Re: [PATCH] Assert we don't create recursive DW_AT_abstract_origin

[Jason Merrill]

On 10/30/23 08:57, Richard Biener wrote:
We have a support case that shows GCC 7 sometimes creates
DW_TAG_label refering to itself via a DW_AT_abstract_origin
when using LTO.  This for example triggers the sanity check
added below during LTO bootstrap.
Making this check cover more than just DW_AT_abstract_origin
breaks bootstrap on trunk for

       /* GNU extension: Record what type our vtable lives in.  */
       if (TYPE_VFIELD (type))
         {
           tree vtype = DECL_FCONTEXT (TYPE_VFIELD (type));

           gen_type_die (vtype, context_die);
           add_AT_die_ref (type_die, DW_AT_containing_type,
                           lookup_type_die (vtype));

so the check is for now restricted to DW_AT_abstract_origin.

Bootstrapped on x86_64-unknown-linux-gnu, OK?

Let's also check for DW_AT_specification, since that's the other one 
get_AT follows.  OK with that change.

My workaround for the GCC 7 problem is

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 5590845d2a4..07185a1a0d3 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -23030,7 +23031,7 @@ gen_label_die (tree decl, dw_die_ref context_die)
        lbl_die = new_die (DW_TAG_label, context_die, decl);
        equate_decl_number_to_die (decl, lbl_die);
  
-      if (origin != NULL)
+      if (origin != NULL && origin != decl)
         add_abstract_origin_attribute (lbl_die, origin);
        else
         add_name_and_src_coords_attributes (lbl_die, decl);

that's not needed on trunk because there we dont' end up
with LABEL_DECLs with self-DECL_ABSTRACT_ORIGIN (and not DECL_ABSTRACT).

Thanks,
Richard.

        * dwarf2out.cc (add_AT_die_ref): Assert we do not add
        a self-ref DW_AT_abstract_origin.
---
  gcc/dwarf2out.cc | 1 +
  1 file changed, 1 insertion(+)

diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index 1e0cec66c5e..0070a9e8412 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -4908,6 +4908,7 @@ add_AT_die_ref (dw_die_ref die, enum dwarf_attribute 
attr_kind, dw_die_ref targ_
  {
    dw_attr_node attr;
    gcc_checking_assert (targ_die != NULL);
+  gcc_assert (targ_die != die || attr_kind != DW_AT_abstract_origin);
  
    /* With LTO we can end up trying to reference something we didn't create
       a DIE for.  Avoid crashing later on a NULL referenced DIE.  */