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::VoidTy));
 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.getValues();
 496   bool StartedMetadataBlock = false;
 497   unsigned MDSAbbrev = 0;
 498   unsigned String8Abbrev = 0;
 499   SmallVector<uint64_t, 64> Record;
 500   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 501
 502     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 503       if (!StartedMetadataBlock) {
 504         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 505         StartedMetadataBlock = true;
 506       }
 507       WriteMDNode(N, VE, Stream, Record);
 508     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 509       if (!StartedMetadataBlock)  {
 510         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 511
 512         // Abbrev for METADATA_STRING.
 513         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 514         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 515         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 516         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 517         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 518         StartedMetadataBlock = true;
 519       }
 520
 521       // Code: [strchar x N]
 522       const char *StrBegin = MDS->begin();
 523       for (unsigned i = 0, e = MDS->length(); i != e; ++i)
 524         Record.push_back(StrBegin[i]);
 525
 526       // Emit the finished record.
 527       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 528       Record.clear();
 529     } else if (const NamedMDNode *NMD = dyn_cast<NamedMDNode>(Vals[i].first)) {
 530       if (!StartedMetadataBlock)  {
 531         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 532         StartedMetadataBlock = true;
 533         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 534         Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 535         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 536         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 537         String8Abbrev = Stream.EmitAbbrev(Abbv);
 538       }
 539
 540       // Write name.
 541       const char *StrBegin = NMD->getName().data();
 542       for (unsigned i = 0, e = NMD->getName().size(); i != e; ++i)
 543         Record.push_back(StrBegin[i]);
 544       Stream.EmitRecord(bitc::METADATA_NAME, Record, String8Abbrev);
 545       Record.clear();
 546
 547       // Write named metadata elements.
 548       for (unsigned i = 0, e = NMD->getNumElements(); i != e; ++i) {
 549         if (NMD->getElement(i))
 550           Record.push_back(VE.getValueID(NMD->getElement(i)));
 551         else
 552           Record.push_back(0);
 553       }
 554       Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 555       Record.clear();
 556     }
 557   }
 558
 559   if (StartedMetadataBlock)
 560     Stream.ExitBlock();
 561 }
 562
 563 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 564                            const ValueEnumerator &VE,
 565                            BitstreamWriter &Stream, bool isGlobal) {
 566   if (FirstVal == LastVal) return;
 567
 568   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 569
 570   unsigned AggregateAbbrev = 0;
 571   unsigned String8Abbrev = 0;
 572   unsigned CString7Abbrev = 0;
 573   unsigned CString6Abbrev = 0;
 574   // If this is a constant pool for the module, emit module-specific abbrevs.
 575   if (isGlobal) {
 576     // Abbrev for CST_CODE_AGGREGATE.
 577     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 578     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 579     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 580     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 581     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 582
 583     // Abbrev for CST_CODE_STRING.
 584     Abbv = new BitCodeAbbrev();
 585     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 586     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 587     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 588     String8Abbrev = Stream.EmitAbbrev(Abbv);
 589     // Abbrev for CST_CODE_CSTRING.
 590     Abbv = new BitCodeAbbrev();
 591     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 592     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 593     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 594     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 595     // Abbrev for CST_CODE_CSTRING.
 596     Abbv = new BitCodeAbbrev();
 597     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 598     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 599     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 600     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 601   }
 602
 603   SmallVector<uint64_t, 64> Record;
 604
 605   const ValueEnumerator::ValueList &Vals = VE.getValues();
 606   const Type *LastTy = 0;
 607   for (unsigned i = FirstVal; i != LastVal; ++i) {
 608     const Value *V = Vals[i].first;
 609     if (isa<MetadataBase>(V))
 610       continue;
 611     // If we need to switch types, do so now.
 612     if (V->getType() != LastTy) {
 613       LastTy = V->getType();
 614       Record.push_back(VE.getTypeID(LastTy));
 615       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 616                         CONSTANTS_SETTYPE_ABBREV);
 617       Record.clear();
 618     }
 619
 620     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 621       Record.push_back(unsigned(IA->hasSideEffects()));
 622
 623       // Add the asm string.
 624       const std::string &AsmStr = IA->getAsmString();
 625       Record.push_back(AsmStr.size());
 626       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 627         Record.push_back(AsmStr[i]);
 628
 629       // Add the constraint string.
 630       const std::string &ConstraintStr = IA->getConstraintString();
 631       Record.push_back(ConstraintStr.size());
 632       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 633         Record.push_back(ConstraintStr[i]);
 634       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 635       Record.clear();
 636       continue;
 637     }
 638     const Constant *C = cast<Constant>(V);
 639     unsigned Code = -1U;
 640     unsigned AbbrevToUse = 0;
 641     if (C->isNullValue()) {
 642       Code = bitc::CST_CODE_NULL;
 643     } else if (isa<UndefValue>(C)) {
 644       Code = bitc::CST_CODE_UNDEF;
 645     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 646       if (IV->getBitWidth() <= 64) {
 647         int64_t V = IV->getSExtValue();
 648         if (V >= 0)
 649           Record.push_back(V << 1);
 650         else
 651           Record.push_back((-V << 1) | 1);
 652         Code = bitc::CST_CODE_INTEGER;
 653         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 654       } else {                             // Wide integers, > 64 bits in size.
 655         // We have an arbitrary precision integer value to write whose
 656         // bit width is > 64. However, in canonical unsigned integer
 657         // format it is likely that the high bits are going to be zero.
 658         // So, we only write the number of active words.
 659         unsigned NWords = IV->getValue().getActiveWords();
 660         const uint64_t *RawWords = IV->getValue().getRawData();
 661         for (unsigned i = 0; i != NWords; ++i) {
 662           int64_t V = RawWords[i];
 663           if (V >= 0)
 664             Record.push_back(V << 1);
 665           else
 666             Record.push_back((-V << 1) | 1);
 667         }
 668         Code = bitc::CST_CODE_WIDE_INTEGER;
 669       }
 670     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 671       Code = bitc::CST_CODE_FLOAT;
 672       const Type *Ty = CFP->getType();
 673       if (Ty == Type::FloatTy || Ty == Type::DoubleTy) {
 674         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 675       } else if (Ty == Type::X86_FP80Ty) {
 676         // api needed to prevent premature destruction
 677         // bits are not in the same order as a normal i80 APInt, compensate.
 678         APInt api = CFP->getValueAPF().bitcastToAPInt();
 679         const uint64_t *p = api.getRawData();
 680         Record.push_back((p[1] << 48) | (p[0] >> 16));
 681         Record.push_back(p[0] & 0xffffLL);
 682       } else if (Ty == Type::FP128Ty || Ty == Type::PPC_FP128Ty) {
 683         APInt api = CFP->getValueAPF().bitcastToAPInt();
 684         const uint64_t *p = api.getRawData();
 685         Record.push_back(p[0]);
 686         Record.push_back(p[1]);
 687       } else {
 688         assert (0 && "Unknown FP type!");
 689       }
 690     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 691       // Emit constant strings specially.
 692       unsigned NumOps = C->getNumOperands();
 693       // If this is a null-terminated string, use the denser CSTRING encoding.
 694       if (C->getOperand(NumOps-1)->isNullValue()) {
 695         Code = bitc::CST_CODE_CSTRING;
 696         --NumOps;  // Don't encode the null, which isn't allowed by char6.
 697       } else {
 698         Code = bitc::CST_CODE_STRING;
 699         AbbrevToUse = String8Abbrev;
 700       }
 701       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 702       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 703       for (unsigned i = 0; i != NumOps; ++i) {
 704         unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
 705         Record.push_back(V);
 706         isCStr7 &= (V & 128) == 0;
 707         if (isCStrChar6)
 708           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 709       }
 710
 711       if (isCStrChar6)
 712         AbbrevToUse = CString6Abbrev;
 713       else if (isCStr7)
 714         AbbrevToUse = CString7Abbrev;
 715     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
 716                isa<ConstantVector>(V)) {
 717       Code = bitc::CST_CODE_AGGREGATE;
 718       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 719         Record.push_back(VE.getValueID(C->getOperand(i)));
 720       AbbrevToUse = AggregateAbbrev;
 721     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 722       switch (CE->getOpcode()) {
 723       default:
 724         if (Instruction::isCast(CE->getOpcode())) {
 725           Code = bitc::CST_CODE_CE_CAST;
 726           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 727           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 728           Record.push_back(VE.getValueID(C->getOperand(0)));
 729           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 730         } else {
 731           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 732           Code = bitc::CST_CODE_CE_BINOP;
 733           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 734           Record.push_back(VE.getValueID(C->getOperand(0)));
 735           Record.push_back(VE.getValueID(C->getOperand(1)));
 736           uint64_t Flags = GetOptimizationFlags(CE);
 737           if (Flags != 0)
 738             Record.push_back(Flags);
 739         }
 740         break;
 741       case Instruction::GetElementPtr:
 742         Code = bitc::CST_CODE_CE_GEP;
 743         if (cast<GEPOperator>(C)->isInBounds())
 744           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
 745         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 746           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 747           Record.push_back(VE.getValueID(C->getOperand(i)));
 748         }
 749         break;
 750       case Instruction::Select:
 751         Code = bitc::CST_CODE_CE_SELECT;
 752         Record.push_back(VE.getValueID(C->getOperand(0)));
 753         Record.push_back(VE.getValueID(C->getOperand(1)));
 754         Record.push_back(VE.getValueID(C->getOperand(2)));
 755         break;
 756       case Instruction::ExtractElement:
 757         Code = bitc::CST_CODE_CE_EXTRACTELT;
 758         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 759         Record.push_back(VE.getValueID(C->getOperand(0)));
 760         Record.push_back(VE.getValueID(C->getOperand(1)));
 761         break;
 762       case Instruction::InsertElement:
 763         Code = bitc::CST_CODE_CE_INSERTELT;
 764         Record.push_back(VE.getValueID(C->getOperand(0)));
 765         Record.push_back(VE.getValueID(C->getOperand(1)));
 766         Record.push_back(VE.getValueID(C->getOperand(2)));
 767         break;
 768       case Instruction::ShuffleVector:
 769         // If the return type and argument types are the same, this is a
 770         // standard shufflevector instruction.  If the types are different,
 771         // then the shuffle is widening or truncating the input vectors, and
 772         // the argument type must also be encoded.
 773         if (C->getType() == C->getOperand(0)->getType()) {
 774           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 775         } else {
 776           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 777           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 778         }
 779         Record.push_back(VE.getValueID(C->getOperand(0)));
 780         Record.push_back(VE.getValueID(C->getOperand(1)));
 781         Record.push_back(VE.getValueID(C->getOperand(2)));
 782         break;
 783       case Instruction::ICmp:
 784       case Instruction::FCmp:
 785         Code = bitc::CST_CODE_CE_CMP;
 786         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 787         Record.push_back(VE.getValueID(C->getOperand(0)));
 788         Record.push_back(VE.getValueID(C->getOperand(1)));
 789         Record.push_back(CE->getPredicate());
 790         break;
 791       }
 792     } else {
 793       llvm_unreachable("Unknown constant!");
 794     }
 795     Stream.EmitRecord(Code, Record, AbbrevToUse);
 796     Record.clear();
 797   }
 798
 799   Stream.ExitBlock();
 800 }
 801
 802 static void WriteModuleConstants(const ValueEnumerator &VE,
 803                                  BitstreamWriter &Stream) {
 804   const ValueEnumerator::ValueList &Vals = VE.getValues();
 805
 806   // Find the first constant to emit, which is the first non-globalvalue value.
 807   // We know globalvalues have been emitted by WriteModuleInfo.
 808   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 809     if (!isa<GlobalValue>(Vals[i].first)) {
 810       WriteConstants(i, Vals.size(), VE, Stream, true);
 811       return;
 812     }
 813   }
 814 }
 815
 816 /// PushValueAndType - The file has to encode both the value and type id for
 817 /// many values, because we need to know what type to create for forward
 818 /// references.  However, most operands are not forward references, so this type
 819 /// field is not needed.
 820 ///
 821 /// This function adds V's value ID to Vals.  If the value ID is higher than the
 822 /// instruction ID, then it is a forward reference, and it also includes the
 823 /// type ID.
 824 static bool PushValueAndType(const Value *V, unsigned InstID,
 825                              SmallVector<unsigned, 64> &Vals,
 826                              ValueEnumerator &VE) {
 827   unsigned ValID = VE.getValueID(V);
 828   Vals.push_back(ValID);
 829   if (ValID >= InstID) {
 830     Vals.push_back(VE.getTypeID(V->getType()));
 831     return true;
 832   }
 833   return false;
 834 }
 835
 836 /// WriteInstruction - Emit an instruction to the specified stream.
 837 static void WriteInstruction(const Instruction &I, unsigned InstID,
 838                              ValueEnumerator &VE, BitstreamWriter &Stream,
 839                              SmallVector<unsigned, 64> &Vals) {
 840   unsigned Code = 0;
 841   unsigned AbbrevToUse = 0;
 842   switch (I.getOpcode()) {
 843   default:
 844     if (Instruction::isCast(I.getOpcode())) {
 845       Code = bitc::FUNC_CODE_INST_CAST;
 846       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 847         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
 848       Vals.push_back(VE.getTypeID(I.getType()));
 849       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
 850     } else {
 851       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
 852       Code = bitc::FUNC_CODE_INST_BINOP;
 853       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 854         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
 855       Vals.push_back(VE.getValueID(I.getOperand(1)));
 856       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
 857       uint64_t Flags = GetOptimizationFlags(&I);
 858       if (Flags != 0) {
 859         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
 860           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
 861         Vals.push_back(Flags);
 862       }
 863     }
 864     break;
 865
 866   case Instruction::GetElementPtr:
 867     Code = bitc::FUNC_CODE_INST_GEP;
 868     if (cast<GEPOperator>(&I)->isInBounds())
 869       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
 870     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 871       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 872     break;
 873   case Instruction::ExtractValue: {
 874     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
 875     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 876     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
 877     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
 878       Vals.push_back(*i);
 879     break;
 880   }
 881   case Instruction::InsertValue: {
 882     Code = bitc::FUNC_CODE_INST_INSERTVAL;
 883     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 884     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 885     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
 886     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
 887       Vals.push_back(*i);
 888     break;
 889   }
 890   case Instruction::Select:
 891     Code = bitc::FUNC_CODE_INST_VSELECT;
 892     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
 893     Vals.push_back(VE.getValueID(I.getOperand(2)));
 894     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 895     break;
 896   case Instruction::ExtractElement:
 897     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
 898     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 899     Vals.push_back(VE.getValueID(I.getOperand(1)));
 900     break;
 901   case Instruction::InsertElement:
 902     Code = bitc::FUNC_CODE_INST_INSERTELT;
 903     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 904     Vals.push_back(VE.getValueID(I.getOperand(1)));
 905     Vals.push_back(VE.getValueID(I.getOperand(2)));
 906     break;
 907   case Instruction::ShuffleVector:
 908     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
 909     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 910     Vals.push_back(VE.getValueID(I.getOperand(1)));
 911     Vals.push_back(VE.getValueID(I.getOperand(2)));
 912     break;
 913   case Instruction::ICmp:
 914   case Instruction::FCmp:
 915     // compare returning Int1Ty or vector of Int1Ty
 916     Code = bitc::FUNC_CODE_INST_CMP2;
 917     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
 918     Vals.push_back(VE.getValueID(I.getOperand(1)));
 919     Vals.push_back(cast<CmpInst>(I).getPredicate());
 920     break;
 921
 922   case Instruction::Ret:
 923     {
 924       Code = bitc::FUNC_CODE_INST_RET;
 925       unsigned NumOperands = I.getNumOperands();
 926       if (NumOperands == 0)
 927         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
 928       else if (NumOperands == 1) {
 929         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
 930           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
 931       } else {
 932         for (unsigned i = 0, e = NumOperands; i != e; ++i)
 933           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
 934       }
 935     }
 936     break;
 937   case Instruction::Br:
 938     {
 939       Code = bitc::FUNC_CODE_INST_BR;
 940       BranchInst &II(cast<BranchInst>(I));
 941       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
 942       if (II.isConditional()) {
 943         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
 944         Vals.push_back(VE.getValueID(II.getCondition()));
 945       }
 946     }
 947     break;
 948   case Instruction::Switch:
 949     Code = bitc::FUNC_CODE_INST_SWITCH;
 950     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
 951     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 952       Vals.push_back(VE.getValueID(I.getOperand(i)));
 953     break;
 954   case Instruction::Invoke: {
 955     const InvokeInst *II = cast<InvokeInst>(&I);
 956     const Value *Callee(II->getCalledValue());
 957     const PointerType *PTy = cast<PointerType>(Callee->getType());
 958     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
 959     Code = bitc::FUNC_CODE_INST_INVOKE;
 960
 961     Vals.push_back(VE.getAttributeID(II->getAttributes()));
 962     Vals.push_back(II->getCallingConv());
 963     Vals.push_back(VE.getValueID(II->getNormalDest()));
 964     Vals.push_back(VE.getValueID(II->getUnwindDest()));
 965     PushValueAndType(Callee, InstID, Vals, VE);
 966
 967     // Emit value #'s for the fixed parameters.
 968     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
 969       Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
 970
 971     // Emit type/value pairs for varargs params.
 972     if (FTy->isVarArg()) {
 973       for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
 974            i != e; ++i)
 975         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
 976     }
 977     break;
 978   }
 979   case Instruction::Unwind:
 980     Code = bitc::FUNC_CODE_INST_UNWIND;
 981     break;
 982   case Instruction::Unreachable:
 983     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
 984     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
 985     break;
 986
 987   case Instruction::PHI:
 988     Code = bitc::FUNC_CODE_INST_PHI;
 989     Vals.push_back(VE.getTypeID(I.getType()));
 990     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
 991       Vals.push_back(VE.getValueID(I.getOperand(i)));
 992     break;
 993
 994   case Instruction::Malloc:
 995     Code = bitc::FUNC_CODE_INST_MALLOC;
 996     Vals.push_back(VE.getTypeID(I.getType()));
 997     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
 998     Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
 999     break;
1000
1001   case Instruction::Free:
1002     Code = bitc::FUNC_CODE_INST_FREE;
1003     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1004     break;
1005
1006   case Instruction::Alloca:
1007     Code = bitc::FUNC_CODE_INST_ALLOCA;
1008     Vals.push_back(VE.getTypeID(I.getType()));
1009     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1010     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1011     break;
1012
1013   case Instruction::Load:
1014     Code = bitc::FUNC_CODE_INST_LOAD;
1015     if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1016       AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1017
1018     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1019     Vals.push_back(cast<LoadInst>(I).isVolatile());
1020     break;
1021   case Instruction::Store:
1022     Code = bitc::FUNC_CODE_INST_STORE2;
1023     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1024     Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
1025     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1026     Vals.push_back(cast<StoreInst>(I).isVolatile());
1027     break;
1028   case Instruction::Call: {
1029     const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
1030     const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1031
1032     Code = bitc::FUNC_CODE_INST_CALL;
1033
1034     const CallInst *CI = cast<CallInst>(&I);
1035     Vals.push_back(VE.getAttributeID(CI->getAttributes()));
1036     Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
1037     PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
1038
1039     // Emit value #'s for the fixed parameters.
1040     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1041       Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
1042
1043     // Emit type/value pairs for varargs params.
1044     if (FTy->isVarArg()) {
1045       unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1046       for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1047            i != e; ++i)
1048         PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1049     }
1050     break;
1051   }
1052   case Instruction::VAArg:
1053     Code = bitc::FUNC_CODE_INST_VAARG;
1054     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1055     Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1056     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1057     break;
1058   }
1059
1060   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1061   Vals.clear();
1062 }
1063
1064 // Emit names for globals/functions etc.
1065 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1066                                   const ValueEnumerator &VE,
1067                                   BitstreamWriter &Stream) {
1068   if (VST.empty()) return;
1069   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1070
1071   // FIXME: Set up the abbrev, we know how many values there are!
1072   // FIXME: We know if the type names can use 7-bit ascii.
1073   SmallVector<unsigned, 64> NameVals;
1074
1075   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1076        SI != SE; ++SI) {
1077
1078     const ValueName &Name = *SI;
1079
1080     // Figure out the encoding to use for the name.
1081     bool is7Bit = true;
1082     bool isChar6 = true;
1083     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1084          C != E; ++C) {
1085       if (isChar6)
1086         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1087       if ((unsigned char)*C & 128) {
1088         is7Bit = false;
1089         break;  // don't bother scanning the rest.
1090       }
1091     }
1092
1093     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1094
1095     // VST_ENTRY:   [valueid, namechar x N]
1096     // VST_BBENTRY: [bbid, namechar x N]
1097     unsigned Code;
1098     if (isa<BasicBlock>(SI->getValue())) {
1099       Code = bitc::VST_CODE_BBENTRY;
1100       if (isChar6)
1101         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1102     } else {
1103       Code = bitc::VST_CODE_ENTRY;
1104       if (isChar6)
1105         AbbrevToUse = VST_ENTRY_6_ABBREV;
1106       else if (is7Bit)
1107         AbbrevToUse = VST_ENTRY_7_ABBREV;
1108     }
1109
1110     NameVals.push_back(VE.getValueID(SI->getValue()));
1111     for (const char *P = Name.getKeyData(),
1112          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1113       NameVals.push_back((unsigned char)*P);
1114
1115     // Emit the finished record.
1116     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1117     NameVals.clear();
1118   }
1119   Stream.ExitBlock();
1120 }
1121
1122 /// WriteFunction - Emit a function body to the module stream.
1123 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1124                           BitstreamWriter &Stream) {
1125   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1126   VE.incorporateFunction(F);
1127
1128   SmallVector<unsigned, 64> Vals;
1129
1130   // Emit the number of basic blocks, so the reader can create them ahead of
1131   // time.
1132   Vals.push_back(VE.getBasicBlocks().size());
1133   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1134   Vals.clear();
1135
1136   // If there are function-local constants, emit them now.
1137   unsigned CstStart, CstEnd;
1138   VE.getFunctionConstantRange(CstStart, CstEnd);
1139   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1140
1141   // Keep a running idea of what the instruction ID is.
1142   unsigned InstID = CstEnd;
1143
1144   // Finally, emit all the instructions, in order.
1145   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1146     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1147          I != E; ++I) {
1148       WriteInstruction(*I, InstID, VE, Stream, Vals);
1149       if (I->getType() != Type::VoidTy)
1150         ++InstID;
1151     }
1152
1153   // Emit names for all the instructions etc.
1154   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1155
1156   VE.purgeFunction();
1157   Stream.ExitBlock();
1158 }
1159
1160 /// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1161 static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1162                                  const ValueEnumerator &VE,
1163                                  BitstreamWriter &Stream) {
1164   if (TST.empty()) return;
1165
1166   Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1167
1168   // 7-bit fixed width VST_CODE_ENTRY strings.
1169   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1170   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1171   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1172                             Log2_32_Ceil(VE.getTypes().size()+1)));
1173   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1174   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1175   unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1176
1177   SmallVector<unsigned, 64> NameVals;
1178
1179   for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1180        TI != TE; ++TI) {
1181     // TST_ENTRY: [typeid, namechar x N]
1182     NameVals.push_back(VE.getTypeID(TI->second));
1183
1184     const std::string &Str = TI->first;
1185     bool is7Bit = true;
1186     for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1187       NameVals.push_back((unsigned char)Str[i]);
1188       if (Str[i] & 128)
1189         is7Bit = false;
1190     }
1191
1192     // Emit the finished record.
1193     Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1194     NameVals.clear();
1195   }
1196
1197   Stream.ExitBlock();
1198 }
1199
1200 // Emit blockinfo, which defines the standard abbreviations etc.
1201 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1202   // We only want to emit block info records for blocks that have multiple
1203   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1204   // blocks can defined their abbrevs inline.
1205   Stream.EnterBlockInfoBlock(2);
1206
1207   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1208     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1209     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1210     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1211     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1212     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1213     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1214                                    Abbv) != VST_ENTRY_8_ABBREV)
1215       llvm_unreachable("Unexpected abbrev ordering!");
1216   }
1217
1218   { // 7-bit fixed width VST_ENTRY strings.
1219     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1220     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1223     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1224     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1225                                    Abbv) != VST_ENTRY_7_ABBREV)
1226       llvm_unreachable("Unexpected abbrev ordering!");
1227   }
1228   { // 6-bit char6 VST_ENTRY strings.
1229     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1230     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1231     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1233     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1234     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1235                                    Abbv) != VST_ENTRY_6_ABBREV)
1236       llvm_unreachable("Unexpected abbrev ordering!");
1237   }
1238   { // 6-bit char6 VST_BBENTRY strings.
1239     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1240     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1241     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1242     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1243     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1244     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1245                                    Abbv) != VST_BBENTRY_6_ABBREV)
1246       llvm_unreachable("Unexpected abbrev ordering!");
1247   }
1248
1249
1250
1251   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1252     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1253     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1254     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1255                               Log2_32_Ceil(VE.getTypes().size()+1)));
1256     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1257                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1258       llvm_unreachable("Unexpected abbrev ordering!");
1259   }
1260
1261   { // INTEGER abbrev for CONSTANTS_BLOCK.
1262     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1263     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1264     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1265     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1266                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1267       llvm_unreachable("Unexpected abbrev ordering!");
1268   }
1269
1270   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1271     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1272     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1273     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1274     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1275                               Log2_32_Ceil(VE.getTypes().size()+1)));
1276     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1277
1278     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1279                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1280       llvm_unreachable("Unexpected abbrev ordering!");
1281   }
1282   { // NULL abbrev for CONSTANTS_BLOCK.
1283     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1284     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1285     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1286                                    Abbv) != CONSTANTS_NULL_Abbrev)
1287       llvm_unreachable("Unexpected abbrev ordering!");
1288   }
1289
1290   // FIXME: This should only use space for first class types!
1291
1292   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1293     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1294     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1295     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1296     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1297     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1298     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1299                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1300       llvm_unreachable("Unexpected abbrev ordering!");
1301   }
1302   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1303     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1304     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1305     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1306     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1307     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1308     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1309                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1310       llvm_unreachable("Unexpected abbrev ordering!");
1311   }
1312   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1313     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1314     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1315     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1316     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1317     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1318     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1319     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1320                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1321       llvm_unreachable("Unexpected abbrev ordering!");
1322   }
1323   { // INST_CAST abbrev for FUNCTION_BLOCK.
1324     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1325     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1326     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1327     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1328                               Log2_32_Ceil(VE.getTypes().size()+1)));
1329     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1330     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1331                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1332       llvm_unreachable("Unexpected abbrev ordering!");
1333   }
1334
1335   { // INST_RET abbrev for FUNCTION_BLOCK.
1336     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1337     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1338     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1339                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1340       llvm_unreachable("Unexpected abbrev ordering!");
1341   }
1342   { // INST_RET abbrev for FUNCTION_BLOCK.
1343     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1344     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1345     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1346     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1347                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1348       llvm_unreachable("Unexpected abbrev ordering!");
1349   }
1350   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1351     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1352     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1353     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1354                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1355       llvm_unreachable("Unexpected abbrev ordering!");
1356   }
1357
1358   Stream.ExitBlock();
1359 }
1360
1361
1362 /// WriteModule - Emit the specified module to the bitstream.
1363 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1364   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1365
1366   // Emit the version number if it is non-zero.
1367   if (CurVersion) {
1368     SmallVector<unsigned, 1> Vals;
1369     Vals.push_back(CurVersion);
1370     Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1371   }
1372
1373   // Analyze the module, enumerating globals, functions, etc.
1374   ValueEnumerator VE(M);
1375
1376   // Emit blockinfo, which defines the standard abbreviations etc.
1377   WriteBlockInfo(VE, Stream);
1378
1379   // Emit information about parameter attributes.
1380   WriteAttributeTable(VE, Stream);
1381
1382   // Emit information describing all of the types in the module.
1383   WriteTypeTable(VE, Stream);
1384
1385   // Emit top-level description of module, including target triple, inline asm,
1386   // descriptors for global variables, and function prototype info.
1387   WriteModuleInfo(M, VE, Stream);
1388
1389   // Emit constants.
1390   WriteModuleConstants(VE, Stream);
1391
1392   // Emit metadata.
1393   WriteModuleMetadata(VE, Stream);
1394
1395   // Emit function bodies.
1396   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1397     if (!I->isDeclaration())
1398       WriteFunction(*I, VE, Stream);
1399
1400   // Emit the type symbol table information.
1401   WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1402
1403   // Emit names for globals/functions etc.
1404   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1405
1406   Stream.ExitBlock();
1407 }
1408
1409 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1410 /// header and trailer to make it compatible with the system archiver.  To do
1411 /// this we emit the following header, and then emit a trailer that pads the
1412 /// file out to be a multiple of 16 bytes.
1413 ///
1414 /// struct bc_header {
1415 ///   uint32_t Magic;         // 0x0B17C0DE
1416 ///   uint32_t Version;       // Version, currently always 0.
1417 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1418 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1419 ///   uint32_t CPUType;       // CPU specifier.
1420 ///   ... potentially more later ...
1421 /// };
1422 enum {
1423   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1424   DarwinBCHeaderSize = 5*4
1425 };
1426
1427 static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1428                                const std::string &TT) {
1429   unsigned CPUType = ~0U;
1430
1431   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1432   // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1433   // specific constants here because they are implicitly part of the Darwin ABI.
1434   enum {
1435     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1436     DARWIN_CPU_TYPE_X86        = 7,
1437     DARWIN_CPU_TYPE_POWERPC    = 18
1438   };
1439
1440   if (TT.find("x86_64-") == 0)
1441     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1442   else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1443            TT[4] == '-' && TT[1] - '3' < 6)
1444     CPUType = DARWIN_CPU_TYPE_X86;
1445   else if (TT.find("powerpc-") == 0)
1446     CPUType = DARWIN_CPU_TYPE_POWERPC;
1447   else if (TT.find("powerpc64-") == 0)
1448     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1449
1450   // Traditional Bitcode starts after header.
1451   unsigned BCOffset = DarwinBCHeaderSize;
1452
1453   Stream.Emit(0x0B17C0DE, 32);
1454   Stream.Emit(0         , 32);  // Version.
1455   Stream.Emit(BCOffset  , 32);
1456   Stream.Emit(0         , 32);  // Filled in later.
1457   Stream.Emit(CPUType   , 32);
1458 }
1459
1460 /// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1461 /// finalize the header.
1462 static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1463   // Update the size field in the header.
1464   Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1465
1466   // If the file is not a multiple of 16 bytes, insert dummy padding.
1467   while (BufferSize & 15) {
1468     Stream.Emit(0, 8);
1469     ++BufferSize;
1470   }
1471 }
1472
1473
1474 /// WriteBitcodeToFile - Write the specified module to the specified output
1475 /// stream.
1476 void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1477   raw_os_ostream RawOut(Out);
1478   // If writing to stdout, set binary mode.
1479   if (llvm::cout == Out)
1480     sys::Program::ChangeStdoutToBinary();
1481   WriteBitcodeToFile(M, RawOut);
1482 }
1483
1484 /// WriteBitcodeToFile - Write the specified module to the specified output
1485 /// stream.
1486 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1487   std::vector<unsigned char> Buffer;
1488   BitstreamWriter Stream(Buffer);
1489
1490   Buffer.reserve(256*1024);
1491
1492   WriteBitcodeToStream( M, Stream );
1493
1494   // If writing to stdout, set binary mode.
1495   if (&llvm::outs() == &Out)
1496     sys::Program::ChangeStdoutToBinary();
1497
1498   // Write the generated bitstream to "Out".
1499   Out.write((char*)&Buffer.front(), Buffer.size());
1500
1501   // Make sure it hits disk now.
1502   Out.flush();
1503 }
1504
1505 /// WriteBitcodeToStream - Write the specified module to the specified output
1506 /// stream.
1507 void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1508   // If this is darwin, emit a file header and trailer if needed.
1509   bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1510   if (isDarwin)
1511     EmitDarwinBCHeader(Stream, M->getTargetTriple());
1512
1513   // Emit the file header.
1514   Stream.Emit((unsigned)'B', 8);
1515   Stream.Emit((unsigned)'C', 8);
1516   Stream.Emit(0x0, 4);
1517   Stream.Emit(0xC, 4);
1518   Stream.Emit(0xE, 4);
1519   Stream.Emit(0xD, 4);
1520
1521   // Emit the module.
1522   WriteModule(M, Stream);
1523
1524   if (isDarwin)
1525     EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1526 }