libdw: Handle split Dwarf Dies in dwarf_die_addr_die.

dwarf_die_addr_die can be used to turn an Dwarf_Die addr back into a
full Dwarf_Die, just given the original Dwarf debug handle. This now
also works for Dwarf_Dies which originated from a split Dwarf. Whenever
a split Dwarf_CU is found the Dwarf it originated from is registered
with the Dwarf that the skeleton Dwarf_CU came from. All registered
split Dwarfs are then searched by dwarf_die_addr_die if the addr didn't
match the main Dwarf or the alt Dwarf.

One limitation in this implementation is that only DIEs that come from
the main .debug_info in the .dwo are supported. Theoretically there could
also be DIEs in an .debug_type or from other/multiple (comdat) sections.

New tests are added for dwarf-4, dwarf-5, split-dwarf-4, split-dwarf-5
and version 4 and 5 dwo files.

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/dwarf-die-addr-die.c b/tests/dwarf-die-addr-die.c
index b4f6dbcd..7899988f 100644
--- a/tests/dwarf-die-addr-die.c
+++ b/tests/dwarf-die-addr-die.c
@@ -134,6 +134,20 @@ check_dbg (Dwarf *dbg)
       res |= check_dbg (alt);
     }
 
+  // Split or Type Dwarf_Dies gotten through dwarf_get_units.
+  Dwarf_CU *cu = NULL;
+  Dwarf_Die subdie;
+  uint8_t unit_type;
+  while (dwarf_get_units (dbg, cu, &cu, NULL,
+                          &unit_type, NULL, &subdie) == 0)
+    {
+      if (dwarf_tag (&subdie) != DW_TAG_invalid)
+        {
+	  printf ("checking %" PRIx8 " subdie\n", unit_type);
+	  res |= check_die (&subdie);
+	}
+    }
+
   return res;
 }