RFR: 8339526: C2: store incorrectly removed for clone() transformed to series of loads/stores [v3]

[Roland Westrelin]

On Tue, 21 Oct 2025 11:41:41 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Roland Westrelin 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 six additional commits since the last revision:
>> 
>>  - review
>>  - Merge branch 'master' into JDK-8339526
>>  - review
>>  - Merge branch 'master' into JDK-8339526
>>  - Update src/hotspot/share/opto/arraycopynode.cpp
>>    
>>    Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
>>  - test & fix
>
>> I will just run (...) a set of benchmarks to increase the confidence that this is indeed a very corner case.
> 
> I ran DaCapo 23 and did not hit the problematic case once. The regular case (exactly same type) is exercised by more than half of the DaCapo 23 benchmarks.
> 
> Will come back with test results in a day or two.

@robcasloz thanks for running tests.

> test/hotspot/jtreg/compiler/arraycopy/TestCloneUnknownClassAtParseTime.java line 1:
> 
>> 1: /*
> 
> Please add a package declaration (`package compiler.arraycopy;`). It would also be valuable if you could incorporate the detailed failure analysis from the PR description into this test file.

Done in new commit.

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PR Comment: https://git.openjdk.org/jdk/pull/27604#issuecomment-3455569071
PR Review Comment: https://git.openjdk.org/jdk/pull/27604#discussion_r2468815342