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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/114999] A few missing optimizations due to `a
 - b` and `b - a` not being detected as negatives of each other
Date: Thu, 09 May 2024 00:16:33 +0000
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X-Bugzilla-Component: tree-optimization
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X-Bugzilla-Keywords: missed-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114999

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|`a - b =3D=3D b - a` -> `a =3D=3D   |A few missing opti=
mizations
                   |b`                          |due to `a - b` and `b - a`
                   |                            |not being detected as
                   |                            |negatives of each other

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Another one:
```
int f(int a, int b, int x)
{
  x =3D a - b;
  int y =3D -x;
  return (x >=3D 0 ? x : 0) + (x <=3D 0 ? y : 0);
}
```

This should be detected as `abs<a - b>` (just like if the assignment to x is
removed.=