[patches] Re: x86-64 gas part II

[Andi Kleen]

On Thu, Dec 21, 2000 at 10:29:20AM +1100, Alan Modra wrote:
> On Wed, 20 Dec 2000, Jan Hubicka wrote:
> 
> > + {"rex",    0, 0x40, X, Cpu64,  NoSuf|IsPrefix,        { 0, 0, 0} },
> > + {"rexz",   0, 0x41, X, Cpu64,  NoSuf|IsPrefix,        { 0, 0, 0} },
> 
> Do these "rex" prefixes actually appear in instructions?  ie. Does it make
> sense to accept a line like " rex mov ..."?  If not, then these prefixes
> shouldn't be in the table.

It makes sense for some instructions like iret or sysret, which change their
operation then, but these could as well be specified with a 'q' suffix. 

-Andi (who is glad that a real problem was found after this useful K&R discussion)