[GOOGLE] Restrict the count_scale to be no larger than 100%

[Dehao Chen <dehao at google dot com>]

In AutoFDO, sometime edge count might be propagated to be too large
due to bad debug info. In this cases, we need to make sure the count
scale is no larger than 100% otherwise it'll make real hot code cold.

Bootstrapped and passed regression test. Performance test on-going.

OK for google-4_8 if performance test is ok?

Thanks,
Dehao

Index: gcc/tree-inline.c
===================================================================
--- gcc/tree-inline.c (revision 206721)
+++ gcc/tree-inline.c (working copy)
@@ -2262,6 +2262,9 @@ copy_cfg_body (copy_body_data * id, gcov_type coun
   else
     count_scale = REG_BR_PROB_BASE;

+  if (flag_auto_profile && count_scale > REG_BR_PROB_BASE)
+    count_scale = REG_BR_PROB_BASE;
+
   /* Register specific tree functions.  */
   gimple_register_cfg_hooks ();

Index: gcc/cgraphclones.c
===================================================================
--- gcc/cgraphclones.c (revision 206721)
+++ gcc/cgraphclones.c (working copy)
@@ -216,7 +216,10 @@ cgraph_clone_node (struct cgraph_node *n, tree dec
      count, we will not update the original callee because it may
      mistakenly mark some hot function as cold.  */
   if (flag_auto_profile && count >= n->count)
-    update_original = false;
+    {
+      update_original = false;
+      new_node->count = n->count;
+    }
   if (update_original)
     {
       n->count -= count;