RFR: 8334228: C2 SuperWord: fix JDK-24 regression in VPointer::cmp_for_sort after JDK-8325155

[Vladimir Kozlov]

On Thu, 13 Jun 2024 13:05:40 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> This is a small regression from https://git.openjdk.org/jdk/pull/18822.
> 
> An overflow in the subtraction between the offsets means that the offsets are not correctly sorted. This has no correctness impact, but hit a verification assert that checked if the offsets were correctly sorted.
> 
> I now removed the subtractions, and replaced it with two comparisons.
> 
> Just out of an abundance of caution, I also converted all other subtractions into comparisons - even though I could probably make an argument that the values would be guaranteed in ranges that would not underflow the subtraction.

Good.

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Marked as reviewed by kvn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19696#pullrequestreview-2116071495