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/Metadata.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 WriteMDNode(const MDNode *N,
 477                         const ValueEnumerator &VE,
 478                         BitstreamWriter &Stream,
 479                         SmallVector<uint64_t, 64> &Record) {
 480   for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
 481     if (N->getElement(i)) {
 482       Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
 483       Record.push_back(VE.getValueID(N->getElement(i)));
 484     } else {
 485       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 486       Record.push_back(0);
 487     }
 488   }
 489   Stream.EmitRecord(bitc::METADATA_NODE, Record, 0);
 490   Record.clear();
 491 }
 492
 493 static void WriteModuleMetadata(const ValueEnumerator &VE,
 494                                 BitstreamWriter &Stream) {
 495   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 496   bool StartedMetadataBlock = false;
 497   unsigned MDSAbbrev = 0;
 498   SmallVector<uint64_t, 64> Record;
 499   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 500
 501     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 502       if (!StartedMetadataBlock) {
 503         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 504         StartedMetadataBlock = true;
 505       }
 506       WriteMDNode(N, VE, Stream, Record);
 507     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 508       if (!StartedMetadataBlock)  {
 509         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 510
 511         // Abbrev for METADATA_STRING.
 512         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 513         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 514         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 515         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 516         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 517         StartedMetadataBlock = true;
 518       }
 519
 520       // Code: [strchar x N]
 521       const char *StrBegin = MDS->begin();
 522       for (unsigned i = 0, e = MDS->length(); i != e; ++i)
 523         Record.push_back(StrBegin[i]);
 524
 525       // Emit the finished record.
 526       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 527       Record.clear();
 528     } else if (const NamedMDNode *NMD = dyn_cast<NamedMDNode>(Vals[i].first)) {
 529       if (!StartedMetadataBlock)  {
 530         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 531         StartedMetadataBlock = true;
 532       }
 533
 534       // Write name.
 535       std::string Str = NMD->getNameStr();
 536       const char *StrBegin = Str.c_str();
 537       for (unsigned i = 0, e = Str.length(); i != e; ++i)
 538         Record.push_back(StrBegin[i]);
 539       Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 540       Record.clear();
 541
 542       // Write named metadata elements.
 543       for (unsigned i = 0, e = NMD->getNumElements(); i != e; ++i) {
 544         if (NMD->getElement(i))
 545           Record.push_back(VE.getValueID(NMD->getElement(i)));
 546         else
 547           Record.push_back(0);
 548       }
 549       Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 550       Record.clear();
 551     }
 552   }
 553
 554   if (StartedMetadataBlock)
 555     Stream.ExitBlock();
 556 }
 557
 558 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 559                            const ValueEnumerator &VE,
 560                            BitstreamWriter &Stream, bool isGlobal) {
 561   if (FirstVal == LastVal) return;
 562
 563   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 564
 565   unsigned AggregateAbbrev = 0;
 566   unsigned String8Abbrev = 0;
 567   unsigned CString7Abbrev = 0;
 568   unsigned CString6Abbrev = 0;
 569   // If this is a constant pool for the module, emit module-specific abbrevs.
 570   if (isGlobal) {
 571     // Abbrev for CST_CODE_AGGREGATE.
 572     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 573     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 574     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 575     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 576     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 577
 578     // Abbrev for CST_CODE_STRING.
 579     Abbv = new BitCodeAbbrev();
 580     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 581     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 582     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 583     String8Abbrev = Stream.EmitAbbrev(Abbv);
 584     // Abbrev for CST_CODE_CSTRING.
 585     Abbv = new BitCodeAbbrev();
 586     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 587     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 588     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 589     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 590     // Abbrev for CST_CODE_CSTRING.
 591     Abbv = new BitCodeAbbrev();
 592     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 593     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 594     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 595     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 596   }
 597
 598   SmallVector<uint64_t, 64> Record;
 599
 600   const ValueEnumerator::ValueList &Vals = VE.getValues();
 601   const Type *LastTy = 0;
 602   for (unsigned i = FirstVal; i != LastVal; ++i) {
 603     const Value *V = Vals[i].first;
 604     // If we need to switch types, do so now.
 605     if (V->getType() != LastTy) {
 606       LastTy = V->getType();
 607       Record.push_back(VE.getTypeID(LastTy));
 608       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 609                         CONSTANTS_SETTYPE_ABBREV);
 610       Record.clear();
 611     }
 612
 613     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 614       Record.push_back(unsigned(IA->hasSideEffects()));
 615
 616       // Add the asm string.
 617       const std::string &AsmStr = IA->getAsmString();
 618       Record.push_back(AsmStr.size());
 619       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 620         Record.push_back(AsmStr[i]);
 621
 622       // Add the constraint string.
 623       const std::string &ConstraintStr = IA->getConstraintString();
 624       Record.push_back(ConstraintStr.size());
 625       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 626         Record.push_back(ConstraintStr[i]);
 627       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 628       Record.clear();
 629       continue;
 630     }
 631     const Constant *C = cast<Constant>(V);
 632     unsigned Code = -1U;
 633     unsigned AbbrevToUse = 0;
 634     if (C->isNullValue()) {
 635       Code = bitc::CST_CODE_NULL;
 636     } else if (isa<UndefValue>(C)) {
 637       Code = bitc::CST_CODE_UNDEF;
 638     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 639       if (IV->getBitWidth() <= 64) {
 640         int64_t V = IV->getSExtValue();
 641         if (V >= 0)
 642           Record.push_back(V << 1);
 643         else
 644           Record.push_back((-V << 1) | 1);
 645         Code = bitc::CST_CODE_INTEGER;
 646         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 647       } else {                             // Wide integers, > 64 bits in size.
 648         // We have an arbitrary precision integer value to write whose
 649         // bit width is > 64. However, in canonical unsigned integer
 650         // format it is likely that the high bits are going to be zero.
 651         // So, we only write the number of active words.
 652         unsigned NWords = IV->getValue().getActiveWords();
 653         const uint64_t *RawWords = IV->getValue().getRawData();
 654         for (unsigned i = 0; i != NWords; ++i) {
 655           int64_t V = RawWords[i];
 656           if (V >= 0)
 657             Record.push_back(V << 1);
 658           else
 659             Record.push_back((-V << 1) | 1);
 660         }
 661         Code = bitc::CST_CODE_WIDE_INTEGER;
 662       }
 663     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 664       Code = bitc::CST_CODE_FLOAT;
 665       const Type *Ty = CFP->getType();
 666       if (Ty == Type::getFloatTy(Ty->getContext()) ||
 667           Ty == Type::getDoubleTy(Ty->getContext())) {
 668         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 669       } else if (Ty == Type::getX86_FP80Ty(Ty->getContext())) {
 670         // api needed to prevent premature destruction
 671         // bits are not in the same order as a normal i80 APInt, compensate.
 672         APInt api = CFP->getValueAPF().bitcastToAPInt();
 673         const uint64_t *p = api.getRawData();
 674         Record.push_back((p[1] << 48) | (p[0] >> 16));
 675         Record.push_back(p[0] & 0xffffLL);
 676       } else if (Ty == Type::getFP128Ty(Ty->getContext()) ||
 677                  Ty == Type::getPPC_FP128Ty(Ty->getContext())) {
 678         APInt api = CFP->getValueAPF().bitcastToAPInt();
 679         const uint64_t *p = api.getRawData();
 680         Record.push_back(p[0]);
 681         Record.push_back(p[1]);
 682       } else {
 683         assert (0 && "Unknown FP type!");
 684       }
 685     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 686       // Emit constant strings specially.
 687       unsigned NumOps = C->getNumOperands();
 688       // If this is a null-terminated string, use the denser CSTRING encoding.
 689       if (C->getOperand(NumOps-1)->isNullValue()) {
 690         Code = bitc::CST_CODE_CSTRING;
 691         --NumOps;  // Don't encode the null, which isn't allowed by char6.
 692       } else {
 693         Code = bitc::CST_CODE_STRING;
 694         AbbrevToUse = String8Abbrev;
 695       }
 696       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 697       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 698       for (unsigned i = 0; i != NumOps; ++i) {
 699         unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
 700         Record.push_back(V);
 701         isCStr7 &= (V & 128) == 0;
 702         if (isCStrChar6)
 703           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 704       }
 705
 706       if (isCStrChar6)
 707         AbbrevToUse = CString6Abbrev;
 708       else if (isCStr7)
 709         AbbrevToUse = CString7Abbrev;
 710     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
 711                isa<ConstantVector>(V)) {
 712       Code = bitc::CST_CODE_AGGREGATE;
 713       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 714         Record.push_back(VE.getValueID(C->getOperand(i)));
 715       AbbrevToUse = AggregateAbbrev;
 716     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 717       switch (CE->getOpcode()) {
 718       default:
 719         if (Instruction::isCast(CE->getOpcode())) {
 720           Code = bitc::CST_CODE_CE_CAST;
 721           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 722           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 723           Record.push_back(VE.getValueID(C->getOperand(0)));
 724           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 725         } else {
 726           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 727           Code = bitc::CST_CODE_CE_BINOP;
 728           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 729           Record.push_back(VE.getValueID(C->getOperand(0)));
 730           Record.push_back(VE.getValueID(C->getOperand(1)));
 731           uint64_t Flags = GetOptimizationFlags(CE);
 732           if (Flags != 0)
 733             Record.push_back(Flags);
 734         }
 735         break;
 736       case Instruction::GetElementPtr:
 737         Code = bitc::CST_CODE_CE_GEP;
 738         if (cast<GEPOperator>(C)->isInBounds())
 739           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
 740         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 741           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 742           Record.push_back(VE.getValueID(C->getOperand(i)));
 743         }
 744         break;
 745       case Instruction::Select:
 746         Code = bitc::CST_CODE_CE_SELECT;
 747         Record.push_back(VE.getValueID(C->getOperand(0)));
 748         Record.push_back(VE.getValueID(C->getOperand(1)));
 749         Record.push_back(VE.getValueID(C->getOperand(2)));
 750         break;
 751       case Instruction::ExtractElement:
 752         Code = bitc::CST_CODE_CE_EXTRACTELT;
 753         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 754         Record.push_back(VE.getValueID(C->getOperand(0)));
 755         Record.push_back(VE.getValueID(C->getOperand(1)));
 756         break;
 757       case Instruction::InsertElement:
 758         Code = bitc::CST_CODE_CE_INSERTELT;
 759         Record.push_back(VE.getValueID(C->getOperand(0)));
 760         Record.push_back(VE.getValueID(C->getOperand(1)));
 761         Record.push_back(VE.getValueID(C->getOperand(2)));
 762         break;
 763       case Instruction::ShuffleVector:
 764         // If the return type and argument types are the same, this is a
 765         // standard shufflevector instruction.  If the types are different,
 766         // then the shuffle is widening or truncating the input vectors, and
 767         // the argument type must also be encoded.
 768         if (C->getType() == C->getOperand(0)->getType()) {
 769           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 770         } else {
 771           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 772           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 773         }
 774         Record.push_back(VE.getValueID(C->getOperand(0)));
 775         Record.push_back(VE.getValueID(C->getOperand(1)));
 776         Record.push_back(VE.getValueID(C->getOperand(2)));
 777         break;
 778       case Instruction::ICmp:
 779       case Instruction::FCmp:
 780         Code = bitc::CST_CODE_CE_CMP;
 781         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 782         Record.push_back(VE.getValueID(C->getOperand(0)));
 783         Record.push_back(VE.getValueID(C->getOperand(1)));
 784         Record.push_back(CE->getPredicate());
 785         break;
 786       }
 787     } else {
 788       llvm_unreachable("Unknown constant!");
 789     }
 790     Stream.EmitRecord(Code, Record, AbbrevToUse);
 791     Record.clear();
 792   }
 793
 794   Stream.ExitBlock();
 795 }
 796
 797 static void WriteModuleConstants(const ValueEnumerator &VE,
 798                                  BitstreamWriter &Stream) {
 799   const ValueEnumerator::ValueList &Vals = VE.getValues();
 800
 801   // Find the first constant to emit, which is the first non-globalvalue value.
 802   // We know globalvalues have been emitted by WriteModuleInfo.
 803   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 804     if (!isa<GlobalValue>(Vals[i].first)) {
 805       WriteConstants(i, Vals.size(), VE, Stream, true);
 806       return;
 807     }
 808   }
 809 }
 810
 811 /// PushValueAndType - The file has to encode both the value and type id for
 812 /// many values, because we need to know what type to create for forward
 813 /// references.  However, most operands are not forward references, so this type
 814 /// field is not needed.
 815 ///
 816 /// This function adds V's value ID to Vals.  If the value ID is higher than the
 817 /// instruction ID, then it is a forward reference, and it also includes the
 818 /// type ID.
 819 static bool PushValueAndType(const Value *V, unsigned InstID,
 820                              SmallVector<unsigned, 64> &Vals,
 821                              ValueEnumerator &VE) {
 822   unsigned ValID = VE.getValueID(V);
 823   Vals.push_back(ValID);
 824   if (ValID >= InstID) {
 825     Vals.push_back(VE.getTypeID(V->getType()));
 826     return true;
 827   }
 828   return false;
 829 }
 830
 831 /// WriteInstruction - Emit an instruction to the specified stream.
 832 static void WriteInstruction(const Instruction &I, unsigned InstID,
 833                              ValueEnumerator &VE, BitstreamWriter &Stream,
 834                              SmallVector<unsigned, 64> &Vals) {
 835   unsigned Code = 0;
 836   unsigned AbbrevToUse = 0;
 837   switch (I.getOpcode()) {
 838   default:
 839     if (Instruction::isCast(I.getOpcode())) {
 840       Code = bitc::FUNC_CODE_INST_CAST;
 841       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 842         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
 843       Vals.push_back(VE.getTypeID(I.getType()));
 844       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
 845     } else {
 846       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
 847       Code = bitc::FUNC_CODE_INST_BINOP;
 848       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 849         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
 850       Vals.push_back(VE.getValueID(I.getOperand(1)));
 851       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
 852       uint64_t Flags = GetOptimizationFlags(&I);
 853       if (Flags != 0) {
 854         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
 855           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
 856         Vals.push_back(Flags);
 857       }
 858     }
 859     break;
 860
 861   case Instruction::GetElementPtr:
 862     Code = bitc::FUNC_CODE_INST_GEP;
 863     if (cast<GEPOperator>(&I)->isInBounds())
 864       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
 865     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 866       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 867     break;
 868   case Instruction::ExtractValue: {
 869     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
 870     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 871     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
 872     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
 873       Vals.push_back(*i);
 874     break;
 875   }
 876   case Instruction::InsertValue: {
 877     Code = bitc::FUNC_CODE_INST_INSERTVAL;
 878     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 879     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 880     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
 881     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
 882       Vals.push_back(*i);
 883     break;
 884   }
 885   case Instruction::Select:
 886     Code = bitc::FUNC_CODE_INST_VSELECT;
 887     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 888     Vals.push_back(VE.getValueID(I.getOperand(2)));
 889     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 890     break;
 891   case Instruction::ExtractElement:
 892     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
 893     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 894     Vals.push_back(VE.getValueID(I.getOperand(1)));
 895     break;
 896   case Instruction::InsertElement:
 897     Code = bitc::FUNC_CODE_INST_INSERTELT;
 898     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 899     Vals.push_back(VE.getValueID(I.getOperand(1)));
 900     Vals.push_back(VE.getValueID(I.getOperand(2)));
 901     break;
 902   case Instruction::ShuffleVector:
 903     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
 904     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 905     Vals.push_back(VE.getValueID(I.getOperand(1)));
 906     Vals.push_back(VE.getValueID(I.getOperand(2)));
 907     break;
 908   case Instruction::ICmp:
 909   case Instruction::FCmp:
 910     // compare returning Int1Ty or vector of Int1Ty
 911     Code = bitc::FUNC_CODE_INST_CMP2;
 912     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 913     Vals.push_back(VE.getValueID(I.getOperand(1)));
 914     Vals.push_back(cast<CmpInst>(I).getPredicate());
 915     break;
 916
 917   case Instruction::Ret:
 918     {
 919       Code = bitc::FUNC_CODE_INST_RET;
 920       unsigned NumOperands = I.getNumOperands();
 921       if (NumOperands == 0)
 922         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
 923       else if (NumOperands == 1) {
 924         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 925           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
 926       } else {
 927         for (unsigned i = 0, e = NumOperands; i != e; ++i)
 928           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 929       }
 930     }
 931     break;
 932   case Instruction::Br:
 933     {
 934       Code = bitc::FUNC_CODE_INST_BR;
 935       BranchInst &II(cast<BranchInst>(I));
 936       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
 937       if (II.isConditional()) {
 938         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
 939         Vals.push_back(VE.getValueID(II.getCondition()));
 940       }
 941     }
 942     break;
 943   case Instruction::Switch:
 944     Code = bitc::FUNC_CODE_INST_SWITCH;
 945     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
 946     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 947       Vals.push_back(VE.getValueID(I.getOperand(i)));
 948     break;
 949   case Instruction::Invoke: {
 950     const InvokeInst *II = cast<InvokeInst>(&I);
 951     const Value *Callee(II->getCalledValue());
 952     const PointerType *PTy = cast<PointerType>(Callee->getType());
 953     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 954     Code = bitc::FUNC_CODE_INST_INVOKE;
 955
 956     Vals.push_back(VE.getAttributeID(II->getAttributes()));
 957     Vals.push_back(II->getCallingConv());
 958     Vals.push_back(VE.getValueID(II->getNormalDest()));
 959     Vals.push_back(VE.getValueID(II->getUnwindDest()));
 960     PushValueAndType(Callee, InstID, Vals, VE);
 961
 962     // Emit value #'s for the fixed parameters.
 963     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 964       Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
 965
 966     // Emit type/value pairs for varargs params.
 967     if (FTy->isVarArg()) {
 968       for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
 969            i != e; ++i)
 970         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
 971     }
 972     break;
 973   }
 974   case Instruction::Unwind:
 975     Code = bitc::FUNC_CODE_INST_UNWIND;
 976     break;
 977   case Instruction::Unreachable:
 978     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
 979     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
 980     break;
 981
 982   case Instruction::PHI:
 983     Code = bitc::FUNC_CODE_INST_PHI;
 984     Vals.push_back(VE.getTypeID(I.getType()));
 985     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 986       Vals.push_back(VE.getValueID(I.getOperand(i)));
 987     break;
 988
 989   case Instruction::Malloc:
 990     Code = bitc::FUNC_CODE_INST_MALLOC;
 991     Vals.push_back(VE.getTypeID(I.getType()));
 992     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 993     Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
 994     break;
 995
 996   case Instruction::Free:
 997     Code = bitc::FUNC_CODE_INST_FREE;
 998     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 999     break;
1000
1001   case Instruction::Alloca:
1002     Code = bitc::FUNC_CODE_INST_ALLOCA;
1003     Vals.push_back(VE.getTypeID(I.getType()));
1004     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1005     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1006     break;
1007
1008   case Instruction::Load:
1009     Code = bitc::FUNC_CODE_INST_LOAD;
1010     if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1011       AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1012
1013     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1014     Vals.push_back(cast<LoadInst>(I).isVolatile());
1015     break;
1016   case Instruction::Store:
1017     Code = bitc::FUNC_CODE_INST_STORE2;
1018     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1019     Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
1020     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1021     Vals.push_back(cast<StoreInst>(I).isVolatile());
1022     break;
1023   case Instruction::Call: {
1024     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
1025     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1026
1027     Code = bitc::FUNC_CODE_INST_CALL;
1028
1029     const CallInst *CI = cast<CallInst>(&I);
1030     Vals.push_back(VE.getAttributeID(CI->getAttributes()));
1031     Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
1032     PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
1033
1034     // Emit value #'s for the fixed parameters.
1035     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1036       Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
1037
1038     // Emit type/value pairs for varargs params.
1039     if (FTy->isVarArg()) {
1040       unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1041       for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1042            i != e; ++i)
1043         PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1044     }
1045     break;
1046   }
1047   case Instruction::VAArg:
1048     Code = bitc::FUNC_CODE_INST_VAARG;
1049     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1050     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1051     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1052     break;
1053   }
1054
1055   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1056   Vals.clear();
1057 }
1058
1059 // Emit names for globals/functions etc.
1060 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1061                                   const ValueEnumerator &VE,
1062                                   BitstreamWriter &Stream) {
1063   if (VST.empty()) return;
1064   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1065
1066   // FIXME: Set up the abbrev, we know how many values there are!
1067   // FIXME: We know if the type names can use 7-bit ascii.
1068   SmallVector<unsigned, 64> NameVals;
1069
1070   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1071        SI != SE; ++SI) {
1072
1073     const ValueName &Name = *SI;
1074
1075     // Figure out the encoding to use for the name.
1076     bool is7Bit = true;
1077     bool isChar6 = true;
1078     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1079          C != E; ++C) {
1080       if (isChar6)
1081         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1082       if ((unsigned char)*C & 128) {
1083         is7Bit = false;
1084         break;  // don't bother scanning the rest.
1085       }
1086     }
1087
1088     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1089
1090     // VST_ENTRY:   [valueid, namechar x N]
1091     // VST_BBENTRY: [bbid, namechar x N]
1092     unsigned Code;
1093     if (isa<BasicBlock>(SI->getValue())) {
1094       Code = bitc::VST_CODE_BBENTRY;
1095       if (isChar6)
1096         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1097     } else {
1098       Code = bitc::VST_CODE_ENTRY;
1099       if (isChar6)
1100         AbbrevToUse = VST_ENTRY_6_ABBREV;
1101       else if (is7Bit)
1102         AbbrevToUse = VST_ENTRY_7_ABBREV;
1103     }
1104
1105     NameVals.push_back(VE.getValueID(SI->getValue()));
1106     for (const char *P = Name.getKeyData(),
1107          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1108       NameVals.push_back((unsigned char)*P);
1109
1110     // Emit the finished record.
1111     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1112     NameVals.clear();
1113   }
1114   Stream.ExitBlock();
1115 }
1116
1117 /// WriteFunction - Emit a function body to the module stream.
1118 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1119                           BitstreamWriter &Stream) {
1120   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1121   VE.incorporateFunction(F);
1122
1123   SmallVector<unsigned, 64> Vals;
1124
1125   // Emit the number of basic blocks, so the reader can create them ahead of
1126   // time.
1127   Vals.push_back(VE.getBasicBlocks().size());
1128   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1129   Vals.clear();
1130
1131   // If there are function-local constants, emit them now.
1132   unsigned CstStart, CstEnd;
1133   VE.getFunctionConstantRange(CstStart, CstEnd);
1134   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1135
1136   // Keep a running idea of what the instruction ID is.
1137   unsigned InstID = CstEnd;
1138
1139   // Finally, emit all the instructions, in order.
1140   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1141     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1142          I != E; ++I) {
1143       WriteInstruction(*I, InstID, VE, Stream, Vals);
1144       if (I->getType() != Type::getVoidTy(F.getContext()))
1145         ++InstID;
1146     }
1147
1148   // Emit names for all the instructions etc.
1149   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1150
1151   VE.purgeFunction();
1152   Stream.ExitBlock();
1153 }
1154
1155 /// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1156 static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1157                                  const ValueEnumerator &VE,
1158                                  BitstreamWriter &Stream) {
1159   if (TST.empty()) return;
1160
1161   Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1162
1163   // 7-bit fixed width VST_CODE_ENTRY strings.
1164   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1165   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1166   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1167                             Log2_32_Ceil(VE.getTypes().size()+1)));
1168   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1169   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1170   unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1171
1172   SmallVector<unsigned, 64> NameVals;
1173
1174   for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1175        TI != TE; ++TI) {
1176     // TST_ENTRY: [typeid, namechar x N]
1177     NameVals.push_back(VE.getTypeID(TI->second));
1178
1179     const std::string &Str = TI->first;
1180     bool is7Bit = true;
1181     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1182       NameVals.push_back((unsigned char)Str[i]);
1183       if (Str[i] & 128)
1184         is7Bit = false;
1185     }
1186
1187     // Emit the finished record.
1188     Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1189     NameVals.clear();
1190   }
1191
1192   Stream.ExitBlock();
1193 }
1194
1195 // Emit blockinfo, which defines the standard abbreviations etc.
1196 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1197   // We only want to emit block info records for blocks that have multiple
1198   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1199   // blocks can defined their abbrevs inline.
1200   Stream.EnterBlockInfoBlock(2);
1201
1202   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1203     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1204     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1205     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1206     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1207     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1208     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1209                                    Abbv) != VST_ENTRY_8_ABBREV)
1210       llvm_unreachable("Unexpected abbrev ordering!");
1211   }
1212
1213   { // 7-bit fixed width VST_ENTRY strings.
1214     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1215     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1216     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1217     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1218     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1219     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1220                                    Abbv) != VST_ENTRY_7_ABBREV)
1221       llvm_unreachable("Unexpected abbrev ordering!");
1222   }
1223   { // 6-bit char6 VST_ENTRY strings.
1224     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1225     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1226     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1227     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1228     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1229     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1230                                    Abbv) != VST_ENTRY_6_ABBREV)
1231       llvm_unreachable("Unexpected abbrev ordering!");
1232   }
1233   { // 6-bit char6 VST_BBENTRY strings.
1234     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1235     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1236     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1237     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1238     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1239     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1240                                    Abbv) != VST_BBENTRY_6_ABBREV)
1241       llvm_unreachable("Unexpected abbrev ordering!");
1242   }
1243
1244
1245
1246   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1247     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1248     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1249     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1250                               Log2_32_Ceil(VE.getTypes().size()+1)));
1251     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1252                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1253       llvm_unreachable("Unexpected abbrev ordering!");
1254   }
1255
1256   { // INTEGER abbrev for CONSTANTS_BLOCK.
1257     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1258     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1259     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1260     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1261                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1262       llvm_unreachable("Unexpected abbrev ordering!");
1263   }
1264
1265   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1266     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1267     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1268     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1269     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1270                               Log2_32_Ceil(VE.getTypes().size()+1)));
1271     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1272
1273     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1274                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1275       llvm_unreachable("Unexpected abbrev ordering!");
1276   }
1277   { // NULL abbrev for CONSTANTS_BLOCK.
1278     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1279     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1280     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1281                                    Abbv) != CONSTANTS_NULL_Abbrev)
1282       llvm_unreachable("Unexpected abbrev ordering!");
1283   }
1284
1285   // FIXME: This should only use space for first class types!
1286
1287   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1288     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1289     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1290     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1291     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1292     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1293     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1294                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1295       llvm_unreachable("Unexpected abbrev ordering!");
1296   }
1297   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1298     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1299     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1300     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1301     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1302     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1303     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1304                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1305       llvm_unreachable("Unexpected abbrev ordering!");
1306   }
1307   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1308     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1309     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1310     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1311     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1313     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1314     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1315                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1316       llvm_unreachable("Unexpected abbrev ordering!");
1317   }
1318   { // INST_CAST abbrev for FUNCTION_BLOCK.
1319     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1320     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1321     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1322     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1323                               Log2_32_Ceil(VE.getTypes().size()+1)));
1324     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1325     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1326                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1327       llvm_unreachable("Unexpected abbrev ordering!");
1328   }
1329
1330   { // INST_RET abbrev for FUNCTION_BLOCK.
1331     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1332     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1333     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1334                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1335       llvm_unreachable("Unexpected abbrev ordering!");
1336   }
1337   { // INST_RET abbrev for FUNCTION_BLOCK.
1338     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1339     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1340     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1341     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1342                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1343       llvm_unreachable("Unexpected abbrev ordering!");
1344   }
1345   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1346     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1347     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1348     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1349                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1350       llvm_unreachable("Unexpected abbrev ordering!");
1351   }
1352
1353   Stream.ExitBlock();
1354 }
1355
1356
1357 /// WriteModule - Emit the specified module to the bitstream.
1358 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1359   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1360
1361   // Emit the version number if it is non-zero.
1362   if (CurVersion) {
1363     SmallVector<unsigned, 1> Vals;
1364     Vals.push_back(CurVersion);
1365     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1366   }
1367
1368   // Analyze the module, enumerating globals, functions, etc.
1369   ValueEnumerator VE(M);
1370
1371   // Emit blockinfo, which defines the standard abbreviations etc.
1372   WriteBlockInfo(VE, Stream);
1373
1374   // Emit information about parameter attributes.
1375   WriteAttributeTable(VE, Stream);
1376
1377   // Emit information describing all of the types in the module.
1378   WriteTypeTable(VE, Stream);
1379
1380   // Emit top-level description of module, including target triple, inline asm,
1381   // descriptors for global variables, and function prototype info.
1382   WriteModuleInfo(M, VE, Stream);
1383
1384   // Emit constants.
1385   WriteModuleConstants(VE, Stream);
1386
1387   // Emit metadata.
1388   WriteModuleMetadata(VE, Stream);
1389
1390   // Emit function bodies.
1391   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1392     if (!I->isDeclaration())
1393       WriteFunction(*I, VE, Stream);
1394
1395   // Emit the type symbol table information.
1396   WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1397
1398   // Emit names for globals/functions etc.
1399   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1400
1401   Stream.ExitBlock();
1402 }
1403
1404 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1405 /// header and trailer to make it compatible with the system archiver.  To do
1406 /// this we emit the following header, and then emit a trailer that pads the
1407 /// file out to be a multiple of 16 bytes.
1408 ///
1409 /// struct bc_header {
1410 ///   uint32_t Magic;         // 0x0B17C0DE
1411 ///   uint32_t Version;       // Version, currently always 0.
1412 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1413 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1414 ///   uint32_t CPUType;       // CPU specifier.
1415 ///   ... potentially more later ...
1416 /// };
1417 enum {
1418   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1419   DarwinBCHeaderSize = 5*4
1420 };
1421
1422 static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1423                                const std::string &TT) {
1424   unsigned CPUType = ~0U;
1425
1426   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1427   // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1428   // specific constants here because they are implicitly part of the Darwin ABI.
1429   enum {
1430     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1431     DARWIN_CPU_TYPE_X86        = 7,
1432     DARWIN_CPU_TYPE_POWERPC    = 18
1433   };
1434
1435   if (TT.find("x86_64-") == 0)
1436     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1437   else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1438            TT[4] == '-' && TT[1] - '3' < 6)
1439     CPUType = DARWIN_CPU_TYPE_X86;
1440   else if (TT.find("powerpc-") == 0)
1441     CPUType = DARWIN_CPU_TYPE_POWERPC;
1442   else if (TT.find("powerpc64-") == 0)
1443     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1444
1445   // Traditional Bitcode starts after header.
1446   unsigned BCOffset = DarwinBCHeaderSize;
1447
1448   Stream.Emit(0x0B17C0DE, 32);
1449   Stream.Emit(0         , 32);  // Version.
1450   Stream.Emit(BCOffset  , 32);
1451   Stream.Emit(0         , 32);  // Filled in later.
1452   Stream.Emit(CPUType   , 32);
1453 }
1454
1455 /// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1456 /// finalize the header.
1457 static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1458   // Update the size field in the header.
1459   Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1460
1461   // If the file is not a multiple of 16 bytes, insert dummy padding.
1462   while (BufferSize & 15) {
1463     Stream.Emit(0, 8);
1464     ++BufferSize;
1465   }
1466 }
1467
1468
1469 /// WriteBitcodeToFile - Write the specified module to the specified output
1470 /// stream.
1471 void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1472   raw_os_ostream RawOut(Out);
1473   // If writing to stdout, set binary mode.
1474   if (llvm::cout == Out)
1475     sys::Program::ChangeStdoutToBinary();
1476   WriteBitcodeToFile(M, RawOut);
1477 }
1478
1479 /// WriteBitcodeToFile - Write the specified module to the specified output
1480 /// stream.
1481 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1482   std::vector<unsigned char> Buffer;
1483   BitstreamWriter Stream(Buffer);
1484
1485   Buffer.reserve(256*1024);
1486
1487   WriteBitcodeToStream( M, Stream );
1488
1489   // If writing to stdout, set binary mode.
1490   if (&llvm::outs() == &Out)
1491     sys::Program::ChangeStdoutToBinary();
1492
1493   // Write the generated bitstream to "Out".
1494   Out.write((char*)&Buffer.front(), Buffer.size());
1495
1496   // Make sure it hits disk now.
1497   Out.flush();
1498 }
1499
1500 /// WriteBitcodeToStream - Write the specified module to the specified output
1501 /// stream.
1502 void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1503   // If this is darwin, emit a file header and trailer if needed.
1504   bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1505   if (isDarwin)
1506     EmitDarwinBCHeader(Stream, M->getTargetTriple());
1507
1508   // Emit the file header.
1509   Stream.Emit((unsigned)'B', 8);
1510   Stream.Emit((unsigned)'C', 8);
1511   Stream.Emit(0x0, 4);
1512   Stream.Emit(0xC, 4);
1513   Stream.Emit(0xE, 4);
1514   Stream.Emit(0xD, 4);
1515
1516   // Emit the module.
1517   WriteModule(M, Stream);
1518
1519   if (isDarwin)
1520     EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1521 }