RFR: 8324751: C2 SuperWord: Aliasing Analysis runtime check [v5]

[Manuel Hässig]

On Sun, 3 Aug 2025 06:59:07 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/mempointer.hpp line 731:
>> 
>>> 729:   }
>>> 730: 
>>> 731:   bool is_valid() const { return _int_group >= 0; }
>> 
>> Why is _int_group not a `uint` if it is always positive or 0?
>
> I don't think it matters too much here. But I do use this as the `is_valid` flag, and I do create invalid summands with the default constructor like this:
> `MemPointerRawSummand(nullptr, NoOverflowInt::make_NaN(), NoOverflowInt::make_NaN(), -1) {}`
> 
> Do you see an issue with this, or a significant inefficiency?

No, I just did not catch the -1 in the default constructor and was wondering if `is_valid()` could be dropped by just using an unsigned type. All good.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24278#discussion_r2251061866