[commit]: dw2_expand_symtabs_with_filename: ignore type units

[commit]: dw2_expand_symtabs_with_filename: ignore type units

[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);

Re: [commit]: dw2_expand_symtabs_with_filename: ignore type units

[Doug Evans]

On Wed, Dec 8, 2010 at 10:10 AM, Doug Evans <dje@google.com> wrote:
> 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.

btw, for future reference,
TUs (DW_TAG_type_unit) can share line tables.
E.g. a program may have 95000 TUs but there may be only 5000 line
tables for all of them.
There may be more work that's needed here, and going forward we'll
want to support such sharing.

Re: [commit]: dw2_expand_symtabs_with_filename: ignore type units

[Yao Qi]

On 12/09/2010 02:10 AM, Doug Evans wrote:
> +     The routine may ignore debug info that is known to not be useful with

Shall we use "not to be" or "to not be" in comments above?

-- 
Yao (齐尧)

Re: [commit]: dw2_expand_symtabs_with_filename: ignore type units

[Doug Evans]

On Thu, Dec 9, 2010 at 12:29 AM, Yao Qi <yao@codesourcery.com> wrote:
> On 12/09/2010 02:10 AM, Doug Evans wrote:
>> +     The routine may ignore debug info that is known to not be useful with
>
> Shall we use "not to be" or "to not be" in comments above?

I like the current wording.

Re: [commit]: dw2_expand_symtabs_with_filename: ignore type units

[Tom Tromey]

>>>>> "Doug" == Doug Evans <dje@google.com> writes:

Doug> TUs (DW_TAG_type_unit) can share line tables.
Doug> E.g. a program may have 95000 TUs but there may be only 5000 line
Doug> tables for all of them.
Doug> There may be more work that's needed here, and going forward we'll
Doug> want to support such sharing.

Could you file a bug report for this?

thanks,
Tom

Re: [commit]: dw2_expand_symtabs_with_filename: ignore type units

[Doug Evans]

On Thu, Dec 9, 2010 at 8:38 AM, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Doug" == Doug Evans <dje@google.com> writes:
>
> Doug> TUs (DW_TAG_type_unit) can share line tables.
> Doug> E.g. a program may have 95000 TUs but there may be only 5000 line
> Doug> tables for all of them.
> Doug> There may be more work that's needed here, and going forward we'll
> Doug> want to support such sharing.
>
> Could you file a bug report for this?

[just closing this thread]

I've caught all the cases I'm aware of in .gdb_index support, so I'm
going to skip the bug report for now.