Patchwork PR debug/49047 (linkage name missing for cdtors)

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Submitter Dodji Seketeli
Date May 26, 2011, 8:03 p.m.
Message ID <m3wrhdp6ui.fsf@seketeli.org>
Download mbox | patch
Permalink /patch/97621/
State New
Headers show

Comments

Dodji Seketeli - May 26, 2011, 8:03 p.m.
Jason Merrill <jason@redhat.com> a écrit:

> Why not just call add_linkage_name after add_abstract_origin_attribute?

That is what I first did and it worked for this case.  But then I wasn't
sure if there could be cases where a function DIE would have the
DW_AT_abstract_origin set, but won't have any actual code? For instance
if the function has DECL_EXTERNAL set.  That's why I wanted to call
add_linkage_name only if the function has DW_AT_{low,high}_pc so that I
am sure it contains actual code.

If my concern is not justified then I guess the patch below should be
enough then.

gcc/

	* dwarf2out.c (gen_subprogram_die): Emit linkage name attribute
	for functions containing actual code for public cloned abstract
	functions.

gcc/testsuite/

	* g++.dg/debug/dwarf2/cdtor-1.C: New test.
---
 gcc/dwarf2out.c                             |    7 +++++++
 gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C |   17 +++++++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
Jason Merrill - May 27, 2011, 4:43 a.m.
On 05/26/2011 04:03 PM, Dodji Seketeli wrote:
> That is what I first did and it worked for this case.  But then I wasn't
> sure if there could be cases where a function DIE would have the
> DW_AT_abstract_origin set, but won't have any actual code? For instance
> if the function has DECL_EXTERNAL set.  That's why I wanted to call
> add_linkage_name only if the function has DW_AT_{low,high}_pc so that I
> am sure it contains actual code.

I think that we only generate debug info for a function if we emit it, 
so it should always have pc attributes.  But you could try adding an 
assert to see if I'm right.

> +      if (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);

add_name_and_src_coords_attributes doesn't check TREE_PUBLIC, so I don't 
think we should here, either; we want the debugger to be able to find 
cloned constructors in anonymous namespaces, too.

Jason

Patch

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 55453a3..0cf782f 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -19636,6 +19636,13 @@  gen_subprogram_die (tree decl, dw_die_ref context_die)
 
       subr_die = new_die (DW_TAG_subprogram, context_die, decl);
       add_abstract_origin_attribute (subr_die, origin);
+      if (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);
     }
   else if (old_die)
     {
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C b/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
new file mode 100644
index 0000000..6d39e54
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/cdtor-1.C
@@ -0,0 +1,17 @@ 
+// origin PR debug/49047
+// { dg-options "-g -dA" }
+// { dg-do compile }
+
+struct K
+{
+  K () { }
+  ~K () { }
+};
+
+int
+main()
+{
+    K k;
+}
+
+// { dg-final {scan-assembler-times "\[^\n\r\]*DW_AT_MIPS_linkage_name:" 2 } }