RFR: 8376264: Mixed jstack could not unwind optimized frame [v2]

[Yasumasa Suenaga]

On Wed, 28 Jan 2026 18:19:44 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Refactoring for simplifying
>
> src/jdk.hotspot.agent/linux/native/libsaproc/dwarf.cpp line 105:
> 
>> 103:   _return_address_reg = RA;
>> 104:   _cfa_offset = 0;
>> 105:   _ra_cfa_offset = 8;
> 
> Can you explain where this offset of 8 is coming from. I see it used in a few places.

It comes from RBP -8 (return address on stack).
Return Address (RA) tends to be CFA - 8 because CFA tends to point RBP, and return address is RBP - 8 in that case.
AFAICS return address would be defined in CFI (in CIE at least), thus we can set arbitraly value in initialization.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29398#discussion_r2739157882