RFR: 8259937: guarantee(loc != NULL) failed: missing saved register with native invoker [v2]

[Jorn Vernee]

On Fri, 12 Feb 2021 10:41:18 GMT, Andrew Dinn <adinn at openjdk.org> wrote:

>> Seems reasonable.
>
> The code here looks ok. I'm slightly concerned about the consequences of adding a new stack frame visible to stack walking code. Does this have the potential to break serviceability code that reports and/or analyzes stack frames (whether that's code in OpenJDK or 3rd party code)?

@adinn I'm not aware of any such use-cases (whether in the JDK or elsewhere). They would only be affected if they were using Panama native calls, which were introduce pretty recently, and are also still in incubator state. 

Inside the JDK the only place where this code is currently being used is in the jdk/java/foreign test stuite, as well as in the internal implementation of the Panama linker. If that test suite still passes I'm happy to call it safe.

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PR: https://git.openjdk.java.net/jdk/pull/2528