--- /dev/null	2017-01-22 10:16:57.869617664 -0800
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir/src/org/graalvm/compiler/lir/alloc/trace/TraceUtil.java	2017-02-15 17:05:35.872931493 -0800
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2015, 2015, 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 org.graalvm.compiler.lir.alloc.trace;
+
+import java.util.List;
+
+import org.graalvm.compiler.core.common.alloc.Trace;
+import org.graalvm.compiler.core.common.alloc.TraceBuilderResult;
+import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
+import org.graalvm.compiler.lir.LIR;
+import org.graalvm.compiler.lir.LIRInstruction;
+import org.graalvm.compiler.lir.StandardOp.JumpOp;
+import org.graalvm.compiler.lir.StandardOp.LabelOp;
+
+import jdk.vm.ci.meta.Value;
+
+public class TraceUtil {
+
+    public static AbstractBlockBase<?> getBestTraceInterPredecessor(TraceBuilderResult traceResult, AbstractBlockBase<?> block) {
+        AbstractBlockBase<?> bestPred = null;
+        int bestTraceId = traceResult.getTraceForBlock(block).getId();
+        for (AbstractBlockBase<?> pred : block.getPredecessors()) {
+            int predTraceId = traceResult.getTraceForBlock(pred).getId();
+            if (predTraceId < bestTraceId) {
+                bestPred = pred;
+                bestTraceId = predTraceId;
+            }
+        }
+        return bestPred;
+    }
+
+    public static boolean isShadowedRegisterValue(Value value) {
+        assert value != null;
+        return value instanceof ShadowedRegisterValue;
+    }
+
+    public static ShadowedRegisterValue asShadowedRegisterValue(Value value) {
+        assert isShadowedRegisterValue(value);
+        return (ShadowedRegisterValue) value;
+    }
+
+    public static boolean isTrivialTrace(LIR lir, Trace trace) {
+        if (trace.size() != 1) {
+            return false;
+        }
+        List<LIRInstruction> instructions = lir.getLIRforBlock(trace.getBlocks()[0]);
+        if (instructions.size() != 2) {
+            return false;
+        }
+        assert instructions.get(0) instanceof LabelOp : "First instruction not a LabelOp: " + instructions.get(0);
+        if (((LabelOp) instructions.get(0)).isPhiIn()) {
+            /*
+             * Merge blocks are in general not trivial block because variables defined by a PHI
+             * always need a location. If the outgoing value of the predecessor is a constant we
+             * need to find an appropriate location (register or stack).
+             *
+             * Note that this case should not happen in practice since the trace containing the
+             * merge block should also contain one of the predecessors. For non-standard trace
+             * builders (e.g. the single block trace builder) this is not the true, though.
+             */
+            return false;
+        }
+        /*
+         * Now we need to check if the BlockEndOp has no special operand requirements (i.e.
+         * stack-slot, register). For now we just check for JumpOp because we know that it doesn't.
+         */
+        return instructions.get(1) instanceof JumpOp;
+    }
+}