Re: gcc suited for DSP architectures?

[<benedetto dot proietti at infinito dot it>]

> Hello everybody,

Hello to you Oliver,
and sorry for the delay.

> in a research project we have developed a processor description
> environment from which several processor related tools can be generated
> (retargetted).
> The architectural focus is on signal processors and not on general
> purpose architectures.
> What is still missing is a way to generate a compiler or at least
> compiler components for DSPs.
> 
> I am thinking of using the gcc environment for this but I am not sure if
> gcc is suited for DSP architectures.

If this can help you, I have built a quite complete
port of GCC for the APEmille machine (a project of
INFN-Italy and DESY-Germany). It's a parallel SIMD supercomputer where the processing nodes are very similiar 
to common DSP. I have had some problems, but finally
the compiler worked and it was very fast: the fastest
compiler for the machine.

> What I am interested in is for example in how far VLIW architectures can
> be addressed by gcc and how softwarepipelining, conditional execution,
> SIMD instructions special purpose units (like MAC or FIR units) and so
> on are supported.

The processors in our case were VLIW, the architecture was SIMD, there was a kind of predication (stack oriented,
not with registers as in IA-64 for example),
but till now there is no software-pipelining.
There are, also, some special function units, but most
of them are hidden to the compiler.

After all, I think GCC is an excellent starting 
environment to build custom compilers, also for 
advanced processors as the one(s) yuo're working on.
We had a optimizing-compiler in 12 months starting
 almost from scratch: if this is good for you, go on!

> Knowing that IA64 has similarities with current DSPs I wonder how gcc is
> approaching this upcomming architecture.
> Maybe one can use this development for DSP backends, too?
> I also would appreciate suggestions for other compiler environments that
> are better suited for my plans.

I don't know many others compiler you could use
(maybe LCC, but you have to write your backend almost
from scratch). GCC is followed and supported by
lots of people. Good people, may I say!

If you need deeper details don't hesitate in the 
mailing list or personally.

Good luck,
Benedetto


> Greetings,
> Oliver Wahlen
>