re PR bootstrap/63432 (profiledbootstrap failure with bootstrap-lto)

2014-10-15  Teresa Johnson  <tejohnson@google.com>

	PR bootstrap/63432
	* tree-ssa-threadupdate.c (recompute_probabilities): Better
	overflow checking.

From-SVN: r216269

gcc/ChangeLog

+2014-10-15  Teresa Johnson  <tejohnson@google.com>
+
+	PR bootstrap/63432
+	* tree-ssa-threadupdate.c (recompute_probabilities): Better
+	overflow checking.
+
 2014-10-15  Renlin Li <renlin.li@arm.com>
 
 	* config/aarch64/aarch64.h (TARGET_CPU_CPP_BUILTINS): Define

gcc/tree-ssa-threadupdate.c

@@ -871,11 +871,14 @@ recompute_probabilities (basic_block bb)
   edge_iterator ei;
   FOR_EACH_EDGE (esucc, ei, bb->succs)
     {
-      if (bb->count)
+      if (!bb->count)
+        continue;
+
+      /* Prevent overflow computation due to insane profiles.  */
+      if (esucc->count < bb->count)
         esucc->probability = GCOV_COMPUTE_SCALE (esucc->count,
                                                  bb->count);
-      if (esucc->probability > REG_BR_PROB_BASE)
-        {
+      else
         /* Can happen with missing/guessed probabilities, since we
            may determine that more is flowing along duplicated
            path than joiner succ probabilities allowed.
@@ -886,7 +889,6 @@ recompute_probabilities (basic_block bb)
            redoing the profile estimation.  */
         esucc->probability = REG_BR_PROB_BASE;
     }
-    }
 }