Peter,
I never have gotten a handle on "branch prediction" within the i-cache
discussion. Are you saying that, for the most part, we should always try
to code so that the normal path is to not-branch wherever possible?
(I know, within limits.)
Tony Thigpen
Peter Relson wrote on 05/16/2017 08:31 AM:
<snip>
Well, in reality you are right of course (who cares about the i-cache?)
but
in theory one is branching around and NOT crashing, so not wasting the
i-cache is a desirable goal.
</snip>
A program coded with any thought for performance would not be "branching
around and NOT crashing". It would be branching out of line upon detecting
the error so that the normal path takes no branch at all.
Thus instead of "BZ NOERROR" (or JZ or whatever), "BNZ ERROR".
Peter Relson
z/OS Core Technology Design
