Request for reviews (XS): 6843752: missing code for an anti-dependent Phi in GCM

[Vladimir Kozlov]

Resending.

http://cr.openjdk.java.net/~kvn/6843752/webrev.00

Fixed 6843752: missing code for an anti-dependent Phi in GCM

Problem:
Changes for 6470497 (part G) incorrectly removed the code
for anti-dependent PHI pinned below load's 'early' block.
As result the load placed below this phi into the block with
lowest frequency and a wrong value is loaded.
In the test case the load placed inside loop which modifies
the loaded value to NULL. As result we got NULL exception.

Solution:
Don't place a load below anti-dependent PHI.
Added the regression test modified to show the problem
in latest VM (the loop body executed less time then
the code before the loop).

Reviewed by:

Fix verified (y/n): y,  bug's test

Other testing:
JPRT