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Scala example source code file (GenMSIL.scala)

This example Scala source code file (GenMSIL.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Scala tags/keywords

array, array, boolean, int, int, io, list, methodinfo, msiltype, nio, none, some, string, string, symbol, symbol

The Scala GenMSIL.scala source code

/* NSC -- new scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author Nikolay Mihaylov
 */


package scala.tools.nsc
package backend.msil

import java.io.{File, IOException}
import java.nio.{ByteBuffer, ByteOrder}

import scala.collection.mutable.{Map, HashMap, HashSet, Stack, ListBuffer}
import scala.tools.nsc.symtab._

import ch.epfl.lamp.compiler.msil.{Type => MsilType, _}
import ch.epfl.lamp.compiler.msil.emit._
import ch.epfl.lamp.compiler.msil.util.PECustomMod

abstract class GenMSIL extends SubComponent {
  import global._
  import loaders.clrTypes
  import clrTypes.{types, constructors, methods, fields}
  import icodes._
  import icodes.opcodes._

  /** Create a new phase */
  override def newPhase(p: Phase) = new MsilPhase(p)

  val phaseName = "msil"
  /** MSIL code generation phase
   */
  class MsilPhase(prev: Phase) extends GlobalPhase(prev) {
    def name = phaseName
    override def newFlags = phaseNewFlags

    override def erasedTypes = true

    override def run() {
      if (settings.debug.value) inform("[running phase " + name + " on icode]")

      val codeGenerator = new BytecodeGenerator

      //classes is ICodes.classes, a HashMap[Symbol, IClass]
      classes.values foreach codeGenerator.findEntryPoint
      if( opt.showClass.isDefined && (codeGenerator.entryPoint == null) ) { // TODO introduce dedicated setting instead
        val entryclass = opt.showClass.get.toString 
        warning("Couldn't find entry class " + entryclass)
      }

      codeGenerator.initAssembly

      val classesSorted = classes.values.toList.sortBy(c => c.symbol.id) // simplifies comparing cross-compiler vs. .exe output 
      classesSorted foreach codeGenerator.createTypeBuilder
      classesSorted foreach codeGenerator.createClassMembers

      try {
        classesSorted foreach codeGenerator.genClass
      } finally {
        codeGenerator.writeAssembly
      }
    }

    override def apply(unit: CompilationUnit) {
      abort("MSIL works on icode classes, not on compilation units!")
    }
  }

  /**
   * MSIL bytecode generator.
   *
   */
  class BytecodeGenerator {

    val MODULE_INSTANCE_NAME = "MODULE$"

    import clrTypes.{VOID => MVOID, BOOLEAN => MBOOL, BYTE => MBYTE, SHORT => MSHORT,
                   CHAR => MCHAR, INT => MINT, LONG => MLONG, FLOAT => MFLOAT,
                   DOUBLE => MDOUBLE, OBJECT => MOBJECT, STRING => MSTRING,
                   STRING_ARRAY => MSTRING_ARRAY,
                   SYMTAB_CONSTR => SYMTAB_ATTRIBUTE_CONSTRUCTOR,
                   SYMTAB_DEFAULT_CONSTR => SYMTAB_ATTRIBUTE_EMPTY_CONSTRUCTOR}

    val EXCEPTION = clrTypes.getType("System.Exception")
    val MBYTE_ARRAY = clrTypes.mkArrayType(MBYTE)

    val ICLONEABLE = clrTypes.getType("System.ICloneable")
    val MEMBERWISE_CLONE = MOBJECT.GetMethod("MemberwiseClone", MsilType.EmptyTypes)

    val MMONITOR       = clrTypes.getType("System.Threading.Monitor")
    val MMONITOR_ENTER = MMONITOR.GetMethod("Enter", Array(MOBJECT))
    val MMONITOR_EXIT  = MMONITOR.GetMethod("Exit", Array(MOBJECT))

    val MSTRING_BUILDER = clrTypes.getType("System.Text.StringBuilder")
    val MSTRING_BUILDER_CONSTR = MSTRING_BUILDER.GetConstructor(MsilType.EmptyTypes)
    val MSTRING_BUILDER_TOSTRING = MSTRING_BUILDER.GetMethod("ToString",
                                                             MsilType.EmptyTypes)

    val TYPE_FROM_HANDLE =
      clrTypes.getType("System.Type").GetMethod("GetTypeFromHandle", Array(clrTypes.getType("System.RuntimeTypeHandle")))

    val INT_PTR = clrTypes.getType("System.IntPtr")

    val JOBJECT = definitions.ObjectClass
    val JSTRING = definitions.StringClass

    val SystemConvert = clrTypes.getType("System.Convert")

    val objParam = Array(MOBJECT)

    val toBool:   MethodInfo = SystemConvert.GetMethod("ToBoolean", objParam) // see comment in emitUnbox 
    val toSByte:  MethodInfo = SystemConvert.GetMethod("ToSByte",   objParam)
    val toShort:  MethodInfo = SystemConvert.GetMethod("ToInt16",   objParam)
    val toChar:   MethodInfo = SystemConvert.GetMethod("ToChar",    objParam)
    val toInt:    MethodInfo = SystemConvert.GetMethod("ToInt32",   objParam)
    val toLong:   MethodInfo = SystemConvert.GetMethod("ToInt64",   objParam)
    val toFloat:  MethodInfo = SystemConvert.GetMethod("ToSingle",  objParam)
    val toDouble: MethodInfo = SystemConvert.GetMethod("ToDouble",  objParam)

    //val boxedUnit: FieldInfo = msilType(definitions.BoxedUnitModule.info).GetField("UNIT")
    val boxedUnit: FieldInfo = fields(definitions.BoxedUnit_UNIT)

    // Scala attributes
    // symtab.Definitions -> object (singleton..)
    val SerializableAttr = definitions.SerializableAttr.tpe
    val CloneableAttr    = definitions.getClass("scala.cloneable").tpe
    val TransientAtt     = definitions.getClass("scala.transient").tpe
    // remoting: the architectures are too different, no mapping (no portable code
    // possible)

    // java instance methods that are mapped to static methods in .net
    // these will need to be called with OpCodes.Call (not Callvirt)
    val dynToStatMapped: HashSet[Symbol] = new HashSet()

    initMappings()

    /** Create the mappings between java and .net classes and methods */
    private def initMappings() {
      mapType(definitions.AnyClass, MOBJECT)
      mapType(definitions.AnyRefClass, MOBJECT)
      //mapType(definitions.NullClass, clrTypes.getType("scala.AllRef$"))
      //mapType(definitions.NothingClass, clrTypes.getType("scala.All$"))
      // FIXME: for some reason the upper two lines map to null
      mapType(definitions.NullClass, EXCEPTION)
      mapType(definitions.NothingClass, EXCEPTION)

      mapType(definitions.BooleanClass, MBOOL)
      mapType(definitions.ByteClass, MBYTE)
      mapType(definitions.ShortClass, MSHORT)
      mapType(definitions.CharClass, MCHAR)
      mapType(definitions.IntClass, MINT)
      mapType(definitions.LongClass, MLONG)
      mapType(definitions.FloatClass, MFLOAT)
      mapType(definitions.DoubleClass, MDOUBLE)
    }

    var clasz: IClass = _
    var method: IMethod = _

    var massembly: AssemblyBuilder = _
    var mmodule: ModuleBuilder = _
    var mcode: ILGenerator = _

    var assemName: String = _
    var firstSourceName = ""
    var outDir: File = _
    var srcPath: File = _
    var moduleName: String = _

    def initAssembly() {

      assemName = settings.assemname.value

      if (assemName == "") {
        if (entryPoint != null) {
          assemName = msilName(entryPoint.enclClass)
          // remove the $ at the end (from module-name)
          assemName = assemName.substring(0, assemName.length() - 1)
        } else {
          // assuming filename of first source file
          assert(firstSourceName.endsWith(".scala"), firstSourceName)
          assemName = firstSourceName.substring(0, firstSourceName.length() - 6)
        }
      } else {
        if (assemName.endsWith(".msil"))
          assemName = assemName.substring(0, assemName.length()-5)
        if (assemName.endsWith(".il"))
          assemName = assemName.substring(0, assemName.length()-3)
        val f: File = new File(assemName)
        assemName = f.getName()
      }
      
      outDir = new File(settings.outdir.value)

      srcPath = new File(settings.sourcedir.value)

      val assemblyName = new AssemblyName()
      assemblyName.Name = assemName
      massembly = AssemblyBuilderFactory.DefineDynamicAssembly(assemblyName)

      moduleName = assemName // + (if (entryPoint == null) ".dll" else ".exe")
      // filename here: .dll or .exe (in both parameters), second: give absolute-path
      mmodule = massembly.DefineDynamicModule(moduleName,
                                              new File(outDir, moduleName).getAbsolutePath())
      assert (mmodule != null)
    }


    /**
     * Form of the custom Attribute parameter (Ecma-335.pdf)
     *      - p. 163 for CustomAttrib Form,
     *      - p. 164 for FixedArg Form (Array and Element) (if array or not is known!)
     *  !! least significant byte first if values longer than one byte !!
     *
     * 1: Prolog (unsigned int16, value 0x0001) -> symtab[0] = 0x01, symtab[1] = 0x00
     * 2: FixedArgs (directly the data, get number and types from related constructor)
     *  2.1: length of the array (unsigned int32, 4 bytes, least significant first)
     *  2.2: the byte array data
     * 3: NumNamed (unsigned int16, number of named fields and properties, 0x0000)
     */
    def addSymtabAttribute(sym: Symbol, tBuilder: TypeBuilder) {
      def addMarker() {
        val markerSymtab = new Array[Byte](4)
        markerSymtab(0) = 1.toByte
        tBuilder.SetCustomAttribute(SYMTAB_ATTRIBUTE_EMPTY_CONSTRUCTOR, markerSymtab)
      }

      // both conditions are needed (why exactly..?)
      if (tBuilder.Name.endsWith("$") || sym.isModuleClass) {
        addMarker()
      } else {
        currentRun.symData.get(sym) match {
          case Some(pickle) =>
            var size = pickle.writeIndex
            val symtab = new Array[Byte](size + 8)
            symtab(0) = 1.toByte
            for (i <- 2 until 6) {
              symtab(i) = (size & 0xff).toByte
              size = size >> 8
            }
            java.lang.System.arraycopy(pickle.bytes, 0, symtab, 6, pickle.writeIndex)

            tBuilder.SetCustomAttribute(SYMTAB_ATTRIBUTE_CONSTRUCTOR, symtab)

            currentRun.symData -= sym
            currentRun.symData -= sym.companionSymbol

          case _ =>
            addMarker()
        }
      }
    }

    /**
     * Mutates `member` adding CLR attributes (if any) based on sym.annotations. 
     * Please notice that CLR custom modifiers are a different beast (see customModifiers below) 
     * and thus shouldn't be added by this method.   
     */
    def addAttributes(member: ICustomAttributeSetter, annotations: List[AnnotationInfo]) {
      val attributes = annotations.map(_.atp.typeSymbol).collect {
        case definitions.TransientAttr => null // TODO this is just an example 
      }
      return // TODO: implement at some point
    }

    /**
     * What's a CLR custom modifier? Intro available as source comments in compiler.msil.CustomModifier.
     * It's basically a marker associated with a location (think of FieldInfo, ParameterInfo, and PropertyInfo) 
     * and thus that marker (be it optional or required) becomes part of the signature of that location. 
     * Some annotations will become CLR attributes (see addAttributes above), others custom modifiers (this method).   
     */
    def customModifiers(annotations: List[AnnotationInfo]): Array[CustomModifier] = {
      annotations.map(_.atp.typeSymbol).collect {
        case definitions.VolatileAttr  => new CustomModifier(true, CustomModifier.VolatileMarker) 
      } toArray
    }
      
    
    
    /*
      if (settings.debug.value)
        log("creating annotations: " + annotations + " for member : " + member)
      for (annot@ AnnotationInfo(typ, annArgs, nvPairs) <- annotations ;
           if annot.isConstant)
           //!typ.typeSymbol.isJavaDefined
      {
//        assert(consts.length <= 1,
//               "too many constant arguments for annotations; "+consts.toString())

        // Problem / TODO having the symbol of the annotations type would be nicer
        // (i hope that type.typeSymbol is the same as the one in types2create)
        // AND: this will crash if the annotations Type is already compiled (-> not a typeBuilder)
        // when this is solved, types2create will be the same as icodes.classes, thus superfluous
        val annType: TypeBuilder = getType(typ.typeSymbol).asInstanceOf[TypeBuilder]
//        val annType: MsilType = getType(typ.typeSymbol)

        // Problem / TODO: i have no idea which constructor is used. This
        // information should be available in AnnotationInfo.
        annType.CreateType() // else, GetConstructors can't be used
        val constr: ConstructorInfo = annType.GetConstructors()(0)
        // prevent a second call of CreateType, only needed because there's no
        // other way than GetConstructors()(0) to get the constructor, if there's
        // no constructor symbol available.

        val args: Array[Byte] =
          getAttributeArgs(
            annArgs map (_.constant.get),
            (for((n,v) <- nvPairs) yield (n, v.constant.get)))
        member.SetCustomAttribute(constr, args)
      }
    } */

/*    def getAttributeArgs(consts: List[Constant], nvPairs: List[(Name, Constant)]): Array[Byte] = {
      val buf = ByteBuffer.allocate(2048) // FIXME: this may be not enough!
      buf.order(ByteOrder.LITTLE_ENDIAN)
      buf.putShort(1.toShort) // signature

      def emitSerString(str: String) = {
          // this is wrong, it has to be the length of the UTF-8 byte array, which
          // may be longer (see clr-book on page 302)
//          val length: Int = str.length
            val strBytes: Array[Byte] = try {
              str.getBytes("UTF-8")
            } catch {
              case _: Error => abort("could not get byte-array for string: " + str)
            }
            val length: Int = strBytes.length //this length is stored big-endian
            if (length < 128)
              buf.put(length.toByte)
            else if (length < (1<<14)) {
              buf.put(((length >> 8) | 0x80).toByte) // the bits 14 and 15 of length are '0'
              buf.put((length | 0xff).toByte)
            } else if (length < (1 << 29)) {
              buf.put(((length >> 24) | 0xc0).toByte)
              buf.put(((length >> 16) & 0xff).toByte)
              buf.put(((length >>  8) & 0xff).toByte)
              buf.put(((length      ) & 0xff).toByte)
            } else
              abort("string too long for attribute parameter: " + length)
            buf.put(strBytes)
      }

      def emitConst(const: Constant): Unit = const.tag match {
        case BooleanTag => buf.put((if (const.booleanValue) 1 else 0).toByte)
        case ByteTag => buf.put(const.byteValue)
        case ShortTag => buf.putShort(const.shortValue)
        case CharTag => buf.putChar(const.charValue)
        case IntTag => buf.putInt(const.intValue)
        case LongTag => buf.putLong(const.longValue)
        case FloatTag => buf.putFloat(const.floatValue)
        case DoubleTag => buf.putDouble(const.doubleValue)
        case StringTag =>
          val str: String = const.stringValue
          if (str == null) {
            buf.put(0xff.toByte)
          } else {
            emitSerString(str)
          }
        case ArrayTag =>
          val arr: Array[Constant] = const.arrayValue
          if (arr == null) {
            buf.putInt(0xffffffff)
          } else {
            buf.putInt(arr.length)
            arr.foreach(emitConst)
          }

        // TODO: other Tags: NoTag, UnitTag, ClassTag, EnumTag, ArrayTag ???

        case _ => abort("could not handle attribute argument: " + const)
      }

      consts foreach emitConst
      buf.putShort(nvPairs.length.toShort)
      def emitNamedArg(nvPair: (Name, Constant)) {
        // the named argument is a property of the attribute (it can't be a field, since
        //  all fields in scala are private)
        buf.put(0x54.toByte)

        def emitType(c: Constant) = c.tag match { // type of the constant, Ecma-335.pdf, page 151
          case BooleanTag => buf.put(0x02.toByte)
          case ByteTag =>    buf.put(0x05.toByte)
          case ShortTag =>   buf.put(0x06.toByte)
          case CharTag =>    buf.put(0x07.toByte)
          case IntTag =>     buf.put(0x08.toByte)
          case LongTag =>    buf.put(0x0a.toByte)
          case FloatTag =>   buf.put(0x0c.toByte)
          case DoubleTag =>  buf.put(0x0d.toByte)
          case StringTag =>  buf.put(0x0e.toByte)

          // TODO: other Tags: NoTag, UnitTag, ClassTag, EnumTag ???

          // ArrayTag falls in here
          case _ => abort("could not handle attribute argument: " + c)
        }

        val cnst: Constant = nvPair._2
        if (cnst.tag == ArrayTag) {
          buf.put(0x1d.toByte)
          emitType(cnst.arrayValue(0)) // FIXME: will crash if array length = 0
        } else if (cnst.tag == EnumTag) {
          buf.put(0x55.toByte)
          // TODO: put a SerString (don't know what exactly, names of the enums somehow..)
              } else {
          buf.put(0x51.toByte)
          emitType(cnst)
        }

        emitSerString(nvPair._1.toString)
        emitConst(nvPair._2)
      }

      val length = buf.position()
      buf.array().slice(0, length)
    } */

    def writeAssembly() {
      if (entryPoint != null) {
        assert(entryPoint.enclClass.isModuleClass, entryPoint.enclClass)
        val mainMethod = methods(entryPoint)
        val stringArrayTypes: Array[MsilType] = Array(MSTRING_ARRAY)
        val globalMain = mmodule.DefineGlobalMethod(
          "Main", MethodAttributes.Public | MethodAttributes.Static,
          MVOID, stringArrayTypes)
        globalMain.DefineParameter(0, ParameterAttributes.None, "args")
        massembly.SetEntryPoint(globalMain)
        val code = globalMain.GetILGenerator()
        val moduleField = getModuleInstanceField(entryPoint.enclClass)
        code.Emit(OpCodes.Ldsfld, moduleField)
        code.Emit(OpCodes.Ldarg_0)
        code.Emit(OpCodes.Callvirt, mainMethod)
        code.Emit(OpCodes.Ret)
      }
      createTypes()
      var outDirName: String = null
      try {
        if (settings.Ygenjavap.isDefault) { // we reuse the JVM-sounding setting because it's conceptually similar
          outDirName = outDir.getPath()
          massembly.Save(outDirName + "\\" + assemName + ".msil") /* use SingleFileILPrinterVisitor */
        } else {
          outDirName = srcPath.getPath()
          massembly.Save(settings.Ygenjavap.value, outDirName)  /* use MultipleFilesILPrinterVisitor */
        }
      } catch {
        case e:IOException => abort("Could not write to " + outDirName + ": " + e.getMessage())
      }
    }

    private def createTypes() {
      for (sym <- classes.keys) {
        val iclass   = classes(sym)
        val tBuilder = types(sym).asInstanceOf[TypeBuilder]
          
        if (settings.debug.value)
          log("Calling CreatType for " + sym + ", " + tBuilder.toString)

        tBuilder.CreateType()
        tBuilder.setSourceFilepath(iclass.cunit.source.file.path)
      }
    }

    private[GenMSIL] def ilasmFileName(iclass: IClass) : String = {
      // method.sourceFile contains just the filename
      iclass.cunit.source.file.toString.replace("\\", "\\\\")
    }

    private[GenMSIL] def genClass(iclass: IClass) {
      val sym = iclass.symbol
      if (settings.debug.value)
        log("Generating class " + sym + " flags: " + Flags.flagsToString(sym.flags))
      clasz = iclass

      val tBuilder = getType(sym).asInstanceOf[TypeBuilder]
      if (isCloneable(sym)) {
        // FIXME: why there's no nme.clone_ ?
        // "Clone": if the code is non-portable, "Clone" is defined, not "clone"
        // TODO: improve condition (should override AnyRef.clone)
        if (iclass.methods.forall(m => {
          !((m.symbol.name.toString() != "clone" || m.symbol.name.toString() != "Clone") &&
            m.symbol.tpe.paramTypes.length != 0)
        })) {
          if (settings.debug.value)
            log("auto-generating cloneable method for " + sym)
          val attrs: Short = (MethodAttributes.Public | MethodAttributes.Virtual |
                              MethodAttributes.HideBySig).toShort
          val cloneMethod = tBuilder.DefineMethod("Clone", attrs, MOBJECT,
                                                  MsilType.EmptyTypes)
          val clCode = cloneMethod.GetILGenerator()
          clCode.Emit(OpCodes.Ldarg_0)
          clCode.Emit(OpCodes.Call, MEMBERWISE_CLONE)
          clCode.Emit(OpCodes.Ret)
        }
      }

      val line = sym.pos.line
      tBuilder.setPosition(line, ilasmFileName(iclass))

      if (isTopLevelModule(sym)) {
        if (sym.companionClass == NoSymbol)
          dumpMirrorClass(sym)
        else
          log("No mirror class for module with linked class: " +
              sym.fullName)
      }

      addSymtabAttribute(sym, tBuilder)
      addAttributes(tBuilder, sym.annotations)

      if (iclass.symbol != definitions.ArrayClass)
        iclass.methods foreach genMethod

    } //genClass


    private def genMethod(m: IMethod) {
      if (settings.debug.value)
        log("Generating method " + m.symbol + " flags: " + Flags.flagsToString(m.symbol.flags) +
            " owner: " + m.symbol.owner)
      method = m
      localBuilders.clear
      computeLocalVarsIndex(m)

      if (m.symbol.isClassConstructor) {
        mcode = constructors(m.symbol).asInstanceOf[ConstructorBuilder].GetILGenerator()
      } else {
        val mBuilder = methods(m.symbol).asInstanceOf[MethodBuilder]
        if (!mBuilder.IsAbstract())
          try {
            mcode = mBuilder.GetILGenerator()
          } catch {
            case e: Exception =>
              java.lang.System.out.println("m.symbol       = " + Flags.flagsToString(m.symbol.flags) + " " + m.symbol)
              java.lang.System.out.println("m.symbol.owner = " + Flags.flagsToString(m.symbol.owner.flags) + " " + m.symbol.owner)
              java.lang.System.out.println("mBuilder       = " + mBuilder)
              java.lang.System.out.println("mBuilder.DeclaringType = " +
                                 TypeAttributes.toString(mBuilder.DeclaringType.Attributes) +
                                 "::" + mBuilder.DeclaringType)
              throw e
          }
          else
            mcode = null
      }

      if (mcode != null) {
        for (local <- m.locals ; if !(m.params contains local)) {
          if (settings.debug.value)
            log("add local var: " + local + ", of kind " + local.kind)
          val t: MsilType = msilType(local.kind)
          val localBuilder = mcode.DeclareLocal(t)
          localBuilder.SetLocalSymInfo(msilName(local.sym))
          localBuilders(local) = localBuilder
        }
        genCode(m)
      }

    }

    /** Special linearizer for methods with at least one exception handler. This
     *  linearizer brings all basic blocks in the right order so that nested
     *  try-catch and try-finally blocks can be emitted.
     */
    val msilLinearizer = new MSILLinearizer()

    val labels: HashMap[BasicBlock, Label] = new HashMap()

    /* when emitting .line, it's enough to include the full filename just once per method, thus reducing filesize. 
     * this scheme relies on the fact that the entry block is emitted first. */
    var dbFilenameSeen = false  

    def genCode(m: IMethod) {

      def makeLabels(blocks: List[BasicBlock]) = {
        if (settings.debug.value)
          log("Making labels for: " + method)
        for (bb <- blocks) labels(bb) = mcode.DefineLabel()
      }

      labels.clear

      var linearization = if(!m.exh.isEmpty) msilLinearizer.linearize(m)
                          else linearizer.linearize(m)

      if (!m.exh.isEmpty)
        linearization = computeExceptionMaps(linearization, m)

      makeLabels(linearization)

      // debug val blocksInM = m.code.blocks.toList.sortBy(bb => bb.label)
      // debug val blocksInL = linearization.sortBy(bb => bb.label)
      // debug val MButNotL  = (blocksInM.toSet) diff (blocksInL.toSet) // if non-empty, a jump to B fails to find a label for B (case CJUMP, case CZJUMP)
      // debug if(!MButNotL.isEmpty) { }

      dbFilenameSeen = false
      genBlocks(linearization)

      // RETURN inside exception blocks are replaced by Leave. The target of the
      // leave is a `Ret` outside any exception block (generated here).
      if (handlerReturnMethod == m) {
        mcode.MarkLabel(handlerReturnLabel)
        if (handlerReturnKind != UNIT)
          mcode.Emit(OpCodes.Ldloc, handlerReturnLocal)
        mcode.Emit(OpCodes.Ret)
      }

      beginExBlock.clear()
      beginCatchBlock.clear()
      endExBlock.clear()
      endFinallyLabels.clear()
    }

    def genBlocks(blocks: List[BasicBlock], previous: BasicBlock = null) {
      blocks match {
        case Nil => ()
        case x :: Nil => genBlock(x, prev = previous, next = null)
        case x :: y :: ys => genBlock(x, prev = previous, next = y); genBlocks(y :: ys, previous = x)
      }
    }

    // the try blocks starting at a certain BasicBlock
    val beginExBlock = new HashMap[BasicBlock, List[ExceptionHandler]]()

    // the catch blocks starting / endling at a certain BasicBlock
    val beginCatchBlock = new HashMap[BasicBlock, ExceptionHandler]()
    val endExBlock = new HashMap[BasicBlock, List[ExceptionHandler]]()

    /** When emitting the code (genBlock), the number of currently active try / catch
     *  blocks. When seeing a `RETURN' inside a try / catch, we need to
     *   - store the result in a local (if it's not UNIT)
     *   - emit `Leave handlerReturnLabel` instead of the Return
     *   - emit code at the end: load the local and return its value
     */
    var currentHandlers = new Stack[ExceptionHandler]
    // The IMethod the Local/Label/Kind below belong to
    var handlerReturnMethod: IMethod = _
    // Stores the result when returning inside an exception block
    var handlerReturnLocal: LocalBuilder = _
    // Label for a return instruction outside any exception block
    var handlerReturnLabel: Label = _
    // The result kind.
    var handlerReturnKind: TypeKind = _
    def returnFromHandler(kind: TypeKind): (LocalBuilder, Label) = {
      if (handlerReturnMethod != method) {
        handlerReturnMethod = method
        if (kind != UNIT) {
          handlerReturnLocal = mcode.DeclareLocal(msilType(kind))
          handlerReturnLocal.SetLocalSymInfo("$handlerReturn")
        }
        handlerReturnLabel = mcode.DefineLabel()
        handlerReturnKind = kind
      }
      (handlerReturnLocal, handlerReturnLabel)
    }

    /** For try/catch nested inside a finally, we can't use `Leave OutsideFinally`, the
     *  Leave target has to be inside the finally (and it has to be the `endfinally` instruction).
     *  So for every finalizer, we have a label which marks the place of the `endfinally`,
     *  nested try/catch blocks will leave there.
     */
    val endFinallyLabels = new HashMap[ExceptionHandler, Label]()

    /** Computes which blocks are the beginning / end of a try or catch block */
    private def computeExceptionMaps(blocks: List[BasicBlock], m: IMethod): List[BasicBlock] = {
      val visitedBlocks = new HashSet[BasicBlock]()

      // handlers which have not been introduced so far
      var openHandlers = m.exh


      /** Example
       *   try {
       *     try {
       *         // *1*
       *     } catch {
       *       case h1 =>
       *     }
       *   } catch {
       *     case h2 =>
       *     case h3 =>
       *       try {
       *
       *       } catch {
       *         case h4 =>  // *2*
       *         case h5 =>
       *       }
       *   }
       */

      // Stack of nested try blocks. Each bloc has a List of ExceptionHandler (multiple
      // catch statements). Example *1*: Stack(List(h2, h3), List(h1))
      val currentTryHandlers = new Stack[List[ExceptionHandler]]()

      // Stack of nested catch blocks. The head of the list is the current catch block. The
      // tail is all following catch blocks. Example *2*: Stack(List(h3), List(h4, h5))
      val currentCatchHandlers = new Stack[List[ExceptionHandler]]()

      for (b <- blocks) {

        // are we past the current catch blocks?
        def endHandlers(): List[ExceptionHandler] = {
          var res: List[ExceptionHandler] = Nil
          if (!currentCatchHandlers.isEmpty) {
            val handler = currentCatchHandlers.top.head
            if (!handler.blocks.contains(b)) {
              // all blocks of the handler are either visited, or not part of the linearization (i.e. dead)
              assert(handler.blocks.forall(b => visitedBlocks.contains(b) || !blocks.contains(b)),
                     "Bad linearization of basic blocks inside catch. Found block not part of the handler\n"+
                     b.fullString +"\nwhile in catch-part of\n"+ handler)

              val rest = currentCatchHandlers.pop.tail
              if (rest.isEmpty) {
                // all catch blocks of that exception handler are covered
                res = handler :: endHandlers()
              } else {
                // there are more catch blocks for that try (handlers covering the same)
                currentCatchHandlers.push(rest)
                beginCatchBlock(b) = rest.head
              }
            }
          }
          res
        }
        val end = endHandlers()
        if (!end.isEmpty) endExBlock(b) = end

        // are we past the current try block?
        if (!currentTryHandlers.isEmpty) {
          val handler = currentTryHandlers.top.head
          if (!handler.covers(b)) {
            // all of the covered blocks are visited, or not part of the linearization
            assert(handler.covered.forall(b => visitedBlocks.contains(b) || !blocks.contains(b)),
                   "Bad linearization of basic blocks inside try. Found non-covered block\n"+
                   b.fullString +"\nwhile in try-part of\n"+ handler)

            assert(handler.startBlock == b,
                   "Bad linearization of basic blocks. The entry block of a catch does not directly follow the try\n"+
                   b.fullString +"\n"+ handler)

            val handlers = currentTryHandlers.pop
            currentCatchHandlers.push(handlers)
            beginCatchBlock(b) = handler
          }
        }

        // are there try blocks starting at b?
        val (newHandlers, stillOpen) = openHandlers.partition(_.covers(b))
        openHandlers = stillOpen

        val newHandlersBySize = newHandlers.groupBy(_.covered.size)
        // big handlers first, smaller ones are nested inside the try of the big one
        // (checked by the assertions below)
        val sizes = newHandlersBySize.keys.toList.sortWith(_ > _)

        val beginHandlers = new ListBuffer[ExceptionHandler]
        for (s <- sizes) {
          val sHandlers = newHandlersBySize(s)
          for (h <- sHandlers) {
            assert(h.covered == sHandlers.head.covered,
                   "bad nesting of exception handlers. same size, but not covering same blocks\n"+
                   h +"\n"+ sHandlers.head)
            assert(h.resultKind == sHandlers.head.resultKind,
                   "bad nesting of exception handlers. same size, but the same resultKind\n"+
                   h +"\n"+ sHandlers.head)
          }
          for (bigger <- beginHandlers; h <- sHandlers) {
            assert(h.covered.subsetOf(bigger.covered),
                   "bad nesting of exception handlers. try blocks of smaller handler are not nested in bigger one.\n"+
                   h +"\n"+ bigger)
            assert(h.blocks.toSet.subsetOf(bigger.covered),
                   "bad nesting of exception handlers. catch blocks of smaller handler are not nested in bigger one.\n"+
                   h +"\n"+ bigger)
          }
          beginHandlers += sHandlers.head
          currentTryHandlers.push(sHandlers)
        }
        beginExBlock(b) = beginHandlers.toList
        visitedBlocks += b
      }

      // if there handlers left (i.e. handlers covering nothing, or a
      // non-existent (dead) block), remove their catch-blocks.
      val liveBlocks = if (openHandlers.isEmpty) blocks else {
        blocks.filter(b => openHandlers.forall(h => !h.blocks.contains(b)))
      }

      /** There might be open handlers, but no more blocks. happens when try/catch end
       *  with `throw` or `return`
       *     def foo() { try { .. throw } catch { _ => .. throw } }
       *
       *  In this case we need some code after the catch block for the auto-generated
       *  `leave` instruction. So we're adding a (dead) `throw new Exception`.
       */
      val rest = currentCatchHandlers.map(handlers => {
        assert(handlers.length == 1, handlers)
        handlers.head
      }).toList

      if (rest.isEmpty) {
        liveBlocks
      } else {
        val b = m.code.newBlock
        b.emit(Seq(
          NEW(REFERENCE(definitions.ThrowableClass)),
          DUP(REFERENCE(definitions.ObjectClass)),
          CALL_METHOD(definitions.ThrowableClass.primaryConstructor, Static(true)),
          THROW(definitions.ThrowableClass)
        ))
        b.close
        endExBlock(b) = rest
        liveBlocks ::: List(b)
      }
    }

    /**
     *  @param block the BasicBlock to emit code for
     *  @param next  the following BasicBlock, `null` if `block` is the last one
     */
    def genBlock(block: BasicBlock, prev: BasicBlock, next: BasicBlock) {

      def loadLocalOrAddress(local: Local, msg : String , loadAddr : Boolean) {
        if (settings.debug.value)
          log(msg + " for " + local)
        val isArg = local.arg
        val i = local.index
        if (isArg)
          loadArg(mcode, loadAddr)(i)
        else
          loadLocal(i, local, mcode, loadAddr)
      }

      def loadFieldOrAddress(field: Symbol, isStatic: Boolean, msg: String, loadAddr : Boolean) {
        if (settings.debug.value)
          log(msg + " with owner: " + field.owner +
              " flags: " + Flags.flagsToString(field.owner.flags))
        var fieldInfo = fields.get(field) match {
          case Some(fInfo) => fInfo
          case None =>
            val fInfo = getType(field.owner).GetField(msilName(field))
            fields(field) = fInfo
            fInfo
        }
        if (fieldInfo.IsVolatile) {
          mcode.Emit(OpCodes.Volatile)
        }
        if (!fieldInfo.IsLiteral) {
          if (loadAddr) {
            mcode.Emit(if (isStatic) OpCodes.Ldsflda else OpCodes.Ldflda, fieldInfo)
          } else {
            mcode.Emit(if (isStatic) OpCodes.Ldsfld else OpCodes.Ldfld, fieldInfo)
          }
        } else {
          assert(!loadAddr, "can't take AddressOf a literal field (not even with readonly. prefix) because no memory was allocated to such field ...")
          // TODO the above can be overcome by loading the value, boxing, and finally unboxing. An address to a copy of the raw value will be on the stack.
         /*  We perform `field inlining' as required by CLR.
          *  Emit as for a CONSTANT ICode stmt, with the twist that the constant value is available
          *  as a java.lang.Object and its .NET type allows constant initialization in CLR, i.e. that type
          *  is one of I1, I2, I4, I8, R4, R8, CHAR, BOOLEAN, STRING, or CLASS (in this last case,
          *  only accepting nullref as value). See Table 9-1 in Lidin's book on ILAsm. */
          val value = fieldInfo.getValue()
          if (value == null) {
            mcode.Emit(OpCodes.Ldnull)
          } else {
            val typ = if (fieldInfo.FieldType.IsEnum) fieldInfo.FieldType.getUnderlyingType
                      else fieldInfo.FieldType
            if (typ == clrTypes.STRING) {
              mcode.Emit(OpCodes.Ldstr, value.asInstanceOf[String])
            } else if (typ == clrTypes.BOOLEAN) {
                mcode.Emit(if (value.asInstanceOf[Boolean]) OpCodes.Ldc_I4_1
                           else OpCodes.Ldc_I4_0)
            } else if (typ == clrTypes.BYTE || typ == clrTypes.UBYTE) {
              loadI4(value.asInstanceOf[Byte], mcode)
            } else if (typ == clrTypes.SHORT || typ == clrTypes.USHORT) {
              loadI4(value.asInstanceOf[Int], mcode)
            } else if (typ == clrTypes.CHAR) {
              loadI4(value.asInstanceOf[Char], mcode)
            } else if (typ == clrTypes.INT || typ == clrTypes.UINT) {
              loadI4(value.asInstanceOf[Int], mcode)
            } else if (typ == clrTypes.LONG || typ == clrTypes.ULONG) {
              mcode.Emit(OpCodes.Ldc_I8, value.asInstanceOf[Long])
            } else if (typ == clrTypes.FLOAT) {
              mcode.Emit(OpCodes.Ldc_R4, value.asInstanceOf[Float])
            } else if (typ == clrTypes.DOUBLE) {
              mcode.Emit(OpCodes.Ldc_R8, value.asInstanceOf[Double])
            } else {
              /* TODO one more case is described in Partition II, 16.2: bytearray(...) */
              abort("Unknown type for static literal field: " + fieldInfo)
            }
          }
        }
      }

      /** Creating objects works differently on .NET. On the JVM
       *  - NEW(type) => reference on Stack
       *  - DUP, load arguments, CALL_METHOD(constructor)
       *
       * On .NET, the NEW and DUP are ignored, but we emit a special method call
       *  - load arguments
       *  - NewObj(constructor) => reference on stack
       *
       * This variable tells whether the previous instruction was a NEW,
       * we expect a DUP which is not emitted. */
      var previousWasNEW = false

      var lastLineNr: Int = 0
      var lastPos: Position = NoPosition


      // EndExceptionBlock must happen before MarkLabel because it adds the
      // Leave instruction. Otherwise, labels(block) points to the Leave
      // (inside the catch) instead of the instruction afterwards.
      for (handlers <- endExBlock.get(block); exh <- handlers) {
        currentHandlers.pop()
        for (l <- endFinallyLabels.get(exh))
          mcode.MarkLabel(l)
        mcode.EndExceptionBlock()
      }

      mcode.MarkLabel(labels(block))
      if (settings.debug.value)
        log("Generating code for block: " + block)

      for (handler <- beginCatchBlock.get(block)) {
        if (!currentHandlers.isEmpty && currentHandlers.top.covered == handler.covered) {
          currentHandlers.pop()
          currentHandlers.push(handler)
        }
        if (handler.cls == NoSymbol) {
          // `finally` blocks are represented the same as `catch`, but with no catch-type
          mcode.BeginFinallyBlock()
        } else {
          val t = getType(handler.cls)
          mcode.BeginCatchBlock(t)
        }
      }
      for (handlers <- beginExBlock.get(block); exh <- handlers) {
        currentHandlers.push(exh)
        mcode.BeginExceptionBlock()
      }

      for (instr <- block) {
        try {
          val currentLineNr = instr.pos.line
          val skip = if(instr.pos.isRange) instr.pos.sameRange(lastPos) else (currentLineNr == lastLineNr);  
          if(!skip || !dbFilenameSeen) {
            val fileName = if(dbFilenameSeen) "" else {dbFilenameSeen = true; ilasmFileName(clasz)}; 
            if(instr.pos.isRange) {
              val startLine = instr.pos.focusStart.line
              val endLine   = instr.pos.focusEnd.line
              val startCol  = instr.pos.focusStart.column 
              val endCol    = instr.pos.focusEnd.column
              mcode.setPosition(startLine, endLine, startCol, endCol, fileName) 
            } else {
              mcode.setPosition(instr.pos.line, fileName) 
            }
            lastLineNr = currentLineNr 
            lastPos = instr.pos
          }
        } catch { case _: UnsupportedOperationException => () }

        if (previousWasNEW)
          assert(instr.isInstanceOf[DUP], block)

        instr match {
          case THIS(clasz) =>
            mcode.Emit(OpCodes.Ldarg_0)

          case CONSTANT(const) =>
            const.tag match {
              case UnitTag    => ()
              case BooleanTag => mcode.Emit(if (const.booleanValue) OpCodes.Ldc_I4_1
                                            else OpCodes.Ldc_I4_0)
              case ByteTag    => loadI4(const.byteValue, mcode)
              case ShortTag   => loadI4(const.shortValue, mcode)
              case CharTag    => loadI4(const.charValue, mcode)
              case IntTag     => loadI4(const.intValue, mcode)
              case LongTag    => mcode.Emit(OpCodes.Ldc_I8, const.longValue)
              case FloatTag   => mcode.Emit(OpCodes.Ldc_R4, const.floatValue)
              case DoubleTag  => mcode.Emit(OpCodes.Ldc_R8, const.doubleValue)
              case StringTag  => mcode.Emit(OpCodes.Ldstr, const.stringValue)
              case NullTag    => mcode.Emit(OpCodes.Ldnull)
              case ClassTag   =>
                mcode.Emit(OpCodes.Ldtoken, msilType(const.typeValue))
                mcode.Emit(OpCodes.Call, TYPE_FROM_HANDLE)
              case _          => abort("Unknown constant value: " + const)
            }

          case LOAD_ARRAY_ITEM(kind) =>
            (kind: @unchecked) match {
              case BOOL           => mcode.Emit(OpCodes.Ldelem_I1)
              case BYTE           => mcode.Emit(OpCodes.Ldelem_I1) // I1 for System.SByte, i.e. a scala.Byte 
              case SHORT          => mcode.Emit(OpCodes.Ldelem_I2)
              case CHAR           => mcode.Emit(OpCodes.Ldelem_U2)
              case INT            => mcode.Emit(OpCodes.Ldelem_I4)
              case LONG           => mcode.Emit(OpCodes.Ldelem_I8)
              case FLOAT          => mcode.Emit(OpCodes.Ldelem_R4)
              case DOUBLE         => mcode.Emit(OpCodes.Ldelem_R8)
              case REFERENCE(cls) => mcode.Emit(OpCodes.Ldelem_Ref)
              case ARRAY(elem)    => mcode.Emit(OpCodes.Ldelem_Ref)

              // case UNIT is not possible: an Array[Unit] will be an
              //  Array[scala.runtime.BoxedUnit] (-> case REFERENCE)
            }

          case LOAD_LOCAL(local) => loadLocalOrAddress(local, "load_local", false)

          case CIL_LOAD_LOCAL_ADDRESS(local) => loadLocalOrAddress(local, "cil_load_local_address", true)

          case LOAD_FIELD(field, isStatic) => loadFieldOrAddress(field, isStatic, "load_field", false)

          case CIL_LOAD_FIELD_ADDRESS(field, isStatic) => loadFieldOrAddress(field, isStatic, "cil_load_field_address", true)

          case CIL_LOAD_ARRAY_ITEM_ADDRESS(kind) => mcode.Emit(OpCodes.Ldelema, msilType(kind))

          case CIL_NEWOBJ(msym) =>
            assert(msym.isClassConstructor)
            val constructorInfo: ConstructorInfo = getConstructor(msym)
            mcode.Emit(OpCodes.Newobj, constructorInfo)

          case LOAD_MODULE(module) =>
            if (settings.debug.value)
              log("Generating LOAD_MODULE for: " + showsym(module))
            mcode.Emit(OpCodes.Ldsfld, getModuleInstanceField(module))

          case STORE_ARRAY_ITEM(kind) =>
            (kind: @unchecked) match {
              case BOOL           => mcode.Emit(OpCodes.Stelem_I1)
              case BYTE           => mcode.Emit(OpCodes.Stelem_I1)
              case SHORT          => mcode.Emit(OpCodes.Stelem_I2)
              case CHAR           => mcode.Emit(OpCodes.Stelem_I2)
              case INT            => mcode.Emit(OpCodes.Stelem_I4)
              case LONG           => mcode.Emit(OpCodes.Stelem_I8)
              case FLOAT          => mcode.Emit(OpCodes.Stelem_R4)
              case DOUBLE         => mcode.Emit(OpCodes.Stelem_R8)
              case REFERENCE(cls) => mcode.Emit(OpCodes.Stelem_Ref)
              case ARRAY(elem)    => mcode.Emit(OpCodes.Stelem_Ref) // @TODO: test this! (occurs when calling a Array[Object]* vararg param method)

              // case UNIT not possible (see comment at LOAD_ARRAY_ITEM)
            }

          case STORE_LOCAL(local) =>
            val isArg = local.arg
            val i = local.index
            if (settings.debug.value)
              log("store_local for " + local + ", index " + i)

            // there are some locals defined by the compiler that
            // are isArg and are need to be stored.
            if (isArg) {
              if (i >= -128 && i <= 127)
                mcode.Emit(OpCodes.Starg_S, i)
              else
                mcode.Emit(OpCodes.Starg, i)
            } else {
              i match {
                case 0 => mcode.Emit(OpCodes.Stloc_0)
                case 1 => mcode.Emit(OpCodes.Stloc_1)
                case 2 => mcode.Emit(OpCodes.Stloc_2)
                case 3 => mcode.Emit(OpCodes.Stloc_3)
                case _      =>
                  if (i >= -128 && i <= 127)
                    mcode.Emit(OpCodes.Stloc_S, localBuilders(local))
                  else
                    mcode.Emit(OpCodes.Stloc, localBuilders(local))
              }
            }

          case STORE_THIS(_) =>
            // this only works for impl classes because the self parameter comes first
            // in the method signature. If that changes, this code has to be revisited.
            mcode.Emit(OpCodes.Starg_S, 0)

          case STORE_FIELD(field, isStatic) =>
            val fieldInfo = fields.get(field) match {
              case Some(fInfo) => fInfo
              case None =>
                val fInfo = getType(field.owner).GetField(msilName(field))
                fields(field) = fInfo
                fInfo
            }
            mcode.Emit(if (isStatic) OpCodes.Stsfld else OpCodes.Stfld, fieldInfo)

          case CALL_PRIMITIVE(primitive) =>
            genPrimitive(primitive, instr.pos)

          case CALL_METHOD(msym, style) =>
            if (msym.isClassConstructor) {
              val constructorInfo: ConstructorInfo = getConstructor(msym)
              (style: @unchecked) match {
                // normal constructor calls are Static..
                case Static(_) =>
                  if (method.symbol.isClassConstructor && method.symbol.owner == msym.owner)
                    // we're generating a constructor (method: IMethod is a constructor), and we're
                    // calling another constructor of the same class.

                    // @LUC TODO: this can probably break, namely when having: class A { def this() { new A() } }
                    // instead, we should instruct the CALL_METHOD with additional information, know whether it's
                    // an instance creation constructor call or not.
                    mcode.Emit(OpCodes.Call, constructorInfo)
                  else
                    mcode.Emit(OpCodes.Newobj, constructorInfo)
                case SuperCall(_) =>
                  mcode.Emit(OpCodes.Call, constructorInfo)
                  if (isStaticModule(clasz.symbol) &&
                      notInitializedModules.contains(clasz.symbol) &&
                      method.symbol.isClassConstructor)
                    {
                      notInitializedModules -= clasz.symbol
                      mcode.Emit(OpCodes.Ldarg_0)
                      mcode.Emit(OpCodes.Stsfld, getModuleInstanceField(clasz.symbol))
                    }
              }

            } else {
              
              var doEmit = true
              getTypeOpt(msym.owner) match {
                case Some(typ) if (typ.IsEnum) => {
                  def negBool() = {
                    mcode.Emit(OpCodes.Ldc_I4_0)
                    mcode.Emit(OpCodes.Ceq)
                  }
                  doEmit = false
                  val name = msym.name
                  if (name eq nme.EQ)       { mcode.Emit(OpCodes.Ceq) }
                  else if (name eq nme.NE)  { mcode.Emit(OpCodes.Ceq); negBool }
                  else if (name eq nme.LT)  { mcode.Emit(OpCodes.Clt) }
                  else if (name eq nme.LE)  { mcode.Emit(OpCodes.Cgt); negBool }
                  else if (name eq nme.GT)  { mcode.Emit(OpCodes.Cgt) }
                  else if (name eq nme.GE)  { mcode.Emit(OpCodes.Clt); negBool }
                  else if (name eq nme.OR)  { mcode.Emit(OpCodes.Or) }
                  else if (name eq nme.AND) { mcode.Emit(OpCodes.And) }
                  else if (name eq nme.XOR) { mcode.Emit(OpCodes.Xor) }
                  else
                    doEmit = true
                }
                case _ => ()
              }

              // method: implicit view(FunctionX[PType0, PType1, ...,PTypeN, ResType]):DelegateType
              val (isDelegateView, paramType, resType) = atPhase(currentRun.typerPhase) {
                msym.tpe match {
                  case MethodType(params, resultType)
                  if (params.length == 1 && msym.name == nme.view_) =>
                    val paramType = params(0).tpe
                    val isDel = definitions.isCorrespondingDelegate(resultType, paramType)
                    (isDel, paramType, resultType)
                  case _ => (false, null, null)
                }
              }
              if (doEmit && isDelegateView) {
                doEmit = false
                createDelegateCaller(paramType, resType)
              }

              if (doEmit &&
                  (msym.name == nme.PLUS || msym.name == nme.MINUS)
                  && clrTypes.isDelegateType(msilType(msym.owner.tpe)))
                {
                doEmit = false
                val methodInfo: MethodInfo = getMethod(msym)
                // call it as a static method, even if the compiler (symbol) thinks it's virtual
                mcode.Emit(OpCodes.Call, methodInfo)
                mcode.Emit(OpCodes.Castclass, msilType(msym.owner.tpe))
              }

              if (doEmit && definitions.Delegate_scalaCallers.contains(msym)) {
                doEmit = false
                val methodSym: Symbol = definitions.Delegate_scalaCallerTargets(msym)
                val delegateType: Type = msym.tpe match {
                  case MethodType(_, retType) => retType
                  case _ => abort("not a method type: " + msym.tpe)
                }
                val methodInfo: MethodInfo = getMethod(methodSym)
                val delegCtor = msilType(delegateType).GetConstructor(Array(MOBJECT, INT_PTR))
                if (methodSym.isStatic) {
                  mcode.Emit(OpCodes.Ldftn, methodInfo)
                } else {
                  mcode.Emit(OpCodes.Dup)
                  mcode.Emit(OpCodes.Ldvirtftn, methodInfo)
                }
                mcode.Emit(OpCodes.Newobj, delegCtor)
              }

              if (doEmit) {
                val methodInfo: MethodInfo = getMethod(msym)
                (style: @unchecked) match {
                  case SuperCall(_) =>
                    mcode.Emit(OpCodes.Call, methodInfo)
                  case Dynamic =>
                    // methodInfo.DeclaringType is null for global methods 
                    val isValuetypeMethod = (methodInfo.DeclaringType ne null) && (methodInfo.DeclaringType.IsValueType)
                    val isValuetypeVirtualMethod = isValuetypeMethod && (methodInfo.IsVirtual) 
                    if (dynToStatMapped(msym)) {
                      mcode.Emit(OpCodes.Call, methodInfo)
                    } else if (isValuetypeVirtualMethod) {
                      mcode.Emit(OpCodes.Constrained, methodInfo.DeclaringType)
                      mcode.Emit(OpCodes.Callvirt, methodInfo)
                    } else if (isValuetypeMethod) {
                      // otherwise error "Callvirt on a value type method" ensues 
                      mcode.Emit(OpCodes.Call, methodInfo)
                    } else {
                      mcode.Emit(OpCodes.Callvirt, methodInfo)
                    }
                  case Static(_) =>
                    if(methodInfo.IsVirtual && !mcode.Ldarg0WasJustEmitted) {
                      mcode.Emit(OpCodes.Callvirt, methodInfo)
                    } else mcode.Emit(OpCodes.Call, methodInfo)
              }
            }
            }

          case BOX(boxType) =>
            emitBox(mcode, boxType)

          case UNBOX(boxType) =>
            emitUnbox(mcode, boxType)

          case CIL_UNBOX(boxType) =>
            mcode.Emit(OpCodes.Unbox, msilType(boxType))

          case CIL_INITOBJ(valueType) =>
            mcode.Emit(OpCodes.Initobj, msilType(valueType))

          case NEW(REFERENCE(cls)) =>
            // the next instruction must be a DUP, see comment on `var previousWasNEW`
            previousWasNEW = true

          // works also for arrays and reference-types
          case CREATE_ARRAY(elem, dims) =>
            // TODO: handle multi dimensional arrays
            assert(dims == 1, "Can't handle multi dimensional arrays")
            mcode.Emit(OpCodes.Newarr, msilType(elem))

          // works for arrays and reference-types
          case IS_INSTANCE(tpe) =>
            mcode.Emit(OpCodes.Isinst, msilType(tpe))
            mcode.Emit(OpCodes.Ldnull)
            mcode.Emit(OpCodes.Ceq)
            mcode.Emit(OpCodes.Ldc_I4_0)
            mcode.Emit(OpCodes.Ceq)

          // works for arrays and reference-types
          // part from the scala reference: "S <: T does not imply
          //  Array[S] <: Array[T] in Scala. However, it is possible
          //  to cast an array of S to an array of T if such a cast
          //  is permitted in the host environment."
          case CHECK_CAST(tpknd) =>
            val tMSIL = msilType(tpknd)
              mcode.Emit(OpCodes.Castclass, tMSIL)

          // no SWITCH is generated when there's
          //  - a default case ("case _ => ...") in the matching expr
          //  - OR is used ("case 1 | 2 => ...")
          case SWITCH(tags, branches) =>
            // tags is List[List[Int]]; a list of integers for every label.
            //    if the int on stack is 4, and 4 is in the second list => jump
            //    to second label
            // branches is List[BasicBlock]
            //    the labels to jump to (the last one is the default one)

            val switchLocal = mcode.DeclareLocal(MINT)
            // several switch variables will appear with the same name in the
            //  assembly code, but this makes no truble
            switchLocal.SetLocalSymInfo("$switch_var")

            mcode.Emit(OpCodes.Stloc, switchLocal)
            var i = 0
            for (l <- tags) {
              var targetLabel = labels(branches(i))
              for (i <- l) {
                mcode.Emit(OpCodes.Ldloc, switchLocal)
                loadI4(i, mcode)
                mcode.Emit(OpCodes.Beq, targetLabel)
              }
              i += 1
            }
            val defaultTarget = labels(branches(i))
            if (next != defaultTarget)
              mcode.Emit(OpCodes.Br, defaultTarget)

          case JUMP(whereto) =>
            val (leaveHandler, leaveFinally, lfTarget) = leavesHandler(block, whereto)
            if (leaveHandler) {
              if (leaveFinally) {
                if (lfTarget.isDefined) mcode.Emit(OpCodes.Leave, lfTarget.get)
                else mcode.Emit(OpCodes.Endfinally)
              } else
                mcode.Emit(OpCodes.Leave, labels(whereto))
            } else if (next != whereto)
              mcode.Emit(OpCodes.Br, labels(whereto))

          case CJUMP(success, failure, cond, kind) =>
            // cond is TestOp (see Primitives.scala), and can take
            // values EQ, NE, LT, GE LE, GT
            // kind is TypeKind
            val isFloat = kind == FLOAT || kind == DOUBLE
            val emit = (c: TestOp, l: Label) => emitBr(c, l, isFloat)
            emitCondBr(block, cond, success, failure, next, emit)

          case CZJUMP(success, failure, cond, kind) =>
            emitCondBr(block, cond, success, failure, next, emitBrBool(_, _))

          case RETURN(kind) =>
            if (currentHandlers.isEmpty)
              mcode.Emit(OpCodes.Ret)
            else {
              val (local, label) = returnFromHandler(kind)
              if (kind != UNIT)
                mcode.Emit(OpCodes.Stloc, local)
              mcode.Emit(OpCodes.Leave, label)
            }

          case THROW(_) =>
            mcode.Emit(OpCodes.Throw)

          case DROP(kind) =>
            mcode.Emit(OpCodes.Pop)

          case DUP(kind) =>
            // see comment on `var previousWasNEW`
            if (!previousWasNEW)
              mcode.Emit(OpCodes.Dup)
            else
              previousWasNEW = false

          case MONITOR_ENTER() =>
            mcode.Emit(OpCodes.Call, MMONITOR_ENTER)

          case MONITOR_EXIT() =>
            mcode.Emit(OpCodes.Call, MMONITOR_EXIT)

          case SCOPE_ENTER(_) | SCOPE_EXIT(_) | LOAD_EXCEPTION(_) =>
            ()
        }

      } // end for (instr <- b) { .. }
    } // end genBlock

    def genPrimitive(primitive: Primitive, pos: Position) {
      primitive match {
        case Negation(kind) =>
          kind match {
            // CHECK: is ist possible to get this for BOOL? in this case, verify.
            case BOOL | BYTE | CHAR | SHORT | INT | LONG | FLOAT | DOUBLE =>
              mcode.Emit(OpCodes.Neg)

            case _ => abort("Impossible to negate a " + kind)
          }

        case Arithmetic(op, kind) =>
          op match {
            case ADD => mcode.Emit(OpCodes.Add)
            case SUB => mcode.Emit(OpCodes.Sub)
            case MUL => mcode.Emit(OpCodes.Mul)
            case DIV => mcode.Emit(OpCodes.Div)
            case REM => mcode.Emit(OpCodes.Rem)
            case NOT => mcode.Emit(OpCodes.Not) //bitwise complement (one's complement)
            case _ => abort("Unknown arithmetic primitive " + primitive )
          }

        case Logical(op, kind) => op match {
          case AND => mcode.Emit(OpCodes.And)
          case OR => mcode.Emit(OpCodes.Or)
          case XOR => mcode.Emit(OpCodes.Xor)
        }

        case Shift(op, kind) => op match {
          case LSL => mcode.Emit(OpCodes.Shl)
          case ASR => mcode.Emit(OpCodes.Shr)
          case LSR => mcode.Emit(OpCodes.Shr_Un)
        }

        case Conversion(src, dst) =>
          if (settings.debug.value)
            log("Converting from: " + src + " to: " + dst)

          dst match {
            case BYTE =>   mcode.Emit(OpCodes.Conv_I1) // I1 for System.SByte, i.e. a scala.Byte
            case SHORT =>  mcode.Emit(OpCodes.Conv_I2)
            case CHAR =>   mcode.Emit(OpCodes.Conv_U2)
            case INT =>    mcode.Emit(OpCodes.Conv_I4)
            case LONG =>   mcode.Emit(OpCodes.Conv_I8)
            case FLOAT =>  mcode.Emit(OpCodes.Conv_R4)
            case DOUBLE => mcode.Emit(OpCodes.Conv_R8)
            case _ =>
              Console.println("Illegal conversion at: " + clasz +
                              " at: " + pos.source + ":" + pos.line)
          }

        case ArrayLength(_) =>
          mcode.Emit(OpCodes.Ldlen)

        case StartConcat =>
          mcode.Emit(OpCodes.Newobj, MSTRING_BUILDER_CONSTR)


        case StringConcat(el) =>
          val elemType : MsilType = el match {
            case REFERENCE(_) | ARRAY(_) => MOBJECT
            case _ => msilType(el)
          }

          val argTypes:Array[MsilType] = Array(elemType)
          val stringBuilderAppend = MSTRING_BUILDER.GetMethod("Append", argTypes )
          mcode.Emit(OpCodes.Callvirt,  stringBuilderAppend)

        case EndConcat =>
          mcode.Emit(OpCodes.Callvirt, MSTRING_BUILDER_TOSTRING)

        case _ =>
          abort("Unimplemented primitive " + primitive)
      }
    } // end genPrimitive


    ////////////////////// loading ///////////////////////

    def loadI4(value: Int, code: ILGenerator): Unit = value match {
      case -1 => code.Emit(OpCodes.Ldc_I4_M1)
      case 0  => code.Emit(OpCodes.Ldc_I4_0)
      case 1  => code.Emit(OpCodes.Ldc_I4_1)
      case 2  => code.Emit(OpCodes.Ldc_I4_2)
      case 3  => code.Emit(OpCodes.Ldc_I4_3)
      case 4  => code.Emit(OpCodes.Ldc_I4_4)
      case 5  => code.Emit(OpCodes.Ldc_I4_5)
      case 6  => code.Emit(OpCodes.Ldc_I4_6)
      case 7  => code.Emit(OpCodes.Ldc_I4_7)
      case 8  => code.Emit(OpCodes.Ldc_I4_8)
      case _  =>
        if (value >= -128 && value <= 127)
          code.Emit(OpCodes.Ldc_I4_S, value)
        else
          code.Emit(OpCodes.Ldc_I4, value)
    }

    def loadArg(code: ILGenerator, loadAddr: Boolean)(i: Int) =
      if (loadAddr) {
        if (i >= -128 && i <= 127)
          code.Emit(OpCodes.Ldarga_S, i)
        else
          code.Emit(OpCodes.Ldarga, i)
      } else {
        i match {
          case 0 => code.Emit(OpCodes.Ldarg_0)
          case 1 => code.Emit(OpCodes.Ldarg_1)
          case 2 => code.Emit(OpCodes.Ldarg_2)
          case 3 => code.Emit(OpCodes.Ldarg_3)
          case _      =>
            if (i >= -128 && i <= 127)
              code.Emit(OpCodes.Ldarg_S, i)
            else
              code.Emit(OpCodes.Ldarg, i)
        }
      }

    def loadLocal(i: Int, local: Local, code: ILGenerator, loadAddr: Boolean) =
      if (loadAddr) {
        if (i >= -128 && i <= 127)
          code.Emit(OpCodes.Ldloca_S, localBuilders(local))
        else
          code.Emit(OpCodes.Ldloca, localBuilders(local))
      } else {
        i match {
          case 0 => code.Emit(OpCodes.Ldloc_0)
          case 1 => code.Emit(OpCodes.Ldloc_1)
          case 2 => code.Emit(OpCodes.Ldloc_2)
          case 3 => code.Emit(OpCodes.Ldloc_3)
          case _      =>
            if (i >= -128 && i <= 127)
              code.Emit(OpCodes.Ldloc_S, localBuilders(local))
            else
              code.Emit(OpCodes.Ldloc, localBuilders(local))
        }
      }

    ////////////////////// branches ///////////////////////

    /** Returns a Triple (Boolean, Boolean, Option[Label])
     *   - whether the jump leaves some exception block (try / catch / finally)
     *   - whether it leaves a finally handler (finally block, but not it's try / catch)
     *   - a label where to jump for leaving the finally handler
     *     . None to leave directly using `endfinally`
     *     . Some(label) to emit `leave label` (for try / catch inside a finally handler)
     */
    def leavesHandler(from: BasicBlock, to: BasicBlock): (Boolean, Boolean, Option[Label]) =
      if (currentHandlers.isEmpty) (false, false, None)
      else {
        val h = currentHandlers.head
        val leaveHead = { h.covers(from) != h.covers(to) ||
                          h.blocks.contains(from) != h.blocks.contains(to) }
        if (leaveHead) {
          // we leave the innermost exception block.
          // find out if we also leave som e `finally` handler
          currentHandlers.find(e => {
            e.cls == NoSymbol && e.blocks.contains(from) != e.blocks.contains(to)
          }) match {
            case Some(finallyHandler) =>
              if (h == finallyHandler) {
                // the finally handler is the innermost, so we can emit `endfinally` directly
                (true, true, None)
              } else {
                // we need to `Leave` to the `endfinally` of the next outer finally handler
                val l = endFinallyLabels.getOrElseUpdate(finallyHandler, mcode.DefineLabel())
                (true, true, Some(l))
              }
            case None =>
              (true, false, None)
          }
        } else (false, false, None)
      }

    def emitCondBr(block: BasicBlock, cond: TestOp, success: BasicBlock, failure: BasicBlock,
                   next: BasicBlock, emitBrFun: (TestOp, Label) => Unit) {
      val (sLeaveHandler, sLeaveFinally, slfTarget) = leavesHandler(block, success)
      val (fLeaveHandler, fLeaveFinally, flfTarget) = leavesHandler(block, failure)

      if (sLeaveHandler || fLeaveHandler) {
        val sLabelOpt = if (sLeaveHandler) {
          val leaveSLabel = mcode.DefineLabel()
          emitBrFun(cond, leaveSLabel)
          Some(leaveSLabel)
        } else {
          emitBrFun(cond, labels(success))
          None
        }

        if (fLeaveHandler) {
          if (fLeaveFinally) {
            if (flfTarget.isDefined) mcode.Emit(OpCodes.Leave, flfTarget.get)
            else mcode.Emit(OpCodes.Endfinally)
          } else
            mcode.Emit(OpCodes.Leave, labels(failure))
        } else
          mcode.Emit(OpCodes.Br, labels(failure))

        sLabelOpt.map(l => {
          mcode.MarkLabel(l)
          if (sLeaveFinally) {
            if (slfTarget.isDefined) mcode.Emit(OpCodes.Leave, slfTarget.get)
            else mcode.Emit(OpCodes.Endfinally)
          } else
            mcode.Emit(OpCodes.Leave, labels(success))
        })
      } else {
        if (next == success) {
          emitBrFun(cond.negate, labels(failure))
        } else {
          emitBrFun(cond, labels(success))
          if (next != failure) {
            mcode.Emit(OpCodes.Br, labels(failure))
          }
        }
      }
    }

    def emitBr(condition: TestOp, dest: Label, isFloat: Boolean) {
      condition match {
        case EQ => mcode.Emit(OpCodes.Beq, dest)
        case NE => mcode.Emit(OpCodes.Bne_Un, dest)
        case LT => mcode.Emit(if (isFloat) OpCodes.Blt_Un else OpCodes.Blt, dest)
        case GE => mcode.Emit(if (isFloat) OpCodes.Bge_Un else OpCodes.Bge, dest)
        case LE => mcode.Emit(if (isFloat) OpCodes.Ble_Un else OpCodes.Ble, dest)
        case GT => mcode.Emit(if (isFloat) OpCodes.Bgt_Un else OpCodes.Bgt, dest)
      }
    }

    def emitBrBool(cond: TestOp, dest: Label) {
      cond match {
        // EQ -> Brfalse, NE -> Brtrue; this is because we come from
        // a CZJUMP. If the value on the stack is 0 (e.g. a boolean
        // method returned false), and we are in the case EQ, then
        // we need to emit Brfalse (EQ Zero means false). vice versa
        case EQ => mcode.Emit(OpCodes.Brfalse, dest)
        case NE => mcode.Emit(OpCodes.Brtrue, dest)
      }
    }

    ////////////////////// local vars ///////////////////////

    /**
     * Compute the indexes of each local variable of the given
     * method.
     */
    def computeLocalVarsIndex(m: IMethod) {
      var idx = if (m.symbol.isStaticMember) 0 else 1

      val params = m.params
      for (l <- params) {
        if (settings.debug.value)
          log("Index value for parameter " + l + ": " + idx)
        l.index = idx
        idx += 1 // sizeOf(l.kind)
      }

      val locvars = m.locals filterNot (params contains)
      idx = 0

      for (l <- locvars) {
        if (settings.debug.value)
          log("Index value for local variable " + l + ": " + idx)
        l.index = idx
        idx += 1 // sizeOf(l.kind)
      }

    }

    ////////////////////// Utilities ////////////////////////

    /** Return the a name of this symbol that can be used on the .NET
     * platform. It removes spaces from names.
     *
     * Special handling: scala.All and scala.AllRef are 'erased' to
     * scala.All$ and scala.AllRef$. This is needed because they are
     * not real classes, and they mean 'abrupt termination upon evaluation
     * of that expression' or 'null' respectively. This handling is
     * done already in GenICode, but here we need to remove references
     * from method signatures to these types, because such classes can
     * not exist in the classpath: the type checker will be very confused.
     */
    def msilName(sym: Symbol): String = {
      val suffix: String = if (sym.hasModuleFlag && !sym.isMethod &&
                               !sym.isImplClass &&
                               !sym.isJavaDefined) "$" else ""
      // Flags.JAVA: "symbol was not defined by a scala-class" (java, or .net-class)

      if (sym == definitions.NothingClass)
        return "scala.runtime.Nothing$"
      else if (sym == definitions.NullClass)
        return "scala.runtime.Null$"

      (if (sym.isClass || (sym.isModule && !sym.isMethod)) {
        if (sym.isNestedClass) sym.simpleName
        else sym.fullName
       } else
         sym.simpleName.toString().trim()) + suffix
    }


    ////////////////////// flags ///////////////////////

    def msilTypeFlags(sym: Symbol): Int = {
      var mf: Int = TypeAttributes.AutoLayout | TypeAttributes.AnsiClass

      if(sym.isNestedClass) {
        mf = mf | (if (sym hasFlag Flags.PRIVATE) TypeAttributes.NestedPrivate else TypeAttributes.NestedPublic)
      } else {
        mf = mf | (if (sym hasFlag Flags.PRIVATE) TypeAttributes.NotPublic else TypeAttributes.Public)
      }
      mf = mf | (if (sym hasFlag Flags.ABSTRACT) TypeAttributes.Abstract else 0)
      mf = mf | (if (sym.isTrait && !sym.isImplClass) TypeAttributes.Interface else TypeAttributes.Class)
      mf = mf | (if (sym isFinal) TypeAttributes.Sealed else 0)

      sym.annotations foreach { a => a match {
        case AnnotationInfo(SerializableAttr, _, _) =>
          // TODO: add the Serializable TypeAttribute also if the annotation
          // System.SerializableAttribute is present (.net annotation, not scala)
          //  Best way to do it: compare with
          //  definitions.getClass("System.SerializableAttribute").tpe
          //  when frontend available
          mf = mf | TypeAttributes.Serializable
        case _ => ()
      }}

      mf
      // static: not possible (or?)
    }

    def msilMethodFlags(sym: Symbol): Short = {
      var mf: Int = MethodAttributes.HideBySig |
        (if (sym hasFlag Flags.PRIVATE) MethodAttributes.Private
         else MethodAttributes.Public)

      if (!sym.isClassConstructor) {
        if (sym.isStaticMember)
          mf = mf | FieldAttributes.Static // coincidentally, same value as for MethodAttributes.Static ...
        else {
          mf = mf | MethodAttributes.Virtual
          if (sym.isFinal && !getType(sym.owner).IsInterface)
            mf = mf | MethodAttributes.Final
          if (sym.isDeferred || getType(sym.owner).IsInterface)
            mf = mf | MethodAttributes.Abstract
        }
      }

      if (sym.isStaticMember) {
        mf = mf | MethodAttributes.Static
      }

      // constructors of module classes should be private
      if (sym.isPrimaryConstructor && isTopLevelModule(sym.owner)) {
        mf |= MethodAttributes.Private
        mf &= ~(MethodAttributes.Public)
      }

      mf.toShort
    }

    def msilFieldFlags(sym: Symbol): Short = {
      var mf: Int =
        if (sym hasFlag Flags.PRIVATE) FieldAttributes.Private
        else if (sym hasFlag Flags.PROTECTED) FieldAttributes.FamORAssem
        else FieldAttributes.Public

      if (sym hasFlag Flags.FINAL)
        mf = mf | FieldAttributes.InitOnly

      if (sym.isStaticMember)
        mf = mf | FieldAttributes.Static

      // TRANSIENT: "not serialized", VOLATILE: doesn't exist on .net
      // TODO: add this annotation also if the class has the custom attribute
      // System.NotSerializedAttribute
      sym.annotations.foreach( a => a match {
        case AnnotationInfo(TransientAtt, _, _) =>
          mf = mf | FieldAttributes.NotSerialized
        case _ => ()
      })

      mf.toShort
    }

    ////////////////////// builders, types ///////////////////////

    var entryPoint: Symbol = _

    val notInitializedModules: HashSet[Symbol] = new HashSet()

    // TODO: create fields also in def createType, and not in genClass,
    // add a getField method (it only works as it is because fields never
    // accessed from outside a class)

    val localBuilders: HashMap[Local, LocalBuilder] = new HashMap()

    private[GenMSIL] def findEntryPoint(cls: IClass) {

      def isEntryPoint(sym: Symbol):Boolean = {
        if (isStaticModule(sym.owner) && msilName(sym) == "main")
          if (sym.tpe.paramTypes.length == 1) {
            toTypeKind(sym.tpe.paramTypes(0)) match {
              case ARRAY(elem) =>
                if (elem.toType.typeSymbol == definitions.StringClass) {
                  return true
                }
              case _ => ()
            }
          }
        false
      }

      if((entryPoint == null) && opt.showClass.isDefined) {  // TODO introduce dedicated setting instead 
        val entryclass = opt.showClass.get.toString 
        val cfn = cls.symbol.fullName
        if(cfn == entryclass) {
          for (m <- cls.methods; if isEntryPoint(m.symbol)) { entryPoint = m.symbol }
          if(entryPoint == null) { warning("Couldn't find main method in class " + cfn) }
        }
      }

      if (firstSourceName == "")
        if (cls.symbol.sourceFile != null) // is null for nested classes
          firstSourceName = cls.symbol.sourceFile.name
    }

    // #####################################################################
    // get and create types

    private def msilType(t: TypeKind): MsilType = (t: @unchecked) match {
      case UNIT           => MVOID
      case BOOL           => MBOOL
      case BYTE           => MBYTE
      case SHORT          => MSHORT
      case CHAR           => MCHAR
      case INT            => MINT
      case LONG           => MLONG
      case FLOAT          => MFLOAT
      case DOUBLE         => MDOUBLE
      case REFERENCE(cls) => getType(cls)
      case ARRAY(elem)    =>
        msilType(elem) match {
          // For type builders, cannot call "clrTypes.mkArrayType" because this looks up
          // the type "tp" in the assembly (not in the HashMap "types" of the backend).
          // This can fail for nested types because the builders are not complete yet.
          case tb: TypeBuilder => tb.MakeArrayType()
          case tp: MsilType => clrTypes.mkArrayType(tp)
        }
    }

    private def msilType(tpe: Type): MsilType = msilType(toTypeKind(tpe))

    private def msilParamTypes(sym: Symbol): Array[MsilType] = {
      sym.tpe.paramTypes.map(msilType).toArray
    }

    def getType(sym: Symbol) = getTypeOpt(sym).getOrElse(abort(showsym(sym)))

    /**
     * Get an MSIL type from a symbol. First look in the clrTypes.types map, then
     * lookup the name using clrTypes.getType
     */
    def getTypeOpt(sym: Symbol): Option[MsilType] = {
      val tmp = types.get(sym)
      tmp match {
        case typ @ Some(_) => typ
        case None =>
          def typeString(sym: Symbol): String = {
            val s = if (sym.isNestedClass) typeString(sym.owner) +"+"+ sym.simpleName
                    else sym.fullName
            if (sym.isModuleClass && !sym.isTrait) s + "$" else s
          }
          val name = typeString(sym)
          val typ = clrTypes.getType(name)
          if (typ == null)
            None
          else {
            types(sym) = typ
            Some(typ)
          }
      }
    }

    def mapType(sym: Symbol, mType: MsilType) {
      assert(mType != null, showsym(sym))
      types(sym) = mType
    }

    def createTypeBuilder(iclass: IClass) {
      /**
       * First look in the clrTypes.types map, if that fails check if it's a class being compiled, otherwise
       * lookup by name (clrTypes.getType calls the static method msil.Type.GetType(fullname)).
       */
      def msilTypeFromSym(sym: Symbol): MsilType = {
        types.get(sym).getOrElse {
          classes.get(sym) match {
            case Some(iclass) =>
	              msilTypeBuilderFromSym(sym)
            case None =>
              getType(sym)
          }
        }
      }

      def msilTypeBuilderFromSym(sym: Symbol): TypeBuilder = {
        if(!(types.contains(sym) && types(sym).isInstanceOf[TypeBuilder])){
          val iclass = classes(sym)
          assert(iclass != null)
          createTypeBuilder(iclass)
        }
        types(sym).asInstanceOf[TypeBuilder]
      }

      val sym = iclass.symbol
      if (types.contains(sym) && types(sym).isInstanceOf[TypeBuilder])
        return

      def isInterface(s: Symbol) = s.isTrait && !s.isImplClass
      val parents: List[Type] =
        if (sym.info.parents.isEmpty) List(definitions.ObjectClass.tpe)
        else sym.info.parents.distinct

      val superType : MsilType = if (isInterface(sym)) null else msilTypeFromSym(parents.head.typeSymbol)
      if (settings.debug.value)
        log("super type: " + parents(0).typeSymbol + ", msil type: " + superType)

      val interfaces: Array[MsilType] =
	parents.tail.map(p => msilTypeFromSym(p.typeSymbol)).toArray
      if (parents.length > 1) {
        if (settings.debug.value) {
          log("interfaces:")
          for (i <- 0.until(interfaces.length)) {
            log("  type: " + parents(i + 1).typeSymbol + ", msil type: " + interfaces(i))
          }
        }
      }

      val tBuilder = if (sym.isNestedClass) {
        val ownerT = msilTypeBuilderFromSym(sym.owner).asInstanceOf[TypeBuilder]
        ownerT.DefineNestedType(msilName(sym), msilTypeFlags(sym), superType, interfaces)
      } else {
        mmodule.DefineType(msilName(sym), msilTypeFlags(sym), superType, interfaces)
      }
      mapType(sym, tBuilder)
    } // createTypeBuilder

    def createClassMembers(iclass: IClass) {
      try {
        createClassMembers0(iclass)
      }
      catch {
        case e: Throwable =>
          java.lang.System.err.println(showsym(iclass.symbol))
          java.lang.System.err.println("with methods = " + iclass.methods)
          throw e
      }
    }

    def createClassMembers0(iclass: IClass) {

      val mtype = getType(iclass.symbol).asInstanceOf[TypeBuilder]

      for (ifield <- iclass.fields) {
        val sym = ifield.symbol
        if (settings.debug.value)
          log("Adding field: " + sym.fullName)

        var attributes = msilFieldFlags(sym)
        val fieldTypeWithCustomMods = 
          new PECustomMod(msilType(sym.tpe), 
                          customModifiers(sym.annotations)) 
        val fBuilder = mtype.DefineField(msilName(sym), 
                                         fieldTypeWithCustomMods, 
                                         attributes)
        fields(sym) = fBuilder
        addAttributes(fBuilder, sym.annotations)
      } // all iclass.fields iterated over

      if (isStaticModule(iclass.symbol)) {
        val sc = iclass.lookupStaticCtor
        if (sc.isDefined) {
          val m = sc.get
          val oldLastBlock = m.code.blocks.last
          val lastBlock = m.code.newBlock
          oldLastBlock.replaceInstruction(oldLastBlock.length - 1, JUMP(lastBlock))
          // call object's private ctor from static ctor
          lastBlock.emit(CIL_NEWOBJ(iclass.symbol.primaryConstructor))
          lastBlock.emit(DROP(toTypeKind(iclass.symbol.tpe)))
          lastBlock emit RETURN(UNIT)
          lastBlock.close
        }
      }

      if (iclass.symbol != definitions.ArrayClass) {
      for (m: IMethod <- iclass.methods) {
        val sym = m.symbol
        if (settings.debug.value)
          log("Creating MethodBuilder for " + Flags.flagsToString(sym.flags) + " " +
              sym.owner.fullName + "::" + sym.name)

        val ownerType = getType(sym.enclClass).asInstanceOf[TypeBuilder]
        assert(mtype == ownerType, "mtype = " + mtype + "; ownerType = " + ownerType)
        var paramTypes = msilParamTypes(sym)
        val attr = msilMethodFlags(sym)

        if (m.symbol.isClassConstructor) {
          val constr =
            ownerType.DefineConstructor(attr, CallingConventions.Standard, paramTypes)
          for (i <- 0.until(paramTypes.length)) {
            constr.DefineParameter(i, ParameterAttributes.None, msilName(m.params(i).sym))
          }
          mapConstructor(sym, constr)
          addAttributes(constr, sym.annotations)
        } else {
          var resType = msilType(m.returnType)
          val method =
            ownerType.DefineMethod(msilName(sym), attr, resType, paramTypes)
          for (i <- 0.until(paramTypes.length)) {
            method.DefineParameter(i, ParameterAttributes.None, msilName(m.params(i).sym))
          }
          if (!methods.contains(sym))
            mapMethod(sym, method)
          addAttributes(method, sym.annotations)
          if (settings.debug.value)
            log("\t created MethodBuilder " + method)
        }
      }
      } // method builders created for non-array iclass

      if (isStaticModule(iclass.symbol)) {
        addModuleInstanceField(iclass.symbol)
        notInitializedModules += iclass.symbol
        if (iclass.lookupStaticCtor.isEmpty) {
          addStaticInit(iclass.symbol)
        }
      }

    } // createClassMembers0

    private def isTopLevelModule(sym: Symbol): Boolean =
      atPhase (currentRun.refchecksPhase) {
        sym.isModuleClass && !sym.isImplClass && !sym.isNestedClass
      }

    // if the module is lifted it does not need to be initialized in
    // its static constructor, and the MODULE$ field is not required.
    // the outer class will care about it.
    private def isStaticModule(sym: Symbol): Boolean = {
      // .net inner classes: removed '!sym.hasFlag(Flags.LIFTED)', added
      // 'sym.isStatic'. -> no longer compatible without skipping flatten!
      sym.isModuleClass && sym.isStatic && !sym.isImplClass
    }

    private def isCloneable(sym: Symbol): Boolean = {
      !sym.annotations.forall( a => a match {
        case AnnotationInfo(CloneableAttr, _, _) => false
        case _ => true
      })
    }

    private def addModuleInstanceField(sym: Symbol) {
      if (settings.debug.value)
        log("Adding Module-Instance Field for " + showsym(sym))
      val tBuilder = getType(sym).asInstanceOf[TypeBuilder]
      val fb = tBuilder.DefineField(MODULE_INSTANCE_NAME,
                           tBuilder,
                           (FieldAttributes.Public |
                            //FieldAttributes.InitOnly |
                            FieldAttributes.Static).toShort)
      fields(sym) = fb
    }


    // the symbol may be a object-symbol (module-symbol), or a module-class-symbol
    private def getModuleInstanceField(sym: Symbol): FieldInfo = {
      assert(sym.isModule || sym.isModuleClass, "Expected module: " + showsym(sym))

      // when called by LOAD_MODULE, the corresponding type maybe doesn't
      // exist yet -> make a getType
      val moduleClassSym = if (sym.isModule) sym.moduleClass else sym

      // TODO: get module field for modules not defined in the
      // source currently compiling (e.g. Console)

      fields get moduleClassSym match {
        case Some(sym) => sym
        case None =>
          //val mclass = types(moduleClassSym)
          val nameInMetadata = nestingAwareFullClassname(moduleClassSym)
          val mClass = clrTypes.getType(nameInMetadata)
          val mfield = mClass.GetField("MODULE$")
          assert(mfield ne null, "module not found " + showsym(moduleClassSym))
          fields(moduleClassSym) = mfield
          mfield
      }

      //fields(moduleClassSym)
    }

    def nestingAwareFullClassname(csym: Symbol) : String = {
      val suffix = moduleSuffix(csym)
      val res = if (csym.isNestedClass)
        nestingAwareFullClassname(csym.owner) + "+" + csym.encodedName
      else
        csym.fullName
      res + suffix
    }

  /** cut&pasted from GenJVM */
  def moduleSuffix(sym: Symbol) =
    if (sym.hasFlag(Flags.MODULE) && !sym.isMethod &&
       !sym.isImplClass && !sym.hasFlag(Flags.JAVA)) "$"
    else "";

    /** Adds a static initializer which creates an instance of the module
     *  class (calls the primary constructor). A special primary constructor
     *  will be generated (notInitializedModules) which stores the new instance
     *  in the MODULE$ field right after the super call.
     */
    private def addStaticInit(sym: Symbol) {
      val tBuilder = getType(sym).asInstanceOf[TypeBuilder]

      val staticInit = tBuilder.DefineConstructor(
        (MethodAttributes.Static | MethodAttributes.Public).toShort,
        CallingConventions.Standard,
        MsilType.EmptyTypes)

      val sicode = staticInit.GetILGenerator()

      val instanceConstructor = constructors(sym.primaryConstructor)

      // there are no constructor parameters. assuming the constructor takes no parameter
      // is fine: we call (in the static constructor) the constructor of the module class,
      // which takes no arguments - an object definition cannot take constructor arguments.
      sicode.Emit(OpCodes.Newobj, instanceConstructor)
      // the stsfld is done in the instance constructor, just after the super call.
      sicode.Emit(OpCodes.Pop)

      sicode.Emit(OpCodes.Ret)
    }

    private def dumpMirrorClass(sym: Symbol) {
      val tBuilder = getType(sym)
      assert(sym.isModuleClass, "Can't generate Mirror-Class for the Non-Module class " + sym)
      if (settings.debug.value)
        log("Dumping mirror class for object: " + sym)
      val moduleName = msilName(sym)
      val mirrorName = moduleName.substring(0, moduleName.length() - 1)
      val mirrorTypeBuilder = mmodule.DefineType(mirrorName,
                                                 TypeAttributes.Class |
                                                 TypeAttributes.Public |
                                                 TypeAttributes.Sealed,
                                                 MOBJECT,
                                                 MsilType.EmptyTypes)

      val iclass = classes(sym)

      for (m <- sym.tpe.nonPrivateMembers
           if m.owner != definitions.ObjectClass && !m.isProtected &&
           m.isMethod && !m.isClassConstructor && !m.isStaticMember && !m.isCase &&
           !m.isDeferred)
        {
          if (settings.debug.value)
            log("   Mirroring method: " + m)
          val paramTypes = msilParamTypes(m)
          val paramNames: Array[String] = new Array[String](paramTypes.length)
          for (i <- 0 until paramTypes.length)
            paramNames(i) = "x_" + i

          // CHECK: verify if getMethodName is better than msilName
          val mirrorMethod = mirrorTypeBuilder.DefineMethod(msilName(m),
                                                            (MethodAttributes.Public |
                                                            MethodAttributes.Static).toShort,
                                                            msilType(m.tpe.resultType),
                                                            paramTypes)

          var i = 0
          while (i < paramTypes.length) {
            mirrorMethod.DefineParameter(i, ParameterAttributes.None, paramNames(i))
            i += 1
          }

          val mirrorCode = mirrorMethod.GetILGenerator()
          mirrorCode.Emit(OpCodes.Ldsfld, getModuleInstanceField(sym))
          val mInfo = getMethod(m)
          for (paramidx <- 0.until(paramTypes.length)) {
            val mInfoParams = mInfo.GetParameters
            val loadAddr = mInfoParams(paramidx).ParameterType.IsByRef
            loadArg(mirrorCode, loadAddr)(paramidx)
          }

          mirrorCode.Emit(OpCodes.Callvirt, getMethod(m))
          mirrorCode.Emit(OpCodes.Ret)
        }

      addSymtabAttribute(sym.sourceModule, mirrorTypeBuilder)

      mirrorTypeBuilder.CreateType()
      mirrorTypeBuilder.setSourceFilepath(iclass.cunit.source.file.path)
    }


    // #####################################################################
    // delegate callers

    var delegateCallers: TypeBuilder = _
    var nbDelegateCallers: Int = 0

    private def initDelegateCallers() = {
      delegateCallers = mmodule.DefineType("$DelegateCallers", TypeAttributes.Public |
                                          TypeAttributes.Sealed)
    }

    private def createDelegateCaller(functionType: Type, delegateType: Type) = {
      if (delegateCallers == null)
        initDelegateCallers()
      // create a field an store the function-object
      val mFunctionType: MsilType = msilType(functionType)
      val anonfunField: FieldBuilder = delegateCallers.DefineField(
        "$anonfunField$$" + nbDelegateCallers, mFunctionType,
        (FieldAttributes.InitOnly | FieldAttributes.Public | FieldAttributes.Static).toShort)
      mcode.Emit(OpCodes.Stsfld, anonfunField)


      // create the static caller method and the delegate object
      val (params, returnType) = delegateType.member(nme.apply).tpe match {
        case MethodType(delParams, delReturn) => (delParams, delReturn)
        case _ => abort("not a delegate type: "  + delegateType)
      }
      val caller: MethodBuilder = delegateCallers.DefineMethod(
        "$delegateCaller$$" + nbDelegateCallers,
        (MethodAttributes.Final | MethodAttributes.Public | MethodAttributes.Static).toShort,
        msilType(returnType), (params map (_.tpe)).map(msilType).toArray)
      for (i <- 0 until params.length)
        caller.DefineParameter(i, ParameterAttributes.None, "arg" + i) // FIXME: use name of parameter symbol 
      val delegCtor = msilType(delegateType).GetConstructor(Array(MOBJECT, INT_PTR))
      mcode.Emit(OpCodes.Ldnull)
      mcode.Emit(OpCodes.Ldftn, caller)
      mcode.Emit(OpCodes.Newobj, delegCtor)


      // create the static caller method body
      val functionApply: MethodInfo = getMethod(functionType.member(nme.apply))
      val dcode: ILGenerator = caller.GetILGenerator()
      dcode.Emit(OpCodes.Ldsfld, anonfunField)
      for (i <- 0 until params.length) {
        loadArg(dcode, false /* TODO confirm whether passing actual as-is to formal is correct wrt the ByRef attribute of the param */)(i)
        emitBox(dcode, toTypeKind(params(i).tpe))
      }
      dcode.Emit(OpCodes.Callvirt, functionApply)
      emitUnbox(dcode, toTypeKind(returnType))
      dcode.Emit(OpCodes.Ret)

      nbDelegateCallers = nbDelegateCallers + 1

    } //def createDelegateCaller

    def emitBox(code: ILGenerator, boxType: TypeKind) = (boxType: @unchecked) match {
      // doesn't make sense, unit as parameter..
      case UNIT   => code.Emit(OpCodes.Ldsfld, boxedUnit)
      case BOOL | BYTE | SHORT | CHAR | INT | LONG | FLOAT | DOUBLE =>
        code.Emit(OpCodes.Box, msilType(boxType))
      case REFERENCE(cls) if clrTypes.isValueType(cls) => 
        code.Emit(OpCodes.Box, (msilType(boxType)))
      case REFERENCE(_) | ARRAY(_) =>
        warning("Tried to BOX a non-valuetype.")
        ()
    }

    def emitUnbox(code: ILGenerator, boxType: TypeKind) = (boxType: @unchecked) match {
      case UNIT   => code.Emit(OpCodes.Pop)
      /* (1) it's essential to keep the code emitted here (as of now plain calls to System.Convert.ToBlaBla methods)
             behaviorally.equiv.wrt. BoxesRunTime.unboxToBlaBla methods 
             (case null: that's easy, case boxed: track changes to unboxBlaBla)
         (2) See also: asInstanceOf to cast from Any to number, 
             tracked in http://lampsvn.epfl.ch/trac/scala/ticket/4437  */
      case BOOL   => code.Emit(OpCodes.Call, toBool) 
      case BYTE   => code.Emit(OpCodes.Call, toSByte)
      case SHORT  => code.Emit(OpCodes.Call, toShort)
      case CHAR   => code.Emit(OpCodes.Call, toChar)
      case INT    => code.Emit(OpCodes.Call, toInt)
      case LONG   => code.Emit(OpCodes.Call, toLong)
      case FLOAT  => code.Emit(OpCodes.Call, toFloat)
      case DOUBLE => code.Emit(OpCodes.Call, toDouble)
      case REFERENCE(cls) if clrTypes.isValueType(cls) =>
        code.Emit(OpCodes.Unbox, msilType(boxType))
        code.Emit(OpCodes.Ldobj, msilType(boxType))
      case REFERENCE(_) | ARRAY(_) =>
        warning("Tried to UNBOX a non-valuetype.")
        ()
    }

    // #####################################################################
    // get and create methods / constructors
 
    def getConstructor(sym: Symbol): ConstructorInfo = constructors.get(sym) match {
      case Some(constr) => constr
      case None =>
        val mClass = getType(sym.owner)
        val constr = mClass.GetConstructor(msilParamTypes(sym))
        if (constr eq null) {
          java.lang.System.out.println("Cannot find constructor " + sym.owner + "::" + sym.name)
          java.lang.System.out.println("scope = " + sym.owner.tpe.decls)
          abort(sym.fullName)
        }
        else {
          mapConstructor(sym, constr)
          constr
        }
    }

    def mapConstructor(sym: Symbol, cInfo: ConstructorInfo) = {
      constructors(sym) = cInfo
    }

    private def getMethod(sym: Symbol): MethodInfo = {

        methods.get(sym) match {
        case Some(method) => method
        case None =>
          val mClass = getType(sym.owner)
          try {
            val method = mClass.GetMethod(msilName(sym), msilParamTypes(sym),
                                          msilType(sym.tpe.resultType))
            if (method eq null) {
              java.lang.System.out.println("Cannot find method " + sym.owner + "::" + msilName(sym))
              java.lang.System.out.println("scope = " + sym.owner.tpe.decls)
              abort(sym.fullName)
            }
            else {
              mapMethod(sym, method)
              method
            }
          }
          catch {
            case e: Exception =>
              Console.println("While looking up " + mClass + "::" + sym.nameString)
            Console.println("\t" + showsym(sym))
            throw e
          }
      }
    }

    /*
     * add a mapping between sym and mInfo
     */
    private def mapMethod(sym: Symbol, mInfo: MethodInfo) {
      assert (mInfo != null, mInfo)
      methods(sym) = mInfo
    }

    /*
     * add mapping between sym and method with newName, paramTypes of newClass
     */
    private def mapMethod(sym: Symbol, newClass: MsilType, newName: String, paramTypes: Array[MsilType]) {
      val methodInfo = newClass.GetMethod(newName, paramTypes)
      assert(methodInfo != null, "Can't find mapping for " + sym + " -> " +
             newName + "(" + paramTypes + ")")
      mapMethod(sym, methodInfo)
      if (methodInfo.IsStatic) 
        dynToStatMapped += sym
    }

    /*
     * add mapping between method with name and paramTypes of clazz to
     * method with newName and newParamTypes of newClass (used for instance
     * for "wait")
     */
    private def mapMethod(
      clazz: Symbol, name: Name, paramTypes: Array[Type],
      newClass: MsilType, newName: String, newParamTypes: Array[MsilType]) {
        val methodSym = lookupMethod(clazz, name, paramTypes)
        assert(methodSym != null, "cannot find method " + name + "(" +
               paramTypes + ")" + " in class " + clazz)
        mapMethod(methodSym, newClass, newName, newParamTypes)
      }

    /*
     * add mapping for member with name and paramTypes to member
     * newName of newClass (same parameters)
     */
    private def mapMethod(
      clazz: Symbol, name: Name, paramTypes: Array[Type],
      newClass: MsilType, newName: String) {
        mapMethod(clazz, name, paramTypes, newClass, newName, paramTypes map msilType)
      }

    /*
     * add mapping for all methods with name of clazz to the corresponding
     * method (same parameters) with newName of newClass
     */
    private def mapMethod(
      clazz: Symbol, name: Name,
      newClass: MsilType, newName: String) {
        val memberSym: Symbol = clazz.tpe.member(name)
        memberSym.tpe match {
          // alternatives: List[Symbol]
          case OverloadedType(_, alternatives) =>
            alternatives.foreach(s => mapMethod(s, newClass, newName, msilParamTypes(s)))

          // paramTypes: List[Type], resType: Type
          case MethodType(params, resType) =>
            mapMethod(memberSym, newClass, newName, msilParamTypes(memberSym))

          case _ =>
            abort("member not found: " + clazz + ", " + name)
        }
      }


    /*
     * find the method in clazz with name and paramTypes
     */
    private def lookupMethod(clazz: Symbol, name: Name, paramTypes: Array[Type]): Symbol = {
      val memberSym = clazz.tpe.member(name)
      memberSym.tpe match {
        case OverloadedType(_, alternatives) =>
          alternatives.find(s => {
            var i: Int = 0
            var typesOK: Boolean = true
            if (paramTypes.length == s.tpe.paramTypes.length) {
              while(i < paramTypes.length) {
                if (paramTypes(i) != s.tpe.paramTypes(i))
                  typesOK = false
                i += 1
              }
            } else {
              typesOK = false
            }
            typesOK
          }) match {
            case Some(sym) => sym
            case None => abort("member of " + clazz + ", " + name + "(" +
                               paramTypes + ") not found")
          }

        case MethodType(_, _) => memberSym

        case _ => abort("member not found: " + name + " of " + clazz)
      }
    }

    private def showsym(sym: Symbol): String = (sym.toString +
      "\n  symbol = " + Flags.flagsToString(sym.flags) + " " + sym +
      "\n  owner  = " + Flags.flagsToString(sym.owner.flags) + " " + sym.owner
    )

  } // class BytecodeGenerator

} // class GenMSIL

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