[Bug debug/49047] New: DW_AT_linkage_name missing for constructors and destructors

[Bug debug/49047] New: DW_AT_linkage_name missing for constructors and destructors

[tromey at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

           Summary: DW_AT_linkage_name missing for constructors and
                    destructors
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tromey@gcc.gnu.org


Compile this with -g:

struct K
{
  K () { }
  ~K () { }

  int m () { return 5; }
};

K k;


If you run 'readelf -wi' on it, you will see that 'm' has a linkage name:

 <2><66>: Abbrev Number: 5 (DW_TAG_subprogram)
    <67>   DW_AT_external    : 1        
    <68>   DW_AT_name        : m        
    <6a>   DW_AT_decl_file   : 1        
    <6b>   DW_AT_decl_line   : 6        
    <6c>   DW_AT_MIPS_linkage_name: (indirect string, offset: 0x76): _ZN1K1mEv  

However, the constructors and destructor do not.

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-05-19 08:17:48 UTC ---
My guess is that's because there is no single symbol for them, but two or
three.

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at seketeli dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #2 from dodji at seketeli dot org <dodji at seketeli dot org> 2011-05-25 15:15:03 UTC ---
The candidate patch below might do what you want.

Note that, constructors/destructor functions are cloned.  The cloning
process yields a DIE tree.  So the destructor K::~K is represented by an
abstract function DIE.  There is then a concrete function DIE (let's
call it 'foo'), that would effectively contain the code of K::~K, and
which DW_AT_abstract_origin points to the DIE of the abstract function.
It's for 'foo' that the patch below emits the linkage name.  Is this
enough for your need?

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 55453a3..c49f90a 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -19601,6 +19601,7 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
   dw_die_ref old_die = lookup_decl_die (decl);
   int declaration = (current_function_decl != decl
              || class_or_namespace_scope_p (context_die));
+  bool fn_has_code_addr_p = false;

   premark_used_types ();

@@ -19769,6 +19770,7 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
           /* We have already generated the labels.  */
           add_AT_lbl_id (subr_die, DW_AT_low_pc, fde->dw_fde_begin);
           add_AT_lbl_id (subr_die, DW_AT_high_pc, fde->dw_fde_end);
+          fn_has_code_addr_p = true;
         }
       else
         {
@@ -19780,6 +19782,7 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
           ASM_GENERATE_INTERNAL_LABEL (label_id, FUNC_END_LABEL,
                        current_function_funcdef_no);
           add_AT_lbl_id (subr_die, DW_AT_high_pc, label_id);
+          fn_has_code_addr_p = true;
         }

 #if VMS_DEBUGGING_INFO
@@ -19928,7 +19931,15 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)

       if (cfun->static_chain_decl)
     add_AT_location_description (subr_die, DW_AT_static_link,
-         loc_list_from_tree (cfun->static_chain_decl, 2));
+         loc_list_from_tree (cfun->static_chain_decl, 2));      
+
+      if (fn_has_code_addr_p && origin && TREE_PUBLIC (origin))
+    /*  So this is where the actual code for a publicly accessible
+        cloned function is.  Let's emit linkage name attribute for
+        it.  This helps debuggers to e.g, set breakpoints into
+        constructors/destructors when the user asks "break
+        K::K".  */
+    add_linkage_name (subr_die, decl);
     }

   /* Generate child dies for template paramaters.  */

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[tromey at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #3 from Tom Tromey <tromey at gcc dot gnu.org> 2011-05-25 18:00:23 UTC ---
I tried this patch on a simple example and I think the
output looks good.

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at seketeli dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #4 from dodji at seketeli dot org <dodji at seketeli dot org> 2011-05-27 09:09:35 UTC ---
A candidate patch was posted to
http://gcc.gnu.org/ml/gcc-patches/2011-05/msg02044.html

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #5 from Dodji Seketeli <dodji at gcc dot gnu.org> 2011-05-31 12:09:10 UTC ---
Author: dodji
Date: Tue May 31 12:09:06 2011
New Revision: 174472

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=174472
Log:
Fix PR debug/49047

gcc/

    * dwarf2out.c (gen_subprogram_die): Emit linkage name attribute
    for concrete functions containing the code of cloned functions.

gcc/testsuite/

    * g++.dg/debug/dwarf2/cdtor-1.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.c
    trunk/gcc/testsuite/ChangeLog

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #6 from Dodji Seketeli <dodji at gcc dot gnu.org> 2011-05-31 12:17:12 UTC ---
Author: dodji
Date: Tue May 31 12:17:06 2011
New Revision: 174473

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=174473
Log:
Revert "Fix PR debug/49047"

This reverts commit ce20032a8ad4d9d4fa37192e2ecc73cb257094e8.

Added:
    trunk/libjava/sysdep/x86-64/locks.h
      - copied, changed from r174472, trunk/libjava/sysdep/i386/locks.h
Removed:
    trunk/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.c
    trunk/gcc/testsuite/ChangeLog
    trunk/libjava/ChangeLog
    trunk/libjava/configure.host
    trunk/libjava/sysdep/i386/locks.h

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

--- Comment #7 from Dodji Seketeli <dodji at gcc dot gnu.org> 2011-05-31 12:17:25 UTC ---
Author: dodji
Date: Tue May 31 12:17:21 2011
New Revision: 174474

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=174474
Log:
Fix PR debug/49047

gcc/

    * dwarf2out.c (gen_subprogram_die): Emit linkage name attribute
    for concrete functions containing the code of cloned functions.

gcc/testsuite/

    * g++.dg/debug/dwarf2/cdtor-1.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.c
    trunk/gcc/testsuite/ChangeLog

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

Dodji Seketeli <dodji at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011.05.31 16:16:36
         AssignedTo|unassigned at gcc dot       |dodji at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

[Bug debug/49047] DW_AT_linkage_name missing for constructors and destructors

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49047

Dodji Seketeli <dodji at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #8 from Dodji Seketeli <dodji at gcc dot gnu.org> 2011-05-31 16:16:56 UTC ---
Fixed in trunk (4.7)