🚀 go-pugleaf

In article <baum-1610951033230001@piem3.atg.apple.com>, Allen J. Baum (baum@apple.com) wrote:
> Ignoring conditional branches for them moment:
>   ALL instructions on the ARM are conditional
>   PA-RISC has a 'skip the next instruction' in arithmetics,
>      which is equivalent to making the next instruction conditional
>   SPARC and ALPHA have conditional move instructions 
>      (from memory here- could be wrong)

I don't think Sparc has a conditional move: I haven't seen it in
the papers I have. If someone else has more information about this,
I'm interested in them. But...

Sparc has also a skip next instruction: more generally, with a
conditional branch, you can skip the following instruction is
the branch is not taken, by writing ",a" after the instruction.
I think this possibility is manly used in loops, e.g.

loop:
...
       be,a  loop
       inc   l0

instead of

loop:
...
       inc   l0
       be    loop
       nop

To skip an instruction conditionally, write something like:

       bne,a label
       <instruction>
label: ...

Here <instruction> is executed iff Z = 0 (nonzero result).

--
Vincent Lefevre, vlefevre@ens.ens-lyon.fr
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[Properties of 17]  4^17 = 17179869184