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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/93990] [x86] Silly code generation for
 _addcarry_u32/_addcarry_u64
Date: Sun, 29 Aug 2021 09:14:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D93990

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |NEW
           Severity|normal                      |enhancement

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
_addcarry_u64(0, a, c, &result0) can definitely be folded into
__builtin_uadd_overflowll/.ADD_OVERFLOW without any troubles.

The second _addcarry_u64 here since the result is not used can be folded in=
to
just an a few adds.

That leaves if there case where the first argument is non-zero and the resu=
lt
is used. I think going the route that Jakub mentions is best for this last
case.=