* Makefile.in (ggc-common.o): Depend on $(PARAMS_H)

	* doc/invoke.texi (ggc-min-expand, ggc-min-heapsize): Update
	documentation.
	* ggc-common.c: Include params.h
	(ggc_min_expand_heuristic, ggc_min_heapsize_heuristic,
	init_ggc_heuristics): New functions.
	* ggc.h (ggc_min_expand_heuristic, ggc_min_heapsize_heuristic,
	init_ggc_heuristics): Prototype.
	* toplev.c (print_version):  Output GGC heuristics.
	(parse_options_and_default_flags): Call init_ggc_heuristics.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@63268 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 41 insertions, 0 deletions

diff --git a/gcc/ggc-common.c b/gcc/ggc-common.c
index e9c2f020668..8a8f7ecd313 100644
--- a/gcc/ggc-common.c
+++ b/gcc/ggc-common.c
@@ -27,6 +27,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "hashtab.h"
 #include "ggc.h"
 #include "toplev.h"
+#include "params.h"
 
 #ifdef HAVE_MMAP_FILE
 # include <sys/mman.h>
@@ -624,3 +625,43 @@ gt_pch_restore (f)
 
   gt_pch_restore_stringpool ();
 }
+
+/* Heuristic to set a default for GGC_MIN_EXPAND.  */
+int
+ggc_min_expand_heuristic()
+{
+  double min_expand = physmem_total();
+  
+  /* The heuristic is a percentage equal to 30% + 70%*(RAM/1GB), yielding
+     a lower bound of 30% and an upper bound of 100% (when RAM >= 1GB).  */
+  min_expand /= 1024*1024*1024;
+  min_expand *= 70;
+  min_expand = MIN (min_expand, 70);
+  min_expand += 30;
+
+  return min_expand;
+}
+
+/* Heuristic to set a default for GGC_MIN_HEAPSIZE.  */
+int
+ggc_min_heapsize_heuristic()
+{
+  double min_heap_kbytes = physmem_total() / 1024;
+  
+  /* The heuristic is RAM/8, with a lower bound of 4M and an upper
+     bound of 128M (when RAM >= 1GB).  */
+  min_heap_kbytes /= 8;
+  min_heap_kbytes = MAX (min_heap_kbytes, 4 * 1024);
+  min_heap_kbytes = MIN (min_heap_kbytes, 128 * 1024);
+
+  return min_heap_kbytes;
+}
+
+void
+init_ggc_heuristics ()
+{
+#ifndef ENABLE_GC_ALWAYS_COLLECT
+  set_param_value ("ggc-min-expand", ggc_min_expand_heuristic());
+  set_param_value ("ggc-min-heapsize", ggc_min_heapsize_heuristic());
+#endif
+}