On Mon, 9 Dec 2024 19:26:53 GMT, Coleen Phillimore <cole...@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. The change to java.lang.Class looks good. Looking at #23396, we might need to filter this field too. src/hotspot/share/classfile/javaClasses.cpp line 1504: > 1502: macro(_reflectionData_offset, k, "reflectionData", > java_lang_ref_SoftReference_signature, false); \ > 1503: macro(_signers_offset, k, "signers", > object_array_signature, false); \ > 1504: macro(_modifiers_offset, k, vmSymbols::modifiers_name(), > int_signature, false) Do we need a trailing semicolon here? src/java.base/share/classes/java/lang/Class.java line 1315: > 1313: > 1314: // Set by the JVM when creating the instance of this java.lang.Class > 1315: private transient int modifiers; If this is set by the JVM, can this be marked `final` so JIT compiler can trust this field? Also preferable if we can move this together with components/signers/classData fields. ------------- PR Review: https://git.openjdk.org/jdk/pull/22652#pullrequestreview-2490110846 PR Comment: https://git.openjdk.org/jdk/pull/22652#issuecomment-2631658029 PR Review Comment: https://git.openjdk.org/jdk/pull/22652#discussion_r1876630297 PR Review Comment: https://git.openjdk.org/jdk/pull/22652#discussion_r1876627105
