-fno-common change

From-SVN: r11940

gcc/c-common.c

@@ -37,7 +37,7 @@ Boston, MA 02111-1307, USA.  */
 
 extern struct obstack permanent_obstack;
 
-enum attrs {A_PACKED, A_NOCOMMON, A_NORETURN, A_CONST, A_T_UNION,
+enum attrs {A_PACKED, A_NOCOMMON, A_COMMON, A_NORETURN, A_CONST, A_T_UNION,
 	    A_CONSTRUCTOR, A_DESTRUCTOR, A_MODE, A_SECTION, A_ALIGNED,
 	    A_UNUSED, A_FORMAT, A_WEAK, A_ALIAS};
 
@@ -263,6 +263,7 @@ init_attributes ()
 {
   add_attribute (A_PACKED, "packed", 0, 0, 0);
   add_attribute (A_NOCOMMON, "nocommon", 0, 0, 1);
+  add_attribute (A_COMMON, "common", 0, 0, 1);
   add_attribute (A_NORETURN, "noreturn", 0, 0, 1);
   add_attribute (A_NORETURN, "volatile", 0, 0, 1);
   add_attribute (A_UNUSED, "unused", 0, 0, 1);
@@ -358,6 +359,13 @@ decl_attributes (node, attributes, prefix_attributes)
 	    warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
 	  break;
 
+	case A_COMMON:
+	  if (TREE_CODE (decl) == VAR_DECL)
+	    DECL_COMMON (decl) = 1;
+	  else
+	    warning ("`%s' attribute ignored", IDENTIFIER_POINTER (name));
+	  break;
+
 	case A_NORETURN:
 	  if (TREE_CODE (decl) == FUNCTION_DECL)
 	    TREE_THIS_VOLATILE (decl) = 1;

gcc/c-decl.c

@@ -3611,8 +3611,12 @@ start_decl (declarator, declspecs, initialized, attributes, prefix_attributes)
   if (TREE_CODE (decl) == FUNCTION_DECL)
     gen_aux_info_record (decl, 0, 0, TYPE_ARG_TYPES (TREE_TYPE (decl)) != 0);
 
-  /* For C and Objective-C, we by default put things in .common when
-     possible.  */
+  /* ANSI specifies that a tentative definition which is not merged with
+     a non-tentative definition behaves exactly like a definition with an
+     initializer equal to zero.  (Section 3.7.2)
+     -fno-common gives strict ANSI behavior.  Usually you don't want it.
+     This matters only for variables with external linkage.  */
+  if (! flag_no_common)
     DECL_COMMON (decl) = 1;
 
   /* Set attributes here so if duplicate decl, will have proper attributes.  */

gcc/final.c

@@ -405,7 +405,7 @@ end_final (filename)
       }
 
       /* Make space for the table of counts.  */
-      if (flag_no_common || size == 0)
+      if (size == 0)
 	{
 	  /* Realign data section.  */
 	  ASM_OUTPUT_ALIGN (asm_out_file, align);

gcc/flags.h

@@ -315,7 +315,8 @@ extern int flag_pedantic_errors;
 
 extern int flag_pic;
 
-/* Nonzero means place uninitialized global data in the bss section.  */
+/* Nonzero means don't place uninitialized global data in common storage
+   by default.  */
 
 extern int flag_no_common;
 

gcc/toplev.c

@@ -482,7 +482,8 @@ int flag_short_temps;
 
 int flag_pic;
 
-/* Nonzero means place uninitialized global data in the bss section. */
+/* Nonzero means don't place uninitialized global data in common storage
+   by default. */
 
 int flag_no_common;
 

gcc/varasm.c

@@ -1229,18 +1229,11 @@ assemble_variable (decl, top_level, at_end, dont_output_data)
 
   /* Handle uninitialized definitions.  */
 
-  /* ANSI specifies that a tentative definition which is not merged with
-     a non-tentative definition behaves exactly like a definition with an
-     initializer equal to zero.  (Section 3.7.2)
-     -fno-common gives strict ANSI behavior.  Usually you don't want it.
-     This matters only for variables with external linkage.  */
-
   if ((DECL_INITIAL (decl) == 0 || DECL_INITIAL (decl) == error_mark_node)
       /* If the target can't output uninitialized but not common global data
 	 in .bss, then we have to use .data.  */
 #if ! defined (ASM_OUTPUT_BSS) && ! defined (ASM_OUTPUT_ALIGNED_BSS)
-      && (! flag_no_common || ! TREE_PUBLIC (decl))
-      && DECL_COMMON (decl)
+      && (DECL_COMMON (decl) || ! TREE_PUBLIC (decl))
 #endif
       && ! dont_output_data)
     {
@@ -1286,7 +1279,6 @@ assemble_variable (decl, top_level, at_end, dont_output_data)
       if (TREE_PUBLIC (decl)
 #if defined (ASM_OUTPUT_BSS) || defined (ASM_OUTPUT_ALIGNED_BSS)
 	  && DECL_COMMON (decl)
-	  && ! flag_no_common
 #endif
 	  )
 	{