xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 4a435e0896fd59510afa1e8b99e37e1dcd14f317)
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 
42 cl::opt<unsigned>
43     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
44                    cl::desc("Number of metadatas above which we emit an index "
45                             "to enable lazy-loading"));
46 /// These are manifest constants used by the bitcode writer. They do not need to
47 /// be kept in sync with the reader, but need to be consistent within this file.
48 enum {
49   // VALUE_SYMTAB_BLOCK abbrev id's.
50   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
51   VST_ENTRY_7_ABBREV,
52   VST_ENTRY_6_ABBREV,
53   VST_BBENTRY_6_ABBREV,
54 
55   // CONSTANTS_BLOCK abbrev id's.
56   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
57   CONSTANTS_INTEGER_ABBREV,
58   CONSTANTS_CE_CAST_Abbrev,
59   CONSTANTS_NULL_Abbrev,
60 
61   // FUNCTION_BLOCK abbrev id's.
62   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
63   FUNCTION_INST_BINOP_ABBREV,
64   FUNCTION_INST_BINOP_FLAGS_ABBREV,
65   FUNCTION_INST_CAST_ABBREV,
66   FUNCTION_INST_RET_VOID_ABBREV,
67   FUNCTION_INST_RET_VAL_ABBREV,
68   FUNCTION_INST_UNREACHABLE_ABBREV,
69   FUNCTION_INST_GEP_ABBREV,
70 };
71 
72 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
73 /// file type.
74 class BitcodeWriterBase {
75 protected:
76   /// The stream created and owned by the client.
77   BitstreamWriter &Stream;
78 
79   /// Saves the offset of the VSTOffset record that must eventually be
80   /// backpatched with the offset of the actual VST.
81   uint64_t VSTOffsetPlaceholder = 0;
82 
83 public:
84   /// Constructs a BitcodeWriterBase object that writes to the provided
85   /// \p Stream.
86   BitcodeWriterBase(BitstreamWriter &Stream) : Stream(Stream) {}
87 
88 protected:
89   bool hasVSTOffsetPlaceholder() { return VSTOffsetPlaceholder != 0; }
90   void writeValueSymbolTableForwardDecl();
91   void writeBitcodeHeader();
92 };
93 
94 /// Class to manage the bitcode writing for a module.
95 class ModuleBitcodeWriter : public BitcodeWriterBase {
96   /// Pointer to the buffer allocated by caller for bitcode writing.
97   const SmallVectorImpl<char> &Buffer;
98 
99   /// The Module to write to bitcode.
100   const Module &M;
101 
102   /// Enumerates ids for all values in the module.
103   ValueEnumerator VE;
104 
105   /// Optional per-module index to write for ThinLTO.
106   const ModuleSummaryIndex *Index;
107 
108   /// True if a module hash record should be written.
109   bool GenerateHash;
110 
111   /// The start bit of the identification block.
112   uint64_t BitcodeStartBit;
113 
114   /// Map that holds the correspondence between GUIDs in the summary index,
115   /// that came from indirect call profiles, and a value id generated by this
116   /// class to use in the VST and summary block records.
117   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
118 
119   /// Tracks the last value id recorded in the GUIDToValueMap.
120   unsigned GlobalValueId;
121 
122 public:
123   /// Constructs a ModuleBitcodeWriter object for the given Module,
124   /// writing to the provided \p Buffer.
125   ModuleBitcodeWriter(const Module *M, SmallVectorImpl<char> &Buffer,
126                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
127                       const ModuleSummaryIndex *Index, bool GenerateHash)
128       : BitcodeWriterBase(Stream), Buffer(Buffer), M(*M),
129         VE(*M, ShouldPreserveUseListOrder), Index(Index),
130         GenerateHash(GenerateHash), BitcodeStartBit(Stream.GetCurrentBitNo()) {
131     // Assign ValueIds to any callee values in the index that came from
132     // indirect call profiles and were recorded as a GUID not a Value*
133     // (which would have been assigned an ID by the ValueEnumerator).
134     // The starting ValueId is just after the number of values in the
135     // ValueEnumerator, so that they can be emitted in the VST.
136     GlobalValueId = VE.getValues().size();
137     if (!Index)
138       return;
139     for (const auto &GUIDSummaryLists : *Index)
140       // Examine all summaries for this GUID.
141       for (auto &Summary : GUIDSummaryLists.second)
142         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
143           // For each call in the function summary, see if the call
144           // is to a GUID (which means it is for an indirect call,
145           // otherwise we would have a Value for it). If so, synthesize
146           // a value id.
147           for (auto &CallEdge : FS->calls())
148             if (CallEdge.first.isGUID())
149               assignValueId(CallEdge.first.getGUID());
150   }
151 
152   /// Emit the current module to the bitstream.
153   void write();
154 
155 private:
156   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
157 
158   void writeAttributeGroupTable();
159   void writeAttributeTable();
160   void writeTypeTable();
161   void writeComdats();
162   void writeModuleInfo();
163   void writeValueAsMetadata(const ValueAsMetadata *MD,
164                             SmallVectorImpl<uint64_t> &Record);
165   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
166                     unsigned Abbrev);
167   unsigned createDILocationAbbrev();
168   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
169                        unsigned &Abbrev);
170   unsigned createGenericDINodeAbbrev();
171   void writeGenericDINode(const GenericDINode *N,
172                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
173   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
174                        unsigned Abbrev);
175   void writeDIEnumerator(const DIEnumerator *N,
176                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
177   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
178                         unsigned Abbrev);
179   void writeDIDerivedType(const DIDerivedType *N,
180                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
181   void writeDICompositeType(const DICompositeType *N,
182                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
183   void writeDISubroutineType(const DISubroutineType *N,
184                              SmallVectorImpl<uint64_t> &Record,
185                              unsigned Abbrev);
186   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
187                    unsigned Abbrev);
188   void writeDICompileUnit(const DICompileUnit *N,
189                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
190   void writeDISubprogram(const DISubprogram *N,
191                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
192   void writeDILexicalBlock(const DILexicalBlock *N,
193                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
194   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
195                                SmallVectorImpl<uint64_t> &Record,
196                                unsigned Abbrev);
197   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
198                         unsigned Abbrev);
199   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
200                     unsigned Abbrev);
201   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
202                         unsigned Abbrev);
203   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
204                      unsigned Abbrev);
205   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
206                                     SmallVectorImpl<uint64_t> &Record,
207                                     unsigned Abbrev);
208   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
209                                      SmallVectorImpl<uint64_t> &Record,
210                                      unsigned Abbrev);
211   void writeDIGlobalVariable(const DIGlobalVariable *N,
212                              SmallVectorImpl<uint64_t> &Record,
213                              unsigned Abbrev);
214   void writeDILocalVariable(const DILocalVariable *N,
215                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
216   void writeDIExpression(const DIExpression *N,
217                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
218   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
219                                        SmallVectorImpl<uint64_t> &Record,
220                                        unsigned Abbrev);
221   void writeDIObjCProperty(const DIObjCProperty *N,
222                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
223   void writeDIImportedEntity(const DIImportedEntity *N,
224                              SmallVectorImpl<uint64_t> &Record,
225                              unsigned Abbrev);
226   unsigned createNamedMetadataAbbrev();
227   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
228   unsigned createMetadataStringsAbbrev();
229   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
230                             SmallVectorImpl<uint64_t> &Record);
231   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
232                             SmallVectorImpl<uint64_t> &Record,
233                             std::vector<unsigned> *MDAbbrevs = nullptr,
234                             std::vector<uint64_t> *IndexPos = nullptr);
235   void writeModuleMetadata();
236   void writeFunctionMetadata(const Function &F);
237   void writeFunctionMetadataAttachment(const Function &F);
238   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
239   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
240                                     const GlobalObject &GO);
241   void writeModuleMetadataKinds();
242   void writeOperandBundleTags();
243   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
244   void writeModuleConstants();
245   bool pushValueAndType(const Value *V, unsigned InstID,
246                         SmallVectorImpl<unsigned> &Vals);
247   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
248   void pushValue(const Value *V, unsigned InstID,
249                  SmallVectorImpl<unsigned> &Vals);
250   void pushValueSigned(const Value *V, unsigned InstID,
251                        SmallVectorImpl<uint64_t> &Vals);
252   void writeInstruction(const Instruction &I, unsigned InstID,
253                         SmallVectorImpl<unsigned> &Vals);
254   void writeValueSymbolTable(
255       const ValueSymbolTable &VST, bool IsModuleLevel = false,
256       DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex = nullptr);
257   void writeUseList(UseListOrder &&Order);
258   void writeUseListBlock(const Function *F);
259   void
260   writeFunction(const Function &F,
261                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
262   void writeBlockInfo();
263   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
264                                            GlobalValueSummary *Summary,
265                                            unsigned ValueID,
266                                            unsigned FSCallsAbbrev,
267                                            unsigned FSCallsProfileAbbrev,
268                                            const Function &F);
269   void writeModuleLevelReferences(const GlobalVariable &V,
270                                   SmallVector<uint64_t, 64> &NameVals,
271                                   unsigned FSModRefsAbbrev);
272   void writePerModuleGlobalValueSummary();
273   void writeModuleHash(size_t BlockStartPos);
274 
275   void assignValueId(GlobalValue::GUID ValGUID) {
276     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
277   }
278   unsigned getValueId(GlobalValue::GUID ValGUID) {
279     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
280     // Expect that any GUID value had a value Id assigned by an
281     // earlier call to assignValueId.
282     assert(VMI != GUIDToValueIdMap.end() &&
283            "GUID does not have assigned value Id");
284     return VMI->second;
285   }
286   // Helper to get the valueId for the type of value recorded in VI.
287   unsigned getValueId(ValueInfo VI) {
288     if (VI.isGUID())
289       return getValueId(VI.getGUID());
290     return VE.getValueID(VI.getValue());
291   }
292   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
293 };
294 
295 /// Class to manage the bitcode writing for a combined index.
296 class IndexBitcodeWriter : public BitcodeWriterBase {
297   /// The combined index to write to bitcode.
298   const ModuleSummaryIndex &Index;
299 
300   /// When writing a subset of the index for distributed backends, client
301   /// provides a map of modules to the corresponding GUIDs/summaries to write.
302   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
303 
304   /// Map that holds the correspondence between the GUID used in the combined
305   /// index and a value id generated by this class to use in references.
306   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
307 
308   /// Tracks the last value id recorded in the GUIDToValueMap.
309   unsigned GlobalValueId = 0;
310 
311 public:
312   /// Constructs a IndexBitcodeWriter object for the given combined index,
313   /// writing to the provided \p Buffer. When writing a subset of the index
314   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
315   IndexBitcodeWriter(BitstreamWriter &Stream, const ModuleSummaryIndex &Index,
316                      const std::map<std::string, GVSummaryMapTy>
317                          *ModuleToSummariesForIndex = nullptr)
318       : BitcodeWriterBase(Stream), Index(Index),
319         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
320     // Assign unique value ids to all summaries to be written, for use
321     // in writing out the call graph edges. Save the mapping from GUID
322     // to the new global value id to use when writing those edges, which
323     // are currently saved in the index in terms of GUID.
324     for (const auto &I : *this)
325       GUIDToValueIdMap[I.first] = ++GlobalValueId;
326   }
327 
328   /// The below iterator returns the GUID and associated summary.
329   typedef std::pair<GlobalValue::GUID, GlobalValueSummary *> GVInfo;
330 
331   /// Iterator over the value GUID and summaries to be written to bitcode,
332   /// hides the details of whether they are being pulled from the entire
333   /// index or just those in a provided ModuleToSummariesForIndex map.
334   class iterator
335       : public llvm::iterator_facade_base<iterator, std::forward_iterator_tag,
336                                           GVInfo> {
337     /// Enables access to parent class.
338     const IndexBitcodeWriter &Writer;
339 
340     // Iterators used when writing only those summaries in a provided
341     // ModuleToSummariesForIndex map:
342 
343     /// Points to the last element in outer ModuleToSummariesForIndex map.
344     std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesBack;
345     /// Iterator on outer ModuleToSummariesForIndex map.
346     std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesIter;
347     /// Iterator on an inner global variable summary map.
348     GVSummaryMapTy::const_iterator ModuleGVSummariesIter;
349 
350     // Iterators used when writing all summaries in the index:
351 
352     /// Points to the last element in the Index outer GlobalValueMap.
353     const_gvsummary_iterator IndexSummariesBack;
354     /// Iterator on outer GlobalValueMap.
355     const_gvsummary_iterator IndexSummariesIter;
356     /// Iterator on an inner GlobalValueSummaryList.
357     GlobalValueSummaryList::const_iterator IndexGVSummariesIter;
358 
359   public:
360     /// Construct iterator from parent \p Writer and indicate if we are
361     /// constructing the end iterator.
362     iterator(const IndexBitcodeWriter &Writer, bool IsAtEnd) : Writer(Writer) {
363       // Set up the appropriate set of iterators given whether we are writing
364       // the full index or just a subset.
365       // Can't setup the Back or inner iterators if the corresponding map
366       // is empty. This will be handled specially in operator== as well.
367       if (Writer.ModuleToSummariesForIndex &&
368           !Writer.ModuleToSummariesForIndex->empty()) {
369         for (ModuleSummariesBack = Writer.ModuleToSummariesForIndex->begin();
370              std::next(ModuleSummariesBack) !=
371              Writer.ModuleToSummariesForIndex->end();
372              ModuleSummariesBack++)
373           ;
374         ModuleSummariesIter = !IsAtEnd
375                                   ? Writer.ModuleToSummariesForIndex->begin()
376                                   : ModuleSummariesBack;
377         ModuleGVSummariesIter = !IsAtEnd ? ModuleSummariesIter->second.begin()
378                                          : ModuleSummariesBack->second.end();
379       } else if (!Writer.ModuleToSummariesForIndex &&
380                  Writer.Index.begin() != Writer.Index.end()) {
381         for (IndexSummariesBack = Writer.Index.begin();
382              std::next(IndexSummariesBack) != Writer.Index.end();
383              IndexSummariesBack++)
384           ;
385         IndexSummariesIter =
386             !IsAtEnd ? Writer.Index.begin() : IndexSummariesBack;
387         IndexGVSummariesIter = !IsAtEnd ? IndexSummariesIter->second.begin()
388                                         : IndexSummariesBack->second.end();
389       }
390     }
391 
392     /// Increment the appropriate set of iterators.
393     iterator &operator++() {
394       // First the inner iterator is incremented, then if it is at the end
395       // and there are more outer iterations to go, the inner is reset to
396       // the start of the next inner list.
397       if (Writer.ModuleToSummariesForIndex) {
398         ++ModuleGVSummariesIter;
399         if (ModuleGVSummariesIter == ModuleSummariesIter->second.end() &&
400             ModuleSummariesIter != ModuleSummariesBack) {
401           ++ModuleSummariesIter;
402           ModuleGVSummariesIter = ModuleSummariesIter->second.begin();
403         }
404       } else {
405         ++IndexGVSummariesIter;
406         if (IndexGVSummariesIter == IndexSummariesIter->second.end() &&
407             IndexSummariesIter != IndexSummariesBack) {
408           ++IndexSummariesIter;
409           IndexGVSummariesIter = IndexSummariesIter->second.begin();
410         }
411       }
412       return *this;
413     }
414 
415     /// Access the <GUID,GlobalValueSummary*> pair corresponding to the current
416     /// outer and inner iterator positions.
417     GVInfo operator*() {
418       if (Writer.ModuleToSummariesForIndex)
419         return std::make_pair(ModuleGVSummariesIter->first,
420                               ModuleGVSummariesIter->second);
421       return std::make_pair(IndexSummariesIter->first,
422                             IndexGVSummariesIter->get());
423     }
424 
425     /// Checks if the iterators are equal, with special handling for empty
426     /// indexes.
427     bool operator==(const iterator &RHS) const {
428       if (Writer.ModuleToSummariesForIndex) {
429         // First ensure that both are writing the same subset.
430         if (Writer.ModuleToSummariesForIndex !=
431             RHS.Writer.ModuleToSummariesForIndex)
432           return false;
433         // Already determined above that maps are the same, so if one is
434         // empty, they both are.
435         if (Writer.ModuleToSummariesForIndex->empty())
436           return true;
437         // Ensure the ModuleGVSummariesIter are iterating over the same
438         // container before checking them below.
439         if (ModuleSummariesIter != RHS.ModuleSummariesIter)
440           return false;
441         return ModuleGVSummariesIter == RHS.ModuleGVSummariesIter;
442       }
443       // First ensure RHS also writing the full index, and that both are
444       // writing the same full index.
445       if (RHS.Writer.ModuleToSummariesForIndex ||
446           &Writer.Index != &RHS.Writer.Index)
447         return false;
448       // Already determined above that maps are the same, so if one is
449       // empty, they both are.
450       if (Writer.Index.begin() == Writer.Index.end())
451         return true;
452       // Ensure the IndexGVSummariesIter are iterating over the same
453       // container before checking them below.
454       if (IndexSummariesIter != RHS.IndexSummariesIter)
455         return false;
456       return IndexGVSummariesIter == RHS.IndexGVSummariesIter;
457     }
458   };
459 
460   /// Obtain the start iterator over the summaries to be written.
461   iterator begin() { return iterator(*this, /*IsAtEnd=*/false); }
462   /// Obtain the end iterator over the summaries to be written.
463   iterator end() { return iterator(*this, /*IsAtEnd=*/true); }
464 
465   /// Main entry point for writing a combined index to bitcode.
466   void write();
467 
468 private:
469   void writeIndex();
470   void writeModStrings();
471   void writeCombinedValueSymbolTable();
472   void writeCombinedGlobalValueSummary();
473 
474   /// Indicates whether the provided \p ModulePath should be written into
475   /// the module string table, e.g. if full index written or if it is in
476   /// the provided subset.
477   bool doIncludeModule(StringRef ModulePath) {
478     return !ModuleToSummariesForIndex ||
479            ModuleToSummariesForIndex->count(ModulePath);
480   }
481 
482   bool hasValueId(GlobalValue::GUID ValGUID) {
483     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
484     return VMI != GUIDToValueIdMap.end();
485   }
486   unsigned getValueId(GlobalValue::GUID ValGUID) {
487     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
488     // If this GUID doesn't have an entry, assign one.
489     if (VMI == GUIDToValueIdMap.end()) {
490       GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
491       return GlobalValueId;
492     } else {
493       return VMI->second;
494     }
495   }
496   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
497 };
498 } // end anonymous namespace
499 
500 static unsigned getEncodedCastOpcode(unsigned Opcode) {
501   switch (Opcode) {
502   default: llvm_unreachable("Unknown cast instruction!");
503   case Instruction::Trunc   : return bitc::CAST_TRUNC;
504   case Instruction::ZExt    : return bitc::CAST_ZEXT;
505   case Instruction::SExt    : return bitc::CAST_SEXT;
506   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
507   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
508   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
509   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
510   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
511   case Instruction::FPExt   : return bitc::CAST_FPEXT;
512   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
513   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
514   case Instruction::BitCast : return bitc::CAST_BITCAST;
515   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
516   }
517 }
518 
519 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
520   switch (Opcode) {
521   default: llvm_unreachable("Unknown binary instruction!");
522   case Instruction::Add:
523   case Instruction::FAdd: return bitc::BINOP_ADD;
524   case Instruction::Sub:
525   case Instruction::FSub: return bitc::BINOP_SUB;
526   case Instruction::Mul:
527   case Instruction::FMul: return bitc::BINOP_MUL;
528   case Instruction::UDiv: return bitc::BINOP_UDIV;
529   case Instruction::FDiv:
530   case Instruction::SDiv: return bitc::BINOP_SDIV;
531   case Instruction::URem: return bitc::BINOP_UREM;
532   case Instruction::FRem:
533   case Instruction::SRem: return bitc::BINOP_SREM;
534   case Instruction::Shl:  return bitc::BINOP_SHL;
535   case Instruction::LShr: return bitc::BINOP_LSHR;
536   case Instruction::AShr: return bitc::BINOP_ASHR;
537   case Instruction::And:  return bitc::BINOP_AND;
538   case Instruction::Or:   return bitc::BINOP_OR;
539   case Instruction::Xor:  return bitc::BINOP_XOR;
540   }
541 }
542 
543 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
544   switch (Op) {
545   default: llvm_unreachable("Unknown RMW operation!");
546   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
547   case AtomicRMWInst::Add: return bitc::RMW_ADD;
548   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
549   case AtomicRMWInst::And: return bitc::RMW_AND;
550   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
551   case AtomicRMWInst::Or: return bitc::RMW_OR;
552   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
553   case AtomicRMWInst::Max: return bitc::RMW_MAX;
554   case AtomicRMWInst::Min: return bitc::RMW_MIN;
555   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
556   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
557   }
558 }
559 
560 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
561   switch (Ordering) {
562   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
563   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
564   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
565   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
566   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
567   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
568   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
569   }
570   llvm_unreachable("Invalid ordering");
571 }
572 
573 static unsigned getEncodedSynchScope(SynchronizationScope SynchScope) {
574   switch (SynchScope) {
575   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
576   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
577   }
578   llvm_unreachable("Invalid synch scope");
579 }
580 
581 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
582                               StringRef Str, unsigned AbbrevToUse) {
583   SmallVector<unsigned, 64> Vals;
584 
585   // Code: [strchar x N]
586   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
587     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
588       AbbrevToUse = 0;
589     Vals.push_back(Str[i]);
590   }
591 
592   // Emit the finished record.
593   Stream.EmitRecord(Code, Vals, AbbrevToUse);
594 }
595 
596 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
597   switch (Kind) {
598   case Attribute::Alignment:
599     return bitc::ATTR_KIND_ALIGNMENT;
600   case Attribute::AllocSize:
601     return bitc::ATTR_KIND_ALLOC_SIZE;
602   case Attribute::AlwaysInline:
603     return bitc::ATTR_KIND_ALWAYS_INLINE;
604   case Attribute::ArgMemOnly:
605     return bitc::ATTR_KIND_ARGMEMONLY;
606   case Attribute::Builtin:
607     return bitc::ATTR_KIND_BUILTIN;
608   case Attribute::ByVal:
609     return bitc::ATTR_KIND_BY_VAL;
610   case Attribute::Convergent:
611     return bitc::ATTR_KIND_CONVERGENT;
612   case Attribute::InAlloca:
613     return bitc::ATTR_KIND_IN_ALLOCA;
614   case Attribute::Cold:
615     return bitc::ATTR_KIND_COLD;
616   case Attribute::InaccessibleMemOnly:
617     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
618   case Attribute::InaccessibleMemOrArgMemOnly:
619     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
620   case Attribute::InlineHint:
621     return bitc::ATTR_KIND_INLINE_HINT;
622   case Attribute::InReg:
623     return bitc::ATTR_KIND_IN_REG;
624   case Attribute::JumpTable:
625     return bitc::ATTR_KIND_JUMP_TABLE;
626   case Attribute::MinSize:
627     return bitc::ATTR_KIND_MIN_SIZE;
628   case Attribute::Naked:
629     return bitc::ATTR_KIND_NAKED;
630   case Attribute::Nest:
631     return bitc::ATTR_KIND_NEST;
632   case Attribute::NoAlias:
633     return bitc::ATTR_KIND_NO_ALIAS;
634   case Attribute::NoBuiltin:
635     return bitc::ATTR_KIND_NO_BUILTIN;
636   case Attribute::NoCapture:
637     return bitc::ATTR_KIND_NO_CAPTURE;
638   case Attribute::NoDuplicate:
639     return bitc::ATTR_KIND_NO_DUPLICATE;
640   case Attribute::NoImplicitFloat:
641     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
642   case Attribute::NoInline:
643     return bitc::ATTR_KIND_NO_INLINE;
644   case Attribute::NoRecurse:
645     return bitc::ATTR_KIND_NO_RECURSE;
646   case Attribute::NonLazyBind:
647     return bitc::ATTR_KIND_NON_LAZY_BIND;
648   case Attribute::NonNull:
649     return bitc::ATTR_KIND_NON_NULL;
650   case Attribute::Dereferenceable:
651     return bitc::ATTR_KIND_DEREFERENCEABLE;
652   case Attribute::DereferenceableOrNull:
653     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
654   case Attribute::NoRedZone:
655     return bitc::ATTR_KIND_NO_RED_ZONE;
656   case Attribute::NoReturn:
657     return bitc::ATTR_KIND_NO_RETURN;
658   case Attribute::NoUnwind:
659     return bitc::ATTR_KIND_NO_UNWIND;
660   case Attribute::OptimizeForSize:
661     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
662   case Attribute::OptimizeNone:
663     return bitc::ATTR_KIND_OPTIMIZE_NONE;
664   case Attribute::ReadNone:
665     return bitc::ATTR_KIND_READ_NONE;
666   case Attribute::ReadOnly:
667     return bitc::ATTR_KIND_READ_ONLY;
668   case Attribute::Returned:
669     return bitc::ATTR_KIND_RETURNED;
670   case Attribute::ReturnsTwice:
671     return bitc::ATTR_KIND_RETURNS_TWICE;
672   case Attribute::SExt:
673     return bitc::ATTR_KIND_S_EXT;
674   case Attribute::StackAlignment:
675     return bitc::ATTR_KIND_STACK_ALIGNMENT;
676   case Attribute::StackProtect:
677     return bitc::ATTR_KIND_STACK_PROTECT;
678   case Attribute::StackProtectReq:
679     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
680   case Attribute::StackProtectStrong:
681     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
682   case Attribute::SafeStack:
683     return bitc::ATTR_KIND_SAFESTACK;
684   case Attribute::StructRet:
685     return bitc::ATTR_KIND_STRUCT_RET;
686   case Attribute::SanitizeAddress:
687     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
688   case Attribute::SanitizeThread:
689     return bitc::ATTR_KIND_SANITIZE_THREAD;
690   case Attribute::SanitizeMemory:
691     return bitc::ATTR_KIND_SANITIZE_MEMORY;
692   case Attribute::SwiftError:
693     return bitc::ATTR_KIND_SWIFT_ERROR;
694   case Attribute::SwiftSelf:
695     return bitc::ATTR_KIND_SWIFT_SELF;
696   case Attribute::UWTable:
697     return bitc::ATTR_KIND_UW_TABLE;
698   case Attribute::WriteOnly:
699     return bitc::ATTR_KIND_WRITEONLY;
700   case Attribute::ZExt:
701     return bitc::ATTR_KIND_Z_EXT;
702   case Attribute::EndAttrKinds:
703     llvm_unreachable("Can not encode end-attribute kinds marker.");
704   case Attribute::None:
705     llvm_unreachable("Can not encode none-attribute.");
706   }
707 
708   llvm_unreachable("Trying to encode unknown attribute");
709 }
710 
711 void ModuleBitcodeWriter::writeAttributeGroupTable() {
712   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
713   if (AttrGrps.empty()) return;
714 
715   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
716 
717   SmallVector<uint64_t, 64> Record;
718   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
719     AttributeSet AS = AttrGrps[i];
720     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
721       AttributeSet A = AS.getSlotAttributes(i);
722 
723       Record.push_back(VE.getAttributeGroupID(A));
724       Record.push_back(AS.getSlotIndex(i));
725 
726       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
727            I != E; ++I) {
728         Attribute Attr = *I;
729         if (Attr.isEnumAttribute()) {
730           Record.push_back(0);
731           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
732         } else if (Attr.isIntAttribute()) {
733           Record.push_back(1);
734           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
735           Record.push_back(Attr.getValueAsInt());
736         } else {
737           StringRef Kind = Attr.getKindAsString();
738           StringRef Val = Attr.getValueAsString();
739 
740           Record.push_back(Val.empty() ? 3 : 4);
741           Record.append(Kind.begin(), Kind.end());
742           Record.push_back(0);
743           if (!Val.empty()) {
744             Record.append(Val.begin(), Val.end());
745             Record.push_back(0);
746           }
747         }
748       }
749 
750       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
751       Record.clear();
752     }
753   }
754 
755   Stream.ExitBlock();
756 }
757 
758 void ModuleBitcodeWriter::writeAttributeTable() {
759   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
760   if (Attrs.empty()) return;
761 
762   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
763 
764   SmallVector<uint64_t, 64> Record;
765   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
766     const AttributeSet &A = Attrs[i];
767     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
768       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
769 
770     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
771     Record.clear();
772   }
773 
774   Stream.ExitBlock();
775 }
776 
777 /// WriteTypeTable - Write out the type table for a module.
778 void ModuleBitcodeWriter::writeTypeTable() {
779   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
780 
781   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
782   SmallVector<uint64_t, 64> TypeVals;
783 
784   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
785 
786   // Abbrev for TYPE_CODE_POINTER.
787   auto Abbv = std::make_shared<BitCodeAbbrev>();
788   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
789   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
790   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
791   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
792 
793   // Abbrev for TYPE_CODE_FUNCTION.
794   Abbv = std::make_shared<BitCodeAbbrev>();
795   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
796   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
797   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
798   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
799 
800   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
801 
802   // Abbrev for TYPE_CODE_STRUCT_ANON.
803   Abbv = std::make_shared<BitCodeAbbrev>();
804   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
805   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
806   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
807   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
808 
809   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
810 
811   // Abbrev for TYPE_CODE_STRUCT_NAME.
812   Abbv = std::make_shared<BitCodeAbbrev>();
813   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
814   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
815   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
816   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
817 
818   // Abbrev for TYPE_CODE_STRUCT_NAMED.
819   Abbv = std::make_shared<BitCodeAbbrev>();
820   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
822   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
823   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
824 
825   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
826 
827   // Abbrev for TYPE_CODE_ARRAY.
828   Abbv = std::make_shared<BitCodeAbbrev>();
829   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
830   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
831   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
832 
833   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
834 
835   // Emit an entry count so the reader can reserve space.
836   TypeVals.push_back(TypeList.size());
837   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
838   TypeVals.clear();
839 
840   // Loop over all of the types, emitting each in turn.
841   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
842     Type *T = TypeList[i];
843     int AbbrevToUse = 0;
844     unsigned Code = 0;
845 
846     switch (T->getTypeID()) {
847     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
848     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
849     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
850     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
851     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
852     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
853     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
854     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
855     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
856     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
857     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
858     case Type::IntegerTyID:
859       // INTEGER: [width]
860       Code = bitc::TYPE_CODE_INTEGER;
861       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
862       break;
863     case Type::PointerTyID: {
864       PointerType *PTy = cast<PointerType>(T);
865       // POINTER: [pointee type, address space]
866       Code = bitc::TYPE_CODE_POINTER;
867       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
868       unsigned AddressSpace = PTy->getAddressSpace();
869       TypeVals.push_back(AddressSpace);
870       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
871       break;
872     }
873     case Type::FunctionTyID: {
874       FunctionType *FT = cast<FunctionType>(T);
875       // FUNCTION: [isvararg, retty, paramty x N]
876       Code = bitc::TYPE_CODE_FUNCTION;
877       TypeVals.push_back(FT->isVarArg());
878       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
879       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
880         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
881       AbbrevToUse = FunctionAbbrev;
882       break;
883     }
884     case Type::StructTyID: {
885       StructType *ST = cast<StructType>(T);
886       // STRUCT: [ispacked, eltty x N]
887       TypeVals.push_back(ST->isPacked());
888       // Output all of the element types.
889       for (StructType::element_iterator I = ST->element_begin(),
890            E = ST->element_end(); I != E; ++I)
891         TypeVals.push_back(VE.getTypeID(*I));
892 
893       if (ST->isLiteral()) {
894         Code = bitc::TYPE_CODE_STRUCT_ANON;
895         AbbrevToUse = StructAnonAbbrev;
896       } else {
897         if (ST->isOpaque()) {
898           Code = bitc::TYPE_CODE_OPAQUE;
899         } else {
900           Code = bitc::TYPE_CODE_STRUCT_NAMED;
901           AbbrevToUse = StructNamedAbbrev;
902         }
903 
904         // Emit the name if it is present.
905         if (!ST->getName().empty())
906           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
907                             StructNameAbbrev);
908       }
909       break;
910     }
911     case Type::ArrayTyID: {
912       ArrayType *AT = cast<ArrayType>(T);
913       // ARRAY: [numelts, eltty]
914       Code = bitc::TYPE_CODE_ARRAY;
915       TypeVals.push_back(AT->getNumElements());
916       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
917       AbbrevToUse = ArrayAbbrev;
918       break;
919     }
920     case Type::VectorTyID: {
921       VectorType *VT = cast<VectorType>(T);
922       // VECTOR [numelts, eltty]
923       Code = bitc::TYPE_CODE_VECTOR;
924       TypeVals.push_back(VT->getNumElements());
925       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
926       break;
927     }
928     }
929 
930     // Emit the finished record.
931     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
932     TypeVals.clear();
933   }
934 
935   Stream.ExitBlock();
936 }
937 
938 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
939   switch (Linkage) {
940   case GlobalValue::ExternalLinkage:
941     return 0;
942   case GlobalValue::WeakAnyLinkage:
943     return 16;
944   case GlobalValue::AppendingLinkage:
945     return 2;
946   case GlobalValue::InternalLinkage:
947     return 3;
948   case GlobalValue::LinkOnceAnyLinkage:
949     return 18;
950   case GlobalValue::ExternalWeakLinkage:
951     return 7;
952   case GlobalValue::CommonLinkage:
953     return 8;
954   case GlobalValue::PrivateLinkage:
955     return 9;
956   case GlobalValue::WeakODRLinkage:
957     return 17;
958   case GlobalValue::LinkOnceODRLinkage:
959     return 19;
960   case GlobalValue::AvailableExternallyLinkage:
961     return 12;
962   }
963   llvm_unreachable("Invalid linkage");
964 }
965 
966 static unsigned getEncodedLinkage(const GlobalValue &GV) {
967   return getEncodedLinkage(GV.getLinkage());
968 }
969 
970 // Decode the flags for GlobalValue in the summary
971 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
972   uint64_t RawFlags = 0;
973 
974   RawFlags |= Flags.NotEligibleToImport; // bool
975   RawFlags |= (Flags.LiveRoot << 1);
976   // Linkage don't need to be remapped at that time for the summary. Any future
977   // change to the getEncodedLinkage() function will need to be taken into
978   // account here as well.
979   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
980 
981   return RawFlags;
982 }
983 
984 static unsigned getEncodedVisibility(const GlobalValue &GV) {
985   switch (GV.getVisibility()) {
986   case GlobalValue::DefaultVisibility:   return 0;
987   case GlobalValue::HiddenVisibility:    return 1;
988   case GlobalValue::ProtectedVisibility: return 2;
989   }
990   llvm_unreachable("Invalid visibility");
991 }
992 
993 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
994   switch (GV.getDLLStorageClass()) {
995   case GlobalValue::DefaultStorageClass:   return 0;
996   case GlobalValue::DLLImportStorageClass: return 1;
997   case GlobalValue::DLLExportStorageClass: return 2;
998   }
999   llvm_unreachable("Invalid DLL storage class");
1000 }
1001 
1002 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1003   switch (GV.getThreadLocalMode()) {
1004     case GlobalVariable::NotThreadLocal:         return 0;
1005     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1006     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1007     case GlobalVariable::InitialExecTLSModel:    return 3;
1008     case GlobalVariable::LocalExecTLSModel:      return 4;
1009   }
1010   llvm_unreachable("Invalid TLS model");
1011 }
1012 
1013 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1014   switch (C.getSelectionKind()) {
1015   case Comdat::Any:
1016     return bitc::COMDAT_SELECTION_KIND_ANY;
1017   case Comdat::ExactMatch:
1018     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1019   case Comdat::Largest:
1020     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1021   case Comdat::NoDuplicates:
1022     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1023   case Comdat::SameSize:
1024     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1025   }
1026   llvm_unreachable("Invalid selection kind");
1027 }
1028 
1029 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1030   switch (GV.getUnnamedAddr()) {
1031   case GlobalValue::UnnamedAddr::None:   return 0;
1032   case GlobalValue::UnnamedAddr::Local:  return 2;
1033   case GlobalValue::UnnamedAddr::Global: return 1;
1034   }
1035   llvm_unreachable("Invalid unnamed_addr");
1036 }
1037 
1038 void ModuleBitcodeWriter::writeComdats() {
1039   SmallVector<unsigned, 64> Vals;
1040   for (const Comdat *C : VE.getComdats()) {
1041     // COMDAT: [selection_kind, name]
1042     Vals.push_back(getEncodedComdatSelectionKind(*C));
1043     size_t Size = C->getName().size();
1044     assert(isUInt<32>(Size));
1045     Vals.push_back(Size);
1046     for (char Chr : C->getName())
1047       Vals.push_back((unsigned char)Chr);
1048     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1049     Vals.clear();
1050   }
1051 }
1052 
1053 /// Write a record that will eventually hold the word offset of the
1054 /// module-level VST. For now the offset is 0, which will be backpatched
1055 /// after the real VST is written. Saves the bit offset to backpatch.
1056 void BitcodeWriterBase::writeValueSymbolTableForwardDecl() {
1057   // Write a placeholder value in for the offset of the real VST,
1058   // which is written after the function blocks so that it can include
1059   // the offset of each function. The placeholder offset will be
1060   // updated when the real VST is written.
1061   auto Abbv = std::make_shared<BitCodeAbbrev>();
1062   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1063   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1064   // hold the real VST offset. Must use fixed instead of VBR as we don't
1065   // know how many VBR chunks to reserve ahead of time.
1066   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1067   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1068 
1069   // Emit the placeholder
1070   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1071   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1072 
1073   // Compute and save the bit offset to the placeholder, which will be
1074   // patched when the real VST is written. We can simply subtract the 32-bit
1075   // fixed size from the current bit number to get the location to backpatch.
1076   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1077 }
1078 
1079 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1080 
1081 /// Determine the encoding to use for the given string name and length.
1082 static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
1083   bool isChar6 = true;
1084   for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
1085     if (isChar6)
1086       isChar6 = BitCodeAbbrevOp::isChar6(*C);
1087     if ((unsigned char)*C & 128)
1088       // don't bother scanning the rest.
1089       return SE_Fixed8;
1090   }
1091   if (isChar6)
1092     return SE_Char6;
1093   else
1094     return SE_Fixed7;
1095 }
1096 
1097 /// Emit top-level description of module, including target triple, inline asm,
1098 /// descriptors for global variables, and function prototype info.
1099 /// Returns the bit offset to backpatch with the location of the real VST.
1100 void ModuleBitcodeWriter::writeModuleInfo() {
1101   // Emit various pieces of data attached to a module.
1102   if (!M.getTargetTriple().empty())
1103     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1104                       0 /*TODO*/);
1105   const std::string &DL = M.getDataLayoutStr();
1106   if (!DL.empty())
1107     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1108   if (!M.getModuleInlineAsm().empty())
1109     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1110                       0 /*TODO*/);
1111 
1112   // Emit information about sections and GC, computing how many there are. Also
1113   // compute the maximum alignment value.
1114   std::map<std::string, unsigned> SectionMap;
1115   std::map<std::string, unsigned> GCMap;
1116   unsigned MaxAlignment = 0;
1117   unsigned MaxGlobalType = 0;
1118   for (const GlobalValue &GV : M.globals()) {
1119     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1120     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1121     if (GV.hasSection()) {
1122       // Give section names unique ID's.
1123       unsigned &Entry = SectionMap[GV.getSection()];
1124       if (!Entry) {
1125         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1126                           0 /*TODO*/);
1127         Entry = SectionMap.size();
1128       }
1129     }
1130   }
1131   for (const Function &F : M) {
1132     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1133     if (F.hasSection()) {
1134       // Give section names unique ID's.
1135       unsigned &Entry = SectionMap[F.getSection()];
1136       if (!Entry) {
1137         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1138                           0 /*TODO*/);
1139         Entry = SectionMap.size();
1140       }
1141     }
1142     if (F.hasGC()) {
1143       // Same for GC names.
1144       unsigned &Entry = GCMap[F.getGC()];
1145       if (!Entry) {
1146         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1147                           0 /*TODO*/);
1148         Entry = GCMap.size();
1149       }
1150     }
1151   }
1152 
1153   // Emit abbrev for globals, now that we know # sections and max alignment.
1154   unsigned SimpleGVarAbbrev = 0;
1155   if (!M.global_empty()) {
1156     // Add an abbrev for common globals with no visibility or thread localness.
1157     auto Abbv = std::make_shared<BitCodeAbbrev>();
1158     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1159     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1160                               Log2_32_Ceil(MaxGlobalType+1)));
1161     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1162                                                            //| explicitType << 1
1163                                                            //| constant
1164     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1165     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1166     if (MaxAlignment == 0)                                 // Alignment.
1167       Abbv->Add(BitCodeAbbrevOp(0));
1168     else {
1169       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1170       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1171                                Log2_32_Ceil(MaxEncAlignment+1)));
1172     }
1173     if (SectionMap.empty())                                    // Section.
1174       Abbv->Add(BitCodeAbbrevOp(0));
1175     else
1176       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1177                                Log2_32_Ceil(SectionMap.size()+1)));
1178     // Don't bother emitting vis + thread local.
1179     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1180   }
1181 
1182   // Emit the global variable information.
1183   SmallVector<unsigned, 64> Vals;
1184   for (const GlobalVariable &GV : M.globals()) {
1185     unsigned AbbrevToUse = 0;
1186 
1187     // GLOBALVAR: [type, isconst, initid,
1188     //             linkage, alignment, section, visibility, threadlocal,
1189     //             unnamed_addr, externally_initialized, dllstorageclass,
1190     //             comdat]
1191     Vals.push_back(VE.getTypeID(GV.getValueType()));
1192     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1193     Vals.push_back(GV.isDeclaration() ? 0 :
1194                    (VE.getValueID(GV.getInitializer()) + 1));
1195     Vals.push_back(getEncodedLinkage(GV));
1196     Vals.push_back(Log2_32(GV.getAlignment())+1);
1197     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1198     if (GV.isThreadLocal() ||
1199         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1200         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1201         GV.isExternallyInitialized() ||
1202         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1203         GV.hasComdat()) {
1204       Vals.push_back(getEncodedVisibility(GV));
1205       Vals.push_back(getEncodedThreadLocalMode(GV));
1206       Vals.push_back(getEncodedUnnamedAddr(GV));
1207       Vals.push_back(GV.isExternallyInitialized());
1208       Vals.push_back(getEncodedDLLStorageClass(GV));
1209       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1210     } else {
1211       AbbrevToUse = SimpleGVarAbbrev;
1212     }
1213 
1214     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1215     Vals.clear();
1216   }
1217 
1218   // Emit the function proto information.
1219   for (const Function &F : M) {
1220     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
1221     //             section, visibility, gc, unnamed_addr, prologuedata,
1222     //             dllstorageclass, comdat, prefixdata, personalityfn]
1223     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1224     Vals.push_back(F.getCallingConv());
1225     Vals.push_back(F.isDeclaration());
1226     Vals.push_back(getEncodedLinkage(F));
1227     Vals.push_back(VE.getAttributeID(F.getAttributes()));
1228     Vals.push_back(Log2_32(F.getAlignment())+1);
1229     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1230     Vals.push_back(getEncodedVisibility(F));
1231     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1232     Vals.push_back(getEncodedUnnamedAddr(F));
1233     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1234                                        : 0);
1235     Vals.push_back(getEncodedDLLStorageClass(F));
1236     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1237     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1238                                      : 0);
1239     Vals.push_back(
1240         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1241 
1242     unsigned AbbrevToUse = 0;
1243     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1244     Vals.clear();
1245   }
1246 
1247   // Emit the alias information.
1248   for (const GlobalAlias &A : M.aliases()) {
1249     // ALIAS: [alias type, aliasee val#, linkage, visibility, dllstorageclass,
1250     //         threadlocal, unnamed_addr]
1251     Vals.push_back(VE.getTypeID(A.getValueType()));
1252     Vals.push_back(A.getType()->getAddressSpace());
1253     Vals.push_back(VE.getValueID(A.getAliasee()));
1254     Vals.push_back(getEncodedLinkage(A));
1255     Vals.push_back(getEncodedVisibility(A));
1256     Vals.push_back(getEncodedDLLStorageClass(A));
1257     Vals.push_back(getEncodedThreadLocalMode(A));
1258     Vals.push_back(getEncodedUnnamedAddr(A));
1259     unsigned AbbrevToUse = 0;
1260     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1261     Vals.clear();
1262   }
1263 
1264   // Emit the ifunc information.
1265   for (const GlobalIFunc &I : M.ifuncs()) {
1266     // IFUNC: [ifunc type, address space, resolver val#, linkage, visibility]
1267     Vals.push_back(VE.getTypeID(I.getValueType()));
1268     Vals.push_back(I.getType()->getAddressSpace());
1269     Vals.push_back(VE.getValueID(I.getResolver()));
1270     Vals.push_back(getEncodedLinkage(I));
1271     Vals.push_back(getEncodedVisibility(I));
1272     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1273     Vals.clear();
1274   }
1275 
1276   // Emit the module's source file name.
1277   {
1278     StringEncoding Bits = getStringEncoding(M.getSourceFileName().data(),
1279                                             M.getSourceFileName().size());
1280     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1281     if (Bits == SE_Char6)
1282       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1283     else if (Bits == SE_Fixed7)
1284       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1285 
1286     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1287     auto Abbv = std::make_shared<BitCodeAbbrev>();
1288     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1289     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1290     Abbv->Add(AbbrevOpToUse);
1291     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1292 
1293     for (const auto P : M.getSourceFileName())
1294       Vals.push_back((unsigned char)P);
1295 
1296     // Emit the finished record.
1297     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1298     Vals.clear();
1299   }
1300 
1301   // If we have a VST, write the VSTOFFSET record placeholder.
1302   if (M.getValueSymbolTable().empty())
1303     return;
1304   writeValueSymbolTableForwardDecl();
1305 }
1306 
1307 static uint64_t getOptimizationFlags(const Value *V) {
1308   uint64_t Flags = 0;
1309 
1310   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1311     if (OBO->hasNoSignedWrap())
1312       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1313     if (OBO->hasNoUnsignedWrap())
1314       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1315   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1316     if (PEO->isExact())
1317       Flags |= 1 << bitc::PEO_EXACT;
1318   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1319     if (FPMO->hasUnsafeAlgebra())
1320       Flags |= FastMathFlags::UnsafeAlgebra;
1321     if (FPMO->hasNoNaNs())
1322       Flags |= FastMathFlags::NoNaNs;
1323     if (FPMO->hasNoInfs())
1324       Flags |= FastMathFlags::NoInfs;
1325     if (FPMO->hasNoSignedZeros())
1326       Flags |= FastMathFlags::NoSignedZeros;
1327     if (FPMO->hasAllowReciprocal())
1328       Flags |= FastMathFlags::AllowReciprocal;
1329   }
1330 
1331   return Flags;
1332 }
1333 
1334 void ModuleBitcodeWriter::writeValueAsMetadata(
1335     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1336   // Mimic an MDNode with a value as one operand.
1337   Value *V = MD->getValue();
1338   Record.push_back(VE.getTypeID(V->getType()));
1339   Record.push_back(VE.getValueID(V));
1340   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1341   Record.clear();
1342 }
1343 
1344 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1345                                        SmallVectorImpl<uint64_t> &Record,
1346                                        unsigned Abbrev) {
1347   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1348     Metadata *MD = N->getOperand(i);
1349     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1350            "Unexpected function-local metadata");
1351     Record.push_back(VE.getMetadataOrNullID(MD));
1352   }
1353   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1354                                     : bitc::METADATA_NODE,
1355                     Record, Abbrev);
1356   Record.clear();
1357 }
1358 
1359 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1360   // Assume the column is usually under 128, and always output the inlined-at
1361   // location (it's never more expensive than building an array size 1).
1362   auto Abbv = std::make_shared<BitCodeAbbrev>();
1363   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1365   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1366   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1367   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1368   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1369   return Stream.EmitAbbrev(std::move(Abbv));
1370 }
1371 
1372 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1373                                           SmallVectorImpl<uint64_t> &Record,
1374                                           unsigned &Abbrev) {
1375   if (!Abbrev)
1376     Abbrev = createDILocationAbbrev();
1377 
1378   Record.push_back(N->isDistinct());
1379   Record.push_back(N->getLine());
1380   Record.push_back(N->getColumn());
1381   Record.push_back(VE.getMetadataID(N->getScope()));
1382   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1383 
1384   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1385   Record.clear();
1386 }
1387 
1388 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1389   // Assume the column is usually under 128, and always output the inlined-at
1390   // location (it's never more expensive than building an array size 1).
1391   auto Abbv = std::make_shared<BitCodeAbbrev>();
1392   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1393   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1394   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1395   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1396   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1399   return Stream.EmitAbbrev(std::move(Abbv));
1400 }
1401 
1402 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1403                                              SmallVectorImpl<uint64_t> &Record,
1404                                              unsigned &Abbrev) {
1405   if (!Abbrev)
1406     Abbrev = createGenericDINodeAbbrev();
1407 
1408   Record.push_back(N->isDistinct());
1409   Record.push_back(N->getTag());
1410   Record.push_back(0); // Per-tag version field; unused for now.
1411 
1412   for (auto &I : N->operands())
1413     Record.push_back(VE.getMetadataOrNullID(I));
1414 
1415   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1416   Record.clear();
1417 }
1418 
1419 static uint64_t rotateSign(int64_t I) {
1420   uint64_t U = I;
1421   return I < 0 ? ~(U << 1) : U << 1;
1422 }
1423 
1424 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1425                                           SmallVectorImpl<uint64_t> &Record,
1426                                           unsigned Abbrev) {
1427   Record.push_back(N->isDistinct());
1428   Record.push_back(N->getCount());
1429   Record.push_back(rotateSign(N->getLowerBound()));
1430 
1431   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1432   Record.clear();
1433 }
1434 
1435 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1436                                             SmallVectorImpl<uint64_t> &Record,
1437                                             unsigned Abbrev) {
1438   Record.push_back(N->isDistinct());
1439   Record.push_back(rotateSign(N->getValue()));
1440   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1441 
1442   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1443   Record.clear();
1444 }
1445 
1446 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1447                                            SmallVectorImpl<uint64_t> &Record,
1448                                            unsigned Abbrev) {
1449   Record.push_back(N->isDistinct());
1450   Record.push_back(N->getTag());
1451   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1452   Record.push_back(N->getSizeInBits());
1453   Record.push_back(N->getAlignInBits());
1454   Record.push_back(N->getEncoding());
1455 
1456   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1457   Record.clear();
1458 }
1459 
1460 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1461                                              SmallVectorImpl<uint64_t> &Record,
1462                                              unsigned Abbrev) {
1463   Record.push_back(N->isDistinct());
1464   Record.push_back(N->getTag());
1465   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1466   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1467   Record.push_back(N->getLine());
1468   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1469   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1470   Record.push_back(N->getSizeInBits());
1471   Record.push_back(N->getAlignInBits());
1472   Record.push_back(N->getOffsetInBits());
1473   Record.push_back(N->getFlags());
1474   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1475 
1476   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1477   // that there is no DWARF address space associated with DIDerivedType.
1478   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1479     Record.push_back(*DWARFAddressSpace + 1);
1480   else
1481     Record.push_back(0);
1482 
1483   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1484   Record.clear();
1485 }
1486 
1487 void ModuleBitcodeWriter::writeDICompositeType(
1488     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1489     unsigned Abbrev) {
1490   const unsigned IsNotUsedInOldTypeRef = 0x2;
1491   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1492   Record.push_back(N->getTag());
1493   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1494   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1495   Record.push_back(N->getLine());
1496   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1497   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1498   Record.push_back(N->getSizeInBits());
1499   Record.push_back(N->getAlignInBits());
1500   Record.push_back(N->getOffsetInBits());
1501   Record.push_back(N->getFlags());
1502   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1503   Record.push_back(N->getRuntimeLang());
1504   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1505   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1506   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1507 
1508   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1509   Record.clear();
1510 }
1511 
1512 void ModuleBitcodeWriter::writeDISubroutineType(
1513     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1514     unsigned Abbrev) {
1515   const unsigned HasNoOldTypeRefs = 0x2;
1516   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1517   Record.push_back(N->getFlags());
1518   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1519   Record.push_back(N->getCC());
1520 
1521   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1522   Record.clear();
1523 }
1524 
1525 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1526                                       SmallVectorImpl<uint64_t> &Record,
1527                                       unsigned Abbrev) {
1528   Record.push_back(N->isDistinct());
1529   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1530   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1531   Record.push_back(N->getChecksumKind());
1532   Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()));
1533 
1534   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1535   Record.clear();
1536 }
1537 
1538 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1539                                              SmallVectorImpl<uint64_t> &Record,
1540                                              unsigned Abbrev) {
1541   assert(N->isDistinct() && "Expected distinct compile units");
1542   Record.push_back(/* IsDistinct */ true);
1543   Record.push_back(N->getSourceLanguage());
1544   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1545   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1546   Record.push_back(N->isOptimized());
1547   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1548   Record.push_back(N->getRuntimeVersion());
1549   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1550   Record.push_back(N->getEmissionKind());
1551   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1552   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1553   Record.push_back(/* subprograms */ 0);
1554   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1555   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1556   Record.push_back(N->getDWOId());
1557   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1558   Record.push_back(N->getSplitDebugInlining());
1559   Record.push_back(N->getDebugInfoForProfiling());
1560 
1561   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1562   Record.clear();
1563 }
1564 
1565 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1566                                             SmallVectorImpl<uint64_t> &Record,
1567                                             unsigned Abbrev) {
1568   uint64_t HasUnitFlag = 1 << 1;
1569   Record.push_back(N->isDistinct() | HasUnitFlag);
1570   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1571   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1572   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1573   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1574   Record.push_back(N->getLine());
1575   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1576   Record.push_back(N->isLocalToUnit());
1577   Record.push_back(N->isDefinition());
1578   Record.push_back(N->getScopeLine());
1579   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1580   Record.push_back(N->getVirtuality());
1581   Record.push_back(N->getVirtualIndex());
1582   Record.push_back(N->getFlags());
1583   Record.push_back(N->isOptimized());
1584   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1585   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1586   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1587   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1588   Record.push_back(N->getThisAdjustment());
1589 
1590   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1591   Record.clear();
1592 }
1593 
1594 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1595                                               SmallVectorImpl<uint64_t> &Record,
1596                                               unsigned Abbrev) {
1597   Record.push_back(N->isDistinct());
1598   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1599   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1600   Record.push_back(N->getLine());
1601   Record.push_back(N->getColumn());
1602 
1603   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1604   Record.clear();
1605 }
1606 
1607 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1608     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1609     unsigned Abbrev) {
1610   Record.push_back(N->isDistinct());
1611   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1612   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1613   Record.push_back(N->getDiscriminator());
1614 
1615   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1616   Record.clear();
1617 }
1618 
1619 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1620                                            SmallVectorImpl<uint64_t> &Record,
1621                                            unsigned Abbrev) {
1622   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1623   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1624   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1625   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1626   Record.push_back(N->getLine());
1627 
1628   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1629   Record.clear();
1630 }
1631 
1632 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1633                                        SmallVectorImpl<uint64_t> &Record,
1634                                        unsigned Abbrev) {
1635   Record.push_back(N->isDistinct());
1636   Record.push_back(N->getMacinfoType());
1637   Record.push_back(N->getLine());
1638   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1639   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1640 
1641   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1642   Record.clear();
1643 }
1644 
1645 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1646                                            SmallVectorImpl<uint64_t> &Record,
1647                                            unsigned Abbrev) {
1648   Record.push_back(N->isDistinct());
1649   Record.push_back(N->getMacinfoType());
1650   Record.push_back(N->getLine());
1651   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1652   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1653 
1654   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1655   Record.clear();
1656 }
1657 
1658 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1659                                         SmallVectorImpl<uint64_t> &Record,
1660                                         unsigned Abbrev) {
1661   Record.push_back(N->isDistinct());
1662   for (auto &I : N->operands())
1663     Record.push_back(VE.getMetadataOrNullID(I));
1664 
1665   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1666   Record.clear();
1667 }
1668 
1669 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1670     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1671     unsigned Abbrev) {
1672   Record.push_back(N->isDistinct());
1673   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1674   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1675 
1676   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1677   Record.clear();
1678 }
1679 
1680 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1681     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1682     unsigned Abbrev) {
1683   Record.push_back(N->isDistinct());
1684   Record.push_back(N->getTag());
1685   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1686   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1687   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1688 
1689   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1690   Record.clear();
1691 }
1692 
1693 void ModuleBitcodeWriter::writeDIGlobalVariable(
1694     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1695     unsigned Abbrev) {
1696   const uint64_t Version = 1 << 1;
1697   Record.push_back((uint64_t)N->isDistinct() | Version);
1698   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1699   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1700   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1701   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1702   Record.push_back(N->getLine());
1703   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1704   Record.push_back(N->isLocalToUnit());
1705   Record.push_back(N->isDefinition());
1706   Record.push_back(/* expr */ 0);
1707   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1708   Record.push_back(N->getAlignInBits());
1709 
1710   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1711   Record.clear();
1712 }
1713 
1714 void ModuleBitcodeWriter::writeDILocalVariable(
1715     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1716     unsigned Abbrev) {
1717   // In order to support all possible bitcode formats in BitcodeReader we need
1718   // to distinguish the following cases:
1719   // 1) Record has no artificial tag (Record[1]),
1720   //   has no obsolete inlinedAt field (Record[9]).
1721   //   In this case Record size will be 8, HasAlignment flag is false.
1722   // 2) Record has artificial tag (Record[1]),
1723   //   has no obsolete inlignedAt field (Record[9]).
1724   //   In this case Record size will be 9, HasAlignment flag is false.
1725   // 3) Record has both artificial tag (Record[1]) and
1726   //   obsolete inlignedAt field (Record[9]).
1727   //   In this case Record size will be 10, HasAlignment flag is false.
1728   // 4) Record has neither artificial tag, nor inlignedAt field, but
1729   //   HasAlignment flag is true and Record[8] contains alignment value.
1730   const uint64_t HasAlignmentFlag = 1 << 1;
1731   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1732   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1733   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1734   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1735   Record.push_back(N->getLine());
1736   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1737   Record.push_back(N->getArg());
1738   Record.push_back(N->getFlags());
1739   Record.push_back(N->getAlignInBits());
1740 
1741   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1742   Record.clear();
1743 }
1744 
1745 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1746                                             SmallVectorImpl<uint64_t> &Record,
1747                                             unsigned Abbrev) {
1748   Record.reserve(N->getElements().size() + 1);
1749 
1750   const uint64_t HasOpFragmentFlag = 1 << 1;
1751   Record.push_back((uint64_t)N->isDistinct() | HasOpFragmentFlag);
1752   Record.append(N->elements_begin(), N->elements_end());
1753 
1754   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1755   Record.clear();
1756 }
1757 
1758 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1759     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1760     unsigned Abbrev) {
1761   Record.push_back(N->isDistinct());
1762   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1763   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1764 
1765   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1766   Record.clear();
1767 }
1768 
1769 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1770                                               SmallVectorImpl<uint64_t> &Record,
1771                                               unsigned Abbrev) {
1772   Record.push_back(N->isDistinct());
1773   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1774   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1775   Record.push_back(N->getLine());
1776   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1777   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1778   Record.push_back(N->getAttributes());
1779   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1780 
1781   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1782   Record.clear();
1783 }
1784 
1785 void ModuleBitcodeWriter::writeDIImportedEntity(
1786     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1787     unsigned Abbrev) {
1788   Record.push_back(N->isDistinct());
1789   Record.push_back(N->getTag());
1790   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1791   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1792   Record.push_back(N->getLine());
1793   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1794 
1795   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1796   Record.clear();
1797 }
1798 
1799 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1800   auto Abbv = std::make_shared<BitCodeAbbrev>();
1801   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1802   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1803   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1804   return Stream.EmitAbbrev(std::move(Abbv));
1805 }
1806 
1807 void ModuleBitcodeWriter::writeNamedMetadata(
1808     SmallVectorImpl<uint64_t> &Record) {
1809   if (M.named_metadata_empty())
1810     return;
1811 
1812   unsigned Abbrev = createNamedMetadataAbbrev();
1813   for (const NamedMDNode &NMD : M.named_metadata()) {
1814     // Write name.
1815     StringRef Str = NMD.getName();
1816     Record.append(Str.bytes_begin(), Str.bytes_end());
1817     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1818     Record.clear();
1819 
1820     // Write named metadata operands.
1821     for (const MDNode *N : NMD.operands())
1822       Record.push_back(VE.getMetadataID(N));
1823     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1824     Record.clear();
1825   }
1826 }
1827 
1828 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1829   auto Abbv = std::make_shared<BitCodeAbbrev>();
1830   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1831   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1832   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1833   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1834   return Stream.EmitAbbrev(std::move(Abbv));
1835 }
1836 
1837 /// Write out a record for MDString.
1838 ///
1839 /// All the metadata strings in a metadata block are emitted in a single
1840 /// record.  The sizes and strings themselves are shoved into a blob.
1841 void ModuleBitcodeWriter::writeMetadataStrings(
1842     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1843   if (Strings.empty())
1844     return;
1845 
1846   // Start the record with the number of strings.
1847   Record.push_back(bitc::METADATA_STRINGS);
1848   Record.push_back(Strings.size());
1849 
1850   // Emit the sizes of the strings in the blob.
1851   SmallString<256> Blob;
1852   {
1853     BitstreamWriter W(Blob);
1854     for (const Metadata *MD : Strings)
1855       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1856     W.FlushToWord();
1857   }
1858 
1859   // Add the offset to the strings to the record.
1860   Record.push_back(Blob.size());
1861 
1862   // Add the strings to the blob.
1863   for (const Metadata *MD : Strings)
1864     Blob.append(cast<MDString>(MD)->getString());
1865 
1866   // Emit the final record.
1867   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1868   Record.clear();
1869 }
1870 
1871 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1872 enum MetadataAbbrev : unsigned {
1873 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1874 #include "llvm/IR/Metadata.def"
1875   LastPlusOne
1876 };
1877 
1878 void ModuleBitcodeWriter::writeMetadataRecords(
1879     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1880     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1881   if (MDs.empty())
1882     return;
1883 
1884   // Initialize MDNode abbreviations.
1885 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1886 #include "llvm/IR/Metadata.def"
1887 
1888   for (const Metadata *MD : MDs) {
1889     if (IndexPos)
1890       IndexPos->push_back(Stream.GetCurrentBitNo());
1891     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1892       assert(N->isResolved() && "Expected forward references to be resolved");
1893 
1894       switch (N->getMetadataID()) {
1895       default:
1896         llvm_unreachable("Invalid MDNode subclass");
1897 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1898   case Metadata::CLASS##Kind:                                                  \
1899     if (MDAbbrevs)                                                             \
1900       write##CLASS(cast<CLASS>(N), Record,                                     \
1901                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1902     else                                                                       \
1903       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1904     continue;
1905 #include "llvm/IR/Metadata.def"
1906       }
1907     }
1908     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1909   }
1910 }
1911 
1912 void ModuleBitcodeWriter::writeModuleMetadata() {
1913   if (!VE.hasMDs() && M.named_metadata_empty())
1914     return;
1915 
1916   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1917   SmallVector<uint64_t, 64> Record;
1918 
1919   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1920   // block and load any metadata.
1921   std::vector<unsigned> MDAbbrevs;
1922 
1923   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1924   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1925   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1926       createGenericDINodeAbbrev();
1927 
1928   auto Abbv = std::make_shared<BitCodeAbbrev>();
1929   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1932   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1933 
1934   Abbv = std::make_shared<BitCodeAbbrev>();
1935   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1936   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1937   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1938   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1939 
1940   // Emit MDStrings together upfront.
1941   writeMetadataStrings(VE.getMDStrings(), Record);
1942 
1943   // We only emit an index for the metadata record if we have more than a given
1944   // (naive) threshold of metadatas, otherwise it is not worth it.
1945   if (VE.getNonMDStrings().size() > IndexThreshold) {
1946     // Write a placeholder value in for the offset of the metadata index,
1947     // which is written after the records, so that it can include
1948     // the offset of each entry. The placeholder offset will be
1949     // updated after all records are emitted.
1950     uint64_t Vals[] = {0, 0};
1951     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
1952   }
1953 
1954   // Compute and save the bit offset to the current position, which will be
1955   // patched when we emit the index later. We can simply subtract the 64-bit
1956   // fixed size from the current bit number to get the location to backpatch.
1957   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
1958 
1959   // This index will contain the bitpos for each individual record.
1960   std::vector<uint64_t> IndexPos;
1961   IndexPos.reserve(VE.getNonMDStrings().size());
1962 
1963   // Write all the records
1964   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
1965 
1966   if (VE.getNonMDStrings().size() > IndexThreshold) {
1967     // Now that we have emitted all the records we will emit the index. But
1968     // first
1969     // backpatch the forward reference so that the reader can skip the records
1970     // efficiently.
1971     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
1972                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
1973 
1974     // Delta encode the index.
1975     uint64_t PreviousValue = IndexOffsetRecordBitPos;
1976     for (auto &Elt : IndexPos) {
1977       auto EltDelta = Elt - PreviousValue;
1978       PreviousValue = Elt;
1979       Elt = EltDelta;
1980     }
1981     // Emit the index record.
1982     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
1983     IndexPos.clear();
1984   }
1985 
1986   // Write the named metadata now.
1987   writeNamedMetadata(Record);
1988 
1989   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
1990     SmallVector<uint64_t, 4> Record;
1991     Record.push_back(VE.getValueID(&GO));
1992     pushGlobalMetadataAttachment(Record, GO);
1993     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
1994   };
1995   for (const Function &F : M)
1996     if (F.isDeclaration() && F.hasMetadata())
1997       AddDeclAttachedMetadata(F);
1998   // FIXME: Only store metadata for declarations here, and move data for global
1999   // variable definitions to a separate block (PR28134).
2000   for (const GlobalVariable &GV : M.globals())
2001     if (GV.hasMetadata())
2002       AddDeclAttachedMetadata(GV);
2003 
2004   Stream.ExitBlock();
2005 }
2006 
2007 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2008   if (!VE.hasMDs())
2009     return;
2010 
2011   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2012   SmallVector<uint64_t, 64> Record;
2013   writeMetadataStrings(VE.getMDStrings(), Record);
2014   writeMetadataRecords(VE.getNonMDStrings(), Record);
2015   Stream.ExitBlock();
2016 }
2017 
2018 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2019     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2020   // [n x [id, mdnode]]
2021   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2022   GO.getAllMetadata(MDs);
2023   for (const auto &I : MDs) {
2024     Record.push_back(I.first);
2025     Record.push_back(VE.getMetadataID(I.second));
2026   }
2027 }
2028 
2029 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2030   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2031 
2032   SmallVector<uint64_t, 64> Record;
2033 
2034   if (F.hasMetadata()) {
2035     pushGlobalMetadataAttachment(Record, F);
2036     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2037     Record.clear();
2038   }
2039 
2040   // Write metadata attachments
2041   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2042   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2043   for (const BasicBlock &BB : F)
2044     for (const Instruction &I : BB) {
2045       MDs.clear();
2046       I.getAllMetadataOtherThanDebugLoc(MDs);
2047 
2048       // If no metadata, ignore instruction.
2049       if (MDs.empty()) continue;
2050 
2051       Record.push_back(VE.getInstructionID(&I));
2052 
2053       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2054         Record.push_back(MDs[i].first);
2055         Record.push_back(VE.getMetadataID(MDs[i].second));
2056       }
2057       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2058       Record.clear();
2059     }
2060 
2061   Stream.ExitBlock();
2062 }
2063 
2064 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2065   SmallVector<uint64_t, 64> Record;
2066 
2067   // Write metadata kinds
2068   // METADATA_KIND - [n x [id, name]]
2069   SmallVector<StringRef, 8> Names;
2070   M.getMDKindNames(Names);
2071 
2072   if (Names.empty()) return;
2073 
2074   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2075 
2076   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2077     Record.push_back(MDKindID);
2078     StringRef KName = Names[MDKindID];
2079     Record.append(KName.begin(), KName.end());
2080 
2081     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2082     Record.clear();
2083   }
2084 
2085   Stream.ExitBlock();
2086 }
2087 
2088 void ModuleBitcodeWriter::writeOperandBundleTags() {
2089   // Write metadata kinds
2090   //
2091   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2092   //
2093   // OPERAND_BUNDLE_TAG - [strchr x N]
2094 
2095   SmallVector<StringRef, 8> Tags;
2096   M.getOperandBundleTags(Tags);
2097 
2098   if (Tags.empty())
2099     return;
2100 
2101   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2102 
2103   SmallVector<uint64_t, 64> Record;
2104 
2105   for (auto Tag : Tags) {
2106     Record.append(Tag.begin(), Tag.end());
2107 
2108     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2109     Record.clear();
2110   }
2111 
2112   Stream.ExitBlock();
2113 }
2114 
2115 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2116   if ((int64_t)V >= 0)
2117     Vals.push_back(V << 1);
2118   else
2119     Vals.push_back((-V << 1) | 1);
2120 }
2121 
2122 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2123                                          bool isGlobal) {
2124   if (FirstVal == LastVal) return;
2125 
2126   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2127 
2128   unsigned AggregateAbbrev = 0;
2129   unsigned String8Abbrev = 0;
2130   unsigned CString7Abbrev = 0;
2131   unsigned CString6Abbrev = 0;
2132   // If this is a constant pool for the module, emit module-specific abbrevs.
2133   if (isGlobal) {
2134     // Abbrev for CST_CODE_AGGREGATE.
2135     auto Abbv = std::make_shared<BitCodeAbbrev>();
2136     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2137     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2138     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2139     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2140 
2141     // Abbrev for CST_CODE_STRING.
2142     Abbv = std::make_shared<BitCodeAbbrev>();
2143     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2144     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2146     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2147     // Abbrev for CST_CODE_CSTRING.
2148     Abbv = std::make_shared<BitCodeAbbrev>();
2149     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2150     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2151     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2152     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2153     // Abbrev for CST_CODE_CSTRING.
2154     Abbv = std::make_shared<BitCodeAbbrev>();
2155     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2156     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2157     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2158     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2159   }
2160 
2161   SmallVector<uint64_t, 64> Record;
2162 
2163   const ValueEnumerator::ValueList &Vals = VE.getValues();
2164   Type *LastTy = nullptr;
2165   for (unsigned i = FirstVal; i != LastVal; ++i) {
2166     const Value *V = Vals[i].first;
2167     // If we need to switch types, do so now.
2168     if (V->getType() != LastTy) {
2169       LastTy = V->getType();
2170       Record.push_back(VE.getTypeID(LastTy));
2171       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2172                         CONSTANTS_SETTYPE_ABBREV);
2173       Record.clear();
2174     }
2175 
2176     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2177       Record.push_back(unsigned(IA->hasSideEffects()) |
2178                        unsigned(IA->isAlignStack()) << 1 |
2179                        unsigned(IA->getDialect()&1) << 2);
2180 
2181       // Add the asm string.
2182       const std::string &AsmStr = IA->getAsmString();
2183       Record.push_back(AsmStr.size());
2184       Record.append(AsmStr.begin(), AsmStr.end());
2185 
2186       // Add the constraint string.
2187       const std::string &ConstraintStr = IA->getConstraintString();
2188       Record.push_back(ConstraintStr.size());
2189       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2190       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2191       Record.clear();
2192       continue;
2193     }
2194     const Constant *C = cast<Constant>(V);
2195     unsigned Code = -1U;
2196     unsigned AbbrevToUse = 0;
2197     if (C->isNullValue()) {
2198       Code = bitc::CST_CODE_NULL;
2199     } else if (isa<UndefValue>(C)) {
2200       Code = bitc::CST_CODE_UNDEF;
2201     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2202       if (IV->getBitWidth() <= 64) {
2203         uint64_t V = IV->getSExtValue();
2204         emitSignedInt64(Record, V);
2205         Code = bitc::CST_CODE_INTEGER;
2206         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2207       } else {                             // Wide integers, > 64 bits in size.
2208         // We have an arbitrary precision integer value to write whose
2209         // bit width is > 64. However, in canonical unsigned integer
2210         // format it is likely that the high bits are going to be zero.
2211         // So, we only write the number of active words.
2212         unsigned NWords = IV->getValue().getActiveWords();
2213         const uint64_t *RawWords = IV->getValue().getRawData();
2214         for (unsigned i = 0; i != NWords; ++i) {
2215           emitSignedInt64(Record, RawWords[i]);
2216         }
2217         Code = bitc::CST_CODE_WIDE_INTEGER;
2218       }
2219     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2220       Code = bitc::CST_CODE_FLOAT;
2221       Type *Ty = CFP->getType();
2222       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2223         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2224       } else if (Ty->isX86_FP80Ty()) {
2225         // api needed to prevent premature destruction
2226         // bits are not in the same order as a normal i80 APInt, compensate.
2227         APInt api = CFP->getValueAPF().bitcastToAPInt();
2228         const uint64_t *p = api.getRawData();
2229         Record.push_back((p[1] << 48) | (p[0] >> 16));
2230         Record.push_back(p[0] & 0xffffLL);
2231       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2232         APInt api = CFP->getValueAPF().bitcastToAPInt();
2233         const uint64_t *p = api.getRawData();
2234         Record.push_back(p[0]);
2235         Record.push_back(p[1]);
2236       } else {
2237         assert (0 && "Unknown FP type!");
2238       }
2239     } else if (isa<ConstantDataSequential>(C) &&
2240                cast<ConstantDataSequential>(C)->isString()) {
2241       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2242       // Emit constant strings specially.
2243       unsigned NumElts = Str->getNumElements();
2244       // If this is a null-terminated string, use the denser CSTRING encoding.
2245       if (Str->isCString()) {
2246         Code = bitc::CST_CODE_CSTRING;
2247         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2248       } else {
2249         Code = bitc::CST_CODE_STRING;
2250         AbbrevToUse = String8Abbrev;
2251       }
2252       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2253       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2254       for (unsigned i = 0; i != NumElts; ++i) {
2255         unsigned char V = Str->getElementAsInteger(i);
2256         Record.push_back(V);
2257         isCStr7 &= (V & 128) == 0;
2258         if (isCStrChar6)
2259           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2260       }
2261 
2262       if (isCStrChar6)
2263         AbbrevToUse = CString6Abbrev;
2264       else if (isCStr7)
2265         AbbrevToUse = CString7Abbrev;
2266     } else if (const ConstantDataSequential *CDS =
2267                   dyn_cast<ConstantDataSequential>(C)) {
2268       Code = bitc::CST_CODE_DATA;
2269       Type *EltTy = CDS->getType()->getElementType();
2270       if (isa<IntegerType>(EltTy)) {
2271         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2272           Record.push_back(CDS->getElementAsInteger(i));
2273       } else {
2274         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2275           Record.push_back(
2276               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2277       }
2278     } else if (isa<ConstantAggregate>(C)) {
2279       Code = bitc::CST_CODE_AGGREGATE;
2280       for (const Value *Op : C->operands())
2281         Record.push_back(VE.getValueID(Op));
2282       AbbrevToUse = AggregateAbbrev;
2283     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2284       switch (CE->getOpcode()) {
2285       default:
2286         if (Instruction::isCast(CE->getOpcode())) {
2287           Code = bitc::CST_CODE_CE_CAST;
2288           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2289           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2290           Record.push_back(VE.getValueID(C->getOperand(0)));
2291           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2292         } else {
2293           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2294           Code = bitc::CST_CODE_CE_BINOP;
2295           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2296           Record.push_back(VE.getValueID(C->getOperand(0)));
2297           Record.push_back(VE.getValueID(C->getOperand(1)));
2298           uint64_t Flags = getOptimizationFlags(CE);
2299           if (Flags != 0)
2300             Record.push_back(Flags);
2301         }
2302         break;
2303       case Instruction::GetElementPtr: {
2304         Code = bitc::CST_CODE_CE_GEP;
2305         const auto *GO = cast<GEPOperator>(C);
2306         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2307         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2308           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2309           Record.push_back((*Idx << 1) | GO->isInBounds());
2310         } else if (GO->isInBounds())
2311           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2312         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2313           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2314           Record.push_back(VE.getValueID(C->getOperand(i)));
2315         }
2316         break;
2317       }
2318       case Instruction::Select:
2319         Code = bitc::CST_CODE_CE_SELECT;
2320         Record.push_back(VE.getValueID(C->getOperand(0)));
2321         Record.push_back(VE.getValueID(C->getOperand(1)));
2322         Record.push_back(VE.getValueID(C->getOperand(2)));
2323         break;
2324       case Instruction::ExtractElement:
2325         Code = bitc::CST_CODE_CE_EXTRACTELT;
2326         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2327         Record.push_back(VE.getValueID(C->getOperand(0)));
2328         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2329         Record.push_back(VE.getValueID(C->getOperand(1)));
2330         break;
2331       case Instruction::InsertElement:
2332         Code = bitc::CST_CODE_CE_INSERTELT;
2333         Record.push_back(VE.getValueID(C->getOperand(0)));
2334         Record.push_back(VE.getValueID(C->getOperand(1)));
2335         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2336         Record.push_back(VE.getValueID(C->getOperand(2)));
2337         break;
2338       case Instruction::ShuffleVector:
2339         // If the return type and argument types are the same, this is a
2340         // standard shufflevector instruction.  If the types are different,
2341         // then the shuffle is widening or truncating the input vectors, and
2342         // the argument type must also be encoded.
2343         if (C->getType() == C->getOperand(0)->getType()) {
2344           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2345         } else {
2346           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2347           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2348         }
2349         Record.push_back(VE.getValueID(C->getOperand(0)));
2350         Record.push_back(VE.getValueID(C->getOperand(1)));
2351         Record.push_back(VE.getValueID(C->getOperand(2)));
2352         break;
2353       case Instruction::ICmp:
2354       case Instruction::FCmp:
2355         Code = bitc::CST_CODE_CE_CMP;
2356         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2357         Record.push_back(VE.getValueID(C->getOperand(0)));
2358         Record.push_back(VE.getValueID(C->getOperand(1)));
2359         Record.push_back(CE->getPredicate());
2360         break;
2361       }
2362     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2363       Code = bitc::CST_CODE_BLOCKADDRESS;
2364       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2365       Record.push_back(VE.getValueID(BA->getFunction()));
2366       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2367     } else {
2368 #ifndef NDEBUG
2369       C->dump();
2370 #endif
2371       llvm_unreachable("Unknown constant!");
2372     }
2373     Stream.EmitRecord(Code, Record, AbbrevToUse);
2374     Record.clear();
2375   }
2376 
2377   Stream.ExitBlock();
2378 }
2379 
2380 void ModuleBitcodeWriter::writeModuleConstants() {
2381   const ValueEnumerator::ValueList &Vals = VE.getValues();
2382 
2383   // Find the first constant to emit, which is the first non-globalvalue value.
2384   // We know globalvalues have been emitted by WriteModuleInfo.
2385   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2386     if (!isa<GlobalValue>(Vals[i].first)) {
2387       writeConstants(i, Vals.size(), true);
2388       return;
2389     }
2390   }
2391 }
2392 
2393 /// pushValueAndType - The file has to encode both the value and type id for
2394 /// many values, because we need to know what type to create for forward
2395 /// references.  However, most operands are not forward references, so this type
2396 /// field is not needed.
2397 ///
2398 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2399 /// instruction ID, then it is a forward reference, and it also includes the
2400 /// type ID.  The value ID that is written is encoded relative to the InstID.
2401 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2402                                            SmallVectorImpl<unsigned> &Vals) {
2403   unsigned ValID = VE.getValueID(V);
2404   // Make encoding relative to the InstID.
2405   Vals.push_back(InstID - ValID);
2406   if (ValID >= InstID) {
2407     Vals.push_back(VE.getTypeID(V->getType()));
2408     return true;
2409   }
2410   return false;
2411 }
2412 
2413 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2414                                               unsigned InstID) {
2415   SmallVector<unsigned, 64> Record;
2416   LLVMContext &C = CS.getInstruction()->getContext();
2417 
2418   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2419     const auto &Bundle = CS.getOperandBundleAt(i);
2420     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2421 
2422     for (auto &Input : Bundle.Inputs)
2423       pushValueAndType(Input, InstID, Record);
2424 
2425     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2426     Record.clear();
2427   }
2428 }
2429 
2430 /// pushValue - Like pushValueAndType, but where the type of the value is
2431 /// omitted (perhaps it was already encoded in an earlier operand).
2432 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2433                                     SmallVectorImpl<unsigned> &Vals) {
2434   unsigned ValID = VE.getValueID(V);
2435   Vals.push_back(InstID - ValID);
2436 }
2437 
2438 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2439                                           SmallVectorImpl<uint64_t> &Vals) {
2440   unsigned ValID = VE.getValueID(V);
2441   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2442   emitSignedInt64(Vals, diff);
2443 }
2444 
2445 /// WriteInstruction - Emit an instruction to the specified stream.
2446 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2447                                            unsigned InstID,
2448                                            SmallVectorImpl<unsigned> &Vals) {
2449   unsigned Code = 0;
2450   unsigned AbbrevToUse = 0;
2451   VE.setInstructionID(&I);
2452   switch (I.getOpcode()) {
2453   default:
2454     if (Instruction::isCast(I.getOpcode())) {
2455       Code = bitc::FUNC_CODE_INST_CAST;
2456       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2457         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2458       Vals.push_back(VE.getTypeID(I.getType()));
2459       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2460     } else {
2461       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2462       Code = bitc::FUNC_CODE_INST_BINOP;
2463       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2464         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2465       pushValue(I.getOperand(1), InstID, Vals);
2466       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2467       uint64_t Flags = getOptimizationFlags(&I);
2468       if (Flags != 0) {
2469         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2470           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2471         Vals.push_back(Flags);
2472       }
2473     }
2474     break;
2475 
2476   case Instruction::GetElementPtr: {
2477     Code = bitc::FUNC_CODE_INST_GEP;
2478     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2479     auto &GEPInst = cast<GetElementPtrInst>(I);
2480     Vals.push_back(GEPInst.isInBounds());
2481     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2482     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2483       pushValueAndType(I.getOperand(i), InstID, Vals);
2484     break;
2485   }
2486   case Instruction::ExtractValue: {
2487     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2488     pushValueAndType(I.getOperand(0), InstID, Vals);
2489     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2490     Vals.append(EVI->idx_begin(), EVI->idx_end());
2491     break;
2492   }
2493   case Instruction::InsertValue: {
2494     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2495     pushValueAndType(I.getOperand(0), InstID, Vals);
2496     pushValueAndType(I.getOperand(1), InstID, Vals);
2497     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2498     Vals.append(IVI->idx_begin(), IVI->idx_end());
2499     break;
2500   }
2501   case Instruction::Select:
2502     Code = bitc::FUNC_CODE_INST_VSELECT;
2503     pushValueAndType(I.getOperand(1), InstID, Vals);
2504     pushValue(I.getOperand(2), InstID, Vals);
2505     pushValueAndType(I.getOperand(0), InstID, Vals);
2506     break;
2507   case Instruction::ExtractElement:
2508     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2509     pushValueAndType(I.getOperand(0), InstID, Vals);
2510     pushValueAndType(I.getOperand(1), InstID, Vals);
2511     break;
2512   case Instruction::InsertElement:
2513     Code = bitc::FUNC_CODE_INST_INSERTELT;
2514     pushValueAndType(I.getOperand(0), InstID, Vals);
2515     pushValue(I.getOperand(1), InstID, Vals);
2516     pushValueAndType(I.getOperand(2), InstID, Vals);
2517     break;
2518   case Instruction::ShuffleVector:
2519     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2520     pushValueAndType(I.getOperand(0), InstID, Vals);
2521     pushValue(I.getOperand(1), InstID, Vals);
2522     pushValue(I.getOperand(2), InstID, Vals);
2523     break;
2524   case Instruction::ICmp:
2525   case Instruction::FCmp: {
2526     // compare returning Int1Ty or vector of Int1Ty
2527     Code = bitc::FUNC_CODE_INST_CMP2;
2528     pushValueAndType(I.getOperand(0), InstID, Vals);
2529     pushValue(I.getOperand(1), InstID, Vals);
2530     Vals.push_back(cast<CmpInst>(I).getPredicate());
2531     uint64_t Flags = getOptimizationFlags(&I);
2532     if (Flags != 0)
2533       Vals.push_back(Flags);
2534     break;
2535   }
2536 
2537   case Instruction::Ret:
2538     {
2539       Code = bitc::FUNC_CODE_INST_RET;
2540       unsigned NumOperands = I.getNumOperands();
2541       if (NumOperands == 0)
2542         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2543       else if (NumOperands == 1) {
2544         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2545           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2546       } else {
2547         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2548           pushValueAndType(I.getOperand(i), InstID, Vals);
2549       }
2550     }
2551     break;
2552   case Instruction::Br:
2553     {
2554       Code = bitc::FUNC_CODE_INST_BR;
2555       const BranchInst &II = cast<BranchInst>(I);
2556       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2557       if (II.isConditional()) {
2558         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2559         pushValue(II.getCondition(), InstID, Vals);
2560       }
2561     }
2562     break;
2563   case Instruction::Switch:
2564     {
2565       Code = bitc::FUNC_CODE_INST_SWITCH;
2566       const SwitchInst &SI = cast<SwitchInst>(I);
2567       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2568       pushValue(SI.getCondition(), InstID, Vals);
2569       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2570       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
2571         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2572         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2573       }
2574     }
2575     break;
2576   case Instruction::IndirectBr:
2577     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2578     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2579     // Encode the address operand as relative, but not the basic blocks.
2580     pushValue(I.getOperand(0), InstID, Vals);
2581     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2582       Vals.push_back(VE.getValueID(I.getOperand(i)));
2583     break;
2584 
2585   case Instruction::Invoke: {
2586     const InvokeInst *II = cast<InvokeInst>(&I);
2587     const Value *Callee = II->getCalledValue();
2588     FunctionType *FTy = II->getFunctionType();
2589 
2590     if (II->hasOperandBundles())
2591       writeOperandBundles(II, InstID);
2592 
2593     Code = bitc::FUNC_CODE_INST_INVOKE;
2594 
2595     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2596     Vals.push_back(II->getCallingConv() | 1 << 13);
2597     Vals.push_back(VE.getValueID(II->getNormalDest()));
2598     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2599     Vals.push_back(VE.getTypeID(FTy));
2600     pushValueAndType(Callee, InstID, Vals);
2601 
2602     // Emit value #'s for the fixed parameters.
2603     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2604       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2605 
2606     // Emit type/value pairs for varargs params.
2607     if (FTy->isVarArg()) {
2608       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2609            i != e; ++i)
2610         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2611     }
2612     break;
2613   }
2614   case Instruction::Resume:
2615     Code = bitc::FUNC_CODE_INST_RESUME;
2616     pushValueAndType(I.getOperand(0), InstID, Vals);
2617     break;
2618   case Instruction::CleanupRet: {
2619     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2620     const auto &CRI = cast<CleanupReturnInst>(I);
2621     pushValue(CRI.getCleanupPad(), InstID, Vals);
2622     if (CRI.hasUnwindDest())
2623       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2624     break;
2625   }
2626   case Instruction::CatchRet: {
2627     Code = bitc::FUNC_CODE_INST_CATCHRET;
2628     const auto &CRI = cast<CatchReturnInst>(I);
2629     pushValue(CRI.getCatchPad(), InstID, Vals);
2630     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2631     break;
2632   }
2633   case Instruction::CleanupPad:
2634   case Instruction::CatchPad: {
2635     const auto &FuncletPad = cast<FuncletPadInst>(I);
2636     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2637                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2638     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2639 
2640     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2641     Vals.push_back(NumArgOperands);
2642     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2643       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2644     break;
2645   }
2646   case Instruction::CatchSwitch: {
2647     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2648     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2649 
2650     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2651 
2652     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2653     Vals.push_back(NumHandlers);
2654     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2655       Vals.push_back(VE.getValueID(CatchPadBB));
2656 
2657     if (CatchSwitch.hasUnwindDest())
2658       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2659     break;
2660   }
2661   case Instruction::Unreachable:
2662     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2663     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2664     break;
2665 
2666   case Instruction::PHI: {
2667     const PHINode &PN = cast<PHINode>(I);
2668     Code = bitc::FUNC_CODE_INST_PHI;
2669     // With the newer instruction encoding, forward references could give
2670     // negative valued IDs.  This is most common for PHIs, so we use
2671     // signed VBRs.
2672     SmallVector<uint64_t, 128> Vals64;
2673     Vals64.push_back(VE.getTypeID(PN.getType()));
2674     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2675       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2676       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2677     }
2678     // Emit a Vals64 vector and exit.
2679     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2680     Vals64.clear();
2681     return;
2682   }
2683 
2684   case Instruction::LandingPad: {
2685     const LandingPadInst &LP = cast<LandingPadInst>(I);
2686     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2687     Vals.push_back(VE.getTypeID(LP.getType()));
2688     Vals.push_back(LP.isCleanup());
2689     Vals.push_back(LP.getNumClauses());
2690     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2691       if (LP.isCatch(I))
2692         Vals.push_back(LandingPadInst::Catch);
2693       else
2694         Vals.push_back(LandingPadInst::Filter);
2695       pushValueAndType(LP.getClause(I), InstID, Vals);
2696     }
2697     break;
2698   }
2699 
2700   case Instruction::Alloca: {
2701     Code = bitc::FUNC_CODE_INST_ALLOCA;
2702     const AllocaInst &AI = cast<AllocaInst>(I);
2703     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2704     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2705     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2706     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2707     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2708            "not enough bits for maximum alignment");
2709     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2710     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2711     AlignRecord |= 1 << 6;
2712     AlignRecord |= AI.isSwiftError() << 7;
2713     Vals.push_back(AlignRecord);
2714     break;
2715   }
2716 
2717   case Instruction::Load:
2718     if (cast<LoadInst>(I).isAtomic()) {
2719       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2720       pushValueAndType(I.getOperand(0), InstID, Vals);
2721     } else {
2722       Code = bitc::FUNC_CODE_INST_LOAD;
2723       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2724         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2725     }
2726     Vals.push_back(VE.getTypeID(I.getType()));
2727     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2728     Vals.push_back(cast<LoadInst>(I).isVolatile());
2729     if (cast<LoadInst>(I).isAtomic()) {
2730       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2731       Vals.push_back(getEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2732     }
2733     break;
2734   case Instruction::Store:
2735     if (cast<StoreInst>(I).isAtomic())
2736       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2737     else
2738       Code = bitc::FUNC_CODE_INST_STORE;
2739     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2740     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2741     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2742     Vals.push_back(cast<StoreInst>(I).isVolatile());
2743     if (cast<StoreInst>(I).isAtomic()) {
2744       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2745       Vals.push_back(getEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2746     }
2747     break;
2748   case Instruction::AtomicCmpXchg:
2749     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2750     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2751     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2752     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2753     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2754     Vals.push_back(
2755         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2756     Vals.push_back(
2757         getEncodedSynchScope(cast<AtomicCmpXchgInst>(I).getSynchScope()));
2758     Vals.push_back(
2759         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2760     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2761     break;
2762   case Instruction::AtomicRMW:
2763     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2764     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2765     pushValue(I.getOperand(1), InstID, Vals);        // val.
2766     Vals.push_back(
2767         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2768     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2769     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2770     Vals.push_back(
2771         getEncodedSynchScope(cast<AtomicRMWInst>(I).getSynchScope()));
2772     break;
2773   case Instruction::Fence:
2774     Code = bitc::FUNC_CODE_INST_FENCE;
2775     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2776     Vals.push_back(getEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2777     break;
2778   case Instruction::Call: {
2779     const CallInst &CI = cast<CallInst>(I);
2780     FunctionType *FTy = CI.getFunctionType();
2781 
2782     if (CI.hasOperandBundles())
2783       writeOperandBundles(&CI, InstID);
2784 
2785     Code = bitc::FUNC_CODE_INST_CALL;
2786 
2787     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2788 
2789     unsigned Flags = getOptimizationFlags(&I);
2790     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2791                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2792                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2793                    1 << bitc::CALL_EXPLICIT_TYPE |
2794                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2795                    unsigned(Flags != 0) << bitc::CALL_FMF);
2796     if (Flags != 0)
2797       Vals.push_back(Flags);
2798 
2799     Vals.push_back(VE.getTypeID(FTy));
2800     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2801 
2802     // Emit value #'s for the fixed parameters.
2803     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2804       // Check for labels (can happen with asm labels).
2805       if (FTy->getParamType(i)->isLabelTy())
2806         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2807       else
2808         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2809     }
2810 
2811     // Emit type/value pairs for varargs params.
2812     if (FTy->isVarArg()) {
2813       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2814            i != e; ++i)
2815         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2816     }
2817     break;
2818   }
2819   case Instruction::VAArg:
2820     Code = bitc::FUNC_CODE_INST_VAARG;
2821     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2822     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2823     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2824     break;
2825   }
2826 
2827   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2828   Vals.clear();
2829 }
2830 
2831 /// Emit names for globals/functions etc. \p IsModuleLevel is true when
2832 /// we are writing the module-level VST, where we are including a function
2833 /// bitcode index and need to backpatch the VST forward declaration record.
2834 void ModuleBitcodeWriter::writeValueSymbolTable(
2835     const ValueSymbolTable &VST, bool IsModuleLevel,
2836     DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex) {
2837   if (VST.empty()) {
2838     // writeValueSymbolTableForwardDecl should have returned early as
2839     // well. Ensure this handling remains in sync by asserting that
2840     // the placeholder offset is not set.
2841     assert(!IsModuleLevel || !hasVSTOffsetPlaceholder());
2842     return;
2843   }
2844 
2845   if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
2846     // Get the offset of the VST we are writing, and backpatch it into
2847     // the VST forward declaration record.
2848     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2849     // The BitcodeStartBit was the stream offset of the identification block.
2850     VSTOffset -= bitcodeStartBit();
2851     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2852     // Note that we add 1 here because the offset is relative to one word
2853     // before the start of the identification block, which was historically
2854     // always the start of the regular bitcode header.
2855     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2856   }
2857 
2858   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2859 
2860   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2861   // records, which are not used in the per-function VSTs.
2862   unsigned FnEntry8BitAbbrev;
2863   unsigned FnEntry7BitAbbrev;
2864   unsigned FnEntry6BitAbbrev;
2865   unsigned GUIDEntryAbbrev;
2866   if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
2867     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2868     auto Abbv = std::make_shared<BitCodeAbbrev>();
2869     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2870     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2871     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2872     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2873     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2874     FnEntry8BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2875 
2876     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2877     Abbv = std::make_shared<BitCodeAbbrev>();
2878     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2879     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2880     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2881     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2882     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2883     FnEntry7BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2884 
2885     // 6-bit char6 VST_CODE_FNENTRY function strings.
2886     Abbv = std::make_shared<BitCodeAbbrev>();
2887     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2888     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2889     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2890     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2891     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2892     FnEntry6BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2893 
2894     // FIXME: Change the name of this record as it is now used by
2895     // the per-module index as well.
2896     Abbv = std::make_shared<BitCodeAbbrev>();
2897     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2898     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2899     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2900     GUIDEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2901   }
2902 
2903   // FIXME: Set up the abbrev, we know how many values there are!
2904   // FIXME: We know if the type names can use 7-bit ascii.
2905   SmallVector<uint64_t, 64> NameVals;
2906 
2907   for (const ValueName &Name : VST) {
2908     // Figure out the encoding to use for the name.
2909     StringEncoding Bits =
2910         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2911 
2912     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2913     NameVals.push_back(VE.getValueID(Name.getValue()));
2914 
2915     Function *F = dyn_cast<Function>(Name.getValue());
2916     if (!F) {
2917       // If value is an alias, need to get the aliased base object to
2918       // see if it is a function.
2919       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2920       if (GA && GA->getBaseObject())
2921         F = dyn_cast<Function>(GA->getBaseObject());
2922     }
2923 
2924     // VST_CODE_ENTRY:   [valueid, namechar x N]
2925     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2926     // VST_CODE_BBENTRY: [bbid, namechar x N]
2927     unsigned Code;
2928     if (isa<BasicBlock>(Name.getValue())) {
2929       Code = bitc::VST_CODE_BBENTRY;
2930       if (Bits == SE_Char6)
2931         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2932     } else if (F && !F->isDeclaration()) {
2933       // Must be the module-level VST, where we pass in the Index and
2934       // have a VSTOffsetPlaceholder. The function-level VST should not
2935       // contain any Function symbols.
2936       assert(FunctionToBitcodeIndex);
2937       assert(hasVSTOffsetPlaceholder());
2938 
2939       // Save the word offset of the function (from the start of the
2940       // actual bitcode written to the stream).
2941       uint64_t BitcodeIndex = (*FunctionToBitcodeIndex)[F] - bitcodeStartBit();
2942       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2943       // Note that we add 1 here because the offset is relative to one word
2944       // before the start of the identification block, which was historically
2945       // always the start of the regular bitcode header.
2946       NameVals.push_back(BitcodeIndex / 32 + 1);
2947 
2948       Code = bitc::VST_CODE_FNENTRY;
2949       AbbrevToUse = FnEntry8BitAbbrev;
2950       if (Bits == SE_Char6)
2951         AbbrevToUse = FnEntry6BitAbbrev;
2952       else if (Bits == SE_Fixed7)
2953         AbbrevToUse = FnEntry7BitAbbrev;
2954     } else {
2955       Code = bitc::VST_CODE_ENTRY;
2956       if (Bits == SE_Char6)
2957         AbbrevToUse = VST_ENTRY_6_ABBREV;
2958       else if (Bits == SE_Fixed7)
2959         AbbrevToUse = VST_ENTRY_7_ABBREV;
2960     }
2961 
2962     for (const auto P : Name.getKey())
2963       NameVals.push_back((unsigned char)P);
2964 
2965     // Emit the finished record.
2966     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2967     NameVals.clear();
2968   }
2969   // Emit any GUID valueIDs created for indirect call edges into the
2970   // module-level VST.
2971   if (IsModuleLevel && hasVSTOffsetPlaceholder())
2972     for (const auto &GI : valueIds()) {
2973       NameVals.push_back(GI.second);
2974       NameVals.push_back(GI.first);
2975       Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals,
2976                         GUIDEntryAbbrev);
2977       NameVals.clear();
2978     }
2979   Stream.ExitBlock();
2980 }
2981 
2982 /// Emit function names and summary offsets for the combined index
2983 /// used by ThinLTO.
2984 void IndexBitcodeWriter::writeCombinedValueSymbolTable() {
2985   assert(hasVSTOffsetPlaceholder() && "Expected non-zero VSTOffsetPlaceholder");
2986   // Get the offset of the VST we are writing, and backpatch it into
2987   // the VST forward declaration record.
2988   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2989   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2990   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2991 
2992   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2993 
2994   auto Abbv = std::make_shared<BitCodeAbbrev>();
2995   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2996   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2997   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2998   unsigned EntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2999 
3000   SmallVector<uint64_t, 64> NameVals;
3001   for (const auto &GVI : valueIds()) {
3002     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
3003     NameVals.push_back(GVI.second);
3004     NameVals.push_back(GVI.first);
3005 
3006     // Emit the finished record.
3007     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
3008     NameVals.clear();
3009   }
3010   Stream.ExitBlock();
3011 }
3012 
3013 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3014   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3015   unsigned Code;
3016   if (isa<BasicBlock>(Order.V))
3017     Code = bitc::USELIST_CODE_BB;
3018   else
3019     Code = bitc::USELIST_CODE_DEFAULT;
3020 
3021   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3022   Record.push_back(VE.getValueID(Order.V));
3023   Stream.EmitRecord(Code, Record);
3024 }
3025 
3026 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3027   assert(VE.shouldPreserveUseListOrder() &&
3028          "Expected to be preserving use-list order");
3029 
3030   auto hasMore = [&]() {
3031     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3032   };
3033   if (!hasMore())
3034     // Nothing to do.
3035     return;
3036 
3037   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3038   while (hasMore()) {
3039     writeUseList(std::move(VE.UseListOrders.back()));
3040     VE.UseListOrders.pop_back();
3041   }
3042   Stream.ExitBlock();
3043 }
3044 
3045 /// Emit a function body to the module stream.
3046 void ModuleBitcodeWriter::writeFunction(
3047     const Function &F,
3048     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3049   // Save the bitcode index of the start of this function block for recording
3050   // in the VST.
3051   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3052 
3053   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3054   VE.incorporateFunction(F);
3055 
3056   SmallVector<unsigned, 64> Vals;
3057 
3058   // Emit the number of basic blocks, so the reader can create them ahead of
3059   // time.
3060   Vals.push_back(VE.getBasicBlocks().size());
3061   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3062   Vals.clear();
3063 
3064   // If there are function-local constants, emit them now.
3065   unsigned CstStart, CstEnd;
3066   VE.getFunctionConstantRange(CstStart, CstEnd);
3067   writeConstants(CstStart, CstEnd, false);
3068 
3069   // If there is function-local metadata, emit it now.
3070   writeFunctionMetadata(F);
3071 
3072   // Keep a running idea of what the instruction ID is.
3073   unsigned InstID = CstEnd;
3074 
3075   bool NeedsMetadataAttachment = F.hasMetadata();
3076 
3077   DILocation *LastDL = nullptr;
3078   // Finally, emit all the instructions, in order.
3079   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3080     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3081          I != E; ++I) {
3082       writeInstruction(*I, InstID, Vals);
3083 
3084       if (!I->getType()->isVoidTy())
3085         ++InstID;
3086 
3087       // If the instruction has metadata, write a metadata attachment later.
3088       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3089 
3090       // If the instruction has a debug location, emit it.
3091       DILocation *DL = I->getDebugLoc();
3092       if (!DL)
3093         continue;
3094 
3095       if (DL == LastDL) {
3096         // Just repeat the same debug loc as last time.
3097         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3098         continue;
3099       }
3100 
3101       Vals.push_back(DL->getLine());
3102       Vals.push_back(DL->getColumn());
3103       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3104       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3105       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3106       Vals.clear();
3107 
3108       LastDL = DL;
3109     }
3110 
3111   // Emit names for all the instructions etc.
3112   if (auto *Symtab = F.getValueSymbolTable())
3113     writeValueSymbolTable(*Symtab);
3114 
3115   if (NeedsMetadataAttachment)
3116     writeFunctionMetadataAttachment(F);
3117   if (VE.shouldPreserveUseListOrder())
3118     writeUseListBlock(&F);
3119   VE.purgeFunction();
3120   Stream.ExitBlock();
3121 }
3122 
3123 // Emit blockinfo, which defines the standard abbreviations etc.
3124 void ModuleBitcodeWriter::writeBlockInfo() {
3125   // We only want to emit block info records for blocks that have multiple
3126   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3127   // Other blocks can define their abbrevs inline.
3128   Stream.EnterBlockInfoBlock();
3129 
3130   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3131     auto Abbv = std::make_shared<BitCodeAbbrev>();
3132     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3134     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3135     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3136     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3137         VST_ENTRY_8_ABBREV)
3138       llvm_unreachable("Unexpected abbrev ordering!");
3139   }
3140 
3141   { // 7-bit fixed width VST_CODE_ENTRY strings.
3142     auto Abbv = std::make_shared<BitCodeAbbrev>();
3143     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3144     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3146     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3147     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3148         VST_ENTRY_7_ABBREV)
3149       llvm_unreachable("Unexpected abbrev ordering!");
3150   }
3151   { // 6-bit char6 VST_CODE_ENTRY strings.
3152     auto Abbv = std::make_shared<BitCodeAbbrev>();
3153     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3154     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3156     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3157     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3158         VST_ENTRY_6_ABBREV)
3159       llvm_unreachable("Unexpected abbrev ordering!");
3160   }
3161   { // 6-bit char6 VST_CODE_BBENTRY strings.
3162     auto Abbv = std::make_shared<BitCodeAbbrev>();
3163     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3164     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3165     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3166     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3167     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3168         VST_BBENTRY_6_ABBREV)
3169       llvm_unreachable("Unexpected abbrev ordering!");
3170   }
3171 
3172 
3173 
3174   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3175     auto Abbv = std::make_shared<BitCodeAbbrev>();
3176     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3178                               VE.computeBitsRequiredForTypeIndicies()));
3179     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3180         CONSTANTS_SETTYPE_ABBREV)
3181       llvm_unreachable("Unexpected abbrev ordering!");
3182   }
3183 
3184   { // INTEGER abbrev for CONSTANTS_BLOCK.
3185     auto Abbv = std::make_shared<BitCodeAbbrev>();
3186     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3187     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3188     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3189         CONSTANTS_INTEGER_ABBREV)
3190       llvm_unreachable("Unexpected abbrev ordering!");
3191   }
3192 
3193   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3194     auto Abbv = std::make_shared<BitCodeAbbrev>();
3195     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3196     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3197     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3198                               VE.computeBitsRequiredForTypeIndicies()));
3199     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3200 
3201     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3202         CONSTANTS_CE_CAST_Abbrev)
3203       llvm_unreachable("Unexpected abbrev ordering!");
3204   }
3205   { // NULL abbrev for CONSTANTS_BLOCK.
3206     auto Abbv = std::make_shared<BitCodeAbbrev>();
3207     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3208     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3209         CONSTANTS_NULL_Abbrev)
3210       llvm_unreachable("Unexpected abbrev ordering!");
3211   }
3212 
3213   // FIXME: This should only use space for first class types!
3214 
3215   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3216     auto Abbv = std::make_shared<BitCodeAbbrev>();
3217     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3218     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3220                               VE.computeBitsRequiredForTypeIndicies()));
3221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3223     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3224         FUNCTION_INST_LOAD_ABBREV)
3225       llvm_unreachable("Unexpected abbrev ordering!");
3226   }
3227   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3228     auto Abbv = std::make_shared<BitCodeAbbrev>();
3229     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3230     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3231     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3233     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3234         FUNCTION_INST_BINOP_ABBREV)
3235       llvm_unreachable("Unexpected abbrev ordering!");
3236   }
3237   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3238     auto Abbv = std::make_shared<BitCodeAbbrev>();
3239     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3240     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3241     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3242     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3243     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
3244     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3245         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3246       llvm_unreachable("Unexpected abbrev ordering!");
3247   }
3248   { // INST_CAST abbrev for FUNCTION_BLOCK.
3249     auto Abbv = std::make_shared<BitCodeAbbrev>();
3250     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3251     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3252     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3253                               VE.computeBitsRequiredForTypeIndicies()));
3254     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3255     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3256         FUNCTION_INST_CAST_ABBREV)
3257       llvm_unreachable("Unexpected abbrev ordering!");
3258   }
3259 
3260   { // INST_RET abbrev for FUNCTION_BLOCK.
3261     auto Abbv = std::make_shared<BitCodeAbbrev>();
3262     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3263     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3264         FUNCTION_INST_RET_VOID_ABBREV)
3265       llvm_unreachable("Unexpected abbrev ordering!");
3266   }
3267   { // INST_RET abbrev for FUNCTION_BLOCK.
3268     auto Abbv = std::make_shared<BitCodeAbbrev>();
3269     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3270     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3271     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3272         FUNCTION_INST_RET_VAL_ABBREV)
3273       llvm_unreachable("Unexpected abbrev ordering!");
3274   }
3275   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3276     auto Abbv = std::make_shared<BitCodeAbbrev>();
3277     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3278     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3279         FUNCTION_INST_UNREACHABLE_ABBREV)
3280       llvm_unreachable("Unexpected abbrev ordering!");
3281   }
3282   {
3283     auto Abbv = std::make_shared<BitCodeAbbrev>();
3284     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3285     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3286     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3287                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3288     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3289     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3290     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3291         FUNCTION_INST_GEP_ABBREV)
3292       llvm_unreachable("Unexpected abbrev ordering!");
3293   }
3294 
3295   Stream.ExitBlock();
3296 }
3297 
3298 /// Write the module path strings, currently only used when generating
3299 /// a combined index file.
3300 void IndexBitcodeWriter::writeModStrings() {
3301   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3302 
3303   // TODO: See which abbrev sizes we actually need to emit
3304 
3305   // 8-bit fixed-width MST_ENTRY strings.
3306   auto Abbv = std::make_shared<BitCodeAbbrev>();
3307   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3308   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3309   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3310   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3311   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3312 
3313   // 7-bit fixed width MST_ENTRY strings.
3314   Abbv = std::make_shared<BitCodeAbbrev>();
3315   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3316   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3317   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3318   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3319   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3320 
3321   // 6-bit char6 MST_ENTRY strings.
3322   Abbv = std::make_shared<BitCodeAbbrev>();
3323   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3324   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3325   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3326   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3327   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3328 
3329   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3330   Abbv = std::make_shared<BitCodeAbbrev>();
3331   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3332   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3333   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3334   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3335   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3336   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3337   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3338 
3339   SmallVector<unsigned, 64> Vals;
3340   for (const auto &MPSE : Index.modulePaths()) {
3341     if (!doIncludeModule(MPSE.getKey()))
3342       continue;
3343     StringEncoding Bits =
3344         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
3345     unsigned AbbrevToUse = Abbrev8Bit;
3346     if (Bits == SE_Char6)
3347       AbbrevToUse = Abbrev6Bit;
3348     else if (Bits == SE_Fixed7)
3349       AbbrevToUse = Abbrev7Bit;
3350 
3351     Vals.push_back(MPSE.getValue().first);
3352 
3353     for (const auto P : MPSE.getKey())
3354       Vals.push_back((unsigned char)P);
3355 
3356     // Emit the finished record.
3357     Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3358 
3359     Vals.clear();
3360     // Emit an optional hash for the module now
3361     auto &Hash = MPSE.getValue().second;
3362     bool AllZero = true; // Detect if the hash is empty, and do not generate it
3363     for (auto Val : Hash) {
3364       if (Val)
3365         AllZero = false;
3366       Vals.push_back(Val);
3367     }
3368     if (!AllZero) {
3369       // Emit the hash record.
3370       Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3371     }
3372 
3373     Vals.clear();
3374   }
3375   Stream.ExitBlock();
3376 }
3377 
3378 /// Write the function type metadata related records that need to appear before
3379 /// a function summary entry (whether per-module or combined).
3380 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3381                                              FunctionSummary *FS) {
3382   if (!FS->type_tests().empty())
3383     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3384 
3385   SmallVector<uint64_t, 64> Record;
3386 
3387   auto WriteVFuncIdVec = [&](uint64_t Ty,
3388                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3389     if (VFs.empty())
3390       return;
3391     Record.clear();
3392     for (auto &VF : VFs) {
3393       Record.push_back(VF.GUID);
3394       Record.push_back(VF.Offset);
3395     }
3396     Stream.EmitRecord(Ty, Record);
3397   };
3398 
3399   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3400                   FS->type_test_assume_vcalls());
3401   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3402                   FS->type_checked_load_vcalls());
3403 
3404   auto WriteConstVCallVec = [&](uint64_t Ty,
3405                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3406     for (auto &VC : VCs) {
3407       Record.clear();
3408       Record.push_back(VC.VFunc.GUID);
3409       Record.push_back(VC.VFunc.Offset);
3410       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3411       Stream.EmitRecord(Ty, Record);
3412     }
3413   };
3414 
3415   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3416                      FS->type_test_assume_const_vcalls());
3417   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3418                      FS->type_checked_load_const_vcalls());
3419 }
3420 
3421 // Helper to emit a single function summary record.
3422 void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
3423     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3424     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3425     const Function &F) {
3426   NameVals.push_back(ValueID);
3427 
3428   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3429   writeFunctionTypeMetadataRecords(Stream, FS);
3430 
3431   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3432   NameVals.push_back(FS->instCount());
3433   NameVals.push_back(FS->refs().size());
3434 
3435   for (auto &RI : FS->refs())
3436     NameVals.push_back(VE.getValueID(RI.getValue()));
3437 
3438   bool HasProfileData = F.getEntryCount().hasValue();
3439   for (auto &ECI : FS->calls()) {
3440     NameVals.push_back(getValueId(ECI.first));
3441     if (HasProfileData)
3442       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3443   }
3444 
3445   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3446   unsigned Code =
3447       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
3448 
3449   // Emit the finished record.
3450   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3451   NameVals.clear();
3452 }
3453 
3454 // Collect the global value references in the given variable's initializer,
3455 // and emit them in a summary record.
3456 void ModuleBitcodeWriter::writeModuleLevelReferences(
3457     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3458     unsigned FSModRefsAbbrev) {
3459   auto Summaries =
3460       Index->findGlobalValueSummaryList(GlobalValue::getGUID(V.getName()));
3461   if (Summaries == Index->end()) {
3462     // Only declarations should not have a summary (a declaration might however
3463     // have a summary if the def was in module level asm).
3464     assert(V.isDeclaration());
3465     return;
3466   }
3467   auto *Summary = Summaries->second.front().get();
3468   NameVals.push_back(VE.getValueID(&V));
3469   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3470   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3471 
3472   unsigned SizeBeforeRefs = NameVals.size();
3473   for (auto &RI : VS->refs())
3474     NameVals.push_back(VE.getValueID(RI.getValue()));
3475   // Sort the refs for determinism output, the vector returned by FS->refs() has
3476   // been initialized from a DenseSet.
3477   std::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3478 
3479   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3480                     FSModRefsAbbrev);
3481   NameVals.clear();
3482 }
3483 
3484 // Current version for the summary.
3485 // This is bumped whenever we introduce changes in the way some record are
3486 // interpreted, like flags for instance.
3487 static const uint64_t INDEX_VERSION = 3;
3488 
3489 /// Emit the per-module summary section alongside the rest of
3490 /// the module's bitcode.
3491 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
3492   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 4);
3493 
3494   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3495 
3496   if (Index->begin() == Index->end()) {
3497     Stream.ExitBlock();
3498     return;
3499   }
3500 
3501   // Abbrev for FS_PERMODULE.
3502   auto Abbv = std::make_shared<BitCodeAbbrev>();
3503   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3504   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3505   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3506   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3507   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3508   // numrefs x valueid, n x (valueid)
3509   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3510   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3511   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3512 
3513   // Abbrev for FS_PERMODULE_PROFILE.
3514   Abbv = std::make_shared<BitCodeAbbrev>();
3515   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3516   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3517   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3518   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3519   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3520   // numrefs x valueid, n x (valueid, hotness)
3521   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3522   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3523   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3524 
3525   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3526   Abbv = std::make_shared<BitCodeAbbrev>();
3527   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3528   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3529   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3530   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3531   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3532   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3533 
3534   // Abbrev for FS_ALIAS.
3535   Abbv = std::make_shared<BitCodeAbbrev>();
3536   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3537   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3538   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3539   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3540   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3541 
3542   SmallVector<uint64_t, 64> NameVals;
3543   // Iterate over the list of functions instead of the Index to
3544   // ensure the ordering is stable.
3545   for (const Function &F : M) {
3546     // Summary emission does not support anonymous functions, they have to
3547     // renamed using the anonymous function renaming pass.
3548     if (!F.hasName())
3549       report_fatal_error("Unexpected anonymous function when writing summary");
3550 
3551     auto Summaries =
3552         Index->findGlobalValueSummaryList(GlobalValue::getGUID(F.getName()));
3553     if (Summaries == Index->end()) {
3554       // Only declarations should not have a summary (a declaration might
3555       // however have a summary if the def was in module level asm).
3556       assert(F.isDeclaration());
3557       continue;
3558     }
3559     auto *Summary = Summaries->second.front().get();
3560     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3561                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3562   }
3563 
3564   // Capture references from GlobalVariable initializers, which are outside
3565   // of a function scope.
3566   for (const GlobalVariable &G : M.globals())
3567     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3568 
3569   for (const GlobalAlias &A : M.aliases()) {
3570     auto *Aliasee = A.getBaseObject();
3571     if (!Aliasee->hasName())
3572       // Nameless function don't have an entry in the summary, skip it.
3573       continue;
3574     auto AliasId = VE.getValueID(&A);
3575     auto AliaseeId = VE.getValueID(Aliasee);
3576     NameVals.push_back(AliasId);
3577     auto *Summary = Index->getGlobalValueSummary(A);
3578     AliasSummary *AS = cast<AliasSummary>(Summary);
3579     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3580     NameVals.push_back(AliaseeId);
3581     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3582     NameVals.clear();
3583   }
3584 
3585   Stream.ExitBlock();
3586 }
3587 
3588 /// Emit the combined summary section into the combined index file.
3589 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3590   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3591   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3592 
3593   // Abbrev for FS_COMBINED.
3594   auto Abbv = std::make_shared<BitCodeAbbrev>();
3595   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3596   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3597   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3598   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3599   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3600   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3601   // numrefs x valueid, n x (valueid)
3602   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3603   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3604   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3605 
3606   // Abbrev for FS_COMBINED_PROFILE.
3607   Abbv = std::make_shared<BitCodeAbbrev>();
3608   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3609   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3610   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3611   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3612   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3613   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3614   // numrefs x valueid, n x (valueid, hotness)
3615   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3616   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3617   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3618 
3619   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3620   Abbv = std::make_shared<BitCodeAbbrev>();
3621   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3622   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3623   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3624   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3625   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3626   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3627   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3628 
3629   // Abbrev for FS_COMBINED_ALIAS.
3630   Abbv = std::make_shared<BitCodeAbbrev>();
3631   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3632   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3633   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3634   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3635   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3636   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3637 
3638   // The aliases are emitted as a post-pass, and will point to the value
3639   // id of the aliasee. Save them in a vector for post-processing.
3640   SmallVector<AliasSummary *, 64> Aliases;
3641 
3642   // Save the value id for each summary for alias emission.
3643   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3644 
3645   SmallVector<uint64_t, 64> NameVals;
3646 
3647   // For local linkage, we also emit the original name separately
3648   // immediately after the record.
3649   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3650     if (!GlobalValue::isLocalLinkage(S.linkage()))
3651       return;
3652     NameVals.push_back(S.getOriginalName());
3653     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3654     NameVals.clear();
3655   };
3656 
3657   for (const auto &I : *this) {
3658     GlobalValueSummary *S = I.second;
3659     assert(S);
3660 
3661     assert(hasValueId(I.first));
3662     unsigned ValueId = getValueId(I.first);
3663     SummaryToValueIdMap[S] = ValueId;
3664 
3665     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3666       // Will process aliases as a post-pass because the reader wants all
3667       // global to be loaded first.
3668       Aliases.push_back(AS);
3669       continue;
3670     }
3671 
3672     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3673       NameVals.push_back(ValueId);
3674       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3675       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3676       for (auto &RI : VS->refs()) {
3677         NameVals.push_back(getValueId(RI.getGUID()));
3678       }
3679 
3680       // Emit the finished record.
3681       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3682                         FSModRefsAbbrev);
3683       NameVals.clear();
3684       MaybeEmitOriginalName(*S);
3685       continue;
3686     }
3687 
3688     auto *FS = cast<FunctionSummary>(S);
3689     writeFunctionTypeMetadataRecords(Stream, FS);
3690 
3691     NameVals.push_back(ValueId);
3692     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3693     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3694     NameVals.push_back(FS->instCount());
3695     NameVals.push_back(FS->refs().size());
3696 
3697     for (auto &RI : FS->refs()) {
3698       NameVals.push_back(getValueId(RI.getGUID()));
3699     }
3700 
3701     bool HasProfileData = false;
3702     for (auto &EI : FS->calls()) {
3703       HasProfileData |= EI.second.Hotness != CalleeInfo::HotnessType::Unknown;
3704       if (HasProfileData)
3705         break;
3706     }
3707 
3708     for (auto &EI : FS->calls()) {
3709       // If this GUID doesn't have a value id, it doesn't have a function
3710       // summary and we don't need to record any calls to it.
3711       GlobalValue::GUID GUID = EI.first.getGUID();
3712       if (!hasValueId(GUID)) {
3713         // For SamplePGO, the indirect call targets for local functions will
3714         // have its original name annotated in profile. We try to find the
3715         // corresponding PGOFuncName as the GUID.
3716         GUID = Index.getGUIDFromOriginalID(GUID);
3717         if (GUID == 0 || !hasValueId(GUID))
3718           continue;
3719       }
3720       NameVals.push_back(getValueId(GUID));
3721       if (HasProfileData)
3722         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3723     }
3724 
3725     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3726     unsigned Code =
3727         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3728 
3729     // Emit the finished record.
3730     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3731     NameVals.clear();
3732     MaybeEmitOriginalName(*S);
3733   }
3734 
3735   for (auto *AS : Aliases) {
3736     auto AliasValueId = SummaryToValueIdMap[AS];
3737     assert(AliasValueId);
3738     NameVals.push_back(AliasValueId);
3739     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3740     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3741     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3742     assert(AliaseeValueId);
3743     NameVals.push_back(AliaseeValueId);
3744 
3745     // Emit the finished record.
3746     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3747     NameVals.clear();
3748     MaybeEmitOriginalName(*AS);
3749   }
3750 
3751   Stream.ExitBlock();
3752 }
3753 
3754 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3755 /// current llvm version, and a record for the epoch number.
3756 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3757   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3758 
3759   // Write the "user readable" string identifying the bitcode producer
3760   auto Abbv = std::make_shared<BitCodeAbbrev>();
3761   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3762   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3763   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3764   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3765   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3766                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3767 
3768   // Write the epoch version
3769   Abbv = std::make_shared<BitCodeAbbrev>();
3770   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3771   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3772   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3773   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3774   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3775   Stream.ExitBlock();
3776 }
3777 
3778 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3779   // Emit the module's hash.
3780   // MODULE_CODE_HASH: [5*i32]
3781   SHA1 Hasher;
3782   Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3783                                   Buffer.size() - BlockStartPos));
3784   StringRef Hash = Hasher.result();
3785   uint32_t Vals[5];
3786   for (int Pos = 0; Pos < 20; Pos += 4) {
3787     Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3788   }
3789 
3790   // Emit the finished record.
3791   Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3792 }
3793 
3794 void ModuleBitcodeWriter::write() {
3795   writeIdentificationBlock(Stream);
3796 
3797   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3798   size_t BlockStartPos = Buffer.size();
3799 
3800   SmallVector<unsigned, 1> Vals;
3801   unsigned CurVersion = 1;
3802   Vals.push_back(CurVersion);
3803   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3804 
3805   // Emit blockinfo, which defines the standard abbreviations etc.
3806   writeBlockInfo();
3807 
3808   // Emit information about attribute groups.
3809   writeAttributeGroupTable();
3810 
3811   // Emit information about parameter attributes.
3812   writeAttributeTable();
3813 
3814   // Emit information describing all of the types in the module.
3815   writeTypeTable();
3816 
3817   writeComdats();
3818 
3819   // Emit top-level description of module, including target triple, inline asm,
3820   // descriptors for global variables, and function prototype info.
3821   writeModuleInfo();
3822 
3823   // Emit constants.
3824   writeModuleConstants();
3825 
3826   // Emit metadata kind names.
3827   writeModuleMetadataKinds();
3828 
3829   // Emit metadata.
3830   writeModuleMetadata();
3831 
3832   // Emit module-level use-lists.
3833   if (VE.shouldPreserveUseListOrder())
3834     writeUseListBlock(nullptr);
3835 
3836   writeOperandBundleTags();
3837 
3838   // Emit function bodies.
3839   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3840   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3841     if (!F->isDeclaration())
3842       writeFunction(*F, FunctionToBitcodeIndex);
3843 
3844   // Need to write after the above call to WriteFunction which populates
3845   // the summary information in the index.
3846   if (Index)
3847     writePerModuleGlobalValueSummary();
3848 
3849   writeValueSymbolTable(M.getValueSymbolTable(),
3850                         /* IsModuleLevel */ true, &FunctionToBitcodeIndex);
3851 
3852   if (GenerateHash) {
3853     writeModuleHash(BlockStartPos);
3854   }
3855 
3856   Stream.ExitBlock();
3857 }
3858 
3859 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3860                                uint32_t &Position) {
3861   support::endian::write32le(&Buffer[Position], Value);
3862   Position += 4;
3863 }
3864 
3865 /// If generating a bc file on darwin, we have to emit a
3866 /// header and trailer to make it compatible with the system archiver.  To do
3867 /// this we emit the following header, and then emit a trailer that pads the
3868 /// file out to be a multiple of 16 bytes.
3869 ///
3870 /// struct bc_header {
3871 ///   uint32_t Magic;         // 0x0B17C0DE
3872 ///   uint32_t Version;       // Version, currently always 0.
3873 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3874 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3875 ///   uint32_t CPUType;       // CPU specifier.
3876 ///   ... potentially more later ...
3877 /// };
3878 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3879                                          const Triple &TT) {
3880   unsigned CPUType = ~0U;
3881 
3882   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3883   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3884   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3885   // specific constants here because they are implicitly part of the Darwin ABI.
3886   enum {
3887     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3888     DARWIN_CPU_TYPE_X86        = 7,
3889     DARWIN_CPU_TYPE_ARM        = 12,
3890     DARWIN_CPU_TYPE_POWERPC    = 18
3891   };
3892 
3893   Triple::ArchType Arch = TT.getArch();
3894   if (Arch == Triple::x86_64)
3895     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3896   else if (Arch == Triple::x86)
3897     CPUType = DARWIN_CPU_TYPE_X86;
3898   else if (Arch == Triple::ppc)
3899     CPUType = DARWIN_CPU_TYPE_POWERPC;
3900   else if (Arch == Triple::ppc64)
3901     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3902   else if (Arch == Triple::arm || Arch == Triple::thumb)
3903     CPUType = DARWIN_CPU_TYPE_ARM;
3904 
3905   // Traditional Bitcode starts after header.
3906   assert(Buffer.size() >= BWH_HeaderSize &&
3907          "Expected header size to be reserved");
3908   unsigned BCOffset = BWH_HeaderSize;
3909   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3910 
3911   // Write the magic and version.
3912   unsigned Position = 0;
3913   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
3914   writeInt32ToBuffer(0, Buffer, Position); // Version.
3915   writeInt32ToBuffer(BCOffset, Buffer, Position);
3916   writeInt32ToBuffer(BCSize, Buffer, Position);
3917   writeInt32ToBuffer(CPUType, Buffer, Position);
3918 
3919   // If the file is not a multiple of 16 bytes, insert dummy padding.
3920   while (Buffer.size() & 15)
3921     Buffer.push_back(0);
3922 }
3923 
3924 /// Helper to write the header common to all bitcode files.
3925 static void writeBitcodeHeader(BitstreamWriter &Stream) {
3926   // Emit the file header.
3927   Stream.Emit((unsigned)'B', 8);
3928   Stream.Emit((unsigned)'C', 8);
3929   Stream.Emit(0x0, 4);
3930   Stream.Emit(0xC, 4);
3931   Stream.Emit(0xE, 4);
3932   Stream.Emit(0xD, 4);
3933 }
3934 
3935 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
3936     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
3937   writeBitcodeHeader(*Stream);
3938 }
3939 
3940 BitcodeWriter::~BitcodeWriter() = default;
3941 
3942 void BitcodeWriter::writeModule(const Module *M,
3943                                 bool ShouldPreserveUseListOrder,
3944                                 const ModuleSummaryIndex *Index,
3945                                 bool GenerateHash) {
3946   ModuleBitcodeWriter ModuleWriter(
3947       M, Buffer, *Stream, ShouldPreserveUseListOrder, Index, GenerateHash);
3948   ModuleWriter.write();
3949 }
3950 
3951 /// WriteBitcodeToFile - Write the specified module to the specified output
3952 /// stream.
3953 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3954                               bool ShouldPreserveUseListOrder,
3955                               const ModuleSummaryIndex *Index,
3956                               bool GenerateHash) {
3957   SmallVector<char, 0> Buffer;
3958   Buffer.reserve(256*1024);
3959 
3960   // If this is darwin or another generic macho target, reserve space for the
3961   // header.
3962   Triple TT(M->getTargetTriple());
3963   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3964     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3965 
3966   BitcodeWriter Writer(Buffer);
3967   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash);
3968 
3969   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3970     emitDarwinBCHeaderAndTrailer(Buffer, TT);
3971 
3972   // Write the generated bitstream to "Out".
3973   Out.write((char*)&Buffer.front(), Buffer.size());
3974 }
3975 
3976 void IndexBitcodeWriter::write() {
3977   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3978 
3979   SmallVector<unsigned, 1> Vals;
3980   unsigned CurVersion = 1;
3981   Vals.push_back(CurVersion);
3982   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3983 
3984   // If we have a VST, write the VSTOFFSET record placeholder.
3985   writeValueSymbolTableForwardDecl();
3986 
3987   // Write the module paths in the combined index.
3988   writeModStrings();
3989 
3990   // Write the summary combined index records.
3991   writeCombinedGlobalValueSummary();
3992 
3993   // Need a special VST writer for the combined index (we don't have a
3994   // real VST and real values when this is invoked).
3995   writeCombinedValueSymbolTable();
3996 
3997   Stream.ExitBlock();
3998 }
3999 
4000 // Write the specified module summary index to the given raw output stream,
4001 // where it will be written in a new bitcode block. This is used when
4002 // writing the combined index file for ThinLTO. When writing a subset of the
4003 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4004 void llvm::WriteIndexToFile(
4005     const ModuleSummaryIndex &Index, raw_ostream &Out,
4006     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4007   SmallVector<char, 0> Buffer;
4008   Buffer.reserve(256 * 1024);
4009 
4010   BitstreamWriter Stream(Buffer);
4011   writeBitcodeHeader(Stream);
4012 
4013   IndexBitcodeWriter IndexWriter(Stream, Index, ModuleToSummariesForIndex);
4014   IndexWriter.write();
4015 
4016   Out.write((char *)&Buffer.front(), Buffer.size());
4017 }
4018