It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
new file mode 100644
index 0000000..086dca8
--- /dev/null
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -0,0 +1,1226 @@
+//===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Bitcode writer implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Bitcode/BitstreamWriter.h"
+#include "llvm/Bitcode/LLVMBitCodes.h"
+#include "ValueEnumerator.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/InlineAsm.h"
+#include "llvm/Instructions.h"
+#include "llvm/Module.h"
+#include "llvm/ParameterAttributes.h"
+#include "llvm/TypeSymbolTable.h"
+#include "llvm/ValueSymbolTable.h"
+#include "llvm/Support/MathExtras.h"
+using namespace llvm;
+
+/// These are manifest constants used by the bitcode writer. They do not need to
+/// be kept in sync with the reader, but need to be consistent within this file.
+enum {
+  CurVersion = 0,
+  
+  // VALUE_SYMTAB_BLOCK abbrev id's.
+  VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
+  VST_ENTRY_7_ABBREV,
+  VST_ENTRY_6_ABBREV,
+  VST_BBENTRY_6_ABBREV,
+  
+  // CONSTANTS_BLOCK abbrev id's.
+  CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
+  CONSTANTS_INTEGER_ABBREV,
+  CONSTANTS_CE_CAST_Abbrev,
+  CONSTANTS_NULL_Abbrev,
+  
+  // FUNCTION_BLOCK abbrev id's.
+  FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
+  FUNCTION_INST_BINOP_ABBREV,
+  FUNCTION_INST_CAST_ABBREV,
+  FUNCTION_INST_RET_VOID_ABBREV,
+  FUNCTION_INST_RET_VAL_ABBREV,
+  FUNCTION_INST_UNREACHABLE_ABBREV
+};
+
+
+static unsigned GetEncodedCastOpcode(unsigned Opcode) {
+  switch (Opcode) {
+  default: assert(0 && "Unknown cast instruction!");
+  case Instruction::Trunc   : return bitc::CAST_TRUNC;
+  case Instruction::ZExt    : return bitc::CAST_ZEXT;
+  case Instruction::SExt    : return bitc::CAST_SEXT;
+  case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
+  case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
+  case Instruction::UIToFP  : return bitc::CAST_UITOFP;
+  case Instruction::SIToFP  : return bitc::CAST_SITOFP;
+  case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
+  case Instruction::FPExt   : return bitc::CAST_FPEXT;
+  case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
+  case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
+  case Instruction::BitCast : return bitc::CAST_BITCAST;
+  }
+}
+
+static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
+  switch (Opcode) {
+  default: assert(0 && "Unknown binary instruction!");
+  case Instruction::Add:  return bitc::BINOP_ADD;
+  case Instruction::Sub:  return bitc::BINOP_SUB;
+  case Instruction::Mul:  return bitc::BINOP_MUL;
+  case Instruction::UDiv: return bitc::BINOP_UDIV;
+  case Instruction::FDiv:
+  case Instruction::SDiv: return bitc::BINOP_SDIV;
+  case Instruction::URem: return bitc::BINOP_UREM;
+  case Instruction::FRem:
+  case Instruction::SRem: return bitc::BINOP_SREM;
+  case Instruction::Shl:  return bitc::BINOP_SHL;
+  case Instruction::LShr: return bitc::BINOP_LSHR;
+  case Instruction::AShr: return bitc::BINOP_ASHR;
+  case Instruction::And:  return bitc::BINOP_AND;
+  case Instruction::Or:   return bitc::BINOP_OR;
+  case Instruction::Xor:  return bitc::BINOP_XOR;
+  }
+}
+
+
+
+static void WriteStringRecord(unsigned Code, const std::string &Str, 
+                              unsigned AbbrevToUse, BitstreamWriter &Stream) {
+  SmallVector<unsigned, 64> Vals;
+  
+  // Code: [strchar x N]
+  for (unsigned i = 0, e = Str.size(); i != e; ++i)
+    Vals.push_back(Str[i]);
+    
+  // Emit the finished record.
+  Stream.EmitRecord(Code, Vals, AbbrevToUse);
+}
+
+// Emit information about parameter attributes.
+static void WriteParamAttrTable(const ValueEnumerator &VE, 
+                                BitstreamWriter &Stream) {
+  const std::vector<const ParamAttrsList*> &Attrs = VE.getParamAttrs();
+  if (Attrs.empty()) return;
+  
+  Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
+
+  SmallVector<uint64_t, 64> Record;
+  for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
+    const ParamAttrsList *A = Attrs[i];
+    for (unsigned op = 0, e = A->size(); op != e; ++op) {
+      Record.push_back(A->getParamIndex(op));
+      Record.push_back(A->getParamAttrsAtIndex(op));
+    }
+    
+    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
+    Record.clear();
+  }
+  
+  Stream.ExitBlock();
+}
+
+/// WriteTypeTable - Write out the type table for a module.
+static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
+  const ValueEnumerator::TypeList &TypeList = VE.getTypes();
+  
+  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
+  SmallVector<uint64_t, 64> TypeVals;
+  
+  // Abbrev for TYPE_CODE_POINTER.
+  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
+  
+  // Abbrev for TYPE_CODE_FUNCTION.
+  Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getParamAttrs().size()+1)));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
+  
+  // Abbrev for TYPE_CODE_STRUCT.
+  Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
+ 
+  // Abbrev for TYPE_CODE_ARRAY.
+  Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
+  
+  // Emit an entry count so the reader can reserve space.
+  TypeVals.push_back(TypeList.size());
+  Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
+  TypeVals.clear();
+  
+  // Loop over all of the types, emitting each in turn.
+  for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
+    const Type *T = TypeList[i].first;
+    int AbbrevToUse = 0;
+    unsigned Code = 0;
+    
+    switch (T->getTypeID()) {
+    default: assert(0 && "Unknown type!");
+    case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
+    case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
+    case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
+    case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
+    case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
+    case Type::IntegerTyID:
+      // INTEGER: [width]
+      Code = bitc::TYPE_CODE_INTEGER;
+      TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
+      break;
+    case Type::PointerTyID:
+      // POINTER: [pointee type]
+      Code = bitc::TYPE_CODE_POINTER;
+      TypeVals.push_back(VE.getTypeID(cast<PointerType>(T)->getElementType()));
+      AbbrevToUse = PtrAbbrev;
+      break;
+
+    case Type::FunctionTyID: {
+      const FunctionType *FT = cast<FunctionType>(T);
+      // FUNCTION: [isvararg, attrid, retty, paramty x N]
+      Code = bitc::TYPE_CODE_FUNCTION;
+      TypeVals.push_back(FT->isVarArg());
+      TypeVals.push_back(VE.getParamAttrID(FT->getParamAttrs()));
+      TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
+      for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
+        TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
+      AbbrevToUse = FunctionAbbrev;
+      break;
+    }
+    case Type::StructTyID: {
+      const StructType *ST = cast<StructType>(T);
+      // STRUCT: [ispacked, eltty x N]
+      Code = bitc::TYPE_CODE_STRUCT;
+      TypeVals.push_back(ST->isPacked());
+      // Output all of the element types.
+      for (StructType::element_iterator I = ST->element_begin(),
+           E = ST->element_end(); I != E; ++I)
+        TypeVals.push_back(VE.getTypeID(*I));
+      AbbrevToUse = StructAbbrev;
+      break;
+    }
+    case Type::ArrayTyID: {
+      const ArrayType *AT = cast<ArrayType>(T);
+      // ARRAY: [numelts, eltty]
+      Code = bitc::TYPE_CODE_ARRAY;
+      TypeVals.push_back(AT->getNumElements());
+      TypeVals.push_back(VE.getTypeID(AT->getElementType()));
+      AbbrevToUse = ArrayAbbrev;
+      break;
+    }
+    case Type::VectorTyID: {
+      const VectorType *VT = cast<VectorType>(T);
+      // VECTOR [numelts, eltty]
+      Code = bitc::TYPE_CODE_VECTOR;
+      TypeVals.push_back(VT->getNumElements());
+      TypeVals.push_back(VE.getTypeID(VT->getElementType()));
+      break;
+    }
+    }
+
+    // Emit the finished record.
+    Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
+    TypeVals.clear();
+  }
+  
+  Stream.ExitBlock();
+}
+
+static unsigned getEncodedLinkage(const GlobalValue *GV) {
+  switch (GV->getLinkage()) {
+  default: assert(0 && "Invalid linkage!");
+  case GlobalValue::GhostLinkage:  // Map ghost linkage onto external.
+  case GlobalValue::ExternalLinkage:     return 0;
+  case GlobalValue::WeakLinkage:         return 1;
+  case GlobalValue::AppendingLinkage:    return 2;
+  case GlobalValue::InternalLinkage:     return 3;
+  case GlobalValue::LinkOnceLinkage:     return 4;
+  case GlobalValue::DLLImportLinkage:    return 5;
+  case GlobalValue::DLLExportLinkage:    return 6;
+  case GlobalValue::ExternalWeakLinkage: return 7;
+  }
+}
+
+static unsigned getEncodedVisibility(const GlobalValue *GV) {
+  switch (GV->getVisibility()) {
+  default: assert(0 && "Invalid visibility!");
+  case GlobalValue::DefaultVisibility:   return 0;
+  case GlobalValue::HiddenVisibility:    return 1;
+  case GlobalValue::ProtectedVisibility: return 2;
+  }
+}
+
+// Emit top-level description of module, including target triple, inline asm,
+// descriptors for global variables, and function prototype info.
+static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
+                            BitstreamWriter &Stream) {
+  // Emit the list of dependent libraries for the Module.
+  for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
+    WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
+
+  // Emit various pieces of data attached to a module.
+  if (!M->getTargetTriple().empty())
+    WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
+                      0/*TODO*/, Stream);
+  if (!M->getDataLayout().empty())
+    WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
+                      0/*TODO*/, Stream);
+  if (!M->getModuleInlineAsm().empty())
+    WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
+                      0/*TODO*/, Stream);
+
+  // Emit information about sections, computing how many there are.  Also
+  // compute the maximum alignment value.
+  std::map<std::string, unsigned> SectionMap;
+  unsigned MaxAlignment = 0;
+  unsigned MaxGlobalType = 0;
+  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
+       GV != E; ++GV) {
+    MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
+    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
+    
+    if (!GV->hasSection()) continue;
+    // Give section names unique ID's.
+    unsigned &Entry = SectionMap[GV->getSection()];
+    if (Entry != 0) continue;
+    WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
+                      0/*TODO*/, Stream);
+    Entry = SectionMap.size();
+  }
+  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
+    MaxAlignment = std::max(MaxAlignment, F->getAlignment());
+    if (!F->hasSection()) continue;
+    // Give section names unique ID's.
+    unsigned &Entry = SectionMap[F->getSection()];
+    if (Entry != 0) continue;
+    WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
+                      0/*TODO*/, Stream);
+    Entry = SectionMap.size();
+  }
+  
+  // Emit abbrev for globals, now that we know # sections and max alignment.
+  unsigned SimpleGVarAbbrev = 0;
+  if (!M->global_empty()) { 
+    // Add an abbrev for common globals with no visibility or thread localness.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                              Log2_32_Ceil(MaxGlobalType+1)));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));      // Linkage.
+    if (MaxAlignment == 0)                                      // Alignment.
+      Abbv->Add(BitCodeAbbrevOp(0));
+    else {
+      unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
+      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                               Log2_32_Ceil(MaxEncAlignment+1)));
+    }
+    if (SectionMap.empty())                                    // Section.
+      Abbv->Add(BitCodeAbbrevOp(0));
+    else
+      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                               Log2_32_Ceil(SectionMap.size()+1)));
+    // Don't bother emitting vis + thread local.
+    SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
+  }
+  
+  // Emit the global variable information.
+  SmallVector<unsigned, 64> Vals;
+  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
+       GV != E; ++GV) {
+    unsigned AbbrevToUse = 0;
+
+    // GLOBALVAR: [type, isconst, initid, 
+    //             linkage, alignment, section, visibility, threadlocal]
+    Vals.push_back(VE.getTypeID(GV->getType()));
+    Vals.push_back(GV->isConstant());
+    Vals.push_back(GV->isDeclaration() ? 0 :
+                   (VE.getValueID(GV->getInitializer()) + 1));
+    Vals.push_back(getEncodedLinkage(GV));
+    Vals.push_back(Log2_32(GV->getAlignment())+1);
+    Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
+    if (GV->isThreadLocal() || 
+        GV->getVisibility() != GlobalValue::DefaultVisibility) {
+      Vals.push_back(getEncodedVisibility(GV));
+      Vals.push_back(GV->isThreadLocal());
+    } else {
+      AbbrevToUse = SimpleGVarAbbrev;
+    }
+    
+    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
+    Vals.clear();
+  }
+
+  // Emit the function proto information.
+  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
+    // FUNCTION:  [type, callingconv, isproto, linkage, alignment, section,
+    //             visibility]
+    Vals.push_back(VE.getTypeID(F->getType()));
+    Vals.push_back(F->getCallingConv());
+    Vals.push_back(F->isDeclaration());
+    Vals.push_back(getEncodedLinkage(F));
+    
+    // Note: we emit the param attr ID number for the function type of this
+    // function.  In the future, we intend for attrs to be properties of
+    // functions, instead of on the type.  This is to support this future work.
+    Vals.push_back(VE.getParamAttrID(F->getFunctionType()->getParamAttrs()));
+    
+    Vals.push_back(Log2_32(F->getAlignment())+1);
+    Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
+    Vals.push_back(getEncodedVisibility(F));
+    
+    unsigned AbbrevToUse = 0;
+    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
+    Vals.clear();
+  }
+  
+  
+  // Emit the alias information.
+  for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
+       AI != E; ++AI) {
+    Vals.push_back(VE.getTypeID(AI->getType()));
+    Vals.push_back(VE.getValueID(AI->getAliasee()));
+    Vals.push_back(getEncodedLinkage(AI));
+    unsigned AbbrevToUse = 0;
+    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
+    Vals.clear();
+  }
+}
+
+
+static void WriteConstants(unsigned FirstVal, unsigned LastVal,
+                           const ValueEnumerator &VE,
+                           BitstreamWriter &Stream, bool isGlobal) {
+  if (FirstVal == LastVal) return;
+  
+  Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
+
+  unsigned AggregateAbbrev = 0;
+  unsigned String8Abbrev = 0;
+  unsigned CString7Abbrev = 0;
+  unsigned CString6Abbrev = 0;
+  // If this is a constant pool for the module, emit module-specific abbrevs.
+  if (isGlobal) {
+    // Abbrev for CST_CODE_AGGREGATE.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
+    AggregateAbbrev = Stream.EmitAbbrev(Abbv);
+
+    // Abbrev for CST_CODE_STRING.
+    Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+    String8Abbrev = Stream.EmitAbbrev(Abbv);
+    // Abbrev for CST_CODE_CSTRING.
+    Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
+    CString7Abbrev = Stream.EmitAbbrev(Abbv);
+    // Abbrev for CST_CODE_CSTRING.
+    Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+    CString6Abbrev = Stream.EmitAbbrev(Abbv);
+  }  
+  
+  SmallVector<uint64_t, 64> Record;
+
+  const ValueEnumerator::ValueList &Vals = VE.getValues();
+  const Type *LastTy = 0;
+  for (unsigned i = FirstVal; i != LastVal; ++i) {
+    const Value *V = Vals[i].first;
+    // If we need to switch types, do so now.
+    if (V->getType() != LastTy) {
+      LastTy = V->getType();
+      Record.push_back(VE.getTypeID(LastTy));
+      Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
+                        CONSTANTS_SETTYPE_ABBREV);
+      Record.clear();
+    }
+    
+    if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
+      Record.push_back(unsigned(IA->hasSideEffects()));
+      
+      // Add the asm string.
+      const std::string &AsmStr = IA->getAsmString();
+      Record.push_back(AsmStr.size());
+      for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
+        Record.push_back(AsmStr[i]);
+      
+      // Add the constraint string.
+      const std::string &ConstraintStr = IA->getConstraintString();
+      Record.push_back(ConstraintStr.size());
+      for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
+        Record.push_back(ConstraintStr[i]);
+      Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
+      Record.clear();
+      continue;
+    }
+    const Constant *C = cast<Constant>(V);
+    unsigned Code = -1U;
+    unsigned AbbrevToUse = 0;
+    if (C->isNullValue()) {
+      Code = bitc::CST_CODE_NULL;
+    } else if (isa<UndefValue>(C)) {
+      Code = bitc::CST_CODE_UNDEF;
+    } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
+      if (IV->getBitWidth() <= 64) {
+        int64_t V = IV->getSExtValue();
+        if (V >= 0)
+          Record.push_back(V << 1);
+        else
+          Record.push_back((-V << 1) | 1);
+        Code = bitc::CST_CODE_INTEGER;
+        AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
+      } else {                             // Wide integers, > 64 bits in size.
+        // We have an arbitrary precision integer value to write whose 
+        // bit width is > 64. However, in canonical unsigned integer 
+        // format it is likely that the high bits are going to be zero.
+        // So, we only write the number of active words.
+        unsigned NWords = IV->getValue().getActiveWords(); 
+        const uint64_t *RawWords = IV->getValue().getRawData();
+        for (unsigned i = 0; i != NWords; ++i) {
+          int64_t V = RawWords[i];
+          if (V >= 0)
+            Record.push_back(V << 1);
+          else
+            Record.push_back((-V << 1) | 1);
+        }
+        Code = bitc::CST_CODE_WIDE_INTEGER;
+      }
+    } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
+      Code = bitc::CST_CODE_FLOAT;
+      if (CFP->getType() == Type::FloatTy) {
+        Record.push_back(FloatToBits((float)CFP->getValue()));
+      } else {
+        assert (CFP->getType() == Type::DoubleTy && "Unknown FP type!");
+        Record.push_back(DoubleToBits((double)CFP->getValue()));
+      }
+    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
+      // Emit constant strings specially.
+      unsigned NumOps = C->getNumOperands();
+      // If this is a null-terminated string, use the denser CSTRING encoding.
+      if (C->getOperand(NumOps-1)->isNullValue()) {
+        Code = bitc::CST_CODE_CSTRING;
+        --NumOps;  // Don't encode the null, which isn't allowed by char6.
+      } else {
+        Code = bitc::CST_CODE_STRING;
+        AbbrevToUse = String8Abbrev;
+      }
+      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
+      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
+      for (unsigned i = 0; i != NumOps; ++i) {
+        unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
+        Record.push_back(V);
+        isCStr7 &= (V & 128) == 0;
+        if (isCStrChar6) 
+          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
+      }
+      
+      if (isCStrChar6)
+        AbbrevToUse = CString6Abbrev;
+      else if (isCStr7)
+        AbbrevToUse = CString7Abbrev;
+    } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
+               isa<ConstantVector>(V)) {
+      Code = bitc::CST_CODE_AGGREGATE;
+      for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
+        Record.push_back(VE.getValueID(C->getOperand(i)));
+      AbbrevToUse = AggregateAbbrev;
+    } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
+      switch (CE->getOpcode()) {
+      default:
+        if (Instruction::isCast(CE->getOpcode())) {
+          Code = bitc::CST_CODE_CE_CAST;
+          Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
+          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
+          Record.push_back(VE.getValueID(C->getOperand(0)));
+          AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
+        } else {
+          assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
+          Code = bitc::CST_CODE_CE_BINOP;
+          Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
+          Record.push_back(VE.getValueID(C->getOperand(0)));
+          Record.push_back(VE.getValueID(C->getOperand(1)));
+        }
+        break;
+      case Instruction::GetElementPtr:
+        Code = bitc::CST_CODE_CE_GEP;
+        for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
+          Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
+          Record.push_back(VE.getValueID(C->getOperand(i)));
+        }
+        break;
+      case Instruction::Select:
+        Code = bitc::CST_CODE_CE_SELECT;
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        Record.push_back(VE.getValueID(C->getOperand(1)));
+        Record.push_back(VE.getValueID(C->getOperand(2)));
+        break;
+      case Instruction::ExtractElement:
+        Code = bitc::CST_CODE_CE_EXTRACTELT;
+        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        Record.push_back(VE.getValueID(C->getOperand(1)));
+        break;
+      case Instruction::InsertElement:
+        Code = bitc::CST_CODE_CE_INSERTELT;
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        Record.push_back(VE.getValueID(C->getOperand(1)));
+        Record.push_back(VE.getValueID(C->getOperand(2)));
+        break;
+      case Instruction::ShuffleVector:
+        Code = bitc::CST_CODE_CE_SHUFFLEVEC;
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        Record.push_back(VE.getValueID(C->getOperand(1)));
+        Record.push_back(VE.getValueID(C->getOperand(2)));
+        break;
+      case Instruction::ICmp:
+      case Instruction::FCmp:
+        Code = bitc::CST_CODE_CE_CMP;
+        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        Record.push_back(VE.getValueID(C->getOperand(1)));
+        Record.push_back(CE->getPredicate());
+        break;
+      }
+    } else {
+      assert(0 && "Unknown constant!");
+    }
+    Stream.EmitRecord(Code, Record, AbbrevToUse);
+    Record.clear();
+  }
+
+  Stream.ExitBlock();
+}
+
+static void WriteModuleConstants(const ValueEnumerator &VE,
+                                 BitstreamWriter &Stream) {
+  const ValueEnumerator::ValueList &Vals = VE.getValues();
+  
+  // Find the first constant to emit, which is the first non-globalvalue value.
+  // We know globalvalues have been emitted by WriteModuleInfo.
+  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
+    if (!isa<GlobalValue>(Vals[i].first)) {
+      WriteConstants(i, Vals.size(), VE, Stream, true);
+      return;
+    }
+  }
+}
+
+/// PushValueAndType - The file has to encode both the value and type id for
+/// many values, because we need to know what type to create for forward
+/// references.  However, most operands are not forward references, so this type
+/// field is not needed.
+///
+/// This function adds V's value ID to Vals.  If the value ID is higher than the
+/// instruction ID, then it is a forward reference, and it also includes the
+/// type ID.
+static bool PushValueAndType(Value *V, unsigned InstID,
+                             SmallVector<unsigned, 64> &Vals, 
+                             ValueEnumerator &VE) {
+  unsigned ValID = VE.getValueID(V);
+  Vals.push_back(ValID);
+  if (ValID >= InstID) {
+    Vals.push_back(VE.getTypeID(V->getType()));
+    return true;
+  }
+  return false;
+}
+
+/// WriteInstruction - Emit an instruction to the specified stream.
+static void WriteInstruction(const Instruction &I, unsigned InstID,
+                             ValueEnumerator &VE, BitstreamWriter &Stream,
+                             SmallVector<unsigned, 64> &Vals) {
+  unsigned Code = 0;
+  unsigned AbbrevToUse = 0;
+  switch (I.getOpcode()) {
+  default:
+    if (Instruction::isCast(I.getOpcode())) {
+      Code = bitc::FUNC_CODE_INST_CAST;
+      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
+        AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
+      Vals.push_back(VE.getTypeID(I.getType()));
+      Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
+    } else {
+      assert(isa<BinaryOperator>(I) && "Unknown instruction!");
+      Code = bitc::FUNC_CODE_INST_BINOP;
+      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
+        AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
+      Vals.push_back(VE.getValueID(I.getOperand(1)));
+      Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
+    }
+    break;
+
+  case Instruction::GetElementPtr:
+    Code = bitc::FUNC_CODE_INST_GEP;
+    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+      PushValueAndType(I.getOperand(i), InstID, Vals, VE);
+    break;
+  case Instruction::Select:
+    Code = bitc::FUNC_CODE_INST_SELECT;
+    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
+    Vals.push_back(VE.getValueID(I.getOperand(2)));
+    Vals.push_back(VE.getValueID(I.getOperand(0)));
+    break;
+  case Instruction::ExtractElement:
+    Code = bitc::FUNC_CODE_INST_EXTRACTELT;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
+    Vals.push_back(VE.getValueID(I.getOperand(1)));
+    break;
+  case Instruction::InsertElement:
+    Code = bitc::FUNC_CODE_INST_INSERTELT;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
+    Vals.push_back(VE.getValueID(I.getOperand(1)));
+    Vals.push_back(VE.getValueID(I.getOperand(2)));
+    break;
+  case Instruction::ShuffleVector:
+    Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
+    Vals.push_back(VE.getValueID(I.getOperand(1)));
+    Vals.push_back(VE.getValueID(I.getOperand(2)));
+    break;
+  case Instruction::ICmp:
+  case Instruction::FCmp:
+    Code = bitc::FUNC_CODE_INST_CMP;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
+    Vals.push_back(VE.getValueID(I.getOperand(1)));
+    Vals.push_back(cast<CmpInst>(I).getPredicate());
+    break;
+
+  case Instruction::Ret:
+    Code = bitc::FUNC_CODE_INST_RET;
+    if (!I.getNumOperands())
+      AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
+    else if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
+      AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
+    break;
+  case Instruction::Br:
+    Code = bitc::FUNC_CODE_INST_BR;
+    Vals.push_back(VE.getValueID(I.getOperand(0)));
+    if (cast<BranchInst>(I).isConditional()) {
+      Vals.push_back(VE.getValueID(I.getOperand(1)));
+      Vals.push_back(VE.getValueID(I.getOperand(2)));
+    }
+    break;
+  case Instruction::Switch:
+    Code = bitc::FUNC_CODE_INST_SWITCH;
+    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
+    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+      Vals.push_back(VE.getValueID(I.getOperand(i)));
+    break;
+  case Instruction::Invoke: {
+    const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
+    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+    Code = bitc::FUNC_CODE_INST_INVOKE;
+    
+    // Note: we emit the param attr ID number for the function type of this
+    // function.  In the future, we intend for attrs to be properties of
+    // functions, instead of on the type.  This is to support this future work.
+    Vals.push_back(VE.getParamAttrID(FTy->getParamAttrs()));
+    
+    Vals.push_back(cast<InvokeInst>(I).getCallingConv());
+    Vals.push_back(VE.getValueID(I.getOperand(1)));      // normal dest
+    Vals.push_back(VE.getValueID(I.getOperand(2)));      // unwind dest
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE); // callee
+    
+    // Emit value #'s for the fixed parameters.
+    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
+      Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
+
+    // Emit type/value pairs for varargs params.
+    if (FTy->isVarArg()) {
+      for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
+           i != e; ++i)
+        PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
+    }
+    break;
+  }
+  case Instruction::Unwind:
+    Code = bitc::FUNC_CODE_INST_UNWIND;
+    break;
+  case Instruction::Unreachable:
+    Code = bitc::FUNC_CODE_INST_UNREACHABLE;
+    AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
+    break;
+  
+  case Instruction::PHI:
+    Code = bitc::FUNC_CODE_INST_PHI;
+    Vals.push_back(VE.getTypeID(I.getType()));
+    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+      Vals.push_back(VE.getValueID(I.getOperand(i)));
+    break;
+    
+  case Instruction::Malloc:
+    Code = bitc::FUNC_CODE_INST_MALLOC;
+    Vals.push_back(VE.getTypeID(I.getType()));
+    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
+    Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
+    break;
+    
+  case Instruction::Free:
+    Code = bitc::FUNC_CODE_INST_FREE;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
+    break;
+    
+  case Instruction::Alloca:
+    Code = bitc::FUNC_CODE_INST_ALLOCA;
+    Vals.push_back(VE.getTypeID(I.getType()));
+    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
+    Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
+    break;
+    
+  case Instruction::Load:
+    Code = bitc::FUNC_CODE_INST_LOAD;
+    if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
+      AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
+      
+    Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
+    Vals.push_back(cast<LoadInst>(I).isVolatile());
+    break;
+  case Instruction::Store:
+    Code = bitc::FUNC_CODE_INST_STORE;
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // val.
+    Vals.push_back(VE.getValueID(I.getOperand(1)));       // ptr.
+    Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
+    Vals.push_back(cast<StoreInst>(I).isVolatile());
+    break;
+  case Instruction::Call: {
+    const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
+    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+
+    Code = bitc::FUNC_CODE_INST_CALL;
+    
+    // Note: we emit the param attr ID number for the function type of this
+    // function.  In the future, we intend for attrs to be properties of
+    // functions, instead of on the type.  This is to support this future work.
+    Vals.push_back(VE.getParamAttrID(FTy->getParamAttrs()));
+    
+    Vals.push_back((cast<CallInst>(I).getCallingConv() << 1) |
+                   unsigned(cast<CallInst>(I).isTailCall()));
+    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // Callee
+    
+    // Emit value #'s for the fixed parameters.
+    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
+      Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
+      
+    // Emit type/value pairs for varargs params.
+    if (FTy->isVarArg()) {
+      unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
+      for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
+           i != e; ++i)
+        PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
+    }
+    break;
+  }
+  case Instruction::VAArg:
+    Code = bitc::FUNC_CODE_INST_VAARG;
+    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
+    Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
+    Vals.push_back(VE.getTypeID(I.getType())); // restype.
+    break;
+  }
+  
+  Stream.EmitRecord(Code, Vals, AbbrevToUse);
+  Vals.clear();
+}
+
+// Emit names for globals/functions etc.
+static void WriteValueSymbolTable(const ValueSymbolTable &VST,
+                                  const ValueEnumerator &VE,
+                                  BitstreamWriter &Stream) {
+  if (VST.empty()) return;
+  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
+
+  // FIXME: Set up the abbrev, we know how many values there are!
+  // FIXME: We know if the type names can use 7-bit ascii.
+  SmallVector<unsigned, 64> NameVals;
+  
+  for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
+       SI != SE; ++SI) {
+    
+    const ValueName &Name = *SI;
+    
+    // Figure out the encoding to use for the name.
+    bool is7Bit = true;
+    bool isChar6 = true;
+    for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
+         C != E; ++C) {
+      if (isChar6) 
+        isChar6 = BitCodeAbbrevOp::isChar6(*C);
+      if ((unsigned char)*C & 128) {
+        is7Bit = false;
+        break;  // don't bother scanning the rest.
+      }
+    }
+    
+    unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
+    
+    // VST_ENTRY:   [valueid, namechar x N]
+    // VST_BBENTRY: [bbid, namechar x N]
+    unsigned Code;
+    if (isa<BasicBlock>(SI->getValue())) {
+      Code = bitc::VST_CODE_BBENTRY;
+      if (isChar6)
+        AbbrevToUse = VST_BBENTRY_6_ABBREV;
+    } else {
+      Code = bitc::VST_CODE_ENTRY;
+      if (isChar6)
+        AbbrevToUse = VST_ENTRY_6_ABBREV;
+      else if (is7Bit)
+        AbbrevToUse = VST_ENTRY_7_ABBREV;
+    }
+    
+    NameVals.push_back(VE.getValueID(SI->getValue()));
+    for (const char *P = Name.getKeyData(),
+         *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
+      NameVals.push_back((unsigned char)*P);
+    
+    // Emit the finished record.
+    Stream.EmitRecord(Code, NameVals, AbbrevToUse);
+    NameVals.clear();
+  }
+  Stream.ExitBlock();
+}
+
+/// WriteFunction - Emit a function body to the module stream.
+static void WriteFunction(const Function &F, ValueEnumerator &VE, 
+                          BitstreamWriter &Stream) {
+  Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
+  VE.incorporateFunction(F);
+
+  SmallVector<unsigned, 64> Vals;
+  
+  // Emit the number of basic blocks, so the reader can create them ahead of
+  // time.
+  Vals.push_back(VE.getBasicBlocks().size());
+  Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
+  Vals.clear();
+  
+  // If there are function-local constants, emit them now.
+  unsigned CstStart, CstEnd;
+  VE.getFunctionConstantRange(CstStart, CstEnd);
+  WriteConstants(CstStart, CstEnd, VE, Stream, false);
+  
+  // Keep a running idea of what the instruction ID is. 
+  unsigned InstID = CstEnd;
+  
+  // Finally, emit all the instructions, in order.
+  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
+         I != E; ++I) {
+      WriteInstruction(*I, InstID, VE, Stream, Vals);
+      if (I->getType() != Type::VoidTy)
+        ++InstID;
+    }
+  
+  // Emit names for all the instructions etc.
+  WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
+    
+  VE.purgeFunction();
+  Stream.ExitBlock();
+}
+
+/// WriteTypeSymbolTable - Emit a block for the specified type symtab.
+static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
+                                 const ValueEnumerator &VE,
+                                 BitstreamWriter &Stream) {
+  if (TST.empty()) return;
+  
+  Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
+  
+  // 7-bit fixed width VST_CODE_ENTRY strings.
+  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
+  unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
+  
+  SmallVector<unsigned, 64> NameVals;
+  
+  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end(); 
+       TI != TE; ++TI) {
+    // TST_ENTRY: [typeid, namechar x N]
+    NameVals.push_back(VE.getTypeID(TI->second));
+    
+    const std::string &Str = TI->first;
+    bool is7Bit = true;
+    for (unsigned i = 0, e = Str.size(); i != e; ++i) {
+      NameVals.push_back((unsigned char)Str[i]);
+      if (Str[i] & 128)
+        is7Bit = false;
+    }
+    
+    // Emit the finished record.
+    Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
+    NameVals.clear();
+  }
+  
+  Stream.ExitBlock();
+}
+
+// Emit blockinfo, which defines the standard abbreviations etc.
+static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
+  // We only want to emit block info records for blocks that have multiple
+  // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
+  // blocks can defined their abbrevs inline.
+  Stream.EnterBlockInfoBlock(2);
+  
+  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, 
+                                   Abbv) != VST_ENTRY_8_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  { // 7-bit fixed width VST_ENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
+                                   Abbv) != VST_ENTRY_7_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // 6-bit char6 VST_ENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
+                                   Abbv) != VST_ENTRY_6_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // 6-bit char6 VST_BBENTRY strings.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
+                                   Abbv) != VST_BBENTRY_6_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  
+  
+  { // SETTYPE abbrev for CONSTANTS_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                              Log2_32_Ceil(VE.getTypes().size()+1)));
+    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
+                                   Abbv) != CONSTANTS_SETTYPE_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  { // INTEGER abbrev for CONSTANTS_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
+                                   Abbv) != CONSTANTS_INTEGER_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  { // CE_CAST abbrev for CONSTANTS_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
+                              Log2_32_Ceil(VE.getTypes().size()+1)));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
+
+    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
+                                   Abbv) != CONSTANTS_CE_CAST_Abbrev)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // NULL abbrev for CONSTANTS_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
+    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
+                                   Abbv) != CONSTANTS_NULL_Abbrev)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  // FIXME: This should only use space for first class types!
+ 
+  { // INST_LOAD abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_LOAD_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // INST_BINOP abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_BINOP_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // INST_CAST abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
+                              Log2_32_Ceil(VE.getTypes().size()+1)));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_CAST_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  { // INST_RET abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // INST_RET abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
+                                   Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
+      assert(0 && "Unexpected abbrev ordering!");
+  }
+  
+  Stream.ExitBlock();
+}
+
+
+/// WriteModule - Emit the specified module to the bitstream.
+static void WriteModule(const Module *M, BitstreamWriter &Stream) {
+  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
+  
+  // Emit the version number if it is non-zero.
+  if (CurVersion) {
+    SmallVector<unsigned, 1> Vals;
+    Vals.push_back(CurVersion);
+    Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
+  }
+  
+  // Analyze the module, enumerating globals, functions, etc.
+  ValueEnumerator VE(M);
+
+  // Emit blockinfo, which defines the standard abbreviations etc.
+  WriteBlockInfo(VE, Stream);
+  
+  // Emit information about parameter attributes.
+  WriteParamAttrTable(VE, Stream);
+  
+  // Emit information describing all of the types in the module.
+  WriteTypeTable(VE, Stream);
+  
+  // Emit top-level description of module, including target triple, inline asm,
+  // descriptors for global variables, and function prototype info.
+  WriteModuleInfo(M, VE, Stream);
+  
+  // Emit constants.
+  WriteModuleConstants(VE, Stream);
+  
+  // If we have any aggregate values in the value table, purge them - these can
+  // only be used to initialize global variables.  Doing so makes the value
+  // namespace smaller for code in functions.
+  int NumNonAggregates = VE.PurgeAggregateValues();
+  if (NumNonAggregates != -1) {
+    SmallVector<unsigned, 1> Vals;
+    Vals.push_back(NumNonAggregates);
+    Stream.EmitRecord(bitc::MODULE_CODE_PURGEVALS, Vals);
+  }
+  
+  // Emit function bodies.
+  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
+    if (!I->isDeclaration())
+      WriteFunction(*I, VE, Stream);
+  
+  // Emit the type symbol table information.
+  WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
+  
+  // Emit names for globals/functions etc.
+  WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
+  
+  Stream.ExitBlock();
+}
+
+
+/// WriteBitcodeToFile - Write the specified module to the specified output
+/// stream.
+void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
+  std::vector<unsigned char> Buffer;
+  BitstreamWriter Stream(Buffer);
+  
+  Buffer.reserve(256*1024);
+  
+  // Emit the file header.
+  Stream.Emit((unsigned)'B', 8);
+  Stream.Emit((unsigned)'C', 8);
+  Stream.Emit(0x0, 4);
+  Stream.Emit(0xC, 4);
+  Stream.Emit(0xE, 4);
+  Stream.Emit(0xD, 4);
+
+  // Emit the module.
+  WriteModule(M, Stream);
+  
+  // Write the generated bitstream to "Out".
+  Out.write((char*)&Buffer.front(), Buffer.size());
+  
+  // Make sure it hits disk now.
+  Out.flush();
+}
diff --git a/lib/Bitcode/Writer/BitcodeWriterPass.cpp b/lib/Bitcode/Writer/BitcodeWriterPass.cpp
new file mode 100644
index 0000000..7412311
--- /dev/null
+++ b/lib/Bitcode/Writer/BitcodeWriterPass.cpp
@@ -0,0 +1,43 @@
+//===--- Bitcode/Writer/BitcodeWriterPass.cpp - Bitcode Writer ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// BitcodeWriterPass implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Pass.h"
+using namespace llvm;
+
+namespace {
+  class WriteBitcodePass : public ModulePass {
+    std::ostream *Out;                 // ostream to print on
+  public:
+    static char ID; // Pass identifcation, replacement for typeid
+    WriteBitcodePass() : ModulePass((intptr_t) &ID), Out(0) { } 
+    WriteBitcodePass(std::ostream &o) : ModulePass((intptr_t) &ID), Out(&o) {}
+    
+    bool runOnModule(Module &M) {
+      if (Out)
+        WriteBitcodeToFile(&M, *Out);
+      return false;
+    }
+  };
+}
+
+char WriteBitcodePass::ID = 0;
+static RegisterPass<WriteBitcodePass> X("emitbitcode", "Bitcode Writer");
+
+/// CreateBitcodeWriterPass - Create and return a pass that writes the module
+/// to the specified ostream.
+ModulePass *llvm::CreateBitcodeWriterPass(std::ostream &Str) {
+  return new WriteBitcodePass(Str);
+}
+
+
diff --git a/lib/Bitcode/Writer/Makefile b/lib/Bitcode/Writer/Makefile
new file mode 100644
index 0000000..c87387a
--- /dev/null
+++ b/lib/Bitcode/Writer/Makefile
@@ -0,0 +1,15 @@
+##===- lib/Bitcode/Reader/Makefile -------------------------*- Makefile -*-===##
+# 
+#                     The LLVM Compiler Infrastructure
+#
+# This file was developed by Chris Lattner and is distributed under
+# the University of Illinois Open Source License. See LICENSE.TXT for details.
+# 
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+LIBRARYNAME = LLVMBitWriter
+BUILD_ARCHIVE = 1
+
+include $(LEVEL)/Makefile.common
+
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
new file mode 100644
index 0000000..6b3885e
--- /dev/null
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -0,0 +1,320 @@
+//===-- ValueEnumerator.cpp - Number values and types for bitcode writer --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the ValueEnumerator class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ValueEnumerator.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/TypeSymbolTable.h"
+#include "llvm/ValueSymbolTable.h"
+#include <algorithm>
+using namespace llvm;
+
+static bool isFirstClassType(const std::pair<const llvm::Type*,
+                             unsigned int> &P) {
+  return P.first->isFirstClassType();
+}
+
+static bool isIntegerValue(const std::pair<const Value*, unsigned> &V) {
+  return isa<IntegerType>(V.first->getType());
+}
+
+static bool CompareByFrequency(const std::pair<const llvm::Type*,
+                               unsigned int> &P1,
+                               const std::pair<const llvm::Type*,
+                               unsigned int> &P2) {
+  return P1.second > P2.second;
+}
+
+/// ValueEnumerator - Enumerate module-level information.
+ValueEnumerator::ValueEnumerator(const Module *M) {
+  // Enumerate the global variables.
+  for (Module::const_global_iterator I = M->global_begin(),
+         E = M->global_end(); I != E; ++I)
+    EnumerateValue(I);
+
+  // Enumerate the functions.
+  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
+    EnumerateValue(I);
+
+  // Enumerate the aliases.
+  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
+       I != E; ++I)
+    EnumerateValue(I);
+  
+  // Remember what is the cutoff between globalvalue's and other constants.
+  unsigned FirstConstant = Values.size();
+  
+  // Enumerate the global variable initializers.
+  for (Module::const_global_iterator I = M->global_begin(),
+         E = M->global_end(); I != E; ++I)
+    if (I->hasInitializer())
+      EnumerateValue(I->getInitializer());
+
+  // Enumerate the aliasees.
+  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
+       I != E; ++I)
+    EnumerateValue(I->getAliasee());
+  
+  // Enumerate types used by the type symbol table.
+  EnumerateTypeSymbolTable(M->getTypeSymbolTable());
+
+  // Insert constants that are named at module level into the slot pool so that
+  // the module symbol table can refer to them...
+  EnumerateValueSymbolTable(M->getValueSymbolTable());
+  
+  // Enumerate types used by function bodies and argument lists.
+  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
+    
+    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
+         I != E; ++I)
+      EnumerateType(I->getType());
+    
+    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
+      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
+        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end(); 
+             OI != E; ++OI)
+          EnumerateOperandType(*OI);
+        EnumerateType(I->getType());
+      }
+  }
+  
+  // Optimize constant ordering.
+  OptimizeConstants(FirstConstant, Values.size());
+    
+  // Sort the type table by frequency so that most commonly used types are early
+  // in the table (have low bit-width).
+  std::stable_sort(Types.begin(), Types.end(), CompareByFrequency);
+    
+  // Partition the Type ID's so that the first-class types occur before the
+  // aggregate types.  This allows the aggregate types to be dropped from the
+  // type table after parsing the global variable initializers.
+  std::partition(Types.begin(), Types.end(), isFirstClassType);
+
+  // Now that we rearranged the type table, rebuild TypeMap.
+  for (unsigned i = 0, e = Types.size(); i != e; ++i)
+    TypeMap[Types[i].first] = i+1;
+}
+
+// Optimize constant ordering.
+struct CstSortPredicate {
+  ValueEnumerator &VE;
+  CstSortPredicate(ValueEnumerator &ve) : VE(ve) {}
+  bool operator()(const std::pair<const Value*, unsigned> &LHS,
+                  const std::pair<const Value*, unsigned> &RHS) {
+    // Sort by plane.
+    if (LHS.first->getType() != RHS.first->getType())
+      return VE.getTypeID(LHS.first->getType()) < 
+             VE.getTypeID(RHS.first->getType());
+    // Then by frequency.
+    return LHS.second > RHS.second;
+  }
+};
+
+/// OptimizeConstants - Reorder constant pool for denser encoding.
+void ValueEnumerator::OptimizeConstants(unsigned CstStart, unsigned CstEnd) {
+  if (CstStart == CstEnd || CstStart+1 == CstEnd) return;
+  
+  CstSortPredicate P(*this);
+  std::stable_sort(Values.begin()+CstStart, Values.begin()+CstEnd, P);
+  
+  // Ensure that integer constants are at the start of the constant pool.  This
+  // is important so that GEP structure indices come before gep constant exprs.
+  std::partition(Values.begin()+CstStart, Values.begin()+CstEnd,
+                 isIntegerValue);
+  
+  // Rebuild the modified portion of ValueMap.
+  for (; CstStart != CstEnd; ++CstStart)
+    ValueMap[Values[CstStart].first] = CstStart+1;
+}
+
+
+/// EnumerateTypeSymbolTable - Insert all of the types in the specified symbol
+/// table.
+void ValueEnumerator::EnumerateTypeSymbolTable(const TypeSymbolTable &TST) {
+  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end(); 
+       TI != TE; ++TI)
+    EnumerateType(TI->second);
+}
+
+/// EnumerateValueSymbolTable - Insert all of the values in the specified symbol
+/// table into the values table.
+void ValueEnumerator::EnumerateValueSymbolTable(const ValueSymbolTable &VST) {
+  for (ValueSymbolTable::const_iterator VI = VST.begin(), VE = VST.end(); 
+       VI != VE; ++VI)
+    EnumerateValue(VI->getValue());
+}
+
+void ValueEnumerator::EnumerateValue(const Value *V) {
+  assert(V->getType() != Type::VoidTy && "Can't insert void values!");
+  
+  // Check to see if it's already in!
+  unsigned &ValueID = ValueMap[V];
+  if (ValueID) {
+    // Increment use count.
+    Values[ValueID-1].second++;
+    return;
+  }
+
+  // Enumerate the type of this value.
+  EnumerateType(V->getType());
+  
+  if (const Constant *C = dyn_cast<Constant>(V)) {
+    if (isa<GlobalValue>(C)) {
+      // Initializers for globals are handled explicitly elsewhere.
+    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
+      // Do not enumerate the initializers for an array of simple characters.
+      // The initializers just polute the value table, and we emit the strings
+      // specially.
+    } else if (C->getNumOperands()) {
+      // If a constant has operands, enumerate them.  This makes sure that if a
+      // constant has uses (for example an array of const ints), that they are
+      // inserted also.
+      
+      // We prefer to enumerate them with values before we enumerate the user
+      // itself.  This makes it more likely that we can avoid forward references
+      // in the reader.  We know that there can be no cycles in the constants
+      // graph that don't go through a global variable.
+      for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
+           I != E; ++I)
+        EnumerateValue(*I);
+      
+      // Finally, add the value.  Doing this could make the ValueID reference be
+      // dangling, don't reuse it.
+      Values.push_back(std::make_pair(V, 1U));
+      ValueMap[V] = Values.size();
+      return;
+    }
+  }
+  
+  // Add the value.
+  Values.push_back(std::make_pair(V, 1U));
+  ValueID = Values.size();
+}
+
+
+void ValueEnumerator::EnumerateType(const Type *Ty) {
+  unsigned &TypeID = TypeMap[Ty];
+  
+  if (TypeID) {
+    // If we've already seen this type, just increase its occurrence count.
+    Types[TypeID-1].second++;
+    return;
+  }
+  
+  // First time we saw this type, add it.
+  Types.push_back(std::make_pair(Ty, 1U));
+  TypeID = Types.size();
+  
+  // Enumerate subtypes.
+  for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
+       I != E; ++I)
+    EnumerateType(*I);
+  
+  // If this is a function type, enumerate the param attrs.
+  if (const FunctionType *FTy = dyn_cast<FunctionType>(Ty))
+    EnumerateParamAttrs(FTy->getParamAttrs());
+}
+
+// Enumerate the types for the specified value.  If the value is a constant,
+// walk through it, enumerating the types of the constant.
+void ValueEnumerator::EnumerateOperandType(const Value *V) {
+  EnumerateType(V->getType());
+  if (const Constant *C = dyn_cast<Constant>(V)) {
+    // If this constant is already enumerated, ignore it, we know its type must
+    // be enumerated.
+    if (ValueMap.count(V)) return;
+
+    // This constant may have operands, make sure to enumerate the types in
+    // them.
+    for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
+      EnumerateOperandType(C->getOperand(i));
+  }
+}
+
+void ValueEnumerator::EnumerateParamAttrs(const ParamAttrsList *PAL) {
+  if (PAL == 0) return;  // null is always 0.
+  // Do a lookup.
+  unsigned &Entry = ParamAttrMap[PAL];
+  if (Entry == 0) {
+    // Never saw this before, add it.
+    ParamAttrs.push_back(PAL);
+    Entry = ParamAttrs.size();
+  }
+}
+
+
+/// PurgeAggregateValues - If there are any aggregate values at the end of the
+/// value list, remove them and return the count of the remaining values.  If
+/// there are none, return -1.
+int ValueEnumerator::PurgeAggregateValues() {
+  // If there are no aggregate values at the end of the list, return -1.
+  if (Values.empty() || Values.back().first->getType()->isFirstClassType())
+    return -1;
+  
+  // Otherwise, remove aggregate values...
+  while (!Values.empty() && !Values.back().first->getType()->isFirstClassType())
+    Values.pop_back();
+  
+  // ... and return the new size.
+  return Values.size();
+}
+
+void ValueEnumerator::incorporateFunction(const Function &F) {
+  NumModuleValues = Values.size();
+  
+  // Adding function arguments to the value table.
+  for(Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
+      I != E; ++I)
+    EnumerateValue(I);
+
+  FirstFuncConstantID = Values.size();
+  
+  // Add all function-level constants to the value table.
+  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I)
+      for (User::const_op_iterator OI = I->op_begin(), E = I->op_end(); 
+           OI != E; ++OI) {
+        if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
+            isa<InlineAsm>(*OI))
+          EnumerateValue(*OI);
+      }
+    BasicBlocks.push_back(BB);
+    ValueMap[BB] = BasicBlocks.size();
+  }
+  
+  // Optimize the constant layout.
+  OptimizeConstants(FirstFuncConstantID, Values.size());
+  
+  FirstInstID = Values.size();
+  
+  // Add all of the instructions.
+  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
+      if (I->getType() != Type::VoidTy)
+        EnumerateValue(I);
+    }
+  }
+}
+
+void ValueEnumerator::purgeFunction() {
+  /// Remove purged values from the ValueMap.
+  for (unsigned i = NumModuleValues, e = Values.size(); i != e; ++i)
+    ValueMap.erase(Values[i].first);
+  for (unsigned i = 0, e = BasicBlocks.size(); i != e; ++i)
+    ValueMap.erase(BasicBlocks[i]);
+    
+  Values.resize(NumModuleValues);
+  BasicBlocks.clear();
+}
+
diff --git a/lib/Bitcode/Writer/ValueEnumerator.h b/lib/Bitcode/Writer/ValueEnumerator.h
new file mode 100644
index 0000000..e255411
--- /dev/null
+++ b/lib/Bitcode/Writer/ValueEnumerator.h
@@ -0,0 +1,126 @@
+//===-- Bitcode/Writer/ValueEnumerator.h - Number values --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class gives values and types Unique ID's.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef VALUE_ENUMERATOR_H
+#define VALUE_ENUMERATOR_H
+
+#include "llvm/ADT/DenseMap.h"
+#include <vector>
+
+namespace llvm {
+
+class Type;
+class Value;
+class BasicBlock;
+class Function;
+class Module;
+class ParamAttrsList;
+class TypeSymbolTable;
+class ValueSymbolTable;
+
+class ValueEnumerator {
+public:
+  // For each type, we remember its Type* and occurrence frequency.
+  typedef std::vector<std::pair<const Type*, unsigned> > TypeList;
+
+  // For each value, we remember its Value* and occurrence frequency.
+  typedef std::vector<std::pair<const Value*, unsigned> > ValueList;
+private:
+  typedef DenseMap<const Type*, unsigned> TypeMapType;
+  TypeMapType TypeMap;
+  TypeList Types;
+
+  typedef DenseMap<const Value*, unsigned> ValueMapType;
+  ValueMapType ValueMap;
+  ValueList Values;
+  
+  typedef DenseMap<const ParamAttrsList*, unsigned> ParamAttrMapType;
+  ParamAttrMapType ParamAttrMap;
+  std::vector<const ParamAttrsList*> ParamAttrs;
+  
+  /// BasicBlocks - This contains all the basic blocks for the currently
+  /// incorporated function.  Their reverse mapping is stored in ValueMap.
+  std::vector<const BasicBlock*> BasicBlocks;
+  
+  /// When a function is incorporated, this is the size of the Values list
+  /// before incorporation.
+  unsigned NumModuleValues;
+  unsigned FirstFuncConstantID;
+  unsigned FirstInstID;
+  
+  ValueEnumerator(const ValueEnumerator &);  // DO NOT IMPLEMENT
+  void operator=(const ValueEnumerator &);   // DO NOT IMPLEMENT
+public:
+  ValueEnumerator(const Module *M);
+
+  unsigned getValueID(const Value *V) const {
+    ValueMapType::const_iterator I = ValueMap.find(V);
+    assert(I != ValueMap.end() && "Value not in slotcalculator!");
+    return I->second-1;
+  }
+  
+  unsigned getTypeID(const Type *T) const {
+    TypeMapType::const_iterator I = TypeMap.find(T);
+    assert(I != TypeMap.end() && "Type not in ValueEnumerator!");
+    return I->second-1;
+  }
+  
+  unsigned getParamAttrID(const ParamAttrsList *PAL) const {
+    if (PAL == 0) return 0;  // Null maps to zero.
+    ParamAttrMapType::const_iterator I = ParamAttrMap.find(PAL);
+    assert(I != ParamAttrMap.end() && "ParamAttr not in ValueEnumerator!");
+    return I->second;
+  }
+
+  /// getFunctionConstantRange - Return the range of values that corresponds to
+  /// function-local constants.
+  void getFunctionConstantRange(unsigned &Start, unsigned &End) const {
+    Start = FirstFuncConstantID;
+    End = FirstInstID;
+  }
+  
+  const ValueList &getValues() const { return Values; }
+  const TypeList &getTypes() const { return Types; }
+  const std::vector<const BasicBlock*> &getBasicBlocks() const {
+    return BasicBlocks; 
+  }
+  const std::vector<const ParamAttrsList*> &getParamAttrs() const {
+    return ParamAttrs;
+  }
+
+  /// PurgeAggregateValues - If there are any aggregate values at the end of the
+  /// value list, remove them and return the count of the remaining values.  If
+  /// there are none, return -1.
+  int PurgeAggregateValues();
+  
+  /// incorporateFunction/purgeFunction - If you'd like to deal with a function,
+  /// use these two methods to get its data into the ValueEnumerator!
+  ///
+  void incorporateFunction(const Function &F);
+  void purgeFunction();
+
+private:
+  void OptimizeConstants(unsigned CstStart, unsigned CstEnd);
+    
+  void EnumerateValue(const Value *V);
+  void EnumerateType(const Type *T);
+  void EnumerateOperandType(const Value *V);
+  void EnumerateParamAttrs(const ParamAttrsList *PAL);
+  
+  void EnumerateTypeSymbolTable(const TypeSymbolTable &ST);
+  void EnumerateValueSymbolTable(const ValueSymbolTable &ST);
+};
+
+} // End llvm namespace
+
+#endif