diff mbox series

Grow GGC after cgraph and summary streaming

Message ID 20191013114420.pxwgf2jnlpw3wjle@kam.mff.cuni.cz
State New
Headers show
Series Grow GGC after cgraph and summary streaming | expand

Commit Message

Jan Hubicka Oct. 13, 2019, 11:44 a.m. UTC 
Hi,
we use ggc_grow to prevent garbage collector from triggering at WPA
time. After streaming in global trees we know that basically all of them
will stay reachable until end of WPA compilation.

This no longer works because tree memory use got down to about 123MB out
of 700MB of GGC memory needed for cc1 build. 
Addition 105MB is used by symbol table and 145 by symbol summaries which
is all explicitly ggc_freed. So I am adding ggc_grow after those two
stremaing steps.  I want to keep all three ggc_grow calls because with
checking collection is triggered and we keep testing that stuff if GGC
safe and no garbage is produced.

We still ggc collect once for cc1 WPA collecing of 118MB of garbage.
I think it is mostly produced by ICF but this needs to be
double-checked.

Bootstrapped/regtested x86_64-linux, comitted.

	* lto-common.c (read_cgraph_and_symbols): Grow ggc memory use after
	summary streaming.
diff mbox series

Patch

Index: lto-common.c
===================================================================
--- lto-common.c	(revision 276935)
+++ lto-common.c	(working copy)
@@ -2781,7 +2781,6 @@  read_cgraph_and_symbols (unsigned nfiles
   /* At this stage we know that majority of GGC memory is reachable.
      Growing the limits prevents unnecesary invocation of GGC.  */
   ggc_grow ();
-  ggc_collect ();
 
   /* Set the hooks so that all of the ipa passes can read in their data.  */
   lto_set_in_hooks (all_file_decl_data, get_section_data, free_section_data);
@@ -2852,7 +2851,11 @@  read_cgraph_and_symbols (unsigned nfiles
   if (tree_with_vars)
     ggc_free (tree_with_vars);
   tree_with_vars = NULL;
-  ggc_collect ();
+  /* During WPA we want to prevent ggc collecting by default.  Grow limits
+     until after the IPA summaries are streamed in.  Basically all IPA memory
+     is explcitly managed by ggc_free and ggc collect is not useful.
+     Exception are the merged declarations.  */
+  ggc_grow ();
 
   timevar_pop (TV_IPA_LTO_DECL_MERGE);
   /* Each pass will set the appropriate timer.  */
@@ -2866,6 +2869,8 @@  read_cgraph_and_symbols (unsigned nfiles
   else
     ipa_read_summaries ();
 
+  ggc_grow ();
+
   for (i = 0; all_file_decl_data[i]; i++)
     {
       gcc_assert (all_file_decl_data[i]->symtab_node_encoder);