Withdrawn: 8331658: secondary_super_cache does not scale well: C1

[Andrew Haley]

On Tue, 28 May 2024 13:22:41 GMT, Andrew Haley <aph at openjdk.org> wrote:

> This is the C1 version of [JDK-8180450](https://bugs.openjdk.org/browse/JDK-8180450).
> 
> The new logic in this PR is as simple as I can make it. It is a somewhat-simplified version of the C2 change in [JDK-8180450](https://bugs.openjdk.org/browse/JDK-8180450). In order to reduce risk I haven't touched the existing slow subtype stub.
> The register allocation logic in the existing code is pretty gnarly, and I have no desire to break anything at this point in the release cycle, so I have allocated just one register more than the existing code does.
> 
> Performance is pretty good. Before and after:
> 
> x64, AMD 2950X, 8 cores:
> 
> 
> Benchmark                                   Mode  Cnt   Score   Error  Units
> SecondarySuperCacheHits.test                avgt    5   0.959 ± 0.091  ns/op
> SecondarySuperCacheInterContention.test     avgt    5  42.931 ± 6.951  ns/op
> SecondarySuperCacheInterContention.test:t1  avgt    5  42.397 ± 7.708  ns/op
> SecondarySuperCacheInterContention.test:t2  avgt    5  43.466 ± 8.238  ns/op
> SecondarySuperCacheIntraContention.test     avgt    5  74.660 ± 0.127  ns/op
> 
> SecondarySuperCacheHits.test                avgt    5  1.480 ± 0.077  ns/op
> SecondarySuperCacheInterContention.test     avgt    5  1.461 ± 0.063  ns/op
> SecondarySuperCacheInterContention.test:t1  avgt    5  1.767 ± 0.078  ns/op
> SecondarySuperCacheInterContention.test:t2  avgt    5  1.155 ± 0.052  ns/op
> SecondarySuperCacheIntraContention.test     avgt    5  1.421 ± 0.002  ns/op
> 
> AArch64, Mac M3, 8 cores:
> 
> 
> Benchmark                     Mode  Cnt  Score   Error  Units
> SecondarySuperCacheHits.test                avgt    5    0.835 ±  0.021  ns/op
> SecondarySuperCacheInterContention.test     avgt    5   74.078 ± 18.095  ns/op
> SecondarySuperCacheInterContention.test:t1  avgt    5   81.863 ± 42.492  ns/op
> SecondarySuperCacheInterContention.test:t2  avgt    5   66.293 ± 11.254  ns/op
> SecondarySuperCacheIntraContention.test     avgt    5  335.563 ±  6.171  ns/op
> 
> SecondarySuperCacheHits.test                avgt    5  1.212 ±  0.004  ns/op
> SecondarySuperCacheInterContention.test     avgt    5  0.871 ±  0.002  ns/op
> SecondarySuperCacheInterContention.test:t1  avgt    5  0.626 ±  0.003  ns/op
> SecondarySuperCacheInterContention.test:t2  avgt    5  1.115 ±  0.006  ns/op
> SecondarySuperCacheIntraContention.test     avgt    5  0.696 ±  0.001  ns/op
> 
> 
> 
> The first test, `SecondarySuperCacheHits`, showns a small regression. It's the "happy path" which simply checks the same subclass again and again in a loop, i...

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/19426