RFR: 8368811: [Leyden] Use AOTRuntimeConstants table for card_table::_byte_map_base [v3]

[Andrew Dinn]

On Thu, 2 Oct 2025 16:07:23 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Currently we use `Relocation` info to patch `card_table::_byte_map_base` referenced in compiled code. This is not completely correct since this is not address. We currently have special check in `AOTCodeCache::init2()` to skip AOT code generation and usage if `byte_map_base` is not relocatable [aotCodeCache.cpp#L341](https://github.com/openjdk/leyden/blob/premain/src/hotspot/share/code/aotCodeCache.cpp#L341)
>> 
>> To avoid this we should use existing `AOTRuntimeConstants` table to load `byte_map_base` from it.
>> 
>> I also added few missing loads `card_shift` from `AOTRuntimeConstants` table. Actually I am not sure why we have it in `AOTRuntimeConstants` table.  From what I see, it is based on `GCCardSizeInBytes` flag [cardTable.cpp#L46](https://github.com/openjdk/leyden/blob/premain/src/hotspot/share/gc/shared/cardTable.cpp#L46) and never modified. The flags is not adjusted ergonomically.  So we can simple record the flag in AOT code configuration and verify it when loading AOT code. 
>> 
>> @adinn  what do you think about `card_shift` in `AOTRuntimeConstants` table? You added it there.
>> 
>> Changes were testing tier1-5.
>
> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Addressed comments

Still looks good.

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PR Comment: https://git.openjdk.org/leyden/pull/102#issuecomment-3363244920