BitcodeWriter.cpp revision 13ed1e293611f51efb87d1d131cda23b39ed3fde 
1//===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Bitcode writer implementation.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Bitcode/ReaderWriter.h"
15#include "llvm/Bitcode/BitstreamWriter.h"
16#include "llvm/Bitcode/LLVMBitCodes.h"
17#include "ValueEnumerator.h"
18#include "llvm/Constants.h"
19#include "llvm/DerivedTypes.h"
20#include "llvm/InlineAsm.h"
21#include "llvm/Instructions.h"
22#include "llvm/Metadata.h"
23#include "llvm/Module.h"
24#include "llvm/Operator.h"
25#include "llvm/TypeSymbolTable.h"
26#include "llvm/ValueSymbolTable.h"
27#include "llvm/Support/ErrorHandling.h"
28#include "llvm/Support/MathExtras.h"
29#include "llvm/Support/Streams.h"
30#include "llvm/Support/raw_ostream.h"
31#include "llvm/System/Program.h"
32using namespace llvm;
33
34/// These are manifest constants used by the bitcode writer. They do not need to
35/// be kept in sync with the reader, but need to be consistent within this file.
36enum {
37  CurVersion = 0,
38
39  // VALUE_SYMTAB_BLOCK abbrev id's.
40  VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
41  VST_ENTRY_7_ABBREV,
42  VST_ENTRY_6_ABBREV,
43  VST_BBENTRY_6_ABBREV,
44
45  // CONSTANTS_BLOCK abbrev id's.
46  CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
47  CONSTANTS_INTEGER_ABBREV,
48  CONSTANTS_CE_CAST_Abbrev,
49  CONSTANTS_NULL_Abbrev,
50
51  // FUNCTION_BLOCK abbrev id's.
52  FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
53  FUNCTION_INST_BINOP_ABBREV,
54  FUNCTION_INST_BINOP_FLAGS_ABBREV,
55  FUNCTION_INST_CAST_ABBREV,
56  FUNCTION_INST_RET_VOID_ABBREV,
57  FUNCTION_INST_RET_VAL_ABBREV,
58  FUNCTION_INST_UNREACHABLE_ABBREV
59};
60
61
62static unsigned GetEncodedCastOpcode(unsigned Opcode) {
63  switch (Opcode) {
64  default: llvm_unreachable("Unknown cast instruction!");
65  case Instruction::Trunc   : return bitc::CAST_TRUNC;
66  case Instruction::ZExt    : return bitc::CAST_ZEXT;
67  case Instruction::SExt    : return bitc::CAST_SEXT;
68  case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
69  case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
70  case Instruction::UIToFP  : return bitc::CAST_UITOFP;
71  case Instruction::SIToFP  : return bitc::CAST_SITOFP;
72  case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
73  case Instruction::FPExt   : return bitc::CAST_FPEXT;
74  case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
75  case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
76  case Instruction::BitCast : return bitc::CAST_BITCAST;
77  }
78}
79
80static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
81  switch (Opcode) {
82  default: llvm_unreachable("Unknown binary instruction!");
83  case Instruction::Add:
84  case Instruction::FAdd: return bitc::BINOP_ADD;
85  case Instruction::Sub:
86  case Instruction::FSub: return bitc::BINOP_SUB;
87  case Instruction::Mul:
88  case Instruction::FMul: return bitc::BINOP_MUL;
89  case Instruction::UDiv: return bitc::BINOP_UDIV;
90  case Instruction::FDiv:
91  case Instruction::SDiv: return bitc::BINOP_SDIV;
92  case Instruction::URem: return bitc::BINOP_UREM;
93  case Instruction::FRem:
94  case Instruction::SRem: return bitc::BINOP_SREM;
95  case Instruction::Shl:  return bitc::BINOP_SHL;
96  case Instruction::LShr: return bitc::BINOP_LSHR;
97  case Instruction::AShr: return bitc::BINOP_ASHR;
98  case Instruction::And:  return bitc::BINOP_AND;
99  case Instruction::Or:   return bitc::BINOP_OR;
100  case Instruction::Xor:  return bitc::BINOP_XOR;
101  }
102}
103
104
105
106static void WriteStringRecord(unsigned Code, const std::string &Str,
107                              unsigned AbbrevToUse, BitstreamWriter &Stream) {
108  SmallVector<unsigned, 64> Vals;
109
110  // Code: [strchar x N]
111  for (unsigned i = 0, e = Str.size(); i != e; ++i)
112    Vals.push_back(Str[i]);
113
114  // Emit the finished record.
115  Stream.EmitRecord(Code, Vals, AbbrevToUse);
116}
117
118// Emit information about parameter attributes.
119static void WriteAttributeTable(const ValueEnumerator &VE,
120                                BitstreamWriter &Stream) {
121  const std::vector<AttrListPtr> &Attrs = VE.getAttributes();
122  if (Attrs.empty()) return;
123
124  Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
125
126  SmallVector<uint64_t, 64> Record;
127  for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
128    const AttrListPtr &A = Attrs[i];
129    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
130      const AttributeWithIndex &PAWI = A.getSlot(i);
131      Record.push_back(PAWI.Index);
132
133      // FIXME: remove in LLVM 3.0
134      // Store the alignment in the bitcode as a 16-bit raw value instead of a
135      // 5-bit log2 encoded value. Shift the bits above the alignment up by
136      // 11 bits.
137      uint64_t FauxAttr = PAWI.Attrs & 0xffff;
138      if (PAWI.Attrs & Attribute::Alignment)
139        FauxAttr |= (1ull<<16)<<(((PAWI.Attrs & Attribute::Alignment)-1) >> 16);
140      FauxAttr |= (PAWI.Attrs & (0x3FFull << 21)) << 11;
141
142      Record.push_back(FauxAttr);
143    }
144
145    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
146    Record.clear();
147  }
148
149  Stream.ExitBlock();
150}
151
152/// WriteTypeTable - Write out the type table for a module.
153static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
154  const ValueEnumerator::TypeList &TypeList = VE.getTypes();
155
156  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
157  SmallVector<uint64_t, 64> TypeVals;
158
159  // Abbrev for TYPE_CODE_POINTER.
160  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
161  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
162  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
163                            Log2_32_Ceil(VE.getTypes().size()+1)));
164  Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
165  unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
166
167  // Abbrev for TYPE_CODE_FUNCTION.
168  Abbv = new BitCodeAbbrev();
169  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
170  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
171  Abbv->Add(BitCodeAbbrevOp(0));  // FIXME: DEAD value, remove in LLVM 3.0
172  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
173  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
174                            Log2_32_Ceil(VE.getTypes().size()+1)));
175  unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
176
177  // Abbrev for TYPE_CODE_STRUCT.
178  Abbv = new BitCodeAbbrev();
179  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
180  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
181  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
182  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
183                            Log2_32_Ceil(VE.getTypes().size()+1)));
184  unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
185
186  // Abbrev for TYPE_CODE_ARRAY.
187  Abbv = new BitCodeAbbrev();
188  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
189  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
190  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
191                            Log2_32_Ceil(VE.getTypes().size()+1)));
192  unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
193
194  // Emit an entry count so the reader can reserve space.
195  TypeVals.push_back(TypeList.size());
196  Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
197  TypeVals.clear();
198
199  // Loop over all of the types, emitting each in turn.
200  for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
201    const Type *T = TypeList[i].first;
202    int AbbrevToUse = 0;
203    unsigned Code = 0;
204
205    switch (T->getTypeID()) {
206    default: llvm_unreachable("Unknown type!");
207    case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
208    case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
209    case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
210    case Type::X86_FP80TyID: Code = bitc::TYPE_CODE_X86_FP80; break;
211    case Type::FP128TyID: Code = bitc::TYPE_CODE_FP128; break;
212    case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
213    case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
214    case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
215    case Type::MetadataTyID: Code = bitc::TYPE_CODE_METADATA; break;
216    case Type::IntegerTyID:
217      // INTEGER: [width]
218      Code = bitc::TYPE_CODE_INTEGER;
219      TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
220      break;
221    case Type::PointerTyID: {
222      const PointerType *PTy = cast<PointerType>(T);
223      // POINTER: [pointee type, address space]
224      Code = bitc::TYPE_CODE_POINTER;
225      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
226      unsigned AddressSpace = PTy->getAddressSpace();
227      TypeVals.push_back(AddressSpace);
228      if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
229      break;
230    }
231    case Type::FunctionTyID: {
232      const FunctionType *FT = cast<FunctionType>(T);
233      // FUNCTION: [isvararg, attrid, retty, paramty x N]
234      Code = bitc::TYPE_CODE_FUNCTION;
235      TypeVals.push_back(FT->isVarArg());
236      TypeVals.push_back(0);  // FIXME: DEAD: remove in llvm 3.0
237      TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
238      for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
239        TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
240      AbbrevToUse = FunctionAbbrev;
241      break;
242    }
243    case Type::StructTyID: {
244      const StructType *ST = cast<StructType>(T);
245      // STRUCT: [ispacked, eltty x N]
246      Code = bitc::TYPE_CODE_STRUCT;
247      TypeVals.push_back(ST->isPacked());
248      // Output all of the element types.
249      for (StructType::element_iterator I = ST->element_begin(),
250           E = ST->element_end(); I != E; ++I)
251        TypeVals.push_back(VE.getTypeID(*I));
252      AbbrevToUse = StructAbbrev;
253      break;
254    }
255    case Type::ArrayTyID: {
256      const ArrayType *AT = cast<ArrayType>(T);
257      // ARRAY: [numelts, eltty]
258      Code = bitc::TYPE_CODE_ARRAY;
259      TypeVals.push_back(AT->getNumElements());
260      TypeVals.push_back(VE.getTypeID(AT->getElementType()));
261      AbbrevToUse = ArrayAbbrev;
262      break;
263    }
264    case Type::VectorTyID: {
265      const VectorType *VT = cast<VectorType>(T);
266      // VECTOR [numelts, eltty]
267      Code = bitc::TYPE_CODE_VECTOR;
268      TypeVals.push_back(VT->getNumElements());
269      TypeVals.push_back(VE.getTypeID(VT->getElementType()));
270      break;
271    }
272    }
273
274    // Emit the finished record.
275    Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
276    TypeVals.clear();
277  }
278
279  Stream.ExitBlock();
280}
281
282static unsigned getEncodedLinkage(const GlobalValue *GV) {
283  switch (GV->getLinkage()) {
284  default: llvm_unreachable("Invalid linkage!");
285  case GlobalValue::GhostLinkage:  // Map ghost linkage onto external.
286  case GlobalValue::ExternalLinkage:            return 0;
287  case GlobalValue::WeakAnyLinkage:             return 1;
288  case GlobalValue::AppendingLinkage:           return 2;
289  case GlobalValue::InternalLinkage:            return 3;
290  case GlobalValue::LinkOnceAnyLinkage:         return 4;
291  case GlobalValue::DLLImportLinkage:           return 5;
292  case GlobalValue::DLLExportLinkage:           return 6;
293  case GlobalValue::ExternalWeakLinkage:        return 7;
294  case GlobalValue::CommonLinkage:              return 8;
295  case GlobalValue::PrivateLinkage:             return 9;
296  case GlobalValue::WeakODRLinkage:             return 10;
297  case GlobalValue::LinkOnceODRLinkage:         return 11;
298  case GlobalValue::AvailableExternallyLinkage: return 12;
299  case GlobalValue::LinkerPrivateLinkage:       return 13;
300  }
301}
302
303static unsigned getEncodedVisibility(const GlobalValue *GV) {
304  switch (GV->getVisibility()) {
305  default: llvm_unreachable("Invalid visibility!");
306  case GlobalValue::DefaultVisibility:   return 0;
307  case GlobalValue::HiddenVisibility:    return 1;
308  case GlobalValue::ProtectedVisibility: return 2;
309  }
310}
311
312// Emit top-level description of module, including target triple, inline asm,
313// descriptors for global variables, and function prototype info.
314static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
315                            BitstreamWriter &Stream) {
316  // Emit the list of dependent libraries for the Module.
317  for (Module::lib_iterator I = M->lib_begin(), E = M->lib_end(); I != E; ++I)
318    WriteStringRecord(bitc::MODULE_CODE_DEPLIB, *I, 0/*TODO*/, Stream);
319
320  // Emit various pieces of data attached to a module.
321  if (!M->getTargetTriple().empty())
322    WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
323                      0/*TODO*/, Stream);
324  if (!M->getDataLayout().empty())
325    WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, M->getDataLayout(),
326                      0/*TODO*/, Stream);
327  if (!M->getModuleInlineAsm().empty())
328    WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
329                      0/*TODO*/, Stream);
330
331  // Emit information about sections and GC, computing how many there are. Also
332  // compute the maximum alignment value.
333  std::map<std::string, unsigned> SectionMap;
334  std::map<std::string, unsigned> GCMap;
335  unsigned MaxAlignment = 0;
336  unsigned MaxGlobalType = 0;
337  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
338       GV != E; ++GV) {
339    MaxAlignment = std::max(MaxAlignment, GV->getAlignment());
340    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV->getType()));
341
342    if (!GV->hasSection()) continue;
343    // Give section names unique ID's.
344    unsigned &Entry = SectionMap[GV->getSection()];
345    if (Entry != 0) continue;
346    WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV->getSection(),
347                      0/*TODO*/, Stream);
348    Entry = SectionMap.size();
349  }
350  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
351    MaxAlignment = std::max(MaxAlignment, F->getAlignment());
352    if (F->hasSection()) {
353      // Give section names unique ID's.
354      unsigned &Entry = SectionMap[F->getSection()];
355      if (!Entry) {
356        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F->getSection(),
357                          0/*TODO*/, Stream);
358        Entry = SectionMap.size();
359      }
360    }
361    if (F->hasGC()) {
362      // Same for GC names.
363      unsigned &Entry = GCMap[F->getGC()];
364      if (!Entry) {
365        WriteStringRecord(bitc::MODULE_CODE_GCNAME, F->getGC(),
366                          0/*TODO*/, Stream);
367        Entry = GCMap.size();
368      }
369    }
370  }
371
372  // Emit abbrev for globals, now that we know # sections and max alignment.
373  unsigned SimpleGVarAbbrev = 0;
374  if (!M->global_empty()) {
375    // Add an abbrev for common globals with no visibility or thread localness.
376    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
377    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
378    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
379                              Log2_32_Ceil(MaxGlobalType+1)));
380    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
381    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
382    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
383    if (MaxAlignment == 0)                                      // Alignment.
384      Abbv->Add(BitCodeAbbrevOp(0));
385    else {
386      unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
387      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
388                               Log2_32_Ceil(MaxEncAlignment+1)));
389    }
390    if (SectionMap.empty())                                    // Section.
391      Abbv->Add(BitCodeAbbrevOp(0));
392    else
393      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
394                               Log2_32_Ceil(SectionMap.size()+1)));
395    // Don't bother emitting vis + thread local.
396    SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
397  }
398
399  // Emit the global variable information.
400  SmallVector<unsigned, 64> Vals;
401  for (Module::const_global_iterator GV = M->global_begin(),E = M->global_end();
402       GV != E; ++GV) {
403    unsigned AbbrevToUse = 0;
404
405    // GLOBALVAR: [type, isconst, initid,
406    //             linkage, alignment, section, visibility, threadlocal]
407    Vals.push_back(VE.getTypeID(GV->getType()));
408    Vals.push_back(GV->isConstant());
409    Vals.push_back(GV->isDeclaration() ? 0 :
410                   (VE.getValueID(GV->getInitializer()) + 1));
411    Vals.push_back(getEncodedLinkage(GV));
412    Vals.push_back(Log2_32(GV->getAlignment())+1);
413    Vals.push_back(GV->hasSection() ? SectionMap[GV->getSection()] : 0);
414    if (GV->isThreadLocal() ||
415        GV->getVisibility() != GlobalValue::DefaultVisibility) {
416      Vals.push_back(getEncodedVisibility(GV));
417      Vals.push_back(GV->isThreadLocal());
418    } else {
419      AbbrevToUse = SimpleGVarAbbrev;
420    }
421
422    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
423    Vals.clear();
424  }
425
426  // Emit the function proto information.
427  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
428    // FUNCTION:  [type, callingconv, isproto, paramattr,
429    //             linkage, alignment, section, visibility, gc]
430    Vals.push_back(VE.getTypeID(F->getType()));
431    Vals.push_back(F->getCallingConv());
432    Vals.push_back(F->isDeclaration());
433    Vals.push_back(getEncodedLinkage(F));
434    Vals.push_back(VE.getAttributeID(F->getAttributes()));
435    Vals.push_back(Log2_32(F->getAlignment())+1);
436    Vals.push_back(F->hasSection() ? SectionMap[F->getSection()] : 0);
437    Vals.push_back(getEncodedVisibility(F));
438    Vals.push_back(F->hasGC() ? GCMap[F->getGC()] : 0);
439
440    unsigned AbbrevToUse = 0;
441    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
442    Vals.clear();
443  }
444
445
446  // Emit the alias information.
447  for (Module::const_alias_iterator AI = M->alias_begin(), E = M->alias_end();
448       AI != E; ++AI) {
449    Vals.push_back(VE.getTypeID(AI->getType()));
450    Vals.push_back(VE.getValueID(AI->getAliasee()));
451    Vals.push_back(getEncodedLinkage(AI));
452    Vals.push_back(getEncodedVisibility(AI));
453    unsigned AbbrevToUse = 0;
454    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
455    Vals.clear();
456  }
457}
458
459static uint64_t GetOptimizationFlags(const Value *V) {
460  uint64_t Flags = 0;
461
462  if (const OverflowingBinaryOperator *OBO =
463        dyn_cast<OverflowingBinaryOperator>(V)) {
464    if (OBO->hasNoSignedOverflow())
465      Flags |= 1 << bitc::OBO_NO_SIGNED_OVERFLOW;
466    if (OBO->hasNoUnsignedOverflow())
467      Flags |= 1 << bitc::OBO_NO_UNSIGNED_OVERFLOW;
468  } else if (const SDivOperator *Div = dyn_cast<SDivOperator>(V)) {
469    if (Div->isExact())
470      Flags |= 1 << bitc::SDIV_EXACT;
471  }
472
473  return Flags;
474}
475
476/// WriteValues - Write Constants and Metadata.
477/// This function could use some refactoring help.
478static void WriteValues(unsigned FirstVal, unsigned LastVal,
479                        const ValueEnumerator &VE,
480                        BitstreamWriter &Stream, bool isGlobal) {
481  if (FirstVal == LastVal) return;
482
483  // MODULE_BLOCK_ID is 0, which is not handled here. So it is OK to use
484  // 0 as the initializer to indicate that block is not set.
485  enum bitc::BlockIDs LastBlockID = bitc::MODULE_BLOCK_ID;
486
487  unsigned AggregateAbbrev = 0;
488  unsigned String8Abbrev = 0;
489  unsigned CString7Abbrev = 0;
490  unsigned CString6Abbrev = 0;
491  unsigned MDSAbbrev = 0;
492
493  SmallVector<uint64_t, 64> Record;
494
495  const ValueEnumerator::ValueList &Vals = VE.getValues();
496  const Type *LastTy = 0;
497  for (unsigned i = FirstVal; i != LastVal; ++i) {
498    const Value *V = Vals[i].first;
499    if (isa<MetadataBase>(V)) {
500      if (LastBlockID != bitc::METADATA_BLOCK_ID) {
501        // Exit privious block.
502        if (LastBlockID != bitc::MODULE_BLOCK_ID)
503          Stream.ExitBlock();
504
505        LastBlockID = bitc::METADATA_BLOCK_ID;
506        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
507        // Abbrev for METADATA_STRING.
508        BitCodeAbbrev *Abbv = new BitCodeAbbrev();
509        Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
510        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
511        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
512        MDSAbbrev = Stream.EmitAbbrev(Abbv);
513      }
514    }
515    if (const MDString *MDS = dyn_cast<MDString>(V)) {
516      // Code: [strchar x N]
517      const char *StrBegin = MDS->begin();
518      for (unsigned i = 0, e = MDS->length(); i != e; ++i)
519        Record.push_back(StrBegin[i]);
520
521      // Emit the finished record.
522      Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
523      Record.clear();
524      continue;
525    } else if (const MDNode *N = dyn_cast<MDNode>(V)) {
526      for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
527        if (N->getElement(i)) {
528          Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
529          Record.push_back(VE.getValueID(N->getElement(i)));
530        } else {
531          Record.push_back(VE.getTypeID(Type::VoidTy));
532          Record.push_back(0);
533        }
534      }
535      Stream.EmitRecord(bitc::METADATA_NODE, Record, 0);
536      Record.clear();
537      continue;
538    } else if (const NamedMDNode *NMD = dyn_cast<NamedMDNode>(V)) {
539      // Write name.
540      std::string Str = NMD->getNameStr();
541      const char *StrBegin = Str.c_str();
542      for (unsigned i = 0, e = Str.length(); i != e; ++i)
543        Record.push_back(StrBegin[i]);
544      Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
545      Record.clear();
546
547      // Write named metadata elements.
548      for (unsigned i = 0, e = NMD->getNumElements(); i != e; ++i) {
549        if (NMD->getElement(i))
550          Record.push_back(VE.getValueID(NMD->getElement(i)));
551        else
552          Record.push_back(0);
553      }
554      Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
555      Record.clear();
556      continue;
557    }
558
559    // If we need to switch block, do so now.
560    if (LastBlockID != bitc::CONSTANTS_BLOCK_ID) {
561      // Exit privious block.
562      if (LastBlockID != bitc::MODULE_BLOCK_ID)
563        Stream.ExitBlock();
564
565      LastBlockID = bitc::CONSTANTS_BLOCK_ID;
566      Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
567      // If this is a constant pool for the module, emit module-specific abbrevs.
568      if (isGlobal) {
569        // Abbrev for CST_CODE_AGGREGATE.
570        BitCodeAbbrev *Abbv = new BitCodeAbbrev();
571        Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
572        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
573        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
574        AggregateAbbrev = Stream.EmitAbbrev(Abbv);
575
576        // Abbrev for CST_CODE_STRING.
577        Abbv = new BitCodeAbbrev();
578        Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
579        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
580        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
581        String8Abbrev = Stream.EmitAbbrev(Abbv);
582
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
590        // Abbrev for CST_CODE_CSTRING.
591        Abbv = new BitCodeAbbrev();
592        Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
593        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
594        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
595        CString6Abbrev = Stream.EmitAbbrev(Abbv);
596      }
597
598    }
599    // If we need to switch types, do so now.
600    if (V->getType() != LastTy) {
601      LastTy = V->getType();
602      Record.push_back(VE.getTypeID(LastTy));
603      Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
604                        CONSTANTS_SETTYPE_ABBREV);
605      Record.clear();
606    }
607
608    if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
609      Record.push_back(unsigned(IA->hasSideEffects()));
610
611      // Add the asm string.
612      const std::string &AsmStr = IA->getAsmString();
613      Record.push_back(AsmStr.size());
614      for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
615        Record.push_back(AsmStr[i]);
616
617      // Add the constraint string.
618      const std::string &ConstraintStr = IA->getConstraintString();
619      Record.push_back(ConstraintStr.size());
620      for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
621        Record.push_back(ConstraintStr[i]);
622      Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
623      Record.clear();
624      continue;
625    }
626    const Constant *C = cast<Constant>(V);
627    unsigned Code = -1U;
628    unsigned AbbrevToUse = 0;
629    if (C->isNullValue()) {
630      Code = bitc::CST_CODE_NULL;
631    } else if (isa<UndefValue>(C)) {
632      Code = bitc::CST_CODE_UNDEF;
633    } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
634      if (IV->getBitWidth() <= 64) {
635        int64_t V = IV->getSExtValue();
636        if (V >= 0)
637          Record.push_back(V << 1);
638        else
639          Record.push_back((-V << 1) | 1);
640        Code = bitc::CST_CODE_INTEGER;
641        AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
642      } else {                             // Wide integers, > 64 bits in size.
643        // We have an arbitrary precision integer value to write whose
644        // bit width is > 64. However, in canonical unsigned integer
645        // format it is likely that the high bits are going to be zero.
646        // So, we only write the number of active words.
647        unsigned NWords = IV->getValue().getActiveWords();
648        const uint64_t *RawWords = IV->getValue().getRawData();
649        for (unsigned i = 0; i != NWords; ++i) {
650          int64_t V = RawWords[i];
651          if (V >= 0)
652            Record.push_back(V << 1);
653          else
654            Record.push_back((-V << 1) | 1);
655        }
656        Code = bitc::CST_CODE_WIDE_INTEGER;
657      }
658    } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
659      Code = bitc::CST_CODE_FLOAT;
660      const Type *Ty = CFP->getType();
661      if (Ty == Type::FloatTy || Ty == Type::DoubleTy) {
662        Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
663      } else if (Ty == Type::X86_FP80Ty) {
664        // api needed to prevent premature destruction
665        // bits are not in the same order as a normal i80 APInt, compensate.
666        APInt api = CFP->getValueAPF().bitcastToAPInt();
667        const uint64_t *p = api.getRawData();
668        Record.push_back((p[1] << 48) | (p[0] >> 16));
669        Record.push_back(p[0] & 0xffffLL);
670      } else if (Ty == Type::FP128Ty || Ty == Type::PPC_FP128Ty) {
671        APInt api = CFP->getValueAPF().bitcastToAPInt();
672        const uint64_t *p = api.getRawData();
673        Record.push_back(p[0]);
674        Record.push_back(p[1]);
675      } else {
676        assert (0 && "Unknown FP type!");
677      }
678    } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
679      // Emit constant strings specially.
680      unsigned NumOps = C->getNumOperands();
681      // If this is a null-terminated string, use the denser CSTRING encoding.
682      if (C->getOperand(NumOps-1)->isNullValue()) {
683        Code = bitc::CST_CODE_CSTRING;
684        --NumOps;  // Don't encode the null, which isn't allowed by char6.
685      } else {
686        Code = bitc::CST_CODE_STRING;
687        AbbrevToUse = String8Abbrev;
688      }
689      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
690      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
691      for (unsigned i = 0; i != NumOps; ++i) {
692        unsigned char V = cast<ConstantInt>(C->getOperand(i))->getZExtValue();
693        Record.push_back(V);
694        isCStr7 &= (V & 128) == 0;
695        if (isCStrChar6)
696          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
697      }
698
699      if (isCStrChar6)
700        AbbrevToUse = CString6Abbrev;
701      else if (isCStr7)
702        AbbrevToUse = CString7Abbrev;
703    } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(V) ||
704               isa<ConstantVector>(V)) {
705      Code = bitc::CST_CODE_AGGREGATE;
706      for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
707        Record.push_back(VE.getValueID(C->getOperand(i)));
708      AbbrevToUse = AggregateAbbrev;
709    } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
710      switch (CE->getOpcode()) {
711      default:
712        if (Instruction::isCast(CE->getOpcode())) {
713          Code = bitc::CST_CODE_CE_CAST;
714          Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
715          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
716          Record.push_back(VE.getValueID(C->getOperand(0)));
717          AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
718        } else {
719          assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
720          Code = bitc::CST_CODE_CE_BINOP;
721          Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
722          Record.push_back(VE.getValueID(C->getOperand(0)));
723          Record.push_back(VE.getValueID(C->getOperand(1)));
724          uint64_t Flags = GetOptimizationFlags(CE);
725          if (Flags != 0)
726            Record.push_back(Flags);
727        }
728        break;
729      case Instruction::GetElementPtr:
730        Code = bitc::CST_CODE_CE_GEP;
731        if (cast<GEPOperator>(C)->isInBounds())
732          Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
733        for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
734          Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
735          Record.push_back(VE.getValueID(C->getOperand(i)));
736        }
737        break;
738      case Instruction::Select:
739        Code = bitc::CST_CODE_CE_SELECT;
740        Record.push_back(VE.getValueID(C->getOperand(0)));
741        Record.push_back(VE.getValueID(C->getOperand(1)));
742        Record.push_back(VE.getValueID(C->getOperand(2)));
743        break;
744      case Instruction::ExtractElement:
745        Code = bitc::CST_CODE_CE_EXTRACTELT;
746        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
747        Record.push_back(VE.getValueID(C->getOperand(0)));
748        Record.push_back(VE.getValueID(C->getOperand(1)));
749        break;
750      case Instruction::InsertElement:
751        Code = bitc::CST_CODE_CE_INSERTELT;
752        Record.push_back(VE.getValueID(C->getOperand(0)));
753        Record.push_back(VE.getValueID(C->getOperand(1)));
754        Record.push_back(VE.getValueID(C->getOperand(2)));
755        break;
756      case Instruction::ShuffleVector:
757        // If the return type and argument types are the same, this is a
758        // standard shufflevector instruction.  If the types are different,
759        // then the shuffle is widening or truncating the input vectors, and
760        // the argument type must also be encoded.
761        if (C->getType() == C->getOperand(0)->getType()) {
762          Code = bitc::CST_CODE_CE_SHUFFLEVEC;
763        } else {
764          Code = bitc::CST_CODE_CE_SHUFVEC_EX;
765          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
766        }
767        Record.push_back(VE.getValueID(C->getOperand(0)));
768        Record.push_back(VE.getValueID(C->getOperand(1)));
769        Record.push_back(VE.getValueID(C->getOperand(2)));
770        break;
771      case Instruction::ICmp:
772      case Instruction::FCmp:
773        Code = bitc::CST_CODE_CE_CMP;
774        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
775        Record.push_back(VE.getValueID(C->getOperand(0)));
776        Record.push_back(VE.getValueID(C->getOperand(1)));
777        Record.push_back(CE->getPredicate());
778        break;
779      }
780    } else {
781      llvm_unreachable("Unknown constant!");
782    }
783    Stream.EmitRecord(Code, Record, AbbrevToUse);
784    Record.clear();
785  }
786
787  Stream.ExitBlock();
788}
789
790static void WriteModuleConstants(const ValueEnumerator &VE,
791                                 BitstreamWriter &Stream) {
792  const ValueEnumerator::ValueList &Vals = VE.getValues();
793
794  // Find the first constant to emit, which is the first non-globalvalue value.
795  // We know globalvalues have been emitted by WriteModuleInfo.
796  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
797    if (!isa<GlobalValue>(Vals[i].first)) {
798      WriteValues(i, Vals.size(), VE, Stream, true);
799      return;
800    }
801  }
802}
803
804/// PushValueAndType - The file has to encode both the value and type id for
805/// many values, because we need to know what type to create for forward
806/// references.  However, most operands are not forward references, so this type
807/// field is not needed.
808///
809/// This function adds V's value ID to Vals.  If the value ID is higher than the
810/// instruction ID, then it is a forward reference, and it also includes the
811/// type ID.
812static bool PushValueAndType(const Value *V, unsigned InstID,
813                             SmallVector<unsigned, 64> &Vals,
814                             ValueEnumerator &VE) {
815  unsigned ValID = VE.getValueID(V);
816  Vals.push_back(ValID);
817  if (ValID >= InstID) {
818    Vals.push_back(VE.getTypeID(V->getType()));
819    return true;
820  }
821  return false;
822}
823
824/// WriteInstruction - Emit an instruction to the specified stream.
825static void WriteInstruction(const Instruction &I, unsigned InstID,
826                             ValueEnumerator &VE, BitstreamWriter &Stream,
827                             SmallVector<unsigned, 64> &Vals) {
828  unsigned Code = 0;
829  unsigned AbbrevToUse = 0;
830  switch (I.getOpcode()) {
831  default:
832    if (Instruction::isCast(I.getOpcode())) {
833      Code = bitc::FUNC_CODE_INST_CAST;
834      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
835        AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
836      Vals.push_back(VE.getTypeID(I.getType()));
837      Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
838    } else {
839      assert(isa<BinaryOperator>(I) && "Unknown instruction!");
840      Code = bitc::FUNC_CODE_INST_BINOP;
841      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
842        AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
843      Vals.push_back(VE.getValueID(I.getOperand(1)));
844      Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
845      uint64_t Flags = GetOptimizationFlags(&I);
846      if (Flags != 0) {
847        if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
848          AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
849        Vals.push_back(Flags);
850      }
851    }
852    break;
853
854  case Instruction::GetElementPtr:
855    Code = bitc::FUNC_CODE_INST_GEP;
856    if (cast<GEPOperator>(&I)->isInBounds())
857      Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
858    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
859      PushValueAndType(I.getOperand(i), InstID, Vals, VE);
860    break;
861  case Instruction::ExtractValue: {
862    Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
863    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
864    const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
865    for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
866      Vals.push_back(*i);
867    break;
868  }
869  case Instruction::InsertValue: {
870    Code = bitc::FUNC_CODE_INST_INSERTVAL;
871    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
872    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
873    const InsertValueInst *IVI = cast<InsertValueInst>(&I);
874    for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
875      Vals.push_back(*i);
876    break;
877  }
878  case Instruction::Select:
879    Code = bitc::FUNC_CODE_INST_VSELECT;
880    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
881    Vals.push_back(VE.getValueID(I.getOperand(2)));
882    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
883    break;
884  case Instruction::ExtractElement:
885    Code = bitc::FUNC_CODE_INST_EXTRACTELT;
886    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
887    Vals.push_back(VE.getValueID(I.getOperand(1)));
888    break;
889  case Instruction::InsertElement:
890    Code = bitc::FUNC_CODE_INST_INSERTELT;
891    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
892    Vals.push_back(VE.getValueID(I.getOperand(1)));
893    Vals.push_back(VE.getValueID(I.getOperand(2)));
894    break;
895  case Instruction::ShuffleVector:
896    Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
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::ICmp:
902  case Instruction::FCmp:
903    // compare returning Int1Ty or vector of Int1Ty
904    Code = bitc::FUNC_CODE_INST_CMP2;
905    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
906    Vals.push_back(VE.getValueID(I.getOperand(1)));
907    Vals.push_back(cast<CmpInst>(I).getPredicate());
908    break;
909
910  case Instruction::Ret:
911    {
912      Code = bitc::FUNC_CODE_INST_RET;
913      unsigned NumOperands = I.getNumOperands();
914      if (NumOperands == 0)
915        AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
916      else if (NumOperands == 1) {
917        if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
918          AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
919      } else {
920        for (unsigned i = 0, e = NumOperands; i != e; ++i)
921          PushValueAndType(I.getOperand(i), InstID, Vals, VE);
922      }
923    }
924    break;
925  case Instruction::Br:
926    {
927      Code = bitc::FUNC_CODE_INST_BR;
928      BranchInst &II(cast<BranchInst>(I));
929      Vals.push_back(VE.getValueID(II.getSuccessor(0)));
930      if (II.isConditional()) {
931        Vals.push_back(VE.getValueID(II.getSuccessor(1)));
932        Vals.push_back(VE.getValueID(II.getCondition()));
933      }
934    }
935    break;
936  case Instruction::Switch:
937    Code = bitc::FUNC_CODE_INST_SWITCH;
938    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
939    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
940      Vals.push_back(VE.getValueID(I.getOperand(i)));
941    break;
942  case Instruction::Invoke: {
943    const InvokeInst *II = cast<InvokeInst>(&I);
944    const Value *Callee(II->getCalledValue());
945    const PointerType *PTy = cast<PointerType>(Callee->getType());
946    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
947    Code = bitc::FUNC_CODE_INST_INVOKE;
948
949    Vals.push_back(VE.getAttributeID(II->getAttributes()));
950    Vals.push_back(II->getCallingConv());
951    Vals.push_back(VE.getValueID(II->getNormalDest()));
952    Vals.push_back(VE.getValueID(II->getUnwindDest()));
953    PushValueAndType(Callee, InstID, Vals, VE);
954
955    // Emit value #'s for the fixed parameters.
956    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
957      Vals.push_back(VE.getValueID(I.getOperand(i+3)));  // fixed param.
958
959    // Emit type/value pairs for varargs params.
960    if (FTy->isVarArg()) {
961      for (unsigned i = 3+FTy->getNumParams(), e = I.getNumOperands();
962           i != e; ++i)
963        PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
964    }
965    break;
966  }
967  case Instruction::Unwind:
968    Code = bitc::FUNC_CODE_INST_UNWIND;
969    break;
970  case Instruction::Unreachable:
971    Code = bitc::FUNC_CODE_INST_UNREACHABLE;
972    AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
973    break;
974
975  case Instruction::PHI:
976    Code = bitc::FUNC_CODE_INST_PHI;
977    Vals.push_back(VE.getTypeID(I.getType()));
978    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
979      Vals.push_back(VE.getValueID(I.getOperand(i)));
980    break;
981
982  case Instruction::Malloc:
983    Code = bitc::FUNC_CODE_INST_MALLOC;
984    Vals.push_back(VE.getTypeID(I.getType()));
985    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
986    Vals.push_back(Log2_32(cast<MallocInst>(I).getAlignment())+1);
987    break;
988
989  case Instruction::Free:
990    Code = bitc::FUNC_CODE_INST_FREE;
991    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
992    break;
993
994  case Instruction::Alloca:
995    Code = bitc::FUNC_CODE_INST_ALLOCA;
996    Vals.push_back(VE.getTypeID(I.getType()));
997    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
998    Vals.push_back(Log2_32(cast<AllocaInst>(I).getAlignment())+1);
999    break;
1000
1001  case Instruction::Load:
1002    Code = bitc::FUNC_CODE_INST_LOAD;
1003    if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1004      AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1005
1006    Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1007    Vals.push_back(cast<LoadInst>(I).isVolatile());
1008    break;
1009  case Instruction::Store:
1010    Code = bitc::FUNC_CODE_INST_STORE2;
1011    PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1012    Vals.push_back(VE.getValueID(I.getOperand(0)));       // val.
1013    Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1014    Vals.push_back(cast<StoreInst>(I).isVolatile());
1015    break;
1016  case Instruction::Call: {
1017    const PointerType *PTy = cast<PointerType>(I.getOperand(0)->getType());
1018    const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1019
1020    Code = bitc::FUNC_CODE_INST_CALL;
1021
1022    const CallInst *CI = cast<CallInst>(&I);
1023    Vals.push_back(VE.getAttributeID(CI->getAttributes()));
1024    Vals.push_back((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
1025    PushValueAndType(CI->getOperand(0), InstID, Vals, VE);  // Callee
1026
1027    // Emit value #'s for the fixed parameters.
1028    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1029      Vals.push_back(VE.getValueID(I.getOperand(i+1)));  // fixed param.
1030
1031    // Emit type/value pairs for varargs params.
1032    if (FTy->isVarArg()) {
1033      unsigned NumVarargs = I.getNumOperands()-1-FTy->getNumParams();
1034      for (unsigned i = I.getNumOperands()-NumVarargs, e = I.getNumOperands();
1035           i != e; ++i)
1036        PushValueAndType(I.getOperand(i), InstID, Vals, VE);  // varargs
1037    }
1038    break;
1039  }
1040  case Instruction::VAArg:
1041    Code = bitc::FUNC_CODE_INST_VAARG;
1042    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1043    Vals.push_back(VE.getValueID(I.getOperand(0))); // valist.
1044    Vals.push_back(VE.getTypeID(I.getType())); // restype.
1045    break;
1046  }
1047
1048  Stream.EmitRecord(Code, Vals, AbbrevToUse);
1049  Vals.clear();
1050}
1051
1052// Emit names for globals/functions etc.
1053static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1054                                  const ValueEnumerator &VE,
1055                                  BitstreamWriter &Stream) {
1056  if (VST.empty()) return;
1057  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1058
1059  // FIXME: Set up the abbrev, we know how many values there are!
1060  // FIXME: We know if the type names can use 7-bit ascii.
1061  SmallVector<unsigned, 64> NameVals;
1062
1063  for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1064       SI != SE; ++SI) {
1065
1066    const ValueName &Name = *SI;
1067
1068    // Figure out the encoding to use for the name.
1069    bool is7Bit = true;
1070    bool isChar6 = true;
1071    for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1072         C != E; ++C) {
1073      if (isChar6)
1074        isChar6 = BitCodeAbbrevOp::isChar6(*C);
1075      if ((unsigned char)*C & 128) {
1076        is7Bit = false;
1077        break;  // don't bother scanning the rest.
1078      }
1079    }
1080
1081    unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1082
1083    // VST_ENTRY:   [valueid, namechar x N]
1084    // VST_BBENTRY: [bbid, namechar x N]
1085    unsigned Code;
1086    if (isa<BasicBlock>(SI->getValue())) {
1087      Code = bitc::VST_CODE_BBENTRY;
1088      if (isChar6)
1089        AbbrevToUse = VST_BBENTRY_6_ABBREV;
1090    } else {
1091      Code = bitc::VST_CODE_ENTRY;
1092      if (isChar6)
1093        AbbrevToUse = VST_ENTRY_6_ABBREV;
1094      else if (is7Bit)
1095        AbbrevToUse = VST_ENTRY_7_ABBREV;
1096    }
1097
1098    NameVals.push_back(VE.getValueID(SI->getValue()));
1099    for (const char *P = Name.getKeyData(),
1100         *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1101      NameVals.push_back((unsigned char)*P);
1102
1103    // Emit the finished record.
1104    Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1105    NameVals.clear();
1106  }
1107  Stream.ExitBlock();
1108}
1109
1110/// WriteFunction - Emit a function body to the module stream.
1111static void WriteFunction(const Function &F, ValueEnumerator &VE,
1112                          BitstreamWriter &Stream) {
1113  Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1114  VE.incorporateFunction(F);
1115
1116  SmallVector<unsigned, 64> Vals;
1117
1118  // Emit the number of basic blocks, so the reader can create them ahead of
1119  // time.
1120  Vals.push_back(VE.getBasicBlocks().size());
1121  Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1122  Vals.clear();
1123
1124  // If there are function-local constants, emit them now.
1125  unsigned CstStart, CstEnd;
1126  VE.getFunctionConstantRange(CstStart, CstEnd);
1127  WriteValues(CstStart, CstEnd, VE, Stream, false);
1128
1129  // Keep a running idea of what the instruction ID is.
1130  unsigned InstID = CstEnd;
1131
1132  // Finally, emit all the instructions, in order.
1133  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1134    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1135         I != E; ++I) {
1136      WriteInstruction(*I, InstID, VE, Stream, Vals);
1137      if (I->getType() != Type::VoidTy)
1138        ++InstID;
1139    }
1140
1141  // Emit names for all the instructions etc.
1142  WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1143
1144  VE.purgeFunction();
1145  Stream.ExitBlock();
1146}
1147
1148/// WriteTypeSymbolTable - Emit a block for the specified type symtab.
1149static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
1150                                 const ValueEnumerator &VE,
1151                                 BitstreamWriter &Stream) {
1152  if (TST.empty()) return;
1153
1154  Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
1155
1156  // 7-bit fixed width VST_CODE_ENTRY strings.
1157  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1158  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1159  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1160                            Log2_32_Ceil(VE.getTypes().size()+1)));
1161  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1162  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1163  unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
1164
1165  SmallVector<unsigned, 64> NameVals;
1166
1167  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
1168       TI != TE; ++TI) {
1169    // TST_ENTRY: [typeid, namechar x N]
1170    NameVals.push_back(VE.getTypeID(TI->second));
1171
1172    const std::string &Str = TI->first;
1173    bool is7Bit = true;
1174    for (unsigned i = 0, e = Str.size(); i != e; ++i) {
1175      NameVals.push_back((unsigned char)Str[i]);
1176      if (Str[i] & 128)
1177        is7Bit = false;
1178    }
1179
1180    // Emit the finished record.
1181    Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
1182    NameVals.clear();
1183  }
1184
1185  Stream.ExitBlock();
1186}
1187
1188// Emit blockinfo, which defines the standard abbreviations etc.
1189static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1190  // We only want to emit block info records for blocks that have multiple
1191  // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.  Other
1192  // blocks can defined their abbrevs inline.
1193  Stream.EnterBlockInfoBlock(2);
1194
1195  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1196    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1197    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1198    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1199    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1200    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1201    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1202                                   Abbv) != VST_ENTRY_8_ABBREV)
1203      llvm_unreachable("Unexpected abbrev ordering!");
1204  }
1205
1206  { // 7-bit fixed width VST_ENTRY strings.
1207    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1208    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1209    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1210    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1211    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1212    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1213                                   Abbv) != VST_ENTRY_7_ABBREV)
1214      llvm_unreachable("Unexpected abbrev ordering!");
1215  }
1216  { // 6-bit char6 VST_ENTRY strings.
1217    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1218    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1219    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1220    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1221    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1222    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1223                                   Abbv) != VST_ENTRY_6_ABBREV)
1224      llvm_unreachable("Unexpected abbrev ordering!");
1225  }
1226  { // 6-bit char6 VST_BBENTRY strings.
1227    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1228    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1229    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1230    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1231    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1232    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1233                                   Abbv) != VST_BBENTRY_6_ABBREV)
1234      llvm_unreachable("Unexpected abbrev ordering!");
1235  }
1236
1237
1238
1239  { // SETTYPE abbrev for CONSTANTS_BLOCK.
1240    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1241    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1242    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1243                              Log2_32_Ceil(VE.getTypes().size()+1)));
1244    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1245                                   Abbv) != CONSTANTS_SETTYPE_ABBREV)
1246      llvm_unreachable("Unexpected abbrev ordering!");
1247  }
1248
1249  { // INTEGER abbrev for CONSTANTS_BLOCK.
1250    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1251    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1252    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1253    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1254                                   Abbv) != CONSTANTS_INTEGER_ABBREV)
1255      llvm_unreachable("Unexpected abbrev ordering!");
1256  }
1257
1258  { // CE_CAST abbrev for CONSTANTS_BLOCK.
1259    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1260    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1261    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1262    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1263                              Log2_32_Ceil(VE.getTypes().size()+1)));
1264    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1265
1266    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1267                                   Abbv) != CONSTANTS_CE_CAST_Abbrev)
1268      llvm_unreachable("Unexpected abbrev ordering!");
1269  }
1270  { // NULL abbrev for CONSTANTS_BLOCK.
1271    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1272    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1273    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1274                                   Abbv) != CONSTANTS_NULL_Abbrev)
1275      llvm_unreachable("Unexpected abbrev ordering!");
1276  }
1277
1278  // FIXME: This should only use space for first class types!
1279
1280  { // INST_LOAD abbrev for FUNCTION_BLOCK.
1281    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1282    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1283    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1284    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1285    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1286    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1287                                   Abbv) != FUNCTION_INST_LOAD_ABBREV)
1288      llvm_unreachable("Unexpected abbrev ordering!");
1289  }
1290  { // INST_BINOP abbrev for FUNCTION_BLOCK.
1291    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1292    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1293    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1294    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1295    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1296    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1297                                   Abbv) != FUNCTION_INST_BINOP_ABBREV)
1298      llvm_unreachable("Unexpected abbrev ordering!");
1299  }
1300  { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1301    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1302    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1303    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1304    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1305    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1306    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1307    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1308                                   Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1309      llvm_unreachable("Unexpected abbrev ordering!");
1310  }
1311  { // INST_CAST abbrev for FUNCTION_BLOCK.
1312    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1313    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1314    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1315    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1316                              Log2_32_Ceil(VE.getTypes().size()+1)));
1317    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1318    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1319                                   Abbv) != FUNCTION_INST_CAST_ABBREV)
1320      llvm_unreachable("Unexpected abbrev ordering!");
1321  }
1322
1323  { // INST_RET abbrev for FUNCTION_BLOCK.
1324    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1325    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1326    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1327                                   Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1328      llvm_unreachable("Unexpected abbrev ordering!");
1329  }
1330  { // INST_RET abbrev for FUNCTION_BLOCK.
1331    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1332    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1333    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1334    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1335                                   Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1336      llvm_unreachable("Unexpected abbrev ordering!");
1337  }
1338  { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1339    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1340    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1341    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1342                                   Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1343      llvm_unreachable("Unexpected abbrev ordering!");
1344  }
1345
1346  Stream.ExitBlock();
1347}
1348
1349
1350/// WriteModule - Emit the specified module to the bitstream.
1351static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1352  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1353
1354  // Emit the version number if it is non-zero.
1355  if (CurVersion) {
1356    SmallVector<unsigned, 1> Vals;
1357    Vals.push_back(CurVersion);
1358    Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1359  }
1360
1361  // Analyze the module, enumerating globals, functions, etc.
1362  ValueEnumerator VE(M);
1363
1364  // Emit blockinfo, which defines the standard abbreviations etc.
1365  WriteBlockInfo(VE, Stream);
1366
1367  // Emit information about parameter attributes.
1368  WriteAttributeTable(VE, Stream);
1369
1370  // Emit information describing all of the types in the module.
1371  WriteTypeTable(VE, Stream);
1372
1373  // Emit top-level description of module, including target triple, inline asm,
1374  // descriptors for global variables, and function prototype info.
1375  WriteModuleInfo(M, VE, Stream);
1376
1377  // Emit constants.
1378  WriteModuleConstants(VE, Stream);
1379
1380  // Emit function bodies.
1381  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
1382    if (!I->isDeclaration())
1383      WriteFunction(*I, VE, Stream);
1384
1385  // Emit the type symbol table information.
1386  WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
1387
1388  // Emit names for globals/functions etc.
1389  WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1390
1391  Stream.ExitBlock();
1392}
1393
1394/// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1395/// header and trailer to make it compatible with the system archiver.  To do
1396/// this we emit the following header, and then emit a trailer that pads the
1397/// file out to be a multiple of 16 bytes.
1398///
1399/// struct bc_header {
1400///   uint32_t Magic;         // 0x0B17C0DE
1401///   uint32_t Version;       // Version, currently always 0.
1402///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1403///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1404///   uint32_t CPUType;       // CPU specifier.
1405///   ... potentially more later ...
1406/// };
1407enum {
1408  DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1409  DarwinBCHeaderSize = 5*4
1410};
1411
1412static void EmitDarwinBCHeader(BitstreamWriter &Stream,
1413                               const std::string &TT) {
1414  unsigned CPUType = ~0U;
1415
1416  // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*.  The CPUType is a
1417  // magic number from /usr/include/mach/machine.h.  It is ok to reproduce the
1418  // specific constants here because they are implicitly part of the Darwin ABI.
1419  enum {
1420    DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1421    DARWIN_CPU_TYPE_X86        = 7,
1422    DARWIN_CPU_TYPE_POWERPC    = 18
1423  };
1424
1425  if (TT.find("x86_64-") == 0)
1426    CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1427  else if (TT.size() >= 5 && TT[0] == 'i' && TT[2] == '8' && TT[3] == '6' &&
1428           TT[4] == '-' && TT[1] - '3' < 6)
1429    CPUType = DARWIN_CPU_TYPE_X86;
1430  else if (TT.find("powerpc-") == 0)
1431    CPUType = DARWIN_CPU_TYPE_POWERPC;
1432  else if (TT.find("powerpc64-") == 0)
1433    CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1434
1435  // Traditional Bitcode starts after header.
1436  unsigned BCOffset = DarwinBCHeaderSize;
1437
1438  Stream.Emit(0x0B17C0DE, 32);
1439  Stream.Emit(0         , 32);  // Version.
1440  Stream.Emit(BCOffset  , 32);
1441  Stream.Emit(0         , 32);  // Filled in later.
1442  Stream.Emit(CPUType   , 32);
1443}
1444
1445/// EmitDarwinBCTrailer - Emit the darwin epilog after the bitcode file and
1446/// finalize the header.
1447static void EmitDarwinBCTrailer(BitstreamWriter &Stream, unsigned BufferSize) {
1448  // Update the size field in the header.
1449  Stream.BackpatchWord(DarwinBCSizeFieldOffset, BufferSize-DarwinBCHeaderSize);
1450
1451  // If the file is not a multiple of 16 bytes, insert dummy padding.
1452  while (BufferSize & 15) {
1453    Stream.Emit(0, 8);
1454    ++BufferSize;
1455  }
1456}
1457
1458
1459/// WriteBitcodeToFile - Write the specified module to the specified output
1460/// stream.
1461void llvm::WriteBitcodeToFile(const Module *M, std::ostream &Out) {
1462  raw_os_ostream RawOut(Out);
1463  // If writing to stdout, set binary mode.
1464  if (llvm::cout == Out)
1465    sys::Program::ChangeStdoutToBinary();
1466  WriteBitcodeToFile(M, RawOut);
1467}
1468
1469/// WriteBitcodeToFile - Write the specified module to the specified output
1470/// stream.
1471void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
1472  std::vector<unsigned char> Buffer;
1473  BitstreamWriter Stream(Buffer);
1474
1475  Buffer.reserve(256*1024);
1476
1477  WriteBitcodeToStream( M, Stream );
1478
1479  // If writing to stdout, set binary mode.
1480  if (&llvm::outs() == &Out)
1481    sys::Program::ChangeStdoutToBinary();
1482
1483  // Write the generated bitstream to "Out".
1484  Out.write((char*)&Buffer.front(), Buffer.size());
1485
1486  // Make sure it hits disk now.
1487  Out.flush();
1488}
1489
1490/// WriteBitcodeToStream - Write the specified module to the specified output
1491/// stream.
1492void llvm::WriteBitcodeToStream(const Module *M, BitstreamWriter &Stream) {
1493  // If this is darwin, emit a file header and trailer if needed.
1494  bool isDarwin = M->getTargetTriple().find("-darwin") != std::string::npos;
1495  if (isDarwin)
1496    EmitDarwinBCHeader(Stream, M->getTargetTriple());
1497
1498  // Emit the file header.
1499  Stream.Emit((unsigned)'B', 8);
1500  Stream.Emit((unsigned)'C', 8);
1501  Stream.Emit(0x0, 4);
1502  Stream.Emit(0xC, 4);
1503  Stream.Emit(0xE, 4);
1504  Stream.Emit(0xD, 4);
1505
1506  // Emit the module.
1507  WriteModule(M, Stream);
1508
1509  if (isDarwin)
1510    EmitDarwinBCTrailer(Stream, Stream.getBuffer().size());
1511}
1512