RFR: JDK-8213199: GC abstraction for Assembler::needs_explicit_null_check()

Erik Österlund erik.osterlund at oracle.com
Thu Nov 1 13:52:27 UTC 2018

Hi Roman,

Would you mind explaining how you need to override this and why? I'm 
afraid I did not quite get it from your description in the RFC (which is 
also why I didn't come up with a solution either).

Am I correct that you need to return false if the passed in offset is 
the cell header offset -8, or is there anything else at all required to 
that logic? You mentioned something about the high order byte being 
masked on AArch64, but didn't quite connect the dot to how that is 
related to this code. Is it?


On 2018-11-01 12:20, Roman Kennke wrote:
> Hi Kim, thanks for reviewing! I'll push it through jdk/submit now.
> Erik: ok for you too?
> Thanks,
> Roman
>>> On Oct 31, 2018, at 6:14 PM, Roman Kennke <rkennke at redhat.com> wrote:
>>> Hi Erik,
>>> right. Fixed this, and what what Kim mentioned plus a missing include:
>>> Incremental:
>>> http://cr.openjdk.java.net/~rkennke/JDK-8213199/webrev.01.diff/
>>> Full:
>>> http://cr.openjdk.java.net/~rkennke/JDK-8213199/webrev.01/
>>> Ok now?
>> Looks good.

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