On Fri, 7 Aug 2026 20:08:07 GMT, Stefan Karlsson <[email protected]> wrote:

>> The main objectives for this PR are:
>>  1) Compact Object Headers needs the Object Monitor Table to work.
>>  2) Both Compact Object Headers 
>> ([JDK-8360700](https://bugs.openjdk.org/browse/JDK-8360700)) and Object 
>> Monitor Table ([JDK-8379782](https://bugs.openjdk.org/browse/JDK-8379782)) 
>> are now enabled by default.
>>  3) If we always use the Object Monitor Table, we will free up lots of bits 
>> in the markword, that could be of use to others (read GC).
>>  4) If we don't need to maintain any "monitor pointer in the mark word" 
>> code, we will simplify the code base.
>> 
>> Therefore this PR will remove the `UseObjectMonitorTable` flag and related 
>> code.
>> 
>> Note that this PR only removes the most obvious use of the 
>> `UseObjectMonitorTable` in the code base. This is to ease the burden on the 
>> reviewers. [JDK-8389938](https://bugs.openjdk.org/browse/JDK-8389938) has 
>> been created to finalize the work by removing the less obvious code, like no 
>> longer used mark word code in different GCs. 
>> 
>> The code has passed tier1-7 testing on supported platforms and smoke testing 
>> using QEMU on `RISC-V`, `PowerPC` and `s390`.
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> src/hotspot/share/runtime/objectMonitor.cpp line 352:
> 
>> 350:          ", encoded this=" INTPTR_FORMAT, object()->mark().value(),     
>>        \
>> 351:          markWord::encode(this).value());
>> 352: 
> 
> Hmm. Was this assert wrong before. Should it have been 
> `assert(!UseObjectMonitorTable || ...`? Would that mean that the assert would 
> still be useful?

Ignore this. `markWord::encode()` is one of those functions that only made 
sense to call with the OMT.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/32257#discussion_r3749803005

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