lra: make reload_pseudo_compare_func a proper comparator

	PR rtl-optimization/57878
	PR rtl-optimization/68988
	* lra-assigns.c (reload_pseudo_compare_func): Remove fragmentation
	avoidance test involving non_reload_pseudos.  Move frequency test
	below the general fragmentation avoidance test.

From-SVN: r252972

gcc/ChangeLog

+2017-09-19  Alexander Monakov  <amonakov@ispras.ru>
+
+	PR rtl-optimization/57878
+	PR rtl-optimization/68988
+	* lra-assigns.c (reload_pseudo_compare_func): Remove fragmentation
+	avoidance test involving non_reload_pseudos.  Move frequency test
+	below the general fragmentation avoidance test.
+
 2017-09-19  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/69728

gcc/lra-assigns.c

@@ -211,24 +211,15 @@ reload_pseudo_compare_func (const void *v1p, const void *v2p)
   if ((diff = (ira_class_hard_regs_num[cl1]
 	       - ira_class_hard_regs_num[cl2])) != 0)
     return diff;
-  if ((diff
-       = (ira_reg_class_max_nregs[cl2][lra_reg_info[r2].biggest_mode]
-	  - ira_reg_class_max_nregs[cl1][lra_reg_info[r1].biggest_mode])) != 0
-      /* The code below executes rarely as nregs == 1 in most cases.
-	 So we should not worry about using faster data structures to
-	 check reload pseudos.  */
-      && ! bitmap_bit_p (&non_reload_pseudos, r1)
-      && ! bitmap_bit_p (&non_reload_pseudos, r2))
-    return diff;
-  if ((diff = (regno_assign_info[regno_assign_info[r2].first].freq
-	       - regno_assign_info[regno_assign_info[r1].first].freq)) != 0)
-    return diff;
   /* Allocate bigger pseudos first to avoid register file
      fragmentation.  */
   if ((diff
        = (ira_reg_class_max_nregs[cl2][lra_reg_info[r2].biggest_mode]
 	  - ira_reg_class_max_nregs[cl1][lra_reg_info[r1].biggest_mode])) != 0)
     return diff;
+  if ((diff = (regno_assign_info[regno_assign_info[r2].first].freq
+	       - regno_assign_info[regno_assign_info[r1].first].freq)) != 0)
+    return diff;
   /* Put pseudos from the thread nearby.  */
   if ((diff = regno_assign_info[r1].first - regno_assign_info[r2].first) != 0)
     return diff;