[Bug middle-end/106819] New: [13 Regression] NaN != NaN comparisons return false at -O2 since r13-2338

[ibuclaw at gdcproject dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106819

            Bug ID: 106819
           Summary: [13 Regression] NaN != NaN comparisons return false at
                    -O2 since r13-2338
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ibuclaw at gdcproject dot org
  Target Milestone: ---

Isolated, and translated to C from the D testsuite, likely can be reduced
further, as I don't think opCmpProper() affects the outcome.

---
static int isNaN(double x)
{
    return x != x;
}

static double opCmpProper(int lhs, double rhs)
{
  return lhs < rhs ? -1.0
       : lhs > rhs ? 1.0
       : lhs == rhs ? 0.0
       : __builtin_nan("");
}

int main()
{
    if (!isNaN(opCmpProper(41, __builtin_nan(""))))
      __builtin_abort();
    return 0;
}