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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/113187] New: `(X & C1) | C2` Simplifies to `A
 & (C1 | C2)` iff `(A & C2) == C2`
Date: Mon, 01 Jan 2024 09:15:25 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pinskia at gcc dot gnu.org
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113187

            Bug ID: 113187
           Summary: `(X & C1) | C2` Simplifies to `A & (C1 | C2)` iff `(A
                    & C2) =3D=3D C2`
           Product: gcc
           Version: 14.0
            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:
```
int f(int X)
{
  int C1 =3D 0x1;
  int C2 =3D 0x2;
  if ((X & C2) !=3D C2)
    __builtin_unreachable();
  return (X & C1) | C2;
}
```

This should be optimized to just `return X & 3;` as `X&0x2` is known to be
already 0x2.=