Switched to JNR-FFI-based native memory access.

src/main/scala/uvm/refimpl/MicroVM.scala

@@ -17,12 +17,15 @@ object MicroVM {
 class MicroVM(heapSize: Word = MicroVM.DEFAULT_HEAP_SIZE,
   globalSize: Word = MicroVM.DEFAULT_GLOBAL_SIZE,
   stackSize: Word = MicroVM.DEFAULT_STACK_SIZE) {
+  
+  // implicitly injected resources
+  private implicit val microVM = this
 
   val globalBundle = new Bundle()
-  val constantPool = new ConstantPool(this)
-  val memoryManager = new MemoryManager(heapSize, globalSize, stackSize, this)
-  val threadStackManager = new ThreadStackManager(this)
-  val trapManager = new TrapManager(this)
+  val constantPool = new ConstantPool()
+  val memoryManager = new MemoryManager(heapSize, globalSize, stackSize)
+  val threadStackManager = new ThreadStackManager()
+  val trapManager = new TrapManager()
   val clientAgents = new HashSet[ClientAgent]()
   
   val irReader = new UIRTextReader(new IDFactory())

src/main/scala/uvm/refimpl/clientInterface.scala

@@ -27,6 +27,11 @@ trait UndefinedFunctionHandler {
 }
 
 class ClientAgent(microVM: MicroVM) {
+  
+  // Injectable resources (used by memory access operations)
+  private implicit val microVM_ = microVM
+  private implicit val memorySupport = microVM.memoryManager.memorySupport
+  
   val handles = new HashSet[Handle]()
 
   microVM.clientAgents.add(this)
@@ -252,7 +257,7 @@ class ClientAgent(microVM: MicroVM) {
     val iRef = b.objRef + b.offset
     val nb = ValueBox.makeBoxForType(uty) 
     
-    MemoryOperations.load(uty, iRef, nb, microVM)
+    MemoryOperations.load(uty, iRef, nb)
 
     newHandle(uty, nb)
   }
@@ -265,7 +270,7 @@ class ClientAgent(microVM: MicroVM) {
     val nvb = newVal.vb    
     val nb = ValueBox.makeBoxForType(uty)
 
-    MemoryOperations.store(uty, iRef, nvb, nb, microVM)
+    MemoryOperations.store(uty, iRef, nvb, nb)
   }
 
   def cmpXchg(ordSucc: MemoryOrder, ordFail: MemoryOrder, weak: Boolean, loc: Handle, expected: Handle, desired: Handle): (Boolean, Handle) = {
@@ -276,7 +281,7 @@ class ClientAgent(microVM: MicroVM) {
     val eb = expected.vb
     val db = desired.vb
     val br = ValueBox.makeBoxForType(uty)
-    val succ = MemoryOperations.cmpXchg(uty, iRef, eb, db, br, microVM)
+    val succ = MemoryOperations.cmpXchg(uty, iRef, eb, db, br)
     (succ, newHandle(uty, br))
   }
 
@@ -287,7 +292,7 @@ class ClientAgent(microVM: MicroVM) {
     val iRef = lb.objRef + lb.offset
     val ob = opnd.vb
     val br = ValueBox.makeBoxForType(uty)
-    MemoryOperations.atomicRMW(uty, op, iRef, ob, br, microVM)
+    MemoryOperations.atomicRMW(uty, op, iRef, ob, br)
     newHandle(uty, br)
   }
 

src/main/scala/uvm/refimpl/exceptions.scala

@@ -19,4 +19,7 @@ class UnimplementedOprationException(message: String = null, cause: Throwable =
 class UvmRuntimeException(message: String = null, cause: Throwable = null) extends UvmRefImplException(message, cause)
 
 /** Thrown when a division by zero is executed and the exception clause is not present. */
-class UvmDivisionByZeroException(message: String = null, cause: Throwable = null) extends UvmRuntimeException(message, cause)
+class UvmDivisionByZeroException(message: String = null, cause: Throwable = null) extends UvmRuntimeException(message, cause)
\ No newline at end of file
+
+/** Thrown when accessing Mu memory but the address is outside the allocated region. */
+class UvmIllegalMemoryAccessException(message: String = null, cause: Throwable = null) extends UvmRuntimeException(message, cause)

src/main/scala/uvm/refimpl/itpr/ConstantPool.scala

@@ -6,7 +6,7 @@ import uvm.ssavariables._
 import uvm.refimpl.MicroVM
 import scala.collection.mutable.HashMap
 
-class ConstantPool(microVM: MicroVM) {
+class ConstantPool(implicit microVM: MicroVM) {
   val globalVarBoxes = HashMap[GlobalVariable, ValueBox]()
 
   def addGlobalVar(g: GlobalVariable) {

src/main/scala/uvm/refimpl/itpr/InterpreterThread.scala

@@ -15,9 +15,12 @@ object InterpreterThread {
   val logger = Logger(LoggerFactory.getLogger(getClass.getName))
 }
 
-class InterpreterThread(val id: Int, microVM: MicroVM, initialStack: InterpreterStack, val mutator: Mutator) {
+class InterpreterThread(val id: Int, implicit private val microVM: MicroVM, initialStack: InterpreterStack, val mutator: Mutator) {
   import InterpreterThread._
-
+  
+  // Injectable resources (used by memory access instructions)
+  implicit private val memorySupport = microVM.memoryManager.memorySupport
+  
   // Thread states
 
   /** The underlying stack. */
@@ -683,7 +686,7 @@ class InterpreterThread(val id: Int, microVM: MicroVM, initialStack: Interpreter
         if (la == 0L) {
           nullRefError(excClause)
         } else {
-          MemoryOperations.load(uty, la, ib, microVM)
+          MemoryOperations.load(uty, la, ib)
           continueNormally()
         }
       }
@@ -698,7 +701,7 @@ class InterpreterThread(val id: Int, microVM: MicroVM, initialStack: Interpreter
         if (la == 0L) {
           nullRefError(excClause)
         } else {
-          MemoryOperations.store(uty, la, nvb, ib, microVM)
+          MemoryOperations.store(uty, la, nvb, ib)
           continueNormally()
         }
       }
@@ -714,7 +717,7 @@ class InterpreterThread(val id: Int, microVM: MicroVM, initialStack: Interpreter
         if (la == 0L) {
           nullRefError(excClause)
         } else {
-          MemoryOperations.cmpXchg(uty, la, eb, db, ib, microVM)
+          MemoryOperations.cmpXchg(uty, la, eb, db, ib)
           continueNormally()
         }
       }
@@ -729,7 +732,7 @@ class InterpreterThread(val id: Int, microVM: MicroVM, initialStack: Interpreter
         if (la == 0L) {
           nullRefError(excClause)
         } else {
-          MemoryOperations.atomicRMW(uty, op, la, ob, ib, microVM)
+          MemoryOperations.atomicRMW(uty, op, la, ob, ib)
           continueNormally()
         }
       }

src/main/scala/uvm/refimpl/itpr/ThreadStackManager.scala

@@ -12,7 +12,7 @@ object ThreadStackManager {
   val logger = Logger(LoggerFactory.getLogger(getClass.getName))
 }
 
-class ThreadStackManager(microVM: MicroVM) {
+class ThreadStackManager(implicit microVM: MicroVM) {
   import ThreadStackManager._
 
   private val stackRegistry = new HashMap[Int, InterpreterStack]()

src/main/scala/uvm/refimpl/itpr/TrapManager.scala

@@ -3,7 +3,7 @@ package uvm.refimpl.itpr
 import uvm.refimpl._
 import scala.collection.mutable.HashSet
 
-class TrapManager(microVM: MicroVM) {
+class TrapManager(implicit microVM: MicroVM) {
   var trapHandler: TrapHandler = DefaultTrapHandler
   var undefinedFunctionHandler: UndefinedFunctionHandler = DefaultUndefinedFunctionHandler
 

src/main/scala/uvm/refimpl/mem/GlobalMemory.scala

@@ -7,9 +7,11 @@ import uvm.refimpl.mem.TypeSizes._
 import uvm.refimpl.mem.bumppointer.RewindableBumpPointerAllocator
 import java.util.HashMap
 
-class GlobalMemory(begin: Word, size: Word, microVM: MicroVM) extends Space("GlobalSpace", begin, size) {
+class GlobalMemory(begin: Word, size: Word)(
+  implicit microVM: MicroVM, memorySupport: MemorySupport)
+    extends Space("GlobalSpace", begin, size) {
 
-  val allocator = new RewindableBumpPointerAllocator(begin, size, microVM)
+  val allocator = new RewindableBumpPointerAllocator(begin, size)
 
   private val locationMap = new HashMap[GlobalCell, Word]()
 

src/main/scala/uvm/refimpl/mem/HeaderUtils.scala

@@ -6,32 +6,35 @@ import uvm.refimpl.mem.TypeSizes.Word
 import com.typesafe.scalalogging._
 import org.slf4j.LoggerFactory
 
+/**
+ * Accessors to object headers. Require MemorySupport. 
+ */
 object HeaderUtils extends StrictLogging {
 
-  def postAllocScalar(addr: Word, tag: Word) {
+  def postAllocScalar(addr: Word, tag: Word)(implicit memorySupport: MemorySupport) {
     setTag(addr, tag)
   }
 
-  def postAllocHybrid(addr: Word, tag: Word, len: Word) {
+  def postAllocHybrid(addr: Word, tag: Word, len: Word)(implicit memorySupport: MemorySupport) {
     postAllocScalar(addr, tag)
     setVarLength(addr, len)
   }
 
-  def getTag(objRef: Word): Word = {
-    MemorySupport.loadLong(objRef + TypeSizes.GC_HEADER_OFFSET_TAG)
+  def getTag(objRef: Word)(implicit memorySupport: MemorySupport): Word = {
+    memorySupport.loadLong(objRef + TypeSizes.GC_HEADER_OFFSET_TAG)
   }
 
-  def getVarLength(objRef: Word): Word = {
-    MemorySupport.loadLong(objRef + TypeSizes.GC_HEADER_OFFSET_HYBRID_LENGTH)
+  def getVarLength(objRef: Word)(implicit memorySupport: MemorySupport): Word = {
+    memorySupport.loadLong(objRef + TypeSizes.GC_HEADER_OFFSET_HYBRID_LENGTH)
   }
 
-  def setTag(objRef: Word, tag: Word) {
+  def setTag(objRef: Word, tag: Word)(implicit memorySupport: MemorySupport) {
     logger.debug("Storing tag 0x%x at addr 0x%x".format(tag, objRef + TypeSizes.GC_HEADER_OFFSET_TAG))
-    MemorySupport.storeLong(objRef + TypeSizes.GC_HEADER_OFFSET_TAG, tag)
+    memorySupport.storeLong(objRef + TypeSizes.GC_HEADER_OFFSET_TAG, tag)
   }
 
-  def setVarLength(objRef: Word, len: Word) {
-    MemorySupport.storeLong(objRef + TypeSizes.GC_HEADER_OFFSET_HYBRID_LENGTH, len)
+  def setVarLength(objRef: Word, len: Word)(implicit memorySupport: MemorySupport) {
+    memorySupport.storeLong(objRef + TypeSizes.GC_HEADER_OFFSET_HYBRID_LENGTH, len)
   }
 
   def getTypeID(tag: Word): Int = (tag & 0x00000000ffffffffL).toInt

src/main/scala/uvm/refimpl/mem/MemUtils.scala

@@ -5,22 +5,22 @@ import TypeSizes._
 
 object MemUtils extends StrictLogging {
 
-  def zeroRegion(start: Word, length: Word) {
+  def zeroRegion(start: Word, length: Word)(implicit memorySupport: MemorySupport) {
     val end = start + length
     logger.debug("Zeroing [0x%x -> 0x%x] %d bytes".format(start, end, length))
     var a = start
     while (a < end) {
-      MemorySupport.storeLong(a, 0)
+      memorySupport.storeLong(a, 0L)
       a += WORD_SIZE_BYTES
     }
   }
 
-  def memcpy(src: Word, dst: Word, length: Word) {
+  def memcpy(src: Word, dst: Word, length: Word)(implicit memorySupport: MemorySupport) {
     logger.debug("Copying [0x%x -> 0x%x] %d bytes".format(src, dst, length))
     var a: Word = 0
     while (a < length) {
-      val oldWord = MemorySupport.loadLong(src + a)
-      MemorySupport.storeLong(dst + a, oldWord)
+      val oldWord = memorySupport.loadLong(src + a)
+      memorySupport.storeLong(dst + a, oldWord)
       a += WORD_SIZE_BYTES
     }
   }

src/main/scala/uvm/refimpl/mem/MemoryManager.scala

@@ -3,23 +3,24 @@ package uvm.refimpl.mem
 import uvm.refimpl._
 import TypeSizes._
 import uvm.refimpl.mem.simpleimmix._
-import MemoryManager._
 
-object MemoryManager {
-  val MEMORY_BEGIN = 0x100000L
-}
-
-class MemoryManager(val heapSize: Word, val globalSize: Word, val stackSize: Word, microVM: MicroVM) {
-
-  val heap = new SimpleImmixHeap(MEMORY_BEGIN, heapSize, microVM)
-
-  val globalMemory = new GlobalMemory(MEMORY_BEGIN + heapSize, globalSize, microVM)
+class MemoryManager(val heapSize: Word, val globalSize: Word, val stackSize: Word)(implicit microVM: MicroVM) {
+  
+  val totalMemorySize = heapSize + globalSize
+  
+  implicit val memorySupport = new MemorySupport(totalMemorySize)  
+  
+  val memoryBegin = memorySupport.muMemoryBegin
+  val heapBegin = TypeSizes.alignUp(memoryBegin, SimpleImmixSpace.BLOCK_SIZE)
+  
+  val heap = new SimpleImmixHeap(heapBegin, heapSize)
+  val globalMemory = new GlobalMemory(heapBegin + heapSize, globalSize)
 
   def makeMutator(): Mutator = heap.makeMutator()
 
   def makeStackMemory(mutator: Mutator): StackMemory = {
     val objRef = mutator.newHybrid(InternalTypes.BYTE_ARRAY, stackSize)
-    val stackMemory = new StackMemory(objRef, stackSize, microVM)
+    val stackMemory = new StackMemory(objRef, stackSize)
     stackMemory
   }
 }

src/main/scala/uvm/refimpl/mem/MemorySupport.scala

@@ -3,100 +3,129 @@ package uvm.refimpl.mem
 import uvm.refimpl.mem.TypeSizes.Word
 import java.nio.ByteBuffer
 import uvm.ssavariables.AtomicRMWOptr._
+import jnr.ffi.{ Runtime, Memory, Pointer }
+import uvm.refimpl.UvmRuntimeException
+import uvm.refimpl.UvmIllegalMemoryAccessException
 
-object MemorySupport {
-  val MEMORY_SIZE: Word = 1024L * 1024L * 1024L
+/**
+ * Support for native memory access. Backed by JNR-FFI.
+ */
+class MemorySupport(val muMemorySize: Word) {
+  val SIZE_LIMIT: Word = Int.MaxValue.toLong
 
-  val bb: ByteBuffer = ByteBuffer.allocateDirect(MEMORY_SIZE.toInt)
-  bb.order(java.nio.ByteOrder.LITTLE_ENDIAN)
+  if (muMemorySize > SIZE_LIMIT) {
+    throw new UvmRuntimeException("Memory too large (%d bytes requested)." +
+      " Due to the limitation of JNR-FFI, the maximum available memory size is %d bytes.".format(muMemorySize, SIZE_LIMIT))
+  }
+
+  val jnrRuntime = Runtime.getSystemRuntime
+  val muMemory = Memory.allocateDirect(jnrRuntime, muMemorySize.toInt, true)
+  val muMemoryBegin = muMemory.address()
+  val muMemoryEnd = muMemoryBegin + muMemorySize
+
+  val theMemory = Pointer.wrap(jnrRuntime, 0L)
+
+  def isInMuMemory(addr: Word): Boolean = muMemoryBegin <= addr && addr < muMemoryEnd
+
+  def assertInMuMemory(inMu: Boolean, addr: Word): Unit = {
+    if (inMu && !isInMuMemory(addr)) {
+      throw new UvmIllegalMemoryAccessException("Accessed address 0x%x outside the Mu memory [0x%x-0x%x].".format(addr, muMemoryBegin, muMemoryEnd))
+    }
+  }
 
-  def loadByte(loc: Word): Byte = bb.get(loc.toInt)
-  def loadShort(loc: Word): Short = bb.getShort(loc.toInt)
-  def loadInt(loc: Word): Int = bb.getInt(loc.toInt)
-  def loadLong(loc: Word): Long = bb.getLong(loc.toInt)
-  def loadI128(loc: Word): (Long, Long) = (bb.getLong(loc.toInt), bb.getLong(loc.toInt + 8))
-  def loadFloat(loc: Word): Float = bb.getFloat(loc.toInt)
-  def loadDouble(loc: Word): Double = bb.getDouble(loc.toInt)
+  def loadByte(addr: Word, inMu: Boolean = true): Byte = { assertInMuMemory(inMu, addr); theMemory.getByte(addr) }
+  def loadShort(addr: Word, inMu: Boolean = true): Short = { assertInMuMemory(inMu, addr); theMemory.getShort(addr) }
+  def loadInt(addr: Word, inMu: Boolean = true): Int = { assertInMuMemory(inMu, addr); theMemory.getInt(addr) }
+  def loadLong(addr: Word, inMu: Boolean = true): Long = { assertInMuMemory(inMu, addr); theMemory.getLong(addr) }
+  def loadI128(addr: Word, inMu: Boolean = true): (Long, Long) = { assertInMuMemory(inMu, addr); (theMemory.getLong(addr), theMemory.getLong(addr + 8)) }
+  def loadFloat(addr: Word, inMu: Boolean = true): Float = { assertInMuMemory(inMu, addr); theMemory.getFloat(addr) }
+  def loadDouble(addr: Word, inMu: Boolean = true): Double = { assertInMuMemory(inMu, addr); theMemory.getDouble(addr) }
 
-  def storeByte(loc: Word, v: Byte): Unit = bb.put(loc.toInt, v)
-  def storeShort(loc: Word, v: Short): Unit = bb.putShort(loc.toInt, v)
-  def storeInt(loc: Word, v: Int): Unit = bb.putInt(loc.toInt, v)
-  def storeLong(loc: Word, v: Long): Unit = bb.putLong(loc.toInt, v)
-  def storeI128(loc: Word, v: (Long, Long)): Unit = { val (low, high) = v; bb.putLong(loc.toInt, low); bb.putLong(loc.toInt + 8, high) }
-  def storeFloat(loc: Word, v: Float): Unit = bb.putFloat(loc.toInt, v)
-  def storeDouble(loc: Word, v: Double): Unit = bb.putDouble(loc.toInt, v)
+  def storeByte(addr: Word, v: Byte, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putByte(addr, v) }
+  def storeShort(addr: Word, v: Short, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putShort(addr, v) }
+  def storeInt(addr: Word, v: Int, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putInt(addr, v) }
+  def storeLong(addr: Word, v: Long, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putLong(addr, v) }
+  def storeI128(addr: Word, v: (Long, Long), inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); val (low, high) = v; theMemory.putLong(addr, low); theMemory.putLong(addr + 8, high) }
+  def storeFloat(addr: Word, v: Float, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putFloat(addr, v) }
+  def storeDouble(addr: Word, v: Double, inMu: Boolean = true): Unit = { assertInMuMemory(inMu, addr); theMemory.putDouble(addr, v) }
 
-  def cmpXchgInt(loc: Word, expected: Int, desired: Int): (Boolean, Int) = {
-    val oldVal = loadInt(loc)
+  def cmpXchgInt(addr: Word, expected: Int, desired: Int, inMu: Boolean = true): (Boolean, Int) = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadInt(addr)
     if (oldVal == expected) {
-      storeInt(loc, desired)
+      storeInt(addr, desired)
       return (true, oldVal)
     } else {
       return (false, oldVal)
     }
   }
 
-  def cmpXchgLong(loc: Word, expected: Long, desired: Long): (Boolean, Long) = {
-    val oldVal = loadLong(loc)
+  def cmpXchgLong(addr: Word, expected: Long, desired: Long, inMu: Boolean = true): (Boolean, Long) = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadLong(addr)
     if (oldVal == expected) {
-      storeLong(loc, desired)
+      storeLong(addr, desired)
       return (true, oldVal)
     } else {
       return (false, oldVal)
     }
   }
 
-  def cmpXchgI128(loc: Word, expected: (Long, Long), desired: (Long, Long)): (Boolean, (Long, Long)) = {
-    val oldVal = loadI128(loc)
+  def cmpXchgI128(addr: Word, expected: (Long, Long), desired: (Long, Long), inMu: Boolean = true): (Boolean, (Long, Long)) = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadI128(addr)
     if (oldVal == expected) {
-      storeI128(loc, desired)
+      storeI128(addr, desired)
       return (true, oldVal)
     } else {
       return (false, oldVal)
     }
   }
 
-  def atomicRMWInt(optr: AtomicRMWOptr, loc: Word, opnd: Int): Int = {
-    val oldVal = loadInt(loc)
+  def atomicRMWInt(optr: AtomicRMWOptr, addr: Word, opnd: Int, inMu: Boolean = true): Int = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadInt(addr)
     val newVal = optr match {
       case XCHG => opnd
-      case ADD => oldVal + opnd
-      case SUB => oldVal - opnd
-      case AND => oldVal & opnd
+      case ADD  => oldVal + opnd
+      case SUB  => oldVal - opnd
+      case AND  => oldVal & opnd
       case NAND => ~(oldVal & opnd)
-      case OR => oldVal | opnd
-      case XOR => oldVal ^ opnd
-      case MAX => Math.max(oldVal, opnd)
-      case MIN => Math.min(oldVal, opnd)
+      case OR   => oldVal | opnd
+      case XOR  => oldVal ^ opnd
+      case MAX  => Math.max(oldVal, opnd)
+      case MIN  => Math.min(oldVal, opnd)
       case UMAX => Math.max(oldVal - Int.MinValue, opnd - Int.MinValue) + Int.MinValue
       case UMIN => Math.min(oldVal - Int.MinValue, opnd - Int.MinValue) + Int.MinValue
     }
-    storeInt(loc, newVal)
+    storeInt(addr, newVal)
     return oldVal
   }
 
-  def atomicRMWLong(optr: AtomicRMWOptr, loc: Word, opnd: Long): Long = {
-    val oldVal = loadLong(loc)
+  def atomicRMWLong(optr: AtomicRMWOptr, addr: Word, opnd: Long, inMu: Boolean = true): Long = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadLong(addr)
     val newVal = optr match {
       case XCHG => opnd
-      case ADD => oldVal + opnd
-      case SUB => oldVal - opnd
-      case AND => oldVal & opnd
+      case ADD  => oldVal + opnd
+      case SUB  => oldVal - opnd
+      case AND  => oldVal & opnd
       case NAND => ~(oldVal & opnd)
-      case OR => oldVal | opnd
-      case XOR => oldVal ^ opnd
-      case MAX => Math.max(oldVal, opnd)
-      case MIN => Math.min(oldVal, opnd)
+      case OR   => oldVal | opnd
+      case XOR  => oldVal ^ opnd
+      case MAX  => Math.max(oldVal, opnd)
+      case MIN  => Math.min(oldVal, opnd)
       case UMAX => Math.max(oldVal - Long.MinValue, opnd - Long.MinValue) + Long.MinValue
       case UMIN => Math.min(oldVal - Long.MinValue, opnd - Long.MinValue) + Long.MinValue
     }
-    storeLong(loc, newVal)
+    storeLong(addr, newVal)
     return oldVal
   }
 
-  def xchgI128(loc: Word, desired: (Long, Long)): (Long, Long) = {
-    val oldVal = loadI128(loc)
-    storeI128(loc, desired)
+  def xchgI128(addr: Word, desired: (Long, Long), inMu: Boolean = true): (Long, Long) = {
+    assertInMuMemory(inMu, addr)
+    val oldVal = loadI128(addr)
+    storeI128(addr, desired)
     return oldVal
   }
-}
+}
\ No newline at end of file

src/main/scala/uvm/refimpl/mem/Mutator.scala

@@ -3,7 +3,7 @@ package uvm.refimpl.mem
 import uvm.types._
 import TypeSizes._
 
-abstract class Mutator {
+abstract class Mutator(implicit memorySupport: MemorySupport) {
 
   def alloc(size: Word, align: Word, headerSize: Word): Word
 

src/main/scala/uvm/refimpl/mem/StackMemory.scala

@@ -9,5 +9,6 @@ import TypeSizes.Word
  * <p>
  * If the stack is Dead, the stackObjRef will be a dangling pointer.
  */
-class StackMemory(val stackObjRef: Word, extend: Word, microVM: MicroVM)
-    extends RewindableBumpPointerAllocator(stackObjRef, extend, microVM)
+class StackMemory(val stackObjRef: Word, extend: Word)(
+    implicit microVM: MicroVM, memorySupport: MemorySupport)
+    extends RewindableBumpPointerAllocator(stackObjRef, extend)

src/main/scala/uvm/refimpl/mem/bumppointer/RewindableBumpPointerAllocator.scala

@@ -14,8 +14,9 @@ object RewindableBumpPointerAllocator {
   val logger: Logger = Logger(LoggerFactory.getLogger(getClass.getName))
 }
 
-class RewindableBumpPointerAllocator(val begin: Word, val extend: Word, val microVM: MicroVM)
-  extends Allocator {
+class RewindableBumpPointerAllocator(val begin: Word, val extend: Word)(
+  implicit microVM: MicroVM, memorySupport: MemorySupport)
+    extends Allocator {
   import RewindableBumpPointerAllocator._