[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-13 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #10 from pj dot pandit at yahoo dot co dot in  2010-08-13 10:37 
---
I think we've stepped away from DW_AT_external.

This global linkage theory is not convincing for why DW_AT_external should be
set for variables/functions that are defined outside of the compilation unit.


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pj dot pandit at yahoo dot co dot in changed:

   What|Removed |Added

 Status|RESOLVED|UNCONFIRMED
 Resolution|INVALID |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-13 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #14 from pj dot pandit at yahoo dot co dot in  2010-08-13 13:14 
---
 But surely if (as you suggest) swscanf had a DIE without DW_AT_external that
 would imply it was private to the compilation unit, which would be wrong.

  Hmmn...may be.

 DW_AT_specification tells you it's defined, DW_AT_external tells you it's
 visible.

  DW_AT_specification does not seem to be present all the time. It shows up in
C++ program, but does not show up in a C program.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-12 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #7 from pj dot pandit at yahoo dot co dot in  2010-08-13 05:52 
---
You got me confused. What do you mean - DW_AT_external is correct for anything
that has global linkage, whether or not is defined. - ?

How do you define global linkage, here?

DIEs for static variables/functions don't have DW_AT_external set, though you
say they've global linkage.

Also, how does on locate the DIEs for variables/functions that are listed in
the .debug_pubnames section($ eu-readelf -wpubnames file). The list of
variables/functions that are *defined* in the same compilation unit and are
*visible/accessible from outside* of it.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-11 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #3 from pj dot pandit at yahoo dot co dot in  2010-08-11 12:15 
---
DW_AT_external is meant to indicate whether a variable/function, that is
defined in the compilation unit, is accessible/visible from the outside of it
or not.

It's a subtle difference between `accessible from' and `accessed from' outside.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-11 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #5 from pj dot pandit at yahoo dot co dot in  2010-08-12 05:30 
---
Doesn't the wording - visible outside of its containing compilation unit - ring
any bells?

Secondly, for variables and functions that are not defined in the compilation
unit, it doesn't make sense to mark them as - visible/accessible from outside -
for, that's more than obvious.

Please see: http://gcc.gnu.org/ml/gcc-help/2010-07/msg00266.html

There is another same thread on dwarf-discuss list, but the archives are not
open for the web.

(I think we need a third umpire to pass a reasonable judgement.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] DWARF DW_AT_external flag set for undefined variables

2010-08-02 Thread pj dot pandit at yahoo dot co dot in 


--- Comment #1 from pj dot pandit at yahoo dot co dot in  2010-08-02 18:38 
---
The following patch to gcc-4.4.4 seems to fix the issue for DW_AT_subprogram
DIEs.


$ diff -Naurp gcc-4.4.4/gcc/dwarf2out.c gcc-4.4.4.1/gcc/dwarf2out.c 


--- gcc-4.4.4/gcc/dwarf2out.c   2010-02-10 20:39:06.0 +0530
+++ gcc-4.4.4.1/gcc/dwarf2out.c 2010-08-02 15:16:17.495688080 +0530
@@ -13712,7 +13712,7 @@ gen_subprogram_die (tree decl, dw_die_re
 {
   subr_die = new_die (DW_TAG_subprogram, context_die, decl);

-  if (TREE_PUBLIC (decl))
+  if (TREE_PUBLIC (decl)  !DECL_EXTERNAL (decl))
add_AT_flag (subr_die, DW_AT_external, 1);

   add_name_and_src_coords_attributes (subr_die, decl);
@@ -14163,7 +14163,7 @@ gen_variable_die (tree decl, tree origin
add_type_attribute (var_die, type, TREE_READONLY (decl),
TREE_THIS_VOLATILE (decl), context_die);

-  if (TREE_PUBLIC (decl))
+  if (TREE_PUBLIC (decl)  !DECL_EXTERNAL (decl))
add_AT_flag (var_die, DW_AT_external, 1);

   if (DECL_ARTIFICIAL (decl))


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153

[Bug c++/45153] New: DWARF DW_AT_external flag set for undefined variables

2010-07-31 Thread pj dot pandit at yahoo dot co dot in 
Hi,

As I understand, the DWARF tag DW_AT_external is meant to indicate whether a
variable/function is accessible from outside an object file(compilation unit)
containing a given DWARF DIE - Debugging Information Entry.

But it looks like DW_AT_external is also set for variables/functions defined in
a different object file, but has a DIE because of linking.

See: http://pastebin.com/vFiBWuhh

It has a small C++ program - greeting.cpp, with it's output and some DWARF
information.

As can be seen, the external flag is set for the standard library functions
such as - swscanf, ungetwd, or vfwprintf - which are not defined or used in
greeting.cpp, but are part of the object file because of linking.

This makes it *difficult* to locate the DIEs describing the functions that are
defined and/or used in greeting.cpp.

Thank you.


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   Summary: DWARF DW_AT_external flag set for undefined variables
   Product: gcc
   Version: 4.4.4
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pj dot pandit at yahoo dot co dot in


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45153