tree-ssa-ccp.c (fold_const_aggregate_ref): Fix handling of array_ref_low_bound…

tree-ssa-ccp.c (fold_const_aggregate_ref): Fix handling of array_ref_low_bound in string access folding.


	* tree-ssa-ccp.c (fold_const_aggregate_ref): Fix handling of array_ref_low_bound
	in string access folding.

From-SVN: r163956

gcc/ChangeLog

+2010-09-07  Jan Hubicka  <jh@suse.cz>
+
+	* tree-ssa-ccp.c (fold_const_aggregate_ref): Fix handling of array_ref_low_bound
+	in string access folding.
+
 2010-09-07  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/45206
@@ -6,7 +11,7 @@
 
 2010-09-07  Jan Hubicka  <jh@suse.cz>
 
-	* gimple.c (maybe_fold_reference): Verify that operand is
+	* gimple-fold.c (maybe_fold_reference): Verify that operand is
 	gimple_min_invariant.
 
 2010-09-07  Richard Guenther  <rguenther@suse.de>

gcc/tree-ssa-ccp.c

@@ -1398,17 +1398,30 @@ fold_const_aggregate_ref (tree t)
 	}
 
       /* Fold read from constant string.  */
-      if (TREE_CODE (ctor) == STRING_CST)
+      if (TREE_CODE (ctor) == STRING_CST
+	  && TREE_CODE (idx) == INTEGER_CST)
 	{
+	  tree low_bound = array_ref_low_bound (t);
+	  double_int low_bound_cst;
+	  double_int index_cst;
+	  double_int length_cst;
+	  bool signed_p = TYPE_UNSIGNED (TREE_TYPE (idx));
+
+	  if (TREE_CODE (low_bound) != INTEGER_CST)
+	    return NULL_TREE;
+	  low_bound_cst = tree_to_double_int (low_bound);
+	  index_cst = tree_to_double_int (idx);
+	  length_cst = uhwi_to_double_int (TREE_STRING_LENGTH (ctor));
+	  index_cst = double_int_sub (index_cst, low_bound_cst);
 	  if ((TYPE_MODE (TREE_TYPE (t))
 	       == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
 	      && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
 	          == MODE_INT)
 	      && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
-	      && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
+	      && double_int_cmp (index_cst, length_cst, signed_p) < 0)
 	    return build_int_cst_type (TREE_TYPE (t),
 				       (TREE_STRING_POINTER (ctor)
-					[TREE_INT_CST_LOW (idx)]));
+					[double_int_to_uhwi (index_cst)]));
 	  return NULL_TREE;
 	}