[vectorIntrinsics] RFR: Optimize mem barriers for ByteBuffer cases

[Radoslaw Smogura]

On Tue, 27 Jul 2021 20:42:13 GMT, Radoslaw Smogura <github.com+7535718+rsmogura at openjdk.org> wrote:

> # Description
> This change tries to remove mem bars for byte buffer cases.
> 
> Previously mem bars were inserted almost unconditionally if attemp to native memory acees where detected. This patch tries to follow up inline_unsafe_access and insert bar only if can't determine if it's heap or off-heap (type missmatch cases are not ported).
> 
> # Testing
> Memory tests should include rollbacking JDK changes, and leaving only hotspot, as intrinsics should be well guarded
> 
> # Notes
> Polluted cases to be addressed later
> 
> # Benchmarks
> 
> Benchmark                                (size)  Mode  Cnt    Score   Error  Units
> ByteBufferVectorAccess.arrays              1024  avgt   10   12.585 ? 0.409  ns/op
> ByteBufferVectorAccess.directBuffers       1024  avgt   10   19.962 ? 0.080  ns/op
> ByteBufferVectorAccess.heapBuffers         1024  avgt   10   15.878 ? 0.187  ns/op
> ByteBufferVectorAccess.pollutedBuffers2    1024  avgt   10  123.702 ? 0.723  ns/op
> ByteBufferVectorAccess.pollutedBuffers3    1024  avgt   10  223.928 ? 1.906  ns/op
> 
> Before
> 
> Benchmark                                (size)  Mode  Cnt    Score   Error  Units
> ByteBufferVectorAccess.arrays              1024  avgt   10   14.730 ? 0.061  ns/op
> ByteBufferVectorAccess.directBuffers       1024  avgt   10   77.707 ? 4.867  ns/op
> ByteBufferVectorAccess.heapBuffers         1024  avgt   10   76.530 ? 1.076  ns/op
> ByteBufferVectorAccess.pollutedBuffers2    1024  avgt   10  143.331 ? 1.096  ns/op
> ByteBufferVectorAccess.pollutedBuffers3    1024  avgt   10  286.645 ? 3.444  ns/op

I did slighlty bigger refactor and pulled out logic responsible for setting decorators from library_call.

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PR: https://git.openjdk.java.net/panama-vector/pull/104