RFR: 8345485: C2 MergeLoads: merge adjacent array/native memory loads into larger load [v12]

[kuaiwei]

On Fri, 18 Apr 2025 08:37:17 GMT, kuaiwei <duke at openjdk.org> wrote:

>> First batch, need to change trains, I'll continue later :)
>
>> First batch, need to change trains, I'll continue later :)
> 
> Thanks for your review. I will check them.

> @kuaiwei Thanks for your response!
> 
> What about these two things I brought up?
> 
> > Do you have some tests where some of the nodes in the load/shift/or expression have other uses?
> 
> It would be good to have these tests, even if we think your code is correct. It is good to verify it with tests. And someone in the future might break it.
> 
> > I think your implementation should go into OrINode, and match the expression up from there. Because we want to replace the old OrI with the new LoadL.
> 
> This is really the pattern we use in `Idea`. We replace the node at the bottom of an expression with a new node (or new expression).

Test is added. If Load/Or has other usage, they can not be merged.

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PR Comment: https://git.openjdk.org/jdk/pull/24023#issuecomment-2833879090