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 "ValueEnumerator.h"
  16 #include "llvm/ADT/Triple.h"
  17 #include "llvm/Bitcode/BitstreamWriter.h"
  18 #include "llvm/Bitcode/LLVMBitCodes.h"
  19 #include "llvm/IR/Constants.h"
  20 #include "llvm/IR/DerivedTypes.h"
  21 #include "llvm/IR/InlineAsm.h"
  22 #include "llvm/IR/Instructions.h"
  23 #include "llvm/IR/Module.h"
  24 #include "llvm/IR/Operator.h"
  25 #include "llvm/IR/ValueSymbolTable.h"
  26 #include "llvm/Support/CommandLine.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Support/MathExtras.h"
  29 #include "llvm/Support/Program.h"
  30 #include "llvm/Support/raw_ostream.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   // VALUE_SYMTAB_BLOCK abbrev id's.
  45   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  46   VST_ENTRY_7_ABBREV,
  47   VST_ENTRY_6_ABBREV,
  48   VST_BBENTRY_6_ABBREV,
  49
  50   // CONSTANTS_BLOCK abbrev id's.
  51   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  52   CONSTANTS_INTEGER_ABBREV,
  53   CONSTANTS_CE_CAST_Abbrev,
  54   CONSTANTS_NULL_Abbrev,
  55
  56   // FUNCTION_BLOCK abbrev id's.
  57   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  58   FUNCTION_INST_BINOP_ABBREV,
  59   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  60   FUNCTION_INST_CAST_ABBREV,
  61   FUNCTION_INST_RET_VOID_ABBREV,
  62   FUNCTION_INST_RET_VAL_ABBREV,
  63   FUNCTION_INST_UNREACHABLE_ABBREV
  64 };
  65
  66 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  67   switch (Opcode) {
  68   default: llvm_unreachable("Unknown cast instruction!");
  69   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  70   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  71   case Instruction::SExt    : return bitc::CAST_SEXT;
  72   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  73   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  74   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  75   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  76   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  77   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  78   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  79   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  80   case Instruction::BitCast : return bitc::CAST_BITCAST;
  81   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
  82   }
  83 }
  84
  85 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  86   switch (Opcode) {
  87   default: llvm_unreachable("Unknown binary instruction!");
  88   case Instruction::Add:
  89   case Instruction::FAdd: return bitc::BINOP_ADD;
  90   case Instruction::Sub:
  91   case Instruction::FSub: return bitc::BINOP_SUB;
  92   case Instruction::Mul:
  93   case Instruction::FMul: return bitc::BINOP_MUL;
  94   case Instruction::UDiv: return bitc::BINOP_UDIV;
  95   case Instruction::FDiv:
  96   case Instruction::SDiv: return bitc::BINOP_SDIV;
  97   case Instruction::URem: return bitc::BINOP_UREM;
  98   case Instruction::FRem:
  99   case Instruction::SRem: return bitc::BINOP_SREM;
 100   case Instruction::Shl:  return bitc::BINOP_SHL;
 101   case Instruction::LShr: return bitc::BINOP_LSHR;
 102   case Instruction::AShr: return bitc::BINOP_ASHR;
 103   case Instruction::And:  return bitc::BINOP_AND;
 104   case Instruction::Or:   return bitc::BINOP_OR;
 105   case Instruction::Xor:  return bitc::BINOP_XOR;
 106   }
 107 }
 108
 109 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 110   switch (Op) {
 111   default: llvm_unreachable("Unknown RMW operation!");
 112   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 113   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 114   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 115   case AtomicRMWInst::And: return bitc::RMW_AND;
 116   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 117   case AtomicRMWInst::Or: return bitc::RMW_OR;
 118   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 119   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 120   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 121   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 122   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 123   }
 124 }
 125
 126 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 127   switch (Ordering) {
 128   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 129   case Unordered: return bitc::ORDERING_UNORDERED;
 130   case Monotonic: return bitc::ORDERING_MONOTONIC;
 131   case Acquire: return bitc::ORDERING_ACQUIRE;
 132   case Release: return bitc::ORDERING_RELEASE;
 133   case AcquireRelease: return bitc::ORDERING_ACQREL;
 134   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 135   }
 136   llvm_unreachable("Invalid ordering");
 137 }
 138
 139 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 140   switch (SynchScope) {
 141   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 142   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 143   }
 144   llvm_unreachable("Invalid synch scope");
 145 }
 146
 147 static void WriteStringRecord(unsigned Code, StringRef Str,
 148                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 149   SmallVector<unsigned, 64> Vals;
 150
 151   // Code: [strchar x N]
 152   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 153     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 154       AbbrevToUse = 0;
 155     Vals.push_back(Str[i]);
 156   }
 157
 158   // Emit the finished record.
 159   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 160 }
 161
 162 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
 163   switch (Kind) {
 164   case Attribute::Alignment:
 165     return bitc::ATTR_KIND_ALIGNMENT;
 166   case Attribute::AlwaysInline:
 167     return bitc::ATTR_KIND_ALWAYS_INLINE;
 168   case Attribute::Builtin:
 169     return bitc::ATTR_KIND_BUILTIN;
 170   case Attribute::ByVal:
 171     return bitc::ATTR_KIND_BY_VAL;
 172   case Attribute::Cold:
 173     return bitc::ATTR_KIND_COLD;
 174   case Attribute::InlineHint:
 175     return bitc::ATTR_KIND_INLINE_HINT;
 176   case Attribute::InReg:
 177     return bitc::ATTR_KIND_IN_REG;
 178   case Attribute::MinSize:
 179     return bitc::ATTR_KIND_MIN_SIZE;
 180   case Attribute::Naked:
 181     return bitc::ATTR_KIND_NAKED;
 182   case Attribute::Nest:
 183     return bitc::ATTR_KIND_NEST;
 184   case Attribute::NoAlias:
 185     return bitc::ATTR_KIND_NO_ALIAS;
 186   case Attribute::NoBuiltin:
 187     return bitc::ATTR_KIND_NO_BUILTIN;
 188   case Attribute::NoCapture:
 189     return bitc::ATTR_KIND_NO_CAPTURE;
 190   case Attribute::NoDuplicate:
 191     return bitc::ATTR_KIND_NO_DUPLICATE;
 192   case Attribute::NoImplicitFloat:
 193     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
 194   case Attribute::NoInline:
 195     return bitc::ATTR_KIND_NO_INLINE;
 196   case Attribute::NonLazyBind:
 197     return bitc::ATTR_KIND_NON_LAZY_BIND;
 198   case Attribute::NoRedZone:
 199     return bitc::ATTR_KIND_NO_RED_ZONE;
 200   case Attribute::NoReturn:
 201     return bitc::ATTR_KIND_NO_RETURN;
 202   case Attribute::NoUnwind:
 203     return bitc::ATTR_KIND_NO_UNWIND;
 204   case Attribute::OptimizeForSize:
 205     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
 206   case Attribute::OptimizeNone:
 207     return bitc::ATTR_KIND_OPTIMIZE_NONE;
 208   case Attribute::ReadNone:
 209     return bitc::ATTR_KIND_READ_NONE;
 210   case Attribute::ReadOnly:
 211     return bitc::ATTR_KIND_READ_ONLY;
 212   case Attribute::Returned:
 213     return bitc::ATTR_KIND_RETURNED;
 214   case Attribute::ReturnsTwice:
 215     return bitc::ATTR_KIND_RETURNS_TWICE;
 216   case Attribute::SExt:
 217     return bitc::ATTR_KIND_S_EXT;
 218   case Attribute::StackAlignment:
 219     return bitc::ATTR_KIND_STACK_ALIGNMENT;
 220   case Attribute::StackProtect:
 221     return bitc::ATTR_KIND_STACK_PROTECT;
 222   case Attribute::StackProtectReq:
 223     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
 224   case Attribute::StackProtectStrong:
 225     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
 226   case Attribute::StructRet:
 227     return bitc::ATTR_KIND_STRUCT_RET;
 228   case Attribute::SanitizeAddress:
 229     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
 230   case Attribute::SanitizeThread:
 231     return bitc::ATTR_KIND_SANITIZE_THREAD;
 232   case Attribute::SanitizeMemory:
 233     return bitc::ATTR_KIND_SANITIZE_MEMORY;
 234   case Attribute::UWTable:
 235     return bitc::ATTR_KIND_UW_TABLE;
 236   case Attribute::ZExt:
 237     return bitc::ATTR_KIND_Z_EXT;
 238   case Attribute::EndAttrKinds:
 239     llvm_unreachable("Can not encode end-attribute kinds marker.");
 240   case Attribute::None:
 241     llvm_unreachable("Can not encode none-attribute.");
 242   }
 243
 244   llvm_unreachable("Trying to encode unknown attribute");
 245 }
 246
 247 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
 248                                      BitstreamWriter &Stream) {
 249   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
 250   if (AttrGrps.empty()) return;
 251
 252   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 253
 254   SmallVector<uint64_t, 64> Record;
 255   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
 256     AttributeSet AS = AttrGrps[i];
 257     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
 258       AttributeSet A = AS.getSlotAttributes(i);
 259
 260       Record.push_back(VE.getAttributeGroupID(A));
 261       Record.push_back(AS.getSlotIndex(i));
 262
 263       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
 264            I != E; ++I) {
 265         Attribute Attr = *I;
 266         if (Attr.isEnumAttribute()) {
 267           Record.push_back(0);
 268           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 269         } else if (Attr.isAlignAttribute()) {
 270           Record.push_back(1);
 271           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 272           Record.push_back(Attr.getValueAsInt());
 273         } else {
 274           StringRef Kind = Attr.getKindAsString();
 275           StringRef Val = Attr.getValueAsString();
 276
 277           Record.push_back(Val.empty() ? 3 : 4);
 278           Record.append(Kind.begin(), Kind.end());
 279           Record.push_back(0);
 280           if (!Val.empty()) {
 281             Record.append(Val.begin(), Val.end());
 282             Record.push_back(0);
 283           }
 284         }
 285       }
 286
 287       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
 288       Record.clear();
 289     }
 290   }
 291
 292   Stream.ExitBlock();
 293 }
 294
 295 static void WriteAttributeTable(const ValueEnumerator &VE,
 296                                 BitstreamWriter &Stream) {
 297   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 298   if (Attrs.empty()) return;
 299
 300   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 301
 302   SmallVector<uint64_t, 64> Record;
 303   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 304     const AttributeSet &A = Attrs[i];
 305     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
 306       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
 307
 308     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 309     Record.clear();
 310   }
 311
 312   Stream.ExitBlock();
 313 }
 314
 315 /// WriteTypeTable - Write out the type table for a module.
 316 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 317   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 318
 319   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 320   SmallVector<uint64_t, 64> TypeVals;
 321
 322   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 323
 324   // Abbrev for TYPE_CODE_POINTER.
 325   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 326   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 327   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 328   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 329   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 330
 331   // Abbrev for TYPE_CODE_FUNCTION.
 332   Abbv = new BitCodeAbbrev();
 333   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 334   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 335   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 336   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 337
 338   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 339
 340   // Abbrev for TYPE_CODE_STRUCT_ANON.
 341   Abbv = new BitCodeAbbrev();
 342   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 343   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 344   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 345   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 346
 347   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 348
 349   // Abbrev for TYPE_CODE_STRUCT_NAME.
 350   Abbv = new BitCodeAbbrev();
 351   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 352   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 353   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 354   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 355
 356   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 357   Abbv = new BitCodeAbbrev();
 358   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 359   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 360   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 361   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 362
 363   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 364
 365   // Abbrev for TYPE_CODE_ARRAY.
 366   Abbv = new BitCodeAbbrev();
 367   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 368   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 369   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 370
 371   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 372
 373   // Emit an entry count so the reader can reserve space.
 374   TypeVals.push_back(TypeList.size());
 375   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 376   TypeVals.clear();
 377
 378   // Loop over all of the types, emitting each in turn.
 379   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 380     Type *T = TypeList[i];
 381     int AbbrevToUse = 0;
 382     unsigned Code = 0;
 383
 384     switch (T->getTypeID()) {
 385     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 386     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 387     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 388     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 389     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 390     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 391     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 392     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 393     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 394     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 395     case Type::IntegerTyID:
 396       // INTEGER: [width]
 397       Code = bitc::TYPE_CODE_INTEGER;
 398       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 399       break;
 400     case Type::PointerTyID: {
 401       PointerType *PTy = cast<PointerType>(T);
 402       // POINTER: [pointee type, address space]
 403       Code = bitc::TYPE_CODE_POINTER;
 404       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 405       unsigned AddressSpace = PTy->getAddressSpace();
 406       TypeVals.push_back(AddressSpace);
 407       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 408       break;
 409     }
 410     case Type::FunctionTyID: {
 411       FunctionType *FT = cast<FunctionType>(T);
 412       // FUNCTION: [isvararg, retty, paramty x N]
 413       Code = bitc::TYPE_CODE_FUNCTION;
 414       TypeVals.push_back(FT->isVarArg());
 415       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 416       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 417         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 418       AbbrevToUse = FunctionAbbrev;
 419       break;
 420     }
 421     case Type::StructTyID: {
 422       StructType *ST = cast<StructType>(T);
 423       // STRUCT: [ispacked, eltty x N]
 424       TypeVals.push_back(ST->isPacked());
 425       // Output all of the element types.
 426       for (StructType::element_iterator I = ST->element_begin(),
 427            E = ST->element_end(); I != E; ++I)
 428         TypeVals.push_back(VE.getTypeID(*I));
 429
 430       if (ST->isLiteral()) {
 431         Code = bitc::TYPE_CODE_STRUCT_ANON;
 432         AbbrevToUse = StructAnonAbbrev;
 433       } else {
 434         if (ST->isOpaque()) {
 435           Code = bitc::TYPE_CODE_OPAQUE;
 436         } else {
 437           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 438           AbbrevToUse = StructNamedAbbrev;
 439         }
 440
 441         // Emit the name if it is present.
 442         if (!ST->getName().empty())
 443           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 444                             StructNameAbbrev, Stream);
 445       }
 446       break;
 447     }
 448     case Type::ArrayTyID: {
 449       ArrayType *AT = cast<ArrayType>(T);
 450       // ARRAY: [numelts, eltty]
 451       Code = bitc::TYPE_CODE_ARRAY;
 452       TypeVals.push_back(AT->getNumElements());
 453       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 454       AbbrevToUse = ArrayAbbrev;
 455       break;
 456     }
 457     case Type::VectorTyID: {
 458       VectorType *VT = cast<VectorType>(T);
 459       // VECTOR [numelts, eltty]
 460       Code = bitc::TYPE_CODE_VECTOR;
 461       TypeVals.push_back(VT->getNumElements());
 462       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 463       break;
 464     }
 465     }
 466
 467     // Emit the finished record.
 468     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 469     TypeVals.clear();
 470   }
 471
 472   Stream.ExitBlock();
 473 }
 474
 475 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 476   switch (GV->getLinkage()) {
 477   case GlobalValue::ExternalLinkage:                 return 0;
 478   case GlobalValue::WeakAnyLinkage:                  return 1;
 479   case GlobalValue::AppendingLinkage:                return 2;
 480   case GlobalValue::InternalLinkage:                 return 3;
 481   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 482   case GlobalValue::DLLImportLinkage:                return 5;
 483   case GlobalValue::DLLExportLinkage:                return 6;
 484   case GlobalValue::ExternalWeakLinkage:             return 7;
 485   case GlobalValue::CommonLinkage:                   return 8;
 486   case GlobalValue::PrivateLinkage:                  return 9;
 487   case GlobalValue::WeakODRLinkage:                  return 10;
 488   case GlobalValue::LinkOnceODRLinkage:              return 11;
 489   case GlobalValue::AvailableExternallyLinkage:      return 12;
 490   case GlobalValue::LinkerPrivateLinkage:            return 13;
 491   case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
 492   }
 493   llvm_unreachable("Invalid linkage");
 494 }
 495
 496 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 497   switch (GV->getVisibility()) {
 498   case GlobalValue::DefaultVisibility:   return 0;
 499   case GlobalValue::HiddenVisibility:    return 1;
 500   case GlobalValue::ProtectedVisibility: return 2;
 501   }
 502   llvm_unreachable("Invalid visibility");
 503 }
 504
 505 static unsigned getEncodedThreadLocalMode(const GlobalVariable *GV) {
 506   switch (GV->getThreadLocalMode()) {
 507     case GlobalVariable::NotThreadLocal:         return 0;
 508     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 509     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 510     case GlobalVariable::InitialExecTLSModel:    return 3;
 511     case GlobalVariable::LocalExecTLSModel:      return 4;
 512   }
 513   llvm_unreachable("Invalid TLS model");
 514 }
 515
 516 // Emit top-level description of module, including target triple, inline asm,
 517 // descriptors for global variables, and function prototype info.
 518 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 519                             BitstreamWriter &Stream) {
 520   // Emit various pieces of data attached to a module.
 521   if (!M->getTargetTriple().empty())
 522     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 523                       0/*TODO*/, Stream);
 524   if (!M->getDataLayout().empty())
 525     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 526                       0/*TODO*/, Stream);
 527   if (!M->getModuleInlineAsm().empty())
 528     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 529                       0/*TODO*/, Stream);
 530
 531   // Emit information about sections and GC, computing how many there are. Also
 532   // compute the maximum alignment value.
 533   std::map<std::string, unsigned> SectionMap;
 534   std::map<std::string, unsigned> GCMap;
 535   unsigned MaxAlignment = 0;
 536   unsigned MaxGlobalType = 0;
 537   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 538        GV != E; ++GV) {
 539     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 540     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 541     if (GV->hasSection()) {
 542       // Give section names unique ID's.
 543       unsigned &Entry = SectionMap[GV->getSection()];
 544       if (!Entry) {
 545         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 546                           0/*TODO*/, Stream);
 547         Entry = SectionMap.size();
 548       }
 549     }
 550   }
 551   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 552     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 553     if (F->hasSection()) {
 554       // Give section names unique ID's.
 555       unsigned &Entry = SectionMap[F->getSection()];
 556       if (!Entry) {
 557         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 558                           0/*TODO*/, Stream);
 559         Entry = SectionMap.size();
 560       }
 561     }
 562     if (F->hasGC()) {
 563       // Same for GC names.
 564       unsigned &Entry = GCMap[F->getGC()];
 565       if (!Entry) {
 566         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 567                           0/*TODO*/, Stream);
 568         Entry = GCMap.size();
 569       }
 570     }
 571   }
 572
 573   // Emit abbrev for globals, now that we know # sections and max alignment.
 574   unsigned SimpleGVarAbbrev = 0;
 575   if (!M->global_empty()) {
 576     // Add an abbrev for common globals with no visibility or thread localness.
 577     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 578     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 579     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 580                               Log2_32_Ceil(MaxGlobalType+1)));
 581     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 582     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 583     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 584     if (MaxAlignment == 0)                                      // Alignment.
 585       Abbv->Add(BitCodeAbbrevOp(0));
 586     else {
 587       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 588       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 589                                Log2_32_Ceil(MaxEncAlignment+1)));
 590     }
 591     if (SectionMap.empty())                                    // Section.
 592       Abbv->Add(BitCodeAbbrevOp(0));
 593     else
 594       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 595                                Log2_32_Ceil(SectionMap.size()+1)));
 596     // Don't bother emitting vis + thread local.
 597     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 598   }
 599
 600   // Emit the global variable information.
 601   SmallVector<unsigned, 64> Vals;
 602   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 603        GV != E; ++GV) {
 604     unsigned AbbrevToUse = 0;
 605
 606     // GLOBALVAR: [type, isconst, initid,
 607     //             linkage, alignment, section, visibility, threadlocal,
 608     //             unnamed_addr, externally_initialized]
 609     Vals.push_back(VE.getTypeID(GV->getType()));
 610     Vals.push_back(GV->isConstant());
 611     Vals.push_back(GV->isDeclaration() ? 0 :
 612                    (VE.getValueID(GV->getInitializer()) + 1));
 613     Vals.push_back(getEncodedLinkage(GV));
 614     Vals.push_back(Log2_32(GV->getAlignment())+1);
 615     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 616     if (GV->isThreadLocal() ||
 617         GV->getVisibility() != GlobalValue::DefaultVisibility ||
 618         GV->hasUnnamedAddr() || GV->isExternallyInitialized()) {
 619       Vals.push_back(getEncodedVisibility(GV));
 620       Vals.push_back(getEncodedThreadLocalMode(GV));
 621       Vals.push_back(GV->hasUnnamedAddr());
 622       Vals.push_back(GV->isExternallyInitialized());
 623     } else {
 624       AbbrevToUse = SimpleGVarAbbrev;
 625     }
 626
 627     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 628     Vals.clear();
 629   }
 630
 631   // Emit the function proto information.
 632   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 633     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 634     //             section, visibility, gc, unnamed_addr, prefix]
 635     Vals.push_back(VE.getTypeID(F->getType()));
 636     Vals.push_back(F->getCallingConv());
 637     Vals.push_back(F->isDeclaration());
 638     Vals.push_back(getEncodedLinkage(F));
 639     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 640     Vals.push_back(Log2_32(F->getAlignment())+1);
 641     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 642     Vals.push_back(getEncodedVisibility(F));
 643     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 644     Vals.push_back(F->hasUnnamedAddr());
 645     Vals.push_back(F->hasPrefixData() ? (VE.getValueID(F->getPrefixData()) + 1)
 646                                       : 0);
 647
 648     unsigned AbbrevToUse = 0;
 649     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 650     Vals.clear();
 651   }
 652
 653   // Emit the alias information.
 654   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 655        AI != E; ++AI) {
 656     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 657     Vals.push_back(VE.getTypeID(AI->getType()));
 658     Vals.push_back(VE.getValueID(AI->getAliasee()));
 659     Vals.push_back(getEncodedLinkage(AI));
 660     Vals.push_back(getEncodedVisibility(AI));
 661     unsigned AbbrevToUse = 0;
 662     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 663     Vals.clear();
 664   }
 665 }
 666
 667 static uint64_t GetOptimizationFlags(const Value *V) {
 668   uint64_t Flags = 0;
 669
 670   if (const OverflowingBinaryOperator *OBO =
 671         dyn_cast<OverflowingBinaryOperator>(V)) {
 672     if (OBO->hasNoSignedWrap())
 673       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 674     if (OBO->hasNoUnsignedWrap())
 675       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 676   } else if (const PossiblyExactOperator *PEO =
 677                dyn_cast<PossiblyExactOperator>(V)) {
 678     if (PEO->isExact())
 679       Flags |= 1 << bitc::PEO_EXACT;
 680   } else if (const FPMathOperator *FPMO =
 681              dyn_cast<const FPMathOperator>(V)) {
 682     if (FPMO->hasUnsafeAlgebra())
 683       Flags |= FastMathFlags::UnsafeAlgebra;
 684     if (FPMO->hasNoNaNs())
 685       Flags |= FastMathFlags::NoNaNs;
 686     if (FPMO->hasNoInfs())
 687       Flags |= FastMathFlags::NoInfs;
 688     if (FPMO->hasNoSignedZeros())
 689       Flags |= FastMathFlags::NoSignedZeros;
 690     if (FPMO->hasAllowReciprocal())
 691       Flags |= FastMathFlags::AllowReciprocal;
 692   }
 693
 694   return Flags;
 695 }
 696
 697 static void WriteMDNode(const MDNode *N,
 698                         const ValueEnumerator &VE,
 699                         BitstreamWriter &Stream,
 700                         SmallVectorImpl<uint64_t> &Record) {
 701   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 702     if (N->getOperand(i)) {
 703       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 704       Record.push_back(VE.getValueID(N->getOperand(i)));
 705     } else {
 706       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 707       Record.push_back(0);
 708     }
 709   }
 710   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 711                                            bitc::METADATA_NODE;
 712   Stream.EmitRecord(MDCode, Record, 0);
 713   Record.clear();
 714 }
 715
 716 static void WriteModuleMetadata(const Module *M,
 717                                 const ValueEnumerator &VE,
 718                                 BitstreamWriter &Stream) {
 719   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 720   bool StartedMetadataBlock = false;
 721   unsigned MDSAbbrev = 0;
 722   SmallVector<uint64_t, 64> Record;
 723   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 724
 725     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 726       if (!N->isFunctionLocal() || !N->getFunction()) {
 727         if (!StartedMetadataBlock) {
 728           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 729           StartedMetadataBlock = true;
 730         }
 731         WriteMDNode(N, VE, Stream, Record);
 732       }
 733     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 734       if (!StartedMetadataBlock)  {
 735         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 736
 737         // Abbrev for METADATA_STRING.
 738         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 739         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 740         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 741         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 742         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 743         StartedMetadataBlock = true;
 744       }
 745
 746       // Code: [strchar x N]
 747       Record.append(MDS->begin(), MDS->end());
 748
 749       // Emit the finished record.
 750       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 751       Record.clear();
 752     }
 753   }
 754
 755   // Write named metadata.
 756   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 757        E = M->named_metadata_end(); I != E; ++I) {
 758     const NamedMDNode *NMD = I;
 759     if (!StartedMetadataBlock)  {
 760       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 761       StartedMetadataBlock = true;
 762     }
 763
 764     // Write name.
 765     StringRef Str = NMD->getName();
 766     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 767       Record.push_back(Str[i]);
 768     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 769     Record.clear();
 770
 771     // Write named metadata operands.
 772     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 773       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 774     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 775     Record.clear();
 776   }
 777
 778   if (StartedMetadataBlock)
 779     Stream.ExitBlock();
 780 }
 781
 782 static void WriteFunctionLocalMetadata(const Function &F,
 783                                        const ValueEnumerator &VE,
 784                                        BitstreamWriter &Stream) {
 785   bool StartedMetadataBlock = false;
 786   SmallVector<uint64_t, 64> Record;
 787   const SmallVectorImpl<const MDNode *> &Vals = VE.getFunctionLocalMDValues();
 788   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 789     if (const MDNode *N = Vals[i])
 790       if (N->isFunctionLocal() && N->getFunction() == &F) {
 791         if (!StartedMetadataBlock) {
 792           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 793           StartedMetadataBlock = true;
 794         }
 795         WriteMDNode(N, VE, Stream, Record);
 796       }
 797
 798   if (StartedMetadataBlock)
 799     Stream.ExitBlock();
 800 }
 801
 802 static void WriteMetadataAttachment(const Function &F,
 803                                     const ValueEnumerator &VE,
 804                                     BitstreamWriter &Stream) {
 805   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 806
 807   SmallVector<uint64_t, 64> Record;
 808
 809   // Write metadata attachments
 810   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 811   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 812
 813   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 814     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 815          I != E; ++I) {
 816       MDs.clear();
 817       I->getAllMetadataOtherThanDebugLoc(MDs);
 818
 819       // If no metadata, ignore instruction.
 820       if (MDs.empty()) continue;
 821
 822       Record.push_back(VE.getInstructionID(I));
 823
 824       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 825         Record.push_back(MDs[i].first);
 826         Record.push_back(VE.getValueID(MDs[i].second));
 827       }
 828       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 829       Record.clear();
 830     }
 831
 832   Stream.ExitBlock();
 833 }
 834
 835 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 836   SmallVector<uint64_t, 64> Record;
 837
 838   // Write metadata kinds
 839   // METADATA_KIND - [n x [id, name]]
 840   SmallVector<StringRef, 8> Names;
 841   M->getMDKindNames(Names);
 842
 843   if (Names.empty()) return;
 844
 845   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 846
 847   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 848     Record.push_back(MDKindID);
 849     StringRef KName = Names[MDKindID];
 850     Record.append(KName.begin(), KName.end());
 851
 852     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 853     Record.clear();
 854   }
 855
 856   Stream.ExitBlock();
 857 }
 858
 859 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 860   if ((int64_t)V >= 0)
 861     Vals.push_back(V << 1);
 862   else
 863     Vals.push_back((-V << 1) | 1);
 864 }
 865
 866 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 867                            const ValueEnumerator &VE,
 868                            BitstreamWriter &Stream, bool isGlobal) {
 869   if (FirstVal == LastVal) return;
 870
 871   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 872
 873   unsigned AggregateAbbrev = 0;
 874   unsigned String8Abbrev = 0;
 875   unsigned CString7Abbrev = 0;
 876   unsigned CString6Abbrev = 0;
 877   // If this is a constant pool for the module, emit module-specific abbrevs.
 878   if (isGlobal) {
 879     // Abbrev for CST_CODE_AGGREGATE.
 880     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 881     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 882     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 883     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 884     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 885
 886     // Abbrev for CST_CODE_STRING.
 887     Abbv = new BitCodeAbbrev();
 888     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 889     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 890     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 891     String8Abbrev = Stream.EmitAbbrev(Abbv);
 892     // Abbrev for CST_CODE_CSTRING.
 893     Abbv = new BitCodeAbbrev();
 894     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 895     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 896     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 897     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 898     // Abbrev for CST_CODE_CSTRING.
 899     Abbv = new BitCodeAbbrev();
 900     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 901     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 902     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 903     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 904   }
 905
 906   SmallVector<uint64_t, 64> Record;
 907
 908   const ValueEnumerator::ValueList &Vals = VE.getValues();
 909   Type *LastTy = 0;
 910   for (unsigned i = FirstVal; i != LastVal; ++i) {
 911     const Value *V = Vals[i].first;
 912     // If we need to switch types, do so now.
 913     if (V->getType() != LastTy) {
 914       LastTy = V->getType();
 915       Record.push_back(VE.getTypeID(LastTy));
 916       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 917                         CONSTANTS_SETTYPE_ABBREV);
 918       Record.clear();
 919     }
 920
 921     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 922       Record.push_back(unsigned(IA->hasSideEffects()) |
 923                        unsigned(IA->isAlignStack()) << 1 |
 924                        unsigned(IA->getDialect()&1) << 2);
 925
 926       // Add the asm string.
 927       const std::string &AsmStr = IA->getAsmString();
 928       Record.push_back(AsmStr.size());
 929       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 930         Record.push_back(AsmStr[i]);
 931
 932       // Add the constraint string.
 933       const std::string &ConstraintStr = IA->getConstraintString();
 934       Record.push_back(ConstraintStr.size());
 935       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 936         Record.push_back(ConstraintStr[i]);
 937       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 938       Record.clear();
 939       continue;
 940     }
 941     const Constant *C = cast<Constant>(V);
 942     unsigned Code = -1U;
 943     unsigned AbbrevToUse = 0;
 944     if (C->isNullValue()) {
 945       Code = bitc::CST_CODE_NULL;
 946     } else if (isa<UndefValue>(C)) {
 947       Code = bitc::CST_CODE_UNDEF;
 948     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 949       if (IV->getBitWidth() <= 64) {
 950         uint64_t V = IV->getSExtValue();
 951         emitSignedInt64(Record, V);
 952         Code = bitc::CST_CODE_INTEGER;
 953         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 954       } else {                             // Wide integers, > 64 bits in size.
 955         // We have an arbitrary precision integer value to write whose
 956         // bit width is > 64. However, in canonical unsigned integer
 957         // format it is likely that the high bits are going to be zero.
 958         // So, we only write the number of active words.
 959         unsigned NWords = IV->getValue().getActiveWords();
 960         const uint64_t *RawWords = IV->getValue().getRawData();
 961         for (unsigned i = 0; i != NWords; ++i) {
 962           emitSignedInt64(Record, RawWords[i]);
 963         }
 964         Code = bitc::CST_CODE_WIDE_INTEGER;
 965       }
 966     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 967       Code = bitc::CST_CODE_FLOAT;
 968       Type *Ty = CFP->getType();
 969       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 970         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 971       } else if (Ty->isX86_FP80Ty()) {
 972         // api needed to prevent premature destruction
 973         // bits are not in the same order as a normal i80 APInt, compensate.
 974         APInt api = CFP->getValueAPF().bitcastToAPInt();
 975         const uint64_t *p = api.getRawData();
 976         Record.push_back((p[1] << 48) | (p[0] >> 16));
 977         Record.push_back(p[0] & 0xffffLL);
 978       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 979         APInt api = CFP->getValueAPF().bitcastToAPInt();
 980         const uint64_t *p = api.getRawData();
 981         Record.push_back(p[0]);
 982         Record.push_back(p[1]);
 983       } else {
 984         assert (0 && "Unknown FP type!");
 985       }
 986     } else if (isa<ConstantDataSequential>(C) &&
 987                cast<ConstantDataSequential>(C)->isString()) {
 988       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 989       // Emit constant strings specially.
 990       unsigned NumElts = Str->getNumElements();
 991       // If this is a null-terminated string, use the denser CSTRING encoding.
 992       if (Str->isCString()) {
 993         Code = bitc::CST_CODE_CSTRING;
 994         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 995       } else {
 996         Code = bitc::CST_CODE_STRING;
 997         AbbrevToUse = String8Abbrev;
 998       }
 999       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1000       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1001       for (unsigned i = 0; i != NumElts; ++i) {
1002         unsigned char V = Str->getElementAsInteger(i);
1003         Record.push_back(V);
1004         isCStr7 &= (V & 128) == 0;
1005         if (isCStrChar6)
1006           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1007       }
1008
1009       if (isCStrChar6)
1010         AbbrevToUse = CString6Abbrev;
1011       else if (isCStr7)
1012         AbbrevToUse = CString7Abbrev;
1013     } else if (const ConstantDataSequential *CDS =
1014                   dyn_cast<ConstantDataSequential>(C)) {
1015       Code = bitc::CST_CODE_DATA;
1016       Type *EltTy = CDS->getType()->getElementType();
1017       if (isa<IntegerType>(EltTy)) {
1018         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1019           Record.push_back(CDS->getElementAsInteger(i));
1020       } else if (EltTy->isFloatTy()) {
1021         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1022           union { float F; uint32_t I; };
1023           F = CDS->getElementAsFloat(i);
1024           Record.push_back(I);
1025         }
1026       } else {
1027         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1028         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1029           union { double F; uint64_t I; };
1030           F = CDS->getElementAsDouble(i);
1031           Record.push_back(I);
1032         }
1033       }
1034     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1035                isa<ConstantVector>(C)) {
1036       Code = bitc::CST_CODE_AGGREGATE;
1037       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1038         Record.push_back(VE.getValueID(C->getOperand(i)));
1039       AbbrevToUse = AggregateAbbrev;
1040     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1041       switch (CE->getOpcode()) {
1042       default:
1043         if (Instruction::isCast(CE->getOpcode())) {
1044           Code = bitc::CST_CODE_CE_CAST;
1045           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1046           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1047           Record.push_back(VE.getValueID(C->getOperand(0)));
1048           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1049         } else {
1050           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1051           Code = bitc::CST_CODE_CE_BINOP;
1052           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1053           Record.push_back(VE.getValueID(C->getOperand(0)));
1054           Record.push_back(VE.getValueID(C->getOperand(1)));
1055           uint64_t Flags = GetOptimizationFlags(CE);
1056           if (Flags != 0)
1057             Record.push_back(Flags);
1058         }
1059         break;
1060       case Instruction::GetElementPtr:
1061         Code = bitc::CST_CODE_CE_GEP;
1062         if (cast<GEPOperator>(C)->isInBounds())
1063           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1064         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1065           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1066           Record.push_back(VE.getValueID(C->getOperand(i)));
1067         }
1068         break;
1069       case Instruction::Select:
1070         Code = bitc::CST_CODE_CE_SELECT;
1071         Record.push_back(VE.getValueID(C->getOperand(0)));
1072         Record.push_back(VE.getValueID(C->getOperand(1)));
1073         Record.push_back(VE.getValueID(C->getOperand(2)));
1074         break;
1075       case Instruction::ExtractElement:
1076         Code = bitc::CST_CODE_CE_EXTRACTELT;
1077         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1078         Record.push_back(VE.getValueID(C->getOperand(0)));
1079         Record.push_back(VE.getValueID(C->getOperand(1)));
1080         break;
1081       case Instruction::InsertElement:
1082         Code = bitc::CST_CODE_CE_INSERTELT;
1083         Record.push_back(VE.getValueID(C->getOperand(0)));
1084         Record.push_back(VE.getValueID(C->getOperand(1)));
1085         Record.push_back(VE.getValueID(C->getOperand(2)));
1086         break;
1087       case Instruction::ShuffleVector:
1088         // If the return type and argument types are the same, this is a
1089         // standard shufflevector instruction.  If the types are different,
1090         // then the shuffle is widening or truncating the input vectors, and
1091         // the argument type must also be encoded.
1092         if (C->getType() == C->getOperand(0)->getType()) {
1093           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1094         } else {
1095           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1096           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1097         }
1098         Record.push_back(VE.getValueID(C->getOperand(0)));
1099         Record.push_back(VE.getValueID(C->getOperand(1)));
1100         Record.push_back(VE.getValueID(C->getOperand(2)));
1101         break;
1102       case Instruction::ICmp:
1103       case Instruction::FCmp:
1104         Code = bitc::CST_CODE_CE_CMP;
1105         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1106         Record.push_back(VE.getValueID(C->getOperand(0)));
1107         Record.push_back(VE.getValueID(C->getOperand(1)));
1108         Record.push_back(CE->getPredicate());
1109         break;
1110       }
1111     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1112       Code = bitc::CST_CODE_BLOCKADDRESS;
1113       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1114       Record.push_back(VE.getValueID(BA->getFunction()));
1115       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1116     } else {
1117 #ifndef NDEBUG
1118       C->dump();
1119 #endif
1120       llvm_unreachable("Unknown constant!");
1121     }
1122     Stream.EmitRecord(Code, Record, AbbrevToUse);
1123     Record.clear();
1124   }
1125
1126   Stream.ExitBlock();
1127 }
1128
1129 static void WriteModuleConstants(const ValueEnumerator &VE,
1130                                  BitstreamWriter &Stream) {
1131   const ValueEnumerator::ValueList &Vals = VE.getValues();
1132
1133   // Find the first constant to emit, which is the first non-globalvalue value.
1134   // We know globalvalues have been emitted by WriteModuleInfo.
1135   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1136     if (!isa<GlobalValue>(Vals[i].first)) {
1137       WriteConstants(i, Vals.size(), VE, Stream, true);
1138       return;
1139     }
1140   }
1141 }
1142
1143 /// PushValueAndType - The file has to encode both the value and type id for
1144 /// many values, because we need to know what type to create for forward
1145 /// references.  However, most operands are not forward references, so this type
1146 /// field is not needed.
1147 ///
1148 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1149 /// instruction ID, then it is a forward reference, and it also includes the
1150 /// type ID.  The value ID that is written is encoded relative to the InstID.
1151 static bool PushValueAndType(const Value *V, unsigned InstID,
1152                              SmallVectorImpl<unsigned> &Vals,
1153                              ValueEnumerator &VE) {
1154   unsigned ValID = VE.getValueID(V);
1155   // Make encoding relative to the InstID.
1156   Vals.push_back(InstID - ValID);
1157   if (ValID >= InstID) {
1158     Vals.push_back(VE.getTypeID(V->getType()));
1159     return true;
1160   }
1161   return false;
1162 }
1163
1164 /// pushValue - Like PushValueAndType, but where the type of the value is
1165 /// omitted (perhaps it was already encoded in an earlier operand).
1166 static void pushValue(const Value *V, unsigned InstID,
1167                       SmallVectorImpl<unsigned> &Vals,
1168                       ValueEnumerator &VE) {
1169   unsigned ValID = VE.getValueID(V);
1170   Vals.push_back(InstID - ValID);
1171 }
1172
1173 static void pushValueSigned(const Value *V, unsigned InstID,
1174                             SmallVectorImpl<uint64_t> &Vals,
1175                             ValueEnumerator &VE) {
1176   unsigned ValID = VE.getValueID(V);
1177   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1178   emitSignedInt64(Vals, diff);
1179 }
1180
1181 /// WriteInstruction - Emit an instruction to the specified stream.
1182 static void WriteInstruction(const Instruction &I, unsigned InstID,
1183                              ValueEnumerator &VE, BitstreamWriter &Stream,
1184                              SmallVectorImpl<unsigned> &Vals) {
1185   unsigned Code = 0;
1186   unsigned AbbrevToUse = 0;
1187   VE.setInstructionID(&I);
1188   switch (I.getOpcode()) {
1189   default:
1190     if (Instruction::isCast(I.getOpcode())) {
1191       Code = bitc::FUNC_CODE_INST_CAST;
1192       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1193         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1194       Vals.push_back(VE.getTypeID(I.getType()));
1195       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1196     } else {
1197       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1198       Code = bitc::FUNC_CODE_INST_BINOP;
1199       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1200         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1201       pushValue(I.getOperand(1), InstID, Vals, VE);
1202       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1203       uint64_t Flags = GetOptimizationFlags(&I);
1204       if (Flags != 0) {
1205         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1206           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1207         Vals.push_back(Flags);
1208       }
1209     }
1210     break;
1211
1212   case Instruction::GetElementPtr:
1213     Code = bitc::FUNC_CODE_INST_GEP;
1214     if (cast<GEPOperator>(&I)->isInBounds())
1215       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1216     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1217       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1218     break;
1219   case Instruction::ExtractValue: {
1220     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1221     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1222     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1223     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1224       Vals.push_back(*i);
1225     break;
1226   }
1227   case Instruction::InsertValue: {
1228     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1229     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1230     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1231     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1232     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1233       Vals.push_back(*i);
1234     break;
1235   }
1236   case Instruction::Select:
1237     Code = bitc::FUNC_CODE_INST_VSELECT;
1238     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1239     pushValue(I.getOperand(2), InstID, Vals, VE);
1240     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1241     break;
1242   case Instruction::ExtractElement:
1243     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1244     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1245     pushValue(I.getOperand(1), InstID, Vals, VE);
1246     break;
1247   case Instruction::InsertElement:
1248     Code = bitc::FUNC_CODE_INST_INSERTELT;
1249     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1250     pushValue(I.getOperand(1), InstID, Vals, VE);
1251     pushValue(I.getOperand(2), InstID, Vals, VE);
1252     break;
1253   case Instruction::ShuffleVector:
1254     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1255     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1256     pushValue(I.getOperand(1), InstID, Vals, VE);
1257     pushValue(I.getOperand(2), InstID, Vals, VE);
1258     break;
1259   case Instruction::ICmp:
1260   case Instruction::FCmp:
1261     // compare returning Int1Ty or vector of Int1Ty
1262     Code = bitc::FUNC_CODE_INST_CMP2;
1263     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1264     pushValue(I.getOperand(1), InstID, Vals, VE);
1265     Vals.push_back(cast<CmpInst>(I).getPredicate());
1266     break;
1267
1268   case Instruction::Ret:
1269     {
1270       Code = bitc::FUNC_CODE_INST_RET;
1271       unsigned NumOperands = I.getNumOperands();
1272       if (NumOperands == 0)
1273         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1274       else if (NumOperands == 1) {
1275         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1276           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1277       } else {
1278         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1279           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1280       }
1281     }
1282     break;
1283   case Instruction::Br:
1284     {
1285       Code = bitc::FUNC_CODE_INST_BR;
1286       const BranchInst &II = cast<BranchInst>(I);
1287       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1288       if (II.isConditional()) {
1289         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1290         pushValue(II.getCondition(), InstID, Vals, VE);
1291       }
1292     }
1293     break;
1294   case Instruction::Switch:
1295     {
1296       Code = bitc::FUNC_CODE_INST_SWITCH;
1297       const SwitchInst &SI = cast<SwitchInst>(I);
1298       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1299       pushValue(SI.getCondition(), InstID, Vals, VE);
1300       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1301       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1302            i != e; ++i) {
1303         Vals.push_back(VE.getValueID(i.getCaseValue()));
1304         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1305       }
1306     }
1307     break;
1308   case Instruction::IndirectBr:
1309     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1310     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1311     // Encode the address operand as relative, but not the basic blocks.
1312     pushValue(I.getOperand(0), InstID, Vals, VE);
1313     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1314       Vals.push_back(VE.getValueID(I.getOperand(i)));
1315     break;
1316
1317   case Instruction::Invoke: {
1318     const InvokeInst *II = cast<InvokeInst>(&I);
1319     const Value *Callee(II->getCalledValue());
1320     PointerType *PTy = cast<PointerType>(Callee->getType());
1321     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1322     Code = bitc::FUNC_CODE_INST_INVOKE;
1323
1324     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1325     Vals.push_back(II->getCallingConv());
1326     Vals.push_back(VE.getValueID(II->getNormalDest()));
1327     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1328     PushValueAndType(Callee, InstID, Vals, VE);
1329
1330     // Emit value #'s for the fixed parameters.
1331     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1332       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1333
1334     // Emit type/value pairs for varargs params.
1335     if (FTy->isVarArg()) {
1336       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1337            i != e; ++i)
1338         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1339     }
1340     break;
1341   }
1342   case Instruction::Resume:
1343     Code = bitc::FUNC_CODE_INST_RESUME;
1344     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1345     break;
1346   case Instruction::Unreachable:
1347     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1348     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1349     break;
1350
1351   case Instruction::PHI: {
1352     const PHINode &PN = cast<PHINode>(I);
1353     Code = bitc::FUNC_CODE_INST_PHI;
1354     // With the newer instruction encoding, forward references could give
1355     // negative valued IDs.  This is most common for PHIs, so we use
1356     // signed VBRs.
1357     SmallVector<uint64_t, 128> Vals64;
1358     Vals64.push_back(VE.getTypeID(PN.getType()));
1359     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1360       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1361       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1362     }
1363     // Emit a Vals64 vector and exit.
1364     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1365     Vals64.clear();
1366     return;
1367   }
1368
1369   case Instruction::LandingPad: {
1370     const LandingPadInst &LP = cast<LandingPadInst>(I);
1371     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1372     Vals.push_back(VE.getTypeID(LP.getType()));
1373     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1374     Vals.push_back(LP.isCleanup());
1375     Vals.push_back(LP.getNumClauses());
1376     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1377       if (LP.isCatch(I))
1378         Vals.push_back(LandingPadInst::Catch);
1379       else
1380         Vals.push_back(LandingPadInst::Filter);
1381       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1382     }
1383     break;
1384   }
1385
1386   case Instruction::Alloca:
1387     Code = bitc::FUNC_CODE_INST_ALLOCA;
1388     Vals.push_back(VE.getTypeID(I.getType()));
1389     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1390     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1391     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1392     break;
1393
1394   case Instruction::Load:
1395     if (cast<LoadInst>(I).isAtomic()) {
1396       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1397       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1398     } else {
1399       Code = bitc::FUNC_CODE_INST_LOAD;
1400       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1401         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1402     }
1403     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1404     Vals.push_back(cast<LoadInst>(I).isVolatile());
1405     if (cast<LoadInst>(I).isAtomic()) {
1406       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1407       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1408     }
1409     break;
1410   case Instruction::Store:
1411     if (cast<StoreInst>(I).isAtomic())
1412       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1413     else
1414       Code = bitc::FUNC_CODE_INST_STORE;
1415     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1416     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1417     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1418     Vals.push_back(cast<StoreInst>(I).isVolatile());
1419     if (cast<StoreInst>(I).isAtomic()) {
1420       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1421       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1422     }
1423     break;
1424   case Instruction::AtomicCmpXchg:
1425     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1426     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1427     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1428     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1429     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1430     Vals.push_back(GetEncodedOrdering(
1431                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1432     Vals.push_back(GetEncodedSynchScope(
1433                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1434     break;
1435   case Instruction::AtomicRMW:
1436     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1437     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1438     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1439     Vals.push_back(GetEncodedRMWOperation(
1440                      cast<AtomicRMWInst>(I).getOperation()));
1441     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1442     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1443     Vals.push_back(GetEncodedSynchScope(
1444                      cast<AtomicRMWInst>(I).getSynchScope()));
1445     break;
1446   case Instruction::Fence:
1447     Code = bitc::FUNC_CODE_INST_FENCE;
1448     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1449     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1450     break;
1451   case Instruction::Call: {
1452     const CallInst &CI = cast<CallInst>(I);
1453     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1454     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1455
1456     Code = bitc::FUNC_CODE_INST_CALL;
1457
1458     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1459     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1460     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1461
1462     // Emit value #'s for the fixed parameters.
1463     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1464       // Check for labels (can happen with asm labels).
1465       if (FTy->getParamType(i)->isLabelTy())
1466         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1467       else
1468         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1469     }
1470
1471     // Emit type/value pairs for varargs params.
1472     if (FTy->isVarArg()) {
1473       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1474            i != e; ++i)
1475         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1476     }
1477     break;
1478   }
1479   case Instruction::VAArg:
1480     Code = bitc::FUNC_CODE_INST_VAARG;
1481     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1482     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1483     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1484     break;
1485   }
1486
1487   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1488   Vals.clear();
1489 }
1490
1491 // Emit names for globals/functions etc.
1492 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1493                                   const ValueEnumerator &VE,
1494                                   BitstreamWriter &Stream) {
1495   if (VST.empty()) return;
1496   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1497
1498   // FIXME: Set up the abbrev, we know how many values there are!
1499   // FIXME: We know if the type names can use 7-bit ascii.
1500   SmallVector<unsigned, 64> NameVals;
1501
1502   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1503        SI != SE; ++SI) {
1504
1505     const ValueName &Name = *SI;
1506
1507     // Figure out the encoding to use for the name.
1508     bool is7Bit = true;
1509     bool isChar6 = true;
1510     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1511          C != E; ++C) {
1512       if (isChar6)
1513         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1514       if ((unsigned char)*C & 128) {
1515         is7Bit = false;
1516         break;  // don't bother scanning the rest.
1517       }
1518     }
1519
1520     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1521
1522     // VST_ENTRY:   [valueid, namechar x N]
1523     // VST_BBENTRY: [bbid, namechar x N]
1524     unsigned Code;
1525     if (isa<BasicBlock>(SI->getValue())) {
1526       Code = bitc::VST_CODE_BBENTRY;
1527       if (isChar6)
1528         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1529     } else {
1530       Code = bitc::VST_CODE_ENTRY;
1531       if (isChar6)
1532         AbbrevToUse = VST_ENTRY_6_ABBREV;
1533       else if (is7Bit)
1534         AbbrevToUse = VST_ENTRY_7_ABBREV;
1535     }
1536
1537     NameVals.push_back(VE.getValueID(SI->getValue()));
1538     for (const char *P = Name.getKeyData(),
1539          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1540       NameVals.push_back((unsigned char)*P);
1541
1542     // Emit the finished record.
1543     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1544     NameVals.clear();
1545   }
1546   Stream.ExitBlock();
1547 }
1548
1549 /// WriteFunction - Emit a function body to the module stream.
1550 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1551                           BitstreamWriter &Stream) {
1552   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1553   VE.incorporateFunction(F);
1554
1555   SmallVector<unsigned, 64> Vals;
1556
1557   // Emit the number of basic blocks, so the reader can create them ahead of
1558   // time.
1559   Vals.push_back(VE.getBasicBlocks().size());
1560   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1561   Vals.clear();
1562
1563   // If there are function-local constants, emit them now.
1564   unsigned CstStart, CstEnd;
1565   VE.getFunctionConstantRange(CstStart, CstEnd);
1566   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1567
1568   // If there is function-local metadata, emit it now.
1569   WriteFunctionLocalMetadata(F, VE, Stream);
1570
1571   // Keep a running idea of what the instruction ID is.
1572   unsigned InstID = CstEnd;
1573
1574   bool NeedsMetadataAttachment = false;
1575
1576   DebugLoc LastDL;
1577
1578   // Finally, emit all the instructions, in order.
1579   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1580     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1581          I != E; ++I) {
1582       WriteInstruction(*I, InstID, VE, Stream, Vals);
1583
1584       if (!I->getType()->isVoidTy())
1585         ++InstID;
1586
1587       // If the instruction has metadata, write a metadata attachment later.
1588       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1589
1590       // If the instruction has a debug location, emit it.
1591       DebugLoc DL = I->getDebugLoc();
1592       if (DL.isUnknown()) {
1593         // nothing todo.
1594       } else if (DL == LastDL) {
1595         // Just repeat the same debug loc as last time.
1596         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1597       } else {
1598         MDNode *Scope, *IA;
1599         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1600
1601         Vals.push_back(DL.getLine());
1602         Vals.push_back(DL.getCol());
1603         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1604         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1605         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1606         Vals.clear();
1607
1608         LastDL = DL;
1609       }
1610     }
1611
1612   // Emit names for all the instructions etc.
1613   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1614
1615   if (NeedsMetadataAttachment)
1616     WriteMetadataAttachment(F, VE, Stream);
1617   VE.purgeFunction();
1618   Stream.ExitBlock();
1619 }
1620
1621 // Emit blockinfo, which defines the standard abbreviations etc.
1622 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1623   // We only want to emit block info records for blocks that have multiple
1624   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1625   // Other blocks can define their abbrevs inline.
1626   Stream.EnterBlockInfoBlock(2);
1627
1628   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1629     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1630     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1631     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1632     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1633     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1634     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1635                                    Abbv) != VST_ENTRY_8_ABBREV)
1636       llvm_unreachable("Unexpected abbrev ordering!");
1637   }
1638
1639   { // 7-bit fixed width VST_ENTRY strings.
1640     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1641     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1642     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1643     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1644     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1645     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1646                                    Abbv) != VST_ENTRY_7_ABBREV)
1647       llvm_unreachable("Unexpected abbrev ordering!");
1648   }
1649   { // 6-bit char6 VST_ENTRY strings.
1650     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1651     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1652     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1653     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1654     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1655     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1656                                    Abbv) != VST_ENTRY_6_ABBREV)
1657       llvm_unreachable("Unexpected abbrev ordering!");
1658   }
1659   { // 6-bit char6 VST_BBENTRY strings.
1660     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1661     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1662     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1663     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1664     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1665     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1666                                    Abbv) != VST_BBENTRY_6_ABBREV)
1667       llvm_unreachable("Unexpected abbrev ordering!");
1668   }
1669
1670
1671
1672   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1673     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1674     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1675     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1676                               Log2_32_Ceil(VE.getTypes().size()+1)));
1677     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1678                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1679       llvm_unreachable("Unexpected abbrev ordering!");
1680   }
1681
1682   { // INTEGER abbrev for CONSTANTS_BLOCK.
1683     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1684     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1685     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1686     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1687                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1688       llvm_unreachable("Unexpected abbrev ordering!");
1689   }
1690
1691   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1692     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1693     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1694     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1695     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1696                               Log2_32_Ceil(VE.getTypes().size()+1)));
1697     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1698
1699     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1700                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1701       llvm_unreachable("Unexpected abbrev ordering!");
1702   }
1703   { // NULL abbrev for CONSTANTS_BLOCK.
1704     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1705     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1706     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1707                                    Abbv) != CONSTANTS_NULL_Abbrev)
1708       llvm_unreachable("Unexpected abbrev ordering!");
1709   }
1710
1711   // FIXME: This should only use space for first class types!
1712
1713   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1714     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1715     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1716     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1717     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1718     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1719     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1720                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1721       llvm_unreachable("Unexpected abbrev ordering!");
1722   }
1723   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1724     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1725     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1726     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1727     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1728     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1729     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1730                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1731       llvm_unreachable("Unexpected abbrev ordering!");
1732   }
1733   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1734     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1735     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1736     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1737     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1738     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1739     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1740     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1741                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1742       llvm_unreachable("Unexpected abbrev ordering!");
1743   }
1744   { // INST_CAST abbrev for FUNCTION_BLOCK.
1745     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1746     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1747     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1748     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1749                               Log2_32_Ceil(VE.getTypes().size()+1)));
1750     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1751     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1752                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1753       llvm_unreachable("Unexpected abbrev ordering!");
1754   }
1755
1756   { // INST_RET abbrev for FUNCTION_BLOCK.
1757     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1758     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1759     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1760                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1761       llvm_unreachable("Unexpected abbrev ordering!");
1762   }
1763   { // INST_RET abbrev for FUNCTION_BLOCK.
1764     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1765     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1766     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1767     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1768                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1769       llvm_unreachable("Unexpected abbrev ordering!");
1770   }
1771   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1772     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1773     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1774     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1775                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1776       llvm_unreachable("Unexpected abbrev ordering!");
1777   }
1778
1779   Stream.ExitBlock();
1780 }
1781
1782 // Sort the Users based on the order in which the reader parses the bitcode
1783 // file.
1784 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1785   // TODO: Implement.
1786   return true;
1787 }
1788
1789 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1790                          BitstreamWriter &Stream) {
1791
1792   // One or zero uses can't get out of order.
1793   if (V->use_empty() || V->hasNUses(1))
1794     return;
1795
1796   // Make a copy of the in-memory use-list for sorting.
1797   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1798   SmallVector<const User*, 8> UseList;
1799   UseList.reserve(UseListSize);
1800   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1801        I != E; ++I) {
1802     const User *U = *I;
1803     UseList.push_back(U);
1804   }
1805
1806   // Sort the copy based on the order read by the BitcodeReader.
1807   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1808
1809   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1810   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1811
1812   // TODO: Emit the USELIST_CODE_ENTRYs.
1813 }
1814
1815 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1816                                  BitstreamWriter &Stream) {
1817   VE.incorporateFunction(*F);
1818
1819   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1820        AI != AE; ++AI)
1821     WriteUseList(AI, VE, Stream);
1822   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1823        ++BB) {
1824     WriteUseList(BB, VE, Stream);
1825     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1826          ++II) {
1827       WriteUseList(II, VE, Stream);
1828       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1829            OI != E; ++OI) {
1830         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1831             isa<InlineAsm>(*OI))
1832           WriteUseList(*OI, VE, Stream);
1833       }
1834     }
1835   }
1836   VE.purgeFunction();
1837 }
1838
1839 // Emit use-lists.
1840 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1841                                 BitstreamWriter &Stream) {
1842   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1843
1844   // XXX: this modifies the module, but in a way that should never change the
1845   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1846   // contain entries in the use_list that do not exist in the Module and are
1847   // not stored in the .bc file.
1848   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1849        I != E; ++I)
1850     I->removeDeadConstantUsers();
1851
1852   // Write the global variables.
1853   for (Module::const_global_iterator GI = M->global_begin(),
1854          GE = M->global_end(); GI != GE; ++GI) {
1855     WriteUseList(GI, VE, Stream);
1856
1857     // Write the global variable initializers.
1858     if (GI->hasInitializer())
1859       WriteUseList(GI->getInitializer(), VE, Stream);
1860   }
1861
1862   // Write the functions.
1863   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1864     WriteUseList(FI, VE, Stream);
1865     if (!FI->isDeclaration())
1866       WriteFunctionUseList(FI, VE, Stream);
1867     if (FI->hasPrefixData())
1868       WriteUseList(FI->getPrefixData(), VE, Stream);
1869   }
1870
1871   // Write the aliases.
1872   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1873        AI != AE; ++AI) {
1874     WriteUseList(AI, VE, Stream);
1875     WriteUseList(AI->getAliasee(), VE, Stream);
1876   }
1877
1878   Stream.ExitBlock();
1879 }
1880
1881 /// WriteModule - Emit the specified module to the bitstream.
1882 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1883   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1884
1885   SmallVector<unsigned, 1> Vals;
1886   unsigned CurVersion = 1;
1887   Vals.push_back(CurVersion);
1888   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1889
1890   // Analyze the module, enumerating globals, functions, etc.
1891   ValueEnumerator VE(M);
1892
1893   // Emit blockinfo, which defines the standard abbreviations etc.
1894   WriteBlockInfo(VE, Stream);
1895
1896   // Emit information about attribute groups.
1897   WriteAttributeGroupTable(VE, Stream);
1898
1899   // Emit information about parameter attributes.
1900   WriteAttributeTable(VE, Stream);
1901
1902   // Emit information describing all of the types in the module.
1903   WriteTypeTable(VE, Stream);
1904
1905   // Emit top-level description of module, including target triple, inline asm,
1906   // descriptors for global variables, and function prototype info.
1907   WriteModuleInfo(M, VE, Stream);
1908
1909   // Emit constants.
1910   WriteModuleConstants(VE, Stream);
1911
1912   // Emit metadata.
1913   WriteModuleMetadata(M, VE, Stream);
1914
1915   // Emit metadata.
1916   WriteModuleMetadataStore(M, Stream);
1917
1918   // Emit names for globals/functions etc.
1919   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1920
1921   // Emit use-lists.
1922   if (EnablePreserveUseListOrdering)
1923     WriteModuleUseLists(M, VE, Stream);
1924
1925   // Emit function bodies.
1926   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1927     if (!F->isDeclaration())
1928       WriteFunction(*F, VE, Stream);
1929
1930   Stream.ExitBlock();
1931 }
1932
1933 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1934 /// header and trailer to make it compatible with the system archiver.  To do
1935 /// this we emit the following header, and then emit a trailer that pads the
1936 /// file out to be a multiple of 16 bytes.
1937 ///
1938 /// struct bc_header {
1939 ///   uint32_t Magic;         // 0x0B17C0DE
1940 ///   uint32_t Version;       // Version, currently always 0.
1941 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1942 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1943 ///   uint32_t CPUType;       // CPU specifier.
1944 ///   ... potentially more later ...
1945 /// };
1946 enum {
1947   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1948   DarwinBCHeaderSize = 5*4
1949 };
1950
1951 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1952                                uint32_t &Position) {
1953   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1954   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1955   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1956   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1957   Position += 4;
1958 }
1959
1960 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1961                                          const Triple &TT) {
1962   unsigned CPUType = ~0U;
1963
1964   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1965   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1966   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1967   // specific constants here because they are implicitly part of the Darwin ABI.
1968   enum {
1969     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1970     DARWIN_CPU_TYPE_X86        = 7,
1971     DARWIN_CPU_TYPE_ARM        = 12,
1972     DARWIN_CPU_TYPE_POWERPC    = 18
1973   };
1974
1975   Triple::ArchType Arch = TT.getArch();
1976   if (Arch == Triple::x86_64)
1977     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1978   else if (Arch == Triple::x86)
1979     CPUType = DARWIN_CPU_TYPE_X86;
1980   else if (Arch == Triple::ppc)
1981     CPUType = DARWIN_CPU_TYPE_POWERPC;
1982   else if (Arch == Triple::ppc64)
1983     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1984   else if (Arch == Triple::arm || Arch == Triple::thumb)
1985     CPUType = DARWIN_CPU_TYPE_ARM;
1986
1987   // Traditional Bitcode starts after header.
1988   assert(Buffer.size() >= DarwinBCHeaderSize &&
1989          "Expected header size to be reserved");
1990   unsigned BCOffset = DarwinBCHeaderSize;
1991   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1992
1993   // Write the magic and version.
1994   unsigned Position = 0;
1995   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1996   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1997   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1998   WriteInt32ToBuffer(BCSize     , Buffer, Position);
1999   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2000
2001   // If the file is not a multiple of 16 bytes, insert dummy padding.
2002   while (Buffer.size() & 15)
2003     Buffer.push_back(0);
2004 }
2005
2006 /// WriteBitcodeToFile - Write the specified module to the specified output
2007 /// stream.
2008 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2009   SmallVector<char, 0> Buffer;
2010   Buffer.reserve(256*1024);
2011
2012   // If this is darwin or another generic macho target, reserve space for the
2013   // header.
2014   Triple TT(M->getTargetTriple());
2015   if (TT.isOSDarwin())
2016     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2017
2018   // Emit the module into the buffer.
2019   {
2020     BitstreamWriter Stream(Buffer);
2021
2022     // Emit the file header.
2023     Stream.Emit((unsigned)'B', 8);
2024     Stream.Emit((unsigned)'C', 8);
2025     Stream.Emit(0x0, 4);
2026     Stream.Emit(0xC, 4);
2027     Stream.Emit(0xE, 4);
2028     Stream.Emit(0xD, 4);
2029
2030     // Emit the module.
2031     WriteModule(M, Stream);
2032   }
2033
2034   if (TT.isOSDarwin())
2035     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2036
2037   // Write the generated bitstream to "Out".
2038   Out.write((char*)&Buffer.front(), Buffer.size());
2039 }