Integrated: 8377339: Implement AOTCacheAccess::get_archived_object using heap roots

[Ioi Lam]

On Fri, 6 Feb 2026 05:50:15 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> The API `oop AOTCacheAccess::get_archived_object(int)` is used by the AOT compiler to access heap objects in the AOT cache.
> 
>  Because the objects can move in the production run, there's currently a complicated way to keep them alive using OopHandles.
> 
> https://github.com/openjdk/leyden/blob/6ce1832147ef3f01602b8fac02160038422a77bf/src/hotspot/share/cds/heapShared.cpp#L545-L610
> 
> However, we already have a mechanism for this: `oop HeapShared::get_root(int index, ...)`
> 
> So we just need to make sure that all oops needed by the AOT compiler are all stored as heap roots.
> 
> This PR is intended to provide an acceptable solution in the short run to be used by the initial AOT compiler integration into the mainline.
> 
> The AOT compiler only needs the following objects
> 
> - a few common exception objects
> - class loaders
> - class mirrors
> - interned strings
> - method handles
> 
> Most of these objects are in the roots already. We just need to add interned strings and method handles into the heap roots.
> 
> (In the future, we should move the AOT compilation before we dump the heap. This way we know exactly what oops should be stored into the heap roots.)
> 
> Notes to reviewers
> - `HeapShared::archived_object_cache()` can now survive GCs that might happen during AOT compilation. I added a new function `HeapShared::archived_object_cache_hash()` with comments about how it uses `oop::identity_hash()`.
> - This code is added to make sure interned strings and method handles are roots
> 
>   if (AOTCodeCache::is_dumping_code() &&
>                (java_lang_invoke_MethodHandle::is_instance(obj) || is_interned_string(obj))) {
>       // Needed by AOT compiler.
>       append_root(obj);
>     }
> 
> - Also some clean up that's not necessary but nice to have:
>   - I removed the `DumpedInternedStrings` and replaced it with much simpler code.

This pull request has now been integrated.

Changeset: 1f016c2b
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/leyden/commit/1f016c2b5b97f9f0fddb631747d529124e9667b2
Stats:     349 lines in 13 files changed: 83 ins; 202 del; 64 mod

8377339: Implement AOTCacheAccess::get_archived_object using heap roots

Reviewed-by: eosterlund, kvn

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PR: https://git.openjdk.org/leyden/pull/108