c-common.c (decl_attributes): Allow applying attribute `unused' on a LABEL_DECL.

        * c-common.c (decl_attributes): Allow applying attribute `unused'
        on a LABEL_DECL.
        * c-parse.in (label): Parse attributes after a label, and call
        `decl_attributes' to handle them.
        * gansidecl.h (ATTRIBUTE_UNUSED_LABEL): Define.
        * genrecog.c (OUTPUT_LABEL, write_tree_1, write_tree): When
        generating labels, mark them with ATTRIBUTE_UNUSED_LABEL.
        * invoke.texi: Note that labels can be marked `unused'.

From-SVN: r24478

gcc/ChangeLog

+Mon Jan  4 10:30:33 1999  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
+
+	* c-common.c (decl_attributes): Allow applying attribute `unused'
+	on a LABEL_DECL.
+
+	* c-parse.in (label): Parse attributes after a label, and call
+ 	`decl_attributes' to handle them.
+
+	* gansidecl.h (ATTRIBUTE_UNUSED_LABEL): Define.
+
+	* genrecog.c (OUTPUT_LABEL, write_tree_1, write_tree): When
+	generating labels, mark them with ATTRIBUTE_UNUSED_LABEL.
+
+	* invoke.texi: Note that labels can be marked `unused'.
+
 Sun Jan 3 23:32:18 PST 1999 Jeff Law  (law@cygnus.com)
 
 	* version.c: Bump for snapshot.

gcc/c-common.c

@@ -521,7 +521,8 @@ decl_attributes (node, attributes, prefix_attributes)
 	    TREE_USED (type) = 1;
 	  else if (TREE_CODE (decl) == PARM_DECL
 		   || TREE_CODE (decl) == VAR_DECL
-		   || TREE_CODE (decl) == FUNCTION_DECL)
+		   || TREE_CODE (decl) == FUNCTION_DECL
+		   || TREE_CODE (decl) == LABEL_DECL)
 	    TREE_USED (decl) = 1;
 	  else
 	    warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));

gcc/c-parse.in

@@ -2214,12 +2214,15 @@ label:	  CASE expr_no_commas ':'
 		      error_with_decl (duplicate, "this is the first default label");
 		    }
 		  position_after_white_space (); }
-	| identifier ':'
+	| identifier ':' maybe_attribute
 		{ tree label = define_label (input_filename, lineno, $1);
 		  stmt_count++;
 		  emit_nop ();
 		  if (label)
-		    expand_label (label);
+		    {
+		      expand_label (label);
+		      decl_attributes (label, $3, NULL_TREE);
+		    }
 		  position_after_white_space (); }
 	;
 

gcc/c-parse.y

@@ -2019,12 +2019,15 @@ label:	  CASE expr_no_commas ':'
 		      error_with_decl (duplicate, "this is the first default label");
 		    }
 		  position_after_white_space (); }
-	| identifier ':'
+	| identifier ':' maybe_attribute
 		{ tree label = define_label (input_filename, lineno, $1);
 		  stmt_count++;
 		  emit_nop ();
 		  if (label)
-		    expand_label (label);
+		    {
+		      expand_label (label);
+		      decl_attributes (label, $3, NULL_TREE);
+		    }
 		  position_after_white_space (); }
 	;
 

gcc/gansidecl.h

@@ -38,6 +38,14 @@ Boston, MA 02111-1307, USA.  */
 # define __attribute__(x)
 #endif
 
+#ifndef ATTRIBUTE_UNUSED_LABEL
+# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 92)
+#  define ATTRIBUTE_UNUSED_LABEL
+# else
+#  define ATTRIBUTE_UNUSED_LABEL ATTRIBUTE_UNUSED
+# endif /* GNUC < 2.92 */
+#endif /* ATTRIBUTE_UNUSED_LABEL */
+
 #ifndef ATTRIBUTE_UNUSED
 #define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 #endif /* ATTRIBUTE_UNUSED */

gcc/genrecog.c

@@ -51,6 +51,9 @@ Boston, MA 02111-1307, USA.  */
 #include "rtl.h"
 #include "obstack.h"
 
+#define OUTPUT_LABEL(INDENT_STRING, LABEL_NUMBER) \
+  printf("%sL%d: ATTRIBUTE_UNUSED_LABEL\n", (INDENT_STRING), (LABEL_NUMBER))
+
 static struct obstack obstack;
 struct obstack *rtl_obstack = &obstack;
 
@@ -1103,7 +1106,7 @@ write_tree_1 (tree, prevpos, afterward, type)
   printf ("\n");
   if (tree && tree->subroutine_number == 0)
     {
-      printf ("  L%d:\n", tree->number);
+      OUTPUT_LABEL ("  ", tree->number);
       tree->label_needed = 0;
     }
 
@@ -1239,7 +1242,7 @@ write_tree_1 (tree, prevpos, afterward, type)
 
       if (p->label_needed && (p->retest_mode || p->retest_code))
 	{
-	  printf ("%sL%d:\n", indents[indent - 2], p->number);
+	  OUTPUT_LABEL (indents[indent - 2], p->number);
 	  p->label_needed = 0;
 	}
 
@@ -1330,7 +1333,7 @@ write_tree_1 (tree, prevpos, afterward, type)
       /* Now that most mode and code tests have been done, we can write out
 	 a label for an inner node, if we haven't already.  */
       if (p->label_needed)
-	printf ("%sL%d:\n", indents[indent - 2], p->number);
+	OUTPUT_LABEL (indents[indent - 2], p->number);
 
       inner_indent = indent;
 
@@ -1563,7 +1566,7 @@ write_tree (tree, prevpos, afterward, initial, type)
 
   if (! initial && tree->subroutine_number > 0)
     {
-      printf (" L%d:\n", tree->number);
+      OUTPUT_LABEL (" ", tree->number);
 
       if (afterward)
 	{

gcc/invoke.texi

@@ -1340,7 +1340,7 @@ In order to get a warning about an unused function parameter, you must
 specify both @samp{-W} and @samp{-Wunused}.
 
 To suppress this warning for an expression, simply cast it to void.  For
-unused variables and parameters, use the @samp{unused} attribute
+unused variables, parameters and labels, use the @samp{unused} attribute
 (@pxref{Variable Attributes}).
 
 @item -Wuninitialized

gcc/objc/objc-parse.y

@@ -2128,12 +2128,15 @@ label:	  CASE expr_no_commas ':'
 		      error_with_decl (duplicate, "this is the first default label");
 		    }
 		  position_after_white_space (); }
-	| identifier ':'
+	| identifier ':' maybe_attribute
 		{ tree label = define_label (input_filename, lineno, $1);
 		  stmt_count++;
 		  emit_nop ();
 		  if (label)
-		    expand_label (label);
+		    {
+		      expand_label (label);
+		      decl_attributes (label, $3, NULL_TREE);
+		    }
 		  position_after_white_space (); }
 	;