RFR: 8322694: C1: Handle Constant and IfOp in NullCheckEliminator [v3]

[Tobias Hartmann]

On Wed, 7 Feb 2024 00:44:12 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> This patch added the support for Constant and IfOn in NullCheckEliminator to eliminate more null check.
>> 
>> testing: tier 1-4 no extra test failure
>
> Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   should visit IfOp directly

Still looks good to me.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17191#pullrequestreview-1874665695