private StructureConstant createClassInfoStruct() {
    int flags = 0;

    if (Modifier.isPublic(sootClass.getModifiers())) {
      flags |= CI_PUBLIC;
    }
    if (Modifier.isFinal(sootClass.getModifiers())) {
      flags |= CI_FINAL;
    }
    if (Modifier.isInterface(sootClass.getModifiers())) {
      flags |= CI_INTERFACE;
    }
    if (Modifier.isAbstract(sootClass.getModifiers())) {
      flags |= CI_ABSTRACT;
    }
    if ((sootClass.getModifiers() & 0x1000) > 0) {
      flags |= CI_SYNTHETIC;
    }
    if (Modifier.isAnnotation(sootClass.getModifiers())) {
      flags |= CI_ANNOTATION;
    }
    if (Modifier.isEnum(sootClass.getModifiers())) {
      flags |= CI_ENUM;
    }
    if (attributesEncoder.classHasAttributes()) {
      flags |= CI_ATTRIBUTES;
    }
    if (hasFinalizer(sootClass)) {
      flags |= CI_FINALIZABLE;
    }

    // Create the ClassInfoHeader structure.
    StructureConstantBuilder header = new StructureConstantBuilder();
    header.add(new NullConstant(I8_PTR)); // Points to the runtime Class struct
    header.add(new IntegerConstant(flags));
    header.add(getString(getInternalName(sootClass)));
    if (sootClass.declaresMethod("<clinit>", Collections.emptyList(), VoidType.v())) {
      SootMethod method = sootClass.getMethod("<clinit>", Collections.emptyList(), VoidType.v());
      header.add(new FunctionRef(mangleMethod(method), getFunctionType(method)));
    } else {
      header.add(new NullConstant(I8_PTR));
    }
    header.add(sizeof(classType));
    header.add(sizeof(instanceType));
    if (!instanceFields.isEmpty()) {
      header.add(offsetof(instanceType, 1, 1));
    } else {
      header.add(sizeof(instanceType));
    }
    header.add(new IntegerConstant((short) countReferences(classFields)));
    header.add(new IntegerConstant((short) countReferences(instanceFields)));

    PackedStructureConstantBuilder body = new PackedStructureConstantBuilder();
    body.add(new IntegerConstant((short) sootClass.getInterfaceCount()));
    body.add(new IntegerConstant((short) sootClass.getFieldCount()));
    body.add(new IntegerConstant((short) sootClass.getMethodCount()));

    if (!sootClass.isInterface()) {
      body.add(
          getStringOrNull(
              sootClass.hasSuperclass() ? getInternalName(sootClass.getSuperclass()) : null));
    }

    if (attributesEncoder.classHasAttributes()) {
      body.add(new ConstantBitcast(attributesEncoder.getClassAttributes().ref(), I8_PTR));
    }

    for (SootClass s : sootClass.getInterfaces()) {
      body.add(getString(getInternalName(s)));
    }

    for (SootField f : sootClass.getFields()) {
      flags = 0;
      soot.Type t = f.getType();
      if (t instanceof PrimType) {
        if (t.equals(BooleanType.v())) {
          flags |= DESC_Z;
        } else if (t.equals(ByteType.v())) {
          flags |= DESC_B;
        } else if (t.equals(ShortType.v())) {
          flags |= DESC_S;
        } else if (t.equals(CharType.v())) {
          flags |= DESC_C;
        } else if (t.equals(IntType.v())) {
          flags |= DESC_I;
        } else if (t.equals(LongType.v())) {
          flags |= DESC_J;
        } else if (t.equals(FloatType.v())) {
          flags |= DESC_F;
        } else if (t.equals(DoubleType.v())) {
          flags |= DESC_D;
        }
        flags <<= 12;
      }
      if (Modifier.isPublic(f.getModifiers())) {
        flags |= FI_PUBLIC;
      } else if (Modifier.isPrivate(f.getModifiers())) {
        flags |= FI_PRIVATE;
      } else if (Modifier.isProtected(f.getModifiers())) {
        flags |= FI_PROTECTED;
      }
      if (Modifier.isStatic(f.getModifiers())) {
        flags |= FI_STATIC;
      }
      if (Modifier.isFinal(f.getModifiers())) {
        flags |= FI_FINAL;
      }
      if (Modifier.isVolatile(f.getModifiers())) {
        flags |= FI_VOLATILE;
      }
      if (Modifier.isTransient(f.getModifiers())) {
        flags |= FI_TRANSIENT;
      }
      if ((f.getModifiers() & 0x1000) > 0) {
        flags |= FI_SYNTHETIC;
      }
      if (Modifier.isEnum(f.getModifiers())) {
        flags |= FI_ENUM;
      }
      if (attributesEncoder.fieldHasAttributes(f)) {
        flags |= FI_ATTRIBUTES;
      }
      body.add(new IntegerConstant((short) flags));
      body.add(getString(f.getName()));
      if (!(t instanceof PrimType)) {
        body.add(getString(getDescriptor(f)));
      }
      if (f.isStatic()) {
        int index = classFields.indexOf(f);
        body.add(offsetof(classType, 1, index, 1));
      } else {
        int index = instanceFields.indexOf(f);
        body.add(offsetof(instanceType, 1, 1 + index, 1));
      }
      if (attributesEncoder.fieldHasAttributes(f)) {
        body.add(new ConstantBitcast(attributesEncoder.getFieldAttributes(f).ref(), I8_PTR));
      }
    }

    for (SootMethod m : sootClass.getMethods()) {
      soot.Type t = m.getReturnType();
      flags = 0;
      if (Modifier.isPublic(m.getModifiers())) {
        flags |= MI_PUBLIC;
      } else if (Modifier.isPrivate(m.getModifiers())) {
        flags |= MI_PRIVATE;
      } else if (Modifier.isProtected(m.getModifiers())) {
        flags |= MI_PROTECTED;
      }
      if (Modifier.isStatic(m.getModifiers())) {
        flags |= MI_STATIC;
      }
      if (Modifier.isFinal(m.getModifiers())) {
        flags |= MI_FINAL;
      }
      if (Modifier.isSynchronized(m.getModifiers())) {
        flags |= MI_SYNCHRONIZED;
      }
      if ((m.getModifiers() & 0x0040) > 0) {
        flags |= MI_BRIDGE;
      }
      if ((m.getModifiers() & 0x0080) > 0) {
        flags |= MI_VARARGS;
      }
      if (Modifier.isNative(m.getModifiers())) {
        if (!isStruct(sootClass) && !isStructMember(m)) {
          flags |= MI_NATIVE;
        }
      }
      if (Modifier.isAbstract(m.getModifiers())) {
        flags |= MI_ABSTRACT;
      }
      if (Modifier.isStrictFP(m.getModifiers())) {
        flags |= MI_STRICT;
      }
      if ((m.getModifiers() & 0x1000) > 0) {
        flags |= MI_SYNTHETIC;
      }
      if (attributesEncoder.methodHasAttributes(m)) {
        flags |= MI_ATTRIBUTES;
      }
      if (isBridge(m)) {
        flags |= MI_BRO_BRIDGE;
      }
      if (isCallback(m)) {
        flags |= MI_BRO_CALLBACK;
      }
      if ((t instanceof PrimType || t == VoidType.v()) && m.getParameterCount() == 0) {
        flags |= MI_COMPACT_DESC;
      }
      body.add(new IntegerConstant((short) flags));

      body.add(getString(m.getName()));

      if ((flags & MI_COMPACT_DESC) > 0) {
        int desc = 0;
        if (t.equals(BooleanType.v())) {
          desc = DESC_Z;
        } else if (t.equals(ByteType.v())) {
          desc = DESC_B;
        } else if (t.equals(ShortType.v())) {
          desc = DESC_S;
        } else if (t.equals(CharType.v())) {
          desc = DESC_C;
        } else if (t.equals(IntType.v())) {
          desc = DESC_I;
        } else if (t.equals(LongType.v())) {
          desc = DESC_J;
        } else if (t.equals(FloatType.v())) {
          desc = DESC_F;
        } else if (t.equals(DoubleType.v())) {
          desc = DESC_D;
        } else if (t.equals(VoidType.v())) {
          desc = DESC_V;
        }
        body.add(new IntegerConstant((byte) desc));
      } else {
        body.add(getString(getDescriptor(m)));
      }
      if (attributesEncoder.methodHasAttributes(m)) {
        body.add(new ConstantBitcast(attributesEncoder.getMethodAttributes(m).ref(), I8_PTR));
      }
      if (!m.isAbstract()) {
        body.add(new ConstantBitcast(new FunctionRef(mangleMethod(m), getFunctionType(m)), I8_PTR));
        body.add(
            new IntegerConstant(
                DUMMY_METHOD_SIZE)); // Size of function. This value will be modified later by
                                     // patching the .s file.
        if (m.isSynchronized()) {
          body.add(
              new ConstantBitcast(
                  new FunctionRef(mangleMethod(m) + "_synchronized", getFunctionType(m)), I8_PTR));
        }
      }
      if (isBridge(m)) {
        body.add(new GlobalRef(BridgeMethodCompiler.getTargetFnPtrName(m), I8_PTR));
      }
      if (isCallback(m)) {
        body.add(
            new ConstantBitcast(
                new FunctionRef(mangleMethod(m) + "_callback", getCallbackFunctionType(m)),
                I8_PTR));
      }
    }

    // Return the struct {header, body}. To be compatible with the C code in classinfo.c
    // it is important that the header is padded the same as in C so that the body starts
    // after sizeof(ClassInfoHeader) bytes.
    return new StructureConstantBuilder().add(header.build()).add(body.build()).build();
  }
  private void compile(Clazz clazz, OutputStream out) throws IOException {
    sootClass = clazz.getSootClass();
    mb = new ModuleBuilder();
    trampolines = new HashSet<Trampoline>();
    catches = new HashSet<String>();
    classFields = getClassFields(sootClass);
    instanceFields = getInstanceFields(sootClass);
    classType = getClassType(sootClass);
    instanceType = getInstanceType(sootClass);

    attributesEncoder.encode(mb, sootClass);

    // Add a <clinit> method if the class has ConstantValueTags but no <clinit>.
    // This has to be done before createInfoStruct() is called otherwise the
    // ClassInfoHeader->initializer value will become NULL and constant static fields
    // will never be initialized.
    if (!sootClass.declaresMethodByName("<clinit>") && hasConstantValueTags(classFields)) {
      SootMethod clinit =
          new SootMethod("<clinit>", Collections.EMPTY_LIST, VoidType.v(), Modifier.STATIC);
      JimpleBody body = Jimple.v().newBody(clinit);
      clinit.setActiveBody(body);
      body.getUnits().add(new JReturnVoidStmt());
      this.sootClass.addMethod(clinit);
    }

    if (isStruct(sootClass)) {
      if (!Modifier.isFinal(sootClass.getModifiers())) {
        throw new IllegalArgumentException("Struct class must be final");
      }
      SootMethod _sizeOf =
          new SootMethod("_sizeOf", Collections.EMPTY_LIST, IntType.v(), Modifier.PROTECTED);
      sootClass.addMethod(_sizeOf);
      SootMethod sizeOf =
          new SootMethod(
              "sizeOf", Collections.EMPTY_LIST, IntType.v(), Modifier.PUBLIC | Modifier.STATIC);
      sootClass.addMethod(sizeOf);
    }

    mb.addInclude(
        getClass()
            .getClassLoader()
            .getResource(
                String.format("header-%s-%s.ll", config.getOs().getFamily(), config.getArch())));
    mb.addInclude(getClass().getClassLoader().getResource("header.ll"));

    mb.addFunction(createInstanceof());
    mb.addFunction(createCheckcast());
    mb.addFunction(createLdcClass());
    mb.addFunction(createLdcClassWrapper());
    Function allocator = createAllocator();
    mb.addFunction(allocator);
    mb.addFunction(createClassInitWrapperFunction(allocator.ref()));

    for (SootField f : sootClass.getFields()) {
      Function getter = createFieldGetter(f);
      Function setter = createFieldSetter(f);
      mb.addFunction(getter);
      mb.addFunction(setter);
      if (f.isStatic() && !f.isPrivate()) {
        mb.addFunction(createClassInitWrapperFunction(getter.ref()));
        if (!f.isFinal()) {
          mb.addFunction(createClassInitWrapperFunction(setter.ref()));
        }
      }
    }

    for (SootMethod method : sootClass.getMethods()) {
      String name = method.getName();
      if (isBridge(method)) {
        bridgeMethod(method);
      } else if (isStruct(sootClass)
          && ("_sizeOf".equals(name) || "sizeOf".equals(name) || isStructMember(method))) {
        structMember(method);
      } else if (method.isNative()) {
        nativeMethod(method);
      } else if (!method.isAbstract()) {
        method(method);
      }
      if (!name.equals("<clinit>")
          && !name.equals("<init>")
          && !method.isPrivate()
          && !method.isStatic()
          && !Modifier.isFinal(method.getModifiers())
          && !Modifier.isFinal(sootClass.getModifiers())) {

        createLookupFunction(method);
      }
      if (method.isStatic()) {
        String fnName = mangleMethod(method);
        if (method.isSynchronized()) {
          fnName += "_synchronized";
        }
        FunctionRef fn = new FunctionRef(fnName, getFunctionType(method));
        mb.addFunction(createClassInitWrapperFunction(fn));
      }
    }

    Set<String> trampolineDependencies = new HashSet<String>();
    for (Trampoline trampoline : trampolines) {
      trampolineResolver.compile(mb, trampoline);
      trampolineDependencies.addAll(trampolineResolver.getDependencies());
    }

    Global classInfoStruct = null;
    StructureConstant classInfoErrorStruct = createClassInfoErrorStruct();
    if (classInfoErrorStruct != null) {
      // The class cannot be loaded at runtime. Replace the ClassInfo struct
      // with a ClassInfoError struct with details of why.
      classInfoStruct = new Global(mangleClass(sootClass) + "_info_struct", classInfoErrorStruct);
    } else {
      classInfoStruct =
          new Global(mangleClass(sootClass) + "_info_struct", createClassInfoStruct());
    }
    mb.addGlobal(classInfoStruct);

    Function infoFn = FunctionBuilder.infoStruct(sootClass);
    infoFn.add(new Ret(new ConstantBitcast(classInfoStruct.ref(), I8_PTR_PTR)));
    mb.addFunction(infoFn);

    out.write(mb.build().toString().getBytes("UTF-8"));

    clazz.clearDependencies();
    clazz.addDependency(
        "java/lang/Object"); // Make sure no class or interface has zero dependencies
    if (sootClass.hasSuperclass() && !sootClass.isInterface()) {
      clazz.addDependency(getInternalName(sootClass.getSuperclass()));
    }
    for (SootClass iface : sootClass.getInterfaces()) {
      clazz.addDependency(getInternalName(iface));
    }
    for (SootField f : sootClass.getFields()) {
      addDependencyIfNeeded(clazz, f.getType());
    }
    for (SootMethod m : sootClass.getMethods()) {
      addDependencyIfNeeded(clazz, m.getReturnType());
      @SuppressWarnings("unchecked")
      List<soot.Type> paramTypes = (List<soot.Type>) m.getParameterTypes();
      for (soot.Type type : paramTypes) {
        addDependencyIfNeeded(clazz, type);
      }
    }
    clazz.addDependencies(attributesEncoder.getDependencies());
    clazz.addDependencies(trampolineDependencies);
    clazz.addDependencies(catches);

    for (Trampoline t : trampolines) {
      if (!(t instanceof LdcString)) {
        String desc = t.getTarget();
        if (desc.charAt(0) == 'L' || desc.charAt(0) == '[') {
          // Target is a descriptor
          addDependencyIfNeeded(clazz, desc);
        } else {
          clazz.addDependency(t.getTarget());
        }
      }
      if (t instanceof FieldAccessor) {
        addDependencyIfNeeded(clazz, ((FieldAccessor) t).getFieldDesc());
      } else if (t instanceof Invoke) {
        String methodDesc = ((Invoke) t).getMethodDesc();
        addDependencyIfNeeded(clazz, getReturnTypeDescriptor(methodDesc));
        for (String desc : getParameterDescriptors(methodDesc)) {
          addDependencyIfNeeded(clazz, desc);
        }
      }
    }
    clazz.saveDependencies();
  }