[squeak-dev] x86 sarl curiosity...

Eliot Miranda eliot.miranda at gmail.com
Wed Jan 21 21:08:56 UTC 2009


Hi Martin,  can you send me the assembly?  Or show me the opcodes? When I
try this it doesn't work.  So I must be doing something differently.
and Hi!  Robert Hirschfeld mentioned you when he and I met last week.

On Wed, Jan 21, 2009 at 11:06 AM, Martin Beck <
martin.beck at hpi.uni-potsdam.de> wrote:

> Hi Eliot,
>
> Eliot Miranda wrote:
> > Hi All,
> >     anyone know the x86/IA32 really well?  If so, read on.  Otherwise
> save
> > yourself the yawn.
> >
> [...]
> > (my emphasis added).  But neither the Bochs simulator nor my Intel Core
> Duo
> > set the flags when doing sarl $1, %eax when %eax contains -1.  Have I
> > misread, or is the manual wrong?
> >
> I cannot confirm this. Using this simple C-Program:
>
> int calc(int i) {
>  return i >> 1;
> }
>
> int main() {
>  printf("%i\n", calc(-1));
> }
>
> my GCC 4.3.2 generates a sarl %eax instruction as the assembler output
> shows. Debugging it with Kdbg shows a change of the flags after the
> instruction. In fact, CF and SF are set as (more or less) expected. I
> also have a Intel Core 2 Duo.
>
> Regards,
> Martin
>
>
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