2013-06-10 Cary Coutant <ccoutant@google.com>

gcc/
	* dwarf2out.c (hash_external_ref): Use die_symbol or signature
	for hash so that hash table traversal order is deterministic.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@199927 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 16 insertions, 1 deletions

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index b615b181a3b..f42ad66353b 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -7388,7 +7388,22 @@ struct external_ref_hasher : typed_free_remove <external_ref>
 inline hashval_t
 external_ref_hasher::hash (const value_type *r)
 {
-  return htab_hash_pointer (r->type);
+  dw_die_ref die = r->type;
+  hashval_t h = 0;
+
+  /* We can't use the address of the DIE for hashing, because
+     that will make the order of the stub DIEs non-deterministic.  */
+  if (! die->comdat_type_p)
+    /* We have a symbol; use it to compute a hash.  */
+    h = htab_hash_string (die->die_id.die_symbol);
+  else
+    {
+      /* We have a type signature; use a subset of the bits as the hash.
+	 The 8-byte signature is at least as large as hashval_t.  */
+      comdat_type_node_ref type_node = die->die_id.die_type_node;
+      memcpy (&h, type_node->signature, sizeof (h));
+    }
+  return h;
 }
 
 inline bool