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