RFR: 8370708: RISC-V: Add VerifyStackAtCalls [v5]

[Robbin Ehn]

On Tue, 4 Nov 2025 07:58:34 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/riscv.ad line 1187:
>> 
>>> 1185: }
>>> 1186: 
>>> 1187: constexpr uint64_t MAJIK_DWORD = 0xabbaabbaabbaabbaull;
>> 
>> Looking at `PhaseChaitin::dump_frame`, I found the hard-coded MAJIK word for x86. Should we add RISCV MAJIK DWORD here?
>> https://github.com/openjdk/jdk/blob/576f9694b092f2a11a6a4e5a82c2b0e12203bd9c/src/hotspot/share/opto/chaitin.cpp#L2409-L2411
>
> Oh, yes.
> 
> The reason I did not want to use "BADB100D" is because of sign extension of B if we would be off by 4 bytes.
> E.i. I want a zero bit on all 4-byte borders. And  ABBA....ABBA is at lets easier for me to find when eye-balling.
> 
> I have to think what to do here: do we want same majik on all platforms.... etc...

Fixed

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PR Review Comment: https://git.openjdk.org/jdk/pull/28005#discussion_r2490349411