repinfo.adb (List_Component_Layout): Remove superfluous space for zero-sized field.

	* repinfo.adb (List_Component_Layout): Remove superfluous space for
	zero-sized field.
	* gcc-interface/ada-tree.h (TYPE_IS_EXTRA_SUBTYPE_P): New macro.
	* gcc-interface/gigi.h (create_extra_subtype): Declare.
	* gcc-interface/decl.c (TYPE_ARRAY_SIZE_LIMIT): Likewise.
	(update_n_elem): New function.
	(gnat_to_gnu_entity): Use create_extra_subtype to create extra subtypes
	instead of doing it manually.
	<E_Array_Type>: Use update_n_elem to compute the maximum size.  Use the
 	index type instead of base type for the bounds. Set TYPE_ARRAY_MAX_SIZE
	of the array to the maximum size.
	<E_Array_Subtype>: Create an extra subtype using the index type of the
	base array type for self-referential bounds.  Use update_n_elem to
	compute the maximum size.  Set TYPE_ARRAY_MAX_SIZE of the array to the
	maximum size.
	(gnat_to_gnu_field): Clear DECL_NONADDRESSABLE_P on discriminants.
	* gcc-interface/misc.c (gnat_get_alias_set): Return the alias set of
	the base type for an extra subtype.
	(gnat_type_max_size): Remove obsolete code.
	* gcc-interface/trans.c (Attribute_to_gnu): Minor tweak.
	(can_be_lower_p): Deal with pathological types.
	* gcc-interface/utils.c (create_extra_subtype): New function.
	(create_field_decl): Minor tweak.
	(max_size) <tcc_reference>: Compute a better value by using the extra
 	subtypes on the self-referential bounds.
	<tcc_binary>: Rewrite.  Deal with "negative value" in unsigned types.
	<tcc_expression>: Likewise.
	* gcc-interface/utils2.c (compare_arrays): Retrieve the original bounds
	of the arrays upfront.  Swap only if the second length is not constant.
	Use comparisons on the original bounds consistently for the null tests.
	(build_binary_op): Use TYPE_IS_EXTRA_SUBTYPE_P macro.
	(build_allocator): Minor tweak.

From-SVN: r268318

1 files changed, 20 insertions, 11 deletions

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index 3e326b4..3b0093e 100644
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -2374,15 +2374,12 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute)
       else
 	gnu_result = rm_size (gnu_type);
 
-      /* Deal with a self-referential size by returning the maximum size for
-	 a type and by qualifying the size with the object otherwise.  */
-      if (CONTAINS_PLACEHOLDER_P (gnu_result))
-	{
-	  if (TREE_CODE (gnu_prefix) == TYPE_DECL)
-	    gnu_result = max_size (gnu_result, true);
-	  else
-	    gnu_result = substitute_placeholder_in_expr (gnu_result, gnu_expr);
-	}
+      /* Deal with a self-referential size by qualifying the size with the
+	 object or returning the maximum size for a type.  */
+      if (TREE_CODE (gnu_prefix) != TYPE_DECL)
+	gnu_result = SUBSTITUTE_PLACEHOLDER_IN_EXPR (gnu_result, gnu_expr);
+      else if (CONTAINS_PLACEHOLDER_P (gnu_result))
+	gnu_result = max_size (gnu_result, true);
 
       /* If the type contains a template, subtract the padded size of the
 	 template, except for 'Max_Size_In_Storage_Elements because we need
@@ -3227,13 +3224,25 @@ static bool
 can_be_lower_p (tree val1, tree val2)
 {
   if (TREE_CODE (val1) == NOP_EXPR)
-    val1 = TYPE_MIN_VALUE (TREE_TYPE (TREE_OPERAND (val1, 0)));
+    {
+      tree type = TREE_TYPE (TREE_OPERAND (val1, 0));
+      if (can_be_lower_p (TYPE_MAX_VALUE (type), TYPE_MIN_VALUE (type)))
+	return true;
+
+      val1 = TYPE_MIN_VALUE (type);
+    }
 
   if (TREE_CODE (val1) != INTEGER_CST)
     return true;
 
   if (TREE_CODE (val2) == NOP_EXPR)
-    val2 = TYPE_MAX_VALUE (TREE_TYPE (TREE_OPERAND (val2, 0)));
+    {
+      tree type = TREE_TYPE (TREE_OPERAND (val2, 0));
+      if (can_be_lower_p (TYPE_MAX_VALUE (type), TYPE_MIN_VALUE (type)))
+	return true;
+
+      val2 = TYPE_MAX_VALUE (type);
+    }
 
   if (TREE_CODE (val2) != INTEGER_CST)
     return true;