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Re: For GCCv3: recommend -fno-builtin and remove -fvtable-gc
- To: Richard Shih-Ping Chan <cshihpin at dso dot org dot sg>
- Subject: Re: [ECOS] For GCCv3: recommend -fno-builtin and remove -fvtable-gc
- From: Andrew Lunn <andrew dot lunn at ascom dot ch>
- Date: Tue, 10 Jul 2001 09:29:18 +0200
- Cc: ecos-discuss at sources dot redhat dot com
- References: <20010710094111.A12594@cshihpin.dso.org.sg>
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.
Andrew