diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/BasicBlock.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/BasicBlock.java
index ccb8b09..51f7d51 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/BasicBlock.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/BasicBlock.java
@@ -213,6 +213,14 @@ public StringBuilder toDot(StringBuilder sb, boolean verbose) {
         sb.append("</TABLE>");
         return sb;
     }
+    public StringBuilder listDomFrontiers(StringBuilder sb) {
+        sb.append("L").append(this.bid).append(":");
+        for (BasicBlock bb: dominationFrontier) {
+            sb.append(" L").append(bb.bid);
+        }
+        sb.append("\n");
+        return sb;
+    }
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
index 48526e6..501e7d5 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
@@ -426,7 +426,7 @@ private boolean compileArrayStoreExpr(AST.ArrayStoreExpr arrayStoreExpr) {
     }
 
     private boolean compileNewExpr(AST.NewExpr newExpr) {
-        codeNew(newExpr.type);
+        codeNew(newExpr.type,newExpr.len,newExpr.initValue);
         return false;
     }
 
@@ -644,20 +644,44 @@ else if (indexed instanceof Operand.LoadFieldOperand loadFieldOperand)
             codeMove(value, indexed);
     }
 
-    private void codeNew(Type type) {
+    private void codeNew(Type type, AST.Expr len, AST.Expr initVal) {
         if (type instanceof Type.TypeArray typeArray)
-            codeNewArray(typeArray);
+            codeNewArray(typeArray, len, initVal);
         else if (type instanceof Type.TypeStruct typeStruct)
             codeNewStruct(typeStruct);
         else
             throw new CompilerException("Unexpected type: " + type);
     }
 
-    private void codeNewArray(Type.TypeArray typeArray) {
+    private void codeNewArray(Type.TypeArray typeArray, AST.Expr len, AST.Expr initVal) {
         var temp = createTemp(typeArray);
+        Operand lenOperand = null;
+        Operand initValOperand = null;
+        if (len != null) {
+            boolean indexed = compileExpr(len);
+            if (indexed)
+                codeIndexedLoad();
+            if (initVal != null) {
+                indexed = compileExpr(initVal);
+                if (indexed)
+                    codeIndexedLoad();
+                initValOperand = pop();
+            }
+            lenOperand = pop();
+        }
+        Instruction insn;
         var target = (Operand.RegisterOperand) issa.write(temp);
-        var insn = new Instruction.NewArray(typeArray, target);
+        if (lenOperand != null) {
+            if (initValOperand != null)
+                insn = new Instruction.NewArray(typeArray, target, issa.read(lenOperand), issa.read(initValOperand));
+            else
+                insn = new Instruction.NewArray(typeArray, target, issa.read(lenOperand));
+        }
+        else
+            insn = new Instruction.NewArray(typeArray, target);
         issa.recordDef(target, insn);
+        if (lenOperand != null) issa.recordUse(lenOperand,insn);
+        if (initValOperand != null) issa.recordUse(initValOperand,insn);
         code(insn);
     }
 
@@ -941,6 +965,32 @@ private Register addPhiOperands(Register variable, Instruction.Phi phi) {
             return tryRemovingPhi(phi);
         }
 
+        // The Phi's def is dead so we need to remove
+        // all occurrences of this def from the memoized defs
+        // per Basic Block
+        private void clearDefs(Instruction.Phi phi) {
+            // TODO rethink the data structure for currentDef
+            var def = phi.value();
+            var defs = currentDef.get(def.nonSSAId());
+            // Make a list of block/reg that we need to delete
+            var bbList = new ArrayList<BasicBlock>();
+            var regList = new ArrayList<Register>();
+            for (var entries : defs.entrySet()) {
+                var bb = entries.getKey();
+                var reg = entries.getValue();
+                if (reg.equals(def)) {
+                    bbList.add(bb);
+                    regList.add(reg);
+                }
+            }
+            // Now delete them
+            for (int i = 0; i < bbList.size(); i++) {
+                var bb = bbList.get(i);
+                var reg = regList.get(i);
+                defs.remove(bb, reg);
+            }
+        }
+
         private Register tryRemovingPhi(Instruction.Phi phi) {
             Register same = null;
             // Check if phi has distinct inputs
@@ -967,6 +1017,9 @@ private Register tryRemovingPhi(Instruction.Phi phi) {
             // remove all uses of phi to same and remove phi
             replacePhiValueAndUsers(phi, same);
             phi.block.deleteInstruction(phi);
+            // Since the phi is dead any references to its def
+            // must be removed; this is not mentioned in the paper
+            clearDefs(phi);
             // try to recursively remove all phi users, which might have become trivial
             for (var use: users) {
                 if (use instanceof Instruction.Phi phiuser)
@@ -979,25 +1032,28 @@ private Register tryRemovingPhi(Instruction.Phi phi) {
          * Reroute all uses of phi to new value
          */
         private void replacePhiValueAndUsers(Instruction.Phi phi, Register newValue) {
-            var oldDefUseChain = ssaDefUses.get(phi.value());
+            var oldValue = phi.value();
+            var oldDefUseChain = ssaDefUses.get(oldValue);
             var newDefUseChain = ssaDefUses.get(newValue);
             if (newDefUseChain == null) {
-                // Can be null because this may be existing def
-                newDefUseChain = SSAEdges.addDef(ssaDefUses, newValue, phi);
+                throw new CompilerException("Expected error: undefined var " + newValue);
             }
             if (oldDefUseChain != null) {
                 for (Instruction instruction: oldDefUseChain.useList) {
+                    boolean replaced;
                     if (instruction instanceof Instruction.Phi somePhi) {
-                        somePhi.replaceInput(phi.value(), newValue);
+                        replaced = somePhi.replaceInput(oldValue, newValue);
                     }
                     else {
-                        instruction.replaceUse(phi.value(), newValue);
+                        replaced = instruction.replaceUse(oldValue, newValue);
+                    }
+                    if (!replaced) {
+                        throw new CompilerException("Discrepancy between var use list and var definition");
                     }
                 }
                 // Users of phi old value become users of the new value
                 newDefUseChain.useList.addAll(oldDefUseChain.useList);
                 oldDefUseChain.useList.clear();
-                // FIXME remove old def from def-use chains
             }
         }
 
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/DominatorTree.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/DominatorTree.java
index ea3dc2f..2a6b120 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/DominatorTree.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/DominatorTree.java
@@ -1,10 +1,8 @@
 package com.compilerprogramming.ezlang.compiler;
 
-import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
-import java.util.function.Consumer;
 
 /**
  * The dominator tree construction algorithm is based on figure 9.24,
@@ -34,6 +32,7 @@ public DominatorTree(BasicBlock entry) {
         populateTree();
         setDepth();
         calculateDominanceFrontiers();
+        //calculateDominanceFrontiersMethod2();
     }
 
     private void calculateDominatorTree() {
@@ -41,7 +40,7 @@ private void calculateDominatorTree() {
         annotateBlocksWithRPO();
         sortBlocksByRPO();
 
-        // Set IDom entry for root to itself
+        // Set IDom entry for root to itself (see note below)
         entry.idom = entry;
         boolean changed = true;
         while (changed) {
@@ -68,6 +67,11 @@ private void calculateDominatorTree() {
                 }
             }
         }
+        // There is a contradiction between what is described in the book
+        // and the algo - as the book says the IDOM for root is undefined
+        // But we set this to itself when calculating. So after calculations
+        // are done, set this to null. This is technically more correct IMO.
+        entry.idom = null;
     }
 
     private void resetDomInfo() {
@@ -146,7 +150,7 @@ private BasicBlock findFirstPredecessorWithIdom(BasicBlock n) {
     private void populateTree() {
         for (BasicBlock block : blocks) {
             BasicBlock idom = block.idom;
-            if (idom == block) // root
+            if (idom == null) // root
                 continue;
             // add edge from idom to n
             idom.dominatedChildren.add(block);
@@ -166,12 +170,13 @@ private void setDepth() {
      */
     private void setDepth_(BasicBlock block) {
         BasicBlock idom = block.idom;
-        if (idom != block) {
+        if (idom != null) {
             assert idom.domDepth > 0;
             block.domDepth = idom.domDepth + 1;
-        } else {
-            assert idom.domDepth == 1;
-            assert idom.domDepth == block.domDepth;
+        }
+        else {
+            // root (entry) block's idom is null
+            assert block.domDepth == 1;
         }
         for (BasicBlock child : block.dominatedChildren)
             setDepth_(child);
@@ -189,6 +194,8 @@ private void calculateDominanceFrontiers() {
         //          while runner != doms[b]
         //              add b to runner’s dominance frontier set
         //              runner = doms[runner]
+        for (BasicBlock b: blocks)
+            b.dominationFrontier.clear();   // empty set
         for (BasicBlock b : blocks) {
             if (b.predecessors.size() >= 2) {
                 for (BasicBlock p : b.predecessors) {
@@ -204,6 +211,37 @@ private void calculateDominanceFrontiers() {
         }
     }
 
+    // We have an alternative approach to calculating DOM Frontiers to
+    // allow us to validate above
+    private void calculateDominanceFrontiersMethod2()
+    {
+        for (BasicBlock b: blocks)
+            b.dominationFrontier.clear();   // empty set
+        computeDF(entry);
+    }
+
+    // Implementation based on description in pg 440 of
+    // Modern Compiler implementation in C
+    // Appel
+    private void computeDF(BasicBlock n) {
+        var S = new HashSet<BasicBlock>();
+        for (BasicBlock y: n.successors) {
+            if (y.idom != n)
+                S.add(y);
+        }
+        for (BasicBlock c: n.dominatedChildren) {
+            computeDF(c);
+            for (BasicBlock w: c.dominationFrontier) {
+                // Note that the printed book has an error below
+                // and errata gives the correct version
+                if (!n.dominates(w) || n==w) {
+                    S.add(w);
+                }
+            }
+        }
+        n.dominationFrontier.addAll(S);
+    }
+
     public String generateDotOutput() {
         StringBuilder sb = new StringBuilder();
         sb.append("digraph DomTree {\n");
@@ -212,10 +250,18 @@ public String generateDotOutput() {
         }
         for (BasicBlock n : blocks) {
             BasicBlock idom = n.idom;
-            if (idom == n) continue;
+            if (idom == null) continue;
             sb.append(idom.uniqueName()).append("->").append(n.uniqueName()).append(";\n");
         }
         sb.append("}\n");
         return sb.toString();
     }
+
+    public String listDomFrontiers() {
+        StringBuilder sb = new StringBuilder();
+        for (BasicBlock n : blocks) {
+            n.listDomFrontiers(sb);
+        }
+        return sb.toString();
+    }
 }
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/EnterSSA.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/EnterSSA.java
index 83e7c24..143b123 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/EnterSSA.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/EnterSSA.java
@@ -41,9 +41,17 @@ public EnterSSA(CompiledFunction bytecodeFunction, EnumSet<Options> options) {
             System.out.println("Pre SSA Dominator Tree");
             System.out.println(domTree.generateDotOutput());
         }
+        if (options.contains(Options.DUMP_PRE_SSA_DOMFRONTIERS)) {
+            System.out.println("Pre SSA Dominance Frontiers");
+            System.out.println(domTree.listDomFrontiers());
+        }
         this.blocks = domTree.blocks;   // the blocks are ordered reverse post order
         findNonLocalNames();
         new Liveness(bytecodeFunction); // EWe require liveness info to construct pruned ssa
+        if (options.contains(Options.DUMP_PRE_SSA_LIVENESS)) {
+            System.out.println("Pre SSA Liveness");
+            System.out.println(bytecodeFunction.toStr(new StringBuilder(), true));
+        }
         insertPhis();
         renameVars();
         bytecodeFunction.isSSA = true;
@@ -177,8 +185,9 @@ void search(BasicBlock block) {
         }
         // Pop stacks for defs
         for (Instruction i: block.instructions) {
-            if (i.definesVar()) {
-                var reg = i.def();
+            // Phis don't answer to definesVar() or def()
+            if (i.definesVar() || i instanceof Instruction.Phi) {
+                var reg = i instanceof Instruction.Phi phi ? phi.value() : i.def();
                 stacks[reg.nonSSAId()].pop();
             }
         }
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
index 0ab1203..0aa50ff 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
@@ -124,14 +124,28 @@ public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand) {
             super(I_NEW_ARRAY, destOperand);
             this.type = type;
         }
+        public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand, Operand len) {
+            super(I_NEW_ARRAY, destOperand, len);
+            this.type = type;
+        }
+        public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand, Operand len, Operand initValue) {
+            super(I_NEW_ARRAY, destOperand, len, initValue);
+            this.type = type;
+        }
+        public Operand len() { return uses.length > 0 ? uses[0] : null; }
+        public Operand initValue() { return uses.length > 1 ? uses[1] : null; }
         public Operand.RegisterOperand destOperand() { return def; }
         @Override
         public StringBuilder toStr(StringBuilder sb) {
-            return sb.append(def)
+            sb.append(def)
                     .append(" = ")
                     .append("New(")
-                    .append(type)
-                    .append(")");
+                    .append(type);
+            if (len() != null)
+                sb.append(", len=").append(len());
+            if (initValue() != null)
+                sb.append(", initValue=").append(initValue());
+            return sb.append(")");
         }
     }
 
@@ -417,15 +431,18 @@ public void addInput(Register register) {
             newUses[newUses.length-1] = new Operand.RegisterOperand(register);
             this.uses = newUses;
         }
-        public void replaceInput(Register oldReg, Register newReg) {
+        public boolean replaceInput(Register oldReg, Register newReg) {
+            boolean replaced = false;
             for (int i = 0; i < numInputs(); i++) {
                 if (isRegisterInput(i)) {
                     Register in = inputAsRegister(i);
                     if (in.equals(oldReg)) {
                         replaceInput(i, newReg);
+                        replaced = true;
                     }
                 }
             }
+            return replaced;
         }
     }
 
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Options.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Options.java
index e71988c..b53c8cd 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Options.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Options.java
@@ -10,6 +10,8 @@ public enum Options {
     REGALLOC,
     DUMP_INITIAL_IR,
     DUMP_PRE_SSA_DOMTREE,
+    DUMP_PRE_SSA_DOMFRONTIERS,
+    DUMP_PRE_SSA_LIVENESS,
     DUMP_SSA_IR,
     DUMP_SCCP_PREAPPLY,
     DUMP_SCCP_POSTAPPLY,
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Register.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Register.java
index 3376e61..42895b9 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Register.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/Register.java
@@ -40,7 +40,7 @@ public class Register {
      *
      * Not unique.
      */
-    private final String name;
+    protected final String name;
     /**
      * The type of the register
      */
@@ -50,7 +50,7 @@ public class Register {
      * of the executing function. Multiple registers may share the same
      * frame slot because of different non-overlapping life times.
      */
-    private int frameSlot;
+    protected int frameSlot;
 
     public Register(int id, String name, Type type) {
         this(id,name,type,id);  // Initially frame slot is set to the unique ID
@@ -107,7 +107,15 @@ public SSARegister(Register original, int id, int version) {
         public int nonSSAId() {
             return originalRegNumber;
         }
-    }
 
+        @Override
+        public String toString() {
+            return "SSARegister{name=" + name + ", id=" + id + ", frameSlot=" + frameSlot + ", ssaVersion=" + ssaVersion + ", originalRegNumber=" + originalRegNumber + '}';
+        }
+    }
 
+    @Override
+    public String toString() {
+        return "Register{name=" + name + ", id=" + id + ", frameSlot=" + frameSlot + "}";
+    }
 }
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SSAEdges.java b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SSAEdges.java
index 4e81e91..41ebb8b 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SSAEdges.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SSAEdges.java
@@ -89,6 +89,8 @@ private static void recordUses(Map<Register, SSADef> defUseChains, Register[] in
 
     public static void recordUse(Map<Register, SSADef> defUseChains, Instruction instruction, Register register) {
         SSADef def = defUseChains.get(register);
+        if (def == null)
+            throw new CompilerException("No def found for " + register);
         def.useList.add(instruction);
     }
 
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
index c85fa24..654d2df 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
@@ -200,7 +200,19 @@ else if (binaryInst.right() instanceof Operand.RegisterOperand registerOperand)
                     }
                 }
                 case Instruction.NewArray newArrayInst -> {
-                    execStack.stack[base + newArrayInst.destOperand().frameSlot()] = new Value.ArrayValue(newArrayInst.type);
+                    long size = 0;
+                    Value initValue = null;
+                    if (newArrayInst.len() instanceof Operand.ConstantOperand constantOperand)
+                        size = constantOperand.value;
+                    else if (newArrayInst.len() instanceof Operand.RegisterOperand registerOperand) {
+                        Value.IntegerValue indexValue = (Value.IntegerValue) execStack.stack[base + registerOperand.frameSlot()];
+                        size = (long) indexValue.value;
+                    }
+                    if (newArrayInst.initValue() instanceof Operand.ConstantOperand constantOperand)
+                        initValue = new Value.IntegerValue(constantOperand.value);
+                    else if (newArrayInst.initValue() instanceof Operand.RegisterOperand registerOperand)
+                        initValue = execStack.stack[base + registerOperand.frameSlot()];
+                    execStack.stack[base + newArrayInst.destOperand().frameSlot()] = new Value.ArrayValue(newArrayInst.type, size, initValue);
                 }
                 case Instruction.NewStruct newStructInst -> {
                     execStack.stack[base + newStructInst.destOperand().frameSlot()] = new Value.StructValue(newStructInst.type);
diff --git a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
index 7f914a6..6717daa 100644
--- a/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
+++ b/optvm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
@@ -17,9 +17,12 @@ public NullValue() {}
     static public class ArrayValue extends Value {
         public final Type.TypeArray arrayType;
         public final ArrayList<Value> values;
-        public ArrayValue(Type.TypeArray arrayType) {
+        public ArrayValue(Type.TypeArray arrayType, long len, Value initValue) {
             this.arrayType = arrayType;
             values = new ArrayList<>();
+            for (long i = 0; i < len; i++) {
+                values.add(initValue);
+            }
         }
     }
     static public class StructValue extends Value {
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
index b6873ec..11b46eb 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
@@ -214,7 +214,7 @@ func foo()->[Int] {
         String result = compileSrc(src);
         Assert.assertEquals("""
 L0:
-    %t0 = New([Int])
+    %t0 = New([Int], len=3)
     %t0[0] = 1
     %t0[1] = 2
     %t0[2] = 3
@@ -235,7 +235,7 @@ func foo(n: Int) -> [Int] {
         Assert.assertEquals("""
 L0:
     arg n
-    %t1 = New([Int])
+    %t1 = New([Int], len=1)
     %t1[0] = n
     ret %t1
     goto  L1
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestDominators.java b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestDominators.java
index 4a74ded..a58843b 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestDominators.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestDominators.java
@@ -12,6 +12,8 @@ BasicBlock add(List<BasicBlock> nodes, BasicBlock node) {
         return node;
     }
 
+    // This CFG example is taken from page 473 of
+    // Engineering a Compiler 3rd ed
     BasicBlock makeGraph(List<BasicBlock> nodes) {
         BasicBlock r0 = add(nodes, new BasicBlock(1));
         BasicBlock r1 = add(nodes, new BasicBlock(2, r0));
@@ -28,15 +30,34 @@ BasicBlock makeGraph(List<BasicBlock> nodes) {
         return r0;
     }
 
+    // This DOM Tree example is taken from page 473 of
+    // Engineering a Compiler 3rd ed
     @Test
     public void testDominatorTree() {
         List<BasicBlock> nodes = new ArrayList<>();
         BasicBlock root = makeGraph(nodes);
         DominatorTree tree = new DominatorTree(root);
         System.out.println(tree.generateDotOutput());
-        long[] expectedIdoms = {0,1,1,2,2,4,2,6,6,6};
+        // expected            {_,_,0,1,1,3,1,5,5,5}
+        // Note first entry is not used
+        // Note we set idom of root to itself so the second entry
+        // does not match example
+        long[] expectedIdoms = {-1,0,1,2,2,4,2,6,6,6};
         for (BasicBlock n: nodes) {
-            Assert.assertEquals(expectedIdoms[(int)n.bid], n.idom.bid);
+            if (expectedIdoms[(int)n.bid] == 0)
+                Assert.assertNull(n.idom);
+            else
+                Assert.assertEquals(expectedIdoms[(int)n.bid], n.idom.bid);
+        }
+        // -1 means empty set
+        long[] expectedDF = {0,-1,2,4,2,-1,4,8,4,8};
+        for (BasicBlock n: nodes) {
+            if (expectedDF[(int)n.bid] == -1) {
+                Assert.assertTrue(n.dominationFrontier.isEmpty());
+            }
+            else {
+                Assert.assertEquals(1,n.dominationFrontier.size());
+            }
         }
     }
 
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestIncrementalSSA.java b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestIncrementalSSA.java
index e4f9b93..e3a5272 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestIncrementalSSA.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestIncrementalSSA.java
@@ -183,188 +183,189 @@ func example14_66(p: Int, q: Int, r: Int, s: Int, t: Int) {
                 """;
         String result = compileSrc(src);
         Assert.assertEquals("""
-                func print(a: Int,b: Int,c: Int,d: Int)
-                Reg #0 a 0
-                Reg #1 b 1
-                Reg #2 c 2
-                Reg #3 d 3
-                L0:
-                    arg a
-                    arg b
-                    arg c
-                    arg d
-                    goto  L1
-                L1:
-                func example14_66(p: Int,q: Int,r: Int,s: Int,t: Int)
-                Reg #0 p 0
-                Reg #1 q 1
-                Reg #2 r 2
-                Reg #3 s 3
-                Reg #4 t 4
-                Reg #5 i 5
-                Reg #6 j 6
-                Reg #7 k 7
-                Reg #8 l 8
-                Reg #9 p_1 0
-                Reg #10 i_1 5
-                Reg #11 j_1 6
-                Reg #12 q_1 1
-                Reg #13 l_1 8
-                Reg #14 l_2 8
-                Reg #15 %t15 15
-                Reg #16 k_1 7
-                Reg #17 k_2 7
-                Reg #18 k_3 7
-                Reg #19 %t19 19
-                Reg #20 k_4 7
-                Reg #21 %t21 21
-                Reg #22 i_2 5
-                Reg #23 i_3 5
-                Reg #24 %t24 24
-                Reg #25 j_2 6
-                Reg #26 j_3 6
-                Reg #27 j_4 6
-                Reg #28 %t28 28
-                Reg #29 k_5 7
-                Reg #30 %t30 30
-                Reg #31 l_3 8
-                Reg #32 l_4 8
-                Reg #33 l_5 8
-                Reg #34 r_1 2
-                Reg #35 %t35 35
-                Reg #36 l_6 8
-                Reg #37 l_7 8
-                Reg #38 %t38 38
-                Reg #39 s_1 3
-                Reg #40 s_2 3
-                Reg #41 r_2 2
-                Reg #42 r_3 2
-                Reg #43 r_4 2
-                Reg #44 r_5 2
-                Reg #45 s_3 3
-                Reg #46 s_4 3
-                Reg #47 s_5 3
-                Reg #48 l_8 8
-                Reg #49 %t49 49
-                Reg #50 i_4 5
-                Reg #51 i_5 5
-                Reg #52 i_6 5
-                Reg #53 i_7 5
-                Reg #54 %t54 54
-                Reg #55 t_1 4
-                Reg #56 t_2 4
-                Reg #57 t_3 4
-                Reg #58 t_4 4
-                Reg #59 t_5 4
-                Reg #60 t_6 4
-                Reg #61 p_2 0
-                Reg #62 p_3 0
-                Reg #63 p_4 0
-                Reg #64 p_5 0
-                Reg #65 p_6 0
-                Reg #66 q_2 1
-                Reg #67 q_3 1
-                Reg #68 q_4 1
-                Reg #69 q_5 1
-                Reg #70 q_6 1
-                Reg #71 r_6 2
-                Reg #72 s_6 3
-                Reg #73 j_5 6
-                Reg #74 j_6 6
-                Reg #75 j_7 6
-                Reg #76 k_6 7
-                Reg #77 k_7 7
-                Reg #78 k_8 7
-                Reg #79 l_9 8
-                L0:
-                    arg p
-                    arg q
-                    arg r
-                    arg s
-                    arg t
-                    i = 1
-                    j = 1
-                    k = 1
-                    l = 1
-                    goto  L2
-                L2:
-                    t_5 = phi(t, t_1)
-                    s_5 = phi(s, s_2)
-                    r_4 = phi(r, r_1)
-                    l_5 = phi(l, l_9)
-                    j_4 = phi(j, j_5)
-                    k_2 = phi(k, k_6)
-                    q_1 = phi(q, q_2)
-                    i_1 = phi(i, i_7)
-                    p_1 = phi(p, p_2)
-                    if 1 goto L3 else goto L4
-                L3:
-                    if p_1 goto L5 else goto L6
-                L5:
-                    j_1 = i_1
-                    if q_1 goto L8 else goto L9
-                L8:
-                    l_1 = 2
-                    goto  L10
-                L10:
-                    l_4 = phi(l_1, l_2)
-                    %t15 = k_2+1
-                    k_3 = %t15
-                    goto  L7
-                L7:
-                    l_3 = phi(l_4, l_5)
-                    k_5 = phi(k_3, k_4)
-                    j_2 = phi(j_1, j_4)
-                    %t21 = i_1
-                    %t24 = j_2
-                    %t28 = k_5
-                    %t30 = l_3
-                    call print params %t21, %t24, %t28, %t30
-                    goto  L11
-                L11:
-                    l_6 = phi(l_3, l_8)
-                    if 1 goto L12 else goto L13
-                L12:
-                    if r_4 goto L14 else goto L15
-                L14:
-                    %t35 = l_6+4
-                    l_7 = %t35
-                    goto  L15
-                L15:
-                    l_8 = phi(l_6, l_7)
-                    %t38 = !s_5
-                    if %t38 goto L16 else goto L17
-                L16:
-                    goto  L13
-                L13:
-                    l_9 = phi(l_6, l_8)
-                    k_6 = phi(k_5, k_7)
-                    j_5 = phi(j_2, j_6)
-                    q_2 = phi(q_1, q_3)
-                    p_2 = phi(p_1, p_3)
-                    t_1 = phi(t_5, t_2)
-                    i_4 = phi(i_1, i_5)
-                    %t49 = i_4+6
-                    i_7 = %t49
-                    %t54 = !t_1
-                    if %t54 goto L18 else goto L19
-                L18:
-                    goto  L4
-                L4:
-                    goto  L1
-                L1:
-                L19:
-                    goto  L2
-                L17:
-                    goto  L11
-                L9:
-                    l_2 = 3
-                    goto  L10
-                L6:
-                    %t19 = k_2+2
-                    k_4 = %t19
-                    goto  L7
-                """, result);
+func print(a: Int,b: Int,c: Int,d: Int)
+Reg #0 a 0
+Reg #1 b 1
+Reg #2 c 2
+Reg #3 d 3
+L0:
+    arg a
+    arg b
+    arg c
+    arg d
+    goto  L1
+L1:
+func example14_66(p: Int,q: Int,r: Int,s: Int,t: Int)
+Reg #0 p 0
+Reg #1 q 1
+Reg #2 r 2
+Reg #3 s 3
+Reg #4 t 4
+Reg #5 i 5
+Reg #6 j 6
+Reg #7 k 7
+Reg #8 l 8
+Reg #9 p_1 0
+Reg #10 i_1 5
+Reg #11 j_1 6
+Reg #12 q_1 1
+Reg #13 l_1 8
+Reg #14 l_2 8
+Reg #15 %t15 15
+Reg #16 k_1 7
+Reg #17 k_2 7
+Reg #18 k_3 7
+Reg #19 %t19 19
+Reg #20 k_4 7
+Reg #21 %t21 21
+Reg #22 i_2 5
+Reg #23 i_3 5
+Reg #24 %t24 24
+Reg #25 j_2 6
+Reg #26 j_3 6
+Reg #27 j_4 6
+Reg #28 %t28 28
+Reg #29 k_5 7
+Reg #30 %t30 30
+Reg #31 l_3 8
+Reg #32 l_4 8
+Reg #33 l_5 8
+Reg #34 r_1 2
+Reg #35 %t35 35
+Reg #36 l_6 8
+Reg #37 l_7 8
+Reg #38 %t38 38
+Reg #39 s_1 3
+Reg #40 s_2 3
+Reg #41 r_2 2
+Reg #42 r_3 2
+Reg #43 r_4 2
+Reg #44 r_5 2
+Reg #45 s_3 3
+Reg #46 s_4 3
+Reg #47 s_5 3
+Reg #48 l_8 8
+Reg #49 %t49 49
+Reg #50 i_4 5
+Reg #51 i_5 5
+Reg #52 i_6 5
+Reg #53 i_7 5
+Reg #54 i_8 5
+Reg #55 %t55 55
+Reg #56 t_1 4
+Reg #57 t_2 4
+Reg #58 t_3 4
+Reg #59 t_4 4
+Reg #60 t_5 4
+Reg #61 t_6 4
+Reg #62 t_7 4
+Reg #63 p_2 0
+Reg #64 p_3 0
+Reg #65 p_4 0
+Reg #66 p_5 0
+Reg #67 p_6 0
+Reg #68 p_7 0
+Reg #69 q_2 1
+Reg #70 q_3 1
+Reg #71 q_4 1
+Reg #72 q_5 1
+Reg #73 q_6 1
+Reg #74 q_7 1
+Reg #75 r_6 2
+Reg #76 r_7 2
+Reg #77 r_8 2
+Reg #78 r_9 2
+Reg #79 s_6 3
+Reg #80 s_7 3
+Reg #81 s_8 3
+Reg #82 s_9 3
+Reg #83 j_5 6
+Reg #84 j_6 6
+Reg #85 j_7 6
+Reg #86 j_8 6
+Reg #87 k_6 7
+Reg #88 k_7 7
+Reg #89 k_8 7
+Reg #90 k_9 7
+Reg #91 l_9 8
+L0:
+    arg p
+    arg q
+    arg r
+    arg s
+    arg t
+    i = 1
+    j = 1
+    k = 1
+    l = 1
+    goto  L2
+L2:
+    l_5 = phi(l, l_9)
+    j_4 = phi(j, j_2)
+    k_2 = phi(k, k_5)
+    i_1 = phi(i, i_8)
+    if 1 goto L3 else goto L4
+L3:
+    if p goto L5 else goto L6
+L5:
+    j_1 = i_1
+    if q goto L8 else goto L9
+L8:
+    l_1 = 2
+    goto  L10
+L10:
+    l_4 = phi(l_1, l_2)
+    %t15 = k_2+1
+    k_3 = %t15
+    goto  L7
+L7:
+    l_3 = phi(l_4, l_5)
+    k_5 = phi(k_3, k_4)
+    j_2 = phi(j_1, j_4)
+    %t21 = i_1
+    %t24 = j_2
+    %t28 = k_5
+    %t30 = l_3
+    call print params %t21, %t24, %t28, %t30
+    goto  L11
+L11:
+    l_6 = phi(l_3, l_8)
+    if 1 goto L12 else goto L13
+L12:
+    if r goto L14 else goto L15
+L14:
+    %t35 = l_6+4
+    l_7 = %t35
+    goto  L15
+L15:
+    l_8 = phi(l_6, l_7)
+    %t38 = !s
+    if %t38 goto L16 else goto L17
+L16:
+    goto  L13
+L13:
+    l_9 = phi(l_6, l_8)
+    %t49 = i_1+6
+    i_8 = %t49
+    %t55 = !t
+    if %t55 goto L18 else goto L19
+L18:
+    goto  L4
+L4:
+    goto  L1
+L1:
+L19:
+    goto  L2
+L17:
+    goto  L11
+L9:
+    l_2 = 3
+    goto  L10
+L6:
+    %t19 = k_2+2
+    k_4 = %t19
+    goto  L7
+""", result);
     }
 
     @Test
@@ -606,6 +607,114 @@ func main()->Int
 """, result);
     }
 
+    @Test
+    public void testSSA11() {
+        String src = """
+        func main()->Int {
+            var a = 0
+            var i = 0
+            var j = 0
+            while (i < 3) {
+                j = 0
+                while (j < 3) {
+                    if (i == j) 
+                        a = a + i + j
+                    else if (i > j)
+                        a = a - 1
+                    j = j + 1        
+                }
+                i = i + 1    
+            }
+            return a
+        }
+""";
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func main()->Int
+Reg #0 a 0
+Reg #1 i 1
+Reg #2 j 2
+Reg #3 %t3 3
+Reg #4 i_1 1
+Reg #5 j_1 2
+Reg #6 %t6 6
+Reg #7 j_2 2
+Reg #8 %t8 8
+Reg #9 i_2 1
+Reg #10 %t10 10
+Reg #11 a_1 0
+Reg #12 %t12 12
+Reg #13 a_2 0
+Reg #14 %t14 14
+Reg #15 %t15 15
+Reg #16 a_3 0
+Reg #17 %t17 17
+Reg #18 j_3 2
+Reg #19 j_4 2
+Reg #20 j_5 2
+Reg #21 a_4 0
+Reg #22 a_5 0
+Reg #23 a_6 0
+Reg #24 i_3 1
+Reg #25 i_4 1
+Reg #26 %t26 26
+Reg #27 i_5 1
+Reg #28 i_6 1
+Reg #29 i_7 1
+Reg #30 i_8 1
+L0:
+    a = 0
+    i = 0
+    j = 0
+    goto  L2
+L2:
+    a_4 = phi(a, a_1)
+    i_1 = phi(i, i_8)
+    %t3 = i_1<3
+    if %t3 goto L3 else goto L4
+L3:
+    j_1 = 0
+    goto  L5
+L5:
+    a_1 = phi(a_4, a_5)
+    j_2 = phi(j_1, j_5)
+    %t6 = j_2<3
+    if %t6 goto L6 else goto L7
+L6:
+    %t8 = i_1==j_2
+    if %t8 goto L8 else goto L9
+L8:
+    %t10 = a_1+i_1
+    %t12 = %t10+j_2
+    a_2 = %t12
+    goto  L10
+L10:
+    a_5 = phi(a_2, a_6)
+    %t17 = j_2+1
+    j_5 = %t17
+    goto  L5
+L9:
+    %t14 = i_1>j_2
+    if %t14 goto L11 else goto L12
+L11:
+    %t15 = a_1-1
+    a_3 = %t15
+    goto  L12
+L12:
+    a_6 = phi(a_1, a_3)
+    goto  L10
+L7:
+    %t26 = i_1+1
+    i_8 = %t26
+    goto  L2
+L4:
+    ret a_4
+    goto  L1
+L1:
+""", result);
+    }
+
+
     @Test
     public void testSSA17() {
         String src = """
@@ -670,4 +779,446 @@ func merge(begin: Int,middle: Int,end: Int)
 """, result);
     }
 
+    @Test
+    public void testSSA18()
+    {
+        String src = """
+                func foo(len: Int, val: Int, x: Int, y: Int)->[Int] {
+                    if (x > y) {
+                        len=len+x
+                        val=val+x
+                    }
+                    return new [Int]{len=len,value=val} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func foo(len: Int,val: Int,x: Int,y: Int)->[Int]
+Reg #0 len 0
+Reg #1 val 1
+Reg #2 x 2
+Reg #3 y 3
+Reg #4 %t4 4
+Reg #5 %t5 5
+Reg #6 len_1 0
+Reg #7 %t7 7
+Reg #8 val_1 1
+Reg #9 %t9 9
+Reg #10 len_2 0
+Reg #11 val_2 1
+L0:
+    arg len
+    arg val
+    arg x
+    arg y
+    %t4 = x>y
+    if %t4 goto L2 else goto L3
+L2:
+    %t5 = len+x
+    len_1 = %t5
+    %t7 = val+x
+    val_1 = %t7
+    goto  L3
+L3:
+    val_2 = phi(val, val_1)
+    len_2 = phi(len, len_1)
+    %t9 = New([Int], len=len_2, initValue=val_2)
+    ret %t9
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testSSA19()
+    {
+        String src = """
+func bug(N: Int)
+{
+    var p=2
+    while( p < N ) {
+        if (p) {
+            p = p + 1
+        }
+    }
+    while ( p < N ) {
+        p = p + 1
+    }
+}
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func bug(N: Int)
+Reg #0 N 0
+Reg #1 p 1
+Reg #2 %t2 2
+Reg #3 p_1 1
+Reg #4 N_1 0
+Reg #5 %t5 5
+Reg #6 p_2 1
+Reg #7 N_2 0
+Reg #8 p_3 1
+Reg #9 %t9 9
+Reg #10 p_4 1
+Reg #11 N_3 0
+Reg #12 %t12 12
+Reg #13 p_5 1
+Reg #14 N_4 0
+Reg #15 N_5 0
+L0:
+    arg N
+    p = 2
+    goto  L2
+L2:
+    p_1 = phi(p, p_3)
+    %t2 = p_1<N
+    if %t2 goto L3 else goto L4
+L3:
+    if p_1 goto L5 else goto L6
+L5:
+    %t5 = p_1+1
+    p_2 = %t5
+    goto  L6
+L6:
+    p_3 = phi(p_1, p_2)
+    goto  L2
+L4:
+    goto  L7
+L7:
+    p_4 = phi(p_1, p_5)
+    %t9 = p_4<N
+    if %t9 goto L8 else goto L9
+L8:
+    %t12 = p_4+1
+    p_5 = %t12
+    goto  L7
+L9:
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testSSA20()
+    {
+        String src = """
+func sieve(N: Int)->[Int]
+{
+    // The main Sieve array
+    var ary = new [Int]{len=N,value=0}
+    // The primes less than N
+    var primes = new [Int]{len=N/2,value=0}
+    // Number of primes so far, searching at index p
+    var nprimes = 0
+    var p=2
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) {
+            p = p + 1
+        }
+        // p is now a prime
+        primes[nprimes] = p
+        nprimes = nprimes+1
+        // Mark out the rest non-primes
+        var i = p + p
+        while( i < N ) {
+            ary[i] = 1
+            i = i + p
+        }
+        p = p + 1
+    }
+
+    // Now just collect the remaining primes, no more marking
+    while ( p < N ) {
+        if( !ary[p] ) {
+            primes[nprimes] = p
+            nprimes = nprimes + 1
+        }
+        p = p + 1
+    }
+
+    // Copy/shrink the result array
+    var rez = new [Int]{len=nprimes,value=0}
+    var j = 0
+    while( j < nprimes ) {
+        rez[j] = primes[j]
+        j = j + 1
+    }
+    return rez
+}
+func eq(a: [Int], b: [Int], n: Int)->Int
+{
+    var result = 1
+    var i = 0
+    while (i < n)
+    {
+        if (a[i] != b[i])
+        {
+            result = 0
+            break
+        }
+        i = i + 1
+    }
+    return result
+}
+
+func main()->Int
+{
+    var rez = sieve(20)
+    var expected = new [Int]{2,3,5,7,11,13,17,19}
+    return eq(rez,expected,8)
+}
+""";
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func sieve(N: Int)->[Int]
+Reg #0 N 0
+Reg #1 ary 1
+Reg #2 primes 2
+Reg #3 nprimes 3
+Reg #4 p 4
+Reg #5 rez 5
+Reg #6 j 6
+Reg #7 i 7
+Reg #8 %t8 8
+Reg #9 %t9 9
+Reg #10 %t10 10
+Reg #11 %t11 11
+Reg #12 p_1 4
+Reg #13 %t13 13
+Reg #14 N_1 0
+Reg #15 %t15 15
+Reg #16 ary_1 1
+Reg #17 p_2 4
+Reg #18 %t18 18
+Reg #19 p_3 4
+Reg #20 ary_2 1
+Reg #21 primes_1 2
+Reg #22 primes_2 2
+Reg #23 nprimes_1 3
+Reg #24 nprimes_2 3
+Reg #25 %t25 25
+Reg #26 nprimes_3 3
+Reg #27 %t27 27
+Reg #28 %t28 28
+Reg #29 i_1 7
+Reg #30 N_2 0
+Reg #31 ary_3 1
+Reg #32 %t32 32
+Reg #33 p_4 4
+Reg #34 i_2 7
+Reg #35 N_3 0
+Reg #36 ary_4 1
+Reg #37 %t37 37
+Reg #38 p_5 4
+Reg #39 p_6 4
+Reg #40 N_4 0
+Reg #41 ary_5 1
+Reg #42 primes_3 2
+Reg #43 nprimes_4 3
+Reg #44 %t44 44
+Reg #45 p_7 4
+Reg #46 N_5 0
+Reg #47 %t47 47
+Reg #48 ary_6 1
+Reg #49 %t49 49
+Reg #50 primes_4 2
+Reg #51 nprimes_5 3
+Reg #52 %t52 52
+Reg #53 nprimes_6 3
+Reg #54 %t54 54
+Reg #55 p_8 4
+Reg #56 p_9 4
+Reg #57 N_6 0
+Reg #58 N_7 0
+Reg #59 N_8 0
+Reg #60 N_9 0
+Reg #61 ary_7 1
+Reg #62 ary_8 1
+Reg #63 ary_9 1
+Reg #64 ary_10 1
+Reg #65 primes_5 2
+Reg #66 primes_6 2
+Reg #67 primes_7 2
+Reg #68 primes_8 2
+Reg #69 nprimes_7 3
+Reg #70 %t70 70
+Reg #71 %t71 71
+Reg #72 j_1 6
+Reg #73 nprimes_8 3
+Reg #74 %t74 74
+Reg #75 primes_9 2
+Reg #76 rez_1 5
+Reg #77 %t77 77
+Reg #78 j_2 6
+Reg #79 primes_10 2
+Reg #80 primes_11 2
+Reg #81 rez_2 5
+L0:
+    arg N
+    %t8 = New([Int], len=N, initValue=0)
+    ary = %t8
+    %t10 = N/2
+    %t9 = New([Int], len=%t10, initValue=0)
+    primes = %t9
+    nprimes = 0
+    p = 2
+    goto  L2
+L2:
+    nprimes_2 = phi(nprimes, nprimes_3)
+    p_1 = phi(p, p_6)
+    %t11 = p_1*p_1
+    %t13 = %t11<N
+    if %t13 goto L3 else goto L4
+L3:
+    goto  L5
+L5:
+    p_2 = phi(p_1, p_3)
+    %t15 = ary[p_2]
+    if %t15 goto L6 else goto L7
+L6:
+    %t18 = p_2+1
+    p_3 = %t18
+    goto  L5
+L7:
+    primes[nprimes_2] = p_2
+    %t25 = nprimes_2+1
+    nprimes_3 = %t25
+    %t27 = p_2+p_2
+    i = %t27
+    goto  L8
+L8:
+    i_1 = phi(i, i_2)
+    %t28 = i_1<N
+    if %t28 goto L9 else goto L10
+L9:
+    ary[i_1] = 1
+    %t32 = i_1+p_2
+    i_2 = %t32
+    goto  L8
+L10:
+    %t37 = p_2+1
+    p_6 = %t37
+    goto  L2
+L4:
+    goto  L11
+L11:
+    nprimes_5 = phi(nprimes_2, nprimes_7)
+    p_7 = phi(p_1, p_9)
+    %t44 = p_7<N
+    if %t44 goto L12 else goto L13
+L12:
+    %t47 = ary[p_7]
+    %t49 = !%t47
+    if %t49 goto L14 else goto L15
+L14:
+    primes[nprimes_5] = p_7
+    %t52 = nprimes_5+1
+    nprimes_6 = %t52
+    goto  L15
+L15:
+    nprimes_7 = phi(nprimes_5, nprimes_6)
+    %t54 = p_7+1
+    p_9 = %t54
+    goto  L11
+L13:
+    %t70 = New([Int], len=nprimes_5, initValue=0)
+    rez = %t70
+    j = 0
+    goto  L16
+L16:
+    j_1 = phi(j, j_2)
+    %t71 = j_1<nprimes_5
+    if %t71 goto L17 else goto L18
+L17:
+    %t74 = primes[j_1]
+    rez[j_1] = %t74
+    %t77 = j_1+1
+    j_2 = %t77
+    goto  L16
+L18:
+    ret rez
+    goto  L1
+L1:
+func eq(a: [Int],b: [Int],n: Int)->Int
+Reg #0 a 0
+Reg #1 b 1
+Reg #2 n 2
+Reg #3 result 3
+Reg #4 i 4
+Reg #5 %t5 5
+Reg #6 i_1 4
+Reg #7 n_1 2
+Reg #8 %t8 8
+Reg #9 a_1 0
+Reg #10 %t10 10
+Reg #11 b_1 1
+Reg #12 %t12 12
+Reg #13 result_1 3
+Reg #14 %t14 14
+Reg #15 i_2 4
+Reg #16 result_2 3
+Reg #17 result_3 3
+L0:
+    arg a
+    arg b
+    arg n
+    result = 1
+    i = 0
+    goto  L2
+L2:
+    i_1 = phi(i, i_2)
+    %t5 = i_1<n
+    if %t5 goto L3 else goto L4
+L3:
+    %t8 = a[i_1]
+    %t10 = b[i_1]
+    %t12 = %t8!=%t10
+    if %t12 goto L5 else goto L6
+L5:
+    result_1 = 0
+    goto  L4
+L4:
+    result_2 = phi(result, result_1)
+    ret result_2
+    goto  L1
+L1:
+L6:
+    %t14 = i_1+1
+    i_2 = %t14
+    goto  L2
+func main()->Int
+Reg #0 rez 0
+Reg #1 expected 1
+Reg #2 %t2 2
+Reg #3 %t3 3
+Reg #4 %t4 4
+Reg #5 %t5 5
+Reg #6 %t6 6
+Reg #7 %t7 7
+Reg #8 %t8 8
+L0:
+    %t2 = 20
+    %t3 = call sieve params %t2
+    rez = %t3
+    %t4 = New([Int], len=8)
+    %t4[0] = 2
+    %t4[1] = 3
+    %t4[2] = 5
+    %t4[3] = 7
+    %t4[4] = 11
+    %t4[5] = 13
+    %t4[6] = 17
+    %t4[7] = 19
+    expected = %t4
+    %t5 = rez
+    %t6 = expected
+    %t7 = 8
+    %t8 = call eq params %t5, %t6, %t7
+    ret %t8
+    goto  L1
+L1:
+""", result);
+    }
 }
\ No newline at end of file
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestSSATransform.java b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestSSATransform.java
index c8b5d6a..02aeb01 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestSSATransform.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/compiler/TestSSATransform.java
@@ -24,10 +24,13 @@ String compileSrc(String src) {
                 sb.append("Before SSA\n");
                 sb.append("==========\n");
                 BasicBlock.toStr(sb, functionBuilder.entry, new BitSet(), false);
+                //functionBuilder.toDot(sb,false);
                 new EnterSSA(functionBuilder, Options.NONE);
+                //new EnterSSA(functionBuilder, EnumSet.of(DUMP_PRE_SSA_DOMFRONTIERS));
                 sb.append("After SSA\n");
                 sb.append("=========\n");
                 BasicBlock.toStr(sb, functionBuilder.entry, new BitSet(), false);
+                //functionBuilder.toDot(sb,false);
                 new ExitSSA(functionBuilder, Options.NONE);
                 sb.append("After exiting SSA\n");
                 sb.append("=================\n");
@@ -1662,7 +1665,7 @@ func foo()->Int {
 Before SSA
 ==========
 L0:
-    %t2 = New([Int])
+    %t2 = New([Int], len=2)
     %t2[0] = 1
     %t2[1] = 2
     arr = %t2
@@ -1675,7 +1678,7 @@ func foo()->Int {
 After SSA
 =========
 L0:
-    %t2_0 = New([Int])
+    %t2_0 = New([Int], len=2)
     %t2_0[0] = 1
     %t2_0[1] = 2
     arr_0 = %t2_0
@@ -1688,7 +1691,7 @@ func foo()->Int {
 After exiting SSA
 =================
 L0:
-    %t2_0 = New([Int])
+    %t2_0 = New([Int], len=2)
     %t2_0[0] = 1
     %t2_0[1] = 2
     arr_0 = %t2_0
@@ -2276,7 +2279,7 @@ else if (i > j)
     %t5_0 = i_1==j_2
     if %t5_0 goto L8 else goto L9
 L8:
-    %t6_0 = a_4+i_1
+    %t6_0 = a_2+i_1
     %t7_0 = %t6_0+j_2
     a_5 = %t7_0
     goto  L10
@@ -2327,7 +2330,7 @@ else if (i > j)
     %t5_0 = i_1==j_2
     if %t5_0 goto L8 else goto L9
 L8:
-    %t6_0 = a_4+i_1
+    %t6_0 = a_2+i_1
     %t7_0 = %t6_0+j_2
     a_5 = %t7_0
     a_6 = a_5
@@ -2781,7 +2784,7 @@ func foo()->Int
 Before SSA
 ==========
 L0:
-    %t1 = New([Foo?])
+    %t1 = New([Foo?], len=2)
     %t2 = New(Foo)
     %t2.i = 1
     %t1[0] = %t2
@@ -2805,7 +2808,7 @@ func foo()->Int
 After SSA
 =========
 L0:
-    %t1_0 = New([Foo?])
+    %t1_0 = New([Foo?], len=2)
     %t2_0 = New(Foo)
     %t2_0.i = 1
     %t1_0[0] = %t2_0
@@ -2830,7 +2833,7 @@ func foo()->Int
 After exiting SSA
 =================
 L0:
-    %t1_0 = New([Foo?])
+    %t1_0 = New([Foo?], len=2)
     %t2_0 = New(Foo)
     %t2_0.i = 1
     %t1_0[0] = %t2_0
@@ -2973,6 +2976,712 @@ func merge(begin: Int, middle: Int, end: Int)
 L3:
     goto  L1
 L1:
+""", result);
+    }
+
+    @Test
+    public void testSSA18()
+    {
+        String src = """
+                func foo(len: Int, val: Int, x: Int, y: Int)->[Int] {
+                    if (x > y) {
+                        len=len+x
+                        val=val+x
+                    }
+                    return new [Int]{len=len,value=val} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func foo
+Before SSA
+==========
+L0:
+    arg len
+    arg val
+    arg x
+    arg y
+    %t4 = x>y
+    if %t4 goto L2 else goto L3
+L2:
+    %t5 = len+x
+    len = %t5
+    %t6 = val+x
+    val = %t6
+    goto  L3
+L3:
+    %t7 = New([Int], len=len, initValue=val)
+    ret %t7
+    goto  L1
+L1:
+After SSA
+=========
+L0:
+    arg len_0
+    arg val_0
+    arg x_0
+    arg y_0
+    %t4_0 = x_0>y_0
+    if %t4_0 goto L2 else goto L3
+L2:
+    %t5_0 = len_0+x_0
+    len_1 = %t5_0
+    %t6_0 = val_0+x_0
+    val_1 = %t6_0
+    goto  L3
+L3:
+    val_2 = phi(val_0, val_1)
+    len_2 = phi(len_0, len_1)
+    %t7_0 = New([Int], len=len_2, initValue=val_2)
+    ret %t7_0
+    goto  L1
+L1:
+After exiting SSA
+=================
+L0:
+    arg len_0
+    arg val_0
+    arg x_0
+    arg y_0
+    %t4_0 = x_0>y_0
+    val_2 = val_0
+    len_2 = len_0
+    if %t4_0 goto L2 else goto L3
+L2:
+    %t5_0 = len_0+x_0
+    len_1 = %t5_0
+    %t6_0 = val_0+x_0
+    val_1 = %t6_0
+    val_2 = val_1
+    len_2 = len_1
+    goto  L3
+L3:
+    %t7_0 = New([Int], len=len_2, initValue=val_2)
+    ret %t7_0
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testSSA19()
+    {
+        String src = """
+func bug(N: Int)
+{
+    var p=2
+    while( p < N ) {
+        if (p) {
+            p = p + 1
+        }
+    }
+    while ( p < N ) {
+        p = p + 1
+    }
+}
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func bug
+Before SSA
+==========
+L0:
+    arg N
+    p = 2
+    goto  L2
+L2:
+    %t2 = p<N
+    if %t2 goto L3 else goto L4
+L3:
+    if p goto L5 else goto L6
+L5:
+    %t3 = p+1
+    p = %t3
+    goto  L6
+L6:
+    goto  L2
+L4:
+    goto  L7
+L7:
+    %t4 = p<N
+    if %t4 goto L8 else goto L9
+L8:
+    %t5 = p+1
+    p = %t5
+    goto  L7
+L9:
+    goto  L1
+L1:
+After SSA
+=========
+L0:
+    arg N_0
+    p_0 = 2
+    goto  L2
+L2:
+    p_1 = phi(p_0, p_5)
+    %t2_0 = p_1<N_0
+    if %t2_0 goto L3 else goto L4
+L3:
+    if p_1 goto L5 else goto L6
+L5:
+    %t3_0 = p_1+1
+    p_4 = %t3_0
+    goto  L6
+L6:
+    p_5 = phi(p_1, p_4)
+    goto  L2
+L4:
+    goto  L7
+L7:
+    p_2 = phi(p_1, p_3)
+    %t4_0 = p_2<N_0
+    if %t4_0 goto L8 else goto L9
+L8:
+    %t5_0 = p_2+1
+    p_3 = %t5_0
+    goto  L7
+L9:
+    goto  L1
+L1:
+After exiting SSA
+=================
+L0:
+    arg N_0
+    p_0 = 2
+    p_1 = p_0
+    goto  L2
+L2:
+    %t2_0 = p_1<N_0
+    if %t2_0 goto L3 else goto L4
+L3:
+    p_5 = p_1
+    if p_1 goto L5 else goto L6
+L5:
+    %t3_0 = p_1+1
+    p_4 = %t3_0
+    p_5 = p_4
+    goto  L6
+L6:
+    p_1 = p_5
+    goto  L2
+L4:
+    p_2 = p_1
+    goto  L7
+L7:
+    %t4_0 = p_2<N_0
+    if %t4_0 goto L8 else goto L9
+L8:
+    %t5_0 = p_2+1
+    p_3 = %t5_0
+    p_2 = p_3
+    goto  L7
+L9:
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testSSA20()
+    {
+        String src = """
+func sieve(N: Int)->[Int]
+{
+    // The main Sieve array
+    var ary = new [Int]{len=N,value=0}
+    // The primes less than N
+    var primes = new [Int]{len=N/2,value=0}
+    // Number of primes so far, searching at index p
+    var nprimes = 0
+    var p=2
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) {
+            p = p + 1
+        }
+        // p is now a prime
+        primes[nprimes] = p
+        nprimes = nprimes+1
+        // Mark out the rest non-primes
+        var i = p + p
+        while( i < N ) {
+            ary[i] = 1
+            i = i + p
+        }
+        p = p + 1
+    }
+
+    // Now just collect the remaining primes, no more marking
+    while ( p < N ) {
+        if( !ary[p] ) {
+            primes[nprimes] = p
+            nprimes = nprimes + 1
+        }
+        p = p + 1
+    }
+
+    // Copy/shrink the result array
+    var rez = new [Int]{len=nprimes,value=0}
+    var j = 0
+    while( j < nprimes ) {
+        rez[j] = primes[j]
+        j = j + 1
+    }
+    return rez
+}
+func eq(a: [Int], b: [Int], n: Int)->Int
+{
+    var result = 1
+    var i = 0
+    while (i < n)
+    {
+        if (a[i] != b[i])
+        {
+            result = 0
+            break
+        }
+        i = i + 1
+    }
+    return result
+}
+
+func main()->Int
+{
+    var rez = sieve(20)
+    var expected = new [Int]{2,3,5,7,11,13,17,19}
+    return eq(rez,expected,8)
+}
+""";
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+func sieve
+Before SSA
+==========
+L0:
+    arg N
+    %t8 = New([Int], len=N, initValue=0)
+    ary = %t8
+    %t10 = N/2
+    %t9 = New([Int], len=%t10, initValue=0)
+    primes = %t9
+    nprimes = 0
+    p = 2
+    goto  L2
+L2:
+    %t11 = p*p
+    %t12 = %t11<N
+    if %t12 goto L3 else goto L4
+L3:
+    goto  L5
+L5:
+    %t13 = ary[p]
+    if %t13 goto L6 else goto L7
+L6:
+    %t14 = p+1
+    p = %t14
+    goto  L5
+L7:
+    primes[nprimes] = p
+    %t15 = nprimes+1
+    nprimes = %t15
+    %t16 = p+p
+    i = %t16
+    goto  L8
+L8:
+    %t17 = i<N
+    if %t17 goto L9 else goto L10
+L9:
+    ary[i] = 1
+    %t18 = i+p
+    i = %t18
+    goto  L8
+L10:
+    %t19 = p+1
+    p = %t19
+    goto  L2
+L4:
+    goto  L11
+L11:
+    %t20 = p<N
+    if %t20 goto L12 else goto L13
+L12:
+    %t21 = ary[p]
+    %t22 = !%t21
+    if %t22 goto L14 else goto L15
+L14:
+    primes[nprimes] = p
+    %t23 = nprimes+1
+    nprimes = %t23
+    goto  L15
+L15:
+    %t24 = p+1
+    p = %t24
+    goto  L11
+L13:
+    %t25 = New([Int], len=nprimes, initValue=0)
+    rez = %t25
+    j = 0
+    goto  L16
+L16:
+    %t26 = j<nprimes
+    if %t26 goto L17 else goto L18
+L17:
+    %t27 = primes[j]
+    rez[j] = %t27
+    %t28 = j+1
+    j = %t28
+    goto  L16
+L18:
+    ret rez
+    goto  L1
+L1:
+After SSA
+=========
+L0:
+    arg N_0
+    %t8_0 = New([Int], len=N_0, initValue=0)
+    ary_0 = %t8_0
+    %t10_0 = N_0/2
+    %t9_0 = New([Int], len=%t10_0, initValue=0)
+    primes_0 = %t9_0
+    nprimes_0 = 0
+    p_0 = 2
+    goto  L2
+L2:
+    p_1 = phi(p_0, p_5)
+    nprimes_1 = phi(nprimes_0, nprimes_5)
+    %t11_0 = p_1*p_1
+    %t12_0 = %t11_0<N_0
+    if %t12_0 goto L3 else goto L4
+L3:
+    goto  L5
+L5:
+    p_4 = phi(p_1, p_6)
+    %t13_0 = ary_0[p_4]
+    if %t13_0 goto L6 else goto L7
+L6:
+    %t14_0 = p_4+1
+    p_6 = %t14_0
+    goto  L5
+L7:
+    primes_0[nprimes_1] = p_4
+    %t15_0 = nprimes_1+1
+    nprimes_5 = %t15_0
+    %t16_0 = p_4+p_4
+    i_0 = %t16_0
+    goto  L8
+L8:
+    i_1 = phi(i_0, i_2)
+    %t17_0 = i_1<N_0
+    if %t17_0 goto L9 else goto L10
+L9:
+    ary_0[i_1] = 1
+    %t18_0 = i_1+p_4
+    i_2 = %t18_0
+    goto  L8
+L10:
+    %t19_0 = p_4+1
+    p_5 = %t19_0
+    goto  L2
+L4:
+    goto  L11
+L11:
+    p_2 = phi(p_1, p_3)
+    nprimes_2 = phi(nprimes_1, nprimes_4)
+    %t20_0 = p_2<N_0
+    if %t20_0 goto L12 else goto L13
+L12:
+    %t21_0 = ary_0[p_2]
+    %t22_0 = !%t21_0
+    if %t22_0 goto L14 else goto L15
+L14:
+    primes_0[nprimes_2] = p_2
+    %t23_0 = nprimes_2+1
+    nprimes_3 = %t23_0
+    goto  L15
+L15:
+    nprimes_4 = phi(nprimes_2, nprimes_3)
+    %t24_0 = p_2+1
+    p_3 = %t24_0
+    goto  L11
+L13:
+    %t25_0 = New([Int], len=nprimes_2, initValue=0)
+    rez_0 = %t25_0
+    j_0 = 0
+    goto  L16
+L16:
+    j_1 = phi(j_0, j_2)
+    %t26_0 = j_1<nprimes_2
+    if %t26_0 goto L17 else goto L18
+L17:
+    %t27_0 = primes_0[j_1]
+    rez_0[j_1] = %t27_0
+    %t28_0 = j_1+1
+    j_2 = %t28_0
+    goto  L16
+L18:
+    ret rez_0
+    goto  L1
+L1:
+After exiting SSA
+=================
+L0:
+    arg N_0
+    %t8_0 = New([Int], len=N_0, initValue=0)
+    ary_0 = %t8_0
+    %t10_0 = N_0/2
+    %t9_0 = New([Int], len=%t10_0, initValue=0)
+    primes_0 = %t9_0
+    nprimes_0 = 0
+    p_0 = 2
+    p_1 = p_0
+    nprimes_1 = nprimes_0
+    goto  L2
+L2:
+    %t11_0 = p_1*p_1
+    %t12_0 = %t11_0<N_0
+    if %t12_0 goto L3 else goto L4
+L3:
+    p_4 = p_1
+    goto  L5
+L5:
+    %t13_0 = ary_0[p_4]
+    if %t13_0 goto L6 else goto L7
+L6:
+    %t14_0 = p_4+1
+    p_6 = %t14_0
+    p_4 = p_6
+    goto  L5
+L7:
+    primes_0[nprimes_1] = p_4
+    %t15_0 = nprimes_1+1
+    nprimes_5 = %t15_0
+    %t16_0 = p_4+p_4
+    i_0 = %t16_0
+    i_1 = i_0
+    goto  L8
+L8:
+    %t17_0 = i_1<N_0
+    if %t17_0 goto L9 else goto L10
+L9:
+    ary_0[i_1] = 1
+    %t18_0 = i_1+p_4
+    i_2 = %t18_0
+    i_1 = i_2
+    goto  L8
+L10:
+    %t19_0 = p_4+1
+    p_5 = %t19_0
+    p_1 = p_5
+    nprimes_1 = nprimes_5
+    goto  L2
+L4:
+    p_2 = p_1
+    nprimes_2 = nprimes_1
+    goto  L11
+L11:
+    %t20_0 = p_2<N_0
+    if %t20_0 goto L12 else goto L13
+L12:
+    %t21_0 = ary_0[p_2]
+    %t22_0 = !%t21_0
+    nprimes_4 = nprimes_2
+    if %t22_0 goto L14 else goto L15
+L14:
+    primes_0[nprimes_2] = p_2
+    %t23_0 = nprimes_2+1
+    nprimes_3 = %t23_0
+    nprimes_4 = nprimes_3
+    goto  L15
+L15:
+    %t24_0 = p_2+1
+    p_3 = %t24_0
+    p_2 = p_3
+    nprimes_2 = nprimes_4
+    goto  L11
+L13:
+    %t25_0 = New([Int], len=nprimes_2, initValue=0)
+    rez_0 = %t25_0
+    j_0 = 0
+    j_1 = j_0
+    goto  L16
+L16:
+    %t26_0 = j_1<nprimes_2
+    if %t26_0 goto L17 else goto L18
+L17:
+    %t27_0 = primes_0[j_1]
+    rez_0[j_1] = %t27_0
+    %t28_0 = j_1+1
+    j_2 = %t28_0
+    j_1 = j_2
+    goto  L16
+L18:
+    ret rez_0
+    goto  L1
+L1:
+func eq
+Before SSA
+==========
+L0:
+    arg a
+    arg b
+    arg n
+    result = 1
+    i = 0
+    goto  L2
+L2:
+    %t5 = i<n
+    if %t5 goto L3 else goto L4
+L3:
+    %t6 = a[i]
+    %t7 = b[i]
+    %t8 = %t6!=%t7
+    if %t8 goto L5 else goto L6
+L5:
+    result = 0
+    goto  L4
+L4:
+    ret result
+    goto  L1
+L1:
+L6:
+    %t9 = i+1
+    i = %t9
+    goto  L2
+After SSA
+=========
+L0:
+    arg a_0
+    arg b_0
+    arg n_0
+    result_0 = 1
+    i_0 = 0
+    goto  L2
+L2:
+    i_1 = phi(i_0, i_2)
+    %t5_0 = i_1<n_0
+    if %t5_0 goto L3 else goto L4
+L3:
+    %t6_0 = a_0[i_1]
+    %t7_0 = b_0[i_1]
+    %t8_0 = %t6_0!=%t7_0
+    if %t8_0 goto L5 else goto L6
+L5:
+    result_1 = 0
+    goto  L4
+L4:
+    result_2 = phi(result_0, result_1)
+    ret result_2
+    goto  L1
+L1:
+L6:
+    %t9_0 = i_1+1
+    i_2 = %t9_0
+    goto  L2
+After exiting SSA
+=================
+L0:
+    arg a_0
+    arg b_0
+    arg n_0
+    result_0 = 1
+    i_0 = 0
+    i_1 = i_0
+    goto  L2
+L2:
+    %t5_0 = i_1<n_0
+    result_2 = result_0
+    if %t5_0 goto L3 else goto L4
+L3:
+    %t6_0 = a_0[i_1]
+    %t7_0 = b_0[i_1]
+    %t8_0 = %t6_0!=%t7_0
+    if %t8_0 goto L5 else goto L6
+L5:
+    result_1 = 0
+    result_2 = result_1
+    goto  L4
+L4:
+    ret result_2
+    goto  L1
+L1:
+L6:
+    %t9_0 = i_1+1
+    i_2 = %t9_0
+    i_1 = i_2
+    goto  L2
+func main
+Before SSA
+==========
+L0:
+    %t2 = 20
+    %t3 = call sieve params %t2
+    rez = %t3
+    %t4 = New([Int], len=8)
+    %t4[0] = 2
+    %t4[1] = 3
+    %t4[2] = 5
+    %t4[3] = 7
+    %t4[4] = 11
+    %t4[5] = 13
+    %t4[6] = 17
+    %t4[7] = 19
+    expected = %t4
+    %t5 = rez
+    %t6 = expected
+    %t7 = 8
+    %t8 = call eq params %t5, %t6, %t7
+    ret %t8
+    goto  L1
+L1:
+After SSA
+=========
+L0:
+    %t2_0 = 20
+    %t3_0 = call sieve params %t2_0
+    rez_0 = %t3_0
+    %t4_0 = New([Int], len=8)
+    %t4_0[0] = 2
+    %t4_0[1] = 3
+    %t4_0[2] = 5
+    %t4_0[3] = 7
+    %t4_0[4] = 11
+    %t4_0[5] = 13
+    %t4_0[6] = 17
+    %t4_0[7] = 19
+    expected_0 = %t4_0
+    %t5_0 = rez_0
+    %t6_0 = expected_0
+    %t7_0 = 8
+    %t8_0 = call eq params %t5_0, %t6_0, %t7_0
+    ret %t8_0
+    goto  L1
+L1:
+After exiting SSA
+=================
+L0:
+    %t2_0 = 20
+    %t3_0 = call sieve params %t2_0
+    rez_0 = %t3_0
+    %t4_0 = New([Int], len=8)
+    %t4_0[0] = 2
+    %t4_0[1] = 3
+    %t4_0[2] = 5
+    %t4_0[3] = 7
+    %t4_0[4] = 11
+    %t4_0[5] = 13
+    %t4_0[6] = 17
+    %t4_0[7] = 19
+    expected_0 = %t4_0
+    %t5_0 = rez_0
+    %t6_0 = expected_0
+    %t7_0 = 8
+    %t8_0 = call eq params %t5_0, %t6_0, %t7_0
+    ret %t8_0
+    goto  L1
+L1:
 """, result);
     }
 }
\ No newline at end of file
diff --git a/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java b/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
index 78af875..456d232 100644
--- a/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
+++ b/optvm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
@@ -693,4 +693,105 @@ func main()->Int
                 integerValue.value == 1);
     }
 
+    @Test
+    public void testFunction108() {
+        String src = """
+                func make(len: Int, val: Int)->[Int]
+                {
+                    return new [Int]{len=len, value=val}
+                }
+                func main()->Int
+                {
+                    var arr = make(3,3);
+                    var i = 0
+                    while (i < 3) {
+                        if (arr[i] != 3)
+                            return 1
+                        i = i + 1
+                    }
+                    return 0
+                }
+                """;
+        var value = compileAndRun(src, "main", Options.OPT);
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue &&
+                integerValue.value == 0);
+    }
+
+    @Test
+    public void testFunction109() {
+        String src = """
+func sieve(N: Int)->[Int]
+{
+    // The main Sieve array
+    var ary = new [Int]{len=N,value=0}
+    // The primes less than N
+    var primes = new [Int]{len=N/2,value=0}
+    // Number of primes so far, searching at index p
+    var nprimes = 0
+    var p=2
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) {
+            p = p + 1
+        }
+        // p is now a prime
+        primes[nprimes] = p
+        nprimes = nprimes+1
+        // Mark out the rest non-primes
+        var i = p + p
+        while( i < N ) {
+            ary[i] = 1
+            i = i + p
+        }
+        p = p + 1
+    }
+
+    // Now just collect the remaining primes, no more marking
+    while ( p < N ) {
+        if( !ary[p] ) {
+            primes[nprimes] = p
+            nprimes = nprimes + 1
+        }
+        p = p + 1
+    }
+
+    // Copy/shrink the result array
+    var rez = new [Int]{len=nprimes,value=0}
+    var j = 0
+    while( j < nprimes ) {
+        rez[j] = primes[j]
+        j = j + 1
+    }
+    return rez
+}
+func eq(a: [Int], b: [Int], n: Int)->Int
+{
+    var result = 1
+    var i = 0
+    while (i < n)
+    {
+        if (a[i] != b[i])
+        {
+            result = 0
+            break
+        }
+        i = i + 1
+    }
+    return result
+}
+
+func main()->Int
+{
+    var rez = sieve(20)
+    var expected = new [Int]{2,3,5,7,11,13,17,19}
+    return eq(rez,expected,8)
+}
+""";
+        var value = compileAndRun(src, "main");
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue &&
+                integerValue.value == 1);
+    }
 }
diff --git a/parser/src/main/java/com/compilerprogramming/ezlang/parser/AST.java b/parser/src/main/java/com/compilerprogramming/ezlang/parser/AST.java
index 46bcf78..162dd29 100644
--- a/parser/src/main/java/com/compilerprogramming/ezlang/parser/AST.java
+++ b/parser/src/main/java/com/compilerprogramming/ezlang/parser/AST.java
@@ -545,14 +545,17 @@ public void accept(ASTVisitor visitor) {
      */
     public static class NewExpr extends Expr {
         public final TypeExpr typeExpr;
-        public final long len; // temp hack, as this needs to be an expression rather than constant
+        public final Expr len;
+        public final Expr initValue;
         public NewExpr(TypeExpr typeExpr) {
             this.typeExpr = typeExpr;
-            this.len = 0;
+            this.len = null;
+            this.initValue = null;
         }
-        public NewExpr(TypeExpr typeExpr, long len) {
+        public NewExpr(TypeExpr typeExpr, Expr len, Expr initValue) {
             this.typeExpr = typeExpr;
             this.len = len;
+            this.initValue = initValue;
         }
         @Override
         public StringBuilder toStr(StringBuilder sb) {
@@ -566,6 +569,11 @@ public void accept(ASTVisitor visitor) {
             if (visitor == null)
                 return;
             typeExpr.accept(visitor);
+            if (len != null) {
+                len.accept(visitor);
+                if (initValue != null)
+                    initValue.accept(visitor);
+            }
             visitor.visit(this, false);
         }
     }
@@ -579,12 +587,7 @@ public static class InitExpr extends Expr {
         public final List<Expr> initExprList;
         public InitExpr(NewExpr newExpr, List<Expr> initExprList) {
             this.initExprList = initExprList;
-            // For arrays we compute length based on number of elements
-            // This is not actually correct - see https://github.com/CompilerProgramming/ez-lang/issues/47
-            if (initExprList.size() != newExpr.len)
-                this.newExpr = new NewExpr(newExpr.typeExpr,initExprList.size());
-            else
-                this.newExpr = newExpr;
+            this.newExpr = newExpr;
         }
         @Override
         public StringBuilder toStr(StringBuilder sb) {
diff --git a/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java b/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
index 821ce6c..423040b 100644
--- a/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
+++ b/parser/src/main/java/com/compilerprogramming/ezlang/parser/Parser.java
@@ -333,6 +333,8 @@ private AST.Expr parseNew(Lexer lexer) {
         matchIdentifier(lexer, "new");
         AST.TypeExpr resultType = parseTypeExpr(lexer);
         var newExpr = new AST.NewExpr(resultType);
+        AST.Expr lenExpr = null;
+        AST.Expr initValueExpr = null;
         List<AST.Expr> initExpr = new ArrayList<>();
         int index = 0;
         if (testPunctuation(lexer, "{")) {
@@ -343,10 +345,14 @@ private AST.Expr parseNew(Lexer lexer) {
                     matchPunctuation(lexer, "=");
                     AST.Expr value = parseBool(lexer);
                     initExpr.add(new AST.InitFieldExpr(newExpr, fieldname, value));
+                    if (fieldname.equals("len"))
+                        lenExpr = value;
+                    else if (fieldname.equals("value"))
+                        initValueExpr = value;
                 }
                 else {
                     var indexLit = Integer.valueOf(index++);
-                    var indexExpr = new AST.LiteralExpr(Token.newNum(indexLit,indexLit.toString(),0));
+                    var indexExpr = new AST.LiteralExpr(Token.newNum(indexLit,indexLit.toString(),currentToken.lineNumber));
                     initExpr.add(new AST.ArrayInitExpr(newExpr, indexExpr, parseBool(lexer)));
                 }
                 if (isToken(currentToken, ","))
@@ -355,6 +361,12 @@ private AST.Expr parseNew(Lexer lexer) {
             }
         }
         matchPunctuation(lexer, "}");
+        if (initExpr.size() > 0 && lenExpr == null) {
+            var sizeLit = Integer.valueOf(initExpr.size());
+            lenExpr = new AST.LiteralExpr(Token.newNum(sizeLit,sizeLit.toString(),currentToken.lineNumber));
+        }
+        if (lenExpr != null)
+            return new AST.InitExpr(new AST.NewExpr(newExpr.typeExpr, lenExpr, initValueExpr), initExpr);
         return new AST.InitExpr(newExpr, initExpr);
     }
 
diff --git a/parser/src/test/java/com/compilerprogramming/ezlang/parser/TestParser.java b/parser/src/test/java/com/compilerprogramming/ezlang/parser/TestParser.java
index 1c60dc0..b4966c3 100644
--- a/parser/src/test/java/com/compilerprogramming/ezlang/parser/TestParser.java
+++ b/parser/src/test/java/com/compilerprogramming/ezlang/parser/TestParser.java
@@ -36,7 +36,7 @@ func bar() -> Test {
 func main() {
     var m = 42
     var t: Tree
-    var array = new [Int] {size=10,1,2,3}
+    var array = new [Int] {len=10,1,2,3}
     array[1] = 42
     t.left = null
     if (m < 1)
diff --git a/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java b/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
index 9433d5c..3071909 100644
--- a/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
+++ b/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/CompiledFunction.java
@@ -383,7 +383,7 @@ private boolean compileArrayStoreExpr(AST.ArrayStoreExpr arrayStoreExpr) {
     }
 
     private boolean compileNewExpr(AST.NewExpr newExpr) {
-        codeNew(newExpr.type);
+        codeNew(newExpr.type,newExpr.len,newExpr.initValue);
         return false;
     }
 
@@ -603,13 +603,42 @@ else if (indexed instanceof Operand.LoadFieldOperand loadFieldOperand)
             code(new Instruction.Move(value, indexed));
     }
 
-    private void codeNew(Type type) {
-        var temp = createTemp(type);
+    private void codeNew(Type type, AST.Expr len, AST.Expr initVal) {
         if (type instanceof Type.TypeArray typeArray)
-            code(new Instruction.NewArray(typeArray, temp));
-        else if (type instanceof Type.TypeStruct typeStruct)
+            codeNewArray(typeArray, len, initVal);
+        else if (type instanceof Type.TypeStruct typeStruct) {
+            var temp = createTemp(type);
             code(new Instruction.NewStruct(typeStruct, temp));
+        }
         else
             throw new CompilerException("Unexpected type: " + type);
     }
+
+    private void codeNewArray(Type.TypeArray typeArray, AST.Expr len, AST.Expr initVal) {
+        var temp = createTemp(typeArray);
+        Operand lenOperand = null;
+        Operand initValOperand = null;
+        if (len != null) {
+            boolean indexed = compileExpr(len);
+            if (indexed)
+                codeIndexedLoad();
+            if (initVal != null) {
+                indexed = compileExpr(initVal);
+                if (indexed)
+                    codeIndexedLoad();
+                initValOperand = pop();
+            }
+            lenOperand = pop();
+        }
+        Instruction insn;
+        if (lenOperand != null) {
+            if (initValOperand != null)
+                insn = new Instruction.NewArray(typeArray, temp, lenOperand, initValOperand);
+            else
+                insn = new Instruction.NewArray(typeArray, temp, lenOperand);
+        }
+        else
+            insn = new Instruction.NewArray(typeArray, temp);
+        code(insn);
+    }
 }
diff --git a/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java b/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
index a80169a..73b5673 100644
--- a/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
+++ b/registervm/src/main/java/com/compilerprogramming/ezlang/compiler/Instruction.java
@@ -62,14 +62,28 @@ public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand) {
             super(I_NEW_ARRAY, destOperand);
             this.type = type;
         }
+        public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand, Operand len) {
+            super(I_NEW_ARRAY, destOperand, len);
+            this.type = type;
+        }
+        public NewArray(Type.TypeArray type, Operand.RegisterOperand destOperand, Operand len, Operand initValue) {
+            super(I_NEW_ARRAY, destOperand, len, initValue);
+            this.type = type;
+        }
+        public Operand len() { return uses.length > 0 ? uses[0] : null; }
+        public Operand initValue() { return uses.length > 1 ? uses[1] : null; }
         public Operand.RegisterOperand destOperand() { return def; }
         @Override
         public StringBuilder toStr(StringBuilder sb) {
-            return sb.append(def)
+            sb.append(def)
                     .append(" = ")
                     .append("New(")
-                    .append(type)
-                    .append(")");
+                    .append(type);
+            if (len() != null)
+                sb.append(", len=").append(len());
+            if (initValue() != null)
+                sb.append(", initValue=").append(initValue());
+            return sb.append(")");
         }
     }
 
diff --git a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
index 919a82e..f441455 100644
--- a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
+++ b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Interpreter.java
@@ -200,7 +200,19 @@ else if (binaryInst.right() instanceof Operand.RegisterOperand registerOperand)
                     }
                 }
                 case Instruction.NewArray newArrayInst -> {
-                    execStack.stack[base + newArrayInst.destOperand().frameSlot()] = new Value.ArrayValue(newArrayInst.type);
+                    long size = 0;
+                    Value initValue = null;
+                    if (newArrayInst.len() instanceof Operand.ConstantOperand constantOperand)
+                        size = constantOperand.value;
+                    else if (newArrayInst.len() instanceof Operand.RegisterOperand registerOperand) {
+                        Value.IntegerValue indexValue = (Value.IntegerValue) execStack.stack[base + registerOperand.frameSlot()];
+                        size = (long) indexValue.value;
+                    }
+                    if (newArrayInst.initValue() instanceof Operand.ConstantOperand constantOperand)
+                        initValue = new Value.IntegerValue(constantOperand.value);
+                    else if (newArrayInst.initValue() instanceof Operand.RegisterOperand registerOperand)
+                        initValue = execStack.stack[base + registerOperand.frameSlot()];
+                    execStack.stack[base + newArrayInst.destOperand().frameSlot()] = new Value.ArrayValue(newArrayInst.type, size, initValue);
                 }
                 case Instruction.NewStruct newStructInst -> {
                     execStack.stack[base + newStructInst.destOperand().frameSlot()] = new Value.StructValue(newStructInst.type);
diff --git a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
index 7f914a6..6717daa 100644
--- a/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
+++ b/registervm/src/main/java/com/compilerprogramming/ezlang/interpreter/Value.java
@@ -17,9 +17,12 @@ public NullValue() {}
     static public class ArrayValue extends Value {
         public final Type.TypeArray arrayType;
         public final ArrayList<Value> values;
-        public ArrayValue(Type.TypeArray arrayType) {
+        public ArrayValue(Type.TypeArray arrayType, long len, Value initValue) {
             this.arrayType = arrayType;
             values = new ArrayList<>();
+            for (long i = 0; i < len; i++) {
+                values.add(initValue);
+            }
         }
     }
     static public class StructValue extends Value {
diff --git a/registervm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java b/registervm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
index 142b8b6..1461658 100644
--- a/registervm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
+++ b/registervm/src/test/java/com/compilerprogramming/ezlang/compiler/TestCompiler.java
@@ -203,7 +203,7 @@ func foo()->[Int] {
         String result = compileSrc(src);
         Assert.assertEquals("""
                 L0:
-                    %t0 = New([Int])
+                    %t0 = New([Int], len=3)
                     %t0[0] = 1
                     %t0[1] = 2
                     %t0[2] = 3
@@ -223,7 +223,7 @@ func foo(n: Int) -> [Int] {
         String result = compileSrc(src);
         Assert.assertEquals("""
                 L0:
-                    %t1 = New([Int])
+                    %t1 = New([Int], len=1)
                     %t1[0] = n
                     ret %t1
                     goto  L1
@@ -577,6 +577,89 @@ public void testFunction29() {
     ret null
     goto  L1
 L1:
+""", result);
+    }
+
+    @Test
+    public void testFunction30() {
+        String src = """
+                func foo()->[Int] { 
+                    return new [Int]{len=10,value=0} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+L0:
+    %t0 = New([Int], len=10, initValue=0)
+    ret %t0
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testFunction31() {
+        String src = """
+                func foo(len: Int, val: Int)->[Int] { 
+                    return new [Int]{len=len,value=val} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+L0:
+    %t2 = New([Int], len=len, initValue=val)
+    ret %t2
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testFunction32() {
+        String src = """
+                func foo(len: Int, val: Int, x: Int)->[Int] { 
+                    return new [Int]{len=len+x,value=val+x} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+L0:
+    %t4 = len+x
+    %t5 = val+x
+    %t3 = New([Int], len=%t4, initValue=%t5)
+    ret %t3
+    goto  L1
+L1:
+""", result);
+    }
+
+    @Test
+    public void testFunction33() {
+        String src = """
+                func foo(len: Int, val: Int, x: Int, y: Int)->[Int] {
+                    if (x > y) {
+                        len=len+x
+                        val=val+x
+                    }
+                    return new [Int]{len=len,value=val} 
+                }
+                """;
+        String result = compileSrc(src);
+        Assert.assertEquals("""
+L0:
+    %t4 = x>y
+    if %t4 goto L2 else goto L3
+L2:
+    %t4 = len+x
+    len = %t4
+    %t4 = val+x
+    val = %t4
+    goto  L3
+L3:
+    %t4 = New([Int], len=len, initValue=val)
+    ret %t4
+    goto  L1
+L1:
 """, result);
     }
 
diff --git a/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java b/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
index 49f8450..3667caa 100644
--- a/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
+++ b/registervm/src/test/java/com/compilerprogramming/ezlang/interpreter/TestInterpreter.java
@@ -326,6 +326,108 @@ func main()->Int
     merge_sort(a, b, 10)
     return eq(a,expect,10)
 }
+""";
+        var value = compileAndRun(src, "main");
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue &&
+                integerValue.value == 1);
+    }
+
+    @Test
+    public void testFunction108() {
+        String src = """
+                func make(len: Int, val: Int)->[Int]
+                {
+                    return new [Int]{len=len, value=val}
+                }
+                func main()->Int
+                {
+                    var arr = make(3,3);
+                    var i = 0
+                    while (i < 3) {
+                        if (arr[i] != 3)
+                            return 1
+                        i = i + 1
+                    }
+                    return 0
+                }
+                """;
+        var value = compileAndRun(src, "main");
+        Assert.assertNotNull(value);
+        Assert.assertTrue(value instanceof Value.IntegerValue integerValue &&
+                integerValue.value == 0);
+    }
+
+    @Test
+    public void testFunction109() {
+        String src = """
+func sieve(N: Int)->[Int]
+{
+    // The main Sieve array
+    var ary = new [Int]{len=N,value=0}
+    // The primes less than N
+    var primes = new [Int]{len=N/2,value=0}
+    // Number of primes so far, searching at index p
+    var nprimes = 0
+    var p=2
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) {
+            p = p + 1
+        }
+        // p is now a prime
+        primes[nprimes] = p
+        nprimes = nprimes+1
+        // Mark out the rest non-primes
+        var i = p + p
+        while( i < N ) {
+            ary[i] = 1
+            i = i + p
+        }
+        p = p + 1
+    }
+
+    // Now just collect the remaining primes, no more marking
+    while ( p < N ) {
+        if( !ary[p] ) {
+            primes[nprimes] = p
+            nprimes = nprimes + 1
+        }
+        p = p + 1
+    }
+
+    // Copy/shrink the result array
+    var rez = new [Int]{len=nprimes,value=0}
+    var j = 0
+    while( j < nprimes ) {
+        rez[j] = primes[j]
+        j = j + 1
+    }
+    return rez
+}
+func eq(a: [Int], b: [Int], n: Int)->Int
+{
+    var result = 1
+    var i = 0
+    while (i < n)
+    {
+        if (a[i] != b[i])
+        {
+            result = 0
+            break
+        }
+        i = i + 1
+    }
+    return result
+}
+
+func main()->Int
+{
+    var rez = sieve(20)
+    var expected = new [Int]{2,3,5,7,11,13,17,19}
+    return eq(rez,expected,8)
+}
 """;
         var value = compileAndRun(src, "main");
         Assert.assertNotNull(value);
diff --git a/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java b/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
index 46805d5..3d7e546 100644
--- a/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
+++ b/seaofnodes/src/main/java/com/compilerprogramming/ezlang/compiler/Compiler.java
@@ -554,7 +554,7 @@ private Node compileNewExpr(AST.NewExpr newExpr) {
         Type type = newExpr.type;
         if (type instanceof Type.TypeArray typeArray) {
             SONTypeMemPtr tarray = (SONTypeMemPtr) TYPES.get(typeArray.name());
-            return newArray(tarray._obj,newExpr.len==0?ZERO:con(newExpr.len));
+            return newArray(tarray._obj,newExpr.len==null?ZERO:compileExpr(newExpr.len));
         }
         else if (type instanceof Type.TypeStruct typeStruct) {
             SONTypeMemPtr tptr = (SONTypeMemPtr) TYPES.get(typeStruct.name());
diff --git a/seaofnodes/src/test/cases/mergsort/sort.ez b/seaofnodes/src/test/cases/mergsort/sort.ez
index 8ad506d..b5a5ae4 100644
--- a/seaofnodes/src/test/cases/mergsort/sort.ez
+++ b/seaofnodes/src/test/cases/mergsort/sort.ez
@@ -6,14 +6,15 @@ func merge_sort(a: [Int], b: [Int], n: Int)
     split_merge(a, 0, n, b)
 }
 
-func split_merge(b: [Int], begin: Int, end: Int, a: [Int])
+func split_merge(b: [Int], begin: Int, end: Int, a: [Int])->Int
 {
     if (end - begin <= 1)
-        return;
+        return 0
     var middle = (end + begin) / 2
     split_merge(a, begin, middle, b)
     split_merge(a, middle, end, b)
     merge(b, begin, middle, end, a)
+    return 0
 }
 
 func merge(b: [Int], begin: Int, middle: Int, end: Int, a: [Int])
diff --git a/seaofnodes/src/test/cases/mergsort/sort.smp b/seaofnodes/src/test/cases/mergsort/sort.smp
index b82b3f4..d0aeaa4 100644
--- a/seaofnodes/src/test/cases/mergsort/sort.smp
+++ b/seaofnodes/src/test/cases/mergsort/sort.smp
@@ -17,23 +17,34 @@ val split_merge = { int[] b, int begin, int end, int[] a ->
 };
 
 val merge = { int[] b, int begin, int middle, int end, int[] a ->
-    int i = begin, j = middle;
-
-    for (int k = begin; k < end; k++) {
+    int i = begin;
+    int j = middle;
+    int k = begin;
+    while (k < end) {
         // && and ||
         bool cond = false;
         if (i < middle) {
             if (j >= end)          cond = true;
             else if (a[i] <= a[j]) cond = true;
         }
-        if (cond) b[k] = a[i++];
-        else      b[k] = a[j++];
+        if (cond) {
+            b[k] = a[i];
+            i = i + 1;
+        }
+        else {
+            b[k] = a[j];
+            j = j + 1;
+        }
+        k = k + 1;
     }
 };
 
 val copy_array = { int[] a, int begin, int end, int[] b ->
-    for (int k = begin; k < end; k++)
+    int k = begin;
+    while (k < end) {
         b[k] = a[k];
+        k = k + 1;
+    }
 };
 
 val eq = { int[] a, int[] b, int n ->
diff --git a/seaofnodes/src/test/cases/sieve/sieve.ez b/seaofnodes/src/test/cases/sieve/sieve.ez
new file mode 100644
index 0000000..8f4aa4a
--- /dev/null
+++ b/seaofnodes/src/test/cases/sieve/sieve.ez
@@ -0,0 +1,67 @@
+func sieve(N: Int)->[Int]
+{
+    // The main Sieve array
+    var ary = new [Int]{len=N,value=0}
+    // The primes less than N
+    var primes = new [Int]{len=N/2,value=0}
+    // Number of primes so far, searching at index p
+    var nprimes = 0
+    var p=2
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) {
+            p = p + 1
+        }
+        // p is now a prime
+        primes[nprimes] = p
+        nprimes = nprimes+1
+        // Mark out the rest non-primes
+        var i = p + p
+        while( i < N ) {
+            ary[i] = 1
+            i = i + p
+        }
+        p = p + 1
+    }
+
+    // Now just collect the remaining primes, no more marking
+    while ( p < N ) {
+        if( !ary[p] ) {
+            primes[nprimes] = p
+            nprimes = nprimes + 1
+        }
+        p = p + 1
+    }
+
+    // Copy/shrink the result array
+    var rez = new [Int]{len=nprimes,value=0}
+    var j = 0
+    while( j < nprimes ) {
+        rez[j] = primes[j]
+        j = j + 1
+    }
+    return rez
+}
+func eq(a: [Int], b: [Int], n: Int)->Int
+{
+    var result = 1
+    var i = 0
+    while (i < n)
+    {
+        if (a[i] != b[i])
+        {
+            result = 0
+            break
+        }
+        i = i + 1
+    }
+    return result
+}
+
+func main()->Int
+{
+    var rez = sieve(20)
+    var expected = new [Int]{2,3,5,7,11,13,17,19}
+    return eq(rez,expected,8)
+}
\ No newline at end of file
diff --git a/seaofnodes/src/test/cases/sieve/sieve.smp b/seaofnodes/src/test/cases/sieve/sieve.smp
new file mode 100644
index 0000000..f0509a8
--- /dev/null
+++ b/seaofnodes/src/test/cases/sieve/sieve.smp
@@ -0,0 +1,31 @@
+// -*- mode: java;  -*-
+val sieve = { int N ->
+    // The main Sieve array
+    bool[] !ary = new bool[N];
+    // The primes less than N
+    u32[] !primes = new u32[N>>1];
+    // Number of primes so far, searching at index p
+    int nprimes = 0, p=2;
+    // Find primes while p^2 < N
+    while( p*p < N ) {
+        // skip marked non-primes
+        while( ary[p] ) p++;
+        // p is now a prime
+        primes[nprimes++] = p;
+        // Mark out the rest non-primes
+        for( int i = p + p; i < ary#; i+= p )
+            ary[i] = true;
+        p++;
+    }
+
+    // Now just collect the remaining primes, no more marking
+    for( ; p < N; p++ )
+        if( !ary[p] )
+            primes[nprimes++] = p;
+
+    // Copy/shrink the result array
+    u32[] !rez = new u32[nprimes];
+    for( int j=0; j < nprimes; j++ )
+        rez[j] = primes[j];
+    return rez;
+};
\ No newline at end of file
diff --git a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
index 0fa930d..743ac68 100644
--- a/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
+++ b/semantic/src/main/java/com/compilerprogramming/ezlang/semantic/SemaAssignTypes.java
@@ -67,6 +67,8 @@ public ASTVisitor visit(AST.VarDecl varDecl, boolean enter) {
     @Override
     public ASTVisitor visit(AST.BinaryExpr binaryExpr, boolean enter) {
         if (!enter) {
+            if (binaryExpr.type != null)
+                return this;
             validType(binaryExpr.expr1.type, true);
             validType(binaryExpr.expr2.type, true);
             if (binaryExpr.expr1.type instanceof Type.TypeInteger &&
@@ -92,7 +94,7 @@ else if (((binaryExpr.expr1.type instanceof Type.TypeNull &&
 
     @Override
     public ASTVisitor visit(AST.UnaryExpr unaryExpr, boolean enter) {
-        if (enter) {
+        if (enter || unaryExpr.type != null) {
             return this;
         }
         validType(unaryExpr.expr.type, false);
@@ -109,6 +111,8 @@ public ASTVisitor visit(AST.UnaryExpr unaryExpr, boolean enter) {
     public ASTVisitor visit(AST.GetFieldExpr fieldExpr, boolean enter) {
         if (enter)
             return this;
+        if (fieldExpr.type != null)
+            return this;
         validType(fieldExpr.object.type, false);
         Type.TypeStruct structType = null;
         if (fieldExpr.object.type instanceof Type.TypeStruct ts) {
@@ -131,6 +135,8 @@ else if (fieldExpr.object.type instanceof Type.TypeNullable ptr &&
     public ASTVisitor visit(AST.SetFieldExpr fieldExpr, boolean enter) {
         if (enter)
             return this;
+        if (fieldExpr.type != null)
+            return this;
         validType(fieldExpr.object.type, true);
         Type.TypeStruct structType = null;
         if (fieldExpr.object.type instanceof Type.TypeStruct ts) {
@@ -140,6 +146,16 @@ else if (fieldExpr.object.type instanceof Type.TypeNullable ptr &&
                 ptr.baseType instanceof Type.TypeStruct ts) {
             structType = ts;
         }
+        else if (fieldExpr.object.type instanceof Type.TypeArray typeArray) {
+            if (fieldExpr.fieldName.equals("len"))
+                checkAssignmentCompatible(typeDictionary.INT,fieldExpr.value.type);
+            else if (fieldExpr.fieldName.equals("value"))
+                checkAssignmentCompatible(typeArray.getElementType(),fieldExpr.value.type);
+            else
+                throw new CompilerException("Unexpected array initializer " + fieldExpr.fieldName);
+            fieldExpr.type = fieldExpr.value.type;
+            return this;
+        }
         else
             throw new CompilerException("Unexpected struct type " + fieldExpr.object.type);
         var fieldType = structType.getField(fieldExpr.fieldName);
@@ -155,6 +171,8 @@ else if (fieldExpr.object.type instanceof Type.TypeNullable ptr &&
     @Override
     public ASTVisitor visit(AST.CallExpr callExpr, boolean enter) {
         if (!enter) {
+            if (callExpr.type != null)
+                return this;
             validType(callExpr.callee.type, false);
             if (callExpr.callee.type instanceof Type.TypeFunction f) {
                 callExpr.type = f.returnType;
@@ -192,6 +210,8 @@ public ASTVisitor visit(AST.ReturnTypeExpr returnTypeExpr, boolean enter) {
     @Override
     public ASTVisitor visit(AST.LiteralExpr literalExpr, boolean enter) {
         if (enter) {
+            if (literalExpr.type != null)
+                return this;
             if (literalExpr.value.kind == Token.Kind.NUM) {
                 literalExpr.type = typeDictionary.INT;
             }
@@ -209,6 +229,8 @@ else if (literalExpr.value.kind == Token.Kind.IDENT
     @Override
     public ASTVisitor visit(AST.ArrayLoadExpr arrayIndexExpr, boolean enter) {
         if (!enter) {
+            if (arrayIndexExpr.type != null)
+                return this;
             validType(arrayIndexExpr.array.type, false);
             Type.TypeArray arrayType = null;
             if (arrayIndexExpr.array.type instanceof Type.TypeArray ta) {
@@ -231,6 +253,8 @@ else if (arrayIndexExpr.array.type instanceof Type.TypeNullable ptr &&
     @Override
     public ASTVisitor visit(AST.ArrayStoreExpr arrayIndexExpr, boolean enter) {
         if (!enter) {
+            if (arrayIndexExpr.type != null)
+                return this;
             validType(arrayIndexExpr.array.type, false);
             Type.TypeArray arrayType = null;
             if (arrayIndexExpr.array.type instanceof Type.TypeArray ta) {
@@ -256,6 +280,8 @@ else if (arrayIndexExpr.array.type instanceof Type.TypeNullable ptr &&
     public ASTVisitor visit(AST.NewExpr newExpr, boolean enter) {
         if (enter)
             return this;
+        if (newExpr.type != null)
+            return this;
         if (newExpr.typeExpr.type == null)
             throw new CompilerException("Unresolved type in new expression");
         validType(newExpr.typeExpr.type, false);
@@ -266,6 +292,14 @@ public ASTVisitor visit(AST.NewExpr newExpr, boolean enter) {
         }
         else if (newExpr.typeExpr.type instanceof Type.TypeArray arrayType) {
             newExpr.type = newExpr.typeExpr.type;
+            if (newExpr.len != null) {
+                if (!(newExpr.len.type instanceof Type.TypeInteger))
+                    throw new CompilerException("Array len must be integer type");
+                if (newExpr.initValue != null) {
+                    if (!arrayType.getElementType().isAssignable(newExpr.initValue.type))
+                        throw new CompilerException("Array init value must be assignable to array element type");
+                }
+            }
         }
         else
             throw new CompilerException("Unsupported type in new expression");
@@ -278,6 +312,8 @@ public ASTVisitor visit(AST.InitExpr initExpr, boolean enter) {
             return this;
         if (initExpr.newExpr.type == null)
             throw new CompilerException("Unresolved type in new expression");
+        if (initExpr.type != null)
+            return this;
         validType(initExpr.newExpr.type, false);
         if (initExpr.newExpr.type instanceof Type.TypeNullable)
             throw new CompilerException("new cannot be used to create a Nullable type");
@@ -290,6 +326,8 @@ public ASTVisitor visit(AST.InitExpr initExpr, boolean enter) {
             }
         }
         else if (initExpr.newExpr.type instanceof Type.TypeArray arrayType) {
+            if (initExpr.initExprList.size() > 0)
+                initExpr.initExprList.removeIf(e->e instanceof AST.InitFieldExpr);
             for (AST.Expr expr: initExpr.initExprList) {
                 checkAssignmentCompatible(arrayType.getElementType(), expr.type);
             }
@@ -304,6 +342,8 @@ else if (initExpr.newExpr.type instanceof Type.TypeArray arrayType) {
     public ASTVisitor visit(AST.NameExpr nameExpr, boolean enter) {
         if (!enter)
             return this;
+        if (nameExpr.type != null)
+            return this;
         var symbol = currentScope.lookup(nameExpr.name);
         if (symbol == null) {
             throw new CompilerException("Unknown symbol " + nameExpr.name);
diff --git a/types/src/main/java/com/compilerprogramming/ezlang/types/Type.java b/types/src/main/java/com/compilerprogramming/ezlang/types/Type.java
index 05cbca6..1c8514c 100644
--- a/types/src/main/java/com/compilerprogramming/ezlang/types/Type.java
+++ b/types/src/main/java/com/compilerprogramming/ezlang/types/Type.java
@@ -53,7 +53,7 @@ public String toString() {
     public String name() { return name; }
 
     public boolean isAssignable(Type other) {
-        if (other instanceof TypeVoid || other instanceof TypeUnknown)
+        if (other == null || other instanceof TypeVoid || other instanceof TypeUnknown)
             return false;
         if (this == other || equals(other)) return true;
         if (this instanceof TypeNullable nullable) {