lib/Bitcode/Writer/BitcodeWriter.cpp

   1 //===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by Chris Lattner and is distributed under
   6 // the University of Illinois Open Source 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/Instructions.h"
  21 #include "llvm/Module.h"
  22 #include "llvm/ParameterAttributes.h"
  23 #include "llvm/TypeSymbolTable.h"
  24 #include "llvm/ValueSymbolTable.h"
  25 #include "llvm/Support/MathExtras.h"
  26 using namespace llvm;
  27
  28 /// These are manifest constants used by the bitcode writer. They do not need to
  29 /// be kept in sync with the reader, but need to be consistent within this file.
  30 enum {
  31   CurVersion = 0,
  32
  33   // VALUE_SYMTAB_BLOCK abbrev id's.
  34   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  35   VST_ENTRY_7_ABBREV,
  36   VST_ENTRY_6_ABBREV,
  37   VST_BBENTRY_6_ABBREV,
  38
  39   // CONSTANTS_BLOCK abbrev id's.
  40   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  41   CONSTANTS_INTEGER_ABBREV,
  42   CONSTANTS_CE_CAST_Abbrev,
  43   CONSTANTS_NULL_Abbrev,
  44
  45   // FUNCTION_BLOCK abbrev id's.
  46   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV
  47 };
  48
  49
  50 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  51   switch (Opcode) {
  52   default: assert(0 && "Unknown cast instruction!");
  53   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  54   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  55   case Instruction::SExt    : return bitc::CAST_SEXT;
  56   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  57   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  58   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  59   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  60   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  61   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  62   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  63   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  64   case Instruction::BitCast : return bitc::CAST_BITCAST;
  65   }
  66 }
  67
  68 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  69   switch (Opcode) {
  70   default: assert(0 && "Unknown binary instruction!");
  71   case Instruction::Add:  return bitc::BINOP_ADD;
  72   case Instruction::Sub:  return bitc::BINOP_SUB;
  73   case Instruction::Mul:  return bitc::BINOP_MUL;
  74   case Instruction::UDiv: return bitc::BINOP_UDIV;
  75   case Instruction::FDiv:
  76   case Instruction::SDiv: return bitc::BINOP_SDIV;
  77   case Instruction::URem: return bitc::BINOP_UREM;
  78   case Instruction::FRem:
  79   case Instruction::SRem: return bitc::BINOP_SREM;
  80   case Instruction::Shl:  return bitc::BINOP_SHL;
  81   case Instruction::LShr: return bitc::BINOP_LSHR;
  82   case Instruction::AShr: return bitc::BINOP_ASHR;
  83   case Instruction::And:  return bitc::BINOP_AND;
  84   case Instruction::Or:   return bitc::BINOP_OR;
  85   case Instruction::Xor:  return bitc::BINOP_XOR;
  86   }
  87 }
  88
  89
  90
  91 static void WriteStringRecord(unsigned Code, const std::string &Str,
  92                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
  93   SmallVector<unsigned, 64> Vals;
  94
  95   // Code: [strchar x N]
  96   for (unsigned i = 0, e = Str.size(); i != e; ++i)
  97     Vals.push_back(Str[i]);
  98
  99   // Emit the finished record.
 100   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 101 }
 102
 103 // Emit information about parameter attributes.
 104 static void WriteParamAttrTable(const ValueEnumerator &VE,
 105                                 BitstreamWriter &Stream) {
 106   const std::vector<const ParamAttrsList*> &Attrs = VE.getParamAttrs();
 107   if (Attrs.empty()) return;
 108
 109   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 110
 111   SmallVector<uint64_t, 64> Record;
 112   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 113     const ParamAttrsList *A = Attrs[i];
 114     for (unsigned op = 0, e = A->size(); op != e; ++op) {
 115       Record.push_back(A->getParamIndex(op));
 116       Record.push_back(A->getParamAttrsAtIndex(op));
 117     }
 118
 119     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 120     Record.clear();
 121   }
 122
 123   Stream.ExitBlock();
 124 }
 125
 126 /// WriteTypeTable - Write out the type table for a module.
 127 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 128   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 129
 130   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
 131   SmallVector<uint64_t, 64> TypeVals;
 132
 133   // Abbrev for TYPE_CODE_POINTER.
 134   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 135   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 136   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 137                             Log2_32_Ceil(VE.getTypes().size()+1)));
 138   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 139
 140   // Abbrev for TYPE_CODE_FUNCTION.
 141   Abbv = new BitCodeAbbrev();
 142   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 143   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 144   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 145                             Log2_32_Ceil(VE.getParamAttrs().size()+1)));
 146   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 147   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 148                             Log2_32_Ceil(VE.getTypes().size()+1)));
 149   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 150
 151   // Abbrev for TYPE_CODE_STRUCT.
 152   Abbv = new BitCodeAbbrev();
 153   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
 154   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 155   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 156   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 157                             Log2_32_Ceil(VE.getTypes().size()+1)));
 158   unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
 159
 160   // Abbrev for TYPE_CODE_ARRAY.
 161   Abbv = new BitCodeAbbrev();
 162   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 163   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 164   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 165                             Log2_32_Ceil(VE.getTypes().size()+1)));
 166   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 167
 168   // Emit an entry count so the reader can reserve space.
 169   TypeVals.push_back(TypeList.size());
 170   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 171   TypeVals.clear();
 172
 173   // Loop over all of the types, emitting each in turn.
 174   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 175     const Type *T = TypeList[i].first;
 176     int AbbrevToUse = 0;
 177     unsigned Code = 0;
 178
 179     switch (T->getTypeID()) {
 180     case Type::PackedStructTyID: // FIXME: Delete Type::PackedStructTyID.
 181     default: assert(0 && "Unknown type!");
 182     case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
 183     case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
 184     case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
 185     case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
 186     case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
 187     case Type::IntegerTyID:
 188       // INTEGER: [width]
 189       Code = bitc::TYPE_CODE_INTEGER;
 190       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 191       break;
 192     case Type::PointerTyID:
 193       // POINTER: [pointee type]
 194       Code = bitc::TYPE_CODE_POINTER;
 195       TypeVals.push_back(VE.getTypeID(cast<PointerType>(T)->getElementType()));
 196       AbbrevToUse = PtrAbbrev;
 197       break;
 198
 199     case Type::FunctionTyID: {
 200       const FunctionType *FT = cast<FunctionType>(T);
 201       // FUNCTION: [isvararg, attrid, retty, paramty x N]
 202       Code = bitc::TYPE_CODE_FUNCTION;
 203       TypeVals.push_back(FT->isVarArg());
 204       TypeVals.push_back(VE.getParamAttrID(FT->getParamAttrs()));
 205       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 206       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 207         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 208       AbbrevToUse = FunctionAbbrev;
 209       break;
 210     }
 211     case Type::StructTyID: {
 212       const StructType *ST = cast<StructType>(T);
 213       // STRUCT: [ispacked, eltty x N]
 214       Code = bitc::TYPE_CODE_STRUCT;
 215       TypeVals.push_back(ST->isPacked());
 216       // Output all of the element types.
 217       for (StructType::element_iterator I = ST->element_begin(),
 218            E = ST->element_end(); I != E; ++I)
 219         TypeVals.push_back(VE.getTypeID(*I));
 220       AbbrevToUse = StructAbbrev;
 221       break;
 222     }
 223     case Type::ArrayTyID: {
 224       const ArrayType *AT = cast<ArrayType>(T);
 225       // ARRAY: [numelts, eltty]
 226       Code = bitc::TYPE_CODE_ARRAY;
 227       TypeVals.push_back(AT->getNumElements());
 228       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 229       AbbrevToUse = ArrayAbbrev;
 230       break;
 231     }
 232     case Type::VectorTyID: {
 233       const VectorType *VT = cast<VectorType>(T);
 234       // VECTOR [numelts, eltty]
 235       Code = bitc::TYPE_CODE_VECTOR;
 236       TypeVals.push_back(VT->getNumElements());
 237       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 238       break;
 239     }
 240     }
 241
 242     // Emit the finished record.
 243     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 244     TypeVals.clear();
 245   }
 246
 247   Stream.ExitBlock();
 248 }
 249
 250 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 251   switch (GV->getLinkage()) {
 252   default: assert(0 && "Invalid linkage!");
 253   case GlobalValue::ExternalLinkage:     return 0;
 254   case GlobalValue::WeakLinkage:         return 1;
 255   case GlobalValue::AppendingLinkage:    return 2;
 256   case GlobalValue::InternalLinkage:     return 3;
 257   case GlobalValue::LinkOnceLinkage:     return 4;
 258   case GlobalValue::DLLImportLinkage:    return 5;
 259   case GlobalValue::DLLExportLinkage:    return 6;
 260   case GlobalValue::ExternalWeakLinkage: return 7;
 261   }
 262 }
 263
 264 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 265   switch (GV->getVisibility()) {
 266   default: assert(0 && "Invalid visibility!");
 267   case GlobalValue::DefaultVisibility:   return 0;
 268   case GlobalValue::HiddenVisibility:    return 1;
 269   case GlobalValue::ProtectedVisibility: return 2;
 270   }
 271 }
 272
 273 // Emit top-level description of module, including target triple, inline asm,
 274 // descriptors for global variables, and function prototype info.
 275 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 276                             BitstreamWriter &Stream) {
 277   // Emit the list of dependent libraries for the Module.
 278   for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
 279     WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
 280
 281   // Emit various pieces of data attached to a module.
 282   if (!M->getTargetTriple().empty())
 283     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 284                       0/*TODO*/, Stream);
 285   if (!M->getDataLayout().empty())
 286     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 287                       0/*TODO*/, Stream);
 288   if (!M->getModuleInlineAsm().empty())
 289     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 290                       0/*TODO*/, Stream);
 291
 292   // Emit information about sections, computing how many there are.  Also
 293   // compute the maximum alignment value.
 294   std::map<std::string, unsigned> SectionMap;
 295   unsigned MaxAlignment = 0;
 296   unsigned MaxGlobalType = 0;
 297   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 298        GV != E; ++GV) {
 299     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 300     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 301
 302     if (!GV->hasSection()) continue;
 303     // Give section names unique ID's.
 304     unsigned &Entry = SectionMap[GV->getSection()];
 305     if (Entry != 0) continue;
 306     WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 307                       0/*TODO*/, Stream);
 308     Entry = SectionMap.size();
 309   }
 310   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 311     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 312     if (!F->hasSection()) continue;
 313     // Give section names unique ID's.
 314     unsigned &Entry = SectionMap[F->getSection()];
 315     if (Entry != 0) continue;
 316     WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 317                       0/*TODO*/, Stream);
 318     Entry = SectionMap.size();
 319   }
 320
 321   // Emit abbrev for globals, now that we know # sections and max alignment.
 322   unsigned SimpleGVarAbbrev = 0;
 323   if (!M->global_empty()) {
 324     // Add an abbrev for common globals with no visibility or thread localness.
 325     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 326     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 327     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 328                               Log2_32_Ceil(MaxGlobalType+1)));
 329     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 330     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 331     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));      // Linkage.
 332     if (MaxAlignment == 0)                                      // Alignment.
 333       Abbv->Add(BitCodeAbbrevOp(0));
 334     else {
 335       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 336       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 337                                Log2_32_Ceil(MaxEncAlignment+1)));
 338     }
 339     if (SectionMap.empty())                                    // Section.
 340       Abbv->Add(BitCodeAbbrevOp(0));
 341     else
 342       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 343                                Log2_32_Ceil(SectionMap.size()+1)));
 344     // Don't bother emitting vis + thread local.
 345     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 346   }
 347
 348   // Emit the global variable information.
 349   SmallVector<unsigned, 64> Vals;
 350   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 351        GV != E; ++GV) {
 352     unsigned AbbrevToUse = 0;
 353
 354     // GLOBALVAR: [type, isconst, initid,
 355     //             linkage, alignment, section, visibility, threadlocal]
 356     Vals.push_back(VE.getTypeID(GV->getType()));
 357     Vals.push_back(GV->isConstant());
 358     Vals.push_back(GV->isDeclaration() ? 0 :
 359                    (VE.getValueID(GV->getInitializer()) + 1));
 360     Vals.push_back(getEncodedLinkage(GV));
 361     Vals.push_back(Log2_32(GV->getAlignment())+1);
 362     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 363     if (GV->isThreadLocal() ||
 364         GV->getVisibility() != GlobalValue::DefaultVisibility) {
 365       Vals.push_back(getEncodedVisibility(GV));
 366       Vals.push_back(GV->isThreadLocal());
 367     } else {
 368       AbbrevToUse = SimpleGVarAbbrev;
 369     }
 370
 371     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 372     Vals.clear();
 373   }
 374
 375   // Emit the function proto information.
 376   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 377     // FUNCTION:  [type, callingconv, isproto, linkage, alignment, section,
 378     //             visibility]
 379     Vals.push_back(VE.getTypeID(F->getType()));
 380     Vals.push_back(F->getCallingConv());
 381     Vals.push_back(F->isDeclaration());
 382     Vals.push_back(getEncodedLinkage(F));
 383     Vals.push_back(Log2_32(F->getAlignment())+1);
 384     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 385     Vals.push_back(getEncodedVisibility(F));
 386
 387     unsigned AbbrevToUse = 0;
 388     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 389     Vals.clear();
 390   }
 391
 392
 393   // Emit the alias information.
 394   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 395        AI != E; ++AI) {
 396     Vals.push_back(VE.getTypeID(AI->getType()));
 397     Vals.push_back(VE.getValueID(AI->getAliasee()));
 398     Vals.push_back(getEncodedLinkage(AI));
 399     unsigned AbbrevToUse = 0;
 400     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 401     Vals.clear();
 402   }
 403 }
 404
 405
 406 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 407                            const ValueEnumerator &VE,
 408                            BitstreamWriter &Stream, bool isGlobal) {
 409   if (FirstVal == LastVal) return;
 410
 411   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 412
 413   unsigned AggregateAbbrev = 0;
 414   unsigned GEPAbbrev = 0;
 415   // If this is a constant pool for the module, emit module-specific abbrevs.
 416   if (isGlobal) {
 417     // Abbrev for CST_CODE_AGGREGATE.
 418     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 419     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 420     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 421     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 422     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 423   }
 424
 425   // FIXME: Install and use abbrevs to reduce size.  Install them globally so
 426   // they don't need to be reemitted for each function body.
 427
 428   SmallVector<uint64_t, 64> Record;
 429
 430   const ValueEnumerator::ValueList &Vals = VE.getValues();
 431   const Type *LastTy = 0;
 432   for (unsigned i = FirstVal; i != LastVal; ++i) {
 433     const Value *V = Vals[i].first;
 434     // If we need to switch types, do so now.
 435     if (V->getType() != LastTy) {
 436       LastTy = V->getType();
 437       Record.push_back(VE.getTypeID(LastTy));
 438       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 439                         CONSTANTS_SETTYPE_ABBREV);
 440       Record.clear();
 441     }
 442
 443     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 444       assert(0 && IA && "FIXME: Inline asm writing unimp!");
 445       continue;
 446     }
 447     const Constant *C = cast<Constant>(V);
 448     unsigned Code = -1U;
 449     unsigned AbbrevToUse = 0;
 450     if (C->isNullValue()) {
 451       Code = bitc::CST_CODE_NULL;
 452     } else if (isa<UndefValue>(C)) {
 453       Code = bitc::CST_CODE_UNDEF;
 454     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 455       if (IV->getBitWidth() <= 64) {
 456         int64_t V = IV->getSExtValue();
 457         if (V >= 0)
 458           Record.push_back(V << 1);
 459         else
 460           Record.push_back((-V << 1) | 1);
 461         Code = bitc::CST_CODE_INTEGER;
 462         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 463       } else {                             // Wide integers, > 64 bits in size.
 464         // We have an arbitrary precision integer value to write whose
 465         // bit width is > 64. However, in canonical unsigned integer
 466         // format it is likely that the high bits are going to be zero.
 467         // So, we only write the number of active words.
 468         unsigned NWords = IV->getValue().getActiveWords();
 469         const uint64_t *RawWords = IV->getValue().getRawData();
 470         for (unsigned i = 0; i != NWords; ++i) {
 471           int64_t V = RawWords[i];
 472           if (V >= 0)
 473             Record.push_back(V << 1);
 474           else
 475             Record.push_back((-V << 1) | 1);
 476         }
 477         Code = bitc::CST_CODE_WIDE_INTEGER;
 478       }
 479     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 480       Code = bitc::CST_CODE_FLOAT;
 481       if (CFP->getType() == Type::FloatTy) {
 482         Record.push_back(FloatToBits((float)CFP->getValue()));
 483       } else {
 484         assert (CFP->getType() == Type::DoubleTy && "Unknown FP type!");
 485         Record.push_back(DoubleToBits((double)CFP->getValue()));
 486       }
 487     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 488       // Emit constant strings specially.
 489       Code = bitc::CST_CODE_STRING;
 490       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 491         Record.push_back(cast<ConstantInt>(C->getOperand(i))->getZExtValue());
 492
 493     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
 494                isa<ConstantVector>(V)) {
 495       Code = bitc::CST_CODE_AGGREGATE;
 496       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 497         Record.push_back(VE.getValueID(C->getOperand(i)));
 498       AbbrevToUse = AggregateAbbrev;
 499     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 500       switch (CE->getOpcode()) {
 501       default:
 502         if (Instruction::isCast(CE->getOpcode())) {
 503           Code = bitc::CST_CODE_CE_CAST;
 504           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 505           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 506           Record.push_back(VE.getValueID(C->getOperand(0)));
 507           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 508         } else {
 509           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 510           Code = bitc::CST_CODE_CE_BINOP;
 511           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 512           Record.push_back(VE.getValueID(C->getOperand(0)));
 513           Record.push_back(VE.getValueID(C->getOperand(1)));
 514         }
 515         break;
 516       case Instruction::GetElementPtr:
 517         Code = bitc::CST_CODE_CE_GEP;
 518         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 519           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 520           Record.push_back(VE.getValueID(C->getOperand(i)));
 521         }
 522         AbbrevToUse = GEPAbbrev;
 523         break;
 524       case Instruction::Select:
 525         Code = bitc::CST_CODE_CE_SELECT;
 526         Record.push_back(VE.getValueID(C->getOperand(0)));
 527         Record.push_back(VE.getValueID(C->getOperand(1)));
 528         Record.push_back(VE.getValueID(C->getOperand(2)));
 529         break;
 530       case Instruction::ExtractElement:
 531         Code = bitc::CST_CODE_CE_EXTRACTELT;
 532         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 533         Record.push_back(VE.getValueID(C->getOperand(0)));
 534         Record.push_back(VE.getValueID(C->getOperand(1)));
 535         break;
 536       case Instruction::InsertElement:
 537         Code = bitc::CST_CODE_CE_INSERTELT;
 538         Record.push_back(VE.getValueID(C->getOperand(0)));
 539         Record.push_back(VE.getValueID(C->getOperand(1)));
 540         Record.push_back(VE.getValueID(C->getOperand(2)));
 541         break;
 542       case Instruction::ShuffleVector:
 543         Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 544         Record.push_back(VE.getValueID(C->getOperand(0)));
 545         Record.push_back(VE.getValueID(C->getOperand(1)));
 546         Record.push_back(VE.getValueID(C->getOperand(2)));
 547         break;
 548       case Instruction::ICmp:
 549       case Instruction::FCmp:
 550         Code = bitc::CST_CODE_CE_CMP;
 551         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 552         Record.push_back(VE.getValueID(C->getOperand(0)));
 553         Record.push_back(VE.getValueID(C->getOperand(1)));
 554         Record.push_back(CE->getPredicate());
 555         break;
 556       }
 557     } else {
 558       assert(0 && "Unknown constant!");
 559     }
 560     Stream.EmitRecord(Code, Record, AbbrevToUse);
 561     Record.clear();
 562   }
 563
 564   Stream.ExitBlock();
 565 }
 566
 567 static void WriteModuleConstants(const ValueEnumerator &VE,
 568                                  BitstreamWriter &Stream) {
 569   const ValueEnumerator::ValueList &Vals = VE.getValues();
 570
 571   // Find the first constant to emit, which is the first non-globalvalue value.
 572   // We know globalvalues have been emitted by WriteModuleInfo.
 573   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 574     if (!isa<GlobalValue>(Vals[i].first)) {
 575       WriteConstants(i, Vals.size(), VE, Stream, true);
 576       return;
 577     }
 578   }
 579 }
 580
 581 /// PushValueAndType - The file has to encode both the value and type id for
 582 /// many values, because we need to know what type to create for forward
 583 /// references.  However, most operands are not forward references, so this type
 584 /// field is not needed.
 585 ///
 586 /// This function adds V's value ID to Vals.  If the value ID is higher than the
 587 /// instruction ID, then it is a forward reference, and it also includes the
 588 /// type ID.
 589 static bool PushValueAndType(Value *V, unsigned InstID,
 590                              SmallVector<unsigned, 64> &Vals,
 591                              ValueEnumerator &VE) {
 592   unsigned ValID = VE.getValueID(V);
 593   Vals.push_back(ValID);
 594   if (ValID >= InstID) {
 595     Vals.push_back(VE.getTypeID(V->getType()));
 596     return true;
 597   }
 598   return false;
 599 }
 600
 601 /// WriteInstruction - Emit an instruction to the specified stream.
 602 static void WriteInstruction(const Instruction &I, unsigned InstID,
 603                              ValueEnumerator &VE, BitstreamWriter &Stream,
 604                              SmallVector<unsigned, 64> &Vals) {
 605   unsigned Code = 0;
 606   unsigned AbbrevToUse = 0;
 607   switch (I.getOpcode()) {
 608   default:
 609     if (Instruction::isCast(I.getOpcode())) {
 610       Code = bitc::FUNC_CODE_INST_CAST;
 611       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 612       Vals.push_back(VE.getTypeID(I.getType()));
 613       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
 614     } else {
 615       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
 616       Code = bitc::FUNC_CODE_INST_BINOP;
 617       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 618       Vals.push_back(VE.getValueID(I.getOperand(1)));
 619       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
 620     }
 621     break;
 622
 623   case Instruction::GetElementPtr:
 624     Code = bitc::FUNC_CODE_INST_GEP;
 625     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 626       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 627     break;
 628   case Instruction::Select:
 629     Code = bitc::FUNC_CODE_INST_SELECT;
 630     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 631     Vals.push_back(VE.getValueID(I.getOperand(2)));
 632     Vals.push_back(VE.getValueID(I.getOperand(0)));
 633     break;
 634   case Instruction::ExtractElement:
 635     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
 636     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 637     Vals.push_back(VE.getValueID(I.getOperand(1)));
 638     break;
 639   case Instruction::InsertElement:
 640     Code = bitc::FUNC_CODE_INST_INSERTELT;
 641     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 642     Vals.push_back(VE.getValueID(I.getOperand(1)));
 643     Vals.push_back(VE.getValueID(I.getOperand(2)));
 644     break;
 645   case Instruction::ShuffleVector:
 646     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
 647     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 648     Vals.push_back(VE.getValueID(I.getOperand(1)));
 649     Vals.push_back(VE.getValueID(I.getOperand(2)));
 650     break;
 651   case Instruction::ICmp:
 652   case Instruction::FCmp:
 653     Code = bitc::FUNC_CODE_INST_CMP;
 654     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 655     Vals.push_back(VE.getValueID(I.getOperand(1)));
 656     Vals.push_back(cast<CmpInst>(I).getPredicate());
 657     break;
 658
 659   case Instruction::Ret:
 660     Code = bitc::FUNC_CODE_INST_RET;
 661     if (I.getNumOperands())
 662       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 663     break;
 664   case Instruction::Br:
 665     Code = bitc::FUNC_CODE_INST_BR;
 666     Vals.push_back(VE.getValueID(I.getOperand(0)));
 667     if (cast<BranchInst>(I).isConditional()) {
 668       Vals.push_back(VE.getValueID(I.getOperand(1)));
 669       Vals.push_back(VE.getValueID(I.getOperand(2)));
 670     }
 671     break;
 672   case Instruction::Switch:
 673     Code = bitc::FUNC_CODE_INST_SWITCH;
 674     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
 675     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 676       Vals.push_back(VE.getValueID(I.getOperand(i)));
 677     break;
 678   case Instruction::Invoke: {
 679     Code = bitc::FUNC_CODE_INST_INVOKE;
 680     Vals.push_back(cast<InvokeInst>(I).getCallingConv());
 681     Vals.push_back(VE.getValueID(I.getOperand(1)));      // normal dest
 682     Vals.push_back(VE.getValueID(I.getOperand(2)));      // unwind dest
 683     PushValueAndType(I.getOperand(0), InstID, Vals, VE); // callee
 684
 685     // Emit value #'s for the fixed parameters.
 686     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
 687     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 688     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 689       Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
 690
 691     // Emit type/value pairs for varargs params.
 692     if (FTy->isVarArg()) {
 693       for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
 694            i != e; ++i)
 695         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
 696     }
 697     break;
 698   }
 699   case Instruction::Unwind:
 700     Code = bitc::FUNC_CODE_INST_UNWIND;
 701     break;
 702   case Instruction::Unreachable:
 703     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
 704     break;
 705
 706   case Instruction::PHI:
 707     Code = bitc::FUNC_CODE_INST_PHI;
 708     Vals.push_back(VE.getTypeID(I.getType()));
 709     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 710       Vals.push_back(VE.getValueID(I.getOperand(i)));
 711     break;
 712
 713   case Instruction::Malloc:
 714     Code = bitc::FUNC_CODE_INST_MALLOC;
 715     Vals.push_back(VE.getTypeID(I.getType()));
 716     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 717     Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
 718     break;
 719
 720   case Instruction::Free:
 721     Code = bitc::FUNC_CODE_INST_FREE;
 722     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 723     break;
 724
 725   case Instruction::Alloca:
 726     Code = bitc::FUNC_CODE_INST_ALLOCA;
 727     Vals.push_back(VE.getTypeID(I.getType()));
 728     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 729     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
 730     break;
 731
 732   case Instruction::Load:
 733     Code = bitc::FUNC_CODE_INST_LOAD;
 734     if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
 735       AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
 736
 737     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
 738     Vals.push_back(cast<LoadInst>(I).isVolatile());
 739     break;
 740   case Instruction::Store:
 741     Code = bitc::FUNC_CODE_INST_STORE;
 742     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // val.
 743     Vals.push_back(VE.getValueID(I.getOperand(1)));       // ptr.
 744     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
 745     Vals.push_back(cast<StoreInst>(I).isVolatile());
 746     break;
 747   case Instruction::Call: {
 748     Code = bitc::FUNC_CODE_INST_CALL;
 749     Vals.push_back((cast<CallInst>(I).getCallingConv() << 1) |
 750                    cast<CallInst>(I).isTailCall());
 751     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // Callee
 752
 753     // Emit value #'s for the fixed parameters.
 754     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
 755     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 756     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 757       Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
 758
 759     // Emit type/value pairs for varargs params.
 760     if (FTy->isVarArg()) {
 761       unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
 762       for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
 763            i != e; ++i)
 764         PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
 765     }
 766     break;
 767   }
 768   case Instruction::VAArg:
 769     Code = bitc::FUNC_CODE_INST_VAARG;
 770     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
 771     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
 772     Vals.push_back(VE.getTypeID(I.getType())); // restype.
 773     break;
 774   }
 775
 776   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 777   Vals.clear();
 778 }
 779
 780 // Emit names for globals/functions etc.
 781 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
 782                                   const ValueEnumerator &VE,
 783                                   BitstreamWriter &Stream) {
 784   if (VST.empty()) return;
 785   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
 786
 787   // FIXME: Set up the abbrev, we know how many values there are!
 788   // FIXME: We know if the type names can use 7-bit ascii.
 789   SmallVector<unsigned, 64> NameVals;
 790
 791   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
 792        SI != SE; ++SI) {
 793
 794     const ValueName &Name = *SI;
 795
 796     // Figure out the encoding to use for the name.
 797     bool is7Bit = true;
 798     bool isChar6 = true;
 799     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
 800          C != E; ++C) {
 801       if (isChar6)
 802         isChar6 = BitCodeAbbrevOp::isChar6(*C);
 803       if ((unsigned char)*C & 128) {
 804         is7Bit = false;
 805         break;  // don't bother scanning the rest.
 806       }
 807     }
 808
 809     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
 810
 811     // VST_ENTRY:   [valueid, namechar x N]
 812     // VST_BBENTRY: [bbid, namechar x N]
 813     unsigned Code;
 814     if (isa<BasicBlock>(SI->getValue())) {
 815       Code = bitc::VST_CODE_BBENTRY;
 816       if (isChar6)
 817         AbbrevToUse = VST_BBENTRY_6_ABBREV;
 818     } else {
 819       Code = bitc::VST_CODE_ENTRY;
 820       if (isChar6)
 821         AbbrevToUse = VST_ENTRY_6_ABBREV;
 822       else if (is7Bit)
 823         AbbrevToUse = VST_ENTRY_7_ABBREV;
 824     }
 825
 826     NameVals.push_back(VE.getValueID(SI->getValue()));
 827     for (const char *P = Name.getKeyData(),
 828          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
 829       NameVals.push_back((unsigned char)*P);
 830
 831     // Emit the finished record.
 832     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
 833     NameVals.clear();
 834   }
 835   Stream.ExitBlock();
 836 }
 837
 838 /// WriteFunction - Emit a function body to the module stream.
 839 static void WriteFunction(const Function &F, ValueEnumerator &VE,
 840                           BitstreamWriter &Stream) {
 841   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 3);
 842   VE.incorporateFunction(F);
 843
 844   SmallVector<unsigned, 64> Vals;
 845
 846   // Emit the number of basic blocks, so the reader can create them ahead of
 847   // time.
 848   Vals.push_back(VE.getBasicBlocks().size());
 849   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
 850   Vals.clear();
 851
 852   // FIXME: Function attributes?
 853
 854   // If there are function-local constants, emit them now.
 855   unsigned CstStart, CstEnd;
 856   VE.getFunctionConstantRange(CstStart, CstEnd);
 857   WriteConstants(CstStart, CstEnd, VE, Stream, false);
 858
 859   // Keep a running idea of what the instruction ID is.
 860   unsigned InstID = CstEnd;
 861
 862   // Finally, emit all the instructions, in order.
 863   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 864     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 865          I != E; ++I) {
 866       WriteInstruction(*I, InstID, VE, Stream, Vals);
 867       if (I->getType() != Type::VoidTy)
 868         ++InstID;
 869     }
 870
 871   // Emit names for all the instructions etc.
 872   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
 873
 874   VE.purgeFunction();
 875   Stream.ExitBlock();
 876 }
 877
 878 /// WriteTypeSymbolTable - Emit a block for the specified type symtab.
 879 static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
 880                                  const ValueEnumerator &VE,
 881                                  BitstreamWriter &Stream) {
 882   if (TST.empty()) return;
 883
 884   Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
 885
 886   // 7-bit fixed width VST_CODE_ENTRY strings.
 887   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 888   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
 889   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 890                             Log2_32_Ceil(VE.getTypes().size()+1)));
 891   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 892   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 893   unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
 894
 895   SmallVector<unsigned, 64> NameVals;
 896
 897   for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
 898        TI != TE; ++TI) {
 899     // TST_ENTRY: [typeid, namechar x N]
 900     NameVals.push_back(VE.getTypeID(TI->second));
 901
 902     const std::string &Str = TI->first;
 903     bool is7Bit = true;
 904     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 905       NameVals.push_back((unsigned char)Str[i]);
 906       if (Str[i] & 128)
 907         is7Bit = false;
 908     }
 909
 910     // Emit the finished record.
 911     Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
 912     NameVals.clear();
 913   }
 914
 915   Stream.ExitBlock();
 916 }
 917
 918 // Emit blockinfo, which defines the standard abbreviations etc.
 919 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 920   // We only want to emit block info records for blocks that have multiple
 921   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
 922   // blocks can defined their abbrevs inline.
 923   Stream.EnterBlockInfoBlock(2);
 924
 925   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
 926     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 927     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
 928     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 929     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 930     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 931     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
 932                                    Abbv) != VST_ENTRY_8_ABBREV)
 933       assert(0 && "Unexpected abbrev ordering!");
 934   }
 935
 936   { // 7-bit fixed width VST_ENTRY strings.
 937     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 938     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
 939     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 940     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 941     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 942     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
 943                                    Abbv) != VST_ENTRY_7_ABBREV)
 944       assert(0 && "Unexpected abbrev ordering!");
 945   }
 946   { // 6-bit char6 VST_ENTRY strings.
 947     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 948     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
 949     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 950     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 951     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 952     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
 953                                    Abbv) != VST_ENTRY_6_ABBREV)
 954       assert(0 && "Unexpected abbrev ordering!");
 955   }
 956   { // 6-bit char6 VST_BBENTRY strings.
 957     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 958     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
 959     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 960     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 961     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 962     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
 963                                    Abbv) != VST_BBENTRY_6_ABBREV)
 964       assert(0 && "Unexpected abbrev ordering!");
 965   }
 966
 967
 968
 969   { // SETTYPE abbrev for CONSTANTS_BLOCK.
 970     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 971     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
 972     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 973                               Log2_32_Ceil(VE.getTypes().size()+1)));
 974     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
 975                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
 976       assert(0 && "Unexpected abbrev ordering!");
 977   }
 978
 979   { // INTEGER abbrev for CONSTANTS_BLOCK.
 980     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 981     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
 982     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
 983     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
 984                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
 985       assert(0 && "Unexpected abbrev ordering!");
 986   }
 987
 988   { // CE_CAST abbrev for CONSTANTS_BLOCK.
 989     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 990     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
 991     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
 992     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
 993                               Log2_32_Ceil(VE.getTypes().size()+1)));
 994     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
 995
 996     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
 997                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
 998       assert(0 && "Unexpected abbrev ordering!");
 999   }
1000   { // NULL abbrev for CONSTANTS_BLOCK.
1001     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1002     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1003     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1004                                    Abbv) != CONSTANTS_NULL_Abbrev)
1005       assert(0 && "Unexpected abbrev ordering!");
1006   }
1007
1008   // FIXME: This should only use space for first class types!
1009
1010   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1011     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1012     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1013     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1014     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1015     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1016     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1017                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1018       assert(0 && "Unexpected abbrev ordering!");
1019   }
1020
1021   Stream.ExitBlock();
1022 }
1023
1024
1025 /// WriteModule - Emit the specified module to the bitstream.
1026 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1027   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1028
1029   // Emit the version number if it is non-zero.
1030   if (CurVersion) {
1031     SmallVector<unsigned, 1> Vals;
1032     Vals.push_back(CurVersion);
1033     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1034   }
1035
1036   // Analyze the module, enumerating globals, functions, etc.
1037   ValueEnumerator VE(M);
1038
1039   // Emit blockinfo, which defines the standard abbreviations etc.
1040   WriteBlockInfo(VE, Stream);
1041
1042   // Emit information about parameter attributes.
1043   WriteParamAttrTable(VE, Stream);
1044
1045   // Emit information describing all of the types in the module.
1046   WriteTypeTable(VE, Stream);
1047
1048   // Emit top-level description of module, including target triple, inline asm,
1049   // descriptors for global variables, and function prototype info.
1050   WriteModuleInfo(M, VE, Stream);
1051
1052   // Emit constants.
1053   WriteModuleConstants(VE, Stream);
1054
1055   // If we have any aggregate values in the value table, purge them - these can
1056   // only be used to initialize global variables.  Doing so makes the value
1057   // namespace smaller for code in functions.
1058   int NumNonAggregates = VE.PurgeAggregateValues();
1059   if (NumNonAggregates != -1) {
1060     SmallVector<unsigned, 1> Vals;
1061     Vals.push_back(NumNonAggregates);
1062     Stream.EmitRecord(bitc::MODULE_CODE_PURGEVALS, Vals);
1063   }
1064
1065   // Emit function bodies.
1066   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1067     if (!I->isDeclaration())
1068       WriteFunction(*I, VE, Stream);
1069
1070   // Emit the type symbol table information.
1071   WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1072
1073   // Emit names for globals/functions etc.
1074   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1075
1076   Stream.ExitBlock();
1077 }
1078
1079
1080 /// WriteBitcodeToFile - Write the specified module to the specified output
1081 /// stream.
1082 void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1083   std::vector<unsigned char> Buffer;
1084   BitstreamWriter Stream(Buffer);
1085
1086   Buffer.reserve(256*1024);
1087
1088   // Emit the file header.
1089   Stream.Emit((unsigned)'B', 8);
1090   Stream.Emit((unsigned)'C', 8);
1091   Stream.Emit(0x0, 4);
1092   Stream.Emit(0xC, 4);
1093   Stream.Emit(0xE, 4);
1094   Stream.Emit(0xD, 4);
1095
1096   // Emit the module.
1097   WriteModule(M, Stream);
1098
1099   // Write the generated bitstream to "Out".
1100   Out.write((char*)&Buffer.front(), Buffer.size());
1101 }