S390: Allowing a NOP instruction without operands

Martin Schwidefsky schwidefsky@de.ibm.com
Fri Jun 19 13:34:00 GMT 2009


On Thu, 18 Jun 2009 11:10:42 +0100
Nick Clifton <nickc@redhat.com> wrote:

> Hi Martin,
> 
> > First of all: yes I think it makes sense to have a nop instruction that
> > can be used without operands. I don't like the implementation though,
> > to check for particular opcodes with a strcmp feels wrong.
> 
> I thought that you might say that. :-)
> 
> > My counter
> > proposal would be to introduce new variantes for the RR_0R and RX_0RRD
> > instruction formats. Make all operands optional and replace the strcmp
> > check with a check against S390_OPERAND_OPTIONAL.
> 
> Fine by me.  I just went with the simplest solution.  (Plus I have never 
> looked at the s390 opcode generation system before and I was worried 
> that if I tried to introduce a new nop pattern I would break something).
> 
> Please could you go ahead and apply your patch ?

Done.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.



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