[9, 8u40] RFR (XS): 8068915: uncommon trap w/ Reason_speculate_class_check causes performance regression due to continuous deoptimizations

[Roland Westrelin]

Hi Vladimir,

> The fix is to (1) forbid changing uncommon trap action under the hood, and (2) consult Compile::too_many_recompiles when adding a speculative guard.

I’m not sure I understand what code (1) above is referring to in your webrev.

Also, why is the problem restricted to speculative traps? Wouldn’t the same checks be required for non speculative traps as well?

Roland.