(j3.2006) F03/0084, was Re: Interp letter ballot #25

Keith Bierman khbkhb
Mon May 14 14:07:45 EDT 2012


On Sun, May 13, 2012 at 9:16 PM, Malcolm Cohen <malcolm at nag-j.co.jp> wrote:

> On Fri, 2012-05-11 at 16:52 +0900, Malcolm Cohen wrote:
>>
> many sage words elided...


>  ..
>
> Yes, and this is a growing percentage.  The only widely-used processor I
> am aware of on which it was not expensive was the DEC Alpha.  Note "was".
>  It is expensive on every commodity processor I have seen since.  There are
> a number of non-commodity specialistic processors that don't have a global
> rounding mode at all, really this is the only case where it is cheap (i.e.
> when it is encoded into each instruction).
>
> Sadly it wasn't even completely cheap on Alpha. They encoded it almost
right, but (I forget which case they neglected) but not quite, so dynamic
setting was still needed and was terribly expensive (moreso than many other
processors). The trap barrier requirement was also annoying for fully IEEE
active exception handling.

But we digress. As Malcom aptly notes, the interp at hand really shouldn't
drag intervals back into the spotlight.
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