RFR: 8307058: Implementation of Generational ZGC [v8]

[Quan Anh Mai]

On Sat, 6 May 2023 04:08:42 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Stefan Karlsson has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 917 commits:
>> 
>>  - ZGC: Generational
>>    
>>    Co-authored-by: Stefan Karlsson <stefank at openjdk.org>
>>    Co-authored-by: Per Liden <pliden at openjdk.org>
>>    Co-authored-by: Albert Mingkun Yang <ayang at openjdk.org>
>>    Co-authored-by: Erik Österlund <eosterlund at openjdk.org>
>>    Co-authored-by: Axel Boldt-Christmas <aboldtch at openjdk.org>
>>    Co-authored-by: Stefan Johansson <kstefanj at openjdk.org>
>>  - UPSTREAM: Introduce check_oop infrastructure to check oops in the oop class
>>  - UPSTREAM: RISCV tmp reg cleanup resolve_jobject
>>  - CLEANUP: barrierSetNMethod_aarch64.cpp
>>  - UPSTREAM: Add relaxed add&fetch for aarch64 atomics
>>  - UPSTREAM: assembler_ppc CMPLI
>>    
>>    Co-authored-by: TheRealMDoerr <martin.doerr at sap.com>
>>  - UPSTREAM: assembler_ppc ANDI
>>    
>>    Co-authored-by: TheRealMDoerr <martin.doerr at sap.com>
>>  - UPSTREAM: Add VMErrorCallback infrastructure
>>  - Merge branch 'zgc_generational' into zgc_generational_rebase_target
>>  - Whitespace nit
>>  - ... and 907 more: https://git.openjdk.org/jdk/compare/705ad7d8...349cf9ae
>
> src/hotspot/cpu/x86/gc/z/zBarrierSetAssembler_x86.cpp line 310:
> 
>> 308:     // A not relocatable object could have spurious raw null pointers in its fields after
>> 309:     // getting promoted to the old generation.
>> 310:     __ cmpw(ref_addr, barrier_Relocation::unpatched);
> 
> `cmpw` with immediates stalls the predecoder, it may be better to `movzwl` to a spare register and `cmpl` there.

I think we use the flag `UseStoreImmI16` for these kinds of situations.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13771#discussion_r1186662246