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 "llvm/Bitcode/BitstreamWriter.h"
  16 #include "llvm/Bitcode/LLVMBitCodes.h"
  17 #include "ValueEnumerator.h"
  18 #include "llvm/Constants.h"
  19 #include "llvm/DerivedTypes.h"
  20 #include "llvm/InlineAsm.h"
  21 #include "llvm/Instructions.h"
  22 #include "llvm/MDNode.h"
  23 #include "llvm/Module.h"
  24 #include "llvm/Operator.h"
  25 #include "llvm/TypeSymbolTable.h"
  26 #include "llvm/ValueSymbolTable.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Support/MathExtras.h"
  29 #include "llvm/Support/Streams.h"
  30 #include "llvm/Support/raw_ostream.h"
  31 #include "llvm/System/Program.h"
  32 using namespace llvm;
  33
  34 /// These are manifest constants used by the bitcode writer. They do not need to
  35 /// be kept in sync with the reader, but need to be consistent within this file.
  36 enum {
  37   CurVersion = 0,
  38
  39   // VALUE_SYMTAB_BLOCK abbrev id's.
  40   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  41   VST_ENTRY_7_ABBREV,
  42   VST_ENTRY_6_ABBREV,
  43   VST_BBENTRY_6_ABBREV,
  44
  45   // CONSTANTS_BLOCK abbrev id's.
  46   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  47   CONSTANTS_INTEGER_ABBREV,
  48   CONSTANTS_CE_CAST_Abbrev,
  49   CONSTANTS_NULL_Abbrev,
  50
  51   // FUNCTION_BLOCK abbrev id's.
  52   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  53   FUNCTION_INST_BINOP_ABBREV,
  54   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  55   FUNCTION_INST_CAST_ABBREV,
  56   FUNCTION_INST_RET_VOID_ABBREV,
  57   FUNCTION_INST_RET_VAL_ABBREV,
  58   FUNCTION_INST_UNREACHABLE_ABBREV
  59 };
  60
  61
  62 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  63   switch (Opcode) {
  64   default: llvm_unreachable("Unknown cast instruction!");
  65   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  66   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  67   case Instruction::SExt    : return bitc::CAST_SEXT;
  68   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  69   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  70   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  71   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  72   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  73   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  74   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  75   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  76   case Instruction::BitCast : return bitc::CAST_BITCAST;
  77   }
  78 }
  79
  80 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  81   switch (Opcode) {
  82   default: llvm_unreachable("Unknown binary instruction!");
  83   case Instruction::Add:
  84   case Instruction::FAdd: return bitc::BINOP_ADD;
  85   case Instruction::Sub:
  86   case Instruction::FSub: return bitc::BINOP_SUB;
  87   case Instruction::Mul:
  88   case Instruction::FMul: return bitc::BINOP_MUL;
  89   case Instruction::UDiv: return bitc::BINOP_UDIV;
  90   case Instruction::FDiv:
  91   case Instruction::SDiv: return bitc::BINOP_SDIV;
  92   case Instruction::URem: return bitc::BINOP_UREM;
  93   case Instruction::FRem:
  94   case Instruction::SRem: return bitc::BINOP_SREM;
  95   case Instruction::Shl:  return bitc::BINOP_SHL;
  96   case Instruction::LShr: return bitc::BINOP_LSHR;
  97   case Instruction::AShr: return bitc::BINOP_ASHR;
  98   case Instruction::And:  return bitc::BINOP_AND;
  99   case Instruction::Or:   return bitc::BINOP_OR;
 100   case Instruction::Xor:  return bitc::BINOP_XOR;
 101   }
 102 }
 103
 104
 105
 106 static void WriteStringRecord(unsigned Code, const std::string &Str,
 107                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 108   SmallVector<unsigned, 64> Vals;
 109
 110   // Code: [strchar x N]
 111   for (unsigned i = 0, e = Str.size(); i != e; ++i)
 112     Vals.push_back(Str[i]);
 113
 114   // Emit the finished record.
 115   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 116 }
 117
 118 // Emit information about parameter attributes.
 119 static void WriteAttributeTable(const ValueEnumerator &VE,
 120                                 BitstreamWriter &Stream) {
 121   const std::vector<AttrListPtr> &Attrs = VE.getAttributes();
 122   if (Attrs.empty()) return;
 123
 124   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 125
 126   SmallVector<uint64_t, 64> Record;
 127   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 128     const AttrListPtr &A = Attrs[i];
 129     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
 130       const AttributeWithIndex &PAWI = A.getSlot(i);
 131       Record.push_back(PAWI.Index);
 132
 133       // FIXME: remove in LLVM 3.0
 134       // Store the alignment in the bitcode as a 16-bit raw value instead of a
 135       // 5-bit log2 encoded value. Shift the bits above the alignment up by
 136       // 11 bits.
 137       uint64_t FauxAttr = PAWI.Attrs & 0xffff;
 138       if (PAWI.Attrs & Attribute::Alignment)
 139         FauxAttr |= (1ull<<16)<<(((PAWI.Attrs & Attribute::Alignment)-1) >> 16);
 140       FauxAttr |= (PAWI.Attrs & (0x3FFull << 21)) << 11;
 141
 142       Record.push_back(FauxAttr);
 143     }
 144
 145     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 146     Record.clear();
 147   }
 148
 149   Stream.ExitBlock();
 150 }
 151
 152 /// WriteTypeTable - Write out the type table for a module.
 153 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 154   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 155
 156   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
 157   SmallVector<uint64_t, 64> TypeVals;
 158
 159   // Abbrev for TYPE_CODE_POINTER.
 160   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 161   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 162   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 163                             Log2_32_Ceil(VE.getTypes().size()+1)));
 164   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 165   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 166
 167   // Abbrev for TYPE_CODE_FUNCTION.
 168   Abbv = new BitCodeAbbrev();
 169   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 170   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 171   Abbv->Add(BitCodeAbbrevOp(0));  // FIXME: DEAD value, remove in LLVM 3.0
 172   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 173   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 174                             Log2_32_Ceil(VE.getTypes().size()+1)));
 175   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 176
 177   // Abbrev for TYPE_CODE_STRUCT.
 178   Abbv = new BitCodeAbbrev();
 179   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
 180   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 181   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 182   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 183                             Log2_32_Ceil(VE.getTypes().size()+1)));
 184   unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
 185
 186   // Abbrev for TYPE_CODE_ARRAY.
 187   Abbv = new BitCodeAbbrev();
 188   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 189   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 190   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 191                             Log2_32_Ceil(VE.getTypes().size()+1)));
 192   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 193
 194   // Emit an entry count so the reader can reserve space.
 195   TypeVals.push_back(TypeList.size());
 196   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 197   TypeVals.clear();
 198
 199   // Loop over all of the types, emitting each in turn.
 200   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 201     const Type *T = TypeList[i].first;
 202     int AbbrevToUse = 0;
 203     unsigned Code = 0;
 204
 205     switch (T->getTypeID()) {
 206     default: llvm_unreachable("Unknown type!");
 207     case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
 208     case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
 209     case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
 210     case Type::X86_FP80TyID: Code = bitc::TYPE_CODE_X86_FP80; break;
 211     case Type::FP128TyID: Code = bitc::TYPE_CODE_FP128; break;
 212     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 213     case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
 214     case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
 215     case Type::MetadataTyID: Code = bitc::TYPE_CODE_METADATA; break;
 216     case Type::IntegerTyID:
 217       // INTEGER: [width]
 218       Code = bitc::TYPE_CODE_INTEGER;
 219       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 220       break;
 221     case Type::PointerTyID: {
 222       const PointerType *PTy = cast<PointerType>(T);
 223       // POINTER: [pointee type, address space]
 224       Code = bitc::TYPE_CODE_POINTER;
 225       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 226       unsigned AddressSpace = PTy->getAddressSpace();
 227       TypeVals.push_back(AddressSpace);
 228       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 229       break;
 230     }
 231     case Type::FunctionTyID: {
 232       const FunctionType *FT = cast<FunctionType>(T);
 233       // FUNCTION: [isvararg, attrid, retty, paramty x N]
 234       Code = bitc::TYPE_CODE_FUNCTION;
 235       TypeVals.push_back(FT->isVarArg());
 236       TypeVals.push_back(0);  // FIXME: DEAD: remove in llvm 3.0
 237       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 238       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 239         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 240       AbbrevToUse = FunctionAbbrev;
 241       break;
 242     }
 243     case Type::StructTyID: {
 244       const StructType *ST = cast<StructType>(T);
 245       // STRUCT: [ispacked, eltty x N]
 246       Code = bitc::TYPE_CODE_STRUCT;
 247       TypeVals.push_back(ST->isPacked());
 248       // Output all of the element types.
 249       for (StructType::element_iterator I = ST->element_begin(),
 250            E = ST->element_end(); I != E; ++I)
 251         TypeVals.push_back(VE.getTypeID(*I));
 252       AbbrevToUse = StructAbbrev;
 253       break;
 254     }
 255     case Type::ArrayTyID: {
 256       const ArrayType *AT = cast<ArrayType>(T);
 257       // ARRAY: [numelts, eltty]
 258       Code = bitc::TYPE_CODE_ARRAY;
 259       TypeVals.push_back(AT->getNumElements());
 260       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 261       AbbrevToUse = ArrayAbbrev;
 262       break;
 263     }
 264     case Type::VectorTyID: {
 265       const VectorType *VT = cast<VectorType>(T);
 266       // VECTOR [numelts, eltty]
 267       Code = bitc::TYPE_CODE_VECTOR;
 268       TypeVals.push_back(VT->getNumElements());
 269       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 270       break;
 271     }
 272     }
 273
 274     // Emit the finished record.
 275     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 276     TypeVals.clear();
 277   }
 278
 279   Stream.ExitBlock();
 280 }
 281
 282 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 283   switch (GV->getLinkage()) {
 284   default: llvm_unreachable("Invalid linkage!");
 285   case GlobalValue::GhostLinkage:  // Map ghost linkage onto external.
 286   case GlobalValue::ExternalLinkage:            return 0;
 287   case GlobalValue::WeakAnyLinkage:             return 1;
 288   case GlobalValue::AppendingLinkage:           return 2;
 289   case GlobalValue::InternalLinkage:            return 3;
 290   case GlobalValue::LinkOnceAnyLinkage:         return 4;
 291   case GlobalValue::DLLImportLinkage:           return 5;
 292   case GlobalValue::DLLExportLinkage:           return 6;
 293   case GlobalValue::ExternalWeakLinkage:        return 7;
 294   case GlobalValue::CommonLinkage:              return 8;
 295   case GlobalValue::PrivateLinkage:             return 9;
 296   case GlobalValue::WeakODRLinkage:             return 10;
 297   case GlobalValue::LinkOnceODRLinkage:         return 11;
 298   case GlobalValue::AvailableExternallyLinkage: return 12;
 299   case GlobalValue::LinkerPrivateLinkage:       return 13;
 300   }
 301 }
 302
 303 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 304   switch (GV->getVisibility()) {
 305   default: llvm_unreachable("Invalid visibility!");
 306   case GlobalValue::DefaultVisibility:   return 0;
 307   case GlobalValue::HiddenVisibility:    return 1;
 308   case GlobalValue::ProtectedVisibility: return 2;
 309   }
 310 }
 311
 312 // Emit top-level description of module, including target triple, inline asm,
 313 // descriptors for global variables, and function prototype info.
 314 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 315                             BitstreamWriter &Stream) {
 316   // Emit the list of dependent libraries for the Module.
 317   for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
 318     WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
 319
 320   // Emit various pieces of data attached to a module.
 321   if (!M->getTargetTriple().empty())
 322     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 323                       0/*TODO*/, Stream);
 324   if (!M->getDataLayout().empty())
 325     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 326                       0/*TODO*/, Stream);
 327   if (!M->getModuleInlineAsm().empty())
 328     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 329                       0/*TODO*/, Stream);
 330
 331   // Emit information about sections and GC, computing how many there are. Also
 332   // compute the maximum alignment value.
 333   std::map<std::string, unsigned> SectionMap;
 334   std::map<std::string, unsigned> GCMap;
 335   unsigned MaxAlignment = 0;
 336   unsigned MaxGlobalType = 0;
 337   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 338        GV != E; ++GV) {
 339     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 340     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 341
 342     if (!GV->hasSection()) continue;
 343     // Give section names unique ID's.
 344     unsigned &Entry = SectionMap[GV->getSection()];
 345     if (Entry != 0) continue;
 346     WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 347                       0/*TODO*/, Stream);
 348     Entry = SectionMap.size();
 349   }
 350   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 351     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 352     if (F->hasSection()) {
 353       // Give section names unique ID's.
 354       unsigned &Entry = SectionMap[F->getSection()];
 355       if (!Entry) {
 356         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 357                           0/*TODO*/, Stream);
 358         Entry = SectionMap.size();
 359       }
 360     }
 361     if (F->hasGC()) {
 362       // Same for GC names.
 363       unsigned &Entry = GCMap[F->getGC()];
 364       if (!Entry) {
 365         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 366                           0/*TODO*/, Stream);
 367         Entry = GCMap.size();
 368       }
 369     }
 370   }
 371
 372   // Emit abbrev for globals, now that we know # sections and max alignment.
 373   unsigned SimpleGVarAbbrev = 0;
 374   if (!M->global_empty()) {
 375     // Add an abbrev for common globals with no visibility or thread localness.
 376     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 377     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 378     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 379                               Log2_32_Ceil(MaxGlobalType+1)));
 380     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 381     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 382     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 383     if (MaxAlignment == 0)                                      // Alignment.
 384       Abbv->Add(BitCodeAbbrevOp(0));
 385     else {
 386       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 387       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 388                                Log2_32_Ceil(MaxEncAlignment+1)));
 389     }
 390     if (SectionMap.empty())                                    // Section.
 391       Abbv->Add(BitCodeAbbrevOp(0));
 392     else
 393       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 394                                Log2_32_Ceil(SectionMap.size()+1)));
 395     // Don't bother emitting vis + thread local.
 396     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 397   }
 398
 399   // Emit the global variable information.
 400   SmallVector<unsigned, 64> Vals;
 401   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 402        GV != E; ++GV) {
 403     unsigned AbbrevToUse = 0;
 404
 405     // GLOBALVAR: [type, isconst, initid,
 406     //             linkage, alignment, section, visibility, threadlocal]
 407     Vals.push_back(VE.getTypeID(GV->getType()));
 408     Vals.push_back(GV->isConstant());
 409     Vals.push_back(GV->isDeclaration() ? 0 :
 410                    (VE.getValueID(GV->getInitializer()) + 1));
 411     Vals.push_back(getEncodedLinkage(GV));
 412     Vals.push_back(Log2_32(GV->getAlignment())+1);
 413     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 414     if (GV->isThreadLocal() ||
 415         GV->getVisibility() != GlobalValue::DefaultVisibility) {
 416       Vals.push_back(getEncodedVisibility(GV));
 417       Vals.push_back(GV->isThreadLocal());
 418     } else {
 419       AbbrevToUse = SimpleGVarAbbrev;
 420     }
 421
 422     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 423     Vals.clear();
 424   }
 425
 426   // Emit the function proto information.
 427   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 428     // FUNCTION:  [type, callingconv, isproto, paramattr,
 429     //             linkage, alignment, section, visibility, gc]
 430     Vals.push_back(VE.getTypeID(F->getType()));
 431     Vals.push_back(F->getCallingConv());
 432     Vals.push_back(F->isDeclaration());
 433     Vals.push_back(getEncodedLinkage(F));
 434     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 435     Vals.push_back(Log2_32(F->getAlignment())+1);
 436     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 437     Vals.push_back(getEncodedVisibility(F));
 438     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 439
 440     unsigned AbbrevToUse = 0;
 441     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 442     Vals.clear();
 443   }
 444
 445
 446   // Emit the alias information.
 447   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 448        AI != E; ++AI) {
 449     Vals.push_back(VE.getTypeID(AI->getType()));
 450     Vals.push_back(VE.getValueID(AI->getAliasee()));
 451     Vals.push_back(getEncodedLinkage(AI));
 452     Vals.push_back(getEncodedVisibility(AI));
 453     unsigned AbbrevToUse = 0;
 454     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 455     Vals.clear();
 456   }
 457 }
 458
 459 static uint64_t GetOptimizationFlags(const Value *V) {
 460   uint64_t Flags = 0;
 461
 462   if (const OverflowingBinaryOperator *OBO =
 463         dyn_cast<OverflowingBinaryOperator>(V)) {
 464     if (OBO->hasNoSignedOverflow())
 465       Flags |= 1 << bitc::OBO_NO_SIGNED_OVERFLOW;
 466     if (OBO->hasNoUnsignedOverflow())
 467       Flags |= 1 << bitc::OBO_NO_UNSIGNED_OVERFLOW;
 468   } else if (const SDivOperator *Div = dyn_cast<SDivOperator>(V)) {
 469     if (Div->isExact())
 470       Flags |= 1 << bitc::SDIV_EXACT;
 471   }
 472
 473   return Flags;
 474 }
 475
 476  static void WriteModuleMetadata(const ValueEnumerator &VE,
 477                                  BitstreamWriter &Stream) {
 478    const ValueEnumerator::ValueList &Vals = VE.getValues();
 479    bool StartedMetadataBlock = false;
 480    unsigned MDSAbbrev = 0;
 481    for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 482      if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 483        if (!StartedMetadataBlock)  {
 484         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 485
 486         // Abbrev for METADATA_STRING.
 487         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 488         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 489         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 490         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 491         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 492         StartedMetadataBlock = true;
 493        }
 494
 495       SmallVector<unsigned, 64> StrVals;
 496       StrVals.clear();
 497        // Code: [strchar x N]
 498        const char *StrBegin = MDS->begin();
 499        for (unsigned i = 0, e = MDS->size(); i != e; ++i)
 500         StrVals.push_back(StrBegin[i]);
 501
 502        // Emit the finished record.
 503       Stream.EmitRecord(bitc::METADATA_STRING, StrVals, MDSAbbrev);
 504      }
 505    }
 506
 507    if (StartedMetadataBlock)
 508      Stream.ExitBlock();
 509 }
 510
 511
 512 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 513                            const ValueEnumerator &VE,
 514                            BitstreamWriter &Stream, bool isGlobal) {
 515   if (FirstVal == LastVal) return;
 516
 517   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 518
 519   unsigned AggregateAbbrev = 0;
 520   unsigned String8Abbrev = 0;
 521   unsigned CString7Abbrev = 0;
 522   unsigned CString6Abbrev = 0;
 523   // If this is a constant pool for the module, emit module-specific abbrevs.
 524   if (isGlobal) {
 525     // Abbrev for CST_CODE_AGGREGATE.
 526     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 527     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 528     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 529     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 530     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 531
 532     // Abbrev for CST_CODE_STRING.
 533     Abbv = new BitCodeAbbrev();
 534     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 535     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 536     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 537     String8Abbrev = Stream.EmitAbbrev(Abbv);
 538     // Abbrev for CST_CODE_CSTRING.
 539     Abbv = new BitCodeAbbrev();
 540     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 541     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 542     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 543     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 544     // Abbrev for CST_CODE_CSTRING.
 545     Abbv = new BitCodeAbbrev();
 546     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 547     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 548     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 549     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 550   }
 551
 552   SmallVector<uint64_t, 64> Record;
 553
 554   const ValueEnumerator::ValueList &Vals = VE.getValues();
 555   const Type *LastTy = 0;
 556   for (unsigned i = FirstVal; i != LastVal; ++i) {
 557     const Value *V = Vals[i].first;
 558     if (isa<MDString>(V))
 559       continue;
 560     // If we need to switch types, do so now.
 561     if (V->getType() != LastTy) {
 562       LastTy = V->getType();
 563       Record.push_back(VE.getTypeID(LastTy));
 564       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 565                         CONSTANTS_SETTYPE_ABBREV);
 566       Record.clear();
 567     }
 568
 569     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 570       Record.push_back(unsigned(IA->hasSideEffects()));
 571
 572       // Add the asm string.
 573       const std::string &AsmStr = IA->getAsmString();
 574       Record.push_back(AsmStr.size());
 575       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 576         Record.push_back(AsmStr[i]);
 577
 578       // Add the constraint string.
 579       const std::string &ConstraintStr = IA->getConstraintString();
 580       Record.push_back(ConstraintStr.size());
 581       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 582         Record.push_back(ConstraintStr[i]);
 583       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 584       Record.clear();
 585       continue;
 586     }
 587     const Constant *C = cast<Constant>(V);
 588     unsigned Code = -1U;
 589     unsigned AbbrevToUse = 0;
 590     if (C->isNullValue()) {
 591       Code = bitc::CST_CODE_NULL;
 592     } else if (isa<UndefValue>(C)) {
 593       Code = bitc::CST_CODE_UNDEF;
 594     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 595       if (IV->getBitWidth() <= 64) {
 596         int64_t V = IV->getSExtValue();
 597         if (V >= 0)
 598           Record.push_back(V << 1);
 599         else
 600           Record.push_back((-V << 1) | 1);
 601         Code = bitc::CST_CODE_INTEGER;
 602         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 603       } else {                             // Wide integers, > 64 bits in size.
 604         // We have an arbitrary precision integer value to write whose
 605         // bit width is > 64. However, in canonical unsigned integer
 606         // format it is likely that the high bits are going to be zero.
 607         // So, we only write the number of active words.
 608         unsigned NWords = IV->getValue().getActiveWords();
 609         const uint64_t *RawWords = IV->getValue().getRawData();
 610         for (unsigned i = 0; i != NWords; ++i) {
 611           int64_t V = RawWords[i];
 612           if (V >= 0)
 613             Record.push_back(V << 1);
 614           else
 615             Record.push_back((-V << 1) | 1);
 616         }
 617         Code = bitc::CST_CODE_WIDE_INTEGER;
 618       }
 619     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 620       Code = bitc::CST_CODE_FLOAT;
 621       const Type *Ty = CFP->getType();
 622       if (Ty == Type::FloatTy || Ty == Type::DoubleTy) {
 623         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 624       } else if (Ty == Type::X86_FP80Ty) {
 625         // api needed to prevent premature destruction
 626         // bits are not in the same order as a normal i80 APInt, compensate.
 627         APInt api = CFP->getValueAPF().bitcastToAPInt();
 628         const uint64_t *p = api.getRawData();
 629         Record.push_back((p[1] << 48) | (p[0] >> 16));
 630         Record.push_back(p[0] & 0xffffLL);
 631       } else if (Ty == Type::FP128Ty || Ty == Type::PPC_FP128Ty) {
 632         APInt api = CFP->getValueAPF().bitcastToAPInt();
 633         const uint64_t *p = api.getRawData();
 634         Record.push_back(p[0]);
 635         Record.push_back(p[1]);
 636       } else {
 637         assert (0 && "Unknown FP type!");
 638       }
 639     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 640       // Emit constant strings specially.
 641       unsigned NumOps = C->getNumOperands();
 642       // If this is a null-terminated string, use the denser CSTRING encoding.
 643       if (C->getOperand(NumOps-1)->isNullValue()) {
 644         Code = bitc::CST_CODE_CSTRING;
 645         --NumOps;  // Don't encode the null, which isn't allowed by char6.
 646       } else {
 647         Code = bitc::CST_CODE_STRING;
 648         AbbrevToUse = String8Abbrev;
 649       }
 650       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 651       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 652       for (unsigned i = 0; i != NumOps; ++i) {
 653         unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
 654         Record.push_back(V);
 655         isCStr7 &= (V & 128) == 0;
 656         if (isCStrChar6)
 657           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 658       }
 659
 660       if (isCStrChar6)
 661         AbbrevToUse = CString6Abbrev;
 662       else if (isCStr7)
 663         AbbrevToUse = CString7Abbrev;
 664     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
 665                isa<ConstantVector>(V)) {
 666       Code = bitc::CST_CODE_AGGREGATE;
 667       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 668         Record.push_back(VE.getValueID(C->getOperand(i)));
 669       AbbrevToUse = AggregateAbbrev;
 670     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 671       switch (CE->getOpcode()) {
 672       default:
 673         if (Instruction::isCast(CE->getOpcode())) {
 674           Code = bitc::CST_CODE_CE_CAST;
 675           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 676           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 677           Record.push_back(VE.getValueID(C->getOperand(0)));
 678           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 679         } else {
 680           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 681           Code = bitc::CST_CODE_CE_BINOP;
 682           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 683           Record.push_back(VE.getValueID(C->getOperand(0)));
 684           Record.push_back(VE.getValueID(C->getOperand(1)));
 685           uint64_t Flags = GetOptimizationFlags(CE);
 686           if (Flags != 0)
 687             Record.push_back(Flags);
 688         }
 689         break;
 690       case Instruction::GetElementPtr:
 691         Code = bitc::CST_CODE_CE_GEP;
 692         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 693           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 694           Record.push_back(VE.getValueID(C->getOperand(i)));
 695         }
 696         break;
 697       case Instruction::Select:
 698         Code = bitc::CST_CODE_CE_SELECT;
 699         Record.push_back(VE.getValueID(C->getOperand(0)));
 700         Record.push_back(VE.getValueID(C->getOperand(1)));
 701         Record.push_back(VE.getValueID(C->getOperand(2)));
 702         break;
 703       case Instruction::ExtractElement:
 704         Code = bitc::CST_CODE_CE_EXTRACTELT;
 705         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 706         Record.push_back(VE.getValueID(C->getOperand(0)));
 707         Record.push_back(VE.getValueID(C->getOperand(1)));
 708         break;
 709       case Instruction::InsertElement:
 710         Code = bitc::CST_CODE_CE_INSERTELT;
 711         Record.push_back(VE.getValueID(C->getOperand(0)));
 712         Record.push_back(VE.getValueID(C->getOperand(1)));
 713         Record.push_back(VE.getValueID(C->getOperand(2)));
 714         break;
 715       case Instruction::ShuffleVector:
 716         // If the return type and argument types are the same, this is a
 717         // standard shufflevector instruction.  If the types are different,
 718         // then the shuffle is widening or truncating the input vectors, and
 719         // the argument type must also be encoded.
 720         if (C->getType() == C->getOperand(0)->getType()) {
 721           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 722         } else {
 723           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 724           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 725         }
 726         Record.push_back(VE.getValueID(C->getOperand(0)));
 727         Record.push_back(VE.getValueID(C->getOperand(1)));
 728         Record.push_back(VE.getValueID(C->getOperand(2)));
 729         break;
 730       case Instruction::ICmp:
 731       case Instruction::FCmp:
 732         Code = bitc::CST_CODE_CE_CMP;
 733         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 734         Record.push_back(VE.getValueID(C->getOperand(0)));
 735         Record.push_back(VE.getValueID(C->getOperand(1)));
 736         Record.push_back(CE->getPredicate());
 737         break;
 738       }
 739     } else if (const MDNode *N = dyn_cast<MDNode>(C)) {
 740       Code = bitc::CST_CODE_MDNODE;
 741       for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
 742         if (N->getElement(i)) {
 743           Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
 744           Record.push_back(VE.getValueID(N->getElement(i)));
 745         } else {
 746           Record.push_back(VE.getTypeID(Type::VoidTy));
 747           Record.push_back(0);
 748         }
 749       }
 750     } else {
 751       llvm_unreachable("Unknown constant!");
 752     }
 753     Stream.EmitRecord(Code, Record, AbbrevToUse);
 754     Record.clear();
 755   }
 756
 757   Stream.ExitBlock();
 758 }
 759
 760 static void WriteModuleConstants(const ValueEnumerator &VE,
 761                                  BitstreamWriter &Stream) {
 762   const ValueEnumerator::ValueList &Vals = VE.getValues();
 763
 764   // Find the first constant to emit, which is the first non-globalvalue value.
 765   // We know globalvalues have been emitted by WriteModuleInfo.
 766   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 767     if (!isa<GlobalValue>(Vals[i].first)) {
 768       WriteConstants(i, Vals.size(), VE, Stream, true);
 769       return;
 770     }
 771   }
 772 }
 773
 774 /// PushValueAndType - The file has to encode both the value and type id for
 775 /// many values, because we need to know what type to create for forward
 776 /// references.  However, most operands are not forward references, so this type
 777 /// field is not needed.
 778 ///
 779 /// This function adds V's value ID to Vals.  If the value ID is higher than the
 780 /// instruction ID, then it is a forward reference, and it also includes the
 781 /// type ID.
 782 static bool PushValueAndType(const Value *V, unsigned InstID,
 783                              SmallVector<unsigned, 64> &Vals,
 784                              ValueEnumerator &VE) {
 785   unsigned ValID = VE.getValueID(V);
 786   Vals.push_back(ValID);
 787   if (ValID >= InstID) {
 788     Vals.push_back(VE.getTypeID(V->getType()));
 789     return true;
 790   }
 791   return false;
 792 }
 793
 794 /// WriteInstruction - Emit an instruction to the specified stream.
 795 static void WriteInstruction(const Instruction &I, unsigned InstID,
 796                              ValueEnumerator &VE, BitstreamWriter &Stream,
 797                              SmallVector<unsigned, 64> &Vals) {
 798   unsigned Code = 0;
 799   unsigned AbbrevToUse = 0;
 800   switch (I.getOpcode()) {
 801   default:
 802     if (Instruction::isCast(I.getOpcode())) {
 803       Code = bitc::FUNC_CODE_INST_CAST;
 804       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 805         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
 806       Vals.push_back(VE.getTypeID(I.getType()));
 807       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
 808     } else {
 809       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
 810       Code = bitc::FUNC_CODE_INST_BINOP;
 811       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 812         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
 813       Vals.push_back(VE.getValueID(I.getOperand(1)));
 814       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
 815       uint64_t Flags = GetOptimizationFlags(&I);
 816       if (Flags != 0) {
 817         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
 818           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
 819         Vals.push_back(Flags);
 820       }
 821     }
 822     break;
 823
 824   case Instruction::GetElementPtr:
 825     Code = bitc::FUNC_CODE_INST_GEP;
 826     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 827       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 828     break;
 829   case Instruction::ExtractValue: {
 830     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
 831     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 832     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
 833     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
 834       Vals.push_back(*i);
 835     break;
 836   }
 837   case Instruction::InsertValue: {
 838     Code = bitc::FUNC_CODE_INST_INSERTVAL;
 839     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 840     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 841     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
 842     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
 843       Vals.push_back(*i);
 844     break;
 845   }
 846   case Instruction::Select:
 847     Code = bitc::FUNC_CODE_INST_VSELECT;
 848     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 849     Vals.push_back(VE.getValueID(I.getOperand(2)));
 850     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 851     break;
 852   case Instruction::ExtractElement:
 853     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
 854     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 855     Vals.push_back(VE.getValueID(I.getOperand(1)));
 856     break;
 857   case Instruction::InsertElement:
 858     Code = bitc::FUNC_CODE_INST_INSERTELT;
 859     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 860     Vals.push_back(VE.getValueID(I.getOperand(1)));
 861     Vals.push_back(VE.getValueID(I.getOperand(2)));
 862     break;
 863   case Instruction::ShuffleVector:
 864     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
 865     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 866     Vals.push_back(VE.getValueID(I.getOperand(1)));
 867     Vals.push_back(VE.getValueID(I.getOperand(2)));
 868     break;
 869   case Instruction::ICmp:
 870   case Instruction::FCmp:
 871     // compare returning Int1Ty or vector of Int1Ty
 872     Code = bitc::FUNC_CODE_INST_CMP2;
 873     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 874     Vals.push_back(VE.getValueID(I.getOperand(1)));
 875     Vals.push_back(cast<CmpInst>(I).getPredicate());
 876     break;
 877
 878   case Instruction::Ret:
 879     {
 880       Code = bitc::FUNC_CODE_INST_RET;
 881       unsigned NumOperands = I.getNumOperands();
 882       if (NumOperands == 0)
 883         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
 884       else if (NumOperands == 1) {
 885         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 886           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
 887       } else {
 888         for (unsigned i = 0, e = NumOperands; i != e; ++i)
 889           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 890       }
 891     }
 892     break;
 893   case Instruction::Br:
 894     {
 895       Code = bitc::FUNC_CODE_INST_BR;
 896       BranchInst &II(cast<BranchInst>(I));
 897       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
 898       if (II.isConditional()) {
 899         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
 900         Vals.push_back(VE.getValueID(II.getCondition()));
 901       }
 902     }
 903     break;
 904   case Instruction::Switch:
 905     Code = bitc::FUNC_CODE_INST_SWITCH;
 906     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
 907     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 908       Vals.push_back(VE.getValueID(I.getOperand(i)));
 909     break;
 910   case Instruction::Invoke: {
 911     const InvokeInst *II = cast<InvokeInst>(&I);
 912     const Value *Callee(II->getCalledValue());
 913     const PointerType *PTy = cast<PointerType>(Callee->getType());
 914     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 915     Code = bitc::FUNC_CODE_INST_INVOKE;
 916
 917     Vals.push_back(VE.getAttributeID(II->getAttributes()));
 918     Vals.push_back(II->getCallingConv());
 919     Vals.push_back(VE.getValueID(II->getNormalDest()));
 920     Vals.push_back(VE.getValueID(II->getUnwindDest()));
 921     PushValueAndType(Callee, InstID, Vals, VE);
 922
 923     // Emit value #'s for the fixed parameters.
 924     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 925       Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
 926
 927     // Emit type/value pairs for varargs params.
 928     if (FTy->isVarArg()) {
 929       for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
 930            i != e; ++i)
 931         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
 932     }
 933     break;
 934   }
 935   case Instruction::Unwind:
 936     Code = bitc::FUNC_CODE_INST_UNWIND;
 937     break;
 938   case Instruction::Unreachable:
 939     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
 940     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
 941     break;
 942
 943   case Instruction::PHI:
 944     Code = bitc::FUNC_CODE_INST_PHI;
 945     Vals.push_back(VE.getTypeID(I.getType()));
 946     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 947       Vals.push_back(VE.getValueID(I.getOperand(i)));
 948     break;
 949
 950   case Instruction::Malloc:
 951     Code = bitc::FUNC_CODE_INST_MALLOC;
 952     Vals.push_back(VE.getTypeID(I.getType()));
 953     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 954     Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
 955     break;
 956
 957   case Instruction::Free:
 958     Code = bitc::FUNC_CODE_INST_FREE;
 959     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 960     break;
 961
 962   case Instruction::Alloca:
 963     Code = bitc::FUNC_CODE_INST_ALLOCA;
 964     Vals.push_back(VE.getTypeID(I.getType()));
 965     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 966     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
 967     break;
 968
 969   case Instruction::Load:
 970     Code = bitc::FUNC_CODE_INST_LOAD;
 971     if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
 972       AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
 973
 974     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
 975     Vals.push_back(cast<LoadInst>(I).isVolatile());
 976     break;
 977   case Instruction::Store:
 978     Code = bitc::FUNC_CODE_INST_STORE2;
 979     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
 980     Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
 981     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
 982     Vals.push_back(cast<StoreInst>(I).isVolatile());
 983     break;
 984   case Instruction::Call: {
 985     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
 986     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 987
 988     Code = bitc::FUNC_CODE_INST_CALL;
 989
 990     const CallInst *CI = cast<CallInst>(&I);
 991     Vals.push_back(VE.getAttributeID(CI->getAttributes()));
 992     Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
 993     PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
 994
 995     // Emit value #'s for the fixed parameters.
 996     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 997       Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
 998
 999     // Emit type/value pairs for varargs params.
1000     if (FTy->isVarArg()) {
1001       unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1002       for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1003            i != e; ++i)
1004         PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1005     }
1006     break;
1007   }
1008   case Instruction::VAArg:
1009     Code = bitc::FUNC_CODE_INST_VAARG;
1010     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1011     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1012     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1013     break;
1014   }
1015
1016   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1017   Vals.clear();
1018 }
1019
1020 // Emit names for globals/functions etc.
1021 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1022                                   const ValueEnumerator &VE,
1023                                   BitstreamWriter &Stream) {
1024   if (VST.empty()) return;
1025   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1026
1027   // FIXME: Set up the abbrev, we know how many values there are!
1028   // FIXME: We know if the type names can use 7-bit ascii.
1029   SmallVector<unsigned, 64> NameVals;
1030
1031   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1032        SI != SE; ++SI) {
1033
1034     const ValueName &Name = *SI;
1035
1036     // Figure out the encoding to use for the name.
1037     bool is7Bit = true;
1038     bool isChar6 = true;
1039     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1040          C != E; ++C) {
1041       if (isChar6)
1042         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1043       if ((unsigned char)*C & 128) {
1044         is7Bit = false;
1045         break;  // don't bother scanning the rest.
1046       }
1047     }
1048
1049     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1050
1051     // VST_ENTRY:   [valueid, namechar x N]
1052     // VST_BBENTRY: [bbid, namechar x N]
1053     unsigned Code;
1054     if (isa<BasicBlock>(SI->getValue())) {
1055       Code = bitc::VST_CODE_BBENTRY;
1056       if (isChar6)
1057         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1058     } else {
1059       Code = bitc::VST_CODE_ENTRY;
1060       if (isChar6)
1061         AbbrevToUse = VST_ENTRY_6_ABBREV;
1062       else if (is7Bit)
1063         AbbrevToUse = VST_ENTRY_7_ABBREV;
1064     }
1065
1066     NameVals.push_back(VE.getValueID(SI->getValue()));
1067     for (const char *P = Name.getKeyData(),
1068          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1069       NameVals.push_back((unsigned char)*P);
1070
1071     // Emit the finished record.
1072     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1073     NameVals.clear();
1074   }
1075   Stream.ExitBlock();
1076 }
1077
1078 /// WriteFunction - Emit a function body to the module stream.
1079 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1080                           BitstreamWriter &Stream) {
1081   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1082   VE.incorporateFunction(F);
1083
1084   SmallVector<unsigned, 64> Vals;
1085
1086   // Emit the number of basic blocks, so the reader can create them ahead of
1087   // time.
1088   Vals.push_back(VE.getBasicBlocks().size());
1089   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1090   Vals.clear();
1091
1092   // If there are function-local constants, emit them now.
1093   unsigned CstStart, CstEnd;
1094   VE.getFunctionConstantRange(CstStart, CstEnd);
1095   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1096
1097   // Keep a running idea of what the instruction ID is.
1098   unsigned InstID = CstEnd;
1099
1100   // Finally, emit all the instructions, in order.
1101   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1102     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1103          I != E; ++I) {
1104       WriteInstruction(*I, InstID, VE, Stream, Vals);
1105       if (I->getType() != Type::VoidTy)
1106         ++InstID;
1107     }
1108
1109   // Emit names for all the instructions etc.
1110   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1111
1112   VE.purgeFunction();
1113   Stream.ExitBlock();
1114 }
1115
1116 /// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1117 static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1118                                  const ValueEnumerator &VE,
1119                                  BitstreamWriter &Stream) {
1120   if (TST.empty()) return;
1121
1122   Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1123
1124   // 7-bit fixed width VST_CODE_ENTRY strings.
1125   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1126   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1127   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1128                             Log2_32_Ceil(VE.getTypes().size()+1)));
1129   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1130   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1131   unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1132
1133   SmallVector<unsigned, 64> NameVals;
1134
1135   for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1136        TI != TE; ++TI) {
1137     // TST_ENTRY: [typeid, namechar x N]
1138     NameVals.push_back(VE.getTypeID(TI->second));
1139
1140     const std::string &Str = TI->first;
1141     bool is7Bit = true;
1142     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1143       NameVals.push_back((unsigned char)Str[i]);
1144       if (Str[i] & 128)
1145         is7Bit = false;
1146     }
1147
1148     // Emit the finished record.
1149     Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1150     NameVals.clear();
1151   }
1152
1153   Stream.ExitBlock();
1154 }
1155
1156 // Emit blockinfo, which defines the standard abbreviations etc.
1157 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1158   // We only want to emit block info records for blocks that have multiple
1159   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1160   // blocks can defined their abbrevs inline.
1161   Stream.EnterBlockInfoBlock(2);
1162
1163   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1164     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1165     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1166     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1167     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1168     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1169     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1170                                    Abbv) != VST_ENTRY_8_ABBREV)
1171       llvm_unreachable("Unexpected abbrev ordering!");
1172   }
1173
1174   { // 7-bit fixed width VST_ENTRY strings.
1175     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1176     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1178     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1179     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1180     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1181                                    Abbv) != VST_ENTRY_7_ABBREV)
1182       llvm_unreachable("Unexpected abbrev ordering!");
1183   }
1184   { // 6-bit char6 VST_ENTRY strings.
1185     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1186     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1187     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1188     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1189     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1190     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1191                                    Abbv) != VST_ENTRY_6_ABBREV)
1192       llvm_unreachable("Unexpected abbrev ordering!");
1193   }
1194   { // 6-bit char6 VST_BBENTRY strings.
1195     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1196     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1197     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1198     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1199     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1200     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1201                                    Abbv) != VST_BBENTRY_6_ABBREV)
1202       llvm_unreachable("Unexpected abbrev ordering!");
1203   }
1204
1205
1206
1207   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1208     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1209     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1210     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1211                               Log2_32_Ceil(VE.getTypes().size()+1)));
1212     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1213                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1214       llvm_unreachable("Unexpected abbrev ordering!");
1215   }
1216
1217   { // INTEGER abbrev for CONSTANTS_BLOCK.
1218     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1219     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1220     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1221     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1222                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1223       llvm_unreachable("Unexpected abbrev ordering!");
1224   }
1225
1226   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1227     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1228     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1229     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1230     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1231                               Log2_32_Ceil(VE.getTypes().size()+1)));
1232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1233
1234     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1235                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1236       llvm_unreachable("Unexpected abbrev ordering!");
1237   }
1238   { // NULL abbrev for CONSTANTS_BLOCK.
1239     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1240     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1241     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1242                                    Abbv) != CONSTANTS_NULL_Abbrev)
1243       llvm_unreachable("Unexpected abbrev ordering!");
1244   }
1245
1246   // FIXME: This should only use space for first class types!
1247
1248   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1249     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1250     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1251     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1252     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1253     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1254     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1255                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1256       llvm_unreachable("Unexpected abbrev ordering!");
1257   }
1258   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1259     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1260     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1261     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1262     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1263     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1264     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1265                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1266       llvm_unreachable("Unexpected abbrev ordering!");
1267   }
1268   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1269     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1270     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1271     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1272     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1273     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1274     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1275     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1276                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1277       llvm_unreachable("Unexpected abbrev ordering!");
1278   }
1279   { // INST_CAST abbrev for FUNCTION_BLOCK.
1280     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1281     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1282     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1283     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1284                               Log2_32_Ceil(VE.getTypes().size()+1)));
1285     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1286     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1287                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1288       llvm_unreachable("Unexpected abbrev ordering!");
1289   }
1290
1291   { // INST_RET abbrev for FUNCTION_BLOCK.
1292     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1293     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1294     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1295                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1296       llvm_unreachable("Unexpected abbrev ordering!");
1297   }
1298   { // INST_RET abbrev for FUNCTION_BLOCK.
1299     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1300     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1301     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1302     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1303                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1304       llvm_unreachable("Unexpected abbrev ordering!");
1305   }
1306   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1307     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1308     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1309     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1310                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1311       llvm_unreachable("Unexpected abbrev ordering!");
1312   }
1313
1314   Stream.ExitBlock();
1315 }
1316
1317
1318 /// WriteModule - Emit the specified module to the bitstream.
1319 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1320   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1321
1322   // Emit the version number if it is non-zero.
1323   if (CurVersion) {
1324     SmallVector<unsigned, 1> Vals;
1325     Vals.push_back(CurVersion);
1326     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1327   }
1328
1329   // Analyze the module, enumerating globals, functions, etc.
1330   ValueEnumerator VE(M);
1331
1332   // Emit blockinfo, which defines the standard abbreviations etc.
1333   WriteBlockInfo(VE, Stream);
1334
1335   // Emit information about parameter attributes.
1336   WriteAttributeTable(VE, Stream);
1337
1338   // Emit information describing all of the types in the module.
1339   WriteTypeTable(VE, Stream);
1340
1341   // Emit top-level description of module, including target triple, inline asm,
1342   // descriptors for global variables, and function prototype info.
1343   WriteModuleInfo(M, VE, Stream);
1344
1345   // Emit metadata.
1346   WriteModuleMetadata(VE, Stream);
1347
1348   // Emit constants.
1349   WriteModuleConstants(VE, Stream);
1350
1351   // Emit function bodies.
1352   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1353     if (!I->isDeclaration())
1354       WriteFunction(*I, VE, Stream);
1355
1356   // Emit the type symbol table information.
1357   WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1358
1359   // Emit names for globals/functions etc.
1360   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1361
1362   Stream.ExitBlock();
1363 }
1364
1365 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1366 /// header and trailer to make it compatible with the system archiver.  To do
1367 /// this we emit the following header, and then emit a trailer that pads the
1368 /// file out to be a multiple of 16 bytes.
1369 ///
1370 /// struct bc_header {
1371 ///   uint32_t Magic;         // 0x0B17C0DE
1372 ///   uint32_t Version;       // Version, currently always 0.
1373 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1374 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1375 ///   uint32_t CPUType;       // CPU specifier.
1376 ///   ... potentially more later ...
1377 /// };
1378 enum {
1379   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1380   DarwinBCHeaderSize = 5*4
1381 };
1382
1383 static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1384                                const std::string &TT) {
1385   unsigned CPUType = ~0U;
1386
1387   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1388   // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1389   // specific constants here because they are implicitly part of the Darwin ABI.
1390   enum {
1391     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1392     DARWIN_CPU_TYPE_X86        = 7,
1393     DARWIN_CPU_TYPE_POWERPC    = 18
1394   };
1395
1396   if (TT.find("x86_64-") == 0)
1397     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1398   else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1399            TT[4] == '-' && TT[1] - '3' < 6)
1400     CPUType = DARWIN_CPU_TYPE_X86;
1401   else if (TT.find("powerpc-") == 0)
1402     CPUType = DARWIN_CPU_TYPE_POWERPC;
1403   else if (TT.find("powerpc64-") == 0)
1404     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1405
1406   // Traditional Bitcode starts after header.
1407   unsigned BCOffset = DarwinBCHeaderSize;
1408
1409   Stream.Emit(0x0B17C0DE, 32);
1410   Stream.Emit(0         , 32);  // Version.
1411   Stream.Emit(BCOffset  , 32);
1412   Stream.Emit(0         , 32);  // Filled in later.
1413   Stream.Emit(CPUType   , 32);
1414 }
1415
1416 /// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1417 /// finalize the header.
1418 static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1419   // Update the size field in the header.
1420   Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1421
1422   // If the file is not a multiple of 16 bytes, insert dummy padding.
1423   while (BufferSize & 15) {
1424     Stream.Emit(0, 8);
1425     ++BufferSize;
1426   }
1427 }
1428
1429
1430 /// WriteBitcodeToFile - Write the specified module to the specified output
1431 /// stream.
1432 void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1433   raw_os_ostream RawOut(Out);
1434   // If writing to stdout, set binary mode.
1435   if (llvm::cout == Out)
1436     sys::Program::ChangeStdoutToBinary();
1437   WriteBitcodeToFile(M, RawOut);
1438 }
1439
1440 /// WriteBitcodeToFile - Write the specified module to the specified output
1441 /// stream.
1442 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1443   std::vector<unsigned char> Buffer;
1444   BitstreamWriter Stream(Buffer);
1445
1446   Buffer.reserve(256*1024);
1447
1448   WriteBitcodeToStream( M, Stream );
1449
1450   // If writing to stdout, set binary mode.
1451   if (&llvm::outs() == &Out)
1452     sys::Program::ChangeStdoutToBinary();
1453
1454   // Write the generated bitstream to "Out".
1455   Out.write((char*)&Buffer.front(), Buffer.size());
1456
1457   // Make sure it hits disk now.
1458   Out.flush();
1459 }
1460
1461 /// WriteBitcodeToStream - Write the specified module to the specified output
1462 /// stream.
1463 void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1464   // If this is darwin, emit a file header and trailer if needed.
1465   bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1466   if (isDarwin)
1467     EmitDarwinBCHeader(Stream, M->getTargetTriple());
1468
1469   // Emit the file header.
1470   Stream.Emit((unsigned)'B', 8);
1471   Stream.Emit((unsigned)'C', 8);
1472   Stream.Emit(0x0, 4);
1473   Stream.Emit(0xC, 4);
1474   Stream.Emit(0xE, 4);
1475   Stream.Emit(0xD, 4);
1476
1477   // Emit the module.
1478   WriteModule(M, Stream);
1479
1480   if (isDarwin)
1481     EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1482 }