On 2018-08-02, at 11:27:28, Charles Mills wrote:
>> Can EX modify the CC mask in a target branch instruction?
>
> You bet!
> Branch prediction is always ... well, like any other prediction.
>
It was mentioned in IBM-MAIN that BCT(R) is predicted to always branch;
BC is predicted to never branch. I hope there's an exception for BC 15:
EX targets, syscall arguments, etc.
If so, I wondered if:
BC cond,target Highly probable branch, but predicted not to branch
Might be better optimized as:
BC 15-cond,*+8 Probable not branch; correctly predicted
BC 15,target Predictably certain to branch.
(JIT compilation is supposed to fix things like this.)
-- gil
