Subject: Re: CCL:Bug in g77 (2.95.1) compiler

From: Jochen <[email-masked]>
Date: Thu, 21 Oct 1999 21:29:59 +0200

On Don, 21 Okt 1999 [email-masked] wrote:

>Unlike the previous one, compiling gradlib/ijdkl.f of the TURBOMOLE
>system gives wrong results in basis set optimizations if compiled with -O2.
>(-O0 works for both compilers). At first glance, I could not see any
>programming error in ijdkl.f which breaks optimization.

Well, bugs are usually not found at a first glance - esp. those that only
lurk out when optimizing.
These actually is a typicla point of compiler(optimizer) bugs as well -
many commercial compilers do show up these or that bug if they are told
to optimize hard.
Of course there might be an optimizer bug in the gbe - but since this is
a common backend of gcc, g++, g77, ... (java, chill, pascal, ... ), many
of them are recognized readily.

Have you reported the bug to the g77/GCC developers ?

>I no not know if I have time to track down this bug, but perhaps it is a good
>idea to be careful with the "New" compiler.

Yep, I would suggest to be as careful as you should be with any new
product.

Have you actually tried the -O1 flag ? Have you tested wether the
"dangerous" -f options can be accounted for the problem (there is a
lsiting of some to be careful about in the gcc manual, IIRC).

-- Jochen
        Heinrich-Heine-Universität, Institut für Physikalische Chemie I
        Universitätsstr. 1, Geb. 26.43.02.29, 40225 Düsseldorf, Germany
phone 02118113681 fax 02118115195  --  www-public.rz.uni-duesseldorf.de/~jochen
[email-masked] -- [email-masked] -- [email-masked]