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]
 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       Vals.push_back(getEncodedVisibility(GV));
 621       Vals.push_back(getEncodedThreadLocalMode(GV));
 622       Vals.push_back(GV->hasUnnamedAddr());
 623       Vals.push_back(GV->isExternallyInitialized());
 624     } else {
 625       AbbrevToUse = SimpleGVarAbbrev;
 626     }
 627
 628     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 629     Vals.clear();
 630   }
 631
 632   // Emit the function proto information.
 633   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 634     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 635     //             section, visibility, gc, unnamed_addr, prefix]
 636     Vals.push_back(VE.getTypeID(F->getType()));
 637     Vals.push_back(F->getCallingConv());
 638     Vals.push_back(F->isDeclaration());
 639     Vals.push_back(getEncodedLinkage(F));
 640     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 641     Vals.push_back(Log2_32(F->getAlignment())+1);
 642     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 643     Vals.push_back(getEncodedVisibility(F));
 644     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 645     Vals.push_back(F->hasUnnamedAddr());
 646     Vals.push_back(F->hasPrefixData() ? (VE.getValueID(F->getPrefixData()) + 1)
 647                                       : 0);
 648
 649     unsigned AbbrevToUse = 0;
 650     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 651     Vals.clear();
 652   }
 653
 654   // Emit the alias information.
 655   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 656        AI != E; ++AI) {
 657     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 658     Vals.push_back(VE.getTypeID(AI->getType()));
 659     Vals.push_back(VE.getValueID(AI->getAliasee()));
 660     Vals.push_back(getEncodedLinkage(AI));
 661     Vals.push_back(getEncodedVisibility(AI));
 662     unsigned AbbrevToUse = 0;
 663     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 664     Vals.clear();
 665   }
 666 }
 667
 668 static uint64_t GetOptimizationFlags(const Value *V) {
 669   uint64_t Flags = 0;
 670
 671   if (const OverflowingBinaryOperator *OBO =
 672         dyn_cast<OverflowingBinaryOperator>(V)) {
 673     if (OBO->hasNoSignedWrap())
 674       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 675     if (OBO->hasNoUnsignedWrap())
 676       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 677   } else if (const PossiblyExactOperator *PEO =
 678                dyn_cast<PossiblyExactOperator>(V)) {
 679     if (PEO->isExact())
 680       Flags |= 1 << bitc::PEO_EXACT;
 681   } else if (const FPMathOperator *FPMO =
 682              dyn_cast<const FPMathOperator>(V)) {
 683     if (FPMO->hasUnsafeAlgebra())
 684       Flags |= FastMathFlags::UnsafeAlgebra;
 685     if (FPMO->hasNoNaNs())
 686       Flags |= FastMathFlags::NoNaNs;
 687     if (FPMO->hasNoInfs())
 688       Flags |= FastMathFlags::NoInfs;
 689     if (FPMO->hasNoSignedZeros())
 690       Flags |= FastMathFlags::NoSignedZeros;
 691     if (FPMO->hasAllowReciprocal())
 692       Flags |= FastMathFlags::AllowReciprocal;
 693   }
 694
 695   return Flags;
 696 }
 697
 698 static void WriteMDNode(const MDNode *N,
 699                         const ValueEnumerator &VE,
 700                         BitstreamWriter &Stream,
 701                         SmallVectorImpl<uint64_t> &Record) {
 702   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 703     if (N->getOperand(i)) {
 704       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 705       Record.push_back(VE.getValueID(N->getOperand(i)));
 706     } else {
 707       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 708       Record.push_back(0);
 709     }
 710   }
 711   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 712                                            bitc::METADATA_NODE;
 713   Stream.EmitRecord(MDCode, Record, 0);
 714   Record.clear();
 715 }
 716
 717 static void WriteModuleMetadata(const Module *M,
 718                                 const ValueEnumerator &VE,
 719                                 BitstreamWriter &Stream) {
 720   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 721   bool StartedMetadataBlock = false;
 722   unsigned MDSAbbrev = 0;
 723   SmallVector<uint64_t, 64> Record;
 724   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 725
 726     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 727       if (!N->isFunctionLocal() || !N->getFunction()) {
 728         if (!StartedMetadataBlock) {
 729           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 730           StartedMetadataBlock = true;
 731         }
 732         WriteMDNode(N, VE, Stream, Record);
 733       }
 734     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 735       if (!StartedMetadataBlock)  {
 736         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 737
 738         // Abbrev for METADATA_STRING.
 739         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 740         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 741         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 742         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 743         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 744         StartedMetadataBlock = true;
 745       }
 746
 747       // Code: [strchar x N]
 748       Record.append(MDS->begin(), MDS->end());
 749
 750       // Emit the finished record.
 751       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 752       Record.clear();
 753     }
 754   }
 755
 756   // Write named metadata.
 757   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 758        E = M->named_metadata_end(); I != E; ++I) {
 759     const NamedMDNode *NMD = I;
 760     if (!StartedMetadataBlock)  {
 761       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 762       StartedMetadataBlock = true;
 763     }
 764
 765     // Write name.
 766     StringRef Str = NMD->getName();
 767     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 768       Record.push_back(Str[i]);
 769     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 770     Record.clear();
 771
 772     // Write named metadata operands.
 773     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 774       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 775     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 776     Record.clear();
 777   }
 778
 779   if (StartedMetadataBlock)
 780     Stream.ExitBlock();
 781 }
 782
 783 static void WriteFunctionLocalMetadata(const Function &F,
 784                                        const ValueEnumerator &VE,
 785                                        BitstreamWriter &Stream) {
 786   bool StartedMetadataBlock = false;
 787   SmallVector<uint64_t, 64> Record;
 788   const SmallVectorImpl<const MDNode *> &Vals = VE.getFunctionLocalMDValues();
 789   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 790     if (const MDNode *N = Vals[i])
 791       if (N->isFunctionLocal() && N->getFunction() == &F) {
 792         if (!StartedMetadataBlock) {
 793           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 794           StartedMetadataBlock = true;
 795         }
 796         WriteMDNode(N, VE, Stream, Record);
 797       }
 798
 799   if (StartedMetadataBlock)
 800     Stream.ExitBlock();
 801 }
 802
 803 static void WriteMetadataAttachment(const Function &F,
 804                                     const ValueEnumerator &VE,
 805                                     BitstreamWriter &Stream) {
 806   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 807
 808   SmallVector<uint64_t, 64> Record;
 809
 810   // Write metadata attachments
 811   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 812   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 813
 814   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 815     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 816          I != E; ++I) {
 817       MDs.clear();
 818       I->getAllMetadataOtherThanDebugLoc(MDs);
 819
 820       // If no metadata, ignore instruction.
 821       if (MDs.empty()) continue;
 822
 823       Record.push_back(VE.getInstructionID(I));
 824
 825       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 826         Record.push_back(MDs[i].first);
 827         Record.push_back(VE.getValueID(MDs[i].second));
 828       }
 829       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 830       Record.clear();
 831     }
 832
 833   Stream.ExitBlock();
 834 }
 835
 836 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 837   SmallVector<uint64_t, 64> Record;
 838
 839   // Write metadata kinds
 840   // METADATA_KIND - [n x [id, name]]
 841   SmallVector<StringRef, 8> Names;
 842   M->getMDKindNames(Names);
 843
 844   if (Names.empty()) return;
 845
 846   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 847
 848   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 849     Record.push_back(MDKindID);
 850     StringRef KName = Names[MDKindID];
 851     Record.append(KName.begin(), KName.end());
 852
 853     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 854     Record.clear();
 855   }
 856
 857   Stream.ExitBlock();
 858 }
 859
 860 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 861   if ((int64_t)V >= 0)
 862     Vals.push_back(V << 1);
 863   else
 864     Vals.push_back((-V << 1) | 1);
 865 }
 866
 867 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 868                            const ValueEnumerator &VE,
 869                            BitstreamWriter &Stream, bool isGlobal) {
 870   if (FirstVal == LastVal) return;
 871
 872   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 873
 874   unsigned AggregateAbbrev = 0;
 875   unsigned String8Abbrev = 0;
 876   unsigned CString7Abbrev = 0;
 877   unsigned CString6Abbrev = 0;
 878   // If this is a constant pool for the module, emit module-specific abbrevs.
 879   if (isGlobal) {
 880     // Abbrev for CST_CODE_AGGREGATE.
 881     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 882     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 883     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 884     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 885     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 886
 887     // Abbrev for CST_CODE_STRING.
 888     Abbv = new BitCodeAbbrev();
 889     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 890     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 891     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 892     String8Abbrev = Stream.EmitAbbrev(Abbv);
 893     // Abbrev for CST_CODE_CSTRING.
 894     Abbv = new BitCodeAbbrev();
 895     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 896     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 897     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 898     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 899     // Abbrev for CST_CODE_CSTRING.
 900     Abbv = new BitCodeAbbrev();
 901     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 902     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 903     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 904     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 905   }
 906
 907   SmallVector<uint64_t, 64> Record;
 908
 909   const ValueEnumerator::ValueList &Vals = VE.getValues();
 910   Type *LastTy = 0;
 911   for (unsigned i = FirstVal; i != LastVal; ++i) {
 912     const Value *V = Vals[i].first;
 913     // If we need to switch types, do so now.
 914     if (V->getType() != LastTy) {
 915       LastTy = V->getType();
 916       Record.push_back(VE.getTypeID(LastTy));
 917       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 918                         CONSTANTS_SETTYPE_ABBREV);
 919       Record.clear();
 920     }
 921
 922     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 923       Record.push_back(unsigned(IA->hasSideEffects()) |
 924                        unsigned(IA->isAlignStack()) << 1 |
 925                        unsigned(IA->getDialect()&1) << 2);
 926
 927       // Add the asm string.
 928       const std::string &AsmStr = IA->getAsmString();
 929       Record.push_back(AsmStr.size());
 930       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 931         Record.push_back(AsmStr[i]);
 932
 933       // Add the constraint string.
 934       const std::string &ConstraintStr = IA->getConstraintString();
 935       Record.push_back(ConstraintStr.size());
 936       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 937         Record.push_back(ConstraintStr[i]);
 938       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 939       Record.clear();
 940       continue;
 941     }
 942     const Constant *C = cast<Constant>(V);
 943     unsigned Code = -1U;
 944     unsigned AbbrevToUse = 0;
 945     if (C->isNullValue()) {
 946       Code = bitc::CST_CODE_NULL;
 947     } else if (isa<UndefValue>(C)) {
 948       Code = bitc::CST_CODE_UNDEF;
 949     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 950       if (IV->getBitWidth() <= 64) {
 951         uint64_t V = IV->getSExtValue();
 952         emitSignedInt64(Record, V);
 953         Code = bitc::CST_CODE_INTEGER;
 954         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 955       } else {                             // Wide integers, > 64 bits in size.
 956         // We have an arbitrary precision integer value to write whose
 957         // bit width is > 64. However, in canonical unsigned integer
 958         // format it is likely that the high bits are going to be zero.
 959         // So, we only write the number of active words.
 960         unsigned NWords = IV->getValue().getActiveWords();
 961         const uint64_t *RawWords = IV->getValue().getRawData();
 962         for (unsigned i = 0; i != NWords; ++i) {
 963           emitSignedInt64(Record, RawWords[i]);
 964         }
 965         Code = bitc::CST_CODE_WIDE_INTEGER;
 966       }
 967     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 968       Code = bitc::CST_CODE_FLOAT;
 969       Type *Ty = CFP->getType();
 970       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 971         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 972       } else if (Ty->isX86_FP80Ty()) {
 973         // api needed to prevent premature destruction
 974         // bits are not in the same order as a normal i80 APInt, compensate.
 975         APInt api = CFP->getValueAPF().bitcastToAPInt();
 976         const uint64_t *p = api.getRawData();
 977         Record.push_back((p[1] << 48) | (p[0] >> 16));
 978         Record.push_back(p[0] & 0xffffLL);
 979       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 980         APInt api = CFP->getValueAPF().bitcastToAPInt();
 981         const uint64_t *p = api.getRawData();
 982         Record.push_back(p[0]);
 983         Record.push_back(p[1]);
 984       } else {
 985         assert (0 && "Unknown FP type!");
 986       }
 987     } else if (isa<ConstantDataSequential>(C) &&
 988                cast<ConstantDataSequential>(C)->isString()) {
 989       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 990       // Emit constant strings specially.
 991       unsigned NumElts = Str->getNumElements();
 992       // If this is a null-terminated string, use the denser CSTRING encoding.
 993       if (Str->isCString()) {
 994         Code = bitc::CST_CODE_CSTRING;
 995         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 996       } else {
 997         Code = bitc::CST_CODE_STRING;
 998         AbbrevToUse = String8Abbrev;
 999       }
1000       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1001       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1002       for (unsigned i = 0; i != NumElts; ++i) {
1003         unsigned char V = Str->getElementAsInteger(i);
1004         Record.push_back(V);
1005         isCStr7 &= (V & 128) == 0;
1006         if (isCStrChar6)
1007           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1008       }
1009
1010       if (isCStrChar6)
1011         AbbrevToUse = CString6Abbrev;
1012       else if (isCStr7)
1013         AbbrevToUse = CString7Abbrev;
1014     } else if (const ConstantDataSequential *CDS =
1015                   dyn_cast<ConstantDataSequential>(C)) {
1016       Code = bitc::CST_CODE_DATA;
1017       Type *EltTy = CDS->getType()->getElementType();
1018       if (isa<IntegerType>(EltTy)) {
1019         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1020           Record.push_back(CDS->getElementAsInteger(i));
1021       } else if (EltTy->isFloatTy()) {
1022         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1023           union { float F; uint32_t I; };
1024           F = CDS->getElementAsFloat(i);
1025           Record.push_back(I);
1026         }
1027       } else {
1028         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1029         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1030           union { double F; uint64_t I; };
1031           F = CDS->getElementAsDouble(i);
1032           Record.push_back(I);
1033         }
1034       }
1035     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1036                isa<ConstantVector>(C)) {
1037       Code = bitc::CST_CODE_AGGREGATE;
1038       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1039         Record.push_back(VE.getValueID(C->getOperand(i)));
1040       AbbrevToUse = AggregateAbbrev;
1041     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1042       switch (CE->getOpcode()) {
1043       default:
1044         if (Instruction::isCast(CE->getOpcode())) {
1045           Code = bitc::CST_CODE_CE_CAST;
1046           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1047           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1048           Record.push_back(VE.getValueID(C->getOperand(0)));
1049           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1050         } else {
1051           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1052           Code = bitc::CST_CODE_CE_BINOP;
1053           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1054           Record.push_back(VE.getValueID(C->getOperand(0)));
1055           Record.push_back(VE.getValueID(C->getOperand(1)));
1056           uint64_t Flags = GetOptimizationFlags(CE);
1057           if (Flags != 0)
1058             Record.push_back(Flags);
1059         }
1060         break;
1061       case Instruction::GetElementPtr:
1062         Code = bitc::CST_CODE_CE_GEP;
1063         if (cast<GEPOperator>(C)->isInBounds())
1064           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1065         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1066           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1067           Record.push_back(VE.getValueID(C->getOperand(i)));
1068         }
1069         break;
1070       case Instruction::Select:
1071         Code = bitc::CST_CODE_CE_SELECT;
1072         Record.push_back(VE.getValueID(C->getOperand(0)));
1073         Record.push_back(VE.getValueID(C->getOperand(1)));
1074         Record.push_back(VE.getValueID(C->getOperand(2)));
1075         break;
1076       case Instruction::ExtractElement:
1077         Code = bitc::CST_CODE_CE_EXTRACTELT;
1078         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1079         Record.push_back(VE.getValueID(C->getOperand(0)));
1080         Record.push_back(VE.getValueID(C->getOperand(1)));
1081         break;
1082       case Instruction::InsertElement:
1083         Code = bitc::CST_CODE_CE_INSERTELT;
1084         Record.push_back(VE.getValueID(C->getOperand(0)));
1085         Record.push_back(VE.getValueID(C->getOperand(1)));
1086         Record.push_back(VE.getValueID(C->getOperand(2)));
1087         break;
1088       case Instruction::ShuffleVector:
1089         // If the return type and argument types are the same, this is a
1090         // standard shufflevector instruction.  If the types are different,
1091         // then the shuffle is widening or truncating the input vectors, and
1092         // the argument type must also be encoded.
1093         if (C->getType() == C->getOperand(0)->getType()) {
1094           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1095         } else {
1096           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1097           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1098         }
1099         Record.push_back(VE.getValueID(C->getOperand(0)));
1100         Record.push_back(VE.getValueID(C->getOperand(1)));
1101         Record.push_back(VE.getValueID(C->getOperand(2)));
1102         break;
1103       case Instruction::ICmp:
1104       case Instruction::FCmp:
1105         Code = bitc::CST_CODE_CE_CMP;
1106         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1107         Record.push_back(VE.getValueID(C->getOperand(0)));
1108         Record.push_back(VE.getValueID(C->getOperand(1)));
1109         Record.push_back(CE->getPredicate());
1110         break;
1111       }
1112     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1113       Code = bitc::CST_CODE_BLOCKADDRESS;
1114       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1115       Record.push_back(VE.getValueID(BA->getFunction()));
1116       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1117     } else {
1118 #ifndef NDEBUG
1119       C->dump();
1120 #endif
1121       llvm_unreachable("Unknown constant!");
1122     }
1123     Stream.EmitRecord(Code, Record, AbbrevToUse);
1124     Record.clear();
1125   }
1126
1127   Stream.ExitBlock();
1128 }
1129
1130 static void WriteModuleConstants(const ValueEnumerator &VE,
1131                                  BitstreamWriter &Stream) {
1132   const ValueEnumerator::ValueList &Vals = VE.getValues();
1133
1134   // Find the first constant to emit, which is the first non-globalvalue value.
1135   // We know globalvalues have been emitted by WriteModuleInfo.
1136   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1137     if (!isa<GlobalValue>(Vals[i].first)) {
1138       WriteConstants(i, Vals.size(), VE, Stream, true);
1139       return;
1140     }
1141   }
1142 }
1143
1144 /// PushValueAndType - The file has to encode both the value and type id for
1145 /// many values, because we need to know what type to create for forward
1146 /// references.  However, most operands are not forward references, so this type
1147 /// field is not needed.
1148 ///
1149 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1150 /// instruction ID, then it is a forward reference, and it also includes the
1151 /// type ID.  The value ID that is written is encoded relative to the InstID.
1152 static bool PushValueAndType(const Value *V, unsigned InstID,
1153                              SmallVectorImpl<unsigned> &Vals,
1154                              ValueEnumerator &VE) {
1155   unsigned ValID = VE.getValueID(V);
1156   // Make encoding relative to the InstID.
1157   Vals.push_back(InstID - ValID);
1158   if (ValID >= InstID) {
1159     Vals.push_back(VE.getTypeID(V->getType()));
1160     return true;
1161   }
1162   return false;
1163 }
1164
1165 /// pushValue - Like PushValueAndType, but where the type of the value is
1166 /// omitted (perhaps it was already encoded in an earlier operand).
1167 static void pushValue(const Value *V, unsigned InstID,
1168                       SmallVectorImpl<unsigned> &Vals,
1169                       ValueEnumerator &VE) {
1170   unsigned ValID = VE.getValueID(V);
1171   Vals.push_back(InstID - ValID);
1172 }
1173
1174 static void pushValueSigned(const Value *V, unsigned InstID,
1175                             SmallVectorImpl<uint64_t> &Vals,
1176                             ValueEnumerator &VE) {
1177   unsigned ValID = VE.getValueID(V);
1178   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1179   emitSignedInt64(Vals, diff);
1180 }
1181
1182 /// WriteInstruction - Emit an instruction to the specified stream.
1183 static void WriteInstruction(const Instruction &I, unsigned InstID,
1184                              ValueEnumerator &VE, BitstreamWriter &Stream,
1185                              SmallVectorImpl<unsigned> &Vals) {
1186   unsigned Code = 0;
1187   unsigned AbbrevToUse = 0;
1188   VE.setInstructionID(&I);
1189   switch (I.getOpcode()) {
1190   default:
1191     if (Instruction::isCast(I.getOpcode())) {
1192       Code = bitc::FUNC_CODE_INST_CAST;
1193       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1194         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1195       Vals.push_back(VE.getTypeID(I.getType()));
1196       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1197     } else {
1198       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1199       Code = bitc::FUNC_CODE_INST_BINOP;
1200       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1201         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1202       pushValue(I.getOperand(1), InstID, Vals, VE);
1203       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1204       uint64_t Flags = GetOptimizationFlags(&I);
1205       if (Flags != 0) {
1206         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1207           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1208         Vals.push_back(Flags);
1209       }
1210     }
1211     break;
1212
1213   case Instruction::GetElementPtr:
1214     Code = bitc::FUNC_CODE_INST_GEP;
1215     if (cast<GEPOperator>(&I)->isInBounds())
1216       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1217     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1218       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1219     break;
1220   case Instruction::ExtractValue: {
1221     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1222     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1223     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1224     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1225       Vals.push_back(*i);
1226     break;
1227   }
1228   case Instruction::InsertValue: {
1229     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1230     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1231     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1232     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1233     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1234       Vals.push_back(*i);
1235     break;
1236   }
1237   case Instruction::Select:
1238     Code = bitc::FUNC_CODE_INST_VSELECT;
1239     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1240     pushValue(I.getOperand(2), InstID, Vals, VE);
1241     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1242     break;
1243   case Instruction::ExtractElement:
1244     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1245     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1246     pushValue(I.getOperand(1), InstID, Vals, VE);
1247     break;
1248   case Instruction::InsertElement:
1249     Code = bitc::FUNC_CODE_INST_INSERTELT;
1250     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1251     pushValue(I.getOperand(1), InstID, Vals, VE);
1252     pushValue(I.getOperand(2), InstID, Vals, VE);
1253     break;
1254   case Instruction::ShuffleVector:
1255     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1256     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1257     pushValue(I.getOperand(1), InstID, Vals, VE);
1258     pushValue(I.getOperand(2), InstID, Vals, VE);
1259     break;
1260   case Instruction::ICmp:
1261   case Instruction::FCmp:
1262     // compare returning Int1Ty or vector of Int1Ty
1263     Code = bitc::FUNC_CODE_INST_CMP2;
1264     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1265     pushValue(I.getOperand(1), InstID, Vals, VE);
1266     Vals.push_back(cast<CmpInst>(I).getPredicate());
1267     break;
1268
1269   case Instruction::Ret:
1270     {
1271       Code = bitc::FUNC_CODE_INST_RET;
1272       unsigned NumOperands = I.getNumOperands();
1273       if (NumOperands == 0)
1274         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1275       else if (NumOperands == 1) {
1276         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1277           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1278       } else {
1279         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1280           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1281       }
1282     }
1283     break;
1284   case Instruction::Br:
1285     {
1286       Code = bitc::FUNC_CODE_INST_BR;
1287       const BranchInst &II = cast<BranchInst>(I);
1288       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1289       if (II.isConditional()) {
1290         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1291         pushValue(II.getCondition(), InstID, Vals, VE);
1292       }
1293     }
1294     break;
1295   case Instruction::Switch:
1296     {
1297       Code = bitc::FUNC_CODE_INST_SWITCH;
1298       const SwitchInst &SI = cast<SwitchInst>(I);
1299       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1300       pushValue(SI.getCondition(), InstID, Vals, VE);
1301       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1302       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1303            i != e; ++i) {
1304         Vals.push_back(VE.getValueID(i.getCaseValue()));
1305         Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1306       }
1307     }
1308     break;
1309   case Instruction::IndirectBr:
1310     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1311     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1312     // Encode the address operand as relative, but not the basic blocks.
1313     pushValue(I.getOperand(0), InstID, Vals, VE);
1314     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1315       Vals.push_back(VE.getValueID(I.getOperand(i)));
1316     break;
1317
1318   case Instruction::Invoke: {
1319     const InvokeInst *II = cast<InvokeInst>(&I);
1320     const Value *Callee(II->getCalledValue());
1321     PointerType *PTy = cast<PointerType>(Callee->getType());
1322     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1323     Code = bitc::FUNC_CODE_INST_INVOKE;
1324
1325     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1326     Vals.push_back(II->getCallingConv());
1327     Vals.push_back(VE.getValueID(II->getNormalDest()));
1328     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1329     PushValueAndType(Callee, InstID, Vals, VE);
1330
1331     // Emit value #'s for the fixed parameters.
1332     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1333       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1334
1335     // Emit type/value pairs for varargs params.
1336     if (FTy->isVarArg()) {
1337       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1338            i != e; ++i)
1339         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1340     }
1341     break;
1342   }
1343   case Instruction::Resume:
1344     Code = bitc::FUNC_CODE_INST_RESUME;
1345     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1346     break;
1347   case Instruction::Unreachable:
1348     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1349     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1350     break;
1351
1352   case Instruction::PHI: {
1353     const PHINode &PN = cast<PHINode>(I);
1354     Code = bitc::FUNC_CODE_INST_PHI;
1355     // With the newer instruction encoding, forward references could give
1356     // negative valued IDs.  This is most common for PHIs, so we use
1357     // signed VBRs.
1358     SmallVector<uint64_t, 128> Vals64;
1359     Vals64.push_back(VE.getTypeID(PN.getType()));
1360     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1361       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1362       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1363     }
1364     // Emit a Vals64 vector and exit.
1365     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1366     Vals64.clear();
1367     return;
1368   }
1369
1370   case Instruction::LandingPad: {
1371     const LandingPadInst &LP = cast<LandingPadInst>(I);
1372     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1373     Vals.push_back(VE.getTypeID(LP.getType()));
1374     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1375     Vals.push_back(LP.isCleanup());
1376     Vals.push_back(LP.getNumClauses());
1377     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1378       if (LP.isCatch(I))
1379         Vals.push_back(LandingPadInst::Catch);
1380       else
1381         Vals.push_back(LandingPadInst::Filter);
1382       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1383     }
1384     break;
1385   }
1386
1387   case Instruction::Alloca:
1388     Code = bitc::FUNC_CODE_INST_ALLOCA;
1389     Vals.push_back(VE.getTypeID(I.getType()));
1390     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1391     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1392     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1393     break;
1394
1395   case Instruction::Load:
1396     if (cast<LoadInst>(I).isAtomic()) {
1397       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1398       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1399     } else {
1400       Code = bitc::FUNC_CODE_INST_LOAD;
1401       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1402         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1403     }
1404     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1405     Vals.push_back(cast<LoadInst>(I).isVolatile());
1406     if (cast<LoadInst>(I).isAtomic()) {
1407       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1408       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1409     }
1410     break;
1411   case Instruction::Store:
1412     if (cast<StoreInst>(I).isAtomic())
1413       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1414     else
1415       Code = bitc::FUNC_CODE_INST_STORE;
1416     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1417     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1418     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1419     Vals.push_back(cast<StoreInst>(I).isVolatile());
1420     if (cast<StoreInst>(I).isAtomic()) {
1421       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1422       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1423     }
1424     break;
1425   case Instruction::AtomicCmpXchg:
1426     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1427     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1428     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1429     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1430     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1431     Vals.push_back(GetEncodedOrdering(
1432                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1433     Vals.push_back(GetEncodedSynchScope(
1434                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1435     break;
1436   case Instruction::AtomicRMW:
1437     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1438     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1439     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1440     Vals.push_back(GetEncodedRMWOperation(
1441                      cast<AtomicRMWInst>(I).getOperation()));
1442     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1443     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1444     Vals.push_back(GetEncodedSynchScope(
1445                      cast<AtomicRMWInst>(I).getSynchScope()));
1446     break;
1447   case Instruction::Fence:
1448     Code = bitc::FUNC_CODE_INST_FENCE;
1449     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1450     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1451     break;
1452   case Instruction::Call: {
1453     const CallInst &CI = cast<CallInst>(I);
1454     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1455     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1456
1457     Code = bitc::FUNC_CODE_INST_CALL;
1458
1459     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1460     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1461     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1462
1463     // Emit value #'s for the fixed parameters.
1464     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1465       // Check for labels (can happen with asm labels).
1466       if (FTy->getParamType(i)->isLabelTy())
1467         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1468       else
1469         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1470     }
1471
1472     // Emit type/value pairs for varargs params.
1473     if (FTy->isVarArg()) {
1474       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1475            i != e; ++i)
1476         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1477     }
1478     break;
1479   }
1480   case Instruction::VAArg:
1481     Code = bitc::FUNC_CODE_INST_VAARG;
1482     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1483     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1484     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1485     break;
1486   }
1487
1488   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1489   Vals.clear();
1490 }
1491
1492 // Emit names for globals/functions etc.
1493 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1494                                   const ValueEnumerator &VE,
1495                                   BitstreamWriter &Stream) {
1496   if (VST.empty()) return;
1497   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1498
1499   // FIXME: Set up the abbrev, we know how many values there are!
1500   // FIXME: We know if the type names can use 7-bit ascii.
1501   SmallVector<unsigned, 64> NameVals;
1502
1503   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1504        SI != SE; ++SI) {
1505
1506     const ValueName &Name = *SI;
1507
1508     // Figure out the encoding to use for the name.
1509     bool is7Bit = true;
1510     bool isChar6 = true;
1511     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1512          C != E; ++C) {
1513       if (isChar6)
1514         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1515       if ((unsigned char)*C & 128) {
1516         is7Bit = false;
1517         break;  // don't bother scanning the rest.
1518       }
1519     }
1520
1521     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1522
1523     // VST_ENTRY:   [valueid, namechar x N]
1524     // VST_BBENTRY: [bbid, namechar x N]
1525     unsigned Code;
1526     if (isa<BasicBlock>(SI->getValue())) {
1527       Code = bitc::VST_CODE_BBENTRY;
1528       if (isChar6)
1529         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1530     } else {
1531       Code = bitc::VST_CODE_ENTRY;
1532       if (isChar6)
1533         AbbrevToUse = VST_ENTRY_6_ABBREV;
1534       else if (is7Bit)
1535         AbbrevToUse = VST_ENTRY_7_ABBREV;
1536     }
1537
1538     NameVals.push_back(VE.getValueID(SI->getValue()));
1539     for (const char *P = Name.getKeyData(),
1540          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1541       NameVals.push_back((unsigned char)*P);
1542
1543     // Emit the finished record.
1544     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1545     NameVals.clear();
1546   }
1547   Stream.ExitBlock();
1548 }
1549
1550 /// WriteFunction - Emit a function body to the module stream.
1551 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1552                           BitstreamWriter &Stream) {
1553   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1554   VE.incorporateFunction(F);
1555
1556   SmallVector<unsigned, 64> Vals;
1557
1558   // Emit the number of basic blocks, so the reader can create them ahead of
1559   // time.
1560   Vals.push_back(VE.getBasicBlocks().size());
1561   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1562   Vals.clear();
1563
1564   // If there are function-local constants, emit them now.
1565   unsigned CstStart, CstEnd;
1566   VE.getFunctionConstantRange(CstStart, CstEnd);
1567   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1568
1569   // If there is function-local metadata, emit it now.
1570   WriteFunctionLocalMetadata(F, VE, Stream);
1571
1572   // Keep a running idea of what the instruction ID is.
1573   unsigned InstID = CstEnd;
1574
1575   bool NeedsMetadataAttachment = false;
1576
1577   DebugLoc LastDL;
1578
1579   // Finally, emit all the instructions, in order.
1580   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1581     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1582          I != E; ++I) {
1583       WriteInstruction(*I, InstID, VE, Stream, Vals);
1584
1585       if (!I->getType()->isVoidTy())
1586         ++InstID;
1587
1588       // If the instruction has metadata, write a metadata attachment later.
1589       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1590
1591       // If the instruction has a debug location, emit it.
1592       DebugLoc DL = I->getDebugLoc();
1593       if (DL.isUnknown()) {
1594         // nothing todo.
1595       } else if (DL == LastDL) {
1596         // Just repeat the same debug loc as last time.
1597         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1598       } else {
1599         MDNode *Scope, *IA;
1600         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1601
1602         Vals.push_back(DL.getLine());
1603         Vals.push_back(DL.getCol());
1604         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1605         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1606         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1607         Vals.clear();
1608
1609         LastDL = DL;
1610       }
1611     }
1612
1613   // Emit names for all the instructions etc.
1614   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1615
1616   if (NeedsMetadataAttachment)
1617     WriteMetadataAttachment(F, VE, Stream);
1618   VE.purgeFunction();
1619   Stream.ExitBlock();
1620 }
1621
1622 // Emit blockinfo, which defines the standard abbreviations etc.
1623 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1624   // We only want to emit block info records for blocks that have multiple
1625   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1626   // Other blocks can define their abbrevs inline.
1627   Stream.EnterBlockInfoBlock(2);
1628
1629   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1630     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1631     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1632     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1633     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1634     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1635     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1636                                    Abbv) != VST_ENTRY_8_ABBREV)
1637       llvm_unreachable("Unexpected abbrev ordering!");
1638   }
1639
1640   { // 7-bit fixed width VST_ENTRY strings.
1641     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1642     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1643     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1644     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1645     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1646     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1647                                    Abbv) != VST_ENTRY_7_ABBREV)
1648       llvm_unreachable("Unexpected abbrev ordering!");
1649   }
1650   { // 6-bit char6 VST_ENTRY strings.
1651     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1652     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1653     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1654     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1655     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1656     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1657                                    Abbv) != VST_ENTRY_6_ABBREV)
1658       llvm_unreachable("Unexpected abbrev ordering!");
1659   }
1660   { // 6-bit char6 VST_BBENTRY strings.
1661     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1662     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1663     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1664     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1665     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1666     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1667                                    Abbv) != VST_BBENTRY_6_ABBREV)
1668       llvm_unreachable("Unexpected abbrev ordering!");
1669   }
1670
1671
1672
1673   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1674     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1675     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1676     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1677                               Log2_32_Ceil(VE.getTypes().size()+1)));
1678     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1679                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1680       llvm_unreachable("Unexpected abbrev ordering!");
1681   }
1682
1683   { // INTEGER abbrev for CONSTANTS_BLOCK.
1684     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1685     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1686     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1687     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1688                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1689       llvm_unreachable("Unexpected abbrev ordering!");
1690   }
1691
1692   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1693     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1694     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1695     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1696     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1697                               Log2_32_Ceil(VE.getTypes().size()+1)));
1698     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1699
1700     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1701                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1702       llvm_unreachable("Unexpected abbrev ordering!");
1703   }
1704   { // NULL abbrev for CONSTANTS_BLOCK.
1705     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1706     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1707     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1708                                    Abbv) != CONSTANTS_NULL_Abbrev)
1709       llvm_unreachable("Unexpected abbrev ordering!");
1710   }
1711
1712   // FIXME: This should only use space for first class types!
1713
1714   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1715     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1716     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1717     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1718     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1719     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1720     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1721                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1722       llvm_unreachable("Unexpected abbrev ordering!");
1723   }
1724   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1725     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1726     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1727     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1728     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1729     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1730     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1731                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1732       llvm_unreachable("Unexpected abbrev ordering!");
1733   }
1734   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1735     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1736     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1737     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1738     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1739     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1740     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1741     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1742                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1743       llvm_unreachable("Unexpected abbrev ordering!");
1744   }
1745   { // INST_CAST abbrev for FUNCTION_BLOCK.
1746     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1747     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1748     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1749     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1750                               Log2_32_Ceil(VE.getTypes().size()+1)));
1751     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1752     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1753                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1754       llvm_unreachable("Unexpected abbrev ordering!");
1755   }
1756
1757   { // INST_RET abbrev for FUNCTION_BLOCK.
1758     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1759     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1760     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1761                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1762       llvm_unreachable("Unexpected abbrev ordering!");
1763   }
1764   { // INST_RET abbrev for FUNCTION_BLOCK.
1765     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1766     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1767     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1768     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1769                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1770       llvm_unreachable("Unexpected abbrev ordering!");
1771   }
1772   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1773     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1774     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1775     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1776                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1777       llvm_unreachable("Unexpected abbrev ordering!");
1778   }
1779
1780   Stream.ExitBlock();
1781 }
1782
1783 // Sort the Users based on the order in which the reader parses the bitcode
1784 // file.
1785 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1786   // TODO: Implement.
1787   return true;
1788 }
1789
1790 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1791                          BitstreamWriter &Stream) {
1792
1793   // One or zero uses can't get out of order.
1794   if (V->use_empty() || V->hasNUses(1))
1795     return;
1796
1797   // Make a copy of the in-memory use-list for sorting.
1798   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1799   SmallVector<const User*, 8> UseList;
1800   UseList.reserve(UseListSize);
1801   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1802        I != E; ++I) {
1803     const User *U = *I;
1804     UseList.push_back(U);
1805   }
1806
1807   // Sort the copy based on the order read by the BitcodeReader.
1808   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1809
1810   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1811   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1812
1813   // TODO: Emit the USELIST_CODE_ENTRYs.
1814 }
1815
1816 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1817                                  BitstreamWriter &Stream) {
1818   VE.incorporateFunction(*F);
1819
1820   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1821        AI != AE; ++AI)
1822     WriteUseList(AI, VE, Stream);
1823   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1824        ++BB) {
1825     WriteUseList(BB, VE, Stream);
1826     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1827          ++II) {
1828       WriteUseList(II, VE, Stream);
1829       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1830            OI != E; ++OI) {
1831         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1832             isa<InlineAsm>(*OI))
1833           WriteUseList(*OI, VE, Stream);
1834       }
1835     }
1836   }
1837   VE.purgeFunction();
1838 }
1839
1840 // Emit use-lists.
1841 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1842                                 BitstreamWriter &Stream) {
1843   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1844
1845   // XXX: this modifies the module, but in a way that should never change the
1846   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1847   // contain entries in the use_list that do not exist in the Module and are
1848   // not stored in the .bc file.
1849   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1850        I != E; ++I)
1851     I->removeDeadConstantUsers();
1852
1853   // Write the global variables.
1854   for (Module::const_global_iterator GI = M->global_begin(),
1855          GE = M->global_end(); GI != GE; ++GI) {
1856     WriteUseList(GI, VE, Stream);
1857
1858     // Write the global variable initializers.
1859     if (GI->hasInitializer())
1860       WriteUseList(GI->getInitializer(), VE, Stream);
1861   }
1862
1863   // Write the functions.
1864   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1865     WriteUseList(FI, VE, Stream);
1866     if (!FI->isDeclaration())
1867       WriteFunctionUseList(FI, VE, Stream);
1868     if (FI->hasPrefixData())
1869       WriteUseList(FI->getPrefixData(), VE, Stream);
1870   }
1871
1872   // Write the aliases.
1873   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1874        AI != AE; ++AI) {
1875     WriteUseList(AI, VE, Stream);
1876     WriteUseList(AI->getAliasee(), VE, Stream);
1877   }
1878
1879   Stream.ExitBlock();
1880 }
1881
1882 /// WriteModule - Emit the specified module to the bitstream.
1883 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1884   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1885
1886   SmallVector<unsigned, 1> Vals;
1887   unsigned CurVersion = 1;
1888   Vals.push_back(CurVersion);
1889   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1890
1891   // Analyze the module, enumerating globals, functions, etc.
1892   ValueEnumerator VE(M);
1893
1894   // Emit blockinfo, which defines the standard abbreviations etc.
1895   WriteBlockInfo(VE, Stream);
1896
1897   // Emit information about attribute groups.
1898   WriteAttributeGroupTable(VE, Stream);
1899
1900   // Emit information about parameter attributes.
1901   WriteAttributeTable(VE, Stream);
1902
1903   // Emit information describing all of the types in the module.
1904   WriteTypeTable(VE, Stream);
1905
1906   // Emit top-level description of module, including target triple, inline asm,
1907   // descriptors for global variables, and function prototype info.
1908   WriteModuleInfo(M, VE, Stream);
1909
1910   // Emit constants.
1911   WriteModuleConstants(VE, Stream);
1912
1913   // Emit metadata.
1914   WriteModuleMetadata(M, VE, Stream);
1915
1916   // Emit metadata.
1917   WriteModuleMetadataStore(M, Stream);
1918
1919   // Emit names for globals/functions etc.
1920   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1921
1922   // Emit use-lists.
1923   if (EnablePreserveUseListOrdering)
1924     WriteModuleUseLists(M, VE, Stream);
1925
1926   // Emit function bodies.
1927   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1928     if (!F->isDeclaration())
1929       WriteFunction(*F, VE, Stream);
1930
1931   Stream.ExitBlock();
1932 }
1933
1934 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1935 /// header and trailer to make it compatible with the system archiver.  To do
1936 /// this we emit the following header, and then emit a trailer that pads the
1937 /// file out to be a multiple of 16 bytes.
1938 ///
1939 /// struct bc_header {
1940 ///   uint32_t Magic;         // 0x0B17C0DE
1941 ///   uint32_t Version;       // Version, currently always 0.
1942 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1943 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1944 ///   uint32_t CPUType;       // CPU specifier.
1945 ///   ... potentially more later ...
1946 /// };
1947 enum {
1948   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1949   DarwinBCHeaderSize = 5*4
1950 };
1951
1952 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1953                                uint32_t &Position) {
1954   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1955   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1956   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1957   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1958   Position += 4;
1959 }
1960
1961 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1962                                          const Triple &TT) {
1963   unsigned CPUType = ~0U;
1964
1965   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1966   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1967   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1968   // specific constants here because they are implicitly part of the Darwin ABI.
1969   enum {
1970     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1971     DARWIN_CPU_TYPE_X86        = 7,
1972     DARWIN_CPU_TYPE_ARM        = 12,
1973     DARWIN_CPU_TYPE_POWERPC    = 18
1974   };
1975
1976   Triple::ArchType Arch = TT.getArch();
1977   if (Arch == Triple::x86_64)
1978     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1979   else if (Arch == Triple::x86)
1980     CPUType = DARWIN_CPU_TYPE_X86;
1981   else if (Arch == Triple::ppc)
1982     CPUType = DARWIN_CPU_TYPE_POWERPC;
1983   else if (Arch == Triple::ppc64)
1984     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1985   else if (Arch == Triple::arm || Arch == Triple::thumb)
1986     CPUType = DARWIN_CPU_TYPE_ARM;
1987
1988   // Traditional Bitcode starts after header.
1989   assert(Buffer.size() >= DarwinBCHeaderSize &&
1990          "Expected header size to be reserved");
1991   unsigned BCOffset = DarwinBCHeaderSize;
1992   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1993
1994   // Write the magic and version.
1995   unsigned Position = 0;
1996   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1997   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1998   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1999   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2000   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2001
2002   // If the file is not a multiple of 16 bytes, insert dummy padding.
2003   while (Buffer.size() & 15)
2004     Buffer.push_back(0);
2005 }
2006
2007 /// WriteBitcodeToFile - Write the specified module to the specified output
2008 /// stream.
2009 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2010   SmallVector<char, 0> Buffer;
2011   Buffer.reserve(256*1024);
2012
2013   // If this is darwin or another generic macho target, reserve space for the
2014   // header.
2015   Triple TT(M->getTargetTriple());
2016   if (TT.isOSDarwin())
2017     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2018
2019   // Emit the module into the buffer.
2020   {
2021     BitstreamWriter Stream(Buffer);
2022
2023     // Emit the file header.
2024     Stream.Emit((unsigned)'B', 8);
2025     Stream.Emit((unsigned)'C', 8);
2026     Stream.Emit(0x0, 4);
2027     Stream.Emit(0xC, 4);
2028     Stream.Emit(0xE, 4);
2029     Stream.Emit(0xD, 4);
2030
2031     // Emit the module.
2032     WriteModule(M, Stream);
2033   }
2034
2035   if (TT.isOSDarwin())
2036     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2037
2038   // Write the generated bitstream to "Out".
2039   Out.write((char*)&Buffer.front(), Buffer.size());
2040 }