Do not stream redundant stuff

as discussed on IRC this adds knob to disable stuff we stream "just for fun"
(or to make it easier to debug streamer desychnonization).

Te size of .o files in gcc subdirectory is reduced form 506MB to 492MB

gcc/

	* lto-streamer-out.c (lto_output_tree): Add streamer_debugging check.
	* lto-streamer.h (streamer_debugging): New constant
	* tree-streamer-in.c (streamer_read_tree_bitfields): Add
	streamer_debugging check.
	(streamer_get_pickled_tree): Likewise.
	* tree-streamer-out.c (pack_ts_base_value_fields): Likewise.

5 files changed, 31 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d584459..a83cc4b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2020-05-25  Jan Hubicka  <hubicka@ucw.cz>
+
+	* lto-streamer-out.c (lto_output_tree): Add streamer_debugging check.
+	* lto-streamer.h (streamer_debugging): New constant
+	* tree-streamer-in.c (streamer_read_tree_bitfields): Add
+	streamer_debugging check.
+	(streamer_get_pickled_tree): Likewise.
+	* tree-streamer-out.c (pack_ts_base_value_fields): Likewise.
+
 2020-05-25  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/95308
diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index 887a51d..288e3c0 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -1748,8 +1748,9 @@ lto_output_tree (struct output_block *ob, tree expr,
 	 will instantiate two different nodes for the same object.  */
       streamer_write_record_start (ob, LTO_tree_pickle_reference);
       streamer_write_uhwi (ob, ix);
-      streamer_write_enum (ob->main_stream, LTO_tags, LTO_NUM_TAGS,
-			   lto_tree_code_to_tag (TREE_CODE (expr)));
+      if (streamer_debugging)
+	streamer_write_enum (ob->main_stream, LTO_tags, LTO_NUM_TAGS,
+			     lto_tree_code_to_tag (TREE_CODE (expr)));
       lto_stats.num_pickle_refs_output++;
     }
   else
diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
index a466fb8..93da3c6 100644
--- a/gcc/lto-streamer.h
+++ b/gcc/lto-streamer.h
@@ -125,6 +125,9 @@ along with GCC; see the file COPYING3.  If not see
 
 typedef unsigned char	lto_decl_flags_t;
 
+/* Stream additional data to LTO object files to make it easier to debug
+   streaming code.  This changes object files.  */
+static const bool streamer_debugging = false;
 
 /* Tags representing the various IL objects written to the bytecode file
    (GIMPLE statements, basic blocks, EH regions, tree nodes, etc).
diff --git a/gcc/tree-streamer-in.c b/gcc/tree-streamer-in.c
index 450f40d..d2e45e3 100644
--- a/gcc/tree-streamer-in.c
+++ b/gcc/tree-streamer-in.c
@@ -487,9 +487,13 @@ streamer_read_tree_bitfields (class lto_input_block *ib,
 
   /* The first word in BP contains the code of the tree that we
      are about to read.  */
-  code = (enum tree_code) bp_unpack_value (&bp, 16);
-  lto_tag_check (lto_tree_code_to_tag (code),
-		 lto_tree_code_to_tag (TREE_CODE (expr)));
+  if (streamer_debugging)
+    {
+      code = (enum tree_code) bp_unpack_value (&bp, 16);
+      lto_tag_check (lto_tree_code_to_tag (code),
+		     lto_tree_code_to_tag (TREE_CODE (expr)));
+    }
+  code = TREE_CODE (expr);
 
   /* Note that all these functions are highly sensitive to changes in
      the types and sizes of each of the fields being packed.  */
@@ -1107,11 +1111,14 @@ streamer_get_pickled_tree (class lto_input_block *ib, class data_in *data_in)
   enum LTO_tags expected_tag;
 
   ix = streamer_read_uhwi (ib);
-  expected_tag = streamer_read_enum (ib, LTO_tags, LTO_NUM_TAGS);
-
   result = streamer_tree_cache_get_tree (data_in->reader_cache, ix);
-  gcc_assert (result
-              && TREE_CODE (result) == lto_tag_to_tree_code (expected_tag));
+
+  if (streamer_debugging)
+    {
+      expected_tag = streamer_read_enum (ib, LTO_tags, LTO_NUM_TAGS);
+      gcc_assert (result
+		  && TREE_CODE (result) == lto_tag_to_tree_code (expected_tag));
+    }
 
   return result;
 }
diff --git a/gcc/tree-streamer-out.c b/gcc/tree-streamer-out.c
index 4e8a12c..94635c4 100644
--- a/gcc/tree-streamer-out.c
+++ b/gcc/tree-streamer-out.c
@@ -71,7 +71,8 @@ write_identifier (struct output_block *ob,
 static inline void
 pack_ts_base_value_fields (struct bitpack_d *bp, tree expr)
 {
-  bp_pack_value (bp, TREE_CODE (expr), 16);
+  if (streamer_debugging)
+    bp_pack_value (bp, TREE_CODE (expr), 16);
   if (!TYPE_P (expr))
     {
       bp_pack_value (bp, TREE_SIDE_EFFECTS (expr), 1);