RFR: 8259937: guarantee(loc != NULL) failed: missing saved register with native invoker [v4]

[Vladimir Ivanov]

On Wed, 24 Feb 2021 16:12:59 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> We spotted this issue with Shenandoah and I managed to write a simple
>> test case that reproduces it reliably with Shenandoah but the issue is
>> independent of the GC.
>> 
>> The loop in the test case calls a native invoker with an oop live in
>> rbp. rbp is saved in the native invoker stub's frame. A safepoint is
>> triggered from the safepoint check in the native invoker. The stack
>> walking code sees that rbp contains an oop but can't find where that
>> oop is stored. That's because stack walking updates the caller's frame
>> with the location of rbp in the callee on calls to
>> frame::sender(). But the current code sets the last java frame to be
>> the compiled frame where rbp is live. So there's no call to
>> frame::sender() to update the location rbp. The fix I propose is that
>> the frame of the native invoker be visible by stack walking. On a
>> safepoint, stack walking starts from the native invoker thread, then
>> calls frame::sender() to move to the compiled frame. That causes rbp
>> to be properly recorded with its location in the native invoker frame.
>> 
>> Same problem affects both x86 and aarch64. I've tested this patch with:
>> 
>> make run-test TEST="java/foreign" TEST_VM_OPTS="-Xcomp" JTREG="TIMEOUT_FACTOR=10"
>> 
>> on both platforms.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Revert "test & debug"
>   
>   This reverts commit cb9dd24c9fcccc6997e9fca874e2860f966b9576.

Marked as reviewed by vlivanov (Reviewer).

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