On Thu, 28 Aug 2025 21:17:42 GMT, Ioi Lam <[email protected]> wrote:
>> This PR loads the classes for the boot/platform/app loaders with
>> `AOTLinkedClassBulkLoader::preload_classes()`. This happens at the very
>> beginning of `vmClasses::resolve_all()`, before any Java code is executed.
>>
>> - We essentially iterate over all the classes inside the
>> `AOTLinkedClassTable` and adds them into the system dictionary using the new
>> method `SystemDictionary::preload_class()`.
>> - `SystemDictionary::preload_class(..., k)` is lightweight because it's
>> called in a single thread after all super types of `k` have been loaded. So
>> most of the complicated work (such as place holders, circularity detection,
>> etc) in `SystemDictionary::resolve_or_null(..., k)` can be skipped. We also
>> don't need to call into `ClassLoader::load_class()` as the boot/platform/app
>> loaders are well-behaved.
>> - In the assembly phase, we record the mirror, package, protection domain,
>> code source, etc, of these classes. So there's no need to programmatically
>> create them in the production run. See `HeapShared::copy_java_mirror()` and
>> also changes in ClassLoader.java and SecureClassLoader.java.
>
> Ioi Lam has updated the pull request with a new target base due to a merge or
> a rebase. The pull request now contains 20 commits:
>
> - Merge branch 'master' into 8350550-preload-aot-classes-during-vm-bootstrap
> - @DanHeidinga comments -- added comments and asserts about the handling of
> enums
> - @DanHeidinga comment - add test: user enum types are not initialized in
> assembly phase
> - @DanHeidinga comment -- assembly phase should check if URLStreamHandler
> might be overridden in the production run
> - @DanHeidinga comments
> - tightened SystemDictionary::preload_class()
> - Fixed bugs found in JCK
> - added entry in ProblemList-AotJdk.txt due to 8323727
> - more clean up
> - Merge branch 'master' into 8350550-preload-aot-classes-during-vm-bootstrap
> - ... and 10 more: https://git.openjdk.org/jdk/compare/075ddef8...1a8ea501
src/hotspot/share/cds/aotOopChecker.cpp line 53:
> 51: // the production run.
> 52: void AOTOopChecker::check(oop obj) {
> 53: precond(vmClasses::URL_klass()->is_final());
`AOTOopChecker::check` is a generic method, so this precond should ideally be
inside the next block that explicitly handles URL class objects.
src/hotspot/share/cds/aotOopChecker.cpp line 55:
> 53: precond(vmClasses::URL_klass()->is_final());
> 54:
> 55: if (obj->klass()->is_subclass_of(vmClasses::URL_klass())) {
URL is a final class, so shouldn't `obj->klass() == vmClasses::URL_klass()` be
sufficient?
src/hotspot/share/classfile/javaClasses.cpp line 1063:
> 1061:
> 1062: // Statically allocate fixup lists because they always get created.
> 1063: void java_lang_Class::allocate_fixup_lists() {
Do we need `fixup_module_field_list` when `is_using_preloaded_classes` is true?
src/hotspot/share/memory/iterator.inline.hpp line 58:
> 56: ClaimMetadataVisitingOopIterateClosure::do_cld(cld);
> 57: } else {
> 58: assert(AOTLinkedClassBulkLoader::is_pending_aot_linked_class(k),
> "sanity");
Why is the null check and assert not valid anymore?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/26375#discussion_r2331108015
PR Review Comment: https://git.openjdk.org/jdk/pull/26375#discussion_r2334124611
PR Review Comment: https://git.openjdk.org/jdk/pull/26375#discussion_r2334124798
PR Review Comment: https://git.openjdk.org/jdk/pull/26375#discussion_r2334211674
