On Fri, 10 Jan 2014 20:08:57 +0000
Brian Drummond <[email protected]> wrote:

> Generally no, neither is preferred; they serve different purposes and
> each has its strengths.
> 
> One recent user found the gcc version choked with huge auto-generated
> VHDL source files (along the lines of gate-level netlists), consuming
> gigabytes of swap space during the (gcc backend) optimisation passes
> then falling over with allocation errors, while the mcode version
> sailed through the same test with 10% or less of the memory
> foootprint.
> 

I guess both should be available in a FreeBSD port. Are they
distinguished in their naming and organization such that both can exist
on the same system without conflicts or confusions?

> Another user routinely links to C code (and I have linked to Ada)
> using the VHPI interface; as the mcode compiler supports neither of
> these languages, the gcc version is essential to him.
> 

This is a *very* significant point! Thank you! I came to the GHDL
project as part of an exploration of the possibility of embedding
several [expert systems][1] into a layered discrete-event simulation
model. The foreign function facility (with VHPIDIRECT) is important.

[1]: http://clipsrules.sourceforge.net/

> I have performed precisely ONE such comparison and to my surprise, the
> penalty using the mcode compiler was only 20% (vs gcc at -O or -O1; at
> the time, -O2 and -O3 failed to compile; since fixed).
> 
> More such comparisons could be useful.
> 

Maybe a project wiki page with some tables and (possibly) graphs? I can
add that to my TODO list.

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