[Bug tree-optimization/20703] [tcb] FRE does not remove a fully redundant load.

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2005-04-01 16:47 
-------
Before FRE.  (That is, the result of copyprop)

foo (array)
{
  int D.1134;
  int D.1133;
  int * D.1132;

<bb 0>:
  D.1132_3 = array_2 + 4B;
  #   VUSE <TMT.0_9>;
  D.1133_4 = *D.1132_3;
  if (D.1133_4 != 0) goto <L0>; else goto <L1>;

<L0>:;
  D.1132_7 = array_2 + 4B;
  #   VUSE <TMT.0_9>;
  D.1134_8 = *D.1132_7;
  goto <bb 3> (<L2>);

<L1>:;
  D.1134_6 = 0;

  # D.1134_1 = PHI <D.1134_8(1), 0(2)>;
<L2>:;
  return D.1134_1;

}

After FRE.

foo (array)
{
  int D.1134;
  int D.1133;
  int * D.1132;

<bb 0>:
  D.1132_3 = array_2 + 4B;
  #   VUSE <TMT.0_9>;
  D.1133_4 = *D.1132_3;
  if (D.1133_4 != 0) goto <L0>; else goto <L1>;

<L0>:;
  D.1132_7 = D.1132_3;
  #   VUSE <TMT.0_9>;
  D.1134_8 = *D.1132_7;
  goto <bb 3> (<L2>);

<L1>:;
  D.1134_6 = 0;

  # D.1134_1 = PHI <D.1134_8(1), 0(2)>;
<L2>:;
  return D.1134_1;

}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20703