RFR: 8313800: AArch64: SA stack walking code having trouble finding sender frame when invoking LambdaForms is involved

[Andrew Haley]

On Thu, 7 Sep 2023 21:31:24 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> This PR fixes a specific problem caused by using r29/rfp to unwind Java code. For some time we have treated r29 as a callee-saved scratch register, and it is freely used by C2-generated code. Therefore, any code in SA that uses getFP() in a compiled frame is very likely to come to grief.
>> 
>> I believe this is the root cause of 8313800, but it's very hard to prove that because because it's something of an intermittent fault.
>
> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/aarch64/AARCH64Frame.java line 331:
> 
>> 329: 
>> 330:   //------------------------------------------------------------------------------
>> 331:   // frame::adjust_unextended_sp
> 
> This is just repeating the comment below.

Thanks.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15624#discussion_r1319600134