On Wed, 3 Jun 2026 16:02:40 GMT, Vladimir Kozlov <[email protected]> wrote:
>> Roland Westrelin has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> review
>
> src/hotspot/share/opto/escape.cpp line 4537:
>
>> 4535:
>> 4536: bool ConnectionGraph::flat_access_aliases_with(Node* flat_access,
>> const TypeOopPtr *toop) {
>> 4537: Node* base = flat_access->is_StoreFlat() ?
>> flat_access->as_StoreFlat()->base() : flat_access->as_LoadFlat()->base();
>
> What type of `base` node could be here?
`base` can be anything that's a pointer (at offset 0) but not an `AddP`.
> src/hotspot/share/opto/escape.cpp line 4651:
>
>> 4649: // ConnectionGraph::optimize_flat_accesses() and has no effect
>> on the memory state
>> 4650: // - or it is a LoadFlat for some object unrelated to alias_idx
>> 4651: // In both cases, it's safe to assume this LoadFlat doesn't
>> modify the memory for alias_idx
>
> Which flat load can modify memory? I surprise that this node has Memory
> projection.
Whey they are expanded they need memory barriers which is why I think they have
a memory projection. If the `LoadFlat` is from a non escaping object, then it
doesn't need memory barriers when it's expanded AFAIU.
-------------
PR Review Comment:
https://git.openjdk.org/valhalla/pull/2489#discussion_r3357114323
PR Review Comment:
https://git.openjdk.org/valhalla/pull/2489#discussion_r3357128995
