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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/109495] Stack is used (unexpectedly) for copying
 on-heap objects (no problem in clang)
Date: Thu, 13 Apr 2023 11:49:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109495

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
      Known to fail|                            |13.0, 7.5.0
            Version|unknown                     |13.0
                 CC|                            |hubicka at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
             Target|                            |x86_64-*-*
   Last reconfirmed|                            |2023-04-13
             Status|UNCONFIRMED                 |NEW
          Component|c++                         |middle-end
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Selected stringop expansion strategy: libcall
Selected stringop expansion strategy: libcall
Selected stringop expansion strategy: libcall
Selected stringop expansion strategy: libcall

;; MEM[(struct Child *)_6].D.35468 =3D MEM[(const struct Child &)_3].D.3546=
8;

and for some reason we expand this to a memcpy to a stack temporary
and then a memcpy from that stack temporary!?=