PATCH for using both RELA and REL relocations in the samebackend

[Mark Mitchell <mark@codesourcery.com>]

On IRIX6, some relocation sections use RELA relocations and some use
REL relocations.  Here's a patch to support this kind of behavior in
general.

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com

1999-05-31  Mark Mitchell  <mark@codesourcery.com>

	* elf-bfd.h (elf_backend_data): Remove use_rela_p.  Add
	may_use_rel_p, may_use_rela_p, default_use_rela_p.
	* section.c (SEC_ELF_USE_RELA): New constant.
	* elf.c (bfd_section_from_shdr): Set or clear SEC_ELF_USE_RELA.
	(_bfd_elf_new_section_hook): Likewise.
	(elf_fake_sections): Use may_use_rela_p, etc., instead of
	use_rela_p.
	* elfcode.h (write_relocs): Determine whether or not use rela
	relocs based on the relocation section header.
	* elflink.c (_bfd_elf_create_dynamic_sections): Use default_use_rela_p
	instead of use_rela_p.
	* elfxx-target.h (elf_backend_may_use_relp): New macro.
	(elf_backend_may_use_rela_p): Likewise.
	(elf_backend_default_use_rela_p): Likewise.
	(elfNN_bed): Use them.
	
Index: elf-bfd.h
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/elf-bfd.h,v
retrieving revision 1.5
diff -u -p -r1.5 elf-bfd.h
--- elf-bfd.h	1999/05/31 20:46:40	1.5
+++ elf-bfd.h	1999/05/31 21:12:48
@@ -255,11 +255,6 @@ struct elf_size_info {
 
 struct elf_backend_data
 {
-  /* Whether the backend uses REL or RELA relocations.  FIXME: some
-     ELF backends use both.  When we need to support one, this whole
-     approach will need to be changed.  */
-  int use_rela_p;
-
   /* The architecture for this backend.  */
   enum bfd_architecture arch;
 
@@ -539,6 +534,23 @@ struct elf_backend_data
      the so-called reserved entries on some systems.  */
   bfd_vma got_header_size;
   bfd_vma plt_header_size;
+
+  /* Whether the backend may use REL relocations.  (Some backends use
+     both REL and RELA relocations, and this flag is set for those
+     backends.)  */
+  unsigned may_use_rel_p : 1;
+    
+  /* Whether the backend may use RELA relocations.  (Some backends use
+     both REL and RELA relocations, and this flag is set for those
+     backends.)  */
+  unsigned may_use_rela_p : 1;
+
+  /* Whether the default relocation type is RELA.  If a backend with
+     this flag set wants REL relocations for a particular section,
+     it must note that explicitly.  Similarly, if this flag is clear,
+     and the backend wants RELA relocations for a particular 
+     section.  */   
+  unsigned default_use_rela_p : 1;
 
   unsigned want_got_plt : 1;
   unsigned plt_readonly : 1;
Index: section.c
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/section.c,v
retrieving revision 1.4
diff -u -p -r1.4 section.c
--- section.c	1999/05/31 20:46:41	1.4
+++ section.c	1999/05/31 21:12:48
@@ -307,6 +307,14 @@ CODE_FRAGMENT
 .	{* This section should not be subject to garbage collection.  *}
 .#define SEC_KEEP 0x1000000
 .
+.#define SEC_ELF_USE_RELA 0x2000000
+.       {* The relocations for this section are of the RELA, rather
+.	   than the REL, variety.  As indicated by the name, this 
+.	   flag is Elf-specific.  It is store in FLAGS, rather than in
+.	   the Elf-specific data, because some programs (like objcopy)
+.	   copy all the attributes of a section by copying its 
+.	   flags.  *}
+.
 .	{*  End of section flags.  *}
 .
 .	{* Some internal packed boolean fields.  *}
Index: elf.c
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/elf.c,v
retrieving revision 1.5
diff -u -p -r1.5 elf.c
--- elf.c	1999/05/31 20:46:40	1.5
+++ elf.c	1999/05/31 21:17:33
@@ -1265,6 +1265,12 @@ bfd_section_from_shdr (abfd, shindex)
 	target_sect->flags |= SEC_RELOC;
 	target_sect->relocation = NULL;
 	target_sect->rel_filepos = hdr->sh_offset;
+	/* In the section to which the relocations apply, mark whether
+	   its relocations are of the REL or RELA variety.  */
+	if (hdr->sh_type == SHT_RELA)
+	  target_sect->flags |= SEC_ELF_USE_RELA;
+	else
+	  target_sect->flags &= ~SEC_ELF_USE_RELA;
 	abfd->flags |= HAS_RELOC;
 	return true;
       }
@@ -1323,12 +1329,19 @@ _bfd_elf_new_section_hook (abfd, sec)
      asection *sec;
 {
   struct bfd_elf_section_data *sdata;
+  flagword f;
 
   sdata = (struct bfd_elf_section_data *) bfd_alloc (abfd, sizeof (*sdata));
   if (!sdata)
     return false;
   sec->used_by_bfd = (PTR) sdata;
   memset (sdata, 0, sizeof (*sdata));
+
+  /* Indicate whether or not this section should use RELA relocations.  */
+  f = bfd_get_section_flags (abfd, sec);
+  if (get_elf_backend_data (abfd)->default_use_rela_p)
+    f |= SEC_ELF_USE_RELA;
+
   return true;
 }
 
@@ -1491,13 +1504,13 @@ elf_fake_sections (abfd, asect, failedpt
       this_hdr->sh_entsize = bed->s->sizeof_dyn;
     }
   else if (strncmp (asect->name, ".rela.", 6) == 0
-	   && get_elf_backend_data (abfd)->use_rela_p)
+	   && get_elf_backend_data (abfd)->may_use_rela_p)
     {
       this_hdr->sh_type = SHT_RELA;
       this_hdr->sh_entsize = bed->s->sizeof_rela;
     }
   else if (strncmp (asect->name, ".rel.", 5) == 0
-	   && ! get_elf_backend_data (abfd)->use_rela_p)
+	   && get_elf_backend_data (abfd)->may_use_rel_p)
     {
       this_hdr->sh_type = SHT_REL;
       this_hdr->sh_entsize = bed->s->sizeof_rel;
@@ -1558,19 +1571,16 @@ elf_fake_sections (abfd, asect, failedpt
     this_hdr->sh_flags |= SHF_EXECINSTR;
 
   /* Check for processor-specific section types.  */
-  {
-    struct elf_backend_data *bed = get_elf_backend_data (abfd);
-
-    if (bed->elf_backend_fake_sections)
-      (*bed->elf_backend_fake_sections) (abfd, this_hdr, asect);
-  }
+  if (bed->elf_backend_fake_sections)
+    (*bed->elf_backend_fake_sections) (abfd, this_hdr, asect);
 
   /* If the section has relocs, set up a section header for the
      SHT_REL[A] section.  */
   if ((asect->flags & SEC_RELOC) != 0)
     {
       Elf_Internal_Shdr *rela_hdr;
-      int use_rela_p = get_elf_backend_data (abfd)->use_rela_p;
+      int use_rela_p 
+	= bfd_get_section_flags (abfd, asect) & SEC_ELF_USE_RELA;
       char *name;
 
       rela_hdr = &elf_section_data (asect)->rel_hdr;
@@ -3952,8 +3962,8 @@ swap_out_syms (abfd, sttp, relocatable_p
 	flagword flags = syms[idx]->flags;
 	int type;
 
-	if (flags & BSF_SECTION_SYM)
-	  /* Section symbols have no names.  */
+	if ((flags & BSF_SECTION_SYM) && !syms[idx]->name)
+	  /* Some section symbols have no names.  */
 	  sym.st_name = 0;
 	else
 	  {
Index: elfcode.h
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/elfcode.h,v
retrieving revision 1.5
diff -u -p -r1.5 elfcode.h
--- elfcode.h	1999/05/31 20:46:41	1.5
+++ elfcode.h	1999/05/31 21:12:48
@@ -729,7 +729,7 @@ write_relocs (abfd, sec, data)
   Elf_External_Rela *outbound_relocas;
   Elf_External_Rel *outbound_relocs;
   unsigned int idx;
-  int use_rela_p = get_elf_backend_data (abfd)->use_rela_p;
+  int use_rela_p;
   asymbol *last_sym = 0;
   int last_sym_idx = 0;
 
@@ -756,6 +756,16 @@ write_relocs (abfd, sec, data)
       *failedp = true;
       return;
     }
+
+  /* Figure out whether the relocations are RELA or REL relocations.  */
+  if (rela_hdr->sh_type == SHT_RELA)
+    use_rela_p = true;
+  else if (rela_hdr->sh_type == SHT_REL)
+    use_rela_p = false;
+  else
+    /* Every relocation section should be either an SHT_RELA or an
+       SHT_REL section.  */
+    abort ();
 
   /* orelocation has the data, reloc_count has the count... */
   if (use_rela_p)
Index: elflink.c
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/elflink.c,v
retrieving revision 1.3
diff -u -p -r1.3 elflink.c
--- elflink.c	1999/05/31 20:46:41	1.3
+++ elflink.c	1999/05/31 21:12:48
@@ -147,7 +147,8 @@ _bfd_elf_create_dynamic_sections (abfd, 
 	return false;
     }
 
-  s = bfd_make_section (abfd, bed->use_rela_p ? ".rela.plt" : ".rel.plt");
+  s = bfd_make_section (abfd, 
+			bed->default_use_rela_p ? ".rela.plt" : ".rel.plt");
   if (s == NULL
       || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY)
       || ! bfd_set_section_alignment (abfd, s, ptralign))
@@ -180,7 +181,9 @@ _bfd_elf_create_dynamic_sections (abfd, 
      copy relocs.  */
   if (! info->shared)
     {
-      s = bfd_make_section (abfd, bed->use_rela_p ? ".rela.bss" : ".rel.bss");
+      s = bfd_make_section (abfd, 
+			    bed->default_use_rela_p 
+			    ? ".rela.bss" : ".rel.bss"); 
       if (s == NULL
 	  || ! bfd_set_section_flags (abfd, s, flags | SEC_READONLY)
 	  || ! bfd_set_section_alignment (abfd, s, ptralign))
Index: elfxx-target.h
===================================================================
RCS file: /usr/local/Repository/binutils/bfd/elfxx-target.h,v
retrieving revision 1.4
diff -u -p -r1.4 elfxx-target.h
--- elfxx-target.h	1999/05/31 20:46:41	1.4
+++ elfxx-target.h	1999/05/31 21:15:40
@@ -294,6 +294,28 @@ Foundation, Inc., 59 Temple Place - Suit
 #define elf_backend_post_process_headers	NULL
 #endif
 
+/* Previously, backends could only use SHT_REL or SHT_RELA relocation
+   sections, but not both.  They defined USE_REL to indicate SHT_REL
+   sections, and left it undefined to indicated SHT_RELA sections.
+   For backwards compatibility, we still support this usage.  */
+#ifndef USE_REL
+#define USE_REL 0
+#else
+#undef USE_REL
+#define USE_REL 1
+#endif 
+
+/* Use these in new code.  */
+#ifndef elf_backend_may_use_rel_p 
+#define elf_backend_may_use_rel_p USE_REL
+#endif 
+#ifndef elf_backend_may_use_rela_p
+#define elf_backend_may_use_rela_p !USE_REL
+#endif
+#ifndef elf_backend_default_use_rela_p 
+#define elf_backend_default_use_rela_p !USE_REL
+#endif
+
 #ifndef ELF_MACHINE_ALT1
 #define ELF_MACHINE_ALT1 0
 #endif
@@ -310,11 +332,6 @@ extern const struct elf_size_info _bfd_e
 
 static CONST struct elf_backend_data elfNN_bed =
 {
-#ifdef USE_REL
-  0,				/* use_rela_p */
-#else
-  1,				/* use_rela_p */
-#endif
   ELF_ARCH,			/* arch */
   ELF_MACHINE_CODE,		/* elf_machine_code */
   ELF_MAXPAGESIZE,		/* maxpagesize */
@@ -355,6 +372,9 @@ static CONST struct elf_backend_data elf
   elf_backend_got_symbol_offset,
   elf_backend_got_header_size,
   elf_backend_plt_header_size,
+  elf_backend_may_use_rel_p,
+  elf_backend_may_use_rela_p,
+  elf_backend_default_use_rela_p,
   elf_backend_want_got_plt,
   elf_backend_plt_readonly,
   elf_backend_want_plt_sym,