RFR: 8318124: JFR: Rewrite instrumentation to use Class-File API

[Chen Liang]

On Sun, 15 Oct 2023 20:20:48 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> Hi,
> 
> Could I have a review of an enhancement that replaces the use of ASM with the new Class-File API. This change only deals with bytecode that writes event data into buffers. Bytecode transformations carried out by classes in jdk.jfr.internal.intrument package are kept as is. Plan is to try to replace those with events in java.base.
> 
> To simplify the review process, I have tried to keep the code in the classes EventInstrumentation and EventClassBuilder similar to what existed before. Further refactorizations may happen at a later stage. 
> 
> Testing: tier1-3 + jdk/jdk/jfr
> 
> Thanks
> Erik

src/jdk.jfr/share/classes/jdk/jfr/internal/EventClassBuilder.java line 73:

> 71:         byte[] bytes = Classfile.of().build(ClassDesc.of(fullClassName), cb -> build(cb));
> 72:         try {
> 73:             String name = "/Users/egahlin/DynamicEvent" + (idCounter.longValue() - 1);

You probably wish to use `Bytecode.log` instead.

src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line 204:

> 202:         String typeDescriptor = classDesc.descriptorString();
> 203:         for (ClassElement ce : classModel.elements()) {
> 204:             if (ce instanceof RuntimeVisibleAnnotationsAttribute rvaa) {

You can use `classModel.findAttribute(Attributes.RUNTIME_VISIBLE_ANNOTATIONS)` instead of looping.

src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line 227:

> 225:         for (MethodModel m : classModel.methods()) {
> 226:             for (MethodElement me : m.elements()) {
> 227:                 if (me instanceof RuntimeVisibleAnnotationsAttribute rvaa) {

Same remark, `m.findAttribute(Attributes.RUNTIME_VISIBLE_ANNOTATIONS)`

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PR Review Comment: https://git.openjdk.org/jdk/pull/16195#discussion_r1359971991
PR Review Comment: https://git.openjdk.org/jdk/pull/16195#discussion_r1359976477
PR Review Comment: https://git.openjdk.org/jdk/pull/16195#discussion_r1359976987