review (S) for 6958485: fix for 6879921 was insufficient

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/6958485

6958485: fix for 6879921 was insufficient
Reviewed-by:

6879921 fixed a case where the superword optimization was attempting
to handle arrays of oops which we shouldn't allow.  A guard was
inserted in stmts_can_pack which fixed the original issue.  Testing
with bigapps has shown that there are other paths where this problem
can manifest.  In particular this pattern:

 dst[i] = (src[i] != null ? false : true);

shows that are_adjacent_refs can be reached through est_savings,
skipping the added is_java_primitive guard.  The fix is to put an
is_java_primitive guard into are_adjacent_refs to guard the data_size
calls.  Tested with new testcase.