[Bug tree-optimization/118167] New: Loop invariant is not deduced in C++-iterator-style loop over pointers

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118167

            Bug ID: 118167
           Summary: Loop invariant is not deduced in C++-iterator-style
                    loop over pointers
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sjames at gcc dot gnu.org
  Target Milestone: ---

This is from https://github.com/llvm/llvm-project/issues/101372.

```
struct SpanAsPointers {
    int *begin, *end;
};

int sum_span_as_pointers(SpanAsPointers s) {
    int *begin = s.begin;
    int *end = s.end;
    [[assume (begin <= end)]];

    int sum = 0;
    int *iter = begin;
    while (iter != end) {
        assert(iter < end); /* should be optimised out */
        sum += *iter;
        iter++;
    }
    return sum;
}
```

godbolt link with more explanation: https://godbolt.org/z/fjevMcYKf