On Thu, 3 Nov 2022 11:39:51 GMT, Coleen Phillimore <[email protected]> wrote:
>> src/hotspot/share/prims/jvmtiTagMapTable.cpp line 116:
>>
>>> 114:
>>> 115: JvmtiTagMapEntry* JvmtiTagMapTable::find(oop obj) {
>>> 116: if (obj->has_no_hash()) {
>>
>> This new function you added checks if the markWord has a hashCode. If there
>> is a displaced markWord, then it very well might be that there is a
>> hashCode, but it is in the displaced markWord - either in a stack lock or an
>> ObjectMonitor. Bailing here does not seem correct, as it might actually be
>> in the table even if there is no hashCode in the markWord. Is this an
>> optimization?
>
> It is an optimization. I don't think we want to create an identity hash for
> all oops just for lookup. Is there a better way to find if an oop hashCode?
I was hoping there was just a bit but you're right. I renamed it to
fast_no_hash_check() and only return true if the object is unlocked and added a
comment.
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PR: https://git.openjdk.org/jdk/pull/10938
