--- /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/ssa/SSAVerifier.java	2017-02-15 17:05:58.458884074 -0800
@@ -0,0 +1,141 @@
+/*
+ * 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 static org.graalvm.compiler.lir.LIRValueUtil.isJavaConstant;
+import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue;
+import static jdk.vm.ci.code.ValueUtil.isRegister;
+
+import java.util.BitSet;
+import java.util.EnumSet;
+import java.util.HashMap;
+
+import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
+import org.graalvm.compiler.debug.Debug;
+import org.graalvm.compiler.debug.Debug.Scope;
+import org.graalvm.compiler.debug.Indent;
+import org.graalvm.compiler.lir.InstructionValueConsumer;
+import org.graalvm.compiler.lir.LIR;
+import org.graalvm.compiler.lir.LIRInstruction;
+import org.graalvm.compiler.lir.LIRInstruction.OperandFlag;
+import org.graalvm.compiler.lir.LIRInstruction.OperandMode;
+
+import jdk.vm.ci.meta.Value;
+
+final class SSAVerifier {
+    private static class Entry {
+        private final LIRInstruction inst;
+        private final AbstractBlockBase<?> block;
+
+        Entry(LIRInstruction inst, AbstractBlockBase<?> block) {
+            this.inst = inst;
+            this.block = block;
+        }
+    }
+
+    private final LIR lir;
+    private final BitSet visited;
+    private final HashMap<Value, Entry> defined;
+    private AbstractBlockBase<?> currentBlock;
+
+    SSAVerifier(LIR lir) {
+        this.lir = lir;
+        this.visited = new BitSet(lir.getControlFlowGraph().getBlocks().length);
+        this.defined = new HashMap<>();
+    }
+
+    @SuppressWarnings("try")
+    public boolean verify() {
+        try (Scope s = Debug.scope("SSAVerifier", lir)) {
+            for (AbstractBlockBase<?> block : lir.getControlFlowGraph().getBlocks()) {
+                doBlock(block);
+            }
+        } catch (Throwable e) {
+            throw Debug.handle(e);
+        }
+        return true;
+    }
+
+    @SuppressWarnings("try")
+    private void doBlock(AbstractBlockBase<?> b) {
+        if (visited.get(b.getId())) {
+            return;
+        }
+        for (AbstractBlockBase<?> pred : b.getPredecessors()) {
+            if (!b.isLoopHeader() || !pred.isLoopEnd()) {
+                doBlock(pred);
+            }
+        }
+        try (Indent indent = Debug.logAndIndent(Debug.INFO_LOG_LEVEL, "handle block %s", b)) {
+            assert verifyBlock(b);
+        }
+    }
+
+    private boolean verifyBlock(AbstractBlockBase<?> block) {
+        currentBlock = block;
+        assert !visited.get(block.getId()) : "Block already visited: " + block;
+        visited.set(block.getId());
+        for (LIRInstruction op : lir.getLIRforBlock(block)) {
+            op.visitEachAlive(this::useConsumer);
+            op.visitEachState(this::useConsumer);
+            op.visitEachInput(this::useConsumer);
+
+            op.visitEachTemp(this::defConsumer);
+            op.visitEachOutput(this::defConsumer);
+
+        }
+        currentBlock = null;
+        return true;
+    }
+
+    /**
+     * @see InstructionValueConsumer
+     * @param mode
+     * @param flags
+     */
+    private void useConsumer(LIRInstruction inst, Value value, OperandMode mode, EnumSet<OperandFlag> flags) {
+        if (shouldProcess(value)) {
+            assert defined.keySet().contains(value) || flags.contains(OperandFlag.UNINITIALIZED) : String.format("Value %s used at instruction %s in block %s but never defined", value, inst,
+                            currentBlock);
+        }
+    }
+
+    /**
+     * @see InstructionValueConsumer
+     * @param mode
+     * @param flags
+     */
+    private void defConsumer(LIRInstruction inst, Value value, OperandMode mode, EnumSet<OperandFlag> flags) {
+        if (shouldProcess(value)) {
+            assert !defined.keySet().contains(value) : String.format("Value %s redefined at %s but never defined (previous definition %s in block %s)", value, inst, defined.get(value).inst,
+                            defined.get(value).block);
+            defined.put(value, new Entry(inst, currentBlock));
+        }
+    }
+
+    private static boolean shouldProcess(Value value) {
+        return !value.equals(Value.ILLEGAL) && !isJavaConstant(value) && !isRegister(value) && !isStackSlotValue(value);
+    }
+
+}