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Re: compiler-options?


On Sat, 3 Feb 2001, Christopher C. Chimelis wrote:

> I would use -mcpu= before -Wa,-m21164a in general, but that really depends
> on what you're looking to do.  The -Wa option passes the -m21164a option

So you are recommending either to use only -mcpu= or to use both with
-mcpu= first?

> > One thing I was told to use as well, was -mieee. What are the comments
> > on this item? Does it slow down the execution of the code?
> The -mieee option is a special case, IMO.  If you have code that needs it
> (ie, anything that needs IEEE math compliance or anything that will
> generate a SIGFPE), use 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. 

> If not, it does slow down the code and bloats it a bit.  There have
> been frequent discussions about compiling the entire Alpha deb tree
> with -mieee, but so far, nobody has made a convincing enough argument
> for it to justify the general slow-down that we would see. 

Unfortunately, computing time is an important item in molecular
phylogeny. It is a difference whether an analysis takes 12 days or 7.

> In reality, though, for small binaries like 'ls', it won't make a
> noticable difference, but larger software would make it very apparent.

Or smaller soft which does a lot of repetitions?
Phylogenetic methods have usually repetitive structure. Datasets are
calculated through again and again.

Apart from this:

I encounter problems to report the -O-bug to submit@bugs.debian.org and
have no idea what is going wrong. The return of my first attempt was
understandable, I put a blank line before the Package line, but after
correction, it still returned with error message:

Your message didn't have a Package: line at the start (in the
pseudo-header following the real mail header), or didn't have a
pseudo-header at all.

These were my starting lines:

Package: gcc
Version: 1:2.95.2-13

So what is wrong about it? (Preprocessed file was attached to the





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