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Date: Sun, 28 Mar 2004 01:54:00 -0000
From: "kazu at cs dot umass dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040328015408.14758.kazu@cs.umass.edu>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug optimization/14758] New: [tree-ssa] another missed forward propagation opportunity
X-Bugzilla-Reason: CC
X-SW-Source: 2004-03/txt/msg03216.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

void bar (void);

void
foo (int a)
{
  a = !a;
  a = !a;
  a = !a;
  a = !a;
  a = !a;

  if (a)
    bar ();
}

Here is the last tree in SSA form:

foo (a)
{
<bb 0>:
  a_2 = a_1 == 0;
  a_3 = a_2 == 0;
  if (a_3 == 0) goto <L0>; else goto <L1>;

<L0>:;
  bar () [tail call];

<L1>:;
  return;

}

Note that a_2 and a_3 still remain.

-- 
           Summary: [tree-ssa] another missed forward propagation
                    opportunity
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Keywords: pessimizes-code
          Severity: enhancement
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at cs dot umass dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14758