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    SmallVector<uint64_t, 64> Record;
 482    for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 483
 484      if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 485        if (!StartedMetadataBlock) {
 486          Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 487          StartedMetadataBlock = true;
 488        }
 489       for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
 490         if (N->getElement(i)) {
 491           Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
 492           Record.push_back(VE.getValueID(N->getElement(i)));
 493         } else {
 494           Record.push_back(VE.getTypeID(Type::VoidTy));
 495           Record.push_back(0);
 496         }
 497       }
 498       Stream.EmitRecord(bitc::METADATA_NODE, Record, 0);
 499       Record.clear();
 500      } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 501        if (!StartedMetadataBlock)  {
 502         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 503
 504         // Abbrev for METADATA_STRING.
 505         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 506         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 507         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 508         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 509         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 510         StartedMetadataBlock = true;
 511        }
 512
 513        // Code: [strchar x N]
 514        const char *StrBegin = MDS->begin();
 515        for (unsigned i = 0, e = MDS->size(); i != e; ++i)
 516         Record.push_back(StrBegin[i]);
 517
 518        // Emit the finished record.
 519       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 520       Record.clear();
 521      }
 522    }
 523
 524    if (StartedMetadataBlock)
 525      Stream.ExitBlock();
 526 }
 527
 528
 529 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 530                            const ValueEnumerator &VE,
 531                            BitstreamWriter &Stream, bool isGlobal) {
 532   if (FirstVal == LastVal) return;
 533
 534   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 535
 536   unsigned AggregateAbbrev = 0;
 537   unsigned String8Abbrev = 0;
 538   unsigned CString7Abbrev = 0;
 539   unsigned CString6Abbrev = 0;
 540   // If this is a constant pool for the module, emit module-specific abbrevs.
 541   if (isGlobal) {
 542     // Abbrev for CST_CODE_AGGREGATE.
 543     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 544     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 545     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 546     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 547     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 548
 549     // Abbrev for CST_CODE_STRING.
 550     Abbv = new BitCodeAbbrev();
 551     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 552     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 553     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 554     String8Abbrev = Stream.EmitAbbrev(Abbv);
 555     // Abbrev for CST_CODE_CSTRING.
 556     Abbv = new BitCodeAbbrev();
 557     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 558     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 559     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 560     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 561     // Abbrev for CST_CODE_CSTRING.
 562     Abbv = new BitCodeAbbrev();
 563     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 564     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 565     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 566     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 567   }
 568
 569   SmallVector<uint64_t, 64> Record;
 570
 571   const ValueEnumerator::ValueList &Vals = VE.getValues();
 572   const Type *LastTy = 0;
 573   for (unsigned i = FirstVal; i != LastVal; ++i) {
 574     const Value *V = Vals[i].first;
 575     if (isa<MDString>(V) || isa<MDNode>(V))
 576       continue;
 577     // If we need to switch types, do so now.
 578     if (V->getType() != LastTy) {
 579       LastTy = V->getType();
 580       Record.push_back(VE.getTypeID(LastTy));
 581       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 582                         CONSTANTS_SETTYPE_ABBREV);
 583       Record.clear();
 584     }
 585
 586     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 587       Record.push_back(unsigned(IA->hasSideEffects()));
 588
 589       // Add the asm string.
 590       const std::string &AsmStr = IA->getAsmString();
 591       Record.push_back(AsmStr.size());
 592       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 593         Record.push_back(AsmStr[i]);
 594
 595       // Add the constraint string.
 596       const std::string &ConstraintStr = IA->getConstraintString();
 597       Record.push_back(ConstraintStr.size());
 598       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 599         Record.push_back(ConstraintStr[i]);
 600       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 601       Record.clear();
 602       continue;
 603     }
 604     const Constant *C = cast<Constant>(V);
 605     unsigned Code = -1U;
 606     unsigned AbbrevToUse = 0;
 607     if (C->isNullValue()) {
 608       Code = bitc::CST_CODE_NULL;
 609     } else if (isa<UndefValue>(C)) {
 610       Code = bitc::CST_CODE_UNDEF;
 611     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 612       if (IV->getBitWidth() <= 64) {
 613         int64_t V = IV->getSExtValue();
 614         if (V >= 0)
 615           Record.push_back(V << 1);
 616         else
 617           Record.push_back((-V << 1) | 1);
 618         Code = bitc::CST_CODE_INTEGER;
 619         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 620       } else {                             // Wide integers, > 64 bits in size.
 621         // We have an arbitrary precision integer value to write whose
 622         // bit width is > 64. However, in canonical unsigned integer
 623         // format it is likely that the high bits are going to be zero.
 624         // So, we only write the number of active words.
 625         unsigned NWords = IV->getValue().getActiveWords();
 626         const uint64_t *RawWords = IV->getValue().getRawData();
 627         for (unsigned i = 0; i != NWords; ++i) {
 628           int64_t V = RawWords[i];
 629           if (V >= 0)
 630             Record.push_back(V << 1);
 631           else
 632             Record.push_back((-V << 1) | 1);
 633         }
 634         Code = bitc::CST_CODE_WIDE_INTEGER;
 635       }
 636     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 637       Code = bitc::CST_CODE_FLOAT;
 638       const Type *Ty = CFP->getType();
 639       if (Ty == Type::FloatTy || Ty == Type::DoubleTy) {
 640         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 641       } else if (Ty == Type::X86_FP80Ty) {
 642         // api needed to prevent premature destruction
 643         // bits are not in the same order as a normal i80 APInt, compensate.
 644         APInt api = CFP->getValueAPF().bitcastToAPInt();
 645         const uint64_t *p = api.getRawData();
 646         Record.push_back((p[1] << 48) | (p[0] >> 16));
 647         Record.push_back(p[0] & 0xffffLL);
 648       } else if (Ty == Type::FP128Ty || Ty == Type::PPC_FP128Ty) {
 649         APInt api = CFP->getValueAPF().bitcastToAPInt();
 650         const uint64_t *p = api.getRawData();
 651         Record.push_back(p[0]);
 652         Record.push_back(p[1]);
 653       } else {
 654         assert (0 && "Unknown FP type!");
 655       }
 656     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 657       // Emit constant strings specially.
 658       unsigned NumOps = C->getNumOperands();
 659       // If this is a null-terminated string, use the denser CSTRING encoding.
 660       if (C->getOperand(NumOps-1)->isNullValue()) {
 661         Code = bitc::CST_CODE_CSTRING;
 662         --NumOps;  // Don't encode the null, which isn't allowed by char6.
 663       } else {
 664         Code = bitc::CST_CODE_STRING;
 665         AbbrevToUse = String8Abbrev;
 666       }
 667       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 668       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 669       for (unsigned i = 0; i != NumOps; ++i) {
 670         unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
 671         Record.push_back(V);
 672         isCStr7 &= (V & 128) == 0;
 673         if (isCStrChar6)
 674           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 675       }
 676
 677       if (isCStrChar6)
 678         AbbrevToUse = CString6Abbrev;
 679       else if (isCStr7)
 680         AbbrevToUse = CString7Abbrev;
 681     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
 682                isa<ConstantVector>(V)) {
 683       Code = bitc::CST_CODE_AGGREGATE;
 684       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 685         Record.push_back(VE.getValueID(C->getOperand(i)));
 686       AbbrevToUse = AggregateAbbrev;
 687     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 688       switch (CE->getOpcode()) {
 689       default:
 690         if (Instruction::isCast(CE->getOpcode())) {
 691           Code = bitc::CST_CODE_CE_CAST;
 692           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 693           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 694           Record.push_back(VE.getValueID(C->getOperand(0)));
 695           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 696         } else {
 697           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 698           Code = bitc::CST_CODE_CE_BINOP;
 699           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 700           Record.push_back(VE.getValueID(C->getOperand(0)));
 701           Record.push_back(VE.getValueID(C->getOperand(1)));
 702           uint64_t Flags = GetOptimizationFlags(CE);
 703           if (Flags != 0)
 704             Record.push_back(Flags);
 705         }
 706         break;
 707       case Instruction::GetElementPtr:
 708         Code = bitc::CST_CODE_CE_GEP;
 709         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 710           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 711           Record.push_back(VE.getValueID(C->getOperand(i)));
 712         }
 713         break;
 714       case Instruction::Select:
 715         Code = bitc::CST_CODE_CE_SELECT;
 716         Record.push_back(VE.getValueID(C->getOperand(0)));
 717         Record.push_back(VE.getValueID(C->getOperand(1)));
 718         Record.push_back(VE.getValueID(C->getOperand(2)));
 719         break;
 720       case Instruction::ExtractElement:
 721         Code = bitc::CST_CODE_CE_EXTRACTELT;
 722         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 723         Record.push_back(VE.getValueID(C->getOperand(0)));
 724         Record.push_back(VE.getValueID(C->getOperand(1)));
 725         break;
 726       case Instruction::InsertElement:
 727         Code = bitc::CST_CODE_CE_INSERTELT;
 728         Record.push_back(VE.getValueID(C->getOperand(0)));
 729         Record.push_back(VE.getValueID(C->getOperand(1)));
 730         Record.push_back(VE.getValueID(C->getOperand(2)));
 731         break;
 732       case Instruction::ShuffleVector:
 733         // If the return type and argument types are the same, this is a
 734         // standard shufflevector instruction.  If the types are different,
 735         // then the shuffle is widening or truncating the input vectors, and
 736         // the argument type must also be encoded.
 737         if (C->getType() == C->getOperand(0)->getType()) {
 738           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 739         } else {
 740           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 741           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 742         }
 743         Record.push_back(VE.getValueID(C->getOperand(0)));
 744         Record.push_back(VE.getValueID(C->getOperand(1)));
 745         Record.push_back(VE.getValueID(C->getOperand(2)));
 746         break;
 747       case Instruction::ICmp:
 748       case Instruction::FCmp:
 749         Code = bitc::CST_CODE_CE_CMP;
 750         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 751         Record.push_back(VE.getValueID(C->getOperand(0)));
 752         Record.push_back(VE.getValueID(C->getOperand(1)));
 753         Record.push_back(CE->getPredicate());
 754         break;
 755       }
 756     } else {
 757       llvm_unreachable("Unknown constant!");
 758     }
 759     Stream.EmitRecord(Code, Record, AbbrevToUse);
 760     Record.clear();
 761   }
 762
 763   Stream.ExitBlock();
 764 }
 765
 766 static void WriteModuleConstants(const ValueEnumerator &VE,
 767                                  BitstreamWriter &Stream) {
 768   const ValueEnumerator::ValueList &Vals = VE.getValues();
 769
 770   // Find the first constant to emit, which is the first non-globalvalue value.
 771   // We know globalvalues have been emitted by WriteModuleInfo.
 772   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 773     if (!isa<GlobalValue>(Vals[i].first)) {
 774       WriteConstants(i, Vals.size(), VE, Stream, true);
 775       return;
 776     }
 777   }
 778 }
 779
 780 /// PushValueAndType - The file has to encode both the value and type id for
 781 /// many values, because we need to know what type to create for forward
 782 /// references.  However, most operands are not forward references, so this type
 783 /// field is not needed.
 784 ///
 785 /// This function adds V's value ID to Vals.  If the value ID is higher than the
 786 /// instruction ID, then it is a forward reference, and it also includes the
 787 /// type ID.
 788 static bool PushValueAndType(const Value *V, unsigned InstID,
 789                              SmallVector<unsigned, 64> &Vals,
 790                              ValueEnumerator &VE) {
 791   unsigned ValID = VE.getValueID(V);
 792   Vals.push_back(ValID);
 793   if (ValID >= InstID) {
 794     Vals.push_back(VE.getTypeID(V->getType()));
 795     return true;
 796   }
 797   return false;
 798 }
 799
 800 /// WriteInstruction - Emit an instruction to the specified stream.
 801 static void WriteInstruction(const Instruction &I, unsigned InstID,
 802                              ValueEnumerator &VE, BitstreamWriter &Stream,
 803                              SmallVector<unsigned, 64> &Vals) {
 804   unsigned Code = 0;
 805   unsigned AbbrevToUse = 0;
 806   switch (I.getOpcode()) {
 807   default:
 808     if (Instruction::isCast(I.getOpcode())) {
 809       Code = bitc::FUNC_CODE_INST_CAST;
 810       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 811         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
 812       Vals.push_back(VE.getTypeID(I.getType()));
 813       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
 814     } else {
 815       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
 816       Code = bitc::FUNC_CODE_INST_BINOP;
 817       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 818         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
 819       Vals.push_back(VE.getValueID(I.getOperand(1)));
 820       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
 821       uint64_t Flags = GetOptimizationFlags(&I);
 822       if (Flags != 0) {
 823         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
 824           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
 825         Vals.push_back(Flags);
 826       }
 827     }
 828     break;
 829
 830   case Instruction::GetElementPtr:
 831     Code = bitc::FUNC_CODE_INST_GEP;
 832     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 833       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 834     break;
 835   case Instruction::ExtractValue: {
 836     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
 837     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 838     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
 839     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
 840       Vals.push_back(*i);
 841     break;
 842   }
 843   case Instruction::InsertValue: {
 844     Code = bitc::FUNC_CODE_INST_INSERTVAL;
 845     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 846     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 847     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
 848     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
 849       Vals.push_back(*i);
 850     break;
 851   }
 852   case Instruction::Select:
 853     Code = bitc::FUNC_CODE_INST_VSELECT;
 854     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 855     Vals.push_back(VE.getValueID(I.getOperand(2)));
 856     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 857     break;
 858   case Instruction::ExtractElement:
 859     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
 860     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 861     Vals.push_back(VE.getValueID(I.getOperand(1)));
 862     break;
 863   case Instruction::InsertElement:
 864     Code = bitc::FUNC_CODE_INST_INSERTELT;
 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::ShuffleVector:
 870     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
 871     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 872     Vals.push_back(VE.getValueID(I.getOperand(1)));
 873     Vals.push_back(VE.getValueID(I.getOperand(2)));
 874     break;
 875   case Instruction::ICmp:
 876   case Instruction::FCmp:
 877     // compare returning Int1Ty or vector of Int1Ty
 878     Code = bitc::FUNC_CODE_INST_CMP2;
 879     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 880     Vals.push_back(VE.getValueID(I.getOperand(1)));
 881     Vals.push_back(cast<CmpInst>(I).getPredicate());
 882     break;
 883
 884   case Instruction::Ret:
 885     {
 886       Code = bitc::FUNC_CODE_INST_RET;
 887       unsigned NumOperands = I.getNumOperands();
 888       if (NumOperands == 0)
 889         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
 890       else if (NumOperands == 1) {
 891         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 892           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
 893       } else {
 894         for (unsigned i = 0, e = NumOperands; i != e; ++i)
 895           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 896       }
 897     }
 898     break;
 899   case Instruction::Br:
 900     {
 901       Code = bitc::FUNC_CODE_INST_BR;
 902       BranchInst &II(cast<BranchInst>(I));
 903       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
 904       if (II.isConditional()) {
 905         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
 906         Vals.push_back(VE.getValueID(II.getCondition()));
 907       }
 908     }
 909     break;
 910   case Instruction::Switch:
 911     Code = bitc::FUNC_CODE_INST_SWITCH;
 912     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
 913     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 914       Vals.push_back(VE.getValueID(I.getOperand(i)));
 915     break;
 916   case Instruction::Invoke: {
 917     const InvokeInst *II = cast<InvokeInst>(&I);
 918     const Value *Callee(II->getCalledValue());
 919     const PointerType *PTy = cast<PointerType>(Callee->getType());
 920     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 921     Code = bitc::FUNC_CODE_INST_INVOKE;
 922
 923     Vals.push_back(VE.getAttributeID(II->getAttributes()));
 924     Vals.push_back(II->getCallingConv());
 925     Vals.push_back(VE.getValueID(II->getNormalDest()));
 926     Vals.push_back(VE.getValueID(II->getUnwindDest()));
 927     PushValueAndType(Callee, InstID, Vals, VE);
 928
 929     // Emit value #'s for the fixed parameters.
 930     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 931       Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
 932
 933     // Emit type/value pairs for varargs params.
 934     if (FTy->isVarArg()) {
 935       for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
 936            i != e; ++i)
 937         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
 938     }
 939     break;
 940   }
 941   case Instruction::Unwind:
 942     Code = bitc::FUNC_CODE_INST_UNWIND;
 943     break;
 944   case Instruction::Unreachable:
 945     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
 946     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
 947     break;
 948
 949   case Instruction::PHI:
 950     Code = bitc::FUNC_CODE_INST_PHI;
 951     Vals.push_back(VE.getTypeID(I.getType()));
 952     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 953       Vals.push_back(VE.getValueID(I.getOperand(i)));
 954     break;
 955
 956   case Instruction::Malloc:
 957     Code = bitc::FUNC_CODE_INST_MALLOC;
 958     Vals.push_back(VE.getTypeID(I.getType()));
 959     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 960     Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
 961     break;
 962
 963   case Instruction::Free:
 964     Code = bitc::FUNC_CODE_INST_FREE;
 965     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 966     break;
 967
 968   case Instruction::Alloca:
 969     Code = bitc::FUNC_CODE_INST_ALLOCA;
 970     Vals.push_back(VE.getTypeID(I.getType()));
 971     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 972     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
 973     break;
 974
 975   case Instruction::Load:
 976     Code = bitc::FUNC_CODE_INST_LOAD;
 977     if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
 978       AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
 979
 980     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
 981     Vals.push_back(cast<LoadInst>(I).isVolatile());
 982     break;
 983   case Instruction::Store:
 984     Code = bitc::FUNC_CODE_INST_STORE2;
 985     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
 986     Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
 987     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
 988     Vals.push_back(cast<StoreInst>(I).isVolatile());
 989     break;
 990   case Instruction::Call: {
 991     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
 992     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 993
 994     Code = bitc::FUNC_CODE_INST_CALL;
 995
 996     const CallInst *CI = cast<CallInst>(&I);
 997     Vals.push_back(VE.getAttributeID(CI->getAttributes()));
 998     Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
 999     PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
1000
1001     // Emit value #'s for the fixed parameters.
1002     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1003       Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
1004
1005     // Emit type/value pairs for varargs params.
1006     if (FTy->isVarArg()) {
1007       unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1008       for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1009            i != e; ++i)
1010         PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1011     }
1012     break;
1013   }
1014   case Instruction::VAArg:
1015     Code = bitc::FUNC_CODE_INST_VAARG;
1016     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1017     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1018     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1019     break;
1020   }
1021
1022   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1023   Vals.clear();
1024 }
1025
1026 // Emit names for globals/functions etc.
1027 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1028                                   const ValueEnumerator &VE,
1029                                   BitstreamWriter &Stream) {
1030   if (VST.empty()) return;
1031   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1032
1033   // FIXME: Set up the abbrev, we know how many values there are!
1034   // FIXME: We know if the type names can use 7-bit ascii.
1035   SmallVector<unsigned, 64> NameVals;
1036
1037   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1038        SI != SE; ++SI) {
1039
1040     const ValueName &Name = *SI;
1041
1042     // Figure out the encoding to use for the name.
1043     bool is7Bit = true;
1044     bool isChar6 = true;
1045     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1046          C != E; ++C) {
1047       if (isChar6)
1048         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1049       if ((unsigned char)*C & 128) {
1050         is7Bit = false;
1051         break;  // don't bother scanning the rest.
1052       }
1053     }
1054
1055     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1056
1057     // VST_ENTRY:   [valueid, namechar x N]
1058     // VST_BBENTRY: [bbid, namechar x N]
1059     unsigned Code;
1060     if (isa<BasicBlock>(SI->getValue())) {
1061       Code = bitc::VST_CODE_BBENTRY;
1062       if (isChar6)
1063         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1064     } else {
1065       Code = bitc::VST_CODE_ENTRY;
1066       if (isChar6)
1067         AbbrevToUse = VST_ENTRY_6_ABBREV;
1068       else if (is7Bit)
1069         AbbrevToUse = VST_ENTRY_7_ABBREV;
1070     }
1071
1072     NameVals.push_back(VE.getValueID(SI->getValue()));
1073     for (const char *P = Name.getKeyData(),
1074          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1075       NameVals.push_back((unsigned char)*P);
1076
1077     // Emit the finished record.
1078     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1079     NameVals.clear();
1080   }
1081   Stream.ExitBlock();
1082 }
1083
1084 /// WriteFunction - Emit a function body to the module stream.
1085 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1086                           BitstreamWriter &Stream) {
1087   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1088   VE.incorporateFunction(F);
1089
1090   SmallVector<unsigned, 64> Vals;
1091
1092   // Emit the number of basic blocks, so the reader can create them ahead of
1093   // time.
1094   Vals.push_back(VE.getBasicBlocks().size());
1095   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1096   Vals.clear();
1097
1098   // If there are function-local constants, emit them now.
1099   unsigned CstStart, CstEnd;
1100   VE.getFunctionConstantRange(CstStart, CstEnd);
1101   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1102
1103   // Keep a running idea of what the instruction ID is.
1104   unsigned InstID = CstEnd;
1105
1106   // Finally, emit all the instructions, in order.
1107   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1108     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1109          I != E; ++I) {
1110       WriteInstruction(*I, InstID, VE, Stream, Vals);
1111       if (I->getType() != Type::VoidTy)
1112         ++InstID;
1113     }
1114
1115   // Emit names for all the instructions etc.
1116   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1117
1118   VE.purgeFunction();
1119   Stream.ExitBlock();
1120 }
1121
1122 /// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1123 static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1124                                  const ValueEnumerator &VE,
1125                                  BitstreamWriter &Stream) {
1126   if (TST.empty()) return;
1127
1128   Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1129
1130   // 7-bit fixed width VST_CODE_ENTRY strings.
1131   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1132   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1133   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1134                             Log2_32_Ceil(VE.getTypes().size()+1)));
1135   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1136   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1137   unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1138
1139   SmallVector<unsigned, 64> NameVals;
1140
1141   for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1142        TI != TE; ++TI) {
1143     // TST_ENTRY: [typeid, namechar x N]
1144     NameVals.push_back(VE.getTypeID(TI->second));
1145
1146     const std::string &Str = TI->first;
1147     bool is7Bit = true;
1148     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1149       NameVals.push_back((unsigned char)Str[i]);
1150       if (Str[i] & 128)
1151         is7Bit = false;
1152     }
1153
1154     // Emit the finished record.
1155     Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1156     NameVals.clear();
1157   }
1158
1159   Stream.ExitBlock();
1160 }
1161
1162 // Emit blockinfo, which defines the standard abbreviations etc.
1163 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1164   // We only want to emit block info records for blocks that have multiple
1165   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1166   // blocks can defined their abbrevs inline.
1167   Stream.EnterBlockInfoBlock(2);
1168
1169   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1170     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1171     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1173     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1175     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1176                                    Abbv) != VST_ENTRY_8_ABBREV)
1177       llvm_unreachable("Unexpected abbrev ordering!");
1178   }
1179
1180   { // 7-bit fixed width VST_ENTRY strings.
1181     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1182     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1183     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1184     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1185     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1186     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1187                                    Abbv) != VST_ENTRY_7_ABBREV)
1188       llvm_unreachable("Unexpected abbrev ordering!");
1189   }
1190   { // 6-bit char6 VST_ENTRY strings.
1191     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1192     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1193     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1194     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1195     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1196     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1197                                    Abbv) != VST_ENTRY_6_ABBREV)
1198       llvm_unreachable("Unexpected abbrev ordering!");
1199   }
1200   { // 6-bit char6 VST_BBENTRY strings.
1201     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1202     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1203     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1204     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1205     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1206     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1207                                    Abbv) != VST_BBENTRY_6_ABBREV)
1208       llvm_unreachable("Unexpected abbrev ordering!");
1209   }
1210
1211
1212
1213   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1214     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1215     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1216     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1217                               Log2_32_Ceil(VE.getTypes().size()+1)));
1218     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1219                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1220       llvm_unreachable("Unexpected abbrev ordering!");
1221   }
1222
1223   { // INTEGER abbrev for CONSTANTS_BLOCK.
1224     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1225     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1226     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1227     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1228                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1229       llvm_unreachable("Unexpected abbrev ordering!");
1230   }
1231
1232   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1233     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1234     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1235     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1236     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1237                               Log2_32_Ceil(VE.getTypes().size()+1)));
1238     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1239
1240     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1241                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1242       llvm_unreachable("Unexpected abbrev ordering!");
1243   }
1244   { // NULL abbrev for CONSTANTS_BLOCK.
1245     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1246     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1247     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1248                                    Abbv) != CONSTANTS_NULL_Abbrev)
1249       llvm_unreachable("Unexpected abbrev ordering!");
1250   }
1251
1252   // FIXME: This should only use space for first class types!
1253
1254   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1255     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1256     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1257     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1258     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1259     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1260     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1261                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1262       llvm_unreachable("Unexpected abbrev ordering!");
1263   }
1264   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1265     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1266     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1267     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1268     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1269     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1270     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1271                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1272       llvm_unreachable("Unexpected abbrev ordering!");
1273   }
1274   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1275     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1276     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1277     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1278     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1279     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1280     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1281     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1282                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1283       llvm_unreachable("Unexpected abbrev ordering!");
1284   }
1285   { // INST_CAST abbrev for FUNCTION_BLOCK.
1286     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1287     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1288     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1289     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1290                               Log2_32_Ceil(VE.getTypes().size()+1)));
1291     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1292     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1293                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1294       llvm_unreachable("Unexpected abbrev ordering!");
1295   }
1296
1297   { // INST_RET abbrev for FUNCTION_BLOCK.
1298     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1299     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1300     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1301                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1302       llvm_unreachable("Unexpected abbrev ordering!");
1303   }
1304   { // INST_RET abbrev for FUNCTION_BLOCK.
1305     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1306     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1307     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1308     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1309                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1310       llvm_unreachable("Unexpected abbrev ordering!");
1311   }
1312   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1313     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1314     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1315     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1316                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1317       llvm_unreachable("Unexpected abbrev ordering!");
1318   }
1319
1320   Stream.ExitBlock();
1321 }
1322
1323
1324 /// WriteModule - Emit the specified module to the bitstream.
1325 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1326   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1327
1328   // Emit the version number if it is non-zero.
1329   if (CurVersion) {
1330     SmallVector<unsigned, 1> Vals;
1331     Vals.push_back(CurVersion);
1332     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1333   }
1334
1335   // Analyze the module, enumerating globals, functions, etc.
1336   ValueEnumerator VE(M);
1337
1338   // Emit blockinfo, which defines the standard abbreviations etc.
1339   WriteBlockInfo(VE, Stream);
1340
1341   // Emit information about parameter attributes.
1342   WriteAttributeTable(VE, Stream);
1343
1344   // Emit information describing all of the types in the module.
1345   WriteTypeTable(VE, Stream);
1346
1347   // Emit top-level description of module, including target triple, inline asm,
1348   // descriptors for global variables, and function prototype info.
1349   WriteModuleInfo(M, VE, Stream);
1350
1351   // Emit constants.
1352   WriteModuleConstants(VE, Stream);
1353
1354   // Emit metadata.
1355   WriteModuleMetadata(VE, Stream);
1356
1357   // Emit function bodies.
1358   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1359     if (!I->isDeclaration())
1360       WriteFunction(*I, VE, Stream);
1361
1362   // Emit the type symbol table information.
1363   WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1364
1365   // Emit names for globals/functions etc.
1366   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1367
1368   Stream.ExitBlock();
1369 }
1370
1371 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1372 /// header and trailer to make it compatible with the system archiver.  To do
1373 /// this we emit the following header, and then emit a trailer that pads the
1374 /// file out to be a multiple of 16 bytes.
1375 ///
1376 /// struct bc_header {
1377 ///   uint32_t Magic;         // 0x0B17C0DE
1378 ///   uint32_t Version;       // Version, currently always 0.
1379 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1380 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1381 ///   uint32_t CPUType;       // CPU specifier.
1382 ///   ... potentially more later ...
1383 /// };
1384 enum {
1385   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1386   DarwinBCHeaderSize = 5*4
1387 };
1388
1389 static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1390                                const std::string &TT) {
1391   unsigned CPUType = ~0U;
1392
1393   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1394   // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1395   // specific constants here because they are implicitly part of the Darwin ABI.
1396   enum {
1397     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1398     DARWIN_CPU_TYPE_X86        = 7,
1399     DARWIN_CPU_TYPE_POWERPC    = 18
1400   };
1401
1402   if (TT.find("x86_64-") == 0)
1403     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1404   else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1405            TT[4] == '-' && TT[1] - '3' < 6)
1406     CPUType = DARWIN_CPU_TYPE_X86;
1407   else if (TT.find("powerpc-") == 0)
1408     CPUType = DARWIN_CPU_TYPE_POWERPC;
1409   else if (TT.find("powerpc64-") == 0)
1410     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1411
1412   // Traditional Bitcode starts after header.
1413   unsigned BCOffset = DarwinBCHeaderSize;
1414
1415   Stream.Emit(0x0B17C0DE, 32);
1416   Stream.Emit(0         , 32);  // Version.
1417   Stream.Emit(BCOffset  , 32);
1418   Stream.Emit(0         , 32);  // Filled in later.
1419   Stream.Emit(CPUType   , 32);
1420 }
1421
1422 /// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1423 /// finalize the header.
1424 static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1425   // Update the size field in the header.
1426   Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1427
1428   // If the file is not a multiple of 16 bytes, insert dummy padding.
1429   while (BufferSize & 15) {
1430     Stream.Emit(0, 8);
1431     ++BufferSize;
1432   }
1433 }
1434
1435
1436 /// WriteBitcodeToFile - Write the specified module to the specified output
1437 /// stream.
1438 void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1439   raw_os_ostream RawOut(Out);
1440   // If writing to stdout, set binary mode.
1441   if (llvm::cout == Out)
1442     sys::Program::ChangeStdoutToBinary();
1443   WriteBitcodeToFile(M, RawOut);
1444 }
1445
1446 /// WriteBitcodeToFile - Write the specified module to the specified output
1447 /// stream.
1448 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1449   std::vector<unsigned char> Buffer;
1450   BitstreamWriter Stream(Buffer);
1451
1452   Buffer.reserve(256*1024);
1453
1454   WriteBitcodeToStream( M, Stream );
1455
1456   // If writing to stdout, set binary mode.
1457   if (&llvm::outs() == &Out)
1458     sys::Program::ChangeStdoutToBinary();
1459
1460   // Write the generated bitstream to "Out".
1461   Out.write((char*)&Buffer.front(), Buffer.size());
1462
1463   // Make sure it hits disk now.
1464   Out.flush();
1465 }
1466
1467 /// WriteBitcodeToStream - Write the specified module to the specified output
1468 /// stream.
1469 void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1470   // If this is darwin, emit a file header and trailer if needed.
1471   bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1472   if (isDarwin)
1473     EmitDarwinBCHeader(Stream, M->getTargetTriple());
1474
1475   // Emit the file header.
1476   Stream.Emit((unsigned)'B', 8);
1477   Stream.Emit((unsigned)'C', 8);
1478   Stream.Emit(0x0, 4);
1479   Stream.Emit(0xC, 4);
1480   Stream.Emit(0xE, 4);
1481   Stream.Emit(0xD, 4);
1482
1483   // Emit the module.
1484   WriteModule(M, Stream);
1485
1486   if (isDarwin)
1487     EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1488 }