Support NEXT_SECTION in ALIGNOF and SIZEOF

This patch is aimed at making __bss_start properly aligned with the
first of any bss-style sections following.  Most of the work here
involves keeping track of the last output section seen when processing
the linker script.

You can almost align __bss_start properly by using
${RELOCATING+. = ALIGN(${DATA_SDATA-${NO_SMALL_DATA-ALIGNOF(.${SBSS_NAME}) != 0 ? ALIGNOF(.${SBSS_NAME}) : }}${BSS_PLT+ALIGNOF(.plt) != 0 ? ALIGNOF(.plt) : }ALIGNOF(.${BSS_NAME}));}
and changing every place that defines NO_SMALL_DATA to use " ", but
having two .plt sections (marked SPECIAL) on some backends foils that
idea.  The problem is that you only want to pick up the following
.plt, not the one preceeding __bss_start in the data segment if the
backend decides that is the proper .plt section.

Perhaps that could be fixed too, but I decided instead to extend the
linker script a little.  THIS_SECTION and PREV_SECTION could easily be
added too.

	* ld.texi (ALIGNOF, SIZEOF): Update and mention NEXT_SECTION.
	* ldexp.c (output_section_find): New function.
	(fold_name <ALIGNOF, SIZEOF>): Use output_section_find.
	(exp_fold_tree): Add os parameter.  Adjust all calls.
	(exp_fold_tree_no_dot, exp_get_vma, exp_get_power): Likewise.
	* ldexp.h (struct ldexp_control): Add last_os.
	(exp_fold_tree, exp_fold_tree_no_dot): Update prototypes.
	(exp_get_vma, exp_get_power): Likewise.
	* ldlang.c: Pass last output section to expression folder
	calls throughout file.
	(open_input_bfds): Add os parameter to track last os seen.
	(lang_size_sections_1): Rename output_section_statement param
	to current_os.  Track last os.
	(lang_do_assignments_1): Track last os.
	* scripttempl/arclinux.sc: Align to ALIGNOF NEXT_SECTION
	before defining __bss_start.
	* scripttempl/elf.sc: Likewise.
	* scripttempl/elf64bpf.sc: Likewise.
	* scripttempl/elf64hppa.sc: Likewise.
	* scripttempl/elf_chaos.sc: Likewise.
	* scripttempl/elfarc.sc: Likewise.
	* scripttempl/elfd10v.sc: Likewise.
	* scripttempl/elfxtensa.sc: Likewise.
	* scripttempl/epiphany_4x4.sc: Likewise.
	* scripttempl/iq2000.sc: Likewise.
	* scripttempl/mep.sc: Likewise.
	* scripttempl/nds32elf.sc: Likewise.
	* scripttempl/xstormy16.sc: Likewise.
	* testsuite/ld-x86-64/pe-x86-64-5.od: Update expected __bss_start.
	* testsuite/ld-x86-64/pe-x86-64-5.rd: Likewise.

ld/ldlang.c

@@ -2433,7 +2433,7 @@ init_os (lang_output_section_statement_type *s, flagword flags)
 
   /* If supplied an alignment, set it.  */
   if (s->section_alignment != NULL)
-    s->bfd_section->alignment_power = exp_get_power (s->section_alignment,
+    s->bfd_section->alignment_power = exp_get_power (s->section_alignment, s,
 						     "section alignment");
 }
 
@@ -3488,17 +3488,20 @@ static struct bfd_link_hash_entry *plugin_undefs = NULL;
 #endif
 
 static void
-open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
+open_input_bfds (lang_statement_union_type *s,
+		 lang_output_section_statement_type *os,
+		 enum open_bfd_mode mode)
 {
   for (; s != NULL; s = s->header.next)
     {
       switch (s->header.type)
 	{
 	case lang_constructors_statement_enum:
-	  open_input_bfds (constructor_list.head, mode);
+	  open_input_bfds (constructor_list.head, os, mode);
 	  break;
 	case lang_output_section_statement_enum:
-	  open_input_bfds (s->output_section_statement.children.head, mode);
+	  os = &s->output_section_statement;
+	  open_input_bfds (os->children.head, os, mode);
 	  break;
 	case lang_wild_statement_enum:
 	  /* Maybe we should load the file's symbols.  */
@@ -3507,7 +3510,7 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 	      && !wildcardp (s->wild_statement.filename)
 	      && !archive_path (s->wild_statement.filename))
 	    lookup_name (s->wild_statement.filename);
-	  open_input_bfds (s->wild_statement.children.head, mode);
+	  open_input_bfds (s->wild_statement.children.head, os, mode);
 	  break;
 	case lang_group_statement_enum:
 	  {
@@ -3526,7 +3529,7 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 		plugin_insert_save = plugin_insert;
 #endif
 		undefs = link_info.hash->undefs_tail;
-		open_input_bfds (s->group_statement.children.head,
+		open_input_bfds (s->group_statement.children.head, os,
 				 mode | OPEN_BFD_FORCE);
 	      }
 	    while (undefs != link_info.hash->undefs_tail
@@ -3613,7 +3616,7 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 	  break;
 	case lang_assignment_statement_enum:
 	  if (s->assignment_statement.exp->type.node_class != etree_assert)
-	    exp_fold_tree_no_dot (s->assignment_statement.exp);
+	    exp_fold_tree_no_dot (s->assignment_statement.exp, os);
 	  break;
 	default:
 	  break;
@@ -4221,7 +4224,7 @@ map_input_to_output_sections
 		}
 	     else
 	       {
-		 exp_fold_tree_no_dot (os->sectype_value);
+		 exp_fold_tree_no_dot (os->sectype_value, os);
 		 if (expld.result.valid_p)
 		   type = expld.result.value;
 		 else
@@ -4648,6 +4651,7 @@ print_output_section_statement
 
 	  if (output_section_statement->update_dot_tree != NULL)
 	    exp_fold_tree (output_section_statement->update_dot_tree,
+			   output_section_statement,
 			   bfd_abs_section_ptr, &print_dot);
 	}
 
@@ -4686,7 +4690,7 @@ print_assignment (lang_assignment_statement_type *assignment,
     osec = bfd_abs_section_ptr;
 
   if (assignment->exp->type.node_class != etree_provide)
-    exp_fold_tree (tree, osec, &print_dot);
+    exp_fold_tree (tree, output_section, osec, &print_dot);
   else
     expld.result.valid_p = false;
 
@@ -5417,6 +5421,7 @@ size_input_section
       if (output_section_statement->subsection_alignment != NULL)
 	i->alignment_power
 	  = exp_get_power (output_section_statement->subsection_alignment,
+			   output_section_statement,
 			   "subsection alignment");
 
       if (o->alignment_power < i->alignment_power)
@@ -5755,7 +5760,7 @@ ldlang_check_relro_region (lang_statement_union_type *s)
 static bfd_vma
 lang_size_sections_1
   (lang_statement_union_type **prev,
-   lang_output_section_statement_type *output_section_statement,
+   lang_output_section_statement_type *current_os,
    fill_type *fill,
    bfd_vma dot,
    bool *relax,
@@ -5764,6 +5769,7 @@ lang_size_sections_1
   lang_statement_union_type *s;
   lang_statement_union_type *prev_s = NULL;
   bool removed_prev_s = false;
+  lang_output_section_statement_type *os = current_os;
 
   /* Size up the sections from their constituent parts.  */
   for (s = *prev; s != NULL; prev_s = s, s = s->header.next)
@@ -5775,7 +5781,6 @@ lang_size_sections_1
 	case lang_output_section_statement_enum:
 	  {
 	    bfd_vma newdot, after, dotdelta;
-	    lang_output_section_statement_type *os;
 	    lang_memory_region_type *r;
 	    int section_alignment = 0;
 
@@ -5794,7 +5799,7 @@ lang_size_sections_1
 	      os->addr_tree = exp_intop (0);
 	    if (os->addr_tree != NULL)
 	      {
-		exp_fold_tree (os->addr_tree, bfd_abs_section_ptr, &dot);
+		exp_fold_tree (os->addr_tree, os, bfd_abs_section_ptr, &dot);
 
 		if (expld.result.valid_p)
 		  {
@@ -5899,7 +5904,7 @@ lang_size_sections_1
 		    section_alignment = os->bfd_section->alignment_power;
 		  }
 		else
-		  section_alignment = exp_get_power (os->section_alignment,
+		  section_alignment = exp_get_power (os->section_alignment, os,
 						     "section alignment");
 
 		/* Align to what the section needs.  */
@@ -5987,6 +5992,7 @@ lang_size_sections_1
 		       statement.  */
 		    if (os->lma_region != os->region)
 		      section_alignment = exp_get_power (os->section_alignment,
+							 os,
 							 "section alignment");
 		    if (section_alignment > 0)
 		      lma = align_power (lma, section_alignment);
@@ -6076,7 +6082,7 @@ lang_size_sections_1
 	    dot += dotdelta;
 
 	    if (os->update_dot_tree != 0)
-	      exp_fold_tree (os->update_dot_tree, bfd_abs_section_ptr, &dot);
+	      exp_fold_tree (os->update_dot_tree, os, bfd_abs_section_ptr, &dot);
 
 	    /* Update dot in the region ?
 	       We only do this if the section is going to be allocated,
@@ -6107,8 +6113,7 @@ lang_size_sections_1
 	  break;
 
 	case lang_constructors_statement_enum:
-	  dot = lang_size_sections_1 (&constructor_list.head,
-				      output_section_statement,
+	  dot = lang_size_sections_1 (&constructor_list.head, current_os,
 				      fill, dot, relax, check_regions);
 	  break;
 
@@ -6116,14 +6121,13 @@ lang_size_sections_1
 	  {
 	    unsigned int size = 0;
 
-	    s->data_statement.output_offset =
-	      dot - output_section_statement->bfd_section->vma;
-	    s->data_statement.output_section =
-	      output_section_statement->bfd_section;
+	    s->data_statement.output_offset = dot - current_os->bfd_section->vma;
+	    s->data_statement.output_section = current_os->bfd_section;
 
 	    /* We might refer to provided symbols in the expression, and
 	       need to mark them as needed.  */
-	    exp_fold_tree (s->data_statement.exp, bfd_abs_section_ptr, &dot);
+	    exp_fold_tree (s->data_statement.exp, os,
+			   bfd_abs_section_ptr, &dot);
 
 	    switch (s->data_statement.type)
 	      {
@@ -6146,10 +6150,9 @@ lang_size_sections_1
 	    if (size < TO_SIZE ((unsigned) 1))
 	      size = TO_SIZE ((unsigned) 1);
 	    dot += TO_ADDR (size);
-	    if (!(output_section_statement->bfd_section->flags
-		  & SEC_FIXED_SIZE))
-	      output_section_statement->bfd_section->size
-		= TO_SIZE (dot - output_section_statement->bfd_section->vma);
+	    if (!(current_os->bfd_section->flags & SEC_FIXED_SIZE))
+	      current_os->bfd_section->size
+		= TO_SIZE (dot - current_os->bfd_section->vma);
 
 	  }
 	  break;
@@ -6158,29 +6161,27 @@ lang_size_sections_1
 	  {
 	    int size;
 
-	    s->reloc_statement.output_offset =
-	      dot - output_section_statement->bfd_section->vma;
-	    s->reloc_statement.output_section =
-	      output_section_statement->bfd_section;
+	    s->reloc_statement.output_offset
+	      = dot - current_os->bfd_section->vma;
+	    s->reloc_statement.output_section
+	      = current_os->bfd_section;
 	    size = bfd_get_reloc_size (s->reloc_statement.howto);
 	    dot += TO_ADDR (size);
-	    if (!(output_section_statement->bfd_section->flags
-		  & SEC_FIXED_SIZE))
-	      output_section_statement->bfd_section->size
-		= TO_SIZE (dot - output_section_statement->bfd_section->vma);
+	    if (!(current_os->bfd_section->flags & SEC_FIXED_SIZE))
+	      current_os->bfd_section->size
+		= TO_SIZE (dot - current_os->bfd_section->vma);
 	  }
 	  break;
 
 	case lang_wild_statement_enum:
 	  dot = lang_size_sections_1 (&s->wild_statement.children.head,
-				      output_section_statement,
-				      fill, dot, relax, check_regions);
+				      current_os, fill, dot, relax,
+				      check_regions);
 	  break;
 
 	case lang_object_symbols_statement_enum:
-	  link_info.create_object_symbols_section
-	    = output_section_statement->bfd_section;
-	  output_section_statement->bfd_section->flags |= SEC_KEEP;
+	  link_info.create_object_symbols_section = current_os->bfd_section;
+	  current_os->bfd_section->flags |= SEC_KEEP;
 	  break;
 
 	case lang_output_statement_enum:
@@ -6201,8 +6202,7 @@ lang_size_sections_1
 		if (again)
 		  *relax = true;
 	      }
-	    dot = size_input_section (prev, output_section_statement,
-				      fill, &removed, dot);
+	    dot = size_input_section (prev, current_os, fill, &removed, dot);
 	  }
 	  break;
 
@@ -6210,8 +6210,7 @@ lang_size_sections_1
 	  break;
 
 	case lang_fill_statement_enum:
-	  s->fill_statement.output_section =
-	    output_section_statement->bfd_section;
+	  s->fill_statement.output_section = current_os->bfd_section;
 
 	  fill = s->fill_statement.fill;
 	  break;
@@ -6223,9 +6222,7 @@ lang_size_sections_1
 
 	    expld.dataseg.relro = exp_seg_relro_none;
 
-	    exp_fold_tree (tree,
-			   output_section_statement->bfd_section,
-			   &newdot);
+	    exp_fold_tree (tree, os, current_os->bfd_section, &newdot);
 
 	    ldlang_check_relro_region (s);
 
@@ -6236,11 +6233,11 @@ lang_size_sections_1
 		 || tree->type.node_class == etree_assign)
 		&& (tree->assign.dst [0] != '.'
 		    || tree->assign.dst [1] != '\0'))
-	      output_section_statement->update_dot = 1;
+	      current_os->update_dot = 1;
 
-	    if (!output_section_statement->ignored)
+	    if (!current_os->ignored)
 	      {
-		if (output_section_statement == abs_output_section)
+		if (current_os == abs_output_section)
 		  {
 		    /* If we don't have an output section, then just adjust
 		       the default memory address.  */
@@ -6253,7 +6250,7 @@ lang_size_sections_1
 		       put the pad before when relaxing, in case the
 		       assignment references dot.  */
 		    insert_pad (&s->header.next, fill, TO_SIZE (newdot - dot),
-				output_section_statement->bfd_section, dot);
+				current_os->bfd_section, dot);
 
 		    /* Don't neuter the pad below when relaxing.  */
 		    s = s->header.next;
@@ -6262,11 +6259,11 @@ lang_size_sections_1
 		       should have space allocated to it, unless the
 		       user has explicitly stated that the section
 		       should not be allocated.  */
-		    if (output_section_statement->sectype != noalloc_section
-			&& (output_section_statement->sectype != noload_section
+		    if (current_os->sectype != noalloc_section
+			&& (current_os->sectype != noload_section
 			    || (bfd_get_flavour (link_info.output_bfd)
 				== bfd_target_elf_flavour)))
-		      output_section_statement->bfd_section->flags |= SEC_ALLOC;
+		      current_os->bfd_section->flags |= SEC_ALLOC;
 		  }
 		dot = newdot;
 	      }
@@ -6287,13 +6284,13 @@ lang_size_sections_1
 	     section.  bfd_set_section_contents will complain even for
 	     a pad size of zero.  */
 	  s->padding_statement.output_offset
-	    = dot - output_section_statement->bfd_section->vma;
+	    = dot - current_os->bfd_section->vma;
 	  break;
 
 	case lang_group_statement_enum:
 	  dot = lang_size_sections_1 (&s->group_statement.children.head,
-				      output_section_statement,
-				      fill, dot, relax, check_regions);
+				      current_os, fill, dot, relax,
+				      check_regions);
 	  break;
 
 	case lang_insert_statement_enum:
@@ -6540,6 +6537,8 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 		       bfd_vma dot,
 		       bool *found_end)
 {
+  lang_output_section_statement_type *os = current_os;
+
   for (; s != NULL; s = s->header.next)
     {
       switch (s->header.type)
@@ -6551,10 +6550,9 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 
 	case lang_output_section_statement_enum:
 	  {
-	    lang_output_section_statement_type *os;
 	    bfd_vma newdot;
 
-	    os = &(s->output_section_statement);
+	    os = &s->output_section_statement;
 	    os->after_end = *found_end;
 	    init_opb (os->bfd_section);
 	    newdot = dot;
@@ -6581,7 +6579,7 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 		      newdot += TO_ADDR (os->bfd_section->size);
 
 		    if (os->update_dot_tree != NULL)
-		      exp_fold_tree (os->update_dot_tree,
+		      exp_fold_tree (os->update_dot_tree, os,
 				     bfd_abs_section_ptr, &newdot);
 		  }
 		dot = newdot;
@@ -6601,7 +6599,7 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 	  break;
 
 	case lang_data_statement_enum:
-	  exp_fold_tree (s->data_statement.exp, bfd_abs_section_ptr, &dot);
+	  exp_fold_tree (s->data_statement.exp, os, bfd_abs_section_ptr, &dot);
 	  if (expld.result.valid_p)
 	    {
 	      s->data_statement.value = expld.result.value;
@@ -6637,7 +6635,7 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 	  break;
 
 	case lang_reloc_statement_enum:
-	  exp_fold_tree (s->reloc_statement.addend_exp,
+	  exp_fold_tree (s->reloc_statement.addend_exp, os,
 			 bfd_abs_section_ptr, &dot);
 	  if (expld.result.valid_p)
 	    s->reloc_statement.addend_value = expld.result.value;
@@ -6676,7 +6674,7 @@ lang_do_assignments_1 (lang_statement_union_type *s,
 	      if (strcmp (p, "end") == 0)
 		*found_end = true;
 	    }
-	  exp_fold_tree (s->assignment_statement.exp,
+	  exp_fold_tree (s->assignment_statement.exp, os,
 			 (current_os->bfd_section != NULL
 			  ? current_os->bfd_section : bfd_und_section_ptr),
 			 &dot);
@@ -8106,7 +8104,7 @@ lang_process (void)
   /* Create a bfd for each input file.  */
   current_target = default_target;
   lang_statement_iteration++;
-  open_input_bfds (statement_list.head, OPEN_BFD_NORMAL);
+  open_input_bfds (statement_list.head, NULL, OPEN_BFD_NORMAL);
 
   /* Now that open_input_bfds has processed assignments and provide
      statements we can give values to symbolic origin/length now.  */
@@ -8136,7 +8134,12 @@ lang_process (void)
       link_info.lto_all_symbols_read = true;
       /* Open any newly added files, updating the file chains.  */
       plugin_undefs = link_info.hash->undefs_tail;
-      open_input_bfds (*added.tail, OPEN_BFD_NORMAL);
+      lang_output_section_statement_type *last_os = NULL;
+      if (lang_os_list.head != NULL)
+	last_os = ((lang_output_section_statement_type *)
+		   ((char *) lang_os_list.tail
+		    - offsetof (lang_output_section_statement_type, next)));
+      open_input_bfds (*added.tail, last_os, OPEN_BFD_NORMAL);
       if (plugin_undefs == link_info.hash->undefs_tail)
 	plugin_undefs = NULL;
       /* Restore the global list pointer now they have all been added.  */
@@ -8187,7 +8190,7 @@ lang_process (void)
 	  /* Rescan archives in case new undefined symbols have appeared.  */
 	  files = file_chain;
 	  lang_statement_iteration++;
-	  open_input_bfds (statement_list.head, OPEN_BFD_RESCAN);
+	  open_input_bfds (statement_list.head, NULL, OPEN_BFD_RESCAN);
 	  lang_list_remove_tail (&file_chain, &files);
 	  while (files.head != NULL)
 	    {
@@ -8842,7 +8845,7 @@ lang_new_phdr (const char *name,
   n = stat_alloc (sizeof (struct lang_phdr));
   n->next = NULL;
   n->name = name;
-  n->type = exp_get_vma (type, 0, "program header type");
+  n->type = exp_get_vma (type, NULL, 0, "program header type");
   n->filehdr = filehdr;
   n->phdrs = phdrs;
   n->at = at;
@@ -8956,12 +8959,12 @@ lang_record_phdrs (void)
       if (l->flags == NULL)
 	flags = 0;
       else
-	flags = exp_get_vma (l->flags, 0, "phdr flags");
+	flags = exp_get_vma (l->flags, NULL, 0, "phdr flags");
 
       if (l->at == NULL)
 	at = 0;
       else
-	at = exp_get_vma (l->at, 0, "phdr load address");
+	at = exp_get_vma (l->at, NULL, 0, "phdr load address");
 
       if (!bfd_record_phdr (link_info.output_bfd, l->type,
 			    l->flags != NULL, flags, l->at != NULL,
@@ -9721,7 +9724,7 @@ lang_do_memory_regions (bool update_regions_p)
     {
       if (r->origin_exp)
 	{
-	  exp_fold_tree_no_dot (r->origin_exp);
+	  exp_fold_tree_no_dot (r->origin_exp, NULL);
           if (update_regions_p)
             {
               if (expld.result.valid_p)
@@ -9736,7 +9739,7 @@ lang_do_memory_regions (bool update_regions_p)
 	}
       if (r->length_exp)
 	{
-	  exp_fold_tree_no_dot (r->length_exp);
+	  exp_fold_tree_no_dot (r->length_exp, NULL);
           if (update_regions_p)
             {
               if (expld.result.valid_p)