--- /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/ssi/SSIUtil.java	2017-02-15 17:06:00.069953518 -0800
@@ -0,0 +1,196 @@
+/*
+ * 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.ssi;
+
+import java.util.Arrays;
+import java.util.List;
+
+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.LabelOp;
+import org.graalvm.compiler.lir.ValueConsumer;
+import org.graalvm.compiler.lir.ssa.SSAUtil.PhiValueVisitor;
+
+import jdk.vm.ci.meta.Value;
+
+/**
+ * Utilities for working with Static-Single-Information LIR form.
+ *
+ * <h2>Representation of &phi; and &sigma;</h2>
+ *
+ * There are no explicit &phi;/&sigma; {@link LIRInstruction}s. Instead, they are implemented as
+ * parallel copy that spans across a control-flow edge.
+ *
+ * The variables introduced by &phi;/&sigma; of a specific {@linkplain AbstractBlockBase block} are
+ * {@linkplain LabelOp#setIncomingValues attached} to the {@link LabelOp} of the block. The outgoing
+ * values from the predecessor are {@linkplain BlockEndOp#setOutgoingValues input} to the
+ * {@link BlockEndOp} of the predecessor.
+ *
+ * When it does not matter whether we are talking about a &phi; or a &sigma; we call the values that
+ * are defined by a label {@linkplain LabelOp#setIncomingValues incoming} and the values that are
+ * input to the {@link BlockEndOp} of the predecessor {@linkplain BlockEndOp#setOutgoingValues
+ * outgoing}.
+ *
+ * <h2>Implementation Details</h2>
+ *
+ * For our purposes we want a <em>maximal</em> SSI form, which means that all values that are alive
+ * across basic block boundaries are gated with a &phi;/&sigma;. In other words the outgoing and
+ * incoming values of the {@link BlockEndOp} and {@link LabelOp} are equivalent to the live-out and
+ * live-in set of the corresponding block.
+ *
+ * As a side effect variables are local to a block. We reuse the name of the predecessor if they
+ * represent the same value (i.e. not a real &phi; definition).
+ *
+ * <h2>Examples</h2>
+ *
+ * <h3>Merge (&phi;)</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>
+ *
+ * Note: the outgoing values of a block can contain constants (see <code>B0</code>).
+ *
+ * <h3>Split (&sigma;)</h3>
+ *
+ * <pre>
+ * B0 -> B1,B2
+ *   ...
+ *   v0|i = ...
+ *   v1|i = ...
+ *   v2|i = ...
+ *   TEST (x: v1|i, y: v1|i)
+ *   BRANCH ~[v2|i, v0|j] condition: <, true: B1 false: B2
+ * ________________________________________________
+ *
+ * B1 <- B0
+ *   [-, v0|j] = LABEL
+ *   ...
+ * ________________________________________________
+ *
+ * B2 <- B0
+ *   [v2|i, v0|j] = LABEL
+ *   ...
+ * </pre>
+ *
+ * Note: If a incoming value is not needed in a branch it is {@link Value#ILLEGAL ignored} (see
+ * <code>B1<code>).
+ */
+public final class SSIUtil {
+
+    public static BlockEndOp outgoing(LIR lir, AbstractBlockBase<?> block) {
+        return (BlockEndOp) outgoingInst(lir, block);
+    }
+
+    public static LIRInstruction outgoingInst(LIR lir, AbstractBlockBase<?> block) {
+        List<LIRInstruction> instructions = lir.getLIRforBlock(block);
+        int index = instructions.size() - 1;
+        LIRInstruction op = instructions.get(index);
+        return op;
+    }
+
+    public static LabelOp incoming(LIR lir, AbstractBlockBase<?> block) {
+        return (LabelOp) incomingInst(lir, block);
+    }
+
+    private static LIRInstruction incomingInst(LIR lir, AbstractBlockBase<?> block) {
+        return lir.getLIRforBlock(block).get(0);
+    }
+
+    public static void removeIncoming(LIR lir, AbstractBlockBase<?> block) {
+        incoming(lir, block).clearIncomingValues();
+    }
+
+    public static void removeOutgoing(LIR lir, AbstractBlockBase<?> block) {
+        outgoing(lir, block).clearOutgoingValues();
+    }
+
+    /**
+     * Visits each SIGMA/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 forEachValuePair(LIR lir, AbstractBlockBase<?> toBlock, AbstractBlockBase<?> fromBlock, PhiValueVisitor visitor) {
+        assert Arrays.asList(toBlock.getPredecessors()).contains(fromBlock) : String.format("%s not in predecessor list: %s", fromBlock, Arrays.toString(toBlock.getPredecessors()));
+        assert fromBlock.getSuccessorCount() == 1 || toBlock.getPredecessorCount() == 1 : String.format("Critical Edge? %s has %d successors and %s has %d predecessors", fromBlock,
+                        fromBlock.getSuccessorCount(), toBlock, toBlock.getPredecessorCount());
+        assert Arrays.asList(fromBlock.getSuccessors()).contains(toBlock) : String.format("Predecessor block %s has wrong successor: %s, should contain: %s", fromBlock,
+                        Arrays.toString(fromBlock.getSuccessors()), toBlock);
+
+        BlockEndOp blockEnd = outgoing(lir, fromBlock);
+        LabelOp label = incoming(lir, toBlock);
+
+        assert label.getIncomingSize() == blockEnd.getOutgoingSize() : String.format("In/Out size mismatch: in=%d vs. out=%d, blocks %s vs. %s", label.getIncomingSize(), blockEnd.getOutgoingSize(),
+                        toBlock, fromBlock);
+        assert label.getPhiSize() == blockEnd.getPhiSize() : String.format("Phi In/Out size mismatch: in=%d vs. out=%d", label.getPhiSize(), blockEnd.getPhiSize());
+
+        for (int i = 0; i < label.getIncomingSize(); i++) {
+            visitor.visit(label.getIncomingValue(i), blockEnd.getOutgoingValue(i));
+        }
+    }
+
+    public static void forEachRegisterHint(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()) {
+            BlockEndOp blockEnd = outgoing(lir, pred);
+            Value sourceValue = blockEnd.getOutgoingValue(idx);
+            valueConsumer.visitValue((LIRInstruction) blockEnd, 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;
+    }
+
+}