Implement ClassPath class, refactor analysis code to use new ClassPath functionality, start adding verification for individual opcodes

git-svn-id: https://smali.googlecode.com/svn/trunk@574 55b6fa8a-2a1e-11de-a435-ffa8d773f76a

baksmali/src/main/java/org/jf/baksmali/Analysis/Analysis.java

@@ -1,4 +0,0 @@
-package org.jf.baksmali.Analysis;
-
-public class Analysis {
-}

baksmali/src/main/java/org/jf/baksmali/Analysis/AnalysisInstruction.java

@@ -1,5 +0,0 @@
-package org.jf.baksmali.Analysis;
-
-public interface AnalysisInstruction {
-    
-}

dexlib/src/main/java/org/jf/dexlib/Code/Analysis/AnalyzedInstruction.java

@@ -1,6 +1,7 @@
 package org.jf.dexlib.Code.Analysis;
 
-import org.jf.dexlib.Code.Instruction;
+import org.jf.dexlib.Code.*;
+import org.jf.dexlib.Util.ExceptionWithContext;
 
 import java.util.LinkedList;
 
@@ -11,19 +12,24 @@ public class AnalyzedInstruction {
     protected final Instruction instruction;
 
     /**
-     * The address of the instruction, in 2-byte code blocks
+     * The index of the instruction, where the first instruction in the method is at index 0, and so on
      */
-    protected final int codeAddress;
+    protected final int instructionIndex;
 
     /**
      * Instructions that can pass on execution to this one during normal execution
      */
-    protected LinkedList<AnalyzedInstruction> predecessors = new LinkedList<AnalyzedInstruction>();
+    protected final LinkedList<AnalyzedInstruction> predecessors = new LinkedList<AnalyzedInstruction>();
 
     /**
      * Instructions that can execution could pass on to next during normal execution
      */
-    protected LinkedList<AnalyzedInstruction> successors = new LinkedList<AnalyzedInstruction>();
+    protected final LinkedList<AnalyzedInstruction> successors = new LinkedList<AnalyzedInstruction>();
+
+    /**
+     * This contains the register types *after* the instruction has executed
+     */
+    protected final RegisterType[] postRegisterMap;
 
     /**
      * This is set to true when this instruction follows an odexed instruction that couldn't be deodexed. In this case
@@ -36,13 +42,14 @@ public class AnalyzedInstruction {
      */
     protected boolean dead = false;
 
-    public AnalyzedInstruction(Instruction instruction, int codeAddress) {
+    public AnalyzedInstruction(Instruction instruction, int instructionIndex, int registerCount) {
         this.instruction = instruction;
-        this.codeAddress = codeAddress;
+        this.instructionIndex = instructionIndex;
+        this.postRegisterMap = new RegisterType[registerCount];
     }
 
-    public int getCodeAddress() {
-        return codeAddress;
+    public int getInstructionIndex() {
+        return instructionIndex;
     }
 
     protected void addPredecessor(AnalyzedInstruction predecessor) {
@@ -61,5 +68,78 @@ public class AnalyzedInstruction {
         successors.add(successor);
         return true;
     }
+
+    /*
+     * Sets the "post-instruction" register type as indicated. This should only be used to set
+     * the method parameter types for the "start of method" instruction, or to set the register
+     * type of the destination register during verification. The change to the register type
+     * will
+     * @param registerNumber Which register to set
+     * @param registerType The "post-instruction" register type
+     */
+    protected boolean setPostRegisterType(int registerNumber, RegisterType registerType) {
+        assert registerNumber >= 0 && registerNumber < postRegisterMap.length;
+        assert registerType != null;
+
+        RegisterType oldRegisterType = postRegisterMap[registerNumber];
+        if (oldRegisterType == registerType) {
+            return false;
+        }
+
+        postRegisterMap[registerNumber] = registerType;
+        return true;
+    }
+
+    protected RegisterType getMergedRegisterTypeFromPredecessors(int registerNumber) {
+        RegisterType mergedRegisterType = null;
+        for (AnalyzedInstruction predecessor: predecessors) {
+            RegisterType predecessorRegisterType = predecessor.postRegisterMap[registerNumber];
+            assert predecessorRegisterType != null;
+            mergedRegisterType = predecessorRegisterType.merge(mergedRegisterType);
+        }
+        return mergedRegisterType;
+    }
+
+    public boolean setsRegister() {
+        return instruction.opcode.setsRegister();
+    }
+
+    public boolean setsWideRegister() {
+        return instruction.opcode.setsWideRegister();
+    }
+
+    public boolean setsRegister(int registerNumber) {
+        if (!setsRegister()) {
+            return false;
+        }
+        int destinationRegister = getDestinationRegister();
+        if (registerNumber == destinationRegister) {
+            return true;
+        }
+        if (setsWideRegister() && registerNumber == (destinationRegister + 1)) {
+            return true;
+        }
+        return false;
+    }
+
+    public int getDestinationRegister() {
+        if (!this.instruction.opcode.setsRegister()) {
+            throw new ExceptionWithContext("Cannot call getDestinationRegister() for an instruction that doesn't " +
+                    "store a value");
+        }
+        return ((SingleRegisterInstruction)instruction).getRegisterA();
+    }
+
+    public RegisterType getPreInstructionRegisterType(int registerNumber) {
+        //if the specific register is not a destination register, then the stored post-instruction register type will
+        //be the same as the pre-instruction regsiter type, so we can use that.
+        //otherwise, we need to merge the predecessor's post-instruction register types
+
+        if (this.setsRegister(registerNumber)) {
+            return getMergedRegisterTypeFromPredecessors(registerNumber);
+        } else {
+            return postRegisterMap[registerNumber];
+        }
+    }
 }
 

dexlib/src/main/java/org/jf/dexlib/Code/Analysis/ClassPath.java

@@ -0,0 +1,704 @@
+package org.jf.dexlib.Code.Analysis;
+
+import org.jf.dexlib.*;
+import static org.jf.dexlib.ClassDataItem.EncodedMethod;
+import static org.jf.dexlib.ClassDataItem.EncodedField;
+
+import org.jf.dexlib.Util.AccessFlags;
+import org.jf.dexlib.Util.ExceptionWithContext;
+import org.jf.dexlib.Util.SparseArray;
+
+import java.io.File;
+import java.util.*;
+
+public class ClassPath {
+    private static ClassPath theClassPath = null;
+
+    private final HashMap<String, ClassDef> classDefs;
+    protected final ClassDef javaLangObjectClassDef; //Ljava/lang/Object;
+
+    public static void InitializeClassPath(String[] bootClassPath, DexFile dexFile) {
+        if (theClassPath != null) {
+            throw new ExceptionWithContext("Cannot initialize ClassPath multiple times");
+        }
+
+        theClassPath = new ClassPath(bootClassPath, dexFile);
+    }
+
+    private ClassPath(String[] bootClassPath, DexFile dexFile) {
+        if (bootClassPath == null || bootClassPath.length == 0) {
+            throw new ExceptionWithContext("No BOOTCLASSPATH entries were given");
+        }
+
+        classDefs = new HashMap<String, ClassDef>();
+
+        for (String bootClassPathEntry: bootClassPath) {
+            loadBootClassPath(bootClassPathEntry);
+        }
+
+        loadDexFile(dexFile);
+
+        try {
+            javaLangObjectClassDef = getClassDef("Ljava/lang/Object;");
+        } catch (ClassNotFoundException ex) {
+            throw ExceptionWithContext.withContext(ex, "Ljava/lang/Object; must be present in the classpath");
+        }
+
+        for (String primitiveType: new String[]{"Z", "B", "S", "C", "I", "J", "F", "D"}) {
+            ClassDef classDef = new PrimitiveClassDef(primitiveType);
+            classDefs.put(primitiveType, classDef);
+        }
+    }
+
+    private void loadBootClassPath(String bootClassPathEntry) {
+        File file = new File(bootClassPathEntry);
+
+        if (!file.exists()) {
+            throw new ExceptionWithContext("ClassPath entry \"" + bootClassPathEntry + "\" does not exist.");
+        }
+
+        if (!file.canRead()) {
+            throw new ExceptionWithContext("Cannot read ClassPath entry \"" + bootClassPathEntry + "\".");
+        }
+
+        DexFile dexFile;
+        try {
+            dexFile = new DexFile(file);
+        } catch (Exception ex) {
+            throw ExceptionWithContext.withContext(ex, "Error while reading ClassPath entry \"" +
+                    bootClassPathEntry + "\".");
+        }
+
+        loadDexFile(dexFile);
+    }
+
+    private void loadDexFile(DexFile dexFile) {
+        for (ClassDefItem classDefItem: dexFile.ClassDefsSection.getItems()) {
+            //TODO: need to check if the class already exists. (and if so, what to do about it?)
+            ClassDef classDef = new ClassDef(classDefItem);
+            classDefs.put(classDef.getClassType(), classDef);
+            classDef.dumpVtable();
+            classDef.dumpFields();
+        }
+    }
+
+    private static class ClassNotFoundException extends ExceptionWithContext {
+        public ClassNotFoundException(String message) {
+            super(message);
+        }
+    }
+
+    public static ClassDef getClassDef(String classType)  {
+        ClassDef classDef = theClassPath.classDefs.get(classType);
+        if (classDef == null) {
+            //if it's an array class, try to create it
+            if (classType.charAt(0) == '[') {
+                return theClassPath.createArrayClassDef(classType);
+            } else {
+                throw new ClassNotFoundException("Class " + classType + " cannot be found");
+            }
+        }
+        return classDef;
+    }
+
+    public static ClassDef getClassDef(TypeIdItem classType) {
+        return getClassDef(classType.getTypeDescriptor());
+    }
+
+    //256 [ characters
+    private static final String arrayPrefix = "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[" +
+        "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[" +
+        "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[";
+    private static ClassDef getArrayClassDefByElementClassAndDimension(ClassDef classDef, int arrayDimension) {
+        return getClassDef(arrayPrefix.substring(256 - arrayDimension) + classDef.classType);
+    }
+
+    private static ClassDef createArrayClassDef(String arrayClassName) {
+        assert arrayClassName != null;
+        assert arrayClassName.charAt(0) == '[';
+
+        ArrayClassDef arrayClassDef = new ArrayClassDef(arrayClassName);
+        if (arrayClassDef.elementClass == null) {
+            return null;
+        }
+
+        theClassPath.classDefs.put(arrayClassName, arrayClassDef);
+        return arrayClassDef;
+    }
+
+    public static ClassDef getCommonSuperclass(ClassDef class1, ClassDef class2) {
+        if (class1 == class2) {
+            return class1;
+        }
+
+        if (class1 == null) {
+            return class2;
+        }
+
+        if (class2 == null) {
+            return class1;
+        }
+
+        //TODO: do we want to handle primitive types here? I don't think so.. (if not, add assert)
+
+        if (!class1.isInterface && class2.isInterface) {
+            if (class1.implementsInterface(class2)) {
+                return class2;
+            }
+            return theClassPath.javaLangObjectClassDef;
+        }
+
+        if (!class2.isInterface && class1.isInterface) {
+            if (class2.implementsInterface(class1)) {
+                return class1;
+            }
+            return theClassPath.javaLangObjectClassDef;
+        }
+
+        if (class1 instanceof ArrayClassDef && class2 instanceof ArrayClassDef) {
+            return getCommonArraySuperclass((ArrayClassDef)class1, (ArrayClassDef)class2);
+        }
+
+        //we've got two non-array reference types. Find the class depth of each, and then move up the longer one
+        //so that both classes are at the same class depth, and then move each class up until they match
+
+        //we don't strictly need to keep track of the class depth separately, but it's probably slightly faster
+        //to do so, rather than calling getClassDepth() many times
+        int class1Depth = class1.getClassDepth();
+        int class2Depth = class2.getClassDepth();
+
+        while (class1Depth > class2Depth) {
+            class1 = class1.superclass;
+            class1Depth--;
+        }
+
+        while (class2Depth > class1Depth) {
+            class2 = class2.superclass;
+            class2Depth--;
+        }
+
+        while (class1Depth > 0) {
+            if (class1 == class2) {
+                return class1;
+            }
+            class1 = class1.superclass;
+            class1Depth--;
+            class2 = class2.superclass;
+            class2Depth--;
+        }
+
+        return class1;
+    }
+
+    private static ClassDef getCommonArraySuperclass(ArrayClassDef class1, ArrayClassDef class2) {
+        assert class1 != class2;
+
+        //If one of the arrays is a primitive array, then the only option is to return java.lang.Object
+        //TODO: might it be possible to merge something like int[] and short[] into int[]? (I don't think so..)
+        if (class1.elementClass instanceof PrimitiveClassDef || class2.elementClass instanceof PrimitiveClassDef) {
+            return theClassPath.javaLangObjectClassDef;
+        }
+
+        //if the two arrays have the same number of dimensions, then we should return an array class with the
+        //same number of dimensions, for the common superclass of the 2 element classes
+        if (class1.arrayDimensions == class2.arrayDimensions) {
+            ClassDef commonElementClass = getCommonSuperclass(class1.elementClass, class2.elementClass);
+            return getArrayClassDefByElementClassAndDimension(commonElementClass, class1.arrayDimensions);
+        }
+
+        //something like String[][][] and String[][] should be merged to Object[][]
+        //this also holds when the element classes aren't the same (but are both reference types)
+        int dimensions = Math.min(class1.arrayDimensions, class2.arrayDimensions);
+        return getArrayClassDefByElementClassAndDimension(theClassPath.javaLangObjectClassDef, dimensions);
+    }
+
+    public static class ArrayClassDef extends ClassDef {
+        private final ClassDef elementClass;
+        private final int arrayDimensions;
+
+        protected ArrayClassDef(String arrayClassType) {
+            super(arrayClassType, true);
+            assert arrayClassType.charAt(0) == '[';
+
+            int i=0;
+            while (arrayClassType.charAt(i) == '[') i++;
+
+            String elementClassType = arrayClassType.substring(i);
+
+            if (i>256) {
+                throw new ExceptionWithContext("Error while creating array class for element type " + elementClassType +
+                        " with " + i + " dimensions. The maximum number of dimensions is 256");
+            }
+
+            try {
+                elementClass = ClassPath.getClassDef(arrayClassType.substring(i));
+            } catch (ClassNotFoundException ex) {
+                throw ExceptionWithContext.withContext(ex, "Error while creating array class " + arrayClassType);
+            }
+            arrayDimensions = i;
+        }
+
+        public ClassDef getElementClass() {
+            return elementClass;
+        }
+
+        public int getArrayDimensions() {
+            return arrayDimensions;
+        }
+    }
+
+    public static class PrimitiveClassDef extends ClassDef {
+        protected PrimitiveClassDef(String primitiveClassType) {
+            super(primitiveClassType, false);
+        }
+    }
+
+    public static class ClassDef {
+        private final String classType;
+        private final ClassDef superclass;
+        /**
+         * This is a list of all of the interfaces that a class implements, either directly or indirectly. It includes
+         * all interfaces implemented by the superclass, and all super-interfaces of any implemented interface. The
+         * intention is to make it easier to determine whether the class implements a given interface or not.
+         */
+        private final TreeSet<ClassDef> implementedInterfaces;
+
+        private final boolean isInterface;
+
+        private final int classDepth;
+
+        private final String[] vtable;
+        private final HashMap<String, Integer> virtualMethodLookup;
+
+        private final SparseArray<String> instanceFields;
+        private final HashMap<String, Integer> instanceFieldLookup;
+
+        /**
+         * This constructor is used for the ArrayClassDef and PrimitiveClassDef subclasses
+         * @param classType the class type
+         * @param isArrayType whether this is an array ClassDef or a primitive ClassDef
+         */
+        protected ClassDef(String classType, boolean isArrayType) {
+            if (isArrayType) {
+                assert (classType.charAt(0) == '[');
+                this.classType = classType;
+                this.superclass = ClassPath.theClassPath.javaLangObjectClassDef;
+                implementedInterfaces = new TreeSet<ClassDef>();
+                implementedInterfaces.add(ClassPath.getClassDef("Ljava/lang/Cloneable;"));
+                implementedInterfaces.add(ClassPath.getClassDef("Ljava/io/Serializable;"));
+                isInterface = false;
+
+                vtable = superclass.vtable;
+                virtualMethodLookup = superclass.virtualMethodLookup;
+
+                instanceFields = superclass.instanceFields;
+                instanceFieldLookup = superclass.instanceFieldLookup;
+                classDepth = 1; //1 off from java.lang.Object
+            } else {
+                //primitive type
+                this.classType = classType;
+                this.superclass = null;
+                implementedInterfaces = null;
+                isInterface = false;
+                vtable = null;
+                virtualMethodLookup = null;
+                instanceFields = null;
+                instanceFieldLookup = null;
+                classDepth = 0; //TODO: maybe use -1 to indicate not applicable?
+            }
+        }
+
+        protected ClassDef(ClassDefItem classDefItem) {
+            classType = classDefItem.getClassType().getTypeDescriptor();
+
+            isInterface = (classDefItem.getAccessFlags() & AccessFlags.INTERFACE.getValue()) != 0;
+
+            superclass = loadSuperclass(classDefItem);
+            if (superclass == null) {
+                classDepth = 0;
+            } else {
+                classDepth = superclass.classDepth + 1;
+            }
+
+            implementedInterfaces = loadAllImplementedInterfaces(classDefItem);
+
+            vtable = loadVtable(classDefItem);
+            virtualMethodLookup = new HashMap<String, Integer>((int)Math.ceil(vtable.length / .7f), .75f);
+            for (int i=0; i<vtable.length; i++) {
+                virtualMethodLookup.put(vtable[i], i);
+            }
+
+            instanceFields = loadFields(classDefItem);
+            instanceFieldLookup = new HashMap<String, Integer>((int)Math.ceil(instanceFields.size() / .7f), .75f);
+            for (int i=0; i<instanceFields.size(); i++) {
+                instanceFieldLookup.put(instanceFields.get(i), i);
+            }
+        }
+
+        public String getClassType() {
+            return classType;
+        }
+
+        public ClassDef getSuperclass() {
+            return superclass;
+        }
+
+        public int getClassDepth() {
+            return classDepth;
+        }
+
+        public boolean isInterface() {
+            return this.isInterface;
+        }
+
+        public boolean extendsClass(ClassDef superclassDef) {
+            if (superclassDef == null) {
+                return false;
+            }
+
+            if (this == superclassDef) {
+                return true;
+            }
+
+            int superclassDepth = superclassDef.classDepth;
+            ClassDef ancestor = this;
+            while (ancestor.classDepth > superclassDepth) {
+                ancestor = ancestor.getSuperclass();
+            }
+
+            return ancestor == superclassDef;
+        }
+
+        /**
+         * Returns true if this class implements the given interface. This searches the interfaces that this class
+         * directly implements, any interface implemented by this class's superclasses, and any super-interface of
+         * any of these interfaces.
+         * @param interfaceDef the interface
+         * @return true if this class implements the given interface
+         */
+        public boolean implementsInterface(ClassDef interfaceDef) {
+            return implementedInterfaces.contains(interfaceDef);
+        }
+
+        //TODO: GROT
+        public void dumpVtable() {
+            System.out.println(classType + " methods:");
+            int i=0;
+            for (String method: vtable) {
+                System.out.println(i + ":\t" + method);
+                i++;
+            }
+        }
+
+        //TODO: GROT
+        public void dumpFields() {
+            System.out.println(classType + " fields:");
+            for (int i=0; i<instanceFields.size(); i++) {
+                int fieldOffset = instanceFields.keyAt(i);
+                System.out.println(fieldOffset + ":\t" + instanceFields.valueAt(i));
+            }
+        }
+
+        private void swap(byte[] fieldTypes, String[] fields, int position1, int position2) {
+            byte tempType = fieldTypes[position1];
+            fieldTypes[position1] = fieldTypes[position2];
+            fieldTypes[position2] = tempType;
+
+            String tempField = fields[position1];
+            fields[position1] = fields[position2];
+            fields[position2] = tempField;
+        }
+
+        private ClassDef loadSuperclass(ClassDefItem classDefItem) {
+            if (classDefItem.getClassType().getTypeDescriptor().equals("Ljava/lang/Object;")) {
+                if (classDefItem.getSuperclass() != null) {
+                    throw new ExceptionWithContext("Invalid superclass " +
+                            classDefItem.getSuperclass().getTypeDescriptor() + " for Ljava/lang/Object;. " +
+                            "The Object class cannot have a superclass");
+                }
+                return null;
+            } else {
+                TypeIdItem superClass = classDefItem.getSuperclass();
+                if (superClass == null) {
+                    throw new ExceptionWithContext(classDefItem.getClassType().getTypeDescriptor() +
+                            " has no superclass");
+                }
+
+                ClassDef superclass = ClassPath.getClassDef(superClass.getTypeDescriptor());
+
+                if (!isInterface && superclass.isInterface) {
+                    throw new ValidationException("Class " + classType + " has the interface " + superclass.classType +
+                            " as its superclass");
+                }
+                if (isInterface && !superclass.isInterface && superclass !=
+                        ClassPath.theClassPath.javaLangObjectClassDef) {
+                    throw new ValidationException("Interface " + classType + " has the non-interface class " +
+                            superclass.classType + " as its superclass");
+                }
+
+                return superclass;
+            }
+        }
+
+        private TreeSet<ClassDef> loadAllImplementedInterfaces(ClassDefItem classDefItem) {
+            assert classType != null;
+            assert classType.equals("Ljava/lang/Object;") || superclass != null;
+            assert classDefItem != null;
+
+            TreeSet<ClassDef> implementedInterfaceSet = new TreeSet<ClassDef>();
+
+            if (superclass != null) {
+                for (ClassDef interfaceDef: superclass.implementedInterfaces) {
+                    implementedInterfaceSet.add(interfaceDef);
+                }
+            }
+
+            TypeListItem interfaces = classDefItem.getInterfaces();
+            if (interfaces != null) {
+                for (TypeIdItem interfaceType: interfaces.getTypes()) {
+                    ClassDef interfaceDef = ClassPath.getClassDef(interfaceType.getTypeDescriptor());
+                    assert interfaceDef.isInterface;
+                    implementedInterfaceSet.add(interfaceDef);
+
+                    interfaceDef = interfaceDef.getSuperclass();
+                    while (!interfaceDef.getClassType().equals("Ljava/lang/Object;")) {
+                        assert interfaceDef.isInterface;
+                        implementedInterfaceSet.add(interfaceDef);
+                        interfaceDef = interfaceDef.getSuperclass();
+                    }
+                }
+            }
+
+            return implementedInterfaceSet;
+        }
+
+        private String[] loadVtable(ClassDefItem classDefItem) {
+            //TODO: it might be useful to keep track of which class's implementation is used for each virtual method. In other words, associate the implementing class type with each vtable entry
+            List<String> virtualMethodList = new LinkedList<String>();
+            //use a temp hash table, so that we can construct the final lookup with an appropriate
+            //capacity, based on the number of virtual methods
+            HashMap<String, Integer> tempVirtualMethodLookup = new HashMap<String, Integer>();
+
+            //copy the virtual methods from the superclass
+            int methodIndex = 0;
+            if (superclass != null) {
+                for (String method: superclass.vtable) {
+                    virtualMethodList.add(method);
+                    tempVirtualMethodLookup.put(method, methodIndex++);
+                }
+
+                assert superclass.instanceFields != null;
+            }
+
+
+            //iterate over the virtual methods in the current class, and only add them when we don't already have the
+            //method (i.e. if it was implemented by the superclass)
+            ClassDataItem classDataItem = classDefItem.getClassData();
+            if (classDataItem != null) {
+                EncodedMethod[] virtualMethods = classDataItem.getVirtualMethods();
+                if (virtualMethods != null) {
+                    for (EncodedMethod virtualMethod: virtualMethods) {
+                        String methodString = virtualMethod.method.getMethodString();
+                        if (tempVirtualMethodLookup.get(methodString) == null) {
+                            virtualMethodList.add(methodString);
+                        }
+                    }
+                }
+            }
+
+            String[] vtable = new String[virtualMethodList.size()];
+            for (int i=0; i<virtualMethodList.size(); i++) {
+                vtable[i] = virtualMethodList.get(i);
+            }
+
+            return vtable;
+        }
+
+        private SparseArray<String> loadFields(ClassDefItem classDefItem) {
+            //This is a bit of an "involved" operation. We need to follow the same algorithm that dalvik uses to
+            //arrange fields, so that we end up with the same field offsets (which is needed for deodexing).
+
+            final byte REFERENCE = 0;
+            final byte WIDE = 1;
+            final byte OTHER = 2;
+
+            ClassDataItem classDataItem = classDefItem.getClassData();
+
+            String[] fields = null;
+            //the "type" for each field in fields. 0=reference,1=wide,2=other
+            byte[] fieldTypes = null;
+
+            if (classDataItem != null) {
+                EncodedField[] encodedFields = classDataItem.getInstanceFields();
+                if (encodedFields != null) {
+                    fields = new String[encodedFields.length];
+                    fieldTypes = new byte[encodedFields.length];
+
+                    for (int i=0; i<encodedFields.length; i++) {
+                        EncodedField encodedField = encodedFields[i];
+                        String fieldType = encodedField.field.getFieldType().getTypeDescriptor();
+                        String field = String.format("%s:%s", encodedField.field.getFieldName().getStringValue(),
+                                fieldType);
+                        fieldTypes[i] = getFieldType(field);
+                        fields[i] = field;
+                    }
+                }
+            }
+
+            if (fields == null) {
+                fields = new String[0];
+                fieldTypes = new byte[0];
+            }
+
+            //The first operation is to move all of the reference fields to the front. To do this, find the first
+            //non-reference field, then find the last reference field, swap them and repeat
+            int back = fields.length - 1;
+            int front;
+            for (front = 0; front<fields.length; front++) {
+                if (fieldTypes[front] != REFERENCE) {
+                    while (back > front) {
+                        if (fieldTypes[back] == REFERENCE) {
+                            swap(fieldTypes, fields, front, back--);
+                            break;
+                        }
+                        back--;
+                    }
+                }
+
+                if (fieldTypes[front] != REFERENCE) {
+                    break;
+                }
+            }
+
+            //next, we need to group all the wide fields after the reference fields. But the wide fields have to be
+            //8-byte aligned. If we're on an odd field index, we need to insert a 32-bit field. If the next field
+            //is already a 32-bit field, use that. Otherwise, find the first 32-bit field from the end and swap it in.
+            //If there are no 32-bit fields, do nothing for now. We'll add padding when calculating the field offsets
+            if (front < fields.length && (front % 2) != 0) {
+                if (fieldTypes[front] == WIDE) {
+                    //we need to swap in a 32-bit field, so the wide fields will be correctly aligned
+                    back = fields.length - 1;
+                    while (back > front) {
+                        if (fieldTypes[back] == OTHER) {
+                            swap(fieldTypes, fields, front++, back);
+                            break;
+                        }
+                        back--;
+                    }
+                } else {
+                    //there's already a 32-bit field here that we can use
+                    front++;
+                }
+            }
+
+            //do the swap thing for wide fields
+            back = fields.length - 1;
+            for (; front<fields.length; front++) {
+                if (fieldTypes[front] != WIDE) {
+                    while (back > front) {
+                        if (fieldTypes[back] == WIDE) {
+                            swap(fieldTypes, fields, front, back--);
+                            break;
+                        }
+                        back--;
+                    }
+                }
+
+                if (fieldTypes[front] != WIDE) {
+                    break;
+                }
+            }
+
+            int superFieldCount = 0;
+            if (superclass != null) {
+                superclass.instanceFields.size();
+            }
+
+            //now the fields are in the correct order. Add them to the SparseArray and lookup, and calculate the offsets
+            int totalFieldCount = superFieldCount + fields.length;
+            SparseArray<String> instanceFields = new SparseArray<String>(totalFieldCount);
+
+            int fieldOffset;
+
+            if (superclass != null && superFieldCount > 0) {
+                for (int i=0; i<superFieldCount; i++) {
+                    instanceFields.append(superclass.instanceFields.keyAt(i), superclass.instanceFields.valueAt(i));
+                }
+
+                fieldOffset = instanceFields.keyAt(superFieldCount-1);
+
+                String lastSuperField = superclass.instanceFields.valueAt(superFieldCount-1);
+                assert lastSuperField.indexOf(':') >= 0;
+                assert lastSuperField.indexOf(':') < superFieldCount-1; //the ':' shouldn't be the last char
+                char fieldType = lastSuperField.charAt(lastSuperField.indexOf(':') + 1);
+                if (fieldType == 'J' || fieldType == 'D') {
+                    fieldOffset += 8;
+                } else {
+                    fieldOffset += 4;
+                }
+            } else {
+                //the field values start at 8 bytes into the DataObject dalvik structure
+                fieldOffset = 8;
+            }
+
+            boolean gotDouble = false;
+            for (int i=0; i<fields.length; i++) {
+                String field = fields[i];
+
+                //add padding to align the wide fields, if needed
+                if (fieldTypes[i] == WIDE && !gotDouble) {
+                    if (!gotDouble) {
+                        if (fieldOffset % 8 != 0) {
+                            assert fieldOffset % 8 == 4;
+                            fieldOffset += 4;
+                        }
+                        gotDouble = true;
+                    }
+                }
+
+                instanceFields.append(fieldOffset, field);
+                if (fieldTypes[i] == WIDE) {
+                    fieldOffset += 8;
+                } else {
+                    fieldOffset += 4;
+                }
+            }
+            return instanceFields;
+        }
+
+        private byte getFieldType(String field) {
+            int sepIndex = field.indexOf(':');
+
+            //we could use sepIndex >= field.length()-1 instead, but that's too easy to mistake for an off-by-one error
+            if (sepIndex < 0 || sepIndex == field.length()-1 || sepIndex >= field.length()) {
+                assert false;
+                throw new ExceptionWithContext("Invalid field format: " + field);
+            }
+            switch (field.charAt(sepIndex+1)) {
+                case '[':
+                case 'L':
+                    return 0; //REFERENCE
+                case 'J':
+                case 'D':
+                    return 1; //WIDE
+                default:
+                    return 2; //OTHER
+            }
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (!(o instanceof ClassDef)) return false;
+
+            ClassDef classDef = (ClassDef) o;
+
+            return classType.equals(classDef.classType);
+        }
+
+        @Override
+        public int hashCode() {
+            return classType.hashCode();
+        }
+    }
+}

dexlib/src/main/java/org/jf/dexlib/Code/Analysis/RegisterInfo.java

@@ -1,10 +0,0 @@
-package org.jf.dexlib.Code.Analysis;
-
-import java.util.LinkedList;
-
-public class RegisterInfo {
-    private final LinkedList<RegisterType> possibleRegisterTypes = new LinkedList<RegisterType>();
-
-    protected RegisterInfo() {
-    }
-}

dexlib/src/main/java/org/jf/dexlib/Code/Analysis/RegisterType.java

@@ -1,16 +1,32 @@
 package org.jf.dexlib.Code.Analysis;
 
+import org.jf.dexlib.ClassDefItem;
 import org.jf.dexlib.TypeIdItem;
+import static org.jf.dexlib.Code.Analysis.ClassPath.ClassDef;
+import static org.jf.dexlib.Code.Analysis.ClassPath.PrimitiveClassDef;
+import static org.jf.dexlib.Code.Analysis.ClassPath.ArrayClassDef;
+import java.util.HashMap;
 
 public class RegisterType {
-    public final Category category;
-    public final TypeIdItem type;
+    private final static HashMap<RegisterType, RegisterType> internedRegisterTypes =
+            new HashMap<RegisterType, RegisterType>();
+
+    public final Category category;
+    public final ClassDef type;
+
+    private RegisterType(Category category, ClassDef type) {
+        assert ((category == Category.Reference || category == Category.UninitRef) && type != null) ||
+               ((category != Category.Reference && category != Category.UninitRef) && type == null);
 
-    protected RegisterType(Category category, TypeIdItem type) {
         this.category = category;
         this.type = type;
     }
 
+    @Override
+    public String toString() {
+        return "(" + category.name() + (type==null?"":("," + type.getClassType())) + ")";
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -31,26 +47,158 @@ public class RegisterType {
         return result;
     }
 
-
-    /*private static RegisterType[][] mergeTable  =
-        {
-               //Unknown        Null            Nonreference    Reference   Conflicted
-                {Unknown,       Null,           NonReference,   Reference,  Conflicted}, //Unknown
-                {Null,          Null,           NonReference,   Reference,  Conflicted}, //Null
-                {NonReference,  NonReference,   NonReference,   Conflicted, Conflicted}, //NonReference
-                {Reference,     Reference,      Conflicted,     Reference,  Conflicted}, //Referenced
-                {Conflicted,    Conflicted,     Conflicted,     Conflicted, Conflicted}, //Conflicted
-        };*/
-
-    /*public static RegisterType mergeRegisterTypes(RegisterType type1, RegisterType type2) {
-        return mergeTable[type1.ordinal()][type2.ordinal()];
-    }*/
-
     public static enum Category {
         Unknown,
         Null,
-        NonReference,
+        One,
+        Boolean,
+        Byte,
+        PosByte,
+        Short,
+        PosShort,
+        Char,
+        Integer,
+        Float,
+        LongLo,
+        LongHi,
+        DoubleLo,
+        DoubleHi,
+        UninitRef,
         Reference,
-        Conflicted
+        Conflicted;
+
+        protected static Category[][] mergeTable  =
+        {
+                /*             Unknown      Null        One,        Boolean     Byte        PosByte     Short       PosShort    Char        Integer,    Float,      LongLo      LongHi      DoubleLo    DoubleHi    UninitRef   Reference   Conflicted*/
+                /*Unknown*/    {Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown,    Unknown},
+                /*Null*/       {Unknown,    Null,       Conflicted, Boolean,    Byte,       PosByte,    Short,      PosShort,   Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Reference,  Conflicted},
+                /*One*/        {Unknown,    Conflicted, One,        Boolean,    Byte,       PosByte,    Short,      PosShort,   Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Boolean*/    {Unknown,    Boolean,    Boolean,    Boolean,    Byte,       PosByte,    Short,      PosShort,   Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Byte*/       {Unknown,    Byte,       Byte,       Byte,       Byte,       Byte,       Short,      Short,      Integer,    Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*PosByte*/    {Unknown,    PosByte,    PosByte,    PosByte,    Byte,       PosByte,    Short,      PosShort,   Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Short*/      {Unknown,    Short,      Short,      Short,      Short,      Short,      Short,      Short,      Integer,    Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*PosShort*/   {Unknown,    PosShort,   PosShort,   PosShort,   Short,      PosShort,   Short,      PosShort,   Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Char*/       {Unknown,    Char,       Char,       Char,       Integer,    Char,       Integer,    Char,       Char,       Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Integer*/    {Unknown,    Integer,    Integer,    Integer,    Integer,    Integer,    Integer,    Integer,    Integer,    Integer,    Integer,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*Float*/      {Unknown,    Float,      Float,      Float,      Float,      Float,      Float,      Float,      Float,      Integer,    Float,      Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted},
+                /*LongLo*/     {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, LongLo,     Conflicted, LongLo,     Conflicted, Conflicted, Conflicted, Conflicted},
+                /*LongHi*/     {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, LongHi,     Conflicted, LongHi,     Conflicted, Conflicted, Conflicted},
+                /*DoubleLo*/   {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, LongLo,     Conflicted, DoubleLo,   Conflicted, Conflicted, Conflicted, Conflicted},
+                /*DoubleHi*/   {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, LongHi,     Conflicted, DoubleHi,   Conflicted, Conflicted, Conflicted},
+                /*UninitRef*/  {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, UninitRef,  Conflicted, Conflicted},
+                /*Reference*/  {Unknown,    Reference,  Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Reference,  Conflicted},
+                /*Conflicted*/ {Unknown,    Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted, Conflicted}
+        };
+    }
+
+    public static RegisterType getRegisterTypeForTypeIdItem(TypeIdItem typeIdItem) {
+        switch (typeIdItem.getTypeDescriptor().charAt(0)) {
+            case 'V':
+                throw new ValidationException("The V type can only be used as a method return type");
+            case 'Z':
+                return getRegisterType(Category.Boolean, null);
+            case 'B':
+                return getRegisterType(Category.Byte, null);
+            case 'S':
+                return getRegisterType(Category.Short, null);
+            case 'C':
+                return getRegisterType(Category.Char, null);
+            case 'I':
+                return getRegisterType(Category.Integer, null);
+            case 'F':
+                return getRegisterType(Category.Float, null);
+            case 'J':
+                return getRegisterType(Category.LongLo, null);
+            case 'D':
+                return getRegisterType(Category.DoubleLo, null);
+            case 'L':
+            case '[':
+                return getRegisterType(Category.Reference, ClassPath.getClassDef(typeIdItem));
+            default:
+                throw new RuntimeException("Invalid type: " + typeIdItem.getTypeDescriptor());
+        }
+    }
+
+    public static RegisterType getWideRegisterTypeForTypeIdItem(TypeIdItem typeIdItem, boolean firstRegister) {
+        if (typeIdItem.getRegisterCount() == 1) {
+            throw new RuntimeException("Cannot use this method for non-wide register type: " +
+                    typeIdItem.getTypeDescriptor());
+        }
+
+        switch (typeIdItem.getTypeDescriptor().charAt(0)) {
+            case 'J':
+                if (firstRegister) {
+                    return getRegisterType(Category.LongLo, null);
+                } else {
+                    return getRegisterType(Category.LongHi, null);
+                }
+            case 'D':
+                if (firstRegister) {
+                    return getRegisterType(Category.DoubleLo, null);
+                } else {
+                    return getRegisterType(Category.DoubleHi, null);
+                }
+            default:
+                throw new RuntimeException("Invalid type: " + typeIdItem.getTypeDescriptor());
+        }
+    }
+
+    public static RegisterType getRegisterTypeForLiteral(long literalValue) {
+        if (literalValue < -32768) {
+            return getRegisterType(Category.Integer, null);
+        }
+        if (literalValue < -128) {
+            return getRegisterType(Category.Short, null);
+        }
+        if (literalValue < 0) {
+            return getRegisterType(Category.Byte, null);
+        }
+        if (literalValue == 0) {
+            return getRegisterType(Category.Null, null);
+        }
+        if (literalValue == 1) {
+            return getRegisterType(Category.One, null);
+        }
+        if (literalValue < 128) {
+            return getRegisterType(Category.PosByte, null);
+        }
+        if (literalValue < 32768) {
+            return getRegisterType(Category.PosShort, null);
+        }
+        if (literalValue < 65536) {
+            return getRegisterType(Category.Char, null);
+        }
+        return getRegisterType(Category.Integer, null);
+    }
+
+    public RegisterType merge(RegisterType type) {
+        if (type == null || type == this) {
+            return this;
+        }
+
+        Category mergedCategory = Category.mergeTable[this.category.ordinal()][type.category.ordinal()];
+        if (mergedCategory == Category.Conflicted) {
+            throw new ValidationException("Incompatible register types." +
+                    " Category1: " + this.category.name() +
+                    (this.type==null?"":" Type1: " + this.type.getClassType()) +
+                    " Category2: " + type.category.name() +
+                    (type.type==null?"":" Type2: " + type.type.getClassType()));
+        }
+
+        ClassDef mergedType = null;
+        if (mergedCategory == Category.Reference) {
+            mergedType = ClassPath.getCommonSuperclass(this.type, type.type);
+        }
+        return RegisterType.getRegisterType(mergedCategory, mergedType);
+    }
+
+    public static RegisterType getRegisterType(Category category, ClassDef classType) {
+        RegisterType newRegisterType = new RegisterType(category, classType);
+        RegisterType internedRegisterType = internedRegisterTypes.get(newRegisterType);
+        if (internedRegisterType == null) {
+            internedRegisterTypes.put(newRegisterType, newRegisterType);
+            return newRegisterType;
+        }
+        return internedRegisterType;
     }
 }

dexlib/src/main/java/org/jf/dexlib/Code/Analysis/ValidationException.java

@@ -1,6 +1,8 @@
 package org.jf.dexlib.Code.Analysis;
 
-public class ValidationException extends RuntimeException {
+import org.jf.dexlib.Util.ExceptionWithContext;
+
+public class ValidationException extends ExceptionWithContext {
     public ValidationException(String errorMessage) {
         super(errorMessage);
     }