Request for reviews (S): 6991188: C2 Crashes while compiling method

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6991188/webrev.00

Fixed 6991188: C2 Crashes while compiling method

Construction of Connection Graph during EA relied on
DU relation corresponds to nodes index so that def
nodes processed before their uses. Move EA after
IGVN (for 6966411 fix broke that. Because of that
not all Graph edges will be created leading to
incorrect EA results and incorrect Ideal graph.

Walk over interesting nodes (AddP, LoadP, StoreP)
several times until no new edges are created.
Set limit on iterations.

Tested with assert in iterations bailout code and
calls to PhaseIdealLoop::verify() (removed from
final changes). Passed JPRT, full CTW, nsk.