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 *N,
 982                                const ValueEnumerator &VE,
 983                                BitstreamWriter &Stream,
 984                                SmallVectorImpl<uint64_t> &Record,
 985                                unsigned Abbrev) {
 986   Record.push_back(N->isDistinct());
 987   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
 988   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
 989   Record.push_back(N->getLine());
 990   Record.push_back(N->getColumn());
 991
 992   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
 993   Record.clear();
 994 }
 995
 996 static void WriteMDLexicalBlockFile(const MDLexicalBlockFile *N,
 997                                     const ValueEnumerator &VE,
 998                                     BitstreamWriter &Stream,
 999                                     SmallVectorImpl<uint64_t> &Record,
1000                                     unsigned Abbrev) {
1001   Record.push_back(N->isDistinct());
1002   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1003   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1004   Record.push_back(N->getDiscriminator());
1005
1006   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1007   Record.clear();
1008 }
1009
1010 static void WriteMDNamespace(const MDNamespace *N, const ValueEnumerator &VE,
1011                              BitstreamWriter &Stream,
1012                              SmallVectorImpl<uint64_t> &Record,
1013                              unsigned Abbrev) {
1014   Record.push_back(N->isDistinct());
1015   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1016   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1017   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1018   Record.push_back(N->getLine());
1019
1020   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1021   Record.clear();
1022 }
1023
1024 static void WriteMDTemplateTypeParameter(const MDTemplateTypeParameter *,
1025                                          const ValueEnumerator &,
1026                                          BitstreamWriter &,
1027                                          SmallVectorImpl<uint64_t> &,
1028                                          unsigned) {
1029   llvm_unreachable("write not implemented");
1030 }
1031 static void WriteMDTemplateValueParameter(const MDTemplateValueParameter *,
1032                                           const ValueEnumerator &,
1033                                           BitstreamWriter &,
1034                                           SmallVectorImpl<uint64_t> &,
1035                                           unsigned) {
1036   llvm_unreachable("write not implemented");
1037 }
1038 static void WriteMDGlobalVariable(const MDGlobalVariable *,
1039                                   const ValueEnumerator &, BitstreamWriter &,
1040                                   SmallVectorImpl<uint64_t> &, unsigned) {
1041   llvm_unreachable("write not implemented");
1042 }
1043 static void WriteMDLocalVariable(const MDLocalVariable *,
1044                                  const ValueEnumerator &, BitstreamWriter &,
1045                                  SmallVectorImpl<uint64_t> &, unsigned) {
1046   llvm_unreachable("write not implemented");
1047 }
1048 static void WriteMDExpression(const MDExpression *, const ValueEnumerator &,
1049                               BitstreamWriter &, SmallVectorImpl<uint64_t> &,
1050                               unsigned) {
1051   llvm_unreachable("write not implemented");
1052 }
1053 static void WriteMDObjCProperty(const MDObjCProperty *, const ValueEnumerator &,
1054                                 BitstreamWriter &, SmallVectorImpl<uint64_t> &,
1055                                 unsigned) {
1056   llvm_unreachable("write not implemented");
1057 }
1058 static void WriteMDImportedEntity(const MDImportedEntity *,
1059                                   const ValueEnumerator &, BitstreamWriter &,
1060                                   SmallVectorImpl<uint64_t> &, unsigned) {
1061   llvm_unreachable("write not implemented");
1062 }
1063
1064 static void WriteModuleMetadata(const Module *M,
1065                                 const ValueEnumerator &VE,
1066                                 BitstreamWriter &Stream) {
1067   const auto &MDs = VE.getMDs();
1068   if (MDs.empty() && M->named_metadata_empty())
1069     return;
1070
1071   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1072
1073   unsigned MDSAbbrev = 0;
1074   if (VE.hasMDString()) {
1075     // Abbrev for METADATA_STRING.
1076     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1077     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
1078     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1079     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1080     MDSAbbrev = Stream.EmitAbbrev(Abbv);
1081   }
1082
1083   // Initialize MDNode abbreviations.
1084 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1085 #include "llvm/IR/Metadata.def"
1086
1087   if (VE.hasMDLocation()) {
1088     // Abbrev for METADATA_LOCATION.
1089     //
1090     // Assume the column is usually under 128, and always output the inlined-at
1091     // location (it's never more expensive than building an array size 1).
1092     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1093     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1094     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1095     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1096     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1097     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1098     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1099     MDLocationAbbrev = Stream.EmitAbbrev(Abbv);
1100   }
1101
1102   if (VE.hasGenericDebugNode()) {
1103     // Abbrev for METADATA_GENERIC_DEBUG.
1104     //
1105     // Assume the column is usually under 128, and always output the inlined-at
1106     // location (it's never more expensive than building an array size 1).
1107     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1108     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1109     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1110     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1111     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1112     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1113     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1114     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1115     GenericDebugNodeAbbrev = Stream.EmitAbbrev(Abbv);
1116   }
1117
1118   unsigned NameAbbrev = 0;
1119   if (!M->named_metadata_empty()) {
1120     // Abbrev for METADATA_NAME.
1121     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1122     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1123     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1125     NameAbbrev = Stream.EmitAbbrev(Abbv);
1126   }
1127
1128   SmallVector<uint64_t, 64> Record;
1129   for (const Metadata *MD : MDs) {
1130     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1131       switch (N->getMetadataID()) {
1132       default:
1133         llvm_unreachable("Invalid MDNode subclass");
1134 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1135   case Metadata::CLASS##Kind:                                                  \
1136     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1137     continue;
1138 #include "llvm/IR/Metadata.def"
1139       }
1140     }
1141     if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MD)) {
1142       WriteValueAsMetadata(MDC, VE, Stream, Record);
1143       continue;
1144     }
1145     const MDString *MDS = cast<MDString>(MD);
1146     // Code: [strchar x N]
1147     Record.append(MDS->bytes_begin(), MDS->bytes_end());
1148
1149     // Emit the finished record.
1150     Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
1151     Record.clear();
1152   }
1153
1154   // Write named metadata.
1155   for (const NamedMDNode &NMD : M->named_metadata()) {
1156     // Write name.
1157     StringRef Str = NMD.getName();
1158     Record.append(Str.bytes_begin(), Str.bytes_end());
1159     Stream.EmitRecord(bitc::METADATA_NAME, Record, NameAbbrev);
1160     Record.clear();
1161
1162     // Write named metadata operands.
1163     for (const MDNode *N : NMD.operands())
1164       Record.push_back(VE.getMetadataID(N));
1165     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1166     Record.clear();
1167   }
1168
1169   Stream.ExitBlock();
1170 }
1171
1172 static void WriteFunctionLocalMetadata(const Function &F,
1173                                        const ValueEnumerator &VE,
1174                                        BitstreamWriter &Stream) {
1175   bool StartedMetadataBlock = false;
1176   SmallVector<uint64_t, 64> Record;
1177   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1178       VE.getFunctionLocalMDs();
1179   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1180     assert(MDs[i] && "Expected valid function-local metadata");
1181     if (!StartedMetadataBlock) {
1182       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1183       StartedMetadataBlock = true;
1184     }
1185     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1186   }
1187
1188   if (StartedMetadataBlock)
1189     Stream.ExitBlock();
1190 }
1191
1192 static void WriteMetadataAttachment(const Function &F,
1193                                     const ValueEnumerator &VE,
1194                                     BitstreamWriter &Stream) {
1195   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1196
1197   SmallVector<uint64_t, 64> Record;
1198
1199   // Write metadata attachments
1200   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1201   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1202
1203   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1204     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1205          I != E; ++I) {
1206       MDs.clear();
1207       I->getAllMetadataOtherThanDebugLoc(MDs);
1208
1209       // If no metadata, ignore instruction.
1210       if (MDs.empty()) continue;
1211
1212       Record.push_back(VE.getInstructionID(I));
1213
1214       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1215         Record.push_back(MDs[i].first);
1216         Record.push_back(VE.getMetadataID(MDs[i].second));
1217       }
1218       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1219       Record.clear();
1220     }
1221
1222   Stream.ExitBlock();
1223 }
1224
1225 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1226   SmallVector<uint64_t, 64> Record;
1227
1228   // Write metadata kinds
1229   // METADATA_KIND - [n x [id, name]]
1230   SmallVector<StringRef, 8> Names;
1231   M->getMDKindNames(Names);
1232
1233   if (Names.empty()) return;
1234
1235   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1236
1237   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1238     Record.push_back(MDKindID);
1239     StringRef KName = Names[MDKindID];
1240     Record.append(KName.begin(), KName.end());
1241
1242     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1243     Record.clear();
1244   }
1245
1246   Stream.ExitBlock();
1247 }
1248
1249 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1250   if ((int64_t)V >= 0)
1251     Vals.push_back(V << 1);
1252   else
1253     Vals.push_back((-V << 1) | 1);
1254 }
1255
1256 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1257                            const ValueEnumerator &VE,
1258                            BitstreamWriter &Stream, bool isGlobal) {
1259   if (FirstVal == LastVal) return;
1260
1261   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1262
1263   unsigned AggregateAbbrev = 0;
1264   unsigned String8Abbrev = 0;
1265   unsigned CString7Abbrev = 0;
1266   unsigned CString6Abbrev = 0;
1267   // If this is a constant pool for the module, emit module-specific abbrevs.
1268   if (isGlobal) {
1269     // Abbrev for CST_CODE_AGGREGATE.
1270     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1271     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1272     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1273     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1274     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1275
1276     // Abbrev for CST_CODE_STRING.
1277     Abbv = new BitCodeAbbrev();
1278     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1279     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1280     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1281     String8Abbrev = Stream.EmitAbbrev(Abbv);
1282     // Abbrev for CST_CODE_CSTRING.
1283     Abbv = new BitCodeAbbrev();
1284     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1285     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1286     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1287     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1288     // Abbrev for CST_CODE_CSTRING.
1289     Abbv = new BitCodeAbbrev();
1290     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1291     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1292     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1293     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1294   }
1295
1296   SmallVector<uint64_t, 64> Record;
1297
1298   const ValueEnumerator::ValueList &Vals = VE.getValues();
1299   Type *LastTy = nullptr;
1300   for (unsigned i = FirstVal; i != LastVal; ++i) {
1301     const Value *V = Vals[i].first;
1302     // If we need to switch types, do so now.
1303     if (V->getType() != LastTy) {
1304       LastTy = V->getType();
1305       Record.push_back(VE.getTypeID(LastTy));
1306       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1307                         CONSTANTS_SETTYPE_ABBREV);
1308       Record.clear();
1309     }
1310
1311     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1312       Record.push_back(unsigned(IA->hasSideEffects()) |
1313                        unsigned(IA->isAlignStack()) << 1 |
1314                        unsigned(IA->getDialect()&1) << 2);
1315
1316       // Add the asm string.
1317       const std::string &AsmStr = IA->getAsmString();
1318       Record.push_back(AsmStr.size());
1319       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
1320         Record.push_back(AsmStr[i]);
1321
1322       // Add the constraint string.
1323       const std::string &ConstraintStr = IA->getConstraintString();
1324       Record.push_back(ConstraintStr.size());
1325       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
1326         Record.push_back(ConstraintStr[i]);
1327       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1328       Record.clear();
1329       continue;
1330     }
1331     const Constant *C = cast<Constant>(V);
1332     unsigned Code = -1U;
1333     unsigned AbbrevToUse = 0;
1334     if (C->isNullValue()) {
1335       Code = bitc::CST_CODE_NULL;
1336     } else if (isa<UndefValue>(C)) {
1337       Code = bitc::CST_CODE_UNDEF;
1338     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1339       if (IV->getBitWidth() <= 64) {
1340         uint64_t V = IV->getSExtValue();
1341         emitSignedInt64(Record, V);
1342         Code = bitc::CST_CODE_INTEGER;
1343         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1344       } else {                             // Wide integers, > 64 bits in size.
1345         // We have an arbitrary precision integer value to write whose
1346         // bit width is > 64. However, in canonical unsigned integer
1347         // format it is likely that the high bits are going to be zero.
1348         // So, we only write the number of active words.
1349         unsigned NWords = IV->getValue().getActiveWords();
1350         const uint64_t *RawWords = IV->getValue().getRawData();
1351         for (unsigned i = 0; i != NWords; ++i) {
1352           emitSignedInt64(Record, RawWords[i]);
1353         }
1354         Code = bitc::CST_CODE_WIDE_INTEGER;
1355       }
1356     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1357       Code = bitc::CST_CODE_FLOAT;
1358       Type *Ty = CFP->getType();
1359       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1360         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1361       } else if (Ty->isX86_FP80Ty()) {
1362         // api needed to prevent premature destruction
1363         // bits are not in the same order as a normal i80 APInt, compensate.
1364         APInt api = CFP->getValueAPF().bitcastToAPInt();
1365         const uint64_t *p = api.getRawData();
1366         Record.push_back((p[1] << 48) | (p[0] >> 16));
1367         Record.push_back(p[0] & 0xffffLL);
1368       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1369         APInt api = CFP->getValueAPF().bitcastToAPInt();
1370         const uint64_t *p = api.getRawData();
1371         Record.push_back(p[0]);
1372         Record.push_back(p[1]);
1373       } else {
1374         assert (0 && "Unknown FP type!");
1375       }
1376     } else if (isa<ConstantDataSequential>(C) &&
1377                cast<ConstantDataSequential>(C)->isString()) {
1378       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1379       // Emit constant strings specially.
1380       unsigned NumElts = Str->getNumElements();
1381       // If this is a null-terminated string, use the denser CSTRING encoding.
1382       if (Str->isCString()) {
1383         Code = bitc::CST_CODE_CSTRING;
1384         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1385       } else {
1386         Code = bitc::CST_CODE_STRING;
1387         AbbrevToUse = String8Abbrev;
1388       }
1389       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1390       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1391       for (unsigned i = 0; i != NumElts; ++i) {
1392         unsigned char V = Str->getElementAsInteger(i);
1393         Record.push_back(V);
1394         isCStr7 &= (V & 128) == 0;
1395         if (isCStrChar6)
1396           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1397       }
1398
1399       if (isCStrChar6)
1400         AbbrevToUse = CString6Abbrev;
1401       else if (isCStr7)
1402         AbbrevToUse = CString7Abbrev;
1403     } else if (const ConstantDataSequential *CDS =
1404                   dyn_cast<ConstantDataSequential>(C)) {
1405       Code = bitc::CST_CODE_DATA;
1406       Type *EltTy = CDS->getType()->getElementType();
1407       if (isa<IntegerType>(EltTy)) {
1408         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1409           Record.push_back(CDS->getElementAsInteger(i));
1410       } else if (EltTy->isFloatTy()) {
1411         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1412           union { float F; uint32_t I; };
1413           F = CDS->getElementAsFloat(i);
1414           Record.push_back(I);
1415         }
1416       } else {
1417         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1418         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1419           union { double F; uint64_t I; };
1420           F = CDS->getElementAsDouble(i);
1421           Record.push_back(I);
1422         }
1423       }
1424     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1425                isa<ConstantVector>(C)) {
1426       Code = bitc::CST_CODE_AGGREGATE;
1427       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1428         Record.push_back(VE.getValueID(C->getOperand(i)));
1429       AbbrevToUse = AggregateAbbrev;
1430     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1431       switch (CE->getOpcode()) {
1432       default:
1433         if (Instruction::isCast(CE->getOpcode())) {
1434           Code = bitc::CST_CODE_CE_CAST;
1435           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1436           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1437           Record.push_back(VE.getValueID(C->getOperand(0)));
1438           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1439         } else {
1440           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1441           Code = bitc::CST_CODE_CE_BINOP;
1442           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1443           Record.push_back(VE.getValueID(C->getOperand(0)));
1444           Record.push_back(VE.getValueID(C->getOperand(1)));
1445           uint64_t Flags = GetOptimizationFlags(CE);
1446           if (Flags != 0)
1447             Record.push_back(Flags);
1448         }
1449         break;
1450       case Instruction::GetElementPtr:
1451         Code = bitc::CST_CODE_CE_GEP;
1452         if (cast<GEPOperator>(C)->isInBounds())
1453           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1454         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1455           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1456           Record.push_back(VE.getValueID(C->getOperand(i)));
1457         }
1458         break;
1459       case Instruction::Select:
1460         Code = bitc::CST_CODE_CE_SELECT;
1461         Record.push_back(VE.getValueID(C->getOperand(0)));
1462         Record.push_back(VE.getValueID(C->getOperand(1)));
1463         Record.push_back(VE.getValueID(C->getOperand(2)));
1464         break;
1465       case Instruction::ExtractElement:
1466         Code = bitc::CST_CODE_CE_EXTRACTELT;
1467         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1468         Record.push_back(VE.getValueID(C->getOperand(0)));
1469         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1470         Record.push_back(VE.getValueID(C->getOperand(1)));
1471         break;
1472       case Instruction::InsertElement:
1473         Code = bitc::CST_CODE_CE_INSERTELT;
1474         Record.push_back(VE.getValueID(C->getOperand(0)));
1475         Record.push_back(VE.getValueID(C->getOperand(1)));
1476         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1477         Record.push_back(VE.getValueID(C->getOperand(2)));
1478         break;
1479       case Instruction::ShuffleVector:
1480         // If the return type and argument types are the same, this is a
1481         // standard shufflevector instruction.  If the types are different,
1482         // then the shuffle is widening or truncating the input vectors, and
1483         // the argument type must also be encoded.
1484         if (C->getType() == C->getOperand(0)->getType()) {
1485           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1486         } else {
1487           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1488           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1489         }
1490         Record.push_back(VE.getValueID(C->getOperand(0)));
1491         Record.push_back(VE.getValueID(C->getOperand(1)));
1492         Record.push_back(VE.getValueID(C->getOperand(2)));
1493         break;
1494       case Instruction::ICmp:
1495       case Instruction::FCmp:
1496         Code = bitc::CST_CODE_CE_CMP;
1497         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1498         Record.push_back(VE.getValueID(C->getOperand(0)));
1499         Record.push_back(VE.getValueID(C->getOperand(1)));
1500         Record.push_back(CE->getPredicate());
1501         break;
1502       }
1503     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1504       Code = bitc::CST_CODE_BLOCKADDRESS;
1505       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1506       Record.push_back(VE.getValueID(BA->getFunction()));
1507       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1508     } else {
1509 #ifndef NDEBUG
1510       C->dump();
1511 #endif
1512       llvm_unreachable("Unknown constant!");
1513     }
1514     Stream.EmitRecord(Code, Record, AbbrevToUse);
1515     Record.clear();
1516   }
1517
1518   Stream.ExitBlock();
1519 }
1520
1521 static void WriteModuleConstants(const ValueEnumerator &VE,
1522                                  BitstreamWriter &Stream) {
1523   const ValueEnumerator::ValueList &Vals = VE.getValues();
1524
1525   // Find the first constant to emit, which is the first non-globalvalue value.
1526   // We know globalvalues have been emitted by WriteModuleInfo.
1527   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1528     if (!isa<GlobalValue>(Vals[i].first)) {
1529       WriteConstants(i, Vals.size(), VE, Stream, true);
1530       return;
1531     }
1532   }
1533 }
1534
1535 /// PushValueAndType - The file has to encode both the value and type id for
1536 /// many values, because we need to know what type to create for forward
1537 /// references.  However, most operands are not forward references, so this type
1538 /// field is not needed.
1539 ///
1540 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1541 /// instruction ID, then it is a forward reference, and it also includes the
1542 /// type ID.  The value ID that is written is encoded relative to the InstID.
1543 static bool PushValueAndType(const Value *V, unsigned InstID,
1544                              SmallVectorImpl<unsigned> &Vals,
1545                              ValueEnumerator &VE) {
1546   unsigned ValID = VE.getValueID(V);
1547   // Make encoding relative to the InstID.
1548   Vals.push_back(InstID - ValID);
1549   if (ValID >= InstID) {
1550     Vals.push_back(VE.getTypeID(V->getType()));
1551     return true;
1552   }
1553   return false;
1554 }
1555
1556 /// pushValue - Like PushValueAndType, but where the type of the value is
1557 /// omitted (perhaps it was already encoded in an earlier operand).
1558 static void pushValue(const Value *V, unsigned InstID,
1559                       SmallVectorImpl<unsigned> &Vals,
1560                       ValueEnumerator &VE) {
1561   unsigned ValID = VE.getValueID(V);
1562   Vals.push_back(InstID - ValID);
1563 }
1564
1565 static void pushValueSigned(const Value *V, unsigned InstID,
1566                             SmallVectorImpl<uint64_t> &Vals,
1567                             ValueEnumerator &VE) {
1568   unsigned ValID = VE.getValueID(V);
1569   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1570   emitSignedInt64(Vals, diff);
1571 }
1572
1573 /// WriteInstruction - Emit an instruction to the specified stream.
1574 static void WriteInstruction(const Instruction &I, unsigned InstID,
1575                              ValueEnumerator &VE, BitstreamWriter &Stream,
1576                              SmallVectorImpl<unsigned> &Vals) {
1577   unsigned Code = 0;
1578   unsigned AbbrevToUse = 0;
1579   VE.setInstructionID(&I);
1580   switch (I.getOpcode()) {
1581   default:
1582     if (Instruction::isCast(I.getOpcode())) {
1583       Code = bitc::FUNC_CODE_INST_CAST;
1584       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1585         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1586       Vals.push_back(VE.getTypeID(I.getType()));
1587       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1588     } else {
1589       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1590       Code = bitc::FUNC_CODE_INST_BINOP;
1591       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1592         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1593       pushValue(I.getOperand(1), InstID, Vals, VE);
1594       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1595       uint64_t Flags = GetOptimizationFlags(&I);
1596       if (Flags != 0) {
1597         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1598           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1599         Vals.push_back(Flags);
1600       }
1601     }
1602     break;
1603
1604   case Instruction::GetElementPtr:
1605     Code = bitc::FUNC_CODE_INST_GEP;
1606     if (cast<GEPOperator>(&I)->isInBounds())
1607       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1608     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1609       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1610     break;
1611   case Instruction::ExtractValue: {
1612     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1613     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1614     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1615     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1616       Vals.push_back(*i);
1617     break;
1618   }
1619   case Instruction::InsertValue: {
1620     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1621     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1622     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1623     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1624     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1625       Vals.push_back(*i);
1626     break;
1627   }
1628   case Instruction::Select:
1629     Code = bitc::FUNC_CODE_INST_VSELECT;
1630     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1631     pushValue(I.getOperand(2), InstID, Vals, VE);
1632     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1633     break;
1634   case Instruction::ExtractElement:
1635     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1636     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1637     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1638     break;
1639   case Instruction::InsertElement:
1640     Code = bitc::FUNC_CODE_INST_INSERTELT;
1641     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1642     pushValue(I.getOperand(1), InstID, Vals, VE);
1643     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1644     break;
1645   case Instruction::ShuffleVector:
1646     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1647     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1648     pushValue(I.getOperand(1), InstID, Vals, VE);
1649     pushValue(I.getOperand(2), InstID, Vals, VE);
1650     break;
1651   case Instruction::ICmp:
1652   case Instruction::FCmp:
1653     // compare returning Int1Ty or vector of Int1Ty
1654     Code = bitc::FUNC_CODE_INST_CMP2;
1655     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1656     pushValue(I.getOperand(1), InstID, Vals, VE);
1657     Vals.push_back(cast<CmpInst>(I).getPredicate());
1658     break;
1659
1660   case Instruction::Ret:
1661     {
1662       Code = bitc::FUNC_CODE_INST_RET;
1663       unsigned NumOperands = I.getNumOperands();
1664       if (NumOperands == 0)
1665         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1666       else if (NumOperands == 1) {
1667         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1668           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1669       } else {
1670         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1671           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1672       }
1673     }
1674     break;
1675   case Instruction::Br:
1676     {
1677       Code = bitc::FUNC_CODE_INST_BR;
1678       const BranchInst &II = cast<BranchInst>(I);
1679       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1680       if (II.isConditional()) {
1681         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1682         pushValue(II.getCondition(), InstID, Vals, VE);
1683       }
1684     }
1685     break;
1686   case Instruction::Switch:
1687     {
1688       Code = bitc::FUNC_CODE_INST_SWITCH;
1689       const SwitchInst &SI = cast<SwitchInst>(I);
1690       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1691       pushValue(SI.getCondition(), InstID, Vals, VE);
1692       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1693       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1694            i != e; ++i) {
1695         Vals.push_back(VE.getValueID(i.getCaseValue()));
1696         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1697       }
1698     }
1699     break;
1700   case Instruction::IndirectBr:
1701     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1702     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1703     // Encode the address operand as relative, but not the basic blocks.
1704     pushValue(I.getOperand(0), InstID, Vals, VE);
1705     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1706       Vals.push_back(VE.getValueID(I.getOperand(i)));
1707     break;
1708
1709   case Instruction::Invoke: {
1710     const InvokeInst *II = cast<InvokeInst>(&I);
1711     const Value *Callee(II->getCalledValue());
1712     PointerType *PTy = cast<PointerType>(Callee->getType());
1713     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1714     Code = bitc::FUNC_CODE_INST_INVOKE;
1715
1716     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1717     Vals.push_back(II->getCallingConv());
1718     Vals.push_back(VE.getValueID(II->getNormalDest()));
1719     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1720     PushValueAndType(Callee, InstID, Vals, VE);
1721
1722     // Emit value #'s for the fixed parameters.
1723     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1724       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1725
1726     // Emit type/value pairs for varargs params.
1727     if (FTy->isVarArg()) {
1728       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1729            i != e; ++i)
1730         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1731     }
1732     break;
1733   }
1734   case Instruction::Resume:
1735     Code = bitc::FUNC_CODE_INST_RESUME;
1736     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1737     break;
1738   case Instruction::Unreachable:
1739     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1740     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1741     break;
1742
1743   case Instruction::PHI: {
1744     const PHINode &PN = cast<PHINode>(I);
1745     Code = bitc::FUNC_CODE_INST_PHI;
1746     // With the newer instruction encoding, forward references could give
1747     // negative valued IDs.  This is most common for PHIs, so we use
1748     // signed VBRs.
1749     SmallVector<uint64_t, 128> Vals64;
1750     Vals64.push_back(VE.getTypeID(PN.getType()));
1751     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1752       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1753       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1754     }
1755     // Emit a Vals64 vector and exit.
1756     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1757     Vals64.clear();
1758     return;
1759   }
1760
1761   case Instruction::LandingPad: {
1762     const LandingPadInst &LP = cast<LandingPadInst>(I);
1763     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1764     Vals.push_back(VE.getTypeID(LP.getType()));
1765     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1766     Vals.push_back(LP.isCleanup());
1767     Vals.push_back(LP.getNumClauses());
1768     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1769       if (LP.isCatch(I))
1770         Vals.push_back(LandingPadInst::Catch);
1771       else
1772         Vals.push_back(LandingPadInst::Filter);
1773       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1774     }
1775     break;
1776   }
1777
1778   case Instruction::Alloca: {
1779     Code = bitc::FUNC_CODE_INST_ALLOCA;
1780     Vals.push_back(VE.getTypeID(I.getType()));
1781     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1782     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1783     const AllocaInst &AI = cast<AllocaInst>(I);
1784     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
1785     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
1786            "not enough bits for maximum alignment");
1787     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
1788     AlignRecord |= AI.isUsedWithInAlloca() << 5;
1789     Vals.push_back(AlignRecord);
1790     break;
1791   }
1792
1793   case Instruction::Load:
1794     if (cast<LoadInst>(I).isAtomic()) {
1795       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1796       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1797     } else {
1798       Code = bitc::FUNC_CODE_INST_LOAD;
1799       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1800         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1801     }
1802     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1803     Vals.push_back(cast<LoadInst>(I).isVolatile());
1804     if (cast<LoadInst>(I).isAtomic()) {
1805       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1806       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1807     }
1808     break;
1809   case Instruction::Store:
1810     if (cast<StoreInst>(I).isAtomic())
1811       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1812     else
1813       Code = bitc::FUNC_CODE_INST_STORE;
1814     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1815     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1816     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1817     Vals.push_back(cast<StoreInst>(I).isVolatile());
1818     if (cast<StoreInst>(I).isAtomic()) {
1819       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1820       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1821     }
1822     break;
1823   case Instruction::AtomicCmpXchg:
1824     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1825     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1826     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1827     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1828     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1829     Vals.push_back(GetEncodedOrdering(
1830                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
1831     Vals.push_back(GetEncodedSynchScope(
1832                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1833     Vals.push_back(GetEncodedOrdering(
1834                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
1835     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
1836     break;
1837   case Instruction::AtomicRMW:
1838     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1839     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1840     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1841     Vals.push_back(GetEncodedRMWOperation(
1842                      cast<AtomicRMWInst>(I).getOperation()));
1843     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1844     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1845     Vals.push_back(GetEncodedSynchScope(
1846                      cast<AtomicRMWInst>(I).getSynchScope()));
1847     break;
1848   case Instruction::Fence:
1849     Code = bitc::FUNC_CODE_INST_FENCE;
1850     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1851     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1852     break;
1853   case Instruction::Call: {
1854     const CallInst &CI = cast<CallInst>(I);
1855     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1856     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1857
1858     Code = bitc::FUNC_CODE_INST_CALL;
1859
1860     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1861     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()) |
1862                    unsigned(CI.isMustTailCall()) << 14);
1863     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1864
1865     // Emit value #'s for the fixed parameters.
1866     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1867       // Check for labels (can happen with asm labels).
1868       if (FTy->getParamType(i)->isLabelTy())
1869         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1870       else
1871         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1872     }
1873
1874     // Emit type/value pairs for varargs params.
1875     if (FTy->isVarArg()) {
1876       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1877            i != e; ++i)
1878         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1879     }
1880     break;
1881   }
1882   case Instruction::VAArg:
1883     Code = bitc::FUNC_CODE_INST_VAARG;
1884     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1885     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1886     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1887     break;
1888   }
1889
1890   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1891   Vals.clear();
1892 }
1893
1894 // Emit names for globals/functions etc.
1895 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1896                                   const ValueEnumerator &VE,
1897                                   BitstreamWriter &Stream) {
1898   if (VST.empty()) return;
1899   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1900
1901   // FIXME: Set up the abbrev, we know how many values there are!
1902   // FIXME: We know if the type names can use 7-bit ascii.
1903   SmallVector<unsigned, 64> NameVals;
1904
1905   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1906        SI != SE; ++SI) {
1907
1908     const ValueName &Name = *SI;
1909
1910     // Figure out the encoding to use for the name.
1911     bool is7Bit = true;
1912     bool isChar6 = true;
1913     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1914          C != E; ++C) {
1915       if (isChar6)
1916         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1917       if ((unsigned char)*C & 128) {
1918         is7Bit = false;
1919         break;  // don't bother scanning the rest.
1920       }
1921     }
1922
1923     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1924
1925     // VST_ENTRY:   [valueid, namechar x N]
1926     // VST_BBENTRY: [bbid, namechar x N]
1927     unsigned Code;
1928     if (isa<BasicBlock>(SI->getValue())) {
1929       Code = bitc::VST_CODE_BBENTRY;
1930       if (isChar6)
1931         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1932     } else {
1933       Code = bitc::VST_CODE_ENTRY;
1934       if (isChar6)
1935         AbbrevToUse = VST_ENTRY_6_ABBREV;
1936       else if (is7Bit)
1937         AbbrevToUse = VST_ENTRY_7_ABBREV;
1938     }
1939
1940     NameVals.push_back(VE.getValueID(SI->getValue()));
1941     for (const char *P = Name.getKeyData(),
1942          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1943       NameVals.push_back((unsigned char)*P);
1944
1945     // Emit the finished record.
1946     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1947     NameVals.clear();
1948   }
1949   Stream.ExitBlock();
1950 }
1951
1952 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
1953                          BitstreamWriter &Stream) {
1954   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
1955   unsigned Code;
1956   if (isa<BasicBlock>(Order.V))
1957     Code = bitc::USELIST_CODE_BB;
1958   else
1959     Code = bitc::USELIST_CODE_DEFAULT;
1960
1961   SmallVector<uint64_t, 64> Record;
1962   for (unsigned I : Order.Shuffle)
1963     Record.push_back(I);
1964   Record.push_back(VE.getValueID(Order.V));
1965   Stream.EmitRecord(Code, Record);
1966 }
1967
1968 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
1969                               BitstreamWriter &Stream) {
1970   auto hasMore = [&]() {
1971     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
1972   };
1973   if (!hasMore())
1974     // Nothing to do.
1975     return;
1976
1977   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1978   while (hasMore()) {
1979     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
1980     VE.UseListOrders.pop_back();
1981   }
1982   Stream.ExitBlock();
1983 }
1984
1985 /// WriteFunction - Emit a function body to the module stream.
1986 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1987                           BitstreamWriter &Stream) {
1988   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1989   VE.incorporateFunction(F);
1990
1991   SmallVector<unsigned, 64> Vals;
1992
1993   // Emit the number of basic blocks, so the reader can create them ahead of
1994   // time.
1995   Vals.push_back(VE.getBasicBlocks().size());
1996   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1997   Vals.clear();
1998
1999   // If there are function-local constants, emit them now.
2000   unsigned CstStart, CstEnd;
2001   VE.getFunctionConstantRange(CstStart, CstEnd);
2002   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2003
2004   // If there is function-local metadata, emit it now.
2005   WriteFunctionLocalMetadata(F, VE, Stream);
2006
2007   // Keep a running idea of what the instruction ID is.
2008   unsigned InstID = CstEnd;
2009
2010   bool NeedsMetadataAttachment = false;
2011
2012   DebugLoc LastDL;
2013
2014   // Finally, emit all the instructions, in order.
2015   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2016     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2017          I != E; ++I) {
2018       WriteInstruction(*I, InstID, VE, Stream, Vals);
2019
2020       if (!I->getType()->isVoidTy())
2021         ++InstID;
2022
2023       // If the instruction has metadata, write a metadata attachment later.
2024       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2025
2026       // If the instruction has a debug location, emit it.
2027       DebugLoc DL = I->getDebugLoc();
2028       if (DL.isUnknown()) {
2029         // nothing todo.
2030       } else if (DL == LastDL) {
2031         // Just repeat the same debug loc as last time.
2032         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2033       } else {
2034         MDNode *Scope, *IA;
2035         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
2036         assert(Scope && "Expected valid scope");
2037
2038         Vals.push_back(DL.getLine());
2039         Vals.push_back(DL.getCol());
2040         Vals.push_back(VE.getMetadataOrNullID(Scope));
2041         Vals.push_back(VE.getMetadataOrNullID(IA));
2042         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2043         Vals.clear();
2044
2045         LastDL = DL;
2046       }
2047     }
2048
2049   // Emit names for all the instructions etc.
2050   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2051
2052   if (NeedsMetadataAttachment)
2053     WriteMetadataAttachment(F, VE, Stream);
2054   if (shouldPreserveBitcodeUseListOrder())
2055     WriteUseListBlock(&F, VE, Stream);
2056   VE.purgeFunction();
2057   Stream.ExitBlock();
2058 }
2059
2060 // Emit blockinfo, which defines the standard abbreviations etc.
2061 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2062   // We only want to emit block info records for blocks that have multiple
2063   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2064   // Other blocks can define their abbrevs inline.
2065   Stream.EnterBlockInfoBlock(2);
2066
2067   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
2068     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2069     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2070     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2071     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2072     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2073     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2074                                    Abbv) != VST_ENTRY_8_ABBREV)
2075       llvm_unreachable("Unexpected abbrev ordering!");
2076   }
2077
2078   { // 7-bit fixed width VST_ENTRY strings.
2079     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2080     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2081     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2082     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2083     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2084     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2085                                    Abbv) != VST_ENTRY_7_ABBREV)
2086       llvm_unreachable("Unexpected abbrev ordering!");
2087   }
2088   { // 6-bit char6 VST_ENTRY strings.
2089     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2090     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2091     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2092     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2093     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2094     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2095                                    Abbv) != VST_ENTRY_6_ABBREV)
2096       llvm_unreachable("Unexpected abbrev ordering!");
2097   }
2098   { // 6-bit char6 VST_BBENTRY strings.
2099     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2100     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2101     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2102     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2103     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2104     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2105                                    Abbv) != VST_BBENTRY_6_ABBREV)
2106       llvm_unreachable("Unexpected abbrev ordering!");
2107   }
2108
2109
2110
2111   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2112     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2113     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2114     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2115                               Log2_32_Ceil(VE.getTypes().size()+1)));
2116     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2117                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2118       llvm_unreachable("Unexpected abbrev ordering!");
2119   }
2120
2121   { // INTEGER abbrev for CONSTANTS_BLOCK.
2122     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2123     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2125     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2126                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2127       llvm_unreachable("Unexpected abbrev ordering!");
2128   }
2129
2130   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2131     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2132     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2134     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2135                               Log2_32_Ceil(VE.getTypes().size()+1)));
2136     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2137
2138     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2139                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2140       llvm_unreachable("Unexpected abbrev ordering!");
2141   }
2142   { // NULL abbrev for CONSTANTS_BLOCK.
2143     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2144     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2145     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2146                                    Abbv) != CONSTANTS_NULL_Abbrev)
2147       llvm_unreachable("Unexpected abbrev ordering!");
2148   }
2149
2150   // FIXME: This should only use space for first class types!
2151
2152   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2153     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2154     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2156     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2157     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2158     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2159                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2160       llvm_unreachable("Unexpected abbrev ordering!");
2161   }
2162   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2163     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2164     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2165     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2166     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2167     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2168     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2169                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2170       llvm_unreachable("Unexpected abbrev ordering!");
2171   }
2172   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2173     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2174     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2175     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2178     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2179     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2180                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2181       llvm_unreachable("Unexpected abbrev ordering!");
2182   }
2183   { // INST_CAST abbrev for FUNCTION_BLOCK.
2184     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2185     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2186     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2187     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2188                               Log2_32_Ceil(VE.getTypes().size()+1)));
2189     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2190     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2191                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2192       llvm_unreachable("Unexpected abbrev ordering!");
2193   }
2194
2195   { // INST_RET abbrev for FUNCTION_BLOCK.
2196     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2197     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2198     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2199                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2200       llvm_unreachable("Unexpected abbrev ordering!");
2201   }
2202   { // INST_RET abbrev for FUNCTION_BLOCK.
2203     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2204     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2205     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2206     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2207                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2208       llvm_unreachable("Unexpected abbrev ordering!");
2209   }
2210   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2211     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2212     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2213     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2214                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2215       llvm_unreachable("Unexpected abbrev ordering!");
2216   }
2217
2218   Stream.ExitBlock();
2219 }
2220
2221 /// WriteModule - Emit the specified module to the bitstream.
2222 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
2223   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
2224
2225   SmallVector<unsigned, 1> Vals;
2226   unsigned CurVersion = 1;
2227   Vals.push_back(CurVersion);
2228   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
2229
2230   // Analyze the module, enumerating globals, functions, etc.
2231   ValueEnumerator VE(*M);
2232
2233   // Emit blockinfo, which defines the standard abbreviations etc.
2234   WriteBlockInfo(VE, Stream);
2235
2236   // Emit information about attribute groups.
2237   WriteAttributeGroupTable(VE, Stream);
2238
2239   // Emit information about parameter attributes.
2240   WriteAttributeTable(VE, Stream);
2241
2242   // Emit information describing all of the types in the module.
2243   WriteTypeTable(VE, Stream);
2244
2245   writeComdats(VE, Stream);
2246
2247   // Emit top-level description of module, including target triple, inline asm,
2248   // descriptors for global variables, and function prototype info.
2249   WriteModuleInfo(M, VE, Stream);
2250
2251   // Emit constants.
2252   WriteModuleConstants(VE, Stream);
2253
2254   // Emit metadata.
2255   WriteModuleMetadata(M, VE, Stream);
2256
2257   // Emit metadata.
2258   WriteModuleMetadataStore(M, Stream);
2259
2260   // Emit names for globals/functions etc.
2261   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
2262
2263   // Emit module-level use-lists.
2264   if (shouldPreserveBitcodeUseListOrder())
2265     WriteUseListBlock(nullptr, VE, Stream);
2266
2267   // Emit function bodies.
2268   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
2269     if (!F->isDeclaration())
2270       WriteFunction(*F, VE, Stream);
2271
2272   Stream.ExitBlock();
2273 }
2274
2275 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
2276 /// header and trailer to make it compatible with the system archiver.  To do
2277 /// this we emit the following header, and then emit a trailer that pads the
2278 /// file out to be a multiple of 16 bytes.
2279 ///
2280 /// struct bc_header {
2281 ///   uint32_t Magic;         // 0x0B17C0DE
2282 ///   uint32_t Version;       // Version, currently always 0.
2283 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
2284 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
2285 ///   uint32_t CPUType;       // CPU specifier.
2286 ///   ... potentially more later ...
2287 /// };
2288 enum {
2289   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
2290   DarwinBCHeaderSize = 5*4
2291 };
2292
2293 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
2294                                uint32_t &Position) {
2295   Buffer[Position + 0] = (unsigned char) (Value >>  0);
2296   Buffer[Position + 1] = (unsigned char) (Value >>  8);
2297   Buffer[Position + 2] = (unsigned char) (Value >> 16);
2298   Buffer[Position + 3] = (unsigned char) (Value >> 24);
2299   Position += 4;
2300 }
2301
2302 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
2303                                          const Triple &TT) {
2304   unsigned CPUType = ~0U;
2305
2306   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
2307   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
2308   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
2309   // specific constants here because they are implicitly part of the Darwin ABI.
2310   enum {
2311     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
2312     DARWIN_CPU_TYPE_X86        = 7,
2313     DARWIN_CPU_TYPE_ARM        = 12,
2314     DARWIN_CPU_TYPE_POWERPC    = 18
2315   };
2316
2317   Triple::ArchType Arch = TT.getArch();
2318   if (Arch == Triple::x86_64)
2319     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
2320   else if (Arch == Triple::x86)
2321     CPUType = DARWIN_CPU_TYPE_X86;
2322   else if (Arch == Triple::ppc)
2323     CPUType = DARWIN_CPU_TYPE_POWERPC;
2324   else if (Arch == Triple::ppc64)
2325     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
2326   else if (Arch == Triple::arm || Arch == Triple::thumb)
2327     CPUType = DARWIN_CPU_TYPE_ARM;
2328
2329   // Traditional Bitcode starts after header.
2330   assert(Buffer.size() >= DarwinBCHeaderSize &&
2331          "Expected header size to be reserved");
2332   unsigned BCOffset = DarwinBCHeaderSize;
2333   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
2334
2335   // Write the magic and version.
2336   unsigned Position = 0;
2337   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
2338   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
2339   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
2340   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2341   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2342
2343   // If the file is not a multiple of 16 bytes, insert dummy padding.
2344   while (Buffer.size() & 15)
2345     Buffer.push_back(0);
2346 }
2347
2348 /// WriteBitcodeToFile - Write the specified module to the specified output
2349 /// stream.
2350 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2351   SmallVector<char, 0> Buffer;
2352   Buffer.reserve(256*1024);
2353
2354   // If this is darwin or another generic macho target, reserve space for the
2355   // header.
2356   Triple TT(M->getTargetTriple());
2357   if (TT.isOSDarwin())
2358     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2359
2360   // Emit the module into the buffer.
2361   {
2362     BitstreamWriter Stream(Buffer);
2363
2364     // Emit the file header.
2365     Stream.Emit((unsigned)'B', 8);
2366     Stream.Emit((unsigned)'C', 8);
2367     Stream.Emit(0x0, 4);
2368     Stream.Emit(0xC, 4);
2369     Stream.Emit(0xE, 4);
2370     Stream.Emit(0xD, 4);
2371
2372     // Emit the module.
2373     WriteModule(M, Stream);
2374   }
2375
2376   if (TT.isOSDarwin())
2377     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2378
2379   // Write the generated bitstream to "Out".
2380   Out.write((char*)&Buffer.front(), Buffer.size());
2381 }