[squeak-dev] Re: x86 sarl curiosity...

Eliot Miranda eliot.miranda at gmail.com
Wed Jan 21 21:13:29 UTC 2009


On Wed, Jan 21, 2009 at 12:38 PM, Nicolas Cellier <ncellier at ifrance.com>wrote:

> Eliot Miranda <eliot.miranda <at> gmail.com> writes:
>
> >
> >
> > Hi All,
> >
> >     anyone know the x86/IA32 really well?  If so, read on.  Otherwise
> save
> yourself the yawn.
> >
> > I just tried to save an instruction in Cog;s generated bitShift:
> primitive.
>  It seems to me that SARL (shift arithmetic right long) should set the sign
> flag
> based on the result, in fact it says as much in the manual; I quote
> from IA-32
> Intel(R) Architecture Software Developer's Manual Volume 2B:  Instruction Set
> Reference, N-Z p 4-192
> >
>

>
> Hi Eliot,
> I guess you are adressing case of SmallInteger, otherwise I would
> understand
> optimize as using some MMX 64 or 128 bits arithmetic (like PSRLLQ).
> If relevant, check my trivial optimizations for large ints at
> http://bugs.squeak.org/view.php?id=7109



Hi Nicholas,

    yes I'm doing SmallInteger and also trying to keep the JIT very simple
initially so no MMX registers or instructions in the stage one JIT until I
do floating-point.  I'll take a look at these.  Thanks.

>

> <http://bugs.squeak.org/view.php?id=7109>
>
> Nicolas
>
>
>
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