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/DebugInfoMetadata.h"
  21 #include "llvm/IR/DerivedTypes.h"
  22 #include "llvm/IR/InlineAsm.h"
  23 #include "llvm/IR/Instructions.h"
  24 #include "llvm/IR/Module.h"
  25 #include "llvm/IR/Operator.h"
  26 #include "llvm/IR/UseListOrder.h"
  27 #include "llvm/IR/ValueSymbolTable.h"
  28 #include "llvm/Support/CommandLine.h"
  29 #include "llvm/Support/ErrorHandling.h"
  30 #include "llvm/Support/MathExtras.h"
  31 #include "llvm/Support/Program.h"
  32 #include "llvm/Support/raw_ostream.h"
  33 #include <cctype>
  34 #include <map>
  35 using namespace llvm;
  36
  37 /// These are manifest constants used by the bitcode writer. They do not need to
  38 /// be kept in sync with the reader, but need to be consistent within this file.
  39 enum {
  40   // VALUE_SYMTAB_BLOCK abbrev id's.
  41   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  42   VST_ENTRY_7_ABBREV,
  43   VST_ENTRY_6_ABBREV,
  44   VST_BBENTRY_6_ABBREV,
  45
  46   // CONSTANTS_BLOCK abbrev id's.
  47   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  48   CONSTANTS_INTEGER_ABBREV,
  49   CONSTANTS_CE_CAST_Abbrev,
  50   CONSTANTS_NULL_Abbrev,
  51
  52   // FUNCTION_BLOCK abbrev id's.
  53   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  54   FUNCTION_INST_BINOP_ABBREV,
  55   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  56   FUNCTION_INST_CAST_ABBREV,
  57   FUNCTION_INST_RET_VOID_ABBREV,
  58   FUNCTION_INST_RET_VAL_ABBREV,
  59   FUNCTION_INST_UNREACHABLE_ABBREV
  60 };
  61
  62 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  63   switch (Opcode) {
  64   default: llvm_unreachable("Unknown cast instruction!");
  65   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  66   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  67   case Instruction::SExt    : return bitc::CAST_SEXT;
  68   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  69   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  70   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  71   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  72   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  73   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  74   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  75   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  76   case Instruction::BitCast : return bitc::CAST_BITCAST;
  77   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
  78   }
  79 }
  80
  81 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  82   switch (Opcode) {
  83   default: llvm_unreachable("Unknown binary instruction!");
  84   case Instruction::Add:
  85   case Instruction::FAdd: return bitc::BINOP_ADD;
  86   case Instruction::Sub:
  87   case Instruction::FSub: return bitc::BINOP_SUB;
  88   case Instruction::Mul:
  89   case Instruction::FMul: return bitc::BINOP_MUL;
  90   case Instruction::UDiv: return bitc::BINOP_UDIV;
  91   case Instruction::FDiv:
  92   case Instruction::SDiv: return bitc::BINOP_SDIV;
  93   case Instruction::URem: return bitc::BINOP_UREM;
  94   case Instruction::FRem:
  95   case Instruction::SRem: return bitc::BINOP_SREM;
  96   case Instruction::Shl:  return bitc::BINOP_SHL;
  97   case Instruction::LShr: return bitc::BINOP_LSHR;
  98   case Instruction::AShr: return bitc::BINOP_ASHR;
  99   case Instruction::And:  return bitc::BINOP_AND;
 100   case Instruction::Or:   return bitc::BINOP_OR;
 101   case Instruction::Xor:  return bitc::BINOP_XOR;
 102   }
 103 }
 104
 105 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 106   switch (Op) {
 107   default: llvm_unreachable("Unknown RMW operation!");
 108   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 109   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 110   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 111   case AtomicRMWInst::And: return bitc::RMW_AND;
 112   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 113   case AtomicRMWInst::Or: return bitc::RMW_OR;
 114   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 115   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 116   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 117   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 118   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 119   }
 120 }
 121
 122 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 123   switch (Ordering) {
 124   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 125   case Unordered: return bitc::ORDERING_UNORDERED;
 126   case Monotonic: return bitc::ORDERING_MONOTONIC;
 127   case Acquire: return bitc::ORDERING_ACQUIRE;
 128   case Release: return bitc::ORDERING_RELEASE;
 129   case AcquireRelease: return bitc::ORDERING_ACQREL;
 130   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 131   }
 132   llvm_unreachable("Invalid ordering");
 133 }
 134
 135 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 136   switch (SynchScope) {
 137   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 138   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 139   }
 140   llvm_unreachable("Invalid synch scope");
 141 }
 142
 143 static void WriteStringRecord(unsigned Code, StringRef Str,
 144                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 145   SmallVector<unsigned, 64> Vals;
 146
 147   // Code: [strchar x N]
 148   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 149     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 150       AbbrevToUse = 0;
 151     Vals.push_back(Str[i]);
 152   }
 153
 154   // Emit the finished record.
 155   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 156 }
 157
 158 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
 159   switch (Kind) {
 160   case Attribute::Alignment:
 161     return bitc::ATTR_KIND_ALIGNMENT;
 162   case Attribute::AlwaysInline:
 163     return bitc::ATTR_KIND_ALWAYS_INLINE;
 164   case Attribute::Builtin:
 165     return bitc::ATTR_KIND_BUILTIN;
 166   case Attribute::ByVal:
 167     return bitc::ATTR_KIND_BY_VAL;
 168   case Attribute::InAlloca:
 169     return bitc::ATTR_KIND_IN_ALLOCA;
 170   case Attribute::Cold:
 171     return bitc::ATTR_KIND_COLD;
 172   case Attribute::InlineHint:
 173     return bitc::ATTR_KIND_INLINE_HINT;
 174   case Attribute::InReg:
 175     return bitc::ATTR_KIND_IN_REG;
 176   case Attribute::JumpTable:
 177     return bitc::ATTR_KIND_JUMP_TABLE;
 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::NonNull:
 199     return bitc::ATTR_KIND_NON_NULL;
 200   case Attribute::Dereferenceable:
 201     return bitc::ATTR_KIND_DEREFERENCEABLE;
 202   case Attribute::NoRedZone:
 203     return bitc::ATTR_KIND_NO_RED_ZONE;
 204   case Attribute::NoReturn:
 205     return bitc::ATTR_KIND_NO_RETURN;
 206   case Attribute::NoUnwind:
 207     return bitc::ATTR_KIND_NO_UNWIND;
 208   case Attribute::OptimizeForSize:
 209     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
 210   case Attribute::OptimizeNone:
 211     return bitc::ATTR_KIND_OPTIMIZE_NONE;
 212   case Attribute::ReadNone:
 213     return bitc::ATTR_KIND_READ_NONE;
 214   case Attribute::ReadOnly:
 215     return bitc::ATTR_KIND_READ_ONLY;
 216   case Attribute::Returned:
 217     return bitc::ATTR_KIND_RETURNED;
 218   case Attribute::ReturnsTwice:
 219     return bitc::ATTR_KIND_RETURNS_TWICE;
 220   case Attribute::SExt:
 221     return bitc::ATTR_KIND_S_EXT;
 222   case Attribute::StackAlignment:
 223     return bitc::ATTR_KIND_STACK_ALIGNMENT;
 224   case Attribute::StackProtect:
 225     return bitc::ATTR_KIND_STACK_PROTECT;
 226   case Attribute::StackProtectReq:
 227     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
 228   case Attribute::StackProtectStrong:
 229     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
 230   case Attribute::StructRet:
 231     return bitc::ATTR_KIND_STRUCT_RET;
 232   case Attribute::SanitizeAddress:
 233     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
 234   case Attribute::SanitizeThread:
 235     return bitc::ATTR_KIND_SANITIZE_THREAD;
 236   case Attribute::SanitizeMemory:
 237     return bitc::ATTR_KIND_SANITIZE_MEMORY;
 238   case Attribute::UWTable:
 239     return bitc::ATTR_KIND_UW_TABLE;
 240   case Attribute::ZExt:
 241     return bitc::ATTR_KIND_Z_EXT;
 242   case Attribute::EndAttrKinds:
 243     llvm_unreachable("Can not encode end-attribute kinds marker.");
 244   case Attribute::None:
 245     llvm_unreachable("Can not encode none-attribute.");
 246   }
 247
 248   llvm_unreachable("Trying to encode unknown attribute");
 249 }
 250
 251 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
 252                                      BitstreamWriter &Stream) {
 253   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
 254   if (AttrGrps.empty()) return;
 255
 256   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 257
 258   SmallVector<uint64_t, 64> Record;
 259   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
 260     AttributeSet AS = AttrGrps[i];
 261     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
 262       AttributeSet A = AS.getSlotAttributes(i);
 263
 264       Record.push_back(VE.getAttributeGroupID(A));
 265       Record.push_back(AS.getSlotIndex(i));
 266
 267       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
 268            I != E; ++I) {
 269         Attribute Attr = *I;
 270         if (Attr.isEnumAttribute()) {
 271           Record.push_back(0);
 272           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 273         } else if (Attr.isIntAttribute()) {
 274           Record.push_back(1);
 275           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 276           Record.push_back(Attr.getValueAsInt());
 277         } else {
 278           StringRef Kind = Attr.getKindAsString();
 279           StringRef Val = Attr.getValueAsString();
 280
 281           Record.push_back(Val.empty() ? 3 : 4);
 282           Record.append(Kind.begin(), Kind.end());
 283           Record.push_back(0);
 284           if (!Val.empty()) {
 285             Record.append(Val.begin(), Val.end());
 286             Record.push_back(0);
 287           }
 288         }
 289       }
 290
 291       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
 292       Record.clear();
 293     }
 294   }
 295
 296   Stream.ExitBlock();
 297 }
 298
 299 static void WriteAttributeTable(const ValueEnumerator &VE,
 300                                 BitstreamWriter &Stream) {
 301   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 302   if (Attrs.empty()) return;
 303
 304   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 305
 306   SmallVector<uint64_t, 64> Record;
 307   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 308     const AttributeSet &A = Attrs[i];
 309     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
 310       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
 311
 312     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 313     Record.clear();
 314   }
 315
 316   Stream.ExitBlock();
 317 }
 318
 319 /// WriteTypeTable - Write out the type table for a module.
 320 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 321   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 322
 323   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 324   SmallVector<uint64_t, 64> TypeVals;
 325
 326   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 327
 328   // Abbrev for TYPE_CODE_POINTER.
 329   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 330   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 331   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 332   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 333   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 334
 335   // Abbrev for TYPE_CODE_FUNCTION.
 336   Abbv = new BitCodeAbbrev();
 337   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 338   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 339   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 340   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 341
 342   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 343
 344   // Abbrev for TYPE_CODE_STRUCT_ANON.
 345   Abbv = new BitCodeAbbrev();
 346   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 347   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 348   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 349   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 350
 351   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 352
 353   // Abbrev for TYPE_CODE_STRUCT_NAME.
 354   Abbv = new BitCodeAbbrev();
 355   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 356   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 357   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 358   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 359
 360   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 361   Abbv = new BitCodeAbbrev();
 362   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 363   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 365   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 366
 367   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 368
 369   // Abbrev for TYPE_CODE_ARRAY.
 370   Abbv = new BitCodeAbbrev();
 371   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 374
 375   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 376
 377   // Emit an entry count so the reader can reserve space.
 378   TypeVals.push_back(TypeList.size());
 379   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 380   TypeVals.clear();
 381
 382   // Loop over all of the types, emitting each in turn.
 383   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 384     Type *T = TypeList[i];
 385     int AbbrevToUse = 0;
 386     unsigned Code = 0;
 387
 388     switch (T->getTypeID()) {
 389     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 390     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 391     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 392     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 393     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 394     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 395     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 396     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 397     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 398     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 399     case Type::IntegerTyID:
 400       // INTEGER: [width]
 401       Code = bitc::TYPE_CODE_INTEGER;
 402       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 403       break;
 404     case Type::PointerTyID: {
 405       PointerType *PTy = cast<PointerType>(T);
 406       // POINTER: [pointee type, address space]
 407       Code = bitc::TYPE_CODE_POINTER;
 408       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 409       unsigned AddressSpace = PTy->getAddressSpace();
 410       TypeVals.push_back(AddressSpace);
 411       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 412       break;
 413     }
 414     case Type::FunctionTyID: {
 415       FunctionType *FT = cast<FunctionType>(T);
 416       // FUNCTION: [isvararg, retty, paramty x N]
 417       Code = bitc::TYPE_CODE_FUNCTION;
 418       TypeVals.push_back(FT->isVarArg());
 419       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 420       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 421         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 422       AbbrevToUse = FunctionAbbrev;
 423       break;
 424     }
 425     case Type::StructTyID: {
 426       StructType *ST = cast<StructType>(T);
 427       // STRUCT: [ispacked, eltty x N]
 428       TypeVals.push_back(ST->isPacked());
 429       // Output all of the element types.
 430       for (StructType::element_iterator I = ST->element_begin(),
 431            E = ST->element_end(); I != E; ++I)
 432         TypeVals.push_back(VE.getTypeID(*I));
 433
 434       if (ST->isLiteral()) {
 435         Code = bitc::TYPE_CODE_STRUCT_ANON;
 436         AbbrevToUse = StructAnonAbbrev;
 437       } else {
 438         if (ST->isOpaque()) {
 439           Code = bitc::TYPE_CODE_OPAQUE;
 440         } else {
 441           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 442           AbbrevToUse = StructNamedAbbrev;
 443         }
 444
 445         // Emit the name if it is present.
 446         if (!ST->getName().empty())
 447           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 448                             StructNameAbbrev, Stream);
 449       }
 450       break;
 451     }
 452     case Type::ArrayTyID: {
 453       ArrayType *AT = cast<ArrayType>(T);
 454       // ARRAY: [numelts, eltty]
 455       Code = bitc::TYPE_CODE_ARRAY;
 456       TypeVals.push_back(AT->getNumElements());
 457       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 458       AbbrevToUse = ArrayAbbrev;
 459       break;
 460     }
 461     case Type::VectorTyID: {
 462       VectorType *VT = cast<VectorType>(T);
 463       // VECTOR [numelts, eltty]
 464       Code = bitc::TYPE_CODE_VECTOR;
 465       TypeVals.push_back(VT->getNumElements());
 466       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 467       break;
 468     }
 469     }
 470
 471     // Emit the finished record.
 472     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 473     TypeVals.clear();
 474   }
 475
 476   Stream.ExitBlock();
 477 }
 478
 479 static unsigned getEncodedLinkage(const GlobalValue &GV) {
 480   switch (GV.getLinkage()) {
 481   case GlobalValue::ExternalLinkage:
 482     return 0;
 483   case GlobalValue::WeakAnyLinkage:
 484     return 16;
 485   case GlobalValue::AppendingLinkage:
 486     return 2;
 487   case GlobalValue::InternalLinkage:
 488     return 3;
 489   case GlobalValue::LinkOnceAnyLinkage:
 490     return 18;
 491   case GlobalValue::ExternalWeakLinkage:
 492     return 7;
 493   case GlobalValue::CommonLinkage:
 494     return 8;
 495   case GlobalValue::PrivateLinkage:
 496     return 9;
 497   case GlobalValue::WeakODRLinkage:
 498     return 17;
 499   case GlobalValue::LinkOnceODRLinkage:
 500     return 19;
 501   case GlobalValue::AvailableExternallyLinkage:
 502     return 12;
 503   }
 504   llvm_unreachable("Invalid linkage");
 505 }
 506
 507 static unsigned getEncodedVisibility(const GlobalValue &GV) {
 508   switch (GV.getVisibility()) {
 509   case GlobalValue::DefaultVisibility:   return 0;
 510   case GlobalValue::HiddenVisibility:    return 1;
 511   case GlobalValue::ProtectedVisibility: return 2;
 512   }
 513   llvm_unreachable("Invalid visibility");
 514 }
 515
 516 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
 517   switch (GV.getDLLStorageClass()) {
 518   case GlobalValue::DefaultStorageClass:   return 0;
 519   case GlobalValue::DLLImportStorageClass: return 1;
 520   case GlobalValue::DLLExportStorageClass: return 2;
 521   }
 522   llvm_unreachable("Invalid DLL storage class");
 523 }
 524
 525 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
 526   switch (GV.getThreadLocalMode()) {
 527     case GlobalVariable::NotThreadLocal:         return 0;
 528     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 529     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 530     case GlobalVariable::InitialExecTLSModel:    return 3;
 531     case GlobalVariable::LocalExecTLSModel:      return 4;
 532   }
 533   llvm_unreachable("Invalid TLS model");
 534 }
 535
 536 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
 537   switch (C.getSelectionKind()) {
 538   case Comdat::Any:
 539     return bitc::COMDAT_SELECTION_KIND_ANY;
 540   case Comdat::ExactMatch:
 541     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
 542   case Comdat::Largest:
 543     return bitc::COMDAT_SELECTION_KIND_LARGEST;
 544   case Comdat::NoDuplicates:
 545     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
 546   case Comdat::SameSize:
 547     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
 548   }
 549   llvm_unreachable("Invalid selection kind");
 550 }
 551
 552 static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 553   SmallVector<uint16_t, 64> Vals;
 554   for (const Comdat *C : VE.getComdats()) {
 555     // COMDAT: [selection_kind, name]
 556     Vals.push_back(getEncodedComdatSelectionKind(*C));
 557     size_t Size = C->getName().size();
 558     assert(isUInt<16>(Size));
 559     Vals.push_back(Size);
 560     for (char Chr : C->getName())
 561       Vals.push_back((unsigned char)Chr);
 562     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
 563     Vals.clear();
 564   }
 565 }
 566
 567 // Emit top-level description of module, including target triple, inline asm,
 568 // descriptors for global variables, and function prototype info.
 569 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 570                             BitstreamWriter &Stream) {
 571   // Emit various pieces of data attached to a module.
 572   if (!M->getTargetTriple().empty())
 573     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 574                       0/*TODO*/, Stream);
 575   const std::string &DL = M->getDataLayoutStr();
 576   if (!DL.empty())
 577     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
 578   if (!M->getModuleInlineAsm().empty())
 579     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 580                       0/*TODO*/, Stream);
 581
 582   // Emit information about sections and GC, computing how many there are. Also
 583   // compute the maximum alignment value.
 584   std::map<std::string, unsigned> SectionMap;
 585   std::map<std::string, unsigned> GCMap;
 586   unsigned MaxAlignment = 0;
 587   unsigned MaxGlobalType = 0;
 588   for (const GlobalValue &GV : M->globals()) {
 589     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
 590     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getType()));
 591     if (GV.hasSection()) {
 592       // Give section names unique ID's.
 593       unsigned &Entry = SectionMap[GV.getSection()];
 594       if (!Entry) {
 595         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
 596                           0/*TODO*/, Stream);
 597         Entry = SectionMap.size();
 598       }
 599     }
 600   }
 601   for (const Function &F : *M) {
 602     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
 603     if (F.hasSection()) {
 604       // Give section names unique ID's.
 605       unsigned &Entry = SectionMap[F.getSection()];
 606       if (!Entry) {
 607         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
 608                           0/*TODO*/, Stream);
 609         Entry = SectionMap.size();
 610       }
 611     }
 612     if (F.hasGC()) {
 613       // Same for GC names.
 614       unsigned &Entry = GCMap[F.getGC()];
 615       if (!Entry) {
 616         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
 617                           0/*TODO*/, Stream);
 618         Entry = GCMap.size();
 619       }
 620     }
 621   }
 622
 623   // Emit abbrev for globals, now that we know # sections and max alignment.
 624   unsigned SimpleGVarAbbrev = 0;
 625   if (!M->global_empty()) {
 626     // Add an abbrev for common globals with no visibility or thread localness.
 627     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 628     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 629     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 630                               Log2_32_Ceil(MaxGlobalType+1)));
 631     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 632     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 633     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5));      // Linkage.
 634     if (MaxAlignment == 0)                                      // Alignment.
 635       Abbv->Add(BitCodeAbbrevOp(0));
 636     else {
 637       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 638       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 639                                Log2_32_Ceil(MaxEncAlignment+1)));
 640     }
 641     if (SectionMap.empty())                                    // Section.
 642       Abbv->Add(BitCodeAbbrevOp(0));
 643     else
 644       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 645                                Log2_32_Ceil(SectionMap.size()+1)));
 646     // Don't bother emitting vis + thread local.
 647     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 648   }
 649
 650   // Emit the global variable information.
 651   SmallVector<unsigned, 64> Vals;
 652   for (const GlobalVariable &GV : M->globals()) {
 653     unsigned AbbrevToUse = 0;
 654
 655     // GLOBALVAR: [type, isconst, initid,
 656     //             linkage, alignment, section, visibility, threadlocal,
 657     //             unnamed_addr, externally_initialized, dllstorageclass,
 658     //             comdat]
 659     Vals.push_back(VE.getTypeID(GV.getType()));
 660     Vals.push_back(GV.isConstant());
 661     Vals.push_back(GV.isDeclaration() ? 0 :
 662                    (VE.getValueID(GV.getInitializer()) + 1));
 663     Vals.push_back(getEncodedLinkage(GV));
 664     Vals.push_back(Log2_32(GV.getAlignment())+1);
 665     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
 666     if (GV.isThreadLocal() ||
 667         GV.getVisibility() != GlobalValue::DefaultVisibility ||
 668         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
 669         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
 670         GV.hasComdat()) {
 671       Vals.push_back(getEncodedVisibility(GV));
 672       Vals.push_back(getEncodedThreadLocalMode(GV));
 673       Vals.push_back(GV.hasUnnamedAddr());
 674       Vals.push_back(GV.isExternallyInitialized());
 675       Vals.push_back(getEncodedDLLStorageClass(GV));
 676       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
 677     } else {
 678       AbbrevToUse = SimpleGVarAbbrev;
 679     }
 680
 681     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 682     Vals.clear();
 683   }
 684
 685   // Emit the function proto information.
 686   for (const Function &F : *M) {
 687     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 688     //             section, visibility, gc, unnamed_addr, prologuedata,
 689     //             dllstorageclass, comdat, prefixdata]
 690     Vals.push_back(VE.getTypeID(F.getType()));
 691     Vals.push_back(F.getCallingConv());
 692     Vals.push_back(F.isDeclaration());
 693     Vals.push_back(getEncodedLinkage(F));
 694     Vals.push_back(VE.getAttributeID(F.getAttributes()));
 695     Vals.push_back(Log2_32(F.getAlignment())+1);
 696     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
 697     Vals.push_back(getEncodedVisibility(F));
 698     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
 699     Vals.push_back(F.hasUnnamedAddr());
 700     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
 701                                        : 0);
 702     Vals.push_back(getEncodedDLLStorageClass(F));
 703     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
 704     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
 705                                      : 0);
 706
 707     unsigned AbbrevToUse = 0;
 708     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 709     Vals.clear();
 710   }
 711
 712   // Emit the alias information.
 713   for (const GlobalAlias &A : M->aliases()) {
 714     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 715     Vals.push_back(VE.getTypeID(A.getType()));
 716     Vals.push_back(VE.getValueID(A.getAliasee()));
 717     Vals.push_back(getEncodedLinkage(A));
 718     Vals.push_back(getEncodedVisibility(A));
 719     Vals.push_back(getEncodedDLLStorageClass(A));
 720     Vals.push_back(getEncodedThreadLocalMode(A));
 721     Vals.push_back(A.hasUnnamedAddr());
 722     unsigned AbbrevToUse = 0;
 723     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 724     Vals.clear();
 725   }
 726 }
 727
 728 static uint64_t GetOptimizationFlags(const Value *V) {
 729   uint64_t Flags = 0;
 730
 731   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
 732     if (OBO->hasNoSignedWrap())
 733       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 734     if (OBO->hasNoUnsignedWrap())
 735       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 736   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
 737     if (PEO->isExact())
 738       Flags |= 1 << bitc::PEO_EXACT;
 739   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
 740     if (FPMO->hasUnsafeAlgebra())
 741       Flags |= FastMathFlags::UnsafeAlgebra;
 742     if (FPMO->hasNoNaNs())
 743       Flags |= FastMathFlags::NoNaNs;
 744     if (FPMO->hasNoInfs())
 745       Flags |= FastMathFlags::NoInfs;
 746     if (FPMO->hasNoSignedZeros())
 747       Flags |= FastMathFlags::NoSignedZeros;
 748     if (FPMO->hasAllowReciprocal())
 749       Flags |= FastMathFlags::AllowReciprocal;
 750   }
 751
 752   return Flags;
 753 }
 754
 755 static void WriteValueAsMetadata(const ValueAsMetadata *MD,
 756                                  const ValueEnumerator &VE,
 757                                  BitstreamWriter &Stream,
 758                                  SmallVectorImpl<uint64_t> &Record) {
 759   // Mimic an MDNode with a value as one operand.
 760   Value *V = MD->getValue();
 761   Record.push_back(VE.getTypeID(V->getType()));
 762   Record.push_back(VE.getValueID(V));
 763   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
 764   Record.clear();
 765 }
 766
 767 static void WriteMDTuple(const MDTuple *N, const ValueEnumerator &VE,
 768                          BitstreamWriter &Stream,
 769                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
 770   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 771     Metadata *MD = N->getOperand(i);
 772     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
 773            "Unexpected function-local metadata");
 774     Record.push_back(VE.getMetadataOrNullID(MD));
 775   }
 776   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
 777                                     : bitc::METADATA_NODE,
 778                     Record, Abbrev);
 779   Record.clear();
 780 }
 781
 782 static void WriteMDLocation(const MDLocation *N, const ValueEnumerator &VE,
 783                             BitstreamWriter &Stream,
 784                             SmallVectorImpl<uint64_t> &Record,
 785                             unsigned Abbrev) {
 786   Record.push_back(N->isDistinct());
 787   Record.push_back(N->getLine());
 788   Record.push_back(N->getColumn());
 789   Record.push_back(VE.getMetadataID(N->getScope()));
 790   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
 791
 792   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
 793   Record.clear();
 794 }
 795
 796 static void WriteGenericDebugNode(const GenericDebugNode *N,
 797                                   const ValueEnumerator &VE,
 798                                   BitstreamWriter &Stream,
 799                                   SmallVectorImpl<uint64_t> &Record,
 800                                   unsigned Abbrev) {
 801   Record.push_back(N->isDistinct());
 802   Record.push_back(N->getTag());
 803   Record.push_back(0); // Per-tag version field; unused for now.
 804
 805   for (auto &I : N->operands())
 806     Record.push_back(VE.getMetadataOrNullID(I));
 807
 808   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
 809   Record.clear();
 810 }
 811
 812 static uint64_t rotateSign(int64_t I) {
 813   uint64_t U = I;
 814   return I < 0 ? ~(U << 1) : U << 1;
 815 }
 816
 817 static void WriteMDSubrange(const MDSubrange *N, const ValueEnumerator &,
 818                             BitstreamWriter &Stream,
 819                             SmallVectorImpl<uint64_t> &Record,
 820                             unsigned Abbrev) {
 821   Record.push_back(N->isDistinct());
 822   Record.push_back(N->getCount());
 823   Record.push_back(rotateSign(N->getLo()));
 824
 825   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
 826   Record.clear();
 827 }
 828
 829 static void WriteMDEnumerator(const MDEnumerator *N, const ValueEnumerator &VE,
 830                               BitstreamWriter &Stream,
 831                               SmallVectorImpl<uint64_t> &Record,
 832                               unsigned Abbrev) {
 833   Record.push_back(N->isDistinct());
 834   Record.push_back(rotateSign(N->getValue()));
 835   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
 836
 837   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
 838   Record.clear();
 839 }
 840
 841 static void WriteMDBasicType(const MDBasicType *N, const ValueEnumerator &VE,
 842                              BitstreamWriter &Stream,
 843                              SmallVectorImpl<uint64_t> &Record,
 844                              unsigned Abbrev) {
 845   Record.push_back(N->isDistinct());
 846   Record.push_back(N->getTag());
 847   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
 848   Record.push_back(N->getSizeInBits());
 849   Record.push_back(N->getAlignInBits());
 850   Record.push_back(N->getEncoding());
 851
 852   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
 853   Record.clear();
 854 }
 855
 856 static void WriteMDDerivedType(const MDDerivedType *N,
 857                                const ValueEnumerator &VE,
 858                                BitstreamWriter &Stream,
 859                                SmallVectorImpl<uint64_t> &Record,
 860                                unsigned Abbrev) {
 861   Record.push_back(N->isDistinct());
 862   Record.push_back(N->getTag());
 863   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
 864   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
 865   Record.push_back(N->getLine());
 866   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
 867   Record.push_back(VE.getMetadataID(N->getBaseType()));
 868   Record.push_back(N->getSizeInBits());
 869   Record.push_back(N->getAlignInBits());
 870   Record.push_back(N->getOffsetInBits());
 871   Record.push_back(N->getFlags());
 872   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
 873
 874   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
 875   Record.clear();
 876 }
 877
 878 static void WriteMDCompositeType(const MDCompositeType *N,
 879                                  const ValueEnumerator &VE,
 880                                  BitstreamWriter &Stream,
 881                                  SmallVectorImpl<uint64_t> &Record,
 882                                  unsigned Abbrev) {
 883   Record.push_back(N->isDistinct());
 884   Record.push_back(N->getTag());
 885   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
 886   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
 887   Record.push_back(N->getLine());
 888   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
 889   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
 890   Record.push_back(N->getSizeInBits());
 891   Record.push_back(N->getAlignInBits());
 892   Record.push_back(N->getOffsetInBits());
 893   Record.push_back(N->getFlags());
 894   Record.push_back(VE.getMetadataOrNullID(N->getElements()));
 895   Record.push_back(N->getRuntimeLang());
 896   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
 897   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
 898   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
 899
 900   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
 901   Record.clear();
 902 }
 903
 904 static void WriteMDSubroutineType(const MDSubroutineType *N,
 905                                   const ValueEnumerator &VE,
 906                                   BitstreamWriter &Stream,
 907                                   SmallVectorImpl<uint64_t> &Record,
 908                                   unsigned Abbrev) {
 909   Record.push_back(N->isDistinct());
 910   Record.push_back(N->getFlags());
 911   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray()));
 912
 913   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
 914   Record.clear();
 915 }
 916
 917 static void WriteMDFile(const MDFile *N, const ValueEnumerator &VE,
 918                         BitstreamWriter &Stream,
 919                         SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
 920   Record.push_back(N->isDistinct());
 921   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
 922   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
 923
 924   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
 925   Record.clear();
 926 }
 927
 928 static void WriteMDCompileUnit(const MDCompileUnit *N,
 929                                const ValueEnumerator &VE,
 930                                BitstreamWriter &Stream,
 931                                SmallVectorImpl<uint64_t> &Record,
 932                                unsigned Abbrev) {
 933   Record.push_back(N->isDistinct());
 934   Record.push_back(N->getSourceLanguage());
 935   Record.push_back(VE.getMetadataID(N->getFile()));
 936   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
 937   Record.push_back(N->isOptimized());
 938   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
 939   Record.push_back(N->getRuntimeVersion());
 940   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
 941   Record.push_back(N->getEmissionKind());
 942   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes()));
 943   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes()));
 944   Record.push_back(VE.getMetadataOrNullID(N->getSubprograms()));
 945   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables()));
 946   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities()));
 947
 948   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
 949   Record.clear();
 950 }
 951
 952 static void WriteMDSubprogram(const MDSubprogram *N,
 953                                const ValueEnumerator &VE,
 954                                BitstreamWriter &Stream,
 955                                SmallVectorImpl<uint64_t> &Record,
 956                                unsigned Abbrev) {
 957   Record.push_back(N->isDistinct());
 958   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
 959   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
 960   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
 961   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
 962   Record.push_back(N->getLine());
 963   Record.push_back(VE.getMetadataOrNullID(N->getType()));
 964   Record.push_back(N->isLocalToUnit());
 965   Record.push_back(N->isDefinition());
 966   Record.push_back(N->getScopeLine());
 967   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
 968   Record.push_back(N->getVirtuality());
 969   Record.push_back(N->getVirtualIndex());
 970   Record.push_back(N->getFlags());
 971   Record.push_back(N->isOptimized());
 972   Record.push_back(VE.getMetadataOrNullID(N->getFunction()));
 973   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
 974   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
 975   Record.push_back(VE.getMetadataOrNullID(N->getVariables()));
 976
 977   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
 978   Record.clear();
 979 }
 980
 981 static void WriteMDLexicalBlock(const MDLexicalBlock *, const ValueEnumerator &,
 982                                 BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 983                                 unsigned) {
 984   llvm_unreachable("write not implemented");
 985 }
 986 static void WriteMDLexicalBlockFile(const MDLexicalBlockFile *,
 987                                     const ValueEnumerator &, BitstreamWriter &,
 988                                     SmallVectorImpl<uint64_t> &, unsigned) {
 989   llvm_unreachable("write not implemented");
 990 }
 991 static void WriteMDNamespace(const MDNamespace *, const ValueEnumerator &,
 992                              BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 993                              unsigned) {
 994   llvm_unreachable("write not implemented");
 995 }
 996 static void WriteMDTemplateTypeParameter(const MDTemplateTypeParameter *,
 997                                          const ValueEnumerator &,
 998                                          BitstreamWriter &,
 999                                          SmallVectorImpl<uint64_t> &,
1000                                          unsigned) {
1001   llvm_unreachable("write not implemented");
1002 }
1003 static void WriteMDTemplateValueParameter(const MDTemplateValueParameter *,
1004                                           const ValueEnumerator &,
1005                                           BitstreamWriter &,
1006                                           SmallVectorImpl<uint64_t> &,
1007                                           unsigned) {
1008   llvm_unreachable("write not implemented");
1009 }
1010 static void WriteMDGlobalVariable(const MDGlobalVariable *,
1011                                   const ValueEnumerator &, BitstreamWriter &,
1012                                   SmallVectorImpl<uint64_t> &, unsigned) {
1013   llvm_unreachable("write not implemented");
1014 }
1015 static void WriteMDLocalVariable(const MDLocalVariable *,
1016                                  const ValueEnumerator &, BitstreamWriter &,
1017                                  SmallVectorImpl<uint64_t> &, unsigned) {
1018   llvm_unreachable("write not implemented");
1019 }
1020 static void WriteMDExpression(const MDExpression *, const ValueEnumerator &,
1021                               BitstreamWriter &, SmallVectorImpl<uint64_t> &,
1022                               unsigned) {
1023   llvm_unreachable("write not implemented");
1024 }
1025 static void WriteMDObjCProperty(const MDObjCProperty *, const ValueEnumerator &,
1026                                 BitstreamWriter &, SmallVectorImpl<uint64_t> &,
1027                                 unsigned) {
1028   llvm_unreachable("write not implemented");
1029 }
1030 static void WriteMDImportedEntity(const MDImportedEntity *,
1031                                   const ValueEnumerator &, BitstreamWriter &,
1032                                   SmallVectorImpl<uint64_t> &, unsigned) {
1033   llvm_unreachable("write not implemented");
1034 }
1035
1036 static void WriteModuleMetadata(const Module *M,
1037                                 const ValueEnumerator &VE,
1038                                 BitstreamWriter &Stream) {
1039   const auto &MDs = VE.getMDs();
1040   if (MDs.empty() && M->named_metadata_empty())
1041     return;
1042
1043   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1044
1045   unsigned MDSAbbrev = 0;
1046   if (VE.hasMDString()) {
1047     // Abbrev for METADATA_STRING.
1048     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1049     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
1050     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1051     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1052     MDSAbbrev = Stream.EmitAbbrev(Abbv);
1053   }
1054
1055   // Initialize MDNode abbreviations.
1056 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1057 #include "llvm/IR/Metadata.def"
1058
1059   if (VE.hasMDLocation()) {
1060     // Abbrev for METADATA_LOCATION.
1061     //
1062     // Assume the column is usually under 128, and always output the inlined-at
1063     // location (it's never more expensive than building an array size 1).
1064     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1065     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1066     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1067     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1068     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1069     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1070     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1071     MDLocationAbbrev = Stream.EmitAbbrev(Abbv);
1072   }
1073
1074   if (VE.hasGenericDebugNode()) {
1075     // Abbrev for METADATA_GENERIC_DEBUG.
1076     //
1077     // Assume the column is usually under 128, and always output the inlined-at
1078     // location (it's never more expensive than building an array size 1).
1079     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1080     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1081     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1082     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1083     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1084     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1085     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1086     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1087     GenericDebugNodeAbbrev = Stream.EmitAbbrev(Abbv);
1088   }
1089
1090   unsigned NameAbbrev = 0;
1091   if (!M->named_metadata_empty()) {
1092     // Abbrev for METADATA_NAME.
1093     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1094     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1095     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1096     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1097     NameAbbrev = Stream.EmitAbbrev(Abbv);
1098   }
1099
1100   SmallVector<uint64_t, 64> Record;
1101   for (const Metadata *MD : MDs) {
1102     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1103       switch (N->getMetadataID()) {
1104       default:
1105         llvm_unreachable("Invalid MDNode subclass");
1106 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1107   case Metadata::CLASS##Kind:                                                  \
1108     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1109     continue;
1110 #include "llvm/IR/Metadata.def"
1111       }
1112     }
1113     if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MD)) {
1114       WriteValueAsMetadata(MDC, VE, Stream, Record);
1115       continue;
1116     }
1117     const MDString *MDS = cast<MDString>(MD);
1118     // Code: [strchar x N]
1119     Record.append(MDS->bytes_begin(), MDS->bytes_end());
1120
1121     // Emit the finished record.
1122     Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
1123     Record.clear();
1124   }
1125
1126   // Write named metadata.
1127   for (const NamedMDNode &NMD : M->named_metadata()) {
1128     // Write name.
1129     StringRef Str = NMD.getName();
1130     Record.append(Str.bytes_begin(), Str.bytes_end());
1131     Stream.EmitRecord(bitc::METADATA_NAME, Record, NameAbbrev);
1132     Record.clear();
1133
1134     // Write named metadata operands.
1135     for (const MDNode *N : NMD.operands())
1136       Record.push_back(VE.getMetadataID(N));
1137     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1138     Record.clear();
1139   }
1140
1141   Stream.ExitBlock();
1142 }
1143
1144 static void WriteFunctionLocalMetadata(const Function &F,
1145                                        const ValueEnumerator &VE,
1146                                        BitstreamWriter &Stream) {
1147   bool StartedMetadataBlock = false;
1148   SmallVector<uint64_t, 64> Record;
1149   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1150       VE.getFunctionLocalMDs();
1151   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1152     assert(MDs[i] && "Expected valid function-local metadata");
1153     if (!StartedMetadataBlock) {
1154       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1155       StartedMetadataBlock = true;
1156     }
1157     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1158   }
1159
1160   if (StartedMetadataBlock)
1161     Stream.ExitBlock();
1162 }
1163
1164 static void WriteMetadataAttachment(const Function &F,
1165                                     const ValueEnumerator &VE,
1166                                     BitstreamWriter &Stream) {
1167   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1168
1169   SmallVector<uint64_t, 64> Record;
1170
1171   // Write metadata attachments
1172   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1173   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1174
1175   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1176     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1177          I != E; ++I) {
1178       MDs.clear();
1179       I->getAllMetadataOtherThanDebugLoc(MDs);
1180
1181       // If no metadata, ignore instruction.
1182       if (MDs.empty()) continue;
1183
1184       Record.push_back(VE.getInstructionID(I));
1185
1186       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1187         Record.push_back(MDs[i].first);
1188         Record.push_back(VE.getMetadataID(MDs[i].second));
1189       }
1190       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1191       Record.clear();
1192     }
1193
1194   Stream.ExitBlock();
1195 }
1196
1197 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1198   SmallVector<uint64_t, 64> Record;
1199
1200   // Write metadata kinds
1201   // METADATA_KIND - [n x [id, name]]
1202   SmallVector<StringRef, 8> Names;
1203   M->getMDKindNames(Names);
1204
1205   if (Names.empty()) return;
1206
1207   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1208
1209   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1210     Record.push_back(MDKindID);
1211     StringRef KName = Names[MDKindID];
1212     Record.append(KName.begin(), KName.end());
1213
1214     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1215     Record.clear();
1216   }
1217
1218   Stream.ExitBlock();
1219 }
1220
1221 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1222   if ((int64_t)V >= 0)
1223     Vals.push_back(V << 1);
1224   else
1225     Vals.push_back((-V << 1) | 1);
1226 }
1227
1228 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1229                            const ValueEnumerator &VE,
1230                            BitstreamWriter &Stream, bool isGlobal) {
1231   if (FirstVal == LastVal) return;
1232
1233   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1234
1235   unsigned AggregateAbbrev = 0;
1236   unsigned String8Abbrev = 0;
1237   unsigned CString7Abbrev = 0;
1238   unsigned CString6Abbrev = 0;
1239   // If this is a constant pool for the module, emit module-specific abbrevs.
1240   if (isGlobal) {
1241     // Abbrev for CST_CODE_AGGREGATE.
1242     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1243     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1244     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1245     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1246     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1247
1248     // Abbrev for CST_CODE_STRING.
1249     Abbv = new BitCodeAbbrev();
1250     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1251     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1252     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1253     String8Abbrev = Stream.EmitAbbrev(Abbv);
1254     // Abbrev for CST_CODE_CSTRING.
1255     Abbv = new BitCodeAbbrev();
1256     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1257     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1258     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1259     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1260     // Abbrev for CST_CODE_CSTRING.
1261     Abbv = new BitCodeAbbrev();
1262     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1263     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1264     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1265     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1266   }
1267
1268   SmallVector<uint64_t, 64> Record;
1269
1270   const ValueEnumerator::ValueList &Vals = VE.getValues();
1271   Type *LastTy = nullptr;
1272   for (unsigned i = FirstVal; i != LastVal; ++i) {
1273     const Value *V = Vals[i].first;
1274     // If we need to switch types, do so now.
1275     if (V->getType() != LastTy) {
1276       LastTy = V->getType();
1277       Record.push_back(VE.getTypeID(LastTy));
1278       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1279                         CONSTANTS_SETTYPE_ABBREV);
1280       Record.clear();
1281     }
1282
1283     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1284       Record.push_back(unsigned(IA->hasSideEffects()) |
1285                        unsigned(IA->isAlignStack()) << 1 |
1286                        unsigned(IA->getDialect()&1) << 2);
1287
1288       // Add the asm string.
1289       const std::string &AsmStr = IA->getAsmString();
1290       Record.push_back(AsmStr.size());
1291       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
1292         Record.push_back(AsmStr[i]);
1293
1294       // Add the constraint string.
1295       const std::string &ConstraintStr = IA->getConstraintString();
1296       Record.push_back(ConstraintStr.size());
1297       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
1298         Record.push_back(ConstraintStr[i]);
1299       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1300       Record.clear();
1301       continue;
1302     }
1303     const Constant *C = cast<Constant>(V);
1304     unsigned Code = -1U;
1305     unsigned AbbrevToUse = 0;
1306     if (C->isNullValue()) {
1307       Code = bitc::CST_CODE_NULL;
1308     } else if (isa<UndefValue>(C)) {
1309       Code = bitc::CST_CODE_UNDEF;
1310     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1311       if (IV->getBitWidth() <= 64) {
1312         uint64_t V = IV->getSExtValue();
1313         emitSignedInt64(Record, V);
1314         Code = bitc::CST_CODE_INTEGER;
1315         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1316       } else {                             // Wide integers, > 64 bits in size.
1317         // We have an arbitrary precision integer value to write whose
1318         // bit width is > 64. However, in canonical unsigned integer
1319         // format it is likely that the high bits are going to be zero.
1320         // So, we only write the number of active words.
1321         unsigned NWords = IV->getValue().getActiveWords();
1322         const uint64_t *RawWords = IV->getValue().getRawData();
1323         for (unsigned i = 0; i != NWords; ++i) {
1324           emitSignedInt64(Record, RawWords[i]);
1325         }
1326         Code = bitc::CST_CODE_WIDE_INTEGER;
1327       }
1328     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1329       Code = bitc::CST_CODE_FLOAT;
1330       Type *Ty = CFP->getType();
1331       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1332         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1333       } else if (Ty->isX86_FP80Ty()) {
1334         // api needed to prevent premature destruction
1335         // bits are not in the same order as a normal i80 APInt, compensate.
1336         APInt api = CFP->getValueAPF().bitcastToAPInt();
1337         const uint64_t *p = api.getRawData();
1338         Record.push_back((p[1] << 48) | (p[0] >> 16));
1339         Record.push_back(p[0] & 0xffffLL);
1340       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1341         APInt api = CFP->getValueAPF().bitcastToAPInt();
1342         const uint64_t *p = api.getRawData();
1343         Record.push_back(p[0]);
1344         Record.push_back(p[1]);
1345       } else {
1346         assert (0 && "Unknown FP type!");
1347       }
1348     } else if (isa<ConstantDataSequential>(C) &&
1349                cast<ConstantDataSequential>(C)->isString()) {
1350       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1351       // Emit constant strings specially.
1352       unsigned NumElts = Str->getNumElements();
1353       // If this is a null-terminated string, use the denser CSTRING encoding.
1354       if (Str->isCString()) {
1355         Code = bitc::CST_CODE_CSTRING;
1356         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1357       } else {
1358         Code = bitc::CST_CODE_STRING;
1359         AbbrevToUse = String8Abbrev;
1360       }
1361       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1362       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1363       for (unsigned i = 0; i != NumElts; ++i) {
1364         unsigned char V = Str->getElementAsInteger(i);
1365         Record.push_back(V);
1366         isCStr7 &= (V & 128) == 0;
1367         if (isCStrChar6)
1368           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1369       }
1370
1371       if (isCStrChar6)
1372         AbbrevToUse = CString6Abbrev;
1373       else if (isCStr7)
1374         AbbrevToUse = CString7Abbrev;
1375     } else if (const ConstantDataSequential *CDS =
1376                   dyn_cast<ConstantDataSequential>(C)) {
1377       Code = bitc::CST_CODE_DATA;
1378       Type *EltTy = CDS->getType()->getElementType();
1379       if (isa<IntegerType>(EltTy)) {
1380         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1381           Record.push_back(CDS->getElementAsInteger(i));
1382       } else if (EltTy->isFloatTy()) {
1383         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1384           union { float F; uint32_t I; };
1385           F = CDS->getElementAsFloat(i);
1386           Record.push_back(I);
1387         }
1388       } else {
1389         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1390         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1391           union { double F; uint64_t I; };
1392           F = CDS->getElementAsDouble(i);
1393           Record.push_back(I);
1394         }
1395       }
1396     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1397                isa<ConstantVector>(C)) {
1398       Code = bitc::CST_CODE_AGGREGATE;
1399       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1400         Record.push_back(VE.getValueID(C->getOperand(i)));
1401       AbbrevToUse = AggregateAbbrev;
1402     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1403       switch (CE->getOpcode()) {
1404       default:
1405         if (Instruction::isCast(CE->getOpcode())) {
1406           Code = bitc::CST_CODE_CE_CAST;
1407           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1408           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1409           Record.push_back(VE.getValueID(C->getOperand(0)));
1410           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1411         } else {
1412           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1413           Code = bitc::CST_CODE_CE_BINOP;
1414           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1415           Record.push_back(VE.getValueID(C->getOperand(0)));
1416           Record.push_back(VE.getValueID(C->getOperand(1)));
1417           uint64_t Flags = GetOptimizationFlags(CE);
1418           if (Flags != 0)
1419             Record.push_back(Flags);
1420         }
1421         break;
1422       case Instruction::GetElementPtr:
1423         Code = bitc::CST_CODE_CE_GEP;
1424         if (cast<GEPOperator>(C)->isInBounds())
1425           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1426         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1427           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1428           Record.push_back(VE.getValueID(C->getOperand(i)));
1429         }
1430         break;
1431       case Instruction::Select:
1432         Code = bitc::CST_CODE_CE_SELECT;
1433         Record.push_back(VE.getValueID(C->getOperand(0)));
1434         Record.push_back(VE.getValueID(C->getOperand(1)));
1435         Record.push_back(VE.getValueID(C->getOperand(2)));
1436         break;
1437       case Instruction::ExtractElement:
1438         Code = bitc::CST_CODE_CE_EXTRACTELT;
1439         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1440         Record.push_back(VE.getValueID(C->getOperand(0)));
1441         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1442         Record.push_back(VE.getValueID(C->getOperand(1)));
1443         break;
1444       case Instruction::InsertElement:
1445         Code = bitc::CST_CODE_CE_INSERTELT;
1446         Record.push_back(VE.getValueID(C->getOperand(0)));
1447         Record.push_back(VE.getValueID(C->getOperand(1)));
1448         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1449         Record.push_back(VE.getValueID(C->getOperand(2)));
1450         break;
1451       case Instruction::ShuffleVector:
1452         // If the return type and argument types are the same, this is a
1453         // standard shufflevector instruction.  If the types are different,
1454         // then the shuffle is widening or truncating the input vectors, and
1455         // the argument type must also be encoded.
1456         if (C->getType() == C->getOperand(0)->getType()) {
1457           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1458         } else {
1459           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1460           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1461         }
1462         Record.push_back(VE.getValueID(C->getOperand(0)));
1463         Record.push_back(VE.getValueID(C->getOperand(1)));
1464         Record.push_back(VE.getValueID(C->getOperand(2)));
1465         break;
1466       case Instruction::ICmp:
1467       case Instruction::FCmp:
1468         Code = bitc::CST_CODE_CE_CMP;
1469         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1470         Record.push_back(VE.getValueID(C->getOperand(0)));
1471         Record.push_back(VE.getValueID(C->getOperand(1)));
1472         Record.push_back(CE->getPredicate());
1473         break;
1474       }
1475     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1476       Code = bitc::CST_CODE_BLOCKADDRESS;
1477       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1478       Record.push_back(VE.getValueID(BA->getFunction()));
1479       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1480     } else {
1481 #ifndef NDEBUG
1482       C->dump();
1483 #endif
1484       llvm_unreachable("Unknown constant!");
1485     }
1486     Stream.EmitRecord(Code, Record, AbbrevToUse);
1487     Record.clear();
1488   }
1489
1490   Stream.ExitBlock();
1491 }
1492
1493 static void WriteModuleConstants(const ValueEnumerator &VE,
1494                                  BitstreamWriter &Stream) {
1495   const ValueEnumerator::ValueList &Vals = VE.getValues();
1496
1497   // Find the first constant to emit, which is the first non-globalvalue value.
1498   // We know globalvalues have been emitted by WriteModuleInfo.
1499   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1500     if (!isa<GlobalValue>(Vals[i].first)) {
1501       WriteConstants(i, Vals.size(), VE, Stream, true);
1502       return;
1503     }
1504   }
1505 }
1506
1507 /// PushValueAndType - The file has to encode both the value and type id for
1508 /// many values, because we need to know what type to create for forward
1509 /// references.  However, most operands are not forward references, so this type
1510 /// field is not needed.
1511 ///
1512 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1513 /// instruction ID, then it is a forward reference, and it also includes the
1514 /// type ID.  The value ID that is written is encoded relative to the InstID.
1515 static bool PushValueAndType(const Value *V, unsigned InstID,
1516                              SmallVectorImpl<unsigned> &Vals,
1517                              ValueEnumerator &VE) {
1518   unsigned ValID = VE.getValueID(V);
1519   // Make encoding relative to the InstID.
1520   Vals.push_back(InstID - ValID);
1521   if (ValID >= InstID) {
1522     Vals.push_back(VE.getTypeID(V->getType()));
1523     return true;
1524   }
1525   return false;
1526 }
1527
1528 /// pushValue - Like PushValueAndType, but where the type of the value is
1529 /// omitted (perhaps it was already encoded in an earlier operand).
1530 static void pushValue(const Value *V, unsigned InstID,
1531                       SmallVectorImpl<unsigned> &Vals,
1532                       ValueEnumerator &VE) {
1533   unsigned ValID = VE.getValueID(V);
1534   Vals.push_back(InstID - ValID);
1535 }
1536
1537 static void pushValueSigned(const Value *V, unsigned InstID,
1538                             SmallVectorImpl<uint64_t> &Vals,
1539                             ValueEnumerator &VE) {
1540   unsigned ValID = VE.getValueID(V);
1541   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1542   emitSignedInt64(Vals, diff);
1543 }
1544
1545 /// WriteInstruction - Emit an instruction to the specified stream.
1546 static void WriteInstruction(const Instruction &I, unsigned InstID,
1547                              ValueEnumerator &VE, BitstreamWriter &Stream,
1548                              SmallVectorImpl<unsigned> &Vals) {
1549   unsigned Code = 0;
1550   unsigned AbbrevToUse = 0;
1551   VE.setInstructionID(&I);
1552   switch (I.getOpcode()) {
1553   default:
1554     if (Instruction::isCast(I.getOpcode())) {
1555       Code = bitc::FUNC_CODE_INST_CAST;
1556       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1557         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1558       Vals.push_back(VE.getTypeID(I.getType()));
1559       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1560     } else {
1561       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1562       Code = bitc::FUNC_CODE_INST_BINOP;
1563       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1564         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1565       pushValue(I.getOperand(1), InstID, Vals, VE);
1566       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1567       uint64_t Flags = GetOptimizationFlags(&I);
1568       if (Flags != 0) {
1569         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1570           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1571         Vals.push_back(Flags);
1572       }
1573     }
1574     break;
1575
1576   case Instruction::GetElementPtr:
1577     Code = bitc::FUNC_CODE_INST_GEP;
1578     if (cast<GEPOperator>(&I)->isInBounds())
1579       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1580     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1581       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1582     break;
1583   case Instruction::ExtractValue: {
1584     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1585     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1586     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1587     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1588       Vals.push_back(*i);
1589     break;
1590   }
1591   case Instruction::InsertValue: {
1592     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1593     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1594     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1595     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1596     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1597       Vals.push_back(*i);
1598     break;
1599   }
1600   case Instruction::Select:
1601     Code = bitc::FUNC_CODE_INST_VSELECT;
1602     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1603     pushValue(I.getOperand(2), InstID, Vals, VE);
1604     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1605     break;
1606   case Instruction::ExtractElement:
1607     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1608     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1609     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1610     break;
1611   case Instruction::InsertElement:
1612     Code = bitc::FUNC_CODE_INST_INSERTELT;
1613     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1614     pushValue(I.getOperand(1), InstID, Vals, VE);
1615     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1616     break;
1617   case Instruction::ShuffleVector:
1618     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1619     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1620     pushValue(I.getOperand(1), InstID, Vals, VE);
1621     pushValue(I.getOperand(2), InstID, Vals, VE);
1622     break;
1623   case Instruction::ICmp:
1624   case Instruction::FCmp:
1625     // compare returning Int1Ty or vector of Int1Ty
1626     Code = bitc::FUNC_CODE_INST_CMP2;
1627     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1628     pushValue(I.getOperand(1), InstID, Vals, VE);
1629     Vals.push_back(cast<CmpInst>(I).getPredicate());
1630     break;
1631
1632   case Instruction::Ret:
1633     {
1634       Code = bitc::FUNC_CODE_INST_RET;
1635       unsigned NumOperands = I.getNumOperands();
1636       if (NumOperands == 0)
1637         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1638       else if (NumOperands == 1) {
1639         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1640           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1641       } else {
1642         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1643           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1644       }
1645     }
1646     break;
1647   case Instruction::Br:
1648     {
1649       Code = bitc::FUNC_CODE_INST_BR;
1650       const BranchInst &II = cast<BranchInst>(I);
1651       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1652       if (II.isConditional()) {
1653         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1654         pushValue(II.getCondition(), InstID, Vals, VE);
1655       }
1656     }
1657     break;
1658   case Instruction::Switch:
1659     {
1660       Code = bitc::FUNC_CODE_INST_SWITCH;
1661       const SwitchInst &SI = cast<SwitchInst>(I);
1662       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1663       pushValue(SI.getCondition(), InstID, Vals, VE);
1664       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1665       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1666            i != e; ++i) {
1667         Vals.push_back(VE.getValueID(i.getCaseValue()));
1668         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1669       }
1670     }
1671     break;
1672   case Instruction::IndirectBr:
1673     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1674     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1675     // Encode the address operand as relative, but not the basic blocks.
1676     pushValue(I.getOperand(0), InstID, Vals, VE);
1677     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1678       Vals.push_back(VE.getValueID(I.getOperand(i)));
1679     break;
1680
1681   case Instruction::Invoke: {
1682     const InvokeInst *II = cast<InvokeInst>(&I);
1683     const Value *Callee(II->getCalledValue());
1684     PointerType *PTy = cast<PointerType>(Callee->getType());
1685     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1686     Code = bitc::FUNC_CODE_INST_INVOKE;
1687
1688     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1689     Vals.push_back(II->getCallingConv());
1690     Vals.push_back(VE.getValueID(II->getNormalDest()));
1691     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1692     PushValueAndType(Callee, InstID, Vals, VE);
1693
1694     // Emit value #'s for the fixed parameters.
1695     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1696       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1697
1698     // Emit type/value pairs for varargs params.
1699     if (FTy->isVarArg()) {
1700       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1701            i != e; ++i)
1702         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1703     }
1704     break;
1705   }
1706   case Instruction::Resume:
1707     Code = bitc::FUNC_CODE_INST_RESUME;
1708     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1709     break;
1710   case Instruction::Unreachable:
1711     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1712     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1713     break;
1714
1715   case Instruction::PHI: {
1716     const PHINode &PN = cast<PHINode>(I);
1717     Code = bitc::FUNC_CODE_INST_PHI;
1718     // With the newer instruction encoding, forward references could give
1719     // negative valued IDs.  This is most common for PHIs, so we use
1720     // signed VBRs.
1721     SmallVector<uint64_t, 128> Vals64;
1722     Vals64.push_back(VE.getTypeID(PN.getType()));
1723     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1724       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1725       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1726     }
1727     // Emit a Vals64 vector and exit.
1728     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1729     Vals64.clear();
1730     return;
1731   }
1732
1733   case Instruction::LandingPad: {
1734     const LandingPadInst &LP = cast<LandingPadInst>(I);
1735     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1736     Vals.push_back(VE.getTypeID(LP.getType()));
1737     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1738     Vals.push_back(LP.isCleanup());
1739     Vals.push_back(LP.getNumClauses());
1740     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1741       if (LP.isCatch(I))
1742         Vals.push_back(LandingPadInst::Catch);
1743       else
1744         Vals.push_back(LandingPadInst::Filter);
1745       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1746     }
1747     break;
1748   }
1749
1750   case Instruction::Alloca: {
1751     Code = bitc::FUNC_CODE_INST_ALLOCA;
1752     Vals.push_back(VE.getTypeID(I.getType()));
1753     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1754     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1755     const AllocaInst &AI = cast<AllocaInst>(I);
1756     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
1757     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
1758            "not enough bits for maximum alignment");
1759     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
1760     AlignRecord |= AI.isUsedWithInAlloca() << 5;
1761     Vals.push_back(AlignRecord);
1762     break;
1763   }
1764
1765   case Instruction::Load:
1766     if (cast<LoadInst>(I).isAtomic()) {
1767       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1768       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1769     } else {
1770       Code = bitc::FUNC_CODE_INST_LOAD;
1771       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1772         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1773     }
1774     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1775     Vals.push_back(cast<LoadInst>(I).isVolatile());
1776     if (cast<LoadInst>(I).isAtomic()) {
1777       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1778       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1779     }
1780     break;
1781   case Instruction::Store:
1782     if (cast<StoreInst>(I).isAtomic())
1783       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1784     else
1785       Code = bitc::FUNC_CODE_INST_STORE;
1786     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1787     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1788     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1789     Vals.push_back(cast<StoreInst>(I).isVolatile());
1790     if (cast<StoreInst>(I).isAtomic()) {
1791       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1792       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1793     }
1794     break;
1795   case Instruction::AtomicCmpXchg:
1796     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1797     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1798     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1799     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1800     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1801     Vals.push_back(GetEncodedOrdering(
1802                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
1803     Vals.push_back(GetEncodedSynchScope(
1804                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1805     Vals.push_back(GetEncodedOrdering(
1806                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
1807     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
1808     break;
1809   case Instruction::AtomicRMW:
1810     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1811     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1812     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1813     Vals.push_back(GetEncodedRMWOperation(
1814                      cast<AtomicRMWInst>(I).getOperation()));
1815     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1816     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1817     Vals.push_back(GetEncodedSynchScope(
1818                      cast<AtomicRMWInst>(I).getSynchScope()));
1819     break;
1820   case Instruction::Fence:
1821     Code = bitc::FUNC_CODE_INST_FENCE;
1822     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1823     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1824     break;
1825   case Instruction::Call: {
1826     const CallInst &CI = cast<CallInst>(I);
1827     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1828     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1829
1830     Code = bitc::FUNC_CODE_INST_CALL;
1831
1832     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1833     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()) |
1834                    unsigned(CI.isMustTailCall()) << 14);
1835     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1836
1837     // Emit value #'s for the fixed parameters.
1838     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1839       // Check for labels (can happen with asm labels).
1840       if (FTy->getParamType(i)->isLabelTy())
1841         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1842       else
1843         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1844     }
1845
1846     // Emit type/value pairs for varargs params.
1847     if (FTy->isVarArg()) {
1848       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1849            i != e; ++i)
1850         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1851     }
1852     break;
1853   }
1854   case Instruction::VAArg:
1855     Code = bitc::FUNC_CODE_INST_VAARG;
1856     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1857     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1858     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1859     break;
1860   }
1861
1862   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1863   Vals.clear();
1864 }
1865
1866 // Emit names for globals/functions etc.
1867 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1868                                   const ValueEnumerator &VE,
1869                                   BitstreamWriter &Stream) {
1870   if (VST.empty()) return;
1871   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1872
1873   // FIXME: Set up the abbrev, we know how many values there are!
1874   // FIXME: We know if the type names can use 7-bit ascii.
1875   SmallVector<unsigned, 64> NameVals;
1876
1877   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1878        SI != SE; ++SI) {
1879
1880     const ValueName &Name = *SI;
1881
1882     // Figure out the encoding to use for the name.
1883     bool is7Bit = true;
1884     bool isChar6 = true;
1885     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1886          C != E; ++C) {
1887       if (isChar6)
1888         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1889       if ((unsigned char)*C & 128) {
1890         is7Bit = false;
1891         break;  // don't bother scanning the rest.
1892       }
1893     }
1894
1895     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1896
1897     // VST_ENTRY:   [valueid, namechar x N]
1898     // VST_BBENTRY: [bbid, namechar x N]
1899     unsigned Code;
1900     if (isa<BasicBlock>(SI->getValue())) {
1901       Code = bitc::VST_CODE_BBENTRY;
1902       if (isChar6)
1903         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1904     } else {
1905       Code = bitc::VST_CODE_ENTRY;
1906       if (isChar6)
1907         AbbrevToUse = VST_ENTRY_6_ABBREV;
1908       else if (is7Bit)
1909         AbbrevToUse = VST_ENTRY_7_ABBREV;
1910     }
1911
1912     NameVals.push_back(VE.getValueID(SI->getValue()));
1913     for (const char *P = Name.getKeyData(),
1914          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1915       NameVals.push_back((unsigned char)*P);
1916
1917     // Emit the finished record.
1918     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1919     NameVals.clear();
1920   }
1921   Stream.ExitBlock();
1922 }
1923
1924 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
1925                          BitstreamWriter &Stream) {
1926   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
1927   unsigned Code;
1928   if (isa<BasicBlock>(Order.V))
1929     Code = bitc::USELIST_CODE_BB;
1930   else
1931     Code = bitc::USELIST_CODE_DEFAULT;
1932
1933   SmallVector<uint64_t, 64> Record;
1934   for (unsigned I : Order.Shuffle)
1935     Record.push_back(I);
1936   Record.push_back(VE.getValueID(Order.V));
1937   Stream.EmitRecord(Code, Record);
1938 }
1939
1940 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
1941                               BitstreamWriter &Stream) {
1942   auto hasMore = [&]() {
1943     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
1944   };
1945   if (!hasMore())
1946     // Nothing to do.
1947     return;
1948
1949   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1950   while (hasMore()) {
1951     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
1952     VE.UseListOrders.pop_back();
1953   }
1954   Stream.ExitBlock();
1955 }
1956
1957 /// WriteFunction - Emit a function body to the module stream.
1958 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1959                           BitstreamWriter &Stream) {
1960   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1961   VE.incorporateFunction(F);
1962
1963   SmallVector<unsigned, 64> Vals;
1964
1965   // Emit the number of basic blocks, so the reader can create them ahead of
1966   // time.
1967   Vals.push_back(VE.getBasicBlocks().size());
1968   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1969   Vals.clear();
1970
1971   // If there are function-local constants, emit them now.
1972   unsigned CstStart, CstEnd;
1973   VE.getFunctionConstantRange(CstStart, CstEnd);
1974   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1975
1976   // If there is function-local metadata, emit it now.
1977   WriteFunctionLocalMetadata(F, VE, Stream);
1978
1979   // Keep a running idea of what the instruction ID is.
1980   unsigned InstID = CstEnd;
1981
1982   bool NeedsMetadataAttachment = false;
1983
1984   DebugLoc LastDL;
1985
1986   // Finally, emit all the instructions, in order.
1987   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1988     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1989          I != E; ++I) {
1990       WriteInstruction(*I, InstID, VE, Stream, Vals);
1991
1992       if (!I->getType()->isVoidTy())
1993         ++InstID;
1994
1995       // If the instruction has metadata, write a metadata attachment later.
1996       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1997
1998       // If the instruction has a debug location, emit it.
1999       DebugLoc DL = I->getDebugLoc();
2000       if (DL.isUnknown()) {
2001         // nothing todo.
2002       } else if (DL == LastDL) {
2003         // Just repeat the same debug loc as last time.
2004         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2005       } else {
2006         MDNode *Scope, *IA;
2007         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
2008         assert(Scope && "Expected valid scope");
2009
2010         Vals.push_back(DL.getLine());
2011         Vals.push_back(DL.getCol());
2012         Vals.push_back(VE.getMetadataOrNullID(Scope));
2013         Vals.push_back(VE.getMetadataOrNullID(IA));
2014         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2015         Vals.clear();
2016
2017         LastDL = DL;
2018       }
2019     }
2020
2021   // Emit names for all the instructions etc.
2022   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2023
2024   if (NeedsMetadataAttachment)
2025     WriteMetadataAttachment(F, VE, Stream);
2026   if (shouldPreserveBitcodeUseListOrder())
2027     WriteUseListBlock(&F, VE, Stream);
2028   VE.purgeFunction();
2029   Stream.ExitBlock();
2030 }
2031
2032 // Emit blockinfo, which defines the standard abbreviations etc.
2033 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2034   // We only want to emit block info records for blocks that have multiple
2035   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2036   // Other blocks can define their abbrevs inline.
2037   Stream.EnterBlockInfoBlock(2);
2038
2039   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
2040     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2041     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2042     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2043     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2044     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2045     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2046                                    Abbv) != VST_ENTRY_8_ABBREV)
2047       llvm_unreachable("Unexpected abbrev ordering!");
2048   }
2049
2050   { // 7-bit fixed width VST_ENTRY strings.
2051     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2052     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2053     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2054     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2055     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2056     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2057                                    Abbv) != VST_ENTRY_7_ABBREV)
2058       llvm_unreachable("Unexpected abbrev ordering!");
2059   }
2060   { // 6-bit char6 VST_ENTRY strings.
2061     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2062     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2063     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2064     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2065     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2066     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2067                                    Abbv) != VST_ENTRY_6_ABBREV)
2068       llvm_unreachable("Unexpected abbrev ordering!");
2069   }
2070   { // 6-bit char6 VST_BBENTRY strings.
2071     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2072     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2073     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2074     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2075     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2076     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2077                                    Abbv) != VST_BBENTRY_6_ABBREV)
2078       llvm_unreachable("Unexpected abbrev ordering!");
2079   }
2080
2081
2082
2083   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2084     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2085     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2086     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2087                               Log2_32_Ceil(VE.getTypes().size()+1)));
2088     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2089                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2090       llvm_unreachable("Unexpected abbrev ordering!");
2091   }
2092
2093   { // INTEGER abbrev for CONSTANTS_BLOCK.
2094     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2095     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2096     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2097     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2098                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2099       llvm_unreachable("Unexpected abbrev ordering!");
2100   }
2101
2102   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2103     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2104     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2105     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2106     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2107                               Log2_32_Ceil(VE.getTypes().size()+1)));
2108     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2109
2110     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2111                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2112       llvm_unreachable("Unexpected abbrev ordering!");
2113   }
2114   { // NULL abbrev for CONSTANTS_BLOCK.
2115     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2116     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2117     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2118                                    Abbv) != CONSTANTS_NULL_Abbrev)
2119       llvm_unreachable("Unexpected abbrev ordering!");
2120   }
2121
2122   // FIXME: This should only use space for first class types!
2123
2124   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2125     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2126     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2127     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2128     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2129     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2130     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2131                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2132       llvm_unreachable("Unexpected abbrev ordering!");
2133   }
2134   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2135     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2136     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2137     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2138     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2139     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2140     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2141                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2142       llvm_unreachable("Unexpected abbrev ordering!");
2143   }
2144   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2145     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2146     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2147     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2148     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2149     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2150     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2151     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2152                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2153       llvm_unreachable("Unexpected abbrev ordering!");
2154   }
2155   { // INST_CAST abbrev for FUNCTION_BLOCK.
2156     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2157     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2158     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2159     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2160                               Log2_32_Ceil(VE.getTypes().size()+1)));
2161     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2162     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2163                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2164       llvm_unreachable("Unexpected abbrev ordering!");
2165   }
2166
2167   { // INST_RET abbrev for FUNCTION_BLOCK.
2168     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2169     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2170     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2171                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2172       llvm_unreachable("Unexpected abbrev ordering!");
2173   }
2174   { // INST_RET abbrev for FUNCTION_BLOCK.
2175     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2176     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2178     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2179                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2180       llvm_unreachable("Unexpected abbrev ordering!");
2181   }
2182   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2183     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2184     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2185     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2186                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2187       llvm_unreachable("Unexpected abbrev ordering!");
2188   }
2189
2190   Stream.ExitBlock();
2191 }
2192
2193 /// WriteModule - Emit the specified module to the bitstream.
2194 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
2195   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
2196
2197   SmallVector<unsigned, 1> Vals;
2198   unsigned CurVersion = 1;
2199   Vals.push_back(CurVersion);
2200   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
2201
2202   // Analyze the module, enumerating globals, functions, etc.
2203   ValueEnumerator VE(*M);
2204
2205   // Emit blockinfo, which defines the standard abbreviations etc.
2206   WriteBlockInfo(VE, Stream);
2207
2208   // Emit information about attribute groups.
2209   WriteAttributeGroupTable(VE, Stream);
2210
2211   // Emit information about parameter attributes.
2212   WriteAttributeTable(VE, Stream);
2213
2214   // Emit information describing all of the types in the module.
2215   WriteTypeTable(VE, Stream);
2216
2217   writeComdats(VE, Stream);
2218
2219   // Emit top-level description of module, including target triple, inline asm,
2220   // descriptors for global variables, and function prototype info.
2221   WriteModuleInfo(M, VE, Stream);
2222
2223   // Emit constants.
2224   WriteModuleConstants(VE, Stream);
2225
2226   // Emit metadata.
2227   WriteModuleMetadata(M, VE, Stream);
2228
2229   // Emit metadata.
2230   WriteModuleMetadataStore(M, Stream);
2231
2232   // Emit names for globals/functions etc.
2233   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
2234
2235   // Emit module-level use-lists.
2236   if (shouldPreserveBitcodeUseListOrder())
2237     WriteUseListBlock(nullptr, VE, Stream);
2238
2239   // Emit function bodies.
2240   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
2241     if (!F->isDeclaration())
2242       WriteFunction(*F, VE, Stream);
2243
2244   Stream.ExitBlock();
2245 }
2246
2247 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
2248 /// header and trailer to make it compatible with the system archiver.  To do
2249 /// this we emit the following header, and then emit a trailer that pads the
2250 /// file out to be a multiple of 16 bytes.
2251 ///
2252 /// struct bc_header {
2253 ///   uint32_t Magic;         // 0x0B17C0DE
2254 ///   uint32_t Version;       // Version, currently always 0.
2255 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
2256 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
2257 ///   uint32_t CPUType;       // CPU specifier.
2258 ///   ... potentially more later ...
2259 /// };
2260 enum {
2261   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
2262   DarwinBCHeaderSize = 5*4
2263 };
2264
2265 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
2266                                uint32_t &Position) {
2267   Buffer[Position + 0] = (unsigned char) (Value >>  0);
2268   Buffer[Position + 1] = (unsigned char) (Value >>  8);
2269   Buffer[Position + 2] = (unsigned char) (Value >> 16);
2270   Buffer[Position + 3] = (unsigned char) (Value >> 24);
2271   Position += 4;
2272 }
2273
2274 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
2275                                          const Triple &TT) {
2276   unsigned CPUType = ~0U;
2277
2278   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
2279   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
2280   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
2281   // specific constants here because they are implicitly part of the Darwin ABI.
2282   enum {
2283     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
2284     DARWIN_CPU_TYPE_X86        = 7,
2285     DARWIN_CPU_TYPE_ARM        = 12,
2286     DARWIN_CPU_TYPE_POWERPC    = 18
2287   };
2288
2289   Triple::ArchType Arch = TT.getArch();
2290   if (Arch == Triple::x86_64)
2291     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
2292   else if (Arch == Triple::x86)
2293     CPUType = DARWIN_CPU_TYPE_X86;
2294   else if (Arch == Triple::ppc)
2295     CPUType = DARWIN_CPU_TYPE_POWERPC;
2296   else if (Arch == Triple::ppc64)
2297     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
2298   else if (Arch == Triple::arm || Arch == Triple::thumb)
2299     CPUType = DARWIN_CPU_TYPE_ARM;
2300
2301   // Traditional Bitcode starts after header.
2302   assert(Buffer.size() >= DarwinBCHeaderSize &&
2303          "Expected header size to be reserved");
2304   unsigned BCOffset = DarwinBCHeaderSize;
2305   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
2306
2307   // Write the magic and version.
2308   unsigned Position = 0;
2309   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
2310   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
2311   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
2312   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2313   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2314
2315   // If the file is not a multiple of 16 bytes, insert dummy padding.
2316   while (Buffer.size() & 15)
2317     Buffer.push_back(0);
2318 }
2319
2320 /// WriteBitcodeToFile - Write the specified module to the specified output
2321 /// stream.
2322 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2323   SmallVector<char, 0> Buffer;
2324   Buffer.reserve(256*1024);
2325
2326   // If this is darwin or another generic macho target, reserve space for the
2327   // header.
2328   Triple TT(M->getTargetTriple());
2329   if (TT.isOSDarwin())
2330     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2331
2332   // Emit the module into the buffer.
2333   {
2334     BitstreamWriter Stream(Buffer);
2335
2336     // Emit the file header.
2337     Stream.Emit((unsigned)'B', 8);
2338     Stream.Emit((unsigned)'C', 8);
2339     Stream.Emit(0x0, 4);
2340     Stream.Emit(0xC, 4);
2341     Stream.Emit(0xE, 4);
2342     Stream.Emit(0xD, 4);
2343
2344     // Emit the module.
2345     WriteModule(M, Stream);
2346   }
2347
2348   if (TT.isOSDarwin())
2349     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2350
2351   // Write the generated bitstream to "Out".
2352   Out.write((char*)&Buffer.front(), Buffer.size());
2353 }