RFR: 8308899: Introduce Classfile.Context and improve Classfile.Option(s) [v14]

[Chen Liang]

On Mon, 12 Jun 2023 15:55:49 GMT, Adam Sotona <asotona at openjdk.org> wrote:

>> Classfile context object and multi-state options have been discussed at https://mail.openjdk.org/pipermail/classfile-api-dev/2023-May/000321.html
>> This patch implements the proposed changes in Classfile API and fixes all affected code across JDK sources and tests.
>> 
>> Please review.
>> 
>> Thanks,
>> Adam
>
> Adam Sotona has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 38 commits:
> 
>  - Merge branch 'master' into JDK-8308899-context
>  - Revert of DirectCodeBuilder.needsStackMap pre-calculation
>  - Revert "removal of ClassHierarchyImpl.DEFAULT_RESOLVER"
>    esolver.java
>  - Revert "proposed semi-synchronized caching, where the map is not locked during delegate call"
>    
>    This reverts commit ae2877512d978468743bcaa7e0f596729f12ee72.
>  - fixed StackMapsOption dispatching in DirectCodeBuilder
>  - proposed semi-synchronized caching, where the map is not locked during delegate call
>  - used Factory.INSTANCE for system ClassHierarchyResolver cache
>  - Revert "ClassHierarchyResolver::ofSystem is now thread-unsafe"
>    
>    This reverts commit f3099cd5b252924392995bf65edc710c27822d2b.
>  - ClassHierarchyResolver::ofSystem is now thread-unsafe
>  - removal of ClassHierarchyImpl.DEFAULT_RESOLVER
>    introduction of ClassHierarchyResolver::ofSystem factory method
>    ClassfileImpl does not pre-initialize ClassHierarchyResolverOption with default
>  - ... and 28 more: https://git.openjdk.org/jdk/compare/5d5ae352...9e0d141e

Since "not generating stack maps" really means to use an implicit stack map, I suggest renaming the `STACK_MAPS_NEVER` to `STACK_MAPS_IMPLICIT` to indicate such a confusing feature of StackMapTable. (In fact, the enum element names of StackMapsOption doesn't fit in with other options, they should be ALWAYS_STACK_MAPS, NEVER_STACK_MAPS, etc.)

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PR Comment: https://git.openjdk.org/jdk/pull/14180#issuecomment-1588916612