--- old/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java	2015-11-02 17:06:16.000000000 -1000
+++ new/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java	2015-11-02 17:06:16.000000000 -1000
@@ -22,13 +22,63 @@
  */
 package jdk.vm.ci.hotspot;
 
-import jdk.vm.ci.meta.*;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ConcurrentLinkedQueue;
 
-public class HotSpotSpeculationLog extends SpeculationLog {
+import jdk.vm.ci.meta.JavaConstant;
+import jdk.vm.ci.meta.SpeculationLog;
+
+public class HotSpotSpeculationLog implements SpeculationLog {
+
+    /** Written by the C++ code that performs deoptimization. */
+    private volatile Object lastFailed;
+
+    /** All speculations that have been a deoptimization reason. */
+    private Set<SpeculationReason> failedSpeculations;
+
+    /** Strong references to all reasons embededded in the current nmethod. */
+    private volatile Collection<SpeculationReason> speculations;
+
+    @Override
+    public synchronized void collectFailedSpeculations() {
+        if (lastFailed != null) {
+            if (failedSpeculations == null) {
+                failedSpeculations = new HashSet<>(2);
+            }
+            failedSpeculations.add((SpeculationReason) lastFailed);
+            lastFailed = null;
+            speculations = null;
+        }
+    }
+
+    @Override
+    public boolean maySpeculate(SpeculationReason reason) {
+        if (failedSpeculations != null && failedSpeculations.contains(reason)) {
+            return false;
+        }
+        return true;
+    }
 
     @Override
-    public JavaConstant speculate(Object reason) {
-        addSpeculation(reason);
+    public JavaConstant speculate(SpeculationReason reason) {
+        assert maySpeculate(reason);
+
+        /*
+         * Objects referenced from nmethods are weak references. We need a strong reference to the
+         * reason objects that are embedded in nmethods, so we add them to the speculations
+         * collection.
+         */
+        if (speculations == null) {
+            synchronized (this) {
+                if (speculations == null) {
+                    speculations = new ConcurrentLinkedQueue<>();
+                }
+            }
+        }
+        speculations.add(reason);
+
         return HotSpotObjectConstantImpl.forObject(reason);
     }
 }