RFR: 8242888: Convert dynamic proxy to hidden classes

[Chen Liang]

On Thu, 23 May 2024 03:28:30 GMT, Chen Liang <liach at openjdk.org> wrote:

> Please review this change that convert dynamic proxies implementations to hidden classes, intended to target JDK 24.
> 
> Summary:
> 1. Adds new implementation while preserving the old implementation behind `-Djdk.reflect.useLegacyProxyImpl=true` in case there are compatibility issues.
> 2. ClassLoader.defineClass0 takes a ClassLoader instance but discards it in native code; I updated native code to reuse that ClassLoader for Proxy support.
> 3. ProxyGenerator changes mainly involve using Class data to pass Method list (accessed in a single condy) and removal of obsolete setup code generation.
> 
> Testing: tier1 and tier2 have no related failures.
> 
> Comment: Since #8278, Proxy has been converted to ClassFile API, and infrastructure has changed; now, the migration to hidden classes is much cleaner and has less impact, such as preserving ProtectionDomain and dynamic module without "anchor classes", and avoiding java.lang.invoke package.

A CSR targeting 24 describing the compatibility concerns and behavioral differences is here, somehow not linked by skara: https://bugs.openjdk.org/browse/JDK-8332770
The incompatibilities were much greater in the previous iterations of this issue, such as in dynamic modules, serialization, and in proxy class protection domain. Now these aspects are addressed by this patch, the only real one left is the change in stack trace. Feel free to raise other incompatibilities you have discovered.

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

PR Comment: https://git.openjdk.org/jdk/pull/19356#issuecomment-2126869679