Re: [AD] Optimization flags?

[Eric Botcazou <ebotcazou@xxxxxxxxxx>]

> [About -frename-registers]
>
> No, but the way I understand it, it helps more with the more registers
> you have.. so even if you're kinda limited on registers, you could
> still get some benefit. And what about the PPC?

Yes, it should theoritically be more beneficial on RISC cpus.  But I'm not 
sure in practice.  Maybe on IA-64.

> Of course it'd be bigger (though I wouldn't imagine by mutch?), but
> I'm surprised it's slower. Any particular reason?

Cache trashing.

> [About -funswitch-loops not being the default]
>
> Not according to:
> http://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Optimize-Options.html#Optimize-
>Options

I'm skeptical about this one: while the concept looks theoritically nice,  I 
think it triggers very rarely in practice.  And it could result in bigger 
code too.

> [About -fweb]
> Couldn't hurt to try, but unfortunately I don't have GCC 3.4 and I'm a
> little reluctant to try it (from what I hear it has some problems with
> older code).

This one is more interesting because it really helps the register allocator.

-- 
Eric Botcazou