Integrated: 8316456: StackWalker may skip Continuation::yield0 frame mistakenly

[Mandy Chung]

On Mon, 18 Sep 2023 23:00:09 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> `JVM_MoreStackWalk` has a bug that always assumes that the Java frame
> stream is currently at the frame decoded in the last patch and so always
> advances to the next frame before filling in the new batch of stack frame.
> However `JVM_MoreStackWalk` may return 0.  The library will set 
> the continuation to its parent. It then call `JVM_MoreStackWalk` to continue
> the stack walking but the last decoded frame has already been advanced.
> The Java frame stream is already at the top frame of the parent continuation. .
> The current implementation skips "Continuation::yield0" mistakenly.  This
> only happens with `-XX:+ShowHiddenFrames` or `StackWalker.Option.SHOW_HIDDEN_FRAMES`.
> 
> The fix is to pass the number of frames decoded in the last batch to `JVM_MoreStackWalk`
> so that the VM will determine if the current frame should be skipped or not.
> 
> `test/jdk/jdk/internal/vm/Continuation/Scoped.java` test now correctly checks
> the expected result where "yield0" exists between "enter" and "run" frames.

This pull request has now been integrated.

Changeset: c72f0046
Author:    Mandy Chung <mchung at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/c72f00463fcb1c4a94126932abbc82a2582c10c2
Stats:     210 lines in 7 files changed: 47 ins; 57 del; 106 mod

8316456: StackWalker may skip Continuation::yield0 frame mistakenly

Reviewed-by: rpressler, pchilanomate

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PR: https://git.openjdk.org/jdk/pull/15804