1. volatiles _NEVER_ ever sit in a regester except for reload phase.
even local volatile will be saved in memory (on stack)
2. volatile var updates every time after 'volatile value' updated.
3. gcc _DOES_ optimize over functions calls (how does it work otherwise?)
if you still think gcc does not do a proper job -- please let us know, we'll
fix it shortly.
cheers,
~d
On Tuesday 06 April 2004 16:57, Sergei Sharonov wrote:
> > There is a good point to note here, which catches a lot of
> > people out.
> > GCC is a pretty smart compiler. It will seek out and remove a lot of
> > redundancy. However, this means the programmer has to be more exact
> > about what they write. You can be pretty sloppy writing for
> > IAR, as it
> > fails to optimise away a number of redundant things GCC will. If
> > something is volatile, you'd better make darned sure you
> > declare it as
> > such, or you will have problems.
>
> Sometimes even declaring the variable volatile fails to work for me. It
> still sits in a register and is never updated. I had to move the
> comparison into a separate function. I believe, that works because gcc
> does not (?) optimize over function calls.
>
> Sergei
>
>
>
>
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