[committed] Verify that head of dup-chain is not removed

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

Hi,

Check in verify_dups that the head of a duplicate chain has the die_removed
field set to 0, and fix resulting verification failure in split_dups.

Tested with verify_dups_p set on by default.

Committed to trunk.

Thanks,
- Tom

Verify that head of dup-chain is not removed

2020-01-20  Tom de Vries  <tdevries@suse.de>

	* dwz.c (verify_dups): Check that the head of a duplicate chain has the
	die_removed field set to 0.
	(split_dups): Make sure that the head of a duplicate chain has the
	die_removed field set to 0.

---
 dwz.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/dwz.c b/dwz.c
index 0e4148f..9702152 100644
--- a/dwz.c
+++ b/dwz.c
@@ -4413,6 +4413,7 @@ verify_dups (dw_die_ref die, bool ordered)
 
   assert (die->die_dup == NULL);
   assert (die->die_collapsed_children == 0);
+  assert (die->die_remove == 0);
 
   for (prev = die, d = prev->die_nextdup;
        d;
@@ -6517,13 +6518,14 @@ split_dups (dw_die_ref die, struct obstack *vec)
       merge_dups (def, decls);
     }
 
-  /* If some DIEs are no longer part of a duplicate chain, don't remove
-     them.  */
   for (i = 0; i < count; i++)
     {
       d = arr[i];
-      if (d->die_dup == NULL
-	  && d->die_nextdup == NULL)
+      if (d->die_dup == NULL)
+	/* If DIE is now either:
+	   - no longer part of a duplicate chain, or
+	   - head of a duplicate chain,
+	   don't remove it.  */
 	d->die_remove = 0;
     }