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

[Anjian-Wen]

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 quite a lot unsafe setmemory time
>> 
>> on my musebook, the JMH test micro:java.lang.foreign.MemorySegmentZeroUnsafe shows below
>> 
>> before the patch
>> `Benchmark                       (aligned)  (size)  Mode  Cnt   Score   Error  Units
>> MemorySegmentZeroUnsafe.panama       true       1  avgt   30   24.198 ± 0.392  ns/op
>> MemorySegmentZeroUnsafe.panama       true       2  avgt   30   20.688 ± 0.013  ns/op
>> MemorySegmentZeroUnsafe.panama       true       3  avgt   30   20.703 ± 0.045  ns/op
>> MemorySegmentZeroUnsafe.panama       true       4  avgt   30   20.053 ± 0.016  ns/op
>> MemorySegmentZeroUnsafe.panama       true       5  avgt   30   20.682 ± 0.016  ns/op
>> MemorySegmentZeroUnsafe.panama       true       6  avgt   30   20.732 ± 0.061  ns/op
>> MemorySegmentZeroUnsafe.panama       true       7  avgt   30   21.403 ± 0.096  ns/op
>> MemorySegmentZeroUnsafe.panama       true       8  avgt   30   25.268 ± 0.197  ns/op
>> MemorySegmentZeroUnsafe.panama       true      15  avgt   30   27.481 ± 0.195  ns/op
>> MemorySegmentZeroUnsafe.panama       true      16  avgt   30   27.577 ± 0.019  ns/op
>> MemorySegmentZeroUnsafe.panama       true      63  avgt   30  208.893 ± 2.795  ns/op
>> MemorySegmentZeroUnsafe.panama       true      64  avgt   30  199.167 ± 0.936  ns/op
>> MemorySegmentZeroUnsafe.panama       true     255  avgt   30  220.672 ± 0.879  ns/op
>> MemorySegmentZeroUnsafe.panama       true     256  avgt   30  246.256 ± 0.756  ns/op
>> MemorySegmentZeroUnsafe.panama      false       1  avgt   30   23.849 ± 0.088  ns/op
>> MemorySegmentZeroUnsafe.panama      false       2  avgt   30   20.671 ± 0.006  ns/op
>> MemorySegmentZeroUnsafe.panama      false       3  avgt   30   20.694 ± 0.037  ns/op
>> MemorySegmentZeroUnsafe.panama      false       4  avgt   30   20.048 ± 0.010  ns/op
>> MemorySegmentZeroUnsafe.panama      false       5  avgt   30   20.684 ± 0.020  ns/op
>> MemorySegmentZeroUnsafe.panama      false       6  avgt   30   20.685 ± 0.016  ns/op
>> MemorySegmentZeroUnsafe.panama      false       7  avgt   30   21.383 ± 0.086  ns/op
>> MemorySegmentZeroUnsafe.panama      false       8  avgt   30   25.684 ± 0.006  ns/op
>> MemorySegmentZeroUnsafe.panama      false      15  avgt   30   27.593 ± 0.043  ns/op
>> MemorySegmentZeroUnsafe.panama      false      16  avgt   30   28.437 ± 0.228  ns/op
> ...
>
> Anjian-Wen has refreshed the contents of this pull request, and previous commits have been removed. Incremental views are not available.

added the UnsafeMemoryAccessMark and modified the format
added the jmh benchmark

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PR Comment: https://git.openjdk.org/jdk/pull/23890#issuecomment-2830172176