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<body><div style="font-family: sans-serif;"><div class="plaintext" style="white-space: normal;"><p dir="auto">Thanks, David; I wondered when Klass::prototype_header came and went.</p>
<p dir="auto">Thomas, a peek at klass.hpp shows that Klass::prototype_header has returned to us in Lilliput, with helpers like oopDesc::init_mark. Nice. That looks like a good way to manage Valhalla’s new hoisted metadata bits as well as other header bits.</p>
<p dir="auto">On 11 Mar 2024, at 1:55, Thomas Stüfe wrote:</p>
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<div>In Lilliput, the prototype header contains the nKlass ID.</div>
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<div>Cheers, Thomas<br></div>
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<div dir="ltr" class="gmail_attr">On Mon, Mar 11, 2024 at 2:23 AM David Holmes <<a href="mailto:david.holmes@oracle.com">david.holmes@oracle.com</a>> wrote:<br></div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 10/03/2024 1:38 pm, John Rose wrote:<br>
> What Dan said. Here’s more color commentary:<br>
<snip><br>
> I suggest adding, to Klass itself, a field which is a prototype<br>
> header for the object, with all the right bits in place ...<br>
> (I thought we already had something like this somewhere, but<br>
> a quick check came up empty…)<br>
<br>
We used to have the biased-locking prototype header.<br>
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klass.hpp<br>
// Biased locking support<br>
// Note: the prototype header is always set up to be at least the<br>
// prototype markOop. If biased locking is enabled it may further be<br>
// biasable and have an epoch.<br>
markOop prototype_header() const { return _prototype_header; }<br>
<br>
Cheers,<br>
David<br>
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