assorted PPC questions

[Alan Modra]

On Mon, Aug 17, 2020 at 10:19:28AM +0200, Jan Beulich wrote:
> On 11.08.2020 11:02, Alan Modra wrote:
> > On Wed, Aug 05, 2020 at 09:38:35AM +0200, Jan Beulich wrote:
> >> Wouldn't availability of pseudos implying %cr0 as first (i.e.
> >> destination) operand better be consistent throughout the opcode set?
> > 
> > Are you saying every instruction ought to have a record bit?  ie. that
> > there ought to be xxx. for every xxx?
> 
> No, the question wasn't about the . suffix. Instead what I'm wondering
> is why CMP*, VCMP*, and XVTLSBB have pseudos with the first operand
> omitted (implying %cr0), while e.g. FCMP* doesn't (and there are quite
> a few more).

I'm not sure.  Possibly because you might expect that with a fcmpu
form that allowed the BF field to be omitted, the implied CR field
should be cr1 in line with with the record form of other fp insns,
eg. fmr. sets cr1.  That conflicts with the general rule that an
omitted field has a zero value.  (Yes, we now have a few exceptions,
see *invalid < 0 tests in ppc-opc.c)

-- 
Alan Modra
Australia Development Lab, IBM