RFR: 8330274: C2 SuperWord: VPointer invar: same sum with different addition order should be equal

[Emanuel Peter]

On Tue, 23 Apr 2024 15:45:09 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Fair enough, I agree that, even if there was a solution for this specific case, we would probably encounter other cases where GVN would not be powerful enough to detect the equivalence. I still wonder though what could be causing the `CastLL(invar + iv)` vs. `invar + iv` divergence in your example and whether anything could be done to get rid of it. Maybe worth filing a RFE for further investigation.
>
>> @robcasloz are you intending to review, or was that just a drive-by comment/question?
> 
> I'm happy to review this, just give me a few days.

@robcasloz I decided to drop this PR. Rather than making the current `VPointer` more complicated, I want to refactor it, and then allow for extensions like this to be much more integrated into the pattern matching.

See:
[JDK-8330991](https://bugs.openjdk.org/browse/JDK-8330991) C2 SuperWord: refactor VPointer

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18795#issuecomment-2078751516