Request for reviews (M): 7070134: Hotspot crashes with sigsegv from PorterStemmer

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/7070134/webrev

Fixed 7070134: Hotspot crashes with sigsegv from PorterStemmer

It is an other case of "6831314: C2 may incorrectly change control of type 
nodes". Loop predicate RCE upper_bound check matches an other dominating 
RangeCheck and split_if optimization moves loads to dominating test. In the bug 
case (step4() method) two code branches have the same loads from the same array 
(b[]) and they are combined and moved above array's index check and above 
lower_bound predicate check.

The fix is band-aid to not move data nodes which are attached to a predicate 
test to a dominating test. It is allowed to do that during loop peeling and loop 
predicates generation since they duplicate all checks. I also switched off 
predicate RCE optimization for counted loops with '!=' test since there is no 
guarantee that loop index will be in the range [init, limit) if init > limit.

Added regression test. Refwokload (x64) shows no affect.