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.

1 files changed, 33 insertions, 10 deletions

diff --git a/ld/ldexp.c b/ld/ldexp.c
index 170e1ed..8b9d6dc 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -691,6 +691,24 @@ fold_trinary (etree_type *tree)
 		     : tree->trinary.rhs);
 }
 
+static lang_output_section_statement_type *
+output_section_find (const char *name)
+{
+  lang_output_section_statement_type *os = lang_output_section_find (name);
+
+  if (os == NULL && strcmp (name, "NEXT_SECTION") == 0)
+    {
+      os = expld.last_os;
+      if (os != NULL)
+	while ((os = os->next) != NULL)
+	  if (os->constraint >= 0 && os->bfd_section != NULL)
+	    break;
+      if (os == NULL)
+	os = abs_output_section;
+    }
+  return os;
+}
+
 static void
 fold_name (etree_type *tree)
 {
@@ -850,7 +868,7 @@ fold_name (etree_type *tree)
 	{
 	  lang_output_section_statement_type *os;
 
-	  os = lang_output_section_find (tree->name.name);
+	  os = output_section_find (tree->name.name);
 	  if (os == NULL)
 	    {
 	      if (expld.phase == lang_final_phase_enum)
@@ -1270,29 +1288,32 @@ exp_fold_tree_1 (etree_type *tree)
 }
 
 void
-exp_fold_tree (etree_type *tree, asection *current_section, bfd_vma *dotp)
+exp_fold_tree (etree_type *tree, lang_output_section_statement_type *os,
+	       asection *current_section, bfd_vma *dotp)
 {
   expld.rel_from_abs = false;
   expld.dot = *dotp;
   expld.dotp = dotp;
   expld.section = current_section;
+  expld.last_os = os;
   exp_fold_tree_1 (tree);
 }
 
 void
-exp_fold_tree_no_dot (etree_type *tree)
+exp_fold_tree_no_dot (etree_type *tree, lang_output_section_statement_type *os)
 {
   expld.rel_from_abs = false;
   expld.dot = 0;
   expld.dotp = NULL;
   expld.section = bfd_abs_section_ptr;
+  expld.last_os = os;
   exp_fold_tree_1 (tree);
 }
 
 static void
 exp_value_fold (etree_type *tree)
 {
-  exp_fold_tree_no_dot (tree);
+  exp_fold_tree_no_dot (tree, NULL);
   if (expld.result.valid_p)
     {
       tree->type.node_code = INT;
@@ -1547,11 +1568,12 @@ exp_print_tree (etree_type *tree)
 }
 
 bfd_vma
-exp_get_vma (etree_type *tree, bfd_vma def, char *name)
+exp_get_vma (etree_type *tree, lang_output_section_statement_type *os,
+	     bfd_vma def, char *name)
 {
   if (tree != NULL)
     {
-      exp_fold_tree_no_dot (tree);
+      exp_fold_tree_no_dot (tree, os);
       if (expld.result.valid_p)
 	return expld.result.value;
       else if (name != NULL && expld.phase != lang_mark_phase_enum)
@@ -1567,9 +1589,10 @@ exp_get_vma (etree_type *tree, bfd_vma def, char *name)
    NULL or cannot be resolved, return -1.  */
 
 int
-exp_get_power (etree_type *tree, char *name)
+exp_get_power (etree_type *tree, lang_output_section_statement_type *os,
+	       char *name)
 {
-  bfd_vma x = exp_get_vma (tree, -1, name);
+  bfd_vma x = exp_get_vma (tree, os, -1, name);
   bfd_vma p2;
   int n;
 
@@ -1593,7 +1616,7 @@ exp_get_fill (etree_type *tree, fill_type *def, char *name)
   if (tree == NULL)
     return def;
 
-  exp_fold_tree_no_dot (tree);
+  exp_fold_tree_no_dot (tree, NULL);
   if (!expld.result.valid_p)
     {
       if (name != NULL && expld.phase != lang_mark_phase_enum)
@@ -1647,7 +1670,7 @@ exp_get_abs_int (etree_type *tree, int def, char *name)
 {
   if (tree != NULL)
     {
-      exp_fold_tree_no_dot (tree);
+      exp_fold_tree_no_dot (tree, NULL);
 
       if (expld.result.valid_p)
 	{