Inline assembly queries [2]

[Michael Meissner]

On Tue, Jul 07, 2009 at 02:40:02PM +0200, Andreas Schwab wrote:
> Gabriel Paubert <paubert@iram.es> writes:
> 
> > On Fri, Jul 03, 2009 at 10:57:12PM +0200, Andreas Schwab wrote:
> >> The 'Z' constraint is required for a memory operand for insns that don't
> >> have an update form (which would be selected by the %U modifier).  
> >
> > Hmmm, I believed that it was for instructions that only have an indexed
> > form (all Altivec, byte reverse, and l?arx/st?cx for atomic operations).
> >
> > Of course none of these instructions have an update form, but they don't
> > have an offset encoded in the instruction either.
> 
> Yes, you are right.  IIRC there are either all u/x/ux forms or only the
> x form.

Well VSX adds a new wrinkle in that there are now update indexed memory
reference instructions (i.e. ux), but no reg+offset or reg+offset update forms
for the VSX loads/stores.

-- 
Michael Meissner, IBM
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