Problem when using optimization on aix 5.2 and gcc 4.1.1

[Nick Maclaren]

Andrew Haley <aph-gcc@littlepinkcloud.COM> wrote:
> Thomas Mittelstaedt writes:
>
>  > Compiling with -Wall is not easy for us right now, too. There simply are  
>  > too many!! :-(
> 
> Well, that's your clue, isn't it?

Indeed.  While gcc has had problems with unreasonable or erroneous
warnings, they are almost always repetitions of the same one and
can trivially be removed with a Python/Perl/awk/etc. script.  And I
don't think that it has such problems at present.

My experience with AIX is that the likely cause of both excessive
warnings and misbehaviour is incompatible options.  The documentation
is politely described as unhelpful and inadequate, even by modern
standards (despite its volume).  You need to do a LOT of chasing to
find out the restrictions and incompatibilities, but using the wrong
command or option is a sure recipe for chaos.  And, of course, that
will often show up as misbehaviour only for optimised code :-(

Note that AIX selects between option sets in its xlc and xlf suite
by providing alternative commands.  You need to poke quite a lot
further to discover what that implies about which headers and
libraries it uses in its various modes.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1@cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679