[Bug target/36090] [4.3/4.4 Regression] ppc64 cacoshl miscompilation

[dje at gcc dot gnu dot org]

------- Comment #14 from dje at gcc dot gnu dot org  2008-05-02 15:10 -------
The problematic transformation in simplify_plus_minus() is:

  /* We suppressed creation of trivial CONST expressions in the
     combination loop to avoid recursion.  Create one manually now.
     The combination loop should have ensured that there is exactly
     one CONST_INT, and the sort will have ensured that it is last
     in the array and that any other constant will be next-to-last.  */

  if (n_ops > 1
      && GET_CODE (ops[n_ops - 1].op) == CONST_INT
      && CONSTANT_P (ops[n_ops - 2].op))
    {
      rtx value = ops[n_ops - 1].op;
      if (ops[n_ops - 1].neg ^ ops[n_ops - 2].neg)
        value = neg_const_int (mode, value);
      ops[n_ops - 2].op = plus_constant (ops[n_ops - 2].op, INTVAL (value));
      n_ops--;
    }

If that transformation is avoided, the preferred RTL is generated.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36090