RFR: 8308899: Introduce Classfile.Context and improve Classfile.Option(s) [v2]

[Chen Liang]

On Thu, 1 Jun 2023 15:20:27 GMT, Adam Sotona <asotona at openjdk.org> wrote:

>> Classfile context object and multi-state options have been discussed at https://mail.openjdk.org/pipermail/classfile-api-dev/2023-May/000321.html
>> This patch implements the proposed changes in Classfile API and fixes all affected code across JDK sources and tests.
>> 
>> Please review.
>> 
>> Thanks,
>> Adam
>
> Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fixed benchmarks

In fact, I think we can probably mark Classfile as value-based. Then, whether it's created from a factory at every call or if it's cached (my first 2 review comments) no longer matters as much; the caching behavior will be handled by individual option instances (such as class hierarchy caching in the class hierarchy option's resolver)

src/java.base/share/classes/java/lang/Module.java line 1593:

> 1591:     private Class<?> loadModuleInfoClass(InputStream in) throws IOException {
> 1592:         final String MODULE_INFO = "module-info";
> 1593:         var cc = Classfile.of(Classfile.ConstantPoolSharingOption.DO_NOT_SHARE_CONSTANT_POOL);

This `cc` can be stored in a static final field instead.

src/java.base/share/classes/jdk/internal/classfile/Classfile.java line 55:

> 53: 
> 54:     static Classfile of() {
> 55:         return new ClassfileImpl();

We can create a static final field in `ClassfileImpl` holding a default instance equivalent to that created by `new ClassfileImpl()` and have the `of()` factory return that instance instead.

src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java line 840:

> 838:         try {
> 839:             //clone SplitConstantPool with alternate context
> 840:             var cc = Classfile.of(Classfile.StackMapsOption.DO_NOT_GENERATE_STACK_MAPS);

This should set the Class hierarchy resolver, patch dead code, and filter dead labels options from the original context.

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

PR Comment: https://git.openjdk.org/jdk/pull/14180#issuecomment-1572260124
PR Review Comment: https://git.openjdk.org/jdk/pull/14180#discussion_r1213300095
PR Review Comment: https://git.openjdk.org/jdk/pull/14180#discussion_r1213302665
PR Review Comment: https://git.openjdk.org/jdk/pull/14180#discussion_r1213314212