RFR: 8324186: AARCH64: Use "dmb.ishst+dmb.ishld" for release barrier [v4]

[Fei Yang]

On Fri, 26 Jan 2024 05:43:00 GMT, kuaiwei <duke at openjdk.org> wrote:

>> Details is https://mail.openjdk.org/pipermail/hotspot-compiler-dev/2024-January/071921.html.
>> Using a combined dmb.ish for release barrier will introduce a heavy storeload barrier. Use "dmb.ishst+dmb.ishld" pair instead, we can gain performance improvement on N1 and N2 architecture. The benchmark is test/micro/org/openjdk/bench/vm/compiler/FinalFieldInitialize.java
>> Run with ParallelGC to minimalize impact of gc barrier.
>> 
>> make test TEST="micro:org.openjdk.bench.vm.compiler.FinalFieldInitialize" MICRO="VM_OPTIONS=-XX:+UseParallelGC"
>> ...
>> FinalFieldInitialize.testAllocWithFinal  thrpt    9  1411.601 ?  6.546  ops/s
>> 
>> Without the patch
>> 
>> FinalFieldInitialize.testAllocWithFinal  thrpt    9  1214.575 ? 14.217  ops/s
>
> kuaiwei has updated the pull request incrementally with one additional commit since the last revision:
> 
>   change AlwaysMergeDMB diagnostic option

LGTM. Thanks.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17511#pullrequestreview-1845236858