[commit]: dw2_expand_symtabs_with_filename: ignore type units

[dje@google.com (Doug Evans)]

Hi.

fyi, I checked this in.

A supplemental patch is to rename expand_symtabs_with_filename.
expand_code_symtabs_with_filename?
Let me know if you want this change too.

Btw, prior to this patch "break main" on one program here
expanded gdb's memory usage by 2.5G.  :-)

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, not type units.

Index: symfile.h
===================================================================
RCS file: /cvs/src/src/gdb/symfile.h,v
retrieving revision 1.78
diff -u -p -r1.78 symfile.h
--- symfile.h	24 Nov 2010 19:01:51 -0000	1.78
+++ symfile.h	8 Dec 2010 17:23:17 -0000
@@ -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);
 
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.484
diff -u -p -r1.484 dwarf2read.c
--- dwarf2read.c	8 Dec 2010 17:31:52 -0000	1.484
+++ dwarf2read.c	8 Dec 2010 17:44:00 -0000
@@ -2323,8 +2323,13 @@ dw2_expand_symtabs_with_filename (struct
   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);