RFR: 8354674: AArch64: Intrinsify Unsafe::setMemory [v8]

[Andrew Dinn]

On Thu, 15 May 2025 16:03:44 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> This intrinsic is generally faster than the current implementation for Panama segment operations for all writes larger than about 8 bytes in size, increasing to more than 2* the performance on larger memory blocks on Graviton 2, between "panama" (C2 generated, what we use now) and "unsafe" (this intrinsic).
>> 
>> 
>> Benchmark                       (aligned)  (size)  Mode  Cnt     Score    Error  Units
>> MemorySegmentFillUnsafe.panama       true  262143  avgt   10  7295.638 ±  0.422  ns/op
>> MemorySegmentFillUnsafe.panama      false  262143  avgt   10  8345.300 ± 80.161  ns/op
>> MemorySegmentFillUnsafe.unsafe       true  262143  avgt   10  2930.594 ±  0.180  ns/op
>> MemorySegmentFillUnsafe.unsafe      false  262143  avgt   10  3136.828 ±  0.232  ns/op
>
> Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Copyright format correction

Still good

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Marked as reviewed by adinn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25147#pullrequestreview-2844529876