[10] RFR(S): 8181741: C2 compilation fails with "assert(i<_max) failed: oob"

[Tobias Hartmann]

Hi,

please review the following patch:
https://bugs.openjdk.java.net/browse/JDK-8181741
http://cr.openjdk.java.net/~thartmann/8181741/webrev.00/

PhaseIdealLoop::split_thru_phi() creates a new PhiNode 'phi' and sets the _igvn type through PhaseIdealLoop::register_new_node() -> PhaseIterGVN::register_new_node_with_optimizer() -> set_type_bottom(). Later in PhaseIdealLoop::split_if_with_blocks_pre() we call n->as_ConstraintCast()->dominating_cast(this) with n == 'phi' which fails because the type for 'phi' is not initialized in PhaseIdealLoop (but only in _igvn). 

The call to dominating_cast(this) was introduced in JDK 9 by JDK-8139771 but the the problem only shows up with JDK-8176506 which added a call to type_or_null(val). We should pass both &_igvn and 'this'. I also added an assert to type() and type_or_null() to verify that these methods are not used from PhaseIdealLoop.

Tested with replay compilation, JPRT and RBT (running).

Thanks,
Tobias