diff --git a/llvm/lib/Bytecode/Reader/Reader.cpp b/llvm/lib/Bytecode/Reader/Reader.cpp
index 2ca8a99..353f29c 100644
--- a/llvm/lib/Bytecode/Reader/Reader.cpp
+++ b/llvm/lib/Bytecode/Reader/Reader.cpp
@@ -16,45 +16,163 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "ReaderInternals.h"
-#include "llvm/Bytecode/Reader.h"
+#include "Reader.h"
+#include "llvm/Bytecode/BytecodeHandler.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Constants.h"
+#include "llvm/iMemory.h"
+#include "llvm/iOther.h"
+#include "llvm/iPHINode.h"
+#include "llvm/iTerminators.h"
 #include "llvm/Bytecode/Format.h"
-#include "llvm/Module.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
 #include "Support/StringExtras.h"
+#include <sstream>
+
 using namespace llvm;
 
-unsigned BytecodeParser::getTypeSlot(const Type *Ty) {
-  if (Ty->isPrimitiveType())
-    return Ty->getTypeID();
+/// A convenience macro for calling the handler. Makes maintenance easier in
+/// case the interface to handler methods changes.
+#define HANDLE(method) \
+  if ( Handler ) Handler->handle ## method
 
-  // Scan the compaction table for the type if needed.
-  if (CompactionTable.size() > Type::TypeTyID) {
-    std::vector<Value*> &Plane = CompactionTable[Type::TypeTyID];
-    if (!Plane.empty()) {
-      std::vector<Value*>::iterator I = find(Plane.begin(), Plane.end(),
-                                             const_cast<Type*>(Ty));
-      if (I == Plane.end())
-        throw std::string("Couldn't find type specified in compaction table!");
-      return Type::FirstDerivedTyID + (&*I - &Plane[0]);
-    }
+/// A convenience macro for handling parsing errors.
+#define PARSE_ERROR(inserters) { \
+    std::ostringstream errormsg; \
+    errormsg << inserters; \
+    throw std::string(errormsg.str()); \
   }
 
-  // Check the function level types first...
-  TypeValuesListTy::iterator I = find(FunctionTypeValues.begin(),
-                                      FunctionTypeValues.end(), Ty);
-  if (I != FunctionTypeValues.end())
-    return Type::FirstDerivedTyID + ModuleTypeValues.size() +
-             (&*I - &FunctionTypeValues[0]);
+/// @brief A class for maintaining the slot number definition
+/// as a placeholder for the actual definition.
+template<class SuperType>
+class PlaceholderDef : public SuperType {
+  unsigned ID;
+  PlaceholderDef();                       // DO NOT IMPLEMENT
+  void operator=(const PlaceholderDef &); // DO NOT IMPLEMENT
+public:
+  PlaceholderDef(const Type *Ty, unsigned id) : SuperType(Ty), ID(id) {}
+  unsigned getID() { return ID; }
+};
 
-  I = find(ModuleTypeValues.begin(), ModuleTypeValues.end(), Ty);
-  if (I == ModuleTypeValues.end())
-    throw std::string("Didn't find type in ModuleTypeValues.");
-  return Type::FirstDerivedTyID + (&*I - &ModuleTypeValues[0]);
+struct ConstantPlaceHolderHelper : public ConstantExpr {
+  ConstantPlaceHolderHelper(const Type *Ty)
+    : ConstantExpr(Instruction::UserOp1, Constant::getNullValue(Ty), Ty) {}
+};
+
+typedef PlaceholderDef<ConstantPlaceHolderHelper>  ConstPHolder;
+
+//===----------------------------------------------------------------------===//
+// Bytecode Reading Methods
+//===----------------------------------------------------------------------===//
+
+inline bool BytecodeReader::moreInBlock() {
+  return At < BlockEnd;
 }
 
-const Type *BytecodeParser::getType(unsigned ID) {
-  //cerr << "Looking up Type ID: " << ID << "\n";
+inline void BytecodeReader::checkPastBlockEnd(const char * block_name) {
+  if ( At > BlockEnd )
+    PARSE_ERROR("Attempt to read past the end of " << block_name << " block.");
+}
 
+inline void BytecodeReader::align32() {
+  BufPtr Save = At;
+  At = (const unsigned char *)((unsigned long)(At+3) & (~3UL));
+  if ( At > Save ) 
+    HANDLE(Alignment( At - Save ));
+  if (At > BlockEnd) 
+    PARSE_ERROR("Ran out of data while aligning!");
+}
+
+inline unsigned BytecodeReader::read_uint() {
+  if (At+4 > BlockEnd) 
+    PARSE_ERROR("Ran out of data reading uint!");
+  At += 4;
+  return At[-4] | (At[-3] << 8) | (At[-2] << 16) | (At[-1] << 24);
+}
+
+inline unsigned BytecodeReader::read_vbr_uint() {
+  unsigned Shift = 0;
+  unsigned Result = 0;
+  BufPtr Save = At;
+  
+  do {
+    if (At == BlockEnd) 
+      PARSE_ERROR("Ran out of data reading vbr_uint!");
+    Result |= (unsigned)((*At++) & 0x7F) << Shift;
+    Shift += 7;
+  } while (At[-1] & 0x80);
+  HANDLE(VBR32(At-Save));
+  return Result;
+}
+
+inline uint64_t BytecodeReader::read_vbr_uint64() {
+  unsigned Shift = 0;
+  uint64_t Result = 0;
+  BufPtr Save = At;
+  
+  do {
+    if (At == BlockEnd) 
+      PARSE_ERROR("Ran out of data reading vbr_uint64!");
+    Result |= (uint64_t)((*At++) & 0x7F) << Shift;
+    Shift += 7;
+  } while (At[-1] & 0x80);
+  HANDLE(VBR64(At-Save));
+  return Result;
+}
+
+inline int64_t BytecodeReader::read_vbr_int64() {
+  uint64_t R = read_vbr_uint64();
+  if (R & 1) {
+    if (R != 1)
+      return -(int64_t)(R >> 1);
+    else   // There is no such thing as -0 with integers.  "-0" really means
+           // 0x8000000000000000.
+      return 1LL << 63;
+  } else
+    return  (int64_t)(R >> 1);
+}
+
+inline std::string BytecodeReader::read_str() {
+  unsigned Size = read_vbr_uint();
+  const unsigned char *OldAt = At;
+  At += Size;
+  if (At > BlockEnd)             // Size invalid?
+    PARSE_ERROR("Ran out of data reading a string!");
+  return std::string((char*)OldAt, Size);
+}
+
+inline void BytecodeReader::read_data(void *Ptr, void *End) {
+  unsigned char *Start = (unsigned char *)Ptr;
+  unsigned Amount = (unsigned char *)End - Start;
+  if (At+Amount > BlockEnd) 
+    PARSE_ERROR("Ran out of data!");
+  std::copy(At, At+Amount, Start);
+  At += Amount;
+}
+
+inline void BytecodeReader::read_block(unsigned &Type, unsigned &Size) {
+  Type = read_uint();
+  Size = read_uint();
+  BlockStart = At;
+  if ( At + Size > BlockEnd )
+    PARSE_ERROR("Attempt to size a block past end of memory");
+  BlockEnd = At + Size;
+  HANDLE(Block( Type, BlockStart, Size ));
+}
+
+//===----------------------------------------------------------------------===//
+// IR Lookup Methods
+//===----------------------------------------------------------------------===//
+
+inline bool BytecodeReader::hasImplicitNull(unsigned TyID ) {
+  if (!hasExplicitPrimitiveZeros)
+    return TyID != Type::LabelTyID && TyID != Type::TypeTyID &&
+           TyID != Type::VoidTyID;
+  return TyID >= Type::FirstDerivedTyID;
+}
+
+const Type *BytecodeReader::getType(unsigned ID) {
   if (ID < Type::FirstDerivedTyID)
     if (const Type *T = Type::getPrimitiveType((Type::TypeID)ID))
       return T;   // Asked for a primitive type...
@@ -62,98 +180,124 @@
   // Otherwise, derived types need offset...
   ID -= Type::FirstDerivedTyID;
 
-  if (CompactionTable.size() > Type::TypeTyID &&
-      !CompactionTable[Type::TypeTyID].empty()) {
-    if (ID >= CompactionTable[Type::TypeTyID].size())
-      throw std::string("Type ID out of range for compaction table!");
-    return cast<Type>(CompactionTable[Type::TypeTyID][ID]);
+  if (!CompactionTypes.empty()) {
+    if (ID >= CompactionTypes.size())
+      PARSE_ERROR("Type ID out of range for compaction table!");
+    return CompactionTypes[ID];
   }
 
   // Is it a module-level type?
-  if (ID < ModuleTypeValues.size())
-    return ModuleTypeValues[ID].get();
+    if (ID < ModuleTypes.size())
+      return ModuleTypes[ID].get();
 
-  // Nope, is it a function-level type?
-  ID -= ModuleTypeValues.size();
-  if (ID < FunctionTypeValues.size())
-    return FunctionTypeValues[ID].get();
+    // Nope, is it a function-level type?
+    ID -= ModuleTypes.size();
+    if (ID < FunctionTypes.size())
+      return FunctionTypes[ID].get();
 
-  throw std::string("Illegal type reference!");
+    PARSE_ERROR("Illegal type reference!");
+    return Type::VoidTy;
 }
 
-static inline bool hasImplicitNull(unsigned TyID, bool EncodesPrimitiveZeros) {
-  if (!EncodesPrimitiveZeros)
-    return TyID != Type::LabelTyID && TyID != Type::TypeTyID &&
-           TyID != Type::VoidTyID;
-  return TyID >= Type::FirstDerivedTyID;
+unsigned BytecodeReader::getTypeSlot(const Type *Ty) {
+  if (Ty->isPrimitiveType())
+    return Ty->getTypeID();
+
+  // Scan the compaction table for the type if needed.
+  if (!CompactionTypes.empty()) {
+      std::vector<const Type*>::const_iterator I = 
+	find(CompactionTypes.begin(), CompactionTypes.end(), Ty);
+
+      if (I == CompactionTypes.end())
+	PARSE_ERROR("Couldn't find type specified in compaction table!");
+      return Type::FirstDerivedTyID + (&*I - &CompactionTypes[0]);
+  }
+
+  // Check the function level types first...
+  TypeListTy::iterator I = find(FunctionTypes.begin(), FunctionTypes.end(), Ty);
+
+  if (I != FunctionTypes.end())
+    return Type::FirstDerivedTyID + ModuleTypes.size() +
+	     (&*I - &FunctionTypes[0]);
+
+  // Check the module level types now...
+  I = find(ModuleTypes.begin(), ModuleTypes.end(), Ty);
+  if (I == ModuleTypes.end())
+    PARSE_ERROR("Didn't find type in ModuleTypes.");
+  return Type::FirstDerivedTyID + (&*I - &ModuleTypes[0]);
 }
 
-unsigned BytecodeParser::insertValue(Value *Val, unsigned type,
-                                     ValueTable &ValueTab) {
-  assert((!isa<Constant>(Val) || !cast<Constant>(Val)->isNullValue()) ||
-          !hasImplicitNull(type, hasExplicitPrimitiveZeros) &&
-         "Cannot read null values from bytecode!");
-  assert(type != Type::TypeTyID && "Types should never be insertValue'd!");
-
-  if (ValueTab.size() <= type)
-    ValueTab.resize(type+1);
-
-  if (!ValueTab[type]) ValueTab[type] = new ValueList();
-
-  //cerr << "insertValue Values[" << type << "][" << ValueTab[type].size() 
-  //   << "] = " << Val << "\n";
-  ValueTab[type]->push_back(Val);
-
-  bool HasOffset = hasImplicitNull(type, hasExplicitPrimitiveZeros);
-  return ValueTab[type]->size()-1 + HasOffset;
+const Type *BytecodeReader::getGlobalTableType(unsigned Slot) {
+  if (Slot < Type::FirstDerivedTyID) {
+    const Type *Ty = Type::getPrimitiveType((Type::TypeID)Slot);
+    assert(Ty && "Not a primitive type ID?");
+    return Ty;
+  }
+  Slot -= Type::FirstDerivedTyID;
+  if (Slot >= ModuleTypes.size())
+    PARSE_ERROR("Illegal compaction table type reference!");
+  return ModuleTypes[Slot];
 }
 
-Value *BytecodeParser::getValue(unsigned type, unsigned oNum, bool Create) {
+unsigned BytecodeReader::getGlobalTableTypeSlot(const Type *Ty) {
+  if (Ty->isPrimitiveType())
+    return Ty->getTypeID();
+  TypeListTy::iterator I = find(ModuleTypes.begin(),
+				      ModuleTypes.end(), Ty);
+  if (I == ModuleTypes.end())
+    PARSE_ERROR("Didn't find type in ModuleTypes.");
+  return Type::FirstDerivedTyID + (&*I - &ModuleTypes[0]);
+}
+
+Value * BytecodeReader::getValue(unsigned type, unsigned oNum, bool Create) {
   assert(type != Type::TypeTyID && "getValue() cannot get types!");
   assert(type != Type::LabelTyID && "getValue() cannot get blocks!");
   unsigned Num = oNum;
 
   // If there is a compaction table active, it defines the low-level numbers.
   // If not, the module values define the low-level numbers.
-  if (CompactionTable.size() > type && !CompactionTable[type].empty()) {
-    if (Num < CompactionTable[type].size())
-      return CompactionTable[type][Num];
-    Num -= CompactionTable[type].size();
+  if (CompactionValues.size() > type && !CompactionValues[type].empty()) {
+    if (Num < CompactionValues[type].size())
+      return CompactionValues[type][Num];
+    Num -= CompactionValues[type].size();
   } else {
-    // If the type plane was compactified, figure out the global type ID.
+    // By default, the global type id is the type id passed in
     unsigned GlobalTyID = type;
-    if (CompactionTable.size() > Type::TypeTyID &&
-        !CompactionTable[Type::TypeTyID].empty() &&
-        type >= Type::FirstDerivedTyID) {
-      std::vector<Value*> &TypePlane = CompactionTable[Type::TypeTyID];
-      const Type *Ty = cast<Type>(TypePlane[type-Type::FirstDerivedTyID]);
-      TypeValuesListTy::iterator I =
-        find(ModuleTypeValues.begin(), ModuleTypeValues.end(), Ty);
-      assert(I != ModuleTypeValues.end());
-      GlobalTyID = Type::FirstDerivedTyID + (&*I - &ModuleTypeValues[0]);
+
+    // If the type plane was compactified, figure out the global type ID
+    // by adding the derived type ids and the distance.
+    if (CompactionValues.size() > Type::TypeTyID &&
+	!CompactionTypes.empty() &&
+	type >= Type::FirstDerivedTyID) {
+      const Type *Ty = CompactionTypes[type-Type::FirstDerivedTyID];
+      TypeListTy::iterator I = 
+	find(ModuleTypes.begin(), ModuleTypes.end(), Ty);
+      assert(I != ModuleTypes.end());
+      GlobalTyID = Type::FirstDerivedTyID + (&*I - &ModuleTypes[0]);
     }
 
-    if (hasImplicitNull(GlobalTyID, hasExplicitPrimitiveZeros)) {
+    if (hasImplicitNull(GlobalTyID)) {
       if (Num == 0)
-        return Constant::getNullValue(getType(type));
+	return Constant::getNullValue(getType(type));
       --Num;
     }
 
     if (GlobalTyID < ModuleValues.size() && ModuleValues[GlobalTyID]) {
       if (Num < ModuleValues[GlobalTyID]->size())
-        return ModuleValues[GlobalTyID]->getOperand(Num);
+	return ModuleValues[GlobalTyID]->getOperand(Num);
       Num -= ModuleValues[GlobalTyID]->size();
     }
   }
 
-  if (Values.size() > type && Values[type] && Num < Values[type]->size())
-    return Values[type]->getOperand(Num);
+  if (FunctionValues.size() > type && 
+      FunctionValues[type] && 
+      Num < FunctionValues[type]->size())
+    return FunctionValues[type]->getOperand(Num);
 
   if (!Create) return 0;  // Do not create a placeholder?
 
   std::pair<unsigned,unsigned> KeyValue(type, oNum);
-  std::map<std::pair<unsigned,unsigned>, Value*>::iterator I = 
-    ForwardReferences.lower_bound(KeyValue);
+  ForwardReferenceMap::iterator I = ForwardReferences.lower_bound(KeyValue);
   if (I != ForwardReferences.end() && I->first == KeyValue)
     return I->second;   // We have already created this placeholder
 
@@ -162,11 +306,445 @@
   return Val;
 }
 
+Value* BytecodeReader::getGlobalTableValue(const Type *Ty, unsigned SlotNo) {
+  // FIXME: getTypeSlot is inefficient!
+  unsigned TyID = getGlobalTableTypeSlot(Ty);
+  
+  if (TyID != Type::LabelTyID) {
+    if (SlotNo == 0)
+      return Constant::getNullValue(Ty);
+    --SlotNo;
+  }
+
+  if (TyID >= ModuleValues.size() || ModuleValues[TyID] == 0 ||
+      SlotNo >= ModuleValues[TyID]->size()) {
+    PARSE_ERROR("Corrupt compaction table entry!" 
+	<< TyID << ", " << SlotNo << ": " << ModuleValues.size() << ", "
+	<< (void*)ModuleValues[TyID] << ", "
+	<< ModuleValues[TyID]->size() << "\n");
+  }
+  return ModuleValues[TyID]->getOperand(SlotNo);
+}
+
+Constant* BytecodeReader::getConstantValue(unsigned TypeSlot, unsigned Slot) {
+  if (Value *V = getValue(TypeSlot, Slot, false))
+    if (Constant *C = dyn_cast<Constant>(V))
+      return C;   // If we already have the value parsed, just return it
+    else if (GlobalValue *GV = dyn_cast<GlobalValue>(V))
+      // ConstantPointerRef's are an abomination, but at least they don't have
+      // to infest bytecode files.
+      return ConstantPointerRef::get(GV);
+    else
+      PARSE_ERROR("Reference of a value is expected to be a constant!");
+
+  const Type *Ty = getType(TypeSlot);
+  std::pair<const Type*, unsigned> Key(Ty, Slot);
+  ConstantRefsType::iterator I = ConstantFwdRefs.lower_bound(Key);
+
+  if (I != ConstantFwdRefs.end() && I->first == Key) {
+    return I->second;
+  } else {
+    // Create a placeholder for the constant reference and
+    // keep track of the fact that we have a forward ref to recycle it
+    Constant *C = new ConstPHolder(Ty, Slot);
+    
+    // Keep track of the fact that we have a forward ref to recycle it
+    ConstantFwdRefs.insert(I, std::make_pair(Key, C));
+    return C;
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// IR Construction Methods
+//===----------------------------------------------------------------------===//
+
+unsigned BytecodeReader::insertValue(
+    Value *Val, unsigned type, ValueTable &ValueTab) {
+  assert((!isa<Constant>(Val) || !cast<Constant>(Val)->isNullValue()) ||
+	  !hasImplicitNull(type) &&
+	 "Cannot read null values from bytecode!");
+  assert(type != Type::TypeTyID && "Types should never be insertValue'd!");
+
+  if (ValueTab.size() <= type)
+    ValueTab.resize(type+1);
+
+  if (!ValueTab[type]) ValueTab[type] = new ValueList();
+
+  ValueTab[type]->push_back(Val);
+
+  bool HasOffset = hasImplicitNull(type);
+  return ValueTab[type]->size()-1 + HasOffset;
+}
+
+void BytecodeReader::insertArguments(Function* F ) {
+  const FunctionType *FT = F->getFunctionType();
+  Function::aiterator AI = F->abegin();
+  for (FunctionType::param_iterator It = FT->param_begin();
+       It != FT->param_end(); ++It, ++AI)
+    insertValue(AI, getTypeSlot(AI->getType()), FunctionValues);
+}
+
+//===----------------------------------------------------------------------===//
+// Bytecode Parsing Methods
+//===----------------------------------------------------------------------===//
+
+void BytecodeReader::ParseInstruction(std::vector<unsigned> &Oprnds,
+                                              BasicBlock* BB) {
+  BufPtr SaveAt = At;
+
+  // Clear instruction data
+  Oprnds.clear();
+  unsigned iType = 0;
+  unsigned Opcode = 0;
+  unsigned Op = read_uint();
+
+  // bits   Instruction format:        Common to all formats
+  // --------------------------
+  // 01-00: Opcode type, fixed to 1.
+  // 07-02: Opcode
+  Opcode    = (Op >> 2) & 63;
+  Oprnds.resize((Op >> 0) & 03);
+
+  // Extract the operands
+  switch (Oprnds.size()) {
+  case 1:
+    // bits   Instruction format:
+    // --------------------------
+    // 19-08: Resulting type plane
+    // 31-20: Operand #1 (if set to (2^12-1), then zero operands)
+    //
+    iType   = (Op >>  8) & 4095;
+    Oprnds[0] = (Op >> 20) & 4095;
+    if (Oprnds[0] == 4095)    // Handle special encoding for 0 operands...
+      Oprnds.resize(0);
+    break;
+  case 2:
+    // bits   Instruction format:
+    // --------------------------
+    // 15-08: Resulting type plane
+    // 23-16: Operand #1
+    // 31-24: Operand #2  
+    //
+    iType   = (Op >>  8) & 255;
+    Oprnds[0] = (Op >> 16) & 255;
+    Oprnds[1] = (Op >> 24) & 255;
+    break;
+  case 3:
+    // bits   Instruction format:
+    // --------------------------
+    // 13-08: Resulting type plane
+    // 19-14: Operand #1
+    // 25-20: Operand #2
+    // 31-26: Operand #3
+    //
+    iType   = (Op >>  8) & 63;
+    Oprnds[0] = (Op >> 14) & 63;
+    Oprnds[1] = (Op >> 20) & 63;
+    Oprnds[2] = (Op >> 26) & 63;
+    break;
+  case 0:
+    At -= 4;  // Hrm, try this again...
+    Opcode = read_vbr_uint();
+    Opcode >>= 2;
+    iType = read_vbr_uint();
+
+    unsigned NumOprnds = read_vbr_uint();
+    Oprnds.resize(NumOprnds);
+
+    if (NumOprnds == 0)
+      PARSE_ERROR("Zero-argument instruction found; this is invalid.");
+
+    for (unsigned i = 0; i != NumOprnds; ++i)
+      Oprnds[i] = read_vbr_uint();
+    align32();
+    break;
+  }
+
+  // Get the type of the instruction
+  const Type *InstTy = getType(iType);
+
+  // Hae enough to inform the handler now
+  HANDLE(Instruction(Opcode, InstTy, Oprnds, At-SaveAt));
+
+  // Declare the resulting instruction we'll build.
+  Instruction *Result = 0;
+
+  // Handle binary operators
+  if (Opcode >= Instruction::BinaryOpsBegin &&
+      Opcode <  Instruction::BinaryOpsEnd  && Oprnds.size() == 2)
+    Result = BinaryOperator::create((Instruction::BinaryOps)Opcode,
+                                    getValue(iType, Oprnds[0]),
+                                    getValue(iType, Oprnds[1]));
+
+  switch (Opcode) {
+  default: 
+    if (Result == 0) PARSE_ERROR("Illegal instruction read!");
+    break;
+  case Instruction::VAArg:
+    Result = new VAArgInst(getValue(iType, Oprnds[0]), getType(Oprnds[1]));
+    break;
+  case Instruction::VANext:
+    Result = new VANextInst(getValue(iType, Oprnds[0]), getType(Oprnds[1]));
+    break;
+  case Instruction::Cast:
+    Result = new CastInst(getValue(iType, Oprnds[0]), getType(Oprnds[1]));
+    break;
+  case Instruction::Select:
+    Result = new SelectInst(getValue(Type::BoolTyID, Oprnds[0]),
+                            getValue(iType, Oprnds[1]),
+                            getValue(iType, Oprnds[2]));
+    break;
+  case Instruction::PHI: {
+    if (Oprnds.size() == 0 || (Oprnds.size() & 1))
+      PARSE_ERROR("Invalid phi node encountered!\n");
+
+    PHINode *PN = new PHINode(InstTy);
+    PN->op_reserve(Oprnds.size());
+    for (unsigned i = 0, e = Oprnds.size(); i != e; i += 2)
+      PN->addIncoming(getValue(iType, Oprnds[i]), getBasicBlock(Oprnds[i+1]));
+    Result = PN;
+    break;
+  }
+
+  case Instruction::Shl:
+  case Instruction::Shr:
+    Result = new ShiftInst((Instruction::OtherOps)Opcode,
+                           getValue(iType, Oprnds[0]),
+                           getValue(Type::UByteTyID, Oprnds[1]));
+    break;
+  case Instruction::Ret:
+    if (Oprnds.size() == 0)
+      Result = new ReturnInst();
+    else if (Oprnds.size() == 1)
+      Result = new ReturnInst(getValue(iType, Oprnds[0]));
+    else
+      PARSE_ERROR("Unrecognized instruction!");
+    break;
+
+  case Instruction::Br:
+    if (Oprnds.size() == 1)
+      Result = new BranchInst(getBasicBlock(Oprnds[0]));
+    else if (Oprnds.size() == 3)
+      Result = new BranchInst(getBasicBlock(Oprnds[0]), 
+	  getBasicBlock(Oprnds[1]), getValue(Type::BoolTyID , Oprnds[2]));
+    else
+      PARSE_ERROR("Invalid number of operands for a 'br' instruction!");
+    break;
+  case Instruction::Switch: {
+    if (Oprnds.size() & 1)
+      PARSE_ERROR("Switch statement with odd number of arguments!");
+
+    SwitchInst *I = new SwitchInst(getValue(iType, Oprnds[0]),
+                                   getBasicBlock(Oprnds[1]));
+    for (unsigned i = 2, e = Oprnds.size(); i != e; i += 2)
+      I->addCase(cast<Constant>(getValue(iType, Oprnds[i])),
+                 getBasicBlock(Oprnds[i+1]));
+    Result = I;
+    break;
+  }
+
+  case Instruction::Call: {
+    if (Oprnds.size() == 0)
+      PARSE_ERROR("Invalid call instruction encountered!");
+
+    Value *F = getValue(iType, Oprnds[0]);
+
+    // Check to make sure we have a pointer to function type
+    const PointerType *PTy = dyn_cast<PointerType>(F->getType());
+    if (PTy == 0) PARSE_ERROR("Call to non function pointer value!");
+    const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
+    if (FTy == 0) PARSE_ERROR("Call to non function pointer value!");
+
+    std::vector<Value *> Params;
+    if (!FTy->isVarArg()) {
+      FunctionType::param_iterator It = FTy->param_begin();
+
+      for (unsigned i = 1, e = Oprnds.size(); i != e; ++i) {
+        if (It == FTy->param_end())
+          PARSE_ERROR("Invalid call instruction!");
+        Params.push_back(getValue(getTypeSlot(*It++), Oprnds[i]));
+      }
+      if (It != FTy->param_end())
+        PARSE_ERROR("Invalid call instruction!");
+    } else {
+      Oprnds.erase(Oprnds.begin(), Oprnds.begin()+1);
+
+      unsigned FirstVariableOperand;
+      if (Oprnds.size() < FTy->getNumParams())
+        PARSE_ERROR("Call instruction missing operands!");
+
+      // Read all of the fixed arguments
+      for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
+        Params.push_back(getValue(getTypeSlot(FTy->getParamType(i)),Oprnds[i]));
+      
+      FirstVariableOperand = FTy->getNumParams();
+
+      if ((Oprnds.size()-FirstVariableOperand) & 1) // Must be pairs of type/value
+        PARSE_ERROR("Invalid call instruction!");
+        
+      for (unsigned i = FirstVariableOperand, e = Oprnds.size(); 
+	   i != e; i += 2)
+        Params.push_back(getValue(Oprnds[i], Oprnds[i+1]));
+    }
+
+    Result = new CallInst(F, Params);
+    break;
+  }
+  case Instruction::Invoke: {
+    if (Oprnds.size() < 3) PARSE_ERROR("Invalid invoke instruction!");
+    Value *F = getValue(iType, Oprnds[0]);
+
+    // Check to make sure we have a pointer to function type
+    const PointerType *PTy = dyn_cast<PointerType>(F->getType());
+    if (PTy == 0) PARSE_ERROR("Invoke to non function pointer value!");
+    const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
+    if (FTy == 0) PARSE_ERROR("Invoke to non function pointer value!");
+
+    std::vector<Value *> Params;
+    BasicBlock *Normal, *Except;
+
+    if (!FTy->isVarArg()) {
+      Normal = getBasicBlock(Oprnds[1]);
+      Except = getBasicBlock(Oprnds[2]);
+
+      FunctionType::param_iterator It = FTy->param_begin();
+      for (unsigned i = 3, e = Oprnds.size(); i != e; ++i) {
+        if (It == FTy->param_end())
+          PARSE_ERROR("Invalid invoke instruction!");
+        Params.push_back(getValue(getTypeSlot(*It++), Oprnds[i]));
+      }
+      if (It != FTy->param_end())
+        PARSE_ERROR("Invalid invoke instruction!");
+    } else {
+      Oprnds.erase(Oprnds.begin(), Oprnds.begin()+1);
+
+      Normal = getBasicBlock(Oprnds[0]);
+      Except = getBasicBlock(Oprnds[1]);
+      
+      unsigned FirstVariableArgument = FTy->getNumParams()+2;
+      for (unsigned i = 2; i != FirstVariableArgument; ++i)
+        Params.push_back(getValue(getTypeSlot(FTy->getParamType(i-2)),
+                                  Oprnds[i]));
+      
+      if (Oprnds.size()-FirstVariableArgument & 1) // Must be type/value pairs
+        PARSE_ERROR("Invalid invoke instruction!");
+
+      for (unsigned i = FirstVariableArgument; i < Oprnds.size(); i += 2)
+        Params.push_back(getValue(Oprnds[i], Oprnds[i+1]));
+    }
+
+    Result = new InvokeInst(F, Normal, Except, Params);
+    break;
+  }
+  case Instruction::Malloc:
+    if (Oprnds.size() > 2) PARSE_ERROR("Invalid malloc instruction!");
+    if (!isa<PointerType>(InstTy))
+      PARSE_ERROR("Invalid malloc instruction!");
+
+    Result = new MallocInst(cast<PointerType>(InstTy)->getElementType(),
+                            Oprnds.size() ? getValue(Type::UIntTyID,
+                                                   Oprnds[0]) : 0);
+    break;
+
+  case Instruction::Alloca:
+    if (Oprnds.size() > 2) PARSE_ERROR("Invalid alloca instruction!");
+    if (!isa<PointerType>(InstTy))
+      PARSE_ERROR("Invalid alloca instruction!");
+
+    Result = new AllocaInst(cast<PointerType>(InstTy)->getElementType(),
+                            Oprnds.size() ? getValue(Type::UIntTyID, 
+			    Oprnds[0]) :0);
+    break;
+  case Instruction::Free:
+    if (!isa<PointerType>(InstTy))
+      PARSE_ERROR("Invalid free instruction!");
+    Result = new FreeInst(getValue(iType, Oprnds[0]));
+    break;
+  case Instruction::GetElementPtr: {
+    if (Oprnds.size() == 0 || !isa<PointerType>(InstTy))
+      PARSE_ERROR("Invalid getelementptr instruction!");
+
+    std::vector<Value*> Idx;
+
+    const Type *NextTy = InstTy;
+    for (unsigned i = 1, e = Oprnds.size(); i != e; ++i) {
+      const CompositeType *TopTy = dyn_cast_or_null<CompositeType>(NextTy);
+      if (!TopTy) PARSE_ERROR("Invalid getelementptr instruction!"); 
+
+      unsigned ValIdx = Oprnds[i];
+      unsigned IdxTy = 0;
+      if (!hasRestrictedGEPTypes) {
+        // Struct indices are always uints, sequential type indices can be any
+        // of the 32 or 64-bit integer types.  The actual choice of type is
+        // encoded in the low two bits of the slot number.
+        if (isa<StructType>(TopTy))
+          IdxTy = Type::UIntTyID;
+        else {
+          switch (ValIdx & 3) {
+          default:
+          case 0: IdxTy = Type::UIntTyID; break;
+          case 1: IdxTy = Type::IntTyID; break;
+          case 2: IdxTy = Type::ULongTyID; break;
+          case 3: IdxTy = Type::LongTyID; break;
+          }
+          ValIdx >>= 2;
+        }
+      } else {
+        IdxTy = isa<StructType>(TopTy) ? Type::UByteTyID : Type::LongTyID;
+      }
+
+      Idx.push_back(getValue(IdxTy, ValIdx));
+
+      // Convert ubyte struct indices into uint struct indices.
+      if (isa<StructType>(TopTy) && hasRestrictedGEPTypes)
+        if (ConstantUInt *C = dyn_cast<ConstantUInt>(Idx.back()))
+          Idx[Idx.size()-1] = ConstantExpr::getCast(C, Type::UIntTy);
+
+      NextTy = GetElementPtrInst::getIndexedType(InstTy, Idx, true);
+    }
+
+    Result = new GetElementPtrInst(getValue(iType, Oprnds[0]), Idx);
+    break;
+  }
+
+  case 62:   // volatile load
+  case Instruction::Load:
+    if (Oprnds.size() != 1 || !isa<PointerType>(InstTy))
+      PARSE_ERROR("Invalid load instruction!");
+    Result = new LoadInst(getValue(iType, Oprnds[0]), "", Opcode == 62);
+    break;
+
+  case 63:   // volatile store 
+  case Instruction::Store: {
+    if (!isa<PointerType>(InstTy) || Oprnds.size() != 2)
+      PARSE_ERROR("Invalid store instruction!");
+
+    Value *Ptr = getValue(iType, Oprnds[1]);
+    const Type *ValTy = cast<PointerType>(Ptr->getType())->getElementType();
+    Result = new StoreInst(getValue(getTypeSlot(ValTy), Oprnds[0]), Ptr,
+                           Opcode == 63);
+    break;
+  }
+  case Instruction::Unwind:
+    if (Oprnds.size() != 0) PARSE_ERROR("Invalid unwind instruction!");
+    Result = new UnwindInst();
+    break;
+  }  // end switch(Opcode) 
+
+  unsigned TypeSlot;
+  if (Result->getType() == InstTy)
+    TypeSlot = iType;
+  else
+    TypeSlot = getTypeSlot(Result->getType());
+
+  insertValue(Result, TypeSlot, FunctionValues);
+  BB->getInstList().push_back(Result);
+}
+
 /// getBasicBlock - Get a particular numbered basic block, which might be a
 /// forward reference.  This works together with ParseBasicBlock to handle these
 /// forward references in a clean manner.
-///
-BasicBlock *BytecodeParser::getBasicBlock(unsigned ID) {
+BasicBlock *BytecodeReader::getBasicBlock(unsigned ID) {
   // Make sure there is room in the table...
   if (ParsedBasicBlocks.size() <= ID) ParsedBasicBlocks.resize(ID+1);
 
@@ -181,48 +759,13 @@
   return ParsedBasicBlocks[ID] = new BasicBlock();
 }
 
-/// getConstantValue - Just like getValue, except that it returns a null pointer
-/// only on error.  It always returns a constant (meaning that if the value is
-/// defined, but is not a constant, that is an error).  If the specified
-/// constant hasn't been parsed yet, a placeholder is defined and used.  Later,
-/// after the real value is parsed, the placeholder is eliminated.
-///
-Constant *BytecodeParser::getConstantValue(unsigned TypeSlot, unsigned Slot) {
-  if (Value *V = getValue(TypeSlot, Slot, false))
-    if (Constant *C = dyn_cast<Constant>(V))
-      return C;   // If we already have the value parsed, just return it
-    else if (GlobalValue *GV = dyn_cast<GlobalValue>(V))
-      // ConstantPointerRef's are an abomination, but at least they don't have
-      // to infest bytecode files.
-      return ConstantPointerRef::get(GV);
-    else
-      throw std::string("Reference of a value is expected to be a constant!");
-
-  const Type *Ty = getType(TypeSlot);
-  std::pair<const Type*, unsigned> Key(Ty, Slot);
-  ConstantRefsType::iterator I = ConstantFwdRefs.lower_bound(Key);
-
-  if (I != ConstantFwdRefs.end() && I->first == Key) {
-    BCR_TRACE(5, "Previous forward ref found!\n");
-    return I->second;
-  } else {
-    // Create a placeholder for the constant reference and
-    // keep track of the fact that we have a forward ref to recycle it
-    BCR_TRACE(5, "Creating new forward ref to a constant!\n");
-    Constant *C = new ConstPHolder(Ty, Slot);
-    
-    // Keep track of the fact that we have a forward ref to recycle it
-    ConstantFwdRefs.insert(I, std::make_pair(Key, C));
-    return C;
-  }
-}
-
 /// ParseBasicBlock - In LLVM 1.0 bytecode files, we used to output one
 /// basicblock at a time.  This method reads in one of the basicblock packets.
-BasicBlock *BytecodeParser::ParseBasicBlock(const unsigned char *&Buf,
-                                            const unsigned char *EndBuf,
-                                            unsigned BlockNo) {
-  BasicBlock *BB;
+BasicBlock *BytecodeReader::ParseBasicBlock( unsigned BlockNo) {
+  HANDLE(BasicBlockBegin( BlockNo ));
+
+  BasicBlock *BB = 0;
+
   if (ParsedBasicBlocks.size() == BlockNo)
     ParsedBasicBlocks.push_back(BB = new BasicBlock());
   else if (ParsedBasicBlocks[BlockNo] == 0)
@@ -230,24 +773,23 @@
   else
     BB = ParsedBasicBlocks[BlockNo];
 
-  std::vector<unsigned> Args;
-  while (Buf < EndBuf)
-    ParseInstruction(Buf, EndBuf, Args, BB);
+  std::vector<unsigned> Operands;
+  while ( moreInBlock() )
+    ParseInstruction(Operands, BB);
 
+  HANDLE(BasicBlockEnd( BlockNo ));
   return BB;
 }
 
-
 /// ParseInstructionList - Parse all of the BasicBlock's & Instruction's in the
 /// body of a function.  In post 1.0 bytecode files, we no longer emit basic
 /// block individually, in order to avoid per-basic-block overhead.
-unsigned BytecodeParser::ParseInstructionList(Function *F,
-                                              const unsigned char *&Buf,
-                                              const unsigned char *EndBuf) {
+unsigned BytecodeReader::ParseInstructionList(Function* F) {
   unsigned BlockNo = 0;
   std::vector<unsigned> Args;
 
-  while (Buf < EndBuf) {
+  while ( moreInBlock() ) {
+    HANDLE(BasicBlockBegin( BlockNo ));
     BasicBlock *BB;
     if (ParsedBasicBlocks.size() == BlockNo)
       ParsedBasicBlocks.push_back(BB = new BasicBlock());
@@ -255,24 +797,25 @@
       BB = ParsedBasicBlocks[BlockNo] = new BasicBlock();
     else
       BB = ParsedBasicBlocks[BlockNo];
+    HANDLE(BasicBlockEnd( BlockNo ));
     ++BlockNo;
     F->getBasicBlockList().push_back(BB);
 
     // Read instructions into this basic block until we get to a terminator
-    while (Buf < EndBuf && !BB->getTerminator())
-      ParseInstruction(Buf, EndBuf, Args, BB);
+    while ( moreInBlock() && !BB->getTerminator())
+      ParseInstruction(Args, BB);
 
     if (!BB->getTerminator())
-      throw std::string("Non-terminated basic block found!");
+      PARSE_ERROR("Non-terminated basic block found!");
   }
 
   return BlockNo;
 }
 
-void BytecodeParser::ParseSymbolTable(const unsigned char *&Buf,
-                                      const unsigned char *EndBuf,
-                                      SymbolTable *ST,
-                                      Function *CurrentFunction) {
+void BytecodeReader::ParseSymbolTable(Function *CurrentFunction,
+				      SymbolTable *ST) {
+  HANDLE(SymbolTableBegin(CurrentFunction,ST));
+
   // Allow efficient basic block lookup by number.
   std::vector<BasicBlock*> BBMap;
   if (CurrentFunction)
@@ -280,18 +823,16 @@
            E = CurrentFunction->end(); I != E; ++I)
       BBMap.push_back(I);
 
-  while (Buf < EndBuf) {
+  while ( moreInBlock() ) {
     // Symtab block header: [num entries][type id number]
-    unsigned NumEntries = read_vbr_uint(Buf, EndBuf);
-    unsigned Typ = read_vbr_uint(Buf, EndBuf);
+    unsigned NumEntries = read_vbr_uint();
+    unsigned Typ = read_vbr_uint();
     const Type *Ty = getType(Typ);
-    BCR_TRACE(3, "Plane Type: '" << *Ty << "' with " << NumEntries <<
-                 " entries\n");
 
     for (unsigned i = 0; i != NumEntries; ++i) {
       // Symtab entry: [def slot #][name]
-      unsigned slot = read_vbr_uint(Buf, EndBuf);
-      std::string Name = read_str(Buf, EndBuf);
+      unsigned slot = read_vbr_uint();
+      std::string Name = read_str();
 
       Value *V = 0;
       if (Typ == Type::TypeTyID)
@@ -303,76 +844,444 @@
         V = getValue(Typ, slot, false); // Find mapping...
       }
       if (V == 0)
-        throw "Failed value look-up for name '" + Name + "'";
-      BCR_TRACE(4, "Map: '" << Name << "' to #" << slot << ":" << *V;
-                if (!isa<Instruction>(V)) std::cerr << "\n");
+        PARSE_ERROR("Failed value look-up for name '" << Name << "'");
 
       V->setName(Name, ST);
     }
   }
-
-  if (Buf > EndBuf) throw std::string("Tried to read past end of buffer.");
+  checkPastBlockEnd("Symbol Table");
+  HANDLE(SymbolTableEnd());
 }
 
-void BytecodeParser::ResolveReferencesToConstant(Constant *NewV, unsigned Slot){
+void BytecodeReader::ParseCompactionTable() {
+
+  HANDLE(CompactionTableBegin());
+
+  while ( moreInBlock() ) {
+    unsigned NumEntries = read_vbr_uint();
+    unsigned Ty;
+
+    if ((NumEntries & 3) == 3) {
+      NumEntries >>= 2;
+      Ty = read_vbr_uint();
+    } else {
+      Ty = NumEntries >> 2;
+      NumEntries &= 3;
+    }
+
+    if (Ty >= CompactionValues.size())
+      CompactionValues.resize(Ty+1);
+
+    if (!CompactionValues[Ty].empty())
+      PARSE_ERROR("Compaction table plane contains multiple entries!");
+
+    HANDLE(CompactionTablePlane( Ty, NumEntries ));
+
+    if (Ty == Type::TypeTyID) {
+      for (unsigned i = 0; i != NumEntries; ++i) {
+        unsigned TypeSlot = read_vbr_uint();
+        const Type *Typ = getGlobalTableType(TypeSlot);
+        CompactionTypes.push_back(Typ);
+        HANDLE(CompactionTableType( i, TypeSlot, Typ ));
+      }
+      CompactionTypes.resize(NumEntries+Type::FirstDerivedTyID);
+    } else {
+      const Type *Typ = getType(Ty);
+      // Push the implicit zero
+      CompactionValues[Ty].push_back(Constant::getNullValue(Typ));
+      for (unsigned i = 0; i != NumEntries; ++i) {
+        unsigned ValSlot = read_vbr_uint();
+        Value *V = getGlobalTableValue(Typ, ValSlot);
+        CompactionValues[Ty].push_back(V);
+        HANDLE(CompactionTableValue( i, Ty, ValSlot, Typ ));
+      }
+    }
+  }
+  HANDLE(CompactionTableEnd());
+}
+    
+// Parse a single type constant.
+const Type *BytecodeReader::ParseTypeConstant() {
+  unsigned PrimType = read_vbr_uint();
+
+  const Type *Result = 0;
+  if ((Result = Type::getPrimitiveType((Type::TypeID)PrimType)))
+    return Result;
+  
+  switch (PrimType) {
+  case Type::FunctionTyID: {
+    const Type *RetType = getType(read_vbr_uint());
+
+    unsigned NumParams = read_vbr_uint();
+
+    std::vector<const Type*> Params;
+    while (NumParams--)
+      Params.push_back(getType(read_vbr_uint()));
+
+    bool isVarArg = Params.size() && Params.back() == Type::VoidTy;
+    if (isVarArg) Params.pop_back();
+
+    Result = FunctionType::get(RetType, Params, isVarArg);
+    break;
+  }
+  case Type::ArrayTyID: {
+    unsigned ElTyp = read_vbr_uint();
+    const Type *ElementType = getType(ElTyp);
+
+    unsigned NumElements = read_vbr_uint();
+
+    Result =  ArrayType::get(ElementType, NumElements);
+    break;
+  }
+  case Type::StructTyID: {
+    std::vector<const Type*> Elements;
+    unsigned Typ = read_vbr_uint();
+    while (Typ) {         // List is terminated by void/0 typeid
+      Elements.push_back(getType(Typ));
+      Typ = read_vbr_uint();
+    }
+
+    Result = StructType::get(Elements);
+    break;
+  }
+  case Type::PointerTyID: {
+    unsigned ElTyp = read_vbr_uint();
+    Result = PointerType::get(getType(ElTyp));
+    break;
+  }
+
+  case Type::OpaqueTyID: {
+    Result = OpaqueType::get();
+    break;
+  }
+
+  default:
+    PARSE_ERROR("Don't know how to deserialize primitive type" << PrimType << "\n");
+    break;
+  }
+  HANDLE(Type( Result ));
+  return Result;
+}
+
+// ParseTypeConstants - We have to use this weird code to handle recursive
+// types.  We know that recursive types will only reference the current slab of
+// values in the type plane, but they can forward reference types before they
+// have been read.  For example, Type #0 might be '{ Ty#1 }' and Type #1 might
+// be 'Ty#0*'.  When reading Type #0, type number one doesn't exist.  To fix
+// this ugly problem, we pessimistically insert an opaque type for each type we
+// are about to read.  This means that forward references will resolve to
+// something and when we reread the type later, we can replace the opaque type
+// with a new resolved concrete type.
+//
+void BytecodeReader::ParseTypeConstants(TypeListTy &Tab, unsigned NumEntries){
+  assert(Tab.size() == 0 && "should not have read type constants in before!");
+
+  // Insert a bunch of opaque types to be resolved later...
+  Tab.reserve(NumEntries);
+  for (unsigned i = 0; i != NumEntries; ++i)
+    Tab.push_back(OpaqueType::get());
+
+  // Loop through reading all of the types.  Forward types will make use of the
+  // opaque types just inserted.
+  //
+  for (unsigned i = 0; i != NumEntries; ++i) {
+    const Type *NewTy = ParseTypeConstant(), *OldTy = Tab[i].get();
+    if (NewTy == 0) PARSE_ERROR("Couldn't parse type!");
+
+    // Don't directly push the new type on the Tab. Instead we want to replace 
+    // the opaque type we previously inserted with the new concrete value. This
+    // approach helps with forward references to types. The refinement from the
+    // abstract (opaque) type to the new type causes all uses of the abstract
+    // type to use the concrete type (NewTy). This will also cause the opaque
+    // type to be deleted.
+    cast<DerivedType>(const_cast<Type*>(OldTy))->refineAbstractTypeTo(NewTy);
+
+    // This should have replaced the old opaque type with the new type in the
+    // value table... or with a preexisting type that was already in the system.
+    // Let's just make sure it did.
+    assert(Tab[i] != OldTy && "refineAbstractType didn't work!");
+  }
+}
+
+Constant *BytecodeReader::ParseConstantValue( unsigned TypeID) {
+  // We must check for a ConstantExpr before switching by type because
+  // a ConstantExpr can be of any type, and has no explicit value.
+  // 
+  // 0 if not expr; numArgs if is expr
+  unsigned isExprNumArgs = read_vbr_uint();
+  
+  if (isExprNumArgs) {
+    // FIXME: Encoding of constant exprs could be much more compact!
+    std::vector<Constant*> ArgVec;
+    ArgVec.reserve(isExprNumArgs);
+    unsigned Opcode = read_vbr_uint();
+    
+    // Read the slot number and types of each of the arguments
+    for (unsigned i = 0; i != isExprNumArgs; ++i) {
+      unsigned ArgValSlot = read_vbr_uint();
+      unsigned ArgTypeSlot = read_vbr_uint();
+      
+      // Get the arg value from its slot if it exists, otherwise a placeholder
+      ArgVec.push_back(getConstantValue(ArgTypeSlot, ArgValSlot));
+    }
+    
+    // Construct a ConstantExpr of the appropriate kind
+    if (isExprNumArgs == 1) {           // All one-operand expressions
+      assert(Opcode == Instruction::Cast);
+      Constant* Result = ConstantExpr::getCast(ArgVec[0], getType(TypeID));
+      HANDLE(ConstantExpression(Opcode, ArgVec, Result));
+      return Result;
+    } else if (Opcode == Instruction::GetElementPtr) { // GetElementPtr
+      std::vector<Constant*> IdxList(ArgVec.begin()+1, ArgVec.end());
+
+      if (hasRestrictedGEPTypes) {
+        const Type *BaseTy = ArgVec[0]->getType();
+        generic_gep_type_iterator<std::vector<Constant*>::iterator>
+          GTI = gep_type_begin(BaseTy, IdxList.begin(), IdxList.end()),
+          E = gep_type_end(BaseTy, IdxList.begin(), IdxList.end());
+        for (unsigned i = 0; GTI != E; ++GTI, ++i)
+          if (isa<StructType>(*GTI)) {
+            if (IdxList[i]->getType() != Type::UByteTy)
+              PARSE_ERROR("Invalid index for getelementptr!");
+            IdxList[i] = ConstantExpr::getCast(IdxList[i], Type::UIntTy);
+          }
+      }
+
+      Constant* Result = ConstantExpr::getGetElementPtr(ArgVec[0], IdxList);
+      HANDLE(ConstantExpression(Opcode, ArgVec, Result));
+      return Result;
+    } else if (Opcode == Instruction::Select) {
+      assert(ArgVec.size() == 3);
+      Constant* Result = ConstantExpr::getSelect(ArgVec[0], ArgVec[1], 
+	                                         ArgVec[2]);
+      HANDLE(ConstantExpression(Opcode, ArgVec, Result));
+      return Result;
+    } else {                            // All other 2-operand expressions
+      Constant* Result = ConstantExpr::get(Opcode, ArgVec[0], ArgVec[1]);
+      HANDLE(ConstantExpression(Opcode, ArgVec, Result));
+      return Result;
+    }
+  }
+  
+  // Ok, not an ConstantExpr.  We now know how to read the given type...
+  const Type *Ty = getType(TypeID);
+  switch (Ty->getTypeID()) {
+  case Type::BoolTyID: {
+    unsigned Val = read_vbr_uint();
+    if (Val != 0 && Val != 1) 
+      PARSE_ERROR("Invalid boolean value read.");
+    Constant* Result = ConstantBool::get(Val == 1);
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::UByteTyID:   // Unsigned integer types...
+  case Type::UShortTyID:
+  case Type::UIntTyID: {
+    unsigned Val = read_vbr_uint();
+    if (!ConstantUInt::isValueValidForType(Ty, Val)) 
+      PARSE_ERROR("Invalid unsigned byte/short/int read.");
+    Constant* Result =  ConstantUInt::get(Ty, Val);
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::ULongTyID: {
+    Constant* Result = ConstantUInt::get(Ty, read_vbr_uint64());
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::SByteTyID:   // Signed integer types...
+  case Type::ShortTyID:
+  case Type::IntTyID: {
+  case Type::LongTyID:
+    int64_t Val = read_vbr_int64();
+    if (!ConstantSInt::isValueValidForType(Ty, Val)) 
+      PARSE_ERROR("Invalid signed byte/short/int/long read.");
+    Constant* Result = ConstantSInt::get(Ty, Val);
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::FloatTyID: {
+    float F;
+    read_data(&F, &F+1);
+    Constant* Result = ConstantFP::get(Ty, F);
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::DoubleTyID: {
+    double Val;
+    read_data(&Val, &Val+1);
+    Constant* Result = ConstantFP::get(Ty, Val);
+    HANDLE(ConstantValue(Result));
+    return Result;
+  }
+
+  case Type::TypeTyID:
+    PARSE_ERROR("Type constants shouldn't live in constant table!");
+    break;
+
+  case Type::ArrayTyID: {
+    const ArrayType *AT = cast<ArrayType>(Ty);
+    unsigned NumElements = AT->getNumElements();
+    unsigned TypeSlot = getTypeSlot(AT->getElementType());
+    std::vector<Constant*> Elements;
+    Elements.reserve(NumElements);
+    while (NumElements--)     // Read all of the elements of the constant.
+      Elements.push_back(getConstantValue(TypeSlot,
+                                          read_vbr_uint()));
+    Constant* Result = ConstantArray::get(AT, Elements);
+    HANDLE(ConstantArray(AT, Elements, TypeSlot, Result));
+    return Result;
+  }
+
+  case Type::StructTyID: {
+    const StructType *ST = cast<StructType>(Ty);
+
+    std::vector<Constant *> Elements;
+    Elements.reserve(ST->getNumElements());
+    for (unsigned i = 0; i != ST->getNumElements(); ++i)
+      Elements.push_back(getConstantValue(ST->getElementType(i),
+                                          read_vbr_uint()));
+
+    Constant* Result = ConstantStruct::get(ST, Elements);
+    HANDLE(ConstantStruct(ST, Elements, Result));
+    return Result;
+  }    
+
+  case Type::PointerTyID: {  // ConstantPointerRef value...
+    const PointerType *PT = cast<PointerType>(Ty);
+    unsigned Slot = read_vbr_uint();
+    
+    // Check to see if we have already read this global variable...
+    Value *Val = getValue(TypeID, Slot, false);
+    GlobalValue *GV;
+    if (Val) {
+      if (!(GV = dyn_cast<GlobalValue>(Val))) 
+        PARSE_ERROR("Value of ConstantPointerRef not in ValueTable!");
+    } else {
+      PARSE_ERROR("Forward references are not allowed here.");
+    }
+    
+    Constant* Result = ConstantPointerRef::get(GV);
+    HANDLE(ConstantPointer(PT, Slot, GV, Result));
+    return Result;
+  }
+
+  default:
+    PARSE_ERROR("Don't know how to deserialize constant value of type '"+
+                      Ty->getDescription());
+    break;
+  }
+}
+
+void BytecodeReader::ResolveReferencesToConstant(Constant *NewV, unsigned Slot){
   ConstantRefsType::iterator I =
     ConstantFwdRefs.find(std::make_pair(NewV->getType(), Slot));
   if (I == ConstantFwdRefs.end()) return;   // Never forward referenced?
 
-  BCR_TRACE(3, "Mutating forward refs!\n");
   Value *PH = I->second;   // Get the placeholder...
   PH->replaceAllUsesWith(NewV);
   delete PH;                               // Delete the old placeholder
   ConstantFwdRefs.erase(I);                // Remove the map entry for it
 }
 
-void BytecodeParser::ParseFunction(const unsigned char *&Buf,
-                                   const unsigned char *EndBuf) {
-  if (FunctionSignatureList.empty())
-    throw std::string("FunctionSignatureList empty!");
+void BytecodeReader::ParseStringConstants(unsigned NumEntries, ValueTable &Tab){
+  for (; NumEntries; --NumEntries) {
+    unsigned Typ = read_vbr_uint();
+    const Type *Ty = getType(Typ);
+    if (!isa<ArrayType>(Ty))
+      PARSE_ERROR("String constant data invalid!");
+    
+    const ArrayType *ATy = cast<ArrayType>(Ty);
+    if (ATy->getElementType() != Type::SByteTy &&
+        ATy->getElementType() != Type::UByteTy)
+      PARSE_ERROR("String constant data invalid!");
+    
+    // Read character data.  The type tells us how long the string is.
+    char Data[ATy->getNumElements()]; 
+    read_data(Data, Data+ATy->getNumElements());
 
-  Function *F = FunctionSignatureList.back();
-  FunctionSignatureList.pop_back();
+    std::vector<Constant*> Elements(ATy->getNumElements());
+    if (ATy->getElementType() == Type::SByteTy)
+      for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i)
+        Elements[i] = ConstantSInt::get(Type::SByteTy, (signed char)Data[i]);
+    else
+      for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i)
+        Elements[i] = ConstantUInt::get(Type::UByteTy, (unsigned char)Data[i]);
 
-  // Save the information for future reading of the function
-  LazyFunctionLoadMap[F] = LazyFunctionInfo(Buf, EndBuf);
-  // Pretend we've `parsed' this function
-  Buf = EndBuf;
+    // Create the constant, inserting it as needed.
+    Constant *C = ConstantArray::get(ATy, Elements);
+    unsigned Slot = insertValue(C, Typ, Tab);
+    ResolveReferencesToConstant(C, Slot);
+    HANDLE(ConstantString(cast<ConstantArray>(C)));
+  }
 }
 
-void BytecodeParser::materializeFunction(Function* F) {
-  // Find {start, end} pointers and slot in the map. If not there, we're done.
-  std::map<Function*, LazyFunctionInfo>::iterator Fi =
-    LazyFunctionLoadMap.find(F);
-  if (Fi == LazyFunctionLoadMap.end()) return;
+void BytecodeReader::ParseConstantPool(ValueTable &Tab, 
+                                       TypeListTy &TypeTab) {
+  HANDLE(GlobalConstantsBegin());
+  while ( moreInBlock() ) {
+    unsigned NumEntries = read_vbr_uint();
+    unsigned Typ = read_vbr_uint();
+    if (Typ == Type::TypeTyID) {
+      ParseTypeConstants(TypeTab, NumEntries);
+    } else if (Typ == Type::VoidTyID) {
+      assert(&Tab == &ModuleValues && "Cannot read strings in functions!");
+      ParseStringConstants(NumEntries, Tab);
+    } else {
+      for (unsigned i = 0; i < NumEntries; ++i) {
+        Constant *C = ParseConstantValue(Typ);
+        assert(C && "ParseConstantValue returned NULL!");
+        unsigned Slot = insertValue(C, Typ, Tab);
 
-  const unsigned char *Buf = Fi->second.Buf;
-  const unsigned char *EndBuf = Fi->second.EndBuf;
-  LazyFunctionLoadMap.erase(Fi);
+        // If we are reading a function constant table, make sure that we adjust
+        // the slot number to be the real global constant number.
+        //
+        if (&Tab != &ModuleValues && Typ < ModuleValues.size() &&
+            ModuleValues[Typ])
+          Slot += ModuleValues[Typ]->size();
+        ResolveReferencesToConstant(C, Slot);
+      }
+    }
+  }
+  checkPastBlockEnd("Constant Pool");
+  HANDLE(GlobalConstantsEnd());
+}
 
+void BytecodeReader::ParseFunctionBody(Function* F ) {
+
+  unsigned FuncSize = BlockEnd - At;
   GlobalValue::LinkageTypes Linkage = GlobalValue::ExternalLinkage;
 
-  unsigned LinkageType = read_vbr_uint(Buf, EndBuf);
-  if (LinkageType > 4)
-    throw std::string("Invalid linkage type for Function.");
+  unsigned LinkageType = read_vbr_uint();
   switch (LinkageType) {
   case 0: Linkage = GlobalValue::ExternalLinkage; break;
   case 1: Linkage = GlobalValue::WeakLinkage; break;
   case 2: Linkage = GlobalValue::AppendingLinkage; break;
   case 3: Linkage = GlobalValue::InternalLinkage; break;
   case 4: Linkage = GlobalValue::LinkOnceLinkage; break;
+  default:
+    PARSE_ERROR("Invalid linkage type for Function.");
+    Linkage = GlobalValue::InternalLinkage;
+    break;
   }
 
-  F->setLinkage(Linkage);
+  F->setLinkage( Linkage );
+  HANDLE(FunctionBegin(F,FuncSize));
 
   // Keep track of how many basic blocks we have read in...
   unsigned BlockNum = 0;
   bool InsertedArguments = false;
 
-  while (Buf < EndBuf) {
+  BufPtr MyEnd = BlockEnd;
+  while ( At < MyEnd ) {
     unsigned Type, Size;
-    const unsigned char *OldBuf = Buf;
-    readBlock(Buf, EndBuf, Type, Size);
+    BufPtr OldAt = At;
+    read_block(Type, Size);
 
     switch (Type) {
     case BytecodeFormat::ConstantPool:
@@ -380,21 +1289,15 @@
         // Insert arguments into the value table before we parse the first basic
         // block in the function, but after we potentially read in the
         // compaction table.
-        const FunctionType *FT = F->getFunctionType();
-        Function::aiterator AI = F->abegin();
-        for (FunctionType::param_iterator It = FT->param_begin();
-             It != FT->param_end(); ++It, ++AI)
-          insertValue(AI, getTypeSlot(AI->getType()), Values);
+	insertArguments(F);
         InsertedArguments = true;
       }
 
-      BCR_TRACE(2, "BLOCK BytecodeFormat::ConstantPool: {\n");
-      ParseConstantPool(Buf, Buf+Size, Values, FunctionTypeValues);
+      ParseConstantPool(FunctionValues, FunctionTypes);
       break;
 
     case BytecodeFormat::CompactionTable:
-      BCR_TRACE(2, "BLOCK BytecodeFormat::CompactionTable: {\n");
-      ParseCompactionTable(Buf, Buf+Size);
+      ParseCompactionTable();
       break;
 
     case BytecodeFormat::BasicBlock: {
@@ -402,16 +1305,11 @@
         // Insert arguments into the value table before we parse the first basic
         // block in the function, but after we potentially read in the
         // compaction table.
-        const FunctionType *FT = F->getFunctionType();
-        Function::aiterator AI = F->abegin();
-        for (FunctionType::param_iterator It = FT->param_begin();
-             It != FT->param_end(); ++It, ++AI)
-          insertValue(AI, getTypeSlot(AI->getType()), Values);
+	insertArguments(F);
         InsertedArguments = true;
       }
 
-      BCR_TRACE(2, "BLOCK BytecodeFormat::BasicBlock: {\n");
-      BasicBlock *BB = ParseBasicBlock(Buf, Buf+Size, BlockNum++);
+      BasicBlock *BB = ParseBasicBlock(BlockNum++);
       F->getBasicBlockList().push_back(BB);
       break;
     }
@@ -421,41 +1319,36 @@
       // list for the function, but after we potentially read in the compaction
       // table.
       if (!InsertedArguments) {
-        const FunctionType *FT = F->getFunctionType();
-        Function::aiterator AI = F->abegin();
-        for (FunctionType::param_iterator It = FT->param_begin();
-             It != FT->param_end(); ++It, ++AI)
-          insertValue(AI, getTypeSlot(AI->getType()), Values);
+	insertArguments(F);
         InsertedArguments = true;
       }
 
-      BCR_TRACE(2, "BLOCK BytecodeFormat::InstructionList: {\n");
-      if (BlockNum) throw std::string("Already parsed basic blocks!");
-      BlockNum = ParseInstructionList(F, Buf, Buf+Size);
+      if (BlockNum) 
+	PARSE_ERROR("Already parsed basic blocks!");
+      BlockNum = ParseInstructionList(F);
       break;
     }
 
     case BytecodeFormat::SymbolTable:
-      BCR_TRACE(2, "BLOCK BytecodeFormat::SymbolTable: {\n");
-      ParseSymbolTable(Buf, Buf+Size, &F->getSymbolTable(), F);
+      ParseSymbolTable(F, &F->getSymbolTable());
       break;
 
     default:
-      BCR_TRACE(2, "BLOCK <unknown>:ignored! {\n");
-      Buf += Size;
-      if (OldBuf > Buf) 
-        throw std::string("Wrapped around reading bytecode.");
+      At += Size;
+      if (OldAt > At) 
+        PARSE_ERROR("Wrapped around reading bytecode.");
       break;
     }
-    BCR_TRACE(2, "} end block\n");
+    BlockEnd = MyEnd;
 
     // Malformed bc file if read past end of block.
-    align32(Buf, EndBuf);
+    align32();
   }
 
   // Make sure there were no references to non-existant basic blocks.
   if (BlockNum != ParsedBasicBlocks.size())
-    throw std::string("Illegal basic block operand reference");
+    PARSE_ERROR("Illegal basic block operand reference");
+
   ParsedBasicBlocks.clear();
 
   // Resolve forward references.  Replace any uses of a forward reference value
@@ -496,128 +1389,152 @@
   }
 
   // Clear out function-level types...
-  FunctionTypeValues.clear();
-  CompactionTable.clear();
-  freeTable(Values);
+  FunctionTypes.clear();
+  CompactionTypes.clear();
+  CompactionValues.clear();
+  freeTable(FunctionValues);
+
+  HANDLE(FunctionEnd(F));
 }
 
-void BytecodeParser::ParseCompactionTable(const unsigned char *&Buf,
-                                          const unsigned char *End) {
+void BytecodeReader::ParseFunctionLazily() {
+  if (FunctionSignatureList.empty())
+    PARSE_ERROR("FunctionSignatureList empty!");
 
-  while (Buf != End) {
-    unsigned NumEntries = read_vbr_uint(Buf, End);
-    unsigned Ty;
+  Function *Func = FunctionSignatureList.back();
+  FunctionSignatureList.pop_back();
 
-    if ((NumEntries & 3) == 3) {
-      NumEntries >>= 2;
-      Ty = read_vbr_uint(Buf, End);
-    } else {
-      Ty = NumEntries >> 2;
-      NumEntries &= 3;
-    }
+  // Save the information for future reading of the function
+  LazyFunctionLoadMap[Func] = LazyFunctionInfo(BlockStart, BlockEnd);
 
-    if (Ty >= CompactionTable.size())
-      CompactionTable.resize(Ty+1);
+  // Pretend we've `parsed' this function
+  At = BlockEnd;
+}
 
-    if (!CompactionTable[Ty].empty())
-      throw std::string("Compaction table plane contains multiple entries!");
-    
-    if (Ty == Type::TypeTyID) {
-      for (unsigned i = 0; i != NumEntries; ++i) {
-        const Type *Typ = getGlobalTableType(read_vbr_uint(Buf, End));
-        CompactionTable[Type::TypeTyID].push_back(const_cast<Type*>(Typ));
-      }
+void BytecodeReader::ParseFunction(Function* Func) {
+  // Find {start, end} pointers and slot in the map. If not there, we're done.
+  LazyFunctionMap::iterator Fi = LazyFunctionLoadMap.find(Func);
 
-      CompactionTable.resize(NumEntries+Type::FirstDerivedTyID);
-    } else {
-      const Type *Typ = getType(Ty);
-      // Push the implicit zero
-      CompactionTable[Ty].push_back(Constant::getNullValue(Typ));
-      for (unsigned i = 0; i != NumEntries; ++i) {
-        Value *V = getGlobalTableValue(Typ, read_vbr_uint(Buf, End));
-        CompactionTable[Ty].push_back(V);
-      }
-    }
+  // Make sure we found it
+  if ( Fi == LazyFunctionLoadMap.end() ) {
+    PARSE_ERROR("Unrecognized function of type " << Func->getType()->getDescription());
+    return;
   }
 
+  BlockStart = At = Fi->second.Buf;
+  BlockEnd = Fi->second.EndBuf;
+  assert(Fi->first == Func);
+
+  LazyFunctionLoadMap.erase(Fi);
+
+  this->ParseFunctionBody( Func );
 }
 
+void BytecodeReader::ParseAllFunctionBodies() {
+  LazyFunctionMap::iterator Fi = LazyFunctionLoadMap.begin();
+  LazyFunctionMap::iterator Fe = LazyFunctionLoadMap.end();
 
+  while ( Fi != Fe ) {
+    Function* Func = Fi->first;
+    BlockStart = At = Fi->second.Buf;
+    BlockEnd = Fi->second.EndBuf;
+    this->ParseFunctionBody(Func);
+    ++Fi;
+  }
+}
 
-void BytecodeParser::ParseModuleGlobalInfo(const unsigned char *&Buf,
-                                           const unsigned char *End) {
-  if (!FunctionSignatureList.empty())
-    throw std::string("Two ModuleGlobalInfo packets found!");
+void BytecodeReader::ParseGlobalTypes() {
+  ValueTable T;
+  ParseConstantPool(T, ModuleTypes);
+}
+
+void BytecodeReader::ParseModuleGlobalInfo() {
+
+  HANDLE(ModuleGlobalsBegin());
 
   // Read global variables...
-  unsigned VarType = read_vbr_uint(Buf, End);
+  unsigned VarType = read_vbr_uint();
   while (VarType != Type::VoidTyID) { // List is terminated by Void
     // VarType Fields: bit0 = isConstant, bit1 = hasInitializer, bit2,3,4 =
     // Linkage, bit4+ = slot#
     unsigned SlotNo = VarType >> 5;
     unsigned LinkageID = (VarType >> 2) & 7;
+    bool isConstant = VarType & 1;
+    bool hasInitializer = VarType & 2;
     GlobalValue::LinkageTypes Linkage;
 
     switch (LinkageID) {
-    default: assert(0 && "Unknown linkage type!");
     case 0: Linkage = GlobalValue::ExternalLinkage;  break;
     case 1: Linkage = GlobalValue::WeakLinkage;      break;
     case 2: Linkage = GlobalValue::AppendingLinkage; break;
     case 3: Linkage = GlobalValue::InternalLinkage;  break;
     case 4: Linkage = GlobalValue::LinkOnceLinkage;  break;
+    default: 
+      PARSE_ERROR("Unknown linkage type: " << LinkageID);
+      Linkage = GlobalValue::InternalLinkage;
+      break;
     }
 
     const Type *Ty = getType(SlotNo);
-    if (!isa<PointerType>(Ty))
-      throw std::string("Global not pointer type!  Ty = " + 
-                        Ty->getDescription());
+    if ( !Ty ) {
+      PARSE_ERROR("Global has no type! SlotNo=" << SlotNo);
+    }
+
+    if ( !isa<PointerType>(Ty)) {
+      PARSE_ERROR("Global not a pointer type! Ty= " << Ty->getDescription());
+    }
 
     const Type *ElTy = cast<PointerType>(Ty)->getElementType();
 
     // Create the global variable...
-    GlobalVariable *GV = new GlobalVariable(ElTy, VarType & 1, Linkage,
+    GlobalVariable *GV = new GlobalVariable(ElTy, isConstant, Linkage,
                                             0, "", TheModule);
-    BCR_TRACE(2, "Global Variable of type: " << *Ty << "\n");
     insertValue(GV, SlotNo, ModuleValues);
 
-    if (VarType & 2)   // Does it have an initializer?
-      GlobalInits.push_back(std::make_pair(GV, read_vbr_uint(Buf, End)));
-    VarType = read_vbr_uint(Buf, End);
+    unsigned initSlot = 0;
+    if (hasInitializer) {   
+      initSlot = read_vbr_uint();
+      GlobalInits.push_back(std::make_pair(GV, initSlot));
+    }
+
+    // Notify handler about the global value.
+    HANDLE(GlobalVariable( ElTy, isConstant, Linkage, SlotNo, initSlot ));
+
+    // Get next item
+    VarType = read_vbr_uint();
   }
 
   // Read the function objects for all of the functions that are coming
-  unsigned FnSignature = read_vbr_uint(Buf, End);
+  unsigned FnSignature = read_vbr_uint();
   while (FnSignature != Type::VoidTyID) { // List is terminated by Void
     const Type *Ty = getType(FnSignature);
     if (!isa<PointerType>(Ty) ||
-        !isa<FunctionType>(cast<PointerType>(Ty)->getElementType()))
-      throw std::string("Function not ptr to func type!  Ty = " +
+        !isa<FunctionType>(cast<PointerType>(Ty)->getElementType())) {
+      PARSE_ERROR( "Function not a pointer to function type! Ty = " +
                         Ty->getDescription());
+      // FIXME: what should Ty be if handler continues?
+    }
 
     // We create functions by passing the underlying FunctionType to create...
-    Ty = cast<PointerType>(Ty)->getElementType();
+    const FunctionType* FTy = 
+      cast<FunctionType>(cast<PointerType>(Ty)->getElementType());
 
-    // When the ModuleGlobalInfo section is read, we load the type of each
-    // function and the 'ModuleValues' slot that it lands in.  We then load a
-    // placeholder into its slot to reserve it.  When the function is loaded,
-    // this placeholder is replaced.
-
-    // Insert the placeholder...
-    Function *Func = new Function(cast<FunctionType>(Ty),
-                                  GlobalValue::InternalLinkage, "", TheModule);
+    // Insert the place hodler
+    Function* Func = new Function(FTy, GlobalValue::InternalLinkage, 
+	                          "", TheModule);
     insertValue(Func, FnSignature, ModuleValues);
 
-    // Keep track of this information in a list that is emptied as functions are
-    // loaded...
-    //
+    // Save this for later so we know type of lazily instantiated functions
     FunctionSignatureList.push_back(Func);
 
-    FnSignature = read_vbr_uint(Buf, End);
-    BCR_TRACE(2, "Function of type: " << Ty << "\n");
+    HANDLE(FunctionDeclaration(Func));
+
+    // Get Next function signature
+    FnSignature = read_vbr_uint();
   }
 
   if (hasInconsistentModuleGlobalInfo)
-    align32(Buf, End);
+    align32();
 
   // Now that the function signature list is set up, reverse it so that we can 
   // remove elements efficiently from the back of the vector.
@@ -626,12 +1543,13 @@
   // This is for future proofing... in the future extra fields may be added that
   // we don't understand, so we transparently ignore them.
   //
-  Buf = End;
+  At = BlockEnd;
+
+  HANDLE(ModuleGlobalsEnd());
 }
 
-void BytecodeParser::ParseVersionInfo(const unsigned char *&Buf,
-                                      const unsigned char *EndBuf) {
-  unsigned Version = read_vbr_uint(Buf, EndBuf);
+void BytecodeReader::ParseVersionInfo() {
+  unsigned Version = read_vbr_uint();
 
   // Unpack version number: low four bits are for flags, top bits = version
   Module::Endianness  Endianness;
@@ -671,71 +1589,69 @@
     break;
 
   default:
-    throw std::string("Unknown bytecode version number!");
+    PARSE_ERROR("Unknown bytecode version number: " << RevisionNum);
   }
 
   if (hasNoEndianness) Endianness  = Module::AnyEndianness;
   if (hasNoPointerSize) PointerSize = Module::AnyPointerSize;
 
-  TheModule->setEndianness(Endianness);
-  TheModule->setPointerSize(PointerSize);
-  BCR_TRACE(1, "Bytecode Rev = " << (unsigned)RevisionNum << "\n");
-  BCR_TRACE(1, "Endianness/PointerSize = " << Endianness << ","
-               << PointerSize << "\n");
+  HANDLE(VersionInfo(RevisionNum, Endianness, PointerSize ));
 }
 
-void BytecodeParser::ParseModule(const unsigned char *Buf,
-                                 const unsigned char *EndBuf) {
+void BytecodeReader::ParseModule() {
   unsigned Type, Size;
-  readBlock(Buf, EndBuf, Type, Size);
-  if (Type != BytecodeFormat::Module || Buf+Size != EndBuf)
-    throw std::string("Expected Module packet! B: "+
-        utostr((unsigned)(intptr_t)Buf) + ", S: "+utostr(Size)+
-        " E: "+utostr((unsigned)(intptr_t)EndBuf)); // Hrm, not a class?
 
-  BCR_TRACE(0, "BLOCK BytecodeFormat::Module: {\n");
-  FunctionSignatureList.clear();                 // Just in case...
+  FunctionSignatureList.clear(); // Just in case...
 
   // Read into instance variables...
-  ParseVersionInfo(Buf, EndBuf);
-  align32(Buf, EndBuf);
+  ParseVersionInfo();
+  align32(); /// FIXME: Is this redundant? VI is first and 4 bytes!
 
-  while (Buf < EndBuf) {
-    const unsigned char *OldBuf = Buf;
-    readBlock(Buf, EndBuf, Type, Size);
+  bool SeenModuleGlobalInfo = false;
+  bool SeenGlobalTypePlane = false;
+  BufPtr MyEnd = BlockEnd;
+  while (At < MyEnd) {
+    BufPtr OldAt = At;
+    read_block(Type, Size);
+
     switch (Type) {
+
     case BytecodeFormat::GlobalTypePlane:
-      BCR_TRACE(1, "BLOCK BytecodeFormat::GlobalTypePlane: {\n");
-      ParseGlobalTypes(Buf, Buf+Size);
+      if ( SeenGlobalTypePlane )
+        PARSE_ERROR("Two GlobalTypePlane Blocks Encountered!");
+
+      ParseGlobalTypes();
+      SeenGlobalTypePlane = true;
       break;
 
-    case BytecodeFormat::ModuleGlobalInfo:
-      BCR_TRACE(1, "BLOCK BytecodeFormat::ModuleGlobalInfo: {\n");
-      ParseModuleGlobalInfo(Buf, Buf+Size);
+    case BytecodeFormat::ModuleGlobalInfo: 
+      if ( SeenModuleGlobalInfo )
+        PARSE_ERROR("Two ModuleGlobalInfo Blocks Encountered!");
+      ParseModuleGlobalInfo();
+      SeenModuleGlobalInfo = true;
       break;
 
     case BytecodeFormat::ConstantPool:
-      BCR_TRACE(1, "BLOCK BytecodeFormat::ConstantPool: {\n");
-      ParseConstantPool(Buf, Buf+Size, ModuleValues, ModuleTypeValues);
+      ParseConstantPool(ModuleValues, ModuleTypes);
       break;
 
-    case BytecodeFormat::Function: {
-      BCR_TRACE(1, "BLOCK BytecodeFormat::Function: {\n");
-      ParseFunction(Buf, Buf+Size);
+    case BytecodeFormat::Function:
+      ParseFunctionLazily();
       break;
-    }
 
     case BytecodeFormat::SymbolTable:
-      BCR_TRACE(1, "BLOCK BytecodeFormat::SymbolTable: {\n");
-      ParseSymbolTable(Buf, Buf+Size, &TheModule->getSymbolTable(), 0);
+      ParseSymbolTable(0, &TheModule->getSymbolTable());
       break;
+
     default:
-      Buf += Size;
-      if (OldBuf > Buf) throw std::string("Expected Module Block!");
+      At += Size;
+      if (OldAt > At) {
+        PARSE_ERROR("Unexpected Block of Type" << Type << "encountered!" );
+      }
       break;
     }
-    BCR_TRACE(1, "} end block\n");
-    align32(Buf, EndBuf);
+    BlockEnd = MyEnd;
+    align32();
   }
 
   // After the module constant pool has been read, we can safely initialize
@@ -747,38 +1663,151 @@
 
     // Look up the initializer value...
     // FIXME: Preserve this type ID!
-    unsigned TypeSlot = getTypeSlot(GV->getType()->getElementType());
+
+    const llvm::PointerType* GVType = GV->getType();
+    unsigned TypeSlot = getTypeSlot(GVType->getElementType());
     if (Constant *CV = getConstantValue(TypeSlot, Slot)) {
       if (GV->hasInitializer()) 
-        throw std::string("Global *already* has an initializer?!");
+        PARSE_ERROR("Global *already* has an initializer?!");
+      HANDLE(GlobalInitializer(GV,CV));
       GV->setInitializer(CV);
     } else
-      throw std::string("Cannot find initializer value.");
+      PARSE_ERROR("Cannot find initializer value.");
   }
 
+  /// Make sure we pulled them all out. If we didn't then there's a declaration
+  /// but a missing body. That's not allowed.
   if (!FunctionSignatureList.empty())
-    throw std::string("Function expected, but bytecode stream ended!");
-
-  BCR_TRACE(0, "} end block\n\n");
+    PARSE_ERROR(
+      "Function declared, but bytecode stream ended before definition");
 }
 
-void BytecodeParser::ParseBytecode(const unsigned char *Buf, unsigned Length,
-                                   const std::string &ModuleID) {
+void BytecodeReader::ParseBytecode(
+       BufPtr Buf, unsigned Length,
+       const std::string &ModuleID) {
 
-  unsigned char *EndBuf = (unsigned char*)(Buf + Length);
+  try {
+    At = MemStart = BlockStart = Buf;
+    MemEnd = BlockEnd = Buf + Length;
 
-  // Read and check signature...
-  unsigned Sig = read(Buf, EndBuf);
-  if (Sig != ('l' | ('l' << 8) | ('v' << 16) | ('m' << 24)))
-    throw std::string("Invalid bytecode signature!");
+    // Create the module
+    TheModule = new Module(ModuleID);
 
-  TheModule = new Module(ModuleID);
-  try { 
-    ParseModule(Buf, EndBuf);
-  } catch (std::string &Error) {
-    freeState();       // Must destroy handles before deleting module!
+    HANDLE(Start(TheModule, Length));
+
+    // Read and check signature...
+    unsigned Sig = read_uint();
+    if (Sig != ('l' | ('l' << 8) | ('v' << 16) | ('m' << 24))) {
+      PARSE_ERROR("Invalid bytecode signature: " << Sig);
+    }
+
+
+    // Tell the handler we're starting a module
+    HANDLE(ModuleBegin(ModuleID));
+
+    // Get the module block and size and verify
+    unsigned Type, Size;
+    read_block(Type, Size);
+    if ( Type != BytecodeFormat::Module ) {
+      PARSE_ERROR("Expected Module Block! At: " << unsigned(intptr_t(At))
+	<< ", Type:" << Type << ", Size:" << Size);
+    }
+    if ( At + Size != MemEnd ) {
+      PARSE_ERROR("Invalid Top Level Block Length! At: " 
+	<< unsigned(intptr_t(At)) << ", Type:" << Type << ", Size:" << Size);
+    }
+
+    // Parse the module contents
+    this->ParseModule();
+
+    // Tell the handler we're done
+    HANDLE(ModuleEnd(ModuleID));
+
+    // Check for missing functions
+    if ( hasFunctions() )
+      PARSE_ERROR("Function expected, but bytecode stream ended!");
+
+    // Tell the handler we're
+    HANDLE(Finish());
+
+  } catch (std::string& errstr ) {
+    HANDLE(Error(errstr));
+    freeState();
     delete TheModule;
     TheModule = 0;
     throw;
+  } catch (...) {
+    std::string msg("Unknown Exception Occurred");
+    HANDLE(Error(msg));
+    freeState();
+    delete TheModule;
+    TheModule = 0;
+    throw msg;
   }
 }
+
+//===----------------------------------------------------------------------===//
+//=== Default Implementations of Handler Methods
+//===----------------------------------------------------------------------===//
+
+BytecodeHandler::~BytecodeHandler() {}
+void BytecodeHandler::handleError(const std::string& str ) { }
+void BytecodeHandler::handleStart(Module*m, unsigned Length ) { }
+void BytecodeHandler::handleFinish() { }
+void BytecodeHandler::handleModuleBegin(const std::string& id) { }
+void BytecodeHandler::handleModuleEnd(const std::string& id) { }
+void BytecodeHandler::handleVersionInfo( unsigned char RevisionNum,
+  Module::Endianness Endianness, Module::PointerSize PointerSize) { }
+void BytecodeHandler::handleModuleGlobalsBegin() { }
+void BytecodeHandler::handleGlobalVariable( 
+  const Type* ElemType, bool isConstant, GlobalValue::LinkageTypes,
+  unsigned SlotNo, unsigned initSlot ) { }
+void BytecodeHandler::handleType( const Type* Ty ) {}
+void BytecodeHandler::handleFunctionDeclaration( 
+  Function* Func ) {}
+void BytecodeHandler::handleGlobalInitializer(GlobalVariable*, Constant* ) {}
+void BytecodeHandler::handleModuleGlobalsEnd() { } 
+void BytecodeHandler::handleCompactionTableBegin() { } 
+void BytecodeHandler::handleCompactionTablePlane( 
+  unsigned Ty, unsigned NumEntries) {}
+void BytecodeHandler::handleCompactionTableType( 
+  unsigned i, unsigned TypSlot, const Type* ) {}
+void BytecodeHandler::handleCompactionTableValue( 
+  unsigned i, unsigned TypSlot, unsigned ValSlot, const Type* ) {}
+void BytecodeHandler::handleCompactionTableEnd() { }
+void BytecodeHandler::handleSymbolTableBegin(Function*, SymbolTable*) { }
+void BytecodeHandler::handleSymbolTablePlane( unsigned Ty, unsigned NumEntries, 
+  const Type* Typ) { }
+void BytecodeHandler::handleSymbolTableType( unsigned i, unsigned slot, 
+  const std::string& name ) { }
+void BytecodeHandler::handleSymbolTableValue( unsigned i, unsigned slot, 
+  const std::string& name ) { }
+void BytecodeHandler::handleSymbolTableEnd() { }
+void BytecodeHandler::handleFunctionBegin( Function* Func, 
+  unsigned Size ) {}
+void BytecodeHandler::handleFunctionEnd( Function* Func) { }
+void BytecodeHandler::handleBasicBlockBegin( unsigned blocknum) { } 
+bool BytecodeHandler::handleInstruction( unsigned Opcode, const Type* iType,
+  std::vector<unsigned>& Operands, unsigned Size) { 
+    return Instruction::isTerminator(Opcode); 
+  }
+void BytecodeHandler::handleBasicBlockEnd(unsigned blocknum) { }
+void BytecodeHandler::handleGlobalConstantsBegin() { }
+void BytecodeHandler::handleConstantExpression( unsigned Opcode, 
+  std::vector<Constant*> ArgVec, Constant* Val) { }
+void BytecodeHandler::handleConstantValue( Constant * c ) { }
+void BytecodeHandler::handleConstantArray( const ArrayType* AT, 
+  std::vector<Constant*>& Elements, unsigned TypeSlot, Constant* Val ) { }
+void BytecodeHandler::handleConstantStruct( const StructType* ST,
+  std::vector<Constant*>& ElementSlots, Constant* Val ) { }
+void BytecodeHandler::handleConstantPointer( 
+  const PointerType* PT, unsigned TypeSlot, GlobalValue*, Constant* Val) { }
+void BytecodeHandler::handleConstantString( const ConstantArray* CA ) {}
+void BytecodeHandler::handleGlobalConstantsEnd() {}
+void BytecodeHandler::handleAlignment(unsigned numBytes) {}
+void BytecodeHandler::handleBlock(
+  unsigned BType, const unsigned char* StartPtr, unsigned Size) {}
+void BytecodeHandler::handleVBR32(unsigned Size ) {}
+void BytecodeHandler::handleVBR64(unsigned Size ) {}
+
+// vim: sw=2