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From: "wilco at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/95731] Faiilure to optimize a >= 0 && b >= 0
 to (a | b) >= 0
Date: Tue, 04 Aug 2020 11:21:25 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95731

Wilco <wilco at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-08-04
                 CC|                            |wilco at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Gabriel Ravier from comment #0)
> bool f(int a, int b)
> {
>     return a >=3D 0 && b >=3D 0;
> }
>=20
> This can be optimized to `return (a | b) >=3D 0;`. LLVM does this
> transformation, but GCC does not.

For orthogonality you also want:

a < 0 && b < 0   -> (a & b) < 0
a >=3D 0 || b >=3D 0 -> (a & b) >=3D 0
a < 0 || b < 0   -> (a | b) < 0=