RFR: 8261731: shallow copy the internal buffer of a scalar-replaced java.lang.String object [v2]

[Xin Liu]

On Wed, 17 Feb 2021 17:42:48 GMT, Volker Simonis <simonis at openjdk.org> wrote:

>> Xin Liu has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 36 commits:
>> 
>>  - Merge branch 'master' into optimize_substring
>>  - fix regression for x86-32
>>    
>>    if LP64 is off, the offset of AddP must be I instead of L.
>>    x86 also doesn't emit encodeP/storeN. it use storeP instead.
>>  - add a statistical counter for OptimizeTempArray.
>>    
>>    -XX:+PrintOptoStatistics shows it
>>  - [SIM-JVM-450] support deoptimization v2
>>    
>>    because the src oop of scobj may be another scobj, deoptimization sort
>>    all objects in topological order.
>>    
>>    separate creation of dst oop and reassignment of it.
>>  - add a unit test for deoptimization
>>  - [SIM-JVM-450] support deoptimization part2
>>    
>>    if OptimizeTempArray eliminates an AllocateArrayNode, scalar replacement will
>>    create a nested SafePointScalarObjectNode for the field value:byte[] of j.l.String.
>>    we use the nested sobj and an ObjectValue an envelope. it consists of 3 fields:
>>    1. src 2. src_positio 3. length.
>>    
>>    deoptimizaton recognizes this ad-hoc ObjectValue and re-allocate an arrayOop
>>    for the String object.
>>  - enable OptimizeTempArray by default
>>  - Merge branch 'master' into optimize_substring
>>  - Revert "8260198: TypeInstPtr::dump2() emits multiple lines if Verbose is set"
>>    
>>    This reverts commit a49e34688d7d7c9d3c0d9c824d33f359613c2fc1.
>>  - Revert "add a new bucket afterea_late_inlines"
>>    
>>    afterea_late_inlines bucket is not useful. revert it and its relevant changes
>>  - ... and 26 more: https://git.openjdk.java.net/jdk/compare/849f4c0f...21693ddd
>
> src/hotspot/share/opto/macro.cpp line 1317:
> 
>> 1315: //
>> 1316: //
>> 1317: //  EncodeP:  delele because we don't need storeN
> 
> "delete" not "delele"

got it. thanks. I will update it.

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PR: https://git.openjdk.java.net/jdk/pull/2570