RFR: JDK-8298118: split-if optimization causes empty loop to temporarily have more than one phi [v3]

[Damon Fenacci]

On Tue, 24 Jan 2023 18:38:57 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Damon Fenacci has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   JDK-8298118: add regression test package and narrow compilation options
>
> src/hotspot/share/opto/loopTransform.cpp line 3625:
> 
>> 3623:   for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
>> 3624:     Node* n = cl->fast_out(i);
>> 3625:     if ((n->Opcode() == Op_Phi) && (n->outcnt() > 0)) {
> 
> May be add comment to explain additional check.

@vnkozlov thanks for the suggestion: I've updated the existing comment instead (I hope it is clear enough).

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PR: https://git.openjdk.org/jdk/pull/12148