RFR(XS): 8211451: ~2.5% regression on compression benchmark starting with 12-b11

[Roland Westrelin]

Hi Vladimir,

Vladimir Kozlov <vladimir.kozlov at oracle.com> writes:

> You are saying that don't do that check since this condition will not help to avoid overflow anyway. Right?

Yes.

> And to make this regression go away we need to convert test's loop into counted loop and unroll it even with 'ne' 
> condition. Right?

Yes.

> Can we strengthen code by adding runtime check (predicate) for 'ne' case that init < limit? We do this for limit today.

Would it share the uncommon trap call with the loop limit check or would
that be an entirely new Deoptimization::Reason_XXX?

While we're doing it why not convert:

init_t->_hi > max_jint - stride_con

into a runtime check as well?

Roland.