[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.  */