This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[Ada] Fix fallout of bitfields ABI change on Windows

The MS bitfields ABI and its stringent rules totally break packing in Ada, so 
we cannot use the C layout in this case.  The i386.c hunk fixes an oversight 
which would result in gazillions of warnings for QUAL_UNION_TYPE.

Tested on i586-suse-linux and i686-pc-mingw32, applied on the mainline and the 
4.7 branch (as obvious for the i386.c hunk).

2012-04-30  Eric Botcazou  <>

	* config/i386/i386.c (ix86_handle_struct_attribute): Use the proper
	predicate to discriminate types.

2012-04-30  Eric Botcazou  <>

	* gcc-interface/utils.c (finish_record_type): Force the traditional GCC
	layout for bitfields on the type if it is packed or has a representation
	clause and an alternate layout is available.

Eric Botcazou
Index: config/i386/i386.c
--- config/i386/i386.c	(revision 186907)
+++ config/i386/i386.c	(working copy)
@@ -32465,8 +32465,7 @@ ix86_handle_struct_attribute (tree *node
     type = node;
-  if (!(type && (TREE_CODE (*type) == RECORD_TYPE
-		 || TREE_CODE (*type) == UNION_TYPE)))
+  if (!(type && RECORD_OR_UNION_TYPE_P (*type)))
       warning (OPT_Wattributes, "%qE attribute ignored",
Index: ada/gcc-interface/utils.c
--- ada/gcc-interface/utils.c	(revision 186956)
+++ ada/gcc-interface/utils.c	(working copy)
@@ -721,6 +721,19 @@ finish_record_type (tree record_type, tr
 	 case where there is a rep clause but all fields have errors and
 	 no longer have a position.  */
       TYPE_SIZE (record_type) = 0;
+      /* Ensure we use the traditional GCC layout for bitfields when we need
+	 to pack the record type or have a representation clause.  The other
+	 possible layout (Microsoft C compiler), if available, would prevent
+	 efficient packing in almost all cases.  */
+      if (TARGET_MS_BITFIELD_LAYOUT && TYPE_PACKED (record_type))
+	decl_attributes (&record_type,
+			 tree_cons (get_identifier ("gcc_struct"),
       layout_type (record_type);

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]