Re: [ECOS] For GCCv3: recommend -fno-builtin and remove -fvtable-gc

[Jonathan Larmour <jlarmour at redhat dot com>]

Andrew Lunn wrote:
> 
> On Tue, Jul 10, 2001 at 09:41:11AM -0800, Richard Shih-Ping Chan wrote:
> > Hi eCos team - I would like to make two suggestions for GCC3
> >
> > [1] Make -fno-builtin a default command line option.
> >
> > This is to prevent unwanted optimisations of builtin functions
> > at the default optimisation level of -g -O2. An example is
> > the optimisation of printf and the consequent introduction of
> > extra symbols like putchar and puts by GCCv3.
> 
> I don't think this is a good idea. Some of the build in functions are
> optimized for the particular architecture, eg memcpy, memset,
> etc. They will be faster than the equivelent in the eCos library.
> 
> Is there a -fno-builtin-printf command line option? Just turn off that
> feature. The other option would be to rename printf in redboot, so the
> optimizer does not recognise it.

Yes we have plans to rename Redboot's printf, but in Redboot's short
lifetime it has already become quite pervasive.

In any case, we recommend avoiding GCC v3 on all targets where 2.95 support
exists. GCC v3 is not very stable for most embedded targets.

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine
Come to the Red Hat TechWorld open source conference in Brussels!
Keynotes, techie talks and exhibitions    http://www.redhat-techworld.com/