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Re: ld: can not edit opd Bad value with --gc-sections


On Sat, Oct 22, 2005 at 04:08:50PM +0200, Olaf Hering wrote:
> something broke gcc -Wl,--gc-sections recently.

It was over-enthusiastic error checking in dec_dynrel_count.  When
looking at this problem, I noticed that I didn't heed NO_OPD_RELOCS.
Also, we shouldn't complain about .opd or .toc relocs against symbols
from discarded sections (which we can get with --gc-sections or linker
script /DISCARD/ in combination with --no-opd-optimize
--no-toc-optimize).

	* elf64-ppc.c (dec_dynrel_count): Don't report errors for local
	syms in gc'd sections.
	(ppc64_elf_edit_opd): Don't adjust reloc counts when NO_OPD_RELOCS.
	(elf_backend_action_discarded): Define.
	(ppc64_elf_action_discarded): New function.

Index: bfd/elf64-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf64-ppc.c,v
retrieving revision 1.223
diff -u -p -r1.223 elf64-ppc.c
--- bfd/elf64-ppc.c	6 Oct 2005 19:21:14 -0000	1.223
+++ bfd/elf64-ppc.c	23 Oct 2005 13:00:21 -0000
@@ -95,6 +95,7 @@ static bfd_vma opd_entry_value
 #define elf_backend_hide_symbol		      ppc64_elf_hide_symbol
 #define elf_backend_always_size_sections      ppc64_elf_func_desc_adjust
 #define elf_backend_size_dynamic_sections     ppc64_elf_size_dynamic_sections
+#define elf_backend_action_discarded	      ppc64_elf_action_discarded
 #define elf_backend_relocate_section	      ppc64_elf_relocate_section
 #define elf_backend_finish_dynamic_symbol     ppc64_elf_finish_dynamic_symbol
 #define elf_backend_reloc_type_class	      ppc64_elf_reloc_type_class
@@ -6120,15 +6121,24 @@ dec_dynrel_count (bfd_vma r_info,
 
   if (h != NULL)
     pp = &((struct ppc_link_hash_entry *) h)->dyn_relocs;
-  else if (sym_sec != NULL)
-    {
-      void *vpp = &elf_section_data (sym_sec)->local_dynrel;
-      pp = (struct ppc_dyn_relocs **) vpp;
-    }
   else
     {
-      void *vpp = &elf_section_data (sec)->local_dynrel;
-      pp = (struct ppc_dyn_relocs **) vpp;
+      if (sym_sec != NULL)
+	{
+	  void *vpp = &elf_section_data (sym_sec)->local_dynrel;
+	  pp = (struct ppc_dyn_relocs **) vpp;
+	}
+      else
+	{
+	  void *vpp = &elf_section_data (sec)->local_dynrel;
+	  pp = (struct ppc_dyn_relocs **) vpp;
+	}
+
+      /* elf_gc_sweep may have already removed all dyn relocs associated
+	 with local syms for a given section.  Don't report a dynreloc
+	 miscount.  */
+      if (*pp == NULL)
+	return TRUE;
     }
 
   while ((p = *pp) != NULL)
@@ -6476,7 +6486,8 @@ ppc64_elf_edit_opd (bfd *obfd, struct bf
 
 	      if (skip)
 		{
-		  if (!info->relocatable
+		  if (!NO_OPD_RELOCS
+		      && !info->relocatable
 		      && !dec_dynrel_count (rel->r_info, sec, info,
 					    NULL, h, sym_sec))
 		    goto error_ret;
@@ -9454,6 +9465,21 @@ ppc64_elf_restore_symbols (struct bfd_li
   elf_link_hash_traverse (&htab->elf, undo_symbol_twiddle, info);
 }
 
+/* What to do when ld finds relocations against symbols defined in
+   discarded sections.  */
+
+static unsigned int
+ppc64_elf_action_discarded (asection *sec)
+{
+  if (strcmp (".opd", sec->name) == 0)
+    return 0;
+
+  if (strcmp (".toc", sec->name) == 0)
+    return 0;
+
+  return _bfd_elf_default_action_discarded (sec);
+}
+
 /* The RELOCATE_SECTION function is called by the ELF backend linker
    to handle the relocations for a section.
 
-- 
Alan Modra
IBM OzLabs - Linux Technology Centre


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