Re: [ECOS] What happens during optimization

[Scott Dattalo <scott at dattalo dot com>]

On 15 Nov 2002, Gary Thomas wrote:

> On Fri, 2002-11-15 at 08:40, Grant Edwards wrote:
> > On Fri, Nov 15, 2002 at 07:53:20AM -0700, Gary Thomas wrote:
> > 
> > > Did you rebuild everything after you added the optimization option?
> > 
> > Is it required that eCos and the app be compiled with the same
> > level of optimization?
> 

I was going to ask a very similar question.

> It all depends, but in general I would go for that.

> 
> The quoted example was apt;  the guy built his program and the
> eCos kernel with no optimization.  Thus Cyg_Thread::self was a
> real function.  When he rebuilt the kernel with optimization,
> all of the uses of Cyg_Thread::self were inlined, thus there
> was no copy for his code to link against.
> 
> Mixed optimized/not-optimized code can run into these sort
> of problems where inline functions simply disappear.


In my case, I compiled my app with -O3. I didn't explicitly change the 
eCos opitimization (so it's presumably the default). My code linked just 
fine but didn't run properly. I did not investigate this in detail, but I 
suspect it's due to some inline assembly code (that I wrote).

Scott


-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss