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From: "jm at bourguet dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/95891] New: Missing optimization
Date: Thu, 25 Jun 2020 08:38:57 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 10.1.0
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X-Bugzilla-Who: jm at bourguet dot org
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95891

            Bug ID: 95891
           Summary: Missing optimization
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jm at bourguet dot org
  Target Milestone: ---

I'm sorry, this is perhaps not the correct component but my knowledge of gcc
internals does not allow me to do more than guess.

For all version of gcc I've tried, the following code:

struct point {
    int x, y;
};

bool f(point a, point b) {
    return a.x =3D=3D b.x && a.y =3D=3D b.y;
}

bool f(unsigned long long a, unsigned long long b) {
    return a =3D=3D b;
}

is compiled to

f(point, point):
        xor     eax, eax
        cmp     edi, esi
        je      .L5
        ret
.L5:
        sar     rdi, 32
        sar     rsi, 32
        cmp     edi, esi
        sete    al
        ret
f(unsigned long long, unsigned long long):
        cmp     rdi, rsi
        sete    al
        ret

I'd expect f(point, point) to have the same assembly as f(unsigned long lon=
g,
unsigned long long).

Yours,

-- Jean-Marc Bourguet=