RFR: 8354887: Preserve runtime blobs in AOT code cache [v2]

[Ashutosh Mehra]

On Mon, 12 May 2025 15:17:02 GMT, Andrew Dinn <adinn at openjdk.org> wrote:

>> Ashutosh Mehra has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 11 commits:
>> 
>>  - Merge branch 'master' into preserve-runtime-blobs-master
>>  - Address Vladimir's comments
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Remove irrelevant comment
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Fix win64 compile failures
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Fix AOTCodeFlags.java test
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Fix compile failure in minimal config
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Revert back changes that added AOTRuntimeConstants.
>>    Ensure CompressedOops::base and CompressedKlssPointers::base does not
>>    change in production run
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Fix merge conflicts
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Store/load AsmRemarks and DbgStrings in aot code cache
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - Add missing external address in aarch64
>>    
>>    Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/2a4f37cc...ba612dab
>
> Having discussed this with @fisk it appears that the weak reference load performed by the c2i adapters will not attempt a decode. The barrier load_at method only performs a decode when the decorators include `IN_HEAP`. `resolve_weak_handle` passes in the `IN_NATIVE` decorator which implies no decode should be performed.
> 
> So, this means we can use the adapters even if the compressed oop base differs between training run and production run.

@adinn can you please review this as well?

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PR Comment: https://git.openjdk.org/jdk/pull/25019#issuecomment-2880863631