Work around gold/15646.

	* dwarf2read.c (read_index_from_section): Update comment.
	(struct dw2_symtab_iterator): New member global_seen.
	(dw2_symtab_iter_init): Initialize it.
	(dw2_symtab_iter_next): Skip duplicate global symbols.
	(dw2_expand_symtabs_matching): Ditto.

2 files changed, 45 insertions, 7 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cc97bbe..6541837 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2013-11-12  Doug Evans  <dje@google.com>
+
+	Work around gold/15646.
+	* dwarf2read.c (read_index_from_section): Update comment.
+	(struct dw2_symtab_iterator): New member global_seen.
+	(dw2_symtab_iter_init): Initialize it.
+	(dw2_symtab_iter_next): Skip duplicate global symbols.
+	(dw2_expand_symtabs_matching): Ditto.
+
 2013-11-12  Joel Brobecker  <brobecker@adacore.com>
 
 	* mi/mi-cmds.h (mi_cmd_info_ada_exceptions): Add declaration.
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 7e87ed9..c5c3b5c 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -3034,9 +3034,12 @@ to use the section anyway."),
       return 0;
     }
   /* Version 7 indices generated by gold refer to the CU for a symbol instead
-     of the TU (for symbols coming from TUs).  It's just a performance bug, and
-     we can't distinguish gdb-generated indices from gold-generated ones, so
-     nothing to do here.  */
+     of the TU (for symbols coming from TUs),
+     http://sourceware.org/bugzilla/show_bug.cgi?id=15021.
+     Plus gold-generated indices can have duplicate entries for global symbols,
+     http://sourceware.org/bugzilla/show_bug.cgi?id=15646.
+     These are just performance bugs, and we can't distinguish gdb-generated
+     indices from gold-generated ones, so issue no warning here.  */
 
   /* Indexes with higher version than the one supported by GDB may be no
      longer backward compatible.  */
@@ -3448,6 +3451,11 @@ struct dw2_symtab_iterator
   int next;
   /* The number of elements in VEC, or zero if there is no match.  */
   int length;
+  /* Have we seen a global version of the symbol?
+     If so we can ignore all further global instances.
+     This is to work around gold/15646, inefficient gold-generated
+     indices.  */
+  int global_seen;
 };
 
 /* Initialize the index symtab iterator ITER.
@@ -3467,6 +3475,7 @@ dw2_symtab_iter_init (struct dw2_symtab_iterator *iter,
   iter->block_index = block_index;
   iter->domain = domain;
   iter->next = 0;
+  iter->global_seen = 0;
 
   if (find_slot_in_mapped_hash (index, name, &iter->vec))
     iter->length = MAYBE_SWAP (*iter->vec);
@@ -3518,10 +3527,18 @@ dw2_symtab_iter_next (struct dw2_symtab_iterator *iter)
       if (per_cu->v.quick->symtab)
 	continue;
 
-      if (attrs_valid
-	  && iter->want_specific_block
-	  && want_static != is_static)
-	continue;
+      /* Check static vs global.  */
+      if (attrs_valid)
+	{
+	  if (iter->want_specific_block
+	      && want_static != is_static)
+	    continue;
+	  /* Work around gold/15646.  */
+	  if (!is_static && iter->global_seen)
+	    continue;
+	  if (!is_static)
+	    iter->global_seen = 1;
+	}
 
       /* Only check the symbol's kind if it has one.  */
       if (attrs_valid)
@@ -3849,6 +3866,7 @@ dw2_expand_symtabs_matching
       offset_type idx = 2 * iter;
       const char *name;
       offset_type *vec, vec_len, vec_idx;
+      int global_seen = 0;
 
       if (index->symbol_table[idx] == 0 && index->symbol_table[idx + 1] == 0)
 	continue;
@@ -3867,6 +3885,8 @@ dw2_expand_symtabs_matching
 	{
 	  struct dwarf2_per_cu_data *per_cu;
 	  offset_type cu_index_and_attrs = MAYBE_SWAP (vec[vec_idx + 1]);
+	  /* This value is only valid for index versions >= 7.  */
+	  int is_static = GDB_INDEX_SYMBOL_STATIC_VALUE (cu_index_and_attrs);
 	  gdb_index_symbol_kind symbol_kind =
 	    GDB_INDEX_SYMBOL_KIND_VALUE (cu_index_and_attrs);
 	  int cu_index = GDB_INDEX_CU_VALUE (cu_index_and_attrs);
@@ -3878,6 +3898,15 @@ dw2_expand_symtabs_matching
 	    (index->version >= 7
 	     && symbol_kind != GDB_INDEX_SYMBOL_KIND_NONE);
 
+	  /* Work around gold/15646.  */
+	  if (attrs_valid)
+	    {
+	      if (!is_static && global_seen)
+		continue;
+	      if (!is_static)
+		global_seen = 1;
+	    }
+
 	  /* Only check the symbol's kind if it has one.  */
 	  if (attrs_valid)
 	    {