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

[Robbin Ehn]

On Tue, 4 Nov 2025 04:11:48 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>> 
>>  - Merge branch 'master' into vsc
>>  - Forgot fix format for VSAC
>>  - Fixed format
>>  - Label name
>>  - li->mv, format, space
>>  - Draft
>
> 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...

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PR Review Comment: https://git.openjdk.org/jdk/pull/28005#discussion_r2489075618