On Wed, 8 Apr 2026 12:40:03 GMT, Stefan Karlsson <[email protected]> wrote:

>> @caspernorrbin Started cleaning up markWord.hpp with 
>> https://github.com/openjdk/valhalla/pull/2238, but while reviewing that 
>> patch I realized that it would be good to make a number of simplifications 
>> before proceeding. I talked that through with Casper and @Arraying. Those 
>> changes are now done, and I've taken a pass through markWord.hpp to follow 
>> in the spirit of what Casper did and some of the things we three talked 
>> about.
>> 
>> I've also made updates and clarifications to the comments.
>> 
>> One main thing about this proposal is that I want it to be crystal clear 
>> when we talk about bit and when we talk about a mask. To make sure that the 
>> bit constants only ever refers to one bit I've added helpers to verify that 
>> this is the case.
>
> src/hotspot/share/oops/markWord.hpp line 50:
> 
>> 48: //  klass:22   hash:31  valhalla:4  age:4  self-fwd:1  lock:2
>> 49: //
>> 50: //  - hash - contains the identity hash value: largest value is 31 bits, 
>> see
> 
> Sections below have been moved around to follow the order that we have in the 
> bits above. It might be better to move it the other way around because that's 
> how the constants are listed. And then I can add klass bits as well.

I swapped the order.

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PR Review Comment: 
https://git.openjdk.org/valhalla/pull/2310#discussion_r3051391412

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