RFR: 8351140: RISC-V: Intrinsify Unsafe::setMemory [v2]

[Martin Doerr]

On Fri, 28 Mar 2025 11:24:43 GMT, Anjian-Wen <duke at openjdk.org> wrote:

>> From [JDK-8329331](https://bugs.openjdk.org/browse/JDK-8329331), add riscv unsafe::setMemory intrinsic’s generator generate_unsafe_setmemory. This intrinsic optimizes about 15%-20% unsafe setmemory time
>
> Anjian-Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   RISC-V: Intrinsify Unsafe::setMemory
>   
>   add unsafe memory check

Unfortunately, 'UnsafeMemoryAccessMark' doesn't work like this. Your current implementation marks the code region in `unsafe_setmemory`, but the accesses are done in `StubRoutines::_jbyte_fill` which are outside of that region.

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PR Comment: https://git.openjdk.org/jdk/pull/23890#issuecomment-2761102248