Request for reviews (XS): 6890984: Comparison of 2 arrays could cause VM crash

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6890984/webrev.00

Fixed 6890984: Comparison of 2 arrays could cause VM crash

Problem:
I did incorrect "optimization" in 6827605 changes -
replaced 2 null pointer checks with andptr(p1,p2)
instruction which damages the result register.
I should have use testptr(p1,p2) but it is also incorrect.
There is problem on sparc also - br() instruction is used
instead of brx() when comparing pointers.

Solution:
Restore original null checks for x86.
Use brx() when comparing pointers on sparc.

Reviewed by:

Fix verified (y/n): y, bug's test on both platforms with 32- and 64-bit VM

Other testing:
JPRT