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 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
 165                                      BitstreamWriter &Stream) {
 166   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
 167   if (AttrGrps.empty()) return;
 168
 169   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 170
 171   SmallVector<uint64_t, 64> Record;
 172   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
 173     AttributeSet AS = AttrGrps[i];
 174     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
 175       AttributeSet A = AS.getSlotAttributes(i);
 176
 177       Record.push_back(VE.getAttributeGroupID(A));
 178       Record.push_back(AS.getSlotIndex(i));
 179
 180       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
 181            I != E; ++I) {
 182         Attribute Attr = *I;
 183         if (Attr.isEnumAttribute()) {
 184           Record.push_back(0);
 185           Record.push_back(Attr.getKindAsEnum());
 186         } else if (Attr.isAlignAttribute()) {
 187           Record.push_back(1);
 188           Record.push_back(Attr.getKindAsEnum());
 189           Record.push_back(Attr.getValueAsInt());
 190         } else {
 191           StringRef Kind = Attr.getKindAsString();
 192           StringRef Val = Attr.getValueAsString();
 193
 194           Record.push_back(Val.empty() ? 3 : 4);
 195           Record.append(Kind.begin(), Kind.end());
 196           Record.push_back(0);
 197           if (!Val.empty()) {
 198             Record.append(Val.begin(), Val.end());
 199             Record.push_back(0);
 200           }
 201         }
 202       }
 203
 204       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
 205       Record.clear();
 206     }
 207   }
 208
 209   Stream.ExitBlock();
 210 }
 211
 212 /// \brief This returns an integer containing an encoding of all the LLVM
 213 /// attributes found in the given attribute bitset.  Any change to this encoding
 214 /// is a breaking change to bitcode compatibility.
 215 /// N.B. This should be used only by the bitcode writer!
 216 static uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs,
 217                                                unsigned Index) {
 218   // FIXME: Remove in 4.0!
 219
 220   // FIXME: It doesn't make sense to store the alignment information as an
 221   // expanded out value, we should store it as a log2 value.  However, we can't
 222   // just change that here without breaking bitcode compatibility.  If this ever
 223   // becomes a problem in practice, we should introduce new tag numbers in the
 224   // bitcode file and have those tags use a more efficiently encoded alignment
 225   // field.
 226
 227   // Store the alignment in the bitcode as a 16-bit raw value instead of a 5-bit
 228   // log2 encoded value. Shift the bits above the alignment up by 11 bits.
 229   uint64_t EncodedAttrs = Attrs.Raw(Index) & 0xffff;
 230   if (Attrs.hasAttribute(Index, Attribute::Alignment))
 231     EncodedAttrs |= Attrs.getParamAlignment(Index) << 16;
 232   EncodedAttrs |= (Attrs.Raw(Index) & (0xfffffULL << 21)) << 11;
 233   return EncodedAttrs;
 234 }
 235
 236 static void WriteAttributeTable(const ValueEnumerator &VE,
 237                                 BitstreamWriter &Stream) {
 238   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
 239   if (Attrs.empty()) return;
 240
 241   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 242
 243   // FIXME: Remove this! It no longer works with the current attributes classes.
 244
 245   SmallVector<uint64_t, 64> Record;
 246   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
 247     const AttributeSet &A = Attrs[i];
 248     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
 249       unsigned Index = A.getSlotIndex(i);
 250       Record.push_back(Index);
 251       Record.push_back(encodeLLVMAttributesForBitcode(A.getSlotAttributes(i),
 252                                                       Index));
 253     }
 254
 255     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY_OLD, Record);
 256     Record.clear();
 257   }
 258
 259   Stream.ExitBlock();
 260 }
 261
 262 /// WriteTypeTable - Write out the type table for a module.
 263 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 264   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 265
 266   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
 267   SmallVector<uint64_t, 64> TypeVals;
 268
 269   uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
 270
 271   // Abbrev for TYPE_CODE_POINTER.
 272   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 273   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
 274   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 275   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
 276   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
 277
 278   // Abbrev for TYPE_CODE_FUNCTION.
 279   Abbv = new BitCodeAbbrev();
 280   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
 281   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
 282   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 283   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 284
 285   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 286
 287   // Abbrev for TYPE_CODE_STRUCT_ANON.
 288   Abbv = new BitCodeAbbrev();
 289   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
 290   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 291   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 292   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 293
 294   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 295
 296   // Abbrev for TYPE_CODE_STRUCT_NAME.
 297   Abbv = new BitCodeAbbrev();
 298   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
 299   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 300   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 301   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
 302
 303   // Abbrev for TYPE_CODE_STRUCT_NAMED.
 304   Abbv = new BitCodeAbbrev();
 305   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
 306   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
 307   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 308   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 309
 310   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
 311
 312   // Abbrev for TYPE_CODE_ARRAY.
 313   Abbv = new BitCodeAbbrev();
 314   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
 315   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
 316   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
 317
 318   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
 319
 320   // Emit an entry count so the reader can reserve space.
 321   TypeVals.push_back(TypeList.size());
 322   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
 323   TypeVals.clear();
 324
 325   // Loop over all of the types, emitting each in turn.
 326   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
 327     Type *T = TypeList[i];
 328     int AbbrevToUse = 0;
 329     unsigned Code = 0;
 330
 331     switch (T->getTypeID()) {
 332     default: llvm_unreachable("Unknown type!");
 333     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
 334     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
 335     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
 336     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
 337     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
 338     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
 339     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
 340     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
 341     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
 342     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
 343     case Type::IntegerTyID:
 344       // INTEGER: [width]
 345       Code = bitc::TYPE_CODE_INTEGER;
 346       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
 347       break;
 348     case Type::PointerTyID: {
 349       PointerType *PTy = cast<PointerType>(T);
 350       // POINTER: [pointee type, address space]
 351       Code = bitc::TYPE_CODE_POINTER;
 352       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
 353       unsigned AddressSpace = PTy->getAddressSpace();
 354       TypeVals.push_back(AddressSpace);
 355       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
 356       break;
 357     }
 358     case Type::FunctionTyID: {
 359       FunctionType *FT = cast<FunctionType>(T);
 360       // FUNCTION: [isvararg, retty, paramty x N]
 361       Code = bitc::TYPE_CODE_FUNCTION;
 362       TypeVals.push_back(FT->isVarArg());
 363       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
 364       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
 365         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
 366       AbbrevToUse = FunctionAbbrev;
 367       break;
 368     }
 369     case Type::StructTyID: {
 370       StructType *ST = cast<StructType>(T);
 371       // STRUCT: [ispacked, eltty x N]
 372       TypeVals.push_back(ST->isPacked());
 373       // Output all of the element types.
 374       for (StructType::element_iterator I = ST->element_begin(),
 375            E = ST->element_end(); I != E; ++I)
 376         TypeVals.push_back(VE.getTypeID(*I));
 377
 378       if (ST->isLiteral()) {
 379         Code = bitc::TYPE_CODE_STRUCT_ANON;
 380         AbbrevToUse = StructAnonAbbrev;
 381       } else {
 382         if (ST->isOpaque()) {
 383           Code = bitc::TYPE_CODE_OPAQUE;
 384         } else {
 385           Code = bitc::TYPE_CODE_STRUCT_NAMED;
 386           AbbrevToUse = StructNamedAbbrev;
 387         }
 388
 389         // Emit the name if it is present.
 390         if (!ST->getName().empty())
 391           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
 392                             StructNameAbbrev, Stream);
 393       }
 394       break;
 395     }
 396     case Type::ArrayTyID: {
 397       ArrayType *AT = cast<ArrayType>(T);
 398       // ARRAY: [numelts, eltty]
 399       Code = bitc::TYPE_CODE_ARRAY;
 400       TypeVals.push_back(AT->getNumElements());
 401       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
 402       AbbrevToUse = ArrayAbbrev;
 403       break;
 404     }
 405     case Type::VectorTyID: {
 406       VectorType *VT = cast<VectorType>(T);
 407       // VECTOR [numelts, eltty]
 408       Code = bitc::TYPE_CODE_VECTOR;
 409       TypeVals.push_back(VT->getNumElements());
 410       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
 411       break;
 412     }
 413     }
 414
 415     // Emit the finished record.
 416     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
 417     TypeVals.clear();
 418   }
 419
 420   Stream.ExitBlock();
 421 }
 422
 423 static unsigned getEncodedLinkage(const GlobalValue *GV) {
 424   switch (GV->getLinkage()) {
 425   case GlobalValue::ExternalLinkage:                 return 0;
 426   case GlobalValue::WeakAnyLinkage:                  return 1;
 427   case GlobalValue::AppendingLinkage:                return 2;
 428   case GlobalValue::InternalLinkage:                 return 3;
 429   case GlobalValue::LinkOnceAnyLinkage:              return 4;
 430   case GlobalValue::DLLImportLinkage:                return 5;
 431   case GlobalValue::DLLExportLinkage:                return 6;
 432   case GlobalValue::ExternalWeakLinkage:             return 7;
 433   case GlobalValue::CommonLinkage:                   return 8;
 434   case GlobalValue::PrivateLinkage:                  return 9;
 435   case GlobalValue::WeakODRLinkage:                  return 10;
 436   case GlobalValue::LinkOnceODRLinkage:              return 11;
 437   case GlobalValue::AvailableExternallyLinkage:      return 12;
 438   case GlobalValue::LinkerPrivateLinkage:            return 13;
 439   case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
 440   case GlobalValue::LinkOnceODRAutoHideLinkage:      return 15;
 441   }
 442   llvm_unreachable("Invalid linkage");
 443 }
 444
 445 static unsigned getEncodedVisibility(const GlobalValue *GV) {
 446   switch (GV->getVisibility()) {
 447   case GlobalValue::DefaultVisibility:   return 0;
 448   case GlobalValue::HiddenVisibility:    return 1;
 449   case GlobalValue::ProtectedVisibility: return 2;
 450   }
 451   llvm_unreachable("Invalid visibility");
 452 }
 453
 454 static unsigned getEncodedThreadLocalMode(const GlobalVariable *GV) {
 455   switch (GV->getThreadLocalMode()) {
 456     case GlobalVariable::NotThreadLocal:         return 0;
 457     case GlobalVariable::GeneralDynamicTLSModel: return 1;
 458     case GlobalVariable::LocalDynamicTLSModel:   return 2;
 459     case GlobalVariable::InitialExecTLSModel:    return 3;
 460     case GlobalVariable::LocalExecTLSModel:      return 4;
 461   }
 462   llvm_unreachable("Invalid TLS model");
 463 }
 464
 465 // Emit top-level description of module, including target triple, inline asm,
 466 // descriptors for global variables, and function prototype info.
 467 static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
 468                             BitstreamWriter &Stream) {
 469   // Emit various pieces of data attached to a module.
 470   if (!M->getTargetTriple().empty())
 471     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
 472                       0/*TODO*/, Stream);
 473   if (!M->getDataLayout().empty())
 474     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
 475                       0/*TODO*/, Stream);
 476   if (!M->getModuleInlineAsm().empty())
 477     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
 478                       0/*TODO*/, Stream);
 479
 480   // Emit information about sections and GC, computing how many there are. Also
 481   // compute the maximum alignment value.
 482   std::map<std::string, unsigned> SectionMap;
 483   std::map<std::string, unsigned> GCMap;
 484   unsigned MaxAlignment = 0;
 485   unsigned MaxGlobalType = 0;
 486   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 487        GV != E; ++GV) {
 488     MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
 489     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
 490     if (GV->hasSection()) {
 491       // Give section names unique ID's.
 492       unsigned &Entry = SectionMap[GV->getSection()];
 493       if (!Entry) {
 494         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
 495                           0/*TODO*/, Stream);
 496         Entry = SectionMap.size();
 497       }
 498     }
 499   }
 500   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 501     MaxAlignment = std::max(MaxAlignment, F->getAlignment());
 502     if (F->hasSection()) {
 503       // Give section names unique ID's.
 504       unsigned &Entry = SectionMap[F->getSection()];
 505       if (!Entry) {
 506         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
 507                           0/*TODO*/, Stream);
 508         Entry = SectionMap.size();
 509       }
 510     }
 511     if (F->hasGC()) {
 512       // Same for GC names.
 513       unsigned &Entry = GCMap[F->getGC()];
 514       if (!Entry) {
 515         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
 516                           0/*TODO*/, Stream);
 517         Entry = GCMap.size();
 518       }
 519     }
 520   }
 521
 522   // Emit abbrev for globals, now that we know # sections and max alignment.
 523   unsigned SimpleGVarAbbrev = 0;
 524   if (!M->global_empty()) {
 525     // Add an abbrev for common globals with no visibility or thread localness.
 526     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 527     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
 528     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 529                               Log2_32_Ceil(MaxGlobalType+1)));
 530     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
 531     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
 532     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
 533     if (MaxAlignment == 0)                                      // Alignment.
 534       Abbv->Add(BitCodeAbbrevOp(0));
 535     else {
 536       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
 537       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 538                                Log2_32_Ceil(MaxEncAlignment+1)));
 539     }
 540     if (SectionMap.empty())                                    // Section.
 541       Abbv->Add(BitCodeAbbrevOp(0));
 542     else
 543       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
 544                                Log2_32_Ceil(SectionMap.size()+1)));
 545     // Don't bother emitting vis + thread local.
 546     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
 547   }
 548
 549   // Emit the global variable information.
 550   SmallVector<unsigned, 64> Vals;
 551   for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
 552        GV != E; ++GV) {
 553     unsigned AbbrevToUse = 0;
 554
 555     // GLOBALVAR: [type, isconst, initid,
 556     //             linkage, alignment, section, visibility, threadlocal,
 557     //             unnamed_addr]
 558     Vals.push_back(VE.getTypeID(GV->getType()));
 559     Vals.push_back(GV->isConstant());
 560     Vals.push_back(GV->isDeclaration() ? 0 :
 561                    (VE.getValueID(GV->getInitializer()) + 1));
 562     Vals.push_back(getEncodedLinkage(GV));
 563     Vals.push_back(Log2_32(GV->getAlignment())+1);
 564     Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
 565     if (GV->isThreadLocal() ||
 566         GV->getVisibility() != GlobalValue::DefaultVisibility ||
 567         GV->hasUnnamedAddr() || GV->isExternallyInitialized()) {
 568       Vals.push_back(getEncodedVisibility(GV));
 569       Vals.push_back(getEncodedThreadLocalMode(GV));
 570       Vals.push_back(GV->hasUnnamedAddr());
 571       Vals.push_back(GV->isExternallyInitialized());
 572     } else {
 573       AbbrevToUse = SimpleGVarAbbrev;
 574     }
 575
 576     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
 577     Vals.clear();
 578   }
 579
 580   // Emit the function proto information.
 581   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
 582     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
 583     //             section, visibility, gc, unnamed_addr]
 584     Vals.push_back(VE.getTypeID(F->getType()));
 585     Vals.push_back(F->getCallingConv());
 586     Vals.push_back(F->isDeclaration());
 587     Vals.push_back(getEncodedLinkage(F));
 588     Vals.push_back(VE.getAttributeID(F->getAttributes()));
 589     Vals.push_back(Log2_32(F->getAlignment())+1);
 590     Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
 591     Vals.push_back(getEncodedVisibility(F));
 592     Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
 593     Vals.push_back(F->hasUnnamedAddr());
 594
 595     unsigned AbbrevToUse = 0;
 596     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
 597     Vals.clear();
 598   }
 599
 600   // Emit the alias information.
 601   for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
 602        AI != E; ++AI) {
 603     // ALIAS: [alias type, aliasee val#, linkage, visibility]
 604     Vals.push_back(VE.getTypeID(AI->getType()));
 605     Vals.push_back(VE.getValueID(AI->getAliasee()));
 606     Vals.push_back(getEncodedLinkage(AI));
 607     Vals.push_back(getEncodedVisibility(AI));
 608     unsigned AbbrevToUse = 0;
 609     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
 610     Vals.clear();
 611   }
 612 }
 613
 614 static uint64_t GetOptimizationFlags(const Value *V) {
 615   uint64_t Flags = 0;
 616
 617   if (const OverflowingBinaryOperator *OBO =
 618         dyn_cast<OverflowingBinaryOperator>(V)) {
 619     if (OBO->hasNoSignedWrap())
 620       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
 621     if (OBO->hasNoUnsignedWrap())
 622       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
 623   } else if (const PossiblyExactOperator *PEO =
 624                dyn_cast<PossiblyExactOperator>(V)) {
 625     if (PEO->isExact())
 626       Flags |= 1 << bitc::PEO_EXACT;
 627   } else if (const FPMathOperator *FPMO =
 628              dyn_cast<const FPMathOperator>(V)) {
 629     if (FPMO->hasUnsafeAlgebra())
 630       Flags |= FastMathFlags::UnsafeAlgebra;
 631     if (FPMO->hasNoNaNs())
 632       Flags |= FastMathFlags::NoNaNs;
 633     if (FPMO->hasNoInfs())
 634       Flags |= FastMathFlags::NoInfs;
 635     if (FPMO->hasNoSignedZeros())
 636       Flags |= FastMathFlags::NoSignedZeros;
 637     if (FPMO->hasAllowReciprocal())
 638       Flags |= FastMathFlags::AllowReciprocal;
 639   }
 640
 641   return Flags;
 642 }
 643
 644 static void WriteMDNode(const MDNode *N,
 645                         const ValueEnumerator &VE,
 646                         BitstreamWriter &Stream,
 647                         SmallVector<uint64_t, 64> &Record) {
 648   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 649     if (N->getOperand(i)) {
 650       Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
 651       Record.push_back(VE.getValueID(N->getOperand(i)));
 652     } else {
 653       Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
 654       Record.push_back(0);
 655     }
 656   }
 657   unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
 658                                            bitc::METADATA_NODE;
 659   Stream.EmitRecord(MDCode, Record, 0);
 660   Record.clear();
 661 }
 662
 663 static void WriteModuleMetadata(const Module *M,
 664                                 const ValueEnumerator &VE,
 665                                 BitstreamWriter &Stream) {
 666   const ValueEnumerator::ValueList &Vals = VE.getMDValues();
 667   bool StartedMetadataBlock = false;
 668   unsigned MDSAbbrev = 0;
 669   SmallVector<uint64_t, 64> Record;
 670   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
 671
 672     if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
 673       if (!N->isFunctionLocal() || !N->getFunction()) {
 674         if (!StartedMetadataBlock) {
 675           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 676           StartedMetadataBlock = true;
 677         }
 678         WriteMDNode(N, VE, Stream, Record);
 679       }
 680     } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
 681       if (!StartedMetadataBlock)  {
 682         Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 683
 684         // Abbrev for METADATA_STRING.
 685         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 686         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
 687         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 688         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 689         MDSAbbrev = Stream.EmitAbbrev(Abbv);
 690         StartedMetadataBlock = true;
 691       }
 692
 693       // Code: [strchar x N]
 694       Record.append(MDS->begin(), MDS->end());
 695
 696       // Emit the finished record.
 697       Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
 698       Record.clear();
 699     }
 700   }
 701
 702   // Write named metadata.
 703   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 704        E = M->named_metadata_end(); I != E; ++I) {
 705     const NamedMDNode *NMD = I;
 706     if (!StartedMetadataBlock)  {
 707       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 708       StartedMetadataBlock = true;
 709     }
 710
 711     // Write name.
 712     StringRef Str = NMD->getName();
 713     for (unsigned i = 0, e = Str.size(); i != e; ++i)
 714       Record.push_back(Str[i]);
 715     Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
 716     Record.clear();
 717
 718     // Write named metadata operands.
 719     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
 720       Record.push_back(VE.getValueID(NMD->getOperand(i)));
 721     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
 722     Record.clear();
 723   }
 724
 725   if (StartedMetadataBlock)
 726     Stream.ExitBlock();
 727 }
 728
 729 static void WriteFunctionLocalMetadata(const Function &F,
 730                                        const ValueEnumerator &VE,
 731                                        BitstreamWriter &Stream) {
 732   bool StartedMetadataBlock = false;
 733   SmallVector<uint64_t, 64> Record;
 734   const SmallVector<const MDNode *, 8> &Vals = VE.getFunctionLocalMDValues();
 735   for (unsigned i = 0, e = Vals.size(); i != e; ++i)
 736     if (const MDNode *N = Vals[i])
 737       if (N->isFunctionLocal() && N->getFunction() == &F) {
 738         if (!StartedMetadataBlock) {
 739           Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 740           StartedMetadataBlock = true;
 741         }
 742         WriteMDNode(N, VE, Stream, Record);
 743       }
 744
 745   if (StartedMetadataBlock)
 746     Stream.ExitBlock();
 747 }
 748
 749 static void WriteMetadataAttachment(const Function &F,
 750                                     const ValueEnumerator &VE,
 751                                     BitstreamWriter &Stream) {
 752   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 753
 754   SmallVector<uint64_t, 64> Record;
 755
 756   // Write metadata attachments
 757   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
 758   SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
 759
 760   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
 761     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
 762          I != E; ++I) {
 763       MDs.clear();
 764       I->getAllMetadataOtherThanDebugLoc(MDs);
 765
 766       // If no metadata, ignore instruction.
 767       if (MDs.empty()) continue;
 768
 769       Record.push_back(VE.getInstructionID(I));
 770
 771       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 772         Record.push_back(MDs[i].first);
 773         Record.push_back(VE.getValueID(MDs[i].second));
 774       }
 775       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
 776       Record.clear();
 777     }
 778
 779   Stream.ExitBlock();
 780 }
 781
 782 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
 783   SmallVector<uint64_t, 64> Record;
 784
 785   // Write metadata kinds
 786   // METADATA_KIND - [n x [id, name]]
 787   SmallVector<StringRef, 8> Names;
 788   M->getMDKindNames(Names);
 789
 790   if (Names.empty()) return;
 791
 792   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
 793
 794   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
 795     Record.push_back(MDKindID);
 796     StringRef KName = Names[MDKindID];
 797     Record.append(KName.begin(), KName.end());
 798
 799     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
 800     Record.clear();
 801   }
 802
 803   Stream.ExitBlock();
 804 }
 805
 806 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
 807   if ((int64_t)V >= 0)
 808     Vals.push_back(V << 1);
 809   else
 810     Vals.push_back((-V << 1) | 1);
 811 }
 812
 813 static void EmitAPInt(SmallVectorImpl<uint64_t> &Vals,
 814                       unsigned &Code, unsigned &AbbrevToUse, const APInt &Val,
 815                       bool EmitSizeForWideNumbers = false
 816                       ) {
 817   if (Val.getBitWidth() <= 64) {
 818     uint64_t V = Val.getSExtValue();
 819     emitSignedInt64(Vals, V);
 820     Code = bitc::CST_CODE_INTEGER;
 821     AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
 822   } else {
 823     // Wide integers, > 64 bits in size.
 824     // We have an arbitrary precision integer value to write whose
 825     // bit width is > 64. However, in canonical unsigned integer
 826     // format it is likely that the high bits are going to be zero.
 827     // So, we only write the number of active words.
 828     unsigned NWords = Val.getActiveWords();
 829
 830     if (EmitSizeForWideNumbers)
 831       Vals.push_back(NWords);
 832
 833     const uint64_t *RawWords = Val.getRawData();
 834     for (unsigned i = 0; i != NWords; ++i) {
 835       emitSignedInt64(Vals, RawWords[i]);
 836     }
 837     Code = bitc::CST_CODE_WIDE_INTEGER;
 838   }
 839 }
 840
 841 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
 842                            const ValueEnumerator &VE,
 843                            BitstreamWriter &Stream, bool isGlobal) {
 844   if (FirstVal == LastVal) return;
 845
 846   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
 847
 848   unsigned AggregateAbbrev = 0;
 849   unsigned String8Abbrev = 0;
 850   unsigned CString7Abbrev = 0;
 851   unsigned CString6Abbrev = 0;
 852   // If this is a constant pool for the module, emit module-specific abbrevs.
 853   if (isGlobal) {
 854     // Abbrev for CST_CODE_AGGREGATE.
 855     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
 856     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
 857     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 858     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
 859     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
 860
 861     // Abbrev for CST_CODE_STRING.
 862     Abbv = new BitCodeAbbrev();
 863     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
 864     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 865     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
 866     String8Abbrev = Stream.EmitAbbrev(Abbv);
 867     // Abbrev for CST_CODE_CSTRING.
 868     Abbv = new BitCodeAbbrev();
 869     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 870     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 871     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
 872     CString7Abbrev = Stream.EmitAbbrev(Abbv);
 873     // Abbrev for CST_CODE_CSTRING.
 874     Abbv = new BitCodeAbbrev();
 875     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
 876     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
 877     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
 878     CString6Abbrev = Stream.EmitAbbrev(Abbv);
 879   }
 880
 881   SmallVector<uint64_t, 64> Record;
 882
 883   const ValueEnumerator::ValueList &Vals = VE.getValues();
 884   Type *LastTy = 0;
 885   for (unsigned i = FirstVal; i != LastVal; ++i) {
 886     const Value *V = Vals[i].first;
 887     // If we need to switch types, do so now.
 888     if (V->getType() != LastTy) {
 889       LastTy = V->getType();
 890       Record.push_back(VE.getTypeID(LastTy));
 891       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
 892                         CONSTANTS_SETTYPE_ABBREV);
 893       Record.clear();
 894     }
 895
 896     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
 897       Record.push_back(unsigned(IA->hasSideEffects()) |
 898                        unsigned(IA->isAlignStack()) << 1 |
 899                        unsigned(IA->getDialect()&1) << 2);
 900
 901       // Add the asm string.
 902       const std::string &AsmStr = IA->getAsmString();
 903       Record.push_back(AsmStr.size());
 904       for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
 905         Record.push_back(AsmStr[i]);
 906
 907       // Add the constraint string.
 908       const std::string &ConstraintStr = IA->getConstraintString();
 909       Record.push_back(ConstraintStr.size());
 910       for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
 911         Record.push_back(ConstraintStr[i]);
 912       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
 913       Record.clear();
 914       continue;
 915     }
 916     const Constant *C = cast<Constant>(V);
 917     unsigned Code = -1U;
 918     unsigned AbbrevToUse = 0;
 919     if (C->isNullValue()) {
 920       Code = bitc::CST_CODE_NULL;
 921     } else if (isa<UndefValue>(C)) {
 922       Code = bitc::CST_CODE_UNDEF;
 923     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
 924       EmitAPInt(Record, Code, AbbrevToUse, IV->getValue());
 925     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
 926       Code = bitc::CST_CODE_FLOAT;
 927       Type *Ty = CFP->getType();
 928       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
 929         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
 930       } else if (Ty->isX86_FP80Ty()) {
 931         // api needed to prevent premature destruction
 932         // bits are not in the same order as a normal i80 APInt, compensate.
 933         APInt api = CFP->getValueAPF().bitcastToAPInt();
 934         const uint64_t *p = api.getRawData();
 935         Record.push_back((p[1] << 48) | (p[0] >> 16));
 936         Record.push_back(p[0] & 0xffffLL);
 937       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
 938         APInt api = CFP->getValueAPF().bitcastToAPInt();
 939         const uint64_t *p = api.getRawData();
 940         Record.push_back(p[0]);
 941         Record.push_back(p[1]);
 942       } else {
 943         assert (0 && "Unknown FP type!");
 944       }
 945     } else if (isa<ConstantDataSequential>(C) &&
 946                cast<ConstantDataSequential>(C)->isString()) {
 947       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
 948       // Emit constant strings specially.
 949       unsigned NumElts = Str->getNumElements();
 950       // If this is a null-terminated string, use the denser CSTRING encoding.
 951       if (Str->isCString()) {
 952         Code = bitc::CST_CODE_CSTRING;
 953         --NumElts;  // Don't encode the null, which isn't allowed by char6.
 954       } else {
 955         Code = bitc::CST_CODE_STRING;
 956         AbbrevToUse = String8Abbrev;
 957       }
 958       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
 959       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
 960       for (unsigned i = 0; i != NumElts; ++i) {
 961         unsigned char V = Str->getElementAsInteger(i);
 962         Record.push_back(V);
 963         isCStr7 &= (V & 128) == 0;
 964         if (isCStrChar6)
 965           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
 966       }
 967
 968       if (isCStrChar6)
 969         AbbrevToUse = CString6Abbrev;
 970       else if (isCStr7)
 971         AbbrevToUse = CString7Abbrev;
 972     } else if (const ConstantDataSequential *CDS =
 973                   dyn_cast<ConstantDataSequential>(C)) {
 974       Code = bitc::CST_CODE_DATA;
 975       Type *EltTy = CDS->getType()->getElementType();
 976       if (isa<IntegerType>(EltTy)) {
 977         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
 978           Record.push_back(CDS->getElementAsInteger(i));
 979       } else if (EltTy->isFloatTy()) {
 980         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 981           union { float F; uint32_t I; };
 982           F = CDS->getElementAsFloat(i);
 983           Record.push_back(I);
 984         }
 985       } else {
 986         assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
 987         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
 988           union { double F; uint64_t I; };
 989           F = CDS->getElementAsDouble(i);
 990           Record.push_back(I);
 991         }
 992       }
 993     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
 994                isa<ConstantVector>(C)) {
 995       Code = bitc::CST_CODE_AGGREGATE;
 996       for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
 997         Record.push_back(VE.getValueID(C->getOperand(i)));
 998       AbbrevToUse = AggregateAbbrev;
 999     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1000       switch (CE->getOpcode()) {
1001       default:
1002         if (Instruction::isCast(CE->getOpcode())) {
1003           Code = bitc::CST_CODE_CE_CAST;
1004           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1005           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1006           Record.push_back(VE.getValueID(C->getOperand(0)));
1007           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1008         } else {
1009           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1010           Code = bitc::CST_CODE_CE_BINOP;
1011           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1012           Record.push_back(VE.getValueID(C->getOperand(0)));
1013           Record.push_back(VE.getValueID(C->getOperand(1)));
1014           uint64_t Flags = GetOptimizationFlags(CE);
1015           if (Flags != 0)
1016             Record.push_back(Flags);
1017         }
1018         break;
1019       case Instruction::GetElementPtr:
1020         Code = bitc::CST_CODE_CE_GEP;
1021         if (cast<GEPOperator>(C)->isInBounds())
1022           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1023         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1024           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1025           Record.push_back(VE.getValueID(C->getOperand(i)));
1026         }
1027         break;
1028       case Instruction::Select:
1029         Code = bitc::CST_CODE_CE_SELECT;
1030         Record.push_back(VE.getValueID(C->getOperand(0)));
1031         Record.push_back(VE.getValueID(C->getOperand(1)));
1032         Record.push_back(VE.getValueID(C->getOperand(2)));
1033         break;
1034       case Instruction::ExtractElement:
1035         Code = bitc::CST_CODE_CE_EXTRACTELT;
1036         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1037         Record.push_back(VE.getValueID(C->getOperand(0)));
1038         Record.push_back(VE.getValueID(C->getOperand(1)));
1039         break;
1040       case Instruction::InsertElement:
1041         Code = bitc::CST_CODE_CE_INSERTELT;
1042         Record.push_back(VE.getValueID(C->getOperand(0)));
1043         Record.push_back(VE.getValueID(C->getOperand(1)));
1044         Record.push_back(VE.getValueID(C->getOperand(2)));
1045         break;
1046       case Instruction::ShuffleVector:
1047         // If the return type and argument types are the same, this is a
1048         // standard shufflevector instruction.  If the types are different,
1049         // then the shuffle is widening or truncating the input vectors, and
1050         // the argument type must also be encoded.
1051         if (C->getType() == C->getOperand(0)->getType()) {
1052           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1053         } else {
1054           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1055           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1056         }
1057         Record.push_back(VE.getValueID(C->getOperand(0)));
1058         Record.push_back(VE.getValueID(C->getOperand(1)));
1059         Record.push_back(VE.getValueID(C->getOperand(2)));
1060         break;
1061       case Instruction::ICmp:
1062       case Instruction::FCmp:
1063         Code = bitc::CST_CODE_CE_CMP;
1064         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1065         Record.push_back(VE.getValueID(C->getOperand(0)));
1066         Record.push_back(VE.getValueID(C->getOperand(1)));
1067         Record.push_back(CE->getPredicate());
1068         break;
1069       }
1070     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1071       Code = bitc::CST_CODE_BLOCKADDRESS;
1072       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1073       Record.push_back(VE.getValueID(BA->getFunction()));
1074       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1075     } else {
1076 #ifndef NDEBUG
1077       C->dump();
1078 #endif
1079       llvm_unreachable("Unknown constant!");
1080     }
1081     Stream.EmitRecord(Code, Record, AbbrevToUse);
1082     Record.clear();
1083   }
1084
1085   Stream.ExitBlock();
1086 }
1087
1088 static void WriteModuleConstants(const ValueEnumerator &VE,
1089                                  BitstreamWriter &Stream) {
1090   const ValueEnumerator::ValueList &Vals = VE.getValues();
1091
1092   // Find the first constant to emit, which is the first non-globalvalue value.
1093   // We know globalvalues have been emitted by WriteModuleInfo.
1094   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1095     if (!isa<GlobalValue>(Vals[i].first)) {
1096       WriteConstants(i, Vals.size(), VE, Stream, true);
1097       return;
1098     }
1099   }
1100 }
1101
1102 /// PushValueAndType - The file has to encode both the value and type id for
1103 /// many values, because we need to know what type to create for forward
1104 /// references.  However, most operands are not forward references, so this type
1105 /// field is not needed.
1106 ///
1107 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1108 /// instruction ID, then it is a forward reference, and it also includes the
1109 /// type ID.  The value ID that is written is encoded relative to the InstID.
1110 static bool PushValueAndType(const Value *V, unsigned InstID,
1111                              SmallVector<unsigned, 64> &Vals,
1112                              ValueEnumerator &VE) {
1113   unsigned ValID = VE.getValueID(V);
1114   // Make encoding relative to the InstID.
1115   Vals.push_back(InstID - ValID);
1116   if (ValID >= InstID) {
1117     Vals.push_back(VE.getTypeID(V->getType()));
1118     return true;
1119   }
1120   return false;
1121 }
1122
1123 /// pushValue - Like PushValueAndType, but where the type of the value is
1124 /// omitted (perhaps it was already encoded in an earlier operand).
1125 static void pushValue(const Value *V, unsigned InstID,
1126                       SmallVector<unsigned, 64> &Vals,
1127                       ValueEnumerator &VE) {
1128   unsigned ValID = VE.getValueID(V);
1129   Vals.push_back(InstID - ValID);
1130 }
1131
1132 static void pushValue64(const Value *V, unsigned InstID,
1133                         SmallVector<uint64_t, 128> &Vals,
1134                         ValueEnumerator &VE) {
1135   uint64_t ValID = VE.getValueID(V);
1136   Vals.push_back(InstID - ValID);
1137 }
1138
1139 static void pushValueSigned(const Value *V, unsigned InstID,
1140                             SmallVector<uint64_t, 128> &Vals,
1141                             ValueEnumerator &VE) {
1142   unsigned ValID = VE.getValueID(V);
1143   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1144   emitSignedInt64(Vals, diff);
1145 }
1146
1147 /// WriteInstruction - Emit an instruction to the specified stream.
1148 static void WriteInstruction(const Instruction &I, unsigned InstID,
1149                              ValueEnumerator &VE, BitstreamWriter &Stream,
1150                              SmallVector<unsigned, 64> &Vals) {
1151   unsigned Code = 0;
1152   unsigned AbbrevToUse = 0;
1153   VE.setInstructionID(&I);
1154   switch (I.getOpcode()) {
1155   default:
1156     if (Instruction::isCast(I.getOpcode())) {
1157       Code = bitc::FUNC_CODE_INST_CAST;
1158       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1159         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1160       Vals.push_back(VE.getTypeID(I.getType()));
1161       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1162     } else {
1163       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1164       Code = bitc::FUNC_CODE_INST_BINOP;
1165       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1166         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1167       pushValue(I.getOperand(1), InstID, Vals, VE);
1168       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1169       uint64_t Flags = GetOptimizationFlags(&I);
1170       if (Flags != 0) {
1171         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1172           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1173         Vals.push_back(Flags);
1174       }
1175     }
1176     break;
1177
1178   case Instruction::GetElementPtr:
1179     Code = bitc::FUNC_CODE_INST_GEP;
1180     if (cast<GEPOperator>(&I)->isInBounds())
1181       Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1182     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1183       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1184     break;
1185   case Instruction::ExtractValue: {
1186     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1187     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1188     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1189     for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1190       Vals.push_back(*i);
1191     break;
1192   }
1193   case Instruction::InsertValue: {
1194     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1195     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1196     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1197     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1198     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1199       Vals.push_back(*i);
1200     break;
1201   }
1202   case Instruction::Select:
1203     Code = bitc::FUNC_CODE_INST_VSELECT;
1204     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1205     pushValue(I.getOperand(2), InstID, Vals, VE);
1206     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1207     break;
1208   case Instruction::ExtractElement:
1209     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1210     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1211     pushValue(I.getOperand(1), InstID, Vals, VE);
1212     break;
1213   case Instruction::InsertElement:
1214     Code = bitc::FUNC_CODE_INST_INSERTELT;
1215     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1216     pushValue(I.getOperand(1), InstID, Vals, VE);
1217     pushValue(I.getOperand(2), InstID, Vals, VE);
1218     break;
1219   case Instruction::ShuffleVector:
1220     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1221     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1222     pushValue(I.getOperand(1), InstID, Vals, VE);
1223     pushValue(I.getOperand(2), InstID, Vals, VE);
1224     break;
1225   case Instruction::ICmp:
1226   case Instruction::FCmp:
1227     // compare returning Int1Ty or vector of Int1Ty
1228     Code = bitc::FUNC_CODE_INST_CMP2;
1229     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1230     pushValue(I.getOperand(1), InstID, Vals, VE);
1231     Vals.push_back(cast<CmpInst>(I).getPredicate());
1232     break;
1233
1234   case Instruction::Ret:
1235     {
1236       Code = bitc::FUNC_CODE_INST_RET;
1237       unsigned NumOperands = I.getNumOperands();
1238       if (NumOperands == 0)
1239         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1240       else if (NumOperands == 1) {
1241         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1242           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1243       } else {
1244         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1245           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1246       }
1247     }
1248     break;
1249   case Instruction::Br:
1250     {
1251       Code = bitc::FUNC_CODE_INST_BR;
1252       const BranchInst &II = cast<BranchInst>(I);
1253       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1254       if (II.isConditional()) {
1255         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1256         pushValue(II.getCondition(), InstID, Vals, VE);
1257       }
1258     }
1259     break;
1260   case Instruction::Switch:
1261     {
1262       // Redefine Vals, since here we need to use 64 bit values
1263       // explicitly to store large APInt numbers.
1264       SmallVector<uint64_t, 128> Vals64;
1265
1266       Code = bitc::FUNC_CODE_INST_SWITCH;
1267       const SwitchInst &SI = cast<SwitchInst>(I);
1268
1269       uint32_t SwitchRecordHeader = SI.hash() | (SWITCH_INST_MAGIC << 16);
1270       Vals64.push_back(SwitchRecordHeader);
1271
1272       Vals64.push_back(VE.getTypeID(SI.getCondition()->getType()));
1273       pushValue64(SI.getCondition(), InstID, Vals64, VE);
1274       Vals64.push_back(VE.getValueID(SI.getDefaultDest()));
1275       Vals64.push_back(SI.getNumCases());
1276       for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1277            i != e; ++i) {
1278         const IntegersSubset& CaseRanges = i.getCaseValueEx();
1279         unsigned Code, Abbrev; // will unused.
1280
1281         if (CaseRanges.isSingleNumber()) {
1282           Vals64.push_back(1/*NumItems = 1*/);
1283           Vals64.push_back(true/*IsSingleNumber = true*/);
1284           EmitAPInt(Vals64, Code, Abbrev, CaseRanges.getSingleNumber(0), true);
1285         } else {
1286
1287           Vals64.push_back(CaseRanges.getNumItems());
1288
1289           if (CaseRanges.isSingleNumbersOnly()) {
1290             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1291                  ri != rn; ++ri) {
1292
1293               Vals64.push_back(true/*IsSingleNumber = true*/);
1294
1295               EmitAPInt(Vals64, Code, Abbrev,
1296                         CaseRanges.getSingleNumber(ri), true);
1297             }
1298           } else
1299             for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1300                  ri != rn; ++ri) {
1301               IntegersSubset::Range r = CaseRanges.getItem(ri);
1302               bool IsSingleNumber = CaseRanges.isSingleNumber(ri);
1303
1304               Vals64.push_back(IsSingleNumber);
1305
1306               EmitAPInt(Vals64, Code, Abbrev, r.getLow(), true);
1307               if (!IsSingleNumber)
1308                 EmitAPInt(Vals64, Code, Abbrev, r.getHigh(), true);
1309             }
1310         }
1311         Vals64.push_back(VE.getValueID(i.getCaseSuccessor()));
1312       }
1313
1314       Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1315
1316       // Also do expected action - clear external Vals collection:
1317       Vals.clear();
1318       return;
1319     }
1320     break;
1321   case Instruction::IndirectBr:
1322     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1323     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1324     // Encode the address operand as relative, but not the basic blocks.
1325     pushValue(I.getOperand(0), InstID, Vals, VE);
1326     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1327       Vals.push_back(VE.getValueID(I.getOperand(i)));
1328     break;
1329
1330   case Instruction::Invoke: {
1331     const InvokeInst *II = cast<InvokeInst>(&I);
1332     const Value *Callee(II->getCalledValue());
1333     PointerType *PTy = cast<PointerType>(Callee->getType());
1334     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1335     Code = bitc::FUNC_CODE_INST_INVOKE;
1336
1337     Vals.push_back(VE.getAttributeID(II->getAttributes()));
1338     Vals.push_back(II->getCallingConv());
1339     Vals.push_back(VE.getValueID(II->getNormalDest()));
1340     Vals.push_back(VE.getValueID(II->getUnwindDest()));
1341     PushValueAndType(Callee, InstID, Vals, VE);
1342
1343     // Emit value #'s for the fixed parameters.
1344     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1345       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1346
1347     // Emit type/value pairs for varargs params.
1348     if (FTy->isVarArg()) {
1349       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1350            i != e; ++i)
1351         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1352     }
1353     break;
1354   }
1355   case Instruction::Resume:
1356     Code = bitc::FUNC_CODE_INST_RESUME;
1357     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1358     break;
1359   case Instruction::Unreachable:
1360     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1361     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1362     break;
1363
1364   case Instruction::PHI: {
1365     const PHINode &PN = cast<PHINode>(I);
1366     Code = bitc::FUNC_CODE_INST_PHI;
1367     // With the newer instruction encoding, forward references could give
1368     // negative valued IDs.  This is most common for PHIs, so we use
1369     // signed VBRs.
1370     SmallVector<uint64_t, 128> Vals64;
1371     Vals64.push_back(VE.getTypeID(PN.getType()));
1372     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1373       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1374       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1375     }
1376     // Emit a Vals64 vector and exit.
1377     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1378     Vals64.clear();
1379     return;
1380   }
1381
1382   case Instruction::LandingPad: {
1383     const LandingPadInst &LP = cast<LandingPadInst>(I);
1384     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1385     Vals.push_back(VE.getTypeID(LP.getType()));
1386     PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1387     Vals.push_back(LP.isCleanup());
1388     Vals.push_back(LP.getNumClauses());
1389     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1390       if (LP.isCatch(I))
1391         Vals.push_back(LandingPadInst::Catch);
1392       else
1393         Vals.push_back(LandingPadInst::Filter);
1394       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1395     }
1396     break;
1397   }
1398
1399   case Instruction::Alloca:
1400     Code = bitc::FUNC_CODE_INST_ALLOCA;
1401     Vals.push_back(VE.getTypeID(I.getType()));
1402     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1403     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1404     Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1405     break;
1406
1407   case Instruction::Load:
1408     if (cast<LoadInst>(I).isAtomic()) {
1409       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1410       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1411     } else {
1412       Code = bitc::FUNC_CODE_INST_LOAD;
1413       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1414         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1415     }
1416     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1417     Vals.push_back(cast<LoadInst>(I).isVolatile());
1418     if (cast<LoadInst>(I).isAtomic()) {
1419       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1420       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1421     }
1422     break;
1423   case Instruction::Store:
1424     if (cast<StoreInst>(I).isAtomic())
1425       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1426     else
1427       Code = bitc::FUNC_CODE_INST_STORE;
1428     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1429     pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1430     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1431     Vals.push_back(cast<StoreInst>(I).isVolatile());
1432     if (cast<StoreInst>(I).isAtomic()) {
1433       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1434       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1435     }
1436     break;
1437   case Instruction::AtomicCmpXchg:
1438     Code = bitc::FUNC_CODE_INST_CMPXCHG;
1439     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1440     pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1441     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1442     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1443     Vals.push_back(GetEncodedOrdering(
1444                      cast<AtomicCmpXchgInst>(I).getOrdering()));
1445     Vals.push_back(GetEncodedSynchScope(
1446                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
1447     break;
1448   case Instruction::AtomicRMW:
1449     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1450     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1451     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1452     Vals.push_back(GetEncodedRMWOperation(
1453                      cast<AtomicRMWInst>(I).getOperation()));
1454     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1455     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1456     Vals.push_back(GetEncodedSynchScope(
1457                      cast<AtomicRMWInst>(I).getSynchScope()));
1458     break;
1459   case Instruction::Fence:
1460     Code = bitc::FUNC_CODE_INST_FENCE;
1461     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1462     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1463     break;
1464   case Instruction::Call: {
1465     const CallInst &CI = cast<CallInst>(I);
1466     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1467     FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1468
1469     Code = bitc::FUNC_CODE_INST_CALL;
1470
1471     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1472     Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1473     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1474
1475     // Emit value #'s for the fixed parameters.
1476     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1477       // Check for labels (can happen with asm labels).
1478       if (FTy->getParamType(i)->isLabelTy())
1479         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1480       else
1481         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1482     }
1483
1484     // Emit type/value pairs for varargs params.
1485     if (FTy->isVarArg()) {
1486       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1487            i != e; ++i)
1488         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1489     }
1490     break;
1491   }
1492   case Instruction::VAArg:
1493     Code = bitc::FUNC_CODE_INST_VAARG;
1494     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1495     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1496     Vals.push_back(VE.getTypeID(I.getType())); // restype.
1497     break;
1498   }
1499
1500   Stream.EmitRecord(Code, Vals, AbbrevToUse);
1501   Vals.clear();
1502 }
1503
1504 // Emit names for globals/functions etc.
1505 static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1506                                   const ValueEnumerator &VE,
1507                                   BitstreamWriter &Stream) {
1508   if (VST.empty()) return;
1509   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1510
1511   // FIXME: Set up the abbrev, we know how many values there are!
1512   // FIXME: We know if the type names can use 7-bit ascii.
1513   SmallVector<unsigned, 64> NameVals;
1514
1515   for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1516        SI != SE; ++SI) {
1517
1518     const ValueName &Name = *SI;
1519
1520     // Figure out the encoding to use for the name.
1521     bool is7Bit = true;
1522     bool isChar6 = true;
1523     for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1524          C != E; ++C) {
1525       if (isChar6)
1526         isChar6 = BitCodeAbbrevOp::isChar6(*C);
1527       if ((unsigned char)*C & 128) {
1528         is7Bit = false;
1529         break;  // don't bother scanning the rest.
1530       }
1531     }
1532
1533     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1534
1535     // VST_ENTRY:   [valueid, namechar x N]
1536     // VST_BBENTRY: [bbid, namechar x N]
1537     unsigned Code;
1538     if (isa<BasicBlock>(SI->getValue())) {
1539       Code = bitc::VST_CODE_BBENTRY;
1540       if (isChar6)
1541         AbbrevToUse = VST_BBENTRY_6_ABBREV;
1542     } else {
1543       Code = bitc::VST_CODE_ENTRY;
1544       if (isChar6)
1545         AbbrevToUse = VST_ENTRY_6_ABBREV;
1546       else if (is7Bit)
1547         AbbrevToUse = VST_ENTRY_7_ABBREV;
1548     }
1549
1550     NameVals.push_back(VE.getValueID(SI->getValue()));
1551     for (const char *P = Name.getKeyData(),
1552          *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1553       NameVals.push_back((unsigned char)*P);
1554
1555     // Emit the finished record.
1556     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1557     NameVals.clear();
1558   }
1559   Stream.ExitBlock();
1560 }
1561
1562 /// WriteFunction - Emit a function body to the module stream.
1563 static void WriteFunction(const Function &F, ValueEnumerator &VE,
1564                           BitstreamWriter &Stream) {
1565   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1566   VE.incorporateFunction(F);
1567
1568   SmallVector<unsigned, 64> Vals;
1569
1570   // Emit the number of basic blocks, so the reader can create them ahead of
1571   // time.
1572   Vals.push_back(VE.getBasicBlocks().size());
1573   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1574   Vals.clear();
1575
1576   // If there are function-local constants, emit them now.
1577   unsigned CstStart, CstEnd;
1578   VE.getFunctionConstantRange(CstStart, CstEnd);
1579   WriteConstants(CstStart, CstEnd, VE, Stream, false);
1580
1581   // If there is function-local metadata, emit it now.
1582   WriteFunctionLocalMetadata(F, VE, Stream);
1583
1584   // Keep a running idea of what the instruction ID is.
1585   unsigned InstID = CstEnd;
1586
1587   bool NeedsMetadataAttachment = false;
1588
1589   DebugLoc LastDL;
1590
1591   // Finally, emit all the instructions, in order.
1592   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1593     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1594          I != E; ++I) {
1595       WriteInstruction(*I, InstID, VE, Stream, Vals);
1596
1597       if (!I->getType()->isVoidTy())
1598         ++InstID;
1599
1600       // If the instruction has metadata, write a metadata attachment later.
1601       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1602
1603       // If the instruction has a debug location, emit it.
1604       DebugLoc DL = I->getDebugLoc();
1605       if (DL.isUnknown()) {
1606         // nothing todo.
1607       } else if (DL == LastDL) {
1608         // Just repeat the same debug loc as last time.
1609         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1610       } else {
1611         MDNode *Scope, *IA;
1612         DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1613
1614         Vals.push_back(DL.getLine());
1615         Vals.push_back(DL.getCol());
1616         Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1617         Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1618         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1619         Vals.clear();
1620
1621         LastDL = DL;
1622       }
1623     }
1624
1625   // Emit names for all the instructions etc.
1626   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1627
1628   if (NeedsMetadataAttachment)
1629     WriteMetadataAttachment(F, VE, Stream);
1630   VE.purgeFunction();
1631   Stream.ExitBlock();
1632 }
1633
1634 // Emit blockinfo, which defines the standard abbreviations etc.
1635 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1636   // We only want to emit block info records for blocks that have multiple
1637   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1638   // Other blocks can define their abbrevs inline.
1639   Stream.EnterBlockInfoBlock(2);
1640
1641   { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1642     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1643     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1644     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1645     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1646     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1647     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1648                                    Abbv) != VST_ENTRY_8_ABBREV)
1649       llvm_unreachable("Unexpected abbrev ordering!");
1650   }
1651
1652   { // 7-bit fixed width VST_ENTRY strings.
1653     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1654     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1655     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1656     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1657     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1658     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1659                                    Abbv) != VST_ENTRY_7_ABBREV)
1660       llvm_unreachable("Unexpected abbrev ordering!");
1661   }
1662   { // 6-bit char6 VST_ENTRY strings.
1663     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1664     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1665     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1666     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1667     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1668     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1669                                    Abbv) != VST_ENTRY_6_ABBREV)
1670       llvm_unreachable("Unexpected abbrev ordering!");
1671   }
1672   { // 6-bit char6 VST_BBENTRY strings.
1673     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1674     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1675     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1676     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1677     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1678     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1679                                    Abbv) != VST_BBENTRY_6_ABBREV)
1680       llvm_unreachable("Unexpected abbrev ordering!");
1681   }
1682
1683
1684
1685   { // SETTYPE abbrev for CONSTANTS_BLOCK.
1686     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1687     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1688     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1689                               Log2_32_Ceil(VE.getTypes().size()+1)));
1690     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1691                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
1692       llvm_unreachable("Unexpected abbrev ordering!");
1693   }
1694
1695   { // INTEGER abbrev for CONSTANTS_BLOCK.
1696     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1697     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1698     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1699     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1700                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
1701       llvm_unreachable("Unexpected abbrev ordering!");
1702   }
1703
1704   { // CE_CAST abbrev for CONSTANTS_BLOCK.
1705     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1706     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1707     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1708     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1709                               Log2_32_Ceil(VE.getTypes().size()+1)));
1710     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1711
1712     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1713                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
1714       llvm_unreachable("Unexpected abbrev ordering!");
1715   }
1716   { // NULL abbrev for CONSTANTS_BLOCK.
1717     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1718     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1719     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1720                                    Abbv) != CONSTANTS_NULL_Abbrev)
1721       llvm_unreachable("Unexpected abbrev ordering!");
1722   }
1723
1724   // FIXME: This should only use space for first class types!
1725
1726   { // INST_LOAD abbrev for FUNCTION_BLOCK.
1727     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1728     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1729     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1730     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1731     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1732     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1733                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
1734       llvm_unreachable("Unexpected abbrev ordering!");
1735   }
1736   { // INST_BINOP abbrev for FUNCTION_BLOCK.
1737     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1738     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1739     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1740     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1741     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1742     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1743                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
1744       llvm_unreachable("Unexpected abbrev ordering!");
1745   }
1746   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1747     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1748     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1749     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1750     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1751     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1752     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1753     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1754                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1755       llvm_unreachable("Unexpected abbrev ordering!");
1756   }
1757   { // INST_CAST abbrev for FUNCTION_BLOCK.
1758     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1759     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1760     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1761     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1762                               Log2_32_Ceil(VE.getTypes().size()+1)));
1763     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1764     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1765                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
1766       llvm_unreachable("Unexpected abbrev ordering!");
1767   }
1768
1769   { // INST_RET abbrev for FUNCTION_BLOCK.
1770     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1771     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1772     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1773                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1774       llvm_unreachable("Unexpected abbrev ordering!");
1775   }
1776   { // INST_RET abbrev for FUNCTION_BLOCK.
1777     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1778     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1779     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1780     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1781                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1782       llvm_unreachable("Unexpected abbrev ordering!");
1783   }
1784   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1785     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1786     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1787     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1788                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1789       llvm_unreachable("Unexpected abbrev ordering!");
1790   }
1791
1792   Stream.ExitBlock();
1793 }
1794
1795 // Sort the Users based on the order in which the reader parses the bitcode
1796 // file.
1797 static bool bitcodereader_order(const User *lhs, const User *rhs) {
1798   // TODO: Implement.
1799   return true;
1800 }
1801
1802 static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1803                          BitstreamWriter &Stream) {
1804
1805   // One or zero uses can't get out of order.
1806   if (V->use_empty() || V->hasNUses(1))
1807     return;
1808
1809   // Make a copy of the in-memory use-list for sorting.
1810   unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1811   SmallVector<const User*, 8> UseList;
1812   UseList.reserve(UseListSize);
1813   for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1814        I != E; ++I) {
1815     const User *U = *I;
1816     UseList.push_back(U);
1817   }
1818
1819   // Sort the copy based on the order read by the BitcodeReader.
1820   std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1821
1822   // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1823   // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1824
1825   // TODO: Emit the USELIST_CODE_ENTRYs.
1826 }
1827
1828 static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1829                                  BitstreamWriter &Stream) {
1830   VE.incorporateFunction(*F);
1831
1832   for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1833        AI != AE; ++AI)
1834     WriteUseList(AI, VE, Stream);
1835   for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1836        ++BB) {
1837     WriteUseList(BB, VE, Stream);
1838     for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1839          ++II) {
1840       WriteUseList(II, VE, Stream);
1841       for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1842            OI != E; ++OI) {
1843         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1844             isa<InlineAsm>(*OI))
1845           WriteUseList(*OI, VE, Stream);
1846       }
1847     }
1848   }
1849   VE.purgeFunction();
1850 }
1851
1852 // Emit use-lists.
1853 static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1854                                 BitstreamWriter &Stream) {
1855   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1856
1857   // XXX: this modifies the module, but in a way that should never change the
1858   // behavior of any pass or codegen in LLVM. The problem is that GVs may
1859   // contain entries in the use_list that do not exist in the Module and are
1860   // not stored in the .bc file.
1861   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1862        I != E; ++I)
1863     I->removeDeadConstantUsers();
1864
1865   // Write the global variables.
1866   for (Module::const_global_iterator GI = M->global_begin(),
1867          GE = M->global_end(); GI != GE; ++GI) {
1868     WriteUseList(GI, VE, Stream);
1869
1870     // Write the global variable initializers.
1871     if (GI->hasInitializer())
1872       WriteUseList(GI->getInitializer(), VE, Stream);
1873   }
1874
1875   // Write the functions.
1876   for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1877     WriteUseList(FI, VE, Stream);
1878     if (!FI->isDeclaration())
1879       WriteFunctionUseList(FI, VE, Stream);
1880   }
1881
1882   // Write the aliases.
1883   for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1884        AI != AE; ++AI) {
1885     WriteUseList(AI, VE, Stream);
1886     WriteUseList(AI->getAliasee(), VE, Stream);
1887   }
1888
1889   Stream.ExitBlock();
1890 }
1891
1892 /// WriteModule - Emit the specified module to the bitstream.
1893 static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1894   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1895
1896   SmallVector<unsigned, 1> Vals;
1897   unsigned CurVersion = 1;
1898   Vals.push_back(CurVersion);
1899   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1900
1901   // Analyze the module, enumerating globals, functions, etc.
1902   ValueEnumerator VE(M);
1903
1904   // Emit blockinfo, which defines the standard abbreviations etc.
1905   WriteBlockInfo(VE, Stream);
1906
1907   // Emit information about attribute groups.
1908   WriteAttributeGroupTable(VE, Stream);
1909
1910   // Emit information about parameter attributes.
1911   WriteAttributeTable(VE, Stream);
1912
1913   // Emit information describing all of the types in the module.
1914   WriteTypeTable(VE, Stream);
1915
1916   // Emit top-level description of module, including target triple, inline asm,
1917   // descriptors for global variables, and function prototype info.
1918   WriteModuleInfo(M, VE, Stream);
1919
1920   // Emit constants.
1921   WriteModuleConstants(VE, Stream);
1922
1923   // Emit metadata.
1924   WriteModuleMetadata(M, VE, Stream);
1925
1926   // Emit metadata.
1927   WriteModuleMetadataStore(M, Stream);
1928
1929   // Emit names for globals/functions etc.
1930   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1931
1932   // Emit use-lists.
1933   if (EnablePreserveUseListOrdering)
1934     WriteModuleUseLists(M, VE, Stream);
1935
1936   // Emit function bodies.
1937   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1938     if (!F->isDeclaration())
1939       WriteFunction(*F, VE, Stream);
1940
1941   Stream.ExitBlock();
1942 }
1943
1944 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1945 /// header and trailer to make it compatible with the system archiver.  To do
1946 /// this we emit the following header, and then emit a trailer that pads the
1947 /// file out to be a multiple of 16 bytes.
1948 ///
1949 /// struct bc_header {
1950 ///   uint32_t Magic;         // 0x0B17C0DE
1951 ///   uint32_t Version;       // Version, currently always 0.
1952 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1953 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1954 ///   uint32_t CPUType;       // CPU specifier.
1955 ///   ... potentially more later ...
1956 /// };
1957 enum {
1958   DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1959   DarwinBCHeaderSize = 5*4
1960 };
1961
1962 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1963                                uint32_t &Position) {
1964   Buffer[Position + 0] = (unsigned char) (Value >>  0);
1965   Buffer[Position + 1] = (unsigned char) (Value >>  8);
1966   Buffer[Position + 2] = (unsigned char) (Value >> 16);
1967   Buffer[Position + 3] = (unsigned char) (Value >> 24);
1968   Position += 4;
1969 }
1970
1971 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1972                                          const Triple &TT) {
1973   unsigned CPUType = ~0U;
1974
1975   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1976   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1977   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1978   // specific constants here because they are implicitly part of the Darwin ABI.
1979   enum {
1980     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1981     DARWIN_CPU_TYPE_X86        = 7,
1982     DARWIN_CPU_TYPE_ARM        = 12,
1983     DARWIN_CPU_TYPE_POWERPC    = 18
1984   };
1985
1986   Triple::ArchType Arch = TT.getArch();
1987   if (Arch == Triple::x86_64)
1988     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1989   else if (Arch == Triple::x86)
1990     CPUType = DARWIN_CPU_TYPE_X86;
1991   else if (Arch == Triple::ppc)
1992     CPUType = DARWIN_CPU_TYPE_POWERPC;
1993   else if (Arch == Triple::ppc64)
1994     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1995   else if (Arch == Triple::arm || Arch == Triple::thumb)
1996     CPUType = DARWIN_CPU_TYPE_ARM;
1997
1998   // Traditional Bitcode starts after header.
1999   assert(Buffer.size() >= DarwinBCHeaderSize &&
2000          "Expected header size to be reserved");
2001   unsigned BCOffset = DarwinBCHeaderSize;
2002   unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
2003
2004   // Write the magic and version.
2005   unsigned Position = 0;
2006   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
2007   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
2008   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
2009   WriteInt32ToBuffer(BCSize     , Buffer, Position);
2010   WriteInt32ToBuffer(CPUType    , Buffer, Position);
2011
2012   // If the file is not a multiple of 16 bytes, insert dummy padding.
2013   while (Buffer.size() & 15)
2014     Buffer.push_back(0);
2015 }
2016
2017 /// WriteBitcodeToFile - Write the specified module to the specified output
2018 /// stream.
2019 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2020   SmallVector<char, 0> Buffer;
2021   Buffer.reserve(256*1024);
2022
2023   // If this is darwin or another generic macho target, reserve space for the
2024   // header.
2025   Triple TT(M->getTargetTriple());
2026   if (TT.isOSDarwin())
2027     Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2028
2029   // Emit the module into the buffer.
2030   {
2031     BitstreamWriter Stream(Buffer);
2032
2033     // Emit the file header.
2034     Stream.Emit((unsigned)'B', 8);
2035     Stream.Emit((unsigned)'C', 8);
2036     Stream.Emit(0x0, 4);
2037     Stream.Emit(0xC, 4);
2038     Stream.Emit(0xE, 4);
2039     Stream.Emit(0xD, 4);
2040
2041     // Emit the module.
2042     WriteModule(M, Stream);
2043   }
2044
2045   if (TT.isOSDarwin())
2046     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2047
2048   // Write the generated bitstream to "Out".
2049   Out.write((char*)&Buffer.front(), Buffer.size());
2050 }