diff --git a/teavm-core/src/main/java/org/teavm/model/Program.java b/teavm-core/src/main/java/org/teavm/model/Program.java
index 524d163f0..e8334ddf1 100644
--- a/teavm-core/src/main/java/org/teavm/model/Program.java
+++ b/teavm-core/src/main/java/org/teavm/model/Program.java
@@ -74,6 +74,10 @@ public class Program {
         while (basicBlocks.size() > sz) {
             basicBlocks.remove(basicBlocks.size() - 1);
         }
+        sz = 0;
+        for (int i = 0; i < basicBlocks.size(); ++i) {
+
+        }
     }
 
     public int variableCount() {
diff --git a/teavm-core/src/main/java/org/teavm/optimization/CommonSubexpressionElimination.java b/teavm-core/src/main/java/org/teavm/optimization/CommonSubexpressionElimination.java
new file mode 100644
index 000000000..9e2a58623
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/optimization/CommonSubexpressionElimination.java
@@ -0,0 +1,257 @@
+package org.teavm.optimization;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.teavm.common.Graph;
+import org.teavm.common.GraphUtils;
+import org.teavm.model.BasicBlock;
+import org.teavm.model.Instruction;
+import org.teavm.model.MethodHolder;
+import org.teavm.model.Program;
+import org.teavm.model.instructions.*;
+import org.teavm.model.util.ProgramUtils;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class CommonSubexpressionElimination implements MethodOptimization {
+    private Map<String, Integer> knownValues = new HashMap<>();
+    private Instruction currentInsn;
+    private int[] map;
+    private Program program;
+
+    @Override
+    public void optimize(MethodHolder method) {
+        program = method.getProgram();
+        Graph cfg = ProgramUtils.buildControlFlowGraph(method.getProgram());
+        Graph dom = GraphUtils.buildDominatorGraph(GraphUtils.buildDominatorTree(cfg), cfg.size());
+        map = new int[program.variableCount()];
+        for (int i = 0; i < map.length; ++i) {
+            map[i] = i;
+        }
+
+        int[] stack = new int[cfg.size() * 2];
+        int top = 0;
+        for (int i = 0; i < cfg.size(); ++i) {
+            if (cfg.incomingEdgesCount(i) == 0) {
+                stack[top++] = i;
+            }
+        }
+        while (top > 0) {
+            int v = stack[--top];
+            BasicBlock block = program.basicBlockAt(v);
+            for (int i = 0; i < block.getInstructions().size(); ++i) {
+                currentInsn = block.getInstructions().get(i);
+                currentInsn.acceptVisitor(optimizer);
+                if (currentInsn != null) {
+                    block.getInstructions().set(i, currentInsn);
+                } else {
+                    block.getInstructions().remove(i--);
+                }
+            }
+            for (int succ : dom.outgoingEdges(v)) {
+                stack[top++] = succ;
+            }
+        }
+        program.pack();
+    }
+
+    private void bind(int var, String value) {
+        Integer known = knownValues.get(value);
+        if (known != null) {
+            currentInsn = null;
+            map[var] = known;
+        } else {
+            knownValues.put(value, var);
+        }
+    }
+
+    private InstructionVisitor optimizer = new InstructionVisitor() {
+        @Override
+        public void visit(EmptyInstruction insn) {
+        }
+
+        @Override
+        public void visit(ClassConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(NullConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(IntegerConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(LongConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(FloatConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(DoubleConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(StringConstantInstruction insn) {
+        }
+
+        @Override
+        public void visit(BinaryInstruction insn) {
+            int a = map[insn.getFirstOperand().getIndex()];
+            int b = map[insn.getSecondOperand().getIndex()];
+            insn.setFirstOperand(program.variableAt(a));
+            insn.setSecondOperand(program.variableAt(b));
+            String value;
+            switch (insn.getOperation()) {
+                case ADD:
+                    value = "+";
+                    break;
+                case SUBTRACT:
+                    value = "-";
+                    break;
+                case MULTIPLY:
+                    value = "*";
+                    break;
+                case DIVIDE:
+                    value = "/";
+                    break;
+                case MODULO:
+                    value = "%";
+                    break;
+                case COMPARE:
+                    value = "$";
+                    break;
+                case AND:
+                    value = "&";
+                    break;
+                case OR:
+                    value = "|";
+                    break;
+                case XOR:
+                    value = "^";
+                    break;
+                case SHIFT_LEFT:
+                    value = "<<";
+                    break;
+                case SHIFT_RIGHT:
+                    value = ">>";
+                    break;
+                case SHIFT_RIGHT_UNSIGNED:
+                    value = ">>>";
+                    break;
+                default:
+                    return;
+            }
+            value = "@" + a + value + "@" + b;
+            bind(insn.getReceiver().getIndex(), value);
+        }
+
+        @Override
+        public void visit(NegateInstruction insn) {
+            int a = map[insn.getOperand().getIndex()];
+            insn.setOperand(program.variableAt(a));
+            bind(insn.getReceiver().getIndex(), "-@" + a);
+        }
+
+        @Override
+        public void visit(AssignInstruction insn) {
+            map[insn.getReceiver().getIndex()] = insn.getAssignee().getIndex();
+            currentInsn = null;
+        }
+
+        @Override
+        public void visit(CastInstruction insn) {
+            bind(insn.getReceiver().getIndex(), "@" + insn.getValue().getIndex() + " cast " +
+                    insn.getTargetType());
+        }
+
+        @Override
+        public void visit(CastNumberInstruction insn) {
+            bind(insn.getReceiver().getIndex(), "@" + insn.getValue().getIndex() + " cast " +
+                    insn.getTargetType());
+        }
+
+        @Override
+        public void visit(CastIntegerInstruction insn) {
+            bind(insn.getReceiver().getIndex(), "@" + insn.getValue().getIndex() + " cast " +
+                    insn.getTargetType() + " " + insn.getDirection());
+        }
+
+        @Override
+        public void visit(BranchingInstruction insn) {
+        }
+
+        @Override
+        public void visit(BinaryBranchingInstruction insn) {
+        }
+
+        @Override
+        public void visit(JumpInstruction insn) {
+        }
+
+        @Override
+        public void visit(SwitchInstruction insn) {
+        }
+
+        @Override
+        public void visit(ExitInstruction insn) {
+        }
+
+        @Override
+        public void visit(RaiseInstruction insn) {
+        }
+
+        @Override
+        public void visit(ConstructArrayInstruction insn) {
+        }
+
+        @Override
+        public void visit(ConstructInstruction insn) {
+        }
+
+        @Override
+        public void visit(ConstructMultiArrayInstruction insn) {
+        }
+
+        @Override
+        public void visit(GetFieldInstruction insn) {
+        }
+
+        @Override
+        public void visit(PutFieldInstruction insn) {
+        }
+
+        @Override
+        public void visit(ArrayLengthInstruction insn) {
+        }
+
+        @Override
+        public void visit(CloneArrayInstruction insn) {
+        }
+
+        @Override
+        public void visit(UnwrapArrayInstruction insn) {
+        }
+
+        @Override
+        public void visit(GetElementInstruction insn) {
+        }
+
+        @Override
+        public void visit(PutElementInstruction insn) {
+        }
+
+        @Override
+        public void visit(InvokeInstruction insn) {
+        }
+
+        @Override
+        public void visit(IsInstanceInstruction insn) {
+        }
+    };
+}