RFR: 8330163: C2: improve CMoveNode::Value() when condition is always true or false [v2]

[Quan Anh Mai]

On Fri, 12 Apr 2024 14:34:01 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> This is another small change from something I ran into while working
>> on 8275202. `CMoveNode::Value` can be improved when the condition is
>> known to be always true or false. That doesn't affect IGVN (as the
>> `CMove` is removed in that case) but it can be useful for passes that
>> propagates types such as CCP. In the IR tests, the backbranch of the
>> loop is never taken when the root of the compilation is `test1`. With
>> the change, CCP can eliminate it. Without, it can't.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/hotspot/share/opto/movenode.cpp
>   
>   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>

I see, please go ahead, thanks a lot for your response.

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PR Comment: https://git.openjdk.org/jdk/pull/18757#issuecomment-2060837944