--- /dev/null	2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.lir/src/org/graalvm/compiler/lir/ssa/SSAUtil.java	2016-12-09 00:54:31.373627820 -0800
@@ -0,0 +1,181 @@
+/*
+ * 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.ssa;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.graalvm.compiler.core.common.LIRKind;
+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.LIRInstruction.OperandMode;
+import org.graalvm.compiler.lir.StandardOp.BlockEndOp;
+import org.graalvm.compiler.lir.StandardOp.JumpOp;
+import org.graalvm.compiler.lir.StandardOp.LabelOp;
+import org.graalvm.compiler.lir.ValueConsumer;
+
+import jdk.vm.ci.meta.Value;
+
+/**
+ * Utilities for working with Static-Single-Assignment LIR form.
+ *
+ * <h2>Representation of <code>PHI</code>s</h2>
+ *
+ * There is no explicit <code>PHI</code> {@linkplain LIRInstruction}. Instead, they are implemented
+ * as parallel copy that span across a control-flow edge.
+ *
+ * The variables introduced by <code>PHI</code>s of a specific {@linkplain AbstractBlockBase merge
+ * block} are {@linkplain LabelOp#setIncomingValues attached} to the {@linkplain LabelOp} of the
+ * block. The outgoing values from the predecessor are {@link JumpOp#setOutgoingValues input} to the
+ * {@linkplain BlockEndOp} of the predecessor. Because there are no critical edges we know that the
+ * {@link BlockEndOp} of the predecessor has to be a {@link JumpOp}.
+ *
+ * <h3>Example:</h3>
+ *
+ * <pre>
+ * B0 -> B1
+ *   ...
+ *   v0|i = ...
+ *   JUMP ~[v0|i, int[0|0x0]] destination: B0 -> B1
+ * ________________________________________________
+ *
+ * B2 -> B1
+ *   ...
+ *   v1|i = ...
+ *   v2|i = ...
+ *   JUMP ~[v1|i, v2|i] destination: B2 -> B1
+ * ________________________________________________
+ *
+ * B1 <- B0,B2
+ *   [v3|i, v4|i] = LABEL
+ *   ...
+ * </pre>
+ */
+public final class SSAUtil {
+
+    public interface PhiValueVisitor {
+        /**
+         * @param phiIn the incoming value at the merge block
+         * @param phiOut the outgoing value from the predecessor block
+         */
+        void visit(Value phiIn, Value phiOut);
+    }
+
+    /**
+     * Visits each phi value pair of an edge, i.e. the outgoing value from the predecessor and the
+     * incoming value to the merge block.
+     */
+    public static void forEachPhiValuePair(LIR lir, AbstractBlockBase<?> merge, AbstractBlockBase<?> pred, PhiValueVisitor visitor) {
+        if (merge.getPredecessorCount() < 2) {
+            return;
+        }
+        assert Arrays.asList(merge.getPredecessors()).contains(pred) : String.format("%s not in predecessor list: %s", pred, Arrays.toString(merge.getPredecessors()));
+        assert pred.getSuccessorCount() == 1 : String.format("Merge predecessor block %s has more than one successor? %s", pred, Arrays.toString(pred.getSuccessors()));
+        assert pred.getSuccessors()[0] == merge : String.format("Predecessor block %s has wrong successor: %s, should be: %s", pred, pred.getSuccessors()[0], merge);
+
+        JumpOp jump = phiOut(lir, pred);
+        LabelOp label = phiIn(lir, merge);
+
+        assert label.getIncomingSize() == jump.getOutgoingSize() : String.format("Phi In/Out size mismatch: in=%d vs. out=%d", label.getIncomingSize(), jump.getOutgoingSize());
+        assert label.getPhiSize() == jump.getPhiSize() : String.format("Phi In/Out size mismatch: in=%d vs. out=%d", label.getPhiSize(), jump.getPhiSize());
+
+        for (int i = 0; i < label.getPhiSize(); i++) {
+            visitor.visit(label.getIncomingValue(i), jump.getOutgoingValue(i));
+        }
+    }
+
+    private static JumpOp phiOut(LIR lir, AbstractBlockBase<?> block) {
+        assert block.getSuccessorCount() == 1;
+        List<LIRInstruction> instructions = lir.getLIRforBlock(block);
+        int index = instructions.size() - 1;
+        LIRInstruction op = instructions.get(index);
+        return (JumpOp) op;
+    }
+
+    public static int phiOutIndex(LIR lir, AbstractBlockBase<?> block) {
+        assert block.getSuccessorCount() == 1;
+        List<LIRInstruction> instructions = lir.getLIRforBlock(block);
+        int index = instructions.size() - 1;
+        assert instructions.get(index) instanceof JumpOp;
+        return index;
+    }
+
+    private static LabelOp phiIn(LIR lir, AbstractBlockBase<?> block) {
+        assert block.getPredecessorCount() > 1;
+        LabelOp label = (LabelOp) lir.getLIRforBlock(block).get(0);
+        return label;
+    }
+
+    public static void removePhiOut(LIR lir, AbstractBlockBase<?> block) {
+        JumpOp jump = phiOut(lir, block);
+        jump.clearOutgoingValues();
+    }
+
+    public static void removePhiIn(LIR lir, AbstractBlockBase<?> block) {
+        LabelOp label = phiIn(lir, block);
+        label.clearIncomingValues();
+    }
+
+    public static boolean verifySSAForm(LIR lir) {
+        return new SSAVerifier(lir).verify();
+    }
+
+    public static void verifyPhi(LIR lir, AbstractBlockBase<?> merge) {
+        assert merge.getPredecessorCount() > 1;
+        for (AbstractBlockBase<?> pred : merge.getPredecessors()) {
+            forEachPhiValuePair(lir, merge, pred, (phiIn, phiOut) -> {
+                assert phiIn.getValueKind().equals(phiOut.getValueKind()) ||
+                                (phiIn.getPlatformKind().equals(phiOut.getPlatformKind()) && LIRKind.isUnknownReference(phiIn) && LIRKind.isValue(phiOut));
+            });
+        }
+    }
+
+    public static void forEachPhiRegisterHint(LIR lir, AbstractBlockBase<?> block, LabelOp label, Value targetValue, OperandMode mode, ValueConsumer valueConsumer) {
+        assert mode == OperandMode.DEF : "Wrong operand mode: " + mode;
+        assert lir.getLIRforBlock(block).get(0).equals(label) : String.format("Block %s and Label %s do not match!", block, label);
+
+        if (!label.isPhiIn()) {
+            return;
+        }
+        int idx = indexOfValue(label, targetValue);
+        assert idx >= 0 : String.format("Value %s not in label %s", targetValue, label);
+
+        for (AbstractBlockBase<?> pred : block.getPredecessors()) {
+            JumpOp jump = phiOut(lir, pred);
+            Value sourceValue = jump.getOutgoingValue(idx);
+            valueConsumer.visitValue(jump, sourceValue, null, null);
+        }
+
+    }
+
+    private static int indexOfValue(LabelOp label, Value value) {
+        for (int i = 0; i < label.getIncomingSize(); i++) {
+            if (label.getIncomingValue(i).equals(value)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+}