[PATCH] Fix PR65788

[Richard Biener]

The following fixes PR65788.  We need to use UNDEFINED whenever possible
to not get spurious invalid lattice transitions later.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2015-04-21  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/65788
        * tree-ssa-ccp.c (evaluate_stmt): Evaluate to UNDEFINED early.

Index: gcc/tree-ssa-ccp.c
===================================================================
*** gcc/tree-ssa-ccp.c  (revision 222227)
--- gcc/tree-ssa-ccp.c  (working copy)
*************** evaluate_stmt (gimple stmt)
*** 1756,1761 ****
--- 1756,1769 ----
          val.mask = 0;
        }
      }
+   /* If the statement result is likely UNDEFINED, make it so.  */
+   else if (likelyvalue == UNDEFINED)
+     {
+       val.lattice_val = UNDEFINED;
+       val.value = NULL_TREE;
+       val.mask = 0;
+       return val;
+     }
  
    /* Resort to simplification for bitwise tracking.  */
    if (flag_tree_bit_ccp
*************** evaluate_stmt (gimple stmt)
*** 1890,1896 ****
  
    if (flag_tree_bit_ccp
        && ((is_constant && TREE_CODE (val.value) == INTEGER_CST)
!         || (!is_constant && likelyvalue != UNDEFINED))
        && gimple_get_lhs (stmt)
        && TREE_CODE (gimple_get_lhs (stmt)) == SSA_NAME)
      {
--- 1898,1904 ----
  
    if (flag_tree_bit_ccp
        && ((is_constant && TREE_CODE (val.value) == INTEGER_CST)
!         || !is_constant)
        && gimple_get_lhs (stmt)
        && TREE_CODE (gimple_get_lhs (stmt)) == SSA_NAME)
      {
*************** evaluate_stmt (gimple stmt)
*** 1918,1939 ****
        }
      }
  
    if (!is_constant)
      {
!       /* The statement produced a nonconstant value.  If the statement
!        had UNDEFINED operands, then the result of the statement
!        should be UNDEFINED.  Otherwise, the statement is VARYING.  */
!       if (likelyvalue == UNDEFINED)
!       {
!         val.lattice_val = likelyvalue;
!         val.mask = 0;
!       }
!       else
!       {
!         val.lattice_val = VARYING;
!         val.mask = -1;
!       }
! 
        val.value = NULL_TREE;
      }
  
--- 1926,1936 ----
        }
      }
  
+   /* The statement produced a nonconstant value.  */
    if (!is_constant)
      {
!       val.lattice_val = VARYING;
!       val.mask = -1;
        val.value = NULL_TREE;
      }