diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 17d67afc73..5b894700be 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2010-12-08  Doug Evans  <dje@google.com>
 
+	* symfile.h (quick_symbol_functions): Clarify usage of
+	expand_symtabs_with_filename.
+	* dwarf2read.c (dw2_expand_symtabs_with_filename): Only iterate over
+	comp units, ignore type units.
+
 	* dwarf2read.c (dw2_expand_symtabs_with_filename): Use FILENAME_CMP.
 
 2010-12-07  Doug Evans  <dje@google.com>
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 82cde1bf4f..8801fb18f8 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2323,8 +2323,13 @@ dw2_expand_symtabs_with_filename (struct objfile *objfile,
   int i;
 
   dw2_setup (objfile);
-  for (i = 0; i < (dwarf2_per_objfile->n_comp_units
-		   + dwarf2_per_objfile->n_type_comp_units); ++i)
+
+  /* We don't need to consider type units here.
+     This is only called for examining code, e.g. expand_line_sal.
+     There can be an order of magnitude (or more) more type units
+     than comp units, and we avoid them if we can.  */
+
+  for (i = 0; i < dwarf2_per_objfile->n_comp_units; ++i)
     {
       int j;
       struct dwarf2_per_cu_data *per_cu = dw2_get_cu (i);
diff --git a/gdb/symfile.h b/gdb/symfile.h
index e989d5c042..297c181810 100644
--- a/gdb/symfile.h
+++ b/gdb/symfile.h
@@ -209,7 +209,10 @@ struct quick_symbol_functions
   void (*expand_all_symtabs) (struct objfile *objfile);
 
   /* Read all symbol tables associated with OBJFILE which have the
-     file name FILENAME.  */
+     file name FILENAME.
+     This is for the purposes of examining code only, e.g., expand_line_sal.
+     The routine may ignore debug info that is known to not be useful with
+     code, e.g., DW_TAG_type_unit for dwarf debug info.  */
   void (*expand_symtabs_with_filename) (struct objfile *objfile,
 					const char *filename);