New lazy vals implementation

[szymon-rd]

Cleaned up version of #14545

Implementing the new lazy vals scheme mentioned in #6979, fixing #7140

New PR to avoid force pushing to main branch of the previous author.

Fixes #15149 as well

[szymon-rd]

Applied #14780

[szymon-rd]

Fixed #15149

[szymon-rd]

Wouldn't it be a better idea to use MethodHandles instead of Unsafe?

[szymon-rd]

TODO: Add test for serialization of non transient lazy val.

[sjrd]

MethodHandles are only available on JDK 9+. We have to support 8+.

[bishabosha]

MethodHandles are only available on JDK 9+. We have to support 8+.

for clarity I assume you both mean VarHandle, as method handles were added in JDK 7

[szymon-rd]

@bishabosha I actually meant getter/setter method handles. As far as I know they provide direct access to the field and do not actually rely on getter/setters. It would be nice to perform some benchmarks for sure.

[bishabosha]

@bishabosha I actually meant getter/setter method handles. As far as I know they provide direct access to the field and do not actually rely on getter/setters. It would be nice to perform some benchmarks for sure.

AFAIK these do not support atomic operations like CAS, but varhandle is a direct replacement for methods in Unsafe

[szymon-rd]

@odersky Could you take a look at this, please?

[odersky]

Can you re-push that to staging? That way we can collaborate on it.

[szymon-rd]

Created a new PR to change the source branch: #15296