[committed] Fix get_name in low-mem mode

[Tom de Vries <tdevries@suse.de>]

Hi,

When using --devel-dump-dups in low-mem mode for benchmark cc1 I run into a
segfault:
...
$ dwz cc1 -o 1 -l0 --devel-dump-dups
   ...
Segmentation fault (core dumped)
...

The segfault happens in get_AT (called from get_AT_string, called from
get_name) due to trying to access invalidated fields in a DIE with
die_collapsed_child set.

Fix this by handling die_collapsed_child DIEs in get_name.

Committed to trunk.

Thanks,
- Tom

Fix get_name in low-mem mode

2020-01-08  Tom de Vries  <tdevries@suse.de>

	* dwz.c (get_name): Handle die->die_collapsed_child == 1.

---
 dwz.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dwz.c b/dwz.c
index 8fac945..b4b8339 100644
--- a/dwz.c
+++ b/dwz.c
@@ -4380,6 +4380,8 @@ find_dups_fi (dw_die_ref parent)
 static const char *
 get_name (dw_die_ref die)
 {
+  if (die->die_collapsed_child)
+    return NULL;
   const char *name = get_AT_string (die, DW_AT_name);
   if (name)
     return name;