[Bug tree-optimization/123291] New: missed optimization for summing 0...n-1 in a loop

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123291

            Bug ID: 123291
           Summary: missed optimization for summing 0...n-1 in a loop
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: uecker at gcc dot gnu.org
  Target Milestone: ---

As seen on Matt Godbolt's blog Clang can optimize away the following loop. Not
sure where this is really needed, but I leave it here for reference.

https://xania.org/202512/24-cunning-clang

int sum_up_to(int value) {
  int result = 0;
  for (int x = 0; x < value; ++x) {
    result += x;
  }
  return result;
}

https://aoco.compiler-explorer.com/z/xh8Edo8vM