RFR: 8139457: Array bases are aligned at HeapWord granularity [v61]

[Coleen Phillimore]

On Fri, 27 Oct 2023 10:31:22 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Roman Kennke has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 90 commits:
>> 
>>  - Merge branch 'master' into JDK-8139457
>>  - Fix ARM build
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8139457
>>  - Various cleanups
>>  - RISC changes
>>  - Move gap init into allocate_header() (x86)
>>  - Fix gtest failure on x86
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8139457
>>  - Fix comments
>>  - Fix inconsistencies in argument naming C1_MacroAssembler::allocate_array()
>>  - ... and 80 more: https://git.openjdk.org/jdk/compare/9bfa0829...7eaca124
>
> Also, I think we can handle the issues with `ByteBuffer::alignedSlice`, `ByteBuffer::alignmentOffset`, `MethodHandles::byteArrayViewVarHandle` and `MethodHandles::byteBufferViewVarHandle` separately, ahead of this PR.
> 
> There is already a bug in the spec of these methods, as they try to give alignment guarantees for heap memory that the VM spec does not support.
> 
> I've filed a couple of JBS issues for these: https://bugs.openjdk.org/browse/JDK-8318967 & https://bugs.openjdk.org/browse/JDK-8318966

@JornVernee  thank you for filing these separate issues.

@rkennke I noticed that the two files below require copyright updates.

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/memory/Universe.java
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/Array.java

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PR Comment: https://git.openjdk.org/jdk/pull/11044#issuecomment-1783392459