--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jvmci/jdk.vm.ci.meta/src/jdk/vm/ci/meta/SpeculationLog.java	Thu Oct 08 17:28:41 2015 -0700
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.vm.ci.meta;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+/**
+ * Manages a list of unique deoptimization reasons.
+ *
+ */
+public abstract class SpeculationLog {
+    private volatile Object lastFailed;
+    private volatile Collection<Object> speculations;
+    private Set<Object> failedSpeculations;
+
+    public synchronized void collectFailedSpeculations() {
+        if (lastFailed != null) {
+            if (failedSpeculations == null) {
+                failedSpeculations = new HashSet<>(2);
+            }
+            failedSpeculations.add(lastFailed);
+            lastFailed = null;
+            speculations = null;
+        }
+    }
+
+    public boolean maySpeculate(Object reason) {
+        if (failedSpeculations != null && failedSpeculations.contains(reason)) {
+            return false;
+        }
+        return true;
+    }
+
+    protected void addSpeculation(Object reason) {
+        assert maySpeculate(reason);
+        if (speculations == null) {
+            synchronized (this) {
+                if (speculations == null) {
+                    speculations = new ConcurrentLinkedQueue<>();
+                }
+            }
+        }
+        speculations.add(reason);
+    }
+
+    public abstract JavaConstant speculate(Object reason);
+}