On Thu, 16 Apr 2026 11:17:48 GMT, Christian Hagedorn <[email protected]> wrote:
>> This patch fixes various issues found with abstract value classes where the >> assumption was that we have a concrete value class but we actually could >> have an abstract value class as well. >> >> The main issue found is that a concrete value class is represented with an >> `InlineKlass` while an abstract value class is represented with an >> `InstanceKlass`. Therefore, we cannot cast the latter to `InlineKlass`. >> While working on this, I checked all `is_inlinetype()` uses and found more >> issues. I also found issues around the `Arrays.copyOf/copyOfRange` intrinsic >> but left it as follow-up work and filed >> [JDK-8382226](https://bugs.openjdk.org/browse/JDK-8382226) for it. >> >> Here is a list of fixes included in this patch, together with corresponding >> tests: >> 1. `GraphKit::get_layout_helper()`: Wrong old assumption that nullable >> implies not-flat. >> 2. Checking whether we have a load/store from/to a field of an empty value >> class: >> a. C1: `GraphBuilder::access_field()`, for static and instance field. >> b. C2: `Parse::do_get_xxx()`, for loading >> c. C2: `Parse::do_set_xxx()`, for storing >> 3. `arraycopy` instrinsic: Not bailing out when src or dest is a flat >> abstract value class array - in this case we don't know the layout. We >> currently hit an assert due to an invalid cast, assuming concrete value >> classes when an array is flat. >> >> Additional changes: >> - Added some more asserts >> - Some small code cleanups >> >> Thanks, >> Christian >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Christian Hagedorn has updated the pull request incrementally with one > additional commit since the last revision: > > improve assert message src/hotspot/share/opto/macroArrayCopy.cpp line 1504: > 1502: bool go_to_slow_path = src_elem != dest_elem || top_src->is_flat() != > top_dest->is_flat() || dest_elem == T_VOID; > 1503: if ((top_src->is_flat() && !top_src->elem()->is_inlinetypeptr()) || > 1504: (top_dest->is_flat() && !top_dest->elem()->is_inlinetypeptr())) { Doesn't an `is_flat` array imply concrete elements here? I didn't think we could create a flat array with abstract elements. For example, ObjArrayKlass::array_layout_selection checks element->is_abstract(). FlatArrayKlass asserts element_klass->is_inline_klass(). And FlatArrayKlass::element_klass() returns InlineKlass*. ------------- PR Review Comment: https://git.openjdk.org/valhalla/pull/2325#discussion_r3098058778
