RFR: 8242888: Convert dynamic proxy to hidden classes

[Chen Liang]

On Mon, 27 May 2024 00:03:41 GMT, ExE Boss <duke 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.
>
> src/java.base/share/classes/jdk/internal/reflect/ReflectionFactory.java line 557:
> 
>> 555:     public static boolean useLegacyProxyImpl() {
>> 556:         var config = config();
>> 557:         return config.useLegacyProxyImpl && !config.useOldSerializableConstructor;
> 
> Suggestion:
> 
>         return config.useLegacyProxyImpl || config.useOldSerializableConstructor;

This site can actually simply be `config.useLegacyProxyImpl` as it's initialized in `loadConfig`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19356#discussion_r1615382817