Fix for PR debug/PR46973

Fix for PR debug/PR46973

[Dodji Seketeli]

Hello,

In the example of the patch below the type that is used
Base<long, 47, &a_global, &S::f>::Inner<float> so its
DW_TAG_structure_type is marked as used and is eventually emitted.

The parent DW_TAG_structure_type DIE of Base<long, 47, &a_global,
&S::f> is also rightfully marked as used by
prune_unused_types_mark. The problem is the
DW_TAG_template_type_param and DW_TAG_template_value_param
children DIEs are not marked as used so they are not emitted. As
these DIEs are necessary to fully describe the name of a type, I
think they should be treated by prune_unused_types_mark as it
treats nodes referenced by attributes.

The patch below marks the template parameters and argument related
children DIEs.

Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk.

-- 
	Dodji

commit b13e7d25b5f0a7e9fdd587ca2c5a2ca17aae3628
Author: Dodji Seketeli <dodji@redhat.com>
Date:   Wed Dec 15 23:30:30 2010 +0100

    Fix PR debug/PR46973
    
    gcc/
    
    	* dwarf2out.c (prune_unused_types_mark_generic_parms_dies): New
    	static function.
    	(prune_unused_types_mark): Use it.
    
    gcc/testsuite/
    
    	* g++.dg/debug/dwarf2/template-params-9.C: New test.

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index c985527..4097358 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -6477,6 +6477,7 @@ static void output_loc_list (dw_loc_list_ref);
 static char *gen_internal_sym (const char *);
 
 static void prune_unmark_dies (dw_die_ref);
+static void prune_unused_types_mark_generic_parms_dies (dw_die_ref);
 static void prune_unused_types_mark (dw_die_ref, int);
 static void prune_unused_types_walk (dw_die_ref);
 static void prune_unused_types_walk_attribs (dw_die_ref);
@@ -22126,6 +22127,32 @@ prune_unused_types_walk_attribs (dw_die_ref die)
     }
 }
 
+/* Mark the generic parameters and arguments children DIEs of DIE.  */
+
+static void
+prune_unused_types_mark_generic_parms_dies (dw_die_ref die)
+{
+  dw_die_ref c;
+
+  if (die == NULL || die->die_child == NULL)
+    return;
+  c = die->die_child;
+  do
+    {
+      switch (c->die_tag)
+	{
+	case DW_TAG_template_type_param:
+	case DW_TAG_template_value_param:
+	case DW_TAG_GNU_template_template_param:
+	case DW_TAG_GNU_template_parameter_pack:
+	  prune_unused_types_mark (c, 1);
+	  break;
+	default:
+	  break;
+	}
+      c = c->die_sib;
+    } while (c && c != die->die_child);
+}
 
 /* Mark DIE as being used.  If DOKIDS is true, then walk down
    to DIE's children.  */
@@ -22139,6 +22166,10 @@ prune_unused_types_mark (dw_die_ref die, int dokids)
     {
       /* We haven't done this node yet.  Mark it as used.  */
       die->die_mark = 1;
+      /* If this is the DIE of a generic type instantiation,
+	 mark the children DIEs that describe its generic parms and
+	 args.  */
+      prune_unused_types_mark_generic_parms_dies (die);
 
       /* We also have to mark its parents as used.
 	 (But we don't want to mark our parents' kids due to this.)  */
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/template-params-9.C b/gcc/testsuite/g++.dg/debug/dwarf2/template-params-9.C
new file mode 100644
index 0000000..7af1d91
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/template-params-9.C
@@ -0,0 +1,28 @@
+// Origin PR debug/PR46973
+// { dg-options "-g -dA" }
+// { dg-do compile }
+
+struct S
+{
+  int f;
+};
+
+template<typename T, int I, int *P, int S::*MP>
+struct Base
+{
+  template<typename Z>
+  struct Inner
+  {
+  };
+};
+
+int a_global;
+
+int main ()
+{
+  Base<long, 47, &a_global, &S::f>::Inner<float> inner;
+  return 0;
+}
+
+// { dg-final { scan-assembler-times "DIE \\(\[^\n\r\]*\\) DW_TAG_template_type_param" 2 } }
+// { dg-final { scan-assembler-times "DIE \\(\[^\n\r\]*\\) DW_TAG_template_value_param" 3 } }

Re: Fix for PR debug/PR46973

[Jason Merrill]

OK.  Do we also need this for function template args?

Jason

Re: Fix for PR debug/PR46973

[Dodji Seketeli]

Jason Merrill <jason@redhat.com> writes:

> OK.  Do we also need this for function template args?

As cgraph tells dwarf2out what function to emit, it doesn't have to
prune functions (and their template args) like for types so I believe we
don't have the issue for them.

-- 
		Dodji