BitcodeWriter.cpp revision 190390b8d31af0a549827478911b322af4bc111a 
1//===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Bitcode writer implementation.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Bitcode/ReaderWriter.h"
15#include "llvm/Bitcode/BitstreamWriter.h"
16#include "llvm/Bitcode/LLVMBitCodes.h"
17#include "ValueEnumerator.h"
18#include "llvm/Constants.h"
19#include "llvm/DerivedTypes.h"
20#include "llvm/InlineAsm.h"
21#include "llvm/Instructions.h"
22#include "llvm/Metadata.h"
23#include "llvm/Module.h"
24#include "llvm/Operator.h"
25#include "llvm/TypeSymbolTable.h"
26#include "llvm/ValueSymbolTable.h"
27#include "llvm/Support/ErrorHandling.h"
28#include "llvm/Support/MathExtras.h"
29#include "llvm/Support/raw_ostream.h"
30#include "llvm/System/Program.h"
31using namespace llvm;
32
33/// These are manifest constants used by the bitcode writer. They do not need to
34/// be kept in sync with the reader, but need to be consistent within this file.
35enum {
36  CurVersion = 0,
37
38  // VALUE_SYMTAB_BLOCK abbrev id's.
39  VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
40  VST_ENTRY_7_ABBREV,
41  VST_ENTRY_6_ABBREV,
42  VST_BBENTRY_6_ABBREV,
43
44  // CONSTANTS_BLOCK abbrev id's.
45  CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
46  CONSTANTS_INTEGER_ABBREV,
47  CONSTANTS_CE_CAST_Abbrev,
48  CONSTANTS_NULL_Abbrev,
49
50  // FUNCTION_BLOCK abbrev id's.
51  FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
52  FUNCTION_INST_BINOP_ABBREV,
53  FUNCTION_INST_BINOP_FLAGS_ABBREV,
54  FUNCTION_INST_CAST_ABBREV,
55  FUNCTION_INST_RET_VOID_ABBREV,
56  FUNCTION_INST_RET_VAL_ABBREV,
57  FUNCTION_INST_UNREACHABLE_ABBREV
58};
59
60
61static unsigned GetEncodedCastOpcode(unsigned Opcode) {
62  switch (Opcode) {
63  default: llvm_unreachable("Unknown cast instruction!");
64  case Instruction::Trunc   : return bitc::CAST_TRUNC;
65  case Instruction::ZExt    : return bitc::CAST_ZEXT;
66  case Instruction::SExt    : return bitc::CAST_SEXT;
67  case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
68  case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
69  case Instruction::UIToFP  : return bitc::CAST_UITOFP;
70  case Instruction::SIToFP  : return bitc::CAST_SITOFP;
71  case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
72  case Instruction::FPExt   : return bitc::CAST_FPEXT;
73  case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
74  case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
75  case Instruction::BitCast : return bitc::CAST_BITCAST;
76  }
77}
78
79static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
80  switch (Opcode) {
81  default: llvm_unreachable("Unknown binary instruction!");
82  case Instruction::Add:
83  case Instruction::FAdd: return bitc::BINOP_ADD;
84  case Instruction::Sub:
85  case Instruction::FSub: return bitc::BINOP_SUB;
86  case Instruction::Mul:
87  case Instruction::FMul: return bitc::BINOP_MUL;
88  case Instruction::UDiv: return bitc::BINOP_UDIV;
89  case Instruction::FDiv:
90  case Instruction::SDiv: return bitc::BINOP_SDIV;
91  case Instruction::URem: return bitc::BINOP_UREM;
92  case Instruction::FRem:
93  case Instruction::SRem: return bitc::BINOP_SREM;
94  case Instruction::Shl:  return bitc::BINOP_SHL;
95  case Instruction::LShr: return bitc::BINOP_LSHR;
96  case Instruction::AShr: return bitc::BINOP_ASHR;
97  case Instruction::And:  return bitc::BINOP_AND;
98  case Instruction::Or:   return bitc::BINOP_OR;
99  case Instruction::Xor:  return bitc::BINOP_XOR;
100  }
101}
102
103
104
105static void WriteStringRecord(unsigned Code, const std::string &Str,
106                              unsigned AbbrevToUse, BitstreamWriter &Stream) {
107  SmallVector<unsigned, 64> Vals;
108
109  // Code: [strchar x N]
110  for (unsigned i = 0, e = Str.size(); i != e; ++i)
111    Vals.push_back(Str[i]);
112
113  // Emit the finished record.
114  Stream.EmitRecord(Code, Vals, AbbrevToUse);
115}
116
117// Emit information about parameter attributes.
118static void WriteAttributeTable(const ValueEnumerator &VE,
119                                BitstreamWriter &Stream) {
120  const std::vector<AttrListPtr> &Attrs = VE.getAttributes();
121  if (Attrs.empty()) return;
122
123  Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
124
125  SmallVector<uint64_t, 64> Record;
126  for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
127    const AttrListPtr &A = Attrs[i];
128    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
129      const AttributeWithIndex &PAWI = A.getSlot(i);
130      Record.push_back(PAWI.Index);
131
132      // FIXME: remove in LLVM 3.0
133      // Store the alignment in the bitcode as a 16-bit raw value instead of a
134      // 5-bit log2 encoded value. Shift the bits above the alignment up by
135      // 11 bits.
136      uint64_t FauxAttr = PAWI.Attrs & 0xffff;
137      if (PAWI.Attrs & Attribute::Alignment)
138        FauxAttr |= (1ull<<16)<<(((PAWI.Attrs & Attribute::Alignment)-1) >> 16);
139      FauxAttr |= (PAWI.Attrs & (0x3FFull << 21)) << 11;
140
141      Record.push_back(FauxAttr);
142    }
143
144    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
145    Record.clear();
146  }
147
148  Stream.ExitBlock();
149}
150
151/// WriteTypeTable - Write out the type table for a module.
152static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
153  const ValueEnumerator::TypeList &TypeList = VE.getTypes();
154
155  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
156  SmallVector<uint64_t, 64> TypeVals;
157
158  // Abbrev for TYPE_CODE_POINTER.
159  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
160  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
161  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
162                            Log2_32_Ceil(VE.getTypes().size()+1)));
163  Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
164  unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
165
166  // Abbrev for TYPE_CODE_FUNCTION.
167  Abbv = new BitCodeAbbrev();
168  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
169  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
170  Abbv->Add(BitCodeAbbrevOp(0));  // FIXME: DEAD value, remove in LLVM 3.0
171  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
172  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
173                            Log2_32_Ceil(VE.getTypes().size()+1)));
174  unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
175
176  // Abbrev for TYPE_CODE_STRUCT.
177  Abbv = new BitCodeAbbrev();
178  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
179  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
180  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
181  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
182                            Log2_32_Ceil(VE.getTypes().size()+1)));
183  unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
184
185  // Abbrev for TYPE_CODE_ARRAY.
186  Abbv = new BitCodeAbbrev();
187  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
188  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
189  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
190                            Log2_32_Ceil(VE.getTypes().size()+1)));
191  unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
192
193  // Emit an entry count so the reader can reserve space.
194  TypeVals.push_back(TypeList.size());
195  Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
196  TypeVals.clear();
197
198  // Loop over all of the types, emitting each in turn.
199  for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
200    const Type *T = TypeList[i].first;
201    int AbbrevToUse = 0;
202    unsigned Code = 0;
203
204    switch (T->getTypeID()) {
205    default: llvm_unreachable("Unknown type!");
206    case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
207    case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
208    case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
209    case Type::X86_FP80TyID: Code = bitc::TYPE_CODE_X86_FP80; break;
210    case Type::FP128TyID: Code = bitc::TYPE_CODE_FP128; break;
211    case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
212    case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
213    case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
214    case Type::MetadataTyID: Code = bitc::TYPE_CODE_METADATA; break;
215    case Type::IntegerTyID:
216      // INTEGER: [width]
217      Code = bitc::TYPE_CODE_INTEGER;
218      TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
219      break;
220    case Type::PointerTyID: {
221      const PointerType *PTy = cast<PointerType>(T);
222      // POINTER: [pointee type, address space]
223      Code = bitc::TYPE_CODE_POINTER;
224      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
225      unsigned AddressSpace = PTy->getAddressSpace();
226      TypeVals.push_back(AddressSpace);
227      if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
228      break;
229    }
230    case Type::FunctionTyID: {
231      const FunctionType *FT = cast<FunctionType>(T);
232      // FUNCTION: [isvararg, attrid, retty, paramty x N]
233      Code = bitc::TYPE_CODE_FUNCTION;
234      TypeVals.push_back(FT->isVarArg());
235      TypeVals.push_back(0);  // FIXME: DEAD: remove in llvm 3.0
236      TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
237      for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
238        TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
239      AbbrevToUse = FunctionAbbrev;
240      break;
241    }
242    case Type::StructTyID: {
243      const StructType *ST = cast<StructType>(T);
244      // STRUCT: [ispacked, eltty x N]
245      Code = bitc::TYPE_CODE_STRUCT;
246      TypeVals.push_back(ST->isPacked());
247      // Output all of the element types.
248      for (StructType::element_iterator I = ST->element_begin(),
249           E = ST->element_end(); I != E; ++I)
250        TypeVals.push_back(VE.getTypeID(*I));
251      AbbrevToUse = StructAbbrev;
252      break;
253    }
254    case Type::ArrayTyID: {
255      const ArrayType *AT = cast<ArrayType>(T);
256      // ARRAY: [numelts, eltty]
257      Code = bitc::TYPE_CODE_ARRAY;
258      TypeVals.push_back(AT->getNumElements());
259      TypeVals.push_back(VE.getTypeID(AT->getElementType()));
260      AbbrevToUse = ArrayAbbrev;
261      break;
262    }
263    case Type::VectorTyID: {
264      const VectorType *VT = cast<VectorType>(T);
265      // VECTOR [numelts, eltty]
266      Code = bitc::TYPE_CODE_VECTOR;
267      TypeVals.push_back(VT->getNumElements());
268      TypeVals.push_back(VE.getTypeID(VT->getElementType()));
269      break;
270    }
271    }
272
273    // Emit the finished record.
274    Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
275    TypeVals.clear();
276  }
277
278  Stream.ExitBlock();
279}
280
281static unsigned getEncodedLinkage(const GlobalValue *GV) {
282  switch (GV->getLinkage()) {
283  default: llvm_unreachable("Invalid linkage!");
284  case GlobalValue::GhostLinkage:  // Map ghost linkage onto external.
285  case GlobalValue::ExternalLinkage:            return 0;
286  case GlobalValue::WeakAnyLinkage:             return 1;
287  case GlobalValue::AppendingLinkage:           return 2;
288  case GlobalValue::InternalLinkage:            return 3;
289  case GlobalValue::LinkOnceAnyLinkage:         return 4;
290  case GlobalValue::DLLImportLinkage:           return 5;
291  case GlobalValue::DLLExportLinkage:           return 6;
292  case GlobalValue::ExternalWeakLinkage:        return 7;
293  case GlobalValue::CommonLinkage:              return 8;
294  case GlobalValue::PrivateLinkage:             return 9;
295  case GlobalValue::WeakODRLinkage:             return 10;
296  case GlobalValue::LinkOnceODRLinkage:         return 11;
297  case GlobalValue::AvailableExternallyLinkage: return 12;
298  case GlobalValue::LinkerPrivateLinkage:       return 13;
299  }
300}
301
302static unsigned getEncodedVisibility(const GlobalValue *GV) {
303  switch (GV->getVisibility()) {
304  default: llvm_unreachable("Invalid visibility!");
305  case GlobalValue::DefaultVisibility:   return 0;
306  case GlobalValue::HiddenVisibility:    return 1;
307  case GlobalValue::ProtectedVisibility: return 2;
308  }
309}
310
311// Emit top-level description of module, including target triple, inline asm,
312// descriptors for global variables, and function prototype info.
313static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
314                            BitstreamWriter &Stream) {
315  // Emit the list of dependent libraries for the Module.
316  for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
317    WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
318
319  // Emit various pieces of data attached to a module.
320  if (!M->getTargetTriple().empty())
321    WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
322                      0/*TODO*/, Stream);
323  if (!M->getDataLayout().empty())
324    WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
325                      0/*TODO*/, Stream);
326  if (!M->getModuleInlineAsm().empty())
327    WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
328                      0/*TODO*/, Stream);
329
330  // Emit information about sections and GC, computing how many there are. Also
331  // compute the maximum alignment value.
332  std::map<std::string, unsigned> SectionMap;
333  std::map<std::string, unsigned> GCMap;
334  unsigned MaxAlignment = 0;
335  unsigned MaxGlobalType = 0;
336  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
337       GV != E; ++GV) {
338    MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
339    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
340
341    if (!GV->hasSection()) continue;
342    // Give section names unique ID's.
343    unsigned &Entry = SectionMap[GV->getSection()];
344    if (Entry != 0) continue;
345    WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
346                      0/*TODO*/, Stream);
347    Entry = SectionMap.size();
348  }
349  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
350    MaxAlignment = std::max(MaxAlignment, F->getAlignment());
351    if (F->hasSection()) {
352      // Give section names unique ID's.
353      unsigned &Entry = SectionMap[F->getSection()];
354      if (!Entry) {
355        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
356                          0/*TODO*/, Stream);
357        Entry = SectionMap.size();
358      }
359    }
360    if (F->hasGC()) {
361      // Same for GC names.
362      unsigned &Entry = GCMap[F->getGC()];
363      if (!Entry) {
364        WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
365                          0/*TODO*/, Stream);
366        Entry = GCMap.size();
367      }
368    }
369  }
370
371  // Emit abbrev for globals, now that we know # sections and max alignment.
372  unsigned SimpleGVarAbbrev = 0;
373  if (!M->global_empty()) {
374    // Add an abbrev for common globals with no visibility or thread localness.
375    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
376    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
377    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
378                              Log2_32_Ceil(MaxGlobalType+1)));
379    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
380    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
381    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
382    if (MaxAlignment == 0)                                      // Alignment.
383      Abbv->Add(BitCodeAbbrevOp(0));
384    else {
385      unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
386      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
387                               Log2_32_Ceil(MaxEncAlignment+1)));
388    }
389    if (SectionMap.empty())                                    // Section.
390      Abbv->Add(BitCodeAbbrevOp(0));
391    else
392      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
393                               Log2_32_Ceil(SectionMap.size()+1)));
394    // Don't bother emitting vis + thread local.
395    SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
396  }
397
398  // Emit the global variable information.
399  SmallVector<unsigned, 64> Vals;
400  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
401       GV != E; ++GV) {
402    unsigned AbbrevToUse = 0;
403
404    // GLOBALVAR: [type, isconst, initid,
405    //             linkage, alignment, section, visibility, threadlocal]
406    Vals.push_back(VE.getTypeID(GV->getType()));
407    Vals.push_back(GV->isConstant());
408    Vals.push_back(GV->isDeclaration() ? 0 :
409                   (VE.getValueID(GV->getInitializer()) + 1));
410    Vals.push_back(getEncodedLinkage(GV));
411    Vals.push_back(Log2_32(GV->getAlignment())+1);
412    Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
413    if (GV->isThreadLocal() ||
414        GV->getVisibility() != GlobalValue::DefaultVisibility) {
415      Vals.push_back(getEncodedVisibility(GV));
416      Vals.push_back(GV->isThreadLocal());
417    } else {
418      AbbrevToUse = SimpleGVarAbbrev;
419    }
420
421    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
422    Vals.clear();
423  }
424
425  // Emit the function proto information.
426  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
427    // FUNCTION:  [type, callingconv, isproto, paramattr,
428    //             linkage, alignment, section, visibility, gc]
429    Vals.push_back(VE.getTypeID(F->getType()));
430    Vals.push_back(F->getCallingConv());
431    Vals.push_back(F->isDeclaration());
432    Vals.push_back(getEncodedLinkage(F));
433    Vals.push_back(VE.getAttributeID(F->getAttributes()));
434    Vals.push_back(Log2_32(F->getAlignment())+1);
435    Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
436    Vals.push_back(getEncodedVisibility(F));
437    Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
438
439    unsigned AbbrevToUse = 0;
440    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
441    Vals.clear();
442  }
443
444
445  // Emit the alias information.
446  for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
447       AI != E; ++AI) {
448    Vals.push_back(VE.getTypeID(AI->getType()));
449    Vals.push_back(VE.getValueID(AI->getAliasee()));
450    Vals.push_back(getEncodedLinkage(AI));
451    Vals.push_back(getEncodedVisibility(AI));
452    unsigned AbbrevToUse = 0;
453    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
454    Vals.clear();
455  }
456}
457
458static uint64_t GetOptimizationFlags(const Value *V) {
459  uint64_t Flags = 0;
460
461  if (const OverflowingBinaryOperator *OBO =
462        dyn_cast<OverflowingBinaryOperator>(V)) {
463    if (OBO->hasNoSignedWrap())
464      Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
465    if (OBO->hasNoUnsignedWrap())
466      Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
467  } else if (const SDivOperator *Div = dyn_cast<SDivOperator>(V)) {
468    if (Div->isExact())
469      Flags |= 1 << bitc::SDIV_EXACT;
470  }
471
472  return Flags;
473}
474
475static void WriteMDNode(const MDNode *N,
476                        const ValueEnumerator &VE,
477                        BitstreamWriter &Stream,
478                        SmallVector<uint64_t, 64> &Record) {
479  for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
480    if (N->getElement(i)) {
481      Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
482      Record.push_back(VE.getValueID(N->getElement(i)));
483    } else {
484      Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
485      Record.push_back(0);
486    }
487  }
488  Stream.EmitRecord(bitc::METADATA_NODE, Record, 0);
489  Record.clear();
490}
491
492static void WriteModuleMetadata(const ValueEnumerator &VE,
493                                BitstreamWriter &Stream) {
494  const ValueEnumerator::ValueList &Vals = VE.getMDValues();
495  bool StartedMetadataBlock = false;
496  unsigned MDSAbbrev = 0;
497  SmallVector<uint64_t, 64> Record;
498  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
499
500    if (const MDNode *N = dyn_cast<MDNode>(Vals[i].first)) {
501      if (!StartedMetadataBlock) {
502        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
503        StartedMetadataBlock = true;
504      }
505      WriteMDNode(N, VE, Stream, Record);
506    } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
507      if (!StartedMetadataBlock)  {
508        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
509
510        // Abbrev for METADATA_STRING.
511        BitCodeAbbrev *Abbv = new BitCodeAbbrev();
512        Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
513        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
514        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
515        MDSAbbrev = Stream.EmitAbbrev(Abbv);
516        StartedMetadataBlock = true;
517      }
518
519      // Code: [strchar x N]
520      const char *StrBegin = MDS->begin();
521      for (unsigned i = 0, e = MDS->length(); i != e; ++i)
522        Record.push_back(StrBegin[i]);
523
524      // Emit the finished record.
525      Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
526      Record.clear();
527    } else if (const NamedMDNode *NMD = dyn_cast<NamedMDNode>(Vals[i].first)) {
528      if (!StartedMetadataBlock)  {
529        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
530        StartedMetadataBlock = true;
531      }
532
533      // Write name.
534      std::string Str = NMD->getNameStr();
535      const char *StrBegin = Str.c_str();
536      for (unsigned i = 0, e = Str.length(); i != e; ++i)
537        Record.push_back(StrBegin[i]);
538      Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
539      Record.clear();
540
541      // Write named metadata elements.
542      for (unsigned i = 0, e = NMD->getNumElements(); i != e; ++i) {
543        if (NMD->getElement(i))
544          Record.push_back(VE.getValueID(NMD->getElement(i)));
545        else
546          Record.push_back(0);
547      }
548      Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
549      Record.clear();
550    }
551  }
552
553  if (StartedMetadataBlock)
554    Stream.ExitBlock();
555}
556
557static void WriteConstants(unsigned FirstVal, unsigned LastVal,
558                           const ValueEnumerator &VE,
559                           BitstreamWriter &Stream, bool isGlobal) {
560  if (FirstVal == LastVal) return;
561
562  Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
563
564  unsigned AggregateAbbrev = 0;
565  unsigned String8Abbrev = 0;
566  unsigned CString7Abbrev = 0;
567  unsigned CString6Abbrev = 0;
568  // If this is a constant pool for the module, emit module-specific abbrevs.
569  if (isGlobal) {
570    // Abbrev for CST_CODE_AGGREGATE.
571    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
572    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
573    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
574    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
575    AggregateAbbrev = Stream.EmitAbbrev(Abbv);
576
577    // Abbrev for CST_CODE_STRING.
578    Abbv = new BitCodeAbbrev();
579    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
580    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
581    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
582    String8Abbrev = Stream.EmitAbbrev(Abbv);
583    // Abbrev for CST_CODE_CSTRING.
584    Abbv = new BitCodeAbbrev();
585    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
586    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
587    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
588    CString7Abbrev = Stream.EmitAbbrev(Abbv);
589    // Abbrev for CST_CODE_CSTRING.
590    Abbv = new BitCodeAbbrev();
591    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
592    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
593    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
594    CString6Abbrev = Stream.EmitAbbrev(Abbv);
595  }
596
597  SmallVector<uint64_t, 64> Record;
598
599  const ValueEnumerator::ValueList &Vals = VE.getValues();
600  const Type *LastTy = 0;
601  for (unsigned i = FirstVal; i != LastVal; ++i) {
602    const Value *V = Vals[i].first;
603    // If we need to switch types, do so now.
604    if (V->getType() != LastTy) {
605      LastTy = V->getType();
606      Record.push_back(VE.getTypeID(LastTy));
607      Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
608                        CONSTANTS_SETTYPE_ABBREV);
609      Record.clear();
610    }
611
612    if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
613      Record.push_back(unsigned(IA->hasSideEffects()));
614
615      // Add the asm string.
616      const std::string &AsmStr = IA->getAsmString();
617      Record.push_back(AsmStr.size());
618      for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
619        Record.push_back(AsmStr[i]);
620
621      // Add the constraint string.
622      const std::string &ConstraintStr = IA->getConstraintString();
623      Record.push_back(ConstraintStr.size());
624      for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
625        Record.push_back(ConstraintStr[i]);
626      Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
627      Record.clear();
628      continue;
629    }
630    const Constant *C = cast<Constant>(V);
631    unsigned Code = -1U;
632    unsigned AbbrevToUse = 0;
633    if (C->isNullValue()) {
634      Code = bitc::CST_CODE_NULL;
635    } else if (isa<UndefValue>(C)) {
636      Code = bitc::CST_CODE_UNDEF;
637    } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
638      if (IV->getBitWidth() <= 64) {
639        int64_t V = IV->getSExtValue();
640        if (V >= 0)
641          Record.push_back(V << 1);
642        else
643          Record.push_back((-V << 1) | 1);
644        Code = bitc::CST_CODE_INTEGER;
645        AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
646      } else {                             // Wide integers, > 64 bits in size.
647        // We have an arbitrary precision integer value to write whose
648        // bit width is > 64. However, in canonical unsigned integer
649        // format it is likely that the high bits are going to be zero.
650        // So, we only write the number of active words.
651        unsigned NWords = IV->getValue().getActiveWords();
652        const uint64_t *RawWords = IV->getValue().getRawData();
653        for (unsigned i = 0; i != NWords; ++i) {
654          int64_t V = RawWords[i];
655          if (V >= 0)
656            Record.push_back(V << 1);
657          else
658            Record.push_back((-V << 1) | 1);
659        }
660        Code = bitc::CST_CODE_WIDE_INTEGER;
661      }
662    } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
663      Code = bitc::CST_CODE_FLOAT;
664      const Type *Ty = CFP->getType();
665      if (Ty == Type::getFloatTy(Ty->getContext()) ||
666          Ty == Type::getDoubleTy(Ty->getContext())) {
667        Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
668      } else if (Ty == Type::getX86_FP80Ty(Ty->getContext())) {
669        // api needed to prevent premature destruction
670        // bits are not in the same order as a normal i80 APInt, compensate.
671        APInt api = CFP->getValueAPF().bitcastToAPInt();
672        const uint64_t *p = api.getRawData();
673        Record.push_back((p[1] << 48) | (p[0] >> 16));
674        Record.push_back(p[0] & 0xffffLL);
675      } else if (Ty == Type::getFP128Ty(Ty->getContext()) ||
676                 Ty == Type::getPPC_FP128Ty(Ty->getContext())) {
677        APInt api = CFP->getValueAPF().bitcastToAPInt();
678        const uint64_t *p = api.getRawData();
679        Record.push_back(p[0]);
680        Record.push_back(p[1]);
681      } else {
682        assert (0 && "Unknown FP type!");
683      }
684    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
685      // Emit constant strings specially.
686      unsigned NumOps = C->getNumOperands();
687      // If this is a null-terminated string, use the denser CSTRING encoding.
688      if (C->getOperand(NumOps-1)->isNullValue()) {
689        Code = bitc::CST_CODE_CSTRING;
690        --NumOps;  // Don't encode the null, which isn't allowed by char6.
691      } else {
692        Code = bitc::CST_CODE_STRING;
693        AbbrevToUse = String8Abbrev;
694      }
695      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
696      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
697      for (unsigned i = 0; i != NumOps; ++i) {
698        unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
699        Record.push_back(V);
700        isCStr7 &= (V & 128) == 0;
701        if (isCStrChar6)
702          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
703      }
704
705      if (isCStrChar6)
706        AbbrevToUse = CString6Abbrev;
707      else if (isCStr7)
708        AbbrevToUse = CString7Abbrev;
709    } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
710               isa<ConstantVector>(V)) {
711      Code = bitc::CST_CODE_AGGREGATE;
712      for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
713        Record.push_back(VE.getValueID(C->getOperand(i)));
714      AbbrevToUse = AggregateAbbrev;
715    } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
716      switch (CE->getOpcode()) {
717      default:
718        if (Instruction::isCast(CE->getOpcode())) {
719          Code = bitc::CST_CODE_CE_CAST;
720          Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
721          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
722          Record.push_back(VE.getValueID(C->getOperand(0)));
723          AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
724        } else {
725          assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
726          Code = bitc::CST_CODE_CE_BINOP;
727          Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
728          Record.push_back(VE.getValueID(C->getOperand(0)));
729          Record.push_back(VE.getValueID(C->getOperand(1)));
730          uint64_t Flags = GetOptimizationFlags(CE);
731          if (Flags != 0)
732            Record.push_back(Flags);
733        }
734        break;
735      case Instruction::GetElementPtr:
736        Code = bitc::CST_CODE_CE_GEP;
737        if (cast<GEPOperator>(C)->isInBounds())
738          Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
739        for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
740          Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
741          Record.push_back(VE.getValueID(C->getOperand(i)));
742        }
743        break;
744      case Instruction::Select:
745        Code = bitc::CST_CODE_CE_SELECT;
746        Record.push_back(VE.getValueID(C->getOperand(0)));
747        Record.push_back(VE.getValueID(C->getOperand(1)));
748        Record.push_back(VE.getValueID(C->getOperand(2)));
749        break;
750      case Instruction::ExtractElement:
751        Code = bitc::CST_CODE_CE_EXTRACTELT;
752        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
753        Record.push_back(VE.getValueID(C->getOperand(0)));
754        Record.push_back(VE.getValueID(C->getOperand(1)));
755        break;
756      case Instruction::InsertElement:
757        Code = bitc::CST_CODE_CE_INSERTELT;
758        Record.push_back(VE.getValueID(C->getOperand(0)));
759        Record.push_back(VE.getValueID(C->getOperand(1)));
760        Record.push_back(VE.getValueID(C->getOperand(2)));
761        break;
762      case Instruction::ShuffleVector:
763        // If the return type and argument types are the same, this is a
764        // standard shufflevector instruction.  If the types are different,
765        // then the shuffle is widening or truncating the input vectors, and
766        // the argument type must also be encoded.
767        if (C->getType() == C->getOperand(0)->getType()) {
768          Code = bitc::CST_CODE_CE_SHUFFLEVEC;
769        } else {
770          Code = bitc::CST_CODE_CE_SHUFVEC_EX;
771          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
772        }
773        Record.push_back(VE.getValueID(C->getOperand(0)));
774        Record.push_back(VE.getValueID(C->getOperand(1)));
775        Record.push_back(VE.getValueID(C->getOperand(2)));
776        break;
777      case Instruction::ICmp:
778      case Instruction::FCmp:
779        Code = bitc::CST_CODE_CE_CMP;
780        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
781        Record.push_back(VE.getValueID(C->getOperand(0)));
782        Record.push_back(VE.getValueID(C->getOperand(1)));
783        Record.push_back(CE->getPredicate());
784        break;
785      }
786    } else {
787      llvm_unreachable("Unknown constant!");
788    }
789    Stream.EmitRecord(Code, Record, AbbrevToUse);
790    Record.clear();
791  }
792
793  Stream.ExitBlock();
794}
795
796static void WriteModuleConstants(const ValueEnumerator &VE,
797                                 BitstreamWriter &Stream) {
798  const ValueEnumerator::ValueList &Vals = VE.getValues();
799
800  // Find the first constant to emit, which is the first non-globalvalue value.
801  // We know globalvalues have been emitted by WriteModuleInfo.
802  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
803    if (!isa<GlobalValue>(Vals[i].first)) {
804      WriteConstants(i, Vals.size(), VE, Stream, true);
805      return;
806    }
807  }
808}
809
810/// PushValueAndType - The file has to encode both the value and type id for
811/// many values, because we need to know what type to create for forward
812/// references.  However, most operands are not forward references, so this type
813/// field is not needed.
814///
815/// This function adds V's value ID to Vals.  If the value ID is higher than the
816/// instruction ID, then it is a forward reference, and it also includes the
817/// type ID.
818static bool PushValueAndType(const Value *V, unsigned InstID,
819                             SmallVector<unsigned, 64> &Vals,
820                             ValueEnumerator &VE) {
821  unsigned ValID = VE.getValueID(V);
822  Vals.push_back(ValID);
823  if (ValID >= InstID) {
824    Vals.push_back(VE.getTypeID(V->getType()));
825    return true;
826  }
827  return false;
828}
829
830/// WriteInstruction - Emit an instruction to the specified stream.
831static void WriteInstruction(const Instruction &I, unsigned InstID,
832                             ValueEnumerator &VE, BitstreamWriter &Stream,
833                             SmallVector<unsigned, 64> &Vals) {
834  unsigned Code = 0;
835  unsigned AbbrevToUse = 0;
836  switch (I.getOpcode()) {
837  default:
838    if (Instruction::isCast(I.getOpcode())) {
839      Code = bitc::FUNC_CODE_INST_CAST;
840      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
841        AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
842      Vals.push_back(VE.getTypeID(I.getType()));
843      Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
844    } else {
845      assert(isa<BinaryOperator>(I) && "Unknown instruction!");
846      Code = bitc::FUNC_CODE_INST_BINOP;
847      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
848        AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
849      Vals.push_back(VE.getValueID(I.getOperand(1)));
850      Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
851      uint64_t Flags = GetOptimizationFlags(&I);
852      if (Flags != 0) {
853        if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
854          AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
855        Vals.push_back(Flags);
856      }
857    }
858    break;
859
860  case Instruction::GetElementPtr:
861    Code = bitc::FUNC_CODE_INST_GEP;
862    if (cast<GEPOperator>(&I)->isInBounds())
863      Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
864    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
865      PushValueAndType(I.getOperand(i), InstID, Vals, VE);
866    break;
867  case Instruction::ExtractValue: {
868    Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
869    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
870    const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
871    for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
872      Vals.push_back(*i);
873    break;
874  }
875  case Instruction::InsertValue: {
876    Code = bitc::FUNC_CODE_INST_INSERTVAL;
877    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
878    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
879    const InsertValueInst *IVI = cast<InsertValueInst>(&I);
880    for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
881      Vals.push_back(*i);
882    break;
883  }
884  case Instruction::Select:
885    Code = bitc::FUNC_CODE_INST_VSELECT;
886    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
887    Vals.push_back(VE.getValueID(I.getOperand(2)));
888    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
889    break;
890  case Instruction::ExtractElement:
891    Code = bitc::FUNC_CODE_INST_EXTRACTELT;
892    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
893    Vals.push_back(VE.getValueID(I.getOperand(1)));
894    break;
895  case Instruction::InsertElement:
896    Code = bitc::FUNC_CODE_INST_INSERTELT;
897    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
898    Vals.push_back(VE.getValueID(I.getOperand(1)));
899    Vals.push_back(VE.getValueID(I.getOperand(2)));
900    break;
901  case Instruction::ShuffleVector:
902    Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
903    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
904    Vals.push_back(VE.getValueID(I.getOperand(1)));
905    Vals.push_back(VE.getValueID(I.getOperand(2)));
906    break;
907  case Instruction::ICmp:
908  case Instruction::FCmp:
909    // compare returning Int1Ty or vector of Int1Ty
910    Code = bitc::FUNC_CODE_INST_CMP2;
911    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
912    Vals.push_back(VE.getValueID(I.getOperand(1)));
913    Vals.push_back(cast<CmpInst>(I).getPredicate());
914    break;
915
916  case Instruction::Ret:
917    {
918      Code = bitc::FUNC_CODE_INST_RET;
919      unsigned NumOperands = I.getNumOperands();
920      if (NumOperands == 0)
921        AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
922      else if (NumOperands == 1) {
923        if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
924          AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
925      } else {
926        for (unsigned i = 0, e = NumOperands; i != e; ++i)
927          PushValueAndType(I.getOperand(i), InstID, Vals, VE);
928      }
929    }
930    break;
931  case Instruction::Br:
932    {
933      Code = bitc::FUNC_CODE_INST_BR;
934      BranchInst &II(cast<BranchInst>(I));
935      Vals.push_back(VE.getValueID(II.getSuccessor(0)));
936      if (II.isConditional()) {
937        Vals.push_back(VE.getValueID(II.getSuccessor(1)));
938        Vals.push_back(VE.getValueID(II.getCondition()));
939      }
940    }
941    break;
942  case Instruction::Switch:
943    Code = bitc::FUNC_CODE_INST_SWITCH;
944    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
945    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
946      Vals.push_back(VE.getValueID(I.getOperand(i)));
947    break;
948  case Instruction::Invoke: {
949    const InvokeInst *II = cast<InvokeInst>(&I);
950    const Value *Callee(II->getCalledValue());
951    const PointerType *PTy = cast<PointerType>(Callee->getType());
952    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
953    Code = bitc::FUNC_CODE_INST_INVOKE;
954
955    Vals.push_back(VE.getAttributeID(II->getAttributes()));
956    Vals.push_back(II->getCallingConv());
957    Vals.push_back(VE.getValueID(II->getNormalDest()));
958    Vals.push_back(VE.getValueID(II->getUnwindDest()));
959    PushValueAndType(Callee, InstID, Vals, VE);
960
961    // Emit value #'s for the fixed parameters.
962    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
963      Vals.push_back(VE.getValueID(I.getOperand(i)));  // fixed param.
964
965    // Emit type/value pairs for varargs params.
966    if (FTy->isVarArg()) {
967      for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
968           i != e; ++i)
969        PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
970    }
971    break;
972  }
973  case Instruction::Unwind:
974    Code = bitc::FUNC_CODE_INST_UNWIND;
975    break;
976  case Instruction::Unreachable:
977    Code = bitc::FUNC_CODE_INST_UNREACHABLE;
978    AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
979    break;
980
981  case Instruction::PHI:
982    Code = bitc::FUNC_CODE_INST_PHI;
983    Vals.push_back(VE.getTypeID(I.getType()));
984    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
985      Vals.push_back(VE.getValueID(I.getOperand(i)));
986    break;
987
988  case Instruction::Malloc:
989    Code = bitc::FUNC_CODE_INST_MALLOC;
990    Vals.push_back(VE.getTypeID(I.getType()));
991    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
992    Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
993    break;
994
995  case Instruction::Free:
996    Code = bitc::FUNC_CODE_INST_FREE;
997    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
998    break;
999
1000  case Instruction::Alloca:
1001    Code = bitc::FUNC_CODE_INST_ALLOCA;
1002    Vals.push_back(VE.getTypeID(I.getType()));
1003    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1004    Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
1005    break;
1006
1007  case Instruction::Load:
1008    Code = bitc::FUNC_CODE_INST_LOAD;
1009    if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1010      AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1011
1012    Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1013    Vals.push_back(cast<LoadInst>(I).isVolatile());
1014    break;
1015  case Instruction::Store:
1016    Code = bitc::FUNC_CODE_INST_STORE2;
1017    PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1018    Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
1019    Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1020    Vals.push_back(cast<StoreInst>(I).isVolatile());
1021    break;
1022  case Instruction::Call: {
1023    const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
1024    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1025
1026    Code = bitc::FUNC_CODE_INST_CALL;
1027
1028    const CallInst *CI = cast<CallInst>(&I);
1029    Vals.push_back(VE.getAttributeID(CI->getAttributes()));
1030    Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
1031    PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
1032
1033    // Emit value #'s for the fixed parameters.
1034    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1035      Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
1036
1037    // Emit type/value pairs for varargs params.
1038    if (FTy->isVarArg()) {
1039      unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1040      for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1041           i != e; ++i)
1042        PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1043    }
1044    break;
1045  }
1046  case Instruction::VAArg:
1047    Code = bitc::FUNC_CODE_INST_VAARG;
1048    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1049    Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1050    Vals.push_back(VE.getTypeID(I.getType())); // restype.
1051    break;
1052  }
1053
1054  Stream.EmitRecord(Code, Vals, AbbrevToUse);
1055  Vals.clear();
1056}
1057
1058// Emit names for globals/functions etc.
1059static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1060                                  const ValueEnumerator &VE,
1061                                  BitstreamWriter &Stream) {
1062  if (VST.empty()) return;
1063  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1064
1065  // FIXME: Set up the abbrev, we know how many values there are!
1066  // FIXME: We know if the type names can use 7-bit ascii.
1067  SmallVector<unsigned, 64> NameVals;
1068
1069  for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1070       SI != SE; ++SI) {
1071
1072    const ValueName &Name = *SI;
1073
1074    // Figure out the encoding to use for the name.
1075    bool is7Bit = true;
1076    bool isChar6 = true;
1077    for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1078         C != E; ++C) {
1079      if (isChar6)
1080        isChar6 = BitCodeAbbrevOp::isChar6(*C);
1081      if ((unsigned char)*C & 128) {
1082        is7Bit = false;
1083        break;  // don't bother scanning the rest.
1084      }
1085    }
1086
1087    unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1088
1089    // VST_ENTRY:   [valueid, namechar x N]
1090    // VST_BBENTRY: [bbid, namechar x N]
1091    unsigned Code;
1092    if (isa<BasicBlock>(SI->getValue())) {
1093      Code = bitc::VST_CODE_BBENTRY;
1094      if (isChar6)
1095        AbbrevToUse = VST_BBENTRY_6_ABBREV;
1096    } else {
1097      Code = bitc::VST_CODE_ENTRY;
1098      if (isChar6)
1099        AbbrevToUse = VST_ENTRY_6_ABBREV;
1100      else if (is7Bit)
1101        AbbrevToUse = VST_ENTRY_7_ABBREV;
1102    }
1103
1104    NameVals.push_back(VE.getValueID(SI->getValue()));
1105    for (const char *P = Name.getKeyData(),
1106         *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1107      NameVals.push_back((unsigned char)*P);
1108
1109    // Emit the finished record.
1110    Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1111    NameVals.clear();
1112  }
1113  Stream.ExitBlock();
1114}
1115
1116/// WriteFunction - Emit a function body to the module stream.
1117static void WriteFunction(const Function &F, ValueEnumerator &VE,
1118                          BitstreamWriter &Stream) {
1119  Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1120  VE.incorporateFunction(F);
1121
1122  SmallVector<unsigned, 64> Vals;
1123
1124  // Emit the number of basic blocks, so the reader can create them ahead of
1125  // time.
1126  Vals.push_back(VE.getBasicBlocks().size());
1127  Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1128  Vals.clear();
1129
1130  // If there are function-local constants, emit them now.
1131  unsigned CstStart, CstEnd;
1132  VE.getFunctionConstantRange(CstStart, CstEnd);
1133  WriteConstants(CstStart, CstEnd, VE, Stream, false);
1134
1135  // Keep a running idea of what the instruction ID is.
1136  unsigned InstID = CstEnd;
1137
1138  // Finally, emit all the instructions, in order.
1139  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1140    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1141         I != E; ++I) {
1142      WriteInstruction(*I, InstID, VE, Stream, Vals);
1143      if (I->getType() != Type::getVoidTy(F.getContext()))
1144        ++InstID;
1145    }
1146
1147  // Emit names for all the instructions etc.
1148  WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1149
1150  VE.purgeFunction();
1151  Stream.ExitBlock();
1152}
1153
1154/// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1155static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1156                                 const ValueEnumerator &VE,
1157                                 BitstreamWriter &Stream) {
1158  if (TST.empty()) return;
1159
1160  Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1161
1162  // 7-bit fixed width VST_CODE_ENTRY strings.
1163  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1164  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1165  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1166                            Log2_32_Ceil(VE.getTypes().size()+1)));
1167  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1168  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1169  unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1170
1171  SmallVector<unsigned, 64> NameVals;
1172
1173  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1174       TI != TE; ++TI) {
1175    // TST_ENTRY: [typeid, namechar x N]
1176    NameVals.push_back(VE.getTypeID(TI->second));
1177
1178    const std::string &Str = TI->first;
1179    bool is7Bit = true;
1180    for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1181      NameVals.push_back((unsigned char)Str[i]);
1182      if (Str[i] & 128)
1183        is7Bit = false;
1184    }
1185
1186    // Emit the finished record.
1187    Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1188    NameVals.clear();
1189  }
1190
1191  Stream.ExitBlock();
1192}
1193
1194// Emit blockinfo, which defines the standard abbreviations etc.
1195static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1196  // We only want to emit block info records for blocks that have multiple
1197  // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1198  // blocks can defined their abbrevs inline.
1199  Stream.EnterBlockInfoBlock(2);
1200
1201  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1202    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1203    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1204    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1205    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1206    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1207    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1208                                   Abbv) != VST_ENTRY_8_ABBREV)
1209      llvm_unreachable("Unexpected abbrev ordering!");
1210  }
1211
1212  { // 7-bit fixed width VST_ENTRY strings.
1213    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1214    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1215    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1216    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1217    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1218    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1219                                   Abbv) != VST_ENTRY_7_ABBREV)
1220      llvm_unreachable("Unexpected abbrev ordering!");
1221  }
1222  { // 6-bit char6 VST_ENTRY strings.
1223    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1224    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1225    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1226    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1227    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1228    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1229                                   Abbv) != VST_ENTRY_6_ABBREV)
1230      llvm_unreachable("Unexpected abbrev ordering!");
1231  }
1232  { // 6-bit char6 VST_BBENTRY strings.
1233    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1234    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1235    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1236    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1237    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1238    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1239                                   Abbv) != VST_BBENTRY_6_ABBREV)
1240      llvm_unreachable("Unexpected abbrev ordering!");
1241  }
1242
1243
1244
1245  { // SETTYPE abbrev for CONSTANTS_BLOCK.
1246    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1247    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1248    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1249                              Log2_32_Ceil(VE.getTypes().size()+1)));
1250    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1251                                   Abbv) != CONSTANTS_SETTYPE_ABBREV)
1252      llvm_unreachable("Unexpected abbrev ordering!");
1253  }
1254
1255  { // INTEGER abbrev for CONSTANTS_BLOCK.
1256    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1257    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1258    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1259    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1260                                   Abbv) != CONSTANTS_INTEGER_ABBREV)
1261      llvm_unreachable("Unexpected abbrev ordering!");
1262  }
1263
1264  { // CE_CAST abbrev for CONSTANTS_BLOCK.
1265    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1266    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1267    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1268    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1269                              Log2_32_Ceil(VE.getTypes().size()+1)));
1270    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1271
1272    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1273                                   Abbv) != CONSTANTS_CE_CAST_Abbrev)
1274      llvm_unreachable("Unexpected abbrev ordering!");
1275  }
1276  { // NULL abbrev for CONSTANTS_BLOCK.
1277    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1278    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1279    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1280                                   Abbv) != CONSTANTS_NULL_Abbrev)
1281      llvm_unreachable("Unexpected abbrev ordering!");
1282  }
1283
1284  // FIXME: This should only use space for first class types!
1285
1286  { // INST_LOAD abbrev for FUNCTION_BLOCK.
1287    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1288    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1289    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1290    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1291    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1292    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1293                                   Abbv) != FUNCTION_INST_LOAD_ABBREV)
1294      llvm_unreachable("Unexpected abbrev ordering!");
1295  }
1296  { // INST_BINOP abbrev for FUNCTION_BLOCK.
1297    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1298    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1299    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1300    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1301    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1302    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1303                                   Abbv) != FUNCTION_INST_BINOP_ABBREV)
1304      llvm_unreachable("Unexpected abbrev ordering!");
1305  }
1306  { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1307    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1308    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1309    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1310    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1311    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1312    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1313    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1314                                   Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1315      llvm_unreachable("Unexpected abbrev ordering!");
1316  }
1317  { // INST_CAST abbrev for FUNCTION_BLOCK.
1318    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1319    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1320    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1321    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1322                              Log2_32_Ceil(VE.getTypes().size()+1)));
1323    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1324    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1325                                   Abbv) != FUNCTION_INST_CAST_ABBREV)
1326      llvm_unreachable("Unexpected abbrev ordering!");
1327  }
1328
1329  { // INST_RET abbrev for FUNCTION_BLOCK.
1330    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1331    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1332    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1333                                   Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1334      llvm_unreachable("Unexpected abbrev ordering!");
1335  }
1336  { // INST_RET abbrev for FUNCTION_BLOCK.
1337    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1338    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1339    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1340    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1341                                   Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1342      llvm_unreachable("Unexpected abbrev ordering!");
1343  }
1344  { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1345    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1346    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1347    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1348                                   Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1349      llvm_unreachable("Unexpected abbrev ordering!");
1350  }
1351
1352  Stream.ExitBlock();
1353}
1354
1355
1356/// WriteModule - Emit the specified module to the bitstream.
1357static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1358  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1359
1360  // Emit the version number if it is non-zero.
1361  if (CurVersion) {
1362    SmallVector<unsigned, 1> Vals;
1363    Vals.push_back(CurVersion);
1364    Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1365  }
1366
1367  // Analyze the module, enumerating globals, functions, etc.
1368  ValueEnumerator VE(M);
1369
1370  // Emit blockinfo, which defines the standard abbreviations etc.
1371  WriteBlockInfo(VE, Stream);
1372
1373  // Emit information about parameter attributes.
1374  WriteAttributeTable(VE, Stream);
1375
1376  // Emit information describing all of the types in the module.
1377  WriteTypeTable(VE, Stream);
1378
1379  // Emit top-level description of module, including target triple, inline asm,
1380  // descriptors for global variables, and function prototype info.
1381  WriteModuleInfo(M, VE, Stream);
1382
1383  // Emit constants.
1384  WriteModuleConstants(VE, Stream);
1385
1386  // Emit metadata.
1387  WriteModuleMetadata(VE, Stream);
1388
1389  // Emit function bodies.
1390  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1391    if (!I->isDeclaration())
1392      WriteFunction(*I, VE, Stream);
1393
1394  // Emit the type symbol table information.
1395  WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1396
1397  // Emit names for globals/functions etc.
1398  WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1399
1400  Stream.ExitBlock();
1401}
1402
1403/// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1404/// header and trailer to make it compatible with the system archiver.  To do
1405/// this we emit the following header, and then emit a trailer that pads the
1406/// file out to be a multiple of 16 bytes.
1407///
1408/// struct bc_header {
1409///   uint32_t Magic;         // 0x0B17C0DE
1410///   uint32_t Version;       // Version, currently always 0.
1411///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1412///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1413///   uint32_t CPUType;       // CPU specifier.
1414///   ... potentially more later ...
1415/// };
1416enum {
1417  DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1418  DarwinBCHeaderSize = 5*4
1419};
1420
1421static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1422                               const std::string &TT) {
1423  unsigned CPUType = ~0U;
1424
1425  // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1426  // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1427  // specific constants here because they are implicitly part of the Darwin ABI.
1428  enum {
1429    DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1430    DARWIN_CPU_TYPE_X86        = 7,
1431    DARWIN_CPU_TYPE_POWERPC    = 18
1432  };
1433
1434  if (TT.find("x86_64-") == 0)
1435    CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1436  else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1437           TT[4] == '-' && TT[1] - '3' < 6)
1438    CPUType = DARWIN_CPU_TYPE_X86;
1439  else if (TT.find("powerpc-") == 0)
1440    CPUType = DARWIN_CPU_TYPE_POWERPC;
1441  else if (TT.find("powerpc64-") == 0)
1442    CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1443
1444  // Traditional Bitcode starts after header.
1445  unsigned BCOffset = DarwinBCHeaderSize;
1446
1447  Stream.Emit(0x0B17C0DE, 32);
1448  Stream.Emit(0         , 32);  // Version.
1449  Stream.Emit(BCOffset  , 32);
1450  Stream.Emit(0         , 32);  // Filled in later.
1451  Stream.Emit(CPUType   , 32);
1452}
1453
1454/// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1455/// finalize the header.
1456static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1457  // Update the size field in the header.
1458  Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1459
1460  // If the file is not a multiple of 16 bytes, insert dummy padding.
1461  while (BufferSize & 15) {
1462    Stream.Emit(0, 8);
1463    ++BufferSize;
1464  }
1465}
1466
1467
1468/// WriteBitcodeToFile - Write the specified module to the specified output
1469/// stream.
1470void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1471  std::vector<unsigned char> Buffer;
1472  BitstreamWriter Stream(Buffer);
1473
1474  Buffer.reserve(256*1024);
1475
1476  WriteBitcodeToStream( M, Stream );
1477
1478  // If writing to stdout, set binary mode.
1479  if (&llvm::outs() == &Out)
1480    sys::Program::ChangeStdoutToBinary();
1481
1482  // Write the generated bitstream to "Out".
1483  Out.write((char*)&Buffer.front(), Buffer.size());
1484
1485  // Make sure it hits disk now.
1486  Out.flush();
1487}
1488
1489/// WriteBitcodeToStream - Write the specified module to the specified output
1490/// stream.
1491void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1492  // If this is darwin, emit a file header and trailer if needed.
1493  bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1494  if (isDarwin)
1495    EmitDarwinBCHeader(Stream, M->getTargetTriple());
1496
1497  // Emit the file header.
1498  Stream.Emit((unsigned)'B', 8);
1499  Stream.Emit((unsigned)'C', 8);
1500  Stream.Emit(0x0, 4);
1501  Stream.Emit(0xC, 4);
1502  Stream.Emit(0xE, 4);
1503  Stream.Emit(0xD, 4);
1504
1505  // Emit the module.
1506  WriteModule(M, Stream);
1507
1508  if (isDarwin)
1509    EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1510}
1511