i386.c (ix86_attribute_table): Add new attributes ms_struct and gcc_struct.

	* config/i386/i386.c (ix86_attribute_table): Add new attributes
	ms_struct and gcc_struct.
	(ix86_handle_struct_attribute): New function.
	(ix86_ms_bitfield_layout_p): Update to take new attributes
	into account.
	* doc/extend.texi: Document new attributes.
	* testsuite/gcc.dg/bf-ms-attrib.c: New test.

From-SVN: r61072

gcc/ChangeLog

+2003-01-08  Douglas B Rupp  <rupp@gnat.com>
+
+	* config/i386/i386.c (ix86_attribute_table): Add new attributes
+	ms_struct and gcc_struct.
+	(ix86_handle_struct_attribute): New function.
+	(ix86_ms_bitfield_layout_p): Update to take new attributes
+	into account.
+	* doc/extend.texi: Document new attributes.
+	* testsuite/gcc.dg/bf-ms-attrib.c: New test.
+
 2003-01-08  Danny Smith  <dannysmith@users.sourceforge.net>
 
         PR optimization/8750

gcc/config/i386/i386.c

@@ -870,6 +870,7 @@ static tree ix86_handle_cdecl_attribute PARAMS ((tree *, tree, tree, int, bool *
 static tree ix86_handle_regparm_attribute PARAMS ((tree *, tree, tree, int, bool *));
 static int ix86_value_regno PARAMS ((enum machine_mode));
 static bool ix86_ms_bitfield_layout_p PARAMS ((tree));
+static tree ix86_handle_struct_attribute PARAMS ((tree *, tree, tree, int, bool *));
 static int extended_reg_mentioned_1 PARAMS ((rtx *, void *));
 
 #if defined (DO_GLOBAL_CTORS_BODY) && defined (HAS_INIT_SECTION)
@@ -1456,6 +1457,8 @@ const struct attribute_spec ix86_attribute_table[] =
   { "dllexport", 0, 0, false, false, false, ix86_handle_dll_attribute },
   { "shared",    0, 0, true,  false, false, ix86_handle_shared_attribute },
 #endif
+  { "ms_struct", 0, 0, false, false,  false, ix86_handle_struct_attribute },
+  { "gcc_struct", 0, 0, false, false,  false, ix86_handle_struct_attribute },
   { NULL,        0, 0, false, false, false, NULL }
 };
 
@@ -14531,11 +14534,52 @@ x86_order_regs_for_local_alloc ()
 #define TARGET_USE_MS_BITFIELD_LAYOUT 0
 #endif
 
+/* Handle a "ms_struct" or "gcc_struct" attribute; arguments as in
+   struct attribute_spec.handler.  */
+static tree
+ix86_handle_struct_attribute (node, name, args, flags, no_add_attrs)
+     tree *node;
+     tree name;
+     tree args ATTRIBUTE_UNUSED;
+     int flags ATTRIBUTE_UNUSED;
+     bool *no_add_attrs;
+{
+  tree *type = NULL;
+  if (DECL_P (*node))
+    {
+      if (TREE_CODE (*node) == TYPE_DECL)
+	type = &TREE_TYPE (*node);
+    }
+  else
+    type = node;
+
+  if (!(type && (TREE_CODE (*type) == RECORD_TYPE
+		 || TREE_CODE (*type) == UNION_TYPE)))
+    {
+      warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
+      *no_add_attrs = true;
+    }
+
+  else if ((is_attribute_p ("ms_struct", name)
+	    && lookup_attribute ("gcc_struct", TYPE_ATTRIBUTES (*type)))
+	   || ((is_attribute_p ("gcc_struct", name)
+		&& lookup_attribute ("ms_struct", TYPE_ATTRIBUTES (*type)))))
+    {
+      warning ("`%s' incompatible attribute ignored",
+               IDENTIFIER_POINTER (name));
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 static bool
 ix86_ms_bitfield_layout_p (record_type)
-     tree record_type ATTRIBUTE_UNUSED;
+     tree record_type;
 {
-  return TARGET_USE_MS_BITFIELD_LAYOUT;
+  return (TARGET_USE_MS_BITFIELD_LAYOUT &&
+      !lookup_attribute ("gcc_struct", TYPE_ATTRIBUTES (record_type)))
+    || lookup_attribute ("ms_struct", TYPE_ATTRIBUTES (record_type));
 }
 
 /* Returns an expression indicating where the this parameter is

gcc/doc/extend.texi

@@ -3212,6 +3212,26 @@ Medium and large model objects may live anywhere in the 32-bit address space
 (the compiler will generate @code{seth/add3} instructions to load their
 addresses).
 
+@subsection i386 Variable Attributes
+
+Two attributes are currently defined for i386 configurations:
+@code{ms_struct} and @code{gcc_struct}
+
+@item ms_struct
+@itemx gcc_struct
+@cindex @code{ms_struct}
+@cindex @code{gcc_struct}
+
+If @code{packed} is used on a structure, or if bit-fields are used
+it may be that the Microsoft ABI packs them differently
+than GCC would normally pack them.  Particularly when moving packed
+data between functions compiled with GCC and the native Microsoft compiler
+(either via function call or as data in a file), it may be necessary to access
+either format.
+
+Currently @option{-m[no-]ms-bitfields} is provided for the Windows X86
+compilers to match the native Microsoft compiler.
+
 @end table
 
 To specify multiple attributes, separate them by commas within the
@@ -3471,6 +3491,26 @@ If you replaced @code{short_a} with @code{short} in the variable
 declaration, the above program would abort when compiled with
 @option{-fstrict-aliasing}, which is on by default at @option{-O2} or
 above in recent GCC versions.
+
+@subsection i386 Type Attributes
+
+Two attributes are currently defined for i386 configurations:
+@code{ms_struct} and @code{gcc_struct}
+
+@item ms_struct
+@itemx gcc_struct
+@cindex @code{ms_struct}
+@cindex @code{gcc_struct}
+
+If @code{packed} is used on a structure, or if bit-fields are used
+it may be that the Microsoft ABI packs them differently
+than GCC would normally pack them.  Particularly when moving packed
+data between functions compiled with GCC and the native Microsoft compiler
+(either via function call or as data in a file), it may be necessary to access
+either format.
+
+Currently @option{-m[no-]ms-bitfields} is provided for the Windows X86
+compilers to match the native Microsoft compiler.
 @end table
 
 To specify multiple attributes, separate them by commas within the

gcc/testsuite/gcc.dg/bf-ms-attrib.c

+/* bf-ms-attrib.c */
+/* Adapted from Donn Terry <donnte@microsoft.com> testcase
+   posted to GCC-patches
+   http://gcc.gnu.org/ml/gcc-patches/2000-08/msg00577.html */ 
+
+/* { dg-do run { target *-*-interix* } } */
+
+/* We don't want the default "pedantic-errors" in this case, since we're
+   testing nonstandard stuff to begin with. */
+/* { dg-options "-ansi" } */
+
+#include <stdio.h>
+
+struct one_gcc {
+  int d;
+  unsigned char a;
+  unsigned short b:7;
+  char c;	
+} __attribute__((__gcc_struct__)) ;
+
+
+struct one_ms {
+  int d;
+  unsigned char a;
+  unsigned short b:7;
+  char c;	
+} __attribute__((__ms_struct__));
+
+
+main() 
+  {
+    /* As long as the sizes are as expected, we know attributes are working.
+       bf-ms-layout.c makes sure the right thing happens when the attribute
+       is on. */
+    if (sizeof(struct one_ms) != 12)
+	abort();
+    if (sizeof(struct one_gcc) != 8)
+	abort();
+  }