Re: KEil bought by ARM

"Wilco Dijkstra" <Wilco_dot_Dijkstra@xxxxxxxxxxxx> writes:

> "John Devereux" <jdREMOVE@xxxxxxxxxxxxxxxxxx> wrote in message
> news:87mzkrdzxj.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > "larwe" <zwsdotcom@xxxxxxxxx> writes:
> >
> >> Chris Hills wrote:
> >>
> >> > Actually Open Source is no match for good commercial compilers in so
> >> > many ways.
>
> > Also, even if you accept that the commercial compilers are "better" at
> > code generation (I have not seen this):
>
> You probably haven't used professional compilers then... Yes, in the
> 8 and 16-bit space some commercial compilers are worse than open
> source ones. However 10 year old ARM compilers _still_ generate better
> code than the latest GCC...

I have not used a "professional" (commercial) ARM compiler, this is
true.

> > - gcc is getting better and better. Presumably there is a limit to how
> > good a commercial compiler can be, so any gap should be closing.
>
> GCC is definitely getting better, but is it narrowing the gap? If you
> consider large C++ applications then the scope for improvement is
> enormous - I guess a factor 2 of improvement is achievable.

Maybe - my programs tend to be "medium sized" C. I would suggest that
we can expect further improvements in gcc with respect to "large C++"
programs. This is because efforts by the gcc maintainers in this area
would benefit all targets enormously, compared to working on
micro-optimising a single backend. This is especially likely if the
factor if 2 you mention is correct.

> > - code space and MHz are getting cheaper and cheaper, so it makes
> > less and less difference anyway as time goes on.
>
> Applications grow about as fast as memory and performance do, so any
> improvements are immediately swallowed.

> > - It is getting easier and easier to justify using 32 bit parts (like
> > ARM) in new designs. I would expect the architecture of these parts
> > to more closely match gcc's abilities than, say, the 8051 where Keil
> > have been the leader.
>
> Interestingly in the 32-bit RISC space GCC is furthest behind. If you look
> at EEMBC or Spec for example you don't see (m)any uses of GCC.

Well I guess that depends on who does the benchmarking!

I did come accross this

<http://www.compuphase.com/dhrystone.htm>

In summary, it looks like Keil ran their own compiler with full
optimisation, and gcc with none! When both were run with sensible
settings for embedded work, gcc came out ahead in both speed and
memory footprint.

--

John Devereux
.

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