lib/Bitcode/Writer/BitcodeWriter.cpp

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