"R.S. Nikhil" <[EMAIL PROTECTED]> wrote,
> > From: Manuel M. T. Chakravarty [mailto:[EMAIL PROTECTED]]
> > "R.S. Nikhil" <[EMAIL PROTECTED]> wrote,
> > > ...
> > > But it DID offer an important new feature relative to
> > > the original Fortran programs it was trying to
> > > displace -- completely automatic parallelization
> > > for the Cray vector machines that were the main
> > > workhorses at Livermore and similar labs.
> >
> > Hmm, good point. So, did they succeed in reaching this
> > goal, compared to the awful guessing and trial & error you
> > have to go through before you get any decent performance out
> > of a vectorising Fortran compiler?
>
> In the following paper, the Sisal team describes their technical
> successes, including performance numbers.
>
[...]
> title = "Retire Fortran? A Debate Rekindled",
[...]
I know this paper (and its runtime results are very
impressive), but IIRC it doesn't really answer the question
about how difficult it is to write Sisal code that
vectorises well. My experience with vectorising Fortran
compilers (with only one, to be honest) is that small
variations in coding an algorithm can lead to vastly
different execution times and you often have to have
accurate knowledge about how a vector processor (and the
compiler) works to get it right. It would be interesting to
know how much simpler this is in Sisal. In the paper, they
"simply" re-coded existing Fortran code in Sisal - I guess
the original Fortran code was already streamlined for vector
processing.
[...]
> Unfortunately, these choices won them no respect in the FP community
> (for which, my commentary, shame on the FP community), who chose to
> look down their noses at Sisal for what were essentially trivial and
> shallow reasons (Pascal syntax, focus on those "dirty" arrays instead
> of those "cool" lists, no polymorphism, no higher-order functions,
> ...). This made it MUCH harder for the Sisal team to sell the
> language to their Fortran-writing colleagues, who kept hearing
> negative opinions about Sisal from the FP community.
That is sad, indeed - and fires back, I guess, as an
outsider will likely attribute the failure to a technical
deficiency of FP. Anyway, thank you for outlining the
political background, which I was not aware of.
Manuel
