[Bug tree-optimization/107881] New: (a <= b) == (b >= a) should be optimized to (a == b)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107881

            Bug ID: 107881
           Summary: (a <= b) == (b >= a) should be optimized to (a == b)
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
            Blocks: 107880
  Target Milestone: ---

Take:
```
bool f(int a, int b)
{
  bool t = b <= a;
  bool t1 = a <= b;
  return t == t1;
}
```

We should optimize this to just:
```
bool f1(int a, int b)
{
  return a == b;
}
```
LLVM is able to do it.
We can optimize for & and | but not ^ or ==. (note != gets changed into ^)


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107880
[Bug 107880] bool tautology missed optimisation