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