re PR middle-end/39157 (Code that compiles fine in 1GB of memory with 4.1.2 requires > 20GB in 4.2.* and higher)

	PR middle-end/39157
	* Makefile.in (loop-invariant.o): Depend on $(PARAMS_H).
	* params.h (LOOP_INVARIANT_MAX_BBS_IN_LOOP): Define.
	* params.def (loop-invariant-max-bbs-in-loop): New parameter.
	* opts.c (decode_options): Set loop-invariant-max-bbs-in-loop
	parameter to 1000 for -O1 by default.
	* doc/invoke.texi (loop-invariant-max-bbs-in-loop): Document new
	parameter.
	* loop-invariant.c: Include params.h.
	(move_loop_invariants): Don't call move_single_loop_invariants on
	very large loops.

From-SVN: r144320

1 files changed, 8 insertions, 1 deletions

diff --git a/gcc/opts.c b/gcc/opts.c
index cccb80b..8ae79ae 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -1,5 +1,5 @@
 /* Command line option handling.
-   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
    Contributed by Neil Booth.
 
@@ -811,6 +811,7 @@ decode_options (unsigned int argc, const char **argv)
   static int initial_avg_aliased_vops;
   static int initial_min_crossjump_insns;
   static int initial_max_fields_for_field_sensitive;
+  static int initial_loop_invariant_max_bbs_in_loop;
   static unsigned int initial_lang_mask;
 
   unsigned int i, lang_mask;
@@ -833,6 +834,8 @@ decode_options (unsigned int argc, const char **argv)
 	= compiler_params[PARAM_MIN_CROSSJUMP_INSNS].value;
       initial_max_fields_for_field_sensitive
 	= compiler_params[PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE].value;
+      initial_loop_invariant_max_bbs_in_loop
+	= compiler_params[PARAM_LOOP_INVARIANT_MAX_BBS_IN_LOOP].value;
     }
   else
     lang_mask = initial_lang_mask;
@@ -943,6 +946,10 @@ decode_options (unsigned int argc, const char **argv)
   set_param_value ("max-fields-for-field-sensitive",
 		   (opt2) ? 100 : initial_max_fields_for_field_sensitive);
 
+  /* For -O1 only do loop invariant motion for very small loops.  */
+  set_param_value ("loop-invariant-max-bbs-in-loop",
+		   (opt2) ? initial_loop_invariant_max_bbs_in_loop : 1000);
+
   /* -O3 optimizations.  */
   opt3 = (optimize >= 3);
   flag_predictive_commoning = opt3;