[lworld] RFR: 8363846: [lworld] Make Class.isIdentityClass() non-native

[Chen Liang]

On Tue, 22 Jul 2025 17:41:27 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> This moves isIdentityClass() implementation to Class.java, and checks within the JVM that is_identity_class() doesn't check the access flags for an ArrayKlass, since AccessFlags aren't initialized in ArrayKlasses.  The AccessFlags should be moved from Klass.hpp to InstanceKlass.cpp in mainline but that's a more complicated change and has several pieces.
> Added a test.
> Tested with tier1 locally.

is_identity_class seems widely used in many areas, such as C2 - do we need to verify those usages?

src/hotspot/share/oops/instanceKlass.cpp line 3594:

> 3592: }
> 3593: 
> 3594: void InstanceKlass::check_can_be_annotated_with_NullRestricted(InstanceKlass* type, Symbol* container_klass_name, TRAPS) {

I am surprised we still have this remnant of implicit construction now we have strict fields - shouldn't we replace this with strictness checks?

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PR Review: https://git.openjdk.org/valhalla/pull/1514#pullrequestreview-3045150746
PR Review Comment: https://git.openjdk.org/valhalla/pull/1514#discussion_r2224022195