Sharing the markword (aka Valhalla's markword use)

[Thomas Stüfe]

In Lilliput, the prototype header contains the nKlass ID.

Cheers, Thomas

On Mon, Mar 11, 2024 at 2:23 AM David Holmes <david.holmes at oracle.com>
wrote:

> On 10/03/2024 1:38 pm, John Rose wrote:
> > What Dan said.  Here’s more color commentary:
> <snip>
> > I suggest adding, to Klass itself, a field which is a prototype
> > header for the object, with all the right bits in place ...
> > (I thought we already had something like this somewhere, but
> > a quick check came up empty…)
>
> We used to have the biased-locking prototype header.
>
> klass.hpp
>    // Biased locking support
>    // Note: the prototype header is always set up to be at least the
>    // prototype markOop. If biased locking is enabled it may further be
>    // biasable and have an epoch.
>    markOop prototype_header() const      { return _prototype_header; }
>
> Cheers,
> David
>
>
>
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