bfd/

2011-12-14  Iain Sandoe  <iains@gcc.gnu.org>

	* mach-o-i386.c (text_section_names_xlat): New table.
	(data_section_names_xlat): Likewise.
	(import_section_names_xlat): Likewise.
	(mach_o_i386_segsec_names_xlat): Likewise.
	(bfd_mach_o_tgt_seg_table): Use new tables.
	* mach-o-x86-64.c (bfd_mach_o_tgt_seg_table): Set NULL.
	* mach-o.c (mach_o_section_name_xlat, mach_o_segment_name_xlat):
	Move to mach-o.h as   typedefs.
	(text_section_names_xlat): Update for current GCC usage.
	(data_section_names_xlat): Likewise.
	(dwarf_section_names_xlat): Likewise.
	(objc_section_names_xlat): New table.
	(segsec_names_xlat): Add objc table.
	(bfd_mach_o_normalize_section_name):  Replace with...
	(bfd_mach_o_section_data_for_mach_sect): New.
	(bfd_mach_o_section_data_for_bfd_name): New.
	(bfd_mach_o_section_data_for_bfd_name): Update to use additional data.
	(bfd_mach_o_convert_section_name_to_mach_o): Likewise.
	(bfd_mach_o_bfd_copy_private_section_data): Implement.
	(bfd_mach_o_write_symtab): Write a zero-length string as the first entry
	for compatibility with system tools.
	(bfd_mach_o_build_commands): Update section alignment info.
	(bfd_mach_o_new_section_hook): Use translation table data to define
	default section flags, type, attributes and alignment, when available.
	(bfd_mach_o_init_section_from_mach_o): Add TODO comment.
	(bfd_mach_o_section_type_name): Add 'symbol_stubs'.
	(bfd_mach_o_section_attribute_name): Add 'self_modifying_code'.
	(bfd_mach_o_get_section_type_from_name): Change "not-found" return
	value.
	(bfd_mach_o_tgt_seg_table): Set default NULL.
	* mach-o.h (bfd_mach_o_segment_command):  Use define for name length.
	(bfd_mach_o_backend_data): Move until after contents are defined.
	(bfd_mach_o_normalize_section_name): Remove.
	(bfd_mach_o_convert_section_name_to_bfd): Declare.
	(mach_o_section_name_xlat): Declare.
	(mach_o_segment_name_xlat): Declare.
	(bfd_mach_o_section_data_for_mach_sect): Declare.
	(bfd_mach_o_section_data_for_bfd_name): Declare.

include/
2011-12-14  Iain Sandoe  <iains@gcc.gnu.org>

	* mach-o/loader.h (bfd_mach_o_section_type): define
	BFD_MACH_O_S_ATTR_NONE to 0.


gas/
2011-12-14  Iain Sandoe  <iains@gcc.gnu.org>

	* config/obj-macho.c: Add some more top-level comments.
	(collect_16char_name): New.
	(obj_mach_o_section): Amend to allow syntax compatible with existing system
	tools.  Use section translation data when available.
	(obj_mach_o_segT_from_bfd_name): New.
	(known_sections): Update.
	(obj_mach_o_known_section): Use obj_mach_o_segT_from_bfd_name.
	(objc_sections): New.
	(obj_mach_o_objc_section): New.
	(debug_sections): New.
	(obj_mach_o_debug_section): New.
	(tgt_sections): New.
	(obj_mach_o_opt_tgt_section): New.
	(obj_mach_o_base_section): New.
	(obj_mach_o_common_parse): Update to create BSS on demand and to handle
	lcomm optional alignment param.
	(obj_mach_o_comm): Update parameter name.
	(obj_mach_o_placeholder): New.
	(mach_o_pseudo_table): Update for GCC section directives.
	* config/obj-macho.h (_OBJ_MACH_O_H): New.
	(USE_ALIGN_PTWO): Define.
	(S_SET_ALIGN) Define.

1 files changed, 574 insertions, 102 deletions

diff --git a/gas/config/obj-macho.c b/gas/config/obj-macho.c
index 5f1255d..018f653 100644
--- a/gas/config/obj-macho.c
+++ b/gas/config/obj-macho.c
@@ -1,5 +1,5 @@
 /* Mach-O object file format
-   Copyright 2009 Free Software Foundation, Inc.
+   Copyright 2009, 2011 Free Software Foundation, Inc.
 
    This file is part of GAS, the GNU Assembler.
 
@@ -18,6 +18,23 @@
    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
    02110-1301, USA.  */
 
+/* Here we handle the mach-o directives that are common to all architectures.
+
+   Most significant are mach-o named sections and a variety of symbol type
+   decorations.  */
+
+/* Mach-O supports multiple, named segments each of which may contain
+   multiple named sections.  Thus the concept of subsectioning is 
+   handled by (say) having a __TEXT segment with appropriate flags from
+   which subsections are generated like __text, __const etc.  
+   
+   The well-known as short-hand section switch directives like .text, .data
+   etc. are mapped onto predefined segment/section pairs using facilites
+   supplied by the mach-o port of bfd.
+   
+   A number of additional mach-o short-hand section switch directives are
+   also defined.  */
+
 #define OBJ_HEADER "obj-macho.h"
 
 #include "as.h"
@@ -26,6 +43,15 @@
 #include "write.h"
 #include "mach-o.h"
 #include "mach-o/loader.h"
+#include "obj-macho.h"
+
+/* TODO: Implement "-dynamic"/"-static" command line options.  */
+
+static int obj_mach_o_is_static;
+
+/* Allow for special re-ordering on output.  */
+
+static int seen_objc_section;
 
 static void
 obj_mach_o_weak (int ignore ATTRIBUTE_UNUSED)
@@ -53,104 +79,172 @@ obj_mach_o_weak (int ignore ATTRIBUTE_UNUSED)
   demand_empty_rest_of_line ();
 }
 
-/* Parse:
-   .section segname,sectname[,type[,attribute[,sizeof_stub]]]
-*/
+/* This will put at most 16 characters (terminated by a ',' or newline) from
+   the input stream into dest.  If there are more than 16 chars before the
+   delimiter, a warning is given and the string is truncated.  On completion of
+   this function, input_line_pointer will point to the char after the ',' or 
+   to the newline.  
+   
+   It trims leading and trailing space.  */
+
+static int
+collect_16char_name (char *dest, const char *msg, int require_comma)
+{
+  char c, *namstart;
+
+  SKIP_WHITESPACE ();
+  namstart = input_line_pointer;
+
+  while ( (c = *input_line_pointer) != ',' 
+	 && !is_end_of_line[(unsigned char) c])
+    input_line_pointer++;
+
+  {
+      int len = input_line_pointer - namstart; /* could be zero.  */
+      /* lose any trailing space.  */  
+      while (len > 0 && namstart[len-1] == ' ') 
+        len--;
+      if (len > 16)
+        {
+          *input_line_pointer = '\0'; /* make a temp string.  */
+	  as_bad (_("the %s name '%s' is too long (maximum 16 characters)"),
+		     msg, namstart);
+	  *input_line_pointer = c; /* restore for printing.  */
+	  len = 16;
+	}
+      if (len > 0)
+        memcpy (dest, namstart, len);
+  }
+
+  if (c != ',' && require_comma)
+    {
+      as_bad (_("expected a %s name followed by a `,'"), msg);
+      return 1;
+    }
+
+  return 0;
+}
+
+/* .section
+
+   The '.section' specification syntax looks like:
+   .section <segment> , <section> [, type [, attribs [, size]]]
+
+   White space is allowed everywhere between elements.
+
+   <segment> and <section> may be from 0 to 16 chars in length - they may
+   contain spaces but leading and trailing space will be trimmed.  It is 
+   mandatory that they be present (or that zero-length names are indicated
+   by ",,").
+
+   There is only a single section type for any entry.
+
+   There may be multiple attributes, they are delimited by `+'.
+
+   Not all section types and attributes are accepted by the Darwin system
+   assemblers as user-specifiable - although, at present, we do here.  */
 
 static void
 obj_mach_o_section (int ignore ATTRIBUTE_UNUSED)
 {
   char *p;
-  char *segname;
-  char *sectname;
   char c;
-  int sectype = BFD_MACH_O_S_REGULAR;
+  unsigned int sectype = BFD_MACH_O_S_REGULAR;
+  unsigned int defsectype = BFD_MACH_O_S_REGULAR;
+  unsigned int sectype_given = 0;
   unsigned int secattr = 0;
+  unsigned int defsecattr = 0;
+  int secattr_given = 0;
+  unsigned int secalign = 0;
   offsetT sizeof_stub = 0;
+  const mach_o_section_name_xlat * xlat;
   const char *name;
   flagword oldflags, flags;
   asection *sec;
+  bfd_mach_o_section *msect;
+  char segname[17];
+  char sectname[17];
 
+  /* Zero-length segment and section names are allowed.  */
   /* Parse segment name.  */
-  if (!is_name_beginner (*input_line_pointer))
-    {
-      as_bad (_("missing segment name"));
-      ignore_rest_of_line ();
-      return;
-    }
-  p = input_line_pointer;
-  c = get_symbol_end ();
-  segname = alloca (input_line_pointer - p + 1);
-  strcpy (segname, p);
-  *input_line_pointer = c;
-
-  if (*input_line_pointer != ',')
+  memset (segname, 0, sizeof(segname));
+  if (collect_16char_name (segname, "segment", 1))
     {
-      as_bad (_("missing comma after segment name"));
       ignore_rest_of_line ();
       return;
     }
-  input_line_pointer++;
+  input_line_pointer++; /* Skip the terminating ',' */
 
   /* Parse section name.  */
-  if (!is_name_beginner (*input_line_pointer))
-    {
-      as_bad (_("missing section name"));
-      ignore_rest_of_line ();
-      return;
-    }
-  p = input_line_pointer;
-  c = get_symbol_end ();
-  sectname = alloca (input_line_pointer - p + 1);
-  strcpy (sectname, p);
-  *input_line_pointer = c;
+  memset (sectname, 0, sizeof(sectname));
+  collect_16char_name (sectname, "section", 0);
 
   /* Parse type.  */
   if (*input_line_pointer == ',')
     {
+      char tmpc;
+      int len;
       input_line_pointer++;
-      if (!is_name_beginner (*input_line_pointer))
-        {
-          as_bad (_("missing section type name"));
-          ignore_rest_of_line ();
-          return;
-        }
+      SKIP_WHITESPACE ();
       p = input_line_pointer;
-      c = get_symbol_end ();
-
+      while ((c = *input_line_pointer) != ','
+	      && !is_end_of_line[(unsigned char) c])
+	input_line_pointer++;
+
+      len = input_line_pointer - p;
+      /* strip trailing spaces.  */
+      while (len > 0 && p[len-1] == ' ')
+	len--;
+      tmpc = p[len];
+
+      /* Temporarily make a string from the token.  */
+      p[len] = 0;
       sectype = bfd_mach_o_get_section_type_from_name (p);
-      if (sectype == -1)
+      if (sectype > 255) /* Max Section ID == 255.  */
         {
           as_bad (_("unknown or invalid section type '%s'"), p);
           sectype = BFD_MACH_O_S_REGULAR;
         }
-      *input_line_pointer = c;
-
-      /* Parse attributes.  */
-      if (*input_line_pointer == ',')
+      else
+	sectype_given = 1;
+      /* Restore.  */
+      tmpc = p[len];
+
+      /* Parse attributes.
+	 TODO: check validity of attributes for section type.  */
+      if (sectype_given && c == ',')
         {
           do
             {
               int attr;
 
+	      /* Skip initial `,' and subsequent `+'.  */
               input_line_pointer++;
-
-              if (!is_name_beginner (*input_line_pointer))
-                {
-                  as_bad (_("missing section attribute identifier"));
-                  ignore_rest_of_line ();
-                  break;
-                }
-              p = input_line_pointer;
-              c = get_symbol_end ();
-
+	      SKIP_WHITESPACE ();
+	      p = input_line_pointer;
+	      while ((c = *input_line_pointer) != '+'
+		      && c != ','
+		      && !is_end_of_line[(unsigned char) c])
+		input_line_pointer++;
+
+	      len = input_line_pointer - p;
+	      /* strip trailing spaces.  */
+	      while (len > 0 && p[len-1] == ' ')
+		len--;
+	      tmpc = p[len];
+
+	      /* Temporarily make a string from the token.  */
+	      p[len] ='\0';
               attr = bfd_mach_o_get_section_attribute_from_name (p);
-              if (attr == -1)
+	      if (attr == -1)
                 as_bad (_("unknown or invalid section attribute '%s'"), p);
               else
-                secattr |= attr;
-
-              *input_line_pointer = c;
+		{
+		  secattr_given = 1;
+                  secattr |= attr;
+		}
+	      /* Restore.  */
+	      p[len] = tmpc;
             }
           while (*input_line_pointer == '+');
 
@@ -160,6 +254,7 @@ obj_mach_o_section (int ignore ATTRIBUTE_UNUSED)
               if (sectype != BFD_MACH_O_S_SYMBOL_STUBS)
                 as_bad (_("unexpected sizeof_stub expression"));
 
+	      input_line_pointer++;
               sizeof_stub = get_absolute_expression ();
             }
           else if (sectype == BFD_MACH_O_S_SYMBOL_STUBS)
@@ -168,8 +263,19 @@ obj_mach_o_section (int ignore ATTRIBUTE_UNUSED)
     }
   demand_empty_rest_of_line ();
 
-  bfd_mach_o_normalize_section_name (segname, sectname, &name, &flags);
-  if (name == NULL)
+  flags = SEC_NO_FLAGS;
+  /* This provides default bfd flags and default mach-o section type and
+     attributes along with the canonical name.  */
+  xlat = bfd_mach_o_section_data_for_mach_sect (stdoutput, segname, sectname);
+  if (xlat != NULL)
+    {
+      name = xstrdup (xlat->bfd_name);
+      flags = xlat->bfd_flags;
+      defsectype = xlat->macho_sectype;
+      defsecattr = xlat->macho_secattr;
+      secalign = xlat->sectalign;
+    }
+  else
     {
       /* There is no normal BFD section name for this section.  Create one.
          The name created doesn't really matter as it will never be written
@@ -194,90 +300,368 @@ obj_mach_o_section (int ignore ATTRIBUTE_UNUSED)
   sec = subseg_new (name, 0);
 
   oldflags = bfd_get_section_flags (stdoutput, sec);
-  if (oldflags == SEC_NO_FLAGS)
+  msect = bfd_mach_o_get_mach_o_section (sec);
+   if (oldflags == SEC_NO_FLAGS)
     {
-      bfd_mach_o_section *msect;
-
       if (! bfd_set_section_flags (stdoutput, sec, flags))
 	as_warn (_("error setting flags for \"%s\": %s"),
 		 bfd_section_name (stdoutput, sec),
 		 bfd_errmsg (bfd_get_error ()));
-      msect = bfd_mach_o_get_mach_o_section (sec);
       strncpy (msect->segname, segname, sizeof (msect->segname));
       msect->segname[16] = 0;
       strncpy (msect->sectname, sectname, sizeof (msect->sectname));
       msect->sectname[16] = 0;
-      msect->flags = secattr | sectype;
+      msect->align = secalign;
+      if (sectype_given)
+	{
+	  msect->flags = sectype;
+	  if (secattr_given)
+	    msect->flags |= secattr;
+	  else
+	    msect->flags |= defsecattr;
+	}
+      else
+        msect->flags = defsectype | defsecattr;
       msect->reserved2 = sizeof_stub;
     }
   else if (flags != SEC_NO_FLAGS)
     {
-      if (flags != oldflags)
+      if (flags != oldflags
+	  || msect->flags != (secattr | sectype))
 	as_warn (_("Ignoring changed section attributes for %s"), name);
     }
 }
 
-struct known_section
+static segT 
+obj_mach_o_segT_from_bfd_name (const char *nam, int must_succeed)
 {
-  const char *name;
-  unsigned int flags;
+  const mach_o_section_name_xlat *xlat;
+  const char *segn;
+  segT sec;
+
+  /* BFD has tables of flags and default attributes for all the sections that
+     have a 'canonical' name.  */
+  xlat = bfd_mach_o_section_data_for_bfd_name (stdoutput, nam, &segn);
+  if (xlat == NULL)
+    {
+      if (must_succeed)
+	as_fatal (_("BFD is out of sync with GAS, "
+		     "unhandled well-known section type `%s'"), nam);
+      return NULL;
+    }
+
+  sec = bfd_get_section_by_name (stdoutput, nam);
+  if (sec == NULL)
+    {
+      bfd_mach_o_section *msect;
+
+      sec = subseg_force_new (xlat->bfd_name, 0);
+
+      /* Set default type, attributes and alignment.  */
+      msect = bfd_mach_o_get_mach_o_section (sec);
+      msect->flags = xlat->macho_sectype | xlat->macho_secattr;
+      msect->align = xlat->sectalign;
+
+      if ((msect->flags & BFD_MACH_O_SECTION_TYPE_MASK) 
+	  == BFD_MACH_O_S_ZEROFILL)
+	seg_info (sec)->bss = 1;
+    }
+
+  return sec;
+}
+
+static const char * const known_sections[] =
+{
+  /*  0 */ NULL,
+  /* __TEXT */
+  /*  1 */ ".const",
+  /*  2 */ ".static_const",
+  /*  3 */ ".cstring",
+  /*  4 */ ".literal4",
+  /*  5 */ ".literal8",
+  /*  6 */ ".literal16",
+  /*  7 */ ".constructor",
+  /*  8 */ ".destructor",
+  /*  9 */ ".eh_frame",
+  /* __DATA */
+  /* 10 */ ".const_data",
+  /* 11 */ ".static_data",
+  /* 12 */ ".mod_init_func",
+  /* 13 */ ".mod_term_func",
+  /* 14 */ ".dyld",
+  /* 15 */ ".cfstring"
 };
 
-static const struct known_section known_sections[] =
-  {
-    /* 0 */ { NULL, 0},
-    /* 1 */ { ".cstring", BFD_MACH_O_S_CSTRING_LITERALS }
-  };
+/* Interface for a known non-optional section directive.  */
 
 static void
 obj_mach_o_known_section (int sect_index)
 {
-  const struct known_section *sect = &known_sections[sect_index];
-  asection *old_sec;
-  segT sec;
+  segT section;
+
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
+  section = obj_mach_o_segT_from_bfd_name (known_sections[sect_index], 1);
+  if (section != NULL)
+    subseg_set (section, 0);
+
+  /* else, we leave the section as it was; there was a fatal error anyway.  */
+}
+
+static const char * const objc_sections[] =
+{
+  /*  0 */ NULL,
+  /*  1 */ ".objc_class",
+  /*  2 */ ".objc_meta_class",
+  /*  3 */ ".objc_cat_cls_meth",
+  /*  4 */ ".objc_cat_inst_meth",
+  /*  5 */ ".objc_protocol",
+  /*  6 */ ".objc_string_object",
+  /*  7 */ ".objc_cls_meth",
+  /*  8 */ ".objc_inst_meth",
+  /*  9 */ ".objc_cls_refs",
+  /* 10 */ ".objc_message_refs",
+  /* 11 */ ".objc_symbols",
+  /* 12 */ ".objc_category",
+  /* 13 */ ".objc_class_vars",
+  /* 14 */ ".objc_instance_vars",
+  /* 15 */ ".objc_module_info",
+  /* 16 */ ".cstring", /* objc_class_names Alias for .cstring */
+  /* 17 */ ".cstring", /* Alias objc_meth_var_types for .cstring */
+  /* 18 */ ".cstring", /* objc_meth_var_names Alias for .cstring */
+  /* 19 */ ".objc_selector_strs",
+  /* 20 */ ".objc_image_info", /* extension.  */
+  /* 21 */ ".objc_selector_fixup", /* extension.  */
+  /* 22 */ ".objc1_class_ext", /* ObjC-1 extension.  */
+  /* 23 */ ".objc1_property_list", /* ObjC-1 extension.  */
+  /* 24 */ ".objc1_protocol_ext" /* ObjC-1 extension.  */
+};
+
+/* This currently does the same as known_sections, but kept separate for
+   ease of maintenance.  */
+
+static void
+obj_mach_o_objc_section (int sect_index)
+{
+  segT section;
+  
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
+  section = obj_mach_o_segT_from_bfd_name (objc_sections[sect_index], 1);
+  if (section != NULL)
+    {
+      seen_objc_section = 1; /* We need to ensure that certain sections are
+				present and in the right order.  */
+      subseg_set (section, 0);
+    }
+
+  /* else, we leave the section as it was; there was a fatal error anyway.  */
+}
+
+/* Debug section directives.  */
+
+static const char * const debug_sections[] =
+{
+  /*  0 */ NULL,
+  /* __DWARF */
+  /*  1 */ ".debug_frame",
+  /*  2 */ ".debug_info",
+  /*  3 */ ".debug_abbrev",
+  /*  4 */ ".debug_aranges",
+  /*  5 */ ".debug_macinfo",
+  /*  6 */ ".debug_line",
+  /*  7 */ ".debug_loc",
+  /*  8 */ ".debug_pubnames",
+  /*  9 */ ".debug_pubtypes",
+  /* 10 */ ".debug_str",
+  /* 11 */ ".debug_ranges",
+  /* 12 */ ".debug_macro"
+};
+
+/* ??? Maybe these should be conditional on gdwarf-*.
+   It`s also likely that we will need to be able to set them from the cfi
+   code.  */
+
+static void
+obj_mach_o_debug_section (int sect_index)
+{
+  segT section;
+
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
+  section = obj_mach_o_segT_from_bfd_name (debug_sections[sect_index], 1);
+  if (section != NULL)
+    subseg_set (section, 0);
+
+  /* else, we leave the section as it was; there was a fatal error anyway.  */
+}
+
+/* This could be moved to the tc-xx files, but there is so little dependency
+   there, that the code might as well be shared.  */
+
+struct opt_tgt_sect 
+{
+ const char *name;
+ unsigned x86_val;
+ unsigned ppc_val;
+};
+
+/* The extensions here are for specific sections that are generated by GCC
+   and Darwin system tools, but don't have directives in the `system as'.  */
+
+static const struct opt_tgt_sect tgt_sections[] =
+{
+  /*  0 */ { NULL, 0, 0},
+  /*  1 */ { ".lazy_symbol_pointer", 0, 0},
+  /*  2 */ { ".lazy_symbol_pointer2", 0, 0}, /* X86 - extension */
+  /*  3 */ { ".lazy_symbol_pointer3", 0, 0}, /* X86 - extension */
+  /*  4 */ { ".non_lazy_symbol_pointer", 0, 0},
+  /*  5 */ { ".non_lazy_symbol_pointer_x86", 0, 0}, /* X86 - extension */
+  /*  6 */ { ".symbol_stub", 16, 20},
+  /*  7 */ { ".symbol_stub1", 0, 16}, /* PPC - extension */
+  /*  8 */ { ".picsymbol_stub", 26, 36},
+  /*  9 */ { ".picsymbol_stub1", 0, 32}, /* PPC - extension */
+  /* 10 */ { ".picsymbol_stub2", 25, 0}, /* X86 - extension */
+  /* 11 */ { ".picsymbol_stub3", 5, 0}, /* X86 - extension  */
+};
+
+/* Interface for an optional section directive.  */
+
+static void
+obj_mach_o_opt_tgt_section (int sect_index)
+{
+  const struct opt_tgt_sect *tgtsct = &tgt_sections[sect_index];
+  segT section;
 
 #ifdef md_flush_pending_output
   md_flush_pending_output ();
 #endif
 
-  old_sec = bfd_get_section_by_name (stdoutput, sect->name);
-  if (old_sec)
+  section = obj_mach_o_segT_from_bfd_name (tgtsct->name, 0);
+  if (section == NULL)
     {
-      /* Section already present.  */
-      sec = old_sec;
-      subseg_set (sec, 0);
+      as_bad (_("%s is not used for the selected target"), tgtsct->name);
+      /* Leave the section as it is.  */
     }
   else
     {
-      bfd_mach_o_section *msect;
+      bfd_mach_o_section *mo_sec = bfd_mach_o_get_mach_o_section (section);
+      subseg_set (section, 0);
+#if defined (TC_I386)
+      mo_sec->reserved2 = tgtsct->x86_val;
+#elif defined (TC_PPC)
+      mo_sec->reserved2 = tgtsct->ppc_val;
+#else
+      mo_sec->reserved2 = 0;
+#endif
+    }
+}
 
-      sec = subseg_force_new (sect->name, 0);
+/* We don't necessarily have the three 'base' sections on mach-o.
+   Normally, we would start up with only the 'text' section defined.
+   However, even that can be suppressed with (TODO) c/l option "-n".
+   Thus, we have to be able to create all three sections on-demand.  */
 
-      /* Set default flags.  */
-      msect = bfd_mach_o_get_mach_o_section (sec);
-      msect->flags = sect->flags;
+static void
+obj_mach_o_base_section (int sect_index)
+{
+  segT section;
+
+#ifdef md_flush_pending_output
+  md_flush_pending_output ();
+#endif
+
+  /* We don't support numeric (or any other) qualifications on the
+     well-known section shorthands.  */
+  demand_empty_rest_of_line ();
+
+  switch (sect_index)
+    {
+      /* Handle the three sections that are globally known within GAS.
+	 For Mach-O, these are created on demand rather than at startup.  */
+      case 1:
+	if (text_section == NULL)
+	  text_section = obj_mach_o_segT_from_bfd_name (TEXT_SECTION_NAME, 1);
+	if (obj_mach_o_is_static)
+	  {
+	    bfd_mach_o_section *mo_sec
+		= bfd_mach_o_get_mach_o_section (text_section);
+	    mo_sec->flags &= ~BFD_MACH_O_S_ATTR_PURE_INSTRUCTIONS;
+	  }
+	section = text_section;
+	break;
+      case 2:
+	if (data_section == NULL)
+	  data_section = obj_mach_o_segT_from_bfd_name (DATA_SECTION_NAME, 1);
+	section = data_section;
+	break;
+      case 3:
+        /* ??? maybe this achieves very little, as an addition.  */
+	if (bss_section == NULL)
+	  {
+	    bss_section = obj_mach_o_segT_from_bfd_name (BSS_SECTION_NAME, 1);
+	    seg_info (bss_section)->bss = 1;
+	  }
+	section = bss_section;
+	break;
+      default:
+        as_fatal (_("internal error: base section index out of range"));
+        return;
+	break;
     }
+  subseg_set (section, 0);
 }
 
-/* Called from read.c:s_comm after we've parsed .comm symbol, size.
-   Parse a possible alignment value.  */
+/* This finishes off parsing a .comm or .lcomm statement, which both can have
+   an (optional) alignment field.  It also allows us to create the bss section
+   on demand.  */
 
 static symbolS *
-obj_mach_o_common_parse (int ignore ATTRIBUTE_UNUSED,
-                         symbolS *symbolP, addressT size)
+obj_mach_o_common_parse (int is_local, symbolS *symbolP,
+			 addressT size)
 {
   addressT align = 0;
 
+  /* Both comm and lcomm take an optional alignment, as a power
+     of two between 1 and 15.  */
   if (*input_line_pointer == ',')
     {
+      /* We expect a power of 2.  */
       align = parse_align (0);
       if (align == (addressT) -1)
 	return NULL;
+      if (align > 15)
+	{
+	  as_warn (_("Alignment (%lu) too large: 15 assumed."),
+		  (unsigned long)align);
+	  align = 15;
+	}
     }
 
-  S_SET_VALUE (symbolP, size);
-  S_SET_EXTERNAL (symbolP);
-  S_SET_SEGMENT (symbolP, bfd_com_section_ptr);
+  if (is_local)
+    {
+      /* Create the BSS section on demand.  */
+      if (bss_section == NULL)
+	{
+	  bss_section = obj_mach_o_segT_from_bfd_name (BSS_SECTION_NAME, 1);
+	  seg_info (bss_section)->bss = 1;	  
+	}
+      bss_alloc (symbolP, size, align);
+      S_CLEAR_EXTERNAL (symbolP);
+    }
+  else
+    {
+      S_SET_VALUE (symbolP, size);
+      S_SET_ALIGN (symbolP, align);
+      S_SET_EXTERNAL (symbolP);
+      S_SET_SEGMENT (symbolP, bfd_com_section_ptr);
+    }
 
   symbol_get_bfdsym (symbolP)->flags |= BSF_OBJECT;
 
@@ -285,9 +669,9 @@ obj_mach_o_common_parse (int ignore ATTRIBUTE_UNUSED,
 }
 
 static void
-obj_mach_o_comm (int ignore ATTRIBUTE_UNUSED)
+obj_mach_o_comm (int is_local)
 {
-  s_comm_internal (ignore, obj_mach_o_common_parse);
+  s_comm_internal (is_local, obj_mach_o_common_parse);
 }
 
 static void
@@ -297,13 +681,101 @@ obj_mach_o_subsections_via_symbols (int arg ATTRIBUTE_UNUSED)
   demand_empty_rest_of_line ();
 }
 
+/* Dummy function to allow test-code to work while we are working
+   on things.  */
+
+static void
+obj_mach_o_placeholder (int arg ATTRIBUTE_UNUSED)
+{
+  ignore_rest_of_line ();
+}
+
 const pseudo_typeS mach_o_pseudo_table[] =
 {
-  { "weak", obj_mach_o_weak, 0},
-  { "section", obj_mach_o_section, 0},
-  { "cstring", obj_mach_o_known_section, 1},
-  { "lcomm", s_lcomm, 1 },
+  /* Section directives.  */
   { "comm", obj_mach_o_comm, 0 },
+  { "lcomm", obj_mach_o_comm, 1 },
+
+  { "text", obj_mach_o_base_section, 1},
+  { "data", obj_mach_o_base_section, 2},
+  { "bss", obj_mach_o_base_section, 3},   /* extension */
+
+  { "const", obj_mach_o_known_section, 1},
+  { "static_const", obj_mach_o_known_section, 2},
+  { "cstring", obj_mach_o_known_section, 3},
+  { "literal4", obj_mach_o_known_section, 4},
+  { "literal8", obj_mach_o_known_section, 5},
+  { "literal16", obj_mach_o_known_section, 6},
+  { "constructor", obj_mach_o_known_section, 7},
+  { "destructor", obj_mach_o_known_section, 8},
+  { "eh_frame", obj_mach_o_known_section, 9},
+
+  { "const_data", obj_mach_o_known_section, 10},
+  { "static_data", obj_mach_o_known_section, 11},
+  { "mod_init_func", obj_mach_o_known_section, 12},
+  { "mod_term_func", obj_mach_o_known_section, 13},
+  { "dyld", obj_mach_o_known_section, 14},
+  { "cfstring", obj_mach_o_known_section, 15},
+
+  { "objc_class", obj_mach_o_objc_section, 1},
+  { "objc_meta_class", obj_mach_o_objc_section, 2},
+  { "objc_cat_cls_meth", obj_mach_o_objc_section, 3},
+  { "objc_cat_inst_meth", obj_mach_o_objc_section, 4},
+  { "objc_protocol", obj_mach_o_objc_section, 5},
+  { "objc_string_object", obj_mach_o_objc_section, 6},
+  { "objc_cls_meth", obj_mach_o_objc_section, 7},
+  { "objc_inst_meth", obj_mach_o_objc_section, 8},
+  { "objc_cls_refs", obj_mach_o_objc_section, 9},
+  { "objc_message_refs", obj_mach_o_objc_section, 10},
+  { "objc_symbols", obj_mach_o_objc_section, 11},
+  { "objc_category", obj_mach_o_objc_section, 12},
+  { "objc_class_vars", obj_mach_o_objc_section, 13},
+  { "objc_instance_vars", obj_mach_o_objc_section, 14},
+  { "objc_module_info", obj_mach_o_objc_section, 15},
+  { "objc_class_names", obj_mach_o_objc_section, 16}, /* Alias for .cstring */
+  { "objc_meth_var_types", obj_mach_o_objc_section, 17}, /* Alias for .cstring */
+  { "objc_meth_var_names", obj_mach_o_objc_section, 18}, /* Alias for .cstring */
+  { "objc_selector_strs", obj_mach_o_objc_section, 19},
+  { "objc_image_info", obj_mach_o_objc_section, 20}, /* extension.  */
+  { "objc_selector_fixup", obj_mach_o_objc_section, 21}, /* extension.  */
+  { "objc1_class_ext", obj_mach_o_objc_section, 22}, /* ObjC-1 extension.  */
+  { "objc1_property_list", obj_mach_o_objc_section, 23}, /* ObjC-1 extension.  */
+  { "objc1_protocol_ext", obj_mach_o_objc_section, 24}, /* ObjC-1 extension.  */
+
+  { "debug_frame", obj_mach_o_debug_section, 1}, /* extension.  */
+  { "debug_info", obj_mach_o_debug_section, 2}, /* extension.  */
+  { "debug_abbrev", obj_mach_o_debug_section, 3}, /* extension.  */
+  { "debug_aranges", obj_mach_o_debug_section, 4}, /* extension.  */
+  { "debug_macinfo", obj_mach_o_debug_section, 5}, /* extension.  */
+  { "debug_line", obj_mach_o_debug_section, 6}, /* extension.  */
+  { "debug_loc", obj_mach_o_debug_section, 7}, /* extension.  */
+  { "debug_pubnames", obj_mach_o_debug_section, 8}, /* extension.  */
+  { "debug_pubtypes", obj_mach_o_debug_section, 9}, /* extension.  */
+  { "debug_str", obj_mach_o_debug_section, 10}, /* extension.  */
+  { "debug_ranges", obj_mach_o_debug_section, 11}, /* extension.  */
+  { "debug_macro", obj_mach_o_debug_section, 12}, /* extension.  */
+  
+  { "lazy_symbol_pointer", obj_mach_o_opt_tgt_section, 1},
+  { "lazy_symbol_pointer2", obj_mach_o_opt_tgt_section, 2}, /* extension.  */
+  { "lazy_symbol_pointer3", obj_mach_o_opt_tgt_section, 3}, /* extension.  */
+  { "non_lazy_symbol_pointer", obj_mach_o_opt_tgt_section, 4},
+  { "non_lazy_symbol_pointer_x86", obj_mach_o_opt_tgt_section, 5}, /* extension.  */
+  { "symbol_stub", obj_mach_o_opt_tgt_section, 6},
+  { "symbol_stub1", obj_mach_o_opt_tgt_section, 7}, /* extension.  */
+  { "picsymbol_stub", obj_mach_o_opt_tgt_section, 8}, /* extension.  */
+  { "picsymbol_stub1", obj_mach_o_opt_tgt_section, 9}, /* extension.  */
+  { "picsymbol_stub2", obj_mach_o_opt_tgt_section, 4}, /* extension.  */
+  { "picsymbol_stub3", obj_mach_o_opt_tgt_section, 4}, /* extension.  */
+
+  { "section", obj_mach_o_section, 0},
+
+  /* Symbol-related.  */
+  { "indirect_symbol", obj_mach_o_placeholder, 0},
+  { "weak_definition", obj_mach_o_placeholder, 0},
+  { "private_extern", obj_mach_o_placeholder, 0},
+  { "weak", obj_mach_o_weak, 0},   /* extension */
+
+  /* File flags.  */
   { "subsections_via_symbols", obj_mach_o_subsections_via_symbols, 0 },
 
   {NULL, NULL, 0}