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Date: Tue, 20 Jan 2004 07:35:00 -0000
From: "dann at godzilla dot ics dot uci dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040120073544.13765.dann@godzilla.ics.uci.edu>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug optimization/13765] New:  [tree-ssa] stores to different members of the same array should not alias
X-Bugzilla-Reason: CC
X-SW-Source: 2004-01/txt/msg02348.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

int foo (int * arr)
{
  arr[0] = 1;
  arr[1] = 2;
  if (arr[0] != 1)
    abort ();
  if (arr[1] != 2)
    abort ();
}

The first if is not optimized away because, presumably, the 2 stores are not
considered not to alias.

The .optimized dump:

foo (arr)
{
<bb 0>:
  *arr = 1;
  *(arr + 4B) = 2;
  if (*arr != 1) goto <L0>; else goto <L1>;

<L0>:;
  abort ();

<L1>:;
  return;

}

-- 
           Summary:  [tree-ssa] stores to different members of the same
                    array should not alias
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dann at godzilla dot ics dot uci dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13765