xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 66cf14d06b1c5d20417e312fabd14ffaf4314ae3)
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/APFloat.h"
17 #include "llvm/ADT/APInt.h"
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/None.h"
21 #include "llvm/ADT/Optional.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/StringMap.h"
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/Bitcode/BitCodes.h"
29 #include "llvm/Bitcode/BitstreamWriter.h"
30 #include "llvm/Bitcode/LLVMBitCodes.h"
31 #include "llvm/Config/llvm-config.h"
32 #include "llvm/IR/Attributes.h"
33 #include "llvm/IR/BasicBlock.h"
34 #include "llvm/IR/CallSite.h"
35 #include "llvm/IR/Comdat.h"
36 #include "llvm/IR/Constant.h"
37 #include "llvm/IR/Constants.h"
38 #include "llvm/IR/DebugInfoMetadata.h"
39 #include "llvm/IR/DebugLoc.h"
40 #include "llvm/IR/DerivedTypes.h"
41 #include "llvm/IR/Function.h"
42 #include "llvm/IR/GlobalAlias.h"
43 #include "llvm/IR/GlobalIFunc.h"
44 #include "llvm/IR/GlobalObject.h"
45 #include "llvm/IR/GlobalValue.h"
46 #include "llvm/IR/GlobalVariable.h"
47 #include "llvm/IR/InlineAsm.h"
48 #include "llvm/IR/InstrTypes.h"
49 #include "llvm/IR/Instruction.h"
50 #include "llvm/IR/Instructions.h"
51 #include "llvm/IR/LLVMContext.h"
52 #include "llvm/IR/Metadata.h"
53 #include "llvm/IR/Module.h"
54 #include "llvm/IR/ModuleSummaryIndex.h"
55 #include "llvm/IR/Operator.h"
56 #include "llvm/IR/Type.h"
57 #include "llvm/IR/UseListOrder.h"
58 #include "llvm/IR/Value.h"
59 #include "llvm/IR/ValueSymbolTable.h"
60 #include "llvm/MC/StringTableBuilder.h"
61 #include "llvm/Object/IRSymtab.h"
62 #include "llvm/Support/AtomicOrdering.h"
63 #include "llvm/Support/Casting.h"
64 #include "llvm/Support/CommandLine.h"
65 #include "llvm/Support/Endian.h"
66 #include "llvm/Support/Error.h"
67 #include "llvm/Support/ErrorHandling.h"
68 #include "llvm/Support/MathExtras.h"
69 #include "llvm/Support/SHA1.h"
70 #include "llvm/Support/TargetRegistry.h"
71 #include "llvm/Support/raw_ostream.h"
72 #include <algorithm>
73 #include <cassert>
74 #include <cstddef>
75 #include <cstdint>
76 #include <iterator>
77 #include <map>
78 #include <memory>
79 #include <string>
80 #include <utility>
81 #include <vector>
82 
83 using namespace llvm;
84 
85 static cl::opt<unsigned>
86     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
87                    cl::desc("Number of metadatas above which we emit an index "
88                             "to enable lazy-loading"));
89 
90 cl::opt<bool> WriteRelBFToSummary(
91     "write-relbf-to-summary", cl::Hidden, cl::init(false),
92     cl::desc("Write relative block frequency to function summary "));
93 
94 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
95 
96 namespace {
97 
98 /// These are manifest constants used by the bitcode writer. They do not need to
99 /// be kept in sync with the reader, but need to be consistent within this file.
100 enum {
101   // VALUE_SYMTAB_BLOCK abbrev id's.
102   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
103   VST_ENTRY_7_ABBREV,
104   VST_ENTRY_6_ABBREV,
105   VST_BBENTRY_6_ABBREV,
106 
107   // CONSTANTS_BLOCK abbrev id's.
108   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
109   CONSTANTS_INTEGER_ABBREV,
110   CONSTANTS_CE_CAST_Abbrev,
111   CONSTANTS_NULL_Abbrev,
112 
113   // FUNCTION_BLOCK abbrev id's.
114   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
115   FUNCTION_INST_BINOP_ABBREV,
116   FUNCTION_INST_BINOP_FLAGS_ABBREV,
117   FUNCTION_INST_CAST_ABBREV,
118   FUNCTION_INST_RET_VOID_ABBREV,
119   FUNCTION_INST_RET_VAL_ABBREV,
120   FUNCTION_INST_UNREACHABLE_ABBREV,
121   FUNCTION_INST_GEP_ABBREV,
122 };
123 
124 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
125 /// file type.
126 class BitcodeWriterBase {
127 protected:
128   /// The stream created and owned by the client.
129   BitstreamWriter &Stream;
130 
131   StringTableBuilder &StrtabBuilder;
132 
133 public:
134   /// Constructs a BitcodeWriterBase object that writes to the provided
135   /// \p Stream.
136   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
137       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
138 
139 protected:
140   void writeBitcodeHeader();
141   void writeModuleVersion();
142 };
143 
144 void BitcodeWriterBase::writeModuleVersion() {
145   // VERSION: [version#]
146   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
147 }
148 
149 /// Base class to manage the module bitcode writing, currently subclassed for
150 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
151 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
152 protected:
153   /// The Module to write to bitcode.
154   const Module &M;
155 
156   /// Enumerates ids for all values in the module.
157   ValueEnumerator VE;
158 
159   /// Optional per-module index to write for ThinLTO.
160   const ModuleSummaryIndex *Index;
161 
162   /// Map that holds the correspondence between GUIDs in the summary index,
163   /// that came from indirect call profiles, and a value id generated by this
164   /// class to use in the VST and summary block records.
165   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
166 
167   /// Tracks the last value id recorded in the GUIDToValueMap.
168   unsigned GlobalValueId;
169 
170   /// Saves the offset of the VSTOffset record that must eventually be
171   /// backpatched with the offset of the actual VST.
172   uint64_t VSTOffsetPlaceholder = 0;
173 
174 public:
175   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
176   /// writing to the provided \p Buffer.
177   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
178                           BitstreamWriter &Stream,
179                           bool ShouldPreserveUseListOrder,
180                           const ModuleSummaryIndex *Index)
181       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
182         VE(M, ShouldPreserveUseListOrder), Index(Index) {
183     // Assign ValueIds to any callee values in the index that came from
184     // indirect call profiles and were recorded as a GUID not a Value*
185     // (which would have been assigned an ID by the ValueEnumerator).
186     // The starting ValueId is just after the number of values in the
187     // ValueEnumerator, so that they can be emitted in the VST.
188     GlobalValueId = VE.getValues().size();
189     if (!Index)
190       return;
191     for (const auto &GUIDSummaryLists : *Index)
192       // Examine all summaries for this GUID.
193       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
194         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
195           // For each call in the function summary, see if the call
196           // is to a GUID (which means it is for an indirect call,
197           // otherwise we would have a Value for it). If so, synthesize
198           // a value id.
199           for (auto &CallEdge : FS->calls())
200             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
201               assignValueId(CallEdge.first.getGUID());
202   }
203 
204 protected:
205   void writePerModuleGlobalValueSummary();
206 
207 private:
208   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
209                                            GlobalValueSummary *Summary,
210                                            unsigned ValueID,
211                                            unsigned FSCallsAbbrev,
212                                            unsigned FSCallsProfileAbbrev,
213                                            const Function &F);
214   void writeModuleLevelReferences(const GlobalVariable &V,
215                                   SmallVector<uint64_t, 64> &NameVals,
216                                   unsigned FSModRefsAbbrev);
217 
218   void assignValueId(GlobalValue::GUID ValGUID) {
219     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
220   }
221 
222   unsigned getValueId(GlobalValue::GUID ValGUID) {
223     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
224     // Expect that any GUID value had a value Id assigned by an
225     // earlier call to assignValueId.
226     assert(VMI != GUIDToValueIdMap.end() &&
227            "GUID does not have assigned value Id");
228     return VMI->second;
229   }
230 
231   // Helper to get the valueId for the type of value recorded in VI.
232   unsigned getValueId(ValueInfo VI) {
233     if (!VI.haveGVs() || !VI.getValue())
234       return getValueId(VI.getGUID());
235     return VE.getValueID(VI.getValue());
236   }
237 
238   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
239 };
240 
241 /// Class to manage the bitcode writing for a module.
242 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
243   /// Pointer to the buffer allocated by caller for bitcode writing.
244   const SmallVectorImpl<char> &Buffer;
245 
246   /// True if a module hash record should be written.
247   bool GenerateHash;
248 
249   /// If non-null, when GenerateHash is true, the resulting hash is written
250   /// into ModHash.
251   ModuleHash *ModHash;
252 
253   SHA1 Hasher;
254 
255   /// The start bit of the identification block.
256   uint64_t BitcodeStartBit;
257 
258 public:
259   /// Constructs a ModuleBitcodeWriter object for the given Module,
260   /// writing to the provided \p Buffer.
261   ModuleBitcodeWriter(const Module &M, SmallVectorImpl<char> &Buffer,
262                       StringTableBuilder &StrtabBuilder,
263                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
264                       const ModuleSummaryIndex *Index, bool GenerateHash,
265                       ModuleHash *ModHash = nullptr)
266       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
267                                 ShouldPreserveUseListOrder, Index),
268         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
269         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
270 
271   /// Emit the current module to the bitstream.
272   void write();
273 
274 private:
275   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
276 
277   size_t addToStrtab(StringRef Str);
278 
279   void writeAttributeGroupTable();
280   void writeAttributeTable();
281   void writeTypeTable();
282   void writeComdats();
283   void writeValueSymbolTableForwardDecl();
284   void writeModuleInfo();
285   void writeValueAsMetadata(const ValueAsMetadata *MD,
286                             SmallVectorImpl<uint64_t> &Record);
287   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
288                     unsigned Abbrev);
289   unsigned createDILocationAbbrev();
290   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
291                        unsigned &Abbrev);
292   unsigned createGenericDINodeAbbrev();
293   void writeGenericDINode(const GenericDINode *N,
294                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
295   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
296                        unsigned Abbrev);
297   void writeDIEnumerator(const DIEnumerator *N,
298                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
299   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
300                         unsigned Abbrev);
301   void writeDIDerivedType(const DIDerivedType *N,
302                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
303   void writeDICompositeType(const DICompositeType *N,
304                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
305   void writeDISubroutineType(const DISubroutineType *N,
306                              SmallVectorImpl<uint64_t> &Record,
307                              unsigned Abbrev);
308   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
309                    unsigned Abbrev);
310   void writeDICompileUnit(const DICompileUnit *N,
311                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
312   void writeDISubprogram(const DISubprogram *N,
313                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
314   void writeDILexicalBlock(const DILexicalBlock *N,
315                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
316   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
317                                SmallVectorImpl<uint64_t> &Record,
318                                unsigned Abbrev);
319   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
320                         unsigned Abbrev);
321   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
322                     unsigned Abbrev);
323   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
324                         unsigned Abbrev);
325   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
326                      unsigned Abbrev);
327   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
328                                     SmallVectorImpl<uint64_t> &Record,
329                                     unsigned Abbrev);
330   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
331                                      SmallVectorImpl<uint64_t> &Record,
332                                      unsigned Abbrev);
333   void writeDIGlobalVariable(const DIGlobalVariable *N,
334                              SmallVectorImpl<uint64_t> &Record,
335                              unsigned Abbrev);
336   void writeDILocalVariable(const DILocalVariable *N,
337                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
338   void writeDILabel(const DILabel *N,
339                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
340   void writeDIExpression(const DIExpression *N,
341                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
342   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
343                                        SmallVectorImpl<uint64_t> &Record,
344                                        unsigned Abbrev);
345   void writeDIObjCProperty(const DIObjCProperty *N,
346                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
347   void writeDIImportedEntity(const DIImportedEntity *N,
348                              SmallVectorImpl<uint64_t> &Record,
349                              unsigned Abbrev);
350   unsigned createNamedMetadataAbbrev();
351   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
352   unsigned createMetadataStringsAbbrev();
353   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
354                             SmallVectorImpl<uint64_t> &Record);
355   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
356                             SmallVectorImpl<uint64_t> &Record,
357                             std::vector<unsigned> *MDAbbrevs = nullptr,
358                             std::vector<uint64_t> *IndexPos = nullptr);
359   void writeModuleMetadata();
360   void writeFunctionMetadata(const Function &F);
361   void writeFunctionMetadataAttachment(const Function &F);
362   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
363   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
364                                     const GlobalObject &GO);
365   void writeModuleMetadataKinds();
366   void writeOperandBundleTags();
367   void writeSyncScopeNames();
368   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
369   void writeModuleConstants();
370   bool pushValueAndType(const Value *V, unsigned InstID,
371                         SmallVectorImpl<unsigned> &Vals);
372   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
373   void pushValue(const Value *V, unsigned InstID,
374                  SmallVectorImpl<unsigned> &Vals);
375   void pushValueSigned(const Value *V, unsigned InstID,
376                        SmallVectorImpl<uint64_t> &Vals);
377   void writeInstruction(const Instruction &I, unsigned InstID,
378                         SmallVectorImpl<unsigned> &Vals);
379   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
380   void writeGlobalValueSymbolTable(
381       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
382   void writeUseList(UseListOrder &&Order);
383   void writeUseListBlock(const Function *F);
384   void
385   writeFunction(const Function &F,
386                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
387   void writeBlockInfo();
388   void writeModuleHash(size_t BlockStartPos);
389 
390   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
391     return unsigned(SSID);
392   }
393 };
394 
395 /// Class to manage the bitcode writing for a combined index.
396 class IndexBitcodeWriter : public BitcodeWriterBase {
397   /// The combined index to write to bitcode.
398   const ModuleSummaryIndex &Index;
399 
400   /// When writing a subset of the index for distributed backends, client
401   /// provides a map of modules to the corresponding GUIDs/summaries to write.
402   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
403 
404   /// Map that holds the correspondence between the GUID used in the combined
405   /// index and a value id generated by this class to use in references.
406   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
407 
408   /// Tracks the last value id recorded in the GUIDToValueMap.
409   unsigned GlobalValueId = 0;
410 
411 public:
412   /// Constructs a IndexBitcodeWriter object for the given combined index,
413   /// writing to the provided \p Buffer. When writing a subset of the index
414   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
415   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
416                      const ModuleSummaryIndex &Index,
417                      const std::map<std::string, GVSummaryMapTy>
418                          *ModuleToSummariesForIndex = nullptr)
419       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
420         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
421     // Assign unique value ids to all summaries to be written, for use
422     // in writing out the call graph edges. Save the mapping from GUID
423     // to the new global value id to use when writing those edges, which
424     // are currently saved in the index in terms of GUID.
425     forEachSummary([&](GVInfo I, bool) {
426       GUIDToValueIdMap[I.first] = ++GlobalValueId;
427     });
428   }
429 
430   /// The below iterator returns the GUID and associated summary.
431   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
432 
433   /// Calls the callback for each value GUID and summary to be written to
434   /// bitcode. This hides the details of whether they are being pulled from the
435   /// entire index or just those in a provided ModuleToSummariesForIndex map.
436   template<typename Functor>
437   void forEachSummary(Functor Callback) {
438     if (ModuleToSummariesForIndex) {
439       for (auto &M : *ModuleToSummariesForIndex)
440         for (auto &Summary : M.second) {
441           Callback(Summary, false);
442           // Ensure aliasee is handled, e.g. for assigning a valueId,
443           // even if we are not importing the aliasee directly (the
444           // imported alias will contain a copy of aliasee).
445           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
446             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
447         }
448     } else {
449       for (auto &Summaries : Index)
450         for (auto &Summary : Summaries.second.SummaryList)
451           Callback({Summaries.first, Summary.get()}, false);
452     }
453   }
454 
455   /// Calls the callback for each entry in the modulePaths StringMap that
456   /// should be written to the module path string table. This hides the details
457   /// of whether they are being pulled from the entire index or just those in a
458   /// provided ModuleToSummariesForIndex map.
459   template <typename Functor> void forEachModule(Functor Callback) {
460     if (ModuleToSummariesForIndex) {
461       for (const auto &M : *ModuleToSummariesForIndex) {
462         const auto &MPI = Index.modulePaths().find(M.first);
463         if (MPI == Index.modulePaths().end()) {
464           // This should only happen if the bitcode file was empty, in which
465           // case we shouldn't be importing (the ModuleToSummariesForIndex
466           // would only include the module we are writing and index for).
467           assert(ModuleToSummariesForIndex->size() == 1);
468           continue;
469         }
470         Callback(*MPI);
471       }
472     } else {
473       for (const auto &MPSE : Index.modulePaths())
474         Callback(MPSE);
475     }
476   }
477 
478   /// Main entry point for writing a combined index to bitcode.
479   void write();
480 
481 private:
482   void writeModStrings();
483   void writeCombinedGlobalValueSummary();
484 
485   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
486     auto VMI = GUIDToValueIdMap.find(ValGUID);
487     if (VMI == GUIDToValueIdMap.end())
488       return None;
489     return VMI->second;
490   }
491 
492   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
493 };
494 
495 } // end anonymous namespace
496 
497 static unsigned getEncodedCastOpcode(unsigned Opcode) {
498   switch (Opcode) {
499   default: llvm_unreachable("Unknown cast instruction!");
500   case Instruction::Trunc   : return bitc::CAST_TRUNC;
501   case Instruction::ZExt    : return bitc::CAST_ZEXT;
502   case Instruction::SExt    : return bitc::CAST_SEXT;
503   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
504   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
505   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
506   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
507   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
508   case Instruction::FPExt   : return bitc::CAST_FPEXT;
509   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
510   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
511   case Instruction::BitCast : return bitc::CAST_BITCAST;
512   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
513   }
514 }
515 
516 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
517   switch (Opcode) {
518   default: llvm_unreachable("Unknown binary instruction!");
519   case Instruction::Add:
520   case Instruction::FAdd: return bitc::BINOP_ADD;
521   case Instruction::Sub:
522   case Instruction::FSub: return bitc::BINOP_SUB;
523   case Instruction::Mul:
524   case Instruction::FMul: return bitc::BINOP_MUL;
525   case Instruction::UDiv: return bitc::BINOP_UDIV;
526   case Instruction::FDiv:
527   case Instruction::SDiv: return bitc::BINOP_SDIV;
528   case Instruction::URem: return bitc::BINOP_UREM;
529   case Instruction::FRem:
530   case Instruction::SRem: return bitc::BINOP_SREM;
531   case Instruction::Shl:  return bitc::BINOP_SHL;
532   case Instruction::LShr: return bitc::BINOP_LSHR;
533   case Instruction::AShr: return bitc::BINOP_ASHR;
534   case Instruction::And:  return bitc::BINOP_AND;
535   case Instruction::Or:   return bitc::BINOP_OR;
536   case Instruction::Xor:  return bitc::BINOP_XOR;
537   }
538 }
539 
540 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
541   switch (Op) {
542   default: llvm_unreachable("Unknown RMW operation!");
543   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
544   case AtomicRMWInst::Add: return bitc::RMW_ADD;
545   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
546   case AtomicRMWInst::And: return bitc::RMW_AND;
547   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
548   case AtomicRMWInst::Or: return bitc::RMW_OR;
549   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
550   case AtomicRMWInst::Max: return bitc::RMW_MAX;
551   case AtomicRMWInst::Min: return bitc::RMW_MIN;
552   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
553   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
554   }
555 }
556 
557 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
558   switch (Ordering) {
559   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
560   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
561   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
562   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
563   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
564   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
565   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
566   }
567   llvm_unreachable("Invalid ordering");
568 }
569 
570 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
571                               StringRef Str, unsigned AbbrevToUse) {
572   SmallVector<unsigned, 64> Vals;
573 
574   // Code: [strchar x N]
575   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
576     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
577       AbbrevToUse = 0;
578     Vals.push_back(Str[i]);
579   }
580 
581   // Emit the finished record.
582   Stream.EmitRecord(Code, Vals, AbbrevToUse);
583 }
584 
585 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
586   switch (Kind) {
587   case Attribute::Alignment:
588     return bitc::ATTR_KIND_ALIGNMENT;
589   case Attribute::AllocSize:
590     return bitc::ATTR_KIND_ALLOC_SIZE;
591   case Attribute::AlwaysInline:
592     return bitc::ATTR_KIND_ALWAYS_INLINE;
593   case Attribute::ArgMemOnly:
594     return bitc::ATTR_KIND_ARGMEMONLY;
595   case Attribute::Builtin:
596     return bitc::ATTR_KIND_BUILTIN;
597   case Attribute::ByVal:
598     return bitc::ATTR_KIND_BY_VAL;
599   case Attribute::Convergent:
600     return bitc::ATTR_KIND_CONVERGENT;
601   case Attribute::InAlloca:
602     return bitc::ATTR_KIND_IN_ALLOCA;
603   case Attribute::Cold:
604     return bitc::ATTR_KIND_COLD;
605   case Attribute::InaccessibleMemOnly:
606     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
607   case Attribute::InaccessibleMemOrArgMemOnly:
608     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
609   case Attribute::InlineHint:
610     return bitc::ATTR_KIND_INLINE_HINT;
611   case Attribute::InReg:
612     return bitc::ATTR_KIND_IN_REG;
613   case Attribute::JumpTable:
614     return bitc::ATTR_KIND_JUMP_TABLE;
615   case Attribute::MinSize:
616     return bitc::ATTR_KIND_MIN_SIZE;
617   case Attribute::Naked:
618     return bitc::ATTR_KIND_NAKED;
619   case Attribute::Nest:
620     return bitc::ATTR_KIND_NEST;
621   case Attribute::NoAlias:
622     return bitc::ATTR_KIND_NO_ALIAS;
623   case Attribute::NoBuiltin:
624     return bitc::ATTR_KIND_NO_BUILTIN;
625   case Attribute::NoCapture:
626     return bitc::ATTR_KIND_NO_CAPTURE;
627   case Attribute::NoDuplicate:
628     return bitc::ATTR_KIND_NO_DUPLICATE;
629   case Attribute::NoImplicitFloat:
630     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
631   case Attribute::NoInline:
632     return bitc::ATTR_KIND_NO_INLINE;
633   case Attribute::NoRecurse:
634     return bitc::ATTR_KIND_NO_RECURSE;
635   case Attribute::NonLazyBind:
636     return bitc::ATTR_KIND_NON_LAZY_BIND;
637   case Attribute::NonNull:
638     return bitc::ATTR_KIND_NON_NULL;
639   case Attribute::Dereferenceable:
640     return bitc::ATTR_KIND_DEREFERENCEABLE;
641   case Attribute::DereferenceableOrNull:
642     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
643   case Attribute::NoRedZone:
644     return bitc::ATTR_KIND_NO_RED_ZONE;
645   case Attribute::NoReturn:
646     return bitc::ATTR_KIND_NO_RETURN;
647   case Attribute::NoCfCheck:
648     return bitc::ATTR_KIND_NOCF_CHECK;
649   case Attribute::NoUnwind:
650     return bitc::ATTR_KIND_NO_UNWIND;
651   case Attribute::OptForFuzzing:
652     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
653   case Attribute::OptimizeForSize:
654     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
655   case Attribute::OptimizeNone:
656     return bitc::ATTR_KIND_OPTIMIZE_NONE;
657   case Attribute::ReadNone:
658     return bitc::ATTR_KIND_READ_NONE;
659   case Attribute::ReadOnly:
660     return bitc::ATTR_KIND_READ_ONLY;
661   case Attribute::Returned:
662     return bitc::ATTR_KIND_RETURNED;
663   case Attribute::ReturnsTwice:
664     return bitc::ATTR_KIND_RETURNS_TWICE;
665   case Attribute::SExt:
666     return bitc::ATTR_KIND_S_EXT;
667   case Attribute::Speculatable:
668     return bitc::ATTR_KIND_SPECULATABLE;
669   case Attribute::StackAlignment:
670     return bitc::ATTR_KIND_STACK_ALIGNMENT;
671   case Attribute::StackProtect:
672     return bitc::ATTR_KIND_STACK_PROTECT;
673   case Attribute::StackProtectReq:
674     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
675   case Attribute::StackProtectStrong:
676     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
677   case Attribute::SafeStack:
678     return bitc::ATTR_KIND_SAFESTACK;
679   case Attribute::ShadowCallStack:
680     return bitc::ATTR_KIND_SHADOWCALLSTACK;
681   case Attribute::StrictFP:
682     return bitc::ATTR_KIND_STRICT_FP;
683   case Attribute::StructRet:
684     return bitc::ATTR_KIND_STRUCT_RET;
685   case Attribute::SanitizeAddress:
686     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
687   case Attribute::SanitizeHWAddress:
688     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
689   case Attribute::SanitizeThread:
690     return bitc::ATTR_KIND_SANITIZE_THREAD;
691   case Attribute::SanitizeMemory:
692     return bitc::ATTR_KIND_SANITIZE_MEMORY;
693   case Attribute::SwiftError:
694     return bitc::ATTR_KIND_SWIFT_ERROR;
695   case Attribute::SwiftSelf:
696     return bitc::ATTR_KIND_SWIFT_SELF;
697   case Attribute::UWTable:
698     return bitc::ATTR_KIND_UW_TABLE;
699   case Attribute::WriteOnly:
700     return bitc::ATTR_KIND_WRITEONLY;
701   case Attribute::ZExt:
702     return bitc::ATTR_KIND_Z_EXT;
703   case Attribute::EndAttrKinds:
704     llvm_unreachable("Can not encode end-attribute kinds marker.");
705   case Attribute::None:
706     llvm_unreachable("Can not encode none-attribute.");
707   }
708 
709   llvm_unreachable("Trying to encode unknown attribute");
710 }
711 
712 void ModuleBitcodeWriter::writeAttributeGroupTable() {
713   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
714       VE.getAttributeGroups();
715   if (AttrGrps.empty()) return;
716 
717   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
718 
719   SmallVector<uint64_t, 64> Record;
720   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
721     unsigned AttrListIndex = Pair.first;
722     AttributeSet AS = Pair.second;
723     Record.push_back(VE.getAttributeGroupID(Pair));
724     Record.push_back(AttrListIndex);
725 
726     for (Attribute Attr : AS) {
727       if (Attr.isEnumAttribute()) {
728         Record.push_back(0);
729         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
730       } else if (Attr.isIntAttribute()) {
731         Record.push_back(1);
732         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
733         Record.push_back(Attr.getValueAsInt());
734       } else {
735         StringRef Kind = Attr.getKindAsString();
736         StringRef Val = Attr.getValueAsString();
737 
738         Record.push_back(Val.empty() ? 3 : 4);
739         Record.append(Kind.begin(), Kind.end());
740         Record.push_back(0);
741         if (!Val.empty()) {
742           Record.append(Val.begin(), Val.end());
743           Record.push_back(0);
744         }
745       }
746     }
747 
748     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
749     Record.clear();
750   }
751 
752   Stream.ExitBlock();
753 }
754 
755 void ModuleBitcodeWriter::writeAttributeTable() {
756   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
757   if (Attrs.empty()) return;
758 
759   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
760 
761   SmallVector<uint64_t, 64> Record;
762   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
763     AttributeList AL = Attrs[i];
764     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
765       AttributeSet AS = AL.getAttributes(i);
766       if (AS.hasAttributes())
767         Record.push_back(VE.getAttributeGroupID({i, AS}));
768     }
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   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
800 
801   // Abbrev for TYPE_CODE_STRUCT_ANON.
802   Abbv = std::make_shared<BitCodeAbbrev>();
803   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
804   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
805   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
806   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
807   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
808 
809   // Abbrev for TYPE_CODE_STRUCT_NAME.
810   Abbv = std::make_shared<BitCodeAbbrev>();
811   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
812   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
813   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
814   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
815 
816   // Abbrev for TYPE_CODE_STRUCT_NAMED.
817   Abbv = std::make_shared<BitCodeAbbrev>();
818   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
819   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
820   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
822   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
823 
824   // Abbrev for TYPE_CODE_ARRAY.
825   Abbv = std::make_shared<BitCodeAbbrev>();
826   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
827   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
828   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
829   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
830 
831   // Emit an entry count so the reader can reserve space.
832   TypeVals.push_back(TypeList.size());
833   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
834   TypeVals.clear();
835 
836   // Loop over all of the types, emitting each in turn.
837   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
838     Type *T = TypeList[i];
839     int AbbrevToUse = 0;
840     unsigned Code = 0;
841 
842     switch (T->getTypeID()) {
843     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
844     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
845     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
846     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
847     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
848     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
849     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
850     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
851     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
852     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
853     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
854     case Type::IntegerTyID:
855       // INTEGER: [width]
856       Code = bitc::TYPE_CODE_INTEGER;
857       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
858       break;
859     case Type::PointerTyID: {
860       PointerType *PTy = cast<PointerType>(T);
861       // POINTER: [pointee type, address space]
862       Code = bitc::TYPE_CODE_POINTER;
863       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
864       unsigned AddressSpace = PTy->getAddressSpace();
865       TypeVals.push_back(AddressSpace);
866       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
867       break;
868     }
869     case Type::FunctionTyID: {
870       FunctionType *FT = cast<FunctionType>(T);
871       // FUNCTION: [isvararg, retty, paramty x N]
872       Code = bitc::TYPE_CODE_FUNCTION;
873       TypeVals.push_back(FT->isVarArg());
874       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
875       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
876         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
877       AbbrevToUse = FunctionAbbrev;
878       break;
879     }
880     case Type::StructTyID: {
881       StructType *ST = cast<StructType>(T);
882       // STRUCT: [ispacked, eltty x N]
883       TypeVals.push_back(ST->isPacked());
884       // Output all of the element types.
885       for (StructType::element_iterator I = ST->element_begin(),
886            E = ST->element_end(); I != E; ++I)
887         TypeVals.push_back(VE.getTypeID(*I));
888 
889       if (ST->isLiteral()) {
890         Code = bitc::TYPE_CODE_STRUCT_ANON;
891         AbbrevToUse = StructAnonAbbrev;
892       } else {
893         if (ST->isOpaque()) {
894           Code = bitc::TYPE_CODE_OPAQUE;
895         } else {
896           Code = bitc::TYPE_CODE_STRUCT_NAMED;
897           AbbrevToUse = StructNamedAbbrev;
898         }
899 
900         // Emit the name if it is present.
901         if (!ST->getName().empty())
902           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
903                             StructNameAbbrev);
904       }
905       break;
906     }
907     case Type::ArrayTyID: {
908       ArrayType *AT = cast<ArrayType>(T);
909       // ARRAY: [numelts, eltty]
910       Code = bitc::TYPE_CODE_ARRAY;
911       TypeVals.push_back(AT->getNumElements());
912       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
913       AbbrevToUse = ArrayAbbrev;
914       break;
915     }
916     case Type::VectorTyID: {
917       VectorType *VT = cast<VectorType>(T);
918       // VECTOR [numelts, eltty]
919       Code = bitc::TYPE_CODE_VECTOR;
920       TypeVals.push_back(VT->getNumElements());
921       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
922       break;
923     }
924     }
925 
926     // Emit the finished record.
927     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
928     TypeVals.clear();
929   }
930 
931   Stream.ExitBlock();
932 }
933 
934 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
935   switch (Linkage) {
936   case GlobalValue::ExternalLinkage:
937     return 0;
938   case GlobalValue::WeakAnyLinkage:
939     return 16;
940   case GlobalValue::AppendingLinkage:
941     return 2;
942   case GlobalValue::InternalLinkage:
943     return 3;
944   case GlobalValue::LinkOnceAnyLinkage:
945     return 18;
946   case GlobalValue::ExternalWeakLinkage:
947     return 7;
948   case GlobalValue::CommonLinkage:
949     return 8;
950   case GlobalValue::PrivateLinkage:
951     return 9;
952   case GlobalValue::WeakODRLinkage:
953     return 17;
954   case GlobalValue::LinkOnceODRLinkage:
955     return 19;
956   case GlobalValue::AvailableExternallyLinkage:
957     return 12;
958   }
959   llvm_unreachable("Invalid linkage");
960 }
961 
962 static unsigned getEncodedLinkage(const GlobalValue &GV) {
963   return getEncodedLinkage(GV.getLinkage());
964 }
965 
966 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
967   uint64_t RawFlags = 0;
968   RawFlags |= Flags.ReadNone;
969   RawFlags |= (Flags.ReadOnly << 1);
970   RawFlags |= (Flags.NoRecurse << 2);
971   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
972   return RawFlags;
973 }
974 
975 // Decode the flags for GlobalValue in the summary
976 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
977   uint64_t RawFlags = 0;
978 
979   RawFlags |= Flags.NotEligibleToImport; // bool
980   RawFlags |= (Flags.Live << 1);
981   RawFlags |= (Flags.DSOLocal << 2);
982 
983   // Linkage don't need to be remapped at that time for the summary. Any future
984   // change to the getEncodedLinkage() function will need to be taken into
985   // account here as well.
986   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
987 
988   return RawFlags;
989 }
990 
991 static unsigned getEncodedVisibility(const GlobalValue &GV) {
992   switch (GV.getVisibility()) {
993   case GlobalValue::DefaultVisibility:   return 0;
994   case GlobalValue::HiddenVisibility:    return 1;
995   case GlobalValue::ProtectedVisibility: return 2;
996   }
997   llvm_unreachable("Invalid visibility");
998 }
999 
1000 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1001   switch (GV.getDLLStorageClass()) {
1002   case GlobalValue::DefaultStorageClass:   return 0;
1003   case GlobalValue::DLLImportStorageClass: return 1;
1004   case GlobalValue::DLLExportStorageClass: return 2;
1005   }
1006   llvm_unreachable("Invalid DLL storage class");
1007 }
1008 
1009 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1010   switch (GV.getThreadLocalMode()) {
1011     case GlobalVariable::NotThreadLocal:         return 0;
1012     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1013     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1014     case GlobalVariable::InitialExecTLSModel:    return 3;
1015     case GlobalVariable::LocalExecTLSModel:      return 4;
1016   }
1017   llvm_unreachable("Invalid TLS model");
1018 }
1019 
1020 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1021   switch (C.getSelectionKind()) {
1022   case Comdat::Any:
1023     return bitc::COMDAT_SELECTION_KIND_ANY;
1024   case Comdat::ExactMatch:
1025     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1026   case Comdat::Largest:
1027     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1028   case Comdat::NoDuplicates:
1029     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1030   case Comdat::SameSize:
1031     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1032   }
1033   llvm_unreachable("Invalid selection kind");
1034 }
1035 
1036 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1037   switch (GV.getUnnamedAddr()) {
1038   case GlobalValue::UnnamedAddr::None:   return 0;
1039   case GlobalValue::UnnamedAddr::Local:  return 2;
1040   case GlobalValue::UnnamedAddr::Global: return 1;
1041   }
1042   llvm_unreachable("Invalid unnamed_addr");
1043 }
1044 
1045 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1046   if (GenerateHash)
1047     Hasher.update(Str);
1048   return StrtabBuilder.add(Str);
1049 }
1050 
1051 void ModuleBitcodeWriter::writeComdats() {
1052   SmallVector<unsigned, 64> Vals;
1053   for (const Comdat *C : VE.getComdats()) {
1054     // COMDAT: [strtab offset, strtab size, selection_kind]
1055     Vals.push_back(addToStrtab(C->getName()));
1056     Vals.push_back(C->getName().size());
1057     Vals.push_back(getEncodedComdatSelectionKind(*C));
1058     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1059     Vals.clear();
1060   }
1061 }
1062 
1063 /// Write a record that will eventually hold the word offset of the
1064 /// module-level VST. For now the offset is 0, which will be backpatched
1065 /// after the real VST is written. Saves the bit offset to backpatch.
1066 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1067   // Write a placeholder value in for the offset of the real VST,
1068   // which is written after the function blocks so that it can include
1069   // the offset of each function. The placeholder offset will be
1070   // updated when the real VST is written.
1071   auto Abbv = std::make_shared<BitCodeAbbrev>();
1072   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1073   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1074   // hold the real VST offset. Must use fixed instead of VBR as we don't
1075   // know how many VBR chunks to reserve ahead of time.
1076   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1077   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1078 
1079   // Emit the placeholder
1080   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1081   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1082 
1083   // Compute and save the bit offset to the placeholder, which will be
1084   // patched when the real VST is written. We can simply subtract the 32-bit
1085   // fixed size from the current bit number to get the location to backpatch.
1086   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1087 }
1088 
1089 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1090 
1091 /// Determine the encoding to use for the given string name and length.
1092 static StringEncoding getStringEncoding(StringRef Str) {
1093   bool isChar6 = true;
1094   for (char C : Str) {
1095     if (isChar6)
1096       isChar6 = BitCodeAbbrevOp::isChar6(C);
1097     if ((unsigned char)C & 128)
1098       // don't bother scanning the rest.
1099       return SE_Fixed8;
1100   }
1101   if (isChar6)
1102     return SE_Char6;
1103   return SE_Fixed7;
1104 }
1105 
1106 /// Emit top-level description of module, including target triple, inline asm,
1107 /// descriptors for global variables, and function prototype info.
1108 /// Returns the bit offset to backpatch with the location of the real VST.
1109 void ModuleBitcodeWriter::writeModuleInfo() {
1110   // Emit various pieces of data attached to a module.
1111   if (!M.getTargetTriple().empty())
1112     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1113                       0 /*TODO*/);
1114   const std::string &DL = M.getDataLayoutStr();
1115   if (!DL.empty())
1116     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1117   if (!M.getModuleInlineAsm().empty())
1118     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1119                       0 /*TODO*/);
1120 
1121   // Emit information about sections and GC, computing how many there are. Also
1122   // compute the maximum alignment value.
1123   std::map<std::string, unsigned> SectionMap;
1124   std::map<std::string, unsigned> GCMap;
1125   unsigned MaxAlignment = 0;
1126   unsigned MaxGlobalType = 0;
1127   for (const GlobalValue &GV : M.globals()) {
1128     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1129     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1130     if (GV.hasSection()) {
1131       // Give section names unique ID's.
1132       unsigned &Entry = SectionMap[GV.getSection()];
1133       if (!Entry) {
1134         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1135                           0 /*TODO*/);
1136         Entry = SectionMap.size();
1137       }
1138     }
1139   }
1140   for (const Function &F : M) {
1141     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1142     if (F.hasSection()) {
1143       // Give section names unique ID's.
1144       unsigned &Entry = SectionMap[F.getSection()];
1145       if (!Entry) {
1146         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1147                           0 /*TODO*/);
1148         Entry = SectionMap.size();
1149       }
1150     }
1151     if (F.hasGC()) {
1152       // Same for GC names.
1153       unsigned &Entry = GCMap[F.getGC()];
1154       if (!Entry) {
1155         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1156                           0 /*TODO*/);
1157         Entry = GCMap.size();
1158       }
1159     }
1160   }
1161 
1162   // Emit abbrev for globals, now that we know # sections and max alignment.
1163   unsigned SimpleGVarAbbrev = 0;
1164   if (!M.global_empty()) {
1165     // Add an abbrev for common globals with no visibility or thread localness.
1166     auto Abbv = std::make_shared<BitCodeAbbrev>();
1167     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1168     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1169     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1170     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1171                               Log2_32_Ceil(MaxGlobalType+1)));
1172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1173                                                            //| explicitType << 1
1174                                                            //| constant
1175     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1177     if (MaxAlignment == 0)                                 // Alignment.
1178       Abbv->Add(BitCodeAbbrevOp(0));
1179     else {
1180       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1181       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1182                                Log2_32_Ceil(MaxEncAlignment+1)));
1183     }
1184     if (SectionMap.empty())                                    // Section.
1185       Abbv->Add(BitCodeAbbrevOp(0));
1186     else
1187       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1188                                Log2_32_Ceil(SectionMap.size()+1)));
1189     // Don't bother emitting vis + thread local.
1190     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1191   }
1192 
1193   SmallVector<unsigned, 64> Vals;
1194   // Emit the module's source file name.
1195   {
1196     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1197     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1198     if (Bits == SE_Char6)
1199       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1200     else if (Bits == SE_Fixed7)
1201       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1202 
1203     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1204     auto Abbv = std::make_shared<BitCodeAbbrev>();
1205     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1206     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1207     Abbv->Add(AbbrevOpToUse);
1208     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1209 
1210     for (const auto P : M.getSourceFileName())
1211       Vals.push_back((unsigned char)P);
1212 
1213     // Emit the finished record.
1214     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1215     Vals.clear();
1216   }
1217 
1218   // Emit the global variable information.
1219   for (const GlobalVariable &GV : M.globals()) {
1220     unsigned AbbrevToUse = 0;
1221 
1222     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1223     //             linkage, alignment, section, visibility, threadlocal,
1224     //             unnamed_addr, externally_initialized, dllstorageclass,
1225     //             comdat, attributes, DSO_Local]
1226     Vals.push_back(addToStrtab(GV.getName()));
1227     Vals.push_back(GV.getName().size());
1228     Vals.push_back(VE.getTypeID(GV.getValueType()));
1229     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1230     Vals.push_back(GV.isDeclaration() ? 0 :
1231                    (VE.getValueID(GV.getInitializer()) + 1));
1232     Vals.push_back(getEncodedLinkage(GV));
1233     Vals.push_back(Log2_32(GV.getAlignment())+1);
1234     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1235     if (GV.isThreadLocal() ||
1236         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1237         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1238         GV.isExternallyInitialized() ||
1239         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1240         GV.hasComdat() ||
1241         GV.hasAttributes() ||
1242         GV.isDSOLocal()) {
1243       Vals.push_back(getEncodedVisibility(GV));
1244       Vals.push_back(getEncodedThreadLocalMode(GV));
1245       Vals.push_back(getEncodedUnnamedAddr(GV));
1246       Vals.push_back(GV.isExternallyInitialized());
1247       Vals.push_back(getEncodedDLLStorageClass(GV));
1248       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1249 
1250       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1251       Vals.push_back(VE.getAttributeListID(AL));
1252 
1253       Vals.push_back(GV.isDSOLocal());
1254     } else {
1255       AbbrevToUse = SimpleGVarAbbrev;
1256     }
1257 
1258     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1259     Vals.clear();
1260   }
1261 
1262   // Emit the function proto information.
1263   for (const Function &F : M) {
1264     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1265     //             linkage, paramattrs, alignment, section, visibility, gc,
1266     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1267     //             prefixdata, personalityfn, DSO_Local]
1268     Vals.push_back(addToStrtab(F.getName()));
1269     Vals.push_back(F.getName().size());
1270     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1271     Vals.push_back(F.getCallingConv());
1272     Vals.push_back(F.isDeclaration());
1273     Vals.push_back(getEncodedLinkage(F));
1274     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1275     Vals.push_back(Log2_32(F.getAlignment())+1);
1276     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1277     Vals.push_back(getEncodedVisibility(F));
1278     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1279     Vals.push_back(getEncodedUnnamedAddr(F));
1280     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1281                                        : 0);
1282     Vals.push_back(getEncodedDLLStorageClass(F));
1283     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1284     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1285                                      : 0);
1286     Vals.push_back(
1287         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1288 
1289     Vals.push_back(F.isDSOLocal());
1290     unsigned AbbrevToUse = 0;
1291     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1292     Vals.clear();
1293   }
1294 
1295   // Emit the alias information.
1296   for (const GlobalAlias &A : M.aliases()) {
1297     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1298     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1299     //         DSO_Local]
1300     Vals.push_back(addToStrtab(A.getName()));
1301     Vals.push_back(A.getName().size());
1302     Vals.push_back(VE.getTypeID(A.getValueType()));
1303     Vals.push_back(A.getType()->getAddressSpace());
1304     Vals.push_back(VE.getValueID(A.getAliasee()));
1305     Vals.push_back(getEncodedLinkage(A));
1306     Vals.push_back(getEncodedVisibility(A));
1307     Vals.push_back(getEncodedDLLStorageClass(A));
1308     Vals.push_back(getEncodedThreadLocalMode(A));
1309     Vals.push_back(getEncodedUnnamedAddr(A));
1310     Vals.push_back(A.isDSOLocal());
1311 
1312     unsigned AbbrevToUse = 0;
1313     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1314     Vals.clear();
1315   }
1316 
1317   // Emit the ifunc information.
1318   for (const GlobalIFunc &I : M.ifuncs()) {
1319     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1320     //         val#, linkage, visibility, DSO_Local]
1321     Vals.push_back(addToStrtab(I.getName()));
1322     Vals.push_back(I.getName().size());
1323     Vals.push_back(VE.getTypeID(I.getValueType()));
1324     Vals.push_back(I.getType()->getAddressSpace());
1325     Vals.push_back(VE.getValueID(I.getResolver()));
1326     Vals.push_back(getEncodedLinkage(I));
1327     Vals.push_back(getEncodedVisibility(I));
1328     Vals.push_back(I.isDSOLocal());
1329     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1330     Vals.clear();
1331   }
1332 
1333   writeValueSymbolTableForwardDecl();
1334 }
1335 
1336 static uint64_t getOptimizationFlags(const Value *V) {
1337   uint64_t Flags = 0;
1338 
1339   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1340     if (OBO->hasNoSignedWrap())
1341       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1342     if (OBO->hasNoUnsignedWrap())
1343       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1344   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1345     if (PEO->isExact())
1346       Flags |= 1 << bitc::PEO_EXACT;
1347   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1348     if (FPMO->hasAllowReassoc())
1349       Flags |= bitc::AllowReassoc;
1350     if (FPMO->hasNoNaNs())
1351       Flags |= bitc::NoNaNs;
1352     if (FPMO->hasNoInfs())
1353       Flags |= bitc::NoInfs;
1354     if (FPMO->hasNoSignedZeros())
1355       Flags |= bitc::NoSignedZeros;
1356     if (FPMO->hasAllowReciprocal())
1357       Flags |= bitc::AllowReciprocal;
1358     if (FPMO->hasAllowContract())
1359       Flags |= bitc::AllowContract;
1360     if (FPMO->hasApproxFunc())
1361       Flags |= bitc::ApproxFunc;
1362   }
1363 
1364   return Flags;
1365 }
1366 
1367 void ModuleBitcodeWriter::writeValueAsMetadata(
1368     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1369   // Mimic an MDNode with a value as one operand.
1370   Value *V = MD->getValue();
1371   Record.push_back(VE.getTypeID(V->getType()));
1372   Record.push_back(VE.getValueID(V));
1373   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1374   Record.clear();
1375 }
1376 
1377 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1378                                        SmallVectorImpl<uint64_t> &Record,
1379                                        unsigned Abbrev) {
1380   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1381     Metadata *MD = N->getOperand(i);
1382     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1383            "Unexpected function-local metadata");
1384     Record.push_back(VE.getMetadataOrNullID(MD));
1385   }
1386   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1387                                     : bitc::METADATA_NODE,
1388                     Record, Abbrev);
1389   Record.clear();
1390 }
1391 
1392 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1393   // Assume the column is usually under 128, and always output the inlined-at
1394   // location (it's never more expensive than building an array size 1).
1395   auto Abbv = std::make_shared<BitCodeAbbrev>();
1396   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1399   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1400   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1401   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1402   return Stream.EmitAbbrev(std::move(Abbv));
1403 }
1404 
1405 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1406                                           SmallVectorImpl<uint64_t> &Record,
1407                                           unsigned &Abbrev) {
1408   if (!Abbrev)
1409     Abbrev = createDILocationAbbrev();
1410 
1411   Record.push_back(N->isDistinct());
1412   Record.push_back(N->getLine());
1413   Record.push_back(N->getColumn());
1414   Record.push_back(VE.getMetadataID(N->getScope()));
1415   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1416 
1417   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1418   Record.clear();
1419 }
1420 
1421 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1422   // Assume the column is usually under 128, and always output the inlined-at
1423   // location (it's never more expensive than building an array size 1).
1424   auto Abbv = std::make_shared<BitCodeAbbrev>();
1425   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1426   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1427   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1428   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1429   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1430   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1431   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1432   return Stream.EmitAbbrev(std::move(Abbv));
1433 }
1434 
1435 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1436                                              SmallVectorImpl<uint64_t> &Record,
1437                                              unsigned &Abbrev) {
1438   if (!Abbrev)
1439     Abbrev = createGenericDINodeAbbrev();
1440 
1441   Record.push_back(N->isDistinct());
1442   Record.push_back(N->getTag());
1443   Record.push_back(0); // Per-tag version field; unused for now.
1444 
1445   for (auto &I : N->operands())
1446     Record.push_back(VE.getMetadataOrNullID(I));
1447 
1448   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1449   Record.clear();
1450 }
1451 
1452 static uint64_t rotateSign(int64_t I) {
1453   uint64_t U = I;
1454   return I < 0 ? ~(U << 1) : U << 1;
1455 }
1456 
1457 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1458                                           SmallVectorImpl<uint64_t> &Record,
1459                                           unsigned Abbrev) {
1460   const uint64_t Version = 1 << 1;
1461   Record.push_back((uint64_t)N->isDistinct() | Version);
1462   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1463   Record.push_back(rotateSign(N->getLowerBound()));
1464 
1465   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1466   Record.clear();
1467 }
1468 
1469 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1470                                             SmallVectorImpl<uint64_t> &Record,
1471                                             unsigned Abbrev) {
1472   Record.push_back((N->isUnsigned() << 1) | N->isDistinct());
1473   Record.push_back(rotateSign(N->getValue()));
1474   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1475 
1476   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1477   Record.clear();
1478 }
1479 
1480 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1481                                            SmallVectorImpl<uint64_t> &Record,
1482                                            unsigned Abbrev) {
1483   Record.push_back(N->isDistinct());
1484   Record.push_back(N->getTag());
1485   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1486   Record.push_back(N->getSizeInBits());
1487   Record.push_back(N->getAlignInBits());
1488   Record.push_back(N->getEncoding());
1489   Record.push_back(N->getFlags());
1490 
1491   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1492   Record.clear();
1493 }
1494 
1495 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1496                                              SmallVectorImpl<uint64_t> &Record,
1497                                              unsigned Abbrev) {
1498   Record.push_back(N->isDistinct());
1499   Record.push_back(N->getTag());
1500   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1501   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1502   Record.push_back(N->getLine());
1503   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1504   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1505   Record.push_back(N->getSizeInBits());
1506   Record.push_back(N->getAlignInBits());
1507   Record.push_back(N->getOffsetInBits());
1508   Record.push_back(N->getFlags());
1509   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1510 
1511   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1512   // that there is no DWARF address space associated with DIDerivedType.
1513   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1514     Record.push_back(*DWARFAddressSpace + 1);
1515   else
1516     Record.push_back(0);
1517 
1518   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1519   Record.clear();
1520 }
1521 
1522 void ModuleBitcodeWriter::writeDICompositeType(
1523     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1524     unsigned Abbrev) {
1525   const unsigned IsNotUsedInOldTypeRef = 0x2;
1526   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1527   Record.push_back(N->getTag());
1528   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1529   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1530   Record.push_back(N->getLine());
1531   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1532   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1533   Record.push_back(N->getSizeInBits());
1534   Record.push_back(N->getAlignInBits());
1535   Record.push_back(N->getOffsetInBits());
1536   Record.push_back(N->getFlags());
1537   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1538   Record.push_back(N->getRuntimeLang());
1539   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1540   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1541   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1542   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1543 
1544   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1545   Record.clear();
1546 }
1547 
1548 void ModuleBitcodeWriter::writeDISubroutineType(
1549     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1550     unsigned Abbrev) {
1551   const unsigned HasNoOldTypeRefs = 0x2;
1552   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1553   Record.push_back(N->getFlags());
1554   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1555   Record.push_back(N->getCC());
1556 
1557   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1558   Record.clear();
1559 }
1560 
1561 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1562                                       SmallVectorImpl<uint64_t> &Record,
1563                                       unsigned Abbrev) {
1564   Record.push_back(N->isDistinct());
1565   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1566   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1567   if (N->getRawChecksum()) {
1568     Record.push_back(N->getRawChecksum()->Kind);
1569     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1570   } else {
1571     // Maintain backwards compatibility with the old internal representation of
1572     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1573     Record.push_back(0);
1574     Record.push_back(VE.getMetadataOrNullID(nullptr));
1575   }
1576   auto Source = N->getRawSource();
1577   if (Source)
1578     Record.push_back(VE.getMetadataOrNullID(*Source));
1579 
1580   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1581   Record.clear();
1582 }
1583 
1584 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1585                                              SmallVectorImpl<uint64_t> &Record,
1586                                              unsigned Abbrev) {
1587   assert(N->isDistinct() && "Expected distinct compile units");
1588   Record.push_back(/* IsDistinct */ true);
1589   Record.push_back(N->getSourceLanguage());
1590   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1591   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1592   Record.push_back(N->isOptimized());
1593   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1594   Record.push_back(N->getRuntimeVersion());
1595   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1596   Record.push_back(N->getEmissionKind());
1597   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1598   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1599   Record.push_back(/* subprograms */ 0);
1600   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1601   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1602   Record.push_back(N->getDWOId());
1603   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1604   Record.push_back(N->getSplitDebugInlining());
1605   Record.push_back(N->getDebugInfoForProfiling());
1606   Record.push_back((unsigned)N->getNameTableKind());
1607 
1608   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1609   Record.clear();
1610 }
1611 
1612 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1613                                             SmallVectorImpl<uint64_t> &Record,
1614                                             unsigned Abbrev) {
1615   uint64_t HasUnitFlag = 1 << 1;
1616   Record.push_back(N->isDistinct() | HasUnitFlag);
1617   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1618   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1619   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1620   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1621   Record.push_back(N->getLine());
1622   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1623   Record.push_back(N->isLocalToUnit());
1624   Record.push_back(N->isDefinition());
1625   Record.push_back(N->getScopeLine());
1626   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1627   Record.push_back(N->getVirtuality());
1628   Record.push_back(N->getVirtualIndex());
1629   Record.push_back(N->getFlags());
1630   Record.push_back(N->isOptimized());
1631   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1632   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1633   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1634   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1635   Record.push_back(N->getThisAdjustment());
1636   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1637 
1638   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1639   Record.clear();
1640 }
1641 
1642 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1643                                               SmallVectorImpl<uint64_t> &Record,
1644                                               unsigned Abbrev) {
1645   Record.push_back(N->isDistinct());
1646   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1647   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1648   Record.push_back(N->getLine());
1649   Record.push_back(N->getColumn());
1650 
1651   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1652   Record.clear();
1653 }
1654 
1655 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1656     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1657     unsigned Abbrev) {
1658   Record.push_back(N->isDistinct());
1659   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1660   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1661   Record.push_back(N->getDiscriminator());
1662 
1663   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1664   Record.clear();
1665 }
1666 
1667 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1668                                            SmallVectorImpl<uint64_t> &Record,
1669                                            unsigned Abbrev) {
1670   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1671   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1672   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1673 
1674   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1675   Record.clear();
1676 }
1677 
1678 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1679                                        SmallVectorImpl<uint64_t> &Record,
1680                                        unsigned Abbrev) {
1681   Record.push_back(N->isDistinct());
1682   Record.push_back(N->getMacinfoType());
1683   Record.push_back(N->getLine());
1684   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1685   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1686 
1687   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1688   Record.clear();
1689 }
1690 
1691 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1692                                            SmallVectorImpl<uint64_t> &Record,
1693                                            unsigned Abbrev) {
1694   Record.push_back(N->isDistinct());
1695   Record.push_back(N->getMacinfoType());
1696   Record.push_back(N->getLine());
1697   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1698   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1699 
1700   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1701   Record.clear();
1702 }
1703 
1704 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1705                                         SmallVectorImpl<uint64_t> &Record,
1706                                         unsigned Abbrev) {
1707   Record.push_back(N->isDistinct());
1708   for (auto &I : N->operands())
1709     Record.push_back(VE.getMetadataOrNullID(I));
1710 
1711   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1712   Record.clear();
1713 }
1714 
1715 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1716     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1717     unsigned Abbrev) {
1718   Record.push_back(N->isDistinct());
1719   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1720   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1721 
1722   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1723   Record.clear();
1724 }
1725 
1726 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1727     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1728     unsigned Abbrev) {
1729   Record.push_back(N->isDistinct());
1730   Record.push_back(N->getTag());
1731   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1732   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1733   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1734 
1735   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1736   Record.clear();
1737 }
1738 
1739 void ModuleBitcodeWriter::writeDIGlobalVariable(
1740     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1741     unsigned Abbrev) {
1742   const uint64_t Version = 1 << 1;
1743   Record.push_back((uint64_t)N->isDistinct() | Version);
1744   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1745   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1746   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1747   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1748   Record.push_back(N->getLine());
1749   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1750   Record.push_back(N->isLocalToUnit());
1751   Record.push_back(N->isDefinition());
1752   Record.push_back(/* expr */ 0);
1753   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1754   Record.push_back(N->getAlignInBits());
1755 
1756   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1757   Record.clear();
1758 }
1759 
1760 void ModuleBitcodeWriter::writeDILocalVariable(
1761     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1762     unsigned Abbrev) {
1763   // In order to support all possible bitcode formats in BitcodeReader we need
1764   // to distinguish the following cases:
1765   // 1) Record has no artificial tag (Record[1]),
1766   //   has no obsolete inlinedAt field (Record[9]).
1767   //   In this case Record size will be 8, HasAlignment flag is false.
1768   // 2) Record has artificial tag (Record[1]),
1769   //   has no obsolete inlignedAt field (Record[9]).
1770   //   In this case Record size will be 9, HasAlignment flag is false.
1771   // 3) Record has both artificial tag (Record[1]) and
1772   //   obsolete inlignedAt field (Record[9]).
1773   //   In this case Record size will be 10, HasAlignment flag is false.
1774   // 4) Record has neither artificial tag, nor inlignedAt field, but
1775   //   HasAlignment flag is true and Record[8] contains alignment value.
1776   const uint64_t HasAlignmentFlag = 1 << 1;
1777   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1778   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1779   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1780   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1781   Record.push_back(N->getLine());
1782   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1783   Record.push_back(N->getArg());
1784   Record.push_back(N->getFlags());
1785   Record.push_back(N->getAlignInBits());
1786 
1787   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1788   Record.clear();
1789 }
1790 
1791 void ModuleBitcodeWriter::writeDILabel(
1792     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
1793     unsigned Abbrev) {
1794   Record.push_back((uint64_t)N->isDistinct());
1795   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1796   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1797   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1798   Record.push_back(N->getLine());
1799 
1800   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
1801   Record.clear();
1802 }
1803 
1804 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1805                                             SmallVectorImpl<uint64_t> &Record,
1806                                             unsigned Abbrev) {
1807   Record.reserve(N->getElements().size() + 1);
1808   const uint64_t Version = 3 << 1;
1809   Record.push_back((uint64_t)N->isDistinct() | Version);
1810   Record.append(N->elements_begin(), N->elements_end());
1811 
1812   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1813   Record.clear();
1814 }
1815 
1816 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1817     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1818     unsigned Abbrev) {
1819   Record.push_back(N->isDistinct());
1820   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1821   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1822 
1823   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1824   Record.clear();
1825 }
1826 
1827 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1828                                               SmallVectorImpl<uint64_t> &Record,
1829                                               unsigned Abbrev) {
1830   Record.push_back(N->isDistinct());
1831   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1832   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1833   Record.push_back(N->getLine());
1834   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1835   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1836   Record.push_back(N->getAttributes());
1837   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1838 
1839   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1840   Record.clear();
1841 }
1842 
1843 void ModuleBitcodeWriter::writeDIImportedEntity(
1844     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1845     unsigned Abbrev) {
1846   Record.push_back(N->isDistinct());
1847   Record.push_back(N->getTag());
1848   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1849   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1850   Record.push_back(N->getLine());
1851   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1852   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1853 
1854   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1855   Record.clear();
1856 }
1857 
1858 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1859   auto Abbv = std::make_shared<BitCodeAbbrev>();
1860   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1861   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1862   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1863   return Stream.EmitAbbrev(std::move(Abbv));
1864 }
1865 
1866 void ModuleBitcodeWriter::writeNamedMetadata(
1867     SmallVectorImpl<uint64_t> &Record) {
1868   if (M.named_metadata_empty())
1869     return;
1870 
1871   unsigned Abbrev = createNamedMetadataAbbrev();
1872   for (const NamedMDNode &NMD : M.named_metadata()) {
1873     // Write name.
1874     StringRef Str = NMD.getName();
1875     Record.append(Str.bytes_begin(), Str.bytes_end());
1876     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1877     Record.clear();
1878 
1879     // Write named metadata operands.
1880     for (const MDNode *N : NMD.operands())
1881       Record.push_back(VE.getMetadataID(N));
1882     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1883     Record.clear();
1884   }
1885 }
1886 
1887 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1888   auto Abbv = std::make_shared<BitCodeAbbrev>();
1889   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1890   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1891   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1892   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1893   return Stream.EmitAbbrev(std::move(Abbv));
1894 }
1895 
1896 /// Write out a record for MDString.
1897 ///
1898 /// All the metadata strings in a metadata block are emitted in a single
1899 /// record.  The sizes and strings themselves are shoved into a blob.
1900 void ModuleBitcodeWriter::writeMetadataStrings(
1901     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1902   if (Strings.empty())
1903     return;
1904 
1905   // Start the record with the number of strings.
1906   Record.push_back(bitc::METADATA_STRINGS);
1907   Record.push_back(Strings.size());
1908 
1909   // Emit the sizes of the strings in the blob.
1910   SmallString<256> Blob;
1911   {
1912     BitstreamWriter W(Blob);
1913     for (const Metadata *MD : Strings)
1914       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1915     W.FlushToWord();
1916   }
1917 
1918   // Add the offset to the strings to the record.
1919   Record.push_back(Blob.size());
1920 
1921   // Add the strings to the blob.
1922   for (const Metadata *MD : Strings)
1923     Blob.append(cast<MDString>(MD)->getString());
1924 
1925   // Emit the final record.
1926   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1927   Record.clear();
1928 }
1929 
1930 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1931 enum MetadataAbbrev : unsigned {
1932 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1933 #include "llvm/IR/Metadata.def"
1934   LastPlusOne
1935 };
1936 
1937 void ModuleBitcodeWriter::writeMetadataRecords(
1938     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1939     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1940   if (MDs.empty())
1941     return;
1942 
1943   // Initialize MDNode abbreviations.
1944 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1945 #include "llvm/IR/Metadata.def"
1946 
1947   for (const Metadata *MD : MDs) {
1948     if (IndexPos)
1949       IndexPos->push_back(Stream.GetCurrentBitNo());
1950     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1951       assert(N->isResolved() && "Expected forward references to be resolved");
1952 
1953       switch (N->getMetadataID()) {
1954       default:
1955         llvm_unreachable("Invalid MDNode subclass");
1956 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1957   case Metadata::CLASS##Kind:                                                  \
1958     if (MDAbbrevs)                                                             \
1959       write##CLASS(cast<CLASS>(N), Record,                                     \
1960                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1961     else                                                                       \
1962       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1963     continue;
1964 #include "llvm/IR/Metadata.def"
1965       }
1966     }
1967     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1968   }
1969 }
1970 
1971 void ModuleBitcodeWriter::writeModuleMetadata() {
1972   if (!VE.hasMDs() && M.named_metadata_empty())
1973     return;
1974 
1975   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1976   SmallVector<uint64_t, 64> Record;
1977 
1978   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1979   // block and load any metadata.
1980   std::vector<unsigned> MDAbbrevs;
1981 
1982   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1983   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1984   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1985       createGenericDINodeAbbrev();
1986 
1987   auto Abbv = std::make_shared<BitCodeAbbrev>();
1988   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1989   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1990   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1991   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1992 
1993   Abbv = std::make_shared<BitCodeAbbrev>();
1994   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1995   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1996   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1997   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1998 
1999   // Emit MDStrings together upfront.
2000   writeMetadataStrings(VE.getMDStrings(), Record);
2001 
2002   // We only emit an index for the metadata record if we have more than a given
2003   // (naive) threshold of metadatas, otherwise it is not worth it.
2004   if (VE.getNonMDStrings().size() > IndexThreshold) {
2005     // Write a placeholder value in for the offset of the metadata index,
2006     // which is written after the records, so that it can include
2007     // the offset of each entry. The placeholder offset will be
2008     // updated after all records are emitted.
2009     uint64_t Vals[] = {0, 0};
2010     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2011   }
2012 
2013   // Compute and save the bit offset to the current position, which will be
2014   // patched when we emit the index later. We can simply subtract the 64-bit
2015   // fixed size from the current bit number to get the location to backpatch.
2016   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2017 
2018   // This index will contain the bitpos for each individual record.
2019   std::vector<uint64_t> IndexPos;
2020   IndexPos.reserve(VE.getNonMDStrings().size());
2021 
2022   // Write all the records
2023   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2024 
2025   if (VE.getNonMDStrings().size() > IndexThreshold) {
2026     // Now that we have emitted all the records we will emit the index. But
2027     // first
2028     // backpatch the forward reference so that the reader can skip the records
2029     // efficiently.
2030     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2031                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2032 
2033     // Delta encode the index.
2034     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2035     for (auto &Elt : IndexPos) {
2036       auto EltDelta = Elt - PreviousValue;
2037       PreviousValue = Elt;
2038       Elt = EltDelta;
2039     }
2040     // Emit the index record.
2041     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2042     IndexPos.clear();
2043   }
2044 
2045   // Write the named metadata now.
2046   writeNamedMetadata(Record);
2047 
2048   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2049     SmallVector<uint64_t, 4> Record;
2050     Record.push_back(VE.getValueID(&GO));
2051     pushGlobalMetadataAttachment(Record, GO);
2052     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2053   };
2054   for (const Function &F : M)
2055     if (F.isDeclaration() && F.hasMetadata())
2056       AddDeclAttachedMetadata(F);
2057   // FIXME: Only store metadata for declarations here, and move data for global
2058   // variable definitions to a separate block (PR28134).
2059   for (const GlobalVariable &GV : M.globals())
2060     if (GV.hasMetadata())
2061       AddDeclAttachedMetadata(GV);
2062 
2063   Stream.ExitBlock();
2064 }
2065 
2066 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2067   if (!VE.hasMDs())
2068     return;
2069 
2070   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2071   SmallVector<uint64_t, 64> Record;
2072   writeMetadataStrings(VE.getMDStrings(), Record);
2073   writeMetadataRecords(VE.getNonMDStrings(), Record);
2074   Stream.ExitBlock();
2075 }
2076 
2077 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2078     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2079   // [n x [id, mdnode]]
2080   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2081   GO.getAllMetadata(MDs);
2082   for (const auto &I : MDs) {
2083     Record.push_back(I.first);
2084     Record.push_back(VE.getMetadataID(I.second));
2085   }
2086 }
2087 
2088 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2089   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2090 
2091   SmallVector<uint64_t, 64> Record;
2092 
2093   if (F.hasMetadata()) {
2094     pushGlobalMetadataAttachment(Record, F);
2095     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2096     Record.clear();
2097   }
2098 
2099   // Write metadata attachments
2100   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2101   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2102   for (const BasicBlock &BB : F)
2103     for (const Instruction &I : BB) {
2104       MDs.clear();
2105       I.getAllMetadataOtherThanDebugLoc(MDs);
2106 
2107       // If no metadata, ignore instruction.
2108       if (MDs.empty()) continue;
2109 
2110       Record.push_back(VE.getInstructionID(&I));
2111 
2112       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2113         Record.push_back(MDs[i].first);
2114         Record.push_back(VE.getMetadataID(MDs[i].second));
2115       }
2116       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2117       Record.clear();
2118     }
2119 
2120   Stream.ExitBlock();
2121 }
2122 
2123 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2124   SmallVector<uint64_t, 64> Record;
2125 
2126   // Write metadata kinds
2127   // METADATA_KIND - [n x [id, name]]
2128   SmallVector<StringRef, 8> Names;
2129   M.getMDKindNames(Names);
2130 
2131   if (Names.empty()) return;
2132 
2133   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2134 
2135   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2136     Record.push_back(MDKindID);
2137     StringRef KName = Names[MDKindID];
2138     Record.append(KName.begin(), KName.end());
2139 
2140     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2141     Record.clear();
2142   }
2143 
2144   Stream.ExitBlock();
2145 }
2146 
2147 void ModuleBitcodeWriter::writeOperandBundleTags() {
2148   // Write metadata kinds
2149   //
2150   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2151   //
2152   // OPERAND_BUNDLE_TAG - [strchr x N]
2153 
2154   SmallVector<StringRef, 8> Tags;
2155   M.getOperandBundleTags(Tags);
2156 
2157   if (Tags.empty())
2158     return;
2159 
2160   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2161 
2162   SmallVector<uint64_t, 64> Record;
2163 
2164   for (auto Tag : Tags) {
2165     Record.append(Tag.begin(), Tag.end());
2166 
2167     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2168     Record.clear();
2169   }
2170 
2171   Stream.ExitBlock();
2172 }
2173 
2174 void ModuleBitcodeWriter::writeSyncScopeNames() {
2175   SmallVector<StringRef, 8> SSNs;
2176   M.getContext().getSyncScopeNames(SSNs);
2177   if (SSNs.empty())
2178     return;
2179 
2180   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2181 
2182   SmallVector<uint64_t, 64> Record;
2183   for (auto SSN : SSNs) {
2184     Record.append(SSN.begin(), SSN.end());
2185     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2186     Record.clear();
2187   }
2188 
2189   Stream.ExitBlock();
2190 }
2191 
2192 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2193   if ((int64_t)V >= 0)
2194     Vals.push_back(V << 1);
2195   else
2196     Vals.push_back((-V << 1) | 1);
2197 }
2198 
2199 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2200                                          bool isGlobal) {
2201   if (FirstVal == LastVal) return;
2202 
2203   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2204 
2205   unsigned AggregateAbbrev = 0;
2206   unsigned String8Abbrev = 0;
2207   unsigned CString7Abbrev = 0;
2208   unsigned CString6Abbrev = 0;
2209   // If this is a constant pool for the module, emit module-specific abbrevs.
2210   if (isGlobal) {
2211     // Abbrev for CST_CODE_AGGREGATE.
2212     auto Abbv = std::make_shared<BitCodeAbbrev>();
2213     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2214     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2215     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2216     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2217 
2218     // Abbrev for CST_CODE_STRING.
2219     Abbv = std::make_shared<BitCodeAbbrev>();
2220     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2223     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2224     // Abbrev for CST_CODE_CSTRING.
2225     Abbv = std::make_shared<BitCodeAbbrev>();
2226     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2227     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2228     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2229     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2230     // Abbrev for CST_CODE_CSTRING.
2231     Abbv = std::make_shared<BitCodeAbbrev>();
2232     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2233     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2234     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2235     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2236   }
2237 
2238   SmallVector<uint64_t, 64> Record;
2239 
2240   const ValueEnumerator::ValueList &Vals = VE.getValues();
2241   Type *LastTy = nullptr;
2242   for (unsigned i = FirstVal; i != LastVal; ++i) {
2243     const Value *V = Vals[i].first;
2244     // If we need to switch types, do so now.
2245     if (V->getType() != LastTy) {
2246       LastTy = V->getType();
2247       Record.push_back(VE.getTypeID(LastTy));
2248       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2249                         CONSTANTS_SETTYPE_ABBREV);
2250       Record.clear();
2251     }
2252 
2253     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2254       Record.push_back(unsigned(IA->hasSideEffects()) |
2255                        unsigned(IA->isAlignStack()) << 1 |
2256                        unsigned(IA->getDialect()&1) << 2);
2257 
2258       // Add the asm string.
2259       const std::string &AsmStr = IA->getAsmString();
2260       Record.push_back(AsmStr.size());
2261       Record.append(AsmStr.begin(), AsmStr.end());
2262 
2263       // Add the constraint string.
2264       const std::string &ConstraintStr = IA->getConstraintString();
2265       Record.push_back(ConstraintStr.size());
2266       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2267       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2268       Record.clear();
2269       continue;
2270     }
2271     const Constant *C = cast<Constant>(V);
2272     unsigned Code = -1U;
2273     unsigned AbbrevToUse = 0;
2274     if (C->isNullValue()) {
2275       Code = bitc::CST_CODE_NULL;
2276     } else if (isa<UndefValue>(C)) {
2277       Code = bitc::CST_CODE_UNDEF;
2278     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2279       if (IV->getBitWidth() <= 64) {
2280         uint64_t V = IV->getSExtValue();
2281         emitSignedInt64(Record, V);
2282         Code = bitc::CST_CODE_INTEGER;
2283         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2284       } else {                             // Wide integers, > 64 bits in size.
2285         // We have an arbitrary precision integer value to write whose
2286         // bit width is > 64. However, in canonical unsigned integer
2287         // format it is likely that the high bits are going to be zero.
2288         // So, we only write the number of active words.
2289         unsigned NWords = IV->getValue().getActiveWords();
2290         const uint64_t *RawWords = IV->getValue().getRawData();
2291         for (unsigned i = 0; i != NWords; ++i) {
2292           emitSignedInt64(Record, RawWords[i]);
2293         }
2294         Code = bitc::CST_CODE_WIDE_INTEGER;
2295       }
2296     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2297       Code = bitc::CST_CODE_FLOAT;
2298       Type *Ty = CFP->getType();
2299       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2300         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2301       } else if (Ty->isX86_FP80Ty()) {
2302         // api needed to prevent premature destruction
2303         // bits are not in the same order as a normal i80 APInt, compensate.
2304         APInt api = CFP->getValueAPF().bitcastToAPInt();
2305         const uint64_t *p = api.getRawData();
2306         Record.push_back((p[1] << 48) | (p[0] >> 16));
2307         Record.push_back(p[0] & 0xffffLL);
2308       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2309         APInt api = CFP->getValueAPF().bitcastToAPInt();
2310         const uint64_t *p = api.getRawData();
2311         Record.push_back(p[0]);
2312         Record.push_back(p[1]);
2313       } else {
2314         assert(0 && "Unknown FP type!");
2315       }
2316     } else if (isa<ConstantDataSequential>(C) &&
2317                cast<ConstantDataSequential>(C)->isString()) {
2318       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2319       // Emit constant strings specially.
2320       unsigned NumElts = Str->getNumElements();
2321       // If this is a null-terminated string, use the denser CSTRING encoding.
2322       if (Str->isCString()) {
2323         Code = bitc::CST_CODE_CSTRING;
2324         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2325       } else {
2326         Code = bitc::CST_CODE_STRING;
2327         AbbrevToUse = String8Abbrev;
2328       }
2329       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2330       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2331       for (unsigned i = 0; i != NumElts; ++i) {
2332         unsigned char V = Str->getElementAsInteger(i);
2333         Record.push_back(V);
2334         isCStr7 &= (V & 128) == 0;
2335         if (isCStrChar6)
2336           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2337       }
2338 
2339       if (isCStrChar6)
2340         AbbrevToUse = CString6Abbrev;
2341       else if (isCStr7)
2342         AbbrevToUse = CString7Abbrev;
2343     } else if (const ConstantDataSequential *CDS =
2344                   dyn_cast<ConstantDataSequential>(C)) {
2345       Code = bitc::CST_CODE_DATA;
2346       Type *EltTy = CDS->getType()->getElementType();
2347       if (isa<IntegerType>(EltTy)) {
2348         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2349           Record.push_back(CDS->getElementAsInteger(i));
2350       } else {
2351         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2352           Record.push_back(
2353               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2354       }
2355     } else if (isa<ConstantAggregate>(C)) {
2356       Code = bitc::CST_CODE_AGGREGATE;
2357       for (const Value *Op : C->operands())
2358         Record.push_back(VE.getValueID(Op));
2359       AbbrevToUse = AggregateAbbrev;
2360     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2361       switch (CE->getOpcode()) {
2362       default:
2363         if (Instruction::isCast(CE->getOpcode())) {
2364           Code = bitc::CST_CODE_CE_CAST;
2365           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2366           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2367           Record.push_back(VE.getValueID(C->getOperand(0)));
2368           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2369         } else {
2370           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2371           Code = bitc::CST_CODE_CE_BINOP;
2372           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2373           Record.push_back(VE.getValueID(C->getOperand(0)));
2374           Record.push_back(VE.getValueID(C->getOperand(1)));
2375           uint64_t Flags = getOptimizationFlags(CE);
2376           if (Flags != 0)
2377             Record.push_back(Flags);
2378         }
2379         break;
2380       case Instruction::GetElementPtr: {
2381         Code = bitc::CST_CODE_CE_GEP;
2382         const auto *GO = cast<GEPOperator>(C);
2383         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2384         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2385           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2386           Record.push_back((*Idx << 1) | GO->isInBounds());
2387         } else if (GO->isInBounds())
2388           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2389         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2390           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2391           Record.push_back(VE.getValueID(C->getOperand(i)));
2392         }
2393         break;
2394       }
2395       case Instruction::Select:
2396         Code = bitc::CST_CODE_CE_SELECT;
2397         Record.push_back(VE.getValueID(C->getOperand(0)));
2398         Record.push_back(VE.getValueID(C->getOperand(1)));
2399         Record.push_back(VE.getValueID(C->getOperand(2)));
2400         break;
2401       case Instruction::ExtractElement:
2402         Code = bitc::CST_CODE_CE_EXTRACTELT;
2403         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2404         Record.push_back(VE.getValueID(C->getOperand(0)));
2405         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2406         Record.push_back(VE.getValueID(C->getOperand(1)));
2407         break;
2408       case Instruction::InsertElement:
2409         Code = bitc::CST_CODE_CE_INSERTELT;
2410         Record.push_back(VE.getValueID(C->getOperand(0)));
2411         Record.push_back(VE.getValueID(C->getOperand(1)));
2412         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2413         Record.push_back(VE.getValueID(C->getOperand(2)));
2414         break;
2415       case Instruction::ShuffleVector:
2416         // If the return type and argument types are the same, this is a
2417         // standard shufflevector instruction.  If the types are different,
2418         // then the shuffle is widening or truncating the input vectors, and
2419         // the argument type must also be encoded.
2420         if (C->getType() == C->getOperand(0)->getType()) {
2421           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2422         } else {
2423           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2424           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2425         }
2426         Record.push_back(VE.getValueID(C->getOperand(0)));
2427         Record.push_back(VE.getValueID(C->getOperand(1)));
2428         Record.push_back(VE.getValueID(C->getOperand(2)));
2429         break;
2430       case Instruction::ICmp:
2431       case Instruction::FCmp:
2432         Code = bitc::CST_CODE_CE_CMP;
2433         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2434         Record.push_back(VE.getValueID(C->getOperand(0)));
2435         Record.push_back(VE.getValueID(C->getOperand(1)));
2436         Record.push_back(CE->getPredicate());
2437         break;
2438       }
2439     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2440       Code = bitc::CST_CODE_BLOCKADDRESS;
2441       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2442       Record.push_back(VE.getValueID(BA->getFunction()));
2443       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2444     } else {
2445 #ifndef NDEBUG
2446       C->dump();
2447 #endif
2448       llvm_unreachable("Unknown constant!");
2449     }
2450     Stream.EmitRecord(Code, Record, AbbrevToUse);
2451     Record.clear();
2452   }
2453 
2454   Stream.ExitBlock();
2455 }
2456 
2457 void ModuleBitcodeWriter::writeModuleConstants() {
2458   const ValueEnumerator::ValueList &Vals = VE.getValues();
2459 
2460   // Find the first constant to emit, which is the first non-globalvalue value.
2461   // We know globalvalues have been emitted by WriteModuleInfo.
2462   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2463     if (!isa<GlobalValue>(Vals[i].first)) {
2464       writeConstants(i, Vals.size(), true);
2465       return;
2466     }
2467   }
2468 }
2469 
2470 /// pushValueAndType - The file has to encode both the value and type id for
2471 /// many values, because we need to know what type to create for forward
2472 /// references.  However, most operands are not forward references, so this type
2473 /// field is not needed.
2474 ///
2475 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2476 /// instruction ID, then it is a forward reference, and it also includes the
2477 /// type ID.  The value ID that is written is encoded relative to the InstID.
2478 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2479                                            SmallVectorImpl<unsigned> &Vals) {
2480   unsigned ValID = VE.getValueID(V);
2481   // Make encoding relative to the InstID.
2482   Vals.push_back(InstID - ValID);
2483   if (ValID >= InstID) {
2484     Vals.push_back(VE.getTypeID(V->getType()));
2485     return true;
2486   }
2487   return false;
2488 }
2489 
2490 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2491                                               unsigned InstID) {
2492   SmallVector<unsigned, 64> Record;
2493   LLVMContext &C = CS.getInstruction()->getContext();
2494 
2495   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2496     const auto &Bundle = CS.getOperandBundleAt(i);
2497     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2498 
2499     for (auto &Input : Bundle.Inputs)
2500       pushValueAndType(Input, InstID, Record);
2501 
2502     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2503     Record.clear();
2504   }
2505 }
2506 
2507 /// pushValue - Like pushValueAndType, but where the type of the value is
2508 /// omitted (perhaps it was already encoded in an earlier operand).
2509 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2510                                     SmallVectorImpl<unsigned> &Vals) {
2511   unsigned ValID = VE.getValueID(V);
2512   Vals.push_back(InstID - ValID);
2513 }
2514 
2515 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2516                                           SmallVectorImpl<uint64_t> &Vals) {
2517   unsigned ValID = VE.getValueID(V);
2518   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2519   emitSignedInt64(Vals, diff);
2520 }
2521 
2522 /// WriteInstruction - Emit an instruction to the specified stream.
2523 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2524                                            unsigned InstID,
2525                                            SmallVectorImpl<unsigned> &Vals) {
2526   unsigned Code = 0;
2527   unsigned AbbrevToUse = 0;
2528   VE.setInstructionID(&I);
2529   switch (I.getOpcode()) {
2530   default:
2531     if (Instruction::isCast(I.getOpcode())) {
2532       Code = bitc::FUNC_CODE_INST_CAST;
2533       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2534         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2535       Vals.push_back(VE.getTypeID(I.getType()));
2536       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2537     } else {
2538       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2539       Code = bitc::FUNC_CODE_INST_BINOP;
2540       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2541         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2542       pushValue(I.getOperand(1), InstID, Vals);
2543       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2544       uint64_t Flags = getOptimizationFlags(&I);
2545       if (Flags != 0) {
2546         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2547           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2548         Vals.push_back(Flags);
2549       }
2550     }
2551     break;
2552 
2553   case Instruction::GetElementPtr: {
2554     Code = bitc::FUNC_CODE_INST_GEP;
2555     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2556     auto &GEPInst = cast<GetElementPtrInst>(I);
2557     Vals.push_back(GEPInst.isInBounds());
2558     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2559     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2560       pushValueAndType(I.getOperand(i), InstID, Vals);
2561     break;
2562   }
2563   case Instruction::ExtractValue: {
2564     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2565     pushValueAndType(I.getOperand(0), InstID, Vals);
2566     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2567     Vals.append(EVI->idx_begin(), EVI->idx_end());
2568     break;
2569   }
2570   case Instruction::InsertValue: {
2571     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2572     pushValueAndType(I.getOperand(0), InstID, Vals);
2573     pushValueAndType(I.getOperand(1), InstID, Vals);
2574     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2575     Vals.append(IVI->idx_begin(), IVI->idx_end());
2576     break;
2577   }
2578   case Instruction::Select:
2579     Code = bitc::FUNC_CODE_INST_VSELECT;
2580     pushValueAndType(I.getOperand(1), InstID, Vals);
2581     pushValue(I.getOperand(2), InstID, Vals);
2582     pushValueAndType(I.getOperand(0), InstID, Vals);
2583     break;
2584   case Instruction::ExtractElement:
2585     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2586     pushValueAndType(I.getOperand(0), InstID, Vals);
2587     pushValueAndType(I.getOperand(1), InstID, Vals);
2588     break;
2589   case Instruction::InsertElement:
2590     Code = bitc::FUNC_CODE_INST_INSERTELT;
2591     pushValueAndType(I.getOperand(0), InstID, Vals);
2592     pushValue(I.getOperand(1), InstID, Vals);
2593     pushValueAndType(I.getOperand(2), InstID, Vals);
2594     break;
2595   case Instruction::ShuffleVector:
2596     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2597     pushValueAndType(I.getOperand(0), InstID, Vals);
2598     pushValue(I.getOperand(1), InstID, Vals);
2599     pushValue(I.getOperand(2), InstID, Vals);
2600     break;
2601   case Instruction::ICmp:
2602   case Instruction::FCmp: {
2603     // compare returning Int1Ty or vector of Int1Ty
2604     Code = bitc::FUNC_CODE_INST_CMP2;
2605     pushValueAndType(I.getOperand(0), InstID, Vals);
2606     pushValue(I.getOperand(1), InstID, Vals);
2607     Vals.push_back(cast<CmpInst>(I).getPredicate());
2608     uint64_t Flags = getOptimizationFlags(&I);
2609     if (Flags != 0)
2610       Vals.push_back(Flags);
2611     break;
2612   }
2613 
2614   case Instruction::Ret:
2615     {
2616       Code = bitc::FUNC_CODE_INST_RET;
2617       unsigned NumOperands = I.getNumOperands();
2618       if (NumOperands == 0)
2619         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2620       else if (NumOperands == 1) {
2621         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2622           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2623       } else {
2624         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2625           pushValueAndType(I.getOperand(i), InstID, Vals);
2626       }
2627     }
2628     break;
2629   case Instruction::Br:
2630     {
2631       Code = bitc::FUNC_CODE_INST_BR;
2632       const BranchInst &II = cast<BranchInst>(I);
2633       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2634       if (II.isConditional()) {
2635         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2636         pushValue(II.getCondition(), InstID, Vals);
2637       }
2638     }
2639     break;
2640   case Instruction::Switch:
2641     {
2642       Code = bitc::FUNC_CODE_INST_SWITCH;
2643       const SwitchInst &SI = cast<SwitchInst>(I);
2644       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2645       pushValue(SI.getCondition(), InstID, Vals);
2646       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2647       for (auto Case : SI.cases()) {
2648         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2649         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2650       }
2651     }
2652     break;
2653   case Instruction::IndirectBr:
2654     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2655     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2656     // Encode the address operand as relative, but not the basic blocks.
2657     pushValue(I.getOperand(0), InstID, Vals);
2658     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2659       Vals.push_back(VE.getValueID(I.getOperand(i)));
2660     break;
2661 
2662   case Instruction::Invoke: {
2663     const InvokeInst *II = cast<InvokeInst>(&I);
2664     const Value *Callee = II->getCalledValue();
2665     FunctionType *FTy = II->getFunctionType();
2666 
2667     if (II->hasOperandBundles())
2668       writeOperandBundles(II, InstID);
2669 
2670     Code = bitc::FUNC_CODE_INST_INVOKE;
2671 
2672     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2673     Vals.push_back(II->getCallingConv() | 1 << 13);
2674     Vals.push_back(VE.getValueID(II->getNormalDest()));
2675     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2676     Vals.push_back(VE.getTypeID(FTy));
2677     pushValueAndType(Callee, InstID, Vals);
2678 
2679     // Emit value #'s for the fixed parameters.
2680     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2681       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2682 
2683     // Emit type/value pairs for varargs params.
2684     if (FTy->isVarArg()) {
2685       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2686            i != e; ++i)
2687         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2688     }
2689     break;
2690   }
2691   case Instruction::Resume:
2692     Code = bitc::FUNC_CODE_INST_RESUME;
2693     pushValueAndType(I.getOperand(0), InstID, Vals);
2694     break;
2695   case Instruction::CleanupRet: {
2696     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2697     const auto &CRI = cast<CleanupReturnInst>(I);
2698     pushValue(CRI.getCleanupPad(), InstID, Vals);
2699     if (CRI.hasUnwindDest())
2700       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2701     break;
2702   }
2703   case Instruction::CatchRet: {
2704     Code = bitc::FUNC_CODE_INST_CATCHRET;
2705     const auto &CRI = cast<CatchReturnInst>(I);
2706     pushValue(CRI.getCatchPad(), InstID, Vals);
2707     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2708     break;
2709   }
2710   case Instruction::CleanupPad:
2711   case Instruction::CatchPad: {
2712     const auto &FuncletPad = cast<FuncletPadInst>(I);
2713     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2714                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2715     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2716 
2717     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2718     Vals.push_back(NumArgOperands);
2719     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2720       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2721     break;
2722   }
2723   case Instruction::CatchSwitch: {
2724     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2725     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2726 
2727     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2728 
2729     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2730     Vals.push_back(NumHandlers);
2731     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2732       Vals.push_back(VE.getValueID(CatchPadBB));
2733 
2734     if (CatchSwitch.hasUnwindDest())
2735       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2736     break;
2737   }
2738   case Instruction::Unreachable:
2739     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2740     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2741     break;
2742 
2743   case Instruction::PHI: {
2744     const PHINode &PN = cast<PHINode>(I);
2745     Code = bitc::FUNC_CODE_INST_PHI;
2746     // With the newer instruction encoding, forward references could give
2747     // negative valued IDs.  This is most common for PHIs, so we use
2748     // signed VBRs.
2749     SmallVector<uint64_t, 128> Vals64;
2750     Vals64.push_back(VE.getTypeID(PN.getType()));
2751     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2752       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2753       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2754     }
2755     // Emit a Vals64 vector and exit.
2756     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2757     Vals64.clear();
2758     return;
2759   }
2760 
2761   case Instruction::LandingPad: {
2762     const LandingPadInst &LP = cast<LandingPadInst>(I);
2763     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2764     Vals.push_back(VE.getTypeID(LP.getType()));
2765     Vals.push_back(LP.isCleanup());
2766     Vals.push_back(LP.getNumClauses());
2767     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2768       if (LP.isCatch(I))
2769         Vals.push_back(LandingPadInst::Catch);
2770       else
2771         Vals.push_back(LandingPadInst::Filter);
2772       pushValueAndType(LP.getClause(I), InstID, Vals);
2773     }
2774     break;
2775   }
2776 
2777   case Instruction::Alloca: {
2778     Code = bitc::FUNC_CODE_INST_ALLOCA;
2779     const AllocaInst &AI = cast<AllocaInst>(I);
2780     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2781     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2782     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2783     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2784     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2785            "not enough bits for maximum alignment");
2786     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2787     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2788     AlignRecord |= 1 << 6;
2789     AlignRecord |= AI.isSwiftError() << 7;
2790     Vals.push_back(AlignRecord);
2791     break;
2792   }
2793 
2794   case Instruction::Load:
2795     if (cast<LoadInst>(I).isAtomic()) {
2796       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2797       pushValueAndType(I.getOperand(0), InstID, Vals);
2798     } else {
2799       Code = bitc::FUNC_CODE_INST_LOAD;
2800       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2801         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2802     }
2803     Vals.push_back(VE.getTypeID(I.getType()));
2804     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2805     Vals.push_back(cast<LoadInst>(I).isVolatile());
2806     if (cast<LoadInst>(I).isAtomic()) {
2807       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2808       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2809     }
2810     break;
2811   case Instruction::Store:
2812     if (cast<StoreInst>(I).isAtomic())
2813       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2814     else
2815       Code = bitc::FUNC_CODE_INST_STORE;
2816     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2817     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2818     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2819     Vals.push_back(cast<StoreInst>(I).isVolatile());
2820     if (cast<StoreInst>(I).isAtomic()) {
2821       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2822       Vals.push_back(
2823           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2824     }
2825     break;
2826   case Instruction::AtomicCmpXchg:
2827     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2828     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2829     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2830     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2831     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2832     Vals.push_back(
2833         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2834     Vals.push_back(
2835         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2836     Vals.push_back(
2837         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2838     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2839     break;
2840   case Instruction::AtomicRMW:
2841     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2842     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2843     pushValue(I.getOperand(1), InstID, Vals);        // val.
2844     Vals.push_back(
2845         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2846     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2847     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2848     Vals.push_back(
2849         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2850     break;
2851   case Instruction::Fence:
2852     Code = bitc::FUNC_CODE_INST_FENCE;
2853     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2854     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2855     break;
2856   case Instruction::Call: {
2857     const CallInst &CI = cast<CallInst>(I);
2858     FunctionType *FTy = CI.getFunctionType();
2859 
2860     if (CI.hasOperandBundles())
2861       writeOperandBundles(&CI, InstID);
2862 
2863     Code = bitc::FUNC_CODE_INST_CALL;
2864 
2865     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2866 
2867     unsigned Flags = getOptimizationFlags(&I);
2868     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2869                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2870                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2871                    1 << bitc::CALL_EXPLICIT_TYPE |
2872                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2873                    unsigned(Flags != 0) << bitc::CALL_FMF);
2874     if (Flags != 0)
2875       Vals.push_back(Flags);
2876 
2877     Vals.push_back(VE.getTypeID(FTy));
2878     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2879 
2880     // Emit value #'s for the fixed parameters.
2881     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2882       // Check for labels (can happen with asm labels).
2883       if (FTy->getParamType(i)->isLabelTy())
2884         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2885       else
2886         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2887     }
2888 
2889     // Emit type/value pairs for varargs params.
2890     if (FTy->isVarArg()) {
2891       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2892            i != e; ++i)
2893         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2894     }
2895     break;
2896   }
2897   case Instruction::VAArg:
2898     Code = bitc::FUNC_CODE_INST_VAARG;
2899     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2900     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2901     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2902     break;
2903   }
2904 
2905   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2906   Vals.clear();
2907 }
2908 
2909 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2910 /// to allow clients to efficiently find the function body.
2911 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2912   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2913   // Get the offset of the VST we are writing, and backpatch it into
2914   // the VST forward declaration record.
2915   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2916   // The BitcodeStartBit was the stream offset of the identification block.
2917   VSTOffset -= bitcodeStartBit();
2918   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2919   // Note that we add 1 here because the offset is relative to one word
2920   // before the start of the identification block, which was historically
2921   // always the start of the regular bitcode header.
2922   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2923 
2924   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2925 
2926   auto Abbv = std::make_shared<BitCodeAbbrev>();
2927   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2928   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2929   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2930   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2931 
2932   for (const Function &F : M) {
2933     uint64_t Record[2];
2934 
2935     if (F.isDeclaration())
2936       continue;
2937 
2938     Record[0] = VE.getValueID(&F);
2939 
2940     // Save the word offset of the function (from the start of the
2941     // actual bitcode written to the stream).
2942     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2943     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2944     // Note that we add 1 here because the offset is relative to one word
2945     // before the start of the identification block, which was historically
2946     // always the start of the regular bitcode header.
2947     Record[1] = BitcodeIndex / 32 + 1;
2948 
2949     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2950   }
2951 
2952   Stream.ExitBlock();
2953 }
2954 
2955 /// Emit names for arguments, instructions and basic blocks in a function.
2956 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2957     const ValueSymbolTable &VST) {
2958   if (VST.empty())
2959     return;
2960 
2961   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2962 
2963   // FIXME: Set up the abbrev, we know how many values there are!
2964   // FIXME: We know if the type names can use 7-bit ascii.
2965   SmallVector<uint64_t, 64> NameVals;
2966 
2967   for (const ValueName &Name : VST) {
2968     // Figure out the encoding to use for the name.
2969     StringEncoding Bits = getStringEncoding(Name.getKey());
2970 
2971     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2972     NameVals.push_back(VE.getValueID(Name.getValue()));
2973 
2974     // VST_CODE_ENTRY:   [valueid, namechar x N]
2975     // VST_CODE_BBENTRY: [bbid, namechar x N]
2976     unsigned Code;
2977     if (isa<BasicBlock>(Name.getValue())) {
2978       Code = bitc::VST_CODE_BBENTRY;
2979       if (Bits == SE_Char6)
2980         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2981     } else {
2982       Code = bitc::VST_CODE_ENTRY;
2983       if (Bits == SE_Char6)
2984         AbbrevToUse = VST_ENTRY_6_ABBREV;
2985       else if (Bits == SE_Fixed7)
2986         AbbrevToUse = VST_ENTRY_7_ABBREV;
2987     }
2988 
2989     for (const auto P : Name.getKey())
2990       NameVals.push_back((unsigned char)P);
2991 
2992     // Emit the finished record.
2993     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2994     NameVals.clear();
2995   }
2996 
2997   Stream.ExitBlock();
2998 }
2999 
3000 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3001   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3002   unsigned Code;
3003   if (isa<BasicBlock>(Order.V))
3004     Code = bitc::USELIST_CODE_BB;
3005   else
3006     Code = bitc::USELIST_CODE_DEFAULT;
3007 
3008   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3009   Record.push_back(VE.getValueID(Order.V));
3010   Stream.EmitRecord(Code, Record);
3011 }
3012 
3013 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3014   assert(VE.shouldPreserveUseListOrder() &&
3015          "Expected to be preserving use-list order");
3016 
3017   auto hasMore = [&]() {
3018     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3019   };
3020   if (!hasMore())
3021     // Nothing to do.
3022     return;
3023 
3024   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3025   while (hasMore()) {
3026     writeUseList(std::move(VE.UseListOrders.back()));
3027     VE.UseListOrders.pop_back();
3028   }
3029   Stream.ExitBlock();
3030 }
3031 
3032 /// Emit a function body to the module stream.
3033 void ModuleBitcodeWriter::writeFunction(
3034     const Function &F,
3035     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3036   // Save the bitcode index of the start of this function block for recording
3037   // in the VST.
3038   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3039 
3040   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3041   VE.incorporateFunction(F);
3042 
3043   SmallVector<unsigned, 64> Vals;
3044 
3045   // Emit the number of basic blocks, so the reader can create them ahead of
3046   // time.
3047   Vals.push_back(VE.getBasicBlocks().size());
3048   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3049   Vals.clear();
3050 
3051   // If there are function-local constants, emit them now.
3052   unsigned CstStart, CstEnd;
3053   VE.getFunctionConstantRange(CstStart, CstEnd);
3054   writeConstants(CstStart, CstEnd, false);
3055 
3056   // If there is function-local metadata, emit it now.
3057   writeFunctionMetadata(F);
3058 
3059   // Keep a running idea of what the instruction ID is.
3060   unsigned InstID = CstEnd;
3061 
3062   bool NeedsMetadataAttachment = F.hasMetadata();
3063 
3064   DILocation *LastDL = nullptr;
3065   // Finally, emit all the instructions, in order.
3066   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3067     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3068          I != E; ++I) {
3069       writeInstruction(*I, InstID, Vals);
3070 
3071       if (!I->getType()->isVoidTy())
3072         ++InstID;
3073 
3074       // If the instruction has metadata, write a metadata attachment later.
3075       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3076 
3077       // If the instruction has a debug location, emit it.
3078       DILocation *DL = I->getDebugLoc();
3079       if (!DL)
3080         continue;
3081 
3082       if (DL == LastDL) {
3083         // Just repeat the same debug loc as last time.
3084         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3085         continue;
3086       }
3087 
3088       Vals.push_back(DL->getLine());
3089       Vals.push_back(DL->getColumn());
3090       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3091       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3092       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3093       Vals.clear();
3094 
3095       LastDL = DL;
3096     }
3097 
3098   // Emit names for all the instructions etc.
3099   if (auto *Symtab = F.getValueSymbolTable())
3100     writeFunctionLevelValueSymbolTable(*Symtab);
3101 
3102   if (NeedsMetadataAttachment)
3103     writeFunctionMetadataAttachment(F);
3104   if (VE.shouldPreserveUseListOrder())
3105     writeUseListBlock(&F);
3106   VE.purgeFunction();
3107   Stream.ExitBlock();
3108 }
3109 
3110 // Emit blockinfo, which defines the standard abbreviations etc.
3111 void ModuleBitcodeWriter::writeBlockInfo() {
3112   // We only want to emit block info records for blocks that have multiple
3113   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3114   // Other blocks can define their abbrevs inline.
3115   Stream.EnterBlockInfoBlock();
3116 
3117   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3118     auto Abbv = std::make_shared<BitCodeAbbrev>();
3119     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3120     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3121     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3122     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3123     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3124         VST_ENTRY_8_ABBREV)
3125       llvm_unreachable("Unexpected abbrev ordering!");
3126   }
3127 
3128   { // 7-bit fixed width VST_CODE_ENTRY strings.
3129     auto Abbv = std::make_shared<BitCodeAbbrev>();
3130     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3131     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3132     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3134     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3135         VST_ENTRY_7_ABBREV)
3136       llvm_unreachable("Unexpected abbrev ordering!");
3137   }
3138   { // 6-bit char6 VST_CODE_ENTRY strings.
3139     auto Abbv = std::make_shared<BitCodeAbbrev>();
3140     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3141     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3142     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3143     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3144     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3145         VST_ENTRY_6_ABBREV)
3146       llvm_unreachable("Unexpected abbrev ordering!");
3147   }
3148   { // 6-bit char6 VST_CODE_BBENTRY strings.
3149     auto Abbv = std::make_shared<BitCodeAbbrev>();
3150     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3151     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3153     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3154     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3155         VST_BBENTRY_6_ABBREV)
3156       llvm_unreachable("Unexpected abbrev ordering!");
3157   }
3158 
3159   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3160     auto Abbv = std::make_shared<BitCodeAbbrev>();
3161     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3162     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3163                               VE.computeBitsRequiredForTypeIndicies()));
3164     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3165         CONSTANTS_SETTYPE_ABBREV)
3166       llvm_unreachable("Unexpected abbrev ordering!");
3167   }
3168 
3169   { // INTEGER abbrev for CONSTANTS_BLOCK.
3170     auto Abbv = std::make_shared<BitCodeAbbrev>();
3171     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3173     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3174         CONSTANTS_INTEGER_ABBREV)
3175       llvm_unreachable("Unexpected abbrev ordering!");
3176   }
3177 
3178   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3179     auto Abbv = std::make_shared<BitCodeAbbrev>();
3180     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3181     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3182     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3183                               VE.computeBitsRequiredForTypeIndicies()));
3184     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3185 
3186     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3187         CONSTANTS_CE_CAST_Abbrev)
3188       llvm_unreachable("Unexpected abbrev ordering!");
3189   }
3190   { // NULL abbrev for CONSTANTS_BLOCK.
3191     auto Abbv = std::make_shared<BitCodeAbbrev>();
3192     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3193     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3194         CONSTANTS_NULL_Abbrev)
3195       llvm_unreachable("Unexpected abbrev ordering!");
3196   }
3197 
3198   // FIXME: This should only use space for first class types!
3199 
3200   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3201     auto Abbv = std::make_shared<BitCodeAbbrev>();
3202     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3203     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3204     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3205                               VE.computeBitsRequiredForTypeIndicies()));
3206     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3207     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3208     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3209         FUNCTION_INST_LOAD_ABBREV)
3210       llvm_unreachable("Unexpected abbrev ordering!");
3211   }
3212   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3213     auto Abbv = std::make_shared<BitCodeAbbrev>();
3214     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3215     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3216     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3217     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3218     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3219         FUNCTION_INST_BINOP_ABBREV)
3220       llvm_unreachable("Unexpected abbrev ordering!");
3221   }
3222   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3223     auto Abbv = std::make_shared<BitCodeAbbrev>();
3224     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3225     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3226     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3227     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3228     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3229     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3230         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3231       llvm_unreachable("Unexpected abbrev ordering!");
3232   }
3233   { // INST_CAST abbrev for FUNCTION_BLOCK.
3234     auto Abbv = std::make_shared<BitCodeAbbrev>();
3235     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3236     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3237     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3238                               VE.computeBitsRequiredForTypeIndicies()));
3239     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3240     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3241         FUNCTION_INST_CAST_ABBREV)
3242       llvm_unreachable("Unexpected abbrev ordering!");
3243   }
3244 
3245   { // INST_RET abbrev for FUNCTION_BLOCK.
3246     auto Abbv = std::make_shared<BitCodeAbbrev>();
3247     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3248     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3249         FUNCTION_INST_RET_VOID_ABBREV)
3250       llvm_unreachable("Unexpected abbrev ordering!");
3251   }
3252   { // INST_RET abbrev for FUNCTION_BLOCK.
3253     auto Abbv = std::make_shared<BitCodeAbbrev>();
3254     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3255     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3256     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3257         FUNCTION_INST_RET_VAL_ABBREV)
3258       llvm_unreachable("Unexpected abbrev ordering!");
3259   }
3260   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3261     auto Abbv = std::make_shared<BitCodeAbbrev>();
3262     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3263     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3264         FUNCTION_INST_UNREACHABLE_ABBREV)
3265       llvm_unreachable("Unexpected abbrev ordering!");
3266   }
3267   {
3268     auto Abbv = std::make_shared<BitCodeAbbrev>();
3269     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3270     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3271     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3272                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3273     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3274     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3275     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3276         FUNCTION_INST_GEP_ABBREV)
3277       llvm_unreachable("Unexpected abbrev ordering!");
3278   }
3279 
3280   Stream.ExitBlock();
3281 }
3282 
3283 /// Write the module path strings, currently only used when generating
3284 /// a combined index file.
3285 void IndexBitcodeWriter::writeModStrings() {
3286   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3287 
3288   // TODO: See which abbrev sizes we actually need to emit
3289 
3290   // 8-bit fixed-width MST_ENTRY strings.
3291   auto Abbv = std::make_shared<BitCodeAbbrev>();
3292   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3293   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3294   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3295   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3296   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3297 
3298   // 7-bit fixed width MST_ENTRY strings.
3299   Abbv = std::make_shared<BitCodeAbbrev>();
3300   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3301   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3302   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3303   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3304   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3305 
3306   // 6-bit char6 MST_ENTRY strings.
3307   Abbv = std::make_shared<BitCodeAbbrev>();
3308   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3309   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3310   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3311   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3312   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3313 
3314   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3315   Abbv = std::make_shared<BitCodeAbbrev>();
3316   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3317   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3318   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3319   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3320   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3321   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3322   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3323 
3324   SmallVector<unsigned, 64> Vals;
3325   forEachModule(
3326       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3327         StringRef Key = MPSE.getKey();
3328         const auto &Value = MPSE.getValue();
3329         StringEncoding Bits = getStringEncoding(Key);
3330         unsigned AbbrevToUse = Abbrev8Bit;
3331         if (Bits == SE_Char6)
3332           AbbrevToUse = Abbrev6Bit;
3333         else if (Bits == SE_Fixed7)
3334           AbbrevToUse = Abbrev7Bit;
3335 
3336         Vals.push_back(Value.first);
3337         Vals.append(Key.begin(), Key.end());
3338 
3339         // Emit the finished record.
3340         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3341 
3342         // Emit an optional hash for the module now
3343         const auto &Hash = Value.second;
3344         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3345           Vals.assign(Hash.begin(), Hash.end());
3346           // Emit the hash record.
3347           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3348         }
3349 
3350         Vals.clear();
3351       });
3352   Stream.ExitBlock();
3353 }
3354 
3355 /// Write the function type metadata related records that need to appear before
3356 /// a function summary entry (whether per-module or combined).
3357 static void writeFunctionTypeMetadataRecords(
3358     BitstreamWriter &Stream, FunctionSummary *FS,
3359     std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3360   if (!FS->type_tests().empty()) {
3361     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3362     for (auto &TT : FS->type_tests())
3363       ReferencedTypeIds.insert(TT);
3364   }
3365 
3366   SmallVector<uint64_t, 64> Record;
3367 
3368   auto WriteVFuncIdVec = [&](uint64_t Ty,
3369                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3370     if (VFs.empty())
3371       return;
3372     Record.clear();
3373     for (auto &VF : VFs) {
3374       Record.push_back(VF.GUID);
3375       Record.push_back(VF.Offset);
3376       ReferencedTypeIds.insert(VF.GUID);
3377     }
3378     Stream.EmitRecord(Ty, Record);
3379   };
3380 
3381   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3382                   FS->type_test_assume_vcalls());
3383   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3384                   FS->type_checked_load_vcalls());
3385 
3386   auto WriteConstVCallVec = [&](uint64_t Ty,
3387                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3388     for (auto &VC : VCs) {
3389       Record.clear();
3390       Record.push_back(VC.VFunc.GUID);
3391       ReferencedTypeIds.insert(VC.VFunc.GUID);
3392       Record.push_back(VC.VFunc.Offset);
3393       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3394       Stream.EmitRecord(Ty, Record);
3395     }
3396   };
3397 
3398   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3399                      FS->type_test_assume_const_vcalls());
3400   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3401                      FS->type_checked_load_const_vcalls());
3402 }
3403 
3404 static void writeWholeProgramDevirtResolutionByArg(
3405     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3406     const WholeProgramDevirtResolution::ByArg &ByArg) {
3407   NameVals.push_back(args.size());
3408   NameVals.insert(NameVals.end(), args.begin(), args.end());
3409 
3410   NameVals.push_back(ByArg.TheKind);
3411   NameVals.push_back(ByArg.Info);
3412   NameVals.push_back(ByArg.Byte);
3413   NameVals.push_back(ByArg.Bit);
3414 }
3415 
3416 static void writeWholeProgramDevirtResolution(
3417     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3418     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3419   NameVals.push_back(Id);
3420 
3421   NameVals.push_back(Wpd.TheKind);
3422   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3423   NameVals.push_back(Wpd.SingleImplName.size());
3424 
3425   NameVals.push_back(Wpd.ResByArg.size());
3426   for (auto &A : Wpd.ResByArg)
3427     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3428 }
3429 
3430 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3431                                      StringTableBuilder &StrtabBuilder,
3432                                      const std::string &Id,
3433                                      const TypeIdSummary &Summary) {
3434   NameVals.push_back(StrtabBuilder.add(Id));
3435   NameVals.push_back(Id.size());
3436 
3437   NameVals.push_back(Summary.TTRes.TheKind);
3438   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3439   NameVals.push_back(Summary.TTRes.AlignLog2);
3440   NameVals.push_back(Summary.TTRes.SizeM1);
3441   NameVals.push_back(Summary.TTRes.BitMask);
3442   NameVals.push_back(Summary.TTRes.InlineBits);
3443 
3444   for (auto &W : Summary.WPDRes)
3445     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3446                                       W.second);
3447 }
3448 
3449 // Helper to emit a single function summary record.
3450 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3451     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3452     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3453     const Function &F) {
3454   NameVals.push_back(ValueID);
3455 
3456   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3457   std::set<GlobalValue::GUID> ReferencedTypeIds;
3458   writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3459 
3460   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3461   NameVals.push_back(FS->instCount());
3462   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3463   NameVals.push_back(FS->refs().size());
3464 
3465   for (auto &RI : FS->refs())
3466     NameVals.push_back(VE.getValueID(RI.getValue()));
3467 
3468   bool HasProfileData =
3469       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3470   for (auto &ECI : FS->calls()) {
3471     NameVals.push_back(getValueId(ECI.first));
3472     if (HasProfileData)
3473       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3474     else if (WriteRelBFToSummary)
3475       NameVals.push_back(ECI.second.RelBlockFreq);
3476   }
3477 
3478   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3479   unsigned Code =
3480       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3481                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3482                                              : bitc::FS_PERMODULE));
3483 
3484   // Emit the finished record.
3485   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3486   NameVals.clear();
3487 }
3488 
3489 // Collect the global value references in the given variable's initializer,
3490 // and emit them in a summary record.
3491 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3492     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3493     unsigned FSModRefsAbbrev) {
3494   auto VI = Index->getValueInfo(V.getGUID());
3495   if (!VI || VI.getSummaryList().empty()) {
3496     // Only declarations should not have a summary (a declaration might however
3497     // have a summary if the def was in module level asm).
3498     assert(V.isDeclaration());
3499     return;
3500   }
3501   auto *Summary = VI.getSummaryList()[0].get();
3502   NameVals.push_back(VE.getValueID(&V));
3503   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3504   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3505 
3506   unsigned SizeBeforeRefs = NameVals.size();
3507   for (auto &RI : VS->refs())
3508     NameVals.push_back(VE.getValueID(RI.getValue()));
3509   // Sort the refs for determinism output, the vector returned by FS->refs() has
3510   // been initialized from a DenseSet.
3511   llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3512 
3513   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3514                     FSModRefsAbbrev);
3515   NameVals.clear();
3516 }
3517 
3518 // Current version for the summary.
3519 // This is bumped whenever we introduce changes in the way some record are
3520 // interpreted, like flags for instance.
3521 static const uint64_t INDEX_VERSION = 4;
3522 
3523 /// Emit the per-module summary section alongside the rest of
3524 /// the module's bitcode.
3525 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3526   // By default we compile with ThinLTO if the module has a summary, but the
3527   // client can request full LTO with a module flag.
3528   bool IsThinLTO = true;
3529   if (auto *MD =
3530           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3531     IsThinLTO = MD->getZExtValue();
3532   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3533                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3534                        4);
3535 
3536   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3537 
3538   if (Index->begin() == Index->end()) {
3539     Stream.ExitBlock();
3540     return;
3541   }
3542 
3543   for (const auto &GVI : valueIds()) {
3544     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3545                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3546   }
3547 
3548   // Abbrev for FS_PERMODULE_PROFILE.
3549   auto Abbv = std::make_shared<BitCodeAbbrev>();
3550   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3551   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3552   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3553   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3556   // numrefs x valueid, n x (valueid, hotness)
3557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3558   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3559   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3560 
3561   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
3562   Abbv = std::make_shared<BitCodeAbbrev>();
3563   if (WriteRelBFToSummary)
3564     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
3565   else
3566     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3567   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3568   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3569   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3570   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3571   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3572   // numrefs x valueid, n x (valueid [, rel_block_freq])
3573   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3574   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3575   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3576 
3577   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3578   Abbv = std::make_shared<BitCodeAbbrev>();
3579   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3580   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3581   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3582   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3583   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3584   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3585 
3586   // Abbrev for FS_ALIAS.
3587   Abbv = std::make_shared<BitCodeAbbrev>();
3588   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3589   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3590   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3591   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3592   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3593 
3594   SmallVector<uint64_t, 64> NameVals;
3595   // Iterate over the list of functions instead of the Index to
3596   // ensure the ordering is stable.
3597   for (const Function &F : M) {
3598     // Summary emission does not support anonymous functions, they have to
3599     // renamed using the anonymous function renaming pass.
3600     if (!F.hasName())
3601       report_fatal_error("Unexpected anonymous function when writing summary");
3602 
3603     ValueInfo VI = Index->getValueInfo(F.getGUID());
3604     if (!VI || VI.getSummaryList().empty()) {
3605       // Only declarations should not have a summary (a declaration might
3606       // however have a summary if the def was in module level asm).
3607       assert(F.isDeclaration());
3608       continue;
3609     }
3610     auto *Summary = VI.getSummaryList()[0].get();
3611     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3612                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3613   }
3614 
3615   // Capture references from GlobalVariable initializers, which are outside
3616   // of a function scope.
3617   for (const GlobalVariable &G : M.globals())
3618     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3619 
3620   for (const GlobalAlias &A : M.aliases()) {
3621     auto *Aliasee = A.getBaseObject();
3622     if (!Aliasee->hasName())
3623       // Nameless function don't have an entry in the summary, skip it.
3624       continue;
3625     auto AliasId = VE.getValueID(&A);
3626     auto AliaseeId = VE.getValueID(Aliasee);
3627     NameVals.push_back(AliasId);
3628     auto *Summary = Index->getGlobalValueSummary(A);
3629     AliasSummary *AS = cast<AliasSummary>(Summary);
3630     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3631     NameVals.push_back(AliaseeId);
3632     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3633     NameVals.clear();
3634   }
3635 
3636   Stream.ExitBlock();
3637 }
3638 
3639 /// Emit the combined summary section into the combined index file.
3640 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3641   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3642   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3643 
3644   // Write the index flags.
3645   uint64_t Flags = 0;
3646   if (Index.withGlobalValueDeadStripping())
3647     Flags |= 0x1;
3648   if (Index.skipModuleByDistributedBackend())
3649     Flags |= 0x2;
3650   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
3651 
3652   for (const auto &GVI : valueIds()) {
3653     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3654                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3655   }
3656 
3657   // Abbrev for FS_COMBINED.
3658   auto Abbv = std::make_shared<BitCodeAbbrev>();
3659   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3660   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3661   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3662   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3663   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3664   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3665   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3666   // numrefs x valueid, n x (valueid)
3667   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3668   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3669   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3670 
3671   // Abbrev for FS_COMBINED_PROFILE.
3672   Abbv = std::make_shared<BitCodeAbbrev>();
3673   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3674   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3675   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3676   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3677   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3678   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3679   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3680   // numrefs x valueid, n x (valueid, hotness)
3681   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3682   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3683   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3684 
3685   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3686   Abbv = std::make_shared<BitCodeAbbrev>();
3687   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3688   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3689   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3690   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3691   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3692   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3693   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3694 
3695   // Abbrev for FS_COMBINED_ALIAS.
3696   Abbv = std::make_shared<BitCodeAbbrev>();
3697   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3698   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3699   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3700   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3701   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3702   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3703 
3704   // The aliases are emitted as a post-pass, and will point to the value
3705   // id of the aliasee. Save them in a vector for post-processing.
3706   SmallVector<AliasSummary *, 64> Aliases;
3707 
3708   // Save the value id for each summary for alias emission.
3709   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3710 
3711   SmallVector<uint64_t, 64> NameVals;
3712 
3713   // Set that will be populated during call to writeFunctionTypeMetadataRecords
3714   // with the type ids referenced by this index file.
3715   std::set<GlobalValue::GUID> ReferencedTypeIds;
3716 
3717   // For local linkage, we also emit the original name separately
3718   // immediately after the record.
3719   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3720     if (!GlobalValue::isLocalLinkage(S.linkage()))
3721       return;
3722     NameVals.push_back(S.getOriginalName());
3723     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3724     NameVals.clear();
3725   };
3726 
3727   forEachSummary([&](GVInfo I, bool IsAliasee) {
3728     GlobalValueSummary *S = I.second;
3729     assert(S);
3730 
3731     auto ValueId = getValueId(I.first);
3732     assert(ValueId);
3733     SummaryToValueIdMap[S] = *ValueId;
3734 
3735     // If this is invoked for an aliasee, we want to record the above
3736     // mapping, but then not emit a summary entry (if the aliasee is
3737     // to be imported, we will invoke this separately with IsAliasee=false).
3738     if (IsAliasee)
3739       return;
3740 
3741     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3742       // Will process aliases as a post-pass because the reader wants all
3743       // global to be loaded first.
3744       Aliases.push_back(AS);
3745       return;
3746     }
3747 
3748     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3749       NameVals.push_back(*ValueId);
3750       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3751       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3752       for (auto &RI : VS->refs()) {
3753         auto RefValueId = getValueId(RI.getGUID());
3754         if (!RefValueId)
3755           continue;
3756         NameVals.push_back(*RefValueId);
3757       }
3758 
3759       // Emit the finished record.
3760       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3761                         FSModRefsAbbrev);
3762       NameVals.clear();
3763       MaybeEmitOriginalName(*S);
3764       return;
3765     }
3766 
3767     auto *FS = cast<FunctionSummary>(S);
3768     writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3769 
3770     NameVals.push_back(*ValueId);
3771     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3772     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3773     NameVals.push_back(FS->instCount());
3774     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3775     // Fill in below
3776     NameVals.push_back(0);
3777 
3778     unsigned Count = 0;
3779     for (auto &RI : FS->refs()) {
3780       auto RefValueId = getValueId(RI.getGUID());
3781       if (!RefValueId)
3782         continue;
3783       NameVals.push_back(*RefValueId);
3784       Count++;
3785     }
3786     NameVals[5] = Count;
3787 
3788     bool HasProfileData = false;
3789     for (auto &EI : FS->calls()) {
3790       HasProfileData |=
3791           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
3792       if (HasProfileData)
3793         break;
3794     }
3795 
3796     for (auto &EI : FS->calls()) {
3797       // If this GUID doesn't have a value id, it doesn't have a function
3798       // summary and we don't need to record any calls to it.
3799       GlobalValue::GUID GUID = EI.first.getGUID();
3800       auto CallValueId = getValueId(GUID);
3801       if (!CallValueId) {
3802         // For SamplePGO, the indirect call targets for local functions will
3803         // have its original name annotated in profile. We try to find the
3804         // corresponding PGOFuncName as the GUID.
3805         GUID = Index.getGUIDFromOriginalID(GUID);
3806         if (GUID == 0)
3807           continue;
3808         CallValueId = getValueId(GUID);
3809         if (!CallValueId)
3810           continue;
3811         // The mapping from OriginalId to GUID may return a GUID
3812         // that corresponds to a static variable. Filter it out here.
3813         // This can happen when
3814         // 1) There is a call to a library function which does not have
3815         // a CallValidId;
3816         // 2) There is a static variable with the  OriginalGUID identical
3817         // to the GUID of the library function in 1);
3818         // When this happens, the logic for SamplePGO kicks in and
3819         // the static variable in 2) will be found, which needs to be
3820         // filtered out.
3821         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3822         if (GVSum &&
3823             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3824           continue;
3825       }
3826       NameVals.push_back(*CallValueId);
3827       if (HasProfileData)
3828         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3829     }
3830 
3831     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3832     unsigned Code =
3833         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3834 
3835     // Emit the finished record.
3836     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3837     NameVals.clear();
3838     MaybeEmitOriginalName(*S);
3839   });
3840 
3841   for (auto *AS : Aliases) {
3842     auto AliasValueId = SummaryToValueIdMap[AS];
3843     assert(AliasValueId);
3844     NameVals.push_back(AliasValueId);
3845     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3846     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3847     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3848     assert(AliaseeValueId);
3849     NameVals.push_back(AliaseeValueId);
3850 
3851     // Emit the finished record.
3852     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3853     NameVals.clear();
3854     MaybeEmitOriginalName(*AS);
3855   }
3856 
3857   if (!Index.cfiFunctionDefs().empty()) {
3858     for (auto &S : Index.cfiFunctionDefs()) {
3859       NameVals.push_back(StrtabBuilder.add(S));
3860       NameVals.push_back(S.size());
3861     }
3862     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3863     NameVals.clear();
3864   }
3865 
3866   if (!Index.cfiFunctionDecls().empty()) {
3867     for (auto &S : Index.cfiFunctionDecls()) {
3868       NameVals.push_back(StrtabBuilder.add(S));
3869       NameVals.push_back(S.size());
3870     }
3871     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3872     NameVals.clear();
3873   }
3874 
3875   if (!Index.typeIds().empty()) {
3876     for (auto &S : Index.typeIds()) {
3877       // Skip if not referenced in any GV summary within this index file.
3878       if (!ReferencedTypeIds.count(GlobalValue::getGUID(S.first)))
3879         continue;
3880       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, S.first, S.second);
3881       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
3882       NameVals.clear();
3883     }
3884   }
3885 
3886   Stream.ExitBlock();
3887 }
3888 
3889 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3890 /// current llvm version, and a record for the epoch number.
3891 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3892   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3893 
3894   // Write the "user readable" string identifying the bitcode producer
3895   auto Abbv = std::make_shared<BitCodeAbbrev>();
3896   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3897   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3898   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3899   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3900   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3901                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3902 
3903   // Write the epoch version
3904   Abbv = std::make_shared<BitCodeAbbrev>();
3905   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3906   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3907   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3908   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3909   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3910   Stream.ExitBlock();
3911 }
3912 
3913 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3914   // Emit the module's hash.
3915   // MODULE_CODE_HASH: [5*i32]
3916   if (GenerateHash) {
3917     uint32_t Vals[5];
3918     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3919                                     Buffer.size() - BlockStartPos));
3920     StringRef Hash = Hasher.result();
3921     for (int Pos = 0; Pos < 20; Pos += 4) {
3922       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3923     }
3924 
3925     // Emit the finished record.
3926     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3927 
3928     if (ModHash)
3929       // Save the written hash value.
3930       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3931   }
3932 }
3933 
3934 void ModuleBitcodeWriter::write() {
3935   writeIdentificationBlock(Stream);
3936 
3937   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3938   size_t BlockStartPos = Buffer.size();
3939 
3940   writeModuleVersion();
3941 
3942   // Emit blockinfo, which defines the standard abbreviations etc.
3943   writeBlockInfo();
3944 
3945   // Emit information about attribute groups.
3946   writeAttributeGroupTable();
3947 
3948   // Emit information about parameter attributes.
3949   writeAttributeTable();
3950 
3951   // Emit information describing all of the types in the module.
3952   writeTypeTable();
3953 
3954   writeComdats();
3955 
3956   // Emit top-level description of module, including target triple, inline asm,
3957   // descriptors for global variables, and function prototype info.
3958   writeModuleInfo();
3959 
3960   // Emit constants.
3961   writeModuleConstants();
3962 
3963   // Emit metadata kind names.
3964   writeModuleMetadataKinds();
3965 
3966   // Emit metadata.
3967   writeModuleMetadata();
3968 
3969   // Emit module-level use-lists.
3970   if (VE.shouldPreserveUseListOrder())
3971     writeUseListBlock(nullptr);
3972 
3973   writeOperandBundleTags();
3974   writeSyncScopeNames();
3975 
3976   // Emit function bodies.
3977   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3978   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3979     if (!F->isDeclaration())
3980       writeFunction(*F, FunctionToBitcodeIndex);
3981 
3982   // Need to write after the above call to WriteFunction which populates
3983   // the summary information in the index.
3984   if (Index)
3985     writePerModuleGlobalValueSummary();
3986 
3987   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3988 
3989   writeModuleHash(BlockStartPos);
3990 
3991   Stream.ExitBlock();
3992 }
3993 
3994 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3995                                uint32_t &Position) {
3996   support::endian::write32le(&Buffer[Position], Value);
3997   Position += 4;
3998 }
3999 
4000 /// If generating a bc file on darwin, we have to emit a
4001 /// header and trailer to make it compatible with the system archiver.  To do
4002 /// this we emit the following header, and then emit a trailer that pads the
4003 /// file out to be a multiple of 16 bytes.
4004 ///
4005 /// struct bc_header {
4006 ///   uint32_t Magic;         // 0x0B17C0DE
4007 ///   uint32_t Version;       // Version, currently always 0.
4008 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4009 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4010 ///   uint32_t CPUType;       // CPU specifier.
4011 ///   ... potentially more later ...
4012 /// };
4013 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4014                                          const Triple &TT) {
4015   unsigned CPUType = ~0U;
4016 
4017   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4018   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4019   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4020   // specific constants here because they are implicitly part of the Darwin ABI.
4021   enum {
4022     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4023     DARWIN_CPU_TYPE_X86        = 7,
4024     DARWIN_CPU_TYPE_ARM        = 12,
4025     DARWIN_CPU_TYPE_POWERPC    = 18
4026   };
4027 
4028   Triple::ArchType Arch = TT.getArch();
4029   if (Arch == Triple::x86_64)
4030     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4031   else if (Arch == Triple::x86)
4032     CPUType = DARWIN_CPU_TYPE_X86;
4033   else if (Arch == Triple::ppc)
4034     CPUType = DARWIN_CPU_TYPE_POWERPC;
4035   else if (Arch == Triple::ppc64)
4036     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4037   else if (Arch == Triple::arm || Arch == Triple::thumb)
4038     CPUType = DARWIN_CPU_TYPE_ARM;
4039 
4040   // Traditional Bitcode starts after header.
4041   assert(Buffer.size() >= BWH_HeaderSize &&
4042          "Expected header size to be reserved");
4043   unsigned BCOffset = BWH_HeaderSize;
4044   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4045 
4046   // Write the magic and version.
4047   unsigned Position = 0;
4048   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4049   writeInt32ToBuffer(0, Buffer, Position); // Version.
4050   writeInt32ToBuffer(BCOffset, Buffer, Position);
4051   writeInt32ToBuffer(BCSize, Buffer, Position);
4052   writeInt32ToBuffer(CPUType, Buffer, Position);
4053 
4054   // If the file is not a multiple of 16 bytes, insert dummy padding.
4055   while (Buffer.size() & 15)
4056     Buffer.push_back(0);
4057 }
4058 
4059 /// Helper to write the header common to all bitcode files.
4060 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4061   // Emit the file header.
4062   Stream.Emit((unsigned)'B', 8);
4063   Stream.Emit((unsigned)'C', 8);
4064   Stream.Emit(0x0, 4);
4065   Stream.Emit(0xC, 4);
4066   Stream.Emit(0xE, 4);
4067   Stream.Emit(0xD, 4);
4068 }
4069 
4070 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
4071     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
4072   writeBitcodeHeader(*Stream);
4073 }
4074 
4075 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4076 
4077 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4078   Stream->EnterSubblock(Block, 3);
4079 
4080   auto Abbv = std::make_shared<BitCodeAbbrev>();
4081   Abbv->Add(BitCodeAbbrevOp(Record));
4082   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4083   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4084 
4085   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4086 
4087   Stream->ExitBlock();
4088 }
4089 
4090 void BitcodeWriter::writeSymtab() {
4091   assert(!WroteStrtab && !WroteSymtab);
4092 
4093   // If any module has module-level inline asm, we will require a registered asm
4094   // parser for the target so that we can create an accurate symbol table for
4095   // the module.
4096   for (Module *M : Mods) {
4097     if (M->getModuleInlineAsm().empty())
4098       continue;
4099 
4100     std::string Err;
4101     const Triple TT(M->getTargetTriple());
4102     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4103     if (!T || !T->hasMCAsmParser())
4104       return;
4105   }
4106 
4107   WroteSymtab = true;
4108   SmallVector<char, 0> Symtab;
4109   // The irsymtab::build function may be unable to create a symbol table if the
4110   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4111   // table is not required for correctness, but we still want to be able to
4112   // write malformed modules to bitcode files, so swallow the error.
4113   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4114     consumeError(std::move(E));
4115     return;
4116   }
4117 
4118   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4119             {Symtab.data(), Symtab.size()});
4120 }
4121 
4122 void BitcodeWriter::writeStrtab() {
4123   assert(!WroteStrtab);
4124 
4125   std::vector<char> Strtab;
4126   StrtabBuilder.finalizeInOrder();
4127   Strtab.resize(StrtabBuilder.getSize());
4128   StrtabBuilder.write((uint8_t *)Strtab.data());
4129 
4130   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4131             {Strtab.data(), Strtab.size()});
4132 
4133   WroteStrtab = true;
4134 }
4135 
4136 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4137   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4138   WroteStrtab = true;
4139 }
4140 
4141 void BitcodeWriter::writeModule(const Module &M,
4142                                 bool ShouldPreserveUseListOrder,
4143                                 const ModuleSummaryIndex *Index,
4144                                 bool GenerateHash, ModuleHash *ModHash) {
4145   assert(!WroteStrtab);
4146 
4147   // The Mods vector is used by irsymtab::build, which requires non-const
4148   // Modules in case it needs to materialize metadata. But the bitcode writer
4149   // requires that the module is materialized, so we can cast to non-const here,
4150   // after checking that it is in fact materialized.
4151   assert(M.isMaterialized());
4152   Mods.push_back(const_cast<Module *>(&M));
4153 
4154   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4155                                    ShouldPreserveUseListOrder, Index,
4156                                    GenerateHash, ModHash);
4157   ModuleWriter.write();
4158 }
4159 
4160 void BitcodeWriter::writeIndex(
4161     const ModuleSummaryIndex *Index,
4162     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4163   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4164                                  ModuleToSummariesForIndex);
4165   IndexWriter.write();
4166 }
4167 
4168 /// Write the specified module to the specified output stream.
4169 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4170                               bool ShouldPreserveUseListOrder,
4171                               const ModuleSummaryIndex *Index,
4172                               bool GenerateHash, ModuleHash *ModHash) {
4173   SmallVector<char, 0> Buffer;
4174   Buffer.reserve(256*1024);
4175 
4176   // If this is darwin or another generic macho target, reserve space for the
4177   // header.
4178   Triple TT(M.getTargetTriple());
4179   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4180     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4181 
4182   BitcodeWriter Writer(Buffer);
4183   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4184                      ModHash);
4185   Writer.writeSymtab();
4186   Writer.writeStrtab();
4187 
4188   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4189     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4190 
4191   // Write the generated bitstream to "Out".
4192   Out.write((char*)&Buffer.front(), Buffer.size());
4193 }
4194 
4195 void IndexBitcodeWriter::write() {
4196   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4197 
4198   writeModuleVersion();
4199 
4200   // Write the module paths in the combined index.
4201   writeModStrings();
4202 
4203   // Write the summary combined index records.
4204   writeCombinedGlobalValueSummary();
4205 
4206   Stream.ExitBlock();
4207 }
4208 
4209 // Write the specified module summary index to the given raw output stream,
4210 // where it will be written in a new bitcode block. This is used when
4211 // writing the combined index file for ThinLTO. When writing a subset of the
4212 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4213 void llvm::WriteIndexToFile(
4214     const ModuleSummaryIndex &Index, raw_ostream &Out,
4215     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4216   SmallVector<char, 0> Buffer;
4217   Buffer.reserve(256 * 1024);
4218 
4219   BitcodeWriter Writer(Buffer);
4220   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4221   Writer.writeStrtab();
4222 
4223   Out.write((char *)&Buffer.front(), Buffer.size());
4224 }
4225 
4226 namespace {
4227 
4228 /// Class to manage the bitcode writing for a thin link bitcode file.
4229 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4230   /// ModHash is for use in ThinLTO incremental build, generated while writing
4231   /// the module bitcode file.
4232   const ModuleHash *ModHash;
4233 
4234 public:
4235   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4236                         BitstreamWriter &Stream,
4237                         const ModuleSummaryIndex &Index,
4238                         const ModuleHash &ModHash)
4239       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4240                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4241         ModHash(&ModHash) {}
4242 
4243   void write();
4244 
4245 private:
4246   void writeSimplifiedModuleInfo();
4247 };
4248 
4249 } // end anonymous namespace
4250 
4251 // This function writes a simpilified module info for thin link bitcode file.
4252 // It only contains the source file name along with the name(the offset and
4253 // size in strtab) and linkage for global values. For the global value info
4254 // entry, in order to keep linkage at offset 5, there are three zeros used
4255 // as padding.
4256 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4257   SmallVector<unsigned, 64> Vals;
4258   // Emit the module's source file name.
4259   {
4260     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4261     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4262     if (Bits == SE_Char6)
4263       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4264     else if (Bits == SE_Fixed7)
4265       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4266 
4267     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4268     auto Abbv = std::make_shared<BitCodeAbbrev>();
4269     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4270     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4271     Abbv->Add(AbbrevOpToUse);
4272     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4273 
4274     for (const auto P : M.getSourceFileName())
4275       Vals.push_back((unsigned char)P);
4276 
4277     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4278     Vals.clear();
4279   }
4280 
4281   // Emit the global variable information.
4282   for (const GlobalVariable &GV : M.globals()) {
4283     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4284     Vals.push_back(StrtabBuilder.add(GV.getName()));
4285     Vals.push_back(GV.getName().size());
4286     Vals.push_back(0);
4287     Vals.push_back(0);
4288     Vals.push_back(0);
4289     Vals.push_back(getEncodedLinkage(GV));
4290 
4291     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4292     Vals.clear();
4293   }
4294 
4295   // Emit the function proto information.
4296   for (const Function &F : M) {
4297     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4298     Vals.push_back(StrtabBuilder.add(F.getName()));
4299     Vals.push_back(F.getName().size());
4300     Vals.push_back(0);
4301     Vals.push_back(0);
4302     Vals.push_back(0);
4303     Vals.push_back(getEncodedLinkage(F));
4304 
4305     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4306     Vals.clear();
4307   }
4308 
4309   // Emit the alias information.
4310   for (const GlobalAlias &A : M.aliases()) {
4311     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4312     Vals.push_back(StrtabBuilder.add(A.getName()));
4313     Vals.push_back(A.getName().size());
4314     Vals.push_back(0);
4315     Vals.push_back(0);
4316     Vals.push_back(0);
4317     Vals.push_back(getEncodedLinkage(A));
4318 
4319     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4320     Vals.clear();
4321   }
4322 
4323   // Emit the ifunc information.
4324   for (const GlobalIFunc &I : M.ifuncs()) {
4325     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4326     Vals.push_back(StrtabBuilder.add(I.getName()));
4327     Vals.push_back(I.getName().size());
4328     Vals.push_back(0);
4329     Vals.push_back(0);
4330     Vals.push_back(0);
4331     Vals.push_back(getEncodedLinkage(I));
4332 
4333     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4334     Vals.clear();
4335   }
4336 }
4337 
4338 void ThinLinkBitcodeWriter::write() {
4339   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4340 
4341   writeModuleVersion();
4342 
4343   writeSimplifiedModuleInfo();
4344 
4345   writePerModuleGlobalValueSummary();
4346 
4347   // Write module hash.
4348   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4349 
4350   Stream.ExitBlock();
4351 }
4352 
4353 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4354                                          const ModuleSummaryIndex &Index,
4355                                          const ModuleHash &ModHash) {
4356   assert(!WroteStrtab);
4357 
4358   // The Mods vector is used by irsymtab::build, which requires non-const
4359   // Modules in case it needs to materialize metadata. But the bitcode writer
4360   // requires that the module is materialized, so we can cast to non-const here,
4361   // after checking that it is in fact materialized.
4362   assert(M.isMaterialized());
4363   Mods.push_back(const_cast<Module *>(&M));
4364 
4365   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4366                                        ModHash);
4367   ThinLinkWriter.write();
4368 }
4369 
4370 // Write the specified thin link bitcode file to the given raw output stream,
4371 // where it will be written in a new bitcode block. This is used when
4372 // writing the per-module index file for ThinLTO.
4373 void llvm::WriteThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4374                                       const ModuleSummaryIndex &Index,
4375                                       const ModuleHash &ModHash) {
4376   SmallVector<char, 0> Buffer;
4377   Buffer.reserve(256 * 1024);
4378 
4379   BitcodeWriter Writer(Buffer);
4380   Writer.writeThinLinkBitcode(M, Index, ModHash);
4381   Writer.writeSymtab();
4382   Writer.writeStrtab();
4383 
4384   Out.write((char *)&Buffer.front(), Buffer.size());
4385 }
4386