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List:       gcc-patches
Subject:    Disable loop unswithing for optimize size loops
From:       Jan Hubicka <jh () suse ! cz>
Date:       2008-08-31 15:53:25
Message-ID: 20080831155325.GB24439 () kam ! mff ! cuni ! cz
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Hi,
Tree loop unswitching lacks optimize_loop_for_size_p guard that probably
caused code size increase in FDO SPECfp today.

Honza

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 139830)
+++ ChangeLog	(working copy)
@@ -1,5 +1,10 @@
 2008-08-31  Jan Hubicka  <jh@suse.cz>
 
+	* tree-ssa-loop-unswitch.c (tree_unswitch_single_loop): Check that
+	loop is optimized for speed.
+
+2008-08-31  Jan Hubicka  <jh@suse.cz>
+
 	* postreload-gcse.c (eliminate_partially_redundant_loads): Use optimize_bb_for_size_p.
 	* predict.c (maybe_hot_frequency_p): Make inline.
 	(maybe_hot_count_p): Break out from ...
Index: tree-ssa-loop-unswitch.c
===================================================================
--- tree-ssa-loop-unswitch.c	(revision 139829)
+++ tree-ssa-loop-unswitch.c	(working copy)
@@ -198,6 +198,14 @@ tree_unswitch_single_loop (struct loop *
       return false;
     }
 
+  /* Do not unswitch in cold regions.  */
+  if (optimize_loop_for_size_p (loop))
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, ";; Not unswitching cold loops\n");
+      return false;
+    }
+
   /* The loop should not be too large, to limit code growth.  */
   if (tree_num_loop_insns (loop, &eni_size_weights)
       > (unsigned) PARAM_VALUE (PARAM_MAX_UNSWITCH_INSNS))
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