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 *, const ValueEnumerator &,
 830                               BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 831                               unsigned) {
 832   llvm_unreachable("write not implemented");
 833 }
 834 static void WriteMDBasicType(const MDBasicType *, const ValueEnumerator &,
 835                              BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 836                              unsigned) {
 837   llvm_unreachable("write not implemented");
 838 }
 839 static void WriteMDDerivedType(const MDDerivedType *, const ValueEnumerator &,
 840                                BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 841                                unsigned) {
 842   llvm_unreachable("write not implemented");
 843 }
 844 static void WriteMDCompositeType(const MDCompositeType *,
 845                                  const ValueEnumerator &, BitstreamWriter &,
 846                                  SmallVectorImpl<uint64_t> &, unsigned) {
 847   llvm_unreachable("write not implemented");
 848 }
 849 static void WriteMDSubroutineType(const MDSubroutineType *,
 850                                   const ValueEnumerator &, BitstreamWriter &,
 851                                   SmallVectorImpl<uint64_t> &, unsigned) {
 852   llvm_unreachable("write not implemented");
 853 }
 854 static void WriteMDFile(const MDFile *, const ValueEnumerator &,
 855                         BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 856                         unsigned) {
 857   llvm_unreachable("write not implemented");
 858 }
 859 static void WriteMDCompileUnit(const MDCompileUnit *, const ValueEnumerator &,
 860                                BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 861                                unsigned) {
 862   llvm_unreachable("write not implemented");
 863 }
 864 static void WriteMDSubprogram(const MDSubprogram *, const ValueEnumerator &,
 865                               BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 866                               unsigned) {
 867   llvm_unreachable("write not implemented");
 868 }
 869 static void WriteMDLexicalBlock(const MDLexicalBlock *, const ValueEnumerator &,
 870                                 BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 871                                 unsigned) {
 872   llvm_unreachable("write not implemented");
 873 }
 874 static void WriteMDLexicalBlockFile(const MDLexicalBlockFile *,
 875                                     const ValueEnumerator &, BitstreamWriter &,
 876                                     SmallVectorImpl<uint64_t> &, unsigned) {
 877   llvm_unreachable("write not implemented");
 878 }
 879 static void WriteMDNamespace(const MDNamespace *, const ValueEnumerator &,
 880                              BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 881                              unsigned) {
 882   llvm_unreachable("write not implemented");
 883 }
 884 static void WriteMDTemplateTypeParameter(const MDTemplateTypeParameter *,
 885                                          const ValueEnumerator &,
 886                                          BitstreamWriter &,
 887                                          SmallVectorImpl<uint64_t> &,
 888                                          unsigned) {
 889   llvm_unreachable("write not implemented");
 890 }
 891 static void WriteMDTemplateValueParameter(const MDTemplateValueParameter *,
 892                                           const ValueEnumerator &,
 893                                           BitstreamWriter &,
 894                                           SmallVectorImpl<uint64_t> &,
 895                                           unsigned) {
 896   llvm_unreachable("write not implemented");
 897 }
 898 static void WriteMDGlobalVariable(const MDGlobalVariable *,
 899                                   const ValueEnumerator &, BitstreamWriter &,
 900                                   SmallVectorImpl<uint64_t> &, unsigned) {
 901   llvm_unreachable("write not implemented");
 902 }
 903 static void WriteMDLocalVariable(const MDLocalVariable *,
 904                                  const ValueEnumerator &, BitstreamWriter &,
 905                                  SmallVectorImpl<uint64_t> &, unsigned) {
 906   llvm_unreachable("write not implemented");
 907 }
 908 static void WriteMDExpression(const MDExpression *, const ValueEnumerator &,
 909                               BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 910                               unsigned) {
 911   llvm_unreachable("write not implemented");
 912 }
 913 static void WriteMDObjCProperty(const MDObjCProperty *, const ValueEnumerator &,
 914                                 BitstreamWriter &, SmallVectorImpl<uint64_t> &,
 915                                 unsigned) {
 916   llvm_unreachable("write not implemented");
 917 }
 918 static void WriteMDImportedEntity(const MDImportedEntity *,
 919                                   const ValueEnumerator &, BitstreamWriter &,
 920                                   SmallVectorImpl<uint64_t> &, unsigned) {
 921   llvm_unreachable("write not implemented");
 922 }
 923
 924 static void WriteModuleMetadata(const Module *M,
 925                                 const ValueEnumerator &VE,
 926                                 BitstreamWriter &Stream) {
 927   const auto &MDs = VE.getMDs();
 928   if (MDs.empty() && M->named_metadata_empty())
 929     return;
 930
 931   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 932
 933   unsigned MDSAbbrev = 0;
 934   if (VE.hasMDString()) {
 935     // Abbrev for METADATA_STRING.
 936     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 937     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 938     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 939     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 940     MDSAbbrev = Stream.EmitAbbrev(Abbv);
 941   }
 942
 943   // Initialize MDNode abbreviations.
 944 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
 945 #include "llvm/IR/Metadata.def"
 946
 947   if (VE.hasMDLocation()) {
 948     // Abbrev for METADATA_LOCATION.
 949     //
 950     // Assume the column is usually under 128, and always output the inlined-at
 951     // location (it's never more expensive than building an array size 1).
 952     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 953     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
 954     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
 955     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 956     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 957     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 958     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 959     MDLocationAbbrev = Stream.EmitAbbrev(Abbv);
 960   }
 961
 962   if (VE.hasGenericDebugNode()) {
 963     // Abbrev for METADATA_GENERIC_DEBUG.
 964     //
 965     // Assume the column is usually under 128, and always output the inlined-at
 966     // location (it's never more expensive than building an array size 1).
 967     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 968     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
 969     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
 970     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 971     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
 972     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 973     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 974     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
 975     GenericDebugNodeAbbrev = Stream.EmitAbbrev(Abbv);
 976   }
 977
 978   unsigned NameAbbrev = 0;
 979   if (!M->named_metadata_empty()) {
 980     // Abbrev for METADATA_NAME.
 981     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 982     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
 983     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 984     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 985     NameAbbrev = Stream.EmitAbbrev(Abbv);
 986   }
 987
 988   SmallVector<uint64_t, 64> Record;
 989   for (const Metadata *MD : MDs) {
 990     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
 991       switch (N->getMetadataID()) {
 992       default:
 993         llvm_unreachable("Invalid MDNode subclass");
 994 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
 995   case Metadata::CLASS##Kind:                                                  \
 996     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
 997     continue;
 998 #include "llvm/IR/Metadata.def"
 999       }
1000     }
1001     if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MD)) {
1002       WriteValueAsMetadata(MDC, VE, Stream, Record);
1003       continue;
1004     }
1005     const MDString *MDS = cast<MDString>(MD);
1006     // Code: [strchar x N]
1007     Record.append(MDS->bytes_begin(), MDS->bytes_end());
1008
1009     // Emit the finished record.
1010     Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
1011     Record.clear();
1012   }
1013
1014   // Write named metadata.
1015   for (const NamedMDNode &NMD : M->named_metadata()) {
1016     // Write name.
1017     StringRef Str = NMD.getName();
1018     Record.append(Str.bytes_begin(), Str.bytes_end());
1019     Stream.EmitRecord(bitc::METADATA_NAME, Record, NameAbbrev);
1020     Record.clear();
1021
1022     // Write named metadata operands.
1023     for (const MDNode *N : NMD.operands())
1024       Record.push_back(VE.getMetadataID(N));
1025     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1026     Record.clear();
1027   }
1028
1029   Stream.ExitBlock();
1030 }
1031
1032 static void WriteFunctionLocalMetadata(const Function &F,
1033                                        const ValueEnumerator &VE,
1034                                        BitstreamWriter &Stream) {
1035   bool StartedMetadataBlock = false;
1036   SmallVector<uint64_t, 64> Record;
1037   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1038       VE.getFunctionLocalMDs();
1039   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1040     assert(MDs[i] && "Expected valid function-local metadata");
1041     if (!StartedMetadataBlock) {
1042       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1043       StartedMetadataBlock = true;
1044     }
1045     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1046   }
1047
1048   if (StartedMetadataBlock)
1049     Stream.ExitBlock();
1050 }
1051
1052 static void WriteMetadataAttachment(const Function &F,
1053                                     const ValueEnumerator &VE,
1054                                     BitstreamWriter &Stream) {
1055   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1056
1057   SmallVector<uint64_t, 64> Record;
1058
1059   // Write metadata attachments
1060   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1061   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1062
1063   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1064     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1065          I != E; ++I) {
1066       MDs.clear();
1067       I->getAllMetadataOtherThanDebugLoc(MDs);
1068
1069       // If no metadata, ignore instruction.
1070       if (MDs.empty()) continue;
1071
1072       Record.push_back(VE.getInstructionID(I));
1073
1074       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1075         Record.push_back(MDs[i].first);
1076         Record.push_back(VE.getMetadataID(MDs[i].second));
1077       }
1078       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1079       Record.clear();
1080     }
1081
1082   Stream.ExitBlock();
1083 }
1084
1085 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1086   SmallVector<uint64_t, 64> Record;
1087
1088   // Write metadata kinds
1089   // METADATA_KIND - [n x [id, name]]
1090   SmallVector<StringRef, 8> Names;
1091   M->getMDKindNames(Names);
1092
1093   if (Names.empty()) return;
1094
1095   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1096
1097   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1098     Record.push_back(MDKindID);
1099     StringRef KName = Names[MDKindID];
1100     Record.append(KName.begin(), KName.end());
1101
1102     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1103     Record.clear();
1104   }
1105
1106   Stream.ExitBlock();
1107 }
1108
1109 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1110   if ((int64_t)V >= 0)
1111     Vals.push_back(V << 1);
1112   else
1113     Vals.push_back((-V << 1) | 1);
1114 }
1115
1116 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1117                            const ValueEnumerator &VE,
1118                            BitstreamWriter &Stream, bool isGlobal) {
1119   if (FirstVal == LastVal) return;
1120
1121   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1122
1123   unsigned AggregateAbbrev = 0;
1124   unsigned String8Abbrev = 0;
1125   unsigned CString7Abbrev = 0;
1126   unsigned CString6Abbrev = 0;
1127   // If this is a constant pool for the module, emit module-specific abbrevs.
1128   if (isGlobal) {
1129     // Abbrev for CST_CODE_AGGREGATE.
1130     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1131     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1132     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1134     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1135
1136     // Abbrev for CST_CODE_STRING.
1137     Abbv = new BitCodeAbbrev();
1138     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1139     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1140     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1141     String8Abbrev = Stream.EmitAbbrev(Abbv);
1142     // Abbrev for CST_CODE_CSTRING.
1143     Abbv = new BitCodeAbbrev();
1144     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1146     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1147     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1148     // Abbrev for CST_CODE_CSTRING.
1149     Abbv = new BitCodeAbbrev();
1150     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1151     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1153     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1154   }
1155
1156   SmallVector<uint64_t, 64> Record;
1157
1158   const ValueEnumerator::ValueList &Vals = VE.getValues();
1159   Type *LastTy = nullptr;
1160   for (unsigned i = FirstVal; i != LastVal; ++i) {
1161     const Value *V = Vals[i].first;
1162     // If we need to switch types, do so now.
1163     if (V->getType() != LastTy) {
1164       LastTy = V->getType();
1165       Record.push_back(VE.getTypeID(LastTy));
1166       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1167                         CONSTANTS_SETTYPE_ABBREV);
1168       Record.clear();
1169     }
1170
1171     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1172       Record.push_back(unsigned(IA->hasSideEffects()) |
1173                        unsigned(IA->isAlignStack()) << 1 |
1174                        unsigned(IA->getDialect()&1) << 2);
1175
1176       // Add the asm string.
1177       const std::string &AsmStr = IA->getAsmString();
1178       Record.push_back(AsmStr.size());
1179       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
1180         Record.push_back(AsmStr[i]);
1181
1182       // Add the constraint string.
1183       const std::string &ConstraintStr = IA->getConstraintString();
1184       Record.push_back(ConstraintStr.size());
1185       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
1186         Record.push_back(ConstraintStr[i]);
1187       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1188       Record.clear();
1189       continue;
1190     }
1191     const Constant *C = cast<Constant>(V);
1192     unsigned Code = -1U;
1193     unsigned AbbrevToUse = 0;
1194     if (C->isNullValue()) {
1195       Code = bitc::CST_CODE_NULL;
1196     } else if (isa<UndefValue>(C)) {
1197       Code = bitc::CST_CODE_UNDEF;
1198     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1199       if (IV->getBitWidth() <= 64) {
1200         uint64_t V = IV->getSExtValue();
1201         emitSignedInt64(Record, V);
1202         Code = bitc::CST_CODE_INTEGER;
1203         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1204       } else {                             // Wide integers, > 64 bits in size.
1205         // We have an arbitrary precision integer value to write whose
1206         // bit width is > 64. However, in canonical unsigned integer
1207         // format it is likely that the high bits are going to be zero.
1208         // So, we only write the number of active words.
1209         unsigned NWords = IV->getValue().getActiveWords();
1210         const uint64_t *RawWords = IV->getValue().getRawData();
1211         for (unsigned i = 0; i != NWords; ++i) {
1212           emitSignedInt64(Record, RawWords[i]);
1213         }
1214         Code = bitc::CST_CODE_WIDE_INTEGER;
1215       }
1216     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1217       Code = bitc::CST_CODE_FLOAT;
1218       Type *Ty = CFP->getType();
1219       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1220         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1221       } else if (Ty->isX86_FP80Ty()) {
1222         // api needed to prevent premature destruction
1223         // bits are not in the same order as a normal i80 APInt, compensate.
1224         APInt api = CFP->getValueAPF().bitcastToAPInt();
1225         const uint64_t *p = api.getRawData();
1226         Record.push_back((p[1] << 48) | (p[0] >> 16));
1227         Record.push_back(p[0] & 0xffffLL);
1228       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1229         APInt api = CFP->getValueAPF().bitcastToAPInt();
1230         const uint64_t *p = api.getRawData();
1231         Record.push_back(p[0]);
1232         Record.push_back(p[1]);
1233       } else {
1234         assert (0 && "Unknown FP type!");
1235       }
1236     } else if (isa<ConstantDataSequential>(C) &&
1237                cast<ConstantDataSequential>(C)->isString()) {
1238       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1239       // Emit constant strings specially.
1240       unsigned NumElts = Str->getNumElements();
1241       // If this is a null-terminated string, use the denser CSTRING encoding.
1242       if (Str->isCString()) {
1243         Code = bitc::CST_CODE_CSTRING;
1244         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1245       } else {
1246         Code = bitc::CST_CODE_STRING;
1247         AbbrevToUse = String8Abbrev;
1248       }
1249       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1250       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1251       for (unsigned i = 0; i != NumElts; ++i) {
1252         unsigned char V = Str->getElementAsInteger(i);
1253         Record.push_back(V);
1254         isCStr7 &= (V & 128) == 0;
1255         if (isCStrChar6)
1256           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1257       }
1258
1259       if (isCStrChar6)
1260         AbbrevToUse = CString6Abbrev;
1261       else if (isCStr7)
1262         AbbrevToUse = CString7Abbrev;
1263     } else if (const ConstantDataSequential *CDS =
1264                   dyn_cast<ConstantDataSequential>(C)) {
1265       Code = bitc::CST_CODE_DATA;
1266       Type *EltTy = CDS->getType()->getElementType();
1267       if (isa<IntegerType>(EltTy)) {
1268         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1269           Record.push_back(CDS->getElementAsInteger(i));
1270       } else if (EltTy->isFloatTy()) {
1271         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1272           union { float F; uint32_t I; };
1273           F = CDS->getElementAsFloat(i);
1274           Record.push_back(I);
1275         }
1276       } else {
1277         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1278         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1279           union { double F; uint64_t I; };
1280           F = CDS->getElementAsDouble(i);
1281           Record.push_back(I);
1282         }
1283       }
1284     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1285                isa<ConstantVector>(C)) {
1286       Code = bitc::CST_CODE_AGGREGATE;
1287       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1288         Record.push_back(VE.getValueID(C->getOperand(i)));
1289       AbbrevToUse = AggregateAbbrev;
1290     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1291       switch (CE->getOpcode()) {
1292       default:
1293         if (Instruction::isCast(CE->getOpcode())) {
1294           Code = bitc::CST_CODE_CE_CAST;
1295           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1296           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1297           Record.push_back(VE.getValueID(C->getOperand(0)));
1298           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1299         } else {
1300           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1301           Code = bitc::CST_CODE_CE_BINOP;
1302           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1303           Record.push_back(VE.getValueID(C->getOperand(0)));
1304           Record.push_back(VE.getValueID(C->getOperand(1)));
1305           uint64_t Flags = GetOptimizationFlags(CE);
1306           if (Flags != 0)
1307             Record.push_back(Flags);
1308         }
1309         break;
1310       case Instruction::GetElementPtr:
1311         Code = bitc::CST_CODE_CE_GEP;
1312         if (cast<GEPOperator>(C)->isInBounds())
1313           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1314         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1315           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1316           Record.push_back(VE.getValueID(C->getOperand(i)));
1317         }
1318         break;
1319       case Instruction::Select:
1320         Code = bitc::CST_CODE_CE_SELECT;
1321         Record.push_back(VE.getValueID(C->getOperand(0)));
1322         Record.push_back(VE.getValueID(C->getOperand(1)));
1323         Record.push_back(VE.getValueID(C->getOperand(2)));
1324         break;
1325       case Instruction::ExtractElement:
1326         Code = bitc::CST_CODE_CE_EXTRACTELT;
1327         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1328         Record.push_back(VE.getValueID(C->getOperand(0)));
1329         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1330         Record.push_back(VE.getValueID(C->getOperand(1)));
1331         break;
1332       case Instruction::InsertElement:
1333         Code = bitc::CST_CODE_CE_INSERTELT;
1334         Record.push_back(VE.getValueID(C->getOperand(0)));
1335         Record.push_back(VE.getValueID(C->getOperand(1)));
1336         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1337         Record.push_back(VE.getValueID(C->getOperand(2)));
1338         break;
1339       case Instruction::ShuffleVector:
1340         // If the return type and argument types are the same, this is a
1341         // standard shufflevector instruction.  If the types are different,
1342         // then the shuffle is widening or truncating the input vectors, and
1343         // the argument type must also be encoded.
1344         if (C->getType() == C->getOperand(0)->getType()) {
1345           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1346         } else {
1347           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1348           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1349         }
1350         Record.push_back(VE.getValueID(C->getOperand(0)));
1351         Record.push_back(VE.getValueID(C->getOperand(1)));
1352         Record.push_back(VE.getValueID(C->getOperand(2)));
1353         break;
1354       case Instruction::ICmp:
1355       case Instruction::FCmp:
1356         Code = bitc::CST_CODE_CE_CMP;
1357         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1358         Record.push_back(VE.getValueID(C->getOperand(0)));
1359         Record.push_back(VE.getValueID(C->getOperand(1)));
1360         Record.push_back(CE->getPredicate());
1361         break;
1362       }
1363     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1364       Code = bitc::CST_CODE_BLOCKADDRESS;
1365       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1366       Record.push_back(VE.getValueID(BA->getFunction()));
1367       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1368     } else {
1369 #ifndef NDEBUG
1370       C->dump();
1371 #endif
1372       llvm_unreachable("Unknown constant!");
1373     }
1374     Stream.EmitRecord(Code, Record, AbbrevToUse);
1375     Record.clear();
1376   }
1377
1378   Stream.ExitBlock();
1379 }
1380
1381 static void WriteModuleConstants(const ValueEnumerator &VE,
1382                                  BitstreamWriter &Stream) {
1383   const ValueEnumerator::ValueList &Vals = VE.getValues();
1384
1385   // Find the first constant to emit, which is the first non-globalvalue value.
1386   // We know globalvalues have been emitted by WriteModuleInfo.
1387   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1388     if (!isa<GlobalValue>(Vals[i].first)) {
1389       WriteConstants(i, Vals.size(), VE, Stream, true);
1390       return;
1391     }
1392   }
1393 }
1394
1395 /// PushValueAndType - The file has to encode both the value and type id for
1396 /// many values, because we need to know what type to create for forward
1397 /// references.  However, most operands are not forward references, so this type
1398 /// field is not needed.
1399 ///
1400 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1401 /// instruction ID, then it is a forward reference, and it also includes the
1402 /// type ID.  The value ID that is written is encoded relative to the InstID.
1403 static bool PushValueAndType(const Value *V, unsigned InstID,
1404                              SmallVectorImpl<unsigned> &Vals,
1405                              ValueEnumerator &VE) {
1406   unsigned ValID = VE.getValueID(V);
1407   // Make encoding relative to the InstID.
1408   Vals.push_back(InstID - ValID);
1409   if (ValID >= InstID) {
1410     Vals.push_back(VE.getTypeID(V->getType()));
1411     return true;
1412   }
1413   return false;
1414 }
1415
1416 /// pushValue - Like PushValueAndType, but where the type of the value is
1417 /// omitted (perhaps it was already encoded in an earlier operand).
1418 static void pushValue(const Value *V, unsigned InstID,
1419                       SmallVectorImpl<unsigned> &Vals,
1420                       ValueEnumerator &VE) {
1421   unsigned ValID = VE.getValueID(V);
1422   Vals.push_back(InstID - ValID);
1423 }
1424
1425 static void pushValueSigned(const Value *V, unsigned InstID,
1426                             SmallVectorImpl<uint64_t> &Vals,
1427                             ValueEnumerator &VE) {
1428   unsigned ValID = VE.getValueID(V);
1429   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1430   emitSignedInt64(Vals, diff);
1431 }
1432
1433 /// WriteInstruction - Emit an instruction to the specified stream.
1434 static void WriteInstruction(const Instruction &I, unsigned InstID,
1435                              ValueEnumerator &VE, BitstreamWriter &Stream,
1436                              SmallVectorImpl<unsigned> &Vals) {
1437   unsigned Code = 0;
1438   unsigned AbbrevToUse = 0;
1439   VE.setInstructionID(&I);
1440   switch (I.getOpcode()) {
1441   default:
1442     if (Instruction::isCast(I.getOpcode())) {
1443       Code = bitc::FUNC_CODE_INST_CAST;
1444       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1445         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1446       Vals.push_back(VE.getTypeID(I.getType()));
1447       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1448     } else {
1449       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1450       Code = bitc::FUNC_CODE_INST_BINOP;
1451       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1452         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1453       pushValue(I.getOperand(1), InstID, Vals, VE);
1454       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1455       uint64_t Flags = GetOptimizationFlags(&I);
1456       if (Flags != 0) {
1457         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1458           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1459         Vals.push_back(Flags);
1460       }
1461     }
1462     break;
1463
1464   case Instruction::GetElementPtr:
1465     Code = bitc::FUNC_CODE_INST_GEP;
1466     if (cast<GEPOperator>(&I)->isInBounds())
1467       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1468     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1469       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1470     break;
1471   case Instruction::ExtractValue: {
1472     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1473     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1474     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1475     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1476       Vals.push_back(*i);
1477     break;
1478   }
1479   case Instruction::InsertValue: {
1480     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1481     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1482     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1483     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1484     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1485       Vals.push_back(*i);
1486     break;
1487   }
1488   case Instruction::Select:
1489     Code = bitc::FUNC_CODE_INST_VSELECT;
1490     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1491     pushValue(I.getOperand(2), InstID, Vals, VE);
1492     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1493     break;
1494   case Instruction::ExtractElement:
1495     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1496     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1497     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1498     break;
1499   case Instruction::InsertElement:
1500     Code = bitc::FUNC_CODE_INST_INSERTELT;
1501     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1502     pushValue(I.getOperand(1), InstID, Vals, VE);
1503     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1504     break;
1505   case Instruction::ShuffleVector:
1506     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1507     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1508     pushValue(I.getOperand(1), InstID, Vals, VE);
1509     pushValue(I.getOperand(2), InstID, Vals, VE);
1510     break;
1511   case Instruction::ICmp:
1512   case Instruction::FCmp:
1513     // compare returning Int1Ty or vector of Int1Ty
1514     Code = bitc::FUNC_CODE_INST_CMP2;
1515     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1516     pushValue(I.getOperand(1), InstID, Vals, VE);
1517     Vals.push_back(cast<CmpInst>(I).getPredicate());
1518     break;
1519
1520   case Instruction::Ret:
1521     {
1522       Code = bitc::FUNC_CODE_INST_RET;
1523       unsigned NumOperands = I.getNumOperands();
1524       if (NumOperands == 0)
1525         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1526       else if (NumOperands == 1) {
1527         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1528           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1529       } else {
1530         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1531           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1532       }
1533     }
1534     break;
1535   case Instruction::Br:
1536     {
1537       Code = bitc::FUNC_CODE_INST_BR;
1538       const BranchInst &II = cast<BranchInst>(I);
1539       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1540       if (II.isConditional()) {
1541         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1542         pushValue(II.getCondition(), InstID, Vals, VE);
1543       }
1544     }
1545     break;
1546   case Instruction::Switch:
1547     {
1548       Code = bitc::FUNC_CODE_INST_SWITCH;
1549       const SwitchInst &SI = cast<SwitchInst>(I);
1550       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1551       pushValue(SI.getCondition(), InstID, Vals, VE);
1552       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1553       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1554            i != e; ++i) {
1555         Vals.push_back(VE.getValueID(i.getCaseValue()));
1556         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1557       }
1558     }
1559     break;
1560   case Instruction::IndirectBr:
1561     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1562     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1563     // Encode the address operand as relative, but not the basic blocks.
1564     pushValue(I.getOperand(0), InstID, Vals, VE);
1565     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1566       Vals.push_back(VE.getValueID(I.getOperand(i)));
1567     break;
1568
1569   case Instruction::Invoke: {
1570     const InvokeInst *II = cast<InvokeInst>(&I);
1571     const Value *Callee(II->getCalledValue());
1572     PointerType *PTy = cast<PointerType>(Callee->getType());
1573     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1574     Code = bitc::FUNC_CODE_INST_INVOKE;
1575
1576     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1577     Vals.push_back(II->getCallingConv());
1578     Vals.push_back(VE.getValueID(II->getNormalDest()));
1579     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1580     PushValueAndType(Callee, InstID, Vals, VE);
1581
1582     // Emit value #'s for the fixed parameters.
1583     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1584       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1585
1586     // Emit type/value pairs for varargs params.
1587     if (FTy->isVarArg()) {
1588       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1589            i != e; ++i)
1590         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1591     }
1592     break;
1593   }
1594   case Instruction::Resume:
1595     Code = bitc::FUNC_CODE_INST_RESUME;
1596     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1597     break;
1598   case Instruction::Unreachable:
1599     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1600     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1601     break;
1602
1603   case Instruction::PHI: {
1604     const PHINode &PN = cast<PHINode>(I);
1605     Code = bitc::FUNC_CODE_INST_PHI;
1606     // With the newer instruction encoding, forward references could give
1607     // negative valued IDs.  This is most common for PHIs, so we use
1608     // signed VBRs.
1609     SmallVector<uint64_t, 128> Vals64;
1610     Vals64.push_back(VE.getTypeID(PN.getType()));
1611     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1612       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1613       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1614     }
1615     // Emit a Vals64 vector and exit.
1616     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1617     Vals64.clear();
1618     return;
1619   }
1620
1621   case Instruction::LandingPad: {
1622     const LandingPadInst &LP = cast<LandingPadInst>(I);
1623     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1624     Vals.push_back(VE.getTypeID(LP.getType()));
1625     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1626     Vals.push_back(LP.isCleanup());
1627     Vals.push_back(LP.getNumClauses());
1628     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1629       if (LP.isCatch(I))
1630         Vals.push_back(LandingPadInst::Catch);
1631       else
1632         Vals.push_back(LandingPadInst::Filter);
1633       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1634     }
1635     break;
1636   }
1637
1638   case Instruction::Alloca: {
1639     Code = bitc::FUNC_CODE_INST_ALLOCA;
1640     Vals.push_back(VE.getTypeID(I.getType()));
1641     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1642     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1643     const AllocaInst &AI = cast<AllocaInst>(I);
1644     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
1645     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
1646            "not enough bits for maximum alignment");
1647     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
1648     AlignRecord |= AI.isUsedWithInAlloca() << 5;
1649     Vals.push_back(AlignRecord);
1650     break;
1651   }
1652
1653   case Instruction::Load:
1654     if (cast<LoadInst>(I).isAtomic()) {
1655       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1656       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1657     } else {
1658       Code = bitc::FUNC_CODE_INST_LOAD;
1659       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1660         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1661     }
1662     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1663     Vals.push_back(cast<LoadInst>(I).isVolatile());
1664     if (cast<LoadInst>(I).isAtomic()) {
1665       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1666       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1667     }
1668     break;
1669   case Instruction::Store:
1670     if (cast<StoreInst>(I).isAtomic())
1671       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1672     else
1673       Code = bitc::FUNC_CODE_INST_STORE;
1674     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1675     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1676     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1677     Vals.push_back(cast<StoreInst>(I).isVolatile());
1678     if (cast<StoreInst>(I).isAtomic()) {
1679       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1680       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1681     }
1682     break;
1683   case Instruction::AtomicCmpXchg:
1684     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1685     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1686     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1687     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1688     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1689     Vals.push_back(GetEncodedOrdering(
1690                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
1691     Vals.push_back(GetEncodedSynchScope(
1692                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1693     Vals.push_back(GetEncodedOrdering(
1694                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
1695     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
1696     break;
1697   case Instruction::AtomicRMW:
1698     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1699     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1700     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1701     Vals.push_back(GetEncodedRMWOperation(
1702                      cast<AtomicRMWInst>(I).getOperation()));
1703     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1704     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1705     Vals.push_back(GetEncodedSynchScope(
1706                      cast<AtomicRMWInst>(I).getSynchScope()));
1707     break;
1708   case Instruction::Fence:
1709     Code = bitc::FUNC_CODE_INST_FENCE;
1710     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1711     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1712     break;
1713   case Instruction::Call: {
1714     const CallInst &CI = cast<CallInst>(I);
1715     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1716     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1717
1718     Code = bitc::FUNC_CODE_INST_CALL;
1719
1720     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1721     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()) |
1722                    unsigned(CI.isMustTailCall()) << 14);
1723     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1724
1725     // Emit value #'s for the fixed parameters.
1726     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1727       // Check for labels (can happen with asm labels).
1728       if (FTy->getParamType(i)->isLabelTy())
1729         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1730       else
1731         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1732     }
1733
1734     // Emit type/value pairs for varargs params.
1735     if (FTy->isVarArg()) {
1736       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1737            i != e; ++i)
1738         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1739     }
1740     break;
1741   }
1742   case Instruction::VAArg:
1743     Code = bitc::FUNC_CODE_INST_VAARG;
1744     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1745     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1746     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1747     break;
1748   }
1749
1750   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1751   Vals.clear();
1752 }
1753
1754 // Emit names for globals/functions etc.
1755 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1756                                   const ValueEnumerator &VE,
1757                                   BitstreamWriter &Stream) {
1758   if (VST.empty()) return;
1759   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1760
1761   // FIXME: Set up the abbrev, we know how many values there are!
1762   // FIXME: We know if the type names can use 7-bit ascii.
1763   SmallVector<unsigned, 64> NameVals;
1764
1765   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1766        SI != SE; ++SI) {
1767
1768     const ValueName &Name = *SI;
1769
1770     // Figure out the encoding to use for the name.
1771     bool is7Bit = true;
1772     bool isChar6 = true;
1773     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1774          C != E; ++C) {
1775       if (isChar6)
1776         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1777       if ((unsigned char)*C & 128) {
1778         is7Bit = false;
1779         break;  // don't bother scanning the rest.
1780       }
1781     }
1782
1783     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1784
1785     // VST_ENTRY:   [valueid, namechar x N]
1786     // VST_BBENTRY: [bbid, namechar x N]
1787     unsigned Code;
1788     if (isa<BasicBlock>(SI->getValue())) {
1789       Code = bitc::VST_CODE_BBENTRY;
1790       if (isChar6)
1791         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1792     } else {
1793       Code = bitc::VST_CODE_ENTRY;
1794       if (isChar6)
1795         AbbrevToUse = VST_ENTRY_6_ABBREV;
1796       else if (is7Bit)
1797         AbbrevToUse = VST_ENTRY_7_ABBREV;
1798     }
1799
1800     NameVals.push_back(VE.getValueID(SI->getValue()));
1801     for (const char *P = Name.getKeyData(),
1802          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1803       NameVals.push_back((unsigned char)*P);
1804
1805     // Emit the finished record.
1806     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1807     NameVals.clear();
1808   }
1809   Stream.ExitBlock();
1810 }
1811
1812 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
1813                          BitstreamWriter &Stream) {
1814   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
1815   unsigned Code;
1816   if (isa<BasicBlock>(Order.V))
1817     Code = bitc::USELIST_CODE_BB;
1818   else
1819     Code = bitc::USELIST_CODE_DEFAULT;
1820
1821   SmallVector<uint64_t, 64> Record;
1822   for (unsigned I : Order.Shuffle)
1823     Record.push_back(I);
1824   Record.push_back(VE.getValueID(Order.V));
1825   Stream.EmitRecord(Code, Record);
1826 }
1827
1828 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
1829                               BitstreamWriter &Stream) {
1830   auto hasMore = [&]() {
1831     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
1832   };
1833   if (!hasMore())
1834     // Nothing to do.
1835     return;
1836
1837   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1838   while (hasMore()) {
1839     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
1840     VE.UseListOrders.pop_back();
1841   }
1842   Stream.ExitBlock();
1843 }
1844
1845 /// WriteFunction - Emit a function body to the module stream.
1846 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1847                           BitstreamWriter &Stream) {
1848   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1849   VE.incorporateFunction(F);
1850
1851   SmallVector<unsigned, 64> Vals;
1852
1853   // Emit the number of basic blocks, so the reader can create them ahead of
1854   // time.
1855   Vals.push_back(VE.getBasicBlocks().size());
1856   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1857   Vals.clear();
1858
1859   // If there are function-local constants, emit them now.
1860   unsigned CstStart, CstEnd;
1861   VE.getFunctionConstantRange(CstStart, CstEnd);
1862   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1863
1864   // If there is function-local metadata, emit it now.
1865   WriteFunctionLocalMetadata(F, VE, Stream);
1866
1867   // Keep a running idea of what the instruction ID is.
1868   unsigned InstID = CstEnd;
1869
1870   bool NeedsMetadataAttachment = false;
1871
1872   DebugLoc LastDL;
1873
1874   // Finally, emit all the instructions, in order.
1875   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1876     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1877          I != E; ++I) {
1878       WriteInstruction(*I, InstID, VE, Stream, Vals);
1879
1880       if (!I->getType()->isVoidTy())
1881         ++InstID;
1882
1883       // If the instruction has metadata, write a metadata attachment later.
1884       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1885
1886       // If the instruction has a debug location, emit it.
1887       DebugLoc DL = I->getDebugLoc();
1888       if (DL.isUnknown()) {
1889         // nothing todo.
1890       } else if (DL == LastDL) {
1891         // Just repeat the same debug loc as last time.
1892         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1893       } else {
1894         MDNode *Scope, *IA;
1895         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1896         assert(Scope && "Expected valid scope");
1897
1898         Vals.push_back(DL.getLine());
1899         Vals.push_back(DL.getCol());
1900         Vals.push_back(VE.getMetadataOrNullID(Scope));
1901         Vals.push_back(VE.getMetadataOrNullID(IA));
1902         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1903         Vals.clear();
1904
1905         LastDL = DL;
1906       }
1907     }
1908
1909   // Emit names for all the instructions etc.
1910   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1911
1912   if (NeedsMetadataAttachment)
1913     WriteMetadataAttachment(F, VE, Stream);
1914   if (shouldPreserveBitcodeUseListOrder())
1915     WriteUseListBlock(&F, VE, Stream);
1916   VE.purgeFunction();
1917   Stream.ExitBlock();
1918 }
1919
1920 // Emit blockinfo, which defines the standard abbreviations etc.
1921 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1922   // We only want to emit block info records for blocks that have multiple
1923   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1924   // Other blocks can define their abbrevs inline.
1925   Stream.EnterBlockInfoBlock(2);
1926
1927   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1928     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1929     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1930     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1931     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1932     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1933     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1934                                    Abbv) != VST_ENTRY_8_ABBREV)
1935       llvm_unreachable("Unexpected abbrev ordering!");
1936   }
1937
1938   { // 7-bit fixed width VST_ENTRY strings.
1939     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1940     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1941     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1942     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1943     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1944     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1945                                    Abbv) != VST_ENTRY_7_ABBREV)
1946       llvm_unreachable("Unexpected abbrev ordering!");
1947   }
1948   { // 6-bit char6 VST_ENTRY strings.
1949     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1950     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1951     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1952     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1953     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1954     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1955                                    Abbv) != VST_ENTRY_6_ABBREV)
1956       llvm_unreachable("Unexpected abbrev ordering!");
1957   }
1958   { // 6-bit char6 VST_BBENTRY strings.
1959     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1960     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1961     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1962     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1963     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1964     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1965                                    Abbv) != VST_BBENTRY_6_ABBREV)
1966       llvm_unreachable("Unexpected abbrev ordering!");
1967   }
1968
1969
1970
1971   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1972     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1973     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1974     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1975                               Log2_32_Ceil(VE.getTypes().size()+1)));
1976     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1977                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1978       llvm_unreachable("Unexpected abbrev ordering!");
1979   }
1980
1981   { // INTEGER abbrev for CONSTANTS_BLOCK.
1982     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1983     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1984     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1985     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1986                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1987       llvm_unreachable("Unexpected abbrev ordering!");
1988   }
1989
1990   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1991     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1992     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1993     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1994     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1995                               Log2_32_Ceil(VE.getTypes().size()+1)));
1996     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1997
1998     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1999                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2000       llvm_unreachable("Unexpected abbrev ordering!");
2001   }
2002   { // NULL abbrev for CONSTANTS_BLOCK.
2003     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2004     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2005     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2006                                    Abbv) != CONSTANTS_NULL_Abbrev)
2007       llvm_unreachable("Unexpected abbrev ordering!");
2008   }
2009
2010   // FIXME: This should only use space for first class types!
2011
2012   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2013     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2014     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2015     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2016     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2017     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2018     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2019                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2020       llvm_unreachable("Unexpected abbrev ordering!");
2021   }
2022   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2023     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2024     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2025     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2026     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2027     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2028     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2029                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2030       llvm_unreachable("Unexpected abbrev ordering!");
2031   }
2032   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2033     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2034     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2035     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2036     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2037     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2038     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2039     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2040                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2041       llvm_unreachable("Unexpected abbrev ordering!");
2042   }
2043   { // INST_CAST abbrev for FUNCTION_BLOCK.
2044     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2045     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2046     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2047     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2048                               Log2_32_Ceil(VE.getTypes().size()+1)));
2049     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2050     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2051                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2052       llvm_unreachable("Unexpected abbrev ordering!");
2053   }
2054
2055   { // INST_RET abbrev for FUNCTION_BLOCK.
2056     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2057     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2058     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2059                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2060       llvm_unreachable("Unexpected abbrev ordering!");
2061   }
2062   { // INST_RET abbrev for FUNCTION_BLOCK.
2063     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2064     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2065     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2066     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2067                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2068       llvm_unreachable("Unexpected abbrev ordering!");
2069   }
2070   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2071     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2072     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2073     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2074                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2075       llvm_unreachable("Unexpected abbrev ordering!");
2076   }
2077
2078   Stream.ExitBlock();
2079 }
2080
2081 /// WriteModule - Emit the specified module to the bitstream.
2082 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
2083   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
2084
2085   SmallVector<unsigned, 1> Vals;
2086   unsigned CurVersion = 1;
2087   Vals.push_back(CurVersion);
2088   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
2089
2090   // Analyze the module, enumerating globals, functions, etc.
2091   ValueEnumerator VE(*M);
2092
2093   // Emit blockinfo, which defines the standard abbreviations etc.
2094   WriteBlockInfo(VE, Stream);
2095
2096   // Emit information about attribute groups.
2097   WriteAttributeGroupTable(VE, Stream);
2098
2099   // Emit information about parameter attributes.
2100   WriteAttributeTable(VE, Stream);
2101
2102   // Emit information describing all of the types in the module.
2103   WriteTypeTable(VE, Stream);
2104
2105   writeComdats(VE, Stream);
2106
2107   // Emit top-level description of module, including target triple, inline asm,
2108   // descriptors for global variables, and function prototype info.
2109   WriteModuleInfo(M, VE, Stream);
2110
2111   // Emit constants.
2112   WriteModuleConstants(VE, Stream);
2113
2114   // Emit metadata.
2115   WriteModuleMetadata(M, VE, Stream);
2116
2117   // Emit metadata.
2118   WriteModuleMetadataStore(M, Stream);
2119
2120   // Emit names for globals/functions etc.
2121   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
2122
2123   // Emit module-level use-lists.
2124   if (shouldPreserveBitcodeUseListOrder())
2125     WriteUseListBlock(nullptr, VE, Stream);
2126
2127   // Emit function bodies.
2128   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
2129     if (!F->isDeclaration())
2130       WriteFunction(*F, VE, Stream);
2131
2132   Stream.ExitBlock();
2133 }
2134
2135 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
2136 /// header and trailer to make it compatible with the system archiver.  To do
2137 /// this we emit the following header, and then emit a trailer that pads the
2138 /// file out to be a multiple of 16 bytes.
2139 ///
2140 /// struct bc_header {
2141 ///   uint32_t Magic;         // 0x0B17C0DE
2142 ///   uint32_t Version;       // Version, currently always 0.
2143 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
2144 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
2145 ///   uint32_t CPUType;       // CPU specifier.
2146 ///   ... potentially more later ...
2147 /// };
2148 enum {
2149   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
2150   DarwinBCHeaderSize = 5*4
2151 };
2152
2153 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
2154                                uint32_t &Position) {
2155   Buffer[Position + 0] = (unsigned char) (Value >>  0);
2156   Buffer[Position + 1] = (unsigned char) (Value >>  8);
2157   Buffer[Position + 2] = (unsigned char) (Value >> 16);
2158   Buffer[Position + 3] = (unsigned char) (Value >> 24);
2159   Position += 4;
2160 }
2161
2162 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
2163                                          const Triple &TT) {
2164   unsigned CPUType = ~0U;
2165
2166   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
2167   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
2168   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
2169   // specific constants here because they are implicitly part of the Darwin ABI.
2170   enum {
2171     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
2172     DARWIN_CPU_TYPE_X86        = 7,
2173     DARWIN_CPU_TYPE_ARM        = 12,
2174     DARWIN_CPU_TYPE_POWERPC    = 18
2175   };
2176
2177   Triple::ArchType Arch = TT.getArch();
2178   if (Arch == Triple::x86_64)
2179     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
2180   else if (Arch == Triple::x86)
2181     CPUType = DARWIN_CPU_TYPE_X86;
2182   else if (Arch == Triple::ppc)
2183     CPUType = DARWIN_CPU_TYPE_POWERPC;
2184   else if (Arch == Triple::ppc64)
2185     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
2186   else if (Arch == Triple::arm || Arch == Triple::thumb)
2187     CPUType = DARWIN_CPU_TYPE_ARM;
2188
2189   // Traditional Bitcode starts after header.
2190   assert(Buffer.size() >= DarwinBCHeaderSize &&
2191          "Expected header size to be reserved");
2192   unsigned BCOffset = DarwinBCHeaderSize;
2193   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
2194
2195   // Write the magic and version.
2196   unsigned Position = 0;
2197   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
2198   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
2199   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
2200   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2201   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2202
2203   // If the file is not a multiple of 16 bytes, insert dummy padding.
2204   while (Buffer.size() & 15)
2205     Buffer.push_back(0);
2206 }
2207
2208 /// WriteBitcodeToFile - Write the specified module to the specified output
2209 /// stream.
2210 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2211   SmallVector<char, 0> Buffer;
2212   Buffer.reserve(256*1024);
2213
2214   // If this is darwin or another generic macho target, reserve space for the
2215   // header.
2216   Triple TT(M->getTargetTriple());
2217   if (TT.isOSDarwin())
2218     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2219
2220   // Emit the module into the buffer.
2221   {
2222     BitstreamWriter Stream(Buffer);
2223
2224     // Emit the file header.
2225     Stream.Emit((unsigned)'B', 8);
2226     Stream.Emit((unsigned)'C', 8);
2227     Stream.Emit(0x0, 4);
2228     Stream.Emit(0xC, 4);
2229     Stream.Emit(0xE, 4);
2230     Stream.Emit(0xD, 4);
2231
2232     // Emit the module.
2233     WriteModule(M, Stream);
2234   }
2235
2236   if (TT.isOSDarwin())
2237     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2238
2239   // Write the generated bitstream to "Out".
2240   Out.write((char*)&Buffer.front(), Buffer.size());
2241 }