Re: Param ordering; < and <= felix (22 Jul 2002 18:45 UTC)
Almost OT, < and <= Ben Goetter (in the field) (22 Jul 2002 20:06 UTC)
Re: Almost OT, < and <= David Feuer (22 Jul 2002 22:21 UTC)
RE: Almost OT, < and <= Ben Goetter (in the field) (23 Jul 2002 09:25 UTC)
RE: Almost OT, < and <= David Feuer (23 Jul 2002 14:28 UTC)
Re: Almost OT, < and <= felix (23 Jul 2002 07:30 UTC)
RE: Almost OT, < and <= Ben Goetter (in the field) (23 Jul 2002 08:27 UTC)
Re: Almost OT, < and <= Marc Feeley (25 Jul 2002 23:43 UTC)
RE: Almost OT, < and <= Ben Goetter (26 Jul 2002 02:47 UTC)

Re: Almost OT, < and <= felix 23 Jul 2002 07:30 UTC

> Felix:
> > Where exactly? I can't find it... ;-)
>
> You'll find it deep within the churning (nay, roiling) bowels of the
> processor, being the number of different condition code flags being
> checked in the course of executing a Jxx (x86) or B + cc (ARM).  If you
> were working on a FPGA or implementing bignum comparisons, then I think
> you could more easily find it or its equivalent.

This mailing list is addressing something different, IIRC.

>
> David:
> > This seems kinda [...] architecture-specific.
>
> The way that arithmetical operations affect condition codes shows little
> variation, at least among the popular contemporary processors using
> condition codes.  x86 and ARM are rather diverse architectures, yet they
> agree on Z, N (aka S), C, V.  SPARC, too, I think.  VAX ditto.  All the
> way back to the hoary PDP-11.
>
> MIPS is different, not using condition codes.  The only pure-comparison
> MIPS operation is <.  (Not <=, not >.)  Anything else you'd have to
> synthesize with a subtraction.
>
> Beyond cycle counting, I see op< as more primitive than op<=: one
> establishes order, while the other allows for equivalence.  I would
> prefer a SORT which lets me use the most primitive predicate possible.
> On many platforms it won't matter; but on some, it may.

On which platforms might it matter, then? Can you give a code-
example (C will be fine) which shows any substantial difference in
size or speed?

cheers,
felix