RFR: 8336297: C2: Fix -Wzero-as-null-pointer-constant warnings in derived Node ctors

[Kim Barrett]

On Fri, 12 Jul 2024 21:22:50 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Please review this change that removes some -Wzero-as-null-pointer-constant
>> warnings (when enabled) in C2 code. The constructors for some classes derived
>> from Node pass 0 as the first argument to the base class constructor. Since
>> that parameter is a Node*, this triggers a warning.  Changing to pass nullptr
>> removes the warning.
>> 
>> Testing: mach5 tier1
>
> Good.

Thanks for reviews @vnkozlov and @TheShermanTanker

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PR Comment: https://git.openjdk.org/jdk/pull/20162#issuecomment-2228808506