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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/88518] Function call defeats -Wuninitialized
Date: Tue, 06 Apr 2021 19:59:29 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D88518

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
   Last reconfirmed|                            |2021-4-6
         Resolution|---                         |DUPLICATE
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed as a duplicate of pr60488 (which itself is likely a duplicate of =
some
older bug).  A variable whose address escapes is not considered by the warn=
ing.
 It sees the following IL:

;; Function f (f, funcdef_no=3D0, decl_uid=3D1947, cgraph_uid=3D1, symbol_o=
rder=3D0)

void f ()
{
  long unsigned int i;
  long unsigned int i.0_1;
  long unsigned int _2;

  <bb 2> [local count: 1073741824]:
  # .MEM_4 =3D VDEF <.MEM_3(D)>
  h ();
  # VUSE <.MEM_4>
  i.0_1 =3D i;                    <<< i loaded from memory and not consider=
ed
  _2 =3D i.0_1 + 1;               <<< missing -Wuninitialized
  # .MEM_5 =3D VDEF <.MEM_4>
  i =3D _2;
  # .MEM_6 =3D VDEF <.MEM_5>
  g (&i);
  # .MEM_7 =3D VDEF <.MEM_6>
  i =3D{v} {CLOBBER};
  # VUSE <.MEM_7>
  return;

}

The pointless load persists until the assembly:

f:
.LFB0:
        .cfi_startproc
        subq    $24, %rsp
        .cfi_def_cfa_offset 32
        call    h
        leaq    8(%rsp), %rdi   <<< i loaded from memory
        addq    $1, 8(%rsp)     <<< i++
        call    g
        addq    $24, %rsp
        .cfi_def_cfa_offset 8
        ret
        .cfi_endproc

*** This bug has been marked as a duplicate of bug 60488 ***=