RFR: 8253525: Implement getInstanceSize/sizeOf intrinsics [v6]

[Serguei Spitsyn]

On Tue, 10 Nov 2020 12:04:21 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> This is fork off the SizeOf JEP, JDK-8249196. There is already the entry point in JDK that can use the intrinsic like this: `Instrumentation.getInstanceSize`. Therefore, we can implement the C1/C2 intrinsic now, hook it up to `Instrumentation`, and let the tools use that fast path today.
>> 
>> With this patch, JOL is able to be close to `deepSizeOf` implementation from SizeOf JEP. 
>> 
>> Example performance improvements for sizing up a custom linked list:
>> 
>> Benchmark                     (size)  Mode  Cnt       Score      Error  Units
>> 
>> # Default
>> LinkedChainBench.linkedChain       1  avgt    5     705.835 ±    8.051  ns/op
>> LinkedChainBench.linkedChain      10  avgt    5    3148.874 ±   37.856  ns/op
>> LinkedChainBench.linkedChain     100  avgt    5   28693.256 ±  142.254  ns/op
>> LinkedChainBench.linkedChain    1000  avgt    5  290161.590 ± 4594.631  ns/op
>> 
>> # Instrumentation attached, no intrinsics
>> LinkedChainBench.linkedChain       1  avgt    5    159.659 ±   19.238  ns/op
>> LinkedChainBench.linkedChain      10  avgt    5    717.659 ±   22.540  ns/op
>> LinkedChainBench.linkedChain     100  avgt    5   7739.394 ±  111.683  ns/op
>> LinkedChainBench.linkedChain    1000  avgt    5  80724.238 ± 2887.794  ns/op
>> 
>> # Instrumentation attached, new intrinsics
>> LinkedChainBench.linkedChain       1  avgt    5     95.254 ±   0.808  ns/op
>> LinkedChainBench.linkedChain      10  avgt    5    261.564 ±   8.524  ns/op
>> LinkedChainBench.linkedChain     100  avgt    5   3367.192 ±  21.128  ns/op
>> LinkedChainBench.linkedChain    1000  avgt    5  34148.851 ± 373.080  ns/op
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:
> 
>  - Trim down the iteration count, and use -Xbatch to wait for compilation
>  - Use proper constant names in the test
>  - Merge branch 'master' into JDK-8253525-sizeof-intrinsics
>  - The new intrinsic-related test
>  - Revert the change to test
>  - Merge branch 'master' into JDK-8253525-sizeof-intrinsics
>  - Add new intrinsics to toBeInvestigated list in CheckGraalIntrinsics.java
>  - 8253525: Implement getInstanceSize/sizeOf intrinsics

Aleksey,

Thank you for the update!
It looks good to me.
One more nit, I forgot to list in my previous comment, is uneeded '()' around comparisons:
`+    static final int REF_SIZE = ((compressedOops == null) || (compressedOops == true)) ?  4 : 8;`

Thanks,
Serguei

-------------

Marked as reviewed by sspitsyn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/650