Request for reviews (S): 6892186: 6896084: VM does not reserve protected page below heap for compressed oops implicit null checks (original) (raw)

Vladimir Kozlov Vladimir.Kozlov at Sun.COM
Wed Oct 28 16:13:21 PDT 2009

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http://cr.openjdk.java.net/~kvn/6896084/webrev.00

Fixed 6896084: VM does not reserve protected page below heap for compressed oops implicit null checks

Problem: VM should reserve protected page below heap for compressed oops implicit null checks in compiled code (see 6716785). After zero based compressed oops changes (6791178) the page is not reserved because undefined narrow_oop_base (NULL by default) is used in ReservedHeapSpace() to determine if the page is needed.

Solution: Set narrow_oop_base and narrow_oop_use_implicit_null_checks values according to compressed oops encoding mode in Universe::preferred_heap_base() which is called before ReservedHeapSpace() constructors.

Reviewed by:

Fix verified (y/n): y, test output

Other testing: JPRT

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