smallint usage guidelines
Denis Vlasenko
vda.linux at googlemail.com
Mon Apr 9 11:15:18 UTC 2007
On Monday 09 April 2007 11:45, Natanael Copa wrote:
> > Example:
> > on i386, there is no widening constant store instruction
> > for some types of address modes, thus
> > movl $0x0,(%eax) is "c7 00 00 00 00 00"
> > movb $0x0,(%eax) is "c6 00 00"
>
> (warning: nasm syntax below)
> In this specific example you can actually do:
> xor eax,eax ; 0x31 0xC0 - 2 bytes
Of course, and gcc does that. Actually, gcc knows
many more such tricks.
But my example is a store to _memory_ referenced by eax,
not to eax itself.
--
vda
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