RFR: 6617: Make return value its own element

[Marcus Hirt]

On Thu, 5 Dec 2019 15:32:23 GMT, Jessye Coleman-Shapiro <github.com+29706926+jessyec-s at openjdk.org> wrote:

> This patch addresses [JMC-6617](https://bugs.openjdk.java.net/browse/JMC-6617): Better probe format for return values.
> 
> Currently method return values in the agent are described using a parameter element with an index of -1. This patch makes a designated returnvalue element that can be used for return values.
> 
> ----------------
> 
> Commits:
>  - 368cc573: Make return value its own element
> 
> Changes: https://git.openjdk.java.net/jmc/pull/6/files
>  Webrev: https://webrevs.openjdk.java.net/jmc/6/webrev.00
>   Issue: https://bugs.openjdk.java.net/browse/JMC-6617
>   Stats: 272 lines in 11 files changed: 200 ins; 25 del; 47 mod
>   Patch: https://git.openjdk.java.net/jmc/pull/6.diff
>   Fetch: git fetch https://git.openjdk.java.net/jmc pull/6/head:pull/6

core/org.openjdk.jmc.agent/src/main/java/org/openjdk/jmc/agent/jfr/impl/JFREventClassGenerator.java line 120:

> 119: 
> 120: 	private static void createField(ClassWriter cw, JFRTransformDescriptor td, ReturnValue returnValue, Type type) {
> 121: 		if (!td.isAllowedFieldType(type)) {

Why explicitly adding returnValue to the parameters? Isn't the return value part of the transform descriptor?

PR: https://git.openjdk.java.net/jmc/pull/6