On Wed, 11 Dec 2024 18:15:57 GMT, Dan Heidinga <heidi...@openjdk.org> wrote:
>> The Class.getModifiers() method is implemented as a native method in >> java.lang.Class to access a field that we've calculated when creating the >> mirror. The field is final after that point. The VM doesn't need it >> anymore, so there's no real need for the jdk code to call into the VM to get >> it. This moves the field to Java and removes the intrinsic code. I >> promoted the compute_modifiers() functions to return int since that's how >> java.lang.Class uses the value. It should really be an unsigned short >> though. >> >> There's a couple of JMH benchmarks added with this change. One does show >> that for array classes for non-bootstrap class loader, this results in one >> extra load which in a long loop of just that, is observable. I don't think >> this is real life code. The other benchmarks added show no regression. >> >> Tested with tier1-8. > > src/java.base/share/classes/java/lang/Class.java line 244: > >> 242: classLoader = loader; >> 243: componentType = arrayComponentType; >> 244: modifiers = 0; > > The comment above about assigning a parameter to the field to prevent the JIT > from assuming an incorrect default also should apply to the new `modifiers` > field. I think the constructor, which is never called, should also pass in a > `dummyModifiers` value rather than using 0 directly Yes, definitely, didn't see that this is the right way to do this. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/22652#discussion_r1887157349
