Request for reviews (S): 7041100: The load in String.equals intrinsic executed before null check

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/7041100/webrev

Fixed 7041100: The load in String.equals intrinsic executed before null check

String.equals intrinsic has (rec == arg) check followed by NULL check generated 
by gen_instanceof() when there was no NULL check before. If compiled method also 
has (rec == arg) check followed by explicit NULL check of argument then a load 
from argument could be scheduled before NULL check because of 6831314 bug.

Generate explicit check (uncast(argument) == null) in String.equals intrinsic 
until 6831314 is fixed. We have to uncast not-nullness otherwise the check will 
fold immediately and it is needed until after CCP phase.