ira-build.c (update_conflict_hard_reg_costs): New.

        * ira-build.c (update_conflict_hard_reg_costs): New.
        (ira_build): Call update_conflict_hard_reg_costs.

From-SVN: r159830

gcc/ChangeLog

+2010-05-25  Vladimir Makarov <vmakarov@redhat.com>
+
+	* ira-build.c (update_conflict_hard_reg_costs): New.
+	(ira_build): Call update_conflict_hard_reg_costs.
+
 2010-05-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/41371

gcc/ira-build.c

 /* Building internal representation for IRA.
-   Copyright (C) 2006, 2007, 2008, 2009
+   Copyright (C) 2006, 2007, 2008, 2009, 2010
    Free Software Foundation, Inc.
    Contributed by Vladimir Makarov <vmakarov@redhat.com>.
 
@@ -2757,6 +2757,44 @@ check_allocno_creation (void)
 }
 #endif
 
+/* Identify allocnos which prefer a register class with a single hard register.
+   Adjust ALLOCNO_CONFLICT_HARD_REG_COSTS so that conflicting allocnos are
+   less likely to use the preferred singleton register.  */
+static void
+update_conflict_hard_reg_costs (void)
+{
+  ira_allocno_t a;
+  ira_allocno_iterator ai;
+  int i, index, min;
+
+  FOR_EACH_ALLOCNO (a, ai)
+    {
+      enum reg_class cover_class = ALLOCNO_COVER_CLASS (a);
+      enum reg_class pref = reg_preferred_class (ALLOCNO_REGNO (a));
+
+      if (reg_class_size[pref] != 1)
+	continue;
+      index = (ira_class_hard_reg_index[cover_class]
+	       [ira_class_hard_regs[pref][0]]);
+      if (index < 0)
+	continue;
+      if (ALLOCNO_CONFLICT_HARD_REG_COSTS (a) == NULL
+	  || ALLOCNO_HARD_REG_COSTS (a) == NULL)
+	continue;
+      min = INT_MAX;
+      for (i = ira_class_hard_regs_num[cover_class] - 1; i >= 0; i--)
+	if (ALLOCNO_HARD_REG_COSTS (a)[i] > ALLOCNO_COVER_CLASS_COST (a)
+	    && min > ALLOCNO_HARD_REG_COSTS (a)[i])
+	  min = ALLOCNO_HARD_REG_COSTS (a)[i];
+      if (min == INT_MAX)
+	continue;
+      ira_allocate_and_set_costs (&ALLOCNO_CONFLICT_HARD_REG_COSTS (a),
+				  cover_class, 0);
+      ALLOCNO_CONFLICT_HARD_REG_COSTS (a)[index]
+	-= min - ALLOCNO_COVER_CLASS_COST (a);
+    }
+}
+
 /* Create a internal representation (IR) for IRA (allocnos, copies,
    loop tree nodes).  If LOOPS_P is FALSE the nodes corresponding to
    the loops (except the root which corresponds the all function) and
@@ -2796,6 +2834,7 @@ ira_build (bool loops_p)
   sort_conflict_id_allocno_map ();
   setup_min_max_conflict_allocno_ids ();
   ira_build_conflicts ();
+  update_conflict_hard_reg_costs ();
   if (! ira_conflicts_p)
     {
       ira_allocno_t a;