RFR: 8359064: Expose reason for marking nmethod non-entrant to JVMCI client

[Doug Simon]

On Mon, 9 Jun 2025 23:57:46 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

> We recently introduced a way to set the reason why a nmethod was being marked as `not entrant`, see [here](https://github.com/openjdk/jdk/pull/23980) and [here](https://github.com/openjdk/jdk/pull/25338).
> 
> This PR is to expose in the JVMCI interface the reason why the nmethod was flagged as `not entrant`. This will allow JVMCI-based compilers to implement heuristics to handle re-compilations differently based on what happened to earlier versions of a method, for instance, this will likely be used to address this [RFE in Truffle](https://github.com/oracle/graal/issues/11045
> ). 
> 
> Tested on Linux x86_64, ARM with JTREG tier 1-3.

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/InstalledCode.java line 127:

> 125:     }
> 126: 
> 127:     public int getChangeReason() {

Please add javadoc to this method as well as `getChangeReasonDescription`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25706#discussion_r2137514507