Request for reviews (S): 6912517: JIT bug compiles out (and stops running) code that needs to be run. Causes NPE.

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6912517/webrev.00

Fixed 6912517: JIT bug compiles out (and stops running) code that needs to be run. Causes NPE.

Problem:
Block::implicit_null_check() does not check that the value
is used in memory expression in instructions with embedded
memory load. In the bug case the instruction was:

CmpP val,(tls+off)

Solution:
Add the missing check.
Add regression test.

Reviewed by:

Fix verified (y/n): y, test

Other testing:
JPRT, CTW