(j3.2006) (SC22WG5.4910) [ukfortran] Comment on a comment on the WG5 letterballot on N1947

[Keith Bierman]

Malcolm, I was not referring to YOU when I suggested that some do not
appreciate the costs.

Nor did I intend to imply that John's proposal was voted down because of
integer exceptions.

Yes, if we count by sheer numbers, hardware which can do
this efficiently have become numerous. However, somewhat less so at the
"high end" where a lot of Fortran still rules the roost. But I know you are
quite in touch with a wide spectrum of users on interesting platforms.

The other class of cost, of course, is scarce committee time. I shall not
take up any more of it with this topic. Those of you currently doing the
work can and should choose how to spend your committee time.

Best wishes,
khb

Keith Bierman
khbkhb at gmail.com
kbiermank AIM
303 997 2749


On Thu, Jan 17, 2013 at 10:01 PM, Malcolm Cohen <malcolm at nag-j.co.jp> wrote:

> Keith Bierman wrote:
> >OpenVMS, as far as I know, has only run on processors which physical
> support
> >for overflow detection (Alpha, VAX). So this is not a very useful proof
> point
> >for the significant number of processors that do not have such hardware
> >support.
>
> The vast majority of processors, including the x86 family, have such
> hardware
> support.
>
> >>        2.  Detection of integer overflow conditions was part of John
> Reid's
> >> ENABLE block
> >>proposal in 1994.
> >
> >John was proposing a language feature;
> > he didn't have the burden of actually implementing it,
> > so again this example
> >proves nothing germane to Bill's objections.
>
> John's ENABLE block was not shot down by people raising objections to
> integer
> overflow detection.
>
> >Look at current GPU architecture manuals and hardware specifications for
> >examples of compute engines for which such handling could prove quite
> costly
> >(indeed, making moving computation off the CPU possibly pointless). GPUs
> are
> >similar (in many ways) to the old FPS style array processors and Cray
> style
> >vector machines (just not nearly as polished or easy to program).
> >
> >I'm not saying that these aren't useful or interesting language features.
> But
> >those without any "skin the game" w.r.t. >implementing either the
> hardware or
> >software should not blithely ignore the costs proposed.
>
> (1) No-one is blithely ignoring anything.
> (2) I do in fact know what it costs in hardware and software; in hardware
> the
> costs are not zero but they are miniscule compared to many other cute
> features
> that are being implemented.
> (3) I have in fact implemented it in software without using the hardware
> support.
>
> Or the snarkier but more amusing:
>
> "Losing a rocket on the launch pad: a few billion dollars.
> Being able to brag about your GPU: priceless."
>
> Cheers,
> --
> ................................Malcolm Cohen, Nihon NAG, Tokyo.
>
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