xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 32ca14819848b362af9e1879f3811e68427f5279)
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/Support/ErrorHandling.h"
32 #include "llvm/Support/MathExtras.h"
33 #include "llvm/Support/Program.h"
34 #include "llvm/Support/SHA1.h"
35 #include "llvm/Support/raw_ostream.h"
36 #include <cctype>
37 #include <map>
38 using namespace llvm;
39 
40 namespace {
41 /// These are manifest constants used by the bitcode writer. They do not need to
42 /// be kept in sync with the reader, but need to be consistent within this file.
43 enum {
44   // VALUE_SYMTAB_BLOCK abbrev id's.
45   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
46   VST_ENTRY_7_ABBREV,
47   VST_ENTRY_6_ABBREV,
48   VST_BBENTRY_6_ABBREV,
49 
50   // CONSTANTS_BLOCK abbrev id's.
51   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
52   CONSTANTS_INTEGER_ABBREV,
53   CONSTANTS_CE_CAST_Abbrev,
54   CONSTANTS_NULL_Abbrev,
55 
56   // FUNCTION_BLOCK abbrev id's.
57   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
58   FUNCTION_INST_BINOP_ABBREV,
59   FUNCTION_INST_BINOP_FLAGS_ABBREV,
60   FUNCTION_INST_CAST_ABBREV,
61   FUNCTION_INST_RET_VOID_ABBREV,
62   FUNCTION_INST_RET_VAL_ABBREV,
63   FUNCTION_INST_UNREACHABLE_ABBREV,
64   FUNCTION_INST_GEP_ABBREV,
65 };
66 
67 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
68 /// file type.
69 class BitcodeWriterBase {
70 protected:
71   /// The stream created and owned by the client.
72   BitstreamWriter &Stream;
73 
74   /// Saves the offset of the VSTOffset record that must eventually be
75   /// backpatched with the offset of the actual VST.
76   uint64_t VSTOffsetPlaceholder = 0;
77 
78 public:
79   /// Constructs a BitcodeWriterBase object that writes to the provided
80   /// \p Stream.
81   BitcodeWriterBase(BitstreamWriter &Stream) : Stream(Stream) {}
82 
83 protected:
84   bool hasVSTOffsetPlaceholder() { return VSTOffsetPlaceholder != 0; }
85   void writeValueSymbolTableForwardDecl();
86   void writeBitcodeHeader();
87 };
88 
89 /// Class to manage the bitcode writing for a module.
90 class ModuleBitcodeWriter : public BitcodeWriterBase {
91   /// Pointer to the buffer allocated by caller for bitcode writing.
92   const SmallVectorImpl<char> &Buffer;
93 
94   /// The Module to write to bitcode.
95   const Module &M;
96 
97   /// Enumerates ids for all values in the module.
98   ValueEnumerator VE;
99 
100   /// Optional per-module index to write for ThinLTO.
101   const ModuleSummaryIndex *Index;
102 
103   /// True if a module hash record should be written.
104   bool GenerateHash;
105 
106   /// The start bit of the identification block.
107   uint64_t BitcodeStartBit;
108 
109   /// Map that holds the correspondence between GUIDs in the summary index,
110   /// that came from indirect call profiles, and a value id generated by this
111   /// class to use in the VST and summary block records.
112   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
113 
114   /// Tracks the last value id recorded in the GUIDToValueMap.
115   unsigned GlobalValueId;
116 
117 public:
118   /// Constructs a ModuleBitcodeWriter object for the given Module,
119   /// writing to the provided \p Buffer.
120   ModuleBitcodeWriter(const Module *M, SmallVectorImpl<char> &Buffer,
121                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
122                       const ModuleSummaryIndex *Index, bool GenerateHash)
123       : BitcodeWriterBase(Stream), Buffer(Buffer), M(*M),
124         VE(*M, ShouldPreserveUseListOrder), Index(Index),
125         GenerateHash(GenerateHash), BitcodeStartBit(Stream.GetCurrentBitNo()) {
126     // Assign ValueIds to any callee values in the index that came from
127     // indirect call profiles and were recorded as a GUID not a Value*
128     // (which would have been assigned an ID by the ValueEnumerator).
129     // The starting ValueId is just after the number of values in the
130     // ValueEnumerator, so that they can be emitted in the VST.
131     GlobalValueId = VE.getValues().size();
132     if (!Index)
133       return;
134     for (const auto &GUIDSummaryLists : *Index)
135       // Examine all summaries for this GUID.
136       for (auto &Summary : GUIDSummaryLists.second)
137         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
138           // For each call in the function summary, see if the call
139           // is to a GUID (which means it is for an indirect call,
140           // otherwise we would have a Value for it). If so, synthesize
141           // a value id.
142           for (auto &CallEdge : FS->calls())
143             if (CallEdge.first.isGUID())
144               assignValueId(CallEdge.first.getGUID());
145   }
146 
147   /// Emit the current module to the bitstream.
148   void write();
149 
150 private:
151   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
152 
153   void writeAttributeGroupTable();
154   void writeAttributeTable();
155   void writeTypeTable();
156   void writeComdats();
157   void writeModuleInfo();
158   void writeValueAsMetadata(const ValueAsMetadata *MD,
159                             SmallVectorImpl<uint64_t> &Record);
160   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
161                     unsigned Abbrev);
162   unsigned createDILocationAbbrev();
163   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
164                        unsigned &Abbrev);
165   unsigned createGenericDINodeAbbrev();
166   void writeGenericDINode(const GenericDINode *N,
167                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
168   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
169                        unsigned Abbrev);
170   void writeDIEnumerator(const DIEnumerator *N,
171                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
172   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
173                         unsigned Abbrev);
174   void writeDIDerivedType(const DIDerivedType *N,
175                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
176   void writeDICompositeType(const DICompositeType *N,
177                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
178   void writeDISubroutineType(const DISubroutineType *N,
179                              SmallVectorImpl<uint64_t> &Record,
180                              unsigned Abbrev);
181   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
182                    unsigned Abbrev);
183   void writeDICompileUnit(const DICompileUnit *N,
184                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
185   void writeDISubprogram(const DISubprogram *N,
186                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
187   void writeDILexicalBlock(const DILexicalBlock *N,
188                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
189   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
190                                SmallVectorImpl<uint64_t> &Record,
191                                unsigned Abbrev);
192   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
193                         unsigned Abbrev);
194   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
195                     unsigned Abbrev);
196   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
197                         unsigned Abbrev);
198   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
199                      unsigned Abbrev);
200   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
201                                     SmallVectorImpl<uint64_t> &Record,
202                                     unsigned Abbrev);
203   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
204                                      SmallVectorImpl<uint64_t> &Record,
205                                      unsigned Abbrev);
206   void writeDIGlobalVariable(const DIGlobalVariable *N,
207                              SmallVectorImpl<uint64_t> &Record,
208                              unsigned Abbrev);
209   void writeDILocalVariable(const DILocalVariable *N,
210                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
211   void writeDIExpression(const DIExpression *N,
212                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
213   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
214                                        SmallVectorImpl<uint64_t> &Record,
215                                        unsigned Abbrev);
216   void writeDIObjCProperty(const DIObjCProperty *N,
217                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
218   void writeDIImportedEntity(const DIImportedEntity *N,
219                              SmallVectorImpl<uint64_t> &Record,
220                              unsigned Abbrev);
221   unsigned createNamedMetadataAbbrev();
222   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
223   unsigned createMetadataStringsAbbrev();
224   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
225                             SmallVectorImpl<uint64_t> &Record);
226   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
227                             SmallVectorImpl<uint64_t> &Record,
228                             std::vector<unsigned> *MDAbbrevs = nullptr,
229                             std::vector<uint64_t> *IndexPos = nullptr);
230   void writeModuleMetadata();
231   void writeFunctionMetadata(const Function &F);
232   void writeFunctionMetadataAttachment(const Function &F);
233   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
234   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
235                                     const GlobalObject &GO);
236   void writeModuleMetadataKinds();
237   void writeOperandBundleTags();
238   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
239   void writeModuleConstants();
240   bool pushValueAndType(const Value *V, unsigned InstID,
241                         SmallVectorImpl<unsigned> &Vals);
242   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
243   void pushValue(const Value *V, unsigned InstID,
244                  SmallVectorImpl<unsigned> &Vals);
245   void pushValueSigned(const Value *V, unsigned InstID,
246                        SmallVectorImpl<uint64_t> &Vals);
247   void writeInstruction(const Instruction &I, unsigned InstID,
248                         SmallVectorImpl<unsigned> &Vals);
249   void writeValueSymbolTable(
250       const ValueSymbolTable &VST, bool IsModuleLevel = false,
251       DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex = nullptr);
252   void writeUseList(UseListOrder &&Order);
253   void writeUseListBlock(const Function *F);
254   void
255   writeFunction(const Function &F,
256                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
257   void writeBlockInfo();
258   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
259                                            GlobalValueSummary *Summary,
260                                            unsigned ValueID,
261                                            unsigned FSCallsAbbrev,
262                                            unsigned FSCallsProfileAbbrev,
263                                            const Function &F);
264   void writeModuleLevelReferences(const GlobalVariable &V,
265                                   SmallVector<uint64_t, 64> &NameVals,
266                                   unsigned FSModRefsAbbrev);
267   void writePerModuleGlobalValueSummary();
268   void writeModuleHash(size_t BlockStartPos);
269 
270   void assignValueId(GlobalValue::GUID ValGUID) {
271     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
272   }
273   unsigned getValueId(GlobalValue::GUID ValGUID) {
274     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
275     // Expect that any GUID value had a value Id assigned by an
276     // earlier call to assignValueId.
277     assert(VMI != GUIDToValueIdMap.end() &&
278            "GUID does not have assigned value Id");
279     return VMI->second;
280   }
281   // Helper to get the valueId for the type of value recorded in VI.
282   unsigned getValueId(ValueInfo VI) {
283     if (VI.isGUID())
284       return getValueId(VI.getGUID());
285     return VE.getValueID(VI.getValue());
286   }
287   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
288 };
289 
290 /// Class to manage the bitcode writing for a combined index.
291 class IndexBitcodeWriter : public BitcodeWriterBase {
292   /// The combined index to write to bitcode.
293   const ModuleSummaryIndex &Index;
294 
295   /// When writing a subset of the index for distributed backends, client
296   /// provides a map of modules to the corresponding GUIDs/summaries to write.
297   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
298 
299   /// Map that holds the correspondence between the GUID used in the combined
300   /// index and a value id generated by this class to use in references.
301   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
302 
303   /// Tracks the last value id recorded in the GUIDToValueMap.
304   unsigned GlobalValueId = 0;
305 
306 public:
307   /// Constructs a IndexBitcodeWriter object for the given combined index,
308   /// writing to the provided \p Buffer. When writing a subset of the index
309   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
310   IndexBitcodeWriter(BitstreamWriter &Stream, const ModuleSummaryIndex &Index,
311                      const std::map<std::string, GVSummaryMapTy>
312                          *ModuleToSummariesForIndex = nullptr)
313       : BitcodeWriterBase(Stream), Index(Index),
314         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
315     // Assign unique value ids to all summaries to be written, for use
316     // in writing out the call graph edges. Save the mapping from GUID
317     // to the new global value id to use when writing those edges, which
318     // are currently saved in the index in terms of GUID.
319     for (const auto &I : *this)
320       GUIDToValueIdMap[I.first] = ++GlobalValueId;
321   }
322 
323   /// The below iterator returns the GUID and associated summary.
324   typedef std::pair<GlobalValue::GUID, GlobalValueSummary *> GVInfo;
325 
326   /// Iterator over the value GUID and summaries to be written to bitcode,
327   /// hides the details of whether they are being pulled from the entire
328   /// index or just those in a provided ModuleToSummariesForIndex map.
329   class iterator
330       : public llvm::iterator_facade_base<iterator, std::forward_iterator_tag,
331                                           GVInfo> {
332     /// Enables access to parent class.
333     const IndexBitcodeWriter &Writer;
334 
335     // Iterators used when writing only those summaries in a provided
336     // ModuleToSummariesForIndex map:
337 
338     /// Points to the last element in outer ModuleToSummariesForIndex map.
339     std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesBack;
340     /// Iterator on outer ModuleToSummariesForIndex map.
341     std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesIter;
342     /// Iterator on an inner global variable summary map.
343     GVSummaryMapTy::const_iterator ModuleGVSummariesIter;
344 
345     // Iterators used when writing all summaries in the index:
346 
347     /// Points to the last element in the Index outer GlobalValueMap.
348     const_gvsummary_iterator IndexSummariesBack;
349     /// Iterator on outer GlobalValueMap.
350     const_gvsummary_iterator IndexSummariesIter;
351     /// Iterator on an inner GlobalValueSummaryList.
352     GlobalValueSummaryList::const_iterator IndexGVSummariesIter;
353 
354   public:
355     /// Construct iterator from parent \p Writer and indicate if we are
356     /// constructing the end iterator.
357     iterator(const IndexBitcodeWriter &Writer, bool IsAtEnd) : Writer(Writer) {
358       // Set up the appropriate set of iterators given whether we are writing
359       // the full index or just a subset.
360       // Can't setup the Back or inner iterators if the corresponding map
361       // is empty. This will be handled specially in operator== as well.
362       if (Writer.ModuleToSummariesForIndex &&
363           !Writer.ModuleToSummariesForIndex->empty()) {
364         for (ModuleSummariesBack = Writer.ModuleToSummariesForIndex->begin();
365              std::next(ModuleSummariesBack) !=
366              Writer.ModuleToSummariesForIndex->end();
367              ModuleSummariesBack++)
368           ;
369         ModuleSummariesIter = !IsAtEnd
370                                   ? Writer.ModuleToSummariesForIndex->begin()
371                                   : ModuleSummariesBack;
372         ModuleGVSummariesIter = !IsAtEnd ? ModuleSummariesIter->second.begin()
373                                          : ModuleSummariesBack->second.end();
374       } else if (!Writer.ModuleToSummariesForIndex &&
375                  Writer.Index.begin() != Writer.Index.end()) {
376         for (IndexSummariesBack = Writer.Index.begin();
377              std::next(IndexSummariesBack) != Writer.Index.end();
378              IndexSummariesBack++)
379           ;
380         IndexSummariesIter =
381             !IsAtEnd ? Writer.Index.begin() : IndexSummariesBack;
382         IndexGVSummariesIter = !IsAtEnd ? IndexSummariesIter->second.begin()
383                                         : IndexSummariesBack->second.end();
384       }
385     }
386 
387     /// Increment the appropriate set of iterators.
388     iterator &operator++() {
389       // First the inner iterator is incremented, then if it is at the end
390       // and there are more outer iterations to go, the inner is reset to
391       // the start of the next inner list.
392       if (Writer.ModuleToSummariesForIndex) {
393         ++ModuleGVSummariesIter;
394         if (ModuleGVSummariesIter == ModuleSummariesIter->second.end() &&
395             ModuleSummariesIter != ModuleSummariesBack) {
396           ++ModuleSummariesIter;
397           ModuleGVSummariesIter = ModuleSummariesIter->second.begin();
398         }
399       } else {
400         ++IndexGVSummariesIter;
401         if (IndexGVSummariesIter == IndexSummariesIter->second.end() &&
402             IndexSummariesIter != IndexSummariesBack) {
403           ++IndexSummariesIter;
404           IndexGVSummariesIter = IndexSummariesIter->second.begin();
405         }
406       }
407       return *this;
408     }
409 
410     /// Access the <GUID,GlobalValueSummary*> pair corresponding to the current
411     /// outer and inner iterator positions.
412     GVInfo operator*() {
413       if (Writer.ModuleToSummariesForIndex)
414         return std::make_pair(ModuleGVSummariesIter->first,
415                               ModuleGVSummariesIter->second);
416       return std::make_pair(IndexSummariesIter->first,
417                             IndexGVSummariesIter->get());
418     }
419 
420     /// Checks if the iterators are equal, with special handling for empty
421     /// indexes.
422     bool operator==(const iterator &RHS) const {
423       if (Writer.ModuleToSummariesForIndex) {
424         // First ensure that both are writing the same subset.
425         if (Writer.ModuleToSummariesForIndex !=
426             RHS.Writer.ModuleToSummariesForIndex)
427           return false;
428         // Already determined above that maps are the same, so if one is
429         // empty, they both are.
430         if (Writer.ModuleToSummariesForIndex->empty())
431           return true;
432         // Ensure the ModuleGVSummariesIter are iterating over the same
433         // container before checking them below.
434         if (ModuleSummariesIter != RHS.ModuleSummariesIter)
435           return false;
436         return ModuleGVSummariesIter == RHS.ModuleGVSummariesIter;
437       }
438       // First ensure RHS also writing the full index, and that both are
439       // writing the same full index.
440       if (RHS.Writer.ModuleToSummariesForIndex ||
441           &Writer.Index != &RHS.Writer.Index)
442         return false;
443       // Already determined above that maps are the same, so if one is
444       // empty, they both are.
445       if (Writer.Index.begin() == Writer.Index.end())
446         return true;
447       // Ensure the IndexGVSummariesIter are iterating over the same
448       // container before checking them below.
449       if (IndexSummariesIter != RHS.IndexSummariesIter)
450         return false;
451       return IndexGVSummariesIter == RHS.IndexGVSummariesIter;
452     }
453   };
454 
455   /// Obtain the start iterator over the summaries to be written.
456   iterator begin() { return iterator(*this, /*IsAtEnd=*/false); }
457   /// Obtain the end iterator over the summaries to be written.
458   iterator end() { return iterator(*this, /*IsAtEnd=*/true); }
459 
460   /// Main entry point for writing a combined index to bitcode.
461   void write();
462 
463 private:
464   void writeIndex();
465   void writeModStrings();
466   void writeCombinedValueSymbolTable();
467   void writeCombinedGlobalValueSummary();
468 
469   /// Indicates whether the provided \p ModulePath should be written into
470   /// the module string table, e.g. if full index written or if it is in
471   /// the provided subset.
472   bool doIncludeModule(StringRef ModulePath) {
473     return !ModuleToSummariesForIndex ||
474            ModuleToSummariesForIndex->count(ModulePath);
475   }
476 
477   bool hasValueId(GlobalValue::GUID ValGUID) {
478     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
479     return VMI != GUIDToValueIdMap.end();
480   }
481   unsigned getValueId(GlobalValue::GUID ValGUID) {
482     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
483     // If this GUID doesn't have an entry, assign one.
484     if (VMI == GUIDToValueIdMap.end()) {
485       GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
486       return GlobalValueId;
487     } else {
488       return VMI->second;
489     }
490   }
491   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
492 };
493 } // end anonymous namespace
494 
495 static unsigned getEncodedCastOpcode(unsigned Opcode) {
496   switch (Opcode) {
497   default: llvm_unreachable("Unknown cast instruction!");
498   case Instruction::Trunc   : return bitc::CAST_TRUNC;
499   case Instruction::ZExt    : return bitc::CAST_ZEXT;
500   case Instruction::SExt    : return bitc::CAST_SEXT;
501   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
502   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
503   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
504   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
505   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
506   case Instruction::FPExt   : return bitc::CAST_FPEXT;
507   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
508   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
509   case Instruction::BitCast : return bitc::CAST_BITCAST;
510   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
511   }
512 }
513 
514 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
515   switch (Opcode) {
516   default: llvm_unreachable("Unknown binary instruction!");
517   case Instruction::Add:
518   case Instruction::FAdd: return bitc::BINOP_ADD;
519   case Instruction::Sub:
520   case Instruction::FSub: return bitc::BINOP_SUB;
521   case Instruction::Mul:
522   case Instruction::FMul: return bitc::BINOP_MUL;
523   case Instruction::UDiv: return bitc::BINOP_UDIV;
524   case Instruction::FDiv:
525   case Instruction::SDiv: return bitc::BINOP_SDIV;
526   case Instruction::URem: return bitc::BINOP_UREM;
527   case Instruction::FRem:
528   case Instruction::SRem: return bitc::BINOP_SREM;
529   case Instruction::Shl:  return bitc::BINOP_SHL;
530   case Instruction::LShr: return bitc::BINOP_LSHR;
531   case Instruction::AShr: return bitc::BINOP_ASHR;
532   case Instruction::And:  return bitc::BINOP_AND;
533   case Instruction::Or:   return bitc::BINOP_OR;
534   case Instruction::Xor:  return bitc::BINOP_XOR;
535   }
536 }
537 
538 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
539   switch (Op) {
540   default: llvm_unreachable("Unknown RMW operation!");
541   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
542   case AtomicRMWInst::Add: return bitc::RMW_ADD;
543   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
544   case AtomicRMWInst::And: return bitc::RMW_AND;
545   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
546   case AtomicRMWInst::Or: return bitc::RMW_OR;
547   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
548   case AtomicRMWInst::Max: return bitc::RMW_MAX;
549   case AtomicRMWInst::Min: return bitc::RMW_MIN;
550   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
551   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
552   }
553 }
554 
555 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
556   switch (Ordering) {
557   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
558   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
559   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
560   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
561   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
562   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
563   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
564   }
565   llvm_unreachable("Invalid ordering");
566 }
567 
568 static unsigned getEncodedSynchScope(SynchronizationScope SynchScope) {
569   switch (SynchScope) {
570   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
571   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
572   }
573   llvm_unreachable("Invalid synch scope");
574 }
575 
576 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
577                               StringRef Str, unsigned AbbrevToUse) {
578   SmallVector<unsigned, 64> Vals;
579 
580   // Code: [strchar x N]
581   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
582     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
583       AbbrevToUse = 0;
584     Vals.push_back(Str[i]);
585   }
586 
587   // Emit the finished record.
588   Stream.EmitRecord(Code, Vals, AbbrevToUse);
589 }
590 
591 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
592   switch (Kind) {
593   case Attribute::Alignment:
594     return bitc::ATTR_KIND_ALIGNMENT;
595   case Attribute::AllocSize:
596     return bitc::ATTR_KIND_ALLOC_SIZE;
597   case Attribute::AlwaysInline:
598     return bitc::ATTR_KIND_ALWAYS_INLINE;
599   case Attribute::ArgMemOnly:
600     return bitc::ATTR_KIND_ARGMEMONLY;
601   case Attribute::Builtin:
602     return bitc::ATTR_KIND_BUILTIN;
603   case Attribute::ByVal:
604     return bitc::ATTR_KIND_BY_VAL;
605   case Attribute::Convergent:
606     return bitc::ATTR_KIND_CONVERGENT;
607   case Attribute::InAlloca:
608     return bitc::ATTR_KIND_IN_ALLOCA;
609   case Attribute::Cold:
610     return bitc::ATTR_KIND_COLD;
611   case Attribute::InaccessibleMemOnly:
612     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
613   case Attribute::InaccessibleMemOrArgMemOnly:
614     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
615   case Attribute::InlineHint:
616     return bitc::ATTR_KIND_INLINE_HINT;
617   case Attribute::InReg:
618     return bitc::ATTR_KIND_IN_REG;
619   case Attribute::JumpTable:
620     return bitc::ATTR_KIND_JUMP_TABLE;
621   case Attribute::MinSize:
622     return bitc::ATTR_KIND_MIN_SIZE;
623   case Attribute::Naked:
624     return bitc::ATTR_KIND_NAKED;
625   case Attribute::Nest:
626     return bitc::ATTR_KIND_NEST;
627   case Attribute::NoAlias:
628     return bitc::ATTR_KIND_NO_ALIAS;
629   case Attribute::NoBuiltin:
630     return bitc::ATTR_KIND_NO_BUILTIN;
631   case Attribute::NoCapture:
632     return bitc::ATTR_KIND_NO_CAPTURE;
633   case Attribute::NoDuplicate:
634     return bitc::ATTR_KIND_NO_DUPLICATE;
635   case Attribute::NoImplicitFloat:
636     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
637   case Attribute::NoInline:
638     return bitc::ATTR_KIND_NO_INLINE;
639   case Attribute::NoRecurse:
640     return bitc::ATTR_KIND_NO_RECURSE;
641   case Attribute::NonLazyBind:
642     return bitc::ATTR_KIND_NON_LAZY_BIND;
643   case Attribute::NonNull:
644     return bitc::ATTR_KIND_NON_NULL;
645   case Attribute::Dereferenceable:
646     return bitc::ATTR_KIND_DEREFERENCEABLE;
647   case Attribute::DereferenceableOrNull:
648     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
649   case Attribute::NoRedZone:
650     return bitc::ATTR_KIND_NO_RED_ZONE;
651   case Attribute::NoReturn:
652     return bitc::ATTR_KIND_NO_RETURN;
653   case Attribute::NoUnwind:
654     return bitc::ATTR_KIND_NO_UNWIND;
655   case Attribute::OptimizeForSize:
656     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
657   case Attribute::OptimizeNone:
658     return bitc::ATTR_KIND_OPTIMIZE_NONE;
659   case Attribute::ReadNone:
660     return bitc::ATTR_KIND_READ_NONE;
661   case Attribute::ReadOnly:
662     return bitc::ATTR_KIND_READ_ONLY;
663   case Attribute::Returned:
664     return bitc::ATTR_KIND_RETURNED;
665   case Attribute::ReturnsTwice:
666     return bitc::ATTR_KIND_RETURNS_TWICE;
667   case Attribute::SExt:
668     return bitc::ATTR_KIND_S_EXT;
669   case Attribute::StackAlignment:
670     return bitc::ATTR_KIND_STACK_ALIGNMENT;
671   case Attribute::StackProtect:
672     return bitc::ATTR_KIND_STACK_PROTECT;
673   case Attribute::StackProtectReq:
674     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
675   case Attribute::StackProtectStrong:
676     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
677   case Attribute::SafeStack:
678     return bitc::ATTR_KIND_SAFESTACK;
679   case Attribute::StructRet:
680     return bitc::ATTR_KIND_STRUCT_RET;
681   case Attribute::SanitizeAddress:
682     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
683   case Attribute::SanitizeThread:
684     return bitc::ATTR_KIND_SANITIZE_THREAD;
685   case Attribute::SanitizeMemory:
686     return bitc::ATTR_KIND_SANITIZE_MEMORY;
687   case Attribute::SwiftError:
688     return bitc::ATTR_KIND_SWIFT_ERROR;
689   case Attribute::SwiftSelf:
690     return bitc::ATTR_KIND_SWIFT_SELF;
691   case Attribute::UWTable:
692     return bitc::ATTR_KIND_UW_TABLE;
693   case Attribute::WriteOnly:
694     return bitc::ATTR_KIND_WRITEONLY;
695   case Attribute::ZExt:
696     return bitc::ATTR_KIND_Z_EXT;
697   case Attribute::EndAttrKinds:
698     llvm_unreachable("Can not encode end-attribute kinds marker.");
699   case Attribute::None:
700     llvm_unreachable("Can not encode none-attribute.");
701   }
702 
703   llvm_unreachable("Trying to encode unknown attribute");
704 }
705 
706 void ModuleBitcodeWriter::writeAttributeGroupTable() {
707   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
708   if (AttrGrps.empty()) return;
709 
710   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
711 
712   SmallVector<uint64_t, 64> Record;
713   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
714     AttributeSet AS = AttrGrps[i];
715     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
716       AttributeSet A = AS.getSlotAttributes(i);
717 
718       Record.push_back(VE.getAttributeGroupID(A));
719       Record.push_back(AS.getSlotIndex(i));
720 
721       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
722            I != E; ++I) {
723         Attribute Attr = *I;
724         if (Attr.isEnumAttribute()) {
725           Record.push_back(0);
726           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
727         } else if (Attr.isIntAttribute()) {
728           Record.push_back(1);
729           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
730           Record.push_back(Attr.getValueAsInt());
731         } else {
732           StringRef Kind = Attr.getKindAsString();
733           StringRef Val = Attr.getValueAsString();
734 
735           Record.push_back(Val.empty() ? 3 : 4);
736           Record.append(Kind.begin(), Kind.end());
737           Record.push_back(0);
738           if (!Val.empty()) {
739             Record.append(Val.begin(), Val.end());
740             Record.push_back(0);
741           }
742         }
743       }
744 
745       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
746       Record.clear();
747     }
748   }
749 
750   Stream.ExitBlock();
751 }
752 
753 void ModuleBitcodeWriter::writeAttributeTable() {
754   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
755   if (Attrs.empty()) return;
756 
757   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
758 
759   SmallVector<uint64_t, 64> Record;
760   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
761     const AttributeSet &A = Attrs[i];
762     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
763       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
764 
765     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
766     Record.clear();
767   }
768 
769   Stream.ExitBlock();
770 }
771 
772 /// WriteTypeTable - Write out the type table for a module.
773 void ModuleBitcodeWriter::writeTypeTable() {
774   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
775 
776   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
777   SmallVector<uint64_t, 64> TypeVals;
778 
779   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
780 
781   // Abbrev for TYPE_CODE_POINTER.
782   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
783   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
784   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
785   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
786   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
787 
788   // Abbrev for TYPE_CODE_FUNCTION.
789   Abbv = new BitCodeAbbrev();
790   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
791   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
792   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
793   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
794 
795   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
796 
797   // Abbrev for TYPE_CODE_STRUCT_ANON.
798   Abbv = new BitCodeAbbrev();
799   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
800   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
801   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
802   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
803 
804   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
805 
806   // Abbrev for TYPE_CODE_STRUCT_NAME.
807   Abbv = new BitCodeAbbrev();
808   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
809   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
810   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
811   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
812 
813   // Abbrev for TYPE_CODE_STRUCT_NAMED.
814   Abbv = new BitCodeAbbrev();
815   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
816   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
817   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
818   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
819 
820   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
821 
822   // Abbrev for TYPE_CODE_ARRAY.
823   Abbv = new BitCodeAbbrev();
824   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
825   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
826   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
827 
828   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
829 
830   // Emit an entry count so the reader can reserve space.
831   TypeVals.push_back(TypeList.size());
832   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
833   TypeVals.clear();
834 
835   // Loop over all of the types, emitting each in turn.
836   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
837     Type *T = TypeList[i];
838     int AbbrevToUse = 0;
839     unsigned Code = 0;
840 
841     switch (T->getTypeID()) {
842     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
843     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
844     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
845     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
846     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
847     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
848     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
849     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
850     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
851     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
852     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
853     case Type::IntegerTyID:
854       // INTEGER: [width]
855       Code = bitc::TYPE_CODE_INTEGER;
856       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
857       break;
858     case Type::PointerTyID: {
859       PointerType *PTy = cast<PointerType>(T);
860       // POINTER: [pointee type, address space]
861       Code = bitc::TYPE_CODE_POINTER;
862       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
863       unsigned AddressSpace = PTy->getAddressSpace();
864       TypeVals.push_back(AddressSpace);
865       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
866       break;
867     }
868     case Type::FunctionTyID: {
869       FunctionType *FT = cast<FunctionType>(T);
870       // FUNCTION: [isvararg, retty, paramty x N]
871       Code = bitc::TYPE_CODE_FUNCTION;
872       TypeVals.push_back(FT->isVarArg());
873       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
874       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
875         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
876       AbbrevToUse = FunctionAbbrev;
877       break;
878     }
879     case Type::StructTyID: {
880       StructType *ST = cast<StructType>(T);
881       // STRUCT: [ispacked, eltty x N]
882       TypeVals.push_back(ST->isPacked());
883       // Output all of the element types.
884       for (StructType::element_iterator I = ST->element_begin(),
885            E = ST->element_end(); I != E; ++I)
886         TypeVals.push_back(VE.getTypeID(*I));
887 
888       if (ST->isLiteral()) {
889         Code = bitc::TYPE_CODE_STRUCT_ANON;
890         AbbrevToUse = StructAnonAbbrev;
891       } else {
892         if (ST->isOpaque()) {
893           Code = bitc::TYPE_CODE_OPAQUE;
894         } else {
895           Code = bitc::TYPE_CODE_STRUCT_NAMED;
896           AbbrevToUse = StructNamedAbbrev;
897         }
898 
899         // Emit the name if it is present.
900         if (!ST->getName().empty())
901           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
902                             StructNameAbbrev);
903       }
904       break;
905     }
906     case Type::ArrayTyID: {
907       ArrayType *AT = cast<ArrayType>(T);
908       // ARRAY: [numelts, eltty]
909       Code = bitc::TYPE_CODE_ARRAY;
910       TypeVals.push_back(AT->getNumElements());
911       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
912       AbbrevToUse = ArrayAbbrev;
913       break;
914     }
915     case Type::VectorTyID: {
916       VectorType *VT = cast<VectorType>(T);
917       // VECTOR [numelts, eltty]
918       Code = bitc::TYPE_CODE_VECTOR;
919       TypeVals.push_back(VT->getNumElements());
920       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
921       break;
922     }
923     }
924 
925     // Emit the finished record.
926     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
927     TypeVals.clear();
928   }
929 
930   Stream.ExitBlock();
931 }
932 
933 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
934   switch (Linkage) {
935   case GlobalValue::ExternalLinkage:
936     return 0;
937   case GlobalValue::WeakAnyLinkage:
938     return 16;
939   case GlobalValue::AppendingLinkage:
940     return 2;
941   case GlobalValue::InternalLinkage:
942     return 3;
943   case GlobalValue::LinkOnceAnyLinkage:
944     return 18;
945   case GlobalValue::ExternalWeakLinkage:
946     return 7;
947   case GlobalValue::CommonLinkage:
948     return 8;
949   case GlobalValue::PrivateLinkage:
950     return 9;
951   case GlobalValue::WeakODRLinkage:
952     return 17;
953   case GlobalValue::LinkOnceODRLinkage:
954     return 19;
955   case GlobalValue::AvailableExternallyLinkage:
956     return 12;
957   }
958   llvm_unreachable("Invalid linkage");
959 }
960 
961 static unsigned getEncodedLinkage(const GlobalValue &GV) {
962   return getEncodedLinkage(GV.getLinkage());
963 }
964 
965 // Decode the flags for GlobalValue in the summary
966 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
967   uint64_t RawFlags = 0;
968 
969   RawFlags |= Flags.NoRename; // bool
970   RawFlags |= (Flags.IsNotViableToInline << 1);
971   RawFlags |= (Flags.HasInlineAsmMaybeReferencingInternal << 2);
972   // Linkage don't need to be remapped at that time for the summary. Any future
973   // change to the getEncodedLinkage() function will need to be taken into
974   // account here as well.
975   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
976 
977   return RawFlags;
978 }
979 
980 static unsigned getEncodedVisibility(const GlobalValue &GV) {
981   switch (GV.getVisibility()) {
982   case GlobalValue::DefaultVisibility:   return 0;
983   case GlobalValue::HiddenVisibility:    return 1;
984   case GlobalValue::ProtectedVisibility: return 2;
985   }
986   llvm_unreachable("Invalid visibility");
987 }
988 
989 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
990   switch (GV.getDLLStorageClass()) {
991   case GlobalValue::DefaultStorageClass:   return 0;
992   case GlobalValue::DLLImportStorageClass: return 1;
993   case GlobalValue::DLLExportStorageClass: return 2;
994   }
995   llvm_unreachable("Invalid DLL storage class");
996 }
997 
998 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
999   switch (GV.getThreadLocalMode()) {
1000     case GlobalVariable::NotThreadLocal:         return 0;
1001     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1002     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1003     case GlobalVariable::InitialExecTLSModel:    return 3;
1004     case GlobalVariable::LocalExecTLSModel:      return 4;
1005   }
1006   llvm_unreachable("Invalid TLS model");
1007 }
1008 
1009 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1010   switch (C.getSelectionKind()) {
1011   case Comdat::Any:
1012     return bitc::COMDAT_SELECTION_KIND_ANY;
1013   case Comdat::ExactMatch:
1014     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1015   case Comdat::Largest:
1016     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1017   case Comdat::NoDuplicates:
1018     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1019   case Comdat::SameSize:
1020     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1021   }
1022   llvm_unreachable("Invalid selection kind");
1023 }
1024 
1025 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1026   switch (GV.getUnnamedAddr()) {
1027   case GlobalValue::UnnamedAddr::None:   return 0;
1028   case GlobalValue::UnnamedAddr::Local:  return 2;
1029   case GlobalValue::UnnamedAddr::Global: return 1;
1030   }
1031   llvm_unreachable("Invalid unnamed_addr");
1032 }
1033 
1034 void ModuleBitcodeWriter::writeComdats() {
1035   SmallVector<unsigned, 64> Vals;
1036   for (const Comdat *C : VE.getComdats()) {
1037     // COMDAT: [selection_kind, name]
1038     Vals.push_back(getEncodedComdatSelectionKind(*C));
1039     size_t Size = C->getName().size();
1040     assert(isUInt<32>(Size));
1041     Vals.push_back(Size);
1042     for (char Chr : C->getName())
1043       Vals.push_back((unsigned char)Chr);
1044     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1045     Vals.clear();
1046   }
1047 }
1048 
1049 /// Write a record that will eventually hold the word offset of the
1050 /// module-level VST. For now the offset is 0, which will be backpatched
1051 /// after the real VST is written. Saves the bit offset to backpatch.
1052 void BitcodeWriterBase::writeValueSymbolTableForwardDecl() {
1053   // Write a placeholder value in for the offset of the real VST,
1054   // which is written after the function blocks so that it can include
1055   // the offset of each function. The placeholder offset will be
1056   // updated when the real VST is written.
1057   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1058   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1059   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1060   // hold the real VST offset. Must use fixed instead of VBR as we don't
1061   // know how many VBR chunks to reserve ahead of time.
1062   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1063   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(Abbv);
1064 
1065   // Emit the placeholder
1066   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1067   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1068 
1069   // Compute and save the bit offset to the placeholder, which will be
1070   // patched when the real VST is written. We can simply subtract the 32-bit
1071   // fixed size from the current bit number to get the location to backpatch.
1072   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1073 }
1074 
1075 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1076 
1077 /// Determine the encoding to use for the given string name and length.
1078 static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
1079   bool isChar6 = true;
1080   for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
1081     if (isChar6)
1082       isChar6 = BitCodeAbbrevOp::isChar6(*C);
1083     if ((unsigned char)*C & 128)
1084       // don't bother scanning the rest.
1085       return SE_Fixed8;
1086   }
1087   if (isChar6)
1088     return SE_Char6;
1089   else
1090     return SE_Fixed7;
1091 }
1092 
1093 /// Emit top-level description of module, including target triple, inline asm,
1094 /// descriptors for global variables, and function prototype info.
1095 /// Returns the bit offset to backpatch with the location of the real VST.
1096 void ModuleBitcodeWriter::writeModuleInfo() {
1097   // Emit various pieces of data attached to a module.
1098   if (!M.getTargetTriple().empty())
1099     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1100                       0 /*TODO*/);
1101   const std::string &DL = M.getDataLayoutStr();
1102   if (!DL.empty())
1103     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1104   if (!M.getModuleInlineAsm().empty())
1105     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1106                       0 /*TODO*/);
1107 
1108   // Emit information about sections and GC, computing how many there are. Also
1109   // compute the maximum alignment value.
1110   std::map<std::string, unsigned> SectionMap;
1111   std::map<std::string, unsigned> GCMap;
1112   unsigned MaxAlignment = 0;
1113   unsigned MaxGlobalType = 0;
1114   for (const GlobalValue &GV : M.globals()) {
1115     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1116     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1117     if (GV.hasSection()) {
1118       // Give section names unique ID's.
1119       unsigned &Entry = SectionMap[GV.getSection()];
1120       if (!Entry) {
1121         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1122                           0 /*TODO*/);
1123         Entry = SectionMap.size();
1124       }
1125     }
1126   }
1127   for (const Function &F : M) {
1128     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1129     if (F.hasSection()) {
1130       // Give section names unique ID's.
1131       unsigned &Entry = SectionMap[F.getSection()];
1132       if (!Entry) {
1133         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1134                           0 /*TODO*/);
1135         Entry = SectionMap.size();
1136       }
1137     }
1138     if (F.hasGC()) {
1139       // Same for GC names.
1140       unsigned &Entry = GCMap[F.getGC()];
1141       if (!Entry) {
1142         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1143                           0 /*TODO*/);
1144         Entry = GCMap.size();
1145       }
1146     }
1147   }
1148 
1149   // Emit abbrev for globals, now that we know # sections and max alignment.
1150   unsigned SimpleGVarAbbrev = 0;
1151   if (!M.global_empty()) {
1152     // Add an abbrev for common globals with no visibility or thread localness.
1153     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1154     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1156                               Log2_32_Ceil(MaxGlobalType+1)));
1157     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1158                                                            //| explicitType << 1
1159                                                            //| constant
1160     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1161     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1162     if (MaxAlignment == 0)                                 // Alignment.
1163       Abbv->Add(BitCodeAbbrevOp(0));
1164     else {
1165       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1166       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1167                                Log2_32_Ceil(MaxEncAlignment+1)));
1168     }
1169     if (SectionMap.empty())                                    // Section.
1170       Abbv->Add(BitCodeAbbrevOp(0));
1171     else
1172       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1173                                Log2_32_Ceil(SectionMap.size()+1)));
1174     // Don't bother emitting vis + thread local.
1175     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
1176   }
1177 
1178   // Emit the global variable information.
1179   SmallVector<unsigned, 64> Vals;
1180   for (const GlobalVariable &GV : M.globals()) {
1181     unsigned AbbrevToUse = 0;
1182 
1183     // GLOBALVAR: [type, isconst, initid,
1184     //             linkage, alignment, section, visibility, threadlocal,
1185     //             unnamed_addr, externally_initialized, dllstorageclass,
1186     //             comdat]
1187     Vals.push_back(VE.getTypeID(GV.getValueType()));
1188     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1189     Vals.push_back(GV.isDeclaration() ? 0 :
1190                    (VE.getValueID(GV.getInitializer()) + 1));
1191     Vals.push_back(getEncodedLinkage(GV));
1192     Vals.push_back(Log2_32(GV.getAlignment())+1);
1193     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1194     if (GV.isThreadLocal() ||
1195         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1196         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1197         GV.isExternallyInitialized() ||
1198         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1199         GV.hasComdat()) {
1200       Vals.push_back(getEncodedVisibility(GV));
1201       Vals.push_back(getEncodedThreadLocalMode(GV));
1202       Vals.push_back(getEncodedUnnamedAddr(GV));
1203       Vals.push_back(GV.isExternallyInitialized());
1204       Vals.push_back(getEncodedDLLStorageClass(GV));
1205       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1206     } else {
1207       AbbrevToUse = SimpleGVarAbbrev;
1208     }
1209 
1210     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1211     Vals.clear();
1212   }
1213 
1214   // Emit the function proto information.
1215   for (const Function &F : M) {
1216     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
1217     //             section, visibility, gc, unnamed_addr, prologuedata,
1218     //             dllstorageclass, comdat, prefixdata, personalityfn]
1219     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1220     Vals.push_back(F.getCallingConv());
1221     Vals.push_back(F.isDeclaration());
1222     Vals.push_back(getEncodedLinkage(F));
1223     Vals.push_back(VE.getAttributeID(F.getAttributes()));
1224     Vals.push_back(Log2_32(F.getAlignment())+1);
1225     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1226     Vals.push_back(getEncodedVisibility(F));
1227     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1228     Vals.push_back(getEncodedUnnamedAddr(F));
1229     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1230                                        : 0);
1231     Vals.push_back(getEncodedDLLStorageClass(F));
1232     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1233     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1234                                      : 0);
1235     Vals.push_back(
1236         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1237 
1238     unsigned AbbrevToUse = 0;
1239     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1240     Vals.clear();
1241   }
1242 
1243   // Emit the alias information.
1244   for (const GlobalAlias &A : M.aliases()) {
1245     // ALIAS: [alias type, aliasee val#, linkage, visibility, dllstorageclass,
1246     //         threadlocal, unnamed_addr]
1247     Vals.push_back(VE.getTypeID(A.getValueType()));
1248     Vals.push_back(A.getType()->getAddressSpace());
1249     Vals.push_back(VE.getValueID(A.getAliasee()));
1250     Vals.push_back(getEncodedLinkage(A));
1251     Vals.push_back(getEncodedVisibility(A));
1252     Vals.push_back(getEncodedDLLStorageClass(A));
1253     Vals.push_back(getEncodedThreadLocalMode(A));
1254     Vals.push_back(getEncodedUnnamedAddr(A));
1255     unsigned AbbrevToUse = 0;
1256     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1257     Vals.clear();
1258   }
1259 
1260   // Emit the ifunc information.
1261   for (const GlobalIFunc &I : M.ifuncs()) {
1262     // IFUNC: [ifunc type, address space, resolver val#, linkage, visibility]
1263     Vals.push_back(VE.getTypeID(I.getValueType()));
1264     Vals.push_back(I.getType()->getAddressSpace());
1265     Vals.push_back(VE.getValueID(I.getResolver()));
1266     Vals.push_back(getEncodedLinkage(I));
1267     Vals.push_back(getEncodedVisibility(I));
1268     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1269     Vals.clear();
1270   }
1271 
1272   // Emit the module's source file name.
1273   {
1274     StringEncoding Bits = getStringEncoding(M.getSourceFileName().data(),
1275                                             M.getSourceFileName().size());
1276     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1277     if (Bits == SE_Char6)
1278       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1279     else if (Bits == SE_Fixed7)
1280       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1281 
1282     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1283     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1284     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1285     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1286     Abbv->Add(AbbrevOpToUse);
1287     unsigned FilenameAbbrev = Stream.EmitAbbrev(Abbv);
1288 
1289     for (const auto P : M.getSourceFileName())
1290       Vals.push_back((unsigned char)P);
1291 
1292     // Emit the finished record.
1293     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1294     Vals.clear();
1295   }
1296 
1297   // If we have a VST, write the VSTOFFSET record placeholder.
1298   if (M.getValueSymbolTable().empty())
1299     return;
1300   writeValueSymbolTableForwardDecl();
1301 }
1302 
1303 static uint64_t getOptimizationFlags(const Value *V) {
1304   uint64_t Flags = 0;
1305 
1306   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1307     if (OBO->hasNoSignedWrap())
1308       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1309     if (OBO->hasNoUnsignedWrap())
1310       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1311   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1312     if (PEO->isExact())
1313       Flags |= 1 << bitc::PEO_EXACT;
1314   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1315     if (FPMO->hasUnsafeAlgebra())
1316       Flags |= FastMathFlags::UnsafeAlgebra;
1317     if (FPMO->hasNoNaNs())
1318       Flags |= FastMathFlags::NoNaNs;
1319     if (FPMO->hasNoInfs())
1320       Flags |= FastMathFlags::NoInfs;
1321     if (FPMO->hasNoSignedZeros())
1322       Flags |= FastMathFlags::NoSignedZeros;
1323     if (FPMO->hasAllowReciprocal())
1324       Flags |= FastMathFlags::AllowReciprocal;
1325   }
1326 
1327   return Flags;
1328 }
1329 
1330 void ModuleBitcodeWriter::writeValueAsMetadata(
1331     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1332   // Mimic an MDNode with a value as one operand.
1333   Value *V = MD->getValue();
1334   Record.push_back(VE.getTypeID(V->getType()));
1335   Record.push_back(VE.getValueID(V));
1336   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1337   Record.clear();
1338 }
1339 
1340 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1341                                        SmallVectorImpl<uint64_t> &Record,
1342                                        unsigned Abbrev) {
1343   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1344     Metadata *MD = N->getOperand(i);
1345     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1346            "Unexpected function-local metadata");
1347     Record.push_back(VE.getMetadataOrNullID(MD));
1348   }
1349   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1350                                     : bitc::METADATA_NODE,
1351                     Record, Abbrev);
1352   Record.clear();
1353 }
1354 
1355 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1356   // Assume the column is usually under 128, and always output the inlined-at
1357   // location (it's never more expensive than building an array size 1).
1358   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1359   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1360   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1361   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1362   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1363   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1365   return Stream.EmitAbbrev(Abbv);
1366 }
1367 
1368 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1369                                           SmallVectorImpl<uint64_t> &Record,
1370                                           unsigned &Abbrev) {
1371   if (!Abbrev)
1372     Abbrev = createDILocationAbbrev();
1373 
1374   Record.push_back(N->isDistinct());
1375   Record.push_back(N->getLine());
1376   Record.push_back(N->getColumn());
1377   Record.push_back(VE.getMetadataID(N->getScope()));
1378   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1379 
1380   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1381   Record.clear();
1382 }
1383 
1384 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1385   // Assume the column is usually under 128, and always output the inlined-at
1386   // location (it's never more expensive than building an array size 1).
1387   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1388   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1390   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1391   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1392   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1393   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1394   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1395   return Stream.EmitAbbrev(Abbv);
1396 }
1397 
1398 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1399                                              SmallVectorImpl<uint64_t> &Record,
1400                                              unsigned &Abbrev) {
1401   if (!Abbrev)
1402     Abbrev = createGenericDINodeAbbrev();
1403 
1404   Record.push_back(N->isDistinct());
1405   Record.push_back(N->getTag());
1406   Record.push_back(0); // Per-tag version field; unused for now.
1407 
1408   for (auto &I : N->operands())
1409     Record.push_back(VE.getMetadataOrNullID(I));
1410 
1411   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1412   Record.clear();
1413 }
1414 
1415 static uint64_t rotateSign(int64_t I) {
1416   uint64_t U = I;
1417   return I < 0 ? ~(U << 1) : U << 1;
1418 }
1419 
1420 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1421                                           SmallVectorImpl<uint64_t> &Record,
1422                                           unsigned Abbrev) {
1423   Record.push_back(N->isDistinct());
1424   Record.push_back(N->getCount());
1425   Record.push_back(rotateSign(N->getLowerBound()));
1426 
1427   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1428   Record.clear();
1429 }
1430 
1431 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1432                                             SmallVectorImpl<uint64_t> &Record,
1433                                             unsigned Abbrev) {
1434   Record.push_back(N->isDistinct());
1435   Record.push_back(rotateSign(N->getValue()));
1436   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1437 
1438   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1439   Record.clear();
1440 }
1441 
1442 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1443                                            SmallVectorImpl<uint64_t> &Record,
1444                                            unsigned Abbrev) {
1445   Record.push_back(N->isDistinct());
1446   Record.push_back(N->getTag());
1447   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1448   Record.push_back(N->getSizeInBits());
1449   Record.push_back(N->getAlignInBits());
1450   Record.push_back(N->getEncoding());
1451 
1452   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1453   Record.clear();
1454 }
1455 
1456 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1457                                              SmallVectorImpl<uint64_t> &Record,
1458                                              unsigned Abbrev) {
1459   Record.push_back(N->isDistinct());
1460   Record.push_back(N->getTag());
1461   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1462   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1463   Record.push_back(N->getLine());
1464   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1465   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1466   Record.push_back(N->getSizeInBits());
1467   Record.push_back(N->getAlignInBits());
1468   Record.push_back(N->getOffsetInBits());
1469   Record.push_back(N->getFlags());
1470   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1471 
1472   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1473   Record.clear();
1474 }
1475 
1476 void ModuleBitcodeWriter::writeDICompositeType(
1477     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1478     unsigned Abbrev) {
1479   const unsigned IsNotUsedInOldTypeRef = 0x2;
1480   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1481   Record.push_back(N->getTag());
1482   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1483   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1484   Record.push_back(N->getLine());
1485   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1486   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1487   Record.push_back(N->getSizeInBits());
1488   Record.push_back(N->getAlignInBits());
1489   Record.push_back(N->getOffsetInBits());
1490   Record.push_back(N->getFlags());
1491   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1492   Record.push_back(N->getRuntimeLang());
1493   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1494   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1495   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1496 
1497   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1498   Record.clear();
1499 }
1500 
1501 void ModuleBitcodeWriter::writeDISubroutineType(
1502     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1503     unsigned Abbrev) {
1504   const unsigned HasNoOldTypeRefs = 0x2;
1505   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1506   Record.push_back(N->getFlags());
1507   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1508   Record.push_back(N->getCC());
1509 
1510   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1511   Record.clear();
1512 }
1513 
1514 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1515                                       SmallVectorImpl<uint64_t> &Record,
1516                                       unsigned Abbrev) {
1517   Record.push_back(N->isDistinct());
1518   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1519   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1520   Record.push_back(N->getChecksumKind());
1521   Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()));
1522 
1523   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1524   Record.clear();
1525 }
1526 
1527 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1528                                              SmallVectorImpl<uint64_t> &Record,
1529                                              unsigned Abbrev) {
1530   assert(N->isDistinct() && "Expected distinct compile units");
1531   Record.push_back(/* IsDistinct */ true);
1532   Record.push_back(N->getSourceLanguage());
1533   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1534   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1535   Record.push_back(N->isOptimized());
1536   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1537   Record.push_back(N->getRuntimeVersion());
1538   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1539   Record.push_back(N->getEmissionKind());
1540   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1541   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1542   Record.push_back(/* subprograms */ 0);
1543   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1544   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1545   Record.push_back(N->getDWOId());
1546   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1547   Record.push_back(N->getSplitDebugInlining());
1548 
1549   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1550   Record.clear();
1551 }
1552 
1553 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1554                                             SmallVectorImpl<uint64_t> &Record,
1555                                             unsigned Abbrev) {
1556   uint64_t HasUnitFlag = 1 << 1;
1557   Record.push_back(N->isDistinct() | HasUnitFlag);
1558   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1559   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1560   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1561   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1562   Record.push_back(N->getLine());
1563   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1564   Record.push_back(N->isLocalToUnit());
1565   Record.push_back(N->isDefinition());
1566   Record.push_back(N->getScopeLine());
1567   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1568   Record.push_back(N->getVirtuality());
1569   Record.push_back(N->getVirtualIndex());
1570   Record.push_back(N->getFlags());
1571   Record.push_back(N->isOptimized());
1572   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1573   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1574   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1575   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1576   Record.push_back(N->getThisAdjustment());
1577 
1578   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1579   Record.clear();
1580 }
1581 
1582 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1583                                               SmallVectorImpl<uint64_t> &Record,
1584                                               unsigned Abbrev) {
1585   Record.push_back(N->isDistinct());
1586   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1587   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1588   Record.push_back(N->getLine());
1589   Record.push_back(N->getColumn());
1590 
1591   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1592   Record.clear();
1593 }
1594 
1595 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1596     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1597     unsigned Abbrev) {
1598   Record.push_back(N->isDistinct());
1599   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1600   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1601   Record.push_back(N->getDiscriminator());
1602 
1603   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1604   Record.clear();
1605 }
1606 
1607 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1608                                            SmallVectorImpl<uint64_t> &Record,
1609                                            unsigned Abbrev) {
1610   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1611   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1612   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1613   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1614   Record.push_back(N->getLine());
1615 
1616   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1617   Record.clear();
1618 }
1619 
1620 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1621                                        SmallVectorImpl<uint64_t> &Record,
1622                                        unsigned Abbrev) {
1623   Record.push_back(N->isDistinct());
1624   Record.push_back(N->getMacinfoType());
1625   Record.push_back(N->getLine());
1626   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1627   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1628 
1629   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1630   Record.clear();
1631 }
1632 
1633 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1634                                            SmallVectorImpl<uint64_t> &Record,
1635                                            unsigned Abbrev) {
1636   Record.push_back(N->isDistinct());
1637   Record.push_back(N->getMacinfoType());
1638   Record.push_back(N->getLine());
1639   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1640   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1641 
1642   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1643   Record.clear();
1644 }
1645 
1646 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1647                                         SmallVectorImpl<uint64_t> &Record,
1648                                         unsigned Abbrev) {
1649   Record.push_back(N->isDistinct());
1650   for (auto &I : N->operands())
1651     Record.push_back(VE.getMetadataOrNullID(I));
1652 
1653   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1654   Record.clear();
1655 }
1656 
1657 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1658     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1659     unsigned Abbrev) {
1660   Record.push_back(N->isDistinct());
1661   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1662   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1663 
1664   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1665   Record.clear();
1666 }
1667 
1668 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1669     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1670     unsigned Abbrev) {
1671   Record.push_back(N->isDistinct());
1672   Record.push_back(N->getTag());
1673   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1674   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1675   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1676 
1677   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1678   Record.clear();
1679 }
1680 
1681 void ModuleBitcodeWriter::writeDIGlobalVariable(
1682     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1683     unsigned Abbrev) {
1684   const uint64_t Version = 1 << 1;
1685   Record.push_back((uint64_t)N->isDistinct() | Version);
1686   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1687   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1688   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1689   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1690   Record.push_back(N->getLine());
1691   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1692   Record.push_back(N->isLocalToUnit());
1693   Record.push_back(N->isDefinition());
1694   Record.push_back(/* expr */ 0);
1695   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1696   Record.push_back(N->getAlignInBits());
1697 
1698   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1699   Record.clear();
1700 }
1701 
1702 void ModuleBitcodeWriter::writeDILocalVariable(
1703     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1704     unsigned Abbrev) {
1705   // In order to support all possible bitcode formats in BitcodeReader we need
1706   // to distinguish the following cases:
1707   // 1) Record has no artificial tag (Record[1]),
1708   //   has no obsolete inlinedAt field (Record[9]).
1709   //   In this case Record size will be 8, HasAlignment flag is false.
1710   // 2) Record has artificial tag (Record[1]),
1711   //   has no obsolete inlignedAt field (Record[9]).
1712   //   In this case Record size will be 9, HasAlignment flag is false.
1713   // 3) Record has both artificial tag (Record[1]) and
1714   //   obsolete inlignedAt field (Record[9]).
1715   //   In this case Record size will be 10, HasAlignment flag is false.
1716   // 4) Record has neither artificial tag, nor inlignedAt field, but
1717   //   HasAlignment flag is true and Record[8] contains alignment value.
1718   const uint64_t HasAlignmentFlag = 1 << 1;
1719   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1720   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1721   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1722   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1723   Record.push_back(N->getLine());
1724   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1725   Record.push_back(N->getArg());
1726   Record.push_back(N->getFlags());
1727   Record.push_back(N->getAlignInBits());
1728 
1729   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1730   Record.clear();
1731 }
1732 
1733 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1734                                             SmallVectorImpl<uint64_t> &Record,
1735                                             unsigned Abbrev) {
1736   Record.reserve(N->getElements().size() + 1);
1737 
1738   const uint64_t HasOpFragmentFlag = 1 << 1;
1739   Record.push_back((uint64_t)N->isDistinct() | HasOpFragmentFlag);
1740   Record.append(N->elements_begin(), N->elements_end());
1741 
1742   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1743   Record.clear();
1744 }
1745 
1746 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1747     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1748     unsigned Abbrev) {
1749   Record.push_back(N->isDistinct());
1750   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1751   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1752 
1753   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1754   Record.clear();
1755 }
1756 
1757 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1758                                               SmallVectorImpl<uint64_t> &Record,
1759                                               unsigned Abbrev) {
1760   Record.push_back(N->isDistinct());
1761   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1762   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1763   Record.push_back(N->getLine());
1764   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1765   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1766   Record.push_back(N->getAttributes());
1767   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1768 
1769   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1770   Record.clear();
1771 }
1772 
1773 void ModuleBitcodeWriter::writeDIImportedEntity(
1774     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1775     unsigned Abbrev) {
1776   Record.push_back(N->isDistinct());
1777   Record.push_back(N->getTag());
1778   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1779   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1780   Record.push_back(N->getLine());
1781   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1782 
1783   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1784   Record.clear();
1785 }
1786 
1787 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1788   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1789   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1790   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1791   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1792   return Stream.EmitAbbrev(Abbv);
1793 }
1794 
1795 void ModuleBitcodeWriter::writeNamedMetadata(
1796     SmallVectorImpl<uint64_t> &Record) {
1797   if (M.named_metadata_empty())
1798     return;
1799 
1800   unsigned Abbrev = createNamedMetadataAbbrev();
1801   for (const NamedMDNode &NMD : M.named_metadata()) {
1802     // Write name.
1803     StringRef Str = NMD.getName();
1804     Record.append(Str.bytes_begin(), Str.bytes_end());
1805     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1806     Record.clear();
1807 
1808     // Write named metadata operands.
1809     for (const MDNode *N : NMD.operands())
1810       Record.push_back(VE.getMetadataID(N));
1811     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1812     Record.clear();
1813   }
1814 }
1815 
1816 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1817   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1818   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1819   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1820   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1822   return Stream.EmitAbbrev(Abbv);
1823 }
1824 
1825 /// Write out a record for MDString.
1826 ///
1827 /// All the metadata strings in a metadata block are emitted in a single
1828 /// record.  The sizes and strings themselves are shoved into a blob.
1829 void ModuleBitcodeWriter::writeMetadataStrings(
1830     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1831   if (Strings.empty())
1832     return;
1833 
1834   // Start the record with the number of strings.
1835   Record.push_back(bitc::METADATA_STRINGS);
1836   Record.push_back(Strings.size());
1837 
1838   // Emit the sizes of the strings in the blob.
1839   SmallString<256> Blob;
1840   {
1841     BitstreamWriter W(Blob);
1842     for (const Metadata *MD : Strings)
1843       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1844     W.FlushToWord();
1845   }
1846 
1847   // Add the offset to the strings to the record.
1848   Record.push_back(Blob.size());
1849 
1850   // Add the strings to the blob.
1851   for (const Metadata *MD : Strings)
1852     Blob.append(cast<MDString>(MD)->getString());
1853 
1854   // Emit the final record.
1855   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1856   Record.clear();
1857 }
1858 
1859 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1860 enum MetadataAbbrev : unsigned {
1861 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1862 #include "llvm/IR/Metadata.def"
1863   LastPlusOne
1864 };
1865 
1866 void ModuleBitcodeWriter::writeMetadataRecords(
1867     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1868     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1869   if (MDs.empty())
1870     return;
1871 
1872   // Initialize MDNode abbreviations.
1873 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1874 #include "llvm/IR/Metadata.def"
1875 
1876   for (const Metadata *MD : MDs) {
1877     if (IndexPos)
1878       IndexPos->push_back(Stream.GetCurrentBitNo());
1879     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1880       assert(N->isResolved() && "Expected forward references to be resolved");
1881 
1882       switch (N->getMetadataID()) {
1883       default:
1884         llvm_unreachable("Invalid MDNode subclass");
1885 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1886   case Metadata::CLASS##Kind:                                                  \
1887     if (MDAbbrevs)                                                             \
1888       write##CLASS(cast<CLASS>(N), Record,                                     \
1889                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1890     else                                                                       \
1891       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1892     continue;
1893 #include "llvm/IR/Metadata.def"
1894       }
1895     }
1896     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1897   }
1898 }
1899 
1900 void ModuleBitcodeWriter::writeModuleMetadata() {
1901   if (!VE.hasMDs() && M.named_metadata_empty())
1902     return;
1903 
1904   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1905   SmallVector<uint64_t, 64> Record;
1906 
1907   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1908   // block and load any metadata.
1909   std::vector<unsigned> MDAbbrevs;
1910 
1911   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1912   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1913   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1914       createGenericDINodeAbbrev();
1915 
1916   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1917   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1918   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 64));
1919   unsigned OffsetAbbrev = Stream.EmitAbbrev(Abbv);
1920 
1921   Abbv = new BitCodeAbbrev();
1922   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1923   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1924   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1925   unsigned IndexAbbrev = Stream.EmitAbbrev(Abbv);
1926 
1927   // Emit MDStrings together upfront.
1928   writeMetadataStrings(VE.getMDStrings(), Record);
1929 
1930   // Write a placeholder value in for the offset of the metadata index,
1931   // which is written after the records, so that it can include
1932   // the offset of each entry. The placeholder offset will be
1933   // updated after all records are emitted.
1934   uint64_t Vals[] = {0};
1935   Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
1936 
1937   // Compute and save the bit offset to the current position, which will be
1938   // patched when we emit the index later. We can simply subtract the 64-bit
1939   // fixed size from the current bit number to get the location to backpatch.
1940   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
1941 
1942   // This index will contain the bitpos for each individual record.
1943   std::vector<uint64_t> IndexPos;
1944   IndexPos.reserve(VE.getNonMDStrings().size());
1945 
1946   // Write all the records
1947   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
1948 
1949   // Now that we have emitted all the records we will emit the index. But first
1950   // backpatch the forward reference so that the reader can skip the records
1951   // efficiently.
1952   Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
1953                          Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
1954 
1955   // Delta encode the index.
1956   uint64_t PreviousValue = IndexOffsetRecordBitPos;
1957   for (auto &Elt : IndexPos) {
1958     auto EltDelta = Elt - PreviousValue;
1959     PreviousValue = Elt;
1960     Elt = EltDelta;
1961   }
1962   // Emit the index record.
1963   Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
1964   IndexPos.clear();
1965 
1966   // Write the named metadata now.
1967   writeNamedMetadata(Record);
1968 
1969   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
1970     SmallVector<uint64_t, 4> Record;
1971     Record.push_back(VE.getValueID(&GO));
1972     pushGlobalMetadataAttachment(Record, GO);
1973     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
1974   };
1975   for (const Function &F : M)
1976     if (F.isDeclaration() && F.hasMetadata())
1977       AddDeclAttachedMetadata(F);
1978   // FIXME: Only store metadata for declarations here, and move data for global
1979   // variable definitions to a separate block (PR28134).
1980   for (const GlobalVariable &GV : M.globals())
1981     if (GV.hasMetadata())
1982       AddDeclAttachedMetadata(GV);
1983 
1984   Stream.ExitBlock();
1985 }
1986 
1987 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
1988   if (!VE.hasMDs())
1989     return;
1990 
1991   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1992   SmallVector<uint64_t, 64> Record;
1993   writeMetadataStrings(VE.getMDStrings(), Record);
1994   writeMetadataRecords(VE.getNonMDStrings(), Record);
1995   Stream.ExitBlock();
1996 }
1997 
1998 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
1999     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2000   // [n x [id, mdnode]]
2001   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2002   GO.getAllMetadata(MDs);
2003   for (const auto &I : MDs) {
2004     Record.push_back(I.first);
2005     Record.push_back(VE.getMetadataID(I.second));
2006   }
2007 }
2008 
2009 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2010   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2011 
2012   SmallVector<uint64_t, 64> Record;
2013 
2014   if (F.hasMetadata()) {
2015     pushGlobalMetadataAttachment(Record, F);
2016     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2017     Record.clear();
2018   }
2019 
2020   // Write metadata attachments
2021   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2022   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2023   for (const BasicBlock &BB : F)
2024     for (const Instruction &I : BB) {
2025       MDs.clear();
2026       I.getAllMetadataOtherThanDebugLoc(MDs);
2027 
2028       // If no metadata, ignore instruction.
2029       if (MDs.empty()) continue;
2030 
2031       Record.push_back(VE.getInstructionID(&I));
2032 
2033       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2034         Record.push_back(MDs[i].first);
2035         Record.push_back(VE.getMetadataID(MDs[i].second));
2036       }
2037       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2038       Record.clear();
2039     }
2040 
2041   Stream.ExitBlock();
2042 }
2043 
2044 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2045   SmallVector<uint64_t, 64> Record;
2046 
2047   // Write metadata kinds
2048   // METADATA_KIND - [n x [id, name]]
2049   SmallVector<StringRef, 8> Names;
2050   M.getMDKindNames(Names);
2051 
2052   if (Names.empty()) return;
2053 
2054   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2055 
2056   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2057     Record.push_back(MDKindID);
2058     StringRef KName = Names[MDKindID];
2059     Record.append(KName.begin(), KName.end());
2060 
2061     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2062     Record.clear();
2063   }
2064 
2065   Stream.ExitBlock();
2066 }
2067 
2068 void ModuleBitcodeWriter::writeOperandBundleTags() {
2069   // Write metadata kinds
2070   //
2071   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2072   //
2073   // OPERAND_BUNDLE_TAG - [strchr x N]
2074 
2075   SmallVector<StringRef, 8> Tags;
2076   M.getOperandBundleTags(Tags);
2077 
2078   if (Tags.empty())
2079     return;
2080 
2081   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2082 
2083   SmallVector<uint64_t, 64> Record;
2084 
2085   for (auto Tag : Tags) {
2086     Record.append(Tag.begin(), Tag.end());
2087 
2088     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2089     Record.clear();
2090   }
2091 
2092   Stream.ExitBlock();
2093 }
2094 
2095 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2096   if ((int64_t)V >= 0)
2097     Vals.push_back(V << 1);
2098   else
2099     Vals.push_back((-V << 1) | 1);
2100 }
2101 
2102 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2103                                          bool isGlobal) {
2104   if (FirstVal == LastVal) return;
2105 
2106   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2107 
2108   unsigned AggregateAbbrev = 0;
2109   unsigned String8Abbrev = 0;
2110   unsigned CString7Abbrev = 0;
2111   unsigned CString6Abbrev = 0;
2112   // If this is a constant pool for the module, emit module-specific abbrevs.
2113   if (isGlobal) {
2114     // Abbrev for CST_CODE_AGGREGATE.
2115     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2116     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2117     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2118     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2119     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
2120 
2121     // Abbrev for CST_CODE_STRING.
2122     Abbv = new BitCodeAbbrev();
2123     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2125     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2126     String8Abbrev = Stream.EmitAbbrev(Abbv);
2127     // Abbrev for CST_CODE_CSTRING.
2128     Abbv = new BitCodeAbbrev();
2129     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2130     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2131     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2132     CString7Abbrev = Stream.EmitAbbrev(Abbv);
2133     // Abbrev for CST_CODE_CSTRING.
2134     Abbv = new BitCodeAbbrev();
2135     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2136     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2137     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2138     CString6Abbrev = Stream.EmitAbbrev(Abbv);
2139   }
2140 
2141   SmallVector<uint64_t, 64> Record;
2142 
2143   const ValueEnumerator::ValueList &Vals = VE.getValues();
2144   Type *LastTy = nullptr;
2145   for (unsigned i = FirstVal; i != LastVal; ++i) {
2146     const Value *V = Vals[i].first;
2147     // If we need to switch types, do so now.
2148     if (V->getType() != LastTy) {
2149       LastTy = V->getType();
2150       Record.push_back(VE.getTypeID(LastTy));
2151       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2152                         CONSTANTS_SETTYPE_ABBREV);
2153       Record.clear();
2154     }
2155 
2156     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2157       Record.push_back(unsigned(IA->hasSideEffects()) |
2158                        unsigned(IA->isAlignStack()) << 1 |
2159                        unsigned(IA->getDialect()&1) << 2);
2160 
2161       // Add the asm string.
2162       const std::string &AsmStr = IA->getAsmString();
2163       Record.push_back(AsmStr.size());
2164       Record.append(AsmStr.begin(), AsmStr.end());
2165 
2166       // Add the constraint string.
2167       const std::string &ConstraintStr = IA->getConstraintString();
2168       Record.push_back(ConstraintStr.size());
2169       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2170       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2171       Record.clear();
2172       continue;
2173     }
2174     const Constant *C = cast<Constant>(V);
2175     unsigned Code = -1U;
2176     unsigned AbbrevToUse = 0;
2177     if (C->isNullValue()) {
2178       Code = bitc::CST_CODE_NULL;
2179     } else if (isa<UndefValue>(C)) {
2180       Code = bitc::CST_CODE_UNDEF;
2181     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2182       if (IV->getBitWidth() <= 64) {
2183         uint64_t V = IV->getSExtValue();
2184         emitSignedInt64(Record, V);
2185         Code = bitc::CST_CODE_INTEGER;
2186         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2187       } else {                             // Wide integers, > 64 bits in size.
2188         // We have an arbitrary precision integer value to write whose
2189         // bit width is > 64. However, in canonical unsigned integer
2190         // format it is likely that the high bits are going to be zero.
2191         // So, we only write the number of active words.
2192         unsigned NWords = IV->getValue().getActiveWords();
2193         const uint64_t *RawWords = IV->getValue().getRawData();
2194         for (unsigned i = 0; i != NWords; ++i) {
2195           emitSignedInt64(Record, RawWords[i]);
2196         }
2197         Code = bitc::CST_CODE_WIDE_INTEGER;
2198       }
2199     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2200       Code = bitc::CST_CODE_FLOAT;
2201       Type *Ty = CFP->getType();
2202       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2203         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2204       } else if (Ty->isX86_FP80Ty()) {
2205         // api needed to prevent premature destruction
2206         // bits are not in the same order as a normal i80 APInt, compensate.
2207         APInt api = CFP->getValueAPF().bitcastToAPInt();
2208         const uint64_t *p = api.getRawData();
2209         Record.push_back((p[1] << 48) | (p[0] >> 16));
2210         Record.push_back(p[0] & 0xffffLL);
2211       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2212         APInt api = CFP->getValueAPF().bitcastToAPInt();
2213         const uint64_t *p = api.getRawData();
2214         Record.push_back(p[0]);
2215         Record.push_back(p[1]);
2216       } else {
2217         assert (0 && "Unknown FP type!");
2218       }
2219     } else if (isa<ConstantDataSequential>(C) &&
2220                cast<ConstantDataSequential>(C)->isString()) {
2221       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2222       // Emit constant strings specially.
2223       unsigned NumElts = Str->getNumElements();
2224       // If this is a null-terminated string, use the denser CSTRING encoding.
2225       if (Str->isCString()) {
2226         Code = bitc::CST_CODE_CSTRING;
2227         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2228       } else {
2229         Code = bitc::CST_CODE_STRING;
2230         AbbrevToUse = String8Abbrev;
2231       }
2232       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2233       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2234       for (unsigned i = 0; i != NumElts; ++i) {
2235         unsigned char V = Str->getElementAsInteger(i);
2236         Record.push_back(V);
2237         isCStr7 &= (V & 128) == 0;
2238         if (isCStrChar6)
2239           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2240       }
2241 
2242       if (isCStrChar6)
2243         AbbrevToUse = CString6Abbrev;
2244       else if (isCStr7)
2245         AbbrevToUse = CString7Abbrev;
2246     } else if (const ConstantDataSequential *CDS =
2247                   dyn_cast<ConstantDataSequential>(C)) {
2248       Code = bitc::CST_CODE_DATA;
2249       Type *EltTy = CDS->getType()->getElementType();
2250       if (isa<IntegerType>(EltTy)) {
2251         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2252           Record.push_back(CDS->getElementAsInteger(i));
2253       } else {
2254         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2255           Record.push_back(
2256               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2257       }
2258     } else if (isa<ConstantAggregate>(C)) {
2259       Code = bitc::CST_CODE_AGGREGATE;
2260       for (const Value *Op : C->operands())
2261         Record.push_back(VE.getValueID(Op));
2262       AbbrevToUse = AggregateAbbrev;
2263     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2264       switch (CE->getOpcode()) {
2265       default:
2266         if (Instruction::isCast(CE->getOpcode())) {
2267           Code = bitc::CST_CODE_CE_CAST;
2268           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2269           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2270           Record.push_back(VE.getValueID(C->getOperand(0)));
2271           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2272         } else {
2273           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2274           Code = bitc::CST_CODE_CE_BINOP;
2275           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2276           Record.push_back(VE.getValueID(C->getOperand(0)));
2277           Record.push_back(VE.getValueID(C->getOperand(1)));
2278           uint64_t Flags = getOptimizationFlags(CE);
2279           if (Flags != 0)
2280             Record.push_back(Flags);
2281         }
2282         break;
2283       case Instruction::GetElementPtr: {
2284         Code = bitc::CST_CODE_CE_GEP;
2285         const auto *GO = cast<GEPOperator>(C);
2286         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2287         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2288           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2289           Record.push_back((*Idx << 1) | GO->isInBounds());
2290         } else if (GO->isInBounds())
2291           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2292         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2293           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2294           Record.push_back(VE.getValueID(C->getOperand(i)));
2295         }
2296         break;
2297       }
2298       case Instruction::Select:
2299         Code = bitc::CST_CODE_CE_SELECT;
2300         Record.push_back(VE.getValueID(C->getOperand(0)));
2301         Record.push_back(VE.getValueID(C->getOperand(1)));
2302         Record.push_back(VE.getValueID(C->getOperand(2)));
2303         break;
2304       case Instruction::ExtractElement:
2305         Code = bitc::CST_CODE_CE_EXTRACTELT;
2306         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2307         Record.push_back(VE.getValueID(C->getOperand(0)));
2308         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2309         Record.push_back(VE.getValueID(C->getOperand(1)));
2310         break;
2311       case Instruction::InsertElement:
2312         Code = bitc::CST_CODE_CE_INSERTELT;
2313         Record.push_back(VE.getValueID(C->getOperand(0)));
2314         Record.push_back(VE.getValueID(C->getOperand(1)));
2315         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2316         Record.push_back(VE.getValueID(C->getOperand(2)));
2317         break;
2318       case Instruction::ShuffleVector:
2319         // If the return type and argument types are the same, this is a
2320         // standard shufflevector instruction.  If the types are different,
2321         // then the shuffle is widening or truncating the input vectors, and
2322         // the argument type must also be encoded.
2323         if (C->getType() == C->getOperand(0)->getType()) {
2324           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2325         } else {
2326           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2327           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2328         }
2329         Record.push_back(VE.getValueID(C->getOperand(0)));
2330         Record.push_back(VE.getValueID(C->getOperand(1)));
2331         Record.push_back(VE.getValueID(C->getOperand(2)));
2332         break;
2333       case Instruction::ICmp:
2334       case Instruction::FCmp:
2335         Code = bitc::CST_CODE_CE_CMP;
2336         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2337         Record.push_back(VE.getValueID(C->getOperand(0)));
2338         Record.push_back(VE.getValueID(C->getOperand(1)));
2339         Record.push_back(CE->getPredicate());
2340         break;
2341       }
2342     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2343       Code = bitc::CST_CODE_BLOCKADDRESS;
2344       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2345       Record.push_back(VE.getValueID(BA->getFunction()));
2346       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2347     } else {
2348 #ifndef NDEBUG
2349       C->dump();
2350 #endif
2351       llvm_unreachable("Unknown constant!");
2352     }
2353     Stream.EmitRecord(Code, Record, AbbrevToUse);
2354     Record.clear();
2355   }
2356 
2357   Stream.ExitBlock();
2358 }
2359 
2360 void ModuleBitcodeWriter::writeModuleConstants() {
2361   const ValueEnumerator::ValueList &Vals = VE.getValues();
2362 
2363   // Find the first constant to emit, which is the first non-globalvalue value.
2364   // We know globalvalues have been emitted by WriteModuleInfo.
2365   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2366     if (!isa<GlobalValue>(Vals[i].first)) {
2367       writeConstants(i, Vals.size(), true);
2368       return;
2369     }
2370   }
2371 }
2372 
2373 /// pushValueAndType - The file has to encode both the value and type id for
2374 /// many values, because we need to know what type to create for forward
2375 /// references.  However, most operands are not forward references, so this type
2376 /// field is not needed.
2377 ///
2378 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2379 /// instruction ID, then it is a forward reference, and it also includes the
2380 /// type ID.  The value ID that is written is encoded relative to the InstID.
2381 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2382                                            SmallVectorImpl<unsigned> &Vals) {
2383   unsigned ValID = VE.getValueID(V);
2384   // Make encoding relative to the InstID.
2385   Vals.push_back(InstID - ValID);
2386   if (ValID >= InstID) {
2387     Vals.push_back(VE.getTypeID(V->getType()));
2388     return true;
2389   }
2390   return false;
2391 }
2392 
2393 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2394                                               unsigned InstID) {
2395   SmallVector<unsigned, 64> Record;
2396   LLVMContext &C = CS.getInstruction()->getContext();
2397 
2398   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2399     const auto &Bundle = CS.getOperandBundleAt(i);
2400     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2401 
2402     for (auto &Input : Bundle.Inputs)
2403       pushValueAndType(Input, InstID, Record);
2404 
2405     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2406     Record.clear();
2407   }
2408 }
2409 
2410 /// pushValue - Like pushValueAndType, but where the type of the value is
2411 /// omitted (perhaps it was already encoded in an earlier operand).
2412 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2413                                     SmallVectorImpl<unsigned> &Vals) {
2414   unsigned ValID = VE.getValueID(V);
2415   Vals.push_back(InstID - ValID);
2416 }
2417 
2418 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2419                                           SmallVectorImpl<uint64_t> &Vals) {
2420   unsigned ValID = VE.getValueID(V);
2421   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2422   emitSignedInt64(Vals, diff);
2423 }
2424 
2425 /// WriteInstruction - Emit an instruction to the specified stream.
2426 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2427                                            unsigned InstID,
2428                                            SmallVectorImpl<unsigned> &Vals) {
2429   unsigned Code = 0;
2430   unsigned AbbrevToUse = 0;
2431   VE.setInstructionID(&I);
2432   switch (I.getOpcode()) {
2433   default:
2434     if (Instruction::isCast(I.getOpcode())) {
2435       Code = bitc::FUNC_CODE_INST_CAST;
2436       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2437         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2438       Vals.push_back(VE.getTypeID(I.getType()));
2439       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2440     } else {
2441       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2442       Code = bitc::FUNC_CODE_INST_BINOP;
2443       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2444         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2445       pushValue(I.getOperand(1), InstID, Vals);
2446       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2447       uint64_t Flags = getOptimizationFlags(&I);
2448       if (Flags != 0) {
2449         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2450           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2451         Vals.push_back(Flags);
2452       }
2453     }
2454     break;
2455 
2456   case Instruction::GetElementPtr: {
2457     Code = bitc::FUNC_CODE_INST_GEP;
2458     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2459     auto &GEPInst = cast<GetElementPtrInst>(I);
2460     Vals.push_back(GEPInst.isInBounds());
2461     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2462     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2463       pushValueAndType(I.getOperand(i), InstID, Vals);
2464     break;
2465   }
2466   case Instruction::ExtractValue: {
2467     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2468     pushValueAndType(I.getOperand(0), InstID, Vals);
2469     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2470     Vals.append(EVI->idx_begin(), EVI->idx_end());
2471     break;
2472   }
2473   case Instruction::InsertValue: {
2474     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2475     pushValueAndType(I.getOperand(0), InstID, Vals);
2476     pushValueAndType(I.getOperand(1), InstID, Vals);
2477     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2478     Vals.append(IVI->idx_begin(), IVI->idx_end());
2479     break;
2480   }
2481   case Instruction::Select:
2482     Code = bitc::FUNC_CODE_INST_VSELECT;
2483     pushValueAndType(I.getOperand(1), InstID, Vals);
2484     pushValue(I.getOperand(2), InstID, Vals);
2485     pushValueAndType(I.getOperand(0), InstID, Vals);
2486     break;
2487   case Instruction::ExtractElement:
2488     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2489     pushValueAndType(I.getOperand(0), InstID, Vals);
2490     pushValueAndType(I.getOperand(1), InstID, Vals);
2491     break;
2492   case Instruction::InsertElement:
2493     Code = bitc::FUNC_CODE_INST_INSERTELT;
2494     pushValueAndType(I.getOperand(0), InstID, Vals);
2495     pushValue(I.getOperand(1), InstID, Vals);
2496     pushValueAndType(I.getOperand(2), InstID, Vals);
2497     break;
2498   case Instruction::ShuffleVector:
2499     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2500     pushValueAndType(I.getOperand(0), InstID, Vals);
2501     pushValue(I.getOperand(1), InstID, Vals);
2502     pushValue(I.getOperand(2), InstID, Vals);
2503     break;
2504   case Instruction::ICmp:
2505   case Instruction::FCmp: {
2506     // compare returning Int1Ty or vector of Int1Ty
2507     Code = bitc::FUNC_CODE_INST_CMP2;
2508     pushValueAndType(I.getOperand(0), InstID, Vals);
2509     pushValue(I.getOperand(1), InstID, Vals);
2510     Vals.push_back(cast<CmpInst>(I).getPredicate());
2511     uint64_t Flags = getOptimizationFlags(&I);
2512     if (Flags != 0)
2513       Vals.push_back(Flags);
2514     break;
2515   }
2516 
2517   case Instruction::Ret:
2518     {
2519       Code = bitc::FUNC_CODE_INST_RET;
2520       unsigned NumOperands = I.getNumOperands();
2521       if (NumOperands == 0)
2522         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2523       else if (NumOperands == 1) {
2524         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2525           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2526       } else {
2527         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2528           pushValueAndType(I.getOperand(i), InstID, Vals);
2529       }
2530     }
2531     break;
2532   case Instruction::Br:
2533     {
2534       Code = bitc::FUNC_CODE_INST_BR;
2535       const BranchInst &II = cast<BranchInst>(I);
2536       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2537       if (II.isConditional()) {
2538         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2539         pushValue(II.getCondition(), InstID, Vals);
2540       }
2541     }
2542     break;
2543   case Instruction::Switch:
2544     {
2545       Code = bitc::FUNC_CODE_INST_SWITCH;
2546       const SwitchInst &SI = cast<SwitchInst>(I);
2547       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2548       pushValue(SI.getCondition(), InstID, Vals);
2549       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2550       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
2551         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2552         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2553       }
2554     }
2555     break;
2556   case Instruction::IndirectBr:
2557     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2558     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2559     // Encode the address operand as relative, but not the basic blocks.
2560     pushValue(I.getOperand(0), InstID, Vals);
2561     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2562       Vals.push_back(VE.getValueID(I.getOperand(i)));
2563     break;
2564 
2565   case Instruction::Invoke: {
2566     const InvokeInst *II = cast<InvokeInst>(&I);
2567     const Value *Callee = II->getCalledValue();
2568     FunctionType *FTy = II->getFunctionType();
2569 
2570     if (II->hasOperandBundles())
2571       writeOperandBundles(II, InstID);
2572 
2573     Code = bitc::FUNC_CODE_INST_INVOKE;
2574 
2575     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2576     Vals.push_back(II->getCallingConv() | 1 << 13);
2577     Vals.push_back(VE.getValueID(II->getNormalDest()));
2578     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2579     Vals.push_back(VE.getTypeID(FTy));
2580     pushValueAndType(Callee, InstID, Vals);
2581 
2582     // Emit value #'s for the fixed parameters.
2583     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2584       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2585 
2586     // Emit type/value pairs for varargs params.
2587     if (FTy->isVarArg()) {
2588       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2589            i != e; ++i)
2590         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2591     }
2592     break;
2593   }
2594   case Instruction::Resume:
2595     Code = bitc::FUNC_CODE_INST_RESUME;
2596     pushValueAndType(I.getOperand(0), InstID, Vals);
2597     break;
2598   case Instruction::CleanupRet: {
2599     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2600     const auto &CRI = cast<CleanupReturnInst>(I);
2601     pushValue(CRI.getCleanupPad(), InstID, Vals);
2602     if (CRI.hasUnwindDest())
2603       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2604     break;
2605   }
2606   case Instruction::CatchRet: {
2607     Code = bitc::FUNC_CODE_INST_CATCHRET;
2608     const auto &CRI = cast<CatchReturnInst>(I);
2609     pushValue(CRI.getCatchPad(), InstID, Vals);
2610     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2611     break;
2612   }
2613   case Instruction::CleanupPad:
2614   case Instruction::CatchPad: {
2615     const auto &FuncletPad = cast<FuncletPadInst>(I);
2616     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2617                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2618     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2619 
2620     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2621     Vals.push_back(NumArgOperands);
2622     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2623       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2624     break;
2625   }
2626   case Instruction::CatchSwitch: {
2627     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2628     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2629 
2630     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2631 
2632     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2633     Vals.push_back(NumHandlers);
2634     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2635       Vals.push_back(VE.getValueID(CatchPadBB));
2636 
2637     if (CatchSwitch.hasUnwindDest())
2638       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2639     break;
2640   }
2641   case Instruction::Unreachable:
2642     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2643     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2644     break;
2645 
2646   case Instruction::PHI: {
2647     const PHINode &PN = cast<PHINode>(I);
2648     Code = bitc::FUNC_CODE_INST_PHI;
2649     // With the newer instruction encoding, forward references could give
2650     // negative valued IDs.  This is most common for PHIs, so we use
2651     // signed VBRs.
2652     SmallVector<uint64_t, 128> Vals64;
2653     Vals64.push_back(VE.getTypeID(PN.getType()));
2654     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2655       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2656       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2657     }
2658     // Emit a Vals64 vector and exit.
2659     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2660     Vals64.clear();
2661     return;
2662   }
2663 
2664   case Instruction::LandingPad: {
2665     const LandingPadInst &LP = cast<LandingPadInst>(I);
2666     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2667     Vals.push_back(VE.getTypeID(LP.getType()));
2668     Vals.push_back(LP.isCleanup());
2669     Vals.push_back(LP.getNumClauses());
2670     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2671       if (LP.isCatch(I))
2672         Vals.push_back(LandingPadInst::Catch);
2673       else
2674         Vals.push_back(LandingPadInst::Filter);
2675       pushValueAndType(LP.getClause(I), InstID, Vals);
2676     }
2677     break;
2678   }
2679 
2680   case Instruction::Alloca: {
2681     Code = bitc::FUNC_CODE_INST_ALLOCA;
2682     const AllocaInst &AI = cast<AllocaInst>(I);
2683     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2684     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2685     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2686     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2687     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2688            "not enough bits for maximum alignment");
2689     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2690     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2691     AlignRecord |= 1 << 6;
2692     AlignRecord |= AI.isSwiftError() << 7;
2693     Vals.push_back(AlignRecord);
2694     break;
2695   }
2696 
2697   case Instruction::Load:
2698     if (cast<LoadInst>(I).isAtomic()) {
2699       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2700       pushValueAndType(I.getOperand(0), InstID, Vals);
2701     } else {
2702       Code = bitc::FUNC_CODE_INST_LOAD;
2703       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2704         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2705     }
2706     Vals.push_back(VE.getTypeID(I.getType()));
2707     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2708     Vals.push_back(cast<LoadInst>(I).isVolatile());
2709     if (cast<LoadInst>(I).isAtomic()) {
2710       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2711       Vals.push_back(getEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2712     }
2713     break;
2714   case Instruction::Store:
2715     if (cast<StoreInst>(I).isAtomic())
2716       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2717     else
2718       Code = bitc::FUNC_CODE_INST_STORE;
2719     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2720     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2721     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2722     Vals.push_back(cast<StoreInst>(I).isVolatile());
2723     if (cast<StoreInst>(I).isAtomic()) {
2724       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2725       Vals.push_back(getEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2726     }
2727     break;
2728   case Instruction::AtomicCmpXchg:
2729     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2730     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2731     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2732     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2733     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2734     Vals.push_back(
2735         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2736     Vals.push_back(
2737         getEncodedSynchScope(cast<AtomicCmpXchgInst>(I).getSynchScope()));
2738     Vals.push_back(
2739         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2740     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2741     break;
2742   case Instruction::AtomicRMW:
2743     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2744     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2745     pushValue(I.getOperand(1), InstID, Vals);        // val.
2746     Vals.push_back(
2747         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2748     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2749     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2750     Vals.push_back(
2751         getEncodedSynchScope(cast<AtomicRMWInst>(I).getSynchScope()));
2752     break;
2753   case Instruction::Fence:
2754     Code = bitc::FUNC_CODE_INST_FENCE;
2755     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2756     Vals.push_back(getEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2757     break;
2758   case Instruction::Call: {
2759     const CallInst &CI = cast<CallInst>(I);
2760     FunctionType *FTy = CI.getFunctionType();
2761 
2762     if (CI.hasOperandBundles())
2763       writeOperandBundles(&CI, InstID);
2764 
2765     Code = bitc::FUNC_CODE_INST_CALL;
2766 
2767     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2768 
2769     unsigned Flags = getOptimizationFlags(&I);
2770     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2771                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2772                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2773                    1 << bitc::CALL_EXPLICIT_TYPE |
2774                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2775                    unsigned(Flags != 0) << bitc::CALL_FMF);
2776     if (Flags != 0)
2777       Vals.push_back(Flags);
2778 
2779     Vals.push_back(VE.getTypeID(FTy));
2780     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2781 
2782     // Emit value #'s for the fixed parameters.
2783     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2784       // Check for labels (can happen with asm labels).
2785       if (FTy->getParamType(i)->isLabelTy())
2786         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2787       else
2788         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2789     }
2790 
2791     // Emit type/value pairs for varargs params.
2792     if (FTy->isVarArg()) {
2793       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2794            i != e; ++i)
2795         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2796     }
2797     break;
2798   }
2799   case Instruction::VAArg:
2800     Code = bitc::FUNC_CODE_INST_VAARG;
2801     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2802     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2803     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2804     break;
2805   }
2806 
2807   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2808   Vals.clear();
2809 }
2810 
2811 /// Emit names for globals/functions etc. \p IsModuleLevel is true when
2812 /// we are writing the module-level VST, where we are including a function
2813 /// bitcode index and need to backpatch the VST forward declaration record.
2814 void ModuleBitcodeWriter::writeValueSymbolTable(
2815     const ValueSymbolTable &VST, bool IsModuleLevel,
2816     DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex) {
2817   if (VST.empty()) {
2818     // writeValueSymbolTableForwardDecl should have returned early as
2819     // well. Ensure this handling remains in sync by asserting that
2820     // the placeholder offset is not set.
2821     assert(!IsModuleLevel || !hasVSTOffsetPlaceholder());
2822     return;
2823   }
2824 
2825   if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
2826     // Get the offset of the VST we are writing, and backpatch it into
2827     // the VST forward declaration record.
2828     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2829     // The BitcodeStartBit was the stream offset of the identification block.
2830     VSTOffset -= bitcodeStartBit();
2831     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2832     // Note that we add 1 here because the offset is relative to one word
2833     // before the start of the identification block, which was historically
2834     // always the start of the regular bitcode header.
2835     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2836   }
2837 
2838   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2839 
2840   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2841   // records, which are not used in the per-function VSTs.
2842   unsigned FnEntry8BitAbbrev;
2843   unsigned FnEntry7BitAbbrev;
2844   unsigned FnEntry6BitAbbrev;
2845   unsigned GUIDEntryAbbrev;
2846   if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
2847     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2848     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2849     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2850     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2851     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2852     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2853     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2854     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2855 
2856     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2857     Abbv = new BitCodeAbbrev();
2858     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2859     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2860     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2861     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2862     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2863     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2864 
2865     // 6-bit char6 VST_CODE_FNENTRY function strings.
2866     Abbv = new BitCodeAbbrev();
2867     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2868     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2869     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2870     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2871     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2872     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2873 
2874     // FIXME: Change the name of this record as it is now used by
2875     // the per-module index as well.
2876     Abbv = new BitCodeAbbrev();
2877     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2878     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2879     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2880     GUIDEntryAbbrev = Stream.EmitAbbrev(Abbv);
2881   }
2882 
2883   // FIXME: Set up the abbrev, we know how many values there are!
2884   // FIXME: We know if the type names can use 7-bit ascii.
2885   SmallVector<uint64_t, 64> NameVals;
2886 
2887   for (const ValueName &Name : VST) {
2888     // Figure out the encoding to use for the name.
2889     StringEncoding Bits =
2890         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2891 
2892     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2893     NameVals.push_back(VE.getValueID(Name.getValue()));
2894 
2895     Function *F = dyn_cast<Function>(Name.getValue());
2896     if (!F) {
2897       // If value is an alias, need to get the aliased base object to
2898       // see if it is a function.
2899       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2900       if (GA && GA->getBaseObject())
2901         F = dyn_cast<Function>(GA->getBaseObject());
2902     }
2903 
2904     // VST_CODE_ENTRY:   [valueid, namechar x N]
2905     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2906     // VST_CODE_BBENTRY: [bbid, namechar x N]
2907     unsigned Code;
2908     if (isa<BasicBlock>(Name.getValue())) {
2909       Code = bitc::VST_CODE_BBENTRY;
2910       if (Bits == SE_Char6)
2911         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2912     } else if (F && !F->isDeclaration()) {
2913       // Must be the module-level VST, where we pass in the Index and
2914       // have a VSTOffsetPlaceholder. The function-level VST should not
2915       // contain any Function symbols.
2916       assert(FunctionToBitcodeIndex);
2917       assert(hasVSTOffsetPlaceholder());
2918 
2919       // Save the word offset of the function (from the start of the
2920       // actual bitcode written to the stream).
2921       uint64_t BitcodeIndex = (*FunctionToBitcodeIndex)[F] - bitcodeStartBit();
2922       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2923       // Note that we add 1 here because the offset is relative to one word
2924       // before the start of the identification block, which was historically
2925       // always the start of the regular bitcode header.
2926       NameVals.push_back(BitcodeIndex / 32 + 1);
2927 
2928       Code = bitc::VST_CODE_FNENTRY;
2929       AbbrevToUse = FnEntry8BitAbbrev;
2930       if (Bits == SE_Char6)
2931         AbbrevToUse = FnEntry6BitAbbrev;
2932       else if (Bits == SE_Fixed7)
2933         AbbrevToUse = FnEntry7BitAbbrev;
2934     } else {
2935       Code = bitc::VST_CODE_ENTRY;
2936       if (Bits == SE_Char6)
2937         AbbrevToUse = VST_ENTRY_6_ABBREV;
2938       else if (Bits == SE_Fixed7)
2939         AbbrevToUse = VST_ENTRY_7_ABBREV;
2940     }
2941 
2942     for (const auto P : Name.getKey())
2943       NameVals.push_back((unsigned char)P);
2944 
2945     // Emit the finished record.
2946     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2947     NameVals.clear();
2948   }
2949   // Emit any GUID valueIDs created for indirect call edges into the
2950   // module-level VST.
2951   if (IsModuleLevel && hasVSTOffsetPlaceholder())
2952     for (const auto &GI : valueIds()) {
2953       NameVals.push_back(GI.second);
2954       NameVals.push_back(GI.first);
2955       Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals,
2956                         GUIDEntryAbbrev);
2957       NameVals.clear();
2958     }
2959   Stream.ExitBlock();
2960 }
2961 
2962 /// Emit function names and summary offsets for the combined index
2963 /// used by ThinLTO.
2964 void IndexBitcodeWriter::writeCombinedValueSymbolTable() {
2965   assert(hasVSTOffsetPlaceholder() && "Expected non-zero VSTOffsetPlaceholder");
2966   // Get the offset of the VST we are writing, and backpatch it into
2967   // the VST forward declaration record.
2968   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2969   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2970   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2971 
2972   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2973 
2974   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2975   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2976   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2977   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2978   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2979 
2980   SmallVector<uint64_t, 64> NameVals;
2981   for (const auto &GVI : valueIds()) {
2982     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2983     NameVals.push_back(GVI.second);
2984     NameVals.push_back(GVI.first);
2985 
2986     // Emit the finished record.
2987     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2988     NameVals.clear();
2989   }
2990   Stream.ExitBlock();
2991 }
2992 
2993 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
2994   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2995   unsigned Code;
2996   if (isa<BasicBlock>(Order.V))
2997     Code = bitc::USELIST_CODE_BB;
2998   else
2999     Code = bitc::USELIST_CODE_DEFAULT;
3000 
3001   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3002   Record.push_back(VE.getValueID(Order.V));
3003   Stream.EmitRecord(Code, Record);
3004 }
3005 
3006 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3007   assert(VE.shouldPreserveUseListOrder() &&
3008          "Expected to be preserving use-list order");
3009 
3010   auto hasMore = [&]() {
3011     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3012   };
3013   if (!hasMore())
3014     // Nothing to do.
3015     return;
3016 
3017   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3018   while (hasMore()) {
3019     writeUseList(std::move(VE.UseListOrders.back()));
3020     VE.UseListOrders.pop_back();
3021   }
3022   Stream.ExitBlock();
3023 }
3024 
3025 /// Emit a function body to the module stream.
3026 void ModuleBitcodeWriter::writeFunction(
3027     const Function &F,
3028     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3029   // Save the bitcode index of the start of this function block for recording
3030   // in the VST.
3031   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3032 
3033   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3034   VE.incorporateFunction(F);
3035 
3036   SmallVector<unsigned, 64> Vals;
3037 
3038   // Emit the number of basic blocks, so the reader can create them ahead of
3039   // time.
3040   Vals.push_back(VE.getBasicBlocks().size());
3041   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3042   Vals.clear();
3043 
3044   // If there are function-local constants, emit them now.
3045   unsigned CstStart, CstEnd;
3046   VE.getFunctionConstantRange(CstStart, CstEnd);
3047   writeConstants(CstStart, CstEnd, false);
3048 
3049   // If there is function-local metadata, emit it now.
3050   writeFunctionMetadata(F);
3051 
3052   // Keep a running idea of what the instruction ID is.
3053   unsigned InstID = CstEnd;
3054 
3055   bool NeedsMetadataAttachment = F.hasMetadata();
3056 
3057   DILocation *LastDL = nullptr;
3058   // Finally, emit all the instructions, in order.
3059   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3060     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3061          I != E; ++I) {
3062       writeInstruction(*I, InstID, Vals);
3063 
3064       if (!I->getType()->isVoidTy())
3065         ++InstID;
3066 
3067       // If the instruction has metadata, write a metadata attachment later.
3068       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3069 
3070       // If the instruction has a debug location, emit it.
3071       DILocation *DL = I->getDebugLoc();
3072       if (!DL)
3073         continue;
3074 
3075       if (DL == LastDL) {
3076         // Just repeat the same debug loc as last time.
3077         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3078         continue;
3079       }
3080 
3081       Vals.push_back(DL->getLine());
3082       Vals.push_back(DL->getColumn());
3083       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3084       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3085       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3086       Vals.clear();
3087 
3088       LastDL = DL;
3089     }
3090 
3091   // Emit names for all the instructions etc.
3092   if (auto *Symtab = F.getValueSymbolTable())
3093     writeValueSymbolTable(*Symtab);
3094 
3095   if (NeedsMetadataAttachment)
3096     writeFunctionMetadataAttachment(F);
3097   if (VE.shouldPreserveUseListOrder())
3098     writeUseListBlock(&F);
3099   VE.purgeFunction();
3100   Stream.ExitBlock();
3101 }
3102 
3103 // Emit blockinfo, which defines the standard abbreviations etc.
3104 void ModuleBitcodeWriter::writeBlockInfo() {
3105   // We only want to emit block info records for blocks that have multiple
3106   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3107   // Other blocks can define their abbrevs inline.
3108   Stream.EnterBlockInfoBlock();
3109 
3110   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3111     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3112     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3113     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3114     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3115     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3116     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3117         VST_ENTRY_8_ABBREV)
3118       llvm_unreachable("Unexpected abbrev ordering!");
3119   }
3120 
3121   { // 7-bit fixed width VST_CODE_ENTRY strings.
3122     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3123     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3125     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3126     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3127     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3128         VST_ENTRY_7_ABBREV)
3129       llvm_unreachable("Unexpected abbrev ordering!");
3130   }
3131   { // 6-bit char6 VST_CODE_ENTRY strings.
3132     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3133     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3134     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3135     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3136     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3137     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3138         VST_ENTRY_6_ABBREV)
3139       llvm_unreachable("Unexpected abbrev ordering!");
3140   }
3141   { // 6-bit char6 VST_CODE_BBENTRY strings.
3142     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3143     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3144     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3146     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3147     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3148         VST_BBENTRY_6_ABBREV)
3149       llvm_unreachable("Unexpected abbrev ordering!");
3150   }
3151 
3152 
3153 
3154   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3155     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3156     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3157     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3158                               VE.computeBitsRequiredForTypeIndicies()));
3159     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3160         CONSTANTS_SETTYPE_ABBREV)
3161       llvm_unreachable("Unexpected abbrev ordering!");
3162   }
3163 
3164   { // INTEGER abbrev for CONSTANTS_BLOCK.
3165     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3166     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3167     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3168     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3169         CONSTANTS_INTEGER_ABBREV)
3170       llvm_unreachable("Unexpected abbrev ordering!");
3171   }
3172 
3173   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3174     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3175     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3178                               VE.computeBitsRequiredForTypeIndicies()));
3179     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3180 
3181     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3182         CONSTANTS_CE_CAST_Abbrev)
3183       llvm_unreachable("Unexpected abbrev ordering!");
3184   }
3185   { // NULL abbrev for CONSTANTS_BLOCK.
3186     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3187     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3188     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3189         CONSTANTS_NULL_Abbrev)
3190       llvm_unreachable("Unexpected abbrev ordering!");
3191   }
3192 
3193   // FIXME: This should only use space for first class types!
3194 
3195   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3196     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3197     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3198     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3199     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3200                               VE.computeBitsRequiredForTypeIndicies()));
3201     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3202     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3203     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3204         FUNCTION_INST_LOAD_ABBREV)
3205       llvm_unreachable("Unexpected abbrev ordering!");
3206   }
3207   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3208     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3209     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3210     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3211     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3212     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3213     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3214         FUNCTION_INST_BINOP_ABBREV)
3215       llvm_unreachable("Unexpected abbrev ordering!");
3216   }
3217   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3218     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3219     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3220     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3223     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
3224     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3225         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3226       llvm_unreachable("Unexpected abbrev ordering!");
3227   }
3228   { // INST_CAST abbrev for FUNCTION_BLOCK.
3229     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3230     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3231     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3233                               VE.computeBitsRequiredForTypeIndicies()));
3234     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3235     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3236         FUNCTION_INST_CAST_ABBREV)
3237       llvm_unreachable("Unexpected abbrev ordering!");
3238   }
3239 
3240   { // INST_RET abbrev for FUNCTION_BLOCK.
3241     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3242     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3243     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3244         FUNCTION_INST_RET_VOID_ABBREV)
3245       llvm_unreachable("Unexpected abbrev ordering!");
3246   }
3247   { // INST_RET abbrev for FUNCTION_BLOCK.
3248     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3249     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3250     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3251     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3252         FUNCTION_INST_RET_VAL_ABBREV)
3253       llvm_unreachable("Unexpected abbrev ordering!");
3254   }
3255   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3256     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3257     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3258     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3259         FUNCTION_INST_UNREACHABLE_ABBREV)
3260       llvm_unreachable("Unexpected abbrev ordering!");
3261   }
3262   {
3263     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3264     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3265     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3266     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3267                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3268     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3269     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3270     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3271         FUNCTION_INST_GEP_ABBREV)
3272       llvm_unreachable("Unexpected abbrev ordering!");
3273   }
3274 
3275   Stream.ExitBlock();
3276 }
3277 
3278 /// Write the module path strings, currently only used when generating
3279 /// a combined index file.
3280 void IndexBitcodeWriter::writeModStrings() {
3281   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3282 
3283   // TODO: See which abbrev sizes we actually need to emit
3284 
3285   // 8-bit fixed-width MST_ENTRY strings.
3286   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3287   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3288   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3289   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3290   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3291   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
3292 
3293   // 7-bit fixed width MST_ENTRY strings.
3294   Abbv = new BitCodeAbbrev();
3295   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3296   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3297   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3298   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3299   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
3300 
3301   // 6-bit char6 MST_ENTRY strings.
3302   Abbv = new BitCodeAbbrev();
3303   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3304   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3305   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3306   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3307   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
3308 
3309   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3310   Abbv = new BitCodeAbbrev();
3311   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3312   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3313   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3314   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3315   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3316   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3317   unsigned AbbrevHash = Stream.EmitAbbrev(Abbv);
3318 
3319   SmallVector<unsigned, 64> Vals;
3320   for (const auto &MPSE : Index.modulePaths()) {
3321     if (!doIncludeModule(MPSE.getKey()))
3322       continue;
3323     StringEncoding Bits =
3324         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
3325     unsigned AbbrevToUse = Abbrev8Bit;
3326     if (Bits == SE_Char6)
3327       AbbrevToUse = Abbrev6Bit;
3328     else if (Bits == SE_Fixed7)
3329       AbbrevToUse = Abbrev7Bit;
3330 
3331     Vals.push_back(MPSE.getValue().first);
3332 
3333     for (const auto P : MPSE.getKey())
3334       Vals.push_back((unsigned char)P);
3335 
3336     // Emit the finished record.
3337     Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3338 
3339     Vals.clear();
3340     // Emit an optional hash for the module now
3341     auto &Hash = MPSE.getValue().second;
3342     bool AllZero = true; // Detect if the hash is empty, and do not generate it
3343     for (auto Val : Hash) {
3344       if (Val)
3345         AllZero = false;
3346       Vals.push_back(Val);
3347     }
3348     if (!AllZero) {
3349       // Emit the hash record.
3350       Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3351     }
3352 
3353     Vals.clear();
3354   }
3355   Stream.ExitBlock();
3356 }
3357 
3358 // Helper to emit a single function summary record.
3359 void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
3360     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3361     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3362     const Function &F) {
3363   NameVals.push_back(ValueID);
3364 
3365   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3366   if (!FS->type_tests().empty())
3367     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3368 
3369   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3370   NameVals.push_back(FS->instCount());
3371   NameVals.push_back(FS->refs().size());
3372 
3373   for (auto &RI : FS->refs())
3374     NameVals.push_back(VE.getValueID(RI.getValue()));
3375 
3376   bool HasProfileData = F.getEntryCount().hasValue();
3377   for (auto &ECI : FS->calls()) {
3378     NameVals.push_back(getValueId(ECI.first));
3379     if (HasProfileData)
3380       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3381   }
3382 
3383   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3384   unsigned Code =
3385       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
3386 
3387   // Emit the finished record.
3388   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3389   NameVals.clear();
3390 }
3391 
3392 // Collect the global value references in the given variable's initializer,
3393 // and emit them in a summary record.
3394 void ModuleBitcodeWriter::writeModuleLevelReferences(
3395     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3396     unsigned FSModRefsAbbrev) {
3397   auto Summaries =
3398       Index->findGlobalValueSummaryList(GlobalValue::getGUID(V.getName()));
3399   if (Summaries == Index->end()) {
3400     // Only declarations should not have a summary (a declaration might however
3401     // have a summary if the def was in module level asm).
3402     assert(V.isDeclaration());
3403     return;
3404   }
3405   auto *Summary = Summaries->second.front().get();
3406   NameVals.push_back(VE.getValueID(&V));
3407   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3408   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3409 
3410   unsigned SizeBeforeRefs = NameVals.size();
3411   for (auto &RI : VS->refs())
3412     NameVals.push_back(VE.getValueID(RI.getValue()));
3413   // Sort the refs for determinism output, the vector returned by FS->refs() has
3414   // been initialized from a DenseSet.
3415   std::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3416 
3417   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3418                     FSModRefsAbbrev);
3419   NameVals.clear();
3420 }
3421 
3422 // Current version for the summary.
3423 // This is bumped whenever we introduce changes in the way some record are
3424 // interpreted, like flags for instance.
3425 static const uint64_t INDEX_VERSION = 2;
3426 
3427 /// Emit the per-module summary section alongside the rest of
3428 /// the module's bitcode.
3429 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
3430   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 4);
3431 
3432   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3433 
3434   if (Index->begin() == Index->end()) {
3435     Stream.ExitBlock();
3436     return;
3437   }
3438 
3439   // Abbrev for FS_PERMODULE.
3440   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3441   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3442   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3443   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3444   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3445   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3446   // numrefs x valueid, n x (valueid)
3447   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3448   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3449   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3450 
3451   // Abbrev for FS_PERMODULE_PROFILE.
3452   Abbv = new BitCodeAbbrev();
3453   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3454   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3455   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3456   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3457   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3458   // numrefs x valueid, n x (valueid, hotness)
3459   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3460   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3461   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3462 
3463   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3464   Abbv = new BitCodeAbbrev();
3465   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3466   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3467   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3468   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3469   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3470   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3471 
3472   // Abbrev for FS_ALIAS.
3473   Abbv = new BitCodeAbbrev();
3474   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3475   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3476   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3477   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3478   unsigned FSAliasAbbrev = Stream.EmitAbbrev(Abbv);
3479 
3480   SmallVector<uint64_t, 64> NameVals;
3481   // Iterate over the list of functions instead of the Index to
3482   // ensure the ordering is stable.
3483   for (const Function &F : M) {
3484     // Summary emission does not support anonymous functions, they have to
3485     // renamed using the anonymous function renaming pass.
3486     if (!F.hasName())
3487       report_fatal_error("Unexpected anonymous function when writing summary");
3488 
3489     auto Summaries =
3490         Index->findGlobalValueSummaryList(GlobalValue::getGUID(F.getName()));
3491     if (Summaries == Index->end()) {
3492       // Only declarations should not have a summary (a declaration might
3493       // however have a summary if the def was in module level asm).
3494       assert(F.isDeclaration());
3495       continue;
3496     }
3497     auto *Summary = Summaries->second.front().get();
3498     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3499                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3500   }
3501 
3502   // Capture references from GlobalVariable initializers, which are outside
3503   // of a function scope.
3504   for (const GlobalVariable &G : M.globals())
3505     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3506 
3507   for (const GlobalAlias &A : M.aliases()) {
3508     auto *Aliasee = A.getBaseObject();
3509     if (!Aliasee->hasName())
3510       // Nameless function don't have an entry in the summary, skip it.
3511       continue;
3512     auto AliasId = VE.getValueID(&A);
3513     auto AliaseeId = VE.getValueID(Aliasee);
3514     NameVals.push_back(AliasId);
3515     auto *Summary = Index->getGlobalValueSummary(A);
3516     AliasSummary *AS = cast<AliasSummary>(Summary);
3517     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3518     NameVals.push_back(AliaseeId);
3519     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3520     NameVals.clear();
3521   }
3522 
3523   Stream.ExitBlock();
3524 }
3525 
3526 /// Emit the combined summary section into the combined index file.
3527 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3528   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3529   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3530 
3531   // Abbrev for FS_COMBINED.
3532   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3533   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3534   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3535   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3536   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3537   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3538   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3539   // numrefs x valueid, n x (valueid)
3540   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3541   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3542   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3543 
3544   // Abbrev for FS_COMBINED_PROFILE.
3545   Abbv = new BitCodeAbbrev();
3546   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3547   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3548   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3549   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3550   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3551   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3552   // numrefs x valueid, n x (valueid, hotness)
3553   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3555   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3556 
3557   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3558   Abbv = new BitCodeAbbrev();
3559   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3560   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3561   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3562   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3563   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3564   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3565   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3566 
3567   // Abbrev for FS_COMBINED_ALIAS.
3568   Abbv = new BitCodeAbbrev();
3569   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3570   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3571   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3572   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3573   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3574   unsigned FSAliasAbbrev = Stream.EmitAbbrev(Abbv);
3575 
3576   // The aliases are emitted as a post-pass, and will point to the value
3577   // id of the aliasee. Save them in a vector for post-processing.
3578   SmallVector<AliasSummary *, 64> Aliases;
3579 
3580   // Save the value id for each summary for alias emission.
3581   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3582 
3583   SmallVector<uint64_t, 64> NameVals;
3584 
3585   // For local linkage, we also emit the original name separately
3586   // immediately after the record.
3587   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3588     if (!GlobalValue::isLocalLinkage(S.linkage()))
3589       return;
3590     NameVals.push_back(S.getOriginalName());
3591     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3592     NameVals.clear();
3593   };
3594 
3595   for (const auto &I : *this) {
3596     GlobalValueSummary *S = I.second;
3597     assert(S);
3598 
3599     assert(hasValueId(I.first));
3600     unsigned ValueId = getValueId(I.first);
3601     SummaryToValueIdMap[S] = ValueId;
3602 
3603     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3604       // Will process aliases as a post-pass because the reader wants all
3605       // global to be loaded first.
3606       Aliases.push_back(AS);
3607       continue;
3608     }
3609 
3610     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3611       NameVals.push_back(ValueId);
3612       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3613       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3614       for (auto &RI : VS->refs()) {
3615         NameVals.push_back(getValueId(RI.getGUID()));
3616       }
3617 
3618       // Emit the finished record.
3619       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3620                         FSModRefsAbbrev);
3621       NameVals.clear();
3622       MaybeEmitOriginalName(*S);
3623       continue;
3624     }
3625 
3626     auto *FS = cast<FunctionSummary>(S);
3627     if (!FS->type_tests().empty())
3628       Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3629 
3630     NameVals.push_back(ValueId);
3631     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3632     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3633     NameVals.push_back(FS->instCount());
3634     NameVals.push_back(FS->refs().size());
3635 
3636     for (auto &RI : FS->refs()) {
3637       NameVals.push_back(getValueId(RI.getGUID()));
3638     }
3639 
3640     bool HasProfileData = false;
3641     for (auto &EI : FS->calls()) {
3642       HasProfileData |= EI.second.Hotness != CalleeInfo::HotnessType::Unknown;
3643       if (HasProfileData)
3644         break;
3645     }
3646 
3647     for (auto &EI : FS->calls()) {
3648       // If this GUID doesn't have a value id, it doesn't have a function
3649       // summary and we don't need to record any calls to it.
3650       if (!hasValueId(EI.first.getGUID()))
3651         continue;
3652       NameVals.push_back(getValueId(EI.first.getGUID()));
3653       if (HasProfileData)
3654         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3655     }
3656 
3657     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3658     unsigned Code =
3659         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3660 
3661     // Emit the finished record.
3662     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3663     NameVals.clear();
3664     MaybeEmitOriginalName(*S);
3665   }
3666 
3667   for (auto *AS : Aliases) {
3668     auto AliasValueId = SummaryToValueIdMap[AS];
3669     assert(AliasValueId);
3670     NameVals.push_back(AliasValueId);
3671     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3672     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3673     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3674     assert(AliaseeValueId);
3675     NameVals.push_back(AliaseeValueId);
3676 
3677     // Emit the finished record.
3678     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3679     NameVals.clear();
3680     MaybeEmitOriginalName(*AS);
3681   }
3682 
3683   Stream.ExitBlock();
3684 }
3685 
3686 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3687 /// current llvm version, and a record for the epoch number.
3688 void writeIdentificationBlock(BitstreamWriter &Stream) {
3689   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3690 
3691   // Write the "user readable" string identifying the bitcode producer
3692   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3693   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3694   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3695   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3696   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3697   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3698                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3699 
3700   // Write the epoch version
3701   Abbv = new BitCodeAbbrev();
3702   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3703   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3704   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3705   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3706   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3707   Stream.ExitBlock();
3708 }
3709 
3710 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3711   // Emit the module's hash.
3712   // MODULE_CODE_HASH: [5*i32]
3713   SHA1 Hasher;
3714   Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3715                                   Buffer.size() - BlockStartPos));
3716   StringRef Hash = Hasher.result();
3717   uint32_t Vals[5];
3718   for (int Pos = 0; Pos < 20; Pos += 4) {
3719     Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3720   }
3721 
3722   // Emit the finished record.
3723   Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3724 }
3725 
3726 void ModuleBitcodeWriter::write() {
3727   writeIdentificationBlock(Stream);
3728 
3729   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3730   size_t BlockStartPos = Buffer.size();
3731 
3732   SmallVector<unsigned, 1> Vals;
3733   unsigned CurVersion = 1;
3734   Vals.push_back(CurVersion);
3735   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3736 
3737   // Emit blockinfo, which defines the standard abbreviations etc.
3738   writeBlockInfo();
3739 
3740   // Emit information about attribute groups.
3741   writeAttributeGroupTable();
3742 
3743   // Emit information about parameter attributes.
3744   writeAttributeTable();
3745 
3746   // Emit information describing all of the types in the module.
3747   writeTypeTable();
3748 
3749   writeComdats();
3750 
3751   // Emit top-level description of module, including target triple, inline asm,
3752   // descriptors for global variables, and function prototype info.
3753   writeModuleInfo();
3754 
3755   // Emit constants.
3756   writeModuleConstants();
3757 
3758   // Emit metadata kind names.
3759   writeModuleMetadataKinds();
3760 
3761   // Emit metadata.
3762   writeModuleMetadata();
3763 
3764   // Emit module-level use-lists.
3765   if (VE.shouldPreserveUseListOrder())
3766     writeUseListBlock(nullptr);
3767 
3768   writeOperandBundleTags();
3769 
3770   // Emit function bodies.
3771   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3772   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3773     if (!F->isDeclaration())
3774       writeFunction(*F, FunctionToBitcodeIndex);
3775 
3776   // Need to write after the above call to WriteFunction which populates
3777   // the summary information in the index.
3778   if (Index)
3779     writePerModuleGlobalValueSummary();
3780 
3781   writeValueSymbolTable(M.getValueSymbolTable(),
3782                         /* IsModuleLevel */ true, &FunctionToBitcodeIndex);
3783 
3784   if (GenerateHash) {
3785     writeModuleHash(BlockStartPos);
3786   }
3787 
3788   Stream.ExitBlock();
3789 }
3790 
3791 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3792                                uint32_t &Position) {
3793   support::endian::write32le(&Buffer[Position], Value);
3794   Position += 4;
3795 }
3796 
3797 /// If generating a bc file on darwin, we have to emit a
3798 /// header and trailer to make it compatible with the system archiver.  To do
3799 /// this we emit the following header, and then emit a trailer that pads the
3800 /// file out to be a multiple of 16 bytes.
3801 ///
3802 /// struct bc_header {
3803 ///   uint32_t Magic;         // 0x0B17C0DE
3804 ///   uint32_t Version;       // Version, currently always 0.
3805 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3806 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3807 ///   uint32_t CPUType;       // CPU specifier.
3808 ///   ... potentially more later ...
3809 /// };
3810 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3811                                          const Triple &TT) {
3812   unsigned CPUType = ~0U;
3813 
3814   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3815   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3816   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3817   // specific constants here because they are implicitly part of the Darwin ABI.
3818   enum {
3819     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3820     DARWIN_CPU_TYPE_X86        = 7,
3821     DARWIN_CPU_TYPE_ARM        = 12,
3822     DARWIN_CPU_TYPE_POWERPC    = 18
3823   };
3824 
3825   Triple::ArchType Arch = TT.getArch();
3826   if (Arch == Triple::x86_64)
3827     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3828   else if (Arch == Triple::x86)
3829     CPUType = DARWIN_CPU_TYPE_X86;
3830   else if (Arch == Triple::ppc)
3831     CPUType = DARWIN_CPU_TYPE_POWERPC;
3832   else if (Arch == Triple::ppc64)
3833     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3834   else if (Arch == Triple::arm || Arch == Triple::thumb)
3835     CPUType = DARWIN_CPU_TYPE_ARM;
3836 
3837   // Traditional Bitcode starts after header.
3838   assert(Buffer.size() >= BWH_HeaderSize &&
3839          "Expected header size to be reserved");
3840   unsigned BCOffset = BWH_HeaderSize;
3841   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3842 
3843   // Write the magic and version.
3844   unsigned Position = 0;
3845   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
3846   writeInt32ToBuffer(0, Buffer, Position); // Version.
3847   writeInt32ToBuffer(BCOffset, Buffer, Position);
3848   writeInt32ToBuffer(BCSize, Buffer, Position);
3849   writeInt32ToBuffer(CPUType, Buffer, Position);
3850 
3851   // If the file is not a multiple of 16 bytes, insert dummy padding.
3852   while (Buffer.size() & 15)
3853     Buffer.push_back(0);
3854 }
3855 
3856 /// Helper to write the header common to all bitcode files.
3857 static void writeBitcodeHeader(BitstreamWriter &Stream) {
3858   // Emit the file header.
3859   Stream.Emit((unsigned)'B', 8);
3860   Stream.Emit((unsigned)'C', 8);
3861   Stream.Emit(0x0, 4);
3862   Stream.Emit(0xC, 4);
3863   Stream.Emit(0xE, 4);
3864   Stream.Emit(0xD, 4);
3865 }
3866 
3867 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
3868     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
3869   writeBitcodeHeader(*Stream);
3870 }
3871 
3872 BitcodeWriter::~BitcodeWriter() = default;
3873 
3874 void BitcodeWriter::writeModule(const Module *M,
3875                                 bool ShouldPreserveUseListOrder,
3876                                 const ModuleSummaryIndex *Index,
3877                                 bool GenerateHash) {
3878   ModuleBitcodeWriter ModuleWriter(
3879       M, Buffer, *Stream, ShouldPreserveUseListOrder, Index, GenerateHash);
3880   ModuleWriter.write();
3881 }
3882 
3883 /// WriteBitcodeToFile - Write the specified module to the specified output
3884 /// stream.
3885 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3886                               bool ShouldPreserveUseListOrder,
3887                               const ModuleSummaryIndex *Index,
3888                               bool GenerateHash) {
3889   SmallVector<char, 0> Buffer;
3890   Buffer.reserve(256*1024);
3891 
3892   // If this is darwin or another generic macho target, reserve space for the
3893   // header.
3894   Triple TT(M->getTargetTriple());
3895   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3896     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3897 
3898   BitcodeWriter Writer(Buffer);
3899   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash);
3900 
3901   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3902     emitDarwinBCHeaderAndTrailer(Buffer, TT);
3903 
3904   // Write the generated bitstream to "Out".
3905   Out.write((char*)&Buffer.front(), Buffer.size());
3906 }
3907 
3908 void IndexBitcodeWriter::write() {
3909   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3910 
3911   SmallVector<unsigned, 1> Vals;
3912   unsigned CurVersion = 1;
3913   Vals.push_back(CurVersion);
3914   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3915 
3916   // If we have a VST, write the VSTOFFSET record placeholder.
3917   writeValueSymbolTableForwardDecl();
3918 
3919   // Write the module paths in the combined index.
3920   writeModStrings();
3921 
3922   // Write the summary combined index records.
3923   writeCombinedGlobalValueSummary();
3924 
3925   // Need a special VST writer for the combined index (we don't have a
3926   // real VST and real values when this is invoked).
3927   writeCombinedValueSymbolTable();
3928 
3929   Stream.ExitBlock();
3930 }
3931 
3932 // Write the specified module summary index to the given raw output stream,
3933 // where it will be written in a new bitcode block. This is used when
3934 // writing the combined index file for ThinLTO. When writing a subset of the
3935 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
3936 void llvm::WriteIndexToFile(
3937     const ModuleSummaryIndex &Index, raw_ostream &Out,
3938     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
3939   SmallVector<char, 0> Buffer;
3940   Buffer.reserve(256 * 1024);
3941 
3942   BitstreamWriter Stream(Buffer);
3943   writeBitcodeHeader(Stream);
3944 
3945   IndexBitcodeWriter IndexWriter(Stream, Index, ModuleToSummariesForIndex);
3946   IndexWriter.write();
3947 
3948   Out.write((char *)&Buffer.front(), Buffer.size());
3949 }
3950