RFC: Draft JEP: Generational ZGC

[Stefan Karlsson]

Hi Leslie,

Could you test if this branch compiles as expected?
https://github.com/stefank/jdk/tree/zgc_generational_found_old_initialization

I asked around and it seems like array initialization uses 
copy-initialization of the elements, and that older GCCs didn't take the 
opportunity to convert the copying into move operations. Or something 
along those lines. I've restructured the code to prevent that problem.

Thanks for reporting,
StefanK

On 2022-10-17 12:03, Leslie Zhai wrote:
> Hi Stefan,
>
> gcc 8.3.0 failed to work after the commit 
> 7d0b267e87ec6120a74e5b6282c5e395786d2546: 
> https://github.com/openjdk/zgc/commit/7d0b267e87ec6120a74e5b6282c5e395786d2546 
>
>
> Building target 'images' in configuration 
> 'linux-aarch64-server-fastdebug'
> Updating support/modules_libs/java.base/server/libjvm.so due to 1 file(s)
> /home/zhaixiang/zgc/src/hotspot/share/gc/z/zPageTable.cpp: In 
> constructor 'ZPageTable::FoundOld::FoundOld()':
> /home/zhaixiang/zgc/src/hotspot/share/gc/z/zPageTable.cpp:59:15: 
> error: use of deleted function 'CHeapBitMap::CHeapBitMap(const 
> CHeapBitMap&)'
>      _current{0} {}
>                ^
> In file included from 
> /home/zhaixiang/zgc/src/hotspot/share/memory/allocation.hpp:29,
>                  from 
> /home/zhaixiang/zgc/src/hotspot/share/classfile/classLoaderData.hpp:28,
>                  from 
> /home/zhaixiang/zgc/src/hotspot/share/precompiled/precompiled.hpp:34:
> /home/zhaixiang/zgc/src/hotspot/share/utilities/bitMap.hpp:488:15: 
> note: declared here
>    NONCOPYABLE(CHeapBitMap);
>                ^~~~~~~~~~~
> /home/zhaixiang/zgc/src/hotspot/share/utilities/globalDefinitions.hpp:84:24: 
> note: in definition of macro 'NONCOPYABLE'
>  #define NONCOPYABLE(C) C(C const&) = delete; C& operator=(C const&) = 
> delete /* next token must be ; */
>                         ^
> make[3]: *** [lib/CompileJvm.gmk:149: 
> /home/zhaixiang/zgc/build/linux-aarch64-server-fastdebug/hotspot/variant-server/libjvm/objs/zPageTable.o] 
> Error 1
> make[3]: *** Waiting for unfinished jobs....
> make[2]: *** [make/Main.gmk:252: hotspot-server-libs] Error 2
>
> ERROR: Build failed for target 'images' in configuration 
> 'linux-aarch64-server-fastdebug' (exit code 2)
>
> So I just reverted the commit then continue my porting work.
>
> How to compatible with low version GNU compiler?
>
> Thanks,
>
> Leslie Zhai
>
> 在 2022/10/17 下午5:47, Stefan Karlsson 写道:
>> The development of Generational ZGC happens in this project branch:
>> https://github.com/openjdk/zgc/tree/zgc_generational
>>
>> StefanK
>>
>> On 2022-10-14 14:47, Stefan Karlsson wrote:
>>> Hi all,
>>>
>>> I have created a draft JEP for Generational ZGC. For details, see 
>>> the JBS entry:
>>>
>>> https://bugs.openjdk.org/browse/JDK-8272979
>>>
>>> Comments and feedback are welcome.
>>>
>>> Thanks,
>>> StefanK
>