BitcodeWriter.cpp revision d04a8d4b33ff316ca4cf961e06c9e312eff8e64f 
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/Constants.h"
20#include "llvm/DerivedTypes.h"
21#include "llvm/InlineAsm.h"
22#include "llvm/Instructions.h"
23#include "llvm/Module.h"
24#include "llvm/Operator.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Support/ErrorHandling.h"
27#include "llvm/Support/MathExtras.h"
28#include "llvm/Support/Program.h"
29#include "llvm/Support/raw_ostream.h"
30#include "llvm/ValueSymbolTable.h"
31#include <cctype>
32#include <map>
33using namespace llvm;
34
35static cl::opt<bool>
36EnablePreserveUseListOrdering("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.
43enum {
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
69static 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
87static 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
111static 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
128static 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
141static 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
149static 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.
165static void WriteAttributeTable(const ValueEnumerator &VE,
166                                BitstreamWriter &Stream) {
167  const std::vector<AttrListPtr> &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 AttrListPtr &A = Attrs[i];
175    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
176      const AttributeWithIndex &PAWI = A.getSlot(i);
177      Record.push_back(PAWI.Index);
178      Record.push_back(Attributes::encodeLLVMAttributesForBitcode(PAWI.Attrs));
179    }
180
181    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
182    Record.clear();
183  }
184
185  Stream.ExitBlock();
186}
187
188/// WriteTypeTable - Write out the type table for a module.
189static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
190  const ValueEnumerator::TypeList &TypeList = VE.getTypes();
191
192  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
193  SmallVector<uint64_t, 64> TypeVals;
194
195  uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
196
197  // Abbrev for TYPE_CODE_POINTER.
198  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
199  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
200  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
201  Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
202  unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
203
204  // Abbrev for TYPE_CODE_FUNCTION.
205  Abbv = new BitCodeAbbrev();
206  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
207  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
208  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
209  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
210
211  unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
212
213  // Abbrev for TYPE_CODE_STRUCT_ANON.
214  Abbv = new BitCodeAbbrev();
215  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
216  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
217  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
218  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
219
220  unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
221
222  // Abbrev for TYPE_CODE_STRUCT_NAME.
223  Abbv = new BitCodeAbbrev();
224  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
225  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
226  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
227  unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
228
229  // Abbrev for TYPE_CODE_STRUCT_NAMED.
230  Abbv = new BitCodeAbbrev();
231  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
232  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
233  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
234  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
235
236  unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
237
238  // Abbrev for TYPE_CODE_ARRAY.
239  Abbv = new BitCodeAbbrev();
240  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
241  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
242  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
243
244  unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
245
246  // Emit an entry count so the reader can reserve space.
247  TypeVals.push_back(TypeList.size());
248  Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
249  TypeVals.clear();
250
251  // Loop over all of the types, emitting each in turn.
252  for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
253    Type *T = TypeList[i];
254    int AbbrevToUse = 0;
255    unsigned Code = 0;
256
257    switch (T->getTypeID()) {
258    default: llvm_unreachable("Unknown type!");
259    case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
260    case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
261    case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
262    case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
263    case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
264    case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
265    case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
266    case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
267    case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
268    case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
269    case Type::IntegerTyID:
270      // INTEGER: [width]
271      Code = bitc::TYPE_CODE_INTEGER;
272      TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
273      break;
274    case Type::PointerTyID: {
275      PointerType *PTy = cast<PointerType>(T);
276      // POINTER: [pointee type, address space]
277      Code = bitc::TYPE_CODE_POINTER;
278      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
279      unsigned AddressSpace = PTy->getAddressSpace();
280      TypeVals.push_back(AddressSpace);
281      if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
282      break;
283    }
284    case Type::FunctionTyID: {
285      FunctionType *FT = cast<FunctionType>(T);
286      // FUNCTION: [isvararg, retty, paramty x N]
287      Code = bitc::TYPE_CODE_FUNCTION;
288      TypeVals.push_back(FT->isVarArg());
289      TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
290      for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
291        TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
292      AbbrevToUse = FunctionAbbrev;
293      break;
294    }
295    case Type::StructTyID: {
296      StructType *ST = cast<StructType>(T);
297      // STRUCT: [ispacked, eltty x N]
298      TypeVals.push_back(ST->isPacked());
299      // Output all of the element types.
300      for (StructType::element_iterator I = ST->element_begin(),
301           E = ST->element_end(); I != E; ++I)
302        TypeVals.push_back(VE.getTypeID(*I));
303
304      if (ST->isLiteral()) {
305        Code = bitc::TYPE_CODE_STRUCT_ANON;
306        AbbrevToUse = StructAnonAbbrev;
307      } else {
308        if (ST->isOpaque()) {
309          Code = bitc::TYPE_CODE_OPAQUE;
310        } else {
311          Code = bitc::TYPE_CODE_STRUCT_NAMED;
312          AbbrevToUse = StructNamedAbbrev;
313        }
314
315        // Emit the name if it is present.
316        if (!ST->getName().empty())
317          WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
318                            StructNameAbbrev, Stream);
319      }
320      break;
321    }
322    case Type::ArrayTyID: {
323      ArrayType *AT = cast<ArrayType>(T);
324      // ARRAY: [numelts, eltty]
325      Code = bitc::TYPE_CODE_ARRAY;
326      TypeVals.push_back(AT->getNumElements());
327      TypeVals.push_back(VE.getTypeID(AT->getElementType()));
328      AbbrevToUse = ArrayAbbrev;
329      break;
330    }
331    case Type::VectorTyID: {
332      VectorType *VT = cast<VectorType>(T);
333      // VECTOR [numelts, eltty]
334      Code = bitc::TYPE_CODE_VECTOR;
335      TypeVals.push_back(VT->getNumElements());
336      TypeVals.push_back(VE.getTypeID(VT->getElementType()));
337      break;
338    }
339    }
340
341    // Emit the finished record.
342    Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
343    TypeVals.clear();
344  }
345
346  Stream.ExitBlock();
347}
348
349static unsigned getEncodedLinkage(const GlobalValue *GV) {
350  switch (GV->getLinkage()) {
351  case GlobalValue::ExternalLinkage:                 return 0;
352  case GlobalValue::WeakAnyLinkage:                  return 1;
353  case GlobalValue::AppendingLinkage:                return 2;
354  case GlobalValue::InternalLinkage:                 return 3;
355  case GlobalValue::LinkOnceAnyLinkage:              return 4;
356  case GlobalValue::DLLImportLinkage:                return 5;
357  case GlobalValue::DLLExportLinkage:                return 6;
358  case GlobalValue::ExternalWeakLinkage:             return 7;
359  case GlobalValue::CommonLinkage:                   return 8;
360  case GlobalValue::PrivateLinkage:                  return 9;
361  case GlobalValue::WeakODRLinkage:                  return 10;
362  case GlobalValue::LinkOnceODRLinkage:              return 11;
363  case GlobalValue::AvailableExternallyLinkage:      return 12;
364  case GlobalValue::LinkerPrivateLinkage:            return 13;
365  case GlobalValue::LinkerPrivateWeakLinkage:        return 14;
366  case GlobalValue::LinkOnceODRAutoHideLinkage:      return 15;
367  }
368  llvm_unreachable("Invalid linkage");
369}
370
371static unsigned getEncodedVisibility(const GlobalValue *GV) {
372  switch (GV->getVisibility()) {
373  case GlobalValue::DefaultVisibility:   return 0;
374  case GlobalValue::HiddenVisibility:    return 1;
375  case GlobalValue::ProtectedVisibility: return 2;
376  }
377  llvm_unreachable("Invalid visibility");
378}
379
380static unsigned getEncodedThreadLocalMode(const GlobalVariable *GV) {
381  switch (GV->getThreadLocalMode()) {
382    case GlobalVariable::NotThreadLocal:         return 0;
383    case GlobalVariable::GeneralDynamicTLSModel: return 1;
384    case GlobalVariable::LocalDynamicTLSModel:   return 2;
385    case GlobalVariable::InitialExecTLSModel:    return 3;
386    case GlobalVariable::LocalExecTLSModel:      return 4;
387  }
388  llvm_unreachable("Invalid TLS model");
389}
390
391// Emit top-level description of module, including target triple, inline asm,
392// descriptors for global variables, and function prototype info.
393static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
394                            BitstreamWriter &Stream) {
395  // Emit various pieces of data attached to a module.
396  if (!M->getTargetTriple().empty())
397    WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
398                      0/*TODO*/, Stream);
399  if (!M->getDataLayout().empty())
400    WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
401                      0/*TODO*/, Stream);
402  if (!M->getModuleInlineAsm().empty())
403    WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
404                      0/*TODO*/, Stream);
405
406  // Emit information about sections and GC, computing how many there are. Also
407  // compute the maximum alignment value.
408  std::map<std::string, unsigned> SectionMap;
409  std::map<std::string, unsigned> GCMap;
410  unsigned MaxAlignment = 0;
411  unsigned MaxGlobalType = 0;
412  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
413       GV != E; ++GV) {
414    MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
415    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
416    if (GV->hasSection()) {
417      // Give section names unique ID's.
418      unsigned &Entry = SectionMap[GV->getSection()];
419      if (!Entry) {
420        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
421                          0/*TODO*/, Stream);
422        Entry = SectionMap.size();
423      }
424    }
425  }
426  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
427    MaxAlignment = std::max(MaxAlignment, F->getAlignment());
428    if (F->hasSection()) {
429      // Give section names unique ID's.
430      unsigned &Entry = SectionMap[F->getSection()];
431      if (!Entry) {
432        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
433                          0/*TODO*/, Stream);
434        Entry = SectionMap.size();
435      }
436    }
437    if (F->hasGC()) {
438      // Same for GC names.
439      unsigned &Entry = GCMap[F->getGC()];
440      if (!Entry) {
441        WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
442                          0/*TODO*/, Stream);
443        Entry = GCMap.size();
444      }
445    }
446  }
447
448  // Emit abbrev for globals, now that we know # sections and max alignment.
449  unsigned SimpleGVarAbbrev = 0;
450  if (!M->global_empty()) {
451    // Add an abbrev for common globals with no visibility or thread localness.
452    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
453    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
454    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
455                              Log2_32_Ceil(MaxGlobalType+1)));
456    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
457    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
458    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
459    if (MaxAlignment == 0)                                      // Alignment.
460      Abbv->Add(BitCodeAbbrevOp(0));
461    else {
462      unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
463      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
464                               Log2_32_Ceil(MaxEncAlignment+1)));
465    }
466    if (SectionMap.empty())                                    // Section.
467      Abbv->Add(BitCodeAbbrevOp(0));
468    else
469      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
470                               Log2_32_Ceil(SectionMap.size()+1)));
471    // Don't bother emitting vis + thread local.
472    SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
473  }
474
475  // Emit the global variable information.
476  SmallVector<unsigned, 64> Vals;
477  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
478       GV != E; ++GV) {
479    unsigned AbbrevToUse = 0;
480
481    // GLOBALVAR: [type, isconst, initid,
482    //             linkage, alignment, section, visibility, threadlocal,
483    //             unnamed_addr]
484    Vals.push_back(VE.getTypeID(GV->getType()));
485    Vals.push_back(GV->isConstant());
486    Vals.push_back(GV->isDeclaration() ? 0 :
487                   (VE.getValueID(GV->getInitializer()) + 1));
488    Vals.push_back(getEncodedLinkage(GV));
489    Vals.push_back(Log2_32(GV->getAlignment())+1);
490    Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
491    if (GV->isThreadLocal() ||
492        GV->getVisibility() != GlobalValue::DefaultVisibility ||
493        GV->hasUnnamedAddr()) {
494      Vals.push_back(getEncodedVisibility(GV));
495      Vals.push_back(getEncodedThreadLocalMode(GV));
496      Vals.push_back(GV->hasUnnamedAddr());
497    } else {
498      AbbrevToUse = SimpleGVarAbbrev;
499    }
500
501    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
502    Vals.clear();
503  }
504
505  // Emit the function proto information.
506  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
507    // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
508    //             section, visibility, gc, unnamed_addr]
509    Vals.push_back(VE.getTypeID(F->getType()));
510    Vals.push_back(F->getCallingConv());
511    Vals.push_back(F->isDeclaration());
512    Vals.push_back(getEncodedLinkage(F));
513    Vals.push_back(VE.getAttributeID(F->getAttributes()));
514    Vals.push_back(Log2_32(F->getAlignment())+1);
515    Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
516    Vals.push_back(getEncodedVisibility(F));
517    Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
518    Vals.push_back(F->hasUnnamedAddr());
519
520    unsigned AbbrevToUse = 0;
521    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
522    Vals.clear();
523  }
524
525  // Emit the alias information.
526  for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
527       AI != E; ++AI) {
528    // ALIAS: [alias type, aliasee val#, linkage, visibility]
529    Vals.push_back(VE.getTypeID(AI->getType()));
530    Vals.push_back(VE.getValueID(AI->getAliasee()));
531    Vals.push_back(getEncodedLinkage(AI));
532    Vals.push_back(getEncodedVisibility(AI));
533    unsigned AbbrevToUse = 0;
534    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
535    Vals.clear();
536  }
537}
538
539static uint64_t GetOptimizationFlags(const Value *V) {
540  uint64_t Flags = 0;
541
542  if (const OverflowingBinaryOperator *OBO =
543        dyn_cast<OverflowingBinaryOperator>(V)) {
544    if (OBO->hasNoSignedWrap())
545      Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
546    if (OBO->hasNoUnsignedWrap())
547      Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
548  } else if (const PossiblyExactOperator *PEO =
549               dyn_cast<PossiblyExactOperator>(V)) {
550    if (PEO->isExact())
551      Flags |= 1 << bitc::PEO_EXACT;
552  } else if (const FPMathOperator *FPMO =
553             dyn_cast<const FPMathOperator>(V)) {
554    if (FPMO->hasUnsafeAlgebra())
555      Flags |= 1 << bitc::FMF_UNSAFE_ALGEBRA;
556    if (FPMO->hasNoNaNs())
557      Flags |= 1 << bitc::FMF_NO_NANS;
558    if (FPMO->hasNoInfs())
559      Flags |= 1 << bitc::FMF_NO_INFS;
560    if (FPMO->hasNoSignedZeros())
561      Flags |= 1 << bitc::FMF_NO_SIGNED_ZEROS;
562    if (FPMO->hasAllowReciprocal())
563      Flags |= 1 << bitc::FMF_ALLOW_RECIPROCAL;
564  }
565
566  return Flags;
567}
568
569static void WriteMDNode(const MDNode *N,
570                        const ValueEnumerator &VE,
571                        BitstreamWriter &Stream,
572                        SmallVector<uint64_t, 64> &Record) {
573  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
574    if (N->getOperand(i)) {
575      Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
576      Record.push_back(VE.getValueID(N->getOperand(i)));
577    } else {
578      Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
579      Record.push_back(0);
580    }
581  }
582  unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
583                                           bitc::METADATA_NODE;
584  Stream.EmitRecord(MDCode, Record, 0);
585  Record.clear();
586}
587
588static void WriteModuleMetadata(const Module *M,
589                                const ValueEnumerator &VE,
590                                BitstreamWriter &Stream) {
591  const ValueEnumerator::ValueList &Vals = VE.getMDValues();
592  bool StartedMetadataBlock = false;
593  unsigned MDSAbbrev = 0;
594  SmallVector<uint64_t, 64> Record;
595  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
596
597    if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
598      if (!N->isFunctionLocal() || !N->getFunction()) {
599        if (!StartedMetadataBlock) {
600          Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
601          StartedMetadataBlock = true;
602        }
603        WriteMDNode(N, VE, Stream, Record);
604      }
605    } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
606      if (!StartedMetadataBlock)  {
607        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
608
609        // Abbrev for METADATA_STRING.
610        BitCodeAbbrev *Abbv = new BitCodeAbbrev();
611        Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
612        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
613        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
614        MDSAbbrev = Stream.EmitAbbrev(Abbv);
615        StartedMetadataBlock = true;
616      }
617
618      // Code: [strchar x N]
619      Record.append(MDS->begin(), MDS->end());
620
621      // Emit the finished record.
622      Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
623      Record.clear();
624    }
625  }
626
627  // Write named metadata.
628  for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
629       E = M->named_metadata_end(); I != E; ++I) {
630    const NamedMDNode *NMD = I;
631    if (!StartedMetadataBlock)  {
632      Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
633      StartedMetadataBlock = true;
634    }
635
636    // Write name.
637    StringRef Str = NMD->getName();
638    for (unsigned i = 0, e = Str.size(); i != e; ++i)
639      Record.push_back(Str[i]);
640    Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
641    Record.clear();
642
643    // Write named metadata operands.
644    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
645      Record.push_back(VE.getValueID(NMD->getOperand(i)));
646    Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
647    Record.clear();
648  }
649
650  if (StartedMetadataBlock)
651    Stream.ExitBlock();
652}
653
654static void WriteFunctionLocalMetadata(const Function &F,
655                                       const ValueEnumerator &VE,
656                                       BitstreamWriter &Stream) {
657  bool StartedMetadataBlock = false;
658  SmallVector<uint64_t, 64> Record;
659  const SmallVector<const MDNode *, 8> &Vals = VE.getFunctionLocalMDValues();
660  for (unsigned i = 0, e = Vals.size(); i != e; ++i)
661    if (const MDNode *N = Vals[i])
662      if (N->isFunctionLocal() && N->getFunction() == &F) {
663        if (!StartedMetadataBlock) {
664          Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
665          StartedMetadataBlock = true;
666        }
667        WriteMDNode(N, VE, Stream, Record);
668      }
669
670  if (StartedMetadataBlock)
671    Stream.ExitBlock();
672}
673
674static void WriteMetadataAttachment(const Function &F,
675                                    const ValueEnumerator &VE,
676                                    BitstreamWriter &Stream) {
677  Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
678
679  SmallVector<uint64_t, 64> Record;
680
681  // Write metadata attachments
682  // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
683  SmallVector<std::pair<unsigned, MDNode*>, 4> MDs;
684
685  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
686    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
687         I != E; ++I) {
688      MDs.clear();
689      I->getAllMetadataOtherThanDebugLoc(MDs);
690
691      // If no metadata, ignore instruction.
692      if (MDs.empty()) continue;
693
694      Record.push_back(VE.getInstructionID(I));
695
696      for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
697        Record.push_back(MDs[i].first);
698        Record.push_back(VE.getValueID(MDs[i].second));
699      }
700      Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
701      Record.clear();
702    }
703
704  Stream.ExitBlock();
705}
706
707static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
708  SmallVector<uint64_t, 64> Record;
709
710  // Write metadata kinds
711  // METADATA_KIND - [n x [id, name]]
712  SmallVector<StringRef, 4> Names;
713  M->getMDKindNames(Names);
714
715  if (Names.empty()) return;
716
717  Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
718
719  for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
720    Record.push_back(MDKindID);
721    StringRef KName = Names[MDKindID];
722    Record.append(KName.begin(), KName.end());
723
724    Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
725    Record.clear();
726  }
727
728  Stream.ExitBlock();
729}
730
731static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
732  if ((int64_t)V >= 0)
733    Vals.push_back(V << 1);
734  else
735    Vals.push_back((-V << 1) | 1);
736}
737
738static void EmitAPInt(SmallVectorImpl<uint64_t> &Vals,
739                      unsigned &Code, unsigned &AbbrevToUse, const APInt &Val,
740                      bool EmitSizeForWideNumbers = false
741                      ) {
742  if (Val.getBitWidth() <= 64) {
743    uint64_t V = Val.getSExtValue();
744    emitSignedInt64(Vals, V);
745    Code = bitc::CST_CODE_INTEGER;
746    AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
747  } else {
748    // Wide integers, > 64 bits in size.
749    // We have an arbitrary precision integer value to write whose
750    // bit width is > 64. However, in canonical unsigned integer
751    // format it is likely that the high bits are going to be zero.
752    // So, we only write the number of active words.
753    unsigned NWords = Val.getActiveWords();
754
755    if (EmitSizeForWideNumbers)
756      Vals.push_back(NWords);
757
758    const uint64_t *RawWords = Val.getRawData();
759    for (unsigned i = 0; i != NWords; ++i) {
760      emitSignedInt64(Vals, RawWords[i]);
761    }
762    Code = bitc::CST_CODE_WIDE_INTEGER;
763  }
764}
765
766static void WriteConstants(unsigned FirstVal, unsigned LastVal,
767                           const ValueEnumerator &VE,
768                           BitstreamWriter &Stream, bool isGlobal) {
769  if (FirstVal == LastVal) return;
770
771  Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
772
773  unsigned AggregateAbbrev = 0;
774  unsigned String8Abbrev = 0;
775  unsigned CString7Abbrev = 0;
776  unsigned CString6Abbrev = 0;
777  // If this is a constant pool for the module, emit module-specific abbrevs.
778  if (isGlobal) {
779    // Abbrev for CST_CODE_AGGREGATE.
780    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
781    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
782    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
783    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
784    AggregateAbbrev = Stream.EmitAbbrev(Abbv);
785
786    // Abbrev for CST_CODE_STRING.
787    Abbv = new BitCodeAbbrev();
788    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
789    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
790    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
791    String8Abbrev = Stream.EmitAbbrev(Abbv);
792    // Abbrev for CST_CODE_CSTRING.
793    Abbv = new BitCodeAbbrev();
794    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
795    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
796    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
797    CString7Abbrev = Stream.EmitAbbrev(Abbv);
798    // Abbrev for CST_CODE_CSTRING.
799    Abbv = new BitCodeAbbrev();
800    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
801    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
802    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
803    CString6Abbrev = Stream.EmitAbbrev(Abbv);
804  }
805
806  SmallVector<uint64_t, 64> Record;
807
808  const ValueEnumerator::ValueList &Vals = VE.getValues();
809  Type *LastTy = 0;
810  for (unsigned i = FirstVal; i != LastVal; ++i) {
811    const Value *V = Vals[i].first;
812    // If we need to switch types, do so now.
813    if (V->getType() != LastTy) {
814      LastTy = V->getType();
815      Record.push_back(VE.getTypeID(LastTy));
816      Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
817                        CONSTANTS_SETTYPE_ABBREV);
818      Record.clear();
819    }
820
821    if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
822      Record.push_back(unsigned(IA->hasSideEffects()) |
823                       unsigned(IA->isAlignStack()) << 1 |
824                       unsigned(IA->getDialect()&1) << 2);
825
826      // Add the asm string.
827      const std::string &AsmStr = IA->getAsmString();
828      Record.push_back(AsmStr.size());
829      for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
830        Record.push_back(AsmStr[i]);
831
832      // Add the constraint string.
833      const std::string &ConstraintStr = IA->getConstraintString();
834      Record.push_back(ConstraintStr.size());
835      for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
836        Record.push_back(ConstraintStr[i]);
837      Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
838      Record.clear();
839      continue;
840    }
841    const Constant *C = cast<Constant>(V);
842    unsigned Code = -1U;
843    unsigned AbbrevToUse = 0;
844    if (C->isNullValue()) {
845      Code = bitc::CST_CODE_NULL;
846    } else if (isa<UndefValue>(C)) {
847      Code = bitc::CST_CODE_UNDEF;
848    } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
849      EmitAPInt(Record, Code, AbbrevToUse, IV->getValue());
850    } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
851      Code = bitc::CST_CODE_FLOAT;
852      Type *Ty = CFP->getType();
853      if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
854        Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
855      } else if (Ty->isX86_FP80Ty()) {
856        // api needed to prevent premature destruction
857        // bits are not in the same order as a normal i80 APInt, compensate.
858        APInt api = CFP->getValueAPF().bitcastToAPInt();
859        const uint64_t *p = api.getRawData();
860        Record.push_back((p[1] << 48) | (p[0] >> 16));
861        Record.push_back(p[0] & 0xffffLL);
862      } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
863        APInt api = CFP->getValueAPF().bitcastToAPInt();
864        const uint64_t *p = api.getRawData();
865        Record.push_back(p[0]);
866        Record.push_back(p[1]);
867      } else {
868        assert (0 && "Unknown FP type!");
869      }
870    } else if (isa<ConstantDataSequential>(C) &&
871               cast<ConstantDataSequential>(C)->isString()) {
872      const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
873      // Emit constant strings specially.
874      unsigned NumElts = Str->getNumElements();
875      // If this is a null-terminated string, use the denser CSTRING encoding.
876      if (Str->isCString()) {
877        Code = bitc::CST_CODE_CSTRING;
878        --NumElts;  // Don't encode the null, which isn't allowed by char6.
879      } else {
880        Code = bitc::CST_CODE_STRING;
881        AbbrevToUse = String8Abbrev;
882      }
883      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
884      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
885      for (unsigned i = 0; i != NumElts; ++i) {
886        unsigned char V = Str->getElementAsInteger(i);
887        Record.push_back(V);
888        isCStr7 &= (V & 128) == 0;
889        if (isCStrChar6)
890          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
891      }
892
893      if (isCStrChar6)
894        AbbrevToUse = CString6Abbrev;
895      else if (isCStr7)
896        AbbrevToUse = CString7Abbrev;
897    } else if (const ConstantDataSequential *CDS =
898                  dyn_cast<ConstantDataSequential>(C)) {
899      Code = bitc::CST_CODE_DATA;
900      Type *EltTy = CDS->getType()->getElementType();
901      if (isa<IntegerType>(EltTy)) {
902        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
903          Record.push_back(CDS->getElementAsInteger(i));
904      } else if (EltTy->isFloatTy()) {
905        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
906          union { float F; uint32_t I; };
907          F = CDS->getElementAsFloat(i);
908          Record.push_back(I);
909        }
910      } else {
911        assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
912        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
913          union { double F; uint64_t I; };
914          F = CDS->getElementAsDouble(i);
915          Record.push_back(I);
916        }
917      }
918    } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
919               isa<ConstantVector>(C)) {
920      Code = bitc::CST_CODE_AGGREGATE;
921      for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
922        Record.push_back(VE.getValueID(C->getOperand(i)));
923      AbbrevToUse = AggregateAbbrev;
924    } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
925      switch (CE->getOpcode()) {
926      default:
927        if (Instruction::isCast(CE->getOpcode())) {
928          Code = bitc::CST_CODE_CE_CAST;
929          Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
930          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
931          Record.push_back(VE.getValueID(C->getOperand(0)));
932          AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
933        } else {
934          assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
935          Code = bitc::CST_CODE_CE_BINOP;
936          Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
937          Record.push_back(VE.getValueID(C->getOperand(0)));
938          Record.push_back(VE.getValueID(C->getOperand(1)));
939          uint64_t Flags = GetOptimizationFlags(CE);
940          if (Flags != 0)
941            Record.push_back(Flags);
942        }
943        break;
944      case Instruction::GetElementPtr:
945        Code = bitc::CST_CODE_CE_GEP;
946        if (cast<GEPOperator>(C)->isInBounds())
947          Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
948        for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
949          Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
950          Record.push_back(VE.getValueID(C->getOperand(i)));
951        }
952        break;
953      case Instruction::Select:
954        Code = bitc::CST_CODE_CE_SELECT;
955        Record.push_back(VE.getValueID(C->getOperand(0)));
956        Record.push_back(VE.getValueID(C->getOperand(1)));
957        Record.push_back(VE.getValueID(C->getOperand(2)));
958        break;
959      case Instruction::ExtractElement:
960        Code = bitc::CST_CODE_CE_EXTRACTELT;
961        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
962        Record.push_back(VE.getValueID(C->getOperand(0)));
963        Record.push_back(VE.getValueID(C->getOperand(1)));
964        break;
965      case Instruction::InsertElement:
966        Code = bitc::CST_CODE_CE_INSERTELT;
967        Record.push_back(VE.getValueID(C->getOperand(0)));
968        Record.push_back(VE.getValueID(C->getOperand(1)));
969        Record.push_back(VE.getValueID(C->getOperand(2)));
970        break;
971      case Instruction::ShuffleVector:
972        // If the return type and argument types are the same, this is a
973        // standard shufflevector instruction.  If the types are different,
974        // then the shuffle is widening or truncating the input vectors, and
975        // the argument type must also be encoded.
976        if (C->getType() == C->getOperand(0)->getType()) {
977          Code = bitc::CST_CODE_CE_SHUFFLEVEC;
978        } else {
979          Code = bitc::CST_CODE_CE_SHUFVEC_EX;
980          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
981        }
982        Record.push_back(VE.getValueID(C->getOperand(0)));
983        Record.push_back(VE.getValueID(C->getOperand(1)));
984        Record.push_back(VE.getValueID(C->getOperand(2)));
985        break;
986      case Instruction::ICmp:
987      case Instruction::FCmp:
988        Code = bitc::CST_CODE_CE_CMP;
989        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
990        Record.push_back(VE.getValueID(C->getOperand(0)));
991        Record.push_back(VE.getValueID(C->getOperand(1)));
992        Record.push_back(CE->getPredicate());
993        break;
994      }
995    } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
996      Code = bitc::CST_CODE_BLOCKADDRESS;
997      Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
998      Record.push_back(VE.getValueID(BA->getFunction()));
999      Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1000    } else {
1001#ifndef NDEBUG
1002      C->dump();
1003#endif
1004      llvm_unreachable("Unknown constant!");
1005    }
1006    Stream.EmitRecord(Code, Record, AbbrevToUse);
1007    Record.clear();
1008  }
1009
1010  Stream.ExitBlock();
1011}
1012
1013static void WriteModuleConstants(const ValueEnumerator &VE,
1014                                 BitstreamWriter &Stream) {
1015  const ValueEnumerator::ValueList &Vals = VE.getValues();
1016
1017  // Find the first constant to emit, which is the first non-globalvalue value.
1018  // We know globalvalues have been emitted by WriteModuleInfo.
1019  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1020    if (!isa<GlobalValue>(Vals[i].first)) {
1021      WriteConstants(i, Vals.size(), VE, Stream, true);
1022      return;
1023    }
1024  }
1025}
1026
1027/// PushValueAndType - The file has to encode both the value and type id for
1028/// many values, because we need to know what type to create for forward
1029/// references.  However, most operands are not forward references, so this type
1030/// field is not needed.
1031///
1032/// This function adds V's value ID to Vals.  If the value ID is higher than the
1033/// instruction ID, then it is a forward reference, and it also includes the
1034/// type ID.  The value ID that is written is encoded relative to the InstID.
1035static bool PushValueAndType(const Value *V, unsigned InstID,
1036                             SmallVector<unsigned, 64> &Vals,
1037                             ValueEnumerator &VE) {
1038  unsigned ValID = VE.getValueID(V);
1039  // Make encoding relative to the InstID.
1040  Vals.push_back(InstID - ValID);
1041  if (ValID >= InstID) {
1042    Vals.push_back(VE.getTypeID(V->getType()));
1043    return true;
1044  }
1045  return false;
1046}
1047
1048/// pushValue - Like PushValueAndType, but where the type of the value is
1049/// omitted (perhaps it was already encoded in an earlier operand).
1050static void pushValue(const Value *V, unsigned InstID,
1051                      SmallVector<unsigned, 64> &Vals,
1052                      ValueEnumerator &VE) {
1053  unsigned ValID = VE.getValueID(V);
1054  Vals.push_back(InstID - ValID);
1055}
1056
1057static void pushValue64(const Value *V, unsigned InstID,
1058                        SmallVector<uint64_t, 128> &Vals,
1059                        ValueEnumerator &VE) {
1060  uint64_t ValID = VE.getValueID(V);
1061  Vals.push_back(InstID - ValID);
1062}
1063
1064static void pushValueSigned(const Value *V, unsigned InstID,
1065                            SmallVector<uint64_t, 128> &Vals,
1066                            ValueEnumerator &VE) {
1067  unsigned ValID = VE.getValueID(V);
1068  int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1069  emitSignedInt64(Vals, diff);
1070}
1071
1072/// WriteInstruction - Emit an instruction to the specified stream.
1073static void WriteInstruction(const Instruction &I, unsigned InstID,
1074                             ValueEnumerator &VE, BitstreamWriter &Stream,
1075                             SmallVector<unsigned, 64> &Vals) {
1076  unsigned Code = 0;
1077  unsigned AbbrevToUse = 0;
1078  VE.setInstructionID(&I);
1079  switch (I.getOpcode()) {
1080  default:
1081    if (Instruction::isCast(I.getOpcode())) {
1082      Code = bitc::FUNC_CODE_INST_CAST;
1083      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1084        AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1085      Vals.push_back(VE.getTypeID(I.getType()));
1086      Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1087    } else {
1088      assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1089      Code = bitc::FUNC_CODE_INST_BINOP;
1090      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1091        AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1092      pushValue(I.getOperand(1), InstID, Vals, VE);
1093      Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1094      uint64_t Flags = GetOptimizationFlags(&I);
1095      if (Flags != 0) {
1096        if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1097          AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1098        Vals.push_back(Flags);
1099      }
1100    }
1101    break;
1102
1103  case Instruction::GetElementPtr:
1104    Code = bitc::FUNC_CODE_INST_GEP;
1105    if (cast<GEPOperator>(&I)->isInBounds())
1106      Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1107    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1108      PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1109    break;
1110  case Instruction::ExtractValue: {
1111    Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1112    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1113    const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1114    for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1115      Vals.push_back(*i);
1116    break;
1117  }
1118  case Instruction::InsertValue: {
1119    Code = bitc::FUNC_CODE_INST_INSERTVAL;
1120    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1121    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1122    const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1123    for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1124      Vals.push_back(*i);
1125    break;
1126  }
1127  case Instruction::Select:
1128    Code = bitc::FUNC_CODE_INST_VSELECT;
1129    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1130    pushValue(I.getOperand(2), InstID, Vals, VE);
1131    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1132    break;
1133  case Instruction::ExtractElement:
1134    Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1135    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1136    pushValue(I.getOperand(1), InstID, Vals, VE);
1137    break;
1138  case Instruction::InsertElement:
1139    Code = bitc::FUNC_CODE_INST_INSERTELT;
1140    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1141    pushValue(I.getOperand(1), InstID, Vals, VE);
1142    pushValue(I.getOperand(2), InstID, Vals, VE);
1143    break;
1144  case Instruction::ShuffleVector:
1145    Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1146    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1147    pushValue(I.getOperand(1), InstID, Vals, VE);
1148    pushValue(I.getOperand(2), InstID, Vals, VE);
1149    break;
1150  case Instruction::ICmp:
1151  case Instruction::FCmp:
1152    // compare returning Int1Ty or vector of Int1Ty
1153    Code = bitc::FUNC_CODE_INST_CMP2;
1154    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1155    pushValue(I.getOperand(1), InstID, Vals, VE);
1156    Vals.push_back(cast<CmpInst>(I).getPredicate());
1157    break;
1158
1159  case Instruction::Ret:
1160    {
1161      Code = bitc::FUNC_CODE_INST_RET;
1162      unsigned NumOperands = I.getNumOperands();
1163      if (NumOperands == 0)
1164        AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1165      else if (NumOperands == 1) {
1166        if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1167          AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1168      } else {
1169        for (unsigned i = 0, e = NumOperands; i != e; ++i)
1170          PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1171      }
1172    }
1173    break;
1174  case Instruction::Br:
1175    {
1176      Code = bitc::FUNC_CODE_INST_BR;
1177      BranchInst &II = cast<BranchInst>(I);
1178      Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1179      if (II.isConditional()) {
1180        Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1181        pushValue(II.getCondition(), InstID, Vals, VE);
1182      }
1183    }
1184    break;
1185  case Instruction::Switch:
1186    {
1187      // Redefine Vals, since here we need to use 64 bit values
1188      // explicitly to store large APInt numbers.
1189      SmallVector<uint64_t, 128> Vals64;
1190
1191      Code = bitc::FUNC_CODE_INST_SWITCH;
1192      SwitchInst &SI = cast<SwitchInst>(I);
1193
1194      uint32_t SwitchRecordHeader = SI.hash() | (SWITCH_INST_MAGIC << 16);
1195      Vals64.push_back(SwitchRecordHeader);
1196
1197      Vals64.push_back(VE.getTypeID(SI.getCondition()->getType()));
1198      pushValue64(SI.getCondition(), InstID, Vals64, VE);
1199      Vals64.push_back(VE.getValueID(SI.getDefaultDest()));
1200      Vals64.push_back(SI.getNumCases());
1201      for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
1202           i != e; ++i) {
1203        IntegersSubset& CaseRanges = i.getCaseValueEx();
1204        unsigned Code, Abbrev; // will unused.
1205
1206        if (CaseRanges.isSingleNumber()) {
1207          Vals64.push_back(1/*NumItems = 1*/);
1208          Vals64.push_back(true/*IsSingleNumber = true*/);
1209          EmitAPInt(Vals64, Code, Abbrev, CaseRanges.getSingleNumber(0), true);
1210        } else {
1211
1212          Vals64.push_back(CaseRanges.getNumItems());
1213
1214          if (CaseRanges.isSingleNumbersOnly()) {
1215            for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1216                 ri != rn; ++ri) {
1217
1218              Vals64.push_back(true/*IsSingleNumber = true*/);
1219
1220              EmitAPInt(Vals64, Code, Abbrev,
1221                        CaseRanges.getSingleNumber(ri), true);
1222            }
1223          } else
1224            for (unsigned ri = 0, rn = CaseRanges.getNumItems();
1225                 ri != rn; ++ri) {
1226              IntegersSubset::Range r = CaseRanges.getItem(ri);
1227              bool IsSingleNumber = CaseRanges.isSingleNumber(ri);
1228
1229              Vals64.push_back(IsSingleNumber);
1230
1231              EmitAPInt(Vals64, Code, Abbrev, r.getLow(), true);
1232              if (!IsSingleNumber)
1233                EmitAPInt(Vals64, Code, Abbrev, r.getHigh(), true);
1234            }
1235        }
1236        Vals64.push_back(VE.getValueID(i.getCaseSuccessor()));
1237      }
1238
1239      Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1240
1241      // Also do expected action - clear external Vals collection:
1242      Vals.clear();
1243      return;
1244    }
1245    break;
1246  case Instruction::IndirectBr:
1247    Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1248    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1249    // Encode the address operand as relative, but not the basic blocks.
1250    pushValue(I.getOperand(0), InstID, Vals, VE);
1251    for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1252      Vals.push_back(VE.getValueID(I.getOperand(i)));
1253    break;
1254
1255  case Instruction::Invoke: {
1256    const InvokeInst *II = cast<InvokeInst>(&I);
1257    const Value *Callee(II->getCalledValue());
1258    PointerType *PTy = cast<PointerType>(Callee->getType());
1259    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1260    Code = bitc::FUNC_CODE_INST_INVOKE;
1261
1262    Vals.push_back(VE.getAttributeID(II->getAttributes()));
1263    Vals.push_back(II->getCallingConv());
1264    Vals.push_back(VE.getValueID(II->getNormalDest()));
1265    Vals.push_back(VE.getValueID(II->getUnwindDest()));
1266    PushValueAndType(Callee, InstID, Vals, VE);
1267
1268    // Emit value #'s for the fixed parameters.
1269    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1270      pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1271
1272    // Emit type/value pairs for varargs params.
1273    if (FTy->isVarArg()) {
1274      for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1275           i != e; ++i)
1276        PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1277    }
1278    break;
1279  }
1280  case Instruction::Resume:
1281    Code = bitc::FUNC_CODE_INST_RESUME;
1282    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1283    break;
1284  case Instruction::Unreachable:
1285    Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1286    AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1287    break;
1288
1289  case Instruction::PHI: {
1290    const PHINode &PN = cast<PHINode>(I);
1291    Code = bitc::FUNC_CODE_INST_PHI;
1292    // With the newer instruction encoding, forward references could give
1293    // negative valued IDs.  This is most common for PHIs, so we use
1294    // signed VBRs.
1295    SmallVector<uint64_t, 128> Vals64;
1296    Vals64.push_back(VE.getTypeID(PN.getType()));
1297    for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1298      pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1299      Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1300    }
1301    // Emit a Vals64 vector and exit.
1302    Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1303    Vals64.clear();
1304    return;
1305  }
1306
1307  case Instruction::LandingPad: {
1308    const LandingPadInst &LP = cast<LandingPadInst>(I);
1309    Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1310    Vals.push_back(VE.getTypeID(LP.getType()));
1311    PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1312    Vals.push_back(LP.isCleanup());
1313    Vals.push_back(LP.getNumClauses());
1314    for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1315      if (LP.isCatch(I))
1316        Vals.push_back(LandingPadInst::Catch);
1317      else
1318        Vals.push_back(LandingPadInst::Filter);
1319      PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1320    }
1321    break;
1322  }
1323
1324  case Instruction::Alloca:
1325    Code = bitc::FUNC_CODE_INST_ALLOCA;
1326    Vals.push_back(VE.getTypeID(I.getType()));
1327    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1328    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1329    Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1330    break;
1331
1332  case Instruction::Load:
1333    if (cast<LoadInst>(I).isAtomic()) {
1334      Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1335      PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1336    } else {
1337      Code = bitc::FUNC_CODE_INST_LOAD;
1338      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1339        AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1340    }
1341    Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1342    Vals.push_back(cast<LoadInst>(I).isVolatile());
1343    if (cast<LoadInst>(I).isAtomic()) {
1344      Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1345      Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1346    }
1347    break;
1348  case Instruction::Store:
1349    if (cast<StoreInst>(I).isAtomic())
1350      Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1351    else
1352      Code = bitc::FUNC_CODE_INST_STORE;
1353    PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1354    pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1355    Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1356    Vals.push_back(cast<StoreInst>(I).isVolatile());
1357    if (cast<StoreInst>(I).isAtomic()) {
1358      Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1359      Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1360    }
1361    break;
1362  case Instruction::AtomicCmpXchg:
1363    Code = bitc::FUNC_CODE_INST_CMPXCHG;
1364    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1365    pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1366    pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1367    Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1368    Vals.push_back(GetEncodedOrdering(
1369                     cast<AtomicCmpXchgInst>(I).getOrdering()));
1370    Vals.push_back(GetEncodedSynchScope(
1371                     cast<AtomicCmpXchgInst>(I).getSynchScope()));
1372    break;
1373  case Instruction::AtomicRMW:
1374    Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1375    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1376    pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1377    Vals.push_back(GetEncodedRMWOperation(
1378                     cast<AtomicRMWInst>(I).getOperation()));
1379    Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1380    Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1381    Vals.push_back(GetEncodedSynchScope(
1382                     cast<AtomicRMWInst>(I).getSynchScope()));
1383    break;
1384  case Instruction::Fence:
1385    Code = bitc::FUNC_CODE_INST_FENCE;
1386    Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1387    Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1388    break;
1389  case Instruction::Call: {
1390    const CallInst &CI = cast<CallInst>(I);
1391    PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1392    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1393
1394    Code = bitc::FUNC_CODE_INST_CALL;
1395
1396    Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1397    Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()));
1398    PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1399
1400    // Emit value #'s for the fixed parameters.
1401    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1402      // Check for labels (can happen with asm labels).
1403      if (FTy->getParamType(i)->isLabelTy())
1404        Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1405      else
1406        pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1407    }
1408
1409    // Emit type/value pairs for varargs params.
1410    if (FTy->isVarArg()) {
1411      for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1412           i != e; ++i)
1413        PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1414    }
1415    break;
1416  }
1417  case Instruction::VAArg:
1418    Code = bitc::FUNC_CODE_INST_VAARG;
1419    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1420    pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1421    Vals.push_back(VE.getTypeID(I.getType())); // restype.
1422    break;
1423  }
1424
1425  Stream.EmitRecord(Code, Vals, AbbrevToUse);
1426  Vals.clear();
1427}
1428
1429// Emit names for globals/functions etc.
1430static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1431                                  const ValueEnumerator &VE,
1432                                  BitstreamWriter &Stream) {
1433  if (VST.empty()) return;
1434  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1435
1436  // FIXME: Set up the abbrev, we know how many values there are!
1437  // FIXME: We know if the type names can use 7-bit ascii.
1438  SmallVector<unsigned, 64> NameVals;
1439
1440  for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1441       SI != SE; ++SI) {
1442
1443    const ValueName &Name = *SI;
1444
1445    // Figure out the encoding to use for the name.
1446    bool is7Bit = true;
1447    bool isChar6 = true;
1448    for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1449         C != E; ++C) {
1450      if (isChar6)
1451        isChar6 = BitCodeAbbrevOp::isChar6(*C);
1452      if ((unsigned char)*C & 128) {
1453        is7Bit = false;
1454        break;  // don't bother scanning the rest.
1455      }
1456    }
1457
1458    unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1459
1460    // VST_ENTRY:   [valueid, namechar x N]
1461    // VST_BBENTRY: [bbid, namechar x N]
1462    unsigned Code;
1463    if (isa<BasicBlock>(SI->getValue())) {
1464      Code = bitc::VST_CODE_BBENTRY;
1465      if (isChar6)
1466        AbbrevToUse = VST_BBENTRY_6_ABBREV;
1467    } else {
1468      Code = bitc::VST_CODE_ENTRY;
1469      if (isChar6)
1470        AbbrevToUse = VST_ENTRY_6_ABBREV;
1471      else if (is7Bit)
1472        AbbrevToUse = VST_ENTRY_7_ABBREV;
1473    }
1474
1475    NameVals.push_back(VE.getValueID(SI->getValue()));
1476    for (const char *P = Name.getKeyData(),
1477         *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1478      NameVals.push_back((unsigned char)*P);
1479
1480    // Emit the finished record.
1481    Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1482    NameVals.clear();
1483  }
1484  Stream.ExitBlock();
1485}
1486
1487/// WriteFunction - Emit a function body to the module stream.
1488static void WriteFunction(const Function &F, ValueEnumerator &VE,
1489                          BitstreamWriter &Stream) {
1490  Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1491  VE.incorporateFunction(F);
1492
1493  SmallVector<unsigned, 64> Vals;
1494
1495  // Emit the number of basic blocks, so the reader can create them ahead of
1496  // time.
1497  Vals.push_back(VE.getBasicBlocks().size());
1498  Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1499  Vals.clear();
1500
1501  // If there are function-local constants, emit them now.
1502  unsigned CstStart, CstEnd;
1503  VE.getFunctionConstantRange(CstStart, CstEnd);
1504  WriteConstants(CstStart, CstEnd, VE, Stream, false);
1505
1506  // If there is function-local metadata, emit it now.
1507  WriteFunctionLocalMetadata(F, VE, Stream);
1508
1509  // Keep a running idea of what the instruction ID is.
1510  unsigned InstID = CstEnd;
1511
1512  bool NeedsMetadataAttachment = false;
1513
1514  DebugLoc LastDL;
1515
1516  // Finally, emit all the instructions, in order.
1517  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1518    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1519         I != E; ++I) {
1520      WriteInstruction(*I, InstID, VE, Stream, Vals);
1521
1522      if (!I->getType()->isVoidTy())
1523        ++InstID;
1524
1525      // If the instruction has metadata, write a metadata attachment later.
1526      NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1527
1528      // If the instruction has a debug location, emit it.
1529      DebugLoc DL = I->getDebugLoc();
1530      if (DL.isUnknown()) {
1531        // nothing todo.
1532      } else if (DL == LastDL) {
1533        // Just repeat the same debug loc as last time.
1534        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1535      } else {
1536        MDNode *Scope, *IA;
1537        DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1538
1539        Vals.push_back(DL.getLine());
1540        Vals.push_back(DL.getCol());
1541        Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1542        Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1543        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1544        Vals.clear();
1545
1546        LastDL = DL;
1547      }
1548    }
1549
1550  // Emit names for all the instructions etc.
1551  WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1552
1553  if (NeedsMetadataAttachment)
1554    WriteMetadataAttachment(F, VE, Stream);
1555  VE.purgeFunction();
1556  Stream.ExitBlock();
1557}
1558
1559// Emit blockinfo, which defines the standard abbreviations etc.
1560static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1561  // We only want to emit block info records for blocks that have multiple
1562  // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1563  // Other blocks can define their abbrevs inline.
1564  Stream.EnterBlockInfoBlock(2);
1565
1566  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1567    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1568    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1569    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1570    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1571    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1572    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1573                                   Abbv) != VST_ENTRY_8_ABBREV)
1574      llvm_unreachable("Unexpected abbrev ordering!");
1575  }
1576
1577  { // 7-bit fixed width VST_ENTRY strings.
1578    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1579    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1580    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1581    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1582    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1583    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1584                                   Abbv) != VST_ENTRY_7_ABBREV)
1585      llvm_unreachable("Unexpected abbrev ordering!");
1586  }
1587  { // 6-bit char6 VST_ENTRY strings.
1588    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1589    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1590    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1591    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1592    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1593    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1594                                   Abbv) != VST_ENTRY_6_ABBREV)
1595      llvm_unreachable("Unexpected abbrev ordering!");
1596  }
1597  { // 6-bit char6 VST_BBENTRY strings.
1598    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1599    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1600    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1601    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1602    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1603    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1604                                   Abbv) != VST_BBENTRY_6_ABBREV)
1605      llvm_unreachable("Unexpected abbrev ordering!");
1606  }
1607
1608
1609
1610  { // SETTYPE abbrev for CONSTANTS_BLOCK.
1611    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1612    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1613    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1614                              Log2_32_Ceil(VE.getTypes().size()+1)));
1615    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1616                                   Abbv) != CONSTANTS_SETTYPE_ABBREV)
1617      llvm_unreachable("Unexpected abbrev ordering!");
1618  }
1619
1620  { // INTEGER abbrev for CONSTANTS_BLOCK.
1621    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1622    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1623    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1624    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1625                                   Abbv) != CONSTANTS_INTEGER_ABBREV)
1626      llvm_unreachable("Unexpected abbrev ordering!");
1627  }
1628
1629  { // CE_CAST abbrev for CONSTANTS_BLOCK.
1630    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1631    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1632    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1633    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1634                              Log2_32_Ceil(VE.getTypes().size()+1)));
1635    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1636
1637    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1638                                   Abbv) != CONSTANTS_CE_CAST_Abbrev)
1639      llvm_unreachable("Unexpected abbrev ordering!");
1640  }
1641  { // NULL abbrev for CONSTANTS_BLOCK.
1642    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1643    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1644    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1645                                   Abbv) != CONSTANTS_NULL_Abbrev)
1646      llvm_unreachable("Unexpected abbrev ordering!");
1647  }
1648
1649  // FIXME: This should only use space for first class types!
1650
1651  { // INST_LOAD abbrev for FUNCTION_BLOCK.
1652    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1653    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1654    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1655    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1656    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1657    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1658                                   Abbv) != FUNCTION_INST_LOAD_ABBREV)
1659      llvm_unreachable("Unexpected abbrev ordering!");
1660  }
1661  { // INST_BINOP abbrev for FUNCTION_BLOCK.
1662    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1663    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1664    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1665    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1666    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1667    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1668                                   Abbv) != FUNCTION_INST_BINOP_ABBREV)
1669      llvm_unreachable("Unexpected abbrev ordering!");
1670  }
1671  { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1672    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1673    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1674    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1675    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1676    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1677    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1678    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1679                                   Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1680      llvm_unreachable("Unexpected abbrev ordering!");
1681  }
1682  { // INST_CAST abbrev for FUNCTION_BLOCK.
1683    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1684    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1685    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1686    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1687                              Log2_32_Ceil(VE.getTypes().size()+1)));
1688    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1689    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1690                                   Abbv) != FUNCTION_INST_CAST_ABBREV)
1691      llvm_unreachable("Unexpected abbrev ordering!");
1692  }
1693
1694  { // INST_RET abbrev for FUNCTION_BLOCK.
1695    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1696    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1697    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1698                                   Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1699      llvm_unreachable("Unexpected abbrev ordering!");
1700  }
1701  { // INST_RET abbrev for FUNCTION_BLOCK.
1702    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1703    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1704    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1705    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1706                                   Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1707      llvm_unreachable("Unexpected abbrev ordering!");
1708  }
1709  { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1710    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1711    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1712    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1713                                   Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1714      llvm_unreachable("Unexpected abbrev ordering!");
1715  }
1716
1717  Stream.ExitBlock();
1718}
1719
1720// Sort the Users based on the order in which the reader parses the bitcode
1721// file.
1722static bool bitcodereader_order(const User *lhs, const User *rhs) {
1723  // TODO: Implement.
1724  return true;
1725}
1726
1727static void WriteUseList(const Value *V, const ValueEnumerator &VE,
1728                         BitstreamWriter &Stream) {
1729
1730  // One or zero uses can't get out of order.
1731  if (V->use_empty() || V->hasNUses(1))
1732    return;
1733
1734  // Make a copy of the in-memory use-list for sorting.
1735  unsigned UseListSize = std::distance(V->use_begin(), V->use_end());
1736  SmallVector<const User*, 8> UseList;
1737  UseList.reserve(UseListSize);
1738  for (Value::const_use_iterator I = V->use_begin(), E = V->use_end();
1739       I != E; ++I) {
1740    const User *U = *I;
1741    UseList.push_back(U);
1742  }
1743
1744  // Sort the copy based on the order read by the BitcodeReader.
1745  std::sort(UseList.begin(), UseList.end(), bitcodereader_order);
1746
1747  // TODO: Generate a diff between the BitcodeWriter in-memory use-list and the
1748  // sorted list (i.e., the expected BitcodeReader in-memory use-list).
1749
1750  // TODO: Emit the USELIST_CODE_ENTRYs.
1751}
1752
1753static void WriteFunctionUseList(const Function *F, ValueEnumerator &VE,
1754                                 BitstreamWriter &Stream) {
1755  VE.incorporateFunction(*F);
1756
1757  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
1758       AI != AE; ++AI)
1759    WriteUseList(AI, VE, Stream);
1760  for (Function::const_iterator BB = F->begin(), FE = F->end(); BB != FE;
1761       ++BB) {
1762    WriteUseList(BB, VE, Stream);
1763    for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); II != IE;
1764         ++II) {
1765      WriteUseList(II, VE, Stream);
1766      for (User::const_op_iterator OI = II->op_begin(), E = II->op_end();
1767           OI != E; ++OI) {
1768        if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
1769            isa<InlineAsm>(*OI))
1770          WriteUseList(*OI, VE, Stream);
1771      }
1772    }
1773  }
1774  VE.purgeFunction();
1775}
1776
1777// Emit use-lists.
1778static void WriteModuleUseLists(const Module *M, ValueEnumerator &VE,
1779                                BitstreamWriter &Stream) {
1780  Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1781
1782  // XXX: this modifies the module, but in a way that should never change the
1783  // behavior of any pass or codegen in LLVM. The problem is that GVs may
1784  // contain entries in the use_list that do not exist in the Module and are
1785  // not stored in the .bc file.
1786  for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
1787       I != E; ++I)
1788    I->removeDeadConstantUsers();
1789
1790  // Write the global variables.
1791  for (Module::const_global_iterator GI = M->global_begin(),
1792         GE = M->global_end(); GI != GE; ++GI) {
1793    WriteUseList(GI, VE, Stream);
1794
1795    // Write the global variable initializers.
1796    if (GI->hasInitializer())
1797      WriteUseList(GI->getInitializer(), VE, Stream);
1798  }
1799
1800  // Write the functions.
1801  for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI) {
1802    WriteUseList(FI, VE, Stream);
1803    if (!FI->isDeclaration())
1804      WriteFunctionUseList(FI, VE, Stream);
1805  }
1806
1807  // Write the aliases.
1808  for (Module::const_alias_iterator AI = M->alias_begin(), AE = M->alias_end();
1809       AI != AE; ++AI) {
1810    WriteUseList(AI, VE, Stream);
1811    WriteUseList(AI->getAliasee(), VE, Stream);
1812  }
1813
1814  Stream.ExitBlock();
1815}
1816
1817/// WriteModule - Emit the specified module to the bitstream.
1818static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1819  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1820
1821  SmallVector<unsigned, 1> Vals;
1822  unsigned CurVersion = 1;
1823  Vals.push_back(CurVersion);
1824  Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1825
1826  // Analyze the module, enumerating globals, functions, etc.
1827  ValueEnumerator VE(M);
1828
1829  // Emit blockinfo, which defines the standard abbreviations etc.
1830  WriteBlockInfo(VE, Stream);
1831
1832  // Emit information about parameter attributes.
1833  WriteAttributeTable(VE, Stream);
1834
1835  // Emit information describing all of the types in the module.
1836  WriteTypeTable(VE, Stream);
1837
1838  // Emit top-level description of module, including target triple, inline asm,
1839  // descriptors for global variables, and function prototype info.
1840  WriteModuleInfo(M, VE, Stream);
1841
1842  // Emit constants.
1843  WriteModuleConstants(VE, Stream);
1844
1845  // Emit metadata.
1846  WriteModuleMetadata(M, VE, Stream);
1847
1848  // Emit metadata.
1849  WriteModuleMetadataStore(M, Stream);
1850
1851  // Emit names for globals/functions etc.
1852  WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1853
1854  // Emit use-lists.
1855  if (EnablePreserveUseListOrdering)
1856    WriteModuleUseLists(M, VE, Stream);
1857
1858  // Emit function bodies.
1859  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1860    if (!F->isDeclaration())
1861      WriteFunction(*F, VE, Stream);
1862
1863  Stream.ExitBlock();
1864}
1865
1866/// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1867/// header and trailer to make it compatible with the system archiver.  To do
1868/// this we emit the following header, and then emit a trailer that pads the
1869/// file out to be a multiple of 16 bytes.
1870///
1871/// struct bc_header {
1872///   uint32_t Magic;         // 0x0B17C0DE
1873///   uint32_t Version;       // Version, currently always 0.
1874///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1875///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1876///   uint32_t CPUType;       // CPU specifier.
1877///   ... potentially more later ...
1878/// };
1879enum {
1880  DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1881  DarwinBCHeaderSize = 5*4
1882};
1883
1884static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1885                               uint32_t &Position) {
1886  Buffer[Position + 0] = (unsigned char) (Value >>  0);
1887  Buffer[Position + 1] = (unsigned char) (Value >>  8);
1888  Buffer[Position + 2] = (unsigned char) (Value >> 16);
1889  Buffer[Position + 3] = (unsigned char) (Value >> 24);
1890  Position += 4;
1891}
1892
1893static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1894                                         const Triple &TT) {
1895  unsigned CPUType = ~0U;
1896
1897  // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1898  // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1899  // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1900  // specific constants here because they are implicitly part of the Darwin ABI.
1901  enum {
1902    DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1903    DARWIN_CPU_TYPE_X86        = 7,
1904    DARWIN_CPU_TYPE_ARM        = 12,
1905    DARWIN_CPU_TYPE_POWERPC    = 18
1906  };
1907
1908  Triple::ArchType Arch = TT.getArch();
1909  if (Arch == Triple::x86_64)
1910    CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1911  else if (Arch == Triple::x86)
1912    CPUType = DARWIN_CPU_TYPE_X86;
1913  else if (Arch == Triple::ppc)
1914    CPUType = DARWIN_CPU_TYPE_POWERPC;
1915  else if (Arch == Triple::ppc64)
1916    CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1917  else if (Arch == Triple::arm || Arch == Triple::thumb)
1918    CPUType = DARWIN_CPU_TYPE_ARM;
1919
1920  // Traditional Bitcode starts after header.
1921  assert(Buffer.size() >= DarwinBCHeaderSize &&
1922         "Expected header size to be reserved");
1923  unsigned BCOffset = DarwinBCHeaderSize;
1924  unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1925
1926  // Write the magic and version.
1927  unsigned Position = 0;
1928  WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1929  WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1930  WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1931  WriteInt32ToBuffer(BCSize     , Buffer, Position);
1932  WriteInt32ToBuffer(CPUType    , Buffer, Position);
1933
1934  // If the file is not a multiple of 16 bytes, insert dummy padding.
1935  while (Buffer.size() & 15)
1936    Buffer.push_back(0);
1937}
1938
1939/// WriteBitcodeToFile - Write the specified module to the specified output
1940/// stream.
1941void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1942  SmallVector<char, 1024> Buffer;
1943  Buffer.reserve(256*1024);
1944
1945  // If this is darwin or another generic macho target, reserve space for the
1946  // header.
1947  Triple TT(M->getTargetTriple());
1948  if (TT.isOSDarwin())
1949    Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
1950
1951  // Emit the module into the buffer.
1952  {
1953    BitstreamWriter Stream(Buffer);
1954
1955    // Emit the file header.
1956    Stream.Emit((unsigned)'B', 8);
1957    Stream.Emit((unsigned)'C', 8);
1958    Stream.Emit(0x0, 4);
1959    Stream.Emit(0xC, 4);
1960    Stream.Emit(0xE, 4);
1961    Stream.Emit(0xD, 4);
1962
1963    // Emit the module.
1964    WriteModule(M, Stream);
1965  }
1966
1967  if (TT.isOSDarwin())
1968    EmitDarwinBCHeaderAndTrailer(Buffer, TT);
1969
1970  // Write the generated bitstream to "Out".
1971  Out.write((char*)&Buffer.front(), Buffer.size());
1972}
1973