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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/115363] New: Missing loop vectorization due
 to loop bound load not being pulled out
Date: Wed, 05 Jun 2024 17:55:04 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 15.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115363

            Bug ID: 115363
           Summary: Missing loop vectorization due to loop bound load not
                    being pulled out
           Product: gcc
           Version: 15.0
            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
  Target Milestone: ---

Take:
```
struct out {
  unsigned *array;
};

struct m{
  void f(out *output);
  void f1(out *output);
  int size;
};

void  m::f(out *output)
{
      for (int k =3D 0; k < size; k++) {
        output->array[k] +=3D 1;
      }
}

void  m::f1(out *output)
{
  int tmp =3D size;
  for (int k =3D 0; k < size; k++) {
    output->array[k] +=3D 1;
  }
}
```

We should be able to vectorize `m::f` but currently does not since this->si=
ze
might alias array[k].
But we could version the loop to pull out the this->size out of the loop an=
d we
could vectorize the loop then.=