Request for reviews (S): 7050280: assert(u->as_Unlock()->is_eliminated()) failed: sanity

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/7050280/webrev

Fixed 7050280: assert(u->as_Unlock()->is_eliminated()) failed: sanity

Marking locks for elimination is done in IGVN. Unfortunately the order of IGVN 
worklist processing may affect this marking. Also during EA obj may point to 
several objects but after few ideal graph transformations (CCP) it may point to 
only one non escaping object (but still using phi), corresponding locks and 
unlocks will be marked for elimination. Later obj could be replaced with a new 
node (new phi) and will be no escape information about it. And later after some 
graph reshape other locks and unlocks (which were not marked for elimination 
before) are connected to this new obj but they still will not be marked for 
elimination since new obj has no escape information.

Fix:
Do first round of locks marking during EA after ConnectionGraph is constructed 
when all nodes have escape information. During Macro nodes expansion move 
creation of new eliminated BoxLock into new separate method which is called 
before locks elimination. Use this method to mark all associated (same box and 
obj) lock and unlock nodes which were not marked before (instead of the assert).

Tested with failing case and full CTW.