On Tue, 23 Jul 2024 13:12:23 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> src/hotspot/share/runtime/deoptimization.cpp line 1641:
>>
>>> 1639: assert(fr.is_deoptimized_frame(), "frame must be
>>> scheduled for deoptimization");
>>> 1640: if (LockingMode == LM_LEGACY) {
>>> 1641:
>>> mon_info->lock()->set_displaced_header(markWord::unused_mark());
>>
>> In the existing code how is this restricted to the LM_LEGACY case?? It
>> appears to be unconditional which suggests you are changing the non-UOMT
>> LM_LIGHTWEIGHT logic. ??
>
> Only legacy locking uses the displaced header, I believe, which isn't clear
> in this code at all. This seems like a fix. We should probably assert that
> only legacy locking uses this field as a displaced header.
Update: yes, this code change does assert if you use BasicLock's displaced
header for locking modes other than LM_LEGACY.
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PR Review Comment: https://git.openjdk.org/jdk/pull/20067#discussion_r1688668887
