lib/Bitcode/Writer/BitcodeWriter.cpp

   1 //===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Bitcode writer implementation.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Bitcode/ReaderWriter.h"
  15 #include "ValueEnumerator.h"
  16 #include "llvm/ADT/Triple.h"
  17 #include "llvm/Bitcode/BitstreamWriter.h"
  18 #include "llvm/Bitcode/LLVMBitCodes.h"
  19 #include "llvm/IR/Constants.h"
  20 #include "llvm/IR/DerivedTypes.h"
  21 #include "llvm/IR/InlineAsm.h"
  22 #include "llvm/IR/Instructions.h"
  23 #include "llvm/IR/Module.h"
  24 #include "llvm/IR/Operator.h"
  25 #include "llvm/IR/UseListOrder.h"
  26 #include "llvm/IR/ValueSymbolTable.h"
  27 #include "llvm/Support/CommandLine.h"
  28 #include "llvm/Support/ErrorHandling.h"
  29 #include "llvm/Support/MathExtras.h"
  30 #include "llvm/Support/Program.h"
  31 #include "llvm/Support/raw_ostream.h"
  32 #include <cctype>
  33 #include <map>
  34 using namespace llvm;
  35
  36 /// These are manifest constants used by the bitcode writer. They do not need to
  37 /// be kept in sync with the reader, but need to be consistent within this file.
  38 enum {
  39   // VALUE_SYMTAB_BLOCK abbrev id's.
  40   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  41   VST_ENTRY_7_ABBREV,
  42   VST_ENTRY_6_ABBREV,
  43   VST_BBENTRY_6_ABBREV,
  44
  45   // CONSTANTS_BLOCK abbrev id's.
  46   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  47   CONSTANTS_INTEGER_ABBREV,
  48   CONSTANTS_CE_CAST_Abbrev,
  49   CONSTANTS_NULL_Abbrev,
  50
  51   // FUNCTION_BLOCK abbrev id's.
  52   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  53   FUNCTION_INST_BINOP_ABBREV,
  54   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  55   FUNCTION_INST_CAST_ABBREV,
  56   FUNCTION_INST_RET_VOID_ABBREV,
  57   FUNCTION_INST_RET_VAL_ABBREV,
  58   FUNCTION_INST_UNREACHABLE_ABBREV
  59 };
  60
  61 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  62   switch (Opcode) {
  63   default: llvm_unreachable("Unknown cast instruction!");
  64   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  65   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  66   case Instruction::SExt    : return bitc::CAST_SEXT;
  67   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  68   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  69   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  70   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  71   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  72   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  73   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  74   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  75   case Instruction::BitCast : return bitc::CAST_BITCAST;
  76   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
  77   }
  78 }
  79
  80 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  81   switch (Opcode) {
  82   default: llvm_unreachable("Unknown binary instruction!");
  83   case Instruction::Add:
  84   case Instruction::FAdd: return bitc::BINOP_ADD;
  85   case Instruction::Sub:
  86   case Instruction::FSub: return bitc::BINOP_SUB;
  87   case Instruction::Mul:
  88   case Instruction::FMul: return bitc::BINOP_MUL;
  89   case Instruction::UDiv: return bitc::BINOP_UDIV;
  90   case Instruction::FDiv:
  91   case Instruction::SDiv: return bitc::BINOP_SDIV;
  92   case Instruction::URem: return bitc::BINOP_UREM;
  93   case Instruction::FRem:
  94   case Instruction::SRem: return bitc::BINOP_SREM;
  95   case Instruction::Shl:  return bitc::BINOP_SHL;
  96   case Instruction::LShr: return bitc::BINOP_LSHR;
  97   case Instruction::AShr: return bitc::BINOP_ASHR;
  98   case Instruction::And:  return bitc::BINOP_AND;
  99   case Instruction::Or:   return bitc::BINOP_OR;
 100   case Instruction::Xor:  return bitc::BINOP_XOR;
 101   }
 102 }
 103
 104 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 105   switch (Op) {
 106   default: llvm_unreachable("Unknown RMW operation!");
 107   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 108   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 109   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 110   case AtomicRMWInst::And: return bitc::RMW_AND;
 111   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 112   case AtomicRMWInst::Or: return bitc::RMW_OR;
 113   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 114   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 115   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 116   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 117   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 118   }
 119 }
 120
 121 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 122   switch (Ordering) {
 123   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 124   case Unordered: return bitc::ORDERING_UNORDERED;
 125   case Monotonic: return bitc::ORDERING_MONOTONIC;
 126   case Acquire: return bitc::ORDERING_ACQUIRE;
 127   case Release: return bitc::ORDERING_RELEASE;
 128   case AcquireRelease: return bitc::ORDERING_ACQREL;
 129   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 130   }
 131   llvm_unreachable("Invalid ordering");
 132 }
 133
 134 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 135   switch (SynchScope) {
 136   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 137   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 138   }
 139   llvm_unreachable("Invalid synch scope");
 140 }
 141
 142 static void WriteStringRecord(unsigned Code, StringRef Str,
 143                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 144   SmallVector<unsigned, 64> Vals;
 145
 146   // Code: [strchar x N]
 147   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 148     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 149       AbbrevToUse = 0;
 150     Vals.push_back(Str[i]);
 151   }
 152
 153   // Emit the finished record.
 154   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 155 }
 156
 157 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
 158   switch (Kind) {
 159   case Attribute::Alignment:
 160     return bitc::ATTR_KIND_ALIGNMENT;
 161   case Attribute::AlwaysInline:
 162     return bitc::ATTR_KIND_ALWAYS_INLINE;
 163   case Attribute::Builtin:
 164     return bitc::ATTR_KIND_BUILTIN;
 165   case Attribute::ByVal:
 166     return bitc::ATTR_KIND_BY_VAL;
 167   case Attribute::InAlloca:
 168     return bitc::ATTR_KIND_IN_ALLOCA;
 169   case Attribute::Cold:
 170     return bitc::ATTR_KIND_COLD;
 171   case Attribute::InlineHint:
 172     return bitc::ATTR_KIND_INLINE_HINT;
 173   case Attribute::InReg:
 174     return bitc::ATTR_KIND_IN_REG;
 175   case Attribute::JumpTable:
 176     return bitc::ATTR_KIND_JUMP_TABLE;
 177   case Attribute::MinSize:
 178     return bitc::ATTR_KIND_MIN_SIZE;
 179   case Attribute::Naked:
 180     return bitc::ATTR_KIND_NAKED;
 181   case Attribute::Nest:
 182     return bitc::ATTR_KIND_NEST;
 183   case Attribute::NoAlias:
 184     return bitc::ATTR_KIND_NO_ALIAS;
 185   case Attribute::NoBuiltin:
 186     return bitc::ATTR_KIND_NO_BUILTIN;
 187   case Attribute::NoCapture:
 188     return bitc::ATTR_KIND_NO_CAPTURE;
 189   case Attribute::NoDuplicate:
 190     return bitc::ATTR_KIND_NO_DUPLICATE;
 191   case Attribute::NoImplicitFloat:
 192     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
 193   case Attribute::NoInline:
 194     return bitc::ATTR_KIND_NO_INLINE;
 195   case Attribute::NonLazyBind:
 196     return bitc::ATTR_KIND_NON_LAZY_BIND;
 197   case Attribute::NonNull:
 198     return bitc::ATTR_KIND_NON_NULL;
 199   case Attribute::Dereferenceable:
 200     return bitc::ATTR_KIND_DEREFERENCEABLE;
 201   case Attribute::NoRedZone:
 202     return bitc::ATTR_KIND_NO_RED_ZONE;
 203   case Attribute::NoReturn:
 204     return bitc::ATTR_KIND_NO_RETURN;
 205   case Attribute::NoUnwind:
 206     return bitc::ATTR_KIND_NO_UNWIND;
 207   case Attribute::OptimizeForSize:
 208     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
 209   case Attribute::OptimizeNone:
 210     return bitc::ATTR_KIND_OPTIMIZE_NONE;
 211   case Attribute::ReadNone:
 212     return bitc::ATTR_KIND_READ_NONE;
 213   case Attribute::ReadOnly:
 214     return bitc::ATTR_KIND_READ_ONLY;
 215   case Attribute::Returned:
 216     return bitc::ATTR_KIND_RETURNED;
 217   case Attribute::ReturnsTwice:
 218     return bitc::ATTR_KIND_RETURNS_TWICE;
 219   case Attribute::SExt:
 220     return bitc::ATTR_KIND_S_EXT;
 221   case Attribute::StackAlignment:
 222     return bitc::ATTR_KIND_STACK_ALIGNMENT;
 223   case Attribute::StackProtect:
 224     return bitc::ATTR_KIND_STACK_PROTECT;
 225   case Attribute::StackProtectReq:
 226     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
 227   case Attribute::StackProtectStrong:
 228     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
 229   case Attribute::StructRet:
 230     return bitc::ATTR_KIND_STRUCT_RET;
 231   case Attribute::SanitizeAddress:
 232     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
 233   case Attribute::SanitizeThread:
 234     return bitc::ATTR_KIND_SANITIZE_THREAD;
 235   case Attribute::SanitizeMemory:
 236     return bitc::ATTR_KIND_SANITIZE_MEMORY;
 237   case Attribute::UWTable:
 238     return bitc::ATTR_KIND_UW_TABLE;
 239   case Attribute::ZExt:
 240     return bitc::ATTR_KIND_Z_EXT;
 241   case Attribute::EndAttrKinds:
 242     llvm_unreachable("Can not encode end-attribute kinds marker.");
 243   case Attribute::None:
 244     llvm_unreachable("Can not encode none-attribute.");
 245   }
 246
 247   llvm_unreachable("Trying to encode unknown attribute");
 248 }
 249
 250 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
 251                                      BitstreamWriter &Stream) {
 252   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
 253   if (AttrGrps.empty()) return;
 254
 255   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 256
 257   SmallVector<uint64_t, 64> Record;
 258   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
 259     AttributeSet AS = AttrGrps[i];
 260     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
 261       AttributeSet A = AS.getSlotAttributes(i);
 262
 263       Record.push_back(VE.getAttributeGroupID(A));
 264       Record.push_back(AS.getSlotIndex(i));
 265
 266       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
 267            I != E; ++I) {
 268         Attribute Attr = *I;
 269         if (Attr.isEnumAttribute()) {
 270           Record.push_back(0);
 271           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 272         } else if (Attr.isIntAttribute()) {
 273           Record.push_back(1);
 274           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
 275           Record.push_back(Attr.getValueAsInt());
 276         } else {
 277           StringRef Kind = Attr.getKindAsString();
 278           StringRef Val = Attr.getValueAsString();
 279
 280           Record.push_back(Val.empty() ? 3 : 4);
 281           Record.append(Kind.begin(), Kind.end());
 282           Record.push_back(0);
 283           if (!Val.empty()) {
 284             Record.append(Val.begin(), Val.end());
 285             Record.push_back(0);
 286           }
 287         }
 288       }
 289
 290       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
 291       Record.clear();
 292     }
 293   }
 294
 295   Stream.ExitBlock();
 296 }
 297
 298 static void WriteAttributeTable(const ValueEnumerator &VE,
 299                                 BitstreamWriter &Stream) {
 300   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 301   if (Attrs.empty()) return;
 302
 303   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 304
 305   SmallVector<uint64_t, 64> Record;
 306   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 307     const AttributeSet &A = Attrs[i];
 308     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
 309       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
 310
 311     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 312     Record.clear();
 313   }
 314
 315   Stream.ExitBlock();
 316 }
 317
 318 /// WriteTypeTable - Write out the type table for a module.
 319 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 320   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 321
 322   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 323   SmallVector<uint64_t, 64> TypeVals;
 324
 325   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 326
 327   // Abbrev for TYPE_CODE_POINTER.
 328   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 329   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 330   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 331   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 332   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 333
 334   // Abbrev for TYPE_CODE_FUNCTION.
 335   Abbv = new BitCodeAbbrev();
 336   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 337   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 338   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 339   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 340
 341   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 342
 343   // Abbrev for TYPE_CODE_STRUCT_ANON.
 344   Abbv = new BitCodeAbbrev();
 345   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 346   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 347   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 348   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 349
 350   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 351
 352   // Abbrev for TYPE_CODE_STRUCT_NAME.
 353   Abbv = new BitCodeAbbrev();
 354   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 355   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 356   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 357   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 358
 359   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 360   Abbv = new BitCodeAbbrev();
 361   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 362   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 363   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 365
 366   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 367
 368   // Abbrev for TYPE_CODE_ARRAY.
 369   Abbv = new BitCodeAbbrev();
 370   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 373
 374   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 375
 376   // Emit an entry count so the reader can reserve space.
 377   TypeVals.push_back(TypeList.size());
 378   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 379   TypeVals.clear();
 380
 381   // Loop over all of the types, emitting each in turn.
 382   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 383     Type *T = TypeList[i];
 384     int AbbrevToUse = 0;
 385     unsigned Code = 0;
 386
 387     switch (T->getTypeID()) {
 388     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 389     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 390     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 391     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 392     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 393     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 394     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 395     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 396     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 397     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 398     case Type::IntegerTyID:
 399       // INTEGER: [width]
 400       Code = bitc::TYPE_CODE_INTEGER;
 401       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 402       break;
 403     case Type::PointerTyID: {
 404       PointerType *PTy = cast<PointerType>(T);
 405       // POINTER: [pointee type, address space]
 406       Code = bitc::TYPE_CODE_POINTER;
 407       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 408       unsigned AddressSpace = PTy->getAddressSpace();
 409       TypeVals.push_back(AddressSpace);
 410       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 411       break;
 412     }
 413     case Type::FunctionTyID: {
 414       FunctionType *FT = cast<FunctionType>(T);
 415       // FUNCTION: [isvararg, retty, paramty x N]
 416       Code = bitc::TYPE_CODE_FUNCTION;
 417       TypeVals.push_back(FT->isVarArg());
 418       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 419       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 420         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 421       AbbrevToUse = FunctionAbbrev;
 422       break;
 423     }
 424     case Type::StructTyID: {
 425       StructType *ST = cast<StructType>(T);
 426       // STRUCT: [ispacked, eltty x N]
 427       TypeVals.push_back(ST->isPacked());
 428       // Output all of the element types.
 429       for (StructType::element_iterator I = ST->element_begin(),
 430            E = ST->element_end(); I != E; ++I)
 431         TypeVals.push_back(VE.getTypeID(*I));
 432
 433       if (ST->isLiteral()) {
 434         Code = bitc::TYPE_CODE_STRUCT_ANON;
 435         AbbrevToUse = StructAnonAbbrev;
 436       } else {
 437         if (ST->isOpaque()) {
 438           Code = bitc::TYPE_CODE_OPAQUE;
 439         } else {
 440           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 441           AbbrevToUse = StructNamedAbbrev;
 442         }
 443
 444         // Emit the name if it is present.
 445         if (!ST->getName().empty())
 446           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 447                             StructNameAbbrev, Stream);
 448       }
 449       break;
 450     }
 451     case Type::ArrayTyID: {
 452       ArrayType *AT = cast<ArrayType>(T);
 453       // ARRAY: [numelts, eltty]
 454       Code = bitc::TYPE_CODE_ARRAY;
 455       TypeVals.push_back(AT->getNumElements());
 456       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 457       AbbrevToUse = ArrayAbbrev;
 458       break;
 459     }
 460     case Type::VectorTyID: {
 461       VectorType *VT = cast<VectorType>(T);
 462       // VECTOR [numelts, eltty]
 463       Code = bitc::TYPE_CODE_VECTOR;
 464       TypeVals.push_back(VT->getNumElements());
 465       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 466       break;
 467     }
 468     }
 469
 470     // Emit the finished record.
 471     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 472     TypeVals.clear();
 473   }
 474
 475   Stream.ExitBlock();
 476 }
 477
 478 static unsigned getEncodedLinkage(const GlobalValue &GV) {
 479   switch (GV.getLinkage()) {
 480   case GlobalValue::ExternalLinkage:                 return 0;
 481   case GlobalValue::WeakAnyLinkage:                  return 1;
 482   case GlobalValue::AppendingLinkage:                return 2;
 483   case GlobalValue::InternalLinkage:                 return 3;
 484   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 485   case GlobalValue::ExternalWeakLinkage:             return 7;
 486   case GlobalValue::CommonLinkage:                   return 8;
 487   case GlobalValue::PrivateLinkage:                  return 9;
 488   case GlobalValue::WeakODRLinkage:                  return 10;
 489   case GlobalValue::LinkOnceODRLinkage:              return 11;
 490   case GlobalValue::AvailableExternallyLinkage:      return 12;
 491   }
 492   llvm_unreachable("Invalid linkage");
 493 }
 494
 495 static unsigned getEncodedVisibility(const GlobalValue &GV) {
 496   switch (GV.getVisibility()) {
 497   case GlobalValue::DefaultVisibility:   return 0;
 498   case GlobalValue::HiddenVisibility:    return 1;
 499   case GlobalValue::ProtectedVisibility: return 2;
 500   }
 501   llvm_unreachable("Invalid visibility");
 502 }
 503
 504 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
 505   switch (GV.getDLLStorageClass()) {
 506   case GlobalValue::DefaultStorageClass:   return 0;
 507   case GlobalValue::DLLImportStorageClass: return 1;
 508   case GlobalValue::DLLExportStorageClass: return 2;
 509   }
 510   llvm_unreachable("Invalid DLL storage class");
 511 }
 512
 513 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
 514   switch (GV.getThreadLocalMode()) {
 515     case GlobalVariable::NotThreadLocal:         return 0;
 516     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 517     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 518     case GlobalVariable::InitialExecTLSModel:    return 3;
 519     case GlobalVariable::LocalExecTLSModel:      return 4;
 520   }
 521   llvm_unreachable("Invalid TLS model");
 522 }
 523
 524 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
 525   switch (C.getSelectionKind()) {
 526   case Comdat::Any:
 527     return bitc::COMDAT_SELECTION_KIND_ANY;
 528   case Comdat::ExactMatch:
 529     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
 530   case Comdat::Largest:
 531     return bitc::COMDAT_SELECTION_KIND_LARGEST;
 532   case Comdat::NoDuplicates:
 533     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
 534   case Comdat::SameSize:
 535     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
 536   }
 537   llvm_unreachable("Invalid selection kind");
 538 }
 539
 540 static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 541   SmallVector<uint8_t, 64> Vals;
 542   for (const Comdat *C : VE.getComdats()) {
 543     // COMDAT: [selection_kind, name]
 544     Vals.push_back(getEncodedComdatSelectionKind(*C));
 545     Vals.push_back(C->getName().size());
 546     for (char Chr : C->getName())
 547       Vals.push_back((unsigned char)Chr);
 548     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
 549     Vals.clear();
 550   }
 551 }
 552
 553 // Emit top-level description of module, including target triple, inline asm,
 554 // descriptors for global variables, and function prototype info.
 555 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 556                             BitstreamWriter &Stream) {
 557   // Emit various pieces of data attached to a module.
 558   if (!M->getTargetTriple().empty())
 559     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 560                       0/*TODO*/, Stream);
 561   const std::string &DL = M->getDataLayoutStr();
 562   if (!DL.empty())
 563     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
 564   if (!M->getModuleInlineAsm().empty())
 565     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 566                       0/*TODO*/, Stream);
 567
 568   // Emit information about sections and GC, computing how many there are. Also
 569   // compute the maximum alignment value.
 570   std::map<std::string, unsigned> SectionMap;
 571   std::map<std::string, unsigned> GCMap;
 572   unsigned MaxAlignment = 0;
 573   unsigned MaxGlobalType = 0;
 574   for (const GlobalValue &GV : M->globals()) {
 575     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
 576     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getType()));
 577     if (GV.hasSection()) {
 578       // Give section names unique ID's.
 579       unsigned &Entry = SectionMap[GV.getSection()];
 580       if (!Entry) {
 581         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
 582                           0/*TODO*/, Stream);
 583         Entry = SectionMap.size();
 584       }
 585     }
 586   }
 587   for (const Function &F : *M) {
 588     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
 589     if (F.hasSection()) {
 590       // Give section names unique ID's.
 591       unsigned &Entry = SectionMap[F.getSection()];
 592       if (!Entry) {
 593         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
 594                           0/*TODO*/, Stream);
 595         Entry = SectionMap.size();
 596       }
 597     }
 598     if (F.hasGC()) {
 599       // Same for GC names.
 600       unsigned &Entry = GCMap[F.getGC()];
 601       if (!Entry) {
 602         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
 603                           0/*TODO*/, Stream);
 604         Entry = GCMap.size();
 605       }
 606     }
 607   }
 608
 609   // Emit abbrev for globals, now that we know # sections and max alignment.
 610   unsigned SimpleGVarAbbrev = 0;
 611   if (!M->global_empty()) {
 612     // Add an abbrev for common globals with no visibility or thread localness.
 613     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 614     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 615     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 616                               Log2_32_Ceil(MaxGlobalType+1)));
 617     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 618     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 619     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 620     if (MaxAlignment == 0)                                      // Alignment.
 621       Abbv->Add(BitCodeAbbrevOp(0));
 622     else {
 623       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 624       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 625                                Log2_32_Ceil(MaxEncAlignment+1)));
 626     }
 627     if (SectionMap.empty())                                    // Section.
 628       Abbv->Add(BitCodeAbbrevOp(0));
 629     else
 630       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 631                                Log2_32_Ceil(SectionMap.size()+1)));
 632     // Don't bother emitting vis + thread local.
 633     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 634   }
 635
 636   // Emit the global variable information.
 637   SmallVector<unsigned, 64> Vals;
 638   for (const GlobalVariable &GV : M->globals()) {
 639     unsigned AbbrevToUse = 0;
 640
 641     // GLOBALVAR: [type, isconst, initid,
 642     //             linkage, alignment, section, visibility, threadlocal,
 643     //             unnamed_addr, externally_initialized, dllstorageclass]
 644     Vals.push_back(VE.getTypeID(GV.getType()));
 645     Vals.push_back(GV.isConstant());
 646     Vals.push_back(GV.isDeclaration() ? 0 :
 647                    (VE.getValueID(GV.getInitializer()) + 1));
 648     Vals.push_back(getEncodedLinkage(GV));
 649     Vals.push_back(Log2_32(GV.getAlignment())+1);
 650     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
 651     if (GV.isThreadLocal() ||
 652         GV.getVisibility() != GlobalValue::DefaultVisibility ||
 653         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
 654         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
 655         GV.hasComdat()) {
 656       Vals.push_back(getEncodedVisibility(GV));
 657       Vals.push_back(getEncodedThreadLocalMode(GV));
 658       Vals.push_back(GV.hasUnnamedAddr());
 659       Vals.push_back(GV.isExternallyInitialized());
 660       Vals.push_back(getEncodedDLLStorageClass(GV));
 661       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
 662     } else {
 663       AbbrevToUse = SimpleGVarAbbrev;
 664     }
 665
 666     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 667     Vals.clear();
 668   }
 669
 670   // Emit the function proto information.
 671   for (const Function &F : *M) {
 672     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 673     //             section, visibility, gc, unnamed_addr, prologuedata,
 674     //             dllstorageclass, comdat, prefixdata]
 675     Vals.push_back(VE.getTypeID(F.getType()));
 676     Vals.push_back(F.getCallingConv());
 677     Vals.push_back(F.isDeclaration());
 678     Vals.push_back(getEncodedLinkage(F));
 679     Vals.push_back(VE.getAttributeID(F.getAttributes()));
 680     Vals.push_back(Log2_32(F.getAlignment())+1);
 681     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
 682     Vals.push_back(getEncodedVisibility(F));
 683     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
 684     Vals.push_back(F.hasUnnamedAddr());
 685     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
 686                                        : 0);
 687     Vals.push_back(getEncodedDLLStorageClass(F));
 688     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
 689     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
 690                                      : 0);
 691
 692     unsigned AbbrevToUse = 0;
 693     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 694     Vals.clear();
 695   }
 696
 697   // Emit the alias information.
 698   for (const GlobalAlias &A : M->aliases()) {
 699     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 700     Vals.push_back(VE.getTypeID(A.getType()));
 701     Vals.push_back(VE.getValueID(A.getAliasee()));
 702     Vals.push_back(getEncodedLinkage(A));
 703     Vals.push_back(getEncodedVisibility(A));
 704     Vals.push_back(getEncodedDLLStorageClass(A));
 705     Vals.push_back(getEncodedThreadLocalMode(A));
 706     Vals.push_back(A.hasUnnamedAddr());
 707     unsigned AbbrevToUse = 0;
 708     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 709     Vals.clear();
 710   }
 711 }
 712
 713 static uint64_t GetOptimizationFlags(const Value *V) {
 714   uint64_t Flags = 0;
 715
 716   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
 717     if (OBO->hasNoSignedWrap())
 718       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 719     if (OBO->hasNoUnsignedWrap())
 720       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 721   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
 722     if (PEO->isExact())
 723       Flags |= 1 << bitc::PEO_EXACT;
 724   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
 725     if (FPMO->hasUnsafeAlgebra())
 726       Flags |= FastMathFlags::UnsafeAlgebra;
 727     if (FPMO->hasNoNaNs())
 728       Flags |= FastMathFlags::NoNaNs;
 729     if (FPMO->hasNoInfs())
 730       Flags |= FastMathFlags::NoInfs;
 731     if (FPMO->hasNoSignedZeros())
 732       Flags |= FastMathFlags::NoSignedZeros;
 733     if (FPMO->hasAllowReciprocal())
 734       Flags |= FastMathFlags::AllowReciprocal;
 735   }
 736
 737   return Flags;
 738 }
 739
 740 static void WriteValueAsMetadataImpl(const ValueAsMetadata *MD,
 741                                      const ValueEnumerator &VE,
 742                                      BitstreamWriter &Stream,
 743                                      SmallVectorImpl<uint64_t> &Record,
 744                                      unsigned Code) {
 745   // Mimic an MDNode with a value as one operand.
 746   Value *V = MD->getValue();
 747   Record.push_back(VE.getTypeID(V->getType()));
 748   Record.push_back(VE.getValueID(V));
 749   Stream.EmitRecord(Code, Record, 0);
 750   Record.clear();
 751 }
 752
 753 static void WriteLocalAsMetadata(const LocalAsMetadata *MD,
 754                                  const ValueEnumerator &VE,
 755                                  BitstreamWriter &Stream,
 756                                  SmallVectorImpl<uint64_t> &Record) {
 757   WriteValueAsMetadataImpl(MD, VE, Stream, Record, bitc::METADATA_FN_NODE);
 758 }
 759
 760 static void WriteConstantAsMetadata(const ConstantAsMetadata *MD,
 761                                     const ValueEnumerator &VE,
 762                                     BitstreamWriter &Stream,
 763                                     SmallVectorImpl<uint64_t> &Record) {
 764   WriteValueAsMetadataImpl(MD, VE, Stream, Record, bitc::METADATA_NODE);
 765 }
 766
 767 static void WriteMDNode(const MDNode *N,
 768                         const ValueEnumerator &VE,
 769                         BitstreamWriter &Stream,
 770                         SmallVectorImpl<uint64_t> &Record) {
 771   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 772     Metadata *MD = N->getOperand(i);
 773     if (!MD) {
 774       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 775       Record.push_back(0);
 776       continue;
 777     }
 778     if (auto *V = dyn_cast<ConstantAsMetadata>(MD)) {
 779       Record.push_back(VE.getTypeID(V->getValue()->getType()));
 780       Record.push_back(VE.getValueID(V->getValue()));
 781       continue;
 782     }
 783     assert(!isa<LocalAsMetadata>(MD) && "Unexpected function-local metadata");
 784     Record.push_back(VE.getTypeID(Type::getMetadataTy(N->getContext())));
 785     Record.push_back(VE.getMetadataID(MD));
 786   }
 787   Stream.EmitRecord(bitc::METADATA_NODE, Record, 0);
 788   Record.clear();
 789 }
 790
 791 static void WriteModuleMetadata(const Module *M,
 792                                 const ValueEnumerator &VE,
 793                                 BitstreamWriter &Stream) {
 794   const auto &MDs = VE.getMDs();
 795   bool StartedMetadataBlock = false;
 796   unsigned MDSAbbrev = 0;
 797   SmallVector<uint64_t, 64> Record;
 798   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 799     if (const MDNode *N = dyn_cast<MDNode>(MDs[i])) {
 800       if (!StartedMetadataBlock) {
 801         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 802         StartedMetadataBlock = true;
 803       }
 804       WriteMDNode(N, VE, Stream, Record);
 805     } else if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MDs[i])) {
 806       if (!StartedMetadataBlock) {
 807         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 808         StartedMetadataBlock = true;
 809       }
 810       WriteConstantAsMetadata(MDC, VE, Stream, Record);
 811     } else if (const MDString *MDS = dyn_cast<MDString>(MDs[i])) {
 812       if (!StartedMetadataBlock) {
 813         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 814
 815         // Abbrev for METADATA_STRING.
 816         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 817         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 818         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 819         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 820         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 821         StartedMetadataBlock = true;
 822       }
 823
 824       // Code: [strchar x N]
 825       Record.append(MDS->begin(), MDS->end());
 826
 827       // Emit the finished record.
 828       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 829       Record.clear();
 830     }
 831   }
 832
 833   // Write named metadata.
 834   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 835        E = M->named_metadata_end(); I != E; ++I) {
 836     const NamedMDNode *NMD = I;
 837     if (!StartedMetadataBlock)  {
 838       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 839       StartedMetadataBlock = true;
 840     }
 841
 842     // Write name.
 843     StringRef Str = NMD->getName();
 844     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 845       Record.push_back(Str[i]);
 846     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 847     Record.clear();
 848
 849     // Write named metadata operands.
 850     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 851       Record.push_back(VE.getMetadataID(NMD->getOperand(i)));
 852     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 853     Record.clear();
 854   }
 855
 856   if (StartedMetadataBlock)
 857     Stream.ExitBlock();
 858 }
 859
 860 static void WriteFunctionLocalMetadata(const Function &F,
 861                                        const ValueEnumerator &VE,
 862                                        BitstreamWriter &Stream) {
 863   bool StartedMetadataBlock = false;
 864   SmallVector<uint64_t, 64> Record;
 865   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
 866       VE.getFunctionLocalMDs();
 867   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 868     assert(MDs[i] && "Expected valid function-local metadata");
 869     if (!StartedMetadataBlock) {
 870       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 871       StartedMetadataBlock = true;
 872     }
 873     WriteLocalAsMetadata(MDs[i], VE, Stream, Record);
 874   }
 875
 876   if (StartedMetadataBlock)
 877     Stream.ExitBlock();
 878 }
 879
 880 static void WriteMetadataAttachment(const Function &F,
 881                                     const ValueEnumerator &VE,
 882                                     BitstreamWriter &Stream) {
 883   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 884
 885   SmallVector<uint64_t, 64> Record;
 886
 887   // Write metadata attachments
 888   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 889   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
 890
 891   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 892     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 893          I != E; ++I) {
 894       MDs.clear();
 895       I->getAllMetadataOtherThanDebugLoc(MDs);
 896
 897       // If no metadata, ignore instruction.
 898       if (MDs.empty()) continue;
 899
 900       Record.push_back(VE.getInstructionID(I));
 901
 902       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 903         Record.push_back(MDs[i].first);
 904         Record.push_back(VE.getMetadataID(MDs[i].second));
 905       }
 906       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 907       Record.clear();
 908     }
 909
 910   Stream.ExitBlock();
 911 }
 912
 913 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 914   SmallVector<uint64_t, 64> Record;
 915
 916   // Write metadata kinds
 917   // METADATA_KIND - [n x [id, name]]
 918   SmallVector<StringRef, 8> Names;
 919   M->getMDKindNames(Names);
 920
 921   if (Names.empty()) return;
 922
 923   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 924
 925   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 926     Record.push_back(MDKindID);
 927     StringRef KName = Names[MDKindID];
 928     Record.append(KName.begin(), KName.end());
 929
 930     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 931     Record.clear();
 932   }
 933
 934   Stream.ExitBlock();
 935 }
 936
 937 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 938   if ((int64_t)V >= 0)
 939     Vals.push_back(V << 1);
 940   else
 941     Vals.push_back((-V << 1) | 1);
 942 }
 943
 944 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 945                            const ValueEnumerator &VE,
 946                            BitstreamWriter &Stream, bool isGlobal) {
 947   if (FirstVal == LastVal) return;
 948
 949   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 950
 951   unsigned AggregateAbbrev = 0;
 952   unsigned String8Abbrev = 0;
 953   unsigned CString7Abbrev = 0;
 954   unsigned CString6Abbrev = 0;
 955   // If this is a constant pool for the module, emit module-specific abbrevs.
 956   if (isGlobal) {
 957     // Abbrev for CST_CODE_AGGREGATE.
 958     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 959     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 960     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 961     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 962     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 963
 964     // Abbrev for CST_CODE_STRING.
 965     Abbv = new BitCodeAbbrev();
 966     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 967     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 968     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 969     String8Abbrev = Stream.EmitAbbrev(Abbv);
 970     // Abbrev for CST_CODE_CSTRING.
 971     Abbv = new BitCodeAbbrev();
 972     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 973     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 974     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 975     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 976     // Abbrev for CST_CODE_CSTRING.
 977     Abbv = new BitCodeAbbrev();
 978     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 979     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 980     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 981     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 982   }
 983
 984   SmallVector<uint64_t, 64> Record;
 985
 986   const ValueEnumerator::ValueList &Vals = VE.getValues();
 987   Type *LastTy = nullptr;
 988   for (unsigned i = FirstVal; i != LastVal; ++i) {
 989     const Value *V = Vals[i].first;
 990     // If we need to switch types, do so now.
 991     if (V->getType() != LastTy) {
 992       LastTy = V->getType();
 993       Record.push_back(VE.getTypeID(LastTy));
 994       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 995                         CONSTANTS_SETTYPE_ABBREV);
 996       Record.clear();
 997     }
 998
 999     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1000       Record.push_back(unsigned(IA->hasSideEffects()) |
1001                        unsigned(IA->isAlignStack()) << 1 |
1002                        unsigned(IA->getDialect()&1) << 2);
1003
1004       // Add the asm string.
1005       const std::string &AsmStr = IA->getAsmString();
1006       Record.push_back(AsmStr.size());
1007       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
1008         Record.push_back(AsmStr[i]);
1009
1010       // Add the constraint string.
1011       const std::string &ConstraintStr = IA->getConstraintString();
1012       Record.push_back(ConstraintStr.size());
1013       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
1014         Record.push_back(ConstraintStr[i]);
1015       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1016       Record.clear();
1017       continue;
1018     }
1019     const Constant *C = cast<Constant>(V);
1020     unsigned Code = -1U;
1021     unsigned AbbrevToUse = 0;
1022     if (C->isNullValue()) {
1023       Code = bitc::CST_CODE_NULL;
1024     } else if (isa<UndefValue>(C)) {
1025       Code = bitc::CST_CODE_UNDEF;
1026     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1027       if (IV->getBitWidth() <= 64) {
1028         uint64_t V = IV->getSExtValue();
1029         emitSignedInt64(Record, V);
1030         Code = bitc::CST_CODE_INTEGER;
1031         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1032       } else {                             // Wide integers, > 64 bits in size.
1033         // We have an arbitrary precision integer value to write whose
1034         // bit width is > 64. However, in canonical unsigned integer
1035         // format it is likely that the high bits are going to be zero.
1036         // So, we only write the number of active words.
1037         unsigned NWords = IV->getValue().getActiveWords();
1038         const uint64_t *RawWords = IV->getValue().getRawData();
1039         for (unsigned i = 0; i != NWords; ++i) {
1040           emitSignedInt64(Record, RawWords[i]);
1041         }
1042         Code = bitc::CST_CODE_WIDE_INTEGER;
1043       }
1044     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1045       Code = bitc::CST_CODE_FLOAT;
1046       Type *Ty = CFP->getType();
1047       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1048         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1049       } else if (Ty->isX86_FP80Ty()) {
1050         // api needed to prevent premature destruction
1051         // bits are not in the same order as a normal i80 APInt, compensate.
1052         APInt api = CFP->getValueAPF().bitcastToAPInt();
1053         const uint64_t *p = api.getRawData();
1054         Record.push_back((p[1] << 48) | (p[0] >> 16));
1055         Record.push_back(p[0] & 0xffffLL);
1056       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1057         APInt api = CFP->getValueAPF().bitcastToAPInt();
1058         const uint64_t *p = api.getRawData();
1059         Record.push_back(p[0]);
1060         Record.push_back(p[1]);
1061       } else {
1062         assert (0 && "Unknown FP type!");
1063       }
1064     } else if (isa<ConstantDataSequential>(C) &&
1065                cast<ConstantDataSequential>(C)->isString()) {
1066       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1067       // Emit constant strings specially.
1068       unsigned NumElts = Str->getNumElements();
1069       // If this is a null-terminated string, use the denser CSTRING encoding.
1070       if (Str->isCString()) {
1071         Code = bitc::CST_CODE_CSTRING;
1072         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1073       } else {
1074         Code = bitc::CST_CODE_STRING;
1075         AbbrevToUse = String8Abbrev;
1076       }
1077       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1078       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1079       for (unsigned i = 0; i != NumElts; ++i) {
1080         unsigned char V = Str->getElementAsInteger(i);
1081         Record.push_back(V);
1082         isCStr7 &= (V & 128) == 0;
1083         if (isCStrChar6)
1084           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1085       }
1086
1087       if (isCStrChar6)
1088         AbbrevToUse = CString6Abbrev;
1089       else if (isCStr7)
1090         AbbrevToUse = CString7Abbrev;
1091     } else if (const ConstantDataSequential *CDS =
1092                   dyn_cast<ConstantDataSequential>(C)) {
1093       Code = bitc::CST_CODE_DATA;
1094       Type *EltTy = CDS->getType()->getElementType();
1095       if (isa<IntegerType>(EltTy)) {
1096         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1097           Record.push_back(CDS->getElementAsInteger(i));
1098       } else if (EltTy->isFloatTy()) {
1099         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1100           union { float F; uint32_t I; };
1101           F = CDS->getElementAsFloat(i);
1102           Record.push_back(I);
1103         }
1104       } else {
1105         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1106         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1107           union { double F; uint64_t I; };
1108           F = CDS->getElementAsDouble(i);
1109           Record.push_back(I);
1110         }
1111       }
1112     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1113                isa<ConstantVector>(C)) {
1114       Code = bitc::CST_CODE_AGGREGATE;
1115       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1116         Record.push_back(VE.getValueID(C->getOperand(i)));
1117       AbbrevToUse = AggregateAbbrev;
1118     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1119       switch (CE->getOpcode()) {
1120       default:
1121         if (Instruction::isCast(CE->getOpcode())) {
1122           Code = bitc::CST_CODE_CE_CAST;
1123           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1124           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1125           Record.push_back(VE.getValueID(C->getOperand(0)));
1126           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1127         } else {
1128           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1129           Code = bitc::CST_CODE_CE_BINOP;
1130           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1131           Record.push_back(VE.getValueID(C->getOperand(0)));
1132           Record.push_back(VE.getValueID(C->getOperand(1)));
1133           uint64_t Flags = GetOptimizationFlags(CE);
1134           if (Flags != 0)
1135             Record.push_back(Flags);
1136         }
1137         break;
1138       case Instruction::GetElementPtr:
1139         Code = bitc::CST_CODE_CE_GEP;
1140         if (cast<GEPOperator>(C)->isInBounds())
1141           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1142         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1143           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1144           Record.push_back(VE.getValueID(C->getOperand(i)));
1145         }
1146         break;
1147       case Instruction::Select:
1148         Code = bitc::CST_CODE_CE_SELECT;
1149         Record.push_back(VE.getValueID(C->getOperand(0)));
1150         Record.push_back(VE.getValueID(C->getOperand(1)));
1151         Record.push_back(VE.getValueID(C->getOperand(2)));
1152         break;
1153       case Instruction::ExtractElement:
1154         Code = bitc::CST_CODE_CE_EXTRACTELT;
1155         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1156         Record.push_back(VE.getValueID(C->getOperand(0)));
1157         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1158         Record.push_back(VE.getValueID(C->getOperand(1)));
1159         break;
1160       case Instruction::InsertElement:
1161         Code = bitc::CST_CODE_CE_INSERTELT;
1162         Record.push_back(VE.getValueID(C->getOperand(0)));
1163         Record.push_back(VE.getValueID(C->getOperand(1)));
1164         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1165         Record.push_back(VE.getValueID(C->getOperand(2)));
1166         break;
1167       case Instruction::ShuffleVector:
1168         // If the return type and argument types are the same, this is a
1169         // standard shufflevector instruction.  If the types are different,
1170         // then the shuffle is widening or truncating the input vectors, and
1171         // the argument type must also be encoded.
1172         if (C->getType() == C->getOperand(0)->getType()) {
1173           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1174         } else {
1175           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1176           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1177         }
1178         Record.push_back(VE.getValueID(C->getOperand(0)));
1179         Record.push_back(VE.getValueID(C->getOperand(1)));
1180         Record.push_back(VE.getValueID(C->getOperand(2)));
1181         break;
1182       case Instruction::ICmp:
1183       case Instruction::FCmp:
1184         Code = bitc::CST_CODE_CE_CMP;
1185         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1186         Record.push_back(VE.getValueID(C->getOperand(0)));
1187         Record.push_back(VE.getValueID(C->getOperand(1)));
1188         Record.push_back(CE->getPredicate());
1189         break;
1190       }
1191     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1192       Code = bitc::CST_CODE_BLOCKADDRESS;
1193       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1194       Record.push_back(VE.getValueID(BA->getFunction()));
1195       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1196     } else {
1197 #ifndef NDEBUG
1198       C->dump();
1199 #endif
1200       llvm_unreachable("Unknown constant!");
1201     }
1202     Stream.EmitRecord(Code, Record, AbbrevToUse);
1203     Record.clear();
1204   }
1205
1206   Stream.ExitBlock();
1207 }
1208
1209 static void WriteModuleConstants(const ValueEnumerator &VE,
1210                                  BitstreamWriter &Stream) {
1211   const ValueEnumerator::ValueList &Vals = VE.getValues();
1212
1213   // Find the first constant to emit, which is the first non-globalvalue value.
1214   // We know globalvalues have been emitted by WriteModuleInfo.
1215   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1216     if (!isa<GlobalValue>(Vals[i].first)) {
1217       WriteConstants(i, Vals.size(), VE, Stream, true);
1218       return;
1219     }
1220   }
1221 }
1222
1223 /// PushValueAndType - The file has to encode both the value and type id for
1224 /// many values, because we need to know what type to create for forward
1225 /// references.  However, most operands are not forward references, so this type
1226 /// field is not needed.
1227 ///
1228 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1229 /// instruction ID, then it is a forward reference, and it also includes the
1230 /// type ID.  The value ID that is written is encoded relative to the InstID.
1231 static bool PushValueAndType(const Value *V, unsigned InstID,
1232                              SmallVectorImpl<unsigned> &Vals,
1233                              ValueEnumerator &VE) {
1234   unsigned ValID = VE.getValueID(V);
1235   // Make encoding relative to the InstID.
1236   Vals.push_back(InstID - ValID);
1237   if (ValID >= InstID) {
1238     Vals.push_back(VE.getTypeID(V->getType()));
1239     return true;
1240   }
1241   return false;
1242 }
1243
1244 /// pushValue - Like PushValueAndType, but where the type of the value is
1245 /// omitted (perhaps it was already encoded in an earlier operand).
1246 static void pushValue(const Value *V, unsigned InstID,
1247                       SmallVectorImpl<unsigned> &Vals,
1248                       ValueEnumerator &VE) {
1249   unsigned ValID = VE.getValueID(V);
1250   Vals.push_back(InstID - ValID);
1251 }
1252
1253 static void pushValueSigned(const Value *V, unsigned InstID,
1254                             SmallVectorImpl<uint64_t> &Vals,
1255                             ValueEnumerator &VE) {
1256   unsigned ValID = VE.getValueID(V);
1257   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1258   emitSignedInt64(Vals, diff);
1259 }
1260
1261 /// WriteInstruction - Emit an instruction to the specified stream.
1262 static void WriteInstruction(const Instruction &I, unsigned InstID,
1263                              ValueEnumerator &VE, BitstreamWriter &Stream,
1264                              SmallVectorImpl<unsigned> &Vals) {
1265   unsigned Code = 0;
1266   unsigned AbbrevToUse = 0;
1267   VE.setInstructionID(&I);
1268   switch (I.getOpcode()) {
1269   default:
1270     if (Instruction::isCast(I.getOpcode())) {
1271       Code = bitc::FUNC_CODE_INST_CAST;
1272       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1273         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1274       Vals.push_back(VE.getTypeID(I.getType()));
1275       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1276     } else {
1277       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1278       Code = bitc::FUNC_CODE_INST_BINOP;
1279       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1280         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1281       pushValue(I.getOperand(1), InstID, Vals, VE);
1282       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1283       uint64_t Flags = GetOptimizationFlags(&I);
1284       if (Flags != 0) {
1285         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1286           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1287         Vals.push_back(Flags);
1288       }
1289     }
1290     break;
1291
1292   case Instruction::GetElementPtr:
1293     Code = bitc::FUNC_CODE_INST_GEP;
1294     if (cast<GEPOperator>(&I)->isInBounds())
1295       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1296     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1297       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1298     break;
1299   case Instruction::ExtractValue: {
1300     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1301     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1302     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1303     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1304       Vals.push_back(*i);
1305     break;
1306   }
1307   case Instruction::InsertValue: {
1308     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1309     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1310     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1311     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1312     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1313       Vals.push_back(*i);
1314     break;
1315   }
1316   case Instruction::Select:
1317     Code = bitc::FUNC_CODE_INST_VSELECT;
1318     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1319     pushValue(I.getOperand(2), InstID, Vals, VE);
1320     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1321     break;
1322   case Instruction::ExtractElement:
1323     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1324     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1325     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1326     break;
1327   case Instruction::InsertElement:
1328     Code = bitc::FUNC_CODE_INST_INSERTELT;
1329     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1330     pushValue(I.getOperand(1), InstID, Vals, VE);
1331     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1332     break;
1333   case Instruction::ShuffleVector:
1334     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1335     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1336     pushValue(I.getOperand(1), InstID, Vals, VE);
1337     pushValue(I.getOperand(2), InstID, Vals, VE);
1338     break;
1339   case Instruction::ICmp:
1340   case Instruction::FCmp:
1341     // compare returning Int1Ty or vector of Int1Ty
1342     Code = bitc::FUNC_CODE_INST_CMP2;
1343     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1344     pushValue(I.getOperand(1), InstID, Vals, VE);
1345     Vals.push_back(cast<CmpInst>(I).getPredicate());
1346     break;
1347
1348   case Instruction::Ret:
1349     {
1350       Code = bitc::FUNC_CODE_INST_RET;
1351       unsigned NumOperands = I.getNumOperands();
1352       if (NumOperands == 0)
1353         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1354       else if (NumOperands == 1) {
1355         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1356           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1357       } else {
1358         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1359           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1360       }
1361     }
1362     break;
1363   case Instruction::Br:
1364     {
1365       Code = bitc::FUNC_CODE_INST_BR;
1366       const BranchInst &II = cast<BranchInst>(I);
1367       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1368       if (II.isConditional()) {
1369         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1370         pushValue(II.getCondition(), InstID, Vals, VE);
1371       }
1372     }
1373     break;
1374   case Instruction::Switch:
1375     {
1376       Code = bitc::FUNC_CODE_INST_SWITCH;
1377       const SwitchInst &SI = cast<SwitchInst>(I);
1378       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1379       pushValue(SI.getCondition(), InstID, Vals, VE);
1380       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1381       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1382            i != e; ++i) {
1383         Vals.push_back(VE.getValueID(i.getCaseValue()));
1384         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1385       }
1386     }
1387     break;
1388   case Instruction::IndirectBr:
1389     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1390     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1391     // Encode the address operand as relative, but not the basic blocks.
1392     pushValue(I.getOperand(0), InstID, Vals, VE);
1393     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1394       Vals.push_back(VE.getValueID(I.getOperand(i)));
1395     break;
1396
1397   case Instruction::Invoke: {
1398     const InvokeInst *II = cast<InvokeInst>(&I);
1399     const Value *Callee(II->getCalledValue());
1400     PointerType *PTy = cast<PointerType>(Callee->getType());
1401     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1402     Code = bitc::FUNC_CODE_INST_INVOKE;
1403
1404     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1405     Vals.push_back(II->getCallingConv());
1406     Vals.push_back(VE.getValueID(II->getNormalDest()));
1407     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1408     PushValueAndType(Callee, InstID, Vals, VE);
1409
1410     // Emit value #'s for the fixed parameters.
1411     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1412       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1413
1414     // Emit type/value pairs for varargs params.
1415     if (FTy->isVarArg()) {
1416       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1417            i != e; ++i)
1418         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1419     }
1420     break;
1421   }
1422   case Instruction::Resume:
1423     Code = bitc::FUNC_CODE_INST_RESUME;
1424     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1425     break;
1426   case Instruction::Unreachable:
1427     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1428     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1429     break;
1430
1431   case Instruction::PHI: {
1432     const PHINode &PN = cast<PHINode>(I);
1433     Code = bitc::FUNC_CODE_INST_PHI;
1434     // With the newer instruction encoding, forward references could give
1435     // negative valued IDs.  This is most common for PHIs, so we use
1436     // signed VBRs.
1437     SmallVector<uint64_t, 128> Vals64;
1438     Vals64.push_back(VE.getTypeID(PN.getType()));
1439     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1440       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1441       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1442     }
1443     // Emit a Vals64 vector and exit.
1444     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1445     Vals64.clear();
1446     return;
1447   }
1448
1449   case Instruction::LandingPad: {
1450     const LandingPadInst &LP = cast<LandingPadInst>(I);
1451     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1452     Vals.push_back(VE.getTypeID(LP.getType()));
1453     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1454     Vals.push_back(LP.isCleanup());
1455     Vals.push_back(LP.getNumClauses());
1456     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1457       if (LP.isCatch(I))
1458         Vals.push_back(LandingPadInst::Catch);
1459       else
1460         Vals.push_back(LandingPadInst::Filter);
1461       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1462     }
1463     break;
1464   }
1465
1466   case Instruction::Alloca: {
1467     Code = bitc::FUNC_CODE_INST_ALLOCA;
1468     Vals.push_back(VE.getTypeID(I.getType()));
1469     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1470     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1471     const AllocaInst &AI = cast<AllocaInst>(I);
1472     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
1473     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
1474            "not enough bits for maximum alignment");
1475     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
1476     AlignRecord |= AI.isUsedWithInAlloca() << 5;
1477     Vals.push_back(AlignRecord);
1478     break;
1479   }
1480
1481   case Instruction::Load:
1482     if (cast<LoadInst>(I).isAtomic()) {
1483       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1484       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1485     } else {
1486       Code = bitc::FUNC_CODE_INST_LOAD;
1487       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1488         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1489     }
1490     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1491     Vals.push_back(cast<LoadInst>(I).isVolatile());
1492     if (cast<LoadInst>(I).isAtomic()) {
1493       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1494       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1495     }
1496     break;
1497   case Instruction::Store:
1498     if (cast<StoreInst>(I).isAtomic())
1499       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1500     else
1501       Code = bitc::FUNC_CODE_INST_STORE;
1502     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1503     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1504     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1505     Vals.push_back(cast<StoreInst>(I).isVolatile());
1506     if (cast<StoreInst>(I).isAtomic()) {
1507       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1508       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1509     }
1510     break;
1511   case Instruction::AtomicCmpXchg:
1512     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1513     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1514     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1515     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1516     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1517     Vals.push_back(GetEncodedOrdering(
1518                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
1519     Vals.push_back(GetEncodedSynchScope(
1520                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1521     Vals.push_back(GetEncodedOrdering(
1522                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
1523     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
1524     break;
1525   case Instruction::AtomicRMW:
1526     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1527     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1528     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1529     Vals.push_back(GetEncodedRMWOperation(
1530                      cast<AtomicRMWInst>(I).getOperation()));
1531     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1532     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1533     Vals.push_back(GetEncodedSynchScope(
1534                      cast<AtomicRMWInst>(I).getSynchScope()));
1535     break;
1536   case Instruction::Fence:
1537     Code = bitc::FUNC_CODE_INST_FENCE;
1538     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1539     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1540     break;
1541   case Instruction::Call: {
1542     const CallInst &CI = cast<CallInst>(I);
1543     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1544     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1545
1546     Code = bitc::FUNC_CODE_INST_CALL;
1547
1548     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1549     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()) |
1550                    unsigned(CI.isMustTailCall()) << 14);
1551     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1552
1553     // Emit value #'s for the fixed parameters.
1554     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1555       // Check for labels (can happen with asm labels).
1556       if (FTy->getParamType(i)->isLabelTy())
1557         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1558       else
1559         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1560     }
1561
1562     // Emit type/value pairs for varargs params.
1563     if (FTy->isVarArg()) {
1564       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1565            i != e; ++i)
1566         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1567     }
1568     break;
1569   }
1570   case Instruction::VAArg:
1571     Code = bitc::FUNC_CODE_INST_VAARG;
1572     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1573     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1574     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1575     break;
1576   }
1577
1578   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1579   Vals.clear();
1580 }
1581
1582 // Emit names for globals/functions etc.
1583 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1584                                   const ValueEnumerator &VE,
1585                                   BitstreamWriter &Stream) {
1586   if (VST.empty()) return;
1587   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1588
1589   // FIXME: Set up the abbrev, we know how many values there are!
1590   // FIXME: We know if the type names can use 7-bit ascii.
1591   SmallVector<unsigned, 64> NameVals;
1592
1593   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1594        SI != SE; ++SI) {
1595
1596     const ValueName &Name = *SI;
1597
1598     // Figure out the encoding to use for the name.
1599     bool is7Bit = true;
1600     bool isChar6 = true;
1601     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1602          C != E; ++C) {
1603       if (isChar6)
1604         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1605       if ((unsigned char)*C & 128) {
1606         is7Bit = false;
1607         break;  // don't bother scanning the rest.
1608       }
1609     }
1610
1611     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1612
1613     // VST_ENTRY:   [valueid, namechar x N]
1614     // VST_BBENTRY: [bbid, namechar x N]
1615     unsigned Code;
1616     if (isa<BasicBlock>(SI->getValue())) {
1617       Code = bitc::VST_CODE_BBENTRY;
1618       if (isChar6)
1619         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1620     } else {
1621       Code = bitc::VST_CODE_ENTRY;
1622       if (isChar6)
1623         AbbrevToUse = VST_ENTRY_6_ABBREV;
1624       else if (is7Bit)
1625         AbbrevToUse = VST_ENTRY_7_ABBREV;
1626     }
1627
1628     NameVals.push_back(VE.getValueID(SI->getValue()));
1629     for (const char *P = Name.getKeyData(),
1630          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1631       NameVals.push_back((unsigned char)*P);
1632
1633     // Emit the finished record.
1634     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1635     NameVals.clear();
1636   }
1637   Stream.ExitBlock();
1638 }
1639
1640 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
1641                          BitstreamWriter &Stream) {
1642   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
1643   unsigned Code;
1644   if (isa<BasicBlock>(Order.V))
1645     Code = bitc::USELIST_CODE_BB;
1646   else
1647     Code = bitc::USELIST_CODE_DEFAULT;
1648
1649   SmallVector<uint64_t, 64> Record;
1650   for (unsigned I : Order.Shuffle)
1651     Record.push_back(I);
1652   Record.push_back(VE.getValueID(Order.V));
1653   Stream.EmitRecord(Code, Record);
1654 }
1655
1656 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
1657                               BitstreamWriter &Stream) {
1658   auto hasMore = [&]() {
1659     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
1660   };
1661   if (!hasMore())
1662     // Nothing to do.
1663     return;
1664
1665   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1666   while (hasMore()) {
1667     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
1668     VE.UseListOrders.pop_back();
1669   }
1670   Stream.ExitBlock();
1671 }
1672
1673 /// WriteFunction - Emit a function body to the module stream.
1674 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1675                           BitstreamWriter &Stream) {
1676   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1677   VE.incorporateFunction(F);
1678
1679   SmallVector<unsigned, 64> Vals;
1680
1681   // Emit the number of basic blocks, so the reader can create them ahead of
1682   // time.
1683   Vals.push_back(VE.getBasicBlocks().size());
1684   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1685   Vals.clear();
1686
1687   // If there are function-local constants, emit them now.
1688   unsigned CstStart, CstEnd;
1689   VE.getFunctionConstantRange(CstStart, CstEnd);
1690   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1691
1692   // If there is function-local metadata, emit it now.
1693   WriteFunctionLocalMetadata(F, VE, Stream);
1694
1695   // Keep a running idea of what the instruction ID is.
1696   unsigned InstID = CstEnd;
1697
1698   bool NeedsMetadataAttachment = false;
1699
1700   DebugLoc LastDL;
1701
1702   // Finally, emit all the instructions, in order.
1703   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1704     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1705          I != E; ++I) {
1706       WriteInstruction(*I, InstID, VE, Stream, Vals);
1707
1708       if (!I->getType()->isVoidTy())
1709         ++InstID;
1710
1711       // If the instruction has metadata, write a metadata attachment later.
1712       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1713
1714       // If the instruction has a debug location, emit it.
1715       DebugLoc DL = I->getDebugLoc();
1716       if (DL.isUnknown()) {
1717         // nothing todo.
1718       } else if (DL == LastDL) {
1719         // Just repeat the same debug loc as last time.
1720         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1721       } else {
1722         MDNode *Scope, *IA;
1723         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1724         assert(Scope && "Expected valid scope");
1725
1726         Vals.push_back(DL.getLine());
1727         Vals.push_back(DL.getCol());
1728         Vals.push_back(Scope ? VE.getMetadataID(Scope) + 1 : 0);
1729         Vals.push_back(IA ? VE.getMetadataID(IA) + 1 : 0);
1730         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1731         Vals.clear();
1732
1733         LastDL = DL;
1734       }
1735     }
1736
1737   // Emit names for all the instructions etc.
1738   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1739
1740   if (NeedsMetadataAttachment)
1741     WriteMetadataAttachment(F, VE, Stream);
1742   if (shouldPreserveBitcodeUseListOrder())
1743     WriteUseListBlock(&F, VE, Stream);
1744   VE.purgeFunction();
1745   Stream.ExitBlock();
1746 }
1747
1748 // Emit blockinfo, which defines the standard abbreviations etc.
1749 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1750   // We only want to emit block info records for blocks that have multiple
1751   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1752   // Other blocks can define their abbrevs inline.
1753   Stream.EnterBlockInfoBlock(2);
1754
1755   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1756     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1757     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1758     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1759     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1760     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1761     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1762                                    Abbv) != VST_ENTRY_8_ABBREV)
1763       llvm_unreachable("Unexpected abbrev ordering!");
1764   }
1765
1766   { // 7-bit fixed width VST_ENTRY strings.
1767     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1768     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1769     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1770     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1771     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1772     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1773                                    Abbv) != VST_ENTRY_7_ABBREV)
1774       llvm_unreachable("Unexpected abbrev ordering!");
1775   }
1776   { // 6-bit char6 VST_ENTRY strings.
1777     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1778     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1779     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1780     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1781     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1782     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1783                                    Abbv) != VST_ENTRY_6_ABBREV)
1784       llvm_unreachable("Unexpected abbrev ordering!");
1785   }
1786   { // 6-bit char6 VST_BBENTRY strings.
1787     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1788     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1789     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1790     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1791     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1792     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1793                                    Abbv) != VST_BBENTRY_6_ABBREV)
1794       llvm_unreachable("Unexpected abbrev ordering!");
1795   }
1796
1797
1798
1799   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1800     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1801     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1802     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1803                               Log2_32_Ceil(VE.getTypes().size()+1)));
1804     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1805                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1806       llvm_unreachable("Unexpected abbrev ordering!");
1807   }
1808
1809   { // INTEGER abbrev for CONSTANTS_BLOCK.
1810     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1811     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1812     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1813     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1814                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1815       llvm_unreachable("Unexpected abbrev ordering!");
1816   }
1817
1818   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1819     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1820     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1821     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1822     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1823                               Log2_32_Ceil(VE.getTypes().size()+1)));
1824     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1825
1826     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1827                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1828       llvm_unreachable("Unexpected abbrev ordering!");
1829   }
1830   { // NULL abbrev for CONSTANTS_BLOCK.
1831     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1832     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1833     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1834                                    Abbv) != CONSTANTS_NULL_Abbrev)
1835       llvm_unreachable("Unexpected abbrev ordering!");
1836   }
1837
1838   // FIXME: This should only use space for first class types!
1839
1840   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1841     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1842     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1843     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1844     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1845     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1846     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1847                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1848       llvm_unreachable("Unexpected abbrev ordering!");
1849   }
1850   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1851     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1852     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1853     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1854     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1855     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1856     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1857                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1858       llvm_unreachable("Unexpected abbrev ordering!");
1859   }
1860   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1861     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1862     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1863     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1864     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1865     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1866     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1867     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1868                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1869       llvm_unreachable("Unexpected abbrev ordering!");
1870   }
1871   { // INST_CAST abbrev for FUNCTION_BLOCK.
1872     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1873     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1874     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1875     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1876                               Log2_32_Ceil(VE.getTypes().size()+1)));
1877     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1878     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1879                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1880       llvm_unreachable("Unexpected abbrev ordering!");
1881   }
1882
1883   { // INST_RET abbrev for FUNCTION_BLOCK.
1884     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1885     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1886     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1887                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1888       llvm_unreachable("Unexpected abbrev ordering!");
1889   }
1890   { // INST_RET abbrev for FUNCTION_BLOCK.
1891     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1892     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1893     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1894     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1895                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1896       llvm_unreachable("Unexpected abbrev ordering!");
1897   }
1898   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1899     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1900     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1901     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1902                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1903       llvm_unreachable("Unexpected abbrev ordering!");
1904   }
1905
1906   Stream.ExitBlock();
1907 }
1908
1909 /// WriteModule - Emit the specified module to the bitstream.
1910 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1911   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1912
1913   SmallVector<unsigned, 1> Vals;
1914   unsigned CurVersion = 1;
1915   Vals.push_back(CurVersion);
1916   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1917
1918   // Analyze the module, enumerating globals, functions, etc.
1919   ValueEnumerator VE(*M);
1920
1921   // Emit blockinfo, which defines the standard abbreviations etc.
1922   WriteBlockInfo(VE, Stream);
1923
1924   // Emit information about attribute groups.
1925   WriteAttributeGroupTable(VE, Stream);
1926
1927   // Emit information about parameter attributes.
1928   WriteAttributeTable(VE, Stream);
1929
1930   // Emit information describing all of the types in the module.
1931   WriteTypeTable(VE, Stream);
1932
1933   writeComdats(VE, Stream);
1934
1935   // Emit top-level description of module, including target triple, inline asm,
1936   // descriptors for global variables, and function prototype info.
1937   WriteModuleInfo(M, VE, Stream);
1938
1939   // Emit constants.
1940   WriteModuleConstants(VE, Stream);
1941
1942   // Emit metadata.
1943   WriteModuleMetadata(M, VE, Stream);
1944
1945   // Emit metadata.
1946   WriteModuleMetadataStore(M, Stream);
1947
1948   // Emit names for globals/functions etc.
1949   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1950
1951   // Emit module-level use-lists.
1952   if (shouldPreserveBitcodeUseListOrder())
1953     WriteUseListBlock(nullptr, VE, Stream);
1954
1955   // Emit function bodies.
1956   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1957     if (!F->isDeclaration())
1958       WriteFunction(*F, VE, Stream);
1959
1960   Stream.ExitBlock();
1961 }
1962
1963 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1964 /// header and trailer to make it compatible with the system archiver.  To do
1965 /// this we emit the following header, and then emit a trailer that pads the
1966 /// file out to be a multiple of 16 bytes.
1967 ///
1968 /// struct bc_header {
1969 ///   uint32_t Magic;         // 0x0B17C0DE
1970 ///   uint32_t Version;       // Version, currently always 0.
1971 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1972 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1973 ///   uint32_t CPUType;       // CPU specifier.
1974 ///   ... potentially more later ...
1975 /// };
1976 enum {
1977   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1978   DarwinBCHeaderSize = 5*4
1979 };
1980
1981 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1982                                uint32_t &Position) {
1983   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1984   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1985   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1986   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1987   Position += 4;
1988 }
1989
1990 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1991                                          const Triple &TT) {
1992   unsigned CPUType = ~0U;
1993
1994   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1995   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1996   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1997   // specific constants here because they are implicitly part of the Darwin ABI.
1998   enum {
1999     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
2000     DARWIN_CPU_TYPE_X86        = 7,
2001     DARWIN_CPU_TYPE_ARM        = 12,
2002     DARWIN_CPU_TYPE_POWERPC    = 18
2003   };
2004
2005   Triple::ArchType Arch = TT.getArch();
2006   if (Arch == Triple::x86_64)
2007     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
2008   else if (Arch == Triple::x86)
2009     CPUType = DARWIN_CPU_TYPE_X86;
2010   else if (Arch == Triple::ppc)
2011     CPUType = DARWIN_CPU_TYPE_POWERPC;
2012   else if (Arch == Triple::ppc64)
2013     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
2014   else if (Arch == Triple::arm || Arch == Triple::thumb)
2015     CPUType = DARWIN_CPU_TYPE_ARM;
2016
2017   // Traditional Bitcode starts after header.
2018   assert(Buffer.size() >= DarwinBCHeaderSize &&
2019          "Expected header size to be reserved");
2020   unsigned BCOffset = DarwinBCHeaderSize;
2021   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
2022
2023   // Write the magic and version.
2024   unsigned Position = 0;
2025   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
2026   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
2027   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
2028   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2029   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2030
2031   // If the file is not a multiple of 16 bytes, insert dummy padding.
2032   while (Buffer.size() & 15)
2033     Buffer.push_back(0);
2034 }
2035
2036 /// WriteBitcodeToFile - Write the specified module to the specified output
2037 /// stream.
2038 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2039   SmallVector<char, 0> Buffer;
2040   Buffer.reserve(256*1024);
2041
2042   // If this is darwin or another generic macho target, reserve space for the
2043   // header.
2044   Triple TT(M->getTargetTriple());
2045   if (TT.isOSDarwin())
2046     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2047
2048   // Emit the module into the buffer.
2049   {
2050     BitstreamWriter Stream(Buffer);
2051
2052     // Emit the file header.
2053     Stream.Emit((unsigned)'B', 8);
2054     Stream.Emit((unsigned)'C', 8);
2055     Stream.Emit(0x0, 4);
2056     Stream.Emit(0xC, 4);
2057     Stream.Emit(0xE, 4);
2058     Stream.Emit(0xD, 4);
2059
2060     // Emit the module.
2061     WriteModule(M, Stream);
2062   }
2063
2064   if (TT.isOSDarwin())
2065     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2066
2067   // Write the generated bitstream to "Out".
2068   Out.write((char*)&Buffer.front(), Buffer.size());
2069 }