs to
> avoid further complicating and slowing down Gcc.
> 
> Right now, there is a lot of concern and focus about the
> compilation speed of Gcc, especially when not opimizing.
> So it is very important that any new vectorization support
> not slow the compiler down further, at least by default.

I'd like to emphasize this too, particularly the first paragraph, if
I may.  The best way to get something into GCC like we're discussing
here is to make it as clean and as unintrusive as possible.

Discussions over the last few months on these lists have pointed out how
various architectural aspects of GCC need to change.  One thing I would
like to see happen is a cleaner separation of front end and middle end,
which is why I'm writing my parser with a C-specific IR that is not trees.
We must try as hard as possible to avoid making architectural improvements
harder than they already are (way too hard, really).  The recent addition
of PCH to GCC has raised the bar even further to design changes.

I think the OMP proponents would do best to get GCC's architecture
improved to the point that it is a fairly clean and orthogonal addition
to the compiler.  At that point it would be very hard to find reasonable
objections to its addition.  However, at the moment such objections are
easy to find: the last thing we need is something hackish embedded in
the parsers and middle end of GCC like was intimated in the opening post
of these threads.

Neil.