RFR: 8368811: [Leyden] Use AOTRuntimeConstants table for card_table::_byte_map_base [v2]

Vladimir Kozlov kvn at openjdk.org
Thu Oct 2 05:30:02 UTC 2025


> 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:

  Removed card_shift from AOT constants table. Fixed minimal VM build.

-------------

Changes:
  - all: https://git.openjdk.org/leyden/pull/102/files
  - new: https://git.openjdk.org/leyden/pull/102/files/a1721c98..e94fb605

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=102&range=01
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=102&range=00-01

  Stats: 244 lines in 16 files changed: 37 ins; 175 del; 32 mod
  Patch: https://git.openjdk.org/leyden/pull/102.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/102/head:pull/102

PR: https://git.openjdk.org/leyden/pull/102


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