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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/107053] ones bits is not tracked and popcount
 is not tracked
Date: Tue, 27 Sep 2022 15:40:29 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107053

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note the correct testcase is:
void link_failure();
void f(int a)
{
    a |=3D 0x300;
    int b =3D  __builtin_popcount(a);
    if (b < 2)
        link_failure();
}

--- CUT ---
the range of b should be 2..31 (assuming int is 32bits).
With this change clang is able to optimize it.

For the original testcase I think it can be folded to:
void link_failure();
void f(int a)
{
    int a1 &=3D ~0x300;
    if (a1 !=3D 0)
        link_failure();
}
but that might be worse unless popcount can be removed. (If I did this
correctly).=