[Bug tree-optimization/121595] New: fabs(a+0.0) -> fabs(a) for non trapping case

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121595

            Bug ID: 121595
           Summary: fabs(a+0.0) -> fabs(a) for non trapping case
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
double f(double a)
{
  return __builtin_fabs(a + 0.0);
}
```

In this case adding 0.0 does not change the value. For trapping math yes it
matters and for signaling nans it matters.

Looks like this shows up in opencv.