Implement -z dynamic-undefined-weak

-z nodynamic-undefined-weak is only implemented for x86.  (The sparc
backend has some support code but doesn't enable the option by
including ld/emulparams/dynamic_undefined_weak.sh, and since the
support looks like it may be broken I haven't enabled it.)  This patch
adds the complementary -z dynamic-undefined-weak, extends both options
to affect building of shared libraries as well as executables, and
adds support for the option on powerpc.

include/
	* bfdlink.h (struct bfd_link_info <dynamic_undefined_weak>):
	Revise comment.
bfd/
	* elflink.c (_bfd_elf_adjust_dynamic_symbol): Hide undefweak
	or make dynamic for info->dynamic_undefined_weak 0 and 1.
	* elf32-ppc.c:Formatting.
	(ensure_undefweak_dynamic): Don't make dynamic when
	info->dynamic_undefined_weak is zero.
	(allocate_dynrelocs): Discard undefweak dyn_relocs for
	info->dynamic_undefined_weak.  Discard undef dyn_relocs when
	not default visibility.  Discard undef and undefweak
	dyn_relocs earlier.
	(ppc_elf_relocate_section): Adjust to suit.
	* elf64-ppc.c: Formatting.
	(ensure_undefweak_dynamic): Don't make dynamic when
	info->dynamic_undefined_weak is zero.
	(allocate_dynrelocs): Discard undefweak dyn_relocs for
	info->dynamic_undefined_weak.  Discard them earlier.
ld/
	* ld.texinfo (dynamic-undefined-weak): Document.
	(nodynamic-undefined-weak): Document that this option now can
	be used with shared libs.
	* emulparams/dynamic_undefined_weak.sh: Support -z
	dynamic-undefined-weak.
	* emulparams/elf32ppccommon.sh: Include dynamic_undefined_weak.sh.
	* testsuite/ld-undefined/weak-undef.exp (undef_weak_so),
	(undef_weak_exe): New.  Use them.  Add -z dynamic-undefined-weak
	and -z nodynamic-undefined-weak tests.
	* Makefile.am: Update powerpc dependencies.
	* Makefile.in: Regenerate.

4 files changed, 73 insertions, 31 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f1ca8b4..b66ade6 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,21 @@
+2017-04-19  Alan Modra  <amodra@gmail.com>
+
+	* elflink.c (_bfd_elf_adjust_dynamic_symbol): Hide undefweak
+	or make dynamic for info->dynamic_undefined_weak 0 and 1.
+	* elf32-ppc.c:Formatting.
+	(ensure_undefweak_dynamic): Don't make dynamic when
+	info->dynamic_undefined_weak is zero.
+	(allocate_dynrelocs): Discard undefweak dyn_relocs for
+	info->dynamic_undefined_weak.  Discard undef dyn_relocs when
+	not default visibility.  Discard undef and undefweak
+	dyn_relocs earlier.
+	(ppc_elf_relocate_section): Adjust to suit.
+	* elf64-ppc.c: Formatting.
+	(ensure_undefweak_dynamic): Don't make dynamic when
+	info->dynamic_undefined_weak is zero.
+	(allocate_dynrelocs): Discard undefweak dyn_relocs for
+	info->dynamic_undefined_weak.  Discard them earlier.
+
 2017-04-17  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/21389
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 4bd58e2..6a24a46 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -2609,7 +2609,7 @@ ppc_elf_modify_segment_map (bfd *abfd,
       amt += (m->count - j - 1) * sizeof (asection *);
       n = (struct elf_segment_map *) bfd_zalloc (abfd, amt);
       if (n == NULL)
-        return FALSE;
+	return FALSE;
 
       n->p_type = PT_LOAD;
       n->count = m->count - j;
@@ -5947,6 +5947,7 @@ ensure_undefweak_dynamic (struct bfd_link_info *info,
   struct elf_link_hash_table *htab = elf_hash_table (info);
 
   if (htab->dynamic_sections_created
+      && info->dynamic_undefined_weak != 0
       && h->root.type == bfd_link_hash_undefweak
       && h->dynindx == -1
       && !h->forced_local
@@ -6036,6 +6037,8 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
   else
     eh->elf.got.offset = (bfd_vma) -1;
 
+  /* If no dynamic sections we can't have dynamic relocs, except for
+     IFUNCs which are handled even in static executables.  */
   if (!htab->elf.dynamic_sections_created
       && h->type != STT_GNU_IFUNC)
     eh->dyn_relocs = NULL;
@@ -6050,13 +6053,25 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
      changes.  */
   else if (bfd_link_pic (info))
     {
+      /* Discard relocs on undefined symbols that must be local.  */
+      if (h->root.type == bfd_link_hash_undefined
+	  && ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
+	eh->dyn_relocs = NULL;
+
+      /* Also discard relocs on undefined weak syms with non-default
+	 visibility, or when dynamic_undefined_weak says so.  */
+      else if (h->root.type == bfd_link_hash_undefweak
+	       && (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+		   || info->dynamic_undefined_weak == 0))
+	eh->dyn_relocs = NULL;
+
       /* Relocs that use pc_count are those that appear on a call insn,
 	 or certain REL relocs (see must_be_dyn_reloc) that can be
 	 generated via assembly.  We want calls to protected symbols to
 	 resolve directly to the function rather than going via the plt.
 	 If people want function pointer comparisons to work as expected
 	 then they should avoid writing weird assembly.  */
-      if (SYMBOL_CALLS_LOCAL (info, h))
+      else if (SYMBOL_CALLS_LOCAL (info, h))
 	{
 	  struct elf_dyn_relocs **pp;
 
@@ -6084,24 +6099,11 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	    }
 	}
 
-      /* Discard relocs on undefined symbols that must be local.  */
-      if (eh->dyn_relocs != NULL
-	  && h->root.type == bfd_link_hash_undefined
-	  && (ELF_ST_VISIBILITY (h->other) == STV_HIDDEN
-	      || ELF_ST_VISIBILITY (h->other) == STV_INTERNAL))
-	eh->dyn_relocs = NULL;
-
-      /* Also discard relocs on undefined weak syms with non-default
-	 visibility.  */
-      if (eh->dyn_relocs != NULL
-	  && h->root.type == bfd_link_hash_undefweak)
+      if (eh->dyn_relocs != NULL)
 	{
-	  if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
-	    eh->dyn_relocs = NULL;
-
 	  /* Make sure undefined weak symbols are output as a dynamic
 	     symbol in PIEs.  */
-	  else if (!ensure_undefweak_dynamic (info, h))
+	  if (!ensure_undefweak_dynamic (info, h))
 	    return FALSE;
 	}
     }
@@ -8859,10 +8861,10 @@ ppc_elf_relocate_section (bfd *output_bfd,
 	  if ((bfd_link_pic (info)
 	       && !(h != NULL
 		    && ((h->root.type == bfd_link_hash_undefined
-			 && (ELF_ST_VISIBILITY (h->other) == STV_HIDDEN
-			     || ELF_ST_VISIBILITY (h->other) == STV_INTERNAL))
+			 && ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
 			|| (h->root.type == bfd_link_hash_undefweak
-			    && ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)))
+			    && (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+				|| info->dynamic_undefined_weak == 0))))
 	       && (must_be_dyn_reloc (info, r_type)
 		   || !SYMBOL_CALLS_LOCAL (info, h)))
 	      || (ELIMINATE_COPY_RELOCS
@@ -10979,7 +10981,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
 #define elf_backend_finish_dynamic_sections	ppc_elf_finish_dynamic_sections
 #define elf_backend_fake_sections		ppc_elf_fake_sections
 #define elf_backend_additional_program_headers	ppc_elf_additional_program_headers
-#define elf_backend_modify_segment_map     	ppc_elf_modify_segment_map
+#define elf_backend_modify_segment_map		ppc_elf_modify_segment_map
 #define elf_backend_grok_prstatus		ppc_elf_grok_prstatus
 #define elf_backend_grok_psinfo			ppc_elf_grok_psinfo
 #define elf_backend_write_core_note		ppc_elf_write_core_note
@@ -11049,7 +11051,7 @@ ppc_elf_vxworks_link_hash_table_create (bfd *abfd)
   if (ret)
     {
       struct ppc_elf_link_hash_table *htab
-        = (struct ppc_elf_link_hash_table *)ret;
+	= (struct ppc_elf_link_hash_table *)ret;
       htab->is_vxworks = 1;
       htab->plt_type = PLT_VXWORKS;
       htab->plt_entry_size = VXWORKS_PLT_ENTRY_SIZE;
diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index e48d67d..fc69964 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -9695,6 +9695,7 @@ ensure_undefweak_dynamic (struct bfd_link_info *info,
   struct elf_link_hash_table *htab = elf_hash_table (info);
 
   if (htab->dynamic_sections_created
+      && info->dynamic_undefined_weak != 0
       && h->root.type == bfd_link_hash_undefweak
       && h->dynindx == -1
       && !h->forced_local
@@ -9785,10 +9786,19 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	allocate_got (h, info, gent);
       }
 
+  /* If no dynamic sections we can't have dynamic relocs, except for
+     IFUNCs which are handled even in static executables.  */
   if (!htab->elf.dynamic_sections_created
       && h->type != STT_GNU_IFUNC)
     eh->dyn_relocs = NULL;
 
+  /* Also discard relocs on undefined weak syms with non-default
+     visibility, or when dynamic_undefined_weak says so.  */
+  else if (h->root.type == bfd_link_hash_undefweak
+	   && (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+	       || info->dynamic_undefined_weak == 0))
+    eh->dyn_relocs = NULL;
+
   if (eh->dyn_relocs != NULL)
     {
       struct elf_dyn_relocs *p, **pp;
@@ -9821,17 +9831,11 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 		}
 	    }
 
-	  /* Also discard relocs on undefined weak syms with
-	     non-default visibility.  */
-	  if (eh->dyn_relocs != NULL
-	      && h->root.type == bfd_link_hash_undefweak)
+	  if (eh->dyn_relocs != NULL)
 	    {
-	      if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
-		eh->dyn_relocs = NULL;
-
 	      /* Make sure this symbol is output as a dynamic symbol.
 		 Undefined weak syms won't yet be marked as dynamic.  */
-	      else if (!ensure_undefweak_dynamic (info, h))
+	      if (!ensure_undefweak_dynamic (info, h))
 		return FALSE;
 	    }
 	}
@@ -14320,7 +14324,7 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	      addend = 0;
 	      reloc_dest = DEST_STUB;
 
- 	      if ((stub_entry->stub_type == ppc_stub_plt_call
+	      if ((stub_entry->stub_type == ppc_stub_plt_call
 		   || stub_entry->stub_type == ppc_stub_plt_call_r2save)
 		  && (ALWAYS_EMIT_R2SAVE
 		      || stub_entry->stub_type == ppc_stub_plt_call_r2save)
diff --git a/bfd/elflink.c b/bfd/elflink.c
index b93d4f3..0add01b 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -2803,6 +2803,24 @@ _bfd_elf_adjust_dynamic_symbol (struct elf_link_hash_entry *h, void *data)
   if (! _bfd_elf_fix_symbol_flags (h, eif))
     return FALSE;
 
+  if (h->root.type == bfd_link_hash_undefweak)
+    {
+      if (eif->info->dynamic_undefined_weak == 0)
+	_bfd_elf_link_hash_hide_symbol (eif->info, h, TRUE);
+      else if (eif->info->dynamic_undefined_weak > 0
+	       && h->ref_regular
+	       && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+	       && !bfd_hide_sym_by_version (eif->info->version_info,
+					    h->root.root.string))
+	{
+	  if (!bfd_elf_link_record_dynamic_symbol (eif->info, h))
+	    {
+	      eif->failed = TRUE;
+	      return FALSE;
+	    }
+	}
+    }
+
   /* If this symbol does not require a PLT entry, and it is not
      defined by a dynamic object, or is not referenced by a regular
      object, ignore it.  We do have to handle a weak defined symbol,