RFR (XS): 7181658 CTW: assert(t->meet(t0) == t) failed: Not monotonic

[Vladimir Kozlov]

Thank you, Vladimir, for taking and fixing this bug.

Could you factor the condition into a separate function to be used in both places?

Thanks,
Vladimir

Vladimir Ivanov wrote:
> http://cr.openjdk.java.net/~vlivanov/7181658/webrev.00
> 
> 7181658 CTW: assert(t->meet(t0) == t) failed: Not monotonic
> 
> One of node equivalence checks in CmpUNode::sub doesn't respect 
> ConstraintCast nodes, which could lead to missed optimization 
> opportunities. In this particular case it also breaks monotonicity 
> assumption of CCP analysis due to a discrepancy in logic between 2 cases.
> 
> I haven't been able to come up with a reduced regression test due to 
> some tricky symbol resolution orderings which provoke the bug - even 
> when the method bytecode is effectively the same! :-)
> 
> Testing: failing test, CTW (full testlist)
> 
> Best regards,
> Vladimir Ivanov
>