Add a generic .bss directive for ELF based targets.

PR 3136
	* config/obj-elf.c (elf_pseudo_table): Add entry for .bss.
	(obj_elf_bss): New function.  Change to the .bss section.
	Support an optional subsection number.
	(obj_elf_change_section): Call obj_elf_section_change_hook.
	(obj_elf_section): Likewise.
	(obj_elf_data): Likewise.
	(obj_elf_text): Likewise.
	(obj_elf_struct): Likewise.
	(obj_elf_subsection): Likewise.
	(obj_elf_previous): Likewise.
	* config/obj-elf.h (obj_elf_bss): Prototype.
	* doc/as.texi (Bss): New node.

gas/ChangeLog

@@ -1,3 +1,19 @@
+2021-05-07  Nick Clifton  <nickc@redhat.com>
+
+	PR 3136
+	* config/obj-elf.c (elf_pseudo_table): Add entry for .bss.
+	(obj_elf_bss): New function.  Change to the .bss section.
+	Support an optional subsection number.
+	(obj_elf_change_section): Call obj_elf_section_change_hook.
+	(obj_elf_section): Likewise.
+	(obj_elf_data): Likewise.
+	(obj_elf_text): Likewise.
+	(obj_elf_struct): Likewise.
+	(obj_elf_subsection): Likewise.
+	(obj_elf_previous): Likewise.
+	* config/obj-elf.h (obj_elf_bss): Prototype.
+	* doc/as.texi (Bss): New node.
+
 2021-05-07  Clément Chigot  <clement.chigot@atos.net>
 
 	* config/obj-coff.c (coff_frob_symbol): Don't skip C_DWARF.

gas/config/obj-elf.c

@@ -131,6 +131,7 @@ static const pseudo_typeS elf_pseudo_table[] =
   {"offset", obj_elf_struct, 0},
   {"struct", obj_elf_struct, 0},
   {"text", obj_elf_text, 0},
+  {"bss", obj_elf_bss, 0},
 
   {"tls_common", obj_elf_tls_common, 0},
 
@@ -603,8 +604,8 @@ obj_elf_change_section (const char *name,
       elt->prev_subseg = previous_subsection;
       section_stack = elt;
     }
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+
+  obj_elf_section_change_hook ();
 
   old_sec = bfd_get_section_by_name_if (stdoutput, name, get_section_by_match,
 					(void *) match_p);
@@ -1125,8 +1126,7 @@ obj_elf_section (int push)
       md_flush_pending_output ();
 #endif
 
-      previous_section = now_seg;
-      previous_subsection = now_subseg;
+      obj_elf_section_change_hook ();
 
       s_mri_sect (&mri_type);
 
@@ -1467,6 +1467,28 @@ obj_elf_section (int push)
     subseg_set (now_seg, new_subsection);
 }
 
+/* Change to the .bss section.  */
+
+void
+obj_elf_bss (int i ATTRIBUTE_UNUSED)
+{
+  int temp;
+
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
+  obj_elf_section_change_hook ();
+
+  temp = get_absolute_expression ();
+  subseg_set (bss_section, (subsegT) temp);
+  demand_empty_rest_of_line ();
+
+#ifdef md_elf_section_change_hook
+  md_elf_section_change_hook ();
+#endif
+}
+
 /* Change to the .data section.  */
 
 void
@@ -1476,8 +1498,8 @@ obj_elf_data (int i)
   md_flush_pending_output ();
 #endif
 
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+  obj_elf_section_change_hook ();
+
   s_data (i);
 
 #ifdef md_elf_section_change_hook
@@ -1494,8 +1516,8 @@ obj_elf_text (int i)
   md_flush_pending_output ();
 #endif
 
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+  obj_elf_section_change_hook ();
+
   s_text (i);
 
 #ifdef md_elf_section_change_hook
@@ -1512,8 +1534,8 @@ obj_elf_struct (int i)
   md_flush_pending_output ();
 #endif
 
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+  obj_elf_section_change_hook ();
+
   s_struct (i);
 
 #ifdef md_elf_section_change_hook
@@ -1530,8 +1552,7 @@ obj_elf_subsection (int ignore ATTRIBUTE_UNUSED)
   md_flush_pending_output ();
 #endif
 
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+  obj_elf_section_change_hook ();
 
   temp = get_absolute_expression ();
   subseg_set (now_seg, (subsegT) temp);
@@ -1570,8 +1591,8 @@ obj_elf_previous (int ignore ATTRIBUTE_UNUSED)
 
   new_section = previous_section;
   new_subsection = previous_subsection;
-  previous_section = now_seg;
-  previous_subsection = now_subseg;
+  obj_elf_section_change_hook ();
+
   subseg_set (new_section, new_subsection);
 
 #ifdef md_elf_section_change_hook

gas/config/obj-elf.h

@@ -189,6 +189,7 @@ extern const char * obj_elf_section_name (void);
 extern void obj_elf_previous (int);
 extern void obj_elf_version (int);
 extern void obj_elf_common (int);
+extern void obj_elf_bss (int);
 extern void obj_elf_data (int);
 extern void obj_elf_text (int);
 extern void obj_elf_change_section

gas/doc/as.texi

@@ -4365,6 +4365,7 @@ Some machine configurations provide additional directives.
 * Asciz::                       @code{.asciz "@var{string}"}@dots{}
 * Attach_to_group::             @code{.attach_to_group @var{name}}
 * Balign::                      @code{.balign [@var{abs-expr}[, @var{abs-expr}]]}
+* Bss::                         @code{.bss @var{subsection}}
 * Bundle directives::           @code{.bundle_align_mode @var{abs-expr}}, etc
 * Byte::                        @code{.byte @var{expressions}}
 * CFI directives::		@code{.cfi_startproc [simple]}, @code{.cfi_endproc}, etc.
@@ -4709,6 +4710,18 @@ filled in with the value 0x368d (the exact placement of the bytes depends upon
 the endianness of the processor).  If it skips 1 or 3 bytes, the fill value is
 undefined.
 
+@node Bss
+@section @code{.bss @var{subsection}}
+@cindex @code{bss} directive
+
+@code{.bss} tells @command{@value{AS}} to assemble the following statements
+onto the end of the bss section.
+@ifset ELF
+For ELF based targets an optional @var{subsection} expression (which must
+evaluate to a positive integer) can be provided.  In this case the statements
+are appended to the end of the indicated bss subsection.
+@end ifset
+
 @node Bundle directives
 @section Bundle directives
 @subsection @code{.bundle_align_mode @var{abs-expr}}