On Thu, 8 May 2025 11:22:30 GMT, Alan Bateman <[email protected]> wrote:
> Implementation changes for [JEP 500: Prepare to Make Final Mean > Final](https://openjdk.org/jeps/500). > > Field.set (and Lookup.unreflectSetter) are changed to allow/warn/debug/deny > when mutating a final instance field. JFR event recorded if final field > mutated. Spec updates to Field.set, Field.setAccessible and Module.addOpens > to align with the proposal in the JEP. > > HotSpot is updated to add support for the new command line options. To aid > diagnosability, -Xcheck:jni reports a fatal error when a mutating a final > field with JNI, and -Xlog:jni=debug can help identity when JNI code mutates > finals. For now, JNI code is allowed to set the "write-protected" fields > System.in/out/err, we can re-visit once we change the > System.setIn/setOut/setErr methods to not use JNI (I prefer to keep this > separate to this PR because there is a small startup regression to address > when changing System.setXXX). > > There are many new tests. A small number of existing tests are changed to run > /othervm as reflectively opening a package isn't sufficient. Changing the > tests to /othervm means that jtreg will launch the agent with the command > line options to open the package. > > Testing: tier1-6 Hotspot changes look good. src/hotspot/share/runtime/fieldDescriptor.cpp line 49: > 47: } > 48: > 49: bool fieldDescriptor::is_mutable_static_final() const { Please, migrate `ciField::initialize_from()` from ad-hoc checks to `fieldDescriptor::is_mutable_static_final()`. diff --git a/src/hotspot/share/ci/ciField.cpp b/src/hotspot/share/ci/ciField.cpp index cbe0cadbc93..dffc387612d 100644 --- a/src/hotspot/share/ci/ciField.cpp +++ b/src/hotspot/share/ci/ciField.cpp @@ -267,17 +267,7 @@ void ciField::initialize_from(fieldDescriptor* fd) { // not be constant is when the field is a *special* static & final field // whose value may change. The three examples are java.lang.System.in, // java.lang.System.out, and java.lang.System.err. - assert(vmClasses::System_klass() != nullptr, "Check once per vm"); - if (k == vmClasses::System_klass()) { - // Check offsets for case 2: System.in, System.out, or System.err - if (_offset == java_lang_System::in_offset() || - _offset == java_lang_System::out_offset() || - _offset == java_lang_System::err_offset()) { - _is_constant = false; - return; - } - } - _is_constant = true; + _is_constant = !fd->is_mutable_static_final(); } else { // An instance field can be constant if it's a final static field or if // it's a final non-static field of a trusted class (classes in ------------- Marked as reviewed by vlivanov (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/25115#pullrequestreview-3254635791 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2369888932
