BitcodeWriter.cpp revision 37ed9c199ca639565f6ce88105f9e39e898d82d0 
1//===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Bitcode writer implementation.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Bitcode/ReaderWriter.h"
15#include "ValueEnumerator.h"
16#include "llvm/ADT/Triple.h"
17#include "llvm/Bitcode/BitstreamWriter.h"
18#include "llvm/Bitcode/LLVMBitCodes.h"
19#include "llvm/IR/Constants.h"
20#include "llvm/IR/DerivedTypes.h"
21#include "llvm/IR/InlineAsm.h"
22#include "llvm/IR/Instructions.h"
23#include "llvm/IR/Module.h"
24#include "llvm/IR/Operator.h"
25#include "llvm/IR/UseListOrder.h"
26#include "llvm/IR/ValueSymbolTable.h"
27#include "llvm/Support/CommandLine.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/Support/MathExtras.h"
30#include "llvm/Support/Program.h"
31#include "llvm/Support/raw_ostream.h"
32#include <cctype>
33#include <map>
34using namespace llvm;
35
36/// These are manifest constants used by the bitcode writer. They do not need to
37/// be kept in sync with the reader, but need to be consistent within this file.
38enum {
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
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  case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
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
104static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
105  switch (Op) {
106  default: llvm_unreachable("Unknown RMW operation!");
107  case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
108  case AtomicRMWInst::Add: return bitc::RMW_ADD;
109  case AtomicRMWInst::Sub: return bitc::RMW_SUB;
110  case AtomicRMWInst::And: return bitc::RMW_AND;
111  case AtomicRMWInst::Nand: return bitc::RMW_NAND;
112  case AtomicRMWInst::Or: return bitc::RMW_OR;
113  case AtomicRMWInst::Xor: return bitc::RMW_XOR;
114  case AtomicRMWInst::Max: return bitc::RMW_MAX;
115  case AtomicRMWInst::Min: return bitc::RMW_MIN;
116  case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
117  case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
118  }
119}
120
121static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
122  switch (Ordering) {
123  case NotAtomic: return bitc::ORDERING_NOTATOMIC;
124  case Unordered: return bitc::ORDERING_UNORDERED;
125  case Monotonic: return bitc::ORDERING_MONOTONIC;
126  case Acquire: return bitc::ORDERING_ACQUIRE;
127  case Release: return bitc::ORDERING_RELEASE;
128  case AcquireRelease: return bitc::ORDERING_ACQREL;
129  case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
130  }
131  llvm_unreachable("Invalid ordering");
132}
133
134static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
135  switch (SynchScope) {
136  case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
137  case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
138  }
139  llvm_unreachable("Invalid synch scope");
140}
141
142static void WriteStringRecord(unsigned Code, StringRef Str,
143                              unsigned AbbrevToUse, BitstreamWriter &Stream) {
144  SmallVector<unsigned, 64> Vals;
145
146  // Code: [strchar x N]
147  for (unsigned i = 0, e = Str.size(); i != e; ++i) {
148    if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
149      AbbrevToUse = 0;
150    Vals.push_back(Str[i]);
151  }
152
153  // Emit the finished record.
154  Stream.EmitRecord(Code, Vals, AbbrevToUse);
155}
156
157static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
158  switch (Kind) {
159  case Attribute::Alignment:
160    return bitc::ATTR_KIND_ALIGNMENT;
161  case Attribute::AlwaysInline:
162    return bitc::ATTR_KIND_ALWAYS_INLINE;
163  case Attribute::Builtin:
164    return bitc::ATTR_KIND_BUILTIN;
165  case Attribute::ByVal:
166    return bitc::ATTR_KIND_BY_VAL;
167  case Attribute::InAlloca:
168    return bitc::ATTR_KIND_IN_ALLOCA;
169  case Attribute::Cold:
170    return bitc::ATTR_KIND_COLD;
171  case Attribute::InlineHint:
172    return bitc::ATTR_KIND_INLINE_HINT;
173  case Attribute::InReg:
174    return bitc::ATTR_KIND_IN_REG;
175  case Attribute::JumpTable:
176    return bitc::ATTR_KIND_JUMP_TABLE;
177  case Attribute::MinSize:
178    return bitc::ATTR_KIND_MIN_SIZE;
179  case Attribute::Naked:
180    return bitc::ATTR_KIND_NAKED;
181  case Attribute::Nest:
182    return bitc::ATTR_KIND_NEST;
183  case Attribute::NoAlias:
184    return bitc::ATTR_KIND_NO_ALIAS;
185  case Attribute::NoBuiltin:
186    return bitc::ATTR_KIND_NO_BUILTIN;
187  case Attribute::NoCapture:
188    return bitc::ATTR_KIND_NO_CAPTURE;
189  case Attribute::NoDuplicate:
190    return bitc::ATTR_KIND_NO_DUPLICATE;
191  case Attribute::NoImplicitFloat:
192    return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
193  case Attribute::NoInline:
194    return bitc::ATTR_KIND_NO_INLINE;
195  case Attribute::NonLazyBind:
196    return bitc::ATTR_KIND_NON_LAZY_BIND;
197  case Attribute::NonNull:
198    return bitc::ATTR_KIND_NON_NULL;
199  case Attribute::Dereferenceable:
200    return bitc::ATTR_KIND_DEREFERENCEABLE;
201  case Attribute::NoRedZone:
202    return bitc::ATTR_KIND_NO_RED_ZONE;
203  case Attribute::NoReturn:
204    return bitc::ATTR_KIND_NO_RETURN;
205  case Attribute::NoUnwind:
206    return bitc::ATTR_KIND_NO_UNWIND;
207  case Attribute::OptimizeForSize:
208    return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
209  case Attribute::OptimizeNone:
210    return bitc::ATTR_KIND_OPTIMIZE_NONE;
211  case Attribute::ReadNone:
212    return bitc::ATTR_KIND_READ_NONE;
213  case Attribute::ReadOnly:
214    return bitc::ATTR_KIND_READ_ONLY;
215  case Attribute::Returned:
216    return bitc::ATTR_KIND_RETURNED;
217  case Attribute::ReturnsTwice:
218    return bitc::ATTR_KIND_RETURNS_TWICE;
219  case Attribute::SExt:
220    return bitc::ATTR_KIND_S_EXT;
221  case Attribute::StackAlignment:
222    return bitc::ATTR_KIND_STACK_ALIGNMENT;
223  case Attribute::StackProtect:
224    return bitc::ATTR_KIND_STACK_PROTECT;
225  case Attribute::StackProtectReq:
226    return bitc::ATTR_KIND_STACK_PROTECT_REQ;
227  case Attribute::StackProtectStrong:
228    return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
229  case Attribute::StructRet:
230    return bitc::ATTR_KIND_STRUCT_RET;
231  case Attribute::SanitizeAddress:
232    return bitc::ATTR_KIND_SANITIZE_ADDRESS;
233  case Attribute::SanitizeThread:
234    return bitc::ATTR_KIND_SANITIZE_THREAD;
235  case Attribute::SanitizeMemory:
236    return bitc::ATTR_KIND_SANITIZE_MEMORY;
237  case Attribute::UWTable:
238    return bitc::ATTR_KIND_UW_TABLE;
239  case Attribute::ZExt:
240    return bitc::ATTR_KIND_Z_EXT;
241  case Attribute::EndAttrKinds:
242    llvm_unreachable("Can not encode end-attribute kinds marker.");
243  case Attribute::None:
244    llvm_unreachable("Can not encode none-attribute.");
245  }
246
247  llvm_unreachable("Trying to encode unknown attribute");
248}
249
250static void WriteAttributeGroupTable(const ValueEnumerator &VE,
251                                     BitstreamWriter &Stream) {
252  const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
253  if (AttrGrps.empty()) return;
254
255  Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
256
257  SmallVector<uint64_t, 64> Record;
258  for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
259    AttributeSet AS = AttrGrps[i];
260    for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
261      AttributeSet A = AS.getSlotAttributes(i);
262
263      Record.push_back(VE.getAttributeGroupID(A));
264      Record.push_back(AS.getSlotIndex(i));
265
266      for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
267           I != E; ++I) {
268        Attribute Attr = *I;
269        if (Attr.isEnumAttribute()) {
270          Record.push_back(0);
271          Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
272        } else if (Attr.isIntAttribute()) {
273          Record.push_back(1);
274          Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
275          Record.push_back(Attr.getValueAsInt());
276        } else {
277          StringRef Kind = Attr.getKindAsString();
278          StringRef Val = Attr.getValueAsString();
279
280          Record.push_back(Val.empty() ? 3 : 4);
281          Record.append(Kind.begin(), Kind.end());
282          Record.push_back(0);
283          if (!Val.empty()) {
284            Record.append(Val.begin(), Val.end());
285            Record.push_back(0);
286          }
287        }
288      }
289
290      Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
291      Record.clear();
292    }
293  }
294
295  Stream.ExitBlock();
296}
297
298static void WriteAttributeTable(const ValueEnumerator &VE,
299                                BitstreamWriter &Stream) {
300  const std::vector<AttributeSet> &Attrs = VE.getAttributes();
301  if (Attrs.empty()) return;
302
303  Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
304
305  SmallVector<uint64_t, 64> Record;
306  for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
307    const AttributeSet &A = Attrs[i];
308    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
309      Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
310
311    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
312    Record.clear();
313  }
314
315  Stream.ExitBlock();
316}
317
318/// WriteTypeTable - Write out the type table for a module.
319static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
320  const ValueEnumerator::TypeList &TypeList = VE.getTypes();
321
322  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
323  SmallVector<uint64_t, 64> TypeVals;
324
325  uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
326
327  // Abbrev for TYPE_CODE_POINTER.
328  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
329  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
330  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
331  Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
332  unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
333
334  // Abbrev for TYPE_CODE_FUNCTION.
335  Abbv = new BitCodeAbbrev();
336  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
337  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
338  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
339  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
340
341  unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
342
343  // Abbrev for TYPE_CODE_STRUCT_ANON.
344  Abbv = new BitCodeAbbrev();
345  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
346  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
347  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
348  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
349
350  unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
351
352  // Abbrev for TYPE_CODE_STRUCT_NAME.
353  Abbv = new BitCodeAbbrev();
354  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
355  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
356  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
357  unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
358
359  // Abbrev for TYPE_CODE_STRUCT_NAMED.
360  Abbv = new BitCodeAbbrev();
361  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
362  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
363  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
364  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
365
366  unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
367
368  // Abbrev for TYPE_CODE_ARRAY.
369  Abbv = new BitCodeAbbrev();
370  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
371  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
372  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
373
374  unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
375
376  // Emit an entry count so the reader can reserve space.
377  TypeVals.push_back(TypeList.size());
378  Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
379  TypeVals.clear();
380
381  // Loop over all of the types, emitting each in turn.
382  for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
383    Type *T = TypeList[i];
384    int AbbrevToUse = 0;
385    unsigned Code = 0;
386
387    switch (T->getTypeID()) {
388    case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
389    case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
390    case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
391    case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
392    case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
393    case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
394    case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
395    case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
396    case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
397    case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
398    case Type::IntegerTyID:
399      // INTEGER: [width]
400      Code = bitc::TYPE_CODE_INTEGER;
401      TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
402      break;
403    case Type::PointerTyID: {
404      PointerType *PTy = cast<PointerType>(T);
405      // POINTER: [pointee type, address space]
406      Code = bitc::TYPE_CODE_POINTER;
407      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
408      unsigned AddressSpace = PTy->getAddressSpace();
409      TypeVals.push_back(AddressSpace);
410      if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
411      break;
412    }
413    case Type::FunctionTyID: {
414      FunctionType *FT = cast<FunctionType>(T);
415      // FUNCTION: [isvararg, retty, paramty x N]
416      Code = bitc::TYPE_CODE_FUNCTION;
417      TypeVals.push_back(FT->isVarArg());
418      TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
419      for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
420        TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
421      AbbrevToUse = FunctionAbbrev;
422      break;
423    }
424    case Type::StructTyID: {
425      StructType *ST = cast<StructType>(T);
426      // STRUCT: [ispacked, eltty x N]
427      TypeVals.push_back(ST->isPacked());
428      // Output all of the element types.
429      for (StructType::element_iterator I = ST->element_begin(),
430           E = ST->element_end(); I != E; ++I)
431        TypeVals.push_back(VE.getTypeID(*I));
432
433      if (ST->isLiteral()) {
434        Code = bitc::TYPE_CODE_STRUCT_ANON;
435        AbbrevToUse = StructAnonAbbrev;
436      } else {
437        if (ST->isOpaque()) {
438          Code = bitc::TYPE_CODE_OPAQUE;
439        } else {
440          Code = bitc::TYPE_CODE_STRUCT_NAMED;
441          AbbrevToUse = StructNamedAbbrev;
442        }
443
444        // Emit the name if it is present.
445        if (!ST->getName().empty())
446          WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
447                            StructNameAbbrev, Stream);
448      }
449      break;
450    }
451    case Type::ArrayTyID: {
452      ArrayType *AT = cast<ArrayType>(T);
453      // ARRAY: [numelts, eltty]
454      Code = bitc::TYPE_CODE_ARRAY;
455      TypeVals.push_back(AT->getNumElements());
456      TypeVals.push_back(VE.getTypeID(AT->getElementType()));
457      AbbrevToUse = ArrayAbbrev;
458      break;
459    }
460    case Type::VectorTyID: {
461      VectorType *VT = cast<VectorType>(T);
462      // VECTOR [numelts, eltty]
463      Code = bitc::TYPE_CODE_VECTOR;
464      TypeVals.push_back(VT->getNumElements());
465      TypeVals.push_back(VE.getTypeID(VT->getElementType()));
466      break;
467    }
468    }
469
470    // Emit the finished record.
471    Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
472    TypeVals.clear();
473  }
474
475  Stream.ExitBlock();
476}
477
478static unsigned getEncodedLinkage(const GlobalValue &GV) {
479  switch (GV.getLinkage()) {
480  case GlobalValue::ExternalLinkage:                 return 0;
481  case GlobalValue::WeakAnyLinkage:                  return 1;
482  case GlobalValue::AppendingLinkage:                return 2;
483  case GlobalValue::InternalLinkage:                 return 3;
484  case GlobalValue::LinkOnceAnyLinkage:              return 4;
485  case GlobalValue::ExternalWeakLinkage:             return 7;
486  case GlobalValue::CommonLinkage:                   return 8;
487  case GlobalValue::PrivateLinkage:                  return 9;
488  case GlobalValue::WeakODRLinkage:                  return 10;
489  case GlobalValue::LinkOnceODRLinkage:              return 11;
490  case GlobalValue::AvailableExternallyLinkage:      return 12;
491  }
492  llvm_unreachable("Invalid linkage");
493}
494
495static unsigned getEncodedVisibility(const GlobalValue &GV) {
496  switch (GV.getVisibility()) {
497  case GlobalValue::DefaultVisibility:   return 0;
498  case GlobalValue::HiddenVisibility:    return 1;
499  case GlobalValue::ProtectedVisibility: return 2;
500  }
501  llvm_unreachable("Invalid visibility");
502}
503
504static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
505  switch (GV.getDLLStorageClass()) {
506  case GlobalValue::DefaultStorageClass:   return 0;
507  case GlobalValue::DLLImportStorageClass: return 1;
508  case GlobalValue::DLLExportStorageClass: return 2;
509  }
510  llvm_unreachable("Invalid DLL storage class");
511}
512
513static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
514  switch (GV.getThreadLocalMode()) {
515    case GlobalVariable::NotThreadLocal:         return 0;
516    case GlobalVariable::GeneralDynamicTLSModel: return 1;
517    case GlobalVariable::LocalDynamicTLSModel:   return 2;
518    case GlobalVariable::InitialExecTLSModel:    return 3;
519    case GlobalVariable::LocalExecTLSModel:      return 4;
520  }
521  llvm_unreachable("Invalid TLS model");
522}
523
524static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
525  switch (C.getSelectionKind()) {
526  case Comdat::Any:
527    return bitc::COMDAT_SELECTION_KIND_ANY;
528  case Comdat::ExactMatch:
529    return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
530  case Comdat::Largest:
531    return bitc::COMDAT_SELECTION_KIND_LARGEST;
532  case Comdat::NoDuplicates:
533    return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
534  case Comdat::SameSize:
535    return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
536  }
537  llvm_unreachable("Invalid selection kind");
538}
539
540static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
541  SmallVector<uint8_t, 64> Vals;
542  for (const Comdat *C : VE.getComdats()) {
543    // COMDAT: [selection_kind, name]
544    Vals.push_back(getEncodedComdatSelectionKind(*C));
545    Vals.push_back(C->getName().size());
546    for (char Chr : C->getName())
547      Vals.push_back((unsigned char)Chr);
548    Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
549    Vals.clear();
550  }
551}
552
553// Emit top-level description of module, including target triple, inline asm,
554// descriptors for global variables, and function prototype info.
555static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
556                            BitstreamWriter &Stream) {
557  // Emit various pieces of data attached to a module.
558  if (!M->getTargetTriple().empty())
559    WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
560                      0/*TODO*/, Stream);
561  const std::string &DL = M->getDataLayoutStr();
562  if (!DL.empty())
563    WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
564  if (!M->getModuleInlineAsm().empty())
565    WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
566                      0/*TODO*/, Stream);
567
568  // Emit information about sections and GC, computing how many there are. Also
569  // compute the maximum alignment value.
570  std::map<std::string, unsigned> SectionMap;
571  std::map<std::string, unsigned> GCMap;
572  unsigned MaxAlignment = 0;
573  unsigned MaxGlobalType = 0;
574  for (const GlobalValue &GV : M->globals()) {
575    MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
576    MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getType()));
577    if (GV.hasSection()) {
578      // Give section names unique ID's.
579      unsigned &Entry = SectionMap[GV.getSection()];
580      if (!Entry) {
581        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
582                          0/*TODO*/, Stream);
583        Entry = SectionMap.size();
584      }
585    }
586  }
587  for (const Function &F : *M) {
588    MaxAlignment = std::max(MaxAlignment, F.getAlignment());
589    if (F.hasSection()) {
590      // Give section names unique ID's.
591      unsigned &Entry = SectionMap[F.getSection()];
592      if (!Entry) {
593        WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
594                          0/*TODO*/, Stream);
595        Entry = SectionMap.size();
596      }
597    }
598    if (F.hasGC()) {
599      // Same for GC names.
600      unsigned &Entry = GCMap[F.getGC()];
601      if (!Entry) {
602        WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
603                          0/*TODO*/, Stream);
604        Entry = GCMap.size();
605      }
606    }
607  }
608
609  // Emit abbrev for globals, now that we know # sections and max alignment.
610  unsigned SimpleGVarAbbrev = 0;
611  if (!M->global_empty()) {
612    // Add an abbrev for common globals with no visibility or thread localness.
613    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
614    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
615    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
616                              Log2_32_Ceil(MaxGlobalType+1)));
617    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));      // Constant.
618    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));        // Initializer.
619    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));      // Linkage.
620    if (MaxAlignment == 0)                                      // Alignment.
621      Abbv->Add(BitCodeAbbrevOp(0));
622    else {
623      unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
624      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
625                               Log2_32_Ceil(MaxEncAlignment+1)));
626    }
627    if (SectionMap.empty())                                    // Section.
628      Abbv->Add(BitCodeAbbrevOp(0));
629    else
630      Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
631                               Log2_32_Ceil(SectionMap.size()+1)));
632    // Don't bother emitting vis + thread local.
633    SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
634  }
635
636  // Emit the global variable information.
637  SmallVector<unsigned, 64> Vals;
638  for (const GlobalVariable &GV : M->globals()) {
639    unsigned AbbrevToUse = 0;
640
641    // GLOBALVAR: [type, isconst, initid,
642    //             linkage, alignment, section, visibility, threadlocal,
643    //             unnamed_addr, externally_initialized, dllstorageclass]
644    Vals.push_back(VE.getTypeID(GV.getType()));
645    Vals.push_back(GV.isConstant());
646    Vals.push_back(GV.isDeclaration() ? 0 :
647                   (VE.getValueID(GV.getInitializer()) + 1));
648    Vals.push_back(getEncodedLinkage(GV));
649    Vals.push_back(Log2_32(GV.getAlignment())+1);
650    Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
651    if (GV.isThreadLocal() ||
652        GV.getVisibility() != GlobalValue::DefaultVisibility ||
653        GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
654        GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
655        GV.hasComdat()) {
656      Vals.push_back(getEncodedVisibility(GV));
657      Vals.push_back(getEncodedThreadLocalMode(GV));
658      Vals.push_back(GV.hasUnnamedAddr());
659      Vals.push_back(GV.isExternallyInitialized());
660      Vals.push_back(getEncodedDLLStorageClass(GV));
661      Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
662    } else {
663      AbbrevToUse = SimpleGVarAbbrev;
664    }
665
666    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
667    Vals.clear();
668  }
669
670  // Emit the function proto information.
671  for (const Function &F : *M) {
672    // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
673    //             section, visibility, gc, unnamed_addr, prefix]
674    Vals.push_back(VE.getTypeID(F.getType()));
675    Vals.push_back(F.getCallingConv());
676    Vals.push_back(F.isDeclaration());
677    Vals.push_back(getEncodedLinkage(F));
678    Vals.push_back(VE.getAttributeID(F.getAttributes()));
679    Vals.push_back(Log2_32(F.getAlignment())+1);
680    Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
681    Vals.push_back(getEncodedVisibility(F));
682    Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
683    Vals.push_back(F.hasUnnamedAddr());
684    Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
685                                      : 0);
686    Vals.push_back(getEncodedDLLStorageClass(F));
687    Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
688
689    unsigned AbbrevToUse = 0;
690    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
691    Vals.clear();
692  }
693
694  // Emit the alias information.
695  for (const GlobalAlias &A : M->aliases()) {
696    // ALIAS: [alias type, aliasee val#, linkage, visibility]
697    Vals.push_back(VE.getTypeID(A.getType()));
698    Vals.push_back(VE.getValueID(A.getAliasee()));
699    Vals.push_back(getEncodedLinkage(A));
700    Vals.push_back(getEncodedVisibility(A));
701    Vals.push_back(getEncodedDLLStorageClass(A));
702    Vals.push_back(getEncodedThreadLocalMode(A));
703    Vals.push_back(A.hasUnnamedAddr());
704    unsigned AbbrevToUse = 0;
705    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
706    Vals.clear();
707  }
708}
709
710static uint64_t GetOptimizationFlags(const Value *V) {
711  uint64_t Flags = 0;
712
713  if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
714    if (OBO->hasNoSignedWrap())
715      Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
716    if (OBO->hasNoUnsignedWrap())
717      Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
718  } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
719    if (PEO->isExact())
720      Flags |= 1 << bitc::PEO_EXACT;
721  } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
722    if (FPMO->hasUnsafeAlgebra())
723      Flags |= FastMathFlags::UnsafeAlgebra;
724    if (FPMO->hasNoNaNs())
725      Flags |= FastMathFlags::NoNaNs;
726    if (FPMO->hasNoInfs())
727      Flags |= FastMathFlags::NoInfs;
728    if (FPMO->hasNoSignedZeros())
729      Flags |= FastMathFlags::NoSignedZeros;
730    if (FPMO->hasAllowReciprocal())
731      Flags |= FastMathFlags::AllowReciprocal;
732  }
733
734  return Flags;
735}
736
737static void WriteMDNode(const MDNode *N,
738                        const ValueEnumerator &VE,
739                        BitstreamWriter &Stream,
740                        SmallVectorImpl<uint64_t> &Record) {
741  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
742    if (N->getOperand(i)) {
743      Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
744      Record.push_back(VE.getValueID(N->getOperand(i)));
745    } else {
746      Record.push_back(VE.getTypeID(Type::getVoidTy(N->getContext())));
747      Record.push_back(0);
748    }
749  }
750  unsigned MDCode = N->isFunctionLocal() ? bitc::METADATA_FN_NODE :
751                                           bitc::METADATA_NODE;
752  Stream.EmitRecord(MDCode, Record, 0);
753  Record.clear();
754}
755
756static void WriteModuleMetadata(const Module *M,
757                                const ValueEnumerator &VE,
758                                BitstreamWriter &Stream) {
759  const auto &Vals = VE.getMDValues();
760  bool StartedMetadataBlock = false;
761  unsigned MDSAbbrev = 0;
762  SmallVector<uint64_t, 64> Record;
763  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
764
765    if (const MDNode *N = dyn_cast<MDNode>(Vals[i])) {
766      if (!N->isFunctionLocal() || !N->getFunction()) {
767        if (!StartedMetadataBlock) {
768          Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
769          StartedMetadataBlock = true;
770        }
771        WriteMDNode(N, VE, Stream, Record);
772      }
773    } else if (const MDString *MDS = dyn_cast<MDString>(Vals[i])) {
774      if (!StartedMetadataBlock)  {
775        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
776
777        // Abbrev for METADATA_STRING.
778        BitCodeAbbrev *Abbv = new BitCodeAbbrev();
779        Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
780        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
781        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
782        MDSAbbrev = Stream.EmitAbbrev(Abbv);
783        StartedMetadataBlock = true;
784      }
785
786      // Code: [strchar x N]
787      Record.append(MDS->begin(), MDS->end());
788
789      // Emit the finished record.
790      Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
791      Record.clear();
792    }
793  }
794
795  // Write named metadata.
796  for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
797       E = M->named_metadata_end(); I != E; ++I) {
798    const NamedMDNode *NMD = I;
799    if (!StartedMetadataBlock)  {
800      Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
801      StartedMetadataBlock = true;
802    }
803
804    // Write name.
805    StringRef Str = NMD->getName();
806    for (unsigned i = 0, e = Str.size(); i != e; ++i)
807      Record.push_back(Str[i]);
808    Stream.EmitRecord(bitc::METADATA_NAME, Record, 0/*TODO*/);
809    Record.clear();
810
811    // Write named metadata operands.
812    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
813      Record.push_back(VE.getValueID(NMD->getOperand(i)));
814    Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
815    Record.clear();
816  }
817
818  if (StartedMetadataBlock)
819    Stream.ExitBlock();
820}
821
822static void WriteFunctionLocalMetadata(const Function &F,
823                                       const ValueEnumerator &VE,
824                                       BitstreamWriter &Stream) {
825  bool StartedMetadataBlock = false;
826  SmallVector<uint64_t, 64> Record;
827  const SmallVectorImpl<const MDNode *> &Vals = VE.getFunctionLocalMDValues();
828  for (unsigned i = 0, e = Vals.size(); i != e; ++i)
829    if (const MDNode *N = Vals[i])
830      if (N->isFunctionLocal() && N->getFunction() == &F) {
831        if (!StartedMetadataBlock) {
832          Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
833          StartedMetadataBlock = true;
834        }
835        WriteMDNode(N, VE, Stream, Record);
836      }
837
838  if (StartedMetadataBlock)
839    Stream.ExitBlock();
840}
841
842static void WriteMetadataAttachment(const Function &F,
843                                    const ValueEnumerator &VE,
844                                    BitstreamWriter &Stream) {
845  Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
846
847  SmallVector<uint64_t, 64> Record;
848
849  // Write metadata attachments
850  // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
851  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
852
853  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
854    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
855         I != E; ++I) {
856      MDs.clear();
857      I->getAllMetadataOtherThanDebugLoc(MDs);
858
859      // If no metadata, ignore instruction.
860      if (MDs.empty()) continue;
861
862      Record.push_back(VE.getInstructionID(I));
863
864      for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
865        Record.push_back(MDs[i].first);
866        Record.push_back(VE.getValueID(MDs[i].second));
867      }
868      Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
869      Record.clear();
870    }
871
872  Stream.ExitBlock();
873}
874
875static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
876  SmallVector<uint64_t, 64> Record;
877
878  // Write metadata kinds
879  // METADATA_KIND - [n x [id, name]]
880  SmallVector<StringRef, 8> Names;
881  M->getMDKindNames(Names);
882
883  if (Names.empty()) return;
884
885  Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
886
887  for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
888    Record.push_back(MDKindID);
889    StringRef KName = Names[MDKindID];
890    Record.append(KName.begin(), KName.end());
891
892    Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
893    Record.clear();
894  }
895
896  Stream.ExitBlock();
897}
898
899static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
900  if ((int64_t)V >= 0)
901    Vals.push_back(V << 1);
902  else
903    Vals.push_back((-V << 1) | 1);
904}
905
906static void WriteConstants(unsigned FirstVal, unsigned LastVal,
907                           const ValueEnumerator &VE,
908                           BitstreamWriter &Stream, bool isGlobal) {
909  if (FirstVal == LastVal) return;
910
911  Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
912
913  unsigned AggregateAbbrev = 0;
914  unsigned String8Abbrev = 0;
915  unsigned CString7Abbrev = 0;
916  unsigned CString6Abbrev = 0;
917  // If this is a constant pool for the module, emit module-specific abbrevs.
918  if (isGlobal) {
919    // Abbrev for CST_CODE_AGGREGATE.
920    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
921    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
922    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
923    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
924    AggregateAbbrev = Stream.EmitAbbrev(Abbv);
925
926    // Abbrev for CST_CODE_STRING.
927    Abbv = new BitCodeAbbrev();
928    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
929    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
930    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
931    String8Abbrev = Stream.EmitAbbrev(Abbv);
932    // Abbrev for CST_CODE_CSTRING.
933    Abbv = new BitCodeAbbrev();
934    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
935    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
936    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
937    CString7Abbrev = Stream.EmitAbbrev(Abbv);
938    // Abbrev for CST_CODE_CSTRING.
939    Abbv = new BitCodeAbbrev();
940    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
941    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
942    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
943    CString6Abbrev = Stream.EmitAbbrev(Abbv);
944  }
945
946  SmallVector<uint64_t, 64> Record;
947
948  const ValueEnumerator::ValueList &Vals = VE.getValues();
949  Type *LastTy = nullptr;
950  for (unsigned i = FirstVal; i != LastVal; ++i) {
951    const Value *V = Vals[i].first;
952    // If we need to switch types, do so now.
953    if (V->getType() != LastTy) {
954      LastTy = V->getType();
955      Record.push_back(VE.getTypeID(LastTy));
956      Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
957                        CONSTANTS_SETTYPE_ABBREV);
958      Record.clear();
959    }
960
961    if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
962      Record.push_back(unsigned(IA->hasSideEffects()) |
963                       unsigned(IA->isAlignStack()) << 1 |
964                       unsigned(IA->getDialect()&1) << 2);
965
966      // Add the asm string.
967      const std::string &AsmStr = IA->getAsmString();
968      Record.push_back(AsmStr.size());
969      for (unsigned i = 0, e = AsmStr.size(); i != e; ++i)
970        Record.push_back(AsmStr[i]);
971
972      // Add the constraint string.
973      const std::string &ConstraintStr = IA->getConstraintString();
974      Record.push_back(ConstraintStr.size());
975      for (unsigned i = 0, e = ConstraintStr.size(); i != e; ++i)
976        Record.push_back(ConstraintStr[i]);
977      Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
978      Record.clear();
979      continue;
980    }
981    const Constant *C = cast<Constant>(V);
982    unsigned Code = -1U;
983    unsigned AbbrevToUse = 0;
984    if (C->isNullValue()) {
985      Code = bitc::CST_CODE_NULL;
986    } else if (isa<UndefValue>(C)) {
987      Code = bitc::CST_CODE_UNDEF;
988    } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
989      if (IV->getBitWidth() <= 64) {
990        uint64_t V = IV->getSExtValue();
991        emitSignedInt64(Record, V);
992        Code = bitc::CST_CODE_INTEGER;
993        AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
994      } else {                             // Wide integers, > 64 bits in size.
995        // We have an arbitrary precision integer value to write whose
996        // bit width is > 64. However, in canonical unsigned integer
997        // format it is likely that the high bits are going to be zero.
998        // So, we only write the number of active words.
999        unsigned NWords = IV->getValue().getActiveWords();
1000        const uint64_t *RawWords = IV->getValue().getRawData();
1001        for (unsigned i = 0; i != NWords; ++i) {
1002          emitSignedInt64(Record, RawWords[i]);
1003        }
1004        Code = bitc::CST_CODE_WIDE_INTEGER;
1005      }
1006    } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1007      Code = bitc::CST_CODE_FLOAT;
1008      Type *Ty = CFP->getType();
1009      if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1010        Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1011      } else if (Ty->isX86_FP80Ty()) {
1012        // api needed to prevent premature destruction
1013        // bits are not in the same order as a normal i80 APInt, compensate.
1014        APInt api = CFP->getValueAPF().bitcastToAPInt();
1015        const uint64_t *p = api.getRawData();
1016        Record.push_back((p[1] << 48) | (p[0] >> 16));
1017        Record.push_back(p[0] & 0xffffLL);
1018      } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1019        APInt api = CFP->getValueAPF().bitcastToAPInt();
1020        const uint64_t *p = api.getRawData();
1021        Record.push_back(p[0]);
1022        Record.push_back(p[1]);
1023      } else {
1024        assert (0 && "Unknown FP type!");
1025      }
1026    } else if (isa<ConstantDataSequential>(C) &&
1027               cast<ConstantDataSequential>(C)->isString()) {
1028      const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1029      // Emit constant strings specially.
1030      unsigned NumElts = Str->getNumElements();
1031      // If this is a null-terminated string, use the denser CSTRING encoding.
1032      if (Str->isCString()) {
1033        Code = bitc::CST_CODE_CSTRING;
1034        --NumElts;  // Don't encode the null, which isn't allowed by char6.
1035      } else {
1036        Code = bitc::CST_CODE_STRING;
1037        AbbrevToUse = String8Abbrev;
1038      }
1039      bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1040      bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1041      for (unsigned i = 0; i != NumElts; ++i) {
1042        unsigned char V = Str->getElementAsInteger(i);
1043        Record.push_back(V);
1044        isCStr7 &= (V & 128) == 0;
1045        if (isCStrChar6)
1046          isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1047      }
1048
1049      if (isCStrChar6)
1050        AbbrevToUse = CString6Abbrev;
1051      else if (isCStr7)
1052        AbbrevToUse = CString7Abbrev;
1053    } else if (const ConstantDataSequential *CDS =
1054                  dyn_cast<ConstantDataSequential>(C)) {
1055      Code = bitc::CST_CODE_DATA;
1056      Type *EltTy = CDS->getType()->getElementType();
1057      if (isa<IntegerType>(EltTy)) {
1058        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1059          Record.push_back(CDS->getElementAsInteger(i));
1060      } else if (EltTy->isFloatTy()) {
1061        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1062          union { float F; uint32_t I; };
1063          F = CDS->getElementAsFloat(i);
1064          Record.push_back(I);
1065        }
1066      } else {
1067        assert(EltTy->isDoubleTy() && "Unknown ConstantData element type");
1068        for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1069          union { double F; uint64_t I; };
1070          F = CDS->getElementAsDouble(i);
1071          Record.push_back(I);
1072        }
1073      }
1074    } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1075               isa<ConstantVector>(C)) {
1076      Code = bitc::CST_CODE_AGGREGATE;
1077      for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
1078        Record.push_back(VE.getValueID(C->getOperand(i)));
1079      AbbrevToUse = AggregateAbbrev;
1080    } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1081      switch (CE->getOpcode()) {
1082      default:
1083        if (Instruction::isCast(CE->getOpcode())) {
1084          Code = bitc::CST_CODE_CE_CAST;
1085          Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1086          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1087          Record.push_back(VE.getValueID(C->getOperand(0)));
1088          AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1089        } else {
1090          assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1091          Code = bitc::CST_CODE_CE_BINOP;
1092          Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1093          Record.push_back(VE.getValueID(C->getOperand(0)));
1094          Record.push_back(VE.getValueID(C->getOperand(1)));
1095          uint64_t Flags = GetOptimizationFlags(CE);
1096          if (Flags != 0)
1097            Record.push_back(Flags);
1098        }
1099        break;
1100      case Instruction::GetElementPtr:
1101        Code = bitc::CST_CODE_CE_GEP;
1102        if (cast<GEPOperator>(C)->isInBounds())
1103          Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1104        for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1105          Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1106          Record.push_back(VE.getValueID(C->getOperand(i)));
1107        }
1108        break;
1109      case Instruction::Select:
1110        Code = bitc::CST_CODE_CE_SELECT;
1111        Record.push_back(VE.getValueID(C->getOperand(0)));
1112        Record.push_back(VE.getValueID(C->getOperand(1)));
1113        Record.push_back(VE.getValueID(C->getOperand(2)));
1114        break;
1115      case Instruction::ExtractElement:
1116        Code = bitc::CST_CODE_CE_EXTRACTELT;
1117        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1118        Record.push_back(VE.getValueID(C->getOperand(0)));
1119        Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1120        Record.push_back(VE.getValueID(C->getOperand(1)));
1121        break;
1122      case Instruction::InsertElement:
1123        Code = bitc::CST_CODE_CE_INSERTELT;
1124        Record.push_back(VE.getValueID(C->getOperand(0)));
1125        Record.push_back(VE.getValueID(C->getOperand(1)));
1126        Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1127        Record.push_back(VE.getValueID(C->getOperand(2)));
1128        break;
1129      case Instruction::ShuffleVector:
1130        // If the return type and argument types are the same, this is a
1131        // standard shufflevector instruction.  If the types are different,
1132        // then the shuffle is widening or truncating the input vectors, and
1133        // the argument type must also be encoded.
1134        if (C->getType() == C->getOperand(0)->getType()) {
1135          Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1136        } else {
1137          Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1138          Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1139        }
1140        Record.push_back(VE.getValueID(C->getOperand(0)));
1141        Record.push_back(VE.getValueID(C->getOperand(1)));
1142        Record.push_back(VE.getValueID(C->getOperand(2)));
1143        break;
1144      case Instruction::ICmp:
1145      case Instruction::FCmp:
1146        Code = bitc::CST_CODE_CE_CMP;
1147        Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1148        Record.push_back(VE.getValueID(C->getOperand(0)));
1149        Record.push_back(VE.getValueID(C->getOperand(1)));
1150        Record.push_back(CE->getPredicate());
1151        break;
1152      }
1153    } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1154      Code = bitc::CST_CODE_BLOCKADDRESS;
1155      Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1156      Record.push_back(VE.getValueID(BA->getFunction()));
1157      Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1158    } else {
1159#ifndef NDEBUG
1160      C->dump();
1161#endif
1162      llvm_unreachable("Unknown constant!");
1163    }
1164    Stream.EmitRecord(Code, Record, AbbrevToUse);
1165    Record.clear();
1166  }
1167
1168  Stream.ExitBlock();
1169}
1170
1171static void WriteModuleConstants(const ValueEnumerator &VE,
1172                                 BitstreamWriter &Stream) {
1173  const ValueEnumerator::ValueList &Vals = VE.getValues();
1174
1175  // Find the first constant to emit, which is the first non-globalvalue value.
1176  // We know globalvalues have been emitted by WriteModuleInfo.
1177  for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1178    if (!isa<GlobalValue>(Vals[i].first)) {
1179      WriteConstants(i, Vals.size(), VE, Stream, true);
1180      return;
1181    }
1182  }
1183}
1184
1185/// PushValueAndType - The file has to encode both the value and type id for
1186/// many values, because we need to know what type to create for forward
1187/// references.  However, most operands are not forward references, so this type
1188/// field is not needed.
1189///
1190/// This function adds V's value ID to Vals.  If the value ID is higher than the
1191/// instruction ID, then it is a forward reference, and it also includes the
1192/// type ID.  The value ID that is written is encoded relative to the InstID.
1193static bool PushValueAndType(const Value *V, unsigned InstID,
1194                             SmallVectorImpl<unsigned> &Vals,
1195                             ValueEnumerator &VE) {
1196  unsigned ValID = VE.getValueID(V);
1197  // Make encoding relative to the InstID.
1198  Vals.push_back(InstID - ValID);
1199  if (ValID >= InstID) {
1200    Vals.push_back(VE.getTypeID(V->getType()));
1201    return true;
1202  }
1203  return false;
1204}
1205
1206/// pushValue - Like PushValueAndType, but where the type of the value is
1207/// omitted (perhaps it was already encoded in an earlier operand).
1208static void pushValue(const Value *V, unsigned InstID,
1209                      SmallVectorImpl<unsigned> &Vals,
1210                      ValueEnumerator &VE) {
1211  unsigned ValID = VE.getValueID(V);
1212  Vals.push_back(InstID - ValID);
1213}
1214
1215static void pushValueSigned(const Value *V, unsigned InstID,
1216                            SmallVectorImpl<uint64_t> &Vals,
1217                            ValueEnumerator &VE) {
1218  unsigned ValID = VE.getValueID(V);
1219  int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1220  emitSignedInt64(Vals, diff);
1221}
1222
1223/// WriteInstruction - Emit an instruction to the specified stream.
1224static void WriteInstruction(const Instruction &I, unsigned InstID,
1225                             ValueEnumerator &VE, BitstreamWriter &Stream,
1226                             SmallVectorImpl<unsigned> &Vals) {
1227  unsigned Code = 0;
1228  unsigned AbbrevToUse = 0;
1229  VE.setInstructionID(&I);
1230  switch (I.getOpcode()) {
1231  default:
1232    if (Instruction::isCast(I.getOpcode())) {
1233      Code = bitc::FUNC_CODE_INST_CAST;
1234      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1235        AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1236      Vals.push_back(VE.getTypeID(I.getType()));
1237      Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1238    } else {
1239      assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1240      Code = bitc::FUNC_CODE_INST_BINOP;
1241      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1242        AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1243      pushValue(I.getOperand(1), InstID, Vals, VE);
1244      Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1245      uint64_t Flags = GetOptimizationFlags(&I);
1246      if (Flags != 0) {
1247        if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1248          AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1249        Vals.push_back(Flags);
1250      }
1251    }
1252    break;
1253
1254  case Instruction::GetElementPtr:
1255    Code = bitc::FUNC_CODE_INST_GEP;
1256    if (cast<GEPOperator>(&I)->isInBounds())
1257      Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
1258    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1259      PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1260    break;
1261  case Instruction::ExtractValue: {
1262    Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1263    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1264    const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1265    for (const unsigned *i = EVI->idx_begin(), *e = EVI->idx_end(); i != e; ++i)
1266      Vals.push_back(*i);
1267    break;
1268  }
1269  case Instruction::InsertValue: {
1270    Code = bitc::FUNC_CODE_INST_INSERTVAL;
1271    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1272    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1273    const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1274    for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
1275      Vals.push_back(*i);
1276    break;
1277  }
1278  case Instruction::Select:
1279    Code = bitc::FUNC_CODE_INST_VSELECT;
1280    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1281    pushValue(I.getOperand(2), InstID, Vals, VE);
1282    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1283    break;
1284  case Instruction::ExtractElement:
1285    Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1286    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1287    PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1288    break;
1289  case Instruction::InsertElement:
1290    Code = bitc::FUNC_CODE_INST_INSERTELT;
1291    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1292    pushValue(I.getOperand(1), InstID, Vals, VE);
1293    PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1294    break;
1295  case Instruction::ShuffleVector:
1296    Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1297    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1298    pushValue(I.getOperand(1), InstID, Vals, VE);
1299    pushValue(I.getOperand(2), InstID, Vals, VE);
1300    break;
1301  case Instruction::ICmp:
1302  case Instruction::FCmp:
1303    // compare returning Int1Ty or vector of Int1Ty
1304    Code = bitc::FUNC_CODE_INST_CMP2;
1305    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1306    pushValue(I.getOperand(1), InstID, Vals, VE);
1307    Vals.push_back(cast<CmpInst>(I).getPredicate());
1308    break;
1309
1310  case Instruction::Ret:
1311    {
1312      Code = bitc::FUNC_CODE_INST_RET;
1313      unsigned NumOperands = I.getNumOperands();
1314      if (NumOperands == 0)
1315        AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1316      else if (NumOperands == 1) {
1317        if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1318          AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1319      } else {
1320        for (unsigned i = 0, e = NumOperands; i != e; ++i)
1321          PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1322      }
1323    }
1324    break;
1325  case Instruction::Br:
1326    {
1327      Code = bitc::FUNC_CODE_INST_BR;
1328      const BranchInst &II = cast<BranchInst>(I);
1329      Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1330      if (II.isConditional()) {
1331        Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1332        pushValue(II.getCondition(), InstID, Vals, VE);
1333      }
1334    }
1335    break;
1336  case Instruction::Switch:
1337    {
1338      Code = bitc::FUNC_CODE_INST_SWITCH;
1339      const SwitchInst &SI = cast<SwitchInst>(I);
1340      Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1341      pushValue(SI.getCondition(), InstID, Vals, VE);
1342      Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1343      for (SwitchInst::ConstCaseIt i = SI.case_begin(), e = SI.case_end();
1344           i != e; ++i) {
1345        Vals.push_back(VE.getValueID(i.getCaseValue()));
1346        Vals.push_back(VE.getValueID(i.getCaseSuccessor()));
1347      }
1348    }
1349    break;
1350  case Instruction::IndirectBr:
1351    Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1352    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1353    // Encode the address operand as relative, but not the basic blocks.
1354    pushValue(I.getOperand(0), InstID, Vals, VE);
1355    for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1356      Vals.push_back(VE.getValueID(I.getOperand(i)));
1357    break;
1358
1359  case Instruction::Invoke: {
1360    const InvokeInst *II = cast<InvokeInst>(&I);
1361    const Value *Callee(II->getCalledValue());
1362    PointerType *PTy = cast<PointerType>(Callee->getType());
1363    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1364    Code = bitc::FUNC_CODE_INST_INVOKE;
1365
1366    Vals.push_back(VE.getAttributeID(II->getAttributes()));
1367    Vals.push_back(II->getCallingConv());
1368    Vals.push_back(VE.getValueID(II->getNormalDest()));
1369    Vals.push_back(VE.getValueID(II->getUnwindDest()));
1370    PushValueAndType(Callee, InstID, Vals, VE);
1371
1372    // Emit value #'s for the fixed parameters.
1373    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
1374      pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
1375
1376    // Emit type/value pairs for varargs params.
1377    if (FTy->isVarArg()) {
1378      for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
1379           i != e; ++i)
1380        PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
1381    }
1382    break;
1383  }
1384  case Instruction::Resume:
1385    Code = bitc::FUNC_CODE_INST_RESUME;
1386    PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1387    break;
1388  case Instruction::Unreachable:
1389    Code = bitc::FUNC_CODE_INST_UNREACHABLE;
1390    AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
1391    break;
1392
1393  case Instruction::PHI: {
1394    const PHINode &PN = cast<PHINode>(I);
1395    Code = bitc::FUNC_CODE_INST_PHI;
1396    // With the newer instruction encoding, forward references could give
1397    // negative valued IDs.  This is most common for PHIs, so we use
1398    // signed VBRs.
1399    SmallVector<uint64_t, 128> Vals64;
1400    Vals64.push_back(VE.getTypeID(PN.getType()));
1401    for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
1402      pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
1403      Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
1404    }
1405    // Emit a Vals64 vector and exit.
1406    Stream.EmitRecord(Code, Vals64, AbbrevToUse);
1407    Vals64.clear();
1408    return;
1409  }
1410
1411  case Instruction::LandingPad: {
1412    const LandingPadInst &LP = cast<LandingPadInst>(I);
1413    Code = bitc::FUNC_CODE_INST_LANDINGPAD;
1414    Vals.push_back(VE.getTypeID(LP.getType()));
1415    PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
1416    Vals.push_back(LP.isCleanup());
1417    Vals.push_back(LP.getNumClauses());
1418    for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
1419      if (LP.isCatch(I))
1420        Vals.push_back(LandingPadInst::Catch);
1421      else
1422        Vals.push_back(LandingPadInst::Filter);
1423      PushValueAndType(LP.getClause(I), InstID, Vals, VE);
1424    }
1425    break;
1426  }
1427
1428  case Instruction::Alloca: {
1429    Code = bitc::FUNC_CODE_INST_ALLOCA;
1430    Vals.push_back(VE.getTypeID(I.getType()));
1431    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1432    Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
1433    const AllocaInst &AI = cast<AllocaInst>(I);
1434    unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
1435    assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
1436           "not enough bits for maximum alignment");
1437    assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
1438    AlignRecord |= AI.isUsedWithInAlloca() << 5;
1439    Vals.push_back(AlignRecord);
1440    break;
1441  }
1442
1443  case Instruction::Load:
1444    if (cast<LoadInst>(I).isAtomic()) {
1445      Code = bitc::FUNC_CODE_INST_LOADATOMIC;
1446      PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1447    } else {
1448      Code = bitc::FUNC_CODE_INST_LOAD;
1449      if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
1450        AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
1451    }
1452    Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
1453    Vals.push_back(cast<LoadInst>(I).isVolatile());
1454    if (cast<LoadInst>(I).isAtomic()) {
1455      Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
1456      Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
1457    }
1458    break;
1459  case Instruction::Store:
1460    if (cast<StoreInst>(I).isAtomic())
1461      Code = bitc::FUNC_CODE_INST_STOREATOMIC;
1462    else
1463      Code = bitc::FUNC_CODE_INST_STORE;
1464    PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
1465    pushValue(I.getOperand(0), InstID, Vals, VE);         // val.
1466    Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
1467    Vals.push_back(cast<StoreInst>(I).isVolatile());
1468    if (cast<StoreInst>(I).isAtomic()) {
1469      Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
1470      Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
1471    }
1472    break;
1473  case Instruction::AtomicCmpXchg:
1474    Code = bitc::FUNC_CODE_INST_CMPXCHG;
1475    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1476    pushValue(I.getOperand(1), InstID, Vals, VE);         // cmp.
1477    pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
1478    Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
1479    Vals.push_back(GetEncodedOrdering(
1480                     cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
1481    Vals.push_back(GetEncodedSynchScope(
1482                     cast<AtomicCmpXchgInst>(I).getSynchScope()));
1483    Vals.push_back(GetEncodedOrdering(
1484                     cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
1485    Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
1486    break;
1487  case Instruction::AtomicRMW:
1488    Code = bitc::FUNC_CODE_INST_ATOMICRMW;
1489    PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
1490    pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
1491    Vals.push_back(GetEncodedRMWOperation(
1492                     cast<AtomicRMWInst>(I).getOperation()));
1493    Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
1494    Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
1495    Vals.push_back(GetEncodedSynchScope(
1496                     cast<AtomicRMWInst>(I).getSynchScope()));
1497    break;
1498  case Instruction::Fence:
1499    Code = bitc::FUNC_CODE_INST_FENCE;
1500    Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
1501    Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
1502    break;
1503  case Instruction::Call: {
1504    const CallInst &CI = cast<CallInst>(I);
1505    PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
1506    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1507
1508    Code = bitc::FUNC_CODE_INST_CALL;
1509
1510    Vals.push_back(VE.getAttributeID(CI.getAttributes()));
1511    Vals.push_back((CI.getCallingConv() << 1) | unsigned(CI.isTailCall()) |
1512                   unsigned(CI.isMustTailCall()) << 14);
1513    PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
1514
1515    // Emit value #'s for the fixed parameters.
1516    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
1517      // Check for labels (can happen with asm labels).
1518      if (FTy->getParamType(i)->isLabelTy())
1519        Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
1520      else
1521        pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
1522    }
1523
1524    // Emit type/value pairs for varargs params.
1525    if (FTy->isVarArg()) {
1526      for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
1527           i != e; ++i)
1528        PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
1529    }
1530    break;
1531  }
1532  case Instruction::VAArg:
1533    Code = bitc::FUNC_CODE_INST_VAARG;
1534    Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
1535    pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
1536    Vals.push_back(VE.getTypeID(I.getType())); // restype.
1537    break;
1538  }
1539
1540  Stream.EmitRecord(Code, Vals, AbbrevToUse);
1541  Vals.clear();
1542}
1543
1544// Emit names for globals/functions etc.
1545static void WriteValueSymbolTable(const ValueSymbolTable &VST,
1546                                  const ValueEnumerator &VE,
1547                                  BitstreamWriter &Stream) {
1548  if (VST.empty()) return;
1549  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
1550
1551  // FIXME: Set up the abbrev, we know how many values there are!
1552  // FIXME: We know if the type names can use 7-bit ascii.
1553  SmallVector<unsigned, 64> NameVals;
1554
1555  for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
1556       SI != SE; ++SI) {
1557
1558    const ValueName &Name = *SI;
1559
1560    // Figure out the encoding to use for the name.
1561    bool is7Bit = true;
1562    bool isChar6 = true;
1563    for (const char *C = Name.getKeyData(), *E = C+Name.getKeyLength();
1564         C != E; ++C) {
1565      if (isChar6)
1566        isChar6 = BitCodeAbbrevOp::isChar6(*C);
1567      if ((unsigned char)*C & 128) {
1568        is7Bit = false;
1569        break;  // don't bother scanning the rest.
1570      }
1571    }
1572
1573    unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
1574
1575    // VST_ENTRY:   [valueid, namechar x N]
1576    // VST_BBENTRY: [bbid, namechar x N]
1577    unsigned Code;
1578    if (isa<BasicBlock>(SI->getValue())) {
1579      Code = bitc::VST_CODE_BBENTRY;
1580      if (isChar6)
1581        AbbrevToUse = VST_BBENTRY_6_ABBREV;
1582    } else {
1583      Code = bitc::VST_CODE_ENTRY;
1584      if (isChar6)
1585        AbbrevToUse = VST_ENTRY_6_ABBREV;
1586      else if (is7Bit)
1587        AbbrevToUse = VST_ENTRY_7_ABBREV;
1588    }
1589
1590    NameVals.push_back(VE.getValueID(SI->getValue()));
1591    for (const char *P = Name.getKeyData(),
1592         *E = Name.getKeyData()+Name.getKeyLength(); P != E; ++P)
1593      NameVals.push_back((unsigned char)*P);
1594
1595    // Emit the finished record.
1596    Stream.EmitRecord(Code, NameVals, AbbrevToUse);
1597    NameVals.clear();
1598  }
1599  Stream.ExitBlock();
1600}
1601
1602static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
1603                         BitstreamWriter &Stream) {
1604  assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
1605  unsigned Code;
1606  if (isa<BasicBlock>(Order.V))
1607    Code = bitc::USELIST_CODE_BB;
1608  else
1609    Code = bitc::USELIST_CODE_DEFAULT;
1610
1611  SmallVector<uint64_t, 64> Record;
1612  for (unsigned I : Order.Shuffle)
1613    Record.push_back(I);
1614  Record.push_back(VE.getValueID(Order.V));
1615  Stream.EmitRecord(Code, Record);
1616}
1617
1618static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
1619                              BitstreamWriter &Stream) {
1620  auto hasMore = [&]() {
1621    return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
1622  };
1623  if (!hasMore())
1624    // Nothing to do.
1625    return;
1626
1627  Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
1628  while (hasMore()) {
1629    WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
1630    VE.UseListOrders.pop_back();
1631  }
1632  Stream.ExitBlock();
1633}
1634
1635/// WriteFunction - Emit a function body to the module stream.
1636static void WriteFunction(const Function &F, ValueEnumerator &VE,
1637                          BitstreamWriter &Stream) {
1638  Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
1639  VE.incorporateFunction(F);
1640
1641  SmallVector<unsigned, 64> Vals;
1642
1643  // Emit the number of basic blocks, so the reader can create them ahead of
1644  // time.
1645  Vals.push_back(VE.getBasicBlocks().size());
1646  Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
1647  Vals.clear();
1648
1649  // If there are function-local constants, emit them now.
1650  unsigned CstStart, CstEnd;
1651  VE.getFunctionConstantRange(CstStart, CstEnd);
1652  WriteConstants(CstStart, CstEnd, VE, Stream, false);
1653
1654  // If there is function-local metadata, emit it now.
1655  WriteFunctionLocalMetadata(F, VE, Stream);
1656
1657  // Keep a running idea of what the instruction ID is.
1658  unsigned InstID = CstEnd;
1659
1660  bool NeedsMetadataAttachment = false;
1661
1662  DebugLoc LastDL;
1663
1664  // Finally, emit all the instructions, in order.
1665  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
1666    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
1667         I != E; ++I) {
1668      WriteInstruction(*I, InstID, VE, Stream, Vals);
1669
1670      if (!I->getType()->isVoidTy())
1671        ++InstID;
1672
1673      // If the instruction has metadata, write a metadata attachment later.
1674      NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
1675
1676      // If the instruction has a debug location, emit it.
1677      DebugLoc DL = I->getDebugLoc();
1678      if (DL.isUnknown()) {
1679        // nothing todo.
1680      } else if (DL == LastDL) {
1681        // Just repeat the same debug loc as last time.
1682        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
1683      } else {
1684        MDNode *Scope, *IA;
1685        DL.getScopeAndInlinedAt(Scope, IA, I->getContext());
1686
1687        Vals.push_back(DL.getLine());
1688        Vals.push_back(DL.getCol());
1689        Vals.push_back(Scope ? VE.getValueID(Scope)+1 : 0);
1690        Vals.push_back(IA ? VE.getValueID(IA)+1 : 0);
1691        Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
1692        Vals.clear();
1693
1694        LastDL = DL;
1695      }
1696    }
1697
1698  // Emit names for all the instructions etc.
1699  WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
1700
1701  if (NeedsMetadataAttachment)
1702    WriteMetadataAttachment(F, VE, Stream);
1703  if (shouldPreserveBitcodeUseListOrder())
1704    WriteUseListBlock(&F, VE, Stream);
1705  VE.purgeFunction();
1706  Stream.ExitBlock();
1707}
1708
1709// Emit blockinfo, which defines the standard abbreviations etc.
1710static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
1711  // We only want to emit block info records for blocks that have multiple
1712  // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
1713  // Other blocks can define their abbrevs inline.
1714  Stream.EnterBlockInfoBlock(2);
1715
1716  { // 8-bit fixed-width VST_ENTRY/VST_BBENTRY strings.
1717    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1718    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
1719    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1720    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1721    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1722    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1723                                   Abbv) != VST_ENTRY_8_ABBREV)
1724      llvm_unreachable("Unexpected abbrev ordering!");
1725  }
1726
1727  { // 7-bit fixed width VST_ENTRY strings.
1728    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1729    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1730    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1731    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1732    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1733    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1734                                   Abbv) != VST_ENTRY_7_ABBREV)
1735      llvm_unreachable("Unexpected abbrev ordering!");
1736  }
1737  { // 6-bit char6 VST_ENTRY strings.
1738    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1739    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
1740    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1741    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1742    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1743    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1744                                   Abbv) != VST_ENTRY_6_ABBREV)
1745      llvm_unreachable("Unexpected abbrev ordering!");
1746  }
1747  { // 6-bit char6 VST_BBENTRY strings.
1748    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1749    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
1750    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1751    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1752    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1753    if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
1754                                   Abbv) != VST_BBENTRY_6_ABBREV)
1755      llvm_unreachable("Unexpected abbrev ordering!");
1756  }
1757
1758
1759
1760  { // SETTYPE abbrev for CONSTANTS_BLOCK.
1761    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1762    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
1763    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1764                              Log2_32_Ceil(VE.getTypes().size()+1)));
1765    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1766                                   Abbv) != CONSTANTS_SETTYPE_ABBREV)
1767      llvm_unreachable("Unexpected abbrev ordering!");
1768  }
1769
1770  { // INTEGER abbrev for CONSTANTS_BLOCK.
1771    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1772    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
1773    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1774    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1775                                   Abbv) != CONSTANTS_INTEGER_ABBREV)
1776      llvm_unreachable("Unexpected abbrev ordering!");
1777  }
1778
1779  { // CE_CAST abbrev for CONSTANTS_BLOCK.
1780    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1781    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
1782    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
1783    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
1784                              Log2_32_Ceil(VE.getTypes().size()+1)));
1785    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
1786
1787    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1788                                   Abbv) != CONSTANTS_CE_CAST_Abbrev)
1789      llvm_unreachable("Unexpected abbrev ordering!");
1790  }
1791  { // NULL abbrev for CONSTANTS_BLOCK.
1792    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1793    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
1794    if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
1795                                   Abbv) != CONSTANTS_NULL_Abbrev)
1796      llvm_unreachable("Unexpected abbrev ordering!");
1797  }
1798
1799  // FIXME: This should only use space for first class types!
1800
1801  { // INST_LOAD abbrev for FUNCTION_BLOCK.
1802    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1803    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
1804    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
1805    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
1806    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
1807    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1808                                   Abbv) != FUNCTION_INST_LOAD_ABBREV)
1809      llvm_unreachable("Unexpected abbrev ordering!");
1810  }
1811  { // INST_BINOP abbrev for FUNCTION_BLOCK.
1812    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1813    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1814    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1815    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1816    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1817    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1818                                   Abbv) != FUNCTION_INST_BINOP_ABBREV)
1819      llvm_unreachable("Unexpected abbrev ordering!");
1820  }
1821  { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
1822    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1823    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
1824    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
1825    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
1826    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
1827    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
1828    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1829                                   Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
1830      llvm_unreachable("Unexpected abbrev ordering!");
1831  }
1832  { // INST_CAST abbrev for FUNCTION_BLOCK.
1833    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1834    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
1835    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
1836    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
1837                              Log2_32_Ceil(VE.getTypes().size()+1)));
1838    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
1839    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1840                                   Abbv) != FUNCTION_INST_CAST_ABBREV)
1841      llvm_unreachable("Unexpected abbrev ordering!");
1842  }
1843
1844  { // INST_RET abbrev for FUNCTION_BLOCK.
1845    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1846    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1847    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1848                                   Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
1849      llvm_unreachable("Unexpected abbrev ordering!");
1850  }
1851  { // INST_RET abbrev for FUNCTION_BLOCK.
1852    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1853    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
1854    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
1855    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1856                                   Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
1857      llvm_unreachable("Unexpected abbrev ordering!");
1858  }
1859  { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
1860    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1861    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
1862    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
1863                                   Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
1864      llvm_unreachable("Unexpected abbrev ordering!");
1865  }
1866
1867  Stream.ExitBlock();
1868}
1869
1870/// WriteModule - Emit the specified module to the bitstream.
1871static void WriteModule(const Module *M, BitstreamWriter &Stream) {
1872  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
1873
1874  SmallVector<unsigned, 1> Vals;
1875  unsigned CurVersion = 1;
1876  Vals.push_back(CurVersion);
1877  Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
1878
1879  // Analyze the module, enumerating globals, functions, etc.
1880  ValueEnumerator VE(*M);
1881
1882  // Emit blockinfo, which defines the standard abbreviations etc.
1883  WriteBlockInfo(VE, Stream);
1884
1885  // Emit information about attribute groups.
1886  WriteAttributeGroupTable(VE, Stream);
1887
1888  // Emit information about parameter attributes.
1889  WriteAttributeTable(VE, Stream);
1890
1891  // Emit information describing all of the types in the module.
1892  WriteTypeTable(VE, Stream);
1893
1894  writeComdats(VE, Stream);
1895
1896  // Emit top-level description of module, including target triple, inline asm,
1897  // descriptors for global variables, and function prototype info.
1898  WriteModuleInfo(M, VE, Stream);
1899
1900  // Emit constants.
1901  WriteModuleConstants(VE, Stream);
1902
1903  // Emit metadata.
1904  WriteModuleMetadata(M, VE, Stream);
1905
1906  // Emit metadata.
1907  WriteModuleMetadataStore(M, Stream);
1908
1909  // Emit names for globals/functions etc.
1910  WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
1911
1912  // Emit module-level use-lists.
1913  if (shouldPreserveBitcodeUseListOrder())
1914    WriteUseListBlock(nullptr, VE, Stream);
1915
1916  // Emit function bodies.
1917  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
1918    if (!F->isDeclaration())
1919      WriteFunction(*F, VE, Stream);
1920
1921  Stream.ExitBlock();
1922}
1923
1924/// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
1925/// header and trailer to make it compatible with the system archiver.  To do
1926/// this we emit the following header, and then emit a trailer that pads the
1927/// file out to be a multiple of 16 bytes.
1928///
1929/// struct bc_header {
1930///   uint32_t Magic;         // 0x0B17C0DE
1931///   uint32_t Version;       // Version, currently always 0.
1932///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
1933///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
1934///   uint32_t CPUType;       // CPU specifier.
1935///   ... potentially more later ...
1936/// };
1937enum {
1938  DarwinBCSizeFieldOffset = 3*4, // Offset to bitcode_size.
1939  DarwinBCHeaderSize = 5*4
1940};
1941
1942static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
1943                               uint32_t &Position) {
1944  Buffer[Position + 0] = (unsigned char) (Value >>  0);
1945  Buffer[Position + 1] = (unsigned char) (Value >>  8);
1946  Buffer[Position + 2] = (unsigned char) (Value >> 16);
1947  Buffer[Position + 3] = (unsigned char) (Value >> 24);
1948  Position += 4;
1949}
1950
1951static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
1952                                         const Triple &TT) {
1953  unsigned CPUType = ~0U;
1954
1955  // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
1956  // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
1957  // number from /usr/include/mach/machine.h.  It is ok to reproduce the
1958  // specific constants here because they are implicitly part of the Darwin ABI.
1959  enum {
1960    DARWIN_CPU_ARCH_ABI64      = 0x01000000,
1961    DARWIN_CPU_TYPE_X86        = 7,
1962    DARWIN_CPU_TYPE_ARM        = 12,
1963    DARWIN_CPU_TYPE_POWERPC    = 18
1964  };
1965
1966  Triple::ArchType Arch = TT.getArch();
1967  if (Arch == Triple::x86_64)
1968    CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
1969  else if (Arch == Triple::x86)
1970    CPUType = DARWIN_CPU_TYPE_X86;
1971  else if (Arch == Triple::ppc)
1972    CPUType = DARWIN_CPU_TYPE_POWERPC;
1973  else if (Arch == Triple::ppc64)
1974    CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
1975  else if (Arch == Triple::arm || Arch == Triple::thumb)
1976    CPUType = DARWIN_CPU_TYPE_ARM;
1977
1978  // Traditional Bitcode starts after header.
1979  assert(Buffer.size() >= DarwinBCHeaderSize &&
1980         "Expected header size to be reserved");
1981  unsigned BCOffset = DarwinBCHeaderSize;
1982  unsigned BCSize = Buffer.size()-DarwinBCHeaderSize;
1983
1984  // Write the magic and version.
1985  unsigned Position = 0;
1986  WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
1987  WriteInt32ToBuffer(0          , Buffer, Position); // Version.
1988  WriteInt32ToBuffer(BCOffset   , Buffer, Position);
1989  WriteInt32ToBuffer(BCSize     , Buffer, Position);
1990  WriteInt32ToBuffer(CPUType    , Buffer, Position);
1991
1992  // If the file is not a multiple of 16 bytes, insert dummy padding.
1993  while (Buffer.size() & 15)
1994    Buffer.push_back(0);
1995}
1996
1997/// WriteBitcodeToFile - Write the specified module to the specified output
1998/// stream.
1999void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
2000  SmallVector<char, 0> Buffer;
2001  Buffer.reserve(256*1024);
2002
2003  // If this is darwin or another generic macho target, reserve space for the
2004  // header.
2005  Triple TT(M->getTargetTriple());
2006  if (TT.isOSDarwin())
2007    Buffer.insert(Buffer.begin(), DarwinBCHeaderSize, 0);
2008
2009  // Emit the module into the buffer.
2010  {
2011    BitstreamWriter Stream(Buffer);
2012
2013    // Emit the file header.
2014    Stream.Emit((unsigned)'B', 8);
2015    Stream.Emit((unsigned)'C', 8);
2016    Stream.Emit(0x0, 4);
2017    Stream.Emit(0xC, 4);
2018    Stream.Emit(0xE, 4);
2019    Stream.Emit(0xD, 4);
2020
2021    // Emit the module.
2022    WriteModule(M, Stream);
2023  }
2024
2025  if (TT.isOSDarwin())
2026    EmitDarwinBCHeaderAndTrailer(Buffer, TT);
2027
2028  // Write the generated bitstream to "Out".
2029  Out.write((char*)&Buffer.front(), Buffer.size());
2030}
2031