i386.c (distance_agu_use_in_bb): Proper initialization of 'prev' var to get…

i386.c (distance_agu_use_in_bb): Proper initialization of 'prev' var to get better distance estimation.

* config/i386/i386.c (distance_agu_use_in_bb) : Proper initialization
  of 'prev' var to get better distance estimation.

From-SVN: r202649

gcc/ChangeLog

+2013-09-17  Yuri Rumyantsev  <ysrumyan@gmail.com>
+
+	* config/i386/i386.c (distance_agu_use_in_bb) : Proper initialization
+	of 'prev' var to get better distance estimation.
+
 2013-09-17  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* tree-inline.h (struct copy_body_data): Add transform_parameter.

gcc/config/i386/i386.c

@@ -17469,13 +17469,23 @@ distance_agu_use_in_bb (unsigned int regno,
 			rtx insn, int distance, rtx start,
 			bool *found, bool *redefined)
 {
-  basic_block bb = start ? BLOCK_FOR_INSN (start) : NULL;
+  basic_block bb = NULL;
   rtx next = start;
   rtx prev = NULL;
 
   *found = false;
   *redefined = false;
 
+  if (start != NULL_RTX)
+    {
+      bb = BLOCK_FOR_INSN (start);
+      if (start != BB_HEAD (bb))
+	/* If insn and start belong to the same bb, set prev to insn,
+	   so the call to increase_distance will increase the distance
+	   between insns by 1.  */
+	prev = insn;
+    }
+
   while (next
 	 && next != insn
 	 && distance < LEA_SEARCH_THRESHOLD)