[PATCH 7/8] Output BTF DECL_TAG and TYPE_TAG types

[David Faust via Gcc-patches]

This patch updates btfout.cc to be aware of the DECL_TAG and TYPE_TAG
kinds and output them appropriately.

gcc/

        * btfout.cc (get_btf_kind): Handle TYPE_TAG and DECL_TAG kinds.
        (btf_calc_num_vbytes): Likewise.
        (btf_asm_type): Likewise.
        (output_asm_btf_vlen_bytes): Likewise.
---
 gcc/btfout.cc | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/gcc/btfout.cc b/gcc/btfout.cc
index 31af50521da..f291cd925be 100644
--- a/gcc/btfout.cc
+++ b/gcc/btfout.cc
@@ -136,6 +136,8 @@ get_btf_kind (uint32_t ctf_kind)
     case CTF_K_VOLATILE: return BTF_KIND_VOLATILE;
     case CTF_K_CONST:    return BTF_KIND_CONST;
     case CTF_K_RESTRICT: return BTF_KIND_RESTRICT;
+    case CTF_K_TYPE_TAG: return BTF_KIND_TYPE_TAG;
+    case CTF_K_DECL_TAG: return BTF_KIND_DECL_TAG;
     default:;
     }
   return BTF_KIND_UNKN;
@@ -201,6 +203,7 @@ btf_calc_num_vbytes (ctf_dtdef_ref dtd)
     case BTF_KIND_CONST:
     case BTF_KIND_RESTRICT:
     case BTF_KIND_FUNC:
+    case BTF_KIND_TYPE_TAG:
     /* These kinds have no vlen data.  */
       break;
 
@@ -238,6 +241,10 @@ btf_calc_num_vbytes (ctf_dtdef_ref dtd)
       vlen_bytes += vlen * sizeof (struct btf_var_secinfo);
       break;
 
+    case BTF_KIND_DECL_TAG:
+      vlen_bytes += sizeof (struct btf_decl_tag);
+      break;
+
     default:
       break;
     }
@@ -636,6 +643,22 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
       dw2_asm_output_data (4, dtd->dtd_data.ctti_size, "btt_size: %uB",
                           dtd->dtd_data.ctti_size);
       return;
+    case BTF_KIND_DECL_TAG:
+      {
+       /* A decl tag might refer to (be the child DIE of) a variable. Try to
+          lookup the parent DIE's CTF variable, and if it exists point to the
+          corresponding BTF variable. This is an odd construction - we have a
+          'type' which refers to a variable, rather than the reverse.  */
+       dw_die_ref parent = dw_get_die_parent (dtd->dtd_key);
+       ctf_dvdef_ref dvd = ctf_dvd_lookup (ctfc, parent);
+       if (dvd)
+         {
+           unsigned int var_id =
+             *(btf_var_ids->get (dvd)) + num_types_added + 1;
+           dw2_asm_output_data (4, var_id, "btt_type");
+           return;
+         }
+      }
     default:
       break;
     }
@@ -949,6 +972,11 @@ output_asm_btf_vlen_bytes (ctf_container_ref ctfc, 
ctf_dtdef_ref dtd)
         at this point.  */
       gcc_unreachable ();
 
+    case BTF_KIND_DECL_TAG:
+      dw2_asm_output_data (4, dtd->dtd_u.dtu_btfnote.component_idx,
+                          "decltag_compidx");
+      break;
+
     default:
       /* All other BTF type kinds have no variable length data.  */
       break;
-- 
2.35.1