RFR: 8139457: Array bases are aligned at HeapWord granularity [v11]

[Roman Kennke]

On Thu, 19 Jan 2023 10:43:09 GMT, Stefan Karlsson <stefank 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 25 commits:
>> 
>>  - Merge branch 'master' into JDK-8139457
>>  - Fix gtest for correct base offsets in 32bit builds
>>  - Fix cast warning
>>  - Revert relaxation of array length
>>  - Add guards to ArrayBaseOffsets test to allow running with -UseCompressedClassPointers
>>  - Fix another cast warning
>>  - Clean cast warning from size_t to int
>>  - Clear leading 32bits in Z array allocator
>>  - SA adjustments
>>  - Test for 32bit build
>>  - ... and 15 more: https://git.openjdk.org/jdk/compare/500b45e1...c278a53b
>
> src/hotspot/share/gc/shared/collectedHeap.cpp line 444:
> 
>> 442:   payload_start = payload_start / HeapWordSize;
>> 443:   Copy::fill_to_words(start + payload_start,
>> 444:                       words - payload_start, value);
> 
> This mixes bytes and words. I don't think this is correct.

How does it mix bytes and words? start is a heapword*, payload_start is in word units (I am going to change the line above to make it clearer, words is words ;-).

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PR: https://git.openjdk.org/jdk/pull/11044