Rewrite __start and __stop symbol handling

This arranges for __start and __stop symbols to be defined before
garbage collection, for all target formats.  That should allow the
COFF and PE --gc-sections to keep a singleton orphan input section,
a feature lost by 2017-06-13 commit cbd0eecf26.  The fancier ELF
treatment of keeping all input sections associated with a __start or
__stop symbol, from 2015-10-23 commit 1cce69b9dc, is retained.

.startof. and .sizeof. symbols are deliberately not defined before
garbage collection, so these won't affect garbage collection of
sections.

The patch also ensures __start, __stop, .startof. and .sizeof. symbols
are defined before target size_dynamic_sections is called, albeit
with a preliminary value, so that target code doesn't need to cope
with a symbol changing from undefined at size_dynamic_sections to
defined at relocate_section.

Also, a number of problems with the testcases have been fixed.

	PR ld/20022
	PR ld/21557
	PR ld/21562
	PR ld/21571
include/
	* bfdlink.h (struct bfd_link_hash_entry): Delete undef.section.
bfd/
	* targets.c (struct bfd_target): Add _bfd_define_start_stop.
	(BFD_JUMP_TABLE_LINK): Likewise.
	* elf-bfd.h (bfd_elf_define_start_stop): Declare.
	* elflink.c (_bfd_elf_gc_mark_rsec): Update comment.
	(bfd_elf_define_start_stop): New function.
	* linker.c (bfd_generic_define_start_stop): New function.
	* coff64-rs6000.c (rs6000_xcoff64_vec, rs6000_xcoff64_aix_vec): Init
	new field.
	* aout-adobe.c (aout_32_bfd_define_start_stop): Define.
	* aout-target.h (MY_bfd_define_start_stop): Define.
	* aout-tic30.c (MY_bfd_define_start_stop): Define.
	* binary.c (binary_bfd_define_start_stop): Define.
	* bout.c (b_out_bfd_define_start_stop): Define.
	* coff-alpha.c (_bfd_ecoff_bfd_define_start_stop): Define.
	* coff-mips.c (_bfd_ecoff_bfd_define_start_stop): Define.
	* coff-rs6000.c (_bfd_xcoff_bfd_define_start_stop): Define.
	* coffcode.h (coff_bfd_define_start_stop): Define.
	* elfxx-target.h (bfd_elfNN_bfd_define_start_stop): Define.
	* i386msdos.c (msdos_bfd_define_start_stop): Define.
	* i386os9k.c (os9k_bfd_define_start_stop): Define.
	* ieee.c (ieee_bfd_define_start_stop): Define.
	* ihex.c (ihex_bfd_define_start_stop): Define.
	* libbfd-in.h (_bfd_nolink_bfd_define_start_stop): Define.
	* mach-o-target.c (bfd_mach_o_bfd_define_start_stop): Define.
	* mmo.c (mmo_bfd_define_start_stop): Define.
	* nlm-target.h (nlm_bfd_define_start_stop): Define.
	* oasys.c (oasys_bfd_define_start_stop): Define.
	* pef.c (bfd_pef_bfd_define_start_stop): Define.
	* plugin.c (bfd_plugin_bfd_define_start_stop): Define.
	* ppcboot.c (ppcboot_bfd_define_start_stop): Define.
	* som.c (som_bfd_define_start_stop): Define.
	* srec.c (srec_bfd_define_start_stop): Define.
	* tekhex.c (tekhex_bfd_define_start_stop): Define.
	* versados.c (versados_bfd_define_start_stop): Define.
	* vms-alpha.c (vms_bfd_define_start_stop): Define.
	(alpha_vms_bfd_define_start_stop): Define.
	* xsym.c (bfd_sym_bfd_define_start_stop): Define.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.
ld/
	* emultempl/elf32.em (gld${EMULATION_NAME}_after_open): Don't set
	__start/__stop syms here.
	* ldlang.c (lang_set_startof): Delete.
	(start_stop_syms, start_stop_count, start_stop_alloc): New vars.
	(lang_define_start_stop, lang_init_start_stop, foreach_start_stop,
	undef_start_stop, lang_undef_start_stop, lang_init_startof_sizeof,
	set_start_stop, lang_finalize_start_stop): New functions.
	(lang_process): Call _start_stop functions.
	* testsuite/ld-elf/pr21562a.d: Use xfail rather than notarget.
	Correct typos and list of xfail targets.
	* testsuite/ld-elf/pr21562b.d: Likewise.
	* testsuite/ld-elf/pr21562c.d: Likewise.
	* testsuite/ld-elf/pr21562d.d: Likewise.
	* testsuite/ld-elf/pr21562e.d: Likewise.
	* testsuite/ld-elf/pr21562f.d: Likewise.
	* testsuite/ld-elf/pr21562g.d: Likewise.
	* testsuite/ld-elf/pr21562h.d: Likewise.
	* testsuite/ld-elf/pr21562i.d: Likewise.
	* testsuite/ld-elf/pr21562j.d: Likewise.
	* testsuite/ld-elf/pr21562k.d: Likewise.
	* testsuite/ld-elf/pr21562l.d: Likewise.
	* testsuite/ld-elf/pr21562m.d: Likewise.
	* testsuite/ld-elf/pr21562n.d: Likewise.
	* testsuite/ld-elf/sizeofa.d: Likewise.  Adjust to pass for generic ELF.
	* testsuite/ld-elf/sizeofb.d: Likewise.
	* testsuite/ld-elf/startofa.d: Likewise.
	* testsuite/ld-elf/startofb.d: Likewise.

1 files changed, 0 insertions, 57 deletions

diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index 9468f7d..325d847 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -1218,7 +1218,6 @@ gld${EMULATION_NAME}_after_open (void)
   struct elf_link_hash_table *htab;
   asection *s;
   bfd *abfd;
-  char leading_char;
 
   after_open_default ();
 
@@ -1277,62 +1276,6 @@ gld${EMULATION_NAME}_after_open (void)
       return;
     }
 
-  leading_char = bfd_get_symbol_leading_char (link_info.output_bfd);
-
-  /* Check for input sections whose names match references to
-     __start_SECNAME or __stop_SECNAME symbols.  Mark the matched
-     symbols as hidden and set start_stop for garbage collection.  */
-  for (abfd = link_info.input_bfds; abfd; abfd = abfd->link.next)
-    for (s = abfd->sections; s; s = s->next)
-      {
-	const char *name = bfd_get_section_name (abfd, s);
-	const char *ps;
-
-	for (ps = name; *ps != '\0'; ps++)
-	  if (!ISALNUM ((unsigned char) *ps) && *ps != '_')
-	    break;
-	if (*ps == '\0')
-	  {
-	    struct elf_link_hash_entry *h;
-	    char *symbol = (char *) xmalloc (ps - name
-					     + sizeof "__start_" + 1);
-
-	    symbol[0] = leading_char;
-	    sprintf (symbol + (leading_char != 0), "__start_%s", name);
-	    h = elf_link_hash_lookup (elf_hash_table (&link_info),
-				      symbol, FALSE, FALSE, TRUE);
-	    if (h != NULL
-		&& (h->root.type == bfd_link_hash_undefined
-		    || h->root.type == bfd_link_hash_undefweak)
-		&& h->u2.start_stop_section == NULL)
-	      {
-		h->start_stop = 1;
-		h->u2.start_stop_section = s;
-		_bfd_elf_link_hash_hide_symbol (&link_info, h, TRUE);
-		if (ELF_ST_VISIBILITY (h->other) != STV_INTERNAL)
-		  h->other = ((h->other & ~ELF_ST_VISIBILITY (-1))
-			      | STV_HIDDEN);
-	      }
-
-	    symbol[0] = leading_char;
-	    sprintf (symbol + (leading_char != 0), "__stop_%s", name);
-	    h = elf_link_hash_lookup (elf_hash_table (&link_info),
-				      symbol, FALSE, FALSE, TRUE);
-	    if (h != NULL
-		&& (h->root.type == bfd_link_hash_undefined
-		    || h->root.type == bfd_link_hash_undefweak)
-		&& h->u2.start_stop_section == NULL)
-	      {
-		h->start_stop = 1;
-		h->u2.start_stop_section = s;
-		_bfd_elf_link_hash_hide_symbol (&link_info, h, TRUE);
-		if (ELF_ST_VISIBILITY (h->other) != STV_INTERNAL)
-		  h->other = ((h->other & ~ELF_ST_VISIBILITY (-1))
-			      | STV_HIDDEN);
-	      }
-	  }
-      }
-
   if (!link_info.traditional_format)
     {
       bfd *elfbfd = NULL;