Re: mn10300 dynamic relocation clean up: remove dynamic PCREL32

[Alexandre Oliva <aoliva at redhat dot com>]

Turned out the adoption of _bfd_elf_symbol_refs_local_p introduced
some ugly regressions in handling of common symbols, because it
doesn't handle them properly.  The problem is that common symbols are
initially set up as bfd_link_hash_common, but then, when then linker
turns them into a definition, it doesn't set
ELF_LINK_HASH_DEF_REGULAR, which _bfd_elf_symbol_refs_local_p depends
on to tell whether a symbol is a definition.

This patch introduces ELF_LINK_HASH_COMMON, set for symbols read in as
common symbols.  This bit remains set after the linker turns the
symbol into a definition, and is the new clean way to tell that the
symbol is a definition of a common symbol.  Unfortunately, I had to
switch to a wider data type for elf_link_hash_flags.

After fixing _bfd_elf_symbol_refs_local_p, I switched to
SYMBOL_REFERENCES_LOCAL, that had the correct semantics for mn10300.

While at that, I also cleaned up an ugly bit in the FR-V code that
attempted to handle common symbols but didn't handle them correctly (a
globally-visible common symbol would be assumed to bind locally).

Ok to install?

Index: bfd/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	* elf-bfd.h (elf_link_hash_flags): Bump up from short to long.
	(ELF_LINK_HASH_COMMON): New flag.
	* elflink.c (_bfd_elf_symbol_refs_local_p): Handle common
	definitions.
	(elf_link_add_object_symbols): Set it for common symbols.
	* elf-m10300.c: Use SYMBOL_REFERENCES_LOCAL instead of
	_bfd_elf_symbol_refs_local_p.
	* elf32-frv.c (FRVFDPIC_SYM_LOCAL): Remove hack for common
	symbols.

Index: bfd/elf-bfd.h
===================================================================
RCS file: /cvs/uberbaum/./bfd/elf-bfd.h,v
retrieving revision 1.143
diff -u -p -r1.143 elf-bfd.h
--- bfd/elf-bfd.h 21 Jun 2004 14:45:41 -0000 1.143
+++ bfd/elf-bfd.h 28 Jun 2004 04:47:56 -0000
@@ -168,7 +168,7 @@ struct elf_link_hash_entry
   unsigned char other;
 
   /* Some flags; legal values follow.  */
-  unsigned short elf_link_hash_flags;
+  unsigned long elf_link_hash_flags;
   /* Symbol is referenced by a non-shared object.  */
 #define ELF_LINK_HASH_REF_REGULAR 01
   /* Symbol is defined by a non-shared object.  */
@@ -203,6 +203,13 @@ struct elf_link_hash_entry
   /* Symbol is referenced with a relocation where C/C++ pointer equality
      matters.  */
 #define ELF_LINK_POINTER_EQUALITY_NEEDED 0100000
+  /* Symbol is, or originally was, a common definition.  Necessary
+     because the linker clears all vestiges of common symbol
+     definitions, but doesn't set ELF_LINK_HASH_DEF_REGULAR.  The way
+     to detect a common symbol that became defined is to test whether
+     the symbol is defined or defweak with HASH_REF_REGULAR and
+     HASH_COMMON.  */
+#define ELF_LINK_HASH_COMMON 0200000
 };
 
 /* Will references to this symbol always reference the symbol
Index: bfd/elf-m10300.c
===================================================================
RCS file: /cvs/uberbaum/./bfd/elf-m10300.c,v
retrieving revision 1.55
diff -u -p -r1.55 elf-m10300.c
--- bfd/elf-m10300.c 27 Jun 2004 03:02:21 -0000 1.55
+++ bfd/elf-m10300.c 28 Jun 2004 04:47:59 -0000
@@ -1020,7 +1020,7 @@ mn10300_elf_final_link_relocate (howto, 
       if (info->shared
 	  && (input_section->flags & SEC_ALLOC) != 0
 	  && h != NULL
-	  && ! _bfd_elf_symbol_refs_local_p (h, info, 1))
+	  && ! SYMBOL_REFERENCES_LOCAL (info, h))
 	return bfd_reloc_dangerous;
     }
 
@@ -1079,7 +1079,7 @@ mn10300_elf_final_link_relocate (howto, 
 	      /* h->dynindx may be -1 if this symbol was marked to
 		 become local.  */
 	      if (h == NULL
-		  || _bfd_elf_symbol_refs_local_p (h, info, 1))
+		  || SYMBOL_REFERENCES_LOCAL (info, h))
 		{
 		  relocate = TRUE;
 		  outrel.r_info = ELF32_R_INFO (0, R_MN10300_RELATIVE);
@@ -1302,7 +1302,7 @@ mn10300_elf_final_link_relocate (howto, 
 	      BFD_ASSERT (off != (bfd_vma) -1);
 
 	      if (! elf_hash_table (info)->dynamic_sections_created
-		  || _bfd_elf_symbol_refs_local_p (h, info, 1))
+		  || SYMBOL_REFERENCES_LOCAL (info, h))
 		/* This is actually a static link, or it is a
 		   -Bsymbolic link and the symbol is defined
 		   locally, or the symbol was forced to be local
@@ -1461,9 +1461,9 @@ mn10300_elf_relocate_section (output_bfd
 		       || r_type == R_MN10300_GOT24
 		       || r_type == R_MN10300_GOT16)
 		      && elf_hash_table (info)->dynamic_sections_created
-		      && !_bfd_elf_symbol_refs_local_p (h, info, 1))
+		      && !SYMBOL_REFERENCES_LOCAL (info, hh))
 		  || (r_type == R_MN10300_32
-		      && !_bfd_elf_symbol_refs_local_p (h, info, 1)
+		      && !SYMBOL_REFERENCES_LOCAL (info, hh)
 		      && ((input_section->flags & SEC_ALLOC) != 0
 			  /* DWARF will emit R_MN10300_32 relocations
 			     in its sections against symbols defined
Index: bfd/elf32-frv.c
===================================================================
RCS file: /cvs/uberbaum/./bfd/elf32-frv.c,v
retrieving revision 1.26
diff -u -p -r1.26 elf32-frv.c
--- bfd/elf32-frv.c 24 Jun 2004 04:46:18 -0000 1.26
+++ bfd/elf32-frv.c 28 Jun 2004 04:48:01 -0000
@@ -661,17 +661,7 @@ frvfdpic_elf_link_hash_table_create (bfd
    its function descriptor must be assigned by the dynamic linker.  */
 #define FRVFDPIC_SYM_LOCAL(INFO, H) \
   (_bfd_elf_symbol_refs_local_p ((H), (INFO), 1) \
-   || ! elf_hash_table (INFO)->dynamic_sections_created \
-   || (/* The condition below is an ugly hack to get .scommon data to
-	  be regarded as local.  For some reason the
-	  ELF_LINK_HASH_DEF_REGULAR bit is not set on such common
-	  symbols, and the SEC_IS_COMMON bit is not set any longer
-	  when we need to perform this test.  Hopefully this
-	  approximation is good enough.  */ \
-       ((H)->root.type == bfd_link_hash_defined \
-	|| (H)->root.type == bfd_link_hash_defweak) \
-       && (H)->root.u.def.section->output_section \
-       && ((H)->root.u.def.section->flags & SEC_LINKER_CREATED)))
+   || ! elf_hash_table (INFO)->dynamic_sections_created)
 #define FRVFDPIC_FUNCDESC_LOCAL(INFO, H) \
   ((H)->dynindx == -1 || ! elf_hash_table (INFO)->dynamic_sections_created)
 
Index: bfd/elflink.c
===================================================================
RCS file: /cvs/uberbaum/./bfd/elflink.c,v
retrieving revision 1.74
diff -u -p -r1.74 elflink.c
--- bfd/elflink.c 24 Jun 2004 04:46:22 -0000 1.74
+++ bfd/elflink.c 28 Jun 2004 04:48:06 -0000
@@ -2450,8 +2450,15 @@ _bfd_elf_symbol_refs_local_p (struct elf
     return TRUE;
 
   /* If we don't have a definition in a regular file, then we can't
-     resolve locally.  The sym is either undefined or dynamic.  */
-  if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
+     resolve locally.  The sym is either undefined or dynamic.  Or a
+     common symbol turned into a local definition, so test that before
+     deciding it's not local.  Note we shouldn't test for hash_common,
+     since we don't know beforehand whether they're going to become
+     definitions.  */
+  if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0
+      && !((h->elf_link_hash_flags & ELF_LINK_HASH_COMMON) != 0
+	   && (h->root.type == bfd_link_hash_defined
+	       || h->root.type == bfd_link_hash_defweak)))
     return FALSE;
 
   /* Forced local symbols resolve locally.  */
@@ -3776,6 +3783,11 @@ elf_link_add_object_symbols (bfd *abfd, 
 
 	  h->elf_link_hash_flags |= new_flag;
 
+	  if (h->root.type == bfd_link_hash_common)
+	    h->elf_link_hash_flags |= ELF_LINK_HASH_COMMON;
+	  else
+	    h->elf_link_hash_flags &= ~ELF_LINK_HASH_COMMON;
+
 	  /* Check to see if we need to add an indirect symbol for
 	     the default name.  */
 	  if (definition || h->root.type == bfd_link_hash_common)

-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}