diff --git a/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java b/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
index ac8056755..79a1ae37b 100644
--- a/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
+++ b/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
@@ -159,7 +159,7 @@ public class DependencyChecker {
         for (int i = 0; i < varCount; ++i) {
             parameterNodes[i] = new DependencyNode(this);
             if (shouldLog) {
-                parameterNodes[i].setTag(method.getOwner().getName() + "#" + method.getDescriptor() + ":" + i);
+                parameterNodes[i].setTag(method.getOwnerName() + "#" + method.getDescriptor() + ":" + i);
             }
         }
         DependencyNode resultNode;
@@ -168,7 +168,7 @@ public class DependencyChecker {
         } else {
             resultNode = new DependencyNode(this);
             if (shouldLog) {
-                resultNode.setTag(method.getOwner().getName() + "#" + method.getDescriptor() + ":RESULT");
+                resultNode.setTag(method.getOwnerName() + "#" + method.getDescriptor() + ":RESULT");
             }
         }
         final MethodGraph graph = new MethodGraph(parameterNodes, paramCount, resultNode, this);
diff --git a/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java b/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
index 0aab4352b..9bd265369 100644
--- a/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
+++ b/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
@@ -120,7 +120,7 @@ public class Decompiler {
     public NativeMethodNode decompileNative(MethodHolder method) {
         AnnotationHolder annotHolder = method.getAnnotations().get(GeneratedBy.class.getName());
         if (annotHolder == null) {
-            throw new DecompilationException("Method " + method.getOwner().getName() + "." + method.getDescriptor() +
+            throw new DecompilationException("Method " + method.getOwnerName() + "." + method.getDescriptor() +
                     " is native, but no " + GeneratedBy.class.getName() + " annotation found");
         }
         ValueType annotValue = annotHolder.getValues().get("value").getJavaClass();
@@ -131,9 +131,9 @@ public class Decompiler {
             generator = (Generator)generatorClass.newInstance();
         } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
             throw new DecompilationException("Error instantiating generator " + generatorClassName +
-                    " for native method " + method.getOwner().getName() + "." + method.getDescriptor());
+                    " for native method " + method.getOwnerName() + "." + method.getDescriptor());
         }
-        NativeMethodNode methodNode = new NativeMethodNode(new MethodReference(method.getOwner().getName(),
+        NativeMethodNode methodNode = new NativeMethodNode(new MethodReference(method.getOwnerName(),
                 method.getDescriptor()));
         methodNode.getModifiers().addAll(mapModifiers(method.getModifiers()));
         methodNode.setGenerator(generator);
@@ -193,7 +193,7 @@ public class Decompiler {
         }
         SequentialStatement result = new SequentialStatement();
         result.getSequence().addAll(rootStmt.getBody());
-        MethodReference reference = new MethodReference(method.getOwner().getName(), method.getDescriptor());
+        MethodReference reference = new MethodReference(method.getOwnerName(), method.getDescriptor());
         RegularMethodNode methodNode = new RegularMethodNode(reference);
         methodNode.getModifiers().addAll(mapModifiers(method.getModifiers()));
         methodNode.setBody(result);
diff --git a/teavm-core/src/main/java/org/teavm/model/BasicBlock.java b/teavm-core/src/main/java/org/teavm/model/BasicBlock.java
index d0ef60cba..a4114da1e 100644
--- a/teavm-core/src/main/java/org/teavm/model/BasicBlock.java
+++ b/teavm-core/src/main/java/org/teavm/model/BasicBlock.java
@@ -16,12 +16,13 @@
 package org.teavm.model;
 
 import java.util.*;
+import org.teavm.model.instructions.InstructionReader;
 
 /**
  *
  * @author Alexey Andreev
  */
-public class BasicBlock  {
+public class BasicBlock implements BasicBlockReader {
     private Program program;
     private int index;
     private List<Phi> phis = new ArrayList<>();
@@ -32,10 +33,12 @@ public class BasicBlock  {
         this.index = index;
     }
 
+    @Override
     public Program getProgram() {
         return program;
     }
 
+    @Override
     public int getIndex() {
         return index;
     }
@@ -153,4 +156,29 @@ public class BasicBlock  {
     public List<Phi> getPhis() {
         return safePhis;
     }
+
+    private List<Phi> immutablePhis = Collections.unmodifiableList(phis);
+
+    @Override
+    public List<? extends PhiReader> readPhis() {
+        return immutablePhis;
+    }
+
+    @Override
+    public int instructionCount() {
+        return instructions.size();
+    }
+
+    @Override
+    public void readInstruction(int index, InstructionReader reader) {
+        instructions.get(index).acceptVisitor(new InstructionReadVisitor(reader));
+    }
+
+    @Override
+    public void readAllInstructions(InstructionReader reader) {
+        InstructionReadVisitor visitor = new InstructionReadVisitor(reader);
+        for (Instruction insn : instructions) {
+            insn.acceptVisitor(visitor);
+        }
+    }
 }
diff --git a/teavm-core/src/main/java/org/teavm/model/BasicBlockReader.java b/teavm-core/src/main/java/org/teavm/model/BasicBlockReader.java
new file mode 100644
index 000000000..1cc01d8ce
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/BasicBlockReader.java
@@ -0,0 +1,37 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+import java.util.List;
+import org.teavm.model.instructions.InstructionReader;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface BasicBlockReader {
+    ProgramReader getProgram();
+
+    int getIndex();
+
+    List<? extends PhiReader> readPhis();
+
+    int instructionCount();
+
+    void readInstruction(int index, InstructionReader reader);
+
+    void readAllInstructions(InstructionReader reader);
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/ClassHolder.java b/teavm-core/src/main/java/org/teavm/model/ClassHolder.java
index 1924c3b85..22d1e19e2 100644
--- a/teavm-core/src/main/java/org/teavm/model/ClassHolder.java
+++ b/teavm-core/src/main/java/org/teavm/model/ClassHolder.java
@@ -21,7 +21,7 @@ import java.util.*;
  *
  * @author Alexey Andreev
  */
-public class ClassHolder extends ElementHolder {
+public class ClassHolder extends ElementHolder implements ClassReader {
     private String parent = Object.class.getName();
     private Set<String> interfaces = new HashSet<>();
     private Map<MethodDescriptor, MethodHolder> methods = new HashMap<>();
@@ -31,6 +31,7 @@ public class ClassHolder extends ElementHolder {
         super(name);
     }
 
+    @Override
     public String getParent() {
         return parent;
     }
@@ -39,14 +40,17 @@ public class ClassHolder extends ElementHolder {
         this.parent = parent;
     }
 
+    @Override
     public Set<String> getInterfaces() {
         return interfaces;
     }
 
+    @Override
     public MethodHolder getMethod(MethodDescriptor method) {
         return methods.get(method);
     }
 
+    @Override
     public Collection<MethodHolder> getMethods() {
         return methods.values();
     }
@@ -72,10 +76,12 @@ public class ClassHolder extends ElementHolder {
         method.setOwner(null);
     }
 
+    @Override
     public FieldHolder getField(String name) {
         return fields.get(name);
     }
 
+    @Override
     public Collection<FieldHolder> getFields() {
         return fields.values();
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/ClassReader.java b/teavm-core/src/main/java/org/teavm/model/ClassReader.java
new file mode 100644
index 000000000..6854e8a6b
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/ClassReader.java
@@ -0,0 +1,37 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+import java.util.Collection;
+import java.util.Set;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface ClassReader extends ElementReader {
+    String getParent();
+
+    Set<String> getInterfaces();
+
+    MethodReader getMethod(MethodDescriptor method);
+
+    Collection<? extends MethodReader> getMethods();
+
+    FieldReader getField(String name);
+
+    Collection<? extends FieldReader> getFields();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/ElementHolder.java b/teavm-core/src/main/java/org/teavm/model/ElementHolder.java
index 290a186b5..1d53dc47d 100644
--- a/teavm-core/src/main/java/org/teavm/model/ElementHolder.java
+++ b/teavm-core/src/main/java/org/teavm/model/ElementHolder.java
@@ -21,7 +21,7 @@ import java.util.EnumSet;
  *
  * @author Alexey Andreev
  */
-public abstract class ElementHolder {
+public abstract class ElementHolder implements ElementReader {
     private EnumSet<ElementModifier> modifiers = EnumSet.noneOf(ElementModifier.class);
     private AnnotationContainer annotations = new AnnotationContainer();
     private AccessLevel level = AccessLevel.PACKAGE_PRIVATE;
@@ -31,10 +31,21 @@ public abstract class ElementHolder {
         this.name = name;
     }
 
+    @Override
+    public EnumSet<ElementModifier> readModifiers() {
+        return modifiers.clone();
+    }
+
+    @Override
+    public boolean hasModifier(ElementModifier modifier) {
+        return modifiers.contains(modifier);
+    }
+
     public EnumSet<ElementModifier> getModifiers() {
         return modifiers;
     }
 
+    @Override
     public AccessLevel getLevel() {
         return level;
     }
@@ -43,6 +54,7 @@ public abstract class ElementHolder {
         this.level = level;
     }
 
+    @Override
     public String getName() {
         return name;
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/ElementReader.java b/teavm-core/src/main/java/org/teavm/model/ElementReader.java
new file mode 100644
index 000000000..c2239f95b
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/ElementReader.java
@@ -0,0 +1,32 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+import java.util.EnumSet;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface ElementReader {
+    AccessLevel getLevel();
+
+    EnumSet<ElementModifier> readModifiers();
+
+    boolean hasModifier(ElementModifier modifier);
+
+    String getName();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/FieldHolder.java b/teavm-core/src/main/java/org/teavm/model/FieldHolder.java
index d2c71fbfe..10aef8983 100644
--- a/teavm-core/src/main/java/org/teavm/model/FieldHolder.java
+++ b/teavm-core/src/main/java/org/teavm/model/FieldHolder.java
@@ -20,7 +20,7 @@ package org.teavm.model;
  *
  * @author Alexey Andreev
  */
-public class FieldHolder extends MemberHolder {
+public class FieldHolder extends MemberHolder implements FieldReader {
     private ValueType type;
     private Object initialValue;
     private ClassHolder owner;
@@ -29,6 +29,7 @@ public class FieldHolder extends MemberHolder {
         super(name);
     }
 
+    @Override
     public ValueType getType() {
         return type;
     }
@@ -37,6 +38,7 @@ public class FieldHolder extends MemberHolder {
         this.type = type;
     }
 
+    @Override
     public Object getInitialValue() {
         return initialValue;
     }
@@ -45,12 +47,16 @@ public class FieldHolder extends MemberHolder {
         this.initialValue = initialValue;
     }
 
-    @Override
-    public ClassHolder getOwner() {
+    ClassHolder getOwner() {
         return owner;
     }
 
     void setOwner(ClassHolder owner) {
         this.owner = owner;
     }
+
+    @Override
+    public String getOwnerName() {
+        return owner != null ? owner.getName() : null;
+    }
 }
diff --git a/teavm-core/src/main/java/org/teavm/model/FieldReader.java b/teavm-core/src/main/java/org/teavm/model/FieldReader.java
new file mode 100644
index 000000000..577df212a
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/FieldReader.java
@@ -0,0 +1,26 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface FieldReader extends MemberReader {
+    ValueType getType();
+
+    Object getInitialValue();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/Incoming.java b/teavm-core/src/main/java/org/teavm/model/Incoming.java
index d7df07bd4..df2952e32 100644
--- a/teavm-core/src/main/java/org/teavm/model/Incoming.java
+++ b/teavm-core/src/main/java/org/teavm/model/Incoming.java
@@ -19,11 +19,12 @@ package org.teavm.model;
  *
  * @author Alexey Andreev
  */
-public class Incoming {
+public class Incoming implements IncomingReader {
     private Phi phi;
     private Variable value;
     private BasicBlock source;
 
+    @Override
     public Variable getValue() {
         return value;
     }
@@ -32,6 +33,7 @@ public class Incoming {
         this.value = value;
     }
 
+    @Override
     public BasicBlock getSource() {
         return source;
     }
@@ -40,6 +42,7 @@ public class Incoming {
         this.source = source;
     }
 
+    @Override
     public Phi getPhi() {
         return phi;
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/IncomingReader.java b/teavm-core/src/main/java/org/teavm/model/IncomingReader.java
new file mode 100644
index 000000000..1098a532f
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/IncomingReader.java
@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface IncomingReader {
+    VariableReader getValue();
+
+    BasicBlockReader getSource();
+
+    PhiReader getPhi();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/InstructionReadVisitor.java b/teavm-core/src/main/java/org/teavm/model/InstructionReadVisitor.java
new file mode 100644
index 000000000..92dd04378
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/InstructionReadVisitor.java
@@ -0,0 +1,199 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+import java.util.Collections;
+import org.teavm.model.instructions.*;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+class InstructionReadVisitor implements InstructionVisitor {
+    private InstructionReader reader;
+
+    public InstructionReadVisitor(InstructionReader reader) {
+        this.reader = reader;
+    }
+
+    @Override
+    public void visit(EmptyInstruction insn) {
+        reader.nop();
+    }
+
+    @Override
+    public void visit(ClassConstantInstruction insn) {
+        reader.classConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(NullConstantInstruction insn) {
+        reader.nullConstant(insn.getReceiver());
+    }
+
+    @Override
+    public void visit(IntegerConstantInstruction insn) {
+        reader.integerConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(LongConstantInstruction insn) {
+        reader.longConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(FloatConstantInstruction insn) {
+        reader.floatConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(DoubleConstantInstruction insn) {
+        reader.doubleConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(StringConstantInstruction insn) {
+        reader.stringConstant(insn.getReceiver(), insn.getConstant());
+    }
+
+    @Override
+    public void visit(BinaryInstruction insn) {
+        reader.binary(insn.getOperation(), insn.getReceiver(), insn.getFirstOperand(), insn.getSecondOperand(),
+                insn.getOperandType());
+    }
+
+    @Override
+    public void visit(NegateInstruction insn) {
+        reader.negate(insn.getReceiver(), insn.getOperand(), insn.getOperandType());
+    }
+
+    @Override
+    public void visit(AssignInstruction insn) {
+        reader.assign(insn.getReceiver(), insn.getAssignee());
+    }
+
+    @Override
+    public void visit(CastInstruction insn) {
+        reader.cast(insn.getReceiver(), insn.getValue(), insn.getTargetType());
+    }
+
+    @Override
+    public void visit(CastNumberInstruction insn) {
+        reader.cast(insn.getReceiver(), insn.getValue(), insn.getSourceType(), insn.getTargetType());
+    }
+
+    @Override
+    public void visit(CastIntegerInstruction insn) {
+        reader.cast(insn.getReceiver(), insn.getReceiver(), insn.getTargetType(), insn.getDirection());
+    }
+
+    @Override
+    public void visit(BranchingInstruction insn) {
+        reader.jumpIf(insn.getCondition(), insn.getOperand(), insn.getConsequent(), insn.getAlternative());
+    }
+
+    @Override
+    public void visit(BinaryBranchingInstruction insn) {
+        reader.jumpIf(insn.getCondition(), insn.getFirstOperand(), insn.getSecondOperand(), insn.getConsequent(),
+                insn.getAlternative());
+    }
+
+    @Override
+    public void visit(JumpInstruction insn) {
+        reader.jump(insn.getTarget());
+    }
+
+    @Override
+    public void visit(SwitchInstruction insn) {
+        reader.choose(insn.getCondition(), Collections.unmodifiableList(insn.getEntries()), insn.getDefaultTarget());
+    }
+
+    @Override
+    public void visit(ExitInstruction insn) {
+        reader.exit(insn.getValueToReturn());
+    }
+
+    @Override
+    public void visit(RaiseInstruction insn) {
+        reader.raise(insn.getException());
+    }
+
+    @Override
+    public void visit(ConstructArrayInstruction insn) {
+        reader.createArray(insn.getReceiver(), insn.getItemType(), insn.getSize());
+    }
+
+    @Override
+    public void visit(ConstructInstruction insn) {
+        reader.create(insn.getReceiver(), insn.getType());
+    }
+
+    @Override
+    public void visit(ConstructMultiArrayInstruction insn) {
+        reader.createArray(insn.getReceiver(), insn.getItemType(), Collections.unmodifiableList(insn.getDimensions()));
+    }
+
+    @Override
+    public void visit(GetFieldInstruction insn) {
+        reader.getField(insn.getReceiver(), insn.getInstance(), insn.getField(), insn.getFieldType());
+    }
+
+    @Override
+    public void visit(PutFieldInstruction insn) {
+        reader.putField(insn.getInstance(), insn.getField(), insn.getValue());
+    }
+
+    @Override
+    public void visit(ArrayLengthInstruction insn) {
+        reader.arrayLength(insn.getReceiver(), insn.getArray());
+    }
+
+    @Override
+    public void visit(CloneArrayInstruction insn) {
+        reader.cloneArray(insn.getReceiver(), insn.getArray());
+    }
+
+    @Override
+    public void visit(UnwrapArrayInstruction insn) {
+        reader.unwrapArray(insn.getReceiver(), insn.getArray(), insn.getElementType());
+    }
+
+    @Override
+    public void visit(GetElementInstruction insn) {
+        reader.getElement(insn.getReceiver(), insn.getArray(), insn.getIndex());
+    }
+
+    @Override
+    public void visit(PutElementInstruction insn) {
+        reader.putElement(insn.getArray(), insn.getIndex(), insn.getValue());
+    }
+
+    @Override
+    public void visit(InvokeInstruction insn) {
+        reader.invoke(insn.getReceiver(), insn.getInstance(), insn.getMethod(),
+                Collections.unmodifiableList(insn.getArguments()), insn.getType());
+    }
+
+    @Override
+    public void visit(IsInstanceInstruction insn) {
+        reader.isInstance(insn.getReceiver(), insn.getValue(), insn.getType());
+    }
+
+    @Override
+    public void visit(InitClassInstruction insn) {
+        reader.initClass(insn.getClassName());
+    }
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/MemberHolder.java b/teavm-core/src/main/java/org/teavm/model/MemberHolder.java
index 484ac77f3..b4e9552d3 100644
--- a/teavm-core/src/main/java/org/teavm/model/MemberHolder.java
+++ b/teavm-core/src/main/java/org/teavm/model/MemberHolder.java
@@ -19,10 +19,11 @@ package org.teavm.model;
  *
  * @author Alexey Andreev
  */
-public abstract class MemberHolder extends ElementHolder {
+public abstract class MemberHolder extends ElementHolder implements MemberReader {
     public MemberHolder(String name) {
         super(name);
     }
 
-    public abstract ClassHolder getOwner();
+    @Override
+    public abstract String getOwnerName();
 }
diff --git a/teavm-core/src/main/java/org/teavm/model/MemberReader.java b/teavm-core/src/main/java/org/teavm/model/MemberReader.java
new file mode 100644
index 000000000..16b83daf5
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/MemberReader.java
@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface MemberReader extends ElementReader {
+    String getOwnerName();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/MethodHolder.java b/teavm-core/src/main/java/org/teavm/model/MethodHolder.java
index 433a9694f..345a1314a 100644
--- a/teavm-core/src/main/java/org/teavm/model/MethodHolder.java
+++ b/teavm-core/src/main/java/org/teavm/model/MethodHolder.java
@@ -19,10 +19,10 @@ package org.teavm.model;
  *
  * @author Alexey Andreev
  */
-public class MethodHolder extends MemberHolder {
+public class MethodHolder extends MemberHolder implements MethodReader {
     private MethodDescriptor descriptor;
     private ClassHolder owner;
-    private Program program;
+    private volatile Program program;
 
     public MethodHolder(MethodDescriptor descriptor) {
         super(descriptor.getName());
@@ -33,28 +33,37 @@ public class MethodHolder extends MemberHolder {
         this(new MethodDescriptor(name, signature));
     }
 
+    @Override
     public ValueType getResultType() {
         return descriptor.getResultType();
     }
 
+    @Override
     public int parameterCount() {
         return descriptor.parameterCount();
     }
 
+    @Override
     public ValueType[] getSignature() {
         return descriptor.getSignature();
     }
 
+    @Override
     public ValueType parameterType(int index) {
         return descriptor.parameterType(index);
     }
 
+    @Override
     public ValueType[] getParameterTypes() {
         return descriptor.getParameterTypes();
     }
 
     @Override
-    public ClassHolder getOwner() {
+    public String getOwnerName() {
+        return owner != null ? owner.getName() : null;
+    }
+
+    ClassHolder getOwner() {
         return owner;
     }
 
@@ -62,10 +71,17 @@ public class MethodHolder extends MemberHolder {
         this.owner = owner;
     }
 
+    @Override
     public MethodDescriptor getDescriptor() {
         return descriptor;
     }
 
+    @Override
+    public MethodReference getReference() {
+        return owner != null ? new MethodReference(owner.getName(), descriptor) : null;
+    }
+
+    @Override
     public Program getProgram() {
         return program;
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/MethodReader.java b/teavm-core/src/main/java/org/teavm/model/MethodReader.java
new file mode 100644
index 000000000..152767e27
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/MethodReader.java
@@ -0,0 +1,38 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface MethodReader extends MemberReader {
+    ValueType getResultType();
+
+    int parameterCount();
+
+    ValueType[] getSignature();
+
+    ValueType parameterType(int index);
+
+    ValueType[] getParameterTypes();
+
+    MethodDescriptor getDescriptor();
+
+    MethodReference getReference();
+
+    ProgramReader getProgram();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/Phi.java b/teavm-core/src/main/java/org/teavm/model/Phi.java
index 744d106fd..00f715882 100644
--- a/teavm-core/src/main/java/org/teavm/model/Phi.java
+++ b/teavm-core/src/main/java/org/teavm/model/Phi.java
@@ -17,17 +17,19 @@ package org.teavm.model;
 
 import java.util.AbstractList;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 /**
  *
  * @author Alexey Andreev
  */
-public class Phi {
+public class Phi implements PhiReader {
     private BasicBlock basicBlock;
     private Variable receiver;
     private List<Incoming> incomings = new ArrayList<>();
 
+    @Override
     public BasicBlock getBasicBlock() {
         return basicBlock;
     }
@@ -36,6 +38,7 @@ public class Phi {
         this.basicBlock = basicBlock;
     }
 
+    @Override
     public Variable getReceiver() {
         return receiver;
     }
@@ -95,4 +98,11 @@ public class Phi {
     public List<Incoming> getIncomings() {
         return safeIncomings;
     }
+
+    private List<? extends IncomingReader> immutableIncomings = Collections.unmodifiableList(incomings);
+
+    @Override
+    public List<? extends IncomingReader> readIncomings() {
+        return immutableIncomings;
+    }
 }
diff --git a/teavm-core/src/main/java/org/teavm/model/PhiReader.java b/teavm-core/src/main/java/org/teavm/model/PhiReader.java
new file mode 100644
index 000000000..7577a6786
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/PhiReader.java
@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+import java.util.List;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface PhiReader {
+    BasicBlockReader getBasicBlock();
+
+    VariableReader getReceiver();
+
+    List<? extends IncomingReader> readIncomings();
+}
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 57d66b4cb..9c3cab944 100644
--- a/teavm-core/src/main/java/org/teavm/model/Program.java
+++ b/teavm-core/src/main/java/org/teavm/model/Program.java
@@ -22,7 +22,7 @@ import java.util.List;
  *
  * @author Alexey Andreev
  */
-public class Program {
+public class Program implements ProgramReader {
     private List<BasicBlock> basicBlocks = new ArrayList<>();
     private List<Variable> variables = new ArrayList<>();
     private MethodHolder method;
@@ -54,10 +54,12 @@ public class Program {
         packed = false;
     }
 
+    @Override
     public int basicBlockCount() {
         return basicBlocks.size();
     }
 
+    @Override
     public BasicBlock basicBlockAt(int index) {
         return basicBlocks.get(index);
     }
@@ -106,15 +108,22 @@ public class Program {
         packed = true;
     }
 
+    @Override
     public int variableCount() {
         return variables.size();
     }
 
+    @Override
     public Variable variableAt(int index) {
         return variables.get(index);
     }
 
-    public MethodHolder getMethod() {
+    @Override
+    public MethodReference getMethodReference() {
+        return method != null ? method.getReference() : null;
+    }
+
+    MethodHolder getMethod() {
         return method;
     }
 
diff --git a/teavm-core/src/main/java/org/teavm/model/ProgramReader.java b/teavm-core/src/main/java/org/teavm/model/ProgramReader.java
new file mode 100644
index 000000000..4193ecbda
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/ProgramReader.java
@@ -0,0 +1,32 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface ProgramReader {
+    int basicBlockCount();
+
+    BasicBlockReader basicBlockAt(int index);
+
+    int variableCount();
+
+    VariableReader variableAt(int index);
+
+    MethodReference getMethodReference();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/Variable.java b/teavm-core/src/main/java/org/teavm/model/Variable.java
index b0fb3b27a..ceb63fc01 100644
--- a/teavm-core/src/main/java/org/teavm/model/Variable.java
+++ b/teavm-core/src/main/java/org/teavm/model/Variable.java
@@ -19,7 +19,7 @@ package org.teavm.model;
  *
  * @author Alexey Andreev
  */
-public class Variable {
+public class Variable implements VariableReader {
     private Program program;
     private int index;
     private int register;
@@ -28,6 +28,7 @@ public class Variable {
         this.program = program;
     }
 
+    @Override
     public int getIndex() {
         return index;
     }
@@ -36,6 +37,7 @@ public class Variable {
         this.index = index;
     }
 
+    @Override
     public Program getProgram() {
         return program;
     }
@@ -44,6 +46,7 @@ public class Variable {
         this.program = program;
     }
 
+    @Override
     public int getRegister() {
         return register;
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/VariableReader.java b/teavm-core/src/main/java/org/teavm/model/VariableReader.java
new file mode 100644
index 000000000..d93ed618e
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/VariableReader.java
@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface VariableReader {
+    int getIndex();
+
+    ProgramReader getProgram();
+
+    int getRegister();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/instructions/InstructionReader.java b/teavm-core/src/main/java/org/teavm/model/instructions/InstructionReader.java
new file mode 100644
index 000000000..5df676fed
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/instructions/InstructionReader.java
@@ -0,0 +1,99 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model.instructions;
+
+import java.util.List;
+import org.teavm.model.*;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface InstructionReader {
+    void nop();
+
+    void classConstant(VariableReader receiver, ValueType cst);
+
+    void nullConstant(VariableReader receiver);
+
+    void integerConstant(VariableReader receiver, int cst);
+
+    void longConstant(VariableReader receiver, long cst);
+
+    void floatConstant(VariableReader receiver, float cst);
+
+    void doubleConstant(VariableReader receiver, double cst);
+
+    void stringConstant(VariableReader receiver, String cst);
+
+    void binary(BinaryOperation op, VariableReader receiver, VariableReader first, VariableReader second,
+            NumericOperandType type);
+
+    void negate(VariableReader receiver, VariableReader operand, NumericOperandType type);
+
+    void assign(VariableReader receiver, VariableReader assignee);
+
+    void cast(VariableReader receiver, VariableReader value, ValueType targetType);
+
+    void cast(VariableReader receiver, VariableReader value, NumericOperandType sourceType,
+            NumericOperandType targetType);
+
+    void cast(VariableReader receiver, VariableReader value, IntegerSubtype type,
+            CastIntegerDirection targetType);
+
+    void jumpIf(BranchingCondition cond, VariableReader operand, BasicBlockReader consequent,
+            BasicBlockReader alternative);
+
+    void jumpIf(BinaryBranchingCondition cond, VariableReader first, VariableReader second,
+            BasicBlockReader consequent, BasicBlockReader alternative);
+
+    void jump(BasicBlockReader target);
+
+    void choose(VariableReader condition, List<? extends SwitchTableEntryReader> table,
+            BasicBlockReader defaultTarget);
+
+    void exit(VariableReader valueToReturn);
+
+    void raise(VariableReader exception);
+
+    void createArray(VariableReader receiver, ValueType itemType, VariableReader size);
+
+    void createArray(VariableReader receiver, ValueType itemType, List<? extends VariableReader> dimensions);
+
+    void create(VariableReader receiver, String type);
+
+    void getField(VariableReader receiver, VariableReader instance, FieldReference field, ValueType fieldType);
+
+    void putField(VariableReader instance, FieldReference field, VariableReader value);
+
+    void arrayLength(VariableReader receiver, VariableReader array);
+
+    void cloneArray(VariableReader receiver, VariableReader array);
+
+    void unwrapArray(VariableReader receiver, VariableReader array, ArrayElementType elementType);
+
+    void getElement(VariableReader receiver, VariableReader array, VariableReader index);
+
+    void putElement(VariableReader array, VariableReader index, VariableReader value);
+
+    void invoke(VariableReader receiver, VariableReader instance, MethodReference method,
+            List<? extends VariableReader> arguments,
+            InvocationType type);
+
+    void isInstance(VariableReader receiver, VariableReader value, ValueType type);
+
+    void initClass(String className);
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntry.java b/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntry.java
index 034ee1a42..c06d379d7 100644
--- a/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntry.java
+++ b/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntry.java
@@ -21,7 +21,7 @@ import org.teavm.model.BasicBlock;
  *
  * @author Alexey Andreev
  */
-public class SwitchTableEntry {
+public class SwitchTableEntry implements SwitchTableEntryReader {
     private int condition;
     private BasicBlock target;
     private SwitchInstruction instruction;
@@ -34,6 +34,7 @@ public class SwitchTableEntry {
         this.instruction = instruction;
     }
 
+    @Override
     public int getCondition() {
         return condition;
     }
@@ -42,6 +43,7 @@ public class SwitchTableEntry {
         this.condition = condition;
     }
 
+    @Override
     public BasicBlock getTarget() {
         return target;
     }
diff --git a/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntryReader.java b/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntryReader.java
new file mode 100644
index 000000000..4986e85c1
--- /dev/null
+++ b/teavm-core/src/main/java/org/teavm/model/instructions/SwitchTableEntryReader.java
@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model.instructions;
+
+import org.teavm.model.BasicBlockReader;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public interface SwitchTableEntryReader {
+    int getCondition();
+
+    BasicBlockReader getTarget();
+}
diff --git a/teavm-core/src/main/java/org/teavm/model/resource/ClassRefsRenamer.java b/teavm-core/src/main/java/org/teavm/model/resource/ClassRefsRenamer.java
index 5f1ffe643..91edf4fcf 100644
--- a/teavm-core/src/main/java/org/teavm/model/resource/ClassRefsRenamer.java
+++ b/teavm-core/src/main/java/org/teavm/model/resource/ClassRefsRenamer.java
@@ -54,7 +54,7 @@ class ClassRefsRenamer implements InstructionVisitor {
             renamedCls.addMethod(rename(method));
         }
         for (FieldHolder field : cls.getFields().toArray(new FieldHolder[0])) {
-            field.getOwner().removeField(field);
+            cls.removeField(field);
             renamedCls.addField(field);
         }
         rename(cls.getAnnotations(), renamedCls.getAnnotations());