Re: compiler-options?

[Stefan Schroepfer <whoknows@onlinehome.de>]

Kerstin Hoef-Emden schrieb:
> 
> Hi,
> 
> So you are recommending either to use only -mcpu= or to use both with
> -mcpu= first?

Both. -mcpu=ev56 instructs the compiler to generate code specifically
for ev56 CPUs and -Wa,-m21164a instructs the assembler to accept it.

> What are the "symptoms" that a special code needs -mieee? Most packages
> which I compile, are used for molecular phylogeny. MrBayes, as the name
> says, works with Bayesian methods. I guess, that fpu-operations are
> heavily used in these kind of calculations.

Crashes at runtime. AFAIK the whole problem is that Alpha CPUs can't
handle denormals. Using -mieee the compiler adds support for denormals
in software, which costs performance. So use this option only if you
need it, specifically only for those modules which need it.

Regards,
Stefan Schroepfer