[PATCH] New flag to apply SMS when SC equals 1 (Second try)

[Revital Eres]

Hello,

Following Richard's suggestion here is the patch again.
Tested on ppc64-redhat-linux.

OK for mainline?

Thanks,
Revital


Changelog

        * params.def (sms-min-sc): New param flag.
        * modulo-sched.c (sms_schedule): Use it.

=== modified file 'gcc/modulo-sched.c'
--- gcc/modulo-sched.c  2011-03-27 07:11:08 +0000
+++ gcc/modulo-sched.c  2011-04-17 06:24:21 +0000
@@ -1222,9 +1222,10 @@ sms_schedule (void)
          PS_STAGE_COUNT(ps) = stage_count;
        }
       
-      /* Stage count of 1 means that there is no interleaving between
-         iterations, let the scheduling passes do the job.  */
-      if (stage_count <= 1
+      /* The default value of PARAM_SMS_MIN_SC is 2 as stage count of
+        1 means that there is no interleaving between iterations thus
+        we let the scheduling passes do the job in this case.  */
+      if (stage_count < (unsigned) PARAM_VALUE (PARAM_SMS_MIN_SC)
          || (count_init && (loop_count <= stage_count))
          || (flag_branch_probabilities && (trip_count <= stage_count)))
        {

=== modified file 'gcc/params.def'
--- gcc/params.def      2011-02-02 15:52:08 +0000
+++ gcc/params.def      2011-04-17 05:48:44 +0000
@@ -344,6 +344,11 @@ DEFPARAM(PARAM_SMS_MAX_II_FACTOR,
         "sms-max-ii-factor",
         "A factor for tuning the upper bound that swing modulo scheduler uses 
for scheduling a loop",
         100, 0, 0)
+/* The minimum value of stage count that swing modulo scheduler will generate. 
 */
+DEFPARAM(PARAM_SMS_MIN_SC,
+        "sms-min-sc",
+        "The minimum value of stage count that swing modulo scheduler will 
generate.",
+        2, 1, 1)
 DEFPARAM(PARAM_SMS_DFA_HISTORY,
         "sms-dfa-history",
         "The number of cycles the swing modulo scheduler considers when 
checking conflicts using DFA",