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