6716785: implicit null checks not triggering with CompressedOops
Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes
cfeea66a3fa8ca3686a7cfa2d0ce8ab0169f168d jdk7-b24
cbc8ad9dd0e085a607427ea35411990982f19a36 jdk7-b25
9410f77cc30c604d1caf7c9fe3a57fa19e1acbe8 jdk7-b26
11b4dc9f2be3523ef989a0db8459eb56b3045c3a jdk7-b27
56652b46f328937f6b9b5130f1e4cd80f48868ef jdk7-b28
31e08f70e88d77c2053f91c21b49a04296bdc59a jdk7-b29
2dab2f712e1832c92acfa63ec0337048b9422c20 jdk7-b30