From: Jan Hubicka <jh@suse.cz>
Date: Fri, 22 May 2020 14:37:06 +0000 (+0200)
Subject: Avoid streaming stray references.
X-Git-Tag: releases/gcc-10.3.0~1042
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=23b8829c989079fb164b9be98c73b47cb6f83a8a;p=thirdparty%2Fgcc.git

Avoid streaming stray references.

this patch avoids stremaing completely useless stray references to gobal decl
stream.  I am re-testing the patch (rebased to current tree) on x86_64-linux
and intend to commit once testing finishes.

gcc/ChangeLog:

2020-05-22  Jan Hubicka  <hubicka@ucw.cz>

	* lto-streamer-out.c (lto_output_tree): Do not stream final ref if
	it is not needed.

gcc/lto/ChangeLog:

2020-05-22  Jan Hubicka  <hubicka@ucw.cz>

	* lto-common.c (lto_read_decls): Do not skip stray refs.

(cherry picked from commit bcb63eb2cbd3caf212b9cf42d8c218c09dc6ff8b)
(cherry picked from commit 57400cf273f8052c601d90d86a47705faa17aaa9)
---

diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index 2c3d16799b46..74ea872e5114 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -1746,7 +1746,7 @@ lto_output_tree (struct output_block *ob, tree expr,
 	 it.  */
       if (!existed_p)
 	lto_output_tree_1 (ob, expr, 0, ref_p, this_ref_p);
-      else
+      else if (this_ref_p)
 	{
 	  streamer_write_record_start (ob, LTO_tree_pickle_reference);
 	  streamer_write_uhwi (ob, ix);
diff --git a/gcc/lto/lto-common.c b/gcc/lto/lto-common.c
index 66858a88157c..bcc0919dfc6c 100644
--- a/gcc/lto/lto-common.c
+++ b/gcc/lto/lto-common.c
@@ -1955,25 +1955,19 @@ lto_read_decls (struct lto_file_decl_data *decl_data, const void *data,
       else
 	{
 	  t = lto_input_tree_1 (&ib_main, data_in, tag, 0);
-	  /* We streamed in new tree.  Add it to cache and process dref.  */
-	  if (data_in->reader_cache->nodes.length () == from + 1)
+	  gcc_assert (data_in->reader_cache->nodes.length () == from + 1);
+	  num_unshared_trees_read++;
+	  data_in->location_cache.accept_location_cache ();
+	  process_dref (data_in, t, from);
+	  if (TREE_CODE (t) == IDENTIFIER_NODE
+	      || (TREE_CODE (t) == INTEGER_CST
+		  && !TREE_OVERFLOW (t)))
+	    ;
+	  else
 	    {
-	      num_unshared_trees_read++;
-	      data_in->location_cache.accept_location_cache ();
-	      process_dref (data_in, t, from);
-	      if (TREE_CODE (t) == IDENTIFIER_NODE
-		  || (TREE_CODE (t) == INTEGER_CST
-		      && !TREE_OVERFLOW (t)))
-		;
-	      else
-		{
-		  lto_maybe_register_decl (data_in, t, from);
-		  process_new_tree (t, &hm, from, &total, data_in);
-		}
+	      lto_maybe_register_decl (data_in, t, from);
+	      process_new_tree (t, &hm, from, &total, data_in);
 	    }
-	  else
-	    /* FIXME: It seems useless to pickle stray references.  */
-	    gcc_assert (data_in->reader_cache->nodes.length () == from);
 	}
     }