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
Thu Oct 29 10:09:27 PDT 2009

Thank you, Christian

I will change the type to address.

Vladimir

Christian Thalinger wrote:

On Wed, 2009-10-28 at 16:13 -0700, Vladimir Kozlov wrote:

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 narrowoopbase (NULL by default) is used in ReservedHeapSpace() to determine if the page is needed. Solution: Set narrowoopbase and narrowoopuseimplicitnullchecks values according to compressed oops encoding mode in Universe::preferredheapbase() which is called before ReservedHeapSpace() constructors. Using sizet for base (which is an address) feels a little strange but otherwise looks good. -- Christian

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