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

Nicolas Cellier ncellier at ifrance.com
Wed Jan 21 20:38:57 UTC 2009

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® 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


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