Run eh_frame optimisation for relocatable link

The idea here is to drop .eh_frame FDEs corresponding to dropped
comdat group sections or linkonce sections, but not perform changes in
encoding.

bfd/
	PR 17467
	* elf-eh-frame.c (ENSURE_NO_RELOCS): Don't stop at first NONE reloc.
	(_bfd_elf_parse_eh_frame): When relocatable output, don't set
	flags enabling conversion of CIEs and FDEs to use relative encoding.
	(find_merged_cie): Similarly.
	(_bfd_elf_write_section_eh_frame): Don't edit FDEs when
	relocatable, except for CIE pointer.
	* elflink.c (bfd_elf_reloc_symbol_deleted_p): Return true for
	relocs against symbols in dropped comdat group sections.
	(bfd_elf_discard_info): Do some eh_frame optimisation when
	relocatable.
ld/
	* ldlang.c (lang_add_section): Set up map_head.s and map_tail.s when
	relocatable.

3 files changed, 38 insertions, 15 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index aa2f3ef..be3ae38 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,17 @@
+2014-10-13  Alan Modra  <amodra@gmail.com>
+
+	PR 17467
+	* elf-eh-frame.c (ENSURE_NO_RELOCS): Don't stop at first NONE reloc.
+	(_bfd_elf_parse_eh_frame): When relocatable output, don't set
+	flags enabling conversion of CIEs and FDEs to use relative encoding.
+	(find_merged_cie): Similarly.
+	(_bfd_elf_write_section_eh_frame): Don't edit FDEs when
+	relocatable, except for CIE pointer.
+	* elflink.c (bfd_elf_reloc_symbol_deleted_p): Return true for
+	relocs against symbols in dropped comdat group sections.
+	(bfd_elf_discard_info): Do some eh_frame optimisation when
+	relocatable.
+
 2014-10-09  Jose E. Marchesi  <jose.marchesi@oracle.com>
 
 	* elfxx-sparc.c (_bfd_sparc_elf_merge_private_bfd_data): Handle
diff --git a/bfd/elf-eh-frame.c b/bfd/elf-eh-frame.c
index 331570a..e481f34 100644
--- a/bfd/elf-eh-frame.c
+++ b/bfd/elf-eh-frame.c
@@ -556,10 +556,13 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
 
   /* FIXME: octets_per_byte.  */
 #define ENSURE_NO_RELOCS(buf)				\
-  REQUIRE (!(cookie->rel < cookie->relend		\
-	     && (cookie->rel->r_offset			\
-		 < (bfd_size_type) ((buf) - ehbuf))	\
-	     && cookie->rel->r_info != 0))
+  while (cookie->rel < cookie->relend			\
+	 && (cookie->rel->r_offset			\
+	     < (bfd_size_type) ((buf) - ehbuf)))	\
+    {							\
+      REQUIRE (cookie->rel->r_info == 0);		\
+      cookie->rel++;					\
+    }
 
   /* FIXME: octets_per_byte.  */
 #define SKIP_RELOCS(buf)				\
@@ -726,6 +729,7 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
 	  /* For shared libraries, try to get rid of as many RELATIVE relocs
 	     as possible.  */
 	  if (info->shared
+	      && !info->relocatable
 	      && (get_elf_backend_data (abfd)
 		  ->elf_backend_can_make_relative_eh_frame
 		  (abfd, info, sec)))
@@ -763,10 +767,12 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
 	  ENSURE_NO_RELOCS (buf);
 
 	  if (!info->relocatable)
-	    /* Keep info for merging cies.  */
-	    this_inf->u.cie.u.full_cie = cie;
-	  this_inf->u.cie.per_encoding_relative
-	    = (cie->per_encoding & 0x70) == DW_EH_PE_pcrel;
+	    {
+	      /* Keep info for merging cies.  */
+	      this_inf->u.cie.u.full_cie = cie;
+	      this_inf->u.cie.per_encoding_relative
+		= (cie->per_encoding & 0x70) == DW_EH_PE_pcrel;
+	    }
 	}
       else
 	{
@@ -1071,6 +1077,7 @@ find_merged_cie (bfd *abfd, struct bfd_link_info *info, asection *sec,
 
       if (per_binds_local
 	  && info->shared
+	  && !info->relocatable
 	  && (cie->per_encoding & 0x70) == DW_EH_PE_absptr
 	  && (get_elf_backend_data (abfd)
 	      ->elf_backend_can_make_relative_eh_frame (abfd, info, sec)))
@@ -1577,6 +1584,8 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
 	  value = ((ent->new_offset + sec->output_offset + 4)
 		   - (cie->new_offset + cie->u.cie.u.sec->output_offset));
 	  bfd_put_32 (abfd, value, buf);
+	  if (info->relocatable)
+	    continue;
 	  buf += 4;
 	  width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
 	  value = read_value (abfd, buf, width,
diff --git a/bfd/elflink.c b/bfd/elflink.c
index d33efe0..c8068c0 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -12602,10 +12602,10 @@ bfd_elf_reloc_symbol_deleted_p (bfd_vma offset, void *cookie)
 
 	  if ((h->root.type == bfd_link_hash_defined
 	       || h->root.type == bfd_link_hash_defweak)
-	      && discarded_section (h->root.u.def.section))
+	      && (h->root.u.def.section->owner != rcookie->abfd
+		  || h->root.u.def.section->kept_section != NULL
+		  || discarded_section (h->root.u.def.section)))
 	    return TRUE;
-	  else
-	    return FALSE;
 	}
       else
 	{
@@ -12618,7 +12618,9 @@ bfd_elf_reloc_symbol_deleted_p (bfd_vma offset, void *cookie)
 	  /* Need to: get the symbol; get the section.  */
 	  isym = &rcookie->locsyms[r_symndx];
 	  isec = bfd_section_from_elf_index (rcookie->abfd, isym->st_shndx);
-	  if (isec != NULL && discarded_section (isec))
+	  if (isec != NULL
+	      && (isec->kept_section != NULL
+		  || discarded_section (isec)))
 	    return TRUE;
 	}
       return FALSE;
@@ -12672,9 +12674,7 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
 	}
     }
 
-  o = NULL;
-  if (!info->relocatable)
-    o = bfd_get_section_by_name (output_bfd, ".eh_frame");
+  o = bfd_get_section_by_name (output_bfd, ".eh_frame");
   if (o != NULL)
     {
       asection *i;