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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/94804] Failure to elide useless movs in
 128-bit addition
Date: Tue, 28 Apr 2020 12:38:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94804

--- Comment #3 from Gabriel Ravier <gabravier at gmail dot com> ---
So, things like=20

uint64_t swap64(uint64_t x)
{
    uint64_t a =3D __builtin_bswap32(x);
    x >>=3D 32;
    a <<=3D 32;
    return __builtin_bswap32(x) | a;
}

Having similar problems with useless movs is from the same non well-optimiz=
ed
register allocation on function boundaries ?=