RFR: 8333393: PhaseCFG::insert_anti_dependences can fail to raise LCAs and to add necessary anti-dependence edges [v2]

[Daniel Lundén]

On Mon, 23 Dec 2024 11:04:54 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Updates after comments
>
> src/hotspot/share/opto/gcm.cpp line 790:
> 
>> 788:         Node* n = b->get_node(i);
>> 789:         if (n->is_memory_phi() && C->can_alias(n->adr_type(), load_alias_idx)) {
>> 790:           worklist_def_use_mem_states.push(nullptr, n);
> 
> We may push `<nullptr, initial_mem>` again here, is that an issue? If not, maybe add a comment explaining why.

It is not a problem because the `push` method includes duplication handling for Phis. However, I think it is better for both clarity and efficiency to just check `n != initial_mem` here explicitly (now added).

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PR Review Comment: https://git.openjdk.org/jdk/pull/22852#discussion_r1905869926