PR22374, PowerPC unnecessary PLT entries

We don't need a PLT entry when function pointer initialization in a
read/write section is the only reference to a given function symbol.
This patch prevents the unnecessary PLT entry, and ensures no dynamic
relocs are emitted when UNDEFWEAK_NO_DYNAMIC_RELOC says so.

bfd/
	PR 22374
	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Don't create a plt
	entry when just a dynamic reloc can serve.  Ensure no dynamic
	relocations when UNDEFWEAK_NO_DYNAMIC_RELOC by setting non_got_ref.
	Expand and move the non_got_ref comment.
	* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
ld/
	* testsuite/ld-powerpc/ambiguousv2.d: Remove FIXME.

1 files changed, 26 insertions, 4 deletions

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 8c98fd5d0eb..5cf862b2dca 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -7193,6 +7193,16 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	  h->plt.plist = NULL;
 	  h->needs_plt = 0;
 	  h->pointer_equality_needed = 0;
+	  /* After adjust_dynamic_symbol, non_got_ref set in the
+	     non-pic case means that dyn_relocs for this symbol should
+	     be discarded.  We either want the symbol to remain
+	     undefined, or we have a local definition of some sort.
+	     The "local definition" for non-function symbols may be
+	     due to creating a local definition in .dynbss, and for
+	     ELFv2 function symbols, defining the symbol on the PLT
+	     call stub code.  Set non_got_ref here to ensure undef
+	     weaks stay undefined.  */
+	  h->non_got_ref = 1;
 	}
       else if (abiversion (info->output_bfd) >= 2)
 	{
@@ -7207,13 +7217,25 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	      && !alias_readonly_dynrelocs (h))
 	    {
 	      h->pointer_equality_needed = 0;
-	      /* After adjust_dynamic_symbol, non_got_ref set in
-		 the non-pic case means that dyn_relocs for this
-		 symbol should be discarded.  */
+	      /* Say that we do want dynamic relocs.  */
 	      h->non_got_ref = 0;
+	      /* If we haven't seen a branch reloc then we don't need
+		 a plt entry.  */
+	      if (!h->needs_plt)
+		h->plt.plist = NULL;
 	    }
 
-	  /* If making a plt entry, then we don't need copy relocs.  */
+	  /* ELFv2 function symbols can't have copy relocs.  */
+	  return TRUE;
+	}
+      else if (!h->needs_plt
+	       && !alias_readonly_dynrelocs (h))
+	{
+	  /* If we haven't seen a branch reloc then we don't need a
+	     plt entry.  */
+	  h->plt.plist = NULL;
+	  h->pointer_equality_needed = 0;
+	  h->non_got_ref = 0;
 	  return TRUE;
 	}
     }