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From: "felix.yang at huawei dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/94026] combine missed opportunity to simplify
 comparisons with zero
Date: Fri, 13 Mar 2020 03:09:38 +0000
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X-Bugzilla-Component: rtl-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94026

--- Comment #2 from Fei Yang <felix.yang at huawei dot com> ---
The test case is reduced from spec2017 benchmark.

int FastBoard::count_pliberties(const int i) {
    return count_neighbours(EMPTY, i);
}

// count neighbours of color c at vertex v
int FastBoard::count_neighbours(const int c, const int v) {
    assert(c =3D=3D WHITE || c =3D=3D BLACK || c =3D=3D EMPTY);
    return (m_neighbours[v] >> (NBR_SHIFT * c)) & 7;
}

bool FastBoard::self_atari(int color, int vertex) {
    assert(get_square(vertex) =3D=3D FastBoard::EMPTY);

    // 1) count new liberties, if we add 2 or more we're safe
    if (count_pliberties(vertex) >=3D 2) {
        return false;
    }

    ......=