The purpose of this PR is to simplify JNI code and also to avoid unnecessary `InstanceKlass::cast()` calls.
This PR is intended to be a strict clean-up that preserves existing behaviors. The following helper functions are added to simplify boilerplate code in JNI methods. static Klass* java_lang_Class::as_Klass(jobject java_class); static InstanceKlass* java_lang_Class::as_InstanceKlass(oop java_class); static InstanceKlass* java_lang_Class::as_InstanceKlass(jobject java_class); Klass* get_klass_considering_redefinition(jclass cls, JavaThread *thread); InstanceKlass* get_instance_klass_considering_redefinition(jclass cls, JavaThread *thread); Notes: [1] Before this PR, we have both patterns: java_lang_Class::as_Klass(JNIHandles::resolve(cls)); java_lang_Class::as_Klass(JNIHandles::resolve_non_null(cls)); If `cls` is null, we would get an assert in both cases (`as_Klass()` requires a non-null input). Therefore, I am using `resolve_non_null()` in the `jobject` versions of `as_Klass()`. [2] I refactored `JvmtiThreadState::class_to_verify_considering_redefinition()` so that the caller of this funcation can avoid using `InstanceKlass::cast()`. This is possible because we ONLY store `InstanceKlass*` in `JvmtiThreadState::set_class_being_redefined()` I also removed a few cases of unnecessary `InstanceKlass::cast()`. ------------- Commit messages: - more fixes - tmp: Clean up java mirror handling in JNI methods Changes: https://git.openjdk.org/jdk/pull/27158/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27158&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8367142 Stats: 278 lines in 19 files changed: 46 ins; 65 del; 167 mod Patch: https://git.openjdk.org/jdk/pull/27158.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/27158/head:pull/27158 PR: https://git.openjdk.org/jdk/pull/27158
