attributes weak and alias

From-SVN: r9391

gcc/c-common.c

@@ -30,7 +30,7 @@ extern struct obstack permanent_obstack;
 
 enum attrs {A_PACKED, A_NOCOMMON, A_NORETURN, A_CONST, A_T_UNION,
 	    A_CONSTRUCTOR, A_DESTRUCTOR, A_MODE, A_SECTION, A_ALIGNED,
-	    A_FORMAT};
+	    A_FORMAT, A_WEAK, A_ALIAS};
 
 static void declare_hidden_char_array	PROTO((char *, char *));
 static void add_attribute		PROTO((enum attrs, char *,
@@ -258,6 +258,8 @@ init_attributes ()
   add_attribute (A_SECTION, "section", 1, 1, 1);
   add_attribute (A_ALIGNED, "aligned", 0, 1, 0);
   add_attribute (A_FORMAT, "format", 3, 3, 1);
+  add_attribute (A_WEAK, "weak", 0, 0, 1);
+  add_attribute (A_ALIAS, "alias", 1, 1, 1);
 }
 
 /* Process the attributes listed in ATTRIBUTES and PREFIX_ATTRIBUTES
@@ -606,6 +608,29 @@ decl_attributes (node, attributes, prefix_attributes)
 				    is_scan, format_num, first_arg_num);
 	    break;
 	  }
+
+	case A_WEAK:
+	  declare_weak (decl);
+	  break;
+
+	case A_ALIAS:
+	  if ((TREE_CODE (decl) == FUNCTION_DECL && DECL_INITIAL (decl))
+	      || TREE_CODE (decl) != FUNCTION_DECL && ! DECL_EXTERNAL (decl))
+	    error_with_decl (decl,
+			     "`%s' defined both normally and as an alias");
+	  else if (decl_function_context (decl) == 0)
+	    {
+	      tree id = get_identifier (TREE_STRING_POINTER
+					(TREE_VALUE (args)));
+	      if (TREE_CODE (decl) == FUNCTION_DECL)
+		DECL_INITIAL (decl) = error_mark_node;
+	      else
+		DECL_EXTERNAL (decl) = 0;
+	      assemble_alias (decl, id);
+	    }
+	  else
+	    warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
+	  break;
 	}
     }
 }

gcc/config/aoutos.h

@@ -85,3 +85,18 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 	fputc ('\n', FILE);						\
       }									\
   } while (0)
+
+/* If we're using GNU as and ld, we support weak symbols.  */
+
+#define HANDLE_PRAGMA_WEAK flag_gnu_linker
+#define WEAK_ASM_OP	".weak"
+#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2)				\
+ do { if (flag_gnu_linker)						\
+	{								\
+	  fprintf ((FILE), "\t%s\t", ".set");				\
+	  assemble_name (FILE, LABEL1);					\
+	  fprintf (FILE, ",");						\
+	  assemble_name (FILE, LABEL2);					\
+	  fprintf (FILE, "\n");						\
+	}								\
+  } while (0)

gcc/config/sparc/sunos4.h

@@ -20,3 +20,18 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #define SUNOS4_SHARED_LIBRARIES 1
 
 #include "sparc/sparc.h"
+
+/* If we're using GNU as and ld, we support weak symbols.  */
+
+#define HANDLE_PRAGMA_WEAK flag_gnu_linker
+#define WEAK_ASM_OP	".weak"
+#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2)				\
+ do { if (flag_gnu_linker)						\
+	{								\
+	  fprintf ((FILE), "\t%s\t", ".set");				\
+	  assemble_name (FILE, LABEL1);					\
+	  fprintf (FILE, ",");						\
+	  assemble_name (FILE, LABEL2);					\
+	  fprintf (FILE, "\n");						\
+	}								\
+  } while (0)

gcc/toplev.c

@@ -2574,6 +2574,10 @@ compile_file (name)
       }
   }
 
+  /* Write out any pending weak symbol declarations.  */
+
+  weak_finish ();
+
   /* Do dbx symbols */
 #if defined (DBX_DEBUGGING_INFO) || defined (XCOFF_DEBUGGING_INFO)
   if (write_symbols == DBX_DEBUG || write_symbols == XCOFF_DEBUG)

gcc/varasm.c

@@ -97,8 +97,13 @@ int size_directive_output;
 tree last_assemble_variable_decl;
 
 /* Nonzero if at least one function definition has been seen.  */
+
 static int function_defined;
 
+/* Any weak symbol declarations waiting to be emitted.  */
+
+static tree weak_decls;
+
 struct addr_const;
 struct constant_descriptor;
 struct rtx_const;
@@ -3911,12 +3916,13 @@ output_constructor (exp, size)
     assemble_zeros (size - total_bytes);
 }
 
-
-#ifdef HANDLE_SYSV_PRAGMA
-
 /* Support #pragma weak by default if WEAK_ASM_OP and ASM_OUTPUT_DEF
    are defined.  */
-#if defined (WEAK_ASM_OP) && defined (ASM_OUTPUT_DEF)
+#if !defined (HANDLE_PRAGMA_WEAK) && defined (WEAK_ASM_OP) && defined (ASM_OUTPUT_DEF)
+#define HANDLE_PRAGMA_WEAK 1
+#endif
+
+#if defined (HANDLE_SYSV_PRAGMA) && defined (HANDLE_PRAGMA_WEAK)
 
 /* See c-pragma.c for an identical definition.  */
 enum pragma_state
@@ -3943,21 +3949,77 @@ handle_pragma_weak (what, asm_out_file, name, value)
 {
   if (what == ps_name || what == ps_value)
     {
-      fprintf (asm_out_file, "\t%s\t", WEAK_ASM_OP);
-
-      if (output_bytecode)
-	BC_OUTPUT_LABELREF (asm_out_file, name);
-      else
-	ASM_OUTPUT_LABELREF (asm_out_file, name);
-
-      fputc ('\n', asm_out_file);
-      if (what == ps_value)
-	ASM_OUTPUT_DEF (asm_out_file, name, value);
+      weak_decls = perm_tree_cons (what == ps_value ? value : NULL_TREE,
+				   name, weak_decls);
     }
   else if (! (what == ps_done || what == ps_start))
     warning ("malformed `#pragma weak'");
 }
 
-#endif /* HANDLE_PRAGMA_WEAK or (WEAK_ASM_OP and SET_ASM_OP) */
+#endif /* HANDLE_SYSV_PRAGMA && HANDLE_PRAGMA_WEAK */
+
+/* Declare DECL to be a weak symbol.  */
+
+void
+declare_weak (decl)
+     tree decl;
+{
+  if (! TREE_PUBLIC (decl))
+    error_with_decl (decl, "weak declaration of `%s' must be public");
+  else
+    weak_decls = perm_tree_cons (NULL_TREE, DECL_ASSEMBLER_NAME (decl),
+				 weak_decls);
+}
+
+/* Emit any pending weak declarations.  */
+
+void
+weak_finish ()
+{
+#ifdef HANDLE_PRAGMA_WEAK
+  if (HANDLE_PRAGMA_WEAK)
+    {
+      tree t;
+      for (t = weak_decls; t; t = TREE_CHAIN (t))
+	{
+	  tree decl = TREE_VALUE (t);
+	  char *name = XSTR (XEXP (DECL_RTL (decl), 0), 0);
 
-#endif /* WEAK_ASM_OP && ASM_OUTPUT_DEF */
+	  fprintf (asm_out_file, "\t%s\t", WEAK_ASM_OP);
+
+	  if (output_bytecode)
+	    BC_OUTPUT_LABELREF (asm_out_file, name);
+	  else
+	    ASM_OUTPUT_LABELREF (asm_out_file, name);
+
+	  fputc ('\n', asm_out_file);
+	}
+    }
+#endif
+}
+
+void
+assemble_alias (decl, target)
+     tree decl, target;
+{
+#ifdef ASM_OUTPUT_DEF
+  char *name;
+
+  make_decl_rtl (decl, (char*)0, 1);
+  name = XSTR (XEXP (DECL_RTL (decl), 0), 0);
+
+  /* Make name accessible from other files, if appropriate.  */
+
+  if (TREE_PUBLIC (decl))
+    {
+      if (output_bytecode)
+	BC_GLOBALIZE_LABEL (asm_out_file, name);
+      else
+	ASM_GLOBALIZE_LABEL (asm_out_file, name);
+    }
+
+  ASM_OUTPUT_DEF (asm_out_file, name, IDENTIFIER_POINTER (target));
+#else
+  warning ("alias definitions not supported in this configuration");
+#endif
+}