tree-ssa-pre.c (create_component_ref_by_pieces_1): Drop a zero minimum index…

tree-ssa-pre.c (create_component_ref_by_pieces_1): Drop a zero minimum index only if it is redundant.

	* tree-ssa-pre.c (create_component_ref_by_pieces_1) <ARRAY_REF>: Drop
	a zero minimum index only if it is redundant.

From-SVN: r171800

gcc/ChangeLog

+2011-03-31  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* tree-ssa-pre.c (create_component_ref_by_pieces_1) <ARRAY_REF>: Drop
+	a zero minimum index only if it is redundant.
+
 2011-03-31  Vladimir Makarov  <vmakarov@redhat.com>
 
 	PR rtl-optimization/48381

gcc/testsuite/ChangeLog

+2011-03-31  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/opt16.adb: New test.
+
 2011-03-31  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/defaulted24.C: New.

gcc/testsuite/gnat.dg/opt16.adb

+-- { dg-do compile }
+-- { dg-options "-O2 -gnatws" }
+
+procedure Opt16 is
+
+   generic
+      type T (<>) is private;
+      V, V1 : T;
+      with function F1 (X : T) return T;
+   package GP is
+      R : Boolean := F1 (V) = V1;
+   end GP;
+
+   type AB is array (Boolean range <>) of Boolean;
+
+begin
+   for I1 in Boolean loop
+      for I2 in Boolean loop
+         declare
+            B1 : Boolean := I1;
+            B2 : Boolean := I2;
+            AB1 : AB (Boolean) := (I1, I2);
+            T : AB (B1 .. B2) := (B1 .. B2 => True);
+            F : AB (B1 .. B2) := (B1 .. B2 => False);
+
+            package P is new GP (AB, AB1, NOT AB1, "NOT");
+
+         begin
+            null;
+         end;
+      end loop;
+   end loop;
+end;

gcc/tree-ssa-pre.c

@@ -2874,8 +2874,11 @@ create_component_ref_by_pieces_1 (basic_block block, vn_reference_t ref,
 	  return NULL_TREE;
 	if (genop2)
 	  {
-	    /* Drop zero minimum index.  */
-	    if (tree_int_cst_equal (genop2, integer_zero_node))
+	    tree domain_type = TYPE_DOMAIN (TREE_TYPE (genop0));
+	    /* Drop zero minimum index if redundant.  */
+	    if (integer_zerop (genop2)
+		&& (!domain_type
+		    || integer_zerop (TYPE_MIN_VALUE (domain_type))))
 	      genop2 = NULL_TREE;
 	    else
 	      {