I'll match you on pedantry any day.  :-)
You mean "complement" operator, as flattering a number isn't useful; and
the distinct operand facility instructions don't save any registers, they
save cycles.

I use them some, but unless I missed something, they all can be replaced
with an LR followed by a traditional instruction.  E.g.: ALRK R9,R1,R0 ==
LR R9,R1  ALR R9,R0.
​  So, not a lot of thrill there.​

Also,  ​I'm sure you mean negative numbers aren't idiomatic for bit
masks​... I'll grant that, but my last word is that occasionally new idioms
can be invented.

​sas
​

On Fri, Jul 20, 2018 at 4:49 AM, David Crayford <[email protected]> wrote:

> I don't like using negative numbers in C code because it's not idiomatic
> for the language and I'm pedantic :)
>
> The C compiler uses a XILF instruction to implement to compliment operator
> and does the AND with a NRK instruction. The distinct operand facility is
> interesting.
> It's for register constraint relief. I wonder how much it's used by
> assembler programmers?

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