[multiple changes]

[gcc.git] / gcc / ada / trans.c

diff --git a/gcc/ada/trans.c b/gcc/ada/trans.c
index c9286121ee3c6c9846deb66c5ba6c47444e482e6..b32d4a63f874b85eb32f8ec7312ca264d31c6246 100644 (file)
--- a/gcc/ada/trans.c
+++ b/gcc/ada/trans.c
@@ -273,7 +273,7 @@ gnat_to_gnu (Node_Id gnat_node)
 {
   tree gnu_root;
   bool made_sequence = false;
-    
+
   /* We support the use of this on statements now as a transition
      to full function-at-a-time processing.  So we need to see if anything
      we do generates RTL and returns error_mark_node.  */
@@ -517,14 +517,32 @@ tree_transform (Node_Id gnat_node)
                  && DECL_BY_COMPONENT_PTR_P (gnu_result))))
        {
          int ro = DECL_POINTS_TO_READONLY_P (gnu_result);
+         tree initial;
 
          if (TREE_CODE (gnu_result) == PARM_DECL
              && DECL_BY_COMPONENT_PTR_P (gnu_result))
            gnu_result = convert (build_pointer_type (gnu_result_type),
                                  gnu_result);
 
-         gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE,
-                                      fold (gnu_result));
+         /* If the object is constant, we try to do the dereference directly
+            through the DECL_INITIAL.  This is actually required in order to
+            get correct aliasing information for renamed objects that are
+            components of non-aliased aggregates, because the type of
+            the renamed object and that of the aggregate don't alias.  */
+         if (TREE_READONLY (gnu_result)
+             && DECL_INITIAL (gnu_result)
+             /* Strip possible conversion to reference type.  */
+             && (initial = TREE_CODE (DECL_INITIAL (gnu_result)) == NOP_EXPR
+                           ? TREE_OPERAND (DECL_INITIAL (gnu_result), 0)
+                           : DECL_INITIAL (gnu_result), 1)
+             && TREE_CODE (initial) == ADDR_EXPR
+             && (TREE_CODE (TREE_OPERAND (initial, 0)) == ARRAY_REF
+                 || TREE_CODE (TREE_OPERAND (initial, 0)) == COMPONENT_REF))
+           gnu_result = TREE_OPERAND (initial, 0);
+         else
+           gnu_result = build_unary_op (INDIRECT_REF, NULL_TREE,
+                                        fold (gnu_result));
+
          TREE_READONLY (gnu_result) = TREE_STATIC (gnu_result) = ro;
        }
 
@@ -4373,7 +4391,7 @@ end_block_stmt ()
 
   return gnu_retval;
 }
-   
+
 /* Build a BLOCK_STMT from GNAT_LIST, a possibly-empty list of statements.  */
 
 static tree
@@ -4394,7 +4412,7 @@ build_block_stmt (List_Id gnat_list)
 
   gnu_result = end_block_stmt ();
   return TREE_CODE (gnu_result) == NULL_STMT ? NULL_TREE : gnu_result;
-} 
+}
 
 /* Build an EXPR_STMT to evaluate INSNS.  Use Sloc from GNAT_NODE.   */
 
@@ -4523,7 +4541,7 @@ gnat_expand_stmt (tree gnu_stmt)
          }
       break;
 
-    default: 
+    default:
      abort ();
     }
 }