For example:

```
for (long i = 0; i < n; ++i) { foo(a + i + b); }
```
Can be reassociated to get
```
for (long i = 0; i < n; ++i) { foo(a + b + i); }
```

There is already reassociation code, but it is only applied to `CountedLoop`. `LongCountedLoop` is not a `CountedLoop` by inheritance. https://github.com/openjdk/jdk/blob/99c9ae127c0a3b8c4fc6ede87079ff7c693a2905/src/hotspot/share/opto/loopnode.cpp#L4772-L4777

This might have been regressed in JDK-8259609
The code is there already