RFR: 8351889: C2 crash: assertion failed: Base pointers must match (addp 344)

[Emanuel Peter]

On Wed, 4 Jun 2025 12:30:18 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>>> In the example above, the CastPPs are the bases.
>> 
>> Aaaah, ok now it makes a little more sense to me :)
>> 
>>> > Maybe some more full IR snippets could be helpful, maybe even IGV drawings. But that may be more work for you.
>>> 
>>> I rarely use the IGV so, yeah, that would be more work.
>> 
>> Then what about just the dump of the relevant IR nodes in text form? That is what I meant by `full IR snippets` ;)
>> 
>> Is there any (reasonable) way to push the `CastPP` through the `AddP` here? I guess that may mean duplicating some `AddP` in some cases... But it could also give an opportunity for the `CastPP` to common further up that way. What do you think? It is hard for me to see through it without looking at some examples of the IR.
>
>> Then what about just the dump of the relevant IR nodes in text form? That is what I meant by `full IR snippets` ;)
> 
> Are the omitted inputs to `AddP`s that you'd like to see? Anything else? Do you want to see them added to:
> 
>                                 /-> CastPP#110
> Store#195 -> Phi#360 -> AddP#133 -> AddP#134 -> CastPP#110
>                     -> AddP#277 -> AddP#278 -> CastPP#283
>                                 -> CastPP#283
> 
> ?
> 
>> Is there any (reasonable) way to push the `CastPP` through the `AddP` here? I guess that may mean duplicating some `AddP` in some cases... But it could also give an opportunity for the `CastPP` to common further up that way. What do you think? It is hard for me to see through it without looking at some examples of the IR.
> 
> That's not where C2 expects the `CastPP`s to be so I suppose it could be quite disruptive but hard for me to tell how much. Beyond that, wouldn't we need to know if one `CastPP` dominates the other `CastPP` before we can common them and would have the same issue we have here?

@rwestrel 
> Are the omitted inputs to AddPs that you'd like to see? Anything else?

I'm looking for the dump of all relevant nodes :)

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PR Comment: https://git.openjdk.org/jdk/pull/25386#issuecomment-2995603140