xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 5a57b842cfa8a7cf36eb13670a697dadf01172e0)
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/BitcodeWriter.h"
15 #include "ValueEnumerator.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/ADT/Triple.h"
18 #include "llvm/Bitcode/BitstreamWriter.h"
19 #include "llvm/Bitcode/LLVMBitCodes.h"
20 #include "llvm/IR/CallSite.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DebugInfoMetadata.h"
23 #include "llvm/IR/DerivedTypes.h"
24 #include "llvm/IR/InlineAsm.h"
25 #include "llvm/IR/Instructions.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/Operator.h"
29 #include "llvm/IR/UseListOrder.h"
30 #include "llvm/IR/ValueSymbolTable.h"
31 #include "llvm/MC/StringTableBuilder.h"
32 #include "llvm/Object/IRSymtab.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/MathExtras.h"
35 #include "llvm/Support/Program.h"
36 #include "llvm/Support/SHA1.h"
37 #include "llvm/Support/TargetRegistry.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include <cctype>
40 #include <map>
41 using namespace llvm;
42 
43 namespace {
44 
45 cl::opt<unsigned>
46     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
47                    cl::desc("Number of metadatas above which we emit an index "
48                             "to enable lazy-loading"));
49 /// These are manifest constants used by the bitcode writer. They do not need to
50 /// be kept in sync with the reader, but need to be consistent within this file.
51 enum {
52   // VALUE_SYMTAB_BLOCK abbrev id's.
53   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
54   VST_ENTRY_7_ABBREV,
55   VST_ENTRY_6_ABBREV,
56   VST_BBENTRY_6_ABBREV,
57 
58   // CONSTANTS_BLOCK abbrev id's.
59   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
60   CONSTANTS_INTEGER_ABBREV,
61   CONSTANTS_CE_CAST_Abbrev,
62   CONSTANTS_NULL_Abbrev,
63 
64   // FUNCTION_BLOCK abbrev id's.
65   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
66   FUNCTION_INST_BINOP_ABBREV,
67   FUNCTION_INST_BINOP_FLAGS_ABBREV,
68   FUNCTION_INST_CAST_ABBREV,
69   FUNCTION_INST_RET_VOID_ABBREV,
70   FUNCTION_INST_RET_VAL_ABBREV,
71   FUNCTION_INST_UNREACHABLE_ABBREV,
72   FUNCTION_INST_GEP_ABBREV,
73 };
74 
75 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
76 /// file type.
77 class BitcodeWriterBase {
78 protected:
79   /// The stream created and owned by the client.
80   BitstreamWriter &Stream;
81 
82   StringTableBuilder &StrtabBuilder;
83 
84 public:
85   /// Constructs a BitcodeWriterBase object that writes to the provided
86   /// \p Stream.
87   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
88       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
89 
90 protected:
91   void writeBitcodeHeader();
92   void writeModuleVersion();
93 };
94 
95 void BitcodeWriterBase::writeModuleVersion() {
96   // VERSION: [version#]
97   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
98 }
99 
100 /// Base class to manage the module bitcode writing, currently subclassed for
101 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
102 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
103 protected:
104   /// The Module to write to bitcode.
105   const Module &M;
106 
107   /// Enumerates ids for all values in the module.
108   ValueEnumerator VE;
109 
110   /// Optional per-module index to write for ThinLTO.
111   const ModuleSummaryIndex *Index;
112 
113   /// Map that holds the correspondence between GUIDs in the summary index,
114   /// that came from indirect call profiles, and a value id generated by this
115   /// class to use in the VST and summary block records.
116   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
117 
118   /// Tracks the last value id recorded in the GUIDToValueMap.
119   unsigned GlobalValueId;
120 
121   /// Saves the offset of the VSTOffset record that must eventually be
122   /// backpatched with the offset of the actual VST.
123   uint64_t VSTOffsetPlaceholder = 0;
124 
125 public:
126   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
127   /// writing to the provided \p Buffer.
128   ModuleBitcodeWriterBase(const Module *M, StringTableBuilder &StrtabBuilder,
129                           BitstreamWriter &Stream,
130                           bool ShouldPreserveUseListOrder,
131                           const ModuleSummaryIndex *Index)
132       : BitcodeWriterBase(Stream, StrtabBuilder), M(*M),
133         VE(*M, ShouldPreserveUseListOrder), Index(Index) {
134     // Assign ValueIds to any callee values in the index that came from
135     // indirect call profiles and were recorded as a GUID not a Value*
136     // (which would have been assigned an ID by the ValueEnumerator).
137     // The starting ValueId is just after the number of values in the
138     // ValueEnumerator, so that they can be emitted in the VST.
139     GlobalValueId = VE.getValues().size();
140     if (!Index)
141       return;
142     for (const auto &GUIDSummaryLists : *Index)
143       // Examine all summaries for this GUID.
144       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
145         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
146           // For each call in the function summary, see if the call
147           // is to a GUID (which means it is for an indirect call,
148           // otherwise we would have a Value for it). If so, synthesize
149           // a value id.
150           for (auto &CallEdge : FS->calls())
151             if (!CallEdge.first.getValue())
152               assignValueId(CallEdge.first.getGUID());
153   }
154 
155 protected:
156   void writePerModuleGlobalValueSummary();
157 
158 private:
159   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
160                                            GlobalValueSummary *Summary,
161                                            unsigned ValueID,
162                                            unsigned FSCallsAbbrev,
163                                            unsigned FSCallsProfileAbbrev,
164                                            const Function &F);
165   void writeModuleLevelReferences(const GlobalVariable &V,
166                                   SmallVector<uint64_t, 64> &NameVals,
167                                   unsigned FSModRefsAbbrev);
168 
169   void assignValueId(GlobalValue::GUID ValGUID) {
170     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
171   }
172   unsigned getValueId(GlobalValue::GUID ValGUID) {
173     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
174     // Expect that any GUID value had a value Id assigned by an
175     // earlier call to assignValueId.
176     assert(VMI != GUIDToValueIdMap.end() &&
177            "GUID does not have assigned value Id");
178     return VMI->second;
179   }
180   // Helper to get the valueId for the type of value recorded in VI.
181   unsigned getValueId(ValueInfo VI) {
182     if (!VI.getValue())
183       return getValueId(VI.getGUID());
184     return VE.getValueID(VI.getValue());
185   }
186   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
187 };
188 
189 /// Class to manage the bitcode writing for a module.
190 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
191   /// Pointer to the buffer allocated by caller for bitcode writing.
192   const SmallVectorImpl<char> &Buffer;
193 
194   /// True if a module hash record should be written.
195   bool GenerateHash;
196 
197   /// If non-null, when GenerateHash is true, the resulting hash is written
198   /// into ModHash.
199   ModuleHash *ModHash;
200 
201   SHA1 Hasher;
202 
203   /// The start bit of the identification block.
204   uint64_t BitcodeStartBit;
205 
206 public:
207   /// Constructs a ModuleBitcodeWriter object for the given Module,
208   /// writing to the provided \p Buffer.
209   ModuleBitcodeWriter(const Module *M, SmallVectorImpl<char> &Buffer,
210                       StringTableBuilder &StrtabBuilder,
211                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
212                       const ModuleSummaryIndex *Index, bool GenerateHash,
213                       ModuleHash *ModHash = nullptr)
214       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
215                                 ShouldPreserveUseListOrder, Index),
216         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
217         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
218 
219   /// Emit the current module to the bitstream.
220   void write();
221 
222 private:
223   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
224 
225   size_t addToStrtab(StringRef Str);
226 
227   void writeAttributeGroupTable();
228   void writeAttributeTable();
229   void writeTypeTable();
230   void writeComdats();
231   void writeValueSymbolTableForwardDecl();
232   void writeModuleInfo();
233   void writeValueAsMetadata(const ValueAsMetadata *MD,
234                             SmallVectorImpl<uint64_t> &Record);
235   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
236                     unsigned Abbrev);
237   unsigned createDILocationAbbrev();
238   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
239                        unsigned &Abbrev);
240   unsigned createGenericDINodeAbbrev();
241   void writeGenericDINode(const GenericDINode *N,
242                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
243   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
244                        unsigned Abbrev);
245   void writeDIEnumerator(const DIEnumerator *N,
246                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
247   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
248                         unsigned Abbrev);
249   void writeDIDerivedType(const DIDerivedType *N,
250                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
251   void writeDICompositeType(const DICompositeType *N,
252                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
253   void writeDISubroutineType(const DISubroutineType *N,
254                              SmallVectorImpl<uint64_t> &Record,
255                              unsigned Abbrev);
256   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
257                    unsigned Abbrev);
258   void writeDICompileUnit(const DICompileUnit *N,
259                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
260   void writeDISubprogram(const DISubprogram *N,
261                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
262   void writeDILexicalBlock(const DILexicalBlock *N,
263                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
264   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
265                                SmallVectorImpl<uint64_t> &Record,
266                                unsigned Abbrev);
267   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
268                         unsigned Abbrev);
269   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
270                     unsigned Abbrev);
271   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
272                         unsigned Abbrev);
273   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
274                      unsigned Abbrev);
275   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
276                                     SmallVectorImpl<uint64_t> &Record,
277                                     unsigned Abbrev);
278   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
279                                      SmallVectorImpl<uint64_t> &Record,
280                                      unsigned Abbrev);
281   void writeDIGlobalVariable(const DIGlobalVariable *N,
282                              SmallVectorImpl<uint64_t> &Record,
283                              unsigned Abbrev);
284   void writeDILocalVariable(const DILocalVariable *N,
285                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
286   void writeDIExpression(const DIExpression *N,
287                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
288   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
289                                        SmallVectorImpl<uint64_t> &Record,
290                                        unsigned Abbrev);
291   void writeDIObjCProperty(const DIObjCProperty *N,
292                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
293   void writeDIImportedEntity(const DIImportedEntity *N,
294                              SmallVectorImpl<uint64_t> &Record,
295                              unsigned Abbrev);
296   unsigned createNamedMetadataAbbrev();
297   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
298   unsigned createMetadataStringsAbbrev();
299   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
300                             SmallVectorImpl<uint64_t> &Record);
301   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
302                             SmallVectorImpl<uint64_t> &Record,
303                             std::vector<unsigned> *MDAbbrevs = nullptr,
304                             std::vector<uint64_t> *IndexPos = nullptr);
305   void writeModuleMetadata();
306   void writeFunctionMetadata(const Function &F);
307   void writeFunctionMetadataAttachment(const Function &F);
308   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
309   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
310                                     const GlobalObject &GO);
311   void writeModuleMetadataKinds();
312   void writeOperandBundleTags();
313   void writeSyncScopeNames();
314   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
315   void writeModuleConstants();
316   bool pushValueAndType(const Value *V, unsigned InstID,
317                         SmallVectorImpl<unsigned> &Vals);
318   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
319   void pushValue(const Value *V, unsigned InstID,
320                  SmallVectorImpl<unsigned> &Vals);
321   void pushValueSigned(const Value *V, unsigned InstID,
322                        SmallVectorImpl<uint64_t> &Vals);
323   void writeInstruction(const Instruction &I, unsigned InstID,
324                         SmallVectorImpl<unsigned> &Vals);
325   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
326   void writeGlobalValueSymbolTable(
327       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
328   void writeUseList(UseListOrder &&Order);
329   void writeUseListBlock(const Function *F);
330   void
331   writeFunction(const Function &F,
332                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
333   void writeBlockInfo();
334   void writeModuleHash(size_t BlockStartPos);
335 
336   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
337     return unsigned(SSID);
338   }
339 };
340 
341 /// Class to manage the bitcode writing for a combined index.
342 class IndexBitcodeWriter : public BitcodeWriterBase {
343   /// The combined index to write to bitcode.
344   const ModuleSummaryIndex &Index;
345 
346   /// When writing a subset of the index for distributed backends, client
347   /// provides a map of modules to the corresponding GUIDs/summaries to write.
348   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
349 
350   /// Map that holds the correspondence between the GUID used in the combined
351   /// index and a value id generated by this class to use in references.
352   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
353 
354   /// Tracks the last value id recorded in the GUIDToValueMap.
355   unsigned GlobalValueId = 0;
356 
357 public:
358   /// Constructs a IndexBitcodeWriter object for the given combined index,
359   /// writing to the provided \p Buffer. When writing a subset of the index
360   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
361   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
362                      const ModuleSummaryIndex &Index,
363                      const std::map<std::string, GVSummaryMapTy>
364                          *ModuleToSummariesForIndex = nullptr)
365       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
366         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
367     // Assign unique value ids to all summaries to be written, for use
368     // in writing out the call graph edges. Save the mapping from GUID
369     // to the new global value id to use when writing those edges, which
370     // are currently saved in the index in terms of GUID.
371     forEachSummary([&](GVInfo I) {
372       GUIDToValueIdMap[I.first] = ++GlobalValueId;
373     });
374   }
375 
376   /// The below iterator returns the GUID and associated summary.
377   typedef std::pair<GlobalValue::GUID, GlobalValueSummary *> GVInfo;
378 
379   /// Calls the callback for each value GUID and summary to be written to
380   /// bitcode. This hides the details of whether they are being pulled from the
381   /// entire index or just those in a provided ModuleToSummariesForIndex map.
382   template<typename Functor>
383   void forEachSummary(Functor Callback) {
384     if (ModuleToSummariesForIndex) {
385       for (auto &M : *ModuleToSummariesForIndex)
386         for (auto &Summary : M.second)
387           Callback(Summary);
388     } else {
389       for (auto &Summaries : Index)
390         for (auto &Summary : Summaries.second.SummaryList)
391           Callback({Summaries.first, Summary.get()});
392     }
393   }
394 
395   /// Calls the callback for each entry in the modulePaths StringMap that
396   /// should be written to the module path string table. This hides the details
397   /// of whether they are being pulled from the entire index or just those in a
398   /// provided ModuleToSummariesForIndex map.
399   template <typename Functor> void forEachModule(Functor Callback) {
400     if (ModuleToSummariesForIndex) {
401       for (const auto &M : *ModuleToSummariesForIndex) {
402         const auto &MPI = Index.modulePaths().find(M.first);
403         if (MPI == Index.modulePaths().end()) {
404           // This should only happen if the bitcode file was empty, in which
405           // case we shouldn't be importing (the ModuleToSummariesForIndex
406           // would only include the module we are writing and index for).
407           assert(ModuleToSummariesForIndex->size() == 1);
408           continue;
409         }
410         Callback(*MPI);
411       }
412     } else {
413       for (const auto &MPSE : Index.modulePaths())
414         Callback(MPSE);
415     }
416   }
417 
418   /// Main entry point for writing a combined index to bitcode.
419   void write();
420 
421 private:
422   void writeModStrings();
423   void writeCombinedGlobalValueSummary();
424 
425   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
426     auto VMI = GUIDToValueIdMap.find(ValGUID);
427     if (VMI == GUIDToValueIdMap.end())
428       return None;
429     return VMI->second;
430   }
431   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
432 };
433 } // end anonymous namespace
434 
435 static unsigned getEncodedCastOpcode(unsigned Opcode) {
436   switch (Opcode) {
437   default: llvm_unreachable("Unknown cast instruction!");
438   case Instruction::Trunc   : return bitc::CAST_TRUNC;
439   case Instruction::ZExt    : return bitc::CAST_ZEXT;
440   case Instruction::SExt    : return bitc::CAST_SEXT;
441   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
442   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
443   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
444   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
445   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
446   case Instruction::FPExt   : return bitc::CAST_FPEXT;
447   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
448   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
449   case Instruction::BitCast : return bitc::CAST_BITCAST;
450   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
451   }
452 }
453 
454 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
455   switch (Opcode) {
456   default: llvm_unreachable("Unknown binary instruction!");
457   case Instruction::Add:
458   case Instruction::FAdd: return bitc::BINOP_ADD;
459   case Instruction::Sub:
460   case Instruction::FSub: return bitc::BINOP_SUB;
461   case Instruction::Mul:
462   case Instruction::FMul: return bitc::BINOP_MUL;
463   case Instruction::UDiv: return bitc::BINOP_UDIV;
464   case Instruction::FDiv:
465   case Instruction::SDiv: return bitc::BINOP_SDIV;
466   case Instruction::URem: return bitc::BINOP_UREM;
467   case Instruction::FRem:
468   case Instruction::SRem: return bitc::BINOP_SREM;
469   case Instruction::Shl:  return bitc::BINOP_SHL;
470   case Instruction::LShr: return bitc::BINOP_LSHR;
471   case Instruction::AShr: return bitc::BINOP_ASHR;
472   case Instruction::And:  return bitc::BINOP_AND;
473   case Instruction::Or:   return bitc::BINOP_OR;
474   case Instruction::Xor:  return bitc::BINOP_XOR;
475   }
476 }
477 
478 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
479   switch (Op) {
480   default: llvm_unreachable("Unknown RMW operation!");
481   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
482   case AtomicRMWInst::Add: return bitc::RMW_ADD;
483   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
484   case AtomicRMWInst::And: return bitc::RMW_AND;
485   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
486   case AtomicRMWInst::Or: return bitc::RMW_OR;
487   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
488   case AtomicRMWInst::Max: return bitc::RMW_MAX;
489   case AtomicRMWInst::Min: return bitc::RMW_MIN;
490   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
491   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
492   }
493 }
494 
495 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
496   switch (Ordering) {
497   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
498   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
499   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
500   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
501   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
502   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
503   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
504   }
505   llvm_unreachable("Invalid ordering");
506 }
507 
508 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
509                               StringRef Str, unsigned AbbrevToUse) {
510   SmallVector<unsigned, 64> Vals;
511 
512   // Code: [strchar x N]
513   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
514     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
515       AbbrevToUse = 0;
516     Vals.push_back(Str[i]);
517   }
518 
519   // Emit the finished record.
520   Stream.EmitRecord(Code, Vals, AbbrevToUse);
521 }
522 
523 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
524   switch (Kind) {
525   case Attribute::Alignment:
526     return bitc::ATTR_KIND_ALIGNMENT;
527   case Attribute::AllocSize:
528     return bitc::ATTR_KIND_ALLOC_SIZE;
529   case Attribute::AlwaysInline:
530     return bitc::ATTR_KIND_ALWAYS_INLINE;
531   case Attribute::ArgMemOnly:
532     return bitc::ATTR_KIND_ARGMEMONLY;
533   case Attribute::Builtin:
534     return bitc::ATTR_KIND_BUILTIN;
535   case Attribute::ByVal:
536     return bitc::ATTR_KIND_BY_VAL;
537   case Attribute::Convergent:
538     return bitc::ATTR_KIND_CONVERGENT;
539   case Attribute::InAlloca:
540     return bitc::ATTR_KIND_IN_ALLOCA;
541   case Attribute::Cold:
542     return bitc::ATTR_KIND_COLD;
543   case Attribute::InaccessibleMemOnly:
544     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
545   case Attribute::InaccessibleMemOrArgMemOnly:
546     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
547   case Attribute::InlineHint:
548     return bitc::ATTR_KIND_INLINE_HINT;
549   case Attribute::InReg:
550     return bitc::ATTR_KIND_IN_REG;
551   case Attribute::JumpTable:
552     return bitc::ATTR_KIND_JUMP_TABLE;
553   case Attribute::MinSize:
554     return bitc::ATTR_KIND_MIN_SIZE;
555   case Attribute::Naked:
556     return bitc::ATTR_KIND_NAKED;
557   case Attribute::Nest:
558     return bitc::ATTR_KIND_NEST;
559   case Attribute::NoAlias:
560     return bitc::ATTR_KIND_NO_ALIAS;
561   case Attribute::NoBuiltin:
562     return bitc::ATTR_KIND_NO_BUILTIN;
563   case Attribute::NoCapture:
564     return bitc::ATTR_KIND_NO_CAPTURE;
565   case Attribute::NoDuplicate:
566     return bitc::ATTR_KIND_NO_DUPLICATE;
567   case Attribute::NoImplicitFloat:
568     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
569   case Attribute::NoInline:
570     return bitc::ATTR_KIND_NO_INLINE;
571   case Attribute::NoRecurse:
572     return bitc::ATTR_KIND_NO_RECURSE;
573   case Attribute::NonLazyBind:
574     return bitc::ATTR_KIND_NON_LAZY_BIND;
575   case Attribute::NonNull:
576     return bitc::ATTR_KIND_NON_NULL;
577   case Attribute::Dereferenceable:
578     return bitc::ATTR_KIND_DEREFERENCEABLE;
579   case Attribute::DereferenceableOrNull:
580     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
581   case Attribute::NoRedZone:
582     return bitc::ATTR_KIND_NO_RED_ZONE;
583   case Attribute::NoReturn:
584     return bitc::ATTR_KIND_NO_RETURN;
585   case Attribute::NoUnwind:
586     return bitc::ATTR_KIND_NO_UNWIND;
587   case Attribute::OptimizeForSize:
588     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
589   case Attribute::OptimizeNone:
590     return bitc::ATTR_KIND_OPTIMIZE_NONE;
591   case Attribute::ReadNone:
592     return bitc::ATTR_KIND_READ_NONE;
593   case Attribute::ReadOnly:
594     return bitc::ATTR_KIND_READ_ONLY;
595   case Attribute::Returned:
596     return bitc::ATTR_KIND_RETURNED;
597   case Attribute::ReturnsTwice:
598     return bitc::ATTR_KIND_RETURNS_TWICE;
599   case Attribute::SExt:
600     return bitc::ATTR_KIND_S_EXT;
601   case Attribute::Speculatable:
602     return bitc::ATTR_KIND_SPECULATABLE;
603   case Attribute::StackAlignment:
604     return bitc::ATTR_KIND_STACK_ALIGNMENT;
605   case Attribute::StackProtect:
606     return bitc::ATTR_KIND_STACK_PROTECT;
607   case Attribute::StackProtectReq:
608     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
609   case Attribute::StackProtectStrong:
610     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
611   case Attribute::SafeStack:
612     return bitc::ATTR_KIND_SAFESTACK;
613   case Attribute::StrictFP:
614     return bitc::ATTR_KIND_STRICT_FP;
615   case Attribute::StructRet:
616     return bitc::ATTR_KIND_STRUCT_RET;
617   case Attribute::SanitizeAddress:
618     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
619   case Attribute::SanitizeThread:
620     return bitc::ATTR_KIND_SANITIZE_THREAD;
621   case Attribute::SanitizeMemory:
622     return bitc::ATTR_KIND_SANITIZE_MEMORY;
623   case Attribute::SwiftError:
624     return bitc::ATTR_KIND_SWIFT_ERROR;
625   case Attribute::SwiftSelf:
626     return bitc::ATTR_KIND_SWIFT_SELF;
627   case Attribute::UWTable:
628     return bitc::ATTR_KIND_UW_TABLE;
629   case Attribute::WriteOnly:
630     return bitc::ATTR_KIND_WRITEONLY;
631   case Attribute::ZExt:
632     return bitc::ATTR_KIND_Z_EXT;
633   case Attribute::EndAttrKinds:
634     llvm_unreachable("Can not encode end-attribute kinds marker.");
635   case Attribute::None:
636     llvm_unreachable("Can not encode none-attribute.");
637   }
638 
639   llvm_unreachable("Trying to encode unknown attribute");
640 }
641 
642 void ModuleBitcodeWriter::writeAttributeGroupTable() {
643   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
644       VE.getAttributeGroups();
645   if (AttrGrps.empty()) return;
646 
647   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
648 
649   SmallVector<uint64_t, 64> Record;
650   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
651     unsigned AttrListIndex = Pair.first;
652     AttributeSet AS = Pair.second;
653     Record.push_back(VE.getAttributeGroupID(Pair));
654     Record.push_back(AttrListIndex);
655 
656     for (Attribute Attr : AS) {
657       if (Attr.isEnumAttribute()) {
658         Record.push_back(0);
659         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
660       } else if (Attr.isIntAttribute()) {
661         Record.push_back(1);
662         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
663         Record.push_back(Attr.getValueAsInt());
664       } else {
665         StringRef Kind = Attr.getKindAsString();
666         StringRef Val = Attr.getValueAsString();
667 
668         Record.push_back(Val.empty() ? 3 : 4);
669         Record.append(Kind.begin(), Kind.end());
670         Record.push_back(0);
671         if (!Val.empty()) {
672           Record.append(Val.begin(), Val.end());
673           Record.push_back(0);
674         }
675       }
676     }
677 
678     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
679     Record.clear();
680   }
681 
682   Stream.ExitBlock();
683 }
684 
685 void ModuleBitcodeWriter::writeAttributeTable() {
686   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
687   if (Attrs.empty()) return;
688 
689   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
690 
691   SmallVector<uint64_t, 64> Record;
692   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
693     AttributeList AL = Attrs[i];
694     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
695       AttributeSet AS = AL.getAttributes(i);
696       if (AS.hasAttributes())
697         Record.push_back(VE.getAttributeGroupID({i, AS}));
698     }
699 
700     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
701     Record.clear();
702   }
703 
704   Stream.ExitBlock();
705 }
706 
707 /// WriteTypeTable - Write out the type table for a module.
708 void ModuleBitcodeWriter::writeTypeTable() {
709   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
710 
711   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
712   SmallVector<uint64_t, 64> TypeVals;
713 
714   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
715 
716   // Abbrev for TYPE_CODE_POINTER.
717   auto Abbv = std::make_shared<BitCodeAbbrev>();
718   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
719   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
720   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
721   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
722 
723   // Abbrev for TYPE_CODE_FUNCTION.
724   Abbv = std::make_shared<BitCodeAbbrev>();
725   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
726   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
727   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
728   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
729 
730   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
731 
732   // Abbrev for TYPE_CODE_STRUCT_ANON.
733   Abbv = std::make_shared<BitCodeAbbrev>();
734   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
735   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
736   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
737   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
738 
739   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
740 
741   // Abbrev for TYPE_CODE_STRUCT_NAME.
742   Abbv = std::make_shared<BitCodeAbbrev>();
743   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
744   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
745   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
746   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
747 
748   // Abbrev for TYPE_CODE_STRUCT_NAMED.
749   Abbv = std::make_shared<BitCodeAbbrev>();
750   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
751   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
752   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
753   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
754 
755   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
756 
757   // Abbrev for TYPE_CODE_ARRAY.
758   Abbv = std::make_shared<BitCodeAbbrev>();
759   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
760   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
761   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
762 
763   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
764 
765   // Emit an entry count so the reader can reserve space.
766   TypeVals.push_back(TypeList.size());
767   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
768   TypeVals.clear();
769 
770   // Loop over all of the types, emitting each in turn.
771   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
772     Type *T = TypeList[i];
773     int AbbrevToUse = 0;
774     unsigned Code = 0;
775 
776     switch (T->getTypeID()) {
777     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
778     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
779     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
780     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
781     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
782     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
783     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
784     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
785     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
786     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
787     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
788     case Type::IntegerTyID:
789       // INTEGER: [width]
790       Code = bitc::TYPE_CODE_INTEGER;
791       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
792       break;
793     case Type::PointerTyID: {
794       PointerType *PTy = cast<PointerType>(T);
795       // POINTER: [pointee type, address space]
796       Code = bitc::TYPE_CODE_POINTER;
797       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
798       unsigned AddressSpace = PTy->getAddressSpace();
799       TypeVals.push_back(AddressSpace);
800       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
801       break;
802     }
803     case Type::FunctionTyID: {
804       FunctionType *FT = cast<FunctionType>(T);
805       // FUNCTION: [isvararg, retty, paramty x N]
806       Code = bitc::TYPE_CODE_FUNCTION;
807       TypeVals.push_back(FT->isVarArg());
808       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
809       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
810         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
811       AbbrevToUse = FunctionAbbrev;
812       break;
813     }
814     case Type::StructTyID: {
815       StructType *ST = cast<StructType>(T);
816       // STRUCT: [ispacked, eltty x N]
817       TypeVals.push_back(ST->isPacked());
818       // Output all of the element types.
819       for (StructType::element_iterator I = ST->element_begin(),
820            E = ST->element_end(); I != E; ++I)
821         TypeVals.push_back(VE.getTypeID(*I));
822 
823       if (ST->isLiteral()) {
824         Code = bitc::TYPE_CODE_STRUCT_ANON;
825         AbbrevToUse = StructAnonAbbrev;
826       } else {
827         if (ST->isOpaque()) {
828           Code = bitc::TYPE_CODE_OPAQUE;
829         } else {
830           Code = bitc::TYPE_CODE_STRUCT_NAMED;
831           AbbrevToUse = StructNamedAbbrev;
832         }
833 
834         // Emit the name if it is present.
835         if (!ST->getName().empty())
836           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
837                             StructNameAbbrev);
838       }
839       break;
840     }
841     case Type::ArrayTyID: {
842       ArrayType *AT = cast<ArrayType>(T);
843       // ARRAY: [numelts, eltty]
844       Code = bitc::TYPE_CODE_ARRAY;
845       TypeVals.push_back(AT->getNumElements());
846       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
847       AbbrevToUse = ArrayAbbrev;
848       break;
849     }
850     case Type::VectorTyID: {
851       VectorType *VT = cast<VectorType>(T);
852       // VECTOR [numelts, eltty]
853       Code = bitc::TYPE_CODE_VECTOR;
854       TypeVals.push_back(VT->getNumElements());
855       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
856       break;
857     }
858     }
859 
860     // Emit the finished record.
861     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
862     TypeVals.clear();
863   }
864 
865   Stream.ExitBlock();
866 }
867 
868 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
869   switch (Linkage) {
870   case GlobalValue::ExternalLinkage:
871     return 0;
872   case GlobalValue::WeakAnyLinkage:
873     return 16;
874   case GlobalValue::AppendingLinkage:
875     return 2;
876   case GlobalValue::InternalLinkage:
877     return 3;
878   case GlobalValue::LinkOnceAnyLinkage:
879     return 18;
880   case GlobalValue::ExternalWeakLinkage:
881     return 7;
882   case GlobalValue::CommonLinkage:
883     return 8;
884   case GlobalValue::PrivateLinkage:
885     return 9;
886   case GlobalValue::WeakODRLinkage:
887     return 17;
888   case GlobalValue::LinkOnceODRLinkage:
889     return 19;
890   case GlobalValue::AvailableExternallyLinkage:
891     return 12;
892   }
893   llvm_unreachable("Invalid linkage");
894 }
895 
896 static unsigned getEncodedLinkage(const GlobalValue &GV) {
897   return getEncodedLinkage(GV.getLinkage());
898 }
899 
900 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
901   uint64_t RawFlags = 0;
902   RawFlags |= Flags.ReadNone;
903   RawFlags |= (Flags.ReadOnly << 1);
904   RawFlags |= (Flags.NoRecurse << 2);
905   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
906   return RawFlags;
907 }
908 
909 // Decode the flags for GlobalValue in the summary
910 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
911   uint64_t RawFlags = 0;
912 
913   RawFlags |= Flags.NotEligibleToImport; // bool
914   RawFlags |= (Flags.Live << 1);
915   // Linkage don't need to be remapped at that time for the summary. Any future
916   // change to the getEncodedLinkage() function will need to be taken into
917   // account here as well.
918   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
919 
920   return RawFlags;
921 }
922 
923 static unsigned getEncodedVisibility(const GlobalValue &GV) {
924   switch (GV.getVisibility()) {
925   case GlobalValue::DefaultVisibility:   return 0;
926   case GlobalValue::HiddenVisibility:    return 1;
927   case GlobalValue::ProtectedVisibility: return 2;
928   }
929   llvm_unreachable("Invalid visibility");
930 }
931 
932 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
933   switch (GV.getDLLStorageClass()) {
934   case GlobalValue::DefaultStorageClass:   return 0;
935   case GlobalValue::DLLImportStorageClass: return 1;
936   case GlobalValue::DLLExportStorageClass: return 2;
937   }
938   llvm_unreachable("Invalid DLL storage class");
939 }
940 
941 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
942   switch (GV.getThreadLocalMode()) {
943     case GlobalVariable::NotThreadLocal:         return 0;
944     case GlobalVariable::GeneralDynamicTLSModel: return 1;
945     case GlobalVariable::LocalDynamicTLSModel:   return 2;
946     case GlobalVariable::InitialExecTLSModel:    return 3;
947     case GlobalVariable::LocalExecTLSModel:      return 4;
948   }
949   llvm_unreachable("Invalid TLS model");
950 }
951 
952 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
953   switch (C.getSelectionKind()) {
954   case Comdat::Any:
955     return bitc::COMDAT_SELECTION_KIND_ANY;
956   case Comdat::ExactMatch:
957     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
958   case Comdat::Largest:
959     return bitc::COMDAT_SELECTION_KIND_LARGEST;
960   case Comdat::NoDuplicates:
961     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
962   case Comdat::SameSize:
963     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
964   }
965   llvm_unreachable("Invalid selection kind");
966 }
967 
968 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
969   switch (GV.getUnnamedAddr()) {
970   case GlobalValue::UnnamedAddr::None:   return 0;
971   case GlobalValue::UnnamedAddr::Local:  return 2;
972   case GlobalValue::UnnamedAddr::Global: return 1;
973   }
974   llvm_unreachable("Invalid unnamed_addr");
975 }
976 
977 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
978   if (GenerateHash)
979     Hasher.update(Str);
980   return StrtabBuilder.add(Str);
981 }
982 
983 void ModuleBitcodeWriter::writeComdats() {
984   SmallVector<unsigned, 64> Vals;
985   for (const Comdat *C : VE.getComdats()) {
986     // COMDAT: [strtab offset, strtab size, selection_kind]
987     Vals.push_back(addToStrtab(C->getName()));
988     Vals.push_back(C->getName().size());
989     Vals.push_back(getEncodedComdatSelectionKind(*C));
990     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
991     Vals.clear();
992   }
993 }
994 
995 /// Write a record that will eventually hold the word offset of the
996 /// module-level VST. For now the offset is 0, which will be backpatched
997 /// after the real VST is written. Saves the bit offset to backpatch.
998 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
999   // Write a placeholder value in for the offset of the real VST,
1000   // which is written after the function blocks so that it can include
1001   // the offset of each function. The placeholder offset will be
1002   // updated when the real VST is written.
1003   auto Abbv = std::make_shared<BitCodeAbbrev>();
1004   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1005   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1006   // hold the real VST offset. Must use fixed instead of VBR as we don't
1007   // know how many VBR chunks to reserve ahead of time.
1008   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1009   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1010 
1011   // Emit the placeholder
1012   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1013   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1014 
1015   // Compute and save the bit offset to the placeholder, which will be
1016   // patched when the real VST is written. We can simply subtract the 32-bit
1017   // fixed size from the current bit number to get the location to backpatch.
1018   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1019 }
1020 
1021 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1022 
1023 /// Determine the encoding to use for the given string name and length.
1024 static StringEncoding getStringEncoding(StringRef Str) {
1025   bool isChar6 = true;
1026   for (char C : Str) {
1027     if (isChar6)
1028       isChar6 = BitCodeAbbrevOp::isChar6(C);
1029     if ((unsigned char)C & 128)
1030       // don't bother scanning the rest.
1031       return SE_Fixed8;
1032   }
1033   if (isChar6)
1034     return SE_Char6;
1035   return SE_Fixed7;
1036 }
1037 
1038 /// Emit top-level description of module, including target triple, inline asm,
1039 /// descriptors for global variables, and function prototype info.
1040 /// Returns the bit offset to backpatch with the location of the real VST.
1041 void ModuleBitcodeWriter::writeModuleInfo() {
1042   // Emit various pieces of data attached to a module.
1043   if (!M.getTargetTriple().empty())
1044     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1045                       0 /*TODO*/);
1046   const std::string &DL = M.getDataLayoutStr();
1047   if (!DL.empty())
1048     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1049   if (!M.getModuleInlineAsm().empty())
1050     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1051                       0 /*TODO*/);
1052 
1053   // Emit information about sections and GC, computing how many there are. Also
1054   // compute the maximum alignment value.
1055   std::map<std::string, unsigned> SectionMap;
1056   std::map<std::string, unsigned> GCMap;
1057   unsigned MaxAlignment = 0;
1058   unsigned MaxGlobalType = 0;
1059   for (const GlobalValue &GV : M.globals()) {
1060     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1061     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1062     if (GV.hasSection()) {
1063       // Give section names unique ID's.
1064       unsigned &Entry = SectionMap[GV.getSection()];
1065       if (!Entry) {
1066         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1067                           0 /*TODO*/);
1068         Entry = SectionMap.size();
1069       }
1070     }
1071   }
1072   for (const Function &F : M) {
1073     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1074     if (F.hasSection()) {
1075       // Give section names unique ID's.
1076       unsigned &Entry = SectionMap[F.getSection()];
1077       if (!Entry) {
1078         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1079                           0 /*TODO*/);
1080         Entry = SectionMap.size();
1081       }
1082     }
1083     if (F.hasGC()) {
1084       // Same for GC names.
1085       unsigned &Entry = GCMap[F.getGC()];
1086       if (!Entry) {
1087         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1088                           0 /*TODO*/);
1089         Entry = GCMap.size();
1090       }
1091     }
1092   }
1093 
1094   // Emit abbrev for globals, now that we know # sections and max alignment.
1095   unsigned SimpleGVarAbbrev = 0;
1096   if (!M.global_empty()) {
1097     // Add an abbrev for common globals with no visibility or thread localness.
1098     auto Abbv = std::make_shared<BitCodeAbbrev>();
1099     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1100     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1101     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1102     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1103                               Log2_32_Ceil(MaxGlobalType+1)));
1104     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1105                                                            //| explicitType << 1
1106                                                            //| constant
1107     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1108     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1109     if (MaxAlignment == 0)                                 // Alignment.
1110       Abbv->Add(BitCodeAbbrevOp(0));
1111     else {
1112       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1113       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1114                                Log2_32_Ceil(MaxEncAlignment+1)));
1115     }
1116     if (SectionMap.empty())                                    // Section.
1117       Abbv->Add(BitCodeAbbrevOp(0));
1118     else
1119       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1120                                Log2_32_Ceil(SectionMap.size()+1)));
1121     // Don't bother emitting vis + thread local.
1122     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1123   }
1124 
1125   SmallVector<unsigned, 64> Vals;
1126   // Emit the module's source file name.
1127   {
1128     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1129     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1130     if (Bits == SE_Char6)
1131       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1132     else if (Bits == SE_Fixed7)
1133       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1134 
1135     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1136     auto Abbv = std::make_shared<BitCodeAbbrev>();
1137     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1138     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1139     Abbv->Add(AbbrevOpToUse);
1140     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1141 
1142     for (const auto P : M.getSourceFileName())
1143       Vals.push_back((unsigned char)P);
1144 
1145     // Emit the finished record.
1146     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1147     Vals.clear();
1148   }
1149 
1150   // Emit the global variable information.
1151   for (const GlobalVariable &GV : M.globals()) {
1152     unsigned AbbrevToUse = 0;
1153 
1154     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1155     //             linkage, alignment, section, visibility, threadlocal,
1156     //             unnamed_addr, externally_initialized, dllstorageclass,
1157     //             comdat, attributes]
1158     Vals.push_back(addToStrtab(GV.getName()));
1159     Vals.push_back(GV.getName().size());
1160     Vals.push_back(VE.getTypeID(GV.getValueType()));
1161     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1162     Vals.push_back(GV.isDeclaration() ? 0 :
1163                    (VE.getValueID(GV.getInitializer()) + 1));
1164     Vals.push_back(getEncodedLinkage(GV));
1165     Vals.push_back(Log2_32(GV.getAlignment())+1);
1166     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1167     if (GV.isThreadLocal() ||
1168         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1169         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1170         GV.isExternallyInitialized() ||
1171         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1172         GV.hasComdat() ||
1173         GV.hasAttributes()) {
1174       Vals.push_back(getEncodedVisibility(GV));
1175       Vals.push_back(getEncodedThreadLocalMode(GV));
1176       Vals.push_back(getEncodedUnnamedAddr(GV));
1177       Vals.push_back(GV.isExternallyInitialized());
1178       Vals.push_back(getEncodedDLLStorageClass(GV));
1179       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1180 
1181       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1182       Vals.push_back(VE.getAttributeListID(AL));
1183     } else {
1184       AbbrevToUse = SimpleGVarAbbrev;
1185     }
1186 
1187     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1188     Vals.clear();
1189   }
1190 
1191   // Emit the function proto information.
1192   for (const Function &F : M) {
1193     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1194     //             linkage, paramattrs, alignment, section, visibility, gc,
1195     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1196     //             prefixdata, personalityfn]
1197     Vals.push_back(addToStrtab(F.getName()));
1198     Vals.push_back(F.getName().size());
1199     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1200     Vals.push_back(F.getCallingConv());
1201     Vals.push_back(F.isDeclaration());
1202     Vals.push_back(getEncodedLinkage(F));
1203     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1204     Vals.push_back(Log2_32(F.getAlignment())+1);
1205     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1206     Vals.push_back(getEncodedVisibility(F));
1207     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1208     Vals.push_back(getEncodedUnnamedAddr(F));
1209     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1210                                        : 0);
1211     Vals.push_back(getEncodedDLLStorageClass(F));
1212     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1213     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1214                                      : 0);
1215     Vals.push_back(
1216         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1217 
1218     unsigned AbbrevToUse = 0;
1219     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1220     Vals.clear();
1221   }
1222 
1223   // Emit the alias information.
1224   for (const GlobalAlias &A : M.aliases()) {
1225     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1226     //         visibility, dllstorageclass, threadlocal, unnamed_addr]
1227     Vals.push_back(addToStrtab(A.getName()));
1228     Vals.push_back(A.getName().size());
1229     Vals.push_back(VE.getTypeID(A.getValueType()));
1230     Vals.push_back(A.getType()->getAddressSpace());
1231     Vals.push_back(VE.getValueID(A.getAliasee()));
1232     Vals.push_back(getEncodedLinkage(A));
1233     Vals.push_back(getEncodedVisibility(A));
1234     Vals.push_back(getEncodedDLLStorageClass(A));
1235     Vals.push_back(getEncodedThreadLocalMode(A));
1236     Vals.push_back(getEncodedUnnamedAddr(A));
1237     unsigned AbbrevToUse = 0;
1238     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1239     Vals.clear();
1240   }
1241 
1242   // Emit the ifunc information.
1243   for (const GlobalIFunc &I : M.ifuncs()) {
1244     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1245     //         val#, linkage, visibility]
1246     Vals.push_back(addToStrtab(I.getName()));
1247     Vals.push_back(I.getName().size());
1248     Vals.push_back(VE.getTypeID(I.getValueType()));
1249     Vals.push_back(I.getType()->getAddressSpace());
1250     Vals.push_back(VE.getValueID(I.getResolver()));
1251     Vals.push_back(getEncodedLinkage(I));
1252     Vals.push_back(getEncodedVisibility(I));
1253     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1254     Vals.clear();
1255   }
1256 
1257   writeValueSymbolTableForwardDecl();
1258 }
1259 
1260 static uint64_t getOptimizationFlags(const Value *V) {
1261   uint64_t Flags = 0;
1262 
1263   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1264     if (OBO->hasNoSignedWrap())
1265       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1266     if (OBO->hasNoUnsignedWrap())
1267       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1268   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1269     if (PEO->isExact())
1270       Flags |= 1 << bitc::PEO_EXACT;
1271   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1272     if (FPMO->hasUnsafeAlgebra())
1273       Flags |= FastMathFlags::UnsafeAlgebra;
1274     if (FPMO->hasNoNaNs())
1275       Flags |= FastMathFlags::NoNaNs;
1276     if (FPMO->hasNoInfs())
1277       Flags |= FastMathFlags::NoInfs;
1278     if (FPMO->hasNoSignedZeros())
1279       Flags |= FastMathFlags::NoSignedZeros;
1280     if (FPMO->hasAllowReciprocal())
1281       Flags |= FastMathFlags::AllowReciprocal;
1282     if (FPMO->hasAllowContract())
1283       Flags |= FastMathFlags::AllowContract;
1284   }
1285 
1286   return Flags;
1287 }
1288 
1289 void ModuleBitcodeWriter::writeValueAsMetadata(
1290     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1291   // Mimic an MDNode with a value as one operand.
1292   Value *V = MD->getValue();
1293   Record.push_back(VE.getTypeID(V->getType()));
1294   Record.push_back(VE.getValueID(V));
1295   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1296   Record.clear();
1297 }
1298 
1299 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1300                                        SmallVectorImpl<uint64_t> &Record,
1301                                        unsigned Abbrev) {
1302   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1303     Metadata *MD = N->getOperand(i);
1304     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1305            "Unexpected function-local metadata");
1306     Record.push_back(VE.getMetadataOrNullID(MD));
1307   }
1308   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1309                                     : bitc::METADATA_NODE,
1310                     Record, Abbrev);
1311   Record.clear();
1312 }
1313 
1314 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1315   // Assume the column is usually under 128, and always output the inlined-at
1316   // location (it's never more expensive than building an array size 1).
1317   auto Abbv = std::make_shared<BitCodeAbbrev>();
1318   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1319   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1320   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1321   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1322   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1324   return Stream.EmitAbbrev(std::move(Abbv));
1325 }
1326 
1327 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1328                                           SmallVectorImpl<uint64_t> &Record,
1329                                           unsigned &Abbrev) {
1330   if (!Abbrev)
1331     Abbrev = createDILocationAbbrev();
1332 
1333   Record.push_back(N->isDistinct());
1334   Record.push_back(N->getLine());
1335   Record.push_back(N->getColumn());
1336   Record.push_back(VE.getMetadataID(N->getScope()));
1337   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1338 
1339   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1340   Record.clear();
1341 }
1342 
1343 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1344   // Assume the column is usually under 128, and always output the inlined-at
1345   // location (it's never more expensive than building an array size 1).
1346   auto Abbv = std::make_shared<BitCodeAbbrev>();
1347   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1348   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1349   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1350   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1351   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1352   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1353   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1354   return Stream.EmitAbbrev(std::move(Abbv));
1355 }
1356 
1357 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1358                                              SmallVectorImpl<uint64_t> &Record,
1359                                              unsigned &Abbrev) {
1360   if (!Abbrev)
1361     Abbrev = createGenericDINodeAbbrev();
1362 
1363   Record.push_back(N->isDistinct());
1364   Record.push_back(N->getTag());
1365   Record.push_back(0); // Per-tag version field; unused for now.
1366 
1367   for (auto &I : N->operands())
1368     Record.push_back(VE.getMetadataOrNullID(I));
1369 
1370   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1371   Record.clear();
1372 }
1373 
1374 static uint64_t rotateSign(int64_t I) {
1375   uint64_t U = I;
1376   return I < 0 ? ~(U << 1) : U << 1;
1377 }
1378 
1379 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1380                                           SmallVectorImpl<uint64_t> &Record,
1381                                           unsigned Abbrev) {
1382   Record.push_back(N->isDistinct());
1383   Record.push_back(N->getCount());
1384   Record.push_back(rotateSign(N->getLowerBound()));
1385 
1386   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1387   Record.clear();
1388 }
1389 
1390 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1391                                             SmallVectorImpl<uint64_t> &Record,
1392                                             unsigned Abbrev) {
1393   Record.push_back(N->isDistinct());
1394   Record.push_back(rotateSign(N->getValue()));
1395   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1396 
1397   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1398   Record.clear();
1399 }
1400 
1401 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1402                                            SmallVectorImpl<uint64_t> &Record,
1403                                            unsigned Abbrev) {
1404   Record.push_back(N->isDistinct());
1405   Record.push_back(N->getTag());
1406   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1407   Record.push_back(N->getSizeInBits());
1408   Record.push_back(N->getAlignInBits());
1409   Record.push_back(N->getEncoding());
1410 
1411   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1412   Record.clear();
1413 }
1414 
1415 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1416                                              SmallVectorImpl<uint64_t> &Record,
1417                                              unsigned Abbrev) {
1418   Record.push_back(N->isDistinct());
1419   Record.push_back(N->getTag());
1420   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1421   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1422   Record.push_back(N->getLine());
1423   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1424   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1425   Record.push_back(N->getSizeInBits());
1426   Record.push_back(N->getAlignInBits());
1427   Record.push_back(N->getOffsetInBits());
1428   Record.push_back(N->getFlags());
1429   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1430 
1431   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1432   // that there is no DWARF address space associated with DIDerivedType.
1433   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1434     Record.push_back(*DWARFAddressSpace + 1);
1435   else
1436     Record.push_back(0);
1437 
1438   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1439   Record.clear();
1440 }
1441 
1442 void ModuleBitcodeWriter::writeDICompositeType(
1443     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1444     unsigned Abbrev) {
1445   const unsigned IsNotUsedInOldTypeRef = 0x2;
1446   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1447   Record.push_back(N->getTag());
1448   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1449   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1450   Record.push_back(N->getLine());
1451   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1452   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1453   Record.push_back(N->getSizeInBits());
1454   Record.push_back(N->getAlignInBits());
1455   Record.push_back(N->getOffsetInBits());
1456   Record.push_back(N->getFlags());
1457   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1458   Record.push_back(N->getRuntimeLang());
1459   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1460   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1461   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1462 
1463   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1464   Record.clear();
1465 }
1466 
1467 void ModuleBitcodeWriter::writeDISubroutineType(
1468     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1469     unsigned Abbrev) {
1470   const unsigned HasNoOldTypeRefs = 0x2;
1471   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1472   Record.push_back(N->getFlags());
1473   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1474   Record.push_back(N->getCC());
1475 
1476   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1477   Record.clear();
1478 }
1479 
1480 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1481                                       SmallVectorImpl<uint64_t> &Record,
1482                                       unsigned Abbrev) {
1483   Record.push_back(N->isDistinct());
1484   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1485   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1486   Record.push_back(N->getChecksumKind());
1487   Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()));
1488 
1489   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1490   Record.clear();
1491 }
1492 
1493 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1494                                              SmallVectorImpl<uint64_t> &Record,
1495                                              unsigned Abbrev) {
1496   assert(N->isDistinct() && "Expected distinct compile units");
1497   Record.push_back(/* IsDistinct */ true);
1498   Record.push_back(N->getSourceLanguage());
1499   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1500   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1501   Record.push_back(N->isOptimized());
1502   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1503   Record.push_back(N->getRuntimeVersion());
1504   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1505   Record.push_back(N->getEmissionKind());
1506   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1507   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1508   Record.push_back(/* subprograms */ 0);
1509   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1510   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1511   Record.push_back(N->getDWOId());
1512   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1513   Record.push_back(N->getSplitDebugInlining());
1514   Record.push_back(N->getDebugInfoForProfiling());
1515 
1516   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1517   Record.clear();
1518 }
1519 
1520 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1521                                             SmallVectorImpl<uint64_t> &Record,
1522                                             unsigned Abbrev) {
1523   uint64_t HasUnitFlag = 1 << 1;
1524   Record.push_back(N->isDistinct() | HasUnitFlag);
1525   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1526   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1527   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1528   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1529   Record.push_back(N->getLine());
1530   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1531   Record.push_back(N->isLocalToUnit());
1532   Record.push_back(N->isDefinition());
1533   Record.push_back(N->getScopeLine());
1534   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1535   Record.push_back(N->getVirtuality());
1536   Record.push_back(N->getVirtualIndex());
1537   Record.push_back(N->getFlags());
1538   Record.push_back(N->isOptimized());
1539   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1540   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1541   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1542   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1543   Record.push_back(N->getThisAdjustment());
1544   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1545 
1546   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1547   Record.clear();
1548 }
1549 
1550 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1551                                               SmallVectorImpl<uint64_t> &Record,
1552                                               unsigned Abbrev) {
1553   Record.push_back(N->isDistinct());
1554   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1555   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1556   Record.push_back(N->getLine());
1557   Record.push_back(N->getColumn());
1558 
1559   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1560   Record.clear();
1561 }
1562 
1563 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1564     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1565     unsigned Abbrev) {
1566   Record.push_back(N->isDistinct());
1567   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1568   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1569   Record.push_back(N->getDiscriminator());
1570 
1571   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1572   Record.clear();
1573 }
1574 
1575 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1576                                            SmallVectorImpl<uint64_t> &Record,
1577                                            unsigned Abbrev) {
1578   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1579   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1580   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1581 
1582   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1583   Record.clear();
1584 }
1585 
1586 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1587                                        SmallVectorImpl<uint64_t> &Record,
1588                                        unsigned Abbrev) {
1589   Record.push_back(N->isDistinct());
1590   Record.push_back(N->getMacinfoType());
1591   Record.push_back(N->getLine());
1592   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1593   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1594 
1595   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1596   Record.clear();
1597 }
1598 
1599 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1600                                            SmallVectorImpl<uint64_t> &Record,
1601                                            unsigned Abbrev) {
1602   Record.push_back(N->isDistinct());
1603   Record.push_back(N->getMacinfoType());
1604   Record.push_back(N->getLine());
1605   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1606   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1607 
1608   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1609   Record.clear();
1610 }
1611 
1612 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1613                                         SmallVectorImpl<uint64_t> &Record,
1614                                         unsigned Abbrev) {
1615   Record.push_back(N->isDistinct());
1616   for (auto &I : N->operands())
1617     Record.push_back(VE.getMetadataOrNullID(I));
1618 
1619   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1620   Record.clear();
1621 }
1622 
1623 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1624     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1625     unsigned Abbrev) {
1626   Record.push_back(N->isDistinct());
1627   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1628   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1629 
1630   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1631   Record.clear();
1632 }
1633 
1634 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1635     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1636     unsigned Abbrev) {
1637   Record.push_back(N->isDistinct());
1638   Record.push_back(N->getTag());
1639   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1640   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1641   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1642 
1643   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1644   Record.clear();
1645 }
1646 
1647 void ModuleBitcodeWriter::writeDIGlobalVariable(
1648     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1649     unsigned Abbrev) {
1650   const uint64_t Version = 1 << 1;
1651   Record.push_back((uint64_t)N->isDistinct() | Version);
1652   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1653   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1654   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1655   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1656   Record.push_back(N->getLine());
1657   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1658   Record.push_back(N->isLocalToUnit());
1659   Record.push_back(N->isDefinition());
1660   Record.push_back(/* expr */ 0);
1661   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1662   Record.push_back(N->getAlignInBits());
1663 
1664   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1665   Record.clear();
1666 }
1667 
1668 void ModuleBitcodeWriter::writeDILocalVariable(
1669     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1670     unsigned Abbrev) {
1671   // In order to support all possible bitcode formats in BitcodeReader we need
1672   // to distinguish the following cases:
1673   // 1) Record has no artificial tag (Record[1]),
1674   //   has no obsolete inlinedAt field (Record[9]).
1675   //   In this case Record size will be 8, HasAlignment flag is false.
1676   // 2) Record has artificial tag (Record[1]),
1677   //   has no obsolete inlignedAt field (Record[9]).
1678   //   In this case Record size will be 9, HasAlignment flag is false.
1679   // 3) Record has both artificial tag (Record[1]) and
1680   //   obsolete inlignedAt field (Record[9]).
1681   //   In this case Record size will be 10, HasAlignment flag is false.
1682   // 4) Record has neither artificial tag, nor inlignedAt field, but
1683   //   HasAlignment flag is true and Record[8] contains alignment value.
1684   const uint64_t HasAlignmentFlag = 1 << 1;
1685   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1686   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1687   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1688   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1689   Record.push_back(N->getLine());
1690   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1691   Record.push_back(N->getArg());
1692   Record.push_back(N->getFlags());
1693   Record.push_back(N->getAlignInBits());
1694 
1695   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1696   Record.clear();
1697 }
1698 
1699 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1700                                             SmallVectorImpl<uint64_t> &Record,
1701                                             unsigned Abbrev) {
1702   Record.reserve(N->getElements().size() + 1);
1703   const uint64_t Version = 3 << 1;
1704   Record.push_back((uint64_t)N->isDistinct() | Version);
1705   Record.append(N->elements_begin(), N->elements_end());
1706 
1707   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1708   Record.clear();
1709 }
1710 
1711 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1712     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1713     unsigned Abbrev) {
1714   Record.push_back(N->isDistinct());
1715   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1716   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1717 
1718   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1719   Record.clear();
1720 }
1721 
1722 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1723                                               SmallVectorImpl<uint64_t> &Record,
1724                                               unsigned Abbrev) {
1725   Record.push_back(N->isDistinct());
1726   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1727   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1728   Record.push_back(N->getLine());
1729   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1730   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1731   Record.push_back(N->getAttributes());
1732   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1733 
1734   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1735   Record.clear();
1736 }
1737 
1738 void ModuleBitcodeWriter::writeDIImportedEntity(
1739     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1740     unsigned Abbrev) {
1741   Record.push_back(N->isDistinct());
1742   Record.push_back(N->getTag());
1743   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1744   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1745   Record.push_back(N->getLine());
1746   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1747   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1748 
1749   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1750   Record.clear();
1751 }
1752 
1753 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1754   auto Abbv = std::make_shared<BitCodeAbbrev>();
1755   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1756   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1757   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1758   return Stream.EmitAbbrev(std::move(Abbv));
1759 }
1760 
1761 void ModuleBitcodeWriter::writeNamedMetadata(
1762     SmallVectorImpl<uint64_t> &Record) {
1763   if (M.named_metadata_empty())
1764     return;
1765 
1766   unsigned Abbrev = createNamedMetadataAbbrev();
1767   for (const NamedMDNode &NMD : M.named_metadata()) {
1768     // Write name.
1769     StringRef Str = NMD.getName();
1770     Record.append(Str.bytes_begin(), Str.bytes_end());
1771     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1772     Record.clear();
1773 
1774     // Write named metadata operands.
1775     for (const MDNode *N : NMD.operands())
1776       Record.push_back(VE.getMetadataID(N));
1777     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1778     Record.clear();
1779   }
1780 }
1781 
1782 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1783   auto Abbv = std::make_shared<BitCodeAbbrev>();
1784   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1785   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1786   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1787   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1788   return Stream.EmitAbbrev(std::move(Abbv));
1789 }
1790 
1791 /// Write out a record for MDString.
1792 ///
1793 /// All the metadata strings in a metadata block are emitted in a single
1794 /// record.  The sizes and strings themselves are shoved into a blob.
1795 void ModuleBitcodeWriter::writeMetadataStrings(
1796     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1797   if (Strings.empty())
1798     return;
1799 
1800   // Start the record with the number of strings.
1801   Record.push_back(bitc::METADATA_STRINGS);
1802   Record.push_back(Strings.size());
1803 
1804   // Emit the sizes of the strings in the blob.
1805   SmallString<256> Blob;
1806   {
1807     BitstreamWriter W(Blob);
1808     for (const Metadata *MD : Strings)
1809       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1810     W.FlushToWord();
1811   }
1812 
1813   // Add the offset to the strings to the record.
1814   Record.push_back(Blob.size());
1815 
1816   // Add the strings to the blob.
1817   for (const Metadata *MD : Strings)
1818     Blob.append(cast<MDString>(MD)->getString());
1819 
1820   // Emit the final record.
1821   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1822   Record.clear();
1823 }
1824 
1825 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1826 enum MetadataAbbrev : unsigned {
1827 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1828 #include "llvm/IR/Metadata.def"
1829   LastPlusOne
1830 };
1831 
1832 void ModuleBitcodeWriter::writeMetadataRecords(
1833     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1834     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1835   if (MDs.empty())
1836     return;
1837 
1838   // Initialize MDNode abbreviations.
1839 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1840 #include "llvm/IR/Metadata.def"
1841 
1842   for (const Metadata *MD : MDs) {
1843     if (IndexPos)
1844       IndexPos->push_back(Stream.GetCurrentBitNo());
1845     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1846       assert(N->isResolved() && "Expected forward references to be resolved");
1847 
1848       switch (N->getMetadataID()) {
1849       default:
1850         llvm_unreachable("Invalid MDNode subclass");
1851 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1852   case Metadata::CLASS##Kind:                                                  \
1853     if (MDAbbrevs)                                                             \
1854       write##CLASS(cast<CLASS>(N), Record,                                     \
1855                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1856     else                                                                       \
1857       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1858     continue;
1859 #include "llvm/IR/Metadata.def"
1860       }
1861     }
1862     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1863   }
1864 }
1865 
1866 void ModuleBitcodeWriter::writeModuleMetadata() {
1867   if (!VE.hasMDs() && M.named_metadata_empty())
1868     return;
1869 
1870   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1871   SmallVector<uint64_t, 64> Record;
1872 
1873   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1874   // block and load any metadata.
1875   std::vector<unsigned> MDAbbrevs;
1876 
1877   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1878   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1879   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1880       createGenericDINodeAbbrev();
1881 
1882   auto Abbv = std::make_shared<BitCodeAbbrev>();
1883   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1884   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1885   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1886   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1887 
1888   Abbv = std::make_shared<BitCodeAbbrev>();
1889   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1890   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1891   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1892   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1893 
1894   // Emit MDStrings together upfront.
1895   writeMetadataStrings(VE.getMDStrings(), Record);
1896 
1897   // We only emit an index for the metadata record if we have more than a given
1898   // (naive) threshold of metadatas, otherwise it is not worth it.
1899   if (VE.getNonMDStrings().size() > IndexThreshold) {
1900     // Write a placeholder value in for the offset of the metadata index,
1901     // which is written after the records, so that it can include
1902     // the offset of each entry. The placeholder offset will be
1903     // updated after all records are emitted.
1904     uint64_t Vals[] = {0, 0};
1905     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
1906   }
1907 
1908   // Compute and save the bit offset to the current position, which will be
1909   // patched when we emit the index later. We can simply subtract the 64-bit
1910   // fixed size from the current bit number to get the location to backpatch.
1911   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
1912 
1913   // This index will contain the bitpos for each individual record.
1914   std::vector<uint64_t> IndexPos;
1915   IndexPos.reserve(VE.getNonMDStrings().size());
1916 
1917   // Write all the records
1918   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
1919 
1920   if (VE.getNonMDStrings().size() > IndexThreshold) {
1921     // Now that we have emitted all the records we will emit the index. But
1922     // first
1923     // backpatch the forward reference so that the reader can skip the records
1924     // efficiently.
1925     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
1926                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
1927 
1928     // Delta encode the index.
1929     uint64_t PreviousValue = IndexOffsetRecordBitPos;
1930     for (auto &Elt : IndexPos) {
1931       auto EltDelta = Elt - PreviousValue;
1932       PreviousValue = Elt;
1933       Elt = EltDelta;
1934     }
1935     // Emit the index record.
1936     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
1937     IndexPos.clear();
1938   }
1939 
1940   // Write the named metadata now.
1941   writeNamedMetadata(Record);
1942 
1943   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
1944     SmallVector<uint64_t, 4> Record;
1945     Record.push_back(VE.getValueID(&GO));
1946     pushGlobalMetadataAttachment(Record, GO);
1947     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
1948   };
1949   for (const Function &F : M)
1950     if (F.isDeclaration() && F.hasMetadata())
1951       AddDeclAttachedMetadata(F);
1952   // FIXME: Only store metadata for declarations here, and move data for global
1953   // variable definitions to a separate block (PR28134).
1954   for (const GlobalVariable &GV : M.globals())
1955     if (GV.hasMetadata())
1956       AddDeclAttachedMetadata(GV);
1957 
1958   Stream.ExitBlock();
1959 }
1960 
1961 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
1962   if (!VE.hasMDs())
1963     return;
1964 
1965   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1966   SmallVector<uint64_t, 64> Record;
1967   writeMetadataStrings(VE.getMDStrings(), Record);
1968   writeMetadataRecords(VE.getNonMDStrings(), Record);
1969   Stream.ExitBlock();
1970 }
1971 
1972 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
1973     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
1974   // [n x [id, mdnode]]
1975   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1976   GO.getAllMetadata(MDs);
1977   for (const auto &I : MDs) {
1978     Record.push_back(I.first);
1979     Record.push_back(VE.getMetadataID(I.second));
1980   }
1981 }
1982 
1983 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
1984   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1985 
1986   SmallVector<uint64_t, 64> Record;
1987 
1988   if (F.hasMetadata()) {
1989     pushGlobalMetadataAttachment(Record, F);
1990     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1991     Record.clear();
1992   }
1993 
1994   // Write metadata attachments
1995   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1996   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1997   for (const BasicBlock &BB : F)
1998     for (const Instruction &I : BB) {
1999       MDs.clear();
2000       I.getAllMetadataOtherThanDebugLoc(MDs);
2001 
2002       // If no metadata, ignore instruction.
2003       if (MDs.empty()) continue;
2004 
2005       Record.push_back(VE.getInstructionID(&I));
2006 
2007       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2008         Record.push_back(MDs[i].first);
2009         Record.push_back(VE.getMetadataID(MDs[i].second));
2010       }
2011       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2012       Record.clear();
2013     }
2014 
2015   Stream.ExitBlock();
2016 }
2017 
2018 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2019   SmallVector<uint64_t, 64> Record;
2020 
2021   // Write metadata kinds
2022   // METADATA_KIND - [n x [id, name]]
2023   SmallVector<StringRef, 8> Names;
2024   M.getMDKindNames(Names);
2025 
2026   if (Names.empty()) return;
2027 
2028   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2029 
2030   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2031     Record.push_back(MDKindID);
2032     StringRef KName = Names[MDKindID];
2033     Record.append(KName.begin(), KName.end());
2034 
2035     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2036     Record.clear();
2037   }
2038 
2039   Stream.ExitBlock();
2040 }
2041 
2042 void ModuleBitcodeWriter::writeOperandBundleTags() {
2043   // Write metadata kinds
2044   //
2045   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2046   //
2047   // OPERAND_BUNDLE_TAG - [strchr x N]
2048 
2049   SmallVector<StringRef, 8> Tags;
2050   M.getOperandBundleTags(Tags);
2051 
2052   if (Tags.empty())
2053     return;
2054 
2055   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2056 
2057   SmallVector<uint64_t, 64> Record;
2058 
2059   for (auto Tag : Tags) {
2060     Record.append(Tag.begin(), Tag.end());
2061 
2062     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2063     Record.clear();
2064   }
2065 
2066   Stream.ExitBlock();
2067 }
2068 
2069 void ModuleBitcodeWriter::writeSyncScopeNames() {
2070   SmallVector<StringRef, 8> SSNs;
2071   M.getContext().getSyncScopeNames(SSNs);
2072   if (SSNs.empty())
2073     return;
2074 
2075   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2076 
2077   SmallVector<uint64_t, 64> Record;
2078   for (auto SSN : SSNs) {
2079     Record.append(SSN.begin(), SSN.end());
2080     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2081     Record.clear();
2082   }
2083 
2084   Stream.ExitBlock();
2085 }
2086 
2087 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2088   if ((int64_t)V >= 0)
2089     Vals.push_back(V << 1);
2090   else
2091     Vals.push_back((-V << 1) | 1);
2092 }
2093 
2094 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2095                                          bool isGlobal) {
2096   if (FirstVal == LastVal) return;
2097 
2098   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2099 
2100   unsigned AggregateAbbrev = 0;
2101   unsigned String8Abbrev = 0;
2102   unsigned CString7Abbrev = 0;
2103   unsigned CString6Abbrev = 0;
2104   // If this is a constant pool for the module, emit module-specific abbrevs.
2105   if (isGlobal) {
2106     // Abbrev for CST_CODE_AGGREGATE.
2107     auto Abbv = std::make_shared<BitCodeAbbrev>();
2108     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2109     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2110     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2111     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2112 
2113     // Abbrev for CST_CODE_STRING.
2114     Abbv = std::make_shared<BitCodeAbbrev>();
2115     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2116     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2117     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2118     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2119     // Abbrev for CST_CODE_CSTRING.
2120     Abbv = std::make_shared<BitCodeAbbrev>();
2121     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2122     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2123     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2124     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2125     // Abbrev for CST_CODE_CSTRING.
2126     Abbv = std::make_shared<BitCodeAbbrev>();
2127     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2128     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2129     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2130     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2131   }
2132 
2133   SmallVector<uint64_t, 64> Record;
2134 
2135   const ValueEnumerator::ValueList &Vals = VE.getValues();
2136   Type *LastTy = nullptr;
2137   for (unsigned i = FirstVal; i != LastVal; ++i) {
2138     const Value *V = Vals[i].first;
2139     // If we need to switch types, do so now.
2140     if (V->getType() != LastTy) {
2141       LastTy = V->getType();
2142       Record.push_back(VE.getTypeID(LastTy));
2143       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2144                         CONSTANTS_SETTYPE_ABBREV);
2145       Record.clear();
2146     }
2147 
2148     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2149       Record.push_back(unsigned(IA->hasSideEffects()) |
2150                        unsigned(IA->isAlignStack()) << 1 |
2151                        unsigned(IA->getDialect()&1) << 2);
2152 
2153       // Add the asm string.
2154       const std::string &AsmStr = IA->getAsmString();
2155       Record.push_back(AsmStr.size());
2156       Record.append(AsmStr.begin(), AsmStr.end());
2157 
2158       // Add the constraint string.
2159       const std::string &ConstraintStr = IA->getConstraintString();
2160       Record.push_back(ConstraintStr.size());
2161       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2162       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2163       Record.clear();
2164       continue;
2165     }
2166     const Constant *C = cast<Constant>(V);
2167     unsigned Code = -1U;
2168     unsigned AbbrevToUse = 0;
2169     if (C->isNullValue()) {
2170       Code = bitc::CST_CODE_NULL;
2171     } else if (isa<UndefValue>(C)) {
2172       Code = bitc::CST_CODE_UNDEF;
2173     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2174       if (IV->getBitWidth() <= 64) {
2175         uint64_t V = IV->getSExtValue();
2176         emitSignedInt64(Record, V);
2177         Code = bitc::CST_CODE_INTEGER;
2178         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2179       } else {                             // Wide integers, > 64 bits in size.
2180         // We have an arbitrary precision integer value to write whose
2181         // bit width is > 64. However, in canonical unsigned integer
2182         // format it is likely that the high bits are going to be zero.
2183         // So, we only write the number of active words.
2184         unsigned NWords = IV->getValue().getActiveWords();
2185         const uint64_t *RawWords = IV->getValue().getRawData();
2186         for (unsigned i = 0; i != NWords; ++i) {
2187           emitSignedInt64(Record, RawWords[i]);
2188         }
2189         Code = bitc::CST_CODE_WIDE_INTEGER;
2190       }
2191     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2192       Code = bitc::CST_CODE_FLOAT;
2193       Type *Ty = CFP->getType();
2194       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2195         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2196       } else if (Ty->isX86_FP80Ty()) {
2197         // api needed to prevent premature destruction
2198         // bits are not in the same order as a normal i80 APInt, compensate.
2199         APInt api = CFP->getValueAPF().bitcastToAPInt();
2200         const uint64_t *p = api.getRawData();
2201         Record.push_back((p[1] << 48) | (p[0] >> 16));
2202         Record.push_back(p[0] & 0xffffLL);
2203       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2204         APInt api = CFP->getValueAPF().bitcastToAPInt();
2205         const uint64_t *p = api.getRawData();
2206         Record.push_back(p[0]);
2207         Record.push_back(p[1]);
2208       } else {
2209         assert (0 && "Unknown FP type!");
2210       }
2211     } else if (isa<ConstantDataSequential>(C) &&
2212                cast<ConstantDataSequential>(C)->isString()) {
2213       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2214       // Emit constant strings specially.
2215       unsigned NumElts = Str->getNumElements();
2216       // If this is a null-terminated string, use the denser CSTRING encoding.
2217       if (Str->isCString()) {
2218         Code = bitc::CST_CODE_CSTRING;
2219         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2220       } else {
2221         Code = bitc::CST_CODE_STRING;
2222         AbbrevToUse = String8Abbrev;
2223       }
2224       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2225       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2226       for (unsigned i = 0; i != NumElts; ++i) {
2227         unsigned char V = Str->getElementAsInteger(i);
2228         Record.push_back(V);
2229         isCStr7 &= (V & 128) == 0;
2230         if (isCStrChar6)
2231           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2232       }
2233 
2234       if (isCStrChar6)
2235         AbbrevToUse = CString6Abbrev;
2236       else if (isCStr7)
2237         AbbrevToUse = CString7Abbrev;
2238     } else if (const ConstantDataSequential *CDS =
2239                   dyn_cast<ConstantDataSequential>(C)) {
2240       Code = bitc::CST_CODE_DATA;
2241       Type *EltTy = CDS->getType()->getElementType();
2242       if (isa<IntegerType>(EltTy)) {
2243         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2244           Record.push_back(CDS->getElementAsInteger(i));
2245       } else {
2246         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2247           Record.push_back(
2248               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2249       }
2250     } else if (isa<ConstantAggregate>(C)) {
2251       Code = bitc::CST_CODE_AGGREGATE;
2252       for (const Value *Op : C->operands())
2253         Record.push_back(VE.getValueID(Op));
2254       AbbrevToUse = AggregateAbbrev;
2255     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2256       switch (CE->getOpcode()) {
2257       default:
2258         if (Instruction::isCast(CE->getOpcode())) {
2259           Code = bitc::CST_CODE_CE_CAST;
2260           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2261           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2262           Record.push_back(VE.getValueID(C->getOperand(0)));
2263           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2264         } else {
2265           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2266           Code = bitc::CST_CODE_CE_BINOP;
2267           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2268           Record.push_back(VE.getValueID(C->getOperand(0)));
2269           Record.push_back(VE.getValueID(C->getOperand(1)));
2270           uint64_t Flags = getOptimizationFlags(CE);
2271           if (Flags != 0)
2272             Record.push_back(Flags);
2273         }
2274         break;
2275       case Instruction::GetElementPtr: {
2276         Code = bitc::CST_CODE_CE_GEP;
2277         const auto *GO = cast<GEPOperator>(C);
2278         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2279         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2280           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2281           Record.push_back((*Idx << 1) | GO->isInBounds());
2282         } else if (GO->isInBounds())
2283           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2284         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2285           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2286           Record.push_back(VE.getValueID(C->getOperand(i)));
2287         }
2288         break;
2289       }
2290       case Instruction::Select:
2291         Code = bitc::CST_CODE_CE_SELECT;
2292         Record.push_back(VE.getValueID(C->getOperand(0)));
2293         Record.push_back(VE.getValueID(C->getOperand(1)));
2294         Record.push_back(VE.getValueID(C->getOperand(2)));
2295         break;
2296       case Instruction::ExtractElement:
2297         Code = bitc::CST_CODE_CE_EXTRACTELT;
2298         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2299         Record.push_back(VE.getValueID(C->getOperand(0)));
2300         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2301         Record.push_back(VE.getValueID(C->getOperand(1)));
2302         break;
2303       case Instruction::InsertElement:
2304         Code = bitc::CST_CODE_CE_INSERTELT;
2305         Record.push_back(VE.getValueID(C->getOperand(0)));
2306         Record.push_back(VE.getValueID(C->getOperand(1)));
2307         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2308         Record.push_back(VE.getValueID(C->getOperand(2)));
2309         break;
2310       case Instruction::ShuffleVector:
2311         // If the return type and argument types are the same, this is a
2312         // standard shufflevector instruction.  If the types are different,
2313         // then the shuffle is widening or truncating the input vectors, and
2314         // the argument type must also be encoded.
2315         if (C->getType() == C->getOperand(0)->getType()) {
2316           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2317         } else {
2318           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2319           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2320         }
2321         Record.push_back(VE.getValueID(C->getOperand(0)));
2322         Record.push_back(VE.getValueID(C->getOperand(1)));
2323         Record.push_back(VE.getValueID(C->getOperand(2)));
2324         break;
2325       case Instruction::ICmp:
2326       case Instruction::FCmp:
2327         Code = bitc::CST_CODE_CE_CMP;
2328         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2329         Record.push_back(VE.getValueID(C->getOperand(0)));
2330         Record.push_back(VE.getValueID(C->getOperand(1)));
2331         Record.push_back(CE->getPredicate());
2332         break;
2333       }
2334     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2335       Code = bitc::CST_CODE_BLOCKADDRESS;
2336       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2337       Record.push_back(VE.getValueID(BA->getFunction()));
2338       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2339     } else {
2340 #ifndef NDEBUG
2341       C->dump();
2342 #endif
2343       llvm_unreachable("Unknown constant!");
2344     }
2345     Stream.EmitRecord(Code, Record, AbbrevToUse);
2346     Record.clear();
2347   }
2348 
2349   Stream.ExitBlock();
2350 }
2351 
2352 void ModuleBitcodeWriter::writeModuleConstants() {
2353   const ValueEnumerator::ValueList &Vals = VE.getValues();
2354 
2355   // Find the first constant to emit, which is the first non-globalvalue value.
2356   // We know globalvalues have been emitted by WriteModuleInfo.
2357   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2358     if (!isa<GlobalValue>(Vals[i].first)) {
2359       writeConstants(i, Vals.size(), true);
2360       return;
2361     }
2362   }
2363 }
2364 
2365 /// pushValueAndType - The file has to encode both the value and type id for
2366 /// many values, because we need to know what type to create for forward
2367 /// references.  However, most operands are not forward references, so this type
2368 /// field is not needed.
2369 ///
2370 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2371 /// instruction ID, then it is a forward reference, and it also includes the
2372 /// type ID.  The value ID that is written is encoded relative to the InstID.
2373 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2374                                            SmallVectorImpl<unsigned> &Vals) {
2375   unsigned ValID = VE.getValueID(V);
2376   // Make encoding relative to the InstID.
2377   Vals.push_back(InstID - ValID);
2378   if (ValID >= InstID) {
2379     Vals.push_back(VE.getTypeID(V->getType()));
2380     return true;
2381   }
2382   return false;
2383 }
2384 
2385 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2386                                               unsigned InstID) {
2387   SmallVector<unsigned, 64> Record;
2388   LLVMContext &C = CS.getInstruction()->getContext();
2389 
2390   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2391     const auto &Bundle = CS.getOperandBundleAt(i);
2392     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2393 
2394     for (auto &Input : Bundle.Inputs)
2395       pushValueAndType(Input, InstID, Record);
2396 
2397     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2398     Record.clear();
2399   }
2400 }
2401 
2402 /// pushValue - Like pushValueAndType, but where the type of the value is
2403 /// omitted (perhaps it was already encoded in an earlier operand).
2404 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2405                                     SmallVectorImpl<unsigned> &Vals) {
2406   unsigned ValID = VE.getValueID(V);
2407   Vals.push_back(InstID - ValID);
2408 }
2409 
2410 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2411                                           SmallVectorImpl<uint64_t> &Vals) {
2412   unsigned ValID = VE.getValueID(V);
2413   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2414   emitSignedInt64(Vals, diff);
2415 }
2416 
2417 /// WriteInstruction - Emit an instruction to the specified stream.
2418 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2419                                            unsigned InstID,
2420                                            SmallVectorImpl<unsigned> &Vals) {
2421   unsigned Code = 0;
2422   unsigned AbbrevToUse = 0;
2423   VE.setInstructionID(&I);
2424   switch (I.getOpcode()) {
2425   default:
2426     if (Instruction::isCast(I.getOpcode())) {
2427       Code = bitc::FUNC_CODE_INST_CAST;
2428       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2429         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2430       Vals.push_back(VE.getTypeID(I.getType()));
2431       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2432     } else {
2433       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2434       Code = bitc::FUNC_CODE_INST_BINOP;
2435       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2436         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2437       pushValue(I.getOperand(1), InstID, Vals);
2438       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2439       uint64_t Flags = getOptimizationFlags(&I);
2440       if (Flags != 0) {
2441         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2442           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2443         Vals.push_back(Flags);
2444       }
2445     }
2446     break;
2447 
2448   case Instruction::GetElementPtr: {
2449     Code = bitc::FUNC_CODE_INST_GEP;
2450     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2451     auto &GEPInst = cast<GetElementPtrInst>(I);
2452     Vals.push_back(GEPInst.isInBounds());
2453     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2454     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2455       pushValueAndType(I.getOperand(i), InstID, Vals);
2456     break;
2457   }
2458   case Instruction::ExtractValue: {
2459     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2460     pushValueAndType(I.getOperand(0), InstID, Vals);
2461     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2462     Vals.append(EVI->idx_begin(), EVI->idx_end());
2463     break;
2464   }
2465   case Instruction::InsertValue: {
2466     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2467     pushValueAndType(I.getOperand(0), InstID, Vals);
2468     pushValueAndType(I.getOperand(1), InstID, Vals);
2469     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2470     Vals.append(IVI->idx_begin(), IVI->idx_end());
2471     break;
2472   }
2473   case Instruction::Select:
2474     Code = bitc::FUNC_CODE_INST_VSELECT;
2475     pushValueAndType(I.getOperand(1), InstID, Vals);
2476     pushValue(I.getOperand(2), InstID, Vals);
2477     pushValueAndType(I.getOperand(0), InstID, Vals);
2478     break;
2479   case Instruction::ExtractElement:
2480     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2481     pushValueAndType(I.getOperand(0), InstID, Vals);
2482     pushValueAndType(I.getOperand(1), InstID, Vals);
2483     break;
2484   case Instruction::InsertElement:
2485     Code = bitc::FUNC_CODE_INST_INSERTELT;
2486     pushValueAndType(I.getOperand(0), InstID, Vals);
2487     pushValue(I.getOperand(1), InstID, Vals);
2488     pushValueAndType(I.getOperand(2), InstID, Vals);
2489     break;
2490   case Instruction::ShuffleVector:
2491     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2492     pushValueAndType(I.getOperand(0), InstID, Vals);
2493     pushValue(I.getOperand(1), InstID, Vals);
2494     pushValue(I.getOperand(2), InstID, Vals);
2495     break;
2496   case Instruction::ICmp:
2497   case Instruction::FCmp: {
2498     // compare returning Int1Ty or vector of Int1Ty
2499     Code = bitc::FUNC_CODE_INST_CMP2;
2500     pushValueAndType(I.getOperand(0), InstID, Vals);
2501     pushValue(I.getOperand(1), InstID, Vals);
2502     Vals.push_back(cast<CmpInst>(I).getPredicate());
2503     uint64_t Flags = getOptimizationFlags(&I);
2504     if (Flags != 0)
2505       Vals.push_back(Flags);
2506     break;
2507   }
2508 
2509   case Instruction::Ret:
2510     {
2511       Code = bitc::FUNC_CODE_INST_RET;
2512       unsigned NumOperands = I.getNumOperands();
2513       if (NumOperands == 0)
2514         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2515       else if (NumOperands == 1) {
2516         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2517           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2518       } else {
2519         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2520           pushValueAndType(I.getOperand(i), InstID, Vals);
2521       }
2522     }
2523     break;
2524   case Instruction::Br:
2525     {
2526       Code = bitc::FUNC_CODE_INST_BR;
2527       const BranchInst &II = cast<BranchInst>(I);
2528       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2529       if (II.isConditional()) {
2530         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2531         pushValue(II.getCondition(), InstID, Vals);
2532       }
2533     }
2534     break;
2535   case Instruction::Switch:
2536     {
2537       Code = bitc::FUNC_CODE_INST_SWITCH;
2538       const SwitchInst &SI = cast<SwitchInst>(I);
2539       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2540       pushValue(SI.getCondition(), InstID, Vals);
2541       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2542       for (auto Case : SI.cases()) {
2543         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2544         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2545       }
2546     }
2547     break;
2548   case Instruction::IndirectBr:
2549     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2550     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2551     // Encode the address operand as relative, but not the basic blocks.
2552     pushValue(I.getOperand(0), InstID, Vals);
2553     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2554       Vals.push_back(VE.getValueID(I.getOperand(i)));
2555     break;
2556 
2557   case Instruction::Invoke: {
2558     const InvokeInst *II = cast<InvokeInst>(&I);
2559     const Value *Callee = II->getCalledValue();
2560     FunctionType *FTy = II->getFunctionType();
2561 
2562     if (II->hasOperandBundles())
2563       writeOperandBundles(II, InstID);
2564 
2565     Code = bitc::FUNC_CODE_INST_INVOKE;
2566 
2567     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2568     Vals.push_back(II->getCallingConv() | 1 << 13);
2569     Vals.push_back(VE.getValueID(II->getNormalDest()));
2570     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2571     Vals.push_back(VE.getTypeID(FTy));
2572     pushValueAndType(Callee, InstID, Vals);
2573 
2574     // Emit value #'s for the fixed parameters.
2575     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2576       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2577 
2578     // Emit type/value pairs for varargs params.
2579     if (FTy->isVarArg()) {
2580       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2581            i != e; ++i)
2582         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2583     }
2584     break;
2585   }
2586   case Instruction::Resume:
2587     Code = bitc::FUNC_CODE_INST_RESUME;
2588     pushValueAndType(I.getOperand(0), InstID, Vals);
2589     break;
2590   case Instruction::CleanupRet: {
2591     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2592     const auto &CRI = cast<CleanupReturnInst>(I);
2593     pushValue(CRI.getCleanupPad(), InstID, Vals);
2594     if (CRI.hasUnwindDest())
2595       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2596     break;
2597   }
2598   case Instruction::CatchRet: {
2599     Code = bitc::FUNC_CODE_INST_CATCHRET;
2600     const auto &CRI = cast<CatchReturnInst>(I);
2601     pushValue(CRI.getCatchPad(), InstID, Vals);
2602     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2603     break;
2604   }
2605   case Instruction::CleanupPad:
2606   case Instruction::CatchPad: {
2607     const auto &FuncletPad = cast<FuncletPadInst>(I);
2608     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2609                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2610     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2611 
2612     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2613     Vals.push_back(NumArgOperands);
2614     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2615       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2616     break;
2617   }
2618   case Instruction::CatchSwitch: {
2619     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2620     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2621 
2622     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2623 
2624     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2625     Vals.push_back(NumHandlers);
2626     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2627       Vals.push_back(VE.getValueID(CatchPadBB));
2628 
2629     if (CatchSwitch.hasUnwindDest())
2630       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2631     break;
2632   }
2633   case Instruction::Unreachable:
2634     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2635     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2636     break;
2637 
2638   case Instruction::PHI: {
2639     const PHINode &PN = cast<PHINode>(I);
2640     Code = bitc::FUNC_CODE_INST_PHI;
2641     // With the newer instruction encoding, forward references could give
2642     // negative valued IDs.  This is most common for PHIs, so we use
2643     // signed VBRs.
2644     SmallVector<uint64_t, 128> Vals64;
2645     Vals64.push_back(VE.getTypeID(PN.getType()));
2646     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2647       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2648       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2649     }
2650     // Emit a Vals64 vector and exit.
2651     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2652     Vals64.clear();
2653     return;
2654   }
2655 
2656   case Instruction::LandingPad: {
2657     const LandingPadInst &LP = cast<LandingPadInst>(I);
2658     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2659     Vals.push_back(VE.getTypeID(LP.getType()));
2660     Vals.push_back(LP.isCleanup());
2661     Vals.push_back(LP.getNumClauses());
2662     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2663       if (LP.isCatch(I))
2664         Vals.push_back(LandingPadInst::Catch);
2665       else
2666         Vals.push_back(LandingPadInst::Filter);
2667       pushValueAndType(LP.getClause(I), InstID, Vals);
2668     }
2669     break;
2670   }
2671 
2672   case Instruction::Alloca: {
2673     Code = bitc::FUNC_CODE_INST_ALLOCA;
2674     const AllocaInst &AI = cast<AllocaInst>(I);
2675     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2676     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2677     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2678     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2679     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2680            "not enough bits for maximum alignment");
2681     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2682     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2683     AlignRecord |= 1 << 6;
2684     AlignRecord |= AI.isSwiftError() << 7;
2685     Vals.push_back(AlignRecord);
2686     break;
2687   }
2688 
2689   case Instruction::Load:
2690     if (cast<LoadInst>(I).isAtomic()) {
2691       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2692       pushValueAndType(I.getOperand(0), InstID, Vals);
2693     } else {
2694       Code = bitc::FUNC_CODE_INST_LOAD;
2695       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2696         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2697     }
2698     Vals.push_back(VE.getTypeID(I.getType()));
2699     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2700     Vals.push_back(cast<LoadInst>(I).isVolatile());
2701     if (cast<LoadInst>(I).isAtomic()) {
2702       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2703       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2704     }
2705     break;
2706   case Instruction::Store:
2707     if (cast<StoreInst>(I).isAtomic())
2708       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2709     else
2710       Code = bitc::FUNC_CODE_INST_STORE;
2711     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2712     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2713     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2714     Vals.push_back(cast<StoreInst>(I).isVolatile());
2715     if (cast<StoreInst>(I).isAtomic()) {
2716       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2717       Vals.push_back(
2718           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2719     }
2720     break;
2721   case Instruction::AtomicCmpXchg:
2722     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2723     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2724     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2725     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2726     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2727     Vals.push_back(
2728         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2729     Vals.push_back(
2730         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2731     Vals.push_back(
2732         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2733     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2734     break;
2735   case Instruction::AtomicRMW:
2736     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2737     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2738     pushValue(I.getOperand(1), InstID, Vals);        // val.
2739     Vals.push_back(
2740         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2741     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2742     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2743     Vals.push_back(
2744         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2745     break;
2746   case Instruction::Fence:
2747     Code = bitc::FUNC_CODE_INST_FENCE;
2748     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2749     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2750     break;
2751   case Instruction::Call: {
2752     const CallInst &CI = cast<CallInst>(I);
2753     FunctionType *FTy = CI.getFunctionType();
2754 
2755     if (CI.hasOperandBundles())
2756       writeOperandBundles(&CI, InstID);
2757 
2758     Code = bitc::FUNC_CODE_INST_CALL;
2759 
2760     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2761 
2762     unsigned Flags = getOptimizationFlags(&I);
2763     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2764                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2765                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2766                    1 << bitc::CALL_EXPLICIT_TYPE |
2767                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2768                    unsigned(Flags != 0) << bitc::CALL_FMF);
2769     if (Flags != 0)
2770       Vals.push_back(Flags);
2771 
2772     Vals.push_back(VE.getTypeID(FTy));
2773     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2774 
2775     // Emit value #'s for the fixed parameters.
2776     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2777       // Check for labels (can happen with asm labels).
2778       if (FTy->getParamType(i)->isLabelTy())
2779         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2780       else
2781         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2782     }
2783 
2784     // Emit type/value pairs for varargs params.
2785     if (FTy->isVarArg()) {
2786       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2787            i != e; ++i)
2788         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2789     }
2790     break;
2791   }
2792   case Instruction::VAArg:
2793     Code = bitc::FUNC_CODE_INST_VAARG;
2794     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2795     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2796     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2797     break;
2798   }
2799 
2800   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2801   Vals.clear();
2802 }
2803 
2804 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2805 /// to allow clients to efficiently find the function body.
2806 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2807   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2808   // Get the offset of the VST we are writing, and backpatch it into
2809   // the VST forward declaration record.
2810   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2811   // The BitcodeStartBit was the stream offset of the identification block.
2812   VSTOffset -= bitcodeStartBit();
2813   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2814   // Note that we add 1 here because the offset is relative to one word
2815   // before the start of the identification block, which was historically
2816   // always the start of the regular bitcode header.
2817   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2818 
2819   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2820 
2821   auto Abbv = std::make_shared<BitCodeAbbrev>();
2822   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2823   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2824   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2825   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2826 
2827   for (const Function &F : M) {
2828     uint64_t Record[2];
2829 
2830     if (F.isDeclaration())
2831       continue;
2832 
2833     Record[0] = VE.getValueID(&F);
2834 
2835     // Save the word offset of the function (from the start of the
2836     // actual bitcode written to the stream).
2837     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2838     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2839     // Note that we add 1 here because the offset is relative to one word
2840     // before the start of the identification block, which was historically
2841     // always the start of the regular bitcode header.
2842     Record[1] = BitcodeIndex / 32 + 1;
2843 
2844     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2845   }
2846 
2847   Stream.ExitBlock();
2848 }
2849 
2850 /// Emit names for arguments, instructions and basic blocks in a function.
2851 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2852     const ValueSymbolTable &VST) {
2853   if (VST.empty())
2854     return;
2855 
2856   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2857 
2858   // FIXME: Set up the abbrev, we know how many values there are!
2859   // FIXME: We know if the type names can use 7-bit ascii.
2860   SmallVector<uint64_t, 64> NameVals;
2861 
2862   for (const ValueName &Name : VST) {
2863     // Figure out the encoding to use for the name.
2864     StringEncoding Bits = getStringEncoding(Name.getKey());
2865 
2866     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2867     NameVals.push_back(VE.getValueID(Name.getValue()));
2868 
2869     // VST_CODE_ENTRY:   [valueid, namechar x N]
2870     // VST_CODE_BBENTRY: [bbid, namechar x N]
2871     unsigned Code;
2872     if (isa<BasicBlock>(Name.getValue())) {
2873       Code = bitc::VST_CODE_BBENTRY;
2874       if (Bits == SE_Char6)
2875         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2876     } else {
2877       Code = bitc::VST_CODE_ENTRY;
2878       if (Bits == SE_Char6)
2879         AbbrevToUse = VST_ENTRY_6_ABBREV;
2880       else if (Bits == SE_Fixed7)
2881         AbbrevToUse = VST_ENTRY_7_ABBREV;
2882     }
2883 
2884     for (const auto P : Name.getKey())
2885       NameVals.push_back((unsigned char)P);
2886 
2887     // Emit the finished record.
2888     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2889     NameVals.clear();
2890   }
2891 
2892   Stream.ExitBlock();
2893 }
2894 
2895 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
2896   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2897   unsigned Code;
2898   if (isa<BasicBlock>(Order.V))
2899     Code = bitc::USELIST_CODE_BB;
2900   else
2901     Code = bitc::USELIST_CODE_DEFAULT;
2902 
2903   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2904   Record.push_back(VE.getValueID(Order.V));
2905   Stream.EmitRecord(Code, Record);
2906 }
2907 
2908 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
2909   assert(VE.shouldPreserveUseListOrder() &&
2910          "Expected to be preserving use-list order");
2911 
2912   auto hasMore = [&]() {
2913     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2914   };
2915   if (!hasMore())
2916     // Nothing to do.
2917     return;
2918 
2919   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2920   while (hasMore()) {
2921     writeUseList(std::move(VE.UseListOrders.back()));
2922     VE.UseListOrders.pop_back();
2923   }
2924   Stream.ExitBlock();
2925 }
2926 
2927 /// Emit a function body to the module stream.
2928 void ModuleBitcodeWriter::writeFunction(
2929     const Function &F,
2930     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2931   // Save the bitcode index of the start of this function block for recording
2932   // in the VST.
2933   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
2934 
2935   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2936   VE.incorporateFunction(F);
2937 
2938   SmallVector<unsigned, 64> Vals;
2939 
2940   // Emit the number of basic blocks, so the reader can create them ahead of
2941   // time.
2942   Vals.push_back(VE.getBasicBlocks().size());
2943   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2944   Vals.clear();
2945 
2946   // If there are function-local constants, emit them now.
2947   unsigned CstStart, CstEnd;
2948   VE.getFunctionConstantRange(CstStart, CstEnd);
2949   writeConstants(CstStart, CstEnd, false);
2950 
2951   // If there is function-local metadata, emit it now.
2952   writeFunctionMetadata(F);
2953 
2954   // Keep a running idea of what the instruction ID is.
2955   unsigned InstID = CstEnd;
2956 
2957   bool NeedsMetadataAttachment = F.hasMetadata();
2958 
2959   DILocation *LastDL = nullptr;
2960   // Finally, emit all the instructions, in order.
2961   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2962     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2963          I != E; ++I) {
2964       writeInstruction(*I, InstID, Vals);
2965 
2966       if (!I->getType()->isVoidTy())
2967         ++InstID;
2968 
2969       // If the instruction has metadata, write a metadata attachment later.
2970       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2971 
2972       // If the instruction has a debug location, emit it.
2973       DILocation *DL = I->getDebugLoc();
2974       if (!DL)
2975         continue;
2976 
2977       if (DL == LastDL) {
2978         // Just repeat the same debug loc as last time.
2979         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2980         continue;
2981       }
2982 
2983       Vals.push_back(DL->getLine());
2984       Vals.push_back(DL->getColumn());
2985       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2986       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2987       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2988       Vals.clear();
2989 
2990       LastDL = DL;
2991     }
2992 
2993   // Emit names for all the instructions etc.
2994   if (auto *Symtab = F.getValueSymbolTable())
2995     writeFunctionLevelValueSymbolTable(*Symtab);
2996 
2997   if (NeedsMetadataAttachment)
2998     writeFunctionMetadataAttachment(F);
2999   if (VE.shouldPreserveUseListOrder())
3000     writeUseListBlock(&F);
3001   VE.purgeFunction();
3002   Stream.ExitBlock();
3003 }
3004 
3005 // Emit blockinfo, which defines the standard abbreviations etc.
3006 void ModuleBitcodeWriter::writeBlockInfo() {
3007   // We only want to emit block info records for blocks that have multiple
3008   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3009   // Other blocks can define their abbrevs inline.
3010   Stream.EnterBlockInfoBlock();
3011 
3012   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3013     auto Abbv = std::make_shared<BitCodeAbbrev>();
3014     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3015     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3016     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3017     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3018     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3019         VST_ENTRY_8_ABBREV)
3020       llvm_unreachable("Unexpected abbrev ordering!");
3021   }
3022 
3023   { // 7-bit fixed width VST_CODE_ENTRY strings.
3024     auto Abbv = std::make_shared<BitCodeAbbrev>();
3025     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3026     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3027     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3028     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3029     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3030         VST_ENTRY_7_ABBREV)
3031       llvm_unreachable("Unexpected abbrev ordering!");
3032   }
3033   { // 6-bit char6 VST_CODE_ENTRY strings.
3034     auto Abbv = std::make_shared<BitCodeAbbrev>();
3035     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3036     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3037     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3038     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3039     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3040         VST_ENTRY_6_ABBREV)
3041       llvm_unreachable("Unexpected abbrev ordering!");
3042   }
3043   { // 6-bit char6 VST_CODE_BBENTRY strings.
3044     auto Abbv = std::make_shared<BitCodeAbbrev>();
3045     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3046     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3047     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3048     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3049     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3050         VST_BBENTRY_6_ABBREV)
3051       llvm_unreachable("Unexpected abbrev ordering!");
3052   }
3053 
3054 
3055 
3056   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3057     auto Abbv = std::make_shared<BitCodeAbbrev>();
3058     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3059     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3060                               VE.computeBitsRequiredForTypeIndicies()));
3061     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3062         CONSTANTS_SETTYPE_ABBREV)
3063       llvm_unreachable("Unexpected abbrev ordering!");
3064   }
3065 
3066   { // INTEGER abbrev for CONSTANTS_BLOCK.
3067     auto Abbv = std::make_shared<BitCodeAbbrev>();
3068     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3069     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3070     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3071         CONSTANTS_INTEGER_ABBREV)
3072       llvm_unreachable("Unexpected abbrev ordering!");
3073   }
3074 
3075   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3076     auto Abbv = std::make_shared<BitCodeAbbrev>();
3077     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3078     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3079     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3080                               VE.computeBitsRequiredForTypeIndicies()));
3081     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3082 
3083     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3084         CONSTANTS_CE_CAST_Abbrev)
3085       llvm_unreachable("Unexpected abbrev ordering!");
3086   }
3087   { // NULL abbrev for CONSTANTS_BLOCK.
3088     auto Abbv = std::make_shared<BitCodeAbbrev>();
3089     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3090     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3091         CONSTANTS_NULL_Abbrev)
3092       llvm_unreachable("Unexpected abbrev ordering!");
3093   }
3094 
3095   // FIXME: This should only use space for first class types!
3096 
3097   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3098     auto Abbv = std::make_shared<BitCodeAbbrev>();
3099     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3100     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3101     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3102                               VE.computeBitsRequiredForTypeIndicies()));
3103     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3104     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3105     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3106         FUNCTION_INST_LOAD_ABBREV)
3107       llvm_unreachable("Unexpected abbrev ordering!");
3108   }
3109   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3110     auto Abbv = std::make_shared<BitCodeAbbrev>();
3111     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3112     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3113     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3114     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3115     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3116         FUNCTION_INST_BINOP_ABBREV)
3117       llvm_unreachable("Unexpected abbrev ordering!");
3118   }
3119   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3120     auto Abbv = std::make_shared<BitCodeAbbrev>();
3121     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3122     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3123     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3125     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
3126     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3127         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3128       llvm_unreachable("Unexpected abbrev ordering!");
3129   }
3130   { // INST_CAST abbrev for FUNCTION_BLOCK.
3131     auto Abbv = std::make_shared<BitCodeAbbrev>();
3132     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3134     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3135                               VE.computeBitsRequiredForTypeIndicies()));
3136     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3137     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3138         FUNCTION_INST_CAST_ABBREV)
3139       llvm_unreachable("Unexpected abbrev ordering!");
3140   }
3141 
3142   { // INST_RET abbrev for FUNCTION_BLOCK.
3143     auto Abbv = std::make_shared<BitCodeAbbrev>();
3144     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3145     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3146         FUNCTION_INST_RET_VOID_ABBREV)
3147       llvm_unreachable("Unexpected abbrev ordering!");
3148   }
3149   { // INST_RET abbrev for FUNCTION_BLOCK.
3150     auto Abbv = std::make_shared<BitCodeAbbrev>();
3151     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3153     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3154         FUNCTION_INST_RET_VAL_ABBREV)
3155       llvm_unreachable("Unexpected abbrev ordering!");
3156   }
3157   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3158     auto Abbv = std::make_shared<BitCodeAbbrev>();
3159     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3160     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3161         FUNCTION_INST_UNREACHABLE_ABBREV)
3162       llvm_unreachable("Unexpected abbrev ordering!");
3163   }
3164   {
3165     auto Abbv = std::make_shared<BitCodeAbbrev>();
3166     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3167     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3168     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3169                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3170     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3171     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3172     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3173         FUNCTION_INST_GEP_ABBREV)
3174       llvm_unreachable("Unexpected abbrev ordering!");
3175   }
3176 
3177   Stream.ExitBlock();
3178 }
3179 
3180 /// Write the module path strings, currently only used when generating
3181 /// a combined index file.
3182 void IndexBitcodeWriter::writeModStrings() {
3183   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3184 
3185   // TODO: See which abbrev sizes we actually need to emit
3186 
3187   // 8-bit fixed-width MST_ENTRY strings.
3188   auto Abbv = std::make_shared<BitCodeAbbrev>();
3189   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3190   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3191   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3192   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3193   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3194 
3195   // 7-bit fixed width MST_ENTRY strings.
3196   Abbv = std::make_shared<BitCodeAbbrev>();
3197   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3198   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3199   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3200   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3201   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3202 
3203   // 6-bit char6 MST_ENTRY strings.
3204   Abbv = std::make_shared<BitCodeAbbrev>();
3205   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3206   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3207   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3208   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3209   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3210 
3211   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3212   Abbv = std::make_shared<BitCodeAbbrev>();
3213   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3214   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3215   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3216   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3217   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3218   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3219   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3220 
3221   SmallVector<unsigned, 64> Vals;
3222   forEachModule(
3223       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3224         StringRef Key = MPSE.getKey();
3225         const auto &Value = MPSE.getValue();
3226         StringEncoding Bits = getStringEncoding(Key);
3227         unsigned AbbrevToUse = Abbrev8Bit;
3228         if (Bits == SE_Char6)
3229           AbbrevToUse = Abbrev6Bit;
3230         else if (Bits == SE_Fixed7)
3231           AbbrevToUse = Abbrev7Bit;
3232 
3233         Vals.push_back(Value.first);
3234         Vals.append(Key.begin(), Key.end());
3235 
3236         // Emit the finished record.
3237         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3238 
3239         // Emit an optional hash for the module now
3240         const auto &Hash = Value.second;
3241         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3242           Vals.assign(Hash.begin(), Hash.end());
3243           // Emit the hash record.
3244           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3245         }
3246 
3247         Vals.clear();
3248       });
3249   Stream.ExitBlock();
3250 }
3251 
3252 /// Write the function type metadata related records that need to appear before
3253 /// a function summary entry (whether per-module or combined).
3254 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3255                                              FunctionSummary *FS) {
3256   if (!FS->type_tests().empty())
3257     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3258 
3259   SmallVector<uint64_t, 64> Record;
3260 
3261   auto WriteVFuncIdVec = [&](uint64_t Ty,
3262                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3263     if (VFs.empty())
3264       return;
3265     Record.clear();
3266     for (auto &VF : VFs) {
3267       Record.push_back(VF.GUID);
3268       Record.push_back(VF.Offset);
3269     }
3270     Stream.EmitRecord(Ty, Record);
3271   };
3272 
3273   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3274                   FS->type_test_assume_vcalls());
3275   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3276                   FS->type_checked_load_vcalls());
3277 
3278   auto WriteConstVCallVec = [&](uint64_t Ty,
3279                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3280     for (auto &VC : VCs) {
3281       Record.clear();
3282       Record.push_back(VC.VFunc.GUID);
3283       Record.push_back(VC.VFunc.Offset);
3284       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3285       Stream.EmitRecord(Ty, Record);
3286     }
3287   };
3288 
3289   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3290                      FS->type_test_assume_const_vcalls());
3291   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3292                      FS->type_checked_load_const_vcalls());
3293 }
3294 
3295 // Helper to emit a single function summary record.
3296 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3297     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3298     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3299     const Function &F) {
3300   NameVals.push_back(ValueID);
3301 
3302   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3303   writeFunctionTypeMetadataRecords(Stream, FS);
3304 
3305   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3306   NameVals.push_back(FS->instCount());
3307   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3308   NameVals.push_back(FS->refs().size());
3309 
3310   for (auto &RI : FS->refs())
3311     NameVals.push_back(VE.getValueID(RI.getValue()));
3312 
3313   bool HasProfileData = F.getEntryCount().hasValue();
3314   for (auto &ECI : FS->calls()) {
3315     NameVals.push_back(getValueId(ECI.first));
3316     if (HasProfileData)
3317       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3318   }
3319 
3320   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3321   unsigned Code =
3322       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
3323 
3324   // Emit the finished record.
3325   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3326   NameVals.clear();
3327 }
3328 
3329 // Collect the global value references in the given variable's initializer,
3330 // and emit them in a summary record.
3331 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3332     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3333     unsigned FSModRefsAbbrev) {
3334   auto VI = Index->getValueInfo(GlobalValue::getGUID(V.getName()));
3335   if (!VI || VI.getSummaryList().empty()) {
3336     // Only declarations should not have a summary (a declaration might however
3337     // have a summary if the def was in module level asm).
3338     assert(V.isDeclaration());
3339     return;
3340   }
3341   auto *Summary = VI.getSummaryList()[0].get();
3342   NameVals.push_back(VE.getValueID(&V));
3343   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3344   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3345 
3346   unsigned SizeBeforeRefs = NameVals.size();
3347   for (auto &RI : VS->refs())
3348     NameVals.push_back(VE.getValueID(RI.getValue()));
3349   // Sort the refs for determinism output, the vector returned by FS->refs() has
3350   // been initialized from a DenseSet.
3351   std::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3352 
3353   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3354                     FSModRefsAbbrev);
3355   NameVals.clear();
3356 }
3357 
3358 // Current version for the summary.
3359 // This is bumped whenever we introduce changes in the way some record are
3360 // interpreted, like flags for instance.
3361 static const uint64_t INDEX_VERSION = 4;
3362 
3363 /// Emit the per-module summary section alongside the rest of
3364 /// the module's bitcode.
3365 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3366   // By default we compile with ThinLTO if the module has a summary, but the
3367   // client can request full LTO with a module flag.
3368   bool IsThinLTO = true;
3369   if (auto *MD =
3370           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3371     IsThinLTO = MD->getZExtValue();
3372   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3373                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3374                        4);
3375 
3376   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3377 
3378   if (Index->begin() == Index->end()) {
3379     Stream.ExitBlock();
3380     return;
3381   }
3382 
3383   for (const auto &GVI : valueIds()) {
3384     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3385                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3386   }
3387 
3388   // Abbrev for FS_PERMODULE.
3389   auto Abbv = std::make_shared<BitCodeAbbrev>();
3390   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3391   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3392   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3393   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3394   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3395   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3396   // numrefs x valueid, n x (valueid)
3397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3399   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3400 
3401   // Abbrev for FS_PERMODULE_PROFILE.
3402   Abbv = std::make_shared<BitCodeAbbrev>();
3403   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3404   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3405   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3406   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3407   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3408   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3409   // numrefs x valueid, n x (valueid, hotness)
3410   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3411   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3412   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3413 
3414   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3415   Abbv = std::make_shared<BitCodeAbbrev>();
3416   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3417   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3418   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3419   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3420   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3421   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3422 
3423   // Abbrev for FS_ALIAS.
3424   Abbv = std::make_shared<BitCodeAbbrev>();
3425   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3426   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3427   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3428   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3429   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3430 
3431   SmallVector<uint64_t, 64> NameVals;
3432   // Iterate over the list of functions instead of the Index to
3433   // ensure the ordering is stable.
3434   for (const Function &F : M) {
3435     // Summary emission does not support anonymous functions, they have to
3436     // renamed using the anonymous function renaming pass.
3437     if (!F.hasName())
3438       report_fatal_error("Unexpected anonymous function when writing summary");
3439 
3440     ValueInfo VI = Index->getValueInfo(GlobalValue::getGUID(F.getName()));
3441     if (!VI || VI.getSummaryList().empty()) {
3442       // Only declarations should not have a summary (a declaration might
3443       // however have a summary if the def was in module level asm).
3444       assert(F.isDeclaration());
3445       continue;
3446     }
3447     auto *Summary = VI.getSummaryList()[0].get();
3448     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3449                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3450   }
3451 
3452   // Capture references from GlobalVariable initializers, which are outside
3453   // of a function scope.
3454   for (const GlobalVariable &G : M.globals())
3455     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3456 
3457   for (const GlobalAlias &A : M.aliases()) {
3458     auto *Aliasee = A.getBaseObject();
3459     if (!Aliasee->hasName())
3460       // Nameless function don't have an entry in the summary, skip it.
3461       continue;
3462     auto AliasId = VE.getValueID(&A);
3463     auto AliaseeId = VE.getValueID(Aliasee);
3464     NameVals.push_back(AliasId);
3465     auto *Summary = Index->getGlobalValueSummary(A);
3466     AliasSummary *AS = cast<AliasSummary>(Summary);
3467     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3468     NameVals.push_back(AliaseeId);
3469     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3470     NameVals.clear();
3471   }
3472 
3473   Stream.ExitBlock();
3474 }
3475 
3476 /// Emit the combined summary section into the combined index file.
3477 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3478   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3479   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3480 
3481   for (const auto &GVI : valueIds()) {
3482     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3483                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3484   }
3485 
3486   // Abbrev for FS_COMBINED.
3487   auto Abbv = std::make_shared<BitCodeAbbrev>();
3488   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3489   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3490   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3491   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3492   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3493   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3494   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3495   // numrefs x valueid, n x (valueid)
3496   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3497   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3498   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3499 
3500   // Abbrev for FS_COMBINED_PROFILE.
3501   Abbv = std::make_shared<BitCodeAbbrev>();
3502   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3503   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3504   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3505   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3506   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3507   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3508   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3509   // numrefs x valueid, n x (valueid, hotness)
3510   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3511   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3512   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3513 
3514   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3515   Abbv = std::make_shared<BitCodeAbbrev>();
3516   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3517   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3518   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3519   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3520   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3521   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3522   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3523 
3524   // Abbrev for FS_COMBINED_ALIAS.
3525   Abbv = std::make_shared<BitCodeAbbrev>();
3526   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3527   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3528   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3529   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3530   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3531   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3532 
3533   // The aliases are emitted as a post-pass, and will point to the value
3534   // id of the aliasee. Save them in a vector for post-processing.
3535   SmallVector<AliasSummary *, 64> Aliases;
3536 
3537   // Save the value id for each summary for alias emission.
3538   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3539 
3540   SmallVector<uint64_t, 64> NameVals;
3541 
3542   // For local linkage, we also emit the original name separately
3543   // immediately after the record.
3544   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3545     if (!GlobalValue::isLocalLinkage(S.linkage()))
3546       return;
3547     NameVals.push_back(S.getOriginalName());
3548     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3549     NameVals.clear();
3550   };
3551 
3552   forEachSummary([&](GVInfo I) {
3553     GlobalValueSummary *S = I.second;
3554     assert(S);
3555 
3556     auto ValueId = getValueId(I.first);
3557     assert(ValueId);
3558     SummaryToValueIdMap[S] = *ValueId;
3559 
3560     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3561       // Will process aliases as a post-pass because the reader wants all
3562       // global to be loaded first.
3563       Aliases.push_back(AS);
3564       return;
3565     }
3566 
3567     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3568       NameVals.push_back(*ValueId);
3569       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3570       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3571       for (auto &RI : VS->refs()) {
3572         auto RefValueId = getValueId(RI.getGUID());
3573         if (!RefValueId)
3574           continue;
3575         NameVals.push_back(*RefValueId);
3576       }
3577 
3578       // Emit the finished record.
3579       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3580                         FSModRefsAbbrev);
3581       NameVals.clear();
3582       MaybeEmitOriginalName(*S);
3583       return;
3584     }
3585 
3586     auto *FS = cast<FunctionSummary>(S);
3587     writeFunctionTypeMetadataRecords(Stream, FS);
3588 
3589     NameVals.push_back(*ValueId);
3590     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3591     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3592     NameVals.push_back(FS->instCount());
3593     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3594     // Fill in below
3595     NameVals.push_back(0);
3596 
3597     unsigned Count = 0;
3598     for (auto &RI : FS->refs()) {
3599       auto RefValueId = getValueId(RI.getGUID());
3600       if (!RefValueId)
3601         continue;
3602       NameVals.push_back(*RefValueId);
3603       Count++;
3604     }
3605     NameVals[5] = Count;
3606 
3607     bool HasProfileData = false;
3608     for (auto &EI : FS->calls()) {
3609       HasProfileData |= EI.second.Hotness != CalleeInfo::HotnessType::Unknown;
3610       if (HasProfileData)
3611         break;
3612     }
3613 
3614     for (auto &EI : FS->calls()) {
3615       // If this GUID doesn't have a value id, it doesn't have a function
3616       // summary and we don't need to record any calls to it.
3617       GlobalValue::GUID GUID = EI.first.getGUID();
3618       auto CallValueId = getValueId(GUID);
3619       if (!CallValueId) {
3620         // For SamplePGO, the indirect call targets for local functions will
3621         // have its original name annotated in profile. We try to find the
3622         // corresponding PGOFuncName as the GUID.
3623         GUID = Index.getGUIDFromOriginalID(GUID);
3624         if (GUID == 0)
3625           continue;
3626         CallValueId = getValueId(GUID);
3627         if (!CallValueId)
3628           continue;
3629         // The mapping from OriginalId to GUID may return a GUID
3630         // that corresponds to a static variable. Filter it out here.
3631         // This can happen when
3632         // 1) There is a call to a library function which does not have
3633         // a CallValidId;
3634         // 2) There is a static variable with the  OriginalGUID identical
3635         // to the GUID of the library function in 1);
3636         // When this happens, the logic for SamplePGO kicks in and
3637         // the static varible in 2) will be found, which needs to be
3638         // filtered out.
3639         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3640         if (GVSum &&
3641             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3642           continue;
3643       }
3644       NameVals.push_back(*CallValueId);
3645       if (HasProfileData)
3646         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3647     }
3648 
3649     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3650     unsigned Code =
3651         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3652 
3653     // Emit the finished record.
3654     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3655     NameVals.clear();
3656     MaybeEmitOriginalName(*S);
3657   });
3658 
3659   for (auto *AS : Aliases) {
3660     auto AliasValueId = SummaryToValueIdMap[AS];
3661     assert(AliasValueId);
3662     NameVals.push_back(AliasValueId);
3663     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3664     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3665     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3666     assert(AliaseeValueId);
3667     NameVals.push_back(AliaseeValueId);
3668 
3669     // Emit the finished record.
3670     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3671     NameVals.clear();
3672     MaybeEmitOriginalName(*AS);
3673   }
3674 
3675   if (!Index.cfiFunctionDefs().empty()) {
3676     for (auto &S : Index.cfiFunctionDefs()) {
3677       NameVals.push_back(StrtabBuilder.add(S));
3678       NameVals.push_back(S.size());
3679     }
3680     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3681     NameVals.clear();
3682   }
3683 
3684   if (!Index.cfiFunctionDecls().empty()) {
3685     for (auto &S : Index.cfiFunctionDecls()) {
3686       NameVals.push_back(StrtabBuilder.add(S));
3687       NameVals.push_back(S.size());
3688     }
3689     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3690     NameVals.clear();
3691   }
3692 
3693   Stream.ExitBlock();
3694 }
3695 
3696 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3697 /// current llvm version, and a record for the epoch number.
3698 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3699   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3700 
3701   // Write the "user readable" string identifying the bitcode producer
3702   auto Abbv = std::make_shared<BitCodeAbbrev>();
3703   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3704   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3705   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3706   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3707   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3708                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3709 
3710   // Write the epoch version
3711   Abbv = std::make_shared<BitCodeAbbrev>();
3712   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3713   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3714   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3715   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3716   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3717   Stream.ExitBlock();
3718 }
3719 
3720 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3721   // Emit the module's hash.
3722   // MODULE_CODE_HASH: [5*i32]
3723   if (GenerateHash) {
3724     uint32_t Vals[5];
3725     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3726                                     Buffer.size() - BlockStartPos));
3727     StringRef Hash = Hasher.result();
3728     for (int Pos = 0; Pos < 20; Pos += 4) {
3729       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3730     }
3731 
3732     // Emit the finished record.
3733     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3734 
3735     if (ModHash)
3736       // Save the written hash value.
3737       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3738   }
3739 }
3740 
3741 void ModuleBitcodeWriter::write() {
3742   writeIdentificationBlock(Stream);
3743 
3744   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3745   size_t BlockStartPos = Buffer.size();
3746 
3747   writeModuleVersion();
3748 
3749   // Emit blockinfo, which defines the standard abbreviations etc.
3750   writeBlockInfo();
3751 
3752   // Emit information about attribute groups.
3753   writeAttributeGroupTable();
3754 
3755   // Emit information about parameter attributes.
3756   writeAttributeTable();
3757 
3758   // Emit information describing all of the types in the module.
3759   writeTypeTable();
3760 
3761   writeComdats();
3762 
3763   // Emit top-level description of module, including target triple, inline asm,
3764   // descriptors for global variables, and function prototype info.
3765   writeModuleInfo();
3766 
3767   // Emit constants.
3768   writeModuleConstants();
3769 
3770   // Emit metadata kind names.
3771   writeModuleMetadataKinds();
3772 
3773   // Emit metadata.
3774   writeModuleMetadata();
3775 
3776   // Emit module-level use-lists.
3777   if (VE.shouldPreserveUseListOrder())
3778     writeUseListBlock(nullptr);
3779 
3780   writeOperandBundleTags();
3781   writeSyncScopeNames();
3782 
3783   // Emit function bodies.
3784   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3785   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3786     if (!F->isDeclaration())
3787       writeFunction(*F, FunctionToBitcodeIndex);
3788 
3789   // Need to write after the above call to WriteFunction which populates
3790   // the summary information in the index.
3791   if (Index)
3792     writePerModuleGlobalValueSummary();
3793 
3794   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3795 
3796   writeModuleHash(BlockStartPos);
3797 
3798   Stream.ExitBlock();
3799 }
3800 
3801 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3802                                uint32_t &Position) {
3803   support::endian::write32le(&Buffer[Position], Value);
3804   Position += 4;
3805 }
3806 
3807 /// If generating a bc file on darwin, we have to emit a
3808 /// header and trailer to make it compatible with the system archiver.  To do
3809 /// this we emit the following header, and then emit a trailer that pads the
3810 /// file out to be a multiple of 16 bytes.
3811 ///
3812 /// struct bc_header {
3813 ///   uint32_t Magic;         // 0x0B17C0DE
3814 ///   uint32_t Version;       // Version, currently always 0.
3815 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3816 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3817 ///   uint32_t CPUType;       // CPU specifier.
3818 ///   ... potentially more later ...
3819 /// };
3820 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3821                                          const Triple &TT) {
3822   unsigned CPUType = ~0U;
3823 
3824   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3825   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3826   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3827   // specific constants here because they are implicitly part of the Darwin ABI.
3828   enum {
3829     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3830     DARWIN_CPU_TYPE_X86        = 7,
3831     DARWIN_CPU_TYPE_ARM        = 12,
3832     DARWIN_CPU_TYPE_POWERPC    = 18
3833   };
3834 
3835   Triple::ArchType Arch = TT.getArch();
3836   if (Arch == Triple::x86_64)
3837     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3838   else if (Arch == Triple::x86)
3839     CPUType = DARWIN_CPU_TYPE_X86;
3840   else if (Arch == Triple::ppc)
3841     CPUType = DARWIN_CPU_TYPE_POWERPC;
3842   else if (Arch == Triple::ppc64)
3843     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3844   else if (Arch == Triple::arm || Arch == Triple::thumb)
3845     CPUType = DARWIN_CPU_TYPE_ARM;
3846 
3847   // Traditional Bitcode starts after header.
3848   assert(Buffer.size() >= BWH_HeaderSize &&
3849          "Expected header size to be reserved");
3850   unsigned BCOffset = BWH_HeaderSize;
3851   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3852 
3853   // Write the magic and version.
3854   unsigned Position = 0;
3855   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
3856   writeInt32ToBuffer(0, Buffer, Position); // Version.
3857   writeInt32ToBuffer(BCOffset, Buffer, Position);
3858   writeInt32ToBuffer(BCSize, Buffer, Position);
3859   writeInt32ToBuffer(CPUType, Buffer, Position);
3860 
3861   // If the file is not a multiple of 16 bytes, insert dummy padding.
3862   while (Buffer.size() & 15)
3863     Buffer.push_back(0);
3864 }
3865 
3866 /// Helper to write the header common to all bitcode files.
3867 static void writeBitcodeHeader(BitstreamWriter &Stream) {
3868   // Emit the file header.
3869   Stream.Emit((unsigned)'B', 8);
3870   Stream.Emit((unsigned)'C', 8);
3871   Stream.Emit(0x0, 4);
3872   Stream.Emit(0xC, 4);
3873   Stream.Emit(0xE, 4);
3874   Stream.Emit(0xD, 4);
3875 }
3876 
3877 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
3878     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
3879   writeBitcodeHeader(*Stream);
3880 }
3881 
3882 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
3883 
3884 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
3885   Stream->EnterSubblock(Block, 3);
3886 
3887   auto Abbv = std::make_shared<BitCodeAbbrev>();
3888   Abbv->Add(BitCodeAbbrevOp(Record));
3889   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
3890   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
3891 
3892   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
3893 
3894   Stream->ExitBlock();
3895 }
3896 
3897 void BitcodeWriter::writeSymtab() {
3898   assert(!WroteStrtab && !WroteSymtab);
3899 
3900   // If any module has module-level inline asm, we will require a registered asm
3901   // parser for the target so that we can create an accurate symbol table for
3902   // the module.
3903   for (Module *M : Mods) {
3904     if (M->getModuleInlineAsm().empty())
3905       continue;
3906 
3907     std::string Err;
3908     const Triple TT(M->getTargetTriple());
3909     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
3910     if (!T || !T->hasMCAsmParser())
3911       return;
3912   }
3913 
3914   WroteSymtab = true;
3915   SmallVector<char, 0> Symtab;
3916   // The irsymtab::build function may be unable to create a symbol table if the
3917   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
3918   // table is not required for correctness, but we still want to be able to
3919   // write malformed modules to bitcode files, so swallow the error.
3920   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
3921     consumeError(std::move(E));
3922     return;
3923   }
3924 
3925   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
3926             {Symtab.data(), Symtab.size()});
3927 }
3928 
3929 void BitcodeWriter::writeStrtab() {
3930   assert(!WroteStrtab);
3931 
3932   std::vector<char> Strtab;
3933   StrtabBuilder.finalizeInOrder();
3934   Strtab.resize(StrtabBuilder.getSize());
3935   StrtabBuilder.write((uint8_t *)Strtab.data());
3936 
3937   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
3938             {Strtab.data(), Strtab.size()});
3939 
3940   WroteStrtab = true;
3941 }
3942 
3943 void BitcodeWriter::copyStrtab(StringRef Strtab) {
3944   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
3945   WroteStrtab = true;
3946 }
3947 
3948 void BitcodeWriter::writeModule(const Module *M,
3949                                 bool ShouldPreserveUseListOrder,
3950                                 const ModuleSummaryIndex *Index,
3951                                 bool GenerateHash, ModuleHash *ModHash) {
3952   assert(!WroteStrtab);
3953 
3954   // The Mods vector is used by irsymtab::build, which requires non-const
3955   // Modules in case it needs to materialize metadata. But the bitcode writer
3956   // requires that the module is materialized, so we can cast to non-const here,
3957   // after checking that it is in fact materialized.
3958   assert(M->isMaterialized());
3959   Mods.push_back(const_cast<Module *>(M));
3960 
3961   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
3962                                    ShouldPreserveUseListOrder, Index,
3963                                    GenerateHash, ModHash);
3964   ModuleWriter.write();
3965 }
3966 
3967 void BitcodeWriter::writeIndex(
3968     const ModuleSummaryIndex *Index,
3969     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
3970   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
3971                                  ModuleToSummariesForIndex);
3972   IndexWriter.write();
3973 }
3974 
3975 /// WriteBitcodeToFile - Write the specified module to the specified output
3976 /// stream.
3977 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3978                               bool ShouldPreserveUseListOrder,
3979                               const ModuleSummaryIndex *Index,
3980                               bool GenerateHash, ModuleHash *ModHash) {
3981   SmallVector<char, 0> Buffer;
3982   Buffer.reserve(256*1024);
3983 
3984   // If this is darwin or another generic macho target, reserve space for the
3985   // header.
3986   Triple TT(M->getTargetTriple());
3987   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3988     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3989 
3990   BitcodeWriter Writer(Buffer);
3991   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
3992                      ModHash);
3993   Writer.writeSymtab();
3994   Writer.writeStrtab();
3995 
3996   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3997     emitDarwinBCHeaderAndTrailer(Buffer, TT);
3998 
3999   // Write the generated bitstream to "Out".
4000   Out.write((char*)&Buffer.front(), Buffer.size());
4001 }
4002 
4003 void IndexBitcodeWriter::write() {
4004   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4005 
4006   writeModuleVersion();
4007 
4008   // Write the module paths in the combined index.
4009   writeModStrings();
4010 
4011   // Write the summary combined index records.
4012   writeCombinedGlobalValueSummary();
4013 
4014   Stream.ExitBlock();
4015 }
4016 
4017 // Write the specified module summary index to the given raw output stream,
4018 // where it will be written in a new bitcode block. This is used when
4019 // writing the combined index file for ThinLTO. When writing a subset of the
4020 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4021 void llvm::WriteIndexToFile(
4022     const ModuleSummaryIndex &Index, raw_ostream &Out,
4023     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4024   SmallVector<char, 0> Buffer;
4025   Buffer.reserve(256 * 1024);
4026 
4027   BitcodeWriter Writer(Buffer);
4028   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4029   Writer.writeStrtab();
4030 
4031   Out.write((char *)&Buffer.front(), Buffer.size());
4032 }
4033 
4034 /// Class to manage the bitcode writing for a thin link bitcode file.
4035 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4036   /// ModHash is for use in ThinLTO incremental build, generated while writing
4037   /// the module bitcode file.
4038   const ModuleHash *ModHash;
4039 
4040 public:
4041   ThinLinkBitcodeWriter(const Module *M, StringTableBuilder &StrtabBuilder,
4042                         BitstreamWriter &Stream,
4043                         const ModuleSummaryIndex &Index,
4044                         const ModuleHash &ModHash)
4045       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4046                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4047         ModHash(&ModHash) {}
4048 
4049   void write();
4050 
4051 private:
4052   void writeSimplifiedModuleInfo();
4053 };
4054 
4055 // This function writes a simpilified module info for thin link bitcode file.
4056 // It only contains the source file name along with the name(the offset and
4057 // size in strtab) and linkage for global values. For the global value info
4058 // entry, in order to keep linkage at offset 5, there are three zeros used
4059 // as padding.
4060 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4061   SmallVector<unsigned, 64> Vals;
4062   // Emit the module's source file name.
4063   {
4064     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4065     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4066     if (Bits == SE_Char6)
4067       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4068     else if (Bits == SE_Fixed7)
4069       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4070 
4071     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4072     auto Abbv = std::make_shared<BitCodeAbbrev>();
4073     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4074     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4075     Abbv->Add(AbbrevOpToUse);
4076     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4077 
4078     for (const auto P : M.getSourceFileName())
4079       Vals.push_back((unsigned char)P);
4080 
4081     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4082     Vals.clear();
4083   }
4084 
4085   // Emit the global variable information.
4086   for (const GlobalVariable &GV : M.globals()) {
4087     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4088     Vals.push_back(StrtabBuilder.add(GV.getName()));
4089     Vals.push_back(GV.getName().size());
4090     Vals.push_back(0);
4091     Vals.push_back(0);
4092     Vals.push_back(0);
4093     Vals.push_back(getEncodedLinkage(GV));
4094 
4095     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4096     Vals.clear();
4097   }
4098 
4099   // Emit the function proto information.
4100   for (const Function &F : M) {
4101     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4102     Vals.push_back(StrtabBuilder.add(F.getName()));
4103     Vals.push_back(F.getName().size());
4104     Vals.push_back(0);
4105     Vals.push_back(0);
4106     Vals.push_back(0);
4107     Vals.push_back(getEncodedLinkage(F));
4108 
4109     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4110     Vals.clear();
4111   }
4112 
4113   // Emit the alias information.
4114   for (const GlobalAlias &A : M.aliases()) {
4115     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4116     Vals.push_back(StrtabBuilder.add(A.getName()));
4117     Vals.push_back(A.getName().size());
4118     Vals.push_back(0);
4119     Vals.push_back(0);
4120     Vals.push_back(0);
4121     Vals.push_back(getEncodedLinkage(A));
4122 
4123     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4124     Vals.clear();
4125   }
4126 
4127   // Emit the ifunc information.
4128   for (const GlobalIFunc &I : M.ifuncs()) {
4129     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4130     Vals.push_back(StrtabBuilder.add(I.getName()));
4131     Vals.push_back(I.getName().size());
4132     Vals.push_back(0);
4133     Vals.push_back(0);
4134     Vals.push_back(0);
4135     Vals.push_back(getEncodedLinkage(I));
4136 
4137     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4138     Vals.clear();
4139   }
4140 }
4141 
4142 void ThinLinkBitcodeWriter::write() {
4143   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4144 
4145   writeModuleVersion();
4146 
4147   writeSimplifiedModuleInfo();
4148 
4149   writePerModuleGlobalValueSummary();
4150 
4151   // Write module hash.
4152   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4153 
4154   Stream.ExitBlock();
4155 }
4156 
4157 void BitcodeWriter::writeThinLinkBitcode(const Module *M,
4158                                          const ModuleSummaryIndex &Index,
4159                                          const ModuleHash &ModHash) {
4160   assert(!WroteStrtab);
4161 
4162   // The Mods vector is used by irsymtab::build, which requires non-const
4163   // Modules in case it needs to materialize metadata. But the bitcode writer
4164   // requires that the module is materialized, so we can cast to non-const here,
4165   // after checking that it is in fact materialized.
4166   assert(M->isMaterialized());
4167   Mods.push_back(const_cast<Module *>(M));
4168 
4169   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4170                                        ModHash);
4171   ThinLinkWriter.write();
4172 }
4173 
4174 // Write the specified thin link bitcode file to the given raw output stream,
4175 // where it will be written in a new bitcode block. This is used when
4176 // writing the per-module index file for ThinLTO.
4177 void llvm::WriteThinLinkBitcodeToFile(const Module *M, raw_ostream &Out,
4178                                       const ModuleSummaryIndex &Index,
4179                                       const ModuleHash &ModHash) {
4180   SmallVector<char, 0> Buffer;
4181   Buffer.reserve(256 * 1024);
4182 
4183   BitcodeWriter Writer(Buffer);
4184   Writer.writeThinLinkBitcode(M, Index, ModHash);
4185   Writer.writeSymtab();
4186   Writer.writeStrtab();
4187 
4188   Out.write((char *)&Buffer.front(), Buffer.size());
4189 }
4190