RFR: 8287794: Reverse*VNode::Identity problem [v2]

[Aleksey Shipilev]

On Mon, 25 Jul 2022 13:33:28 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8287794: Review comments resolved.
>
> src/hotspot/share/opto/vectornode.cpp line 1864:
> 
>> 1862:     // OperationV (OperationV X) =>  X
>> 1863:     } else if (!n->is_predicated_vector() && !in1->is_predicated_vector())  {
>> 1864:       return in1->in(1);
> 
> But this will still trigger the SonarCloud warning originally reported by @shipilev because both if and else branch contain the same code, right? Shouldn't the conditions be merged?

I don't think it would trigger a warning. The original warning, as I understand it, was to say that the *unpredicated* `else` branch is the same. So we were guaranteed to take either of branches, and thus the same code, irrelevant of the predicate. It is not the same here: we now have a third path, going out without entering either branch :)

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PR: https://git.openjdk.org/jdk/pull/9623