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 "ValueEnumerator.h"
  16 #include "llvm/ADT/Triple.h"
  17 #include "llvm/Bitcode/BitstreamWriter.h"
  18 #include "llvm/Bitcode/LLVMBitCodes.h"
  19 #include "llvm/IR/Constants.h"
  20 #include "llvm/IR/DerivedTypes.h"
  21 #include "llvm/IR/InlineAsm.h"
  22 #include "llvm/IR/Instructions.h"
  23 #include "llvm/IR/Module.h"
  24 #include "llvm/IR/Operator.h"
  25 #include "llvm/IR/ValueSymbolTable.h"
  26 #include "llvm/Support/CommandLine.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Support/MathExtras.h"
  29 #include "llvm/Support/Program.h"
  30 #include "llvm/Support/raw_ostream.h"
  31 #include <cctype>
  32 #include <map>
  33 using namespace llvm;
  34
  35 static cl::opt<bool>
  36 EnablePreserveUseListOrdering("enable-bc-uselist-preserve",
  37                               cl::desc("Turn on experimental support for "
  38                                        "use-list order preservation."),
  39                               cl::init(false), cl::Hidden);
  40
  41 /// These are manifest constants used by the bitcode writer. They do not need to
  42 /// be kept in sync with the reader, but need to be consistent within this file.
  43 enum {
  44   // VALUE_SYMTAB_BLOCK abbrev id's.
  45   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  46   VST_ENTRY_7_ABBREV,
  47   VST_ENTRY_6_ABBREV,
  48   VST_BBENTRY_6_ABBREV,
  49
  50   // CONSTANTS_BLOCK abbrev id's.
  51   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  52   CONSTANTS_INTEGER_ABBREV,
  53   CONSTANTS_CE_CAST_Abbrev,
  54   CONSTANTS_NULL_Abbrev,
  55
  56   // FUNCTION_BLOCK abbrev id's.
  57   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
  58   FUNCTION_INST_BINOP_ABBREV,
  59   FUNCTION_INST_BINOP_FLAGS_ABBREV,
  60   FUNCTION_INST_CAST_ABBREV,
  61   FUNCTION_INST_RET_VOID_ABBREV,
  62   FUNCTION_INST_RET_VAL_ABBREV,
  63   FUNCTION_INST_UNREACHABLE_ABBREV,
  64
  65   // SwitchInst Magic
  66   SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
  67 };
  68
  69 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
  70   switch (Opcode) {
  71   default: llvm_unreachable("Unknown cast instruction!");
  72   case Instruction::Trunc   : return bitc::CAST_TRUNC;
  73   case Instruction::ZExt    : return bitc::CAST_ZEXT;
  74   case Instruction::SExt    : return bitc::CAST_SEXT;
  75   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
  76   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
  77   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
  78   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
  79   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
  80   case Instruction::FPExt   : return bitc::CAST_FPEXT;
  81   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
  82   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
  83   case Instruction::BitCast : return bitc::CAST_BITCAST;
  84   }
  85 }
  86
  87 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
  88   switch (Opcode) {
  89   default: llvm_unreachable("Unknown binary instruction!");
  90   case Instruction::Add:
  91   case Instruction::FAdd: return bitc::BINOP_ADD;
  92   case Instruction::Sub:
  93   case Instruction::FSub: return bitc::BINOP_SUB;
  94   case Instruction::Mul:
  95   case Instruction::FMul: return bitc::BINOP_MUL;
  96   case Instruction::UDiv: return bitc::BINOP_UDIV;
  97   case Instruction::FDiv:
  98   case Instruction::SDiv: return bitc::BINOP_SDIV;
  99   case Instruction::URem: return bitc::BINOP_UREM;
 100   case Instruction::FRem:
 101   case Instruction::SRem: return bitc::BINOP_SREM;
 102   case Instruction::Shl:  return bitc::BINOP_SHL;
 103   case Instruction::LShr: return bitc::BINOP_LSHR;
 104   case Instruction::AShr: return bitc::BINOP_ASHR;
 105   case Instruction::And:  return bitc::BINOP_AND;
 106   case Instruction::Or:   return bitc::BINOP_OR;
 107   case Instruction::Xor:  return bitc::BINOP_XOR;
 108   }
 109 }
 110
 111 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
 112   switch (Op) {
 113   default: llvm_unreachable("Unknown RMW operation!");
 114   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
 115   case AtomicRMWInst::Add: return bitc::RMW_ADD;
 116   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
 117   case AtomicRMWInst::And: return bitc::RMW_AND;
 118   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
 119   case AtomicRMWInst::Or: return bitc::RMW_OR;
 120   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
 121   case AtomicRMWInst::Max: return bitc::RMW_MAX;
 122   case AtomicRMWInst::Min: return bitc::RMW_MIN;
 123   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
 124   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
 125   }
 126 }
 127
 128 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
 129   switch (Ordering) {
 130   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
 131   case Unordered: return bitc::ORDERING_UNORDERED;
 132   case Monotonic: return bitc::ORDERING_MONOTONIC;
 133   case Acquire: return bitc::ORDERING_ACQUIRE;
 134   case Release: return bitc::ORDERING_RELEASE;
 135   case AcquireRelease: return bitc::ORDERING_ACQREL;
 136   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
 137   }
 138   llvm_unreachable("Invalid ordering");
 139 }
 140
 141 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
 142   switch (SynchScope) {
 143   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
 144   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
 145   }
 146   llvm_unreachable("Invalid synch scope");
 147 }
 148
 149 static void WriteStringRecord(unsigned Code, StringRef Str,
 150                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
 151   SmallVector<unsigned, 64> Vals;
 152
 153   // Code: [strchar x N]
 154   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
 155     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
 156       AbbrevToUse = 0;
 157     Vals.push_back(Str[i]);
 158   }
 159
 160   // Emit the finished record.
 161   Stream.EmitRecord(Code, Vals, AbbrevToUse);
 162 }
 163
 164 // Emit information about parameter attributes.
 165 static void WriteAttributeTable(const ValueEnumerator &VE,
 166                                 BitstreamWriter &Stream) {
 167   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 168   if (Attrs.empty()) return;
 169
 170   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 171
 172   SmallVector<uint64_t, 64> Record;
 173   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 174     const AttributeSet &A = Attrs[i];
 175     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
 176       unsigned Index = A.getSlotIndex(i);
 177       Record.push_back(Index);
 178       Record.push_back(AttributeFuncs::
 179                        encodeLLVMAttributesForBitcode(A.getSlotAttributes(i),
 180                                                       Index));
 181     }
 182
 183     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
 184     Record.clear();
 185   }
 186
 187   Stream.ExitBlock();
 188 }
 189
 190 /// WriteTypeTable - Write out the type table for a module.
 191 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 192   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 193
 194   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 195   SmallVector<uint64_t, 64> TypeVals;
 196
 197   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 198
 199   // Abbrev for TYPE_CODE_POINTER.
 200   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 201   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 202   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 203   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 204   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 205
 206   // Abbrev for TYPE_CODE_FUNCTION.
 207   Abbv = new BitCodeAbbrev();
 208   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 209   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 210   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 211   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 212
 213   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 214
 215   // Abbrev for TYPE_CODE_STRUCT_ANON.
 216   Abbv = new BitCodeAbbrev();
 217   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 218   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 219   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 220   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 221
 222   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 223
 224   // Abbrev for TYPE_CODE_STRUCT_NAME.
 225   Abbv = new BitCodeAbbrev();
 226   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 227   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 228   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 229   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 230
 231   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 232   Abbv = new BitCodeAbbrev();
 233   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 234   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 235   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 236   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 237
 238   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 239
 240   // Abbrev for TYPE_CODE_ARRAY.
 241   Abbv = new BitCodeAbbrev();
 242   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 243   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 244   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 245
 246   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 247
 248   // Emit an entry count so the reader can reserve space.
 249   TypeVals.push_back(TypeList.size());
 250   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 251   TypeVals.clear();
 252
 253   // Loop over all of the types, emitting each in turn.
 254   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 255     Type *T = TypeList[i];
 256     int AbbrevToUse = 0;
 257     unsigned Code = 0;
 258
 259     switch (T->getTypeID()) {
 260     default: llvm_unreachable("Unknown type!");
 261     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 262     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 263     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 264     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 265     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 266     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 267     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 268     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 269     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 270     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 271     case Type::IntegerTyID:
 272       // INTEGER: [width]
 273       Code = bitc::TYPE_CODE_INTEGER;
 274       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 275       break;
 276     case Type::PointerTyID: {
 277       PointerType *PTy = cast<PointerType>(T);
 278       // POINTER: [pointee type, address space]
 279       Code = bitc::TYPE_CODE_POINTER;
 280       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 281       unsigned AddressSpace = PTy->getAddressSpace();
 282       TypeVals.push_back(AddressSpace);
 283       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 284       break;
 285     }
 286     case Type::FunctionTyID: {
 287       FunctionType *FT = cast<FunctionType>(T);
 288       // FUNCTION: [isvararg, retty, paramty x N]
 289       Code = bitc::TYPE_CODE_FUNCTION;
 290       TypeVals.push_back(FT->isVarArg());
 291       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 292       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 293         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 294       AbbrevToUse = FunctionAbbrev;
 295       break;
 296     }
 297     case Type::StructTyID: {
 298       StructType *ST = cast<StructType>(T);
 299       // STRUCT: [ispacked, eltty x N]
 300       TypeVals.push_back(ST->isPacked());
 301       // Output all of the element types.
 302       for (StructType::element_iterator I = ST->element_begin(),
 303            E = ST->element_end(); I != E; ++I)
 304         TypeVals.push_back(VE.getTypeID(*I));
 305
 306       if (ST->isLiteral()) {
 307         Code = bitc::TYPE_CODE_STRUCT_ANON;
 308         AbbrevToUse = StructAnonAbbrev;
 309       } else {
 310         if (ST->isOpaque()) {
 311           Code = bitc::TYPE_CODE_OPAQUE;
 312         } else {
 313           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 314           AbbrevToUse = StructNamedAbbrev;
 315         }
 316
 317         // Emit the name if it is present.
 318         if (!ST->getName().empty())
 319           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 320                             StructNameAbbrev, Stream);
 321       }
 322       break;
 323     }
 324     case Type::ArrayTyID: {
 325       ArrayType *AT = cast<ArrayType>(T);
 326       // ARRAY: [numelts, eltty]
 327       Code = bitc::TYPE_CODE_ARRAY;
 328       TypeVals.push_back(AT->getNumElements());
 329       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 330       AbbrevToUse = ArrayAbbrev;
 331       break;
 332     }
 333     case Type::VectorTyID: {
 334       VectorType *VT = cast<VectorType>(T);
 335       // VECTOR [numelts, eltty]
 336       Code = bitc::TYPE_CODE_VECTOR;
 337       TypeVals.push_back(VT->getNumElements());
 338       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 339       break;
 340     }
 341     }
 342
 343     // Emit the finished record.
 344     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 345     TypeVals.clear();
 346   }
 347
 348   Stream.ExitBlock();
 349 }
 350
 351 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 352   switch (GV->getLinkage()) {
 353   case GlobalValue::ExternalLinkage:                 return 0;
 354   case GlobalValue::WeakAnyLinkage:                  return 1;
 355   case GlobalValue::AppendingLinkage:                return 2;
 356   case GlobalValue::InternalLinkage:                 return 3;
 357   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 358   case GlobalValue::DLLImportLinkage:                return 5;
 359   case GlobalValue::DLLExportLinkage:                return 6;
 360   case GlobalValue::ExternalWeakLinkage:             return 7;
 361   case GlobalValue::CommonLinkage:                   return 8;
 362   case GlobalValue::PrivateLinkage:                  return 9;
 363   case GlobalValue::WeakODRLinkage:                  return 10;
 364   case GlobalValue::LinkOnceODRLinkage:              return 11;
 365   case GlobalValue::AvailableExternallyLinkage:      return 12;
 366   case GlobalValue::LinkerPrivateLinkage:            return 13;
 367   case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
 368   case GlobalValue::LinkOnceODRAutoHideLinkage:      return 15;
 369   }
 370   llvm_unreachable("Invalid linkage");
 371 }
 372
 373 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 374   switch (GV->getVisibility()) {
 375   case GlobalValue::DefaultVisibility:   return 0;
 376   case GlobalValue::HiddenVisibility:    return 1;
 377   case GlobalValue::ProtectedVisibility: return 2;
 378   }
 379   llvm_unreachable("Invalid visibility");
 380 }
 381
 382 static unsigned getEncodedThreadLocalMode(const GlobalVariable *GV) {
 383   switch (GV->getThreadLocalMode()) {
 384     case GlobalVariable::NotThreadLocal:         return 0;
 385     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 386     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 387     case GlobalVariable::InitialExecTLSModel:    return 3;
 388     case GlobalVariable::LocalExecTLSModel:      return 4;
 389   }
 390   llvm_unreachable("Invalid TLS model");
 391 }
 392
 393 // Emit top-level description of module, including target triple, inline asm,
 394 // descriptors for global variables, and function prototype info.
 395 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 396                             BitstreamWriter &Stream) {
 397   // Emit various pieces of data attached to a module.
 398   if (!M->getTargetTriple().empty())
 399     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 400                       0/*TODO*/, Stream);
 401   if (!M->getDataLayout().empty())
 402     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 403                       0/*TODO*/, Stream);
 404   if (!M->getModuleInlineAsm().empty())
 405     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 406                       0/*TODO*/, Stream);
 407
 408   // Emit information about sections and GC, computing how many there are. Also
 409   // compute the maximum alignment value.
 410   std::map<std::string, unsigned> SectionMap;
 411   std::map<std::string, unsigned> GCMap;
 412   unsigned MaxAlignment = 0;
 413   unsigned MaxGlobalType = 0;
 414   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 415        GV != E; ++GV) {
 416     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 417     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 418     if (GV->hasSection()) {
 419       // Give section names unique ID's.
 420       unsigned &Entry = SectionMap[GV->getSection()];
 421       if (!Entry) {
 422         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 423                           0/*TODO*/, Stream);
 424         Entry = SectionMap.size();
 425       }
 426     }
 427   }
 428   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 429     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 430     if (F->hasSection()) {
 431       // Give section names unique ID's.
 432       unsigned &Entry = SectionMap[F->getSection()];
 433       if (!Entry) {
 434         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 435                           0/*TODO*/, Stream);
 436         Entry = SectionMap.size();
 437       }
 438     }
 439     if (F->hasGC()) {
 440       // Same for GC names.
 441       unsigned &Entry = GCMap[F->getGC()];
 442       if (!Entry) {
 443         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 444                           0/*TODO*/, Stream);
 445         Entry = GCMap.size();
 446       }
 447     }
 448   }
 449
 450   // Emit abbrev for globals, now that we know # sections and max alignment.
 451   unsigned SimpleGVarAbbrev = 0;
 452   if (!M->global_empty()) {
 453     // Add an abbrev for common globals with no visibility or thread localness.
 454     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 455     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 456     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 457                               Log2_32_Ceil(MaxGlobalType+1)));
 458     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 459     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 460     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 461     if (MaxAlignment == 0)                                      // Alignment.
 462       Abbv->Add(BitCodeAbbrevOp(0));
 463     else {
 464       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 465       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 466                                Log2_32_Ceil(MaxEncAlignment+1)));
 467     }
 468     if (SectionMap.empty())                                    // Section.
 469       Abbv->Add(BitCodeAbbrevOp(0));
 470     else
 471       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 472                                Log2_32_Ceil(SectionMap.size()+1)));
 473     // Don't bother emitting vis + thread local.
 474     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 475   }
 476
 477   // Emit the global variable information.
 478   SmallVector<unsigned, 64> Vals;
 479   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 480        GV != E; ++GV) {
 481     unsigned AbbrevToUse = 0;
 482
 483     // GLOBALVAR: [type, isconst, initid,
 484     //             linkage, alignment, section, visibility, threadlocal,
 485     //             unnamed_addr]
 486     Vals.push_back(VE.getTypeID(GV->getType()));
 487     Vals.push_back(GV->isConstant());
 488     Vals.push_back(GV->isDeclaration() ? 0 :
 489                    (VE.getValueID(GV->getInitializer()) + 1));
 490     Vals.push_back(getEncodedLinkage(GV));
 491     Vals.push_back(Log2_32(GV->getAlignment())+1);
 492     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 493     if (GV->isThreadLocal() ||
 494         GV->getVisibility() != GlobalValue::DefaultVisibility ||
 495         GV->hasUnnamedAddr()) {
 496       Vals.push_back(getEncodedVisibility(GV));
 497       Vals.push_back(getEncodedThreadLocalMode(GV));
 498       Vals.push_back(GV->hasUnnamedAddr());
 499     } else {
 500       AbbrevToUse = SimpleGVarAbbrev;
 501     }
 502
 503     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 504     Vals.clear();
 505   }
 506
 507   // Emit the function proto information.
 508   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 509     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 510     //             section, visibility, gc, unnamed_addr]
 511     Vals.push_back(VE.getTypeID(F->getType()));
 512     Vals.push_back(F->getCallingConv());
 513     Vals.push_back(F->isDeclaration());
 514     Vals.push_back(getEncodedLinkage(F));
 515     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 516     Vals.push_back(Log2_32(F->getAlignment())+1);
 517     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 518     Vals.push_back(getEncodedVisibility(F));
 519     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 520     Vals.push_back(F->hasUnnamedAddr());
 521
 522     unsigned AbbrevToUse = 0;
 523     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 524     Vals.clear();
 525   }
 526
 527   // Emit the alias information.
 528   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 529        AI != E; ++AI) {
 530     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 531     Vals.push_back(VE.getTypeID(AI->getType()));
 532     Vals.push_back(VE.getValueID(AI->getAliasee()));
 533     Vals.push_back(getEncodedLinkage(AI));
 534     Vals.push_back(getEncodedVisibility(AI));
 535     unsigned AbbrevToUse = 0;
 536     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 537     Vals.clear();
 538   }
 539 }
 540
 541 static uint64_t GetOptimizationFlags(const Value *V) {
 542   uint64_t Flags = 0;
 543
 544   if (const OverflowingBinaryOperator *OBO =
 545         dyn_cast<OverflowingBinaryOperator>(V)) {
 546     if (OBO->hasNoSignedWrap())
 547       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 548     if (OBO->hasNoUnsignedWrap())
 549       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 550   } else if (const PossiblyExactOperator *PEO =
 551                dyn_cast<PossiblyExactOperator>(V)) {
 552     if (PEO->isExact())
 553       Flags |= 1 << bitc::PEO_EXACT;
 554   } else if (const FPMathOperator *FPMO =
 555              dyn_cast<const FPMathOperator>(V)) {
 556     if (FPMO->hasUnsafeAlgebra())
 557       Flags |= FastMathFlags::UnsafeAlgebra;
 558     if (FPMO->hasNoNaNs())
 559       Flags |= FastMathFlags::NoNaNs;
 560     if (FPMO->hasNoInfs())
 561       Flags |= FastMathFlags::NoInfs;
 562     if (FPMO->hasNoSignedZeros())
 563       Flags |= FastMathFlags::NoSignedZeros;
 564     if (FPMO->hasAllowReciprocal())
 565       Flags |= FastMathFlags::AllowReciprocal;
 566   }
 567
 568   return Flags;
 569 }
 570
 571 static void WriteMDNode(const MDNode *N,
 572                         const ValueEnumerator &VE,
 573                         BitstreamWriter &Stream,
 574                         SmallVector<uint64_t, 64> &Record) {
 575   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 576     if (N->getOperand(i)) {
 577       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 578       Record.push_back(VE.getValueID(N->getOperand(i)));
 579     } else {
 580       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 581       Record.push_back(0);
 582     }
 583   }
 584   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 585                                            bitc::METADATA_NODE;
 586   Stream.EmitRecord(MDCode, Record, 0);
 587   Record.clear();
 588 }
 589
 590 static void WriteModuleMetadata(const Module *M,
 591                                 const ValueEnumerator &VE,
 592                                 BitstreamWriter &Stream) {
 593   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 594   bool StartedMetadataBlock = false;
 595   unsigned MDSAbbrev = 0;
 596   SmallVector<uint64_t, 64> Record;
 597   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 598
 599     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 600       if (!N->isFunctionLocal() || !N->getFunction()) {
 601         if (!StartedMetadataBlock) {
 602           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 603           StartedMetadataBlock = true;
 604         }
 605         WriteMDNode(N, VE, Stream, Record);
 606       }
 607     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 608       if (!StartedMetadataBlock)  {
 609         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 610
 611         // Abbrev for METADATA_STRING.
 612         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 613         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 614         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 615         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 616         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 617         StartedMetadataBlock = true;
 618       }
 619
 620       // Code: [strchar x N]
 621       Record.append(MDS->begin(), MDS->end());
 622
 623       // Emit the finished record.
 624       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 625       Record.clear();
 626     }
 627   }
 628
 629   // Write named metadata.
 630   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 631        E = M->named_metadata_end(); I != E; ++I) {
 632     const NamedMDNode *NMD = I;
 633     if (!StartedMetadataBlock)  {
 634       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 635       StartedMetadataBlock = true;
 636     }
 637
 638     // Write name.
 639     StringRef Str = NMD->getName();
 640     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 641       Record.push_back(Str[i]);
 642     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 643     Record.clear();
 644
 645     // Write named metadata operands.
 646     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 647       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 648     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 649     Record.clear();
 650   }
 651
 652   if (StartedMetadataBlock)
 653     Stream.ExitBlock();
 654 }
 655
 656 static void WriteFunctionLocalMetadata(const Function &F,
 657                                        const ValueEnumerator &VE,
 658                                        BitstreamWriter &Stream) {
 659   bool StartedMetadataBlock = false;
 660   SmallVector<uint64_t, 64> Record;
 661   const SmallVector<const MDNode *, 8> &Vals = VE.getFunctionLocalMDValues();
 662   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 663     if (const MDNode *N = Vals[i])
 664       if (N->isFunctionLocal() && N->getFunction() == &F) {
 665         if (!StartedMetadataBlock) {
 666           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 667           StartedMetadataBlock = true;
 668         }
 669         WriteMDNode(N, VE, Stream, Record);
 670       }
 671
 672   if (StartedMetadataBlock)
 673     Stream.ExitBlock();
 674 }
 675
 676 static void WriteMetadataAttachment(const Function &F,
 677                                     const ValueEnumerator &VE,
 678                                     BitstreamWriter &Stream) {
 679   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 680
 681   SmallVector<uint64_t, 64> Record;
 682
 683   // Write metadata attachments
 684   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 685   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 686
 687   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 688     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 689          I != E; ++I) {
 690       MDs.clear();
 691       I->getAllMetadataOtherThanDebugLoc(MDs);
 692
 693       // If no metadata, ignore instruction.
 694       if (MDs.empty()) continue;
 695
 696       Record.push_back(VE.getInstructionID(I));
 697
 698       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 699         Record.push_back(MDs[i].first);
 700         Record.push_back(VE.getValueID(MDs[i].second));
 701       }
 702       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 703       Record.clear();
 704     }
 705
 706   Stream.ExitBlock();
 707 }
 708
 709 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 710   SmallVector<uint64_t, 64> Record;
 711
 712   // Write metadata kinds
 713   // METADATA_KIND - [n x [id, name]]
 714   SmallVector<StringRef, 8> Names;
 715   M->getMDKindNames(Names);
 716
 717   if (Names.empty()) return;
 718
 719   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 720
 721   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 722     Record.push_back(MDKindID);
 723     StringRef KName = Names[MDKindID];
 724     Record.append(KName.begin(), KName.end());
 725
 726     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 727     Record.clear();
 728   }
 729
 730   Stream.ExitBlock();
 731 }
 732
 733 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 734   if ((int64_t)V >= 0)
 735     Vals.push_back(V << 1);
 736   else
 737     Vals.push_back((-V << 1) | 1);
 738 }
 739
 740 static void EmitAPInt(SmallVectorImpl<uint64_t> &Vals,
 741                       unsigned &Code, unsigned &AbbrevToUse, const APInt &Val,
 742                       bool EmitSizeForWideNumbers = false
 743                       ) {
 744   if (Val.getBitWidth() <= 64) {
 745     uint64_t V = Val.getSExtValue();
 746     emitSignedInt64(Vals, V);
 747     Code = bitc::CST_CODE_INTEGER;
 748     AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 749   } else {
 750     // Wide integers, > 64 bits in size.
 751     // We have an arbitrary precision integer value to write whose
 752     // bit width is > 64. However, in canonical unsigned integer
 753     // format it is likely that the high bits are going to be zero.
 754     // So, we only write the number of active words.
 755     unsigned NWords = Val.getActiveWords();
 756
 757     if (EmitSizeForWideNumbers)
 758       Vals.push_back(NWords);
 759
 760     const uint64_t *RawWords = Val.getRawData();
 761     for (unsigned i = 0; i != NWords; ++i) {
 762       emitSignedInt64(Vals, RawWords[i]);
 763     }
 764     Code = bitc::CST_CODE_WIDE_INTEGER;
 765   }
 766 }
 767
 768 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 769                            const ValueEnumerator &VE,
 770                            BitstreamWriter &Stream, bool isGlobal) {
 771   if (FirstVal == LastVal) return;
 772
 773   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 774
 775   unsigned AggregateAbbrev = 0;
 776   unsigned String8Abbrev = 0;
 777   unsigned CString7Abbrev = 0;
 778   unsigned CString6Abbrev = 0;
 779   // If this is a constant pool for the module, emit module-specific abbrevs.
 780   if (isGlobal) {
 781     // Abbrev for CST_CODE_AGGREGATE.
 782     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 783     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 784     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 785     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 786     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 787
 788     // Abbrev for CST_CODE_STRING.
 789     Abbv = new BitCodeAbbrev();
 790     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 791     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 792     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 793     String8Abbrev = Stream.EmitAbbrev(Abbv);
 794     // Abbrev for CST_CODE_CSTRING.
 795     Abbv = new BitCodeAbbrev();
 796     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 797     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 798     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 799     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 800     // Abbrev for CST_CODE_CSTRING.
 801     Abbv = new BitCodeAbbrev();
 802     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 803     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 804     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 805     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 806   }
 807
 808   SmallVector<uint64_t, 64> Record;
 809
 810   const ValueEnumerator::ValueList &Vals = VE.getValues();
 811   Type *LastTy = 0;
 812   for (unsigned i = FirstVal; i != LastVal; ++i) {
 813     const Value *V = Vals[i].first;
 814     // If we need to switch types, do so now.
 815     if (V->getType() != LastTy) {
 816       LastTy = V->getType();
 817       Record.push_back(VE.getTypeID(LastTy));
 818       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 819                         CONSTANTS_SETTYPE_ABBREV);
 820       Record.clear();
 821     }
 822
 823     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 824       Record.push_back(unsigned(IA->hasSideEffects()) |
 825                        unsigned(IA->isAlignStack()) << 1 |
 826                        unsigned(IA->getDialect()&1) << 2);
 827
 828       // Add the asm string.
 829       const std::string &AsmStr = IA->getAsmString();
 830       Record.push_back(AsmStr.size());
 831       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 832         Record.push_back(AsmStr[i]);
 833
 834       // Add the constraint string.
 835       const std::string &ConstraintStr = IA->getConstraintString();
 836       Record.push_back(ConstraintStr.size());
 837       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 838         Record.push_back(ConstraintStr[i]);
 839       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 840       Record.clear();
 841       continue;
 842     }
 843     const Constant *C = cast<Constant>(V);
 844     unsigned Code = -1U;
 845     unsigned AbbrevToUse = 0;
 846     if (C->isNullValue()) {
 847       Code = bitc::CST_CODE_NULL;
 848     } else if (isa<UndefValue>(C)) {
 849       Code = bitc::CST_CODE_UNDEF;
 850     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 851       EmitAPInt(Record, Code, AbbrevToUse, IV->getValue());
 852     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 853       Code = bitc::CST_CODE_FLOAT;
 854       Type *Ty = CFP->getType();
 855       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 856         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 857       } else if (Ty->isX86_FP80Ty()) {
 858         // api needed to prevent premature destruction
 859         // bits are not in the same order as a normal i80 APInt, compensate.
 860         APInt api = CFP->getValueAPF().bitcastToAPInt();
 861         const uint64_t *p = api.getRawData();
 862         Record.push_back((p[1] << 48) | (p[0] >> 16));
 863         Record.push_back(p[0] & 0xffffLL);
 864       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 865         APInt api = CFP->getValueAPF().bitcastToAPInt();
 866         const uint64_t *p = api.getRawData();
 867         Record.push_back(p[0]);
 868         Record.push_back(p[1]);
 869       } else {
 870         assert (0 && "Unknown FP type!");
 871       }
 872     } else if (isa<ConstantDataSequential>(C) &&
 873                cast<ConstantDataSequential>(C)->isString()) {
 874       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 875       // Emit constant strings specially.
 876       unsigned NumElts = Str->getNumElements();
 877       // If this is a null-terminated string, use the denser CSTRING encoding.
 878       if (Str->isCString()) {
 879         Code = bitc::CST_CODE_CSTRING;
 880         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 881       } else {
 882         Code = bitc::CST_CODE_STRING;
 883         AbbrevToUse = String8Abbrev;
 884       }
 885       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 886       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 887       for (unsigned i = 0; i != NumElts; ++i) {
 888         unsigned char V = Str->getElementAsInteger(i);
 889         Record.push_back(V);
 890         isCStr7 &= (V & 128) == 0;
 891         if (isCStrChar6)
 892           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 893       }
 894
 895       if (isCStrChar6)
 896         AbbrevToUse = CString6Abbrev;
 897       else if (isCStr7)
 898         AbbrevToUse = CString7Abbrev;
 899     } else if (const ConstantDataSequential *CDS =
 900                   dyn_cast<ConstantDataSequential>(C)) {
 901       Code = bitc::CST_CODE_DATA;
 902       Type *EltTy = CDS->getType()->getElementType();
 903       if (isa<IntegerType>(EltTy)) {
 904         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
 905           Record.push_back(CDS->getElementAsInteger(i));
 906       } else if (EltTy->isFloatTy()) {
 907         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 908           union { float F; uint32_t I; };
 909           F = CDS->getElementAsFloat(i);
 910           Record.push_back(I);
 911         }
 912       } else {
 913         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
 914         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 915           union { double F; uint64_t I; };
 916           F = CDS->getElementAsDouble(i);
 917           Record.push_back(I);
 918         }
 919       }
 920     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
 921                isa<ConstantVector>(C)) {
 922       Code = bitc::CST_CODE_AGGREGATE;
 923       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 924         Record.push_back(VE.getValueID(C->getOperand(i)));
 925       AbbrevToUse = AggregateAbbrev;
 926     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
 927       switch (CE->getOpcode()) {
 928       default:
 929         if (Instruction::isCast(CE->getOpcode())) {
 930           Code = bitc::CST_CODE_CE_CAST;
 931           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
 932           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 933           Record.push_back(VE.getValueID(C->getOperand(0)));
 934           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
 935         } else {
 936           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
 937           Code = bitc::CST_CODE_CE_BINOP;
 938           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
 939           Record.push_back(VE.getValueID(C->getOperand(0)));
 940           Record.push_back(VE.getValueID(C->getOperand(1)));
 941           uint64_t Flags = GetOptimizationFlags(CE);
 942           if (Flags != 0)
 943             Record.push_back(Flags);
 944         }
 945         break;
 946       case Instruction::GetElementPtr:
 947         Code = bitc::CST_CODE_CE_GEP;
 948         if (cast<GEPOperator>(C)->isInBounds())
 949           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
 950         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
 951           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
 952           Record.push_back(VE.getValueID(C->getOperand(i)));
 953         }
 954         break;
 955       case Instruction::Select:
 956         Code = bitc::CST_CODE_CE_SELECT;
 957         Record.push_back(VE.getValueID(C->getOperand(0)));
 958         Record.push_back(VE.getValueID(C->getOperand(1)));
 959         Record.push_back(VE.getValueID(C->getOperand(2)));
 960         break;
 961       case Instruction::ExtractElement:
 962         Code = bitc::CST_CODE_CE_EXTRACTELT;
 963         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 964         Record.push_back(VE.getValueID(C->getOperand(0)));
 965         Record.push_back(VE.getValueID(C->getOperand(1)));
 966         break;
 967       case Instruction::InsertElement:
 968         Code = bitc::CST_CODE_CE_INSERTELT;
 969         Record.push_back(VE.getValueID(C->getOperand(0)));
 970         Record.push_back(VE.getValueID(C->getOperand(1)));
 971         Record.push_back(VE.getValueID(C->getOperand(2)));
 972         break;
 973       case Instruction::ShuffleVector:
 974         // If the return type and argument types are the same, this is a
 975         // standard shufflevector instruction.  If the types are different,
 976         // then the shuffle is widening or truncating the input vectors, and
 977         // the argument type must also be encoded.
 978         if (C->getType() == C->getOperand(0)->getType()) {
 979           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
 980         } else {
 981           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
 982           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 983         }
 984         Record.push_back(VE.getValueID(C->getOperand(0)));
 985         Record.push_back(VE.getValueID(C->getOperand(1)));
 986         Record.push_back(VE.getValueID(C->getOperand(2)));
 987         break;
 988       case Instruction::ICmp:
 989       case Instruction::FCmp:
 990         Code = bitc::CST_CODE_CE_CMP;
 991         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
 992         Record.push_back(VE.getValueID(C->getOperand(0)));
 993         Record.push_back(VE.getValueID(C->getOperand(1)));
 994         Record.push_back(CE->getPredicate());
 995         break;
 996       }
 997     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
 998       Code = bitc::CST_CODE_BLOCKADDRESS;
 999       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1000       Record.push_back(VE.getValueID(BA->getFunction()));
1001       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1002     } else {
1003 #ifndef NDEBUG
1004       C->dump();
1005 #endif
1006       llvm_unreachable("Unknown constant!");
1007     }
1008     Stream.EmitRecord(Code, Record, AbbrevToUse);
1009     Record.clear();
1010   }
1011
1012   Stream.ExitBlock();
1013 }
1014
1015 static void WriteModuleConstants(const ValueEnumerator &VE,
1016                                  BitstreamWriter &Stream) {
1017   const ValueEnumerator::ValueList &Vals = VE.getValues();
1018
1019   // Find the first constant to emit, which is the first non-globalvalue value.
1020   // We know globalvalues have been emitted by WriteModuleInfo.
1021   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1022     if (!isa<GlobalValue>(Vals[i].first)) {
1023       WriteConstants(i, Vals.size(), VE, Stream, true);
1024       return;
1025     }
1026   }
1027 }
1028
1029 /// PushValueAndType - The file has to encode both the value and type id for
1030 /// many values, because we need to know what type to create for forward
1031 /// references.  However, most operands are not forward references, so this type
1032 /// field is not needed.
1033 ///
1034 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1035 /// instruction ID, then it is a forward reference, and it also includes the
1036 /// type ID.  The value ID that is written is encoded relative to the InstID.
1037 static bool PushValueAndType(const Value *V, unsigned InstID,
1038                              SmallVector<unsigned, 64> &Vals,
1039                              ValueEnumerator &VE) {
1040   unsigned ValID = VE.getValueID(V);
1041   // Make encoding relative to the InstID.
1042   Vals.push_back(InstID - ValID);
1043   if (ValID >= InstID) {
1044     Vals.push_back(VE.getTypeID(V->getType()));
1045     return true;
1046   }
1047   return false;
1048 }
1049
1050 /// pushValue - Like PushValueAndType, but where the type of the value is
1051 /// omitted (perhaps it was already encoded in an earlier operand).
1052 static void pushValue(const Value *V, unsigned InstID,
1053                       SmallVector<unsigned, 64> &Vals,
1054                       ValueEnumerator &VE) {
1055   unsigned ValID = VE.getValueID(V);
1056   Vals.push_back(InstID - ValID);
1057 }
1058
1059 static void pushValue64(const Value *V, unsigned InstID,
1060                         SmallVector<uint64_t, 128> &Vals,
1061                         ValueEnumerator &VE) {
1062   uint64_t ValID = VE.getValueID(V);
1063   Vals.push_back(InstID - ValID);
1064 }
1065
1066 static void pushValueSigned(const Value *V, unsigned InstID,
1067                             SmallVector<uint64_t, 128> &Vals,
1068                             ValueEnumerator &VE) {
1069   unsigned ValID = VE.getValueID(V);
1070   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1071   emitSignedInt64(Vals, diff);
1072 }
1073
1074 /// WriteInstruction - Emit an instruction to the specified stream.
1075 static void WriteInstruction(const Instruction &I, unsigned InstID,
1076                              ValueEnumerator &VE, BitstreamWriter &Stream,
1077                              SmallVector<unsigned, 64> &Vals) {
1078   unsigned Code = 0;
1079   unsigned AbbrevToUse = 0;
1080   VE.setInstructionID(&I);
1081   switch (I.getOpcode()) {
1082   default:
1083     if (Instruction::isCast(I.getOpcode())) {
1084       Code = bitc::FUNC_CODE_INST_CAST;
1085       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1086         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1087       Vals.push_back(VE.getTypeID(I.getType()));
1088       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1089     } else {
1090       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1091       Code = bitc::FUNC_CODE_INST_BINOP;
1092       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1093         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1094       pushValue(I.getOperand(1), InstID, Vals, VE);
1095       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1096       uint64_t Flags = GetOptimizationFlags(&I);
1097       if (Flags != 0) {
1098         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1099           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1100         Vals.push_back(Flags);
1101       }
1102     }
1103     break;
1104
1105   case Instruction::GetElementPtr:
1106     Code = bitc::FUNC_CODE_INST_GEP;
1107     if (cast<GEPOperator>(&I)->isInBounds())
1108       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1109     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1110       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1111     break;
1112   case Instruction::ExtractValue: {
1113     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1114     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1115     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1116     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1117       Vals.push_back(*i);
1118     break;
1119   }
1120   case Instruction::InsertValue: {
1121     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1122     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1123     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1124     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1125     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1126       Vals.push_back(*i);
1127     break;
1128   }
1129   case Instruction::Select:
1130     Code = bitc::FUNC_CODE_INST_VSELECT;
1131     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1132     pushValue(I.getOperand(2), InstID, Vals, VE);
1133     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1134     break;
1135   case Instruction::ExtractElement:
1136     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1137     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1138     pushValue(I.getOperand(1), InstID, Vals, VE);
1139     break;
1140   case Instruction::InsertElement:
1141     Code = bitc::FUNC_CODE_INST_INSERTELT;
1142     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1143     pushValue(I.getOperand(1), InstID, Vals, VE);
1144     pushValue(I.getOperand(2), InstID, Vals, VE);
1145     break;
1146   case Instruction::ShuffleVector:
1147     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1148     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1149     pushValue(I.getOperand(1), InstID, Vals, VE);
1150     pushValue(I.getOperand(2), InstID, Vals, VE);
1151     break;
1152   case Instruction::ICmp:
1153   case Instruction::FCmp:
1154     // compare returning Int1Ty or vector of Int1Ty
1155     Code = bitc::FUNC_CODE_INST_CMP2;
1156     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1157     pushValue(I.getOperand(1), InstID, Vals, VE);
1158     Vals.push_back(cast<CmpInst>(I).getPredicate());
1159     break;
1160
1161   case Instruction::Ret:
1162     {
1163       Code = bitc::FUNC_CODE_INST_RET;
1164       unsigned NumOperands = I.getNumOperands();
1165       if (NumOperands == 0)
1166         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1167       else if (NumOperands == 1) {
1168         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1169           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1170       } else {
1171         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1172           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1173       }
1174     }
1175     break;
1176   case Instruction::Br:
1177     {
1178       Code = bitc::FUNC_CODE_INST_BR;
1179       BranchInst &II = cast<BranchInst>(I);
1180       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1181       if (II.isConditional()) {
1182         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1183         pushValue(II.getCondition(), InstID, Vals, VE);
1184       }
1185     }
1186     break;
1187   case Instruction::Switch:
1188     {
1189       // Redefine Vals, since here we need to use 64 bit values
1190       // explicitly to store large APInt numbers.
1191       SmallVector<uint64_t, 128> Vals64;
1192
1193       Code = bitc::FUNC_CODE_INST_SWITCH;
1194       SwitchInst &SI = cast<SwitchInst>(I);
1195
1196       uint32_t SwitchRecordHeader = SI.hash() | (SWITCH_INST_MAGIC << 16);
1197       Vals64.push_back(SwitchRecordHeader);
1198
1199       Vals64.push_back(VE.getTypeID(SI.getCondition()->getType()));
1200       pushValue64(SI.getCondition(), InstID, Vals64, VE);
1201       Vals64.push_back(VE.getValueID(SI.getDefaultDest()));
1202       Vals64.push_back(SI.getNumCases());
1203       for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
1204            i != e; ++i) {
1205         IntegersSubset& CaseRanges = i.getCaseValueEx();
1206         unsigned Code, Abbrev; // will unused.
1207
1208         if (CaseRanges.isSingleNumber()) {
1209           Vals64.push_back(1/*NumItems = 1*/);
1210           Vals64.push_back(true/*IsSingleNumber = true*/);
1211           EmitAPInt(Vals64, Code, Abbrev, CaseRanges.getSingleNumber(0), true);
1212         } else {
1213
1214           Vals64.push_back(CaseRanges.getNumItems());
1215
1216           if (CaseRanges.isSingleNumbersOnly()) {
1217             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1218                  ri != rn; ++ri) {
1219
1220               Vals64.push_back(true/*IsSingleNumber = true*/);
1221
1222               EmitAPInt(Vals64, Code, Abbrev,
1223                         CaseRanges.getSingleNumber(ri), true);
1224             }
1225           } else
1226             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1227                  ri != rn; ++ri) {
1228               IntegersSubset::Range r = CaseRanges.getItem(ri);
1229               bool IsSingleNumber = CaseRanges.isSingleNumber(ri);
1230
1231               Vals64.push_back(IsSingleNumber);
1232
1233               EmitAPInt(Vals64, Code, Abbrev, r.getLow(), true);
1234               if (!IsSingleNumber)
1235                 EmitAPInt(Vals64, Code, Abbrev, r.getHigh(), true);
1236             }
1237         }
1238         Vals64.push_back(VE.getValueID(i.getCaseSuccessor()));
1239       }
1240
1241       Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1242
1243       // Also do expected action - clear external Vals collection:
1244       Vals.clear();
1245       return;
1246     }
1247     break;
1248   case Instruction::IndirectBr:
1249     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1250     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1251     // Encode the address operand as relative, but not the basic blocks.
1252     pushValue(I.getOperand(0), InstID, Vals, VE);
1253     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1254       Vals.push_back(VE.getValueID(I.getOperand(i)));
1255     break;
1256
1257   case Instruction::Invoke: {
1258     const InvokeInst *II = cast<InvokeInst>(&I);
1259     const Value *Callee(II->getCalledValue());
1260     PointerType *PTy = cast<PointerType>(Callee->getType());
1261     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1262     Code = bitc::FUNC_CODE_INST_INVOKE;
1263
1264     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1265     Vals.push_back(II->getCallingConv());
1266     Vals.push_back(VE.getValueID(II->getNormalDest()));
1267     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1268     PushValueAndType(Callee, InstID, Vals, VE);
1269
1270     // Emit value #'s for the fixed parameters.
1271     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1272       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1273
1274     // Emit type/value pairs for varargs params.
1275     if (FTy->isVarArg()) {
1276       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1277            i != e; ++i)
1278         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1279     }
1280     break;
1281   }
1282   case Instruction::Resume:
1283     Code = bitc::FUNC_CODE_INST_RESUME;
1284     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1285     break;
1286   case Instruction::Unreachable:
1287     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1288     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1289     break;
1290
1291   case Instruction::PHI: {
1292     const PHINode &PN = cast<PHINode>(I);
1293     Code = bitc::FUNC_CODE_INST_PHI;
1294     // With the newer instruction encoding, forward references could give
1295     // negative valued IDs.  This is most common for PHIs, so we use
1296     // signed VBRs.
1297     SmallVector<uint64_t, 128> Vals64;
1298     Vals64.push_back(VE.getTypeID(PN.getType()));
1299     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1300       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1301       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1302     }
1303     // Emit a Vals64 vector and exit.
1304     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1305     Vals64.clear();
1306     return;
1307   }
1308
1309   case Instruction::LandingPad: {
1310     const LandingPadInst &LP = cast<LandingPadInst>(I);
1311     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1312     Vals.push_back(VE.getTypeID(LP.getType()));
1313     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1314     Vals.push_back(LP.isCleanup());
1315     Vals.push_back(LP.getNumClauses());
1316     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1317       if (LP.isCatch(I))
1318         Vals.push_back(LandingPadInst::Catch);
1319       else
1320         Vals.push_back(LandingPadInst::Filter);
1321       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1322     }
1323     break;
1324   }
1325
1326   case Instruction::Alloca:
1327     Code = bitc::FUNC_CODE_INST_ALLOCA;
1328     Vals.push_back(VE.getTypeID(I.getType()));
1329     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1330     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1331     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1332     break;
1333
1334   case Instruction::Load:
1335     if (cast<LoadInst>(I).isAtomic()) {
1336       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1337       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1338     } else {
1339       Code = bitc::FUNC_CODE_INST_LOAD;
1340       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1341         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1342     }
1343     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1344     Vals.push_back(cast<LoadInst>(I).isVolatile());
1345     if (cast<LoadInst>(I).isAtomic()) {
1346       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1347       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1348     }
1349     break;
1350   case Instruction::Store:
1351     if (cast<StoreInst>(I).isAtomic())
1352       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1353     else
1354       Code = bitc::FUNC_CODE_INST_STORE;
1355     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1356     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1357     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1358     Vals.push_back(cast<StoreInst>(I).isVolatile());
1359     if (cast<StoreInst>(I).isAtomic()) {
1360       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1361       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1362     }
1363     break;
1364   case Instruction::AtomicCmpXchg:
1365     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1366     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1367     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1368     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1369     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1370     Vals.push_back(GetEncodedOrdering(
1371                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1372     Vals.push_back(GetEncodedSynchScope(
1373                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1374     break;
1375   case Instruction::AtomicRMW:
1376     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1377     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1378     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1379     Vals.push_back(GetEncodedRMWOperation(
1380                      cast<AtomicRMWInst>(I).getOperation()));
1381     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1382     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1383     Vals.push_back(GetEncodedSynchScope(
1384                      cast<AtomicRMWInst>(I).getSynchScope()));
1385     break;
1386   case Instruction::Fence:
1387     Code = bitc::FUNC_CODE_INST_FENCE;
1388     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1389     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1390     break;
1391   case Instruction::Call: {
1392     const CallInst &CI = cast<CallInst>(I);
1393     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1394     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1395
1396     Code = bitc::FUNC_CODE_INST_CALL;
1397
1398     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1399     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1400     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1401
1402     // Emit value #'s for the fixed parameters.
1403     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1404       // Check for labels (can happen with asm labels).
1405       if (FTy->getParamType(i)->isLabelTy())
1406         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1407       else
1408         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1409     }
1410
1411     // Emit type/value pairs for varargs params.
1412     if (FTy->isVarArg()) {
1413       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1414            i != e; ++i)
1415         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1416     }
1417     break;
1418   }
1419   case Instruction::VAArg:
1420     Code = bitc::FUNC_CODE_INST_VAARG;
1421     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1422     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1423     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1424     break;
1425   }
1426
1427   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1428   Vals.clear();
1429 }
1430
1431 // Emit names for globals/functions etc.
1432 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1433                                   const ValueEnumerator &VE,
1434                                   BitstreamWriter &Stream) {
1435   if (VST.empty()) return;
1436   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1437
1438   // FIXME: Set up the abbrev, we know how many values there are!
1439   // FIXME: We know if the type names can use 7-bit ascii.
1440   SmallVector<unsigned, 64> NameVals;
1441
1442   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1443        SI != SE; ++SI) {
1444
1445     const ValueName &Name = *SI;
1446
1447     // Figure out the encoding to use for the name.
1448     bool is7Bit = true;
1449     bool isChar6 = true;
1450     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1451          C != E; ++C) {
1452       if (isChar6)
1453         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1454       if ((unsigned char)*C & 128) {
1455         is7Bit = false;
1456         break;  // don't bother scanning the rest.
1457       }
1458     }
1459
1460     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1461
1462     // VST_ENTRY:   [valueid, namechar x N]
1463     // VST_BBENTRY: [bbid, namechar x N]
1464     unsigned Code;
1465     if (isa<BasicBlock>(SI->getValue())) {
1466       Code = bitc::VST_CODE_BBENTRY;
1467       if (isChar6)
1468         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1469     } else {
1470       Code = bitc::VST_CODE_ENTRY;
1471       if (isChar6)
1472         AbbrevToUse = VST_ENTRY_6_ABBREV;
1473       else if (is7Bit)
1474         AbbrevToUse = VST_ENTRY_7_ABBREV;
1475     }
1476
1477     NameVals.push_back(VE.getValueID(SI->getValue()));
1478     for (const char *P = Name.getKeyData(),
1479          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1480       NameVals.push_back((unsigned char)*P);
1481
1482     // Emit the finished record.
1483     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1484     NameVals.clear();
1485   }
1486   Stream.ExitBlock();
1487 }
1488
1489 /// WriteFunction - Emit a function body to the module stream.
1490 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1491                           BitstreamWriter &Stream) {
1492   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1493   VE.incorporateFunction(F);
1494
1495   SmallVector<unsigned, 64> Vals;
1496
1497   // Emit the number of basic blocks, so the reader can create them ahead of
1498   // time.
1499   Vals.push_back(VE.getBasicBlocks().size());
1500   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1501   Vals.clear();
1502
1503   // If there are function-local constants, emit them now.
1504   unsigned CstStart, CstEnd;
1505   VE.getFunctionConstantRange(CstStart, CstEnd);
1506   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1507
1508   // If there is function-local metadata, emit it now.
1509   WriteFunctionLocalMetadata(F, VE, Stream);
1510
1511   // Keep a running idea of what the instruction ID is.
1512   unsigned InstID = CstEnd;
1513
1514   bool NeedsMetadataAttachment = false;
1515
1516   DebugLoc LastDL;
1517
1518   // Finally, emit all the instructions, in order.
1519   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1520     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1521          I != E; ++I) {
1522       WriteInstruction(*I, InstID, VE, Stream, Vals);
1523
1524       if (!I->getType()->isVoidTy())
1525         ++InstID;
1526
1527       // If the instruction has metadata, write a metadata attachment later.
1528       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1529
1530       // If the instruction has a debug location, emit it.
1531       DebugLoc DL = I->getDebugLoc();
1532       if (DL.isUnknown()) {
1533         // nothing todo.
1534       } else if (DL == LastDL) {
1535         // Just repeat the same debug loc as last time.
1536         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1537       } else {
1538         MDNode *Scope, *IA;
1539         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1540
1541         Vals.push_back(DL.getLine());
1542         Vals.push_back(DL.getCol());
1543         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1544         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1545         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1546         Vals.clear();
1547
1548         LastDL = DL;
1549       }
1550     }
1551
1552   // Emit names for all the instructions etc.
1553   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1554
1555   if (NeedsMetadataAttachment)
1556     WriteMetadataAttachment(F, VE, Stream);
1557   VE.purgeFunction();
1558   Stream.ExitBlock();
1559 }
1560
1561 // Emit blockinfo, which defines the standard abbreviations etc.
1562 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1563   // We only want to emit block info records for blocks that have multiple
1564   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1565   // Other blocks can define their abbrevs inline.
1566   Stream.EnterBlockInfoBlock(2);
1567
1568   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1569     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1570     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1571     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1572     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1573     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1574     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1575                                    Abbv) != VST_ENTRY_8_ABBREV)
1576       llvm_unreachable("Unexpected abbrev ordering!");
1577   }
1578
1579   { // 7-bit fixed width VST_ENTRY strings.
1580     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1581     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1582     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1583     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1584     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1585     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1586                                    Abbv) != VST_ENTRY_7_ABBREV)
1587       llvm_unreachable("Unexpected abbrev ordering!");
1588   }
1589   { // 6-bit char6 VST_ENTRY strings.
1590     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1591     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1592     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1593     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1594     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1595     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1596                                    Abbv) != VST_ENTRY_6_ABBREV)
1597       llvm_unreachable("Unexpected abbrev ordering!");
1598   }
1599   { // 6-bit char6 VST_BBENTRY strings.
1600     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1601     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1602     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1603     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1604     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1605     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1606                                    Abbv) != VST_BBENTRY_6_ABBREV)
1607       llvm_unreachable("Unexpected abbrev ordering!");
1608   }
1609
1610
1611
1612   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1613     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1614     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1615     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1616                               Log2_32_Ceil(VE.getTypes().size()+1)));
1617     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1618                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1619       llvm_unreachable("Unexpected abbrev ordering!");
1620   }
1621
1622   { // INTEGER abbrev for CONSTANTS_BLOCK.
1623     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1624     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1625     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1626     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1627                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1628       llvm_unreachable("Unexpected abbrev ordering!");
1629   }
1630
1631   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1632     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1633     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1634     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1635     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1636                               Log2_32_Ceil(VE.getTypes().size()+1)));
1637     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1638
1639     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1640                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1641       llvm_unreachable("Unexpected abbrev ordering!");
1642   }
1643   { // NULL abbrev for CONSTANTS_BLOCK.
1644     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1645     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1646     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1647                                    Abbv) != CONSTANTS_NULL_Abbrev)
1648       llvm_unreachable("Unexpected abbrev ordering!");
1649   }
1650
1651   // FIXME: This should only use space for first class types!
1652
1653   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1654     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1655     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1656     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1657     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1658     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1659     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1660                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1661       llvm_unreachable("Unexpected abbrev ordering!");
1662   }
1663   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1664     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1665     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1666     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1667     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1668     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1669     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1670                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1671       llvm_unreachable("Unexpected abbrev ordering!");
1672   }
1673   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1674     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1675     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1676     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1677     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1678     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1679     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1680     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1681                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1682       llvm_unreachable("Unexpected abbrev ordering!");
1683   }
1684   { // INST_CAST abbrev for FUNCTION_BLOCK.
1685     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1686     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1687     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1688     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1689                               Log2_32_Ceil(VE.getTypes().size()+1)));
1690     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1691     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1692                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1693       llvm_unreachable("Unexpected abbrev ordering!");
1694   }
1695
1696   { // INST_RET abbrev for FUNCTION_BLOCK.
1697     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1698     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1699     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1700                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1701       llvm_unreachable("Unexpected abbrev ordering!");
1702   }
1703   { // INST_RET abbrev for FUNCTION_BLOCK.
1704     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1705     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1706     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1707     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1708                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1709       llvm_unreachable("Unexpected abbrev ordering!");
1710   }
1711   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1712     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1713     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1714     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1715                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1716       llvm_unreachable("Unexpected abbrev ordering!");
1717   }
1718
1719   Stream.ExitBlock();
1720 }
1721
1722 // Sort the Users based on the order in which the reader parses the bitcode
1723 // file.
1724 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1725   // TODO: Implement.
1726   return true;
1727 }
1728
1729 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1730                          BitstreamWriter &Stream) {
1731
1732   // One or zero uses can't get out of order.
1733   if (V->use_empty() || V->hasNUses(1))
1734     return;
1735
1736   // Make a copy of the in-memory use-list for sorting.
1737   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1738   SmallVector<const User*, 8> UseList;
1739   UseList.reserve(UseListSize);
1740   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1741        I != E; ++I) {
1742     const User *U = *I;
1743     UseList.push_back(U);
1744   }
1745
1746   // Sort the copy based on the order read by the BitcodeReader.
1747   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1748
1749   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1750   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1751
1752   // TODO: Emit the USELIST_CODE_ENTRYs.
1753 }
1754
1755 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1756                                  BitstreamWriter &Stream) {
1757   VE.incorporateFunction(*F);
1758
1759   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1760        AI != AE; ++AI)
1761     WriteUseList(AI, VE, Stream);
1762   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1763        ++BB) {
1764     WriteUseList(BB, VE, Stream);
1765     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1766          ++II) {
1767       WriteUseList(II, VE, Stream);
1768       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1769            OI != E; ++OI) {
1770         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1771             isa<InlineAsm>(*OI))
1772           WriteUseList(*OI, VE, Stream);
1773       }
1774     }
1775   }
1776   VE.purgeFunction();
1777 }
1778
1779 // Emit use-lists.
1780 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1781                                 BitstreamWriter &Stream) {
1782   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1783
1784   // XXX: this modifies the module, but in a way that should never change the
1785   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1786   // contain entries in the use_list that do not exist in the Module and are
1787   // not stored in the .bc file.
1788   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1789        I != E; ++I)
1790     I->removeDeadConstantUsers();
1791
1792   // Write the global variables.
1793   for (Module::const_global_iterator GI = M->global_begin(),
1794          GE = M->global_end(); GI != GE; ++GI) {
1795     WriteUseList(GI, VE, Stream);
1796
1797     // Write the global variable initializers.
1798     if (GI->hasInitializer())
1799       WriteUseList(GI->getInitializer(), VE, Stream);
1800   }
1801
1802   // Write the functions.
1803   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1804     WriteUseList(FI, VE, Stream);
1805     if (!FI->isDeclaration())
1806       WriteFunctionUseList(FI, VE, Stream);
1807   }
1808
1809   // Write the aliases.
1810   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1811        AI != AE; ++AI) {
1812     WriteUseList(AI, VE, Stream);
1813     WriteUseList(AI->getAliasee(), VE, Stream);
1814   }
1815
1816   Stream.ExitBlock();
1817 }
1818
1819 /// WriteModule - Emit the specified module to the bitstream.
1820 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1821   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1822
1823   SmallVector<unsigned, 1> Vals;
1824   unsigned CurVersion = 1;
1825   Vals.push_back(CurVersion);
1826   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1827
1828   // Analyze the module, enumerating globals, functions, etc.
1829   ValueEnumerator VE(M);
1830
1831   // Emit blockinfo, which defines the standard abbreviations etc.
1832   WriteBlockInfo(VE, Stream);
1833
1834   // Emit information about parameter attributes.
1835   WriteAttributeTable(VE, Stream);
1836
1837   // Emit information describing all of the types in the module.
1838   WriteTypeTable(VE, Stream);
1839
1840   // Emit top-level description of module, including target triple, inline asm,
1841   // descriptors for global variables, and function prototype info.
1842   WriteModuleInfo(M, VE, Stream);
1843
1844   // Emit constants.
1845   WriteModuleConstants(VE, Stream);
1846
1847   // Emit metadata.
1848   WriteModuleMetadata(M, VE, Stream);
1849
1850   // Emit metadata.
1851   WriteModuleMetadataStore(M, Stream);
1852
1853   // Emit names for globals/functions etc.
1854   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1855
1856   // Emit use-lists.
1857   if (EnablePreserveUseListOrdering)
1858     WriteModuleUseLists(M, VE, Stream);
1859
1860   // Emit function bodies.
1861   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1862     if (!F->isDeclaration())
1863       WriteFunction(*F, VE, Stream);
1864
1865   Stream.ExitBlock();
1866 }
1867
1868 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1869 /// header and trailer to make it compatible with the system archiver.  To do
1870 /// this we emit the following header, and then emit a trailer that pads the
1871 /// file out to be a multiple of 16 bytes.
1872 ///
1873 /// struct bc_header {
1874 ///   uint32_t Magic;         // 0x0B17C0DE
1875 ///   uint32_t Version;       // Version, currently always 0.
1876 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1877 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1878 ///   uint32_t CPUType;       // CPU specifier.
1879 ///   ... potentially more later ...
1880 /// };
1881 enum {
1882   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1883   DarwinBCHeaderSize = 5*4
1884 };
1885
1886 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1887                                uint32_t &Position) {
1888   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1889   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1890   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1891   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1892   Position += 4;
1893 }
1894
1895 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1896                                          const Triple &TT) {
1897   unsigned CPUType = ~0U;
1898
1899   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1900   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1901   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1902   // specific constants here because they are implicitly part of the Darwin ABI.
1903   enum {
1904     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1905     DARWIN_CPU_TYPE_X86        = 7,
1906     DARWIN_CPU_TYPE_ARM        = 12,
1907     DARWIN_CPU_TYPE_POWERPC    = 18
1908   };
1909
1910   Triple::ArchType Arch = TT.getArch();
1911   if (Arch == Triple::x86_64)
1912     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1913   else if (Arch == Triple::x86)
1914     CPUType = DARWIN_CPU_TYPE_X86;
1915   else if (Arch == Triple::ppc)
1916     CPUType = DARWIN_CPU_TYPE_POWERPC;
1917   else if (Arch == Triple::ppc64)
1918     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1919   else if (Arch == Triple::arm || Arch == Triple::thumb)
1920     CPUType = DARWIN_CPU_TYPE_ARM;
1921
1922   // Traditional Bitcode starts after header.
1923   assert(Buffer.size() >= DarwinBCHeaderSize &&
1924          "Expected header size to be reserved");
1925   unsigned BCOffset = DarwinBCHeaderSize;
1926   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1927
1928   // Write the magic and version.
1929   unsigned Position = 0;
1930   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1931   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1932   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1933   WriteInt32ToBuffer(BCSize     , Buffer, Position);
1934   WriteInt32ToBuffer(CPUType    , Buffer, Position);
1935
1936   // If the file is not a multiple of 16 bytes, insert dummy padding.
1937   while (Buffer.size() & 15)
1938     Buffer.push_back(0);
1939 }
1940
1941 /// WriteBitcodeToFile - Write the specified module to the specified output
1942 /// stream.
1943 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1944   SmallVector<char, 0> Buffer;
1945   Buffer.reserve(256*1024);
1946
1947   // If this is darwin or another generic macho target, reserve space for the
1948   // header.
1949   Triple TT(M->getTargetTriple());
1950   if (TT.isOSDarwin())
1951     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
1952
1953   // Emit the module into the buffer.
1954   {
1955     BitstreamWriter Stream(Buffer);
1956
1957     // Emit the file header.
1958     Stream.Emit((unsigned)'B', 8);
1959     Stream.Emit((unsigned)'C', 8);
1960     Stream.Emit(0x0, 4);
1961     Stream.Emit(0xC, 4);
1962     Stream.Emit(0xE, 4);
1963     Stream.Emit(0xD, 4);
1964
1965     // Emit the module.
1966     WriteModule(M, Stream);
1967   }
1968
1969   if (TT.isOSDarwin())
1970     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
1971
1972   // Write the generated bitstream to "Out".
1973   Out.write((char*)&Buffer.front(), Buffer.size());
1974 }