[squeak-dev] Re: x86 sarl curiosity...
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
> yourself the yawn.
> > I just tried to save an instruction in Cog;s generated bitShift:
> It seems to me that SARL (shift arithmetic right long) should set the sign
> 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
> optimize as using some MMX 64 or 128 bits arithmetic (like PSRLLQ).
> If relevant, check my trivial optimizations for large ints at
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.
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