Re: Ada and QNX

[Gautier <gautier.demontmollin@maths.unine.ch>]

Igor:

> Summarizing what you and others replied, it looks like everything is
> cool with Ada. Just wondering why it is not yet really resurrected and
> blooming and shining in all its glory.

You should take courses about psychology of the masses...

> Perhaps my personal doubts aren't that personal, huh? Nobody appears to
> write an OS in Ada, being so good for system level work. And by the way,
> many people say that GCC does not generate good code for C,

Who says that ?! Did you play the famous Quake 1 game, it is entirely made
with GCC, including graphics...

> so I'm kinda curious how does GNAT manage to generate good code for
> such a more complex language as Ada.

It doesn't matter. With strong typing, GCC-GNAT knows better what animals
are the variables (not just pointers to something) and optimizes indices,
shifts, registers, inlinings, generics etc. nicely. You can take a look at
my pure-software 3D experiments (see link below).

> Aside from code generation itself, how do they
> manage to implement things like rendesvous in an efficient AND portable
> way? Such things normally belong to system-dependent runtime libraries,
> but in Ada they are part of language and having no proof I nevertheless
> suspect that they are implemented by trading efficiency for portability.

For tasking, I can't tell, but e.g. for exceptions, they don't alter at all
performance: they are well implemented !... Anyway you can see the resulting
assembler code (gcc -S -O2 -gnatpn) for checking what GCC/GNAT does...

____________________________________________________
Gautier  --  http://members.nbci.com/gdemont/e3d.htm