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

[Emanuel Peter]

On Thu, 9 Jan 2025 12:43:31 GMT, Emanuel Peter <epeter 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 793:
> 
>> 791:       if (b == initial_mem_block && !initial_mem->is_Phi()) {
>> 792:         // If we are in the initial memory block, and initial_mem is not itself
>> 793:         // a Phi, no Phis in the block can be initial memory states.
> 
> I'm confused when I read this. As said above, we need a clear definition of `initial`.

Can you explain why `no Phis in the block can be initial memory states.`? I'm probably missing something obvious.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22852#discussion_r1908731081