[PATCH] Fix PR49365

Richard Guenther rguenther@suse.de
Wed Jun 22 14:18:00 GMT 2011


This fixes the prefetching regression caused by rev. 166552 by
adjusting the default min-insn-to-prefetch-ratio.  I benchmarked
SPEC2006 with this change on AMD hardware (where prefetching
is on by default) and apart from recovering the 436.cactusADM
regression there is no other change in performance.

Also bootstrapped and tested on x86_64-unknown-linux-gnu.

I'll wait for comments before committing.

Richard.

2011-06-22  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/49365
	* params.def (min-insn-to-prefetch-ratio): Reduce from 10 to 9.

Index: gcc/params.def
===================================================================
--- gcc/params.def	(revision 175293)
+++ gcc/params.def	(working copy)
@@ -825,7 +825,7 @@ DEFPARAM (PARAM_MIN_INSN_TO_PREFETCH_RAT
 	  "min-insn-to-prefetch-ratio",
 	  "Min. ratio of insns to prefetches to enable prefetching for "
           "a loop with an unknown trip count",
-	  10, 0, 0)
+	  9, 0, 0)
 
 DEFPARAM (PARAM_PREFETCH_MIN_INSN_TO_MEM_RATIO,
 	  "prefetch-min-insn-to-mem-ratio",



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