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PATCH: PR 757: Linker fails to set correct alignment for common symbol

H. J. Lu hjl@lucon.org
Wed Feb 23 01:05:00 GMT 2005 
We ignored alignment requirement of common symbolsif they are in DSO.
This patch tries to fix it.


H.J.
----
2005-02-22  H.J. Lu  <hongjiu.lu@intel.com>

	PR 757
	* elf-bfd.h (_bfd_elf_merge_symbol): Add a pointer to unsigned
	int.

	* elf32-sh-symbian.c (sh_symbian_relocate_section): Pass NULL
	to _bfd_elf_merge_symbol.

	* elflink.c (_bfd_elf_merge_symbol): Use the pointer to
	unsigned int to return the alignment of the old common symbol
	in the dynamic object.
	(_bfd_elf_add_default_symbol): Pass NULL to
	_bfd_elf_merge_symbol.
	(elf_link_add_object_symbols): Pass &old_alignment to
	_bfd_elf_merge_symbol. Get the alignment of the new common
	symbol in the dynamic object.

--- bfd/elf-bfd.h.comm	2005-02-21 11:07:13.000000000 -0800
+++ bfd/elf-bfd.h	2005-02-22 14:53:50.911295647 -0800
@@ -1554,7 +1554,8 @@ extern bfd_boolean _bfd_elf_maybe_strip_
 
 extern bfd_boolean _bfd_elf_merge_symbol
   (bfd *, struct bfd_link_info *, const char *, Elf_Internal_Sym *,
-   asection **, bfd_vma *, struct elf_link_hash_entry **, bfd_boolean *,
+   asection **, bfd_vma *, unsigned int *,
+   struct elf_link_hash_entry **, bfd_boolean *,
    bfd_boolean *, bfd_boolean *, bfd_boolean *);
 
 extern bfd_boolean _bfd_elf_add_default_symbol
--- bfd/elf32-sh-symbian.c.comm	2005-02-21 11:07:31.000000000 -0800
+++ bfd/elf32-sh-symbian.c	2005-02-22 15:01:12.949180556 -0800
@@ -492,8 +492,11 @@ sh_symbian_relocate_section (bfd *      
 	      new_sym.st_other = ELF_ST_VISIBILITY (STV_DEFAULT);
 	      new_sym.st_shndx = SHN_UNDEF;
 
-	      if (! _bfd_elf_merge_symbol (input_bfd, info, ptr->new_name, & new_sym, & psec,
-					   & new_value, & new_hash, & skip, & override, & type_change_ok,
+	      if (! _bfd_elf_merge_symbol (input_bfd, info,
+					   ptr->new_name, & new_sym,
+					   & psec, & new_value, NULL,
+					   & new_hash, & skip,
+					   & override, & type_change_ok,
 					   & size_change_ok))
 		{
 		  _bfd_error_handler (_("%B: Failed to add renamed symbol %s"),
--- bfd/elflink.c.comm	2005-02-11 13:18:13.000000000 -0800
+++ bfd/elflink.c	2005-02-22 15:02:29.422299573 -0800
@@ -756,7 +756,8 @@ _bfd_elf_link_renumber_dynsyms (bfd *out
    TYPE_CHANGE_OK if it is OK for the type to change.  We set
    SIZE_CHANGE_OK if it is OK for the size to change.  By OK to
    change, we mean that we shouldn't warn if the type or size does
-   change.  */
+   change.  We set POLD_ALIGNMENT if an old common symbol in a dynamic
+   object is overridden by a regular object.  */
 
 bfd_boolean
 _bfd_elf_merge_symbol (bfd *abfd,
@@ -765,6 +766,7 @@ _bfd_elf_merge_symbol (bfd *abfd,
 		       Elf_Internal_Sym *sym,
 		       asection **psec,
 		       bfd_vma *pvalue,
+		       unsigned int *pold_alignment,
 		       struct elf_link_hash_entry **sym_hash,
 		       bfd_boolean *skip,
 		       bfd_boolean *override,
@@ -1269,9 +1271,10 @@ _bfd_elf_merge_symbol (bfd *abfd,
       if (h->size > *pvalue)
 	*pvalue = h->size;
 
-      /* FIXME: We no longer know the alignment required by the symbol
-	 in the dynamic object, so we just wind up using the one from
-	 the regular object.  */
+      /* We need to remember the alignment required by the symbol
+	 in the dynamic object.  */
+      BFD_ASSERT (pold_alignment);
+      *pold_alignment = h->root.u.def.section->alignment_power;
 
       olddef = FALSE;
       olddyncommon = FALSE;
@@ -1383,8 +1386,8 @@ _bfd_elf_add_default_symbol (bfd *abfd,
   size_change_ok = FALSE;
   sec = *psec;
   if (!_bfd_elf_merge_symbol (abfd, info, shortname, sym, &sec, value,
-			      &hi, &skip, &override, &type_change_ok,
-			      &size_change_ok))
+			      NULL, &hi, &skip, &override,
+			      &type_change_ok, &size_change_ok))
     return FALSE;
 
   if (skip)
@@ -1487,8 +1490,8 @@ nondefault:
   size_change_ok = FALSE;
   sec = *psec;
   if (!_bfd_elf_merge_symbol (abfd, info, shortname, sym, &sec, value,
-			      &hi, &skip, &override, &type_change_ok,
-			      &size_change_ok))
+			      NULL, &hi, &skip, &override,
+			      &type_change_ok, &size_change_ok))
     return FALSE;
 
   if (skip)
@@ -3525,7 +3528,7 @@ elf_link_add_object_symbols (bfd *abfd, 
     {
       int bind;
       bfd_vma value;
-      asection *sec;
+      asection *sec, *new_sec;
       flagword flags;
       const char *name;
       struct elf_link_hash_entry *h;
@@ -3647,6 +3650,7 @@ elf_link_add_object_symbols (bfd *abfd, 
       type_change_ok = get_elf_backend_data (abfd)->type_change_ok;
       old_alignment = 0;
       old_bfd = NULL;
+      new_sec = sec;
 
       if (is_elf_hash_table (hash_table))
 	{
@@ -3759,7 +3763,8 @@ elf_link_add_object_symbols (bfd *abfd, 
 	      name = newname;
 	    }
 
-	  if (!_bfd_elf_merge_symbol (abfd, info, name, isym, &sec, &value,
+	  if (!_bfd_elf_merge_symbol (abfd, info, name, isym, &sec,
+				      &value, &old_alignment,
 				      sym_hash, &skip, &override,
 				      &type_change_ok, &size_change_ok))
 	    goto error_free_vers;
@@ -3841,12 +3846,20 @@ elf_link_add_object_symbols (bfd *abfd, 
 	}
 
       /* Set the alignment of a common symbol.  */
-      if (isym->st_shndx == SHN_COMMON
+      if ((isym->st_shndx == SHN_COMMON
+	   || bfd_is_com_section (sec))
 	  && h->root.type == bfd_link_hash_common)
 	{
 	  unsigned int align;
 
-	  align = bfd_log2 (isym->st_value);
+	  if (isym->st_shndx == SHN_COMMON)
+	    align = bfd_log2 (isym->st_value);
+	  else
+	    {
+	      /* The new symbol is a common symbol in a shared object.
+		 We need to get the alignment from the section.  */
+	      align = new_sec->alignment_power;
+	    }
 	  if (align > old_alignment
 	      /* Permit an alignment power of zero if an alignment of one
 		 is specified and no other alignments have been specified.  */
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