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   // SwitchInst Magic
  66   SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
  67 };
  68
  69 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  70   switch (Opcode) {
  71   default: llvm_unreachable("Unknown cast instruction!");
  72   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  73   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  74   case Instruction::SExt    : return bitc::CAST_SEXT;
  75   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  76   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  77   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  78   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  79   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  80   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  81   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  82   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  83   case Instruction::BitCast : return bitc::CAST_BITCAST;
  84   }
  85 }
  86
  87 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  88   switch (Opcode) {
  89   default: llvm_unreachable("Unknown binary instruction!");
  90   case Instruction::Add:
  91   case Instruction::FAdd: return bitc::BINOP_ADD;
  92   case Instruction::Sub:
  93   case Instruction::FSub: return bitc::BINOP_SUB;
  94   case Instruction::Mul:
  95   case Instruction::FMul: return bitc::BINOP_MUL;
  96   case Instruction::UDiv: return bitc::BINOP_UDIV;
  97   case Instruction::FDiv:
  98   case Instruction::SDiv: return bitc::BINOP_SDIV;
  99   case Instruction::URem: return bitc::BINOP_UREM;
 100   case Instruction::FRem:
 101   case Instruction::SRem: return bitc::BINOP_SREM;
 102   case Instruction::Shl:  return bitc::BINOP_SHL;
 103   case Instruction::LShr: return bitc::BINOP_LSHR;
 104   case Instruction::AShr: return bitc::BINOP_ASHR;
 105   case Instruction::And:  return bitc::BINOP_AND;
 106   case Instruction::Or:   return bitc::BINOP_OR;
 107   case Instruction::Xor:  return bitc::BINOP_XOR;
 108   }
 109 }
 110
 111 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 112   switch (Op) {
 113   default: llvm_unreachable("Unknown RMW operation!");
 114   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 115   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 116   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 117   case AtomicRMWInst::And: return bitc::RMW_AND;
 118   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 119   case AtomicRMWInst::Or: return bitc::RMW_OR;
 120   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 121   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 122   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 123   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 124   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 125   }
 126 }
 127
 128 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 129   switch (Ordering) {
 130   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 131   case Unordered: return bitc::ORDERING_UNORDERED;
 132   case Monotonic: return bitc::ORDERING_MONOTONIC;
 133   case Acquire: return bitc::ORDERING_ACQUIRE;
 134   case Release: return bitc::ORDERING_RELEASE;
 135   case AcquireRelease: return bitc::ORDERING_ACQREL;
 136   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 137   }
 138   llvm_unreachable("Invalid ordering");
 139 }
 140
 141 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 142   switch (SynchScope) {
 143   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 144   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 145   }
 146   llvm_unreachable("Invalid synch scope");
 147 }
 148
 149 static void WriteStringRecord(unsigned Code, StringRef Str,
 150                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 151   SmallVector<unsigned, 64> Vals;
 152
 153   // Code: [strchar x N]
 154   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 155     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 156       AbbrevToUse = 0;
 157     Vals.push_back(Str[i]);
 158   }
 159
 160   // Emit the finished record.
 161   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 162 }
 163
 164 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
 165                                      BitstreamWriter &Stream) {
 166   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
 167   if (AttrGrps.empty()) return;
 168
 169   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 170
 171   SmallVector<uint64_t, 64> Record;
 172   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
 173     AttributeSet AS = AttrGrps[i];
 174     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
 175       AttributeSet A = AS.getSlotAttributes(i);
 176
 177       Record.push_back(VE.getAttributeGroupID(A));
 178       Record.push_back(AS.getSlotIndex(i));
 179
 180       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
 181            I != E; ++I) {
 182         Attribute Attr = *I;
 183         if (Attr.isEnumAttribute()) {
 184           Record.push_back(0);
 185           Record.push_back(Attr.getKindAsEnum());
 186         } else if (Attr.isAlignAttribute()) {
 187           Record.push_back(1);
 188           Record.push_back(Attr.getKindAsEnum());
 189           Record.push_back(Attr.getValueAsInt());
 190         } else {
 191           StringRef Kind = Attr.getKindAsString();
 192           StringRef Val = Attr.getValueAsString();
 193
 194           Record.push_back(Val.empty() ? 3 : 4);
 195           Record.append(Kind.begin(), Kind.end());
 196           Record.push_back(0);
 197           if (!Val.empty()) {
 198             Record.append(Val.begin(), Val.end());
 199             Record.push_back(0);
 200           }
 201         }
 202       }
 203
 204       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
 205       Record.clear();
 206     }
 207   }
 208
 209   Stream.ExitBlock();
 210 }
 211
 212 static void WriteAttributeTable(const ValueEnumerator &VE,
 213                                 BitstreamWriter &Stream) {
 214   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 215   if (Attrs.empty()) return;
 216
 217   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 218
 219   SmallVector<uint64_t, 64> Record;
 220   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 221     const AttributeSet &A = Attrs[i];
 222     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
 223       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
 224
 225     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 226     Record.clear();
 227   }
 228
 229   Stream.ExitBlock();
 230 }
 231
 232 /// WriteTypeTable - Write out the type table for a module.
 233 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 234   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 235
 236   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 237   SmallVector<uint64_t, 64> TypeVals;
 238
 239   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 240
 241   // Abbrev for TYPE_CODE_POINTER.
 242   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 243   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 244   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 245   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 246   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 247
 248   // Abbrev for TYPE_CODE_FUNCTION.
 249   Abbv = new BitCodeAbbrev();
 250   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 251   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 252   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 253   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 254
 255   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 256
 257   // Abbrev for TYPE_CODE_STRUCT_ANON.
 258   Abbv = new BitCodeAbbrev();
 259   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 260   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 261   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 262   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 263
 264   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 265
 266   // Abbrev for TYPE_CODE_STRUCT_NAME.
 267   Abbv = new BitCodeAbbrev();
 268   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 269   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 270   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 271   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 272
 273   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 274   Abbv = new BitCodeAbbrev();
 275   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 276   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 277   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 278   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 279
 280   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 281
 282   // Abbrev for TYPE_CODE_ARRAY.
 283   Abbv = new BitCodeAbbrev();
 284   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 285   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 286   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 287
 288   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 289
 290   // Emit an entry count so the reader can reserve space.
 291   TypeVals.push_back(TypeList.size());
 292   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 293   TypeVals.clear();
 294
 295   // Loop over all of the types, emitting each in turn.
 296   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 297     Type *T = TypeList[i];
 298     int AbbrevToUse = 0;
 299     unsigned Code = 0;
 300
 301     switch (T->getTypeID()) {
 302     default: llvm_unreachable("Unknown type!");
 303     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 304     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 305     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 306     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 307     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 308     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 309     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 310     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 311     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 312     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 313     case Type::IntegerTyID:
 314       // INTEGER: [width]
 315       Code = bitc::TYPE_CODE_INTEGER;
 316       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 317       break;
 318     case Type::PointerTyID: {
 319       PointerType *PTy = cast<PointerType>(T);
 320       // POINTER: [pointee type, address space]
 321       Code = bitc::TYPE_CODE_POINTER;
 322       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 323       unsigned AddressSpace = PTy->getAddressSpace();
 324       TypeVals.push_back(AddressSpace);
 325       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 326       break;
 327     }
 328     case Type::FunctionTyID: {
 329       FunctionType *FT = cast<FunctionType>(T);
 330       // FUNCTION: [isvararg, retty, paramty x N]
 331       Code = bitc::TYPE_CODE_FUNCTION;
 332       TypeVals.push_back(FT->isVarArg());
 333       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 334       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 335         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 336       AbbrevToUse = FunctionAbbrev;
 337       break;
 338     }
 339     case Type::StructTyID: {
 340       StructType *ST = cast<StructType>(T);
 341       // STRUCT: [ispacked, eltty x N]
 342       TypeVals.push_back(ST->isPacked());
 343       // Output all of the element types.
 344       for (StructType::element_iterator I = ST->element_begin(),
 345            E = ST->element_end(); I != E; ++I)
 346         TypeVals.push_back(VE.getTypeID(*I));
 347
 348       if (ST->isLiteral()) {
 349         Code = bitc::TYPE_CODE_STRUCT_ANON;
 350         AbbrevToUse = StructAnonAbbrev;
 351       } else {
 352         if (ST->isOpaque()) {
 353           Code = bitc::TYPE_CODE_OPAQUE;
 354         } else {
 355           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 356           AbbrevToUse = StructNamedAbbrev;
 357         }
 358
 359         // Emit the name if it is present.
 360         if (!ST->getName().empty())
 361           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 362                             StructNameAbbrev, Stream);
 363       }
 364       break;
 365     }
 366     case Type::ArrayTyID: {
 367       ArrayType *AT = cast<ArrayType>(T);
 368       // ARRAY: [numelts, eltty]
 369       Code = bitc::TYPE_CODE_ARRAY;
 370       TypeVals.push_back(AT->getNumElements());
 371       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 372       AbbrevToUse = ArrayAbbrev;
 373       break;
 374     }
 375     case Type::VectorTyID: {
 376       VectorType *VT = cast<VectorType>(T);
 377       // VECTOR [numelts, eltty]
 378       Code = bitc::TYPE_CODE_VECTOR;
 379       TypeVals.push_back(VT->getNumElements());
 380       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 381       break;
 382     }
 383     }
 384
 385     // Emit the finished record.
 386     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 387     TypeVals.clear();
 388   }
 389
 390   Stream.ExitBlock();
 391 }
 392
 393 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 394   switch (GV->getLinkage()) {
 395   case GlobalValue::ExternalLinkage:                 return 0;
 396   case GlobalValue::WeakAnyLinkage:                  return 1;
 397   case GlobalValue::AppendingLinkage:                return 2;
 398   case GlobalValue::InternalLinkage:                 return 3;
 399   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 400   case GlobalValue::DLLImportLinkage:                return 5;
 401   case GlobalValue::DLLExportLinkage:                return 6;
 402   case GlobalValue::ExternalWeakLinkage:             return 7;
 403   case GlobalValue::CommonLinkage:                   return 8;
 404   case GlobalValue::PrivateLinkage:                  return 9;
 405   case GlobalValue::WeakODRLinkage:                  return 10;
 406   case GlobalValue::LinkOnceODRLinkage:              return 11;
 407   case GlobalValue::AvailableExternallyLinkage:      return 12;
 408   case GlobalValue::LinkerPrivateLinkage:            return 13;
 409   case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
 410   case GlobalValue::LinkOnceODRAutoHideLinkage:      return 15;
 411   }
 412   llvm_unreachable("Invalid linkage");
 413 }
 414
 415 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 416   switch (GV->getVisibility()) {
 417   case GlobalValue::DefaultVisibility:   return 0;
 418   case GlobalValue::HiddenVisibility:    return 1;
 419   case GlobalValue::ProtectedVisibility: return 2;
 420   }
 421   llvm_unreachable("Invalid visibility");
 422 }
 423
 424 static unsigned getEncodedThreadLocalMode(const GlobalVariable *GV) {
 425   switch (GV->getThreadLocalMode()) {
 426     case GlobalVariable::NotThreadLocal:         return 0;
 427     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 428     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 429     case GlobalVariable::InitialExecTLSModel:    return 3;
 430     case GlobalVariable::LocalExecTLSModel:      return 4;
 431   }
 432   llvm_unreachable("Invalid TLS model");
 433 }
 434
 435 // Emit top-level description of module, including target triple, inline asm,
 436 // descriptors for global variables, and function prototype info.
 437 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 438                             BitstreamWriter &Stream) {
 439   // Emit various pieces of data attached to a module.
 440   if (!M->getTargetTriple().empty())
 441     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 442                       0/*TODO*/, Stream);
 443   if (!M->getDataLayout().empty())
 444     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 445                       0/*TODO*/, Stream);
 446   if (!M->getModuleInlineAsm().empty())
 447     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 448                       0/*TODO*/, Stream);
 449
 450   // Emit information about sections and GC, computing how many there are. Also
 451   // compute the maximum alignment value.
 452   std::map<std::string, unsigned> SectionMap;
 453   std::map<std::string, unsigned> GCMap;
 454   unsigned MaxAlignment = 0;
 455   unsigned MaxGlobalType = 0;
 456   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 457        GV != E; ++GV) {
 458     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 459     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 460     if (GV->hasSection()) {
 461       // Give section names unique ID's.
 462       unsigned &Entry = SectionMap[GV->getSection()];
 463       if (!Entry) {
 464         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 465                           0/*TODO*/, Stream);
 466         Entry = SectionMap.size();
 467       }
 468     }
 469   }
 470   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 471     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 472     if (F->hasSection()) {
 473       // Give section names unique ID's.
 474       unsigned &Entry = SectionMap[F->getSection()];
 475       if (!Entry) {
 476         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 477                           0/*TODO*/, Stream);
 478         Entry = SectionMap.size();
 479       }
 480     }
 481     if (F->hasGC()) {
 482       // Same for GC names.
 483       unsigned &Entry = GCMap[F->getGC()];
 484       if (!Entry) {
 485         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 486                           0/*TODO*/, Stream);
 487         Entry = GCMap.size();
 488       }
 489     }
 490   }
 491
 492   // Emit abbrev for globals, now that we know # sections and max alignment.
 493   unsigned SimpleGVarAbbrev = 0;
 494   if (!M->global_empty()) {
 495     // Add an abbrev for common globals with no visibility or thread localness.
 496     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 497     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 498     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 499                               Log2_32_Ceil(MaxGlobalType+1)));
 500     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 501     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 502     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 503     if (MaxAlignment == 0)                                      // Alignment.
 504       Abbv->Add(BitCodeAbbrevOp(0));
 505     else {
 506       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 507       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 508                                Log2_32_Ceil(MaxEncAlignment+1)));
 509     }
 510     if (SectionMap.empty())                                    // Section.
 511       Abbv->Add(BitCodeAbbrevOp(0));
 512     else
 513       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 514                                Log2_32_Ceil(SectionMap.size()+1)));
 515     // Don't bother emitting vis + thread local.
 516     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 517   }
 518
 519   // Emit the global variable information.
 520   SmallVector<unsigned, 64> Vals;
 521   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 522        GV != E; ++GV) {
 523     unsigned AbbrevToUse = 0;
 524
 525     // GLOBALVAR: [type, isconst, initid,
 526     //             linkage, alignment, section, visibility, threadlocal,
 527     //             unnamed_addr]
 528     Vals.push_back(VE.getTypeID(GV->getType()));
 529     Vals.push_back(GV->isConstant());
 530     Vals.push_back(GV->isDeclaration() ? 0 :
 531                    (VE.getValueID(GV->getInitializer()) + 1));
 532     Vals.push_back(getEncodedLinkage(GV));
 533     Vals.push_back(Log2_32(GV->getAlignment())+1);
 534     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 535     if (GV->isThreadLocal() ||
 536         GV->getVisibility() != GlobalValue::DefaultVisibility ||
 537         GV->hasUnnamedAddr() || GV->isExternallyInitialized()) {
 538       Vals.push_back(getEncodedVisibility(GV));
 539       Vals.push_back(getEncodedThreadLocalMode(GV));
 540       Vals.push_back(GV->hasUnnamedAddr());
 541       Vals.push_back(GV->isExternallyInitialized());
 542     } else {
 543       AbbrevToUse = SimpleGVarAbbrev;
 544     }
 545
 546     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 547     Vals.clear();
 548   }
 549
 550   // Emit the function proto information.
 551   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 552     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 553     //             section, visibility, gc, unnamed_addr]
 554     Vals.push_back(VE.getTypeID(F->getType()));
 555     Vals.push_back(F->getCallingConv());
 556     Vals.push_back(F->isDeclaration());
 557     Vals.push_back(getEncodedLinkage(F));
 558     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 559     Vals.push_back(Log2_32(F->getAlignment())+1);
 560     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 561     Vals.push_back(getEncodedVisibility(F));
 562     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 563     Vals.push_back(F->hasUnnamedAddr());
 564
 565     unsigned AbbrevToUse = 0;
 566     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 567     Vals.clear();
 568   }
 569
 570   // Emit the alias information.
 571   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 572        AI != E; ++AI) {
 573     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 574     Vals.push_back(VE.getTypeID(AI->getType()));
 575     Vals.push_back(VE.getValueID(AI->getAliasee()));
 576     Vals.push_back(getEncodedLinkage(AI));
 577     Vals.push_back(getEncodedVisibility(AI));
 578     unsigned AbbrevToUse = 0;
 579     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 580     Vals.clear();
 581   }
 582 }
 583
 584 static uint64_t GetOptimizationFlags(const Value *V) {
 585   uint64_t Flags = 0;
 586
 587   if (const OverflowingBinaryOperator *OBO =
 588         dyn_cast<OverflowingBinaryOperator>(V)) {
 589     if (OBO->hasNoSignedWrap())
 590       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 591     if (OBO->hasNoUnsignedWrap())
 592       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 593   } else if (const PossiblyExactOperator *PEO =
 594                dyn_cast<PossiblyExactOperator>(V)) {
 595     if (PEO->isExact())
 596       Flags |= 1 << bitc::PEO_EXACT;
 597   } else if (const FPMathOperator *FPMO =
 598              dyn_cast<const FPMathOperator>(V)) {
 599     if (FPMO->hasUnsafeAlgebra())
 600       Flags |= FastMathFlags::UnsafeAlgebra;
 601     if (FPMO->hasNoNaNs())
 602       Flags |= FastMathFlags::NoNaNs;
 603     if (FPMO->hasNoInfs())
 604       Flags |= FastMathFlags::NoInfs;
 605     if (FPMO->hasNoSignedZeros())
 606       Flags |= FastMathFlags::NoSignedZeros;
 607     if (FPMO->hasAllowReciprocal())
 608       Flags |= FastMathFlags::AllowReciprocal;
 609   }
 610
 611   return Flags;
 612 }
 613
 614 static void WriteMDNode(const MDNode *N,
 615                         const ValueEnumerator &VE,
 616                         BitstreamWriter &Stream,
 617                         SmallVectorImpl<uint64_t> &Record) {
 618   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 619     if (N->getOperand(i)) {
 620       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 621       Record.push_back(VE.getValueID(N->getOperand(i)));
 622     } else {
 623       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 624       Record.push_back(0);
 625     }
 626   }
 627   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 628                                            bitc::METADATA_NODE;
 629   Stream.EmitRecord(MDCode, Record, 0);
 630   Record.clear();
 631 }
 632
 633 static void WriteModuleMetadata(const Module *M,
 634                                 const ValueEnumerator &VE,
 635                                 BitstreamWriter &Stream) {
 636   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 637   bool StartedMetadataBlock = false;
 638   unsigned MDSAbbrev = 0;
 639   SmallVector<uint64_t, 64> Record;
 640   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 641
 642     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 643       if (!N->isFunctionLocal() || !N->getFunction()) {
 644         if (!StartedMetadataBlock) {
 645           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 646           StartedMetadataBlock = true;
 647         }
 648         WriteMDNode(N, VE, Stream, Record);
 649       }
 650     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 651       if (!StartedMetadataBlock)  {
 652         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 653
 654         // Abbrev for METADATA_STRING.
 655         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 656         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 657         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 658         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 659         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 660         StartedMetadataBlock = true;
 661       }
 662
 663       // Code: [strchar x N]
 664       Record.append(MDS->begin(), MDS->end());
 665
 666       // Emit the finished record.
 667       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 668       Record.clear();
 669     }
 670   }
 671
 672   // Write named metadata.
 673   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 674        E = M->named_metadata_end(); I != E; ++I) {
 675     const NamedMDNode *NMD = I;
 676     if (!StartedMetadataBlock)  {
 677       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 678       StartedMetadataBlock = true;
 679     }
 680
 681     // Write name.
 682     StringRef Str = NMD->getName();
 683     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 684       Record.push_back(Str[i]);
 685     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 686     Record.clear();
 687
 688     // Write named metadata operands.
 689     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 690       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 691     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 692     Record.clear();
 693   }
 694
 695   if (StartedMetadataBlock)
 696     Stream.ExitBlock();
 697 }
 698
 699 static void WriteFunctionLocalMetadata(const Function &F,
 700                                        const ValueEnumerator &VE,
 701                                        BitstreamWriter &Stream) {
 702   bool StartedMetadataBlock = false;
 703   SmallVector<uint64_t, 64> Record;
 704   const SmallVectorImpl<const MDNode *> &Vals = VE.getFunctionLocalMDValues();
 705   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 706     if (const MDNode *N = Vals[i])
 707       if (N->isFunctionLocal() && N->getFunction() == &F) {
 708         if (!StartedMetadataBlock) {
 709           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 710           StartedMetadataBlock = true;
 711         }
 712         WriteMDNode(N, VE, Stream, Record);
 713       }
 714
 715   if (StartedMetadataBlock)
 716     Stream.ExitBlock();
 717 }
 718
 719 static void WriteMetadataAttachment(const Function &F,
 720                                     const ValueEnumerator &VE,
 721                                     BitstreamWriter &Stream) {
 722   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 723
 724   SmallVector<uint64_t, 64> Record;
 725
 726   // Write metadata attachments
 727   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 728   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 729
 730   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 731     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 732          I != E; ++I) {
 733       MDs.clear();
 734       I->getAllMetadataOtherThanDebugLoc(MDs);
 735
 736       // If no metadata, ignore instruction.
 737       if (MDs.empty()) continue;
 738
 739       Record.push_back(VE.getInstructionID(I));
 740
 741       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 742         Record.push_back(MDs[i].first);
 743         Record.push_back(VE.getValueID(MDs[i].second));
 744       }
 745       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 746       Record.clear();
 747     }
 748
 749   Stream.ExitBlock();
 750 }
 751
 752 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 753   SmallVector<uint64_t, 64> Record;
 754
 755   // Write metadata kinds
 756   // METADATA_KIND - [n x [id, name]]
 757   SmallVector<StringRef, 8> Names;
 758   M->getMDKindNames(Names);
 759
 760   if (Names.empty()) return;
 761
 762   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 763
 764   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 765     Record.push_back(MDKindID);
 766     StringRef KName = Names[MDKindID];
 767     Record.append(KName.begin(), KName.end());
 768
 769     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 770     Record.clear();
 771   }
 772
 773   Stream.ExitBlock();
 774 }
 775
 776 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 777   if ((int64_t)V >= 0)
 778     Vals.push_back(V << 1);
 779   else
 780     Vals.push_back((-V << 1) | 1);
 781 }
 782
 783 static void EmitAPInt(SmallVectorImpl<uint64_t> &Vals,
 784                       unsigned &Code, unsigned &AbbrevToUse, const APInt &Val,
 785                       bool EmitSizeForWideNumbers = false
 786                       ) {
 787   if (Val.getBitWidth() <= 64) {
 788     uint64_t V = Val.getSExtValue();
 789     emitSignedInt64(Vals, V);
 790     Code = bitc::CST_CODE_INTEGER;
 791     AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 792   } else {
 793     // Wide integers, > 64 bits in size.
 794     // We have an arbitrary precision integer value to write whose
 795     // bit width is > 64. However, in canonical unsigned integer
 796     // format it is likely that the high bits are going to be zero.
 797     // So, we only write the number of active words.
 798     unsigned NWords = Val.getActiveWords();
 799
 800     if (EmitSizeForWideNumbers)
 801       Vals.push_back(NWords);
 802
 803     const uint64_t *RawWords = Val.getRawData();
 804     for (unsigned i = 0; i != NWords; ++i) {
 805       emitSignedInt64(Vals, RawWords[i]);
 806     }
 807     Code = bitc::CST_CODE_WIDE_INTEGER;
 808   }
 809 }
 810
 811 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 812                            const ValueEnumerator &VE,
 813                            BitstreamWriter &Stream, bool isGlobal) {
 814   if (FirstVal == LastVal) return;
 815
 816   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 817
 818   unsigned AggregateAbbrev = 0;
 819   unsigned String8Abbrev = 0;
 820   unsigned CString7Abbrev = 0;
 821   unsigned CString6Abbrev = 0;
 822   // If this is a constant pool for the module, emit module-specific abbrevs.
 823   if (isGlobal) {
 824     // Abbrev for CST_CODE_AGGREGATE.
 825     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 826     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 827     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 828     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 829     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 830
 831     // Abbrev for CST_CODE_STRING.
 832     Abbv = new BitCodeAbbrev();
 833     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 834     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 835     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 836     String8Abbrev = Stream.EmitAbbrev(Abbv);
 837     // Abbrev for CST_CODE_CSTRING.
 838     Abbv = new BitCodeAbbrev();
 839     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 840     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 841     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 842     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 843     // Abbrev for CST_CODE_CSTRING.
 844     Abbv = new BitCodeAbbrev();
 845     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 846     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 847     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 848     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 849   }
 850
 851   SmallVector<uint64_t, 64> Record;
 852
 853   const ValueEnumerator::ValueList &Vals = VE.getValues();
 854   Type *LastTy = 0;
 855   for (unsigned i = FirstVal; i != LastVal; ++i) {
 856     const Value *V = Vals[i].first;
 857     // If we need to switch types, do so now.
 858     if (V->getType() != LastTy) {
 859       LastTy = V->getType();
 860       Record.push_back(VE.getTypeID(LastTy));
 861       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 862                         CONSTANTS_SETTYPE_ABBREV);
 863       Record.clear();
 864     }
 865
 866     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 867       Record.push_back(unsigned(IA->hasSideEffects()) |
 868                        unsigned(IA->isAlignStack()) << 1 |
 869                        unsigned(IA->getDialect()&1) << 2);
 870
 871       // Add the asm string.
 872       const std::string &AsmStr = IA->getAsmString();
 873       Record.push_back(AsmStr.size());
 874       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 875         Record.push_back(AsmStr[i]);
 876
 877       // Add the constraint string.
 878       const std::string &ConstraintStr = IA->getConstraintString();
 879       Record.push_back(ConstraintStr.size());
 880       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 881         Record.push_back(ConstraintStr[i]);
 882       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 883       Record.clear();
 884       continue;
 885     }
 886     const Constant *C = cast<Constant>(V);
 887     unsigned Code = -1U;
 888     unsigned AbbrevToUse = 0;
 889     if (C->isNullValue()) {
 890       Code = bitc::CST_CODE_NULL;
 891     } else if (isa<UndefValue>(C)) {
 892       Code = bitc::CST_CODE_UNDEF;
 893     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 894       EmitAPInt(Record, Code, AbbrevToUse, IV->getValue());
 895     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 896       Code = bitc::CST_CODE_FLOAT;
 897       Type *Ty = CFP->getType();
 898       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 899         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 900       } else if (Ty->isX86_FP80Ty()) {
 901         // api needed to prevent premature destruction
 902         // bits are not in the same order as a normal i80 APInt, compensate.
 903         APInt api = CFP->getValueAPF().bitcastToAPInt();
 904         const uint64_t *p = api.getRawData();
 905         Record.push_back((p[1] << 48) | (p[0] >> 16));
 906         Record.push_back(p[0] & 0xffffLL);
 907       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 908         APInt api = CFP->getValueAPF().bitcastToAPInt();
 909         const uint64_t *p = api.getRawData();
 910         Record.push_back(p[0]);
 911         Record.push_back(p[1]);
 912       } else {
 913         assert (0 && "Unknown FP type!");
 914       }
 915     } else if (isa<ConstantDataSequential>(C) &&
 916                cast<ConstantDataSequential>(C)->isString()) {
 917       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 918       // Emit constant strings specially.
 919       unsigned NumElts = Str->getNumElements();
 920       // If this is a null-terminated string, use the denser CSTRING encoding.
 921       if (Str->isCString()) {
 922         Code = bitc::CST_CODE_CSTRING;
 923         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 924       } else {
 925         Code = bitc::CST_CODE_STRING;
 926         AbbrevToUse = String8Abbrev;
 927       }
 928       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 929       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 930       for (unsigned i = 0; i != NumElts; ++i) {
 931         unsigned char V = Str->getElementAsInteger(i);
 932         Record.push_back(V);
 933         isCStr7 &= (V & 128) == 0;
 934         if (isCStrChar6)
 935           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 936       }
 937
 938       if (isCStrChar6)
 939         AbbrevToUse = CString6Abbrev;
 940       else if (isCStr7)
 941         AbbrevToUse = CString7Abbrev;
 942     } else if (const ConstantDataSequential *CDS =
 943                   dyn_cast<ConstantDataSequential>(C)) {
 944       Code = bitc::CST_CODE_DATA;
 945       Type *EltTy = CDS->getType()->getElementType();
 946       if (isa<IntegerType>(EltTy)) {
 947         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
 948           Record.push_back(CDS->getElementAsInteger(i));
 949       } else if (EltTy->isFloatTy()) {
 950         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 951           union { float F; uint32_t I; };
 952           F = CDS->getElementAsFloat(i);
 953           Record.push_back(I);
 954         }
 955       } else {
 956         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
 957         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 958           union { double F; uint64_t I; };
 959           F = CDS->getElementAsDouble(i);
 960           Record.push_back(I);
 961         }
 962       }
 963     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
 964                isa<ConstantVector>(C)) {
 965       Code = bitc::CST_CODE_AGGREGATE;
 966       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 967         Record.push_back(VE.getValueID(C->getOperand(i)));
 968       AbbrevToUse = AggregateAbbrev;
 969     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 970       switch (CE->getOpcode()) {
 971       default:
 972         if (Instruction::isCast(CE->getOpcode())) {
 973           Code = bitc::CST_CODE_CE_CAST;
 974           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 975           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 976           Record.push_back(VE.getValueID(C->getOperand(0)));
 977           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 978         } else {
 979           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 980           Code = bitc::CST_CODE_CE_BINOP;
 981           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 982           Record.push_back(VE.getValueID(C->getOperand(0)));
 983           Record.push_back(VE.getValueID(C->getOperand(1)));
 984           uint64_t Flags = GetOptimizationFlags(CE);
 985           if (Flags != 0)
 986             Record.push_back(Flags);
 987         }
 988         break;
 989       case Instruction::GetElementPtr:
 990         Code = bitc::CST_CODE_CE_GEP;
 991         if (cast<GEPOperator>(C)->isInBounds())
 992           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
 993         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 994           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 995           Record.push_back(VE.getValueID(C->getOperand(i)));
 996         }
 997         break;
 998       case Instruction::Select:
 999         Code = bitc::CST_CODE_CE_SELECT;
1000         Record.push_back(VE.getValueID(C->getOperand(0)));
1001         Record.push_back(VE.getValueID(C->getOperand(1)));
1002         Record.push_back(VE.getValueID(C->getOperand(2)));
1003         break;
1004       case Instruction::ExtractElement:
1005         Code = bitc::CST_CODE_CE_EXTRACTELT;
1006         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1007         Record.push_back(VE.getValueID(C->getOperand(0)));
1008         Record.push_back(VE.getValueID(C->getOperand(1)));
1009         break;
1010       case Instruction::InsertElement:
1011         Code = bitc::CST_CODE_CE_INSERTELT;
1012         Record.push_back(VE.getValueID(C->getOperand(0)));
1013         Record.push_back(VE.getValueID(C->getOperand(1)));
1014         Record.push_back(VE.getValueID(C->getOperand(2)));
1015         break;
1016       case Instruction::ShuffleVector:
1017         // If the return type and argument types are the same, this is a
1018         // standard shufflevector instruction.  If the types are different,
1019         // then the shuffle is widening or truncating the input vectors, and
1020         // the argument type must also be encoded.
1021         if (C->getType() == C->getOperand(0)->getType()) {
1022           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1023         } else {
1024           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1025           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1026         }
1027         Record.push_back(VE.getValueID(C->getOperand(0)));
1028         Record.push_back(VE.getValueID(C->getOperand(1)));
1029         Record.push_back(VE.getValueID(C->getOperand(2)));
1030         break;
1031       case Instruction::ICmp:
1032       case Instruction::FCmp:
1033         Code = bitc::CST_CODE_CE_CMP;
1034         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1035         Record.push_back(VE.getValueID(C->getOperand(0)));
1036         Record.push_back(VE.getValueID(C->getOperand(1)));
1037         Record.push_back(CE->getPredicate());
1038         break;
1039       }
1040     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1041       Code = bitc::CST_CODE_BLOCKADDRESS;
1042       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1043       Record.push_back(VE.getValueID(BA->getFunction()));
1044       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1045     } else {
1046 #ifndef NDEBUG
1047       C->dump();
1048 #endif
1049       llvm_unreachable("Unknown constant!");
1050     }
1051     Stream.EmitRecord(Code, Record, AbbrevToUse);
1052     Record.clear();
1053   }
1054
1055   Stream.ExitBlock();
1056 }
1057
1058 static void WriteModuleConstants(const ValueEnumerator &VE,
1059                                  BitstreamWriter &Stream) {
1060   const ValueEnumerator::ValueList &Vals = VE.getValues();
1061
1062   // Find the first constant to emit, which is the first non-globalvalue value.
1063   // We know globalvalues have been emitted by WriteModuleInfo.
1064   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1065     if (!isa<GlobalValue>(Vals[i].first)) {
1066       WriteConstants(i, Vals.size(), VE, Stream, true);
1067       return;
1068     }
1069   }
1070 }
1071
1072 /// PushValueAndType - The file has to encode both the value and type id for
1073 /// many values, because we need to know what type to create for forward
1074 /// references.  However, most operands are not forward references, so this type
1075 /// field is not needed.
1076 ///
1077 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1078 /// instruction ID, then it is a forward reference, and it also includes the
1079 /// type ID.  The value ID that is written is encoded relative to the InstID.
1080 static bool PushValueAndType(const Value *V, unsigned InstID,
1081                              SmallVectorImpl<unsigned> &Vals,
1082                              ValueEnumerator &VE) {
1083   unsigned ValID = VE.getValueID(V);
1084   // Make encoding relative to the InstID.
1085   Vals.push_back(InstID - ValID);
1086   if (ValID >= InstID) {
1087     Vals.push_back(VE.getTypeID(V->getType()));
1088     return true;
1089   }
1090   return false;
1091 }
1092
1093 /// pushValue - Like PushValueAndType, but where the type of the value is
1094 /// omitted (perhaps it was already encoded in an earlier operand).
1095 static void pushValue(const Value *V, unsigned InstID,
1096                       SmallVectorImpl<unsigned> &Vals,
1097                       ValueEnumerator &VE) {
1098   unsigned ValID = VE.getValueID(V);
1099   Vals.push_back(InstID - ValID);
1100 }
1101
1102 static void pushValue64(const Value *V, unsigned InstID,
1103                         SmallVectorImpl<uint64_t> &Vals,
1104                         ValueEnumerator &VE) {
1105   uint64_t ValID = VE.getValueID(V);
1106   Vals.push_back(InstID - ValID);
1107 }
1108
1109 static void pushValueSigned(const Value *V, unsigned InstID,
1110                             SmallVectorImpl<uint64_t> &Vals,
1111                             ValueEnumerator &VE) {
1112   unsigned ValID = VE.getValueID(V);
1113   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1114   emitSignedInt64(Vals, diff);
1115 }
1116
1117 /// WriteInstruction - Emit an instruction to the specified stream.
1118 static void WriteInstruction(const Instruction &I, unsigned InstID,
1119                              ValueEnumerator &VE, BitstreamWriter &Stream,
1120                              SmallVectorImpl<unsigned> &Vals) {
1121   unsigned Code = 0;
1122   unsigned AbbrevToUse = 0;
1123   VE.setInstructionID(&I);
1124   switch (I.getOpcode()) {
1125   default:
1126     if (Instruction::isCast(I.getOpcode())) {
1127       Code = bitc::FUNC_CODE_INST_CAST;
1128       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1129         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1130       Vals.push_back(VE.getTypeID(I.getType()));
1131       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1132     } else {
1133       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1134       Code = bitc::FUNC_CODE_INST_BINOP;
1135       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1136         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1137       pushValue(I.getOperand(1), InstID, Vals, VE);
1138       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1139       uint64_t Flags = GetOptimizationFlags(&I);
1140       if (Flags != 0) {
1141         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1142           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1143         Vals.push_back(Flags);
1144       }
1145     }
1146     break;
1147
1148   case Instruction::GetElementPtr:
1149     Code = bitc::FUNC_CODE_INST_GEP;
1150     if (cast<GEPOperator>(&I)->isInBounds())
1151       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1152     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1153       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1154     break;
1155   case Instruction::ExtractValue: {
1156     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1157     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1158     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1159     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1160       Vals.push_back(*i);
1161     break;
1162   }
1163   case Instruction::InsertValue: {
1164     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1165     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1166     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1167     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1168     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1169       Vals.push_back(*i);
1170     break;
1171   }
1172   case Instruction::Select:
1173     Code = bitc::FUNC_CODE_INST_VSELECT;
1174     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1175     pushValue(I.getOperand(2), InstID, Vals, VE);
1176     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1177     break;
1178   case Instruction::ExtractElement:
1179     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1180     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1181     pushValue(I.getOperand(1), InstID, Vals, VE);
1182     break;
1183   case Instruction::InsertElement:
1184     Code = bitc::FUNC_CODE_INST_INSERTELT;
1185     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1186     pushValue(I.getOperand(1), InstID, Vals, VE);
1187     pushValue(I.getOperand(2), InstID, Vals, VE);
1188     break;
1189   case Instruction::ShuffleVector:
1190     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1191     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1192     pushValue(I.getOperand(1), InstID, Vals, VE);
1193     pushValue(I.getOperand(2), InstID, Vals, VE);
1194     break;
1195   case Instruction::ICmp:
1196   case Instruction::FCmp:
1197     // compare returning Int1Ty or vector of Int1Ty
1198     Code = bitc::FUNC_CODE_INST_CMP2;
1199     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1200     pushValue(I.getOperand(1), InstID, Vals, VE);
1201     Vals.push_back(cast<CmpInst>(I).getPredicate());
1202     break;
1203
1204   case Instruction::Ret:
1205     {
1206       Code = bitc::FUNC_CODE_INST_RET;
1207       unsigned NumOperands = I.getNumOperands();
1208       if (NumOperands == 0)
1209         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1210       else if (NumOperands == 1) {
1211         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1212           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1213       } else {
1214         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1215           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1216       }
1217     }
1218     break;
1219   case Instruction::Br:
1220     {
1221       Code = bitc::FUNC_CODE_INST_BR;
1222       const BranchInst &II = cast<BranchInst>(I);
1223       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1224       if (II.isConditional()) {
1225         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1226         pushValue(II.getCondition(), InstID, Vals, VE);
1227       }
1228     }
1229     break;
1230   case Instruction::Switch:
1231     {
1232       // Redefine Vals, since here we need to use 64 bit values
1233       // explicitly to store large APInt numbers.
1234       SmallVector<uint64_t, 128> Vals64;
1235
1236       Code = bitc::FUNC_CODE_INST_SWITCH;
1237       const SwitchInst &SI = cast<SwitchInst>(I);
1238
1239       uint32_t SwitchRecordHeader = SI.hash() | (SWITCH_INST_MAGIC << 16);
1240       Vals64.push_back(SwitchRecordHeader);
1241
1242       Vals64.push_back(VE.getTypeID(SI.getCondition()->getType()));
1243       pushValue64(SI.getCondition(), InstID, Vals64, VE);
1244       Vals64.push_back(VE.getValueID(SI.getDefaultDest()));
1245       Vals64.push_back(SI.getNumCases());
1246       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1247            i != e; ++i) {
1248         const IntegersSubset& CaseRanges = i.getCaseValueEx();
1249         unsigned Code, Abbrev; // will unused.
1250
1251         if (CaseRanges.isSingleNumber()) {
1252           Vals64.push_back(1/*NumItems = 1*/);
1253           Vals64.push_back(true/*IsSingleNumber = true*/);
1254           EmitAPInt(Vals64, Code, Abbrev, CaseRanges.getSingleNumber(0), true);
1255         } else {
1256
1257           Vals64.push_back(CaseRanges.getNumItems());
1258
1259           if (CaseRanges.isSingleNumbersOnly()) {
1260             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1261                  ri != rn; ++ri) {
1262
1263               Vals64.push_back(true/*IsSingleNumber = true*/);
1264
1265               EmitAPInt(Vals64, Code, Abbrev,
1266                         CaseRanges.getSingleNumber(ri), true);
1267             }
1268           } else
1269             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1270                  ri != rn; ++ri) {
1271               IntegersSubset::Range r = CaseRanges.getItem(ri);
1272               bool IsSingleNumber = CaseRanges.isSingleNumber(ri);
1273
1274               Vals64.push_back(IsSingleNumber);
1275
1276               EmitAPInt(Vals64, Code, Abbrev, r.getLow(), true);
1277               if (!IsSingleNumber)
1278                 EmitAPInt(Vals64, Code, Abbrev, r.getHigh(), true);
1279             }
1280         }
1281         Vals64.push_back(VE.getValueID(i.getCaseSuccessor()));
1282       }
1283
1284       Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1285
1286       // Also do expected action - clear external Vals collection:
1287       Vals.clear();
1288       return;
1289     }
1290     break;
1291   case Instruction::IndirectBr:
1292     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1293     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1294     // Encode the address operand as relative, but not the basic blocks.
1295     pushValue(I.getOperand(0), InstID, Vals, VE);
1296     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1297       Vals.push_back(VE.getValueID(I.getOperand(i)));
1298     break;
1299
1300   case Instruction::Invoke: {
1301     const InvokeInst *II = cast<InvokeInst>(&I);
1302     const Value *Callee(II->getCalledValue());
1303     PointerType *PTy = cast<PointerType>(Callee->getType());
1304     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1305     Code = bitc::FUNC_CODE_INST_INVOKE;
1306
1307     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1308     Vals.push_back(II->getCallingConv());
1309     Vals.push_back(VE.getValueID(II->getNormalDest()));
1310     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1311     PushValueAndType(Callee, InstID, Vals, VE);
1312
1313     // Emit value #'s for the fixed parameters.
1314     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1315       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1316
1317     // Emit type/value pairs for varargs params.
1318     if (FTy->isVarArg()) {
1319       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1320            i != e; ++i)
1321         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1322     }
1323     break;
1324   }
1325   case Instruction::Resume:
1326     Code = bitc::FUNC_CODE_INST_RESUME;
1327     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1328     break;
1329   case Instruction::Unreachable:
1330     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1331     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1332     break;
1333
1334   case Instruction::PHI: {
1335     const PHINode &PN = cast<PHINode>(I);
1336     Code = bitc::FUNC_CODE_INST_PHI;
1337     // With the newer instruction encoding, forward references could give
1338     // negative valued IDs.  This is most common for PHIs, so we use
1339     // signed VBRs.
1340     SmallVector<uint64_t, 128> Vals64;
1341     Vals64.push_back(VE.getTypeID(PN.getType()));
1342     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1343       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1344       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1345     }
1346     // Emit a Vals64 vector and exit.
1347     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1348     Vals64.clear();
1349     return;
1350   }
1351
1352   case Instruction::LandingPad: {
1353     const LandingPadInst &LP = cast<LandingPadInst>(I);
1354     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1355     Vals.push_back(VE.getTypeID(LP.getType()));
1356     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1357     Vals.push_back(LP.isCleanup());
1358     Vals.push_back(LP.getNumClauses());
1359     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1360       if (LP.isCatch(I))
1361         Vals.push_back(LandingPadInst::Catch);
1362       else
1363         Vals.push_back(LandingPadInst::Filter);
1364       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1365     }
1366     break;
1367   }
1368
1369   case Instruction::Alloca:
1370     Code = bitc::FUNC_CODE_INST_ALLOCA;
1371     Vals.push_back(VE.getTypeID(I.getType()));
1372     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1373     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1374     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1375     break;
1376
1377   case Instruction::Load:
1378     if (cast<LoadInst>(I).isAtomic()) {
1379       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1380       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1381     } else {
1382       Code = bitc::FUNC_CODE_INST_LOAD;
1383       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1384         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1385     }
1386     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1387     Vals.push_back(cast<LoadInst>(I).isVolatile());
1388     if (cast<LoadInst>(I).isAtomic()) {
1389       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1390       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1391     }
1392     break;
1393   case Instruction::Store:
1394     if (cast<StoreInst>(I).isAtomic())
1395       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1396     else
1397       Code = bitc::FUNC_CODE_INST_STORE;
1398     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1399     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1400     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1401     Vals.push_back(cast<StoreInst>(I).isVolatile());
1402     if (cast<StoreInst>(I).isAtomic()) {
1403       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1404       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1405     }
1406     break;
1407   case Instruction::AtomicCmpXchg:
1408     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1409     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1410     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1411     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1412     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1413     Vals.push_back(GetEncodedOrdering(
1414                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1415     Vals.push_back(GetEncodedSynchScope(
1416                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1417     break;
1418   case Instruction::AtomicRMW:
1419     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1420     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1421     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1422     Vals.push_back(GetEncodedRMWOperation(
1423                      cast<AtomicRMWInst>(I).getOperation()));
1424     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1425     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1426     Vals.push_back(GetEncodedSynchScope(
1427                      cast<AtomicRMWInst>(I).getSynchScope()));
1428     break;
1429   case Instruction::Fence:
1430     Code = bitc::FUNC_CODE_INST_FENCE;
1431     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1432     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1433     break;
1434   case Instruction::Call: {
1435     const CallInst &CI = cast<CallInst>(I);
1436     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1437     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1438
1439     Code = bitc::FUNC_CODE_INST_CALL;
1440
1441     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1442     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1443     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1444
1445     // Emit value #'s for the fixed parameters.
1446     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1447       // Check for labels (can happen with asm labels).
1448       if (FTy->getParamType(i)->isLabelTy())
1449         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1450       else
1451         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1452     }
1453
1454     // Emit type/value pairs for varargs params.
1455     if (FTy->isVarArg()) {
1456       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1457            i != e; ++i)
1458         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1459     }
1460     break;
1461   }
1462   case Instruction::VAArg:
1463     Code = bitc::FUNC_CODE_INST_VAARG;
1464     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1465     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1466     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1467     break;
1468   }
1469
1470   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1471   Vals.clear();
1472 }
1473
1474 // Emit names for globals/functions etc.
1475 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1476                                   const ValueEnumerator &VE,
1477                                   BitstreamWriter &Stream) {
1478   if (VST.empty()) return;
1479   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1480
1481   // FIXME: Set up the abbrev, we know how many values there are!
1482   // FIXME: We know if the type names can use 7-bit ascii.
1483   SmallVector<unsigned, 64> NameVals;
1484
1485   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1486        SI != SE; ++SI) {
1487
1488     const ValueName &Name = *SI;
1489
1490     // Figure out the encoding to use for the name.
1491     bool is7Bit = true;
1492     bool isChar6 = true;
1493     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1494          C != E; ++C) {
1495       if (isChar6)
1496         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1497       if ((unsigned char)*C & 128) {
1498         is7Bit = false;
1499         break;  // don't bother scanning the rest.
1500       }
1501     }
1502
1503     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1504
1505     // VST_ENTRY:   [valueid, namechar x N]
1506     // VST_BBENTRY: [bbid, namechar x N]
1507     unsigned Code;
1508     if (isa<BasicBlock>(SI->getValue())) {
1509       Code = bitc::VST_CODE_BBENTRY;
1510       if (isChar6)
1511         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1512     } else {
1513       Code = bitc::VST_CODE_ENTRY;
1514       if (isChar6)
1515         AbbrevToUse = VST_ENTRY_6_ABBREV;
1516       else if (is7Bit)
1517         AbbrevToUse = VST_ENTRY_7_ABBREV;
1518     }
1519
1520     NameVals.push_back(VE.getValueID(SI->getValue()));
1521     for (const char *P = Name.getKeyData(),
1522          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1523       NameVals.push_back((unsigned char)*P);
1524
1525     // Emit the finished record.
1526     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1527     NameVals.clear();
1528   }
1529   Stream.ExitBlock();
1530 }
1531
1532 /// WriteFunction - Emit a function body to the module stream.
1533 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1534                           BitstreamWriter &Stream) {
1535   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1536   VE.incorporateFunction(F);
1537
1538   SmallVector<unsigned, 64> Vals;
1539
1540   // Emit the number of basic blocks, so the reader can create them ahead of
1541   // time.
1542   Vals.push_back(VE.getBasicBlocks().size());
1543   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1544   Vals.clear();
1545
1546   // If there are function-local constants, emit them now.
1547   unsigned CstStart, CstEnd;
1548   VE.getFunctionConstantRange(CstStart, CstEnd);
1549   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1550
1551   // If there is function-local metadata, emit it now.
1552   WriteFunctionLocalMetadata(F, VE, Stream);
1553
1554   // Keep a running idea of what the instruction ID is.
1555   unsigned InstID = CstEnd;
1556
1557   bool NeedsMetadataAttachment = false;
1558
1559   DebugLoc LastDL;
1560
1561   // Finally, emit all the instructions, in order.
1562   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1563     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1564          I != E; ++I) {
1565       WriteInstruction(*I, InstID, VE, Stream, Vals);
1566
1567       if (!I->getType()->isVoidTy())
1568         ++InstID;
1569
1570       // If the instruction has metadata, write a metadata attachment later.
1571       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1572
1573       // If the instruction has a debug location, emit it.
1574       DebugLoc DL = I->getDebugLoc();
1575       if (DL.isUnknown()) {
1576         // nothing todo.
1577       } else if (DL == LastDL) {
1578         // Just repeat the same debug loc as last time.
1579         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1580       } else {
1581         MDNode *Scope, *IA;
1582         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1583
1584         Vals.push_back(DL.getLine());
1585         Vals.push_back(DL.getCol());
1586         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1587         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1588         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1589         Vals.clear();
1590
1591         LastDL = DL;
1592       }
1593     }
1594
1595   // Emit names for all the instructions etc.
1596   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1597
1598   if (NeedsMetadataAttachment)
1599     WriteMetadataAttachment(F, VE, Stream);
1600   VE.purgeFunction();
1601   Stream.ExitBlock();
1602 }
1603
1604 // Emit blockinfo, which defines the standard abbreviations etc.
1605 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1606   // We only want to emit block info records for blocks that have multiple
1607   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1608   // Other blocks can define their abbrevs inline.
1609   Stream.EnterBlockInfoBlock(2);
1610
1611   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1612     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1613     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1614     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1615     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1616     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1617     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1618                                    Abbv) != VST_ENTRY_8_ABBREV)
1619       llvm_unreachable("Unexpected abbrev ordering!");
1620   }
1621
1622   { // 7-bit fixed width VST_ENTRY strings.
1623     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1624     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1625     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1626     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1627     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1628     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1629                                    Abbv) != VST_ENTRY_7_ABBREV)
1630       llvm_unreachable("Unexpected abbrev ordering!");
1631   }
1632   { // 6-bit char6 VST_ENTRY strings.
1633     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1634     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1635     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1636     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1637     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1638     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1639                                    Abbv) != VST_ENTRY_6_ABBREV)
1640       llvm_unreachable("Unexpected abbrev ordering!");
1641   }
1642   { // 6-bit char6 VST_BBENTRY strings.
1643     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1644     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1645     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1646     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1647     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1648     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1649                                    Abbv) != VST_BBENTRY_6_ABBREV)
1650       llvm_unreachable("Unexpected abbrev ordering!");
1651   }
1652
1653
1654
1655   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1656     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1657     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1658     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1659                               Log2_32_Ceil(VE.getTypes().size()+1)));
1660     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1661                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1662       llvm_unreachable("Unexpected abbrev ordering!");
1663   }
1664
1665   { // INTEGER abbrev for CONSTANTS_BLOCK.
1666     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1667     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1668     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1669     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1670                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1671       llvm_unreachable("Unexpected abbrev ordering!");
1672   }
1673
1674   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1675     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1676     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1677     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1678     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1679                               Log2_32_Ceil(VE.getTypes().size()+1)));
1680     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1681
1682     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1683                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1684       llvm_unreachable("Unexpected abbrev ordering!");
1685   }
1686   { // NULL abbrev for CONSTANTS_BLOCK.
1687     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1688     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1689     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1690                                    Abbv) != CONSTANTS_NULL_Abbrev)
1691       llvm_unreachable("Unexpected abbrev ordering!");
1692   }
1693
1694   // FIXME: This should only use space for first class types!
1695
1696   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1697     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1698     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1699     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1700     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1701     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1702     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1703                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1704       llvm_unreachable("Unexpected abbrev ordering!");
1705   }
1706   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1707     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1708     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1709     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1710     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1711     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1712     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1713                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1714       llvm_unreachable("Unexpected abbrev ordering!");
1715   }
1716   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1717     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1718     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1719     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1720     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1721     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1722     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1723     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1724                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1725       llvm_unreachable("Unexpected abbrev ordering!");
1726   }
1727   { // INST_CAST abbrev for FUNCTION_BLOCK.
1728     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1729     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1730     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1731     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1732                               Log2_32_Ceil(VE.getTypes().size()+1)));
1733     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1734     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1735                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1736       llvm_unreachable("Unexpected abbrev ordering!");
1737   }
1738
1739   { // INST_RET abbrev for FUNCTION_BLOCK.
1740     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1741     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1742     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1743                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1744       llvm_unreachable("Unexpected abbrev ordering!");
1745   }
1746   { // INST_RET abbrev for FUNCTION_BLOCK.
1747     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1748     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1749     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1750     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1751                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1752       llvm_unreachable("Unexpected abbrev ordering!");
1753   }
1754   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1755     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1756     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1757     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1758                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1759       llvm_unreachable("Unexpected abbrev ordering!");
1760   }
1761
1762   Stream.ExitBlock();
1763 }
1764
1765 // Sort the Users based on the order in which the reader parses the bitcode
1766 // file.
1767 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1768   // TODO: Implement.
1769   return true;
1770 }
1771
1772 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1773                          BitstreamWriter &Stream) {
1774
1775   // One or zero uses can't get out of order.
1776   if (V->use_empty() || V->hasNUses(1))
1777     return;
1778
1779   // Make a copy of the in-memory use-list for sorting.
1780   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1781   SmallVector<const User*, 8> UseList;
1782   UseList.reserve(UseListSize);
1783   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1784        I != E; ++I) {
1785     const User *U = *I;
1786     UseList.push_back(U);
1787   }
1788
1789   // Sort the copy based on the order read by the BitcodeReader.
1790   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1791
1792   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1793   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1794
1795   // TODO: Emit the USELIST_CODE_ENTRYs.
1796 }
1797
1798 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1799                                  BitstreamWriter &Stream) {
1800   VE.incorporateFunction(*F);
1801
1802   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1803        AI != AE; ++AI)
1804     WriteUseList(AI, VE, Stream);
1805   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1806        ++BB) {
1807     WriteUseList(BB, VE, Stream);
1808     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1809          ++II) {
1810       WriteUseList(II, VE, Stream);
1811       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1812            OI != E; ++OI) {
1813         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1814             isa<InlineAsm>(*OI))
1815           WriteUseList(*OI, VE, Stream);
1816       }
1817     }
1818   }
1819   VE.purgeFunction();
1820 }
1821
1822 // Emit use-lists.
1823 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1824                                 BitstreamWriter &Stream) {
1825   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1826
1827   // XXX: this modifies the module, but in a way that should never change the
1828   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1829   // contain entries in the use_list that do not exist in the Module and are
1830   // not stored in the .bc file.
1831   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1832        I != E; ++I)
1833     I->removeDeadConstantUsers();
1834
1835   // Write the global variables.
1836   for (Module::const_global_iterator GI = M->global_begin(),
1837          GE = M->global_end(); GI != GE; ++GI) {
1838     WriteUseList(GI, VE, Stream);
1839
1840     // Write the global variable initializers.
1841     if (GI->hasInitializer())
1842       WriteUseList(GI->getInitializer(), VE, Stream);
1843   }
1844
1845   // Write the functions.
1846   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1847     WriteUseList(FI, VE, Stream);
1848     if (!FI->isDeclaration())
1849       WriteFunctionUseList(FI, VE, Stream);
1850   }
1851
1852   // Write the aliases.
1853   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1854        AI != AE; ++AI) {
1855     WriteUseList(AI, VE, Stream);
1856     WriteUseList(AI->getAliasee(), VE, Stream);
1857   }
1858
1859   Stream.ExitBlock();
1860 }
1861
1862 /// WriteModule - Emit the specified module to the bitstream.
1863 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1864   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1865
1866   SmallVector<unsigned, 1> Vals;
1867   unsigned CurVersion = 1;
1868   Vals.push_back(CurVersion);
1869   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1870
1871   // Analyze the module, enumerating globals, functions, etc.
1872   ValueEnumerator VE(M);
1873
1874   // Emit blockinfo, which defines the standard abbreviations etc.
1875   WriteBlockInfo(VE, Stream);
1876
1877   // Emit information about attribute groups.
1878   WriteAttributeGroupTable(VE, Stream);
1879
1880   // Emit information about parameter attributes.
1881   WriteAttributeTable(VE, Stream);
1882
1883   // Emit information describing all of the types in the module.
1884   WriteTypeTable(VE, Stream);
1885
1886   // Emit top-level description of module, including target triple, inline asm,
1887   // descriptors for global variables, and function prototype info.
1888   WriteModuleInfo(M, VE, Stream);
1889
1890   // Emit constants.
1891   WriteModuleConstants(VE, Stream);
1892
1893   // Emit metadata.
1894   WriteModuleMetadata(M, VE, Stream);
1895
1896   // Emit metadata.
1897   WriteModuleMetadataStore(M, Stream);
1898
1899   // Emit names for globals/functions etc.
1900   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1901
1902   // Emit use-lists.
1903   if (EnablePreserveUseListOrdering)
1904     WriteModuleUseLists(M, VE, Stream);
1905
1906   // Emit function bodies.
1907   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1908     if (!F->isDeclaration())
1909       WriteFunction(*F, VE, Stream);
1910
1911   Stream.ExitBlock();
1912 }
1913
1914 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1915 /// header and trailer to make it compatible with the system archiver.  To do
1916 /// this we emit the following header, and then emit a trailer that pads the
1917 /// file out to be a multiple of 16 bytes.
1918 ///
1919 /// struct bc_header {
1920 ///   uint32_t Magic;         // 0x0B17C0DE
1921 ///   uint32_t Version;       // Version, currently always 0.
1922 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1923 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1924 ///   uint32_t CPUType;       // CPU specifier.
1925 ///   ... potentially more later ...
1926 /// };
1927 enum {
1928   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1929   DarwinBCHeaderSize = 5*4
1930 };
1931
1932 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1933                                uint32_t &Position) {
1934   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1935   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1936   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1937   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1938   Position += 4;
1939 }
1940
1941 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1942                                          const Triple &TT) {
1943   unsigned CPUType = ~0U;
1944
1945   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1946   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1947   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1948   // specific constants here because they are implicitly part of the Darwin ABI.
1949   enum {
1950     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1951     DARWIN_CPU_TYPE_X86        = 7,
1952     DARWIN_CPU_TYPE_ARM        = 12,
1953     DARWIN_CPU_TYPE_POWERPC    = 18
1954   };
1955
1956   Triple::ArchType Arch = TT.getArch();
1957   if (Arch == Triple::x86_64)
1958     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1959   else if (Arch == Triple::x86)
1960     CPUType = DARWIN_CPU_TYPE_X86;
1961   else if (Arch == Triple::ppc)
1962     CPUType = DARWIN_CPU_TYPE_POWERPC;
1963   else if (Arch == Triple::ppc64)
1964     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1965   else if (Arch == Triple::arm || Arch == Triple::thumb)
1966     CPUType = DARWIN_CPU_TYPE_ARM;
1967
1968   // Traditional Bitcode starts after header.
1969   assert(Buffer.size() >= DarwinBCHeaderSize &&
1970          "Expected header size to be reserved");
1971   unsigned BCOffset = DarwinBCHeaderSize;
1972   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1973
1974   // Write the magic and version.
1975   unsigned Position = 0;
1976   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1977   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1978   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1979   WriteInt32ToBuffer(BCSize     , Buffer, Position);
1980   WriteInt32ToBuffer(CPUType    , Buffer, Position);
1981
1982   // If the file is not a multiple of 16 bytes, insert dummy padding.
1983   while (Buffer.size() & 15)
1984     Buffer.push_back(0);
1985 }
1986
1987 /// WriteBitcodeToFile - Write the specified module to the specified output
1988 /// stream.
1989 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1990   SmallVector<char, 0> Buffer;
1991   Buffer.reserve(256*1024);
1992
1993   // If this is darwin or another generic macho target, reserve space for the
1994   // header.
1995   Triple TT(M->getTargetTriple());
1996   if (TT.isOSDarwin())
1997     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
1998
1999   // Emit the module into the buffer.
2000   {
2001     BitstreamWriter Stream(Buffer);
2002
2003     // Emit the file header.
2004     Stream.Emit((unsigned)'B', 8);
2005     Stream.Emit((unsigned)'C', 8);
2006     Stream.Emit(0x0, 4);
2007     Stream.Emit(0xC, 4);
2008     Stream.Emit(0xE, 4);
2009     Stream.Emit(0xD, 4);
2010
2011     // Emit the module.
2012     WriteModule(M, Stream);
2013   }
2014
2015   if (TT.isOSDarwin())
2016     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2017
2018   // Write the generated bitstream to "Out".
2019   Out.write((char*)&Buffer.front(), Buffer.size());
2020 }