lib/Bitcode/Writer/BitcodeWriter.cpp

   1 //===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Bitcode writer implementation.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Bitcode/ReaderWriter.h"
  15 #include "llvm/Bitcode/BitstreamWriter.h"
  16 #include "llvm/Bitcode/LLVMBitCodes.h"
  17 #include "ValueEnumerator.h"
  18 #include "llvm/Constants.h"
  19 #include "llvm/DerivedTypes.h"
  20 #include "llvm/InlineAsm.h"
  21 #include "llvm/Instructions.h"
  22 #include "llvm/Module.h"
  23 #include "llvm/Operator.h"
  24 #include "llvm/ValueSymbolTable.h"
  25 #include "llvm/ADT/Triple.h"
  26 #include "llvm/Support/CommandLine.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Support/MathExtras.h"
  29 #include "llvm/Support/raw_ostream.h"
  30 #include "llvm/Support/Program.h"
  31 #include <cctype>
  32 #include <map>
  33 using namespace llvm;
  34
  35 static cl::opt<bool>
  36 EnablePreserveUseListOrdering("enable-bc-uselist-preserve",
  37                               cl::desc("Turn on experimental support for "
  38                                        "use-list order preservation."),
  39                               cl::init(false), cl::Hidden);
  40
  41 /// These are manifest constants used by the bitcode writer. They do not need to
  42 /// be kept in sync with the reader, but need to be consistent within this file.
  43 enum {
  44   CurVersion = 0,
  45
  46   // VALUE_SYMTAB_BLOCK abbrev id's.
  47   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  48   VST_ENTRY_7_ABBREV,
  49   VST_ENTRY_6_ABBREV,
  50   VST_BBENTRY_6_ABBREV,
  51
  52   // CONSTANTS_BLOCK abbrev id's.
  53   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  54   CONSTANTS_INTEGER_ABBREV,
  55   CONSTANTS_CE_CAST_Abbrev,
  56   CONSTANTS_NULL_Abbrev,
  57
  58   // FUNCTION_BLOCK abbrev id's.
  59   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  60   FUNCTION_INST_BINOP_ABBREV,
  61   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  62   FUNCTION_INST_CAST_ABBREV,
  63   FUNCTION_INST_RET_VOID_ABBREV,
  64   FUNCTION_INST_RET_VAL_ABBREV,
  65   FUNCTION_INST_UNREACHABLE_ABBREV
  66 };
  67
  68 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  69   switch (Opcode) {
  70   default: llvm_unreachable("Unknown cast instruction!");
  71   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  72   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  73   case Instruction::SExt    : return bitc::CAST_SEXT;
  74   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  75   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  76   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  77   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  78   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  79   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  80   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  81   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  82   case Instruction::BitCast : return bitc::CAST_BITCAST;
  83   }
  84 }
  85
  86 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  87   switch (Opcode) {
  88   default: llvm_unreachable("Unknown binary instruction!");
  89   case Instruction::Add:
  90   case Instruction::FAdd: return bitc::BINOP_ADD;
  91   case Instruction::Sub:
  92   case Instruction::FSub: return bitc::BINOP_SUB;
  93   case Instruction::Mul:
  94   case Instruction::FMul: return bitc::BINOP_MUL;
  95   case Instruction::UDiv: return bitc::BINOP_UDIV;
  96   case Instruction::FDiv:
  97   case Instruction::SDiv: return bitc::BINOP_SDIV;
  98   case Instruction::URem: return bitc::BINOP_UREM;
  99   case Instruction::FRem:
 100   case Instruction::SRem: return bitc::BINOP_SREM;
 101   case Instruction::Shl:  return bitc::BINOP_SHL;
 102   case Instruction::LShr: return bitc::BINOP_LSHR;
 103   case Instruction::AShr: return bitc::BINOP_ASHR;
 104   case Instruction::And:  return bitc::BINOP_AND;
 105   case Instruction::Or:   return bitc::BINOP_OR;
 106   case Instruction::Xor:  return bitc::BINOP_XOR;
 107   }
 108 }
 109
 110 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 111   switch (Op) {
 112   default: llvm_unreachable("Unknown RMW operation!");
 113   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 114   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 115   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 116   case AtomicRMWInst::And: return bitc::RMW_AND;
 117   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 118   case AtomicRMWInst::Or: return bitc::RMW_OR;
 119   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 120   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 121   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 122   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 123   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 124   }
 125 }
 126
 127 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 128   switch (Ordering) {
 129   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 130   case Unordered: return bitc::ORDERING_UNORDERED;
 131   case Monotonic: return bitc::ORDERING_MONOTONIC;
 132   case Acquire: return bitc::ORDERING_ACQUIRE;
 133   case Release: return bitc::ORDERING_RELEASE;
 134   case AcquireRelease: return bitc::ORDERING_ACQREL;
 135   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 136   }
 137   llvm_unreachable("Invalid ordering");
 138 }
 139
 140 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 141   switch (SynchScope) {
 142   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 143   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 144   }
 145   llvm_unreachable("Invalid synch scope");
 146 }
 147
 148 static void WriteStringRecord(unsigned Code, StringRef Str,
 149                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 150   SmallVector<unsigned, 64> Vals;
 151
 152   // Code: [strchar x N]
 153   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 154     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 155       AbbrevToUse = 0;
 156     Vals.push_back(Str[i]);
 157   }
 158
 159   // Emit the finished record.
 160   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 161 }
 162
 163 // Emit information about parameter attributes.
 164 static void WriteAttributeTable(const ValueEnumerator &VE,
 165                                 BitstreamWriter &Stream) {
 166   const std::vector<AttrListPtr> &Attrs = VE.getAttributes();
 167   if (Attrs.empty()) return;
 168
 169   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 170
 171   SmallVector<uint64_t, 64> Record;
 172   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 173     const AttrListPtr &A = Attrs[i];
 174     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
 175       const AttributeWithIndex &PAWI = A.getSlot(i);
 176       Record.push_back(PAWI.Index);
 177
 178       // FIXME: remove in LLVM 3.0
 179       // Store the alignment in the bitcode as a 16-bit raw value instead of a
 180       // 5-bit log2 encoded value. Shift the bits above the alignment up by
 181       // 11 bits.
 182       uint64_t FauxAttr = PAWI.Attrs.Raw() & 0xffff;
 183       if (PAWI.Attrs & Attribute::Alignment)
 184         FauxAttr |= (1ull<<16)<<
 185             (((PAWI.Attrs & Attribute::Alignment).Raw()-1) >> 16);
 186       FauxAttr |= (PAWI.Attrs.Raw() & (0x3FFull << 21)) << 11;
 187
 188       Record.push_back(FauxAttr);
 189     }
 190
 191     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 192     Record.clear();
 193   }
 194
 195   Stream.ExitBlock();
 196 }
 197
 198 /// WriteTypeTable - Write out the type table for a module.
 199 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 200   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 201
 202   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 203   SmallVector<uint64_t, 64> TypeVals;
 204
 205   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 206
 207   // Abbrev for TYPE_CODE_POINTER.
 208   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 209   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 210   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 211   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 212   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 213
 214   // Abbrev for TYPE_CODE_FUNCTION.
 215   Abbv = new BitCodeAbbrev();
 216   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 217   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 218   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 219   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 220
 221   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 222
 223   // Abbrev for TYPE_CODE_STRUCT_ANON.
 224   Abbv = new BitCodeAbbrev();
 225   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 226   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 227   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 228   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 229
 230   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 231
 232   // Abbrev for TYPE_CODE_STRUCT_NAME.
 233   Abbv = new BitCodeAbbrev();
 234   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 235   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 236   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 237   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 238
 239   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 240   Abbv = new BitCodeAbbrev();
 241   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 242   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 243   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 244   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 245
 246   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 247
 248   // Abbrev for TYPE_CODE_ARRAY.
 249   Abbv = new BitCodeAbbrev();
 250   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 251   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 252   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 253
 254   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 255
 256   // Emit an entry count so the reader can reserve space.
 257   TypeVals.push_back(TypeList.size());
 258   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 259   TypeVals.clear();
 260
 261   // Loop over all of the types, emitting each in turn.
 262   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 263     Type *T = TypeList[i];
 264     int AbbrevToUse = 0;
 265     unsigned Code = 0;
 266
 267     switch (T->getTypeID()) {
 268     default: llvm_unreachable("Unknown type!");
 269     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;   break;
 270     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;   break;
 271     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;  break;
 272     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE; break;
 273     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80; break;
 274     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128; break;
 275     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 276     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;  break;
 277     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA; break;
 278     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX; break;
 279     case Type::IntegerTyID:
 280       // INTEGER: [width]
 281       Code = bitc::TYPE_CODE_INTEGER;
 282       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 283       break;
 284     case Type::PointerTyID: {
 285       PointerType *PTy = cast<PointerType>(T);
 286       // POINTER: [pointee type, address space]
 287       Code = bitc::TYPE_CODE_POINTER;
 288       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 289       unsigned AddressSpace = PTy->getAddressSpace();
 290       TypeVals.push_back(AddressSpace);
 291       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 292       break;
 293     }
 294     case Type::FunctionTyID: {
 295       FunctionType *FT = cast<FunctionType>(T);
 296       // FUNCTION: [isvararg, retty, paramty x N]
 297       Code = bitc::TYPE_CODE_FUNCTION;
 298       TypeVals.push_back(FT->isVarArg());
 299       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 300       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 301         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 302       AbbrevToUse = FunctionAbbrev;
 303       break;
 304     }
 305     case Type::StructTyID: {
 306       StructType *ST = cast<StructType>(T);
 307       // STRUCT: [ispacked, eltty x N]
 308       TypeVals.push_back(ST->isPacked());
 309       // Output all of the element types.
 310       for (StructType::element_iterator I = ST->element_begin(),
 311            E = ST->element_end(); I != E; ++I)
 312         TypeVals.push_back(VE.getTypeID(*I));
 313
 314       if (ST->isLiteral()) {
 315         Code = bitc::TYPE_CODE_STRUCT_ANON;
 316         AbbrevToUse = StructAnonAbbrev;
 317       } else {
 318         if (ST->isOpaque()) {
 319           Code = bitc::TYPE_CODE_OPAQUE;
 320         } else {
 321           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 322           AbbrevToUse = StructNamedAbbrev;
 323         }
 324
 325         // Emit the name if it is present.
 326         if (!ST->getName().empty())
 327           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 328                             StructNameAbbrev, Stream);
 329       }
 330       break;
 331     }
 332     case Type::ArrayTyID: {
 333       ArrayType *AT = cast<ArrayType>(T);
 334       // ARRAY: [numelts, eltty]
 335       Code = bitc::TYPE_CODE_ARRAY;
 336       TypeVals.push_back(AT->getNumElements());
 337       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 338       AbbrevToUse = ArrayAbbrev;
 339       break;
 340     }
 341     case Type::VectorTyID: {
 342       VectorType *VT = cast<VectorType>(T);
 343       // VECTOR [numelts, eltty]
 344       Code = bitc::TYPE_CODE_VECTOR;
 345       TypeVals.push_back(VT->getNumElements());
 346       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 347       break;
 348     }
 349     }
 350
 351     // Emit the finished record.
 352     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 353     TypeVals.clear();
 354   }
 355
 356   Stream.ExitBlock();
 357 }
 358
 359 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 360   switch (GV->getLinkage()) {
 361   case GlobalValue::ExternalLinkage:                 return 0;
 362   case GlobalValue::WeakAnyLinkage:                  return 1;
 363   case GlobalValue::AppendingLinkage:                return 2;
 364   case GlobalValue::InternalLinkage:                 return 3;
 365   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 366   case GlobalValue::DLLImportLinkage:                return 5;
 367   case GlobalValue::DLLExportLinkage:                return 6;
 368   case GlobalValue::ExternalWeakLinkage:             return 7;
 369   case GlobalValue::CommonLinkage:                   return 8;
 370   case GlobalValue::PrivateLinkage:                  return 9;
 371   case GlobalValue::WeakODRLinkage:                  return 10;
 372   case GlobalValue::LinkOnceODRLinkage:              return 11;
 373   case GlobalValue::AvailableExternallyLinkage:      return 12;
 374   case GlobalValue::LinkerPrivateLinkage:            return 13;
 375   case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
 376   case GlobalValue::LinkerPrivateWeakDefAutoLinkage: return 15;
 377   }
 378   llvm_unreachable("Invalid linkage");
 379 }
 380
 381 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 382   switch (GV->getVisibility()) {
 383   case GlobalValue::DefaultVisibility:   return 0;
 384   case GlobalValue::HiddenVisibility:    return 1;
 385   case GlobalValue::ProtectedVisibility: return 2;
 386   }
 387   llvm_unreachable("Invalid visibility");
 388 }
 389
 390 // Emit top-level description of module, including target triple, inline asm,
 391 // descriptors for global variables, and function prototype info.
 392 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 393                             BitstreamWriter &Stream) {
 394   // Emit the list of dependent libraries for the Module.
 395   for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
 396     WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
 397
 398   // Emit various pieces of data attached to a module.
 399   if (!M->getTargetTriple().empty())
 400     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 401                       0/*TODO*/, Stream);
 402   if (!M->getDataLayout().empty())
 403     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 404                       0/*TODO*/, Stream);
 405   if (!M->getModuleInlineAsm().empty())
 406     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 407                       0/*TODO*/, Stream);
 408
 409   // Emit information about sections and GC, computing how many there are. Also
 410   // compute the maximum alignment value.
 411   std::map<std::string, unsigned> SectionMap;
 412   std::map<std::string, unsigned> GCMap;
 413   unsigned MaxAlignment = 0;
 414   unsigned MaxGlobalType = 0;
 415   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 416        GV != E; ++GV) {
 417     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 418     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 419     if (GV->hasSection()) {
 420       // Give section names unique ID's.
 421       unsigned &Entry = SectionMap[GV->getSection()];
 422       if (!Entry) {
 423         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 424                           0/*TODO*/, Stream);
 425         Entry = SectionMap.size();
 426       }
 427     }
 428   }
 429   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 430     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 431     if (F->hasSection()) {
 432       // Give section names unique ID's.
 433       unsigned &Entry = SectionMap[F->getSection()];
 434       if (!Entry) {
 435         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 436                           0/*TODO*/, Stream);
 437         Entry = SectionMap.size();
 438       }
 439     }
 440     if (F->hasGC()) {
 441       // Same for GC names.
 442       unsigned &Entry = GCMap[F->getGC()];
 443       if (!Entry) {
 444         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 445                           0/*TODO*/, Stream);
 446         Entry = GCMap.size();
 447       }
 448     }
 449   }
 450
 451   // Emit abbrev for globals, now that we know # sections and max alignment.
 452   unsigned SimpleGVarAbbrev = 0;
 453   if (!M->global_empty()) {
 454     // Add an abbrev for common globals with no visibility or thread localness.
 455     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 456     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 457     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 458                               Log2_32_Ceil(MaxGlobalType+1)));
 459     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 460     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 461     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 462     if (MaxAlignment == 0)                                      // Alignment.
 463       Abbv->Add(BitCodeAbbrevOp(0));
 464     else {
 465       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 466       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 467                                Log2_32_Ceil(MaxEncAlignment+1)));
 468     }
 469     if (SectionMap.empty())                                    // Section.
 470       Abbv->Add(BitCodeAbbrevOp(0));
 471     else
 472       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 473                                Log2_32_Ceil(SectionMap.size()+1)));
 474     // Don't bother emitting vis + thread local.
 475     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 476   }
 477
 478   // Emit the global variable information.
 479   SmallVector<unsigned, 64> Vals;
 480   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 481        GV != E; ++GV) {
 482     unsigned AbbrevToUse = 0;
 483
 484     // GLOBALVAR: [type, isconst, initid,
 485     //             linkage, alignment, section, visibility, threadlocal,
 486     //             unnamed_addr]
 487     Vals.push_back(VE.getTypeID(GV->getType()));
 488     Vals.push_back(GV->isConstant());
 489     Vals.push_back(GV->isDeclaration() ? 0 :
 490                    (VE.getValueID(GV->getInitializer()) + 1));
 491     Vals.push_back(getEncodedLinkage(GV));
 492     Vals.push_back(Log2_32(GV->getAlignment())+1);
 493     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 494     if (GV->isThreadLocal() ||
 495         GV->getVisibility() != GlobalValue::DefaultVisibility ||
 496         GV->hasUnnamedAddr()) {
 497       Vals.push_back(getEncodedVisibility(GV));
 498       Vals.push_back(GV->isThreadLocal());
 499       Vals.push_back(GV->hasUnnamedAddr());
 500     } else {
 501       AbbrevToUse = SimpleGVarAbbrev;
 502     }
 503
 504     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 505     Vals.clear();
 506   }
 507
 508   // Emit the function proto information.
 509   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 510     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 511     //             section, visibility, gc, unnamed_addr]
 512     Vals.push_back(VE.getTypeID(F->getType()));
 513     Vals.push_back(F->getCallingConv());
 514     Vals.push_back(F->isDeclaration());
 515     Vals.push_back(getEncodedLinkage(F));
 516     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 517     Vals.push_back(Log2_32(F->getAlignment())+1);
 518     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 519     Vals.push_back(getEncodedVisibility(F));
 520     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 521     Vals.push_back(F->hasUnnamedAddr());
 522
 523     unsigned AbbrevToUse = 0;
 524     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 525     Vals.clear();
 526   }
 527
 528   // Emit the alias information.
 529   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 530        AI != E; ++AI) {
 531     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 532     Vals.push_back(VE.getTypeID(AI->getType()));
 533     Vals.push_back(VE.getValueID(AI->getAliasee()));
 534     Vals.push_back(getEncodedLinkage(AI));
 535     Vals.push_back(getEncodedVisibility(AI));
 536     unsigned AbbrevToUse = 0;
 537     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 538     Vals.clear();
 539   }
 540 }
 541
 542 static uint64_t GetOptimizationFlags(const Value *V) {
 543   uint64_t Flags = 0;
 544
 545   if (const OverflowingBinaryOperator *OBO =
 546         dyn_cast<OverflowingBinaryOperator>(V)) {
 547     if (OBO->hasNoSignedWrap())
 548       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 549     if (OBO->hasNoUnsignedWrap())
 550       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 551   } else if (const PossiblyExactOperator *PEO =
 552                dyn_cast<PossiblyExactOperator>(V)) {
 553     if (PEO->isExact())
 554       Flags |= 1 << bitc::PEO_EXACT;
 555   }
 556
 557   return Flags;
 558 }
 559
 560 static void WriteMDNode(const MDNode *N,
 561                         const ValueEnumerator &VE,
 562                         BitstreamWriter &Stream,
 563                         SmallVector<uint64_t, 64> &Record) {
 564   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 565     if (N->getOperand(i)) {
 566       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 567       Record.push_back(VE.getValueID(N->getOperand(i)));
 568     } else {
 569       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 570       Record.push_back(0);
 571     }
 572   }
 573   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 574                                            bitc::METADATA_NODE;
 575   Stream.EmitRecord(MDCode, Record, 0);
 576   Record.clear();
 577 }
 578
 579 static void WriteModuleMetadata(const Module *M,
 580                                 const ValueEnumerator &VE,
 581                                 BitstreamWriter &Stream) {
 582   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 583   bool StartedMetadataBlock = false;
 584   unsigned MDSAbbrev = 0;
 585   SmallVector<uint64_t, 64> Record;
 586   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 587
 588     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 589       if (!N->isFunctionLocal() || !N->getFunction()) {
 590         if (!StartedMetadataBlock) {
 591           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 592           StartedMetadataBlock = true;
 593         }
 594         WriteMDNode(N, VE, Stream, Record);
 595       }
 596     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 597       if (!StartedMetadataBlock)  {
 598         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 599
 600         // Abbrev for METADATA_STRING.
 601         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 602         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 603         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 604         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 605         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 606         StartedMetadataBlock = true;
 607       }
 608
 609       // Code: [strchar x N]
 610       Record.append(MDS->begin(), MDS->end());
 611
 612       // Emit the finished record.
 613       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 614       Record.clear();
 615     }
 616   }
 617
 618   // Write named metadata.
 619   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 620        E = M->named_metadata_end(); I != E; ++I) {
 621     const NamedMDNode *NMD = I;
 622     if (!StartedMetadataBlock)  {
 623       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 624       StartedMetadataBlock = true;
 625     }
 626
 627     // Write name.
 628     StringRef Str = NMD->getName();
 629     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 630       Record.push_back(Str[i]);
 631     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 632     Record.clear();
 633
 634     // Write named metadata operands.
 635     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 636       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 637     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 638     Record.clear();
 639   }
 640
 641   if (StartedMetadataBlock)
 642     Stream.ExitBlock();
 643 }
 644
 645 static void WriteFunctionLocalMetadata(const Function &F,
 646                                        const ValueEnumerator &VE,
 647                                        BitstreamWriter &Stream) {
 648   bool StartedMetadataBlock = false;
 649   SmallVector<uint64_t, 64> Record;
 650   const SmallVector<const MDNode *, 8> &Vals = VE.getFunctionLocalMDValues();
 651   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 652     if (const MDNode *N = Vals[i])
 653       if (N->isFunctionLocal() && N->getFunction() == &F) {
 654         if (!StartedMetadataBlock) {
 655           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 656           StartedMetadataBlock = true;
 657         }
 658         WriteMDNode(N, VE, Stream, Record);
 659       }
 660
 661   if (StartedMetadataBlock)
 662     Stream.ExitBlock();
 663 }
 664
 665 static void WriteMetadataAttachment(const Function &F,
 666                                     const ValueEnumerator &VE,
 667                                     BitstreamWriter &Stream) {
 668   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 669
 670   SmallVector<uint64_t, 64> Record;
 671
 672   // Write metadata attachments
 673   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 674   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 675
 676   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 677     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 678          I != E; ++I) {
 679       MDs.clear();
 680       I->getAllMetadataOtherThanDebugLoc(MDs);
 681
 682       // If no metadata, ignore instruction.
 683       if (MDs.empty()) continue;
 684
 685       Record.push_back(VE.getInstructionID(I));
 686
 687       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 688         Record.push_back(MDs[i].first);
 689         Record.push_back(VE.getValueID(MDs[i].second));
 690       }
 691       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 692       Record.clear();
 693     }
 694
 695   Stream.ExitBlock();
 696 }
 697
 698 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 699   SmallVector<uint64_t, 64> Record;
 700
 701   // Write metadata kinds
 702   // METADATA_KIND - [n x [id, name]]
 703   SmallVector<StringRef, 4> Names;
 704   M->getMDKindNames(Names);
 705
 706   if (Names.empty()) return;
 707
 708   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 709
 710   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 711     Record.push_back(MDKindID);
 712     StringRef KName = Names[MDKindID];
 713     Record.append(KName.begin(), KName.end());
 714
 715     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 716     Record.clear();
 717   }
 718
 719   Stream.ExitBlock();
 720 }
 721
 722 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 723                            const ValueEnumerator &VE,
 724                            BitstreamWriter &Stream, bool isGlobal) {
 725   if (FirstVal == LastVal) return;
 726
 727   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 728
 729   unsigned AggregateAbbrev = 0;
 730   unsigned String8Abbrev = 0;
 731   unsigned CString7Abbrev = 0;
 732   unsigned CString6Abbrev = 0;
 733   // If this is a constant pool for the module, emit module-specific abbrevs.
 734   if (isGlobal) {
 735     // Abbrev for CST_CODE_AGGREGATE.
 736     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 737     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 738     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 739     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 740     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 741
 742     // Abbrev for CST_CODE_STRING.
 743     Abbv = new BitCodeAbbrev();
 744     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 745     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 746     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 747     String8Abbrev = Stream.EmitAbbrev(Abbv);
 748     // Abbrev for CST_CODE_CSTRING.
 749     Abbv = new BitCodeAbbrev();
 750     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 751     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 752     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 753     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 754     // Abbrev for CST_CODE_CSTRING.
 755     Abbv = new BitCodeAbbrev();
 756     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 757     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 758     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 759     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 760   }
 761
 762   SmallVector<uint64_t, 64> Record;
 763
 764   const ValueEnumerator::ValueList &Vals = VE.getValues();
 765   Type *LastTy = 0;
 766   for (unsigned i = FirstVal; i != LastVal; ++i) {
 767     const Value *V = Vals[i].first;
 768     // If we need to switch types, do so now.
 769     if (V->getType() != LastTy) {
 770       LastTy = V->getType();
 771       Record.push_back(VE.getTypeID(LastTy));
 772       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 773                         CONSTANTS_SETTYPE_ABBREV);
 774       Record.clear();
 775     }
 776
 777     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 778       Record.push_back(unsigned(IA->hasSideEffects()) |
 779                        unsigned(IA->isAlignStack()) << 1);
 780
 781       // Add the asm string.
 782       const std::string &AsmStr = IA->getAsmString();
 783       Record.push_back(AsmStr.size());
 784       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 785         Record.push_back(AsmStr[i]);
 786
 787       // Add the constraint string.
 788       const std::string &ConstraintStr = IA->getConstraintString();
 789       Record.push_back(ConstraintStr.size());
 790       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 791         Record.push_back(ConstraintStr[i]);
 792       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 793       Record.clear();
 794       continue;
 795     }
 796     const Constant *C = cast<Constant>(V);
 797     unsigned Code = -1U;
 798     unsigned AbbrevToUse = 0;
 799     if (C->isNullValue()) {
 800       Code = bitc::CST_CODE_NULL;
 801     } else if (isa<UndefValue>(C)) {
 802       Code = bitc::CST_CODE_UNDEF;
 803     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 804       if (IV->getBitWidth() <= 64) {
 805         uint64_t V = IV->getSExtValue();
 806         if ((int64_t)V >= 0)
 807           Record.push_back(V << 1);
 808         else
 809           Record.push_back((-V << 1) | 1);
 810         Code = bitc::CST_CODE_INTEGER;
 811         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 812       } else {                             // Wide integers, > 64 bits in size.
 813         // We have an arbitrary precision integer value to write whose
 814         // bit width is > 64. However, in canonical unsigned integer
 815         // format it is likely that the high bits are going to be zero.
 816         // So, we only write the number of active words.
 817         unsigned NWords = IV->getValue().getActiveWords();
 818         const uint64_t *RawWords = IV->getValue().getRawData();
 819         for (unsigned i = 0; i != NWords; ++i) {
 820           int64_t V = RawWords[i];
 821           if (V >= 0)
 822             Record.push_back(V << 1);
 823           else
 824             Record.push_back((-V << 1) | 1);
 825         }
 826         Code = bitc::CST_CODE_WIDE_INTEGER;
 827       }
 828     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 829       Code = bitc::CST_CODE_FLOAT;
 830       Type *Ty = CFP->getType();
 831       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 832         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 833       } else if (Ty->isX86_FP80Ty()) {
 834         // api needed to prevent premature destruction
 835         // bits are not in the same order as a normal i80 APInt, compensate.
 836         APInt api = CFP->getValueAPF().bitcastToAPInt();
 837         const uint64_t *p = api.getRawData();
 838         Record.push_back((p[1] << 48) | (p[0] >> 16));
 839         Record.push_back(p[0] & 0xffffLL);
 840       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 841         APInt api = CFP->getValueAPF().bitcastToAPInt();
 842         const uint64_t *p = api.getRawData();
 843         Record.push_back(p[0]);
 844         Record.push_back(p[1]);
 845       } else {
 846         assert (0 && "Unknown FP type!");
 847       }
 848     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 849       const ConstantArray *CA = cast<ConstantArray>(C);
 850       // Emit constant strings specially.
 851       unsigned NumOps = CA->getNumOperands();
 852       // If this is a null-terminated string, use the denser CSTRING encoding.
 853       if (CA->getOperand(NumOps-1)->isNullValue()) {
 854         Code = bitc::CST_CODE_CSTRING;
 855         --NumOps;  // Don't encode the null, which isn't allowed by char6.
 856       } else {
 857         Code = bitc::CST_CODE_STRING;
 858         AbbrevToUse = String8Abbrev;
 859       }
 860       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 861       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 862       for (unsigned i = 0; i != NumOps; ++i) {
 863         unsigned char V = cast<ConstantInt>(CA->getOperand(i))->getZExtValue();
 864         Record.push_back(V);
 865         isCStr7 &= (V & 128) == 0;
 866         if (isCStrChar6)
 867           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 868       }
 869
 870       if (isCStrChar6)
 871         AbbrevToUse = CString6Abbrev;
 872       else if (isCStr7)
 873         AbbrevToUse = CString7Abbrev;
 874     } else if (isa<ConstantDataSequential>(C) &&
 875                cast<ConstantDataSequential>(C)->isString()) {
 876       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 877       // Emit constant strings specially.
 878       unsigned NumElts = Str->getNumElements();
 879       // If this is a null-terminated string, use the denser CSTRING encoding.
 880       if (Str->isCString()) {
 881         Code = bitc::CST_CODE_CSTRING;
 882         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 883       } else {
 884         Code = bitc::CST_CODE_STRING;
 885         AbbrevToUse = String8Abbrev;
 886       }
 887       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 888       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 889       for (unsigned i = 0; i != NumElts; ++i) {
 890         unsigned char V = Str->getElementAsInteger(i);
 891         Record.push_back(V);
 892         isCStr7 &= (V & 128) == 0;
 893         if (isCStrChar6)
 894           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 895       }
 896
 897       if (isCStrChar6)
 898         AbbrevToUse = CString6Abbrev;
 899       else if (isCStr7)
 900         AbbrevToUse = CString7Abbrev;
 901     } else if (const ConstantDataSequential *CDS =
 902                   dyn_cast<ConstantDataSequential>(C)) {
 903       Type *EltTy = CDS->getType()->getElementType();
 904       if (isa<IntegerType>(EltTy)) {
 905         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
 906           Record.push_back(CDS->getElementAsInteger(i));
 907       } else if (EltTy->isFloatTy()) {
 908         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 909           union { float F; uint32_t I; };
 910           F = CDS->getElementAsFloat(i);
 911           Record.push_back(I);
 912         }
 913       } else {
 914         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
 915         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 916           union { double F; uint64_t I; };
 917           F = CDS->getElementAsDouble(i);
 918           Record.push_back(I);
 919         }
 920       }
 921     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
 922                isa<ConstantVector>(C)) {
 923       Code = bitc::CST_CODE_AGGREGATE;
 924       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 925         Record.push_back(VE.getValueID(C->getOperand(i)));
 926       AbbrevToUse = AggregateAbbrev;
 927     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 928       switch (CE->getOpcode()) {
 929       default:
 930         if (Instruction::isCast(CE->getOpcode())) {
 931           Code = bitc::CST_CODE_CE_CAST;
 932           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 933           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 934           Record.push_back(VE.getValueID(C->getOperand(0)));
 935           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 936         } else {
 937           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 938           Code = bitc::CST_CODE_CE_BINOP;
 939           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 940           Record.push_back(VE.getValueID(C->getOperand(0)));
 941           Record.push_back(VE.getValueID(C->getOperand(1)));
 942           uint64_t Flags = GetOptimizationFlags(CE);
 943           if (Flags != 0)
 944             Record.push_back(Flags);
 945         }
 946         break;
 947       case Instruction::GetElementPtr:
 948         Code = bitc::CST_CODE_CE_GEP;
 949         if (cast<GEPOperator>(C)->isInBounds())
 950           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
 951         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 952           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 953           Record.push_back(VE.getValueID(C->getOperand(i)));
 954         }
 955         break;
 956       case Instruction::Select:
 957         Code = bitc::CST_CODE_CE_SELECT;
 958         Record.push_back(VE.getValueID(C->getOperand(0)));
 959         Record.push_back(VE.getValueID(C->getOperand(1)));
 960         Record.push_back(VE.getValueID(C->getOperand(2)));
 961         break;
 962       case Instruction::ExtractElement:
 963         Code = bitc::CST_CODE_CE_EXTRACTELT;
 964         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 965         Record.push_back(VE.getValueID(C->getOperand(0)));
 966         Record.push_back(VE.getValueID(C->getOperand(1)));
 967         break;
 968       case Instruction::InsertElement:
 969         Code = bitc::CST_CODE_CE_INSERTELT;
 970         Record.push_back(VE.getValueID(C->getOperand(0)));
 971         Record.push_back(VE.getValueID(C->getOperand(1)));
 972         Record.push_back(VE.getValueID(C->getOperand(2)));
 973         break;
 974       case Instruction::ShuffleVector:
 975         // If the return type and argument types are the same, this is a
 976         // standard shufflevector instruction.  If the types are different,
 977         // then the shuffle is widening or truncating the input vectors, and
 978         // the argument type must also be encoded.
 979         if (C->getType() == C->getOperand(0)->getType()) {
 980           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 981         } else {
 982           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 983           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 984         }
 985         Record.push_back(VE.getValueID(C->getOperand(0)));
 986         Record.push_back(VE.getValueID(C->getOperand(1)));
 987         Record.push_back(VE.getValueID(C->getOperand(2)));
 988         break;
 989       case Instruction::ICmp:
 990       case Instruction::FCmp:
 991         Code = bitc::CST_CODE_CE_CMP;
 992         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 993         Record.push_back(VE.getValueID(C->getOperand(0)));
 994         Record.push_back(VE.getValueID(C->getOperand(1)));
 995         Record.push_back(CE->getPredicate());
 996         break;
 997       }
 998     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
 999       Code = bitc::CST_CODE_BLOCKADDRESS;
1000       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1001       Record.push_back(VE.getValueID(BA->getFunction()));
1002       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1003     } else {
1004 #ifndef NDEBUG
1005       C->dump();
1006 #endif
1007       llvm_unreachable("Unknown constant!");
1008     }
1009     Stream.EmitRecord(Code, Record, AbbrevToUse);
1010     Record.clear();
1011   }
1012
1013   Stream.ExitBlock();
1014 }
1015
1016 static void WriteModuleConstants(const ValueEnumerator &VE,
1017                                  BitstreamWriter &Stream) {
1018   const ValueEnumerator::ValueList &Vals = VE.getValues();
1019
1020   // Find the first constant to emit, which is the first non-globalvalue value.
1021   // We know globalvalues have been emitted by WriteModuleInfo.
1022   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1023     if (!isa<GlobalValue>(Vals[i].first)) {
1024       WriteConstants(i, Vals.size(), VE, Stream, true);
1025       return;
1026     }
1027   }
1028 }
1029
1030 /// PushValueAndType - The file has to encode both the value and type id for
1031 /// many values, because we need to know what type to create for forward
1032 /// references.  However, most operands are not forward references, so this type
1033 /// field is not needed.
1034 ///
1035 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1036 /// instruction ID, then it is a forward reference, and it also includes the
1037 /// type ID.
1038 static bool PushValueAndType(const Value *V, unsigned InstID,
1039                              SmallVector<unsigned, 64> &Vals,
1040                              ValueEnumerator &VE) {
1041   unsigned ValID = VE.getValueID(V);
1042   Vals.push_back(ValID);
1043   if (ValID >= InstID) {
1044     Vals.push_back(VE.getTypeID(V->getType()));
1045     return true;
1046   }
1047   return false;
1048 }
1049
1050 /// WriteInstruction - Emit an instruction to the specified stream.
1051 static void WriteInstruction(const Instruction &I, unsigned InstID,
1052                              ValueEnumerator &VE, BitstreamWriter &Stream,
1053                              SmallVector<unsigned, 64> &Vals) {
1054   unsigned Code = 0;
1055   unsigned AbbrevToUse = 0;
1056   VE.setInstructionID(&I);
1057   switch (I.getOpcode()) {
1058   default:
1059     if (Instruction::isCast(I.getOpcode())) {
1060       Code = bitc::FUNC_CODE_INST_CAST;
1061       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1062         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1063       Vals.push_back(VE.getTypeID(I.getType()));
1064       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1065     } else {
1066       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1067       Code = bitc::FUNC_CODE_INST_BINOP;
1068       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1069         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1070       Vals.push_back(VE.getValueID(I.getOperand(1)));
1071       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1072       uint64_t Flags = GetOptimizationFlags(&I);
1073       if (Flags != 0) {
1074         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1075           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1076         Vals.push_back(Flags);
1077       }
1078     }
1079     break;
1080
1081   case Instruction::GetElementPtr:
1082     Code = bitc::FUNC_CODE_INST_GEP;
1083     if (cast<GEPOperator>(&I)->isInBounds())
1084       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1085     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1086       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1087     break;
1088   case Instruction::ExtractValue: {
1089     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1090     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1091     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1092     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1093       Vals.push_back(*i);
1094     break;
1095   }
1096   case Instruction::InsertValue: {
1097     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1098     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1099     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1100     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1101     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1102       Vals.push_back(*i);
1103     break;
1104   }
1105   case Instruction::Select:
1106     Code = bitc::FUNC_CODE_INST_VSELECT;
1107     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1108     Vals.push_back(VE.getValueID(I.getOperand(2)));
1109     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1110     break;
1111   case Instruction::ExtractElement:
1112     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1113     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1114     Vals.push_back(VE.getValueID(I.getOperand(1)));
1115     break;
1116   case Instruction::InsertElement:
1117     Code = bitc::FUNC_CODE_INST_INSERTELT;
1118     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1119     Vals.push_back(VE.getValueID(I.getOperand(1)));
1120     Vals.push_back(VE.getValueID(I.getOperand(2)));
1121     break;
1122   case Instruction::ShuffleVector:
1123     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1124     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1125     Vals.push_back(VE.getValueID(I.getOperand(1)));
1126     Vals.push_back(VE.getValueID(I.getOperand(2)));
1127     break;
1128   case Instruction::ICmp:
1129   case Instruction::FCmp:
1130     // compare returning Int1Ty or vector of Int1Ty
1131     Code = bitc::FUNC_CODE_INST_CMP2;
1132     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1133     Vals.push_back(VE.getValueID(I.getOperand(1)));
1134     Vals.push_back(cast<CmpInst>(I).getPredicate());
1135     break;
1136
1137   case Instruction::Ret:
1138     {
1139       Code = bitc::FUNC_CODE_INST_RET;
1140       unsigned NumOperands = I.getNumOperands();
1141       if (NumOperands == 0)
1142         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1143       else if (NumOperands == 1) {
1144         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1145           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1146       } else {
1147         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1148           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1149       }
1150     }
1151     break;
1152   case Instruction::Br:
1153     {
1154       Code = bitc::FUNC_CODE_INST_BR;
1155       BranchInst &II = cast<BranchInst>(I);
1156       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1157       if (II.isConditional()) {
1158         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1159         Vals.push_back(VE.getValueID(II.getCondition()));
1160       }
1161     }
1162     break;
1163   case Instruction::Switch:
1164     Code = bitc::FUNC_CODE_INST_SWITCH;
1165     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1166     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1167       Vals.push_back(VE.getValueID(I.getOperand(i)));
1168     break;
1169   case Instruction::IndirectBr:
1170     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1171     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1172     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1173       Vals.push_back(VE.getValueID(I.getOperand(i)));
1174     break;
1175
1176   case Instruction::Invoke: {
1177     const InvokeInst *II = cast<InvokeInst>(&I);
1178     const Value *Callee(II->getCalledValue());
1179     PointerType *PTy = cast<PointerType>(Callee->getType());
1180     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1181     Code = bitc::FUNC_CODE_INST_INVOKE;
1182
1183     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1184     Vals.push_back(II->getCallingConv());
1185     Vals.push_back(VE.getValueID(II->getNormalDest()));
1186     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1187     PushValueAndType(Callee, InstID, Vals, VE);
1188
1189     // Emit value #'s for the fixed parameters.
1190     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1191       Vals.push_back(VE.getValueID(I.getOperand(i)));  // fixed param.
1192
1193     // Emit type/value pairs for varargs params.
1194     if (FTy->isVarArg()) {
1195       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1196            i != e; ++i)
1197         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1198     }
1199     break;
1200   }
1201   case Instruction::Resume:
1202     Code = bitc::FUNC_CODE_INST_RESUME;
1203     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1204     break;
1205   case Instruction::Unwind:
1206     Code = bitc::FUNC_CODE_INST_UNWIND;
1207     break;
1208   case Instruction::Unreachable:
1209     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1210     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1211     break;
1212
1213   case Instruction::PHI: {
1214     const PHINode &PN = cast<PHINode>(I);
1215     Code = bitc::FUNC_CODE_INST_PHI;
1216     Vals.push_back(VE.getTypeID(PN.getType()));
1217     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1218       Vals.push_back(VE.getValueID(PN.getIncomingValue(i)));
1219       Vals.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1220     }
1221     break;
1222   }
1223
1224   case Instruction::LandingPad: {
1225     const LandingPadInst &LP = cast<LandingPadInst>(I);
1226     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1227     Vals.push_back(VE.getTypeID(LP.getType()));
1228     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1229     Vals.push_back(LP.isCleanup());
1230     Vals.push_back(LP.getNumClauses());
1231     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1232       if (LP.isCatch(I))
1233         Vals.push_back(LandingPadInst::Catch);
1234       else
1235         Vals.push_back(LandingPadInst::Filter);
1236       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1237     }
1238     break;
1239   }
1240
1241   case Instruction::Alloca:
1242     Code = bitc::FUNC_CODE_INST_ALLOCA;
1243     Vals.push_back(VE.getTypeID(I.getType()));
1244     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1245     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1246     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1247     break;
1248
1249   case Instruction::Load:
1250     if (cast<LoadInst>(I).isAtomic()) {
1251       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1252       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1253     } else {
1254       Code = bitc::FUNC_CODE_INST_LOAD;
1255       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1256         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1257     }
1258     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1259     Vals.push_back(cast<LoadInst>(I).isVolatile());
1260     if (cast<LoadInst>(I).isAtomic()) {
1261       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1262       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1263     }
1264     break;
1265   case Instruction::Store:
1266     if (cast<StoreInst>(I).isAtomic())
1267       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1268     else
1269       Code = bitc::FUNC_CODE_INST_STORE;
1270     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1271     Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
1272     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1273     Vals.push_back(cast<StoreInst>(I).isVolatile());
1274     if (cast<StoreInst>(I).isAtomic()) {
1275       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1276       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1277     }
1278     break;
1279   case Instruction::AtomicCmpXchg:
1280     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1281     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1282     Vals.push_back(VE.getValueID(I.getOperand(1)));       // cmp.
1283     Vals.push_back(VE.getValueID(I.getOperand(2)));       // newval.
1284     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1285     Vals.push_back(GetEncodedOrdering(
1286                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1287     Vals.push_back(GetEncodedSynchScope(
1288                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1289     break;
1290   case Instruction::AtomicRMW:
1291     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1292     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1293     Vals.push_back(VE.getValueID(I.getOperand(1)));       // val.
1294     Vals.push_back(GetEncodedRMWOperation(
1295                      cast<AtomicRMWInst>(I).getOperation()));
1296     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1297     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1298     Vals.push_back(GetEncodedSynchScope(
1299                      cast<AtomicRMWInst>(I).getSynchScope()));
1300     break;
1301   case Instruction::Fence:
1302     Code = bitc::FUNC_CODE_INST_FENCE;
1303     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1304     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1305     break;
1306   case Instruction::Call: {
1307     const CallInst &CI = cast<CallInst>(I);
1308     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1309     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1310
1311     Code = bitc::FUNC_CODE_INST_CALL;
1312
1313     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1314     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1315     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1316
1317     // Emit value #'s for the fixed parameters.
1318     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1319       Vals.push_back(VE.getValueID(CI.getArgOperand(i)));  // fixed param.
1320
1321     // Emit type/value pairs for varargs params.
1322     if (FTy->isVarArg()) {
1323       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1324            i != e; ++i)
1325         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1326     }
1327     break;
1328   }
1329   case Instruction::VAArg:
1330     Code = bitc::FUNC_CODE_INST_VAARG;
1331     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1332     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1333     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1334     break;
1335   }
1336
1337   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1338   Vals.clear();
1339 }
1340
1341 // Emit names for globals/functions etc.
1342 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1343                                   const ValueEnumerator &VE,
1344                                   BitstreamWriter &Stream) {
1345   if (VST.empty()) return;
1346   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1347
1348   // FIXME: Set up the abbrev, we know how many values there are!
1349   // FIXME: We know if the type names can use 7-bit ascii.
1350   SmallVector<unsigned, 64> NameVals;
1351
1352   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1353        SI != SE; ++SI) {
1354
1355     const ValueName &Name = *SI;
1356
1357     // Figure out the encoding to use for the name.
1358     bool is7Bit = true;
1359     bool isChar6 = true;
1360     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1361          C != E; ++C) {
1362       if (isChar6)
1363         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1364       if ((unsigned char)*C & 128) {
1365         is7Bit = false;
1366         break;  // don't bother scanning the rest.
1367       }
1368     }
1369
1370     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1371
1372     // VST_ENTRY:   [valueid, namechar x N]
1373     // VST_BBENTRY: [bbid, namechar x N]
1374     unsigned Code;
1375     if (isa<BasicBlock>(SI->getValue())) {
1376       Code = bitc::VST_CODE_BBENTRY;
1377       if (isChar6)
1378         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1379     } else {
1380       Code = bitc::VST_CODE_ENTRY;
1381       if (isChar6)
1382         AbbrevToUse = VST_ENTRY_6_ABBREV;
1383       else if (is7Bit)
1384         AbbrevToUse = VST_ENTRY_7_ABBREV;
1385     }
1386
1387     NameVals.push_back(VE.getValueID(SI->getValue()));
1388     for (const char *P = Name.getKeyData(),
1389          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1390       NameVals.push_back((unsigned char)*P);
1391
1392     // Emit the finished record.
1393     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1394     NameVals.clear();
1395   }
1396   Stream.ExitBlock();
1397 }
1398
1399 /// WriteFunction - Emit a function body to the module stream.
1400 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1401                           BitstreamWriter &Stream) {
1402   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1403   VE.incorporateFunction(F);
1404
1405   SmallVector<unsigned, 64> Vals;
1406
1407   // Emit the number of basic blocks, so the reader can create them ahead of
1408   // time.
1409   Vals.push_back(VE.getBasicBlocks().size());
1410   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1411   Vals.clear();
1412
1413   // If there are function-local constants, emit them now.
1414   unsigned CstStart, CstEnd;
1415   VE.getFunctionConstantRange(CstStart, CstEnd);
1416   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1417
1418   // If there is function-local metadata, emit it now.
1419   WriteFunctionLocalMetadata(F, VE, Stream);
1420
1421   // Keep a running idea of what the instruction ID is.
1422   unsigned InstID = CstEnd;
1423
1424   bool NeedsMetadataAttachment = false;
1425
1426   DebugLoc LastDL;
1427
1428   // Finally, emit all the instructions, in order.
1429   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1430     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1431          I != E; ++I) {
1432       WriteInstruction(*I, InstID, VE, Stream, Vals);
1433
1434       if (!I->getType()->isVoidTy())
1435         ++InstID;
1436
1437       // If the instruction has metadata, write a metadata attachment later.
1438       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1439
1440       // If the instruction has a debug location, emit it.
1441       DebugLoc DL = I->getDebugLoc();
1442       if (DL.isUnknown()) {
1443         // nothing todo.
1444       } else if (DL == LastDL) {
1445         // Just repeat the same debug loc as last time.
1446         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1447       } else {
1448         MDNode *Scope, *IA;
1449         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1450
1451         Vals.push_back(DL.getLine());
1452         Vals.push_back(DL.getCol());
1453         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1454         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1455         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1456         Vals.clear();
1457
1458         LastDL = DL;
1459       }
1460     }
1461
1462   // Emit names for all the instructions etc.
1463   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1464
1465   if (NeedsMetadataAttachment)
1466     WriteMetadataAttachment(F, VE, Stream);
1467   VE.purgeFunction();
1468   Stream.ExitBlock();
1469 }
1470
1471 // Emit blockinfo, which defines the standard abbreviations etc.
1472 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1473   // We only want to emit block info records for blocks that have multiple
1474   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1475   // blocks can defined their abbrevs inline.
1476   Stream.EnterBlockInfoBlock(2);
1477
1478   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1479     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1480     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1481     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1482     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1483     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1484     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1485                                    Abbv) != VST_ENTRY_8_ABBREV)
1486       llvm_unreachable("Unexpected abbrev ordering!");
1487   }
1488
1489   { // 7-bit fixed width VST_ENTRY strings.
1490     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1491     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1492     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1493     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1494     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1495     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1496                                    Abbv) != VST_ENTRY_7_ABBREV)
1497       llvm_unreachable("Unexpected abbrev ordering!");
1498   }
1499   { // 6-bit char6 VST_ENTRY strings.
1500     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1501     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1502     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1503     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1504     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1505     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1506                                    Abbv) != VST_ENTRY_6_ABBREV)
1507       llvm_unreachable("Unexpected abbrev ordering!");
1508   }
1509   { // 6-bit char6 VST_BBENTRY strings.
1510     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1511     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1512     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1513     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1514     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1515     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1516                                    Abbv) != VST_BBENTRY_6_ABBREV)
1517       llvm_unreachable("Unexpected abbrev ordering!");
1518   }
1519
1520
1521
1522   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1523     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1524     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1525     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1526                               Log2_32_Ceil(VE.getTypes().size()+1)));
1527     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1528                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1529       llvm_unreachable("Unexpected abbrev ordering!");
1530   }
1531
1532   { // INTEGER abbrev for CONSTANTS_BLOCK.
1533     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1534     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1535     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1536     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1537                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1538       llvm_unreachable("Unexpected abbrev ordering!");
1539   }
1540
1541   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1542     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1543     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1544     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1545     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1546                               Log2_32_Ceil(VE.getTypes().size()+1)));
1547     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1548
1549     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1550                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1551       llvm_unreachable("Unexpected abbrev ordering!");
1552   }
1553   { // NULL abbrev for CONSTANTS_BLOCK.
1554     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1555     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1556     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1557                                    Abbv) != CONSTANTS_NULL_Abbrev)
1558       llvm_unreachable("Unexpected abbrev ordering!");
1559   }
1560
1561   // FIXME: This should only use space for first class types!
1562
1563   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1564     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1565     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1566     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1567     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1568     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1569     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1570                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1571       llvm_unreachable("Unexpected abbrev ordering!");
1572   }
1573   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1574     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1575     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1576     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1577     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1578     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1579     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1580                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1581       llvm_unreachable("Unexpected abbrev ordering!");
1582   }
1583   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1584     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1585     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1586     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1587     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1588     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1589     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1590     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1591                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1592       llvm_unreachable("Unexpected abbrev ordering!");
1593   }
1594   { // INST_CAST abbrev for FUNCTION_BLOCK.
1595     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1596     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1597     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1598     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1599                               Log2_32_Ceil(VE.getTypes().size()+1)));
1600     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1601     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1602                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1603       llvm_unreachable("Unexpected abbrev ordering!");
1604   }
1605
1606   { // INST_RET abbrev for FUNCTION_BLOCK.
1607     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1608     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1609     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1610                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1611       llvm_unreachable("Unexpected abbrev ordering!");
1612   }
1613   { // INST_RET abbrev for FUNCTION_BLOCK.
1614     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1615     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1616     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1617     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1618                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1619       llvm_unreachable("Unexpected abbrev ordering!");
1620   }
1621   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1622     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1623     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1624     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1625                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1626       llvm_unreachable("Unexpected abbrev ordering!");
1627   }
1628
1629   Stream.ExitBlock();
1630 }
1631
1632 // Sort the Users based on the order in which the reader parses the bitcode
1633 // file.
1634 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1635   // TODO: Implement.
1636   return true;
1637 }
1638
1639 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1640                          BitstreamWriter &Stream) {
1641
1642   // One or zero uses can't get out of order.
1643   if (V->use_empty() || V->hasNUses(1))
1644     return;
1645
1646   // Make a copy of the in-memory use-list for sorting.
1647   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1648   SmallVector<const User*, 8> UseList;
1649   UseList.reserve(UseListSize);
1650   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1651        I != E; ++I) {
1652     const User *U = *I;
1653     UseList.push_back(U);
1654   }
1655
1656   // Sort the copy based on the order read by the BitcodeReader.
1657   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1658
1659   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1660   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1661
1662   // TODO: Emit the USELIST_CODE_ENTRYs.
1663 }
1664
1665 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1666                                  BitstreamWriter &Stream) {
1667   VE.incorporateFunction(*F);
1668
1669   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1670        AI != AE; ++AI)
1671     WriteUseList(AI, VE, Stream);
1672   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1673        ++BB) {
1674     WriteUseList(BB, VE, Stream);
1675     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1676          ++II) {
1677       WriteUseList(II, VE, Stream);
1678       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1679            OI != E; ++OI) {
1680         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1681             isa<InlineAsm>(*OI))
1682           WriteUseList(*OI, VE, Stream);
1683       }
1684     }
1685   }
1686   VE.purgeFunction();
1687 }
1688
1689 // Emit use-lists.
1690 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1691                                 BitstreamWriter &Stream) {
1692   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1693
1694   // XXX: this modifies the module, but in a way that should never change the
1695   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1696   // contain entries in the use_list that do not exist in the Module and are
1697   // not stored in the .bc file.
1698   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1699        I != E; ++I)
1700     I->removeDeadConstantUsers();
1701
1702   // Write the global variables.
1703   for (Module::const_global_iterator GI = M->global_begin(),
1704          GE = M->global_end(); GI != GE; ++GI) {
1705     WriteUseList(GI, VE, Stream);
1706
1707     // Write the global variable initializers.
1708     if (GI->hasInitializer())
1709       WriteUseList(GI->getInitializer(), VE, Stream);
1710   }
1711
1712   // Write the functions.
1713   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1714     WriteUseList(FI, VE, Stream);
1715     if (!FI->isDeclaration())
1716       WriteFunctionUseList(FI, VE, Stream);
1717   }
1718
1719   // Write the aliases.
1720   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1721        AI != AE; ++AI) {
1722     WriteUseList(AI, VE, Stream);
1723     WriteUseList(AI->getAliasee(), VE, Stream);
1724   }
1725
1726   Stream.ExitBlock();
1727 }
1728
1729 /// WriteModule - Emit the specified module to the bitstream.
1730 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1731   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1732
1733   // Emit the version number if it is non-zero.
1734   if (CurVersion) {
1735     SmallVector<unsigned, 1> Vals;
1736     Vals.push_back(CurVersion);
1737     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1738   }
1739
1740   // Analyze the module, enumerating globals, functions, etc.
1741   ValueEnumerator VE(M);
1742
1743   // Emit blockinfo, which defines the standard abbreviations etc.
1744   WriteBlockInfo(VE, Stream);
1745
1746   // Emit information about parameter attributes.
1747   WriteAttributeTable(VE, Stream);
1748
1749   // Emit information describing all of the types in the module.
1750   WriteTypeTable(VE, Stream);
1751
1752   // Emit top-level description of module, including target triple, inline asm,
1753   // descriptors for global variables, and function prototype info.
1754   WriteModuleInfo(M, VE, Stream);
1755
1756   // Emit constants.
1757   WriteModuleConstants(VE, Stream);
1758
1759   // Emit metadata.
1760   WriteModuleMetadata(M, VE, Stream);
1761
1762   // Emit function bodies.
1763   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1764     if (!F->isDeclaration())
1765       WriteFunction(*F, VE, Stream);
1766
1767   // Emit metadata.
1768   WriteModuleMetadataStore(M, Stream);
1769
1770   // Emit names for globals/functions etc.
1771   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1772
1773   // Emit use-lists.
1774   if (EnablePreserveUseListOrdering)
1775     WriteModuleUseLists(M, VE, Stream);
1776
1777   Stream.ExitBlock();
1778 }
1779
1780 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1781 /// header and trailer to make it compatible with the system archiver.  To do
1782 /// this we emit the following header, and then emit a trailer that pads the
1783 /// file out to be a multiple of 16 bytes.
1784 ///
1785 /// struct bc_header {
1786 ///   uint32_t Magic;         // 0x0B17C0DE
1787 ///   uint32_t Version;       // Version, currently always 0.
1788 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1789 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1790 ///   uint32_t CPUType;       // CPU specifier.
1791 ///   ... potentially more later ...
1792 /// };
1793 enum {
1794   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1795   DarwinBCHeaderSize = 5*4
1796 };
1797
1798 static void EmitDarwinBCHeader(BitstreamWriter &Stream, const Triple &TT) {
1799   unsigned CPUType = ~0U;
1800
1801   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1802   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1803   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1804   // specific constants here because they are implicitly part of the Darwin ABI.
1805   enum {
1806     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1807     DARWIN_CPU_TYPE_X86        = 7,
1808     DARWIN_CPU_TYPE_ARM        = 12,
1809     DARWIN_CPU_TYPE_POWERPC    = 18
1810   };
1811
1812   Triple::ArchType Arch = TT.getArch();
1813   if (Arch == Triple::x86_64)
1814     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1815   else if (Arch == Triple::x86)
1816     CPUType = DARWIN_CPU_TYPE_X86;
1817   else if (Arch == Triple::ppc)
1818     CPUType = DARWIN_CPU_TYPE_POWERPC;
1819   else if (Arch == Triple::ppc64)
1820     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1821   else if (Arch == Triple::arm || Arch == Triple::thumb)
1822     CPUType = DARWIN_CPU_TYPE_ARM;
1823
1824   // Traditional Bitcode starts after header.
1825   unsigned BCOffset = DarwinBCHeaderSize;
1826
1827   Stream.Emit(0x0B17C0DE, 32);
1828   Stream.Emit(0         , 32);  // Version.
1829   Stream.Emit(BCOffset  , 32);
1830   Stream.Emit(0         , 32);  // Filled in later.
1831   Stream.Emit(CPUType   , 32);
1832 }
1833
1834 /// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1835 /// finalize the header.
1836 static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1837   // Update the size field in the header.
1838   Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1839
1840   // If the file is not a multiple of 16 bytes, insert dummy padding.
1841   while (BufferSize & 15) {
1842     Stream.Emit(0, 8);
1843     ++BufferSize;
1844   }
1845 }
1846
1847
1848 /// WriteBitcodeToFile - Write the specified module to the specified output
1849 /// stream.
1850 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1851   std::vector<unsigned char> Buffer;
1852   BitstreamWriter Stream(Buffer);
1853
1854   Buffer.reserve(256*1024);
1855
1856   WriteBitcodeToStream( M, Stream );
1857
1858   // Write the generated bitstream to "Out".
1859   Out.write((char*)&Buffer.front(), Buffer.size());
1860 }
1861
1862 /// WriteBitcodeToStream - Write the specified module to the specified output
1863 /// stream.
1864 void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1865   // If this is darwin or another generic macho target, emit a file header and
1866   // trailer if needed.
1867   Triple TT(M->getTargetTriple());
1868   if (TT.isOSDarwin())
1869     EmitDarwinBCHeader(Stream, TT);
1870
1871   // Emit the file header.
1872   Stream.Emit((unsigned)'B', 8);
1873   Stream.Emit((unsigned)'C', 8);
1874   Stream.Emit(0x0, 4);
1875   Stream.Emit(0xC, 4);
1876   Stream.Emit(0xE, 4);
1877   Stream.Emit(0xD, 4);
1878
1879   // Emit the module.
1880   WriteModule(M, Stream);
1881
1882   if (TT.isOSDarwin())
1883     EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1884 }