xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision e9754f0211076bab34e5a070cb8eb392a21c0540)
1 //===- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Bitcode writer implementation.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Bitcode/BitcodeWriter.h"
14 #include "ValueEnumerator.h"
15 #include "llvm/ADT/APFloat.h"
16 #include "llvm/ADT/APInt.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/None.h"
20 #include "llvm/ADT/Optional.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SetVector.h"
23 #include "llvm/ADT/SmallPtrSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringMap.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/Bitcode/BitcodeCommon.h"
30 #include "llvm/Bitcode/BitcodeReader.h"
31 #include "llvm/Bitcode/LLVMBitCodes.h"
32 #include "llvm/Bitstream/BitCodes.h"
33 #include "llvm/Bitstream/BitstreamWriter.h"
34 #include "llvm/Config/llvm-config.h"
35 #include "llvm/IR/Attributes.h"
36 #include "llvm/IR/BasicBlock.h"
37 #include "llvm/IR/Comdat.h"
38 #include "llvm/IR/Constant.h"
39 #include "llvm/IR/Constants.h"
40 #include "llvm/IR/DebugInfoMetadata.h"
41 #include "llvm/IR/DebugLoc.h"
42 #include "llvm/IR/DerivedTypes.h"
43 #include "llvm/IR/Function.h"
44 #include "llvm/IR/GlobalAlias.h"
45 #include "llvm/IR/GlobalIFunc.h"
46 #include "llvm/IR/GlobalObject.h"
47 #include "llvm/IR/GlobalValue.h"
48 #include "llvm/IR/GlobalVariable.h"
49 #include "llvm/IR/InlineAsm.h"
50 #include "llvm/IR/InstrTypes.h"
51 #include "llvm/IR/Instruction.h"
52 #include "llvm/IR/Instructions.h"
53 #include "llvm/IR/LLVMContext.h"
54 #include "llvm/IR/Metadata.h"
55 #include "llvm/IR/Module.h"
56 #include "llvm/IR/ModuleSummaryIndex.h"
57 #include "llvm/IR/Operator.h"
58 #include "llvm/IR/Type.h"
59 #include "llvm/IR/UseListOrder.h"
60 #include "llvm/IR/Value.h"
61 #include "llvm/IR/ValueSymbolTable.h"
62 #include "llvm/MC/StringTableBuilder.h"
63 #include "llvm/MC/TargetRegistry.h"
64 #include "llvm/Object/IRSymtab.h"
65 #include "llvm/Support/AtomicOrdering.h"
66 #include "llvm/Support/Casting.h"
67 #include "llvm/Support/CommandLine.h"
68 #include "llvm/Support/Endian.h"
69 #include "llvm/Support/Error.h"
70 #include "llvm/Support/ErrorHandling.h"
71 #include "llvm/Support/MathExtras.h"
72 #include "llvm/Support/SHA1.h"
73 #include "llvm/Support/raw_ostream.h"
74 #include <algorithm>
75 #include <cassert>
76 #include <cstddef>
77 #include <cstdint>
78 #include <iterator>
79 #include <map>
80 #include <memory>
81 #include <string>
82 #include <utility>
83 #include <vector>
84 
85 using namespace llvm;
86 
87 static cl::opt<unsigned>
88     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
89                    cl::desc("Number of metadatas above which we emit an index "
90                             "to enable lazy-loading"));
91 static cl::opt<uint32_t> FlushThreshold(
92     "bitcode-flush-threshold", cl::Hidden, cl::init(512),
93     cl::desc("The threshold (unit M) for flushing LLVM bitcode."));
94 
95 static cl::opt<bool> WriteRelBFToSummary(
96     "write-relbf-to-summary", cl::Hidden, cl::init(false),
97     cl::desc("Write relative block frequency to function summary "));
98 
99 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
100 
101 namespace {
102 
103 /// These are manifest constants used by the bitcode writer. They do not need to
104 /// be kept in sync with the reader, but need to be consistent within this file.
105 enum {
106   // VALUE_SYMTAB_BLOCK abbrev id's.
107   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
108   VST_ENTRY_7_ABBREV,
109   VST_ENTRY_6_ABBREV,
110   VST_BBENTRY_6_ABBREV,
111 
112   // CONSTANTS_BLOCK abbrev id's.
113   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
114   CONSTANTS_INTEGER_ABBREV,
115   CONSTANTS_CE_CAST_Abbrev,
116   CONSTANTS_NULL_Abbrev,
117 
118   // FUNCTION_BLOCK abbrev id's.
119   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
120   FUNCTION_INST_UNOP_ABBREV,
121   FUNCTION_INST_UNOP_FLAGS_ABBREV,
122   FUNCTION_INST_BINOP_ABBREV,
123   FUNCTION_INST_BINOP_FLAGS_ABBREV,
124   FUNCTION_INST_CAST_ABBREV,
125   FUNCTION_INST_RET_VOID_ABBREV,
126   FUNCTION_INST_RET_VAL_ABBREV,
127   FUNCTION_INST_UNREACHABLE_ABBREV,
128   FUNCTION_INST_GEP_ABBREV,
129 };
130 
131 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
132 /// file type.
133 class BitcodeWriterBase {
134 protected:
135   /// The stream created and owned by the client.
136   BitstreamWriter &Stream;
137 
138   StringTableBuilder &StrtabBuilder;
139 
140 public:
141   /// Constructs a BitcodeWriterBase object that writes to the provided
142   /// \p Stream.
143   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
144       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
145 
146 protected:
147   void writeModuleVersion();
148 };
149 
150 void BitcodeWriterBase::writeModuleVersion() {
151   // VERSION: [version#]
152   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
153 }
154 
155 /// Base class to manage the module bitcode writing, currently subclassed for
156 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
157 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
158 protected:
159   /// The Module to write to bitcode.
160   const Module &M;
161 
162   /// Enumerates ids for all values in the module.
163   ValueEnumerator VE;
164 
165   /// Optional per-module index to write for ThinLTO.
166   const ModuleSummaryIndex *Index;
167 
168   /// Map that holds the correspondence between GUIDs in the summary index,
169   /// that came from indirect call profiles, and a value id generated by this
170   /// class to use in the VST and summary block records.
171   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
172 
173   /// Tracks the last value id recorded in the GUIDToValueMap.
174   unsigned GlobalValueId;
175 
176   /// Saves the offset of the VSTOffset record that must eventually be
177   /// backpatched with the offset of the actual VST.
178   uint64_t VSTOffsetPlaceholder = 0;
179 
180 public:
181   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
182   /// writing to the provided \p Buffer.
183   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
184                           BitstreamWriter &Stream,
185                           bool ShouldPreserveUseListOrder,
186                           const ModuleSummaryIndex *Index)
187       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
188         VE(M, ShouldPreserveUseListOrder), Index(Index) {
189     // Assign ValueIds to any callee values in the index that came from
190     // indirect call profiles and were recorded as a GUID not a Value*
191     // (which would have been assigned an ID by the ValueEnumerator).
192     // The starting ValueId is just after the number of values in the
193     // ValueEnumerator, so that they can be emitted in the VST.
194     GlobalValueId = VE.getValues().size();
195     if (!Index)
196       return;
197     for (const auto &GUIDSummaryLists : *Index)
198       // Examine all summaries for this GUID.
199       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
200         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
201           // For each call in the function summary, see if the call
202           // is to a GUID (which means it is for an indirect call,
203           // otherwise we would have a Value for it). If so, synthesize
204           // a value id.
205           for (auto &CallEdge : FS->calls())
206             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
207               assignValueId(CallEdge.first.getGUID());
208   }
209 
210 protected:
211   void writePerModuleGlobalValueSummary();
212 
213 private:
214   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
215                                            GlobalValueSummary *Summary,
216                                            unsigned ValueID,
217                                            unsigned FSCallsAbbrev,
218                                            unsigned FSCallsProfileAbbrev,
219                                            const Function &F);
220   void writeModuleLevelReferences(const GlobalVariable &V,
221                                   SmallVector<uint64_t, 64> &NameVals,
222                                   unsigned FSModRefsAbbrev,
223                                   unsigned FSModVTableRefsAbbrev);
224 
225   void assignValueId(GlobalValue::GUID ValGUID) {
226     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
227   }
228 
229   unsigned getValueId(GlobalValue::GUID ValGUID) {
230     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
231     // Expect that any GUID value had a value Id assigned by an
232     // earlier call to assignValueId.
233     assert(VMI != GUIDToValueIdMap.end() &&
234            "GUID does not have assigned value Id");
235     return VMI->second;
236   }
237 
238   // Helper to get the valueId for the type of value recorded in VI.
239   unsigned getValueId(ValueInfo VI) {
240     if (!VI.haveGVs() || !VI.getValue())
241       return getValueId(VI.getGUID());
242     return VE.getValueID(VI.getValue());
243   }
244 
245   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
246 };
247 
248 /// Class to manage the bitcode writing for a module.
249 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
250   /// Pointer to the buffer allocated by caller for bitcode writing.
251   const SmallVectorImpl<char> &Buffer;
252 
253   /// True if a module hash record should be written.
254   bool GenerateHash;
255 
256   /// If non-null, when GenerateHash is true, the resulting hash is written
257   /// into ModHash.
258   ModuleHash *ModHash;
259 
260   SHA1 Hasher;
261 
262   /// The start bit of the identification block.
263   uint64_t BitcodeStartBit;
264 
265 public:
266   /// Constructs a ModuleBitcodeWriter object for the given Module,
267   /// writing to the provided \p Buffer.
268   ModuleBitcodeWriter(const Module &M, SmallVectorImpl<char> &Buffer,
269                       StringTableBuilder &StrtabBuilder,
270                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
271                       const ModuleSummaryIndex *Index, bool GenerateHash,
272                       ModuleHash *ModHash = nullptr)
273       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
274                                 ShouldPreserveUseListOrder, Index),
275         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
276         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
277 
278   /// Emit the current module to the bitstream.
279   void write();
280 
281 private:
282   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
283 
284   size_t addToStrtab(StringRef Str);
285 
286   void writeAttributeGroupTable();
287   void writeAttributeTable();
288   void writeTypeTable();
289   void writeComdats();
290   void writeValueSymbolTableForwardDecl();
291   void writeModuleInfo();
292   void writeValueAsMetadata(const ValueAsMetadata *MD,
293                             SmallVectorImpl<uint64_t> &Record);
294   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
295                     unsigned Abbrev);
296   unsigned createDILocationAbbrev();
297   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
298                        unsigned &Abbrev);
299   unsigned createGenericDINodeAbbrev();
300   void writeGenericDINode(const GenericDINode *N,
301                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
302   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
303                        unsigned Abbrev);
304   void writeDIGenericSubrange(const DIGenericSubrange *N,
305                               SmallVectorImpl<uint64_t> &Record,
306                               unsigned Abbrev);
307   void writeDIEnumerator(const DIEnumerator *N,
308                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
309   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
310                         unsigned Abbrev);
311   void writeDIStringType(const DIStringType *N,
312                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
313   void writeDIDerivedType(const DIDerivedType *N,
314                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
315   void writeDICompositeType(const DICompositeType *N,
316                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
317   void writeDISubroutineType(const DISubroutineType *N,
318                              SmallVectorImpl<uint64_t> &Record,
319                              unsigned Abbrev);
320   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
321                    unsigned Abbrev);
322   void writeDICompileUnit(const DICompileUnit *N,
323                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
324   void writeDISubprogram(const DISubprogram *N,
325                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
326   void writeDILexicalBlock(const DILexicalBlock *N,
327                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
328   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
329                                SmallVectorImpl<uint64_t> &Record,
330                                unsigned Abbrev);
331   void writeDICommonBlock(const DICommonBlock *N,
332                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
333   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
334                         unsigned Abbrev);
335   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
336                     unsigned Abbrev);
337   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
338                         unsigned Abbrev);
339   void writeDIArgList(const DIArgList *N, SmallVectorImpl<uint64_t> &Record,
340                       unsigned Abbrev);
341   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
342                      unsigned Abbrev);
343   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
344                                     SmallVectorImpl<uint64_t> &Record,
345                                     unsigned Abbrev);
346   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
347                                      SmallVectorImpl<uint64_t> &Record,
348                                      unsigned Abbrev);
349   void writeDIGlobalVariable(const DIGlobalVariable *N,
350                              SmallVectorImpl<uint64_t> &Record,
351                              unsigned Abbrev);
352   void writeDILocalVariable(const DILocalVariable *N,
353                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
354   void writeDILabel(const DILabel *N,
355                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
356   void writeDIExpression(const DIExpression *N,
357                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
358   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
359                                        SmallVectorImpl<uint64_t> &Record,
360                                        unsigned Abbrev);
361   void writeDIObjCProperty(const DIObjCProperty *N,
362                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
363   void writeDIImportedEntity(const DIImportedEntity *N,
364                              SmallVectorImpl<uint64_t> &Record,
365                              unsigned Abbrev);
366   unsigned createNamedMetadataAbbrev();
367   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
368   unsigned createMetadataStringsAbbrev();
369   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
370                             SmallVectorImpl<uint64_t> &Record);
371   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
372                             SmallVectorImpl<uint64_t> &Record,
373                             std::vector<unsigned> *MDAbbrevs = nullptr,
374                             std::vector<uint64_t> *IndexPos = nullptr);
375   void writeModuleMetadata();
376   void writeFunctionMetadata(const Function &F);
377   void writeFunctionMetadataAttachment(const Function &F);
378   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
379                                     const GlobalObject &GO);
380   void writeModuleMetadataKinds();
381   void writeOperandBundleTags();
382   void writeSyncScopeNames();
383   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
384   void writeModuleConstants();
385   bool pushValueAndType(const Value *V, unsigned InstID,
386                         SmallVectorImpl<unsigned> &Vals);
387   void writeOperandBundles(const CallBase &CB, unsigned InstID);
388   void pushValue(const Value *V, unsigned InstID,
389                  SmallVectorImpl<unsigned> &Vals);
390   void pushValueSigned(const Value *V, unsigned InstID,
391                        SmallVectorImpl<uint64_t> &Vals);
392   void writeInstruction(const Instruction &I, unsigned InstID,
393                         SmallVectorImpl<unsigned> &Vals);
394   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
395   void writeGlobalValueSymbolTable(
396       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
397   void writeUseList(UseListOrder &&Order);
398   void writeUseListBlock(const Function *F);
399   void
400   writeFunction(const Function &F,
401                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
402   void writeBlockInfo();
403   void writeModuleHash(size_t BlockStartPos);
404 
405   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
406     return unsigned(SSID);
407   }
408 
409   unsigned getEncodedAlign(MaybeAlign Alignment) { return encode(Alignment); }
410 };
411 
412 /// Class to manage the bitcode writing for a combined index.
413 class IndexBitcodeWriter : public BitcodeWriterBase {
414   /// The combined index to write to bitcode.
415   const ModuleSummaryIndex &Index;
416 
417   /// When writing a subset of the index for distributed backends, client
418   /// provides a map of modules to the corresponding GUIDs/summaries to write.
419   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
420 
421   /// Map that holds the correspondence between the GUID used in the combined
422   /// index and a value id generated by this class to use in references.
423   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
424 
425   /// Tracks the last value id recorded in the GUIDToValueMap.
426   unsigned GlobalValueId = 0;
427 
428 public:
429   /// Constructs a IndexBitcodeWriter object for the given combined index,
430   /// writing to the provided \p Buffer. When writing a subset of the index
431   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
432   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
433                      const ModuleSummaryIndex &Index,
434                      const std::map<std::string, GVSummaryMapTy>
435                          *ModuleToSummariesForIndex = nullptr)
436       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
437         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
438     // Assign unique value ids to all summaries to be written, for use
439     // in writing out the call graph edges. Save the mapping from GUID
440     // to the new global value id to use when writing those edges, which
441     // are currently saved in the index in terms of GUID.
442     forEachSummary([&](GVInfo I, bool) {
443       GUIDToValueIdMap[I.first] = ++GlobalValueId;
444     });
445   }
446 
447   /// The below iterator returns the GUID and associated summary.
448   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
449 
450   /// Calls the callback for each value GUID and summary to be written to
451   /// bitcode. This hides the details of whether they are being pulled from the
452   /// entire index or just those in a provided ModuleToSummariesForIndex map.
453   template<typename Functor>
454   void forEachSummary(Functor Callback) {
455     if (ModuleToSummariesForIndex) {
456       for (auto &M : *ModuleToSummariesForIndex)
457         for (auto &Summary : M.second) {
458           Callback(Summary, false);
459           // Ensure aliasee is handled, e.g. for assigning a valueId,
460           // even if we are not importing the aliasee directly (the
461           // imported alias will contain a copy of aliasee).
462           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
463             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
464         }
465     } else {
466       for (auto &Summaries : Index)
467         for (auto &Summary : Summaries.second.SummaryList)
468           Callback({Summaries.first, Summary.get()}, false);
469     }
470   }
471 
472   /// Calls the callback for each entry in the modulePaths StringMap that
473   /// should be written to the module path string table. This hides the details
474   /// of whether they are being pulled from the entire index or just those in a
475   /// provided ModuleToSummariesForIndex map.
476   template <typename Functor> void forEachModule(Functor Callback) {
477     if (ModuleToSummariesForIndex) {
478       for (const auto &M : *ModuleToSummariesForIndex) {
479         const auto &MPI = Index.modulePaths().find(M.first);
480         if (MPI == Index.modulePaths().end()) {
481           // This should only happen if the bitcode file was empty, in which
482           // case we shouldn't be importing (the ModuleToSummariesForIndex
483           // would only include the module we are writing and index for).
484           assert(ModuleToSummariesForIndex->size() == 1);
485           continue;
486         }
487         Callback(*MPI);
488       }
489     } else {
490       for (const auto &MPSE : Index.modulePaths())
491         Callback(MPSE);
492     }
493   }
494 
495   /// Main entry point for writing a combined index to bitcode.
496   void write();
497 
498 private:
499   void writeModStrings();
500   void writeCombinedGlobalValueSummary();
501 
502   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
503     auto VMI = GUIDToValueIdMap.find(ValGUID);
504     if (VMI == GUIDToValueIdMap.end())
505       return None;
506     return VMI->second;
507   }
508 
509   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
510 };
511 
512 } // end anonymous namespace
513 
514 static unsigned getEncodedCastOpcode(unsigned Opcode) {
515   switch (Opcode) {
516   default: llvm_unreachable("Unknown cast instruction!");
517   case Instruction::Trunc   : return bitc::CAST_TRUNC;
518   case Instruction::ZExt    : return bitc::CAST_ZEXT;
519   case Instruction::SExt    : return bitc::CAST_SEXT;
520   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
521   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
522   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
523   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
524   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
525   case Instruction::FPExt   : return bitc::CAST_FPEXT;
526   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
527   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
528   case Instruction::BitCast : return bitc::CAST_BITCAST;
529   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
530   }
531 }
532 
533 static unsigned getEncodedUnaryOpcode(unsigned Opcode) {
534   switch (Opcode) {
535   default: llvm_unreachable("Unknown binary instruction!");
536   case Instruction::FNeg: return bitc::UNOP_FNEG;
537   }
538 }
539 
540 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
541   switch (Opcode) {
542   default: llvm_unreachable("Unknown binary instruction!");
543   case Instruction::Add:
544   case Instruction::FAdd: return bitc::BINOP_ADD;
545   case Instruction::Sub:
546   case Instruction::FSub: return bitc::BINOP_SUB;
547   case Instruction::Mul:
548   case Instruction::FMul: return bitc::BINOP_MUL;
549   case Instruction::UDiv: return bitc::BINOP_UDIV;
550   case Instruction::FDiv:
551   case Instruction::SDiv: return bitc::BINOP_SDIV;
552   case Instruction::URem: return bitc::BINOP_UREM;
553   case Instruction::FRem:
554   case Instruction::SRem: return bitc::BINOP_SREM;
555   case Instruction::Shl:  return bitc::BINOP_SHL;
556   case Instruction::LShr: return bitc::BINOP_LSHR;
557   case Instruction::AShr: return bitc::BINOP_ASHR;
558   case Instruction::And:  return bitc::BINOP_AND;
559   case Instruction::Or:   return bitc::BINOP_OR;
560   case Instruction::Xor:  return bitc::BINOP_XOR;
561   }
562 }
563 
564 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
565   switch (Op) {
566   default: llvm_unreachable("Unknown RMW operation!");
567   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
568   case AtomicRMWInst::Add: return bitc::RMW_ADD;
569   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
570   case AtomicRMWInst::And: return bitc::RMW_AND;
571   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
572   case AtomicRMWInst::Or: return bitc::RMW_OR;
573   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
574   case AtomicRMWInst::Max: return bitc::RMW_MAX;
575   case AtomicRMWInst::Min: return bitc::RMW_MIN;
576   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
577   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
578   case AtomicRMWInst::FAdd: return bitc::RMW_FADD;
579   case AtomicRMWInst::FSub: return bitc::RMW_FSUB;
580   case AtomicRMWInst::FMax: return bitc::RMW_FMAX;
581   case AtomicRMWInst::FMin: return bitc::RMW_FMIN;
582   }
583 }
584 
585 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
586   switch (Ordering) {
587   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
588   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
589   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
590   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
591   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
592   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
593   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
594   }
595   llvm_unreachable("Invalid ordering");
596 }
597 
598 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
599                               StringRef Str, unsigned AbbrevToUse) {
600   SmallVector<unsigned, 64> Vals;
601 
602   // Code: [strchar x N]
603   for (char C : Str) {
604     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(C))
605       AbbrevToUse = 0;
606     Vals.push_back(C);
607   }
608 
609   // Emit the finished record.
610   Stream.EmitRecord(Code, Vals, AbbrevToUse);
611 }
612 
613 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
614   switch (Kind) {
615   case Attribute::Alignment:
616     return bitc::ATTR_KIND_ALIGNMENT;
617   case Attribute::AllocAlign:
618     return bitc::ATTR_KIND_ALLOC_ALIGN;
619   case Attribute::AllocSize:
620     return bitc::ATTR_KIND_ALLOC_SIZE;
621   case Attribute::AlwaysInline:
622     return bitc::ATTR_KIND_ALWAYS_INLINE;
623   case Attribute::ArgMemOnly:
624     return bitc::ATTR_KIND_ARGMEMONLY;
625   case Attribute::Builtin:
626     return bitc::ATTR_KIND_BUILTIN;
627   case Attribute::ByVal:
628     return bitc::ATTR_KIND_BY_VAL;
629   case Attribute::Convergent:
630     return bitc::ATTR_KIND_CONVERGENT;
631   case Attribute::InAlloca:
632     return bitc::ATTR_KIND_IN_ALLOCA;
633   case Attribute::Cold:
634     return bitc::ATTR_KIND_COLD;
635   case Attribute::DisableSanitizerInstrumentation:
636     return bitc::ATTR_KIND_DISABLE_SANITIZER_INSTRUMENTATION;
637   case Attribute::FnRetThunkExtern:
638     return bitc::ATTR_KIND_FNRETTHUNK_EXTERN;
639   case Attribute::Hot:
640     return bitc::ATTR_KIND_HOT;
641   case Attribute::ElementType:
642     return bitc::ATTR_KIND_ELEMENTTYPE;
643   case Attribute::InaccessibleMemOnly:
644     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
645   case Attribute::InaccessibleMemOrArgMemOnly:
646     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
647   case Attribute::InlineHint:
648     return bitc::ATTR_KIND_INLINE_HINT;
649   case Attribute::InReg:
650     return bitc::ATTR_KIND_IN_REG;
651   case Attribute::JumpTable:
652     return bitc::ATTR_KIND_JUMP_TABLE;
653   case Attribute::MinSize:
654     return bitc::ATTR_KIND_MIN_SIZE;
655   case Attribute::AllocatedPointer:
656     return bitc::ATTR_KIND_ALLOCATED_POINTER;
657   case Attribute::AllocKind:
658     return bitc::ATTR_KIND_ALLOC_KIND;
659   case Attribute::Memory:
660     return bitc::ATTR_KIND_MEMORY;
661   case Attribute::Naked:
662     return bitc::ATTR_KIND_NAKED;
663   case Attribute::Nest:
664     return bitc::ATTR_KIND_NEST;
665   case Attribute::NoAlias:
666     return bitc::ATTR_KIND_NO_ALIAS;
667   case Attribute::NoBuiltin:
668     return bitc::ATTR_KIND_NO_BUILTIN;
669   case Attribute::NoCallback:
670     return bitc::ATTR_KIND_NO_CALLBACK;
671   case Attribute::NoCapture:
672     return bitc::ATTR_KIND_NO_CAPTURE;
673   case Attribute::NoDuplicate:
674     return bitc::ATTR_KIND_NO_DUPLICATE;
675   case Attribute::NoFree:
676     return bitc::ATTR_KIND_NOFREE;
677   case Attribute::NoImplicitFloat:
678     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
679   case Attribute::NoInline:
680     return bitc::ATTR_KIND_NO_INLINE;
681   case Attribute::NoRecurse:
682     return bitc::ATTR_KIND_NO_RECURSE;
683   case Attribute::NoMerge:
684     return bitc::ATTR_KIND_NO_MERGE;
685   case Attribute::NonLazyBind:
686     return bitc::ATTR_KIND_NON_LAZY_BIND;
687   case Attribute::NonNull:
688     return bitc::ATTR_KIND_NON_NULL;
689   case Attribute::Dereferenceable:
690     return bitc::ATTR_KIND_DEREFERENCEABLE;
691   case Attribute::DereferenceableOrNull:
692     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
693   case Attribute::NoRedZone:
694     return bitc::ATTR_KIND_NO_RED_ZONE;
695   case Attribute::NoReturn:
696     return bitc::ATTR_KIND_NO_RETURN;
697   case Attribute::NoSync:
698     return bitc::ATTR_KIND_NOSYNC;
699   case Attribute::NoCfCheck:
700     return bitc::ATTR_KIND_NOCF_CHECK;
701   case Attribute::NoProfile:
702     return bitc::ATTR_KIND_NO_PROFILE;
703   case Attribute::SkipProfile:
704     return bitc::ATTR_KIND_SKIP_PROFILE;
705   case Attribute::NoUnwind:
706     return bitc::ATTR_KIND_NO_UNWIND;
707   case Attribute::NoSanitizeBounds:
708     return bitc::ATTR_KIND_NO_SANITIZE_BOUNDS;
709   case Attribute::NoSanitizeCoverage:
710     return bitc::ATTR_KIND_NO_SANITIZE_COVERAGE;
711   case Attribute::NullPointerIsValid:
712     return bitc::ATTR_KIND_NULL_POINTER_IS_VALID;
713   case Attribute::OptForFuzzing:
714     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
715   case Attribute::OptimizeForSize:
716     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
717   case Attribute::OptimizeNone:
718     return bitc::ATTR_KIND_OPTIMIZE_NONE;
719   case Attribute::ReadNone:
720     return bitc::ATTR_KIND_READ_NONE;
721   case Attribute::ReadOnly:
722     return bitc::ATTR_KIND_READ_ONLY;
723   case Attribute::Returned:
724     return bitc::ATTR_KIND_RETURNED;
725   case Attribute::ReturnsTwice:
726     return bitc::ATTR_KIND_RETURNS_TWICE;
727   case Attribute::SExt:
728     return bitc::ATTR_KIND_S_EXT;
729   case Attribute::Speculatable:
730     return bitc::ATTR_KIND_SPECULATABLE;
731   case Attribute::StackAlignment:
732     return bitc::ATTR_KIND_STACK_ALIGNMENT;
733   case Attribute::StackProtect:
734     return bitc::ATTR_KIND_STACK_PROTECT;
735   case Attribute::StackProtectReq:
736     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
737   case Attribute::StackProtectStrong:
738     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
739   case Attribute::SafeStack:
740     return bitc::ATTR_KIND_SAFESTACK;
741   case Attribute::ShadowCallStack:
742     return bitc::ATTR_KIND_SHADOWCALLSTACK;
743   case Attribute::StrictFP:
744     return bitc::ATTR_KIND_STRICT_FP;
745   case Attribute::StructRet:
746     return bitc::ATTR_KIND_STRUCT_RET;
747   case Attribute::SanitizeAddress:
748     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
749   case Attribute::SanitizeHWAddress:
750     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
751   case Attribute::SanitizeThread:
752     return bitc::ATTR_KIND_SANITIZE_THREAD;
753   case Attribute::SanitizeMemory:
754     return bitc::ATTR_KIND_SANITIZE_MEMORY;
755   case Attribute::SpeculativeLoadHardening:
756     return bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING;
757   case Attribute::SwiftError:
758     return bitc::ATTR_KIND_SWIFT_ERROR;
759   case Attribute::SwiftSelf:
760     return bitc::ATTR_KIND_SWIFT_SELF;
761   case Attribute::SwiftAsync:
762     return bitc::ATTR_KIND_SWIFT_ASYNC;
763   case Attribute::UWTable:
764     return bitc::ATTR_KIND_UW_TABLE;
765   case Attribute::VScaleRange:
766     return bitc::ATTR_KIND_VSCALE_RANGE;
767   case Attribute::WillReturn:
768     return bitc::ATTR_KIND_WILLRETURN;
769   case Attribute::WriteOnly:
770     return bitc::ATTR_KIND_WRITEONLY;
771   case Attribute::ZExt:
772     return bitc::ATTR_KIND_Z_EXT;
773   case Attribute::ImmArg:
774     return bitc::ATTR_KIND_IMMARG;
775   case Attribute::SanitizeMemTag:
776     return bitc::ATTR_KIND_SANITIZE_MEMTAG;
777   case Attribute::Preallocated:
778     return bitc::ATTR_KIND_PREALLOCATED;
779   case Attribute::NoUndef:
780     return bitc::ATTR_KIND_NOUNDEF;
781   case Attribute::ByRef:
782     return bitc::ATTR_KIND_BYREF;
783   case Attribute::MustProgress:
784     return bitc::ATTR_KIND_MUSTPROGRESS;
785   case Attribute::PresplitCoroutine:
786     return bitc::ATTR_KIND_PRESPLIT_COROUTINE;
787   case Attribute::EndAttrKinds:
788     llvm_unreachable("Can not encode end-attribute kinds marker.");
789   case Attribute::None:
790     llvm_unreachable("Can not encode none-attribute.");
791   case Attribute::EmptyKey:
792   case Attribute::TombstoneKey:
793     llvm_unreachable("Trying to encode EmptyKey/TombstoneKey");
794   }
795 
796   llvm_unreachable("Trying to encode unknown attribute");
797 }
798 
799 void ModuleBitcodeWriter::writeAttributeGroupTable() {
800   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
801       VE.getAttributeGroups();
802   if (AttrGrps.empty()) return;
803 
804   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
805 
806   SmallVector<uint64_t, 64> Record;
807   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
808     unsigned AttrListIndex = Pair.first;
809     AttributeSet AS = Pair.second;
810     Record.push_back(VE.getAttributeGroupID(Pair));
811     Record.push_back(AttrListIndex);
812 
813     for (Attribute Attr : AS) {
814       if (Attr.isEnumAttribute()) {
815         Record.push_back(0);
816         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
817       } else if (Attr.isIntAttribute()) {
818         Record.push_back(1);
819         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
820         Record.push_back(Attr.getValueAsInt());
821       } else if (Attr.isStringAttribute()) {
822         StringRef Kind = Attr.getKindAsString();
823         StringRef Val = Attr.getValueAsString();
824 
825         Record.push_back(Val.empty() ? 3 : 4);
826         Record.append(Kind.begin(), Kind.end());
827         Record.push_back(0);
828         if (!Val.empty()) {
829           Record.append(Val.begin(), Val.end());
830           Record.push_back(0);
831         }
832       } else {
833         assert(Attr.isTypeAttribute());
834         Type *Ty = Attr.getValueAsType();
835         Record.push_back(Ty ? 6 : 5);
836         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
837         if (Ty)
838           Record.push_back(VE.getTypeID(Attr.getValueAsType()));
839       }
840     }
841 
842     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
843     Record.clear();
844   }
845 
846   Stream.ExitBlock();
847 }
848 
849 void ModuleBitcodeWriter::writeAttributeTable() {
850   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
851   if (Attrs.empty()) return;
852 
853   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
854 
855   SmallVector<uint64_t, 64> Record;
856   for (const AttributeList &AL : Attrs) {
857     for (unsigned i : AL.indexes()) {
858       AttributeSet AS = AL.getAttributes(i);
859       if (AS.hasAttributes())
860         Record.push_back(VE.getAttributeGroupID({i, AS}));
861     }
862 
863     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
864     Record.clear();
865   }
866 
867   Stream.ExitBlock();
868 }
869 
870 /// WriteTypeTable - Write out the type table for a module.
871 void ModuleBitcodeWriter::writeTypeTable() {
872   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
873 
874   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
875   SmallVector<uint64_t, 64> TypeVals;
876 
877   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
878 
879   // Abbrev for TYPE_CODE_POINTER.
880   auto Abbv = std::make_shared<BitCodeAbbrev>();
881   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
882   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
883   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
884   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
885 
886   // Abbrev for TYPE_CODE_OPAQUE_POINTER.
887   Abbv = std::make_shared<BitCodeAbbrev>();
888   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_OPAQUE_POINTER));
889   Abbv->Add(BitCodeAbbrevOp(0)); // Addrspace = 0
890   unsigned OpaquePtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
891 
892   // Abbrev for TYPE_CODE_FUNCTION.
893   Abbv = std::make_shared<BitCodeAbbrev>();
894   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
895   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
896   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
897   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
898   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
899 
900   // Abbrev for TYPE_CODE_STRUCT_ANON.
901   Abbv = std::make_shared<BitCodeAbbrev>();
902   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
903   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
904   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
905   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
906   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
907 
908   // Abbrev for TYPE_CODE_STRUCT_NAME.
909   Abbv = std::make_shared<BitCodeAbbrev>();
910   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
911   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
912   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
913   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
914 
915   // Abbrev for TYPE_CODE_STRUCT_NAMED.
916   Abbv = std::make_shared<BitCodeAbbrev>();
917   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
918   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
919   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
920   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
921   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
922 
923   // Abbrev for TYPE_CODE_ARRAY.
924   Abbv = std::make_shared<BitCodeAbbrev>();
925   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
926   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
927   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
928   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
929 
930   // Emit an entry count so the reader can reserve space.
931   TypeVals.push_back(TypeList.size());
932   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
933   TypeVals.clear();
934 
935   // Loop over all of the types, emitting each in turn.
936   for (Type *T : TypeList) {
937     int AbbrevToUse = 0;
938     unsigned Code = 0;
939 
940     switch (T->getTypeID()) {
941     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
942     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
943     case Type::BFloatTyID:    Code = bitc::TYPE_CODE_BFLOAT;    break;
944     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
945     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
946     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
947     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
948     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
949     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
950     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
951     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
952     case Type::X86_AMXTyID:   Code = bitc::TYPE_CODE_X86_AMX;   break;
953     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
954     case Type::IntegerTyID:
955       // INTEGER: [width]
956       Code = bitc::TYPE_CODE_INTEGER;
957       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
958       break;
959     case Type::PointerTyID: {
960       PointerType *PTy = cast<PointerType>(T);
961       unsigned AddressSpace = PTy->getAddressSpace();
962       if (PTy->isOpaque()) {
963         // OPAQUE_POINTER: [address space]
964         Code = bitc::TYPE_CODE_OPAQUE_POINTER;
965         TypeVals.push_back(AddressSpace);
966         if (AddressSpace == 0)
967           AbbrevToUse = OpaquePtrAbbrev;
968       } else {
969         // POINTER: [pointee type, address space]
970         Code = bitc::TYPE_CODE_POINTER;
971         TypeVals.push_back(VE.getTypeID(PTy->getNonOpaquePointerElementType()));
972         TypeVals.push_back(AddressSpace);
973         if (AddressSpace == 0)
974           AbbrevToUse = PtrAbbrev;
975       }
976       break;
977     }
978     case Type::FunctionTyID: {
979       FunctionType *FT = cast<FunctionType>(T);
980       // FUNCTION: [isvararg, retty, paramty x N]
981       Code = bitc::TYPE_CODE_FUNCTION;
982       TypeVals.push_back(FT->isVarArg());
983       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
984       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
985         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
986       AbbrevToUse = FunctionAbbrev;
987       break;
988     }
989     case Type::StructTyID: {
990       StructType *ST = cast<StructType>(T);
991       // STRUCT: [ispacked, eltty x N]
992       TypeVals.push_back(ST->isPacked());
993       // Output all of the element types.
994       for (Type *ET : ST->elements())
995         TypeVals.push_back(VE.getTypeID(ET));
996 
997       if (ST->isLiteral()) {
998         Code = bitc::TYPE_CODE_STRUCT_ANON;
999         AbbrevToUse = StructAnonAbbrev;
1000       } else {
1001         if (ST->isOpaque()) {
1002           Code = bitc::TYPE_CODE_OPAQUE;
1003         } else {
1004           Code = bitc::TYPE_CODE_STRUCT_NAMED;
1005           AbbrevToUse = StructNamedAbbrev;
1006         }
1007 
1008         // Emit the name if it is present.
1009         if (!ST->getName().empty())
1010           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
1011                             StructNameAbbrev);
1012       }
1013       break;
1014     }
1015     case Type::ArrayTyID: {
1016       ArrayType *AT = cast<ArrayType>(T);
1017       // ARRAY: [numelts, eltty]
1018       Code = bitc::TYPE_CODE_ARRAY;
1019       TypeVals.push_back(AT->getNumElements());
1020       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
1021       AbbrevToUse = ArrayAbbrev;
1022       break;
1023     }
1024     case Type::FixedVectorTyID:
1025     case Type::ScalableVectorTyID: {
1026       VectorType *VT = cast<VectorType>(T);
1027       // VECTOR [numelts, eltty] or
1028       //        [numelts, eltty, scalable]
1029       Code = bitc::TYPE_CODE_VECTOR;
1030       TypeVals.push_back(VT->getElementCount().getKnownMinValue());
1031       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
1032       if (isa<ScalableVectorType>(VT))
1033         TypeVals.push_back(true);
1034       break;
1035     }
1036     case Type::TypedPointerTyID:
1037       llvm_unreachable("Typed pointers cannot be added to IR modules");
1038     }
1039 
1040     // Emit the finished record.
1041     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
1042     TypeVals.clear();
1043   }
1044 
1045   Stream.ExitBlock();
1046 }
1047 
1048 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
1049   switch (Linkage) {
1050   case GlobalValue::ExternalLinkage:
1051     return 0;
1052   case GlobalValue::WeakAnyLinkage:
1053     return 16;
1054   case GlobalValue::AppendingLinkage:
1055     return 2;
1056   case GlobalValue::InternalLinkage:
1057     return 3;
1058   case GlobalValue::LinkOnceAnyLinkage:
1059     return 18;
1060   case GlobalValue::ExternalWeakLinkage:
1061     return 7;
1062   case GlobalValue::CommonLinkage:
1063     return 8;
1064   case GlobalValue::PrivateLinkage:
1065     return 9;
1066   case GlobalValue::WeakODRLinkage:
1067     return 17;
1068   case GlobalValue::LinkOnceODRLinkage:
1069     return 19;
1070   case GlobalValue::AvailableExternallyLinkage:
1071     return 12;
1072   }
1073   llvm_unreachable("Invalid linkage");
1074 }
1075 
1076 static unsigned getEncodedLinkage(const GlobalValue &GV) {
1077   return getEncodedLinkage(GV.getLinkage());
1078 }
1079 
1080 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
1081   uint64_t RawFlags = 0;
1082   RawFlags |= Flags.ReadNone;
1083   RawFlags |= (Flags.ReadOnly << 1);
1084   RawFlags |= (Flags.NoRecurse << 2);
1085   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
1086   RawFlags |= (Flags.NoInline << 4);
1087   RawFlags |= (Flags.AlwaysInline << 5);
1088   RawFlags |= (Flags.NoUnwind << 6);
1089   RawFlags |= (Flags.MayThrow << 7);
1090   RawFlags |= (Flags.HasUnknownCall << 8);
1091   RawFlags |= (Flags.MustBeUnreachable << 9);
1092   return RawFlags;
1093 }
1094 
1095 // Decode the flags for GlobalValue in the summary. See getDecodedGVSummaryFlags
1096 // in BitcodeReader.cpp.
1097 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
1098   uint64_t RawFlags = 0;
1099 
1100   RawFlags |= Flags.NotEligibleToImport; // bool
1101   RawFlags |= (Flags.Live << 1);
1102   RawFlags |= (Flags.DSOLocal << 2);
1103   RawFlags |= (Flags.CanAutoHide << 3);
1104 
1105   // Linkage don't need to be remapped at that time for the summary. Any future
1106   // change to the getEncodedLinkage() function will need to be taken into
1107   // account here as well.
1108   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
1109 
1110   RawFlags |= (Flags.Visibility << 8); // 2 bits
1111 
1112   return RawFlags;
1113 }
1114 
1115 static uint64_t getEncodedGVarFlags(GlobalVarSummary::GVarFlags Flags) {
1116   uint64_t RawFlags = Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) |
1117                       (Flags.Constant << 2) | Flags.VCallVisibility << 3;
1118   return RawFlags;
1119 }
1120 
1121 static unsigned getEncodedVisibility(const GlobalValue &GV) {
1122   switch (GV.getVisibility()) {
1123   case GlobalValue::DefaultVisibility:   return 0;
1124   case GlobalValue::HiddenVisibility:    return 1;
1125   case GlobalValue::ProtectedVisibility: return 2;
1126   }
1127   llvm_unreachable("Invalid visibility");
1128 }
1129 
1130 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1131   switch (GV.getDLLStorageClass()) {
1132   case GlobalValue::DefaultStorageClass:   return 0;
1133   case GlobalValue::DLLImportStorageClass: return 1;
1134   case GlobalValue::DLLExportStorageClass: return 2;
1135   }
1136   llvm_unreachable("Invalid DLL storage class");
1137 }
1138 
1139 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1140   switch (GV.getThreadLocalMode()) {
1141     case GlobalVariable::NotThreadLocal:         return 0;
1142     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1143     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1144     case GlobalVariable::InitialExecTLSModel:    return 3;
1145     case GlobalVariable::LocalExecTLSModel:      return 4;
1146   }
1147   llvm_unreachable("Invalid TLS model");
1148 }
1149 
1150 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1151   switch (C.getSelectionKind()) {
1152   case Comdat::Any:
1153     return bitc::COMDAT_SELECTION_KIND_ANY;
1154   case Comdat::ExactMatch:
1155     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1156   case Comdat::Largest:
1157     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1158   case Comdat::NoDeduplicate:
1159     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1160   case Comdat::SameSize:
1161     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1162   }
1163   llvm_unreachable("Invalid selection kind");
1164 }
1165 
1166 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1167   switch (GV.getUnnamedAddr()) {
1168   case GlobalValue::UnnamedAddr::None:   return 0;
1169   case GlobalValue::UnnamedAddr::Local:  return 2;
1170   case GlobalValue::UnnamedAddr::Global: return 1;
1171   }
1172   llvm_unreachable("Invalid unnamed_addr");
1173 }
1174 
1175 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1176   if (GenerateHash)
1177     Hasher.update(Str);
1178   return StrtabBuilder.add(Str);
1179 }
1180 
1181 void ModuleBitcodeWriter::writeComdats() {
1182   SmallVector<unsigned, 64> Vals;
1183   for (const Comdat *C : VE.getComdats()) {
1184     // COMDAT: [strtab offset, strtab size, selection_kind]
1185     Vals.push_back(addToStrtab(C->getName()));
1186     Vals.push_back(C->getName().size());
1187     Vals.push_back(getEncodedComdatSelectionKind(*C));
1188     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1189     Vals.clear();
1190   }
1191 }
1192 
1193 /// Write a record that will eventually hold the word offset of the
1194 /// module-level VST. For now the offset is 0, which will be backpatched
1195 /// after the real VST is written. Saves the bit offset to backpatch.
1196 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1197   // Write a placeholder value in for the offset of the real VST,
1198   // which is written after the function blocks so that it can include
1199   // the offset of each function. The placeholder offset will be
1200   // updated when the real VST is written.
1201   auto Abbv = std::make_shared<BitCodeAbbrev>();
1202   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1203   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1204   // hold the real VST offset. Must use fixed instead of VBR as we don't
1205   // know how many VBR chunks to reserve ahead of time.
1206   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1207   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1208 
1209   // Emit the placeholder
1210   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1211   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1212 
1213   // Compute and save the bit offset to the placeholder, which will be
1214   // patched when the real VST is written. We can simply subtract the 32-bit
1215   // fixed size from the current bit number to get the location to backpatch.
1216   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1217 }
1218 
1219 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1220 
1221 /// Determine the encoding to use for the given string name and length.
1222 static StringEncoding getStringEncoding(StringRef Str) {
1223   bool isChar6 = true;
1224   for (char C : Str) {
1225     if (isChar6)
1226       isChar6 = BitCodeAbbrevOp::isChar6(C);
1227     if ((unsigned char)C & 128)
1228       // don't bother scanning the rest.
1229       return SE_Fixed8;
1230   }
1231   if (isChar6)
1232     return SE_Char6;
1233   return SE_Fixed7;
1234 }
1235 
1236 static_assert(sizeof(GlobalValue::SanitizerMetadata) <= sizeof(unsigned),
1237               "Sanitizer Metadata is too large for naive serialization.");
1238 static unsigned
1239 serializeSanitizerMetadata(const GlobalValue::SanitizerMetadata &Meta) {
1240   return Meta.NoAddress | (Meta.NoHWAddress << 1) |
1241          (Meta.Memtag << 2) | (Meta.IsDynInit << 3);
1242 }
1243 
1244 /// Emit top-level description of module, including target triple, inline asm,
1245 /// descriptors for global variables, and function prototype info.
1246 /// Returns the bit offset to backpatch with the location of the real VST.
1247 void ModuleBitcodeWriter::writeModuleInfo() {
1248   // Emit various pieces of data attached to a module.
1249   if (!M.getTargetTriple().empty())
1250     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1251                       0 /*TODO*/);
1252   const std::string &DL = M.getDataLayoutStr();
1253   if (!DL.empty())
1254     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1255   if (!M.getModuleInlineAsm().empty())
1256     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1257                       0 /*TODO*/);
1258 
1259   // Emit information about sections and GC, computing how many there are. Also
1260   // compute the maximum alignment value.
1261   std::map<std::string, unsigned> SectionMap;
1262   std::map<std::string, unsigned> GCMap;
1263   MaybeAlign MaxAlignment;
1264   unsigned MaxGlobalType = 0;
1265   const auto UpdateMaxAlignment = [&MaxAlignment](const MaybeAlign A) {
1266     if (A)
1267       MaxAlignment = !MaxAlignment ? *A : std::max(*MaxAlignment, *A);
1268   };
1269   for (const GlobalVariable &GV : M.globals()) {
1270     UpdateMaxAlignment(GV.getAlign());
1271     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1272     if (GV.hasSection()) {
1273       // Give section names unique ID's.
1274       unsigned &Entry = SectionMap[std::string(GV.getSection())];
1275       if (!Entry) {
1276         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1277                           0 /*TODO*/);
1278         Entry = SectionMap.size();
1279       }
1280     }
1281   }
1282   for (const Function &F : M) {
1283     UpdateMaxAlignment(F.getAlign());
1284     if (F.hasSection()) {
1285       // Give section names unique ID's.
1286       unsigned &Entry = SectionMap[std::string(F.getSection())];
1287       if (!Entry) {
1288         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1289                           0 /*TODO*/);
1290         Entry = SectionMap.size();
1291       }
1292     }
1293     if (F.hasGC()) {
1294       // Same for GC names.
1295       unsigned &Entry = GCMap[F.getGC()];
1296       if (!Entry) {
1297         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1298                           0 /*TODO*/);
1299         Entry = GCMap.size();
1300       }
1301     }
1302   }
1303 
1304   // Emit abbrev for globals, now that we know # sections and max alignment.
1305   unsigned SimpleGVarAbbrev = 0;
1306   if (!M.global_empty()) {
1307     // Add an abbrev for common globals with no visibility or thread localness.
1308     auto Abbv = std::make_shared<BitCodeAbbrev>();
1309     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1310     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1311     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1313                               Log2_32_Ceil(MaxGlobalType+1)));
1314     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1315                                                            //| explicitType << 1
1316                                                            //| constant
1317     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1318     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1319     if (!MaxAlignment)                                     // Alignment.
1320       Abbv->Add(BitCodeAbbrevOp(0));
1321     else {
1322       unsigned MaxEncAlignment = getEncodedAlign(MaxAlignment);
1323       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1324                                Log2_32_Ceil(MaxEncAlignment+1)));
1325     }
1326     if (SectionMap.empty())                                    // Section.
1327       Abbv->Add(BitCodeAbbrevOp(0));
1328     else
1329       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1330                                Log2_32_Ceil(SectionMap.size()+1)));
1331     // Don't bother emitting vis + thread local.
1332     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1333   }
1334 
1335   SmallVector<unsigned, 64> Vals;
1336   // Emit the module's source file name.
1337   {
1338     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1339     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1340     if (Bits == SE_Char6)
1341       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1342     else if (Bits == SE_Fixed7)
1343       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1344 
1345     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1346     auto Abbv = std::make_shared<BitCodeAbbrev>();
1347     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1348     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1349     Abbv->Add(AbbrevOpToUse);
1350     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1351 
1352     for (const auto P : M.getSourceFileName())
1353       Vals.push_back((unsigned char)P);
1354 
1355     // Emit the finished record.
1356     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1357     Vals.clear();
1358   }
1359 
1360   // Emit the global variable information.
1361   for (const GlobalVariable &GV : M.globals()) {
1362     unsigned AbbrevToUse = 0;
1363 
1364     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1365     //             linkage, alignment, section, visibility, threadlocal,
1366     //             unnamed_addr, externally_initialized, dllstorageclass,
1367     //             comdat, attributes, DSO_Local, GlobalSanitizer]
1368     Vals.push_back(addToStrtab(GV.getName()));
1369     Vals.push_back(GV.getName().size());
1370     Vals.push_back(VE.getTypeID(GV.getValueType()));
1371     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1372     Vals.push_back(GV.isDeclaration() ? 0 :
1373                    (VE.getValueID(GV.getInitializer()) + 1));
1374     Vals.push_back(getEncodedLinkage(GV));
1375     Vals.push_back(getEncodedAlign(GV.getAlign()));
1376     Vals.push_back(GV.hasSection() ? SectionMap[std::string(GV.getSection())]
1377                                    : 0);
1378     if (GV.isThreadLocal() ||
1379         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1380         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1381         GV.isExternallyInitialized() ||
1382         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1383         GV.hasComdat() || GV.hasAttributes() || GV.isDSOLocal() ||
1384         GV.hasPartition() || GV.hasSanitizerMetadata()) {
1385       Vals.push_back(getEncodedVisibility(GV));
1386       Vals.push_back(getEncodedThreadLocalMode(GV));
1387       Vals.push_back(getEncodedUnnamedAddr(GV));
1388       Vals.push_back(GV.isExternallyInitialized());
1389       Vals.push_back(getEncodedDLLStorageClass(GV));
1390       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1391 
1392       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1393       Vals.push_back(VE.getAttributeListID(AL));
1394 
1395       Vals.push_back(GV.isDSOLocal());
1396       Vals.push_back(addToStrtab(GV.getPartition()));
1397       Vals.push_back(GV.getPartition().size());
1398 
1399       Vals.push_back((GV.hasSanitizerMetadata() ? serializeSanitizerMetadata(
1400                                                       GV.getSanitizerMetadata())
1401                                                 : 0));
1402     } else {
1403       AbbrevToUse = SimpleGVarAbbrev;
1404     }
1405 
1406     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1407     Vals.clear();
1408   }
1409 
1410   // Emit the function proto information.
1411   for (const Function &F : M) {
1412     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1413     //             linkage, paramattrs, alignment, section, visibility, gc,
1414     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1415     //             prefixdata, personalityfn, DSO_Local, addrspace]
1416     Vals.push_back(addToStrtab(F.getName()));
1417     Vals.push_back(F.getName().size());
1418     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1419     Vals.push_back(F.getCallingConv());
1420     Vals.push_back(F.isDeclaration());
1421     Vals.push_back(getEncodedLinkage(F));
1422     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1423     Vals.push_back(getEncodedAlign(F.getAlign()));
1424     Vals.push_back(F.hasSection() ? SectionMap[std::string(F.getSection())]
1425                                   : 0);
1426     Vals.push_back(getEncodedVisibility(F));
1427     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1428     Vals.push_back(getEncodedUnnamedAddr(F));
1429     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1430                                        : 0);
1431     Vals.push_back(getEncodedDLLStorageClass(F));
1432     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1433     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1434                                      : 0);
1435     Vals.push_back(
1436         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1437 
1438     Vals.push_back(F.isDSOLocal());
1439     Vals.push_back(F.getAddressSpace());
1440     Vals.push_back(addToStrtab(F.getPartition()));
1441     Vals.push_back(F.getPartition().size());
1442 
1443     unsigned AbbrevToUse = 0;
1444     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1445     Vals.clear();
1446   }
1447 
1448   // Emit the alias information.
1449   for (const GlobalAlias &A : M.aliases()) {
1450     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1451     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1452     //         DSO_Local]
1453     Vals.push_back(addToStrtab(A.getName()));
1454     Vals.push_back(A.getName().size());
1455     Vals.push_back(VE.getTypeID(A.getValueType()));
1456     Vals.push_back(A.getType()->getAddressSpace());
1457     Vals.push_back(VE.getValueID(A.getAliasee()));
1458     Vals.push_back(getEncodedLinkage(A));
1459     Vals.push_back(getEncodedVisibility(A));
1460     Vals.push_back(getEncodedDLLStorageClass(A));
1461     Vals.push_back(getEncodedThreadLocalMode(A));
1462     Vals.push_back(getEncodedUnnamedAddr(A));
1463     Vals.push_back(A.isDSOLocal());
1464     Vals.push_back(addToStrtab(A.getPartition()));
1465     Vals.push_back(A.getPartition().size());
1466 
1467     unsigned AbbrevToUse = 0;
1468     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1469     Vals.clear();
1470   }
1471 
1472   // Emit the ifunc information.
1473   for (const GlobalIFunc &I : M.ifuncs()) {
1474     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1475     //         val#, linkage, visibility, DSO_Local]
1476     Vals.push_back(addToStrtab(I.getName()));
1477     Vals.push_back(I.getName().size());
1478     Vals.push_back(VE.getTypeID(I.getValueType()));
1479     Vals.push_back(I.getType()->getAddressSpace());
1480     Vals.push_back(VE.getValueID(I.getResolver()));
1481     Vals.push_back(getEncodedLinkage(I));
1482     Vals.push_back(getEncodedVisibility(I));
1483     Vals.push_back(I.isDSOLocal());
1484     Vals.push_back(addToStrtab(I.getPartition()));
1485     Vals.push_back(I.getPartition().size());
1486     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1487     Vals.clear();
1488   }
1489 
1490   writeValueSymbolTableForwardDecl();
1491 }
1492 
1493 static uint64_t getOptimizationFlags(const Value *V) {
1494   uint64_t Flags = 0;
1495 
1496   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1497     if (OBO->hasNoSignedWrap())
1498       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1499     if (OBO->hasNoUnsignedWrap())
1500       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1501   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1502     if (PEO->isExact())
1503       Flags |= 1 << bitc::PEO_EXACT;
1504   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1505     if (FPMO->hasAllowReassoc())
1506       Flags |= bitc::AllowReassoc;
1507     if (FPMO->hasNoNaNs())
1508       Flags |= bitc::NoNaNs;
1509     if (FPMO->hasNoInfs())
1510       Flags |= bitc::NoInfs;
1511     if (FPMO->hasNoSignedZeros())
1512       Flags |= bitc::NoSignedZeros;
1513     if (FPMO->hasAllowReciprocal())
1514       Flags |= bitc::AllowReciprocal;
1515     if (FPMO->hasAllowContract())
1516       Flags |= bitc::AllowContract;
1517     if (FPMO->hasApproxFunc())
1518       Flags |= bitc::ApproxFunc;
1519   }
1520 
1521   return Flags;
1522 }
1523 
1524 void ModuleBitcodeWriter::writeValueAsMetadata(
1525     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1526   // Mimic an MDNode with a value as one operand.
1527   Value *V = MD->getValue();
1528   Record.push_back(VE.getTypeID(V->getType()));
1529   Record.push_back(VE.getValueID(V));
1530   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1531   Record.clear();
1532 }
1533 
1534 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1535                                        SmallVectorImpl<uint64_t> &Record,
1536                                        unsigned Abbrev) {
1537   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1538     Metadata *MD = N->getOperand(i);
1539     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1540            "Unexpected function-local metadata");
1541     Record.push_back(VE.getMetadataOrNullID(MD));
1542   }
1543   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1544                                     : bitc::METADATA_NODE,
1545                     Record, Abbrev);
1546   Record.clear();
1547 }
1548 
1549 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1550   // Assume the column is usually under 128, and always output the inlined-at
1551   // location (it's never more expensive than building an array size 1).
1552   auto Abbv = std::make_shared<BitCodeAbbrev>();
1553   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1556   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1558   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1559   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1560   return Stream.EmitAbbrev(std::move(Abbv));
1561 }
1562 
1563 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1564                                           SmallVectorImpl<uint64_t> &Record,
1565                                           unsigned &Abbrev) {
1566   if (!Abbrev)
1567     Abbrev = createDILocationAbbrev();
1568 
1569   Record.push_back(N->isDistinct());
1570   Record.push_back(N->getLine());
1571   Record.push_back(N->getColumn());
1572   Record.push_back(VE.getMetadataID(N->getScope()));
1573   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1574   Record.push_back(N->isImplicitCode());
1575 
1576   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1577   Record.clear();
1578 }
1579 
1580 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1581   // Assume the column is usually under 128, and always output the inlined-at
1582   // location (it's never more expensive than building an array size 1).
1583   auto Abbv = std::make_shared<BitCodeAbbrev>();
1584   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1585   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1586   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1587   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1588   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1589   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1590   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1591   return Stream.EmitAbbrev(std::move(Abbv));
1592 }
1593 
1594 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1595                                              SmallVectorImpl<uint64_t> &Record,
1596                                              unsigned &Abbrev) {
1597   if (!Abbrev)
1598     Abbrev = createGenericDINodeAbbrev();
1599 
1600   Record.push_back(N->isDistinct());
1601   Record.push_back(N->getTag());
1602   Record.push_back(0); // Per-tag version field; unused for now.
1603 
1604   for (auto &I : N->operands())
1605     Record.push_back(VE.getMetadataOrNullID(I));
1606 
1607   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1608   Record.clear();
1609 }
1610 
1611 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1612                                           SmallVectorImpl<uint64_t> &Record,
1613                                           unsigned Abbrev) {
1614   const uint64_t Version = 2 << 1;
1615   Record.push_back((uint64_t)N->isDistinct() | Version);
1616   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1617   Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
1618   Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
1619   Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
1620 
1621   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1622   Record.clear();
1623 }
1624 
1625 void ModuleBitcodeWriter::writeDIGenericSubrange(
1626     const DIGenericSubrange *N, SmallVectorImpl<uint64_t> &Record,
1627     unsigned Abbrev) {
1628   Record.push_back((uint64_t)N->isDistinct());
1629   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1630   Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
1631   Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
1632   Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
1633 
1634   Stream.EmitRecord(bitc::METADATA_GENERIC_SUBRANGE, Record, Abbrev);
1635   Record.clear();
1636 }
1637 
1638 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1639   if ((int64_t)V >= 0)
1640     Vals.push_back(V << 1);
1641   else
1642     Vals.push_back((-V << 1) | 1);
1643 }
1644 
1645 static void emitWideAPInt(SmallVectorImpl<uint64_t> &Vals, const APInt &A) {
1646   // We have an arbitrary precision integer value to write whose
1647   // bit width is > 64. However, in canonical unsigned integer
1648   // format it is likely that the high bits are going to be zero.
1649   // So, we only write the number of active words.
1650   unsigned NumWords = A.getActiveWords();
1651   const uint64_t *RawData = A.getRawData();
1652   for (unsigned i = 0; i < NumWords; i++)
1653     emitSignedInt64(Vals, RawData[i]);
1654 }
1655 
1656 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1657                                             SmallVectorImpl<uint64_t> &Record,
1658                                             unsigned Abbrev) {
1659   const uint64_t IsBigInt = 1 << 2;
1660   Record.push_back(IsBigInt | (N->isUnsigned() << 1) | N->isDistinct());
1661   Record.push_back(N->getValue().getBitWidth());
1662   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1663   emitWideAPInt(Record, N->getValue());
1664 
1665   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1666   Record.clear();
1667 }
1668 
1669 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1670                                            SmallVectorImpl<uint64_t> &Record,
1671                                            unsigned Abbrev) {
1672   Record.push_back(N->isDistinct());
1673   Record.push_back(N->getTag());
1674   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1675   Record.push_back(N->getSizeInBits());
1676   Record.push_back(N->getAlignInBits());
1677   Record.push_back(N->getEncoding());
1678   Record.push_back(N->getFlags());
1679 
1680   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1681   Record.clear();
1682 }
1683 
1684 void ModuleBitcodeWriter::writeDIStringType(const DIStringType *N,
1685                                             SmallVectorImpl<uint64_t> &Record,
1686                                             unsigned Abbrev) {
1687   Record.push_back(N->isDistinct());
1688   Record.push_back(N->getTag());
1689   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1690   Record.push_back(VE.getMetadataOrNullID(N->getStringLength()));
1691   Record.push_back(VE.getMetadataOrNullID(N->getStringLengthExp()));
1692   Record.push_back(VE.getMetadataOrNullID(N->getStringLocationExp()));
1693   Record.push_back(N->getSizeInBits());
1694   Record.push_back(N->getAlignInBits());
1695   Record.push_back(N->getEncoding());
1696 
1697   Stream.EmitRecord(bitc::METADATA_STRING_TYPE, Record, Abbrev);
1698   Record.clear();
1699 }
1700 
1701 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1702                                              SmallVectorImpl<uint64_t> &Record,
1703                                              unsigned Abbrev) {
1704   Record.push_back(N->isDistinct());
1705   Record.push_back(N->getTag());
1706   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1707   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1708   Record.push_back(N->getLine());
1709   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1710   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1711   Record.push_back(N->getSizeInBits());
1712   Record.push_back(N->getAlignInBits());
1713   Record.push_back(N->getOffsetInBits());
1714   Record.push_back(N->getFlags());
1715   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1716 
1717   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1718   // that there is no DWARF address space associated with DIDerivedType.
1719   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1720     Record.push_back(*DWARFAddressSpace + 1);
1721   else
1722     Record.push_back(0);
1723 
1724   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1725 
1726   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1727   Record.clear();
1728 }
1729 
1730 void ModuleBitcodeWriter::writeDICompositeType(
1731     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1732     unsigned Abbrev) {
1733   const unsigned IsNotUsedInOldTypeRef = 0x2;
1734   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1735   Record.push_back(N->getTag());
1736   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1737   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1738   Record.push_back(N->getLine());
1739   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1740   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1741   Record.push_back(N->getSizeInBits());
1742   Record.push_back(N->getAlignInBits());
1743   Record.push_back(N->getOffsetInBits());
1744   Record.push_back(N->getFlags());
1745   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1746   Record.push_back(N->getRuntimeLang());
1747   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1748   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1749   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1750   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1751   Record.push_back(VE.getMetadataOrNullID(N->getRawDataLocation()));
1752   Record.push_back(VE.getMetadataOrNullID(N->getRawAssociated()));
1753   Record.push_back(VE.getMetadataOrNullID(N->getRawAllocated()));
1754   Record.push_back(VE.getMetadataOrNullID(N->getRawRank()));
1755   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1756 
1757   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1758   Record.clear();
1759 }
1760 
1761 void ModuleBitcodeWriter::writeDISubroutineType(
1762     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1763     unsigned Abbrev) {
1764   const unsigned HasNoOldTypeRefs = 0x2;
1765   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1766   Record.push_back(N->getFlags());
1767   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1768   Record.push_back(N->getCC());
1769 
1770   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1771   Record.clear();
1772 }
1773 
1774 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1775                                       SmallVectorImpl<uint64_t> &Record,
1776                                       unsigned Abbrev) {
1777   Record.push_back(N->isDistinct());
1778   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1779   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1780   if (N->getRawChecksum()) {
1781     Record.push_back(N->getRawChecksum()->Kind);
1782     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1783   } else {
1784     // Maintain backwards compatibility with the old internal representation of
1785     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1786     Record.push_back(0);
1787     Record.push_back(VE.getMetadataOrNullID(nullptr));
1788   }
1789   auto Source = N->getRawSource();
1790   if (Source)
1791     Record.push_back(VE.getMetadataOrNullID(*Source));
1792 
1793   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1794   Record.clear();
1795 }
1796 
1797 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1798                                              SmallVectorImpl<uint64_t> &Record,
1799                                              unsigned Abbrev) {
1800   assert(N->isDistinct() && "Expected distinct compile units");
1801   Record.push_back(/* IsDistinct */ true);
1802   Record.push_back(N->getSourceLanguage());
1803   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1804   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1805   Record.push_back(N->isOptimized());
1806   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1807   Record.push_back(N->getRuntimeVersion());
1808   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1809   Record.push_back(N->getEmissionKind());
1810   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1811   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1812   Record.push_back(/* subprograms */ 0);
1813   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1814   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1815   Record.push_back(N->getDWOId());
1816   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1817   Record.push_back(N->getSplitDebugInlining());
1818   Record.push_back(N->getDebugInfoForProfiling());
1819   Record.push_back((unsigned)N->getNameTableKind());
1820   Record.push_back(N->getRangesBaseAddress());
1821   Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
1822   Record.push_back(VE.getMetadataOrNullID(N->getRawSDK()));
1823 
1824   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1825   Record.clear();
1826 }
1827 
1828 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1829                                             SmallVectorImpl<uint64_t> &Record,
1830                                             unsigned Abbrev) {
1831   const uint64_t HasUnitFlag = 1 << 1;
1832   const uint64_t HasSPFlagsFlag = 1 << 2;
1833   Record.push_back(uint64_t(N->isDistinct()) | HasUnitFlag | HasSPFlagsFlag);
1834   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1835   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1836   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1837   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1838   Record.push_back(N->getLine());
1839   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1840   Record.push_back(N->getScopeLine());
1841   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1842   Record.push_back(N->getSPFlags());
1843   Record.push_back(N->getVirtualIndex());
1844   Record.push_back(N->getFlags());
1845   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1846   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1847   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1848   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1849   Record.push_back(N->getThisAdjustment());
1850   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1851   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1852   Record.push_back(VE.getMetadataOrNullID(N->getRawTargetFuncName()));
1853 
1854   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1855   Record.clear();
1856 }
1857 
1858 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1859                                               SmallVectorImpl<uint64_t> &Record,
1860                                               unsigned Abbrev) {
1861   Record.push_back(N->isDistinct());
1862   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1863   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1864   Record.push_back(N->getLine());
1865   Record.push_back(N->getColumn());
1866 
1867   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1868   Record.clear();
1869 }
1870 
1871 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1872     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1873     unsigned Abbrev) {
1874   Record.push_back(N->isDistinct());
1875   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1876   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1877   Record.push_back(N->getDiscriminator());
1878 
1879   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1880   Record.clear();
1881 }
1882 
1883 void ModuleBitcodeWriter::writeDICommonBlock(const DICommonBlock *N,
1884                                              SmallVectorImpl<uint64_t> &Record,
1885                                              unsigned Abbrev) {
1886   Record.push_back(N->isDistinct());
1887   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1888   Record.push_back(VE.getMetadataOrNullID(N->getDecl()));
1889   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1890   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1891   Record.push_back(N->getLineNo());
1892 
1893   Stream.EmitRecord(bitc::METADATA_COMMON_BLOCK, Record, Abbrev);
1894   Record.clear();
1895 }
1896 
1897 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1898                                            SmallVectorImpl<uint64_t> &Record,
1899                                            unsigned Abbrev) {
1900   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1901   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1902   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1903 
1904   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1905   Record.clear();
1906 }
1907 
1908 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1909                                        SmallVectorImpl<uint64_t> &Record,
1910                                        unsigned Abbrev) {
1911   Record.push_back(N->isDistinct());
1912   Record.push_back(N->getMacinfoType());
1913   Record.push_back(N->getLine());
1914   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1915   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1916 
1917   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1918   Record.clear();
1919 }
1920 
1921 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1922                                            SmallVectorImpl<uint64_t> &Record,
1923                                            unsigned Abbrev) {
1924   Record.push_back(N->isDistinct());
1925   Record.push_back(N->getMacinfoType());
1926   Record.push_back(N->getLine());
1927   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1928   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1929 
1930   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1931   Record.clear();
1932 }
1933 
1934 void ModuleBitcodeWriter::writeDIArgList(const DIArgList *N,
1935                                          SmallVectorImpl<uint64_t> &Record,
1936                                          unsigned Abbrev) {
1937   Record.reserve(N->getArgs().size());
1938   for (ValueAsMetadata *MD : N->getArgs())
1939     Record.push_back(VE.getMetadataID(MD));
1940 
1941   Stream.EmitRecord(bitc::METADATA_ARG_LIST, Record, Abbrev);
1942   Record.clear();
1943 }
1944 
1945 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1946                                         SmallVectorImpl<uint64_t> &Record,
1947                                         unsigned Abbrev) {
1948   Record.push_back(N->isDistinct());
1949   for (auto &I : N->operands())
1950     Record.push_back(VE.getMetadataOrNullID(I));
1951   Record.push_back(N->getLineNo());
1952   Record.push_back(N->getIsDecl());
1953 
1954   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1955   Record.clear();
1956 }
1957 
1958 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1959     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1960     unsigned Abbrev) {
1961   Record.push_back(N->isDistinct());
1962   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1963   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1964   Record.push_back(N->isDefault());
1965 
1966   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1967   Record.clear();
1968 }
1969 
1970 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1971     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1972     unsigned Abbrev) {
1973   Record.push_back(N->isDistinct());
1974   Record.push_back(N->getTag());
1975   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1976   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1977   Record.push_back(N->isDefault());
1978   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1979 
1980   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1981   Record.clear();
1982 }
1983 
1984 void ModuleBitcodeWriter::writeDIGlobalVariable(
1985     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1986     unsigned Abbrev) {
1987   const uint64_t Version = 2 << 1;
1988   Record.push_back((uint64_t)N->isDistinct() | Version);
1989   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1990   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1991   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1992   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1993   Record.push_back(N->getLine());
1994   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1995   Record.push_back(N->isLocalToUnit());
1996   Record.push_back(N->isDefinition());
1997   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1998   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
1999   Record.push_back(N->getAlignInBits());
2000   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
2001 
2002   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
2003   Record.clear();
2004 }
2005 
2006 void ModuleBitcodeWriter::writeDILocalVariable(
2007     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
2008     unsigned Abbrev) {
2009   // In order to support all possible bitcode formats in BitcodeReader we need
2010   // to distinguish the following cases:
2011   // 1) Record has no artificial tag (Record[1]),
2012   //   has no obsolete inlinedAt field (Record[9]).
2013   //   In this case Record size will be 8, HasAlignment flag is false.
2014   // 2) Record has artificial tag (Record[1]),
2015   //   has no obsolete inlignedAt field (Record[9]).
2016   //   In this case Record size will be 9, HasAlignment flag is false.
2017   // 3) Record has both artificial tag (Record[1]) and
2018   //   obsolete inlignedAt field (Record[9]).
2019   //   In this case Record size will be 10, HasAlignment flag is false.
2020   // 4) Record has neither artificial tag, nor inlignedAt field, but
2021   //   HasAlignment flag is true and Record[8] contains alignment value.
2022   const uint64_t HasAlignmentFlag = 1 << 1;
2023   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
2024   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2025   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2026   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2027   Record.push_back(N->getLine());
2028   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2029   Record.push_back(N->getArg());
2030   Record.push_back(N->getFlags());
2031   Record.push_back(N->getAlignInBits());
2032   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
2033 
2034   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
2035   Record.clear();
2036 }
2037 
2038 void ModuleBitcodeWriter::writeDILabel(
2039     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
2040     unsigned Abbrev) {
2041   Record.push_back((uint64_t)N->isDistinct());
2042   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2043   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2044   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2045   Record.push_back(N->getLine());
2046 
2047   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
2048   Record.clear();
2049 }
2050 
2051 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
2052                                             SmallVectorImpl<uint64_t> &Record,
2053                                             unsigned Abbrev) {
2054   Record.reserve(N->getElements().size() + 1);
2055   const uint64_t Version = 3 << 1;
2056   Record.push_back((uint64_t)N->isDistinct() | Version);
2057   Record.append(N->elements_begin(), N->elements_end());
2058 
2059   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
2060   Record.clear();
2061 }
2062 
2063 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
2064     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
2065     unsigned Abbrev) {
2066   Record.push_back(N->isDistinct());
2067   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
2068   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
2069 
2070   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
2071   Record.clear();
2072 }
2073 
2074 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
2075                                               SmallVectorImpl<uint64_t> &Record,
2076                                               unsigned Abbrev) {
2077   Record.push_back(N->isDistinct());
2078   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2079   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2080   Record.push_back(N->getLine());
2081   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
2082   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
2083   Record.push_back(N->getAttributes());
2084   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2085 
2086   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
2087   Record.clear();
2088 }
2089 
2090 void ModuleBitcodeWriter::writeDIImportedEntity(
2091     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
2092     unsigned Abbrev) {
2093   Record.push_back(N->isDistinct());
2094   Record.push_back(N->getTag());
2095   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2096   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
2097   Record.push_back(N->getLine());
2098   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2099   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
2100   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
2101 
2102   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
2103   Record.clear();
2104 }
2105 
2106 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
2107   auto Abbv = std::make_shared<BitCodeAbbrev>();
2108   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
2109   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2110   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2111   return Stream.EmitAbbrev(std::move(Abbv));
2112 }
2113 
2114 void ModuleBitcodeWriter::writeNamedMetadata(
2115     SmallVectorImpl<uint64_t> &Record) {
2116   if (M.named_metadata_empty())
2117     return;
2118 
2119   unsigned Abbrev = createNamedMetadataAbbrev();
2120   for (const NamedMDNode &NMD : M.named_metadata()) {
2121     // Write name.
2122     StringRef Str = NMD.getName();
2123     Record.append(Str.bytes_begin(), Str.bytes_end());
2124     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
2125     Record.clear();
2126 
2127     // Write named metadata operands.
2128     for (const MDNode *N : NMD.operands())
2129       Record.push_back(VE.getMetadataID(N));
2130     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
2131     Record.clear();
2132   }
2133 }
2134 
2135 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
2136   auto Abbv = std::make_shared<BitCodeAbbrev>();
2137   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
2138   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
2139   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
2140   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2141   return Stream.EmitAbbrev(std::move(Abbv));
2142 }
2143 
2144 /// Write out a record for MDString.
2145 ///
2146 /// All the metadata strings in a metadata block are emitted in a single
2147 /// record.  The sizes and strings themselves are shoved into a blob.
2148 void ModuleBitcodeWriter::writeMetadataStrings(
2149     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
2150   if (Strings.empty())
2151     return;
2152 
2153   // Start the record with the number of strings.
2154   Record.push_back(bitc::METADATA_STRINGS);
2155   Record.push_back(Strings.size());
2156 
2157   // Emit the sizes of the strings in the blob.
2158   SmallString<256> Blob;
2159   {
2160     BitstreamWriter W(Blob);
2161     for (const Metadata *MD : Strings)
2162       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
2163     W.FlushToWord();
2164   }
2165 
2166   // Add the offset to the strings to the record.
2167   Record.push_back(Blob.size());
2168 
2169   // Add the strings to the blob.
2170   for (const Metadata *MD : Strings)
2171     Blob.append(cast<MDString>(MD)->getString());
2172 
2173   // Emit the final record.
2174   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
2175   Record.clear();
2176 }
2177 
2178 // Generates an enum to use as an index in the Abbrev array of Metadata record.
2179 enum MetadataAbbrev : unsigned {
2180 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
2181 #include "llvm/IR/Metadata.def"
2182   LastPlusOne
2183 };
2184 
2185 void ModuleBitcodeWriter::writeMetadataRecords(
2186     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
2187     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
2188   if (MDs.empty())
2189     return;
2190 
2191   // Initialize MDNode abbreviations.
2192 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
2193 #include "llvm/IR/Metadata.def"
2194 
2195   for (const Metadata *MD : MDs) {
2196     if (IndexPos)
2197       IndexPos->push_back(Stream.GetCurrentBitNo());
2198     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
2199       assert(N->isResolved() && "Expected forward references to be resolved");
2200 
2201       switch (N->getMetadataID()) {
2202       default:
2203         llvm_unreachable("Invalid MDNode subclass");
2204 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
2205   case Metadata::CLASS##Kind:                                                  \
2206     if (MDAbbrevs)                                                             \
2207       write##CLASS(cast<CLASS>(N), Record,                                     \
2208                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
2209     else                                                                       \
2210       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
2211     continue;
2212 #include "llvm/IR/Metadata.def"
2213       }
2214     }
2215     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
2216   }
2217 }
2218 
2219 void ModuleBitcodeWriter::writeModuleMetadata() {
2220   if (!VE.hasMDs() && M.named_metadata_empty())
2221     return;
2222 
2223   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
2224   SmallVector<uint64_t, 64> Record;
2225 
2226   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
2227   // block and load any metadata.
2228   std::vector<unsigned> MDAbbrevs;
2229 
2230   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
2231   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
2232   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
2233       createGenericDINodeAbbrev();
2234 
2235   auto Abbv = std::make_shared<BitCodeAbbrev>();
2236   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
2237   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2238   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2239   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2240 
2241   Abbv = std::make_shared<BitCodeAbbrev>();
2242   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
2243   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2244   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2245   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2246 
2247   // Emit MDStrings together upfront.
2248   writeMetadataStrings(VE.getMDStrings(), Record);
2249 
2250   // We only emit an index for the metadata record if we have more than a given
2251   // (naive) threshold of metadatas, otherwise it is not worth it.
2252   if (VE.getNonMDStrings().size() > IndexThreshold) {
2253     // Write a placeholder value in for the offset of the metadata index,
2254     // which is written after the records, so that it can include
2255     // the offset of each entry. The placeholder offset will be
2256     // updated after all records are emitted.
2257     uint64_t Vals[] = {0, 0};
2258     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2259   }
2260 
2261   // Compute and save the bit offset to the current position, which will be
2262   // patched when we emit the index later. We can simply subtract the 64-bit
2263   // fixed size from the current bit number to get the location to backpatch.
2264   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2265 
2266   // This index will contain the bitpos for each individual record.
2267   std::vector<uint64_t> IndexPos;
2268   IndexPos.reserve(VE.getNonMDStrings().size());
2269 
2270   // Write all the records
2271   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2272 
2273   if (VE.getNonMDStrings().size() > IndexThreshold) {
2274     // Now that we have emitted all the records we will emit the index. But
2275     // first
2276     // backpatch the forward reference so that the reader can skip the records
2277     // efficiently.
2278     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2279                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2280 
2281     // Delta encode the index.
2282     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2283     for (auto &Elt : IndexPos) {
2284       auto EltDelta = Elt - PreviousValue;
2285       PreviousValue = Elt;
2286       Elt = EltDelta;
2287     }
2288     // Emit the index record.
2289     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2290     IndexPos.clear();
2291   }
2292 
2293   // Write the named metadata now.
2294   writeNamedMetadata(Record);
2295 
2296   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2297     SmallVector<uint64_t, 4> Record;
2298     Record.push_back(VE.getValueID(&GO));
2299     pushGlobalMetadataAttachment(Record, GO);
2300     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2301   };
2302   for (const Function &F : M)
2303     if (F.isDeclaration() && F.hasMetadata())
2304       AddDeclAttachedMetadata(F);
2305   // FIXME: Only store metadata for declarations here, and move data for global
2306   // variable definitions to a separate block (PR28134).
2307   for (const GlobalVariable &GV : M.globals())
2308     if (GV.hasMetadata())
2309       AddDeclAttachedMetadata(GV);
2310 
2311   Stream.ExitBlock();
2312 }
2313 
2314 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2315   if (!VE.hasMDs())
2316     return;
2317 
2318   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2319   SmallVector<uint64_t, 64> Record;
2320   writeMetadataStrings(VE.getMDStrings(), Record);
2321   writeMetadataRecords(VE.getNonMDStrings(), Record);
2322   Stream.ExitBlock();
2323 }
2324 
2325 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2326     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2327   // [n x [id, mdnode]]
2328   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2329   GO.getAllMetadata(MDs);
2330   for (const auto &I : MDs) {
2331     Record.push_back(I.first);
2332     Record.push_back(VE.getMetadataID(I.second));
2333   }
2334 }
2335 
2336 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2337   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2338 
2339   SmallVector<uint64_t, 64> Record;
2340 
2341   if (F.hasMetadata()) {
2342     pushGlobalMetadataAttachment(Record, F);
2343     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2344     Record.clear();
2345   }
2346 
2347   // Write metadata attachments
2348   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2349   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2350   for (const BasicBlock &BB : F)
2351     for (const Instruction &I : BB) {
2352       MDs.clear();
2353       I.getAllMetadataOtherThanDebugLoc(MDs);
2354 
2355       // If no metadata, ignore instruction.
2356       if (MDs.empty()) continue;
2357 
2358       Record.push_back(VE.getInstructionID(&I));
2359 
2360       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2361         Record.push_back(MDs[i].first);
2362         Record.push_back(VE.getMetadataID(MDs[i].second));
2363       }
2364       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2365       Record.clear();
2366     }
2367 
2368   Stream.ExitBlock();
2369 }
2370 
2371 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2372   SmallVector<uint64_t, 64> Record;
2373 
2374   // Write metadata kinds
2375   // METADATA_KIND - [n x [id, name]]
2376   SmallVector<StringRef, 8> Names;
2377   M.getMDKindNames(Names);
2378 
2379   if (Names.empty()) return;
2380 
2381   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2382 
2383   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2384     Record.push_back(MDKindID);
2385     StringRef KName = Names[MDKindID];
2386     Record.append(KName.begin(), KName.end());
2387 
2388     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2389     Record.clear();
2390   }
2391 
2392   Stream.ExitBlock();
2393 }
2394 
2395 void ModuleBitcodeWriter::writeOperandBundleTags() {
2396   // Write metadata kinds
2397   //
2398   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2399   //
2400   // OPERAND_BUNDLE_TAG - [strchr x N]
2401 
2402   SmallVector<StringRef, 8> Tags;
2403   M.getOperandBundleTags(Tags);
2404 
2405   if (Tags.empty())
2406     return;
2407 
2408   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2409 
2410   SmallVector<uint64_t, 64> Record;
2411 
2412   for (auto Tag : Tags) {
2413     Record.append(Tag.begin(), Tag.end());
2414 
2415     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2416     Record.clear();
2417   }
2418 
2419   Stream.ExitBlock();
2420 }
2421 
2422 void ModuleBitcodeWriter::writeSyncScopeNames() {
2423   SmallVector<StringRef, 8> SSNs;
2424   M.getContext().getSyncScopeNames(SSNs);
2425   if (SSNs.empty())
2426     return;
2427 
2428   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2429 
2430   SmallVector<uint64_t, 64> Record;
2431   for (auto SSN : SSNs) {
2432     Record.append(SSN.begin(), SSN.end());
2433     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2434     Record.clear();
2435   }
2436 
2437   Stream.ExitBlock();
2438 }
2439 
2440 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2441                                          bool isGlobal) {
2442   if (FirstVal == LastVal) return;
2443 
2444   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2445 
2446   unsigned AggregateAbbrev = 0;
2447   unsigned String8Abbrev = 0;
2448   unsigned CString7Abbrev = 0;
2449   unsigned CString6Abbrev = 0;
2450   // If this is a constant pool for the module, emit module-specific abbrevs.
2451   if (isGlobal) {
2452     // Abbrev for CST_CODE_AGGREGATE.
2453     auto Abbv = std::make_shared<BitCodeAbbrev>();
2454     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2455     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2456     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2457     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2458 
2459     // Abbrev for CST_CODE_STRING.
2460     Abbv = std::make_shared<BitCodeAbbrev>();
2461     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2462     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2463     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2464     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2465     // Abbrev for CST_CODE_CSTRING.
2466     Abbv = std::make_shared<BitCodeAbbrev>();
2467     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2468     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2469     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2470     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2471     // Abbrev for CST_CODE_CSTRING.
2472     Abbv = std::make_shared<BitCodeAbbrev>();
2473     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2474     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2475     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2476     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2477   }
2478 
2479   SmallVector<uint64_t, 64> Record;
2480 
2481   const ValueEnumerator::ValueList &Vals = VE.getValues();
2482   Type *LastTy = nullptr;
2483   for (unsigned i = FirstVal; i != LastVal; ++i) {
2484     const Value *V = Vals[i].first;
2485     // If we need to switch types, do so now.
2486     if (V->getType() != LastTy) {
2487       LastTy = V->getType();
2488       Record.push_back(VE.getTypeID(LastTy));
2489       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2490                         CONSTANTS_SETTYPE_ABBREV);
2491       Record.clear();
2492     }
2493 
2494     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2495       Record.push_back(VE.getTypeID(IA->getFunctionType()));
2496       Record.push_back(
2497           unsigned(IA->hasSideEffects()) | unsigned(IA->isAlignStack()) << 1 |
2498           unsigned(IA->getDialect() & 1) << 2 | unsigned(IA->canThrow()) << 3);
2499 
2500       // Add the asm string.
2501       const std::string &AsmStr = IA->getAsmString();
2502       Record.push_back(AsmStr.size());
2503       Record.append(AsmStr.begin(), AsmStr.end());
2504 
2505       // Add the constraint string.
2506       const std::string &ConstraintStr = IA->getConstraintString();
2507       Record.push_back(ConstraintStr.size());
2508       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2509       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2510       Record.clear();
2511       continue;
2512     }
2513     const Constant *C = cast<Constant>(V);
2514     unsigned Code = -1U;
2515     unsigned AbbrevToUse = 0;
2516     if (C->isNullValue()) {
2517       Code = bitc::CST_CODE_NULL;
2518     } else if (isa<PoisonValue>(C)) {
2519       Code = bitc::CST_CODE_POISON;
2520     } else if (isa<UndefValue>(C)) {
2521       Code = bitc::CST_CODE_UNDEF;
2522     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2523       if (IV->getBitWidth() <= 64) {
2524         uint64_t V = IV->getSExtValue();
2525         emitSignedInt64(Record, V);
2526         Code = bitc::CST_CODE_INTEGER;
2527         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2528       } else {                             // Wide integers, > 64 bits in size.
2529         emitWideAPInt(Record, IV->getValue());
2530         Code = bitc::CST_CODE_WIDE_INTEGER;
2531       }
2532     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2533       Code = bitc::CST_CODE_FLOAT;
2534       Type *Ty = CFP->getType();
2535       if (Ty->isHalfTy() || Ty->isBFloatTy() || Ty->isFloatTy() ||
2536           Ty->isDoubleTy()) {
2537         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2538       } else if (Ty->isX86_FP80Ty()) {
2539         // api needed to prevent premature destruction
2540         // bits are not in the same order as a normal i80 APInt, compensate.
2541         APInt api = CFP->getValueAPF().bitcastToAPInt();
2542         const uint64_t *p = api.getRawData();
2543         Record.push_back((p[1] << 48) | (p[0] >> 16));
2544         Record.push_back(p[0] & 0xffffLL);
2545       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2546         APInt api = CFP->getValueAPF().bitcastToAPInt();
2547         const uint64_t *p = api.getRawData();
2548         Record.push_back(p[0]);
2549         Record.push_back(p[1]);
2550       } else {
2551         assert(0 && "Unknown FP type!");
2552       }
2553     } else if (isa<ConstantDataSequential>(C) &&
2554                cast<ConstantDataSequential>(C)->isString()) {
2555       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2556       // Emit constant strings specially.
2557       unsigned NumElts = Str->getNumElements();
2558       // If this is a null-terminated string, use the denser CSTRING encoding.
2559       if (Str->isCString()) {
2560         Code = bitc::CST_CODE_CSTRING;
2561         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2562       } else {
2563         Code = bitc::CST_CODE_STRING;
2564         AbbrevToUse = String8Abbrev;
2565       }
2566       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2567       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2568       for (unsigned i = 0; i != NumElts; ++i) {
2569         unsigned char V = Str->getElementAsInteger(i);
2570         Record.push_back(V);
2571         isCStr7 &= (V & 128) == 0;
2572         if (isCStrChar6)
2573           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2574       }
2575 
2576       if (isCStrChar6)
2577         AbbrevToUse = CString6Abbrev;
2578       else if (isCStr7)
2579         AbbrevToUse = CString7Abbrev;
2580     } else if (const ConstantDataSequential *CDS =
2581                   dyn_cast<ConstantDataSequential>(C)) {
2582       Code = bitc::CST_CODE_DATA;
2583       Type *EltTy = CDS->getElementType();
2584       if (isa<IntegerType>(EltTy)) {
2585         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2586           Record.push_back(CDS->getElementAsInteger(i));
2587       } else {
2588         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2589           Record.push_back(
2590               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2591       }
2592     } else if (isa<ConstantAggregate>(C)) {
2593       Code = bitc::CST_CODE_AGGREGATE;
2594       for (const Value *Op : C->operands())
2595         Record.push_back(VE.getValueID(Op));
2596       AbbrevToUse = AggregateAbbrev;
2597     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2598       switch (CE->getOpcode()) {
2599       default:
2600         if (Instruction::isCast(CE->getOpcode())) {
2601           Code = bitc::CST_CODE_CE_CAST;
2602           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2603           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2604           Record.push_back(VE.getValueID(C->getOperand(0)));
2605           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2606         } else {
2607           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2608           Code = bitc::CST_CODE_CE_BINOP;
2609           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2610           Record.push_back(VE.getValueID(C->getOperand(0)));
2611           Record.push_back(VE.getValueID(C->getOperand(1)));
2612           uint64_t Flags = getOptimizationFlags(CE);
2613           if (Flags != 0)
2614             Record.push_back(Flags);
2615         }
2616         break;
2617       case Instruction::FNeg: {
2618         assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
2619         Code = bitc::CST_CODE_CE_UNOP;
2620         Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
2621         Record.push_back(VE.getValueID(C->getOperand(0)));
2622         uint64_t Flags = getOptimizationFlags(CE);
2623         if (Flags != 0)
2624           Record.push_back(Flags);
2625         break;
2626       }
2627       case Instruction::GetElementPtr: {
2628         Code = bitc::CST_CODE_CE_GEP;
2629         const auto *GO = cast<GEPOperator>(C);
2630         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2631         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2632           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2633           Record.push_back((*Idx << 1) | GO->isInBounds());
2634         } else if (GO->isInBounds())
2635           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2636         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2637           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2638           Record.push_back(VE.getValueID(C->getOperand(i)));
2639         }
2640         break;
2641       }
2642       case Instruction::Select:
2643         Code = bitc::CST_CODE_CE_SELECT;
2644         Record.push_back(VE.getValueID(C->getOperand(0)));
2645         Record.push_back(VE.getValueID(C->getOperand(1)));
2646         Record.push_back(VE.getValueID(C->getOperand(2)));
2647         break;
2648       case Instruction::ExtractElement:
2649         Code = bitc::CST_CODE_CE_EXTRACTELT;
2650         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2651         Record.push_back(VE.getValueID(C->getOperand(0)));
2652         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2653         Record.push_back(VE.getValueID(C->getOperand(1)));
2654         break;
2655       case Instruction::InsertElement:
2656         Code = bitc::CST_CODE_CE_INSERTELT;
2657         Record.push_back(VE.getValueID(C->getOperand(0)));
2658         Record.push_back(VE.getValueID(C->getOperand(1)));
2659         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2660         Record.push_back(VE.getValueID(C->getOperand(2)));
2661         break;
2662       case Instruction::ShuffleVector:
2663         // If the return type and argument types are the same, this is a
2664         // standard shufflevector instruction.  If the types are different,
2665         // then the shuffle is widening or truncating the input vectors, and
2666         // the argument type must also be encoded.
2667         if (C->getType() == C->getOperand(0)->getType()) {
2668           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2669         } else {
2670           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2671           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2672         }
2673         Record.push_back(VE.getValueID(C->getOperand(0)));
2674         Record.push_back(VE.getValueID(C->getOperand(1)));
2675         Record.push_back(VE.getValueID(CE->getShuffleMaskForBitcode()));
2676         break;
2677       case Instruction::ICmp:
2678       case Instruction::FCmp:
2679         Code = bitc::CST_CODE_CE_CMP;
2680         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2681         Record.push_back(VE.getValueID(C->getOperand(0)));
2682         Record.push_back(VE.getValueID(C->getOperand(1)));
2683         Record.push_back(CE->getPredicate());
2684         break;
2685       }
2686     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2687       Code = bitc::CST_CODE_BLOCKADDRESS;
2688       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2689       Record.push_back(VE.getValueID(BA->getFunction()));
2690       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2691     } else if (const auto *Equiv = dyn_cast<DSOLocalEquivalent>(C)) {
2692       Code = bitc::CST_CODE_DSO_LOCAL_EQUIVALENT;
2693       Record.push_back(VE.getTypeID(Equiv->getGlobalValue()->getType()));
2694       Record.push_back(VE.getValueID(Equiv->getGlobalValue()));
2695     } else if (const auto *NC = dyn_cast<NoCFIValue>(C)) {
2696       Code = bitc::CST_CODE_NO_CFI_VALUE;
2697       Record.push_back(VE.getTypeID(NC->getGlobalValue()->getType()));
2698       Record.push_back(VE.getValueID(NC->getGlobalValue()));
2699     } else {
2700 #ifndef NDEBUG
2701       C->dump();
2702 #endif
2703       llvm_unreachable("Unknown constant!");
2704     }
2705     Stream.EmitRecord(Code, Record, AbbrevToUse);
2706     Record.clear();
2707   }
2708 
2709   Stream.ExitBlock();
2710 }
2711 
2712 void ModuleBitcodeWriter::writeModuleConstants() {
2713   const ValueEnumerator::ValueList &Vals = VE.getValues();
2714 
2715   // Find the first constant to emit, which is the first non-globalvalue value.
2716   // We know globalvalues have been emitted by WriteModuleInfo.
2717   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2718     if (!isa<GlobalValue>(Vals[i].first)) {
2719       writeConstants(i, Vals.size(), true);
2720       return;
2721     }
2722   }
2723 }
2724 
2725 /// pushValueAndType - The file has to encode both the value and type id for
2726 /// many values, because we need to know what type to create for forward
2727 /// references.  However, most operands are not forward references, so this type
2728 /// field is not needed.
2729 ///
2730 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2731 /// instruction ID, then it is a forward reference, and it also includes the
2732 /// type ID.  The value ID that is written is encoded relative to the InstID.
2733 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2734                                            SmallVectorImpl<unsigned> &Vals) {
2735   unsigned ValID = VE.getValueID(V);
2736   // Make encoding relative to the InstID.
2737   Vals.push_back(InstID - ValID);
2738   if (ValID >= InstID) {
2739     Vals.push_back(VE.getTypeID(V->getType()));
2740     return true;
2741   }
2742   return false;
2743 }
2744 
2745 void ModuleBitcodeWriter::writeOperandBundles(const CallBase &CS,
2746                                               unsigned InstID) {
2747   SmallVector<unsigned, 64> Record;
2748   LLVMContext &C = CS.getContext();
2749 
2750   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2751     const auto &Bundle = CS.getOperandBundleAt(i);
2752     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2753 
2754     for (auto &Input : Bundle.Inputs)
2755       pushValueAndType(Input, InstID, Record);
2756 
2757     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2758     Record.clear();
2759   }
2760 }
2761 
2762 /// pushValue - Like pushValueAndType, but where the type of the value is
2763 /// omitted (perhaps it was already encoded in an earlier operand).
2764 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2765                                     SmallVectorImpl<unsigned> &Vals) {
2766   unsigned ValID = VE.getValueID(V);
2767   Vals.push_back(InstID - ValID);
2768 }
2769 
2770 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2771                                           SmallVectorImpl<uint64_t> &Vals) {
2772   unsigned ValID = VE.getValueID(V);
2773   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2774   emitSignedInt64(Vals, diff);
2775 }
2776 
2777 /// WriteInstruction - Emit an instruction to the specified stream.
2778 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2779                                            unsigned InstID,
2780                                            SmallVectorImpl<unsigned> &Vals) {
2781   unsigned Code = 0;
2782   unsigned AbbrevToUse = 0;
2783   VE.setInstructionID(&I);
2784   switch (I.getOpcode()) {
2785   default:
2786     if (Instruction::isCast(I.getOpcode())) {
2787       Code = bitc::FUNC_CODE_INST_CAST;
2788       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2789         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2790       Vals.push_back(VE.getTypeID(I.getType()));
2791       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2792     } else {
2793       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2794       Code = bitc::FUNC_CODE_INST_BINOP;
2795       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2796         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2797       pushValue(I.getOperand(1), InstID, Vals);
2798       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2799       uint64_t Flags = getOptimizationFlags(&I);
2800       if (Flags != 0) {
2801         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2802           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2803         Vals.push_back(Flags);
2804       }
2805     }
2806     break;
2807   case Instruction::FNeg: {
2808     Code = bitc::FUNC_CODE_INST_UNOP;
2809     if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2810       AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
2811     Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
2812     uint64_t Flags = getOptimizationFlags(&I);
2813     if (Flags != 0) {
2814       if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
2815         AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
2816       Vals.push_back(Flags);
2817     }
2818     break;
2819   }
2820   case Instruction::GetElementPtr: {
2821     Code = bitc::FUNC_CODE_INST_GEP;
2822     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2823     auto &GEPInst = cast<GetElementPtrInst>(I);
2824     Vals.push_back(GEPInst.isInBounds());
2825     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2826     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2827       pushValueAndType(I.getOperand(i), InstID, Vals);
2828     break;
2829   }
2830   case Instruction::ExtractValue: {
2831     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2832     pushValueAndType(I.getOperand(0), InstID, Vals);
2833     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2834     Vals.append(EVI->idx_begin(), EVI->idx_end());
2835     break;
2836   }
2837   case Instruction::InsertValue: {
2838     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2839     pushValueAndType(I.getOperand(0), InstID, Vals);
2840     pushValueAndType(I.getOperand(1), InstID, Vals);
2841     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2842     Vals.append(IVI->idx_begin(), IVI->idx_end());
2843     break;
2844   }
2845   case Instruction::Select: {
2846     Code = bitc::FUNC_CODE_INST_VSELECT;
2847     pushValueAndType(I.getOperand(1), InstID, Vals);
2848     pushValue(I.getOperand(2), InstID, Vals);
2849     pushValueAndType(I.getOperand(0), InstID, Vals);
2850     uint64_t Flags = getOptimizationFlags(&I);
2851     if (Flags != 0)
2852       Vals.push_back(Flags);
2853     break;
2854   }
2855   case Instruction::ExtractElement:
2856     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2857     pushValueAndType(I.getOperand(0), InstID, Vals);
2858     pushValueAndType(I.getOperand(1), InstID, Vals);
2859     break;
2860   case Instruction::InsertElement:
2861     Code = bitc::FUNC_CODE_INST_INSERTELT;
2862     pushValueAndType(I.getOperand(0), InstID, Vals);
2863     pushValue(I.getOperand(1), InstID, Vals);
2864     pushValueAndType(I.getOperand(2), InstID, Vals);
2865     break;
2866   case Instruction::ShuffleVector:
2867     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2868     pushValueAndType(I.getOperand(0), InstID, Vals);
2869     pushValue(I.getOperand(1), InstID, Vals);
2870     pushValue(cast<ShuffleVectorInst>(I).getShuffleMaskForBitcode(), InstID,
2871               Vals);
2872     break;
2873   case Instruction::ICmp:
2874   case Instruction::FCmp: {
2875     // compare returning Int1Ty or vector of Int1Ty
2876     Code = bitc::FUNC_CODE_INST_CMP2;
2877     pushValueAndType(I.getOperand(0), InstID, Vals);
2878     pushValue(I.getOperand(1), InstID, Vals);
2879     Vals.push_back(cast<CmpInst>(I).getPredicate());
2880     uint64_t Flags = getOptimizationFlags(&I);
2881     if (Flags != 0)
2882       Vals.push_back(Flags);
2883     break;
2884   }
2885 
2886   case Instruction::Ret:
2887     {
2888       Code = bitc::FUNC_CODE_INST_RET;
2889       unsigned NumOperands = I.getNumOperands();
2890       if (NumOperands == 0)
2891         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2892       else if (NumOperands == 1) {
2893         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2894           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2895       } else {
2896         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2897           pushValueAndType(I.getOperand(i), InstID, Vals);
2898       }
2899     }
2900     break;
2901   case Instruction::Br:
2902     {
2903       Code = bitc::FUNC_CODE_INST_BR;
2904       const BranchInst &II = cast<BranchInst>(I);
2905       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2906       if (II.isConditional()) {
2907         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2908         pushValue(II.getCondition(), InstID, Vals);
2909       }
2910     }
2911     break;
2912   case Instruction::Switch:
2913     {
2914       Code = bitc::FUNC_CODE_INST_SWITCH;
2915       const SwitchInst &SI = cast<SwitchInst>(I);
2916       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2917       pushValue(SI.getCondition(), InstID, Vals);
2918       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2919       for (auto Case : SI.cases()) {
2920         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2921         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2922       }
2923     }
2924     break;
2925   case Instruction::IndirectBr:
2926     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2927     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2928     // Encode the address operand as relative, but not the basic blocks.
2929     pushValue(I.getOperand(0), InstID, Vals);
2930     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2931       Vals.push_back(VE.getValueID(I.getOperand(i)));
2932     break;
2933 
2934   case Instruction::Invoke: {
2935     const InvokeInst *II = cast<InvokeInst>(&I);
2936     const Value *Callee = II->getCalledOperand();
2937     FunctionType *FTy = II->getFunctionType();
2938 
2939     if (II->hasOperandBundles())
2940       writeOperandBundles(*II, InstID);
2941 
2942     Code = bitc::FUNC_CODE_INST_INVOKE;
2943 
2944     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2945     Vals.push_back(II->getCallingConv() | 1 << 13);
2946     Vals.push_back(VE.getValueID(II->getNormalDest()));
2947     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2948     Vals.push_back(VE.getTypeID(FTy));
2949     pushValueAndType(Callee, InstID, Vals);
2950 
2951     // Emit value #'s for the fixed parameters.
2952     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2953       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2954 
2955     // Emit type/value pairs for varargs params.
2956     if (FTy->isVarArg()) {
2957       for (unsigned i = FTy->getNumParams(), e = II->arg_size(); i != e; ++i)
2958         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2959     }
2960     break;
2961   }
2962   case Instruction::Resume:
2963     Code = bitc::FUNC_CODE_INST_RESUME;
2964     pushValueAndType(I.getOperand(0), InstID, Vals);
2965     break;
2966   case Instruction::CleanupRet: {
2967     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2968     const auto &CRI = cast<CleanupReturnInst>(I);
2969     pushValue(CRI.getCleanupPad(), InstID, Vals);
2970     if (CRI.hasUnwindDest())
2971       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2972     break;
2973   }
2974   case Instruction::CatchRet: {
2975     Code = bitc::FUNC_CODE_INST_CATCHRET;
2976     const auto &CRI = cast<CatchReturnInst>(I);
2977     pushValue(CRI.getCatchPad(), InstID, Vals);
2978     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2979     break;
2980   }
2981   case Instruction::CleanupPad:
2982   case Instruction::CatchPad: {
2983     const auto &FuncletPad = cast<FuncletPadInst>(I);
2984     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2985                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2986     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2987 
2988     unsigned NumArgOperands = FuncletPad.arg_size();
2989     Vals.push_back(NumArgOperands);
2990     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2991       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2992     break;
2993   }
2994   case Instruction::CatchSwitch: {
2995     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2996     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2997 
2998     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2999 
3000     unsigned NumHandlers = CatchSwitch.getNumHandlers();
3001     Vals.push_back(NumHandlers);
3002     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
3003       Vals.push_back(VE.getValueID(CatchPadBB));
3004 
3005     if (CatchSwitch.hasUnwindDest())
3006       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
3007     break;
3008   }
3009   case Instruction::CallBr: {
3010     const CallBrInst *CBI = cast<CallBrInst>(&I);
3011     const Value *Callee = CBI->getCalledOperand();
3012     FunctionType *FTy = CBI->getFunctionType();
3013 
3014     if (CBI->hasOperandBundles())
3015       writeOperandBundles(*CBI, InstID);
3016 
3017     Code = bitc::FUNC_CODE_INST_CALLBR;
3018 
3019     Vals.push_back(VE.getAttributeListID(CBI->getAttributes()));
3020 
3021     Vals.push_back(CBI->getCallingConv() << bitc::CALL_CCONV |
3022                    1 << bitc::CALL_EXPLICIT_TYPE);
3023 
3024     Vals.push_back(VE.getValueID(CBI->getDefaultDest()));
3025     Vals.push_back(CBI->getNumIndirectDests());
3026     for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
3027       Vals.push_back(VE.getValueID(CBI->getIndirectDest(i)));
3028 
3029     Vals.push_back(VE.getTypeID(FTy));
3030     pushValueAndType(Callee, InstID, Vals);
3031 
3032     // Emit value #'s for the fixed parameters.
3033     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
3034       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
3035 
3036     // Emit type/value pairs for varargs params.
3037     if (FTy->isVarArg()) {
3038       for (unsigned i = FTy->getNumParams(), e = CBI->arg_size(); i != e; ++i)
3039         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
3040     }
3041     break;
3042   }
3043   case Instruction::Unreachable:
3044     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
3045     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
3046     break;
3047 
3048   case Instruction::PHI: {
3049     const PHINode &PN = cast<PHINode>(I);
3050     Code = bitc::FUNC_CODE_INST_PHI;
3051     // With the newer instruction encoding, forward references could give
3052     // negative valued IDs.  This is most common for PHIs, so we use
3053     // signed VBRs.
3054     SmallVector<uint64_t, 128> Vals64;
3055     Vals64.push_back(VE.getTypeID(PN.getType()));
3056     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
3057       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
3058       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
3059     }
3060 
3061     uint64_t Flags = getOptimizationFlags(&I);
3062     if (Flags != 0)
3063       Vals64.push_back(Flags);
3064 
3065     // Emit a Vals64 vector and exit.
3066     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
3067     Vals64.clear();
3068     return;
3069   }
3070 
3071   case Instruction::LandingPad: {
3072     const LandingPadInst &LP = cast<LandingPadInst>(I);
3073     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
3074     Vals.push_back(VE.getTypeID(LP.getType()));
3075     Vals.push_back(LP.isCleanup());
3076     Vals.push_back(LP.getNumClauses());
3077     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
3078       if (LP.isCatch(I))
3079         Vals.push_back(LandingPadInst::Catch);
3080       else
3081         Vals.push_back(LandingPadInst::Filter);
3082       pushValueAndType(LP.getClause(I), InstID, Vals);
3083     }
3084     break;
3085   }
3086 
3087   case Instruction::Alloca: {
3088     Code = bitc::FUNC_CODE_INST_ALLOCA;
3089     const AllocaInst &AI = cast<AllocaInst>(I);
3090     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
3091     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
3092     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
3093     using APV = AllocaPackedValues;
3094     unsigned Record = 0;
3095     unsigned EncodedAlign = getEncodedAlign(AI.getAlign());
3096     Bitfield::set<APV::AlignLower>(
3097         Record, EncodedAlign & ((1 << APV::AlignLower::Bits) - 1));
3098     Bitfield::set<APV::AlignUpper>(Record,
3099                                    EncodedAlign >> APV::AlignLower::Bits);
3100     Bitfield::set<APV::UsedWithInAlloca>(Record, AI.isUsedWithInAlloca());
3101     Bitfield::set<APV::ExplicitType>(Record, true);
3102     Bitfield::set<APV::SwiftError>(Record, AI.isSwiftError());
3103     Vals.push_back(Record);
3104 
3105     unsigned AS = AI.getAddressSpace();
3106     if (AS != M.getDataLayout().getAllocaAddrSpace())
3107       Vals.push_back(AS);
3108     break;
3109   }
3110 
3111   case Instruction::Load:
3112     if (cast<LoadInst>(I).isAtomic()) {
3113       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
3114       pushValueAndType(I.getOperand(0), InstID, Vals);
3115     } else {
3116       Code = bitc::FUNC_CODE_INST_LOAD;
3117       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
3118         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
3119     }
3120     Vals.push_back(VE.getTypeID(I.getType()));
3121     Vals.push_back(getEncodedAlign(cast<LoadInst>(I).getAlign()));
3122     Vals.push_back(cast<LoadInst>(I).isVolatile());
3123     if (cast<LoadInst>(I).isAtomic()) {
3124       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
3125       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
3126     }
3127     break;
3128   case Instruction::Store:
3129     if (cast<StoreInst>(I).isAtomic())
3130       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
3131     else
3132       Code = bitc::FUNC_CODE_INST_STORE;
3133     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
3134     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
3135     Vals.push_back(getEncodedAlign(cast<StoreInst>(I).getAlign()));
3136     Vals.push_back(cast<StoreInst>(I).isVolatile());
3137     if (cast<StoreInst>(I).isAtomic()) {
3138       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
3139       Vals.push_back(
3140           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
3141     }
3142     break;
3143   case Instruction::AtomicCmpXchg:
3144     Code = bitc::FUNC_CODE_INST_CMPXCHG;
3145     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3146     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
3147     pushValue(I.getOperand(2), InstID, Vals);        // newval.
3148     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
3149     Vals.push_back(
3150         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
3151     Vals.push_back(
3152         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
3153     Vals.push_back(
3154         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
3155     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
3156     Vals.push_back(getEncodedAlign(cast<AtomicCmpXchgInst>(I).getAlign()));
3157     break;
3158   case Instruction::AtomicRMW:
3159     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
3160     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3161     pushValueAndType(I.getOperand(1), InstID, Vals); // valty + val
3162     Vals.push_back(
3163         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
3164     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
3165     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
3166     Vals.push_back(
3167         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
3168     Vals.push_back(getEncodedAlign(cast<AtomicRMWInst>(I).getAlign()));
3169     break;
3170   case Instruction::Fence:
3171     Code = bitc::FUNC_CODE_INST_FENCE;
3172     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
3173     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
3174     break;
3175   case Instruction::Call: {
3176     const CallInst &CI = cast<CallInst>(I);
3177     FunctionType *FTy = CI.getFunctionType();
3178 
3179     if (CI.hasOperandBundles())
3180       writeOperandBundles(CI, InstID);
3181 
3182     Code = bitc::FUNC_CODE_INST_CALL;
3183 
3184     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
3185 
3186     unsigned Flags = getOptimizationFlags(&I);
3187     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
3188                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
3189                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
3190                    1 << bitc::CALL_EXPLICIT_TYPE |
3191                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
3192                    unsigned(Flags != 0) << bitc::CALL_FMF);
3193     if (Flags != 0)
3194       Vals.push_back(Flags);
3195 
3196     Vals.push_back(VE.getTypeID(FTy));
3197     pushValueAndType(CI.getCalledOperand(), InstID, Vals); // Callee
3198 
3199     // Emit value #'s for the fixed parameters.
3200     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
3201       // Check for labels (can happen with asm labels).
3202       if (FTy->getParamType(i)->isLabelTy())
3203         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
3204       else
3205         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
3206     }
3207 
3208     // Emit type/value pairs for varargs params.
3209     if (FTy->isVarArg()) {
3210       for (unsigned i = FTy->getNumParams(), e = CI.arg_size(); i != e; ++i)
3211         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
3212     }
3213     break;
3214   }
3215   case Instruction::VAArg:
3216     Code = bitc::FUNC_CODE_INST_VAARG;
3217     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
3218     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
3219     Vals.push_back(VE.getTypeID(I.getType())); // restype.
3220     break;
3221   case Instruction::Freeze:
3222     Code = bitc::FUNC_CODE_INST_FREEZE;
3223     pushValueAndType(I.getOperand(0), InstID, Vals);
3224     break;
3225   }
3226 
3227   Stream.EmitRecord(Code, Vals, AbbrevToUse);
3228   Vals.clear();
3229 }
3230 
3231 /// Write a GlobalValue VST to the module. The purpose of this data structure is
3232 /// to allow clients to efficiently find the function body.
3233 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
3234   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3235   // Get the offset of the VST we are writing, and backpatch it into
3236   // the VST forward declaration record.
3237   uint64_t VSTOffset = Stream.GetCurrentBitNo();
3238   // The BitcodeStartBit was the stream offset of the identification block.
3239   VSTOffset -= bitcodeStartBit();
3240   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
3241   // Note that we add 1 here because the offset is relative to one word
3242   // before the start of the identification block, which was historically
3243   // always the start of the regular bitcode header.
3244   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
3245 
3246   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3247 
3248   auto Abbv = std::make_shared<BitCodeAbbrev>();
3249   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
3250   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
3251   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
3252   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3253 
3254   for (const Function &F : M) {
3255     uint64_t Record[2];
3256 
3257     if (F.isDeclaration())
3258       continue;
3259 
3260     Record[0] = VE.getValueID(&F);
3261 
3262     // Save the word offset of the function (from the start of the
3263     // actual bitcode written to the stream).
3264     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
3265     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
3266     // Note that we add 1 here because the offset is relative to one word
3267     // before the start of the identification block, which was historically
3268     // always the start of the regular bitcode header.
3269     Record[1] = BitcodeIndex / 32 + 1;
3270 
3271     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
3272   }
3273 
3274   Stream.ExitBlock();
3275 }
3276 
3277 /// Emit names for arguments, instructions and basic blocks in a function.
3278 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
3279     const ValueSymbolTable &VST) {
3280   if (VST.empty())
3281     return;
3282 
3283   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3284 
3285   // FIXME: Set up the abbrev, we know how many values there are!
3286   // FIXME: We know if the type names can use 7-bit ascii.
3287   SmallVector<uint64_t, 64> NameVals;
3288 
3289   for (const ValueName &Name : VST) {
3290     // Figure out the encoding to use for the name.
3291     StringEncoding Bits = getStringEncoding(Name.getKey());
3292 
3293     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
3294     NameVals.push_back(VE.getValueID(Name.getValue()));
3295 
3296     // VST_CODE_ENTRY:   [valueid, namechar x N]
3297     // VST_CODE_BBENTRY: [bbid, namechar x N]
3298     unsigned Code;
3299     if (isa<BasicBlock>(Name.getValue())) {
3300       Code = bitc::VST_CODE_BBENTRY;
3301       if (Bits == SE_Char6)
3302         AbbrevToUse = VST_BBENTRY_6_ABBREV;
3303     } else {
3304       Code = bitc::VST_CODE_ENTRY;
3305       if (Bits == SE_Char6)
3306         AbbrevToUse = VST_ENTRY_6_ABBREV;
3307       else if (Bits == SE_Fixed7)
3308         AbbrevToUse = VST_ENTRY_7_ABBREV;
3309     }
3310 
3311     for (const auto P : Name.getKey())
3312       NameVals.push_back((unsigned char)P);
3313 
3314     // Emit the finished record.
3315     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
3316     NameVals.clear();
3317   }
3318 
3319   Stream.ExitBlock();
3320 }
3321 
3322 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3323   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3324   unsigned Code;
3325   if (isa<BasicBlock>(Order.V))
3326     Code = bitc::USELIST_CODE_BB;
3327   else
3328     Code = bitc::USELIST_CODE_DEFAULT;
3329 
3330   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3331   Record.push_back(VE.getValueID(Order.V));
3332   Stream.EmitRecord(Code, Record);
3333 }
3334 
3335 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3336   assert(VE.shouldPreserveUseListOrder() &&
3337          "Expected to be preserving use-list order");
3338 
3339   auto hasMore = [&]() {
3340     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3341   };
3342   if (!hasMore())
3343     // Nothing to do.
3344     return;
3345 
3346   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3347   while (hasMore()) {
3348     writeUseList(std::move(VE.UseListOrders.back()));
3349     VE.UseListOrders.pop_back();
3350   }
3351   Stream.ExitBlock();
3352 }
3353 
3354 /// Emit a function body to the module stream.
3355 void ModuleBitcodeWriter::writeFunction(
3356     const Function &F,
3357     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3358   // Save the bitcode index of the start of this function block for recording
3359   // in the VST.
3360   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3361 
3362   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3363   VE.incorporateFunction(F);
3364 
3365   SmallVector<unsigned, 64> Vals;
3366 
3367   // Emit the number of basic blocks, so the reader can create them ahead of
3368   // time.
3369   Vals.push_back(VE.getBasicBlocks().size());
3370   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3371   Vals.clear();
3372 
3373   // If there are function-local constants, emit them now.
3374   unsigned CstStart, CstEnd;
3375   VE.getFunctionConstantRange(CstStart, CstEnd);
3376   writeConstants(CstStart, CstEnd, false);
3377 
3378   // If there is function-local metadata, emit it now.
3379   writeFunctionMetadata(F);
3380 
3381   // Keep a running idea of what the instruction ID is.
3382   unsigned InstID = CstEnd;
3383 
3384   bool NeedsMetadataAttachment = F.hasMetadata();
3385 
3386   DILocation *LastDL = nullptr;
3387   SmallSetVector<Function *, 4> BlockAddressUsers;
3388 
3389   // Finally, emit all the instructions, in order.
3390   for (const BasicBlock &BB : F) {
3391     for (const Instruction &I : BB) {
3392       writeInstruction(I, InstID, Vals);
3393 
3394       if (!I.getType()->isVoidTy())
3395         ++InstID;
3396 
3397       // If the instruction has metadata, write a metadata attachment later.
3398       NeedsMetadataAttachment |= I.hasMetadataOtherThanDebugLoc();
3399 
3400       // If the instruction has a debug location, emit it.
3401       DILocation *DL = I.getDebugLoc();
3402       if (!DL)
3403         continue;
3404 
3405       if (DL == LastDL) {
3406         // Just repeat the same debug loc as last time.
3407         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3408         continue;
3409       }
3410 
3411       Vals.push_back(DL->getLine());
3412       Vals.push_back(DL->getColumn());
3413       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3414       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3415       Vals.push_back(DL->isImplicitCode());
3416       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3417       Vals.clear();
3418 
3419       LastDL = DL;
3420     }
3421 
3422     if (BlockAddress *BA = BlockAddress::lookup(&BB)) {
3423       SmallVector<Value *> Worklist{BA};
3424       SmallPtrSet<Value *, 8> Visited{BA};
3425       while (!Worklist.empty()) {
3426         Value *V = Worklist.pop_back_val();
3427         for (User *U : V->users()) {
3428           if (auto *I = dyn_cast<Instruction>(U)) {
3429             Function *P = I->getFunction();
3430             if (P != &F)
3431               BlockAddressUsers.insert(P);
3432           } else if (isa<Constant>(U) && !isa<GlobalValue>(U) &&
3433                      Visited.insert(U).second)
3434             Worklist.push_back(U);
3435         }
3436       }
3437     }
3438   }
3439 
3440   if (!BlockAddressUsers.empty()) {
3441     Vals.resize(BlockAddressUsers.size());
3442     for (auto I : llvm::enumerate(BlockAddressUsers))
3443       Vals[I.index()] = VE.getValueID(I.value());
3444     Stream.EmitRecord(bitc::FUNC_CODE_BLOCKADDR_USERS, Vals);
3445     Vals.clear();
3446   }
3447 
3448   // Emit names for all the instructions etc.
3449   if (auto *Symtab = F.getValueSymbolTable())
3450     writeFunctionLevelValueSymbolTable(*Symtab);
3451 
3452   if (NeedsMetadataAttachment)
3453     writeFunctionMetadataAttachment(F);
3454   if (VE.shouldPreserveUseListOrder())
3455     writeUseListBlock(&F);
3456   VE.purgeFunction();
3457   Stream.ExitBlock();
3458 }
3459 
3460 // Emit blockinfo, which defines the standard abbreviations etc.
3461 void ModuleBitcodeWriter::writeBlockInfo() {
3462   // We only want to emit block info records for blocks that have multiple
3463   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3464   // Other blocks can define their abbrevs inline.
3465   Stream.EnterBlockInfoBlock();
3466 
3467   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3468     auto Abbv = std::make_shared<BitCodeAbbrev>();
3469     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3470     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3471     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3472     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3473     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3474         VST_ENTRY_8_ABBREV)
3475       llvm_unreachable("Unexpected abbrev ordering!");
3476   }
3477 
3478   { // 7-bit fixed width VST_CODE_ENTRY strings.
3479     auto Abbv = std::make_shared<BitCodeAbbrev>();
3480     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3481     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3482     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3483     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3484     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3485         VST_ENTRY_7_ABBREV)
3486       llvm_unreachable("Unexpected abbrev ordering!");
3487   }
3488   { // 6-bit char6 VST_CODE_ENTRY strings.
3489     auto Abbv = std::make_shared<BitCodeAbbrev>();
3490     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3491     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3492     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3493     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3494     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3495         VST_ENTRY_6_ABBREV)
3496       llvm_unreachable("Unexpected abbrev ordering!");
3497   }
3498   { // 6-bit char6 VST_CODE_BBENTRY strings.
3499     auto Abbv = std::make_shared<BitCodeAbbrev>();
3500     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3501     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3502     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3503     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3504     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3505         VST_BBENTRY_6_ABBREV)
3506       llvm_unreachable("Unexpected abbrev ordering!");
3507   }
3508 
3509   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3510     auto Abbv = std::make_shared<BitCodeAbbrev>();
3511     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3512     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3513                               VE.computeBitsRequiredForTypeIndicies()));
3514     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3515         CONSTANTS_SETTYPE_ABBREV)
3516       llvm_unreachable("Unexpected abbrev ordering!");
3517   }
3518 
3519   { // INTEGER abbrev for CONSTANTS_BLOCK.
3520     auto Abbv = std::make_shared<BitCodeAbbrev>();
3521     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3522     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3523     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3524         CONSTANTS_INTEGER_ABBREV)
3525       llvm_unreachable("Unexpected abbrev ordering!");
3526   }
3527 
3528   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3529     auto Abbv = std::make_shared<BitCodeAbbrev>();
3530     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3531     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3532     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3533                               VE.computeBitsRequiredForTypeIndicies()));
3534     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3535 
3536     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3537         CONSTANTS_CE_CAST_Abbrev)
3538       llvm_unreachable("Unexpected abbrev ordering!");
3539   }
3540   { // NULL abbrev for CONSTANTS_BLOCK.
3541     auto Abbv = std::make_shared<BitCodeAbbrev>();
3542     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3543     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3544         CONSTANTS_NULL_Abbrev)
3545       llvm_unreachable("Unexpected abbrev ordering!");
3546   }
3547 
3548   // FIXME: This should only use space for first class types!
3549 
3550   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3551     auto Abbv = std::make_shared<BitCodeAbbrev>();
3552     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3553     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3554     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3555                               VE.computeBitsRequiredForTypeIndicies()));
3556     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3557     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3558     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3559         FUNCTION_INST_LOAD_ABBREV)
3560       llvm_unreachable("Unexpected abbrev ordering!");
3561   }
3562   { // INST_UNOP abbrev for FUNCTION_BLOCK.
3563     auto Abbv = std::make_shared<BitCodeAbbrev>();
3564     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3565     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3566     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3567     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3568         FUNCTION_INST_UNOP_ABBREV)
3569       llvm_unreachable("Unexpected abbrev ordering!");
3570   }
3571   { // INST_UNOP_FLAGS abbrev for FUNCTION_BLOCK.
3572     auto Abbv = std::make_shared<BitCodeAbbrev>();
3573     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3574     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3575     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3576     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3577     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3578         FUNCTION_INST_UNOP_FLAGS_ABBREV)
3579       llvm_unreachable("Unexpected abbrev ordering!");
3580   }
3581   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3582     auto Abbv = std::make_shared<BitCodeAbbrev>();
3583     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3584     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3585     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3586     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3587     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3588         FUNCTION_INST_BINOP_ABBREV)
3589       llvm_unreachable("Unexpected abbrev ordering!");
3590   }
3591   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3592     auto Abbv = std::make_shared<BitCodeAbbrev>();
3593     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3594     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3595     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3596     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3597     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3598     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3599         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3600       llvm_unreachable("Unexpected abbrev ordering!");
3601   }
3602   { // INST_CAST abbrev for FUNCTION_BLOCK.
3603     auto Abbv = std::make_shared<BitCodeAbbrev>();
3604     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3605     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3606     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3607                               VE.computeBitsRequiredForTypeIndicies()));
3608     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3609     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3610         FUNCTION_INST_CAST_ABBREV)
3611       llvm_unreachable("Unexpected abbrev ordering!");
3612   }
3613 
3614   { // INST_RET abbrev for FUNCTION_BLOCK.
3615     auto Abbv = std::make_shared<BitCodeAbbrev>();
3616     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3617     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3618         FUNCTION_INST_RET_VOID_ABBREV)
3619       llvm_unreachable("Unexpected abbrev ordering!");
3620   }
3621   { // INST_RET abbrev for FUNCTION_BLOCK.
3622     auto Abbv = std::make_shared<BitCodeAbbrev>();
3623     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3624     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3625     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3626         FUNCTION_INST_RET_VAL_ABBREV)
3627       llvm_unreachable("Unexpected abbrev ordering!");
3628   }
3629   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3630     auto Abbv = std::make_shared<BitCodeAbbrev>();
3631     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3632     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3633         FUNCTION_INST_UNREACHABLE_ABBREV)
3634       llvm_unreachable("Unexpected abbrev ordering!");
3635   }
3636   {
3637     auto Abbv = std::make_shared<BitCodeAbbrev>();
3638     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3639     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3640     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3641                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3642     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3643     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3644     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3645         FUNCTION_INST_GEP_ABBREV)
3646       llvm_unreachable("Unexpected abbrev ordering!");
3647   }
3648 
3649   Stream.ExitBlock();
3650 }
3651 
3652 /// Write the module path strings, currently only used when generating
3653 /// a combined index file.
3654 void IndexBitcodeWriter::writeModStrings() {
3655   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3656 
3657   // TODO: See which abbrev sizes we actually need to emit
3658 
3659   // 8-bit fixed-width MST_ENTRY strings.
3660   auto Abbv = std::make_shared<BitCodeAbbrev>();
3661   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3662   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3663   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3664   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3665   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3666 
3667   // 7-bit fixed width MST_ENTRY strings.
3668   Abbv = std::make_shared<BitCodeAbbrev>();
3669   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3670   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3671   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3672   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3673   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3674 
3675   // 6-bit char6 MST_ENTRY strings.
3676   Abbv = std::make_shared<BitCodeAbbrev>();
3677   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3678   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3679   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3680   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3681   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3682 
3683   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3684   Abbv = std::make_shared<BitCodeAbbrev>();
3685   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3686   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3687   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3688   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3689   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3690   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3691   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3692 
3693   SmallVector<unsigned, 64> Vals;
3694   forEachModule(
3695       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3696         StringRef Key = MPSE.getKey();
3697         const auto &Value = MPSE.getValue();
3698         StringEncoding Bits = getStringEncoding(Key);
3699         unsigned AbbrevToUse = Abbrev8Bit;
3700         if (Bits == SE_Char6)
3701           AbbrevToUse = Abbrev6Bit;
3702         else if (Bits == SE_Fixed7)
3703           AbbrevToUse = Abbrev7Bit;
3704 
3705         Vals.push_back(Value.first);
3706         Vals.append(Key.begin(), Key.end());
3707 
3708         // Emit the finished record.
3709         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3710 
3711         // Emit an optional hash for the module now
3712         const auto &Hash = Value.second;
3713         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3714           Vals.assign(Hash.begin(), Hash.end());
3715           // Emit the hash record.
3716           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3717         }
3718 
3719         Vals.clear();
3720       });
3721   Stream.ExitBlock();
3722 }
3723 
3724 /// Write the function type metadata related records that need to appear before
3725 /// a function summary entry (whether per-module or combined).
3726 template <typename Fn>
3727 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3728                                              FunctionSummary *FS,
3729                                              Fn GetValueID) {
3730   if (!FS->type_tests().empty())
3731     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3732 
3733   SmallVector<uint64_t, 64> Record;
3734 
3735   auto WriteVFuncIdVec = [&](uint64_t Ty,
3736                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3737     if (VFs.empty())
3738       return;
3739     Record.clear();
3740     for (auto &VF : VFs) {
3741       Record.push_back(VF.GUID);
3742       Record.push_back(VF.Offset);
3743     }
3744     Stream.EmitRecord(Ty, Record);
3745   };
3746 
3747   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3748                   FS->type_test_assume_vcalls());
3749   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3750                   FS->type_checked_load_vcalls());
3751 
3752   auto WriteConstVCallVec = [&](uint64_t Ty,
3753                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3754     for (auto &VC : VCs) {
3755       Record.clear();
3756       Record.push_back(VC.VFunc.GUID);
3757       Record.push_back(VC.VFunc.Offset);
3758       llvm::append_range(Record, VC.Args);
3759       Stream.EmitRecord(Ty, Record);
3760     }
3761   };
3762 
3763   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3764                      FS->type_test_assume_const_vcalls());
3765   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3766                      FS->type_checked_load_const_vcalls());
3767 
3768   auto WriteRange = [&](ConstantRange Range) {
3769     Range = Range.sextOrTrunc(FunctionSummary::ParamAccess::RangeWidth);
3770     assert(Range.getLower().getNumWords() == 1);
3771     assert(Range.getUpper().getNumWords() == 1);
3772     emitSignedInt64(Record, *Range.getLower().getRawData());
3773     emitSignedInt64(Record, *Range.getUpper().getRawData());
3774   };
3775 
3776   if (!FS->paramAccesses().empty()) {
3777     Record.clear();
3778     for (auto &Arg : FS->paramAccesses()) {
3779       size_t UndoSize = Record.size();
3780       Record.push_back(Arg.ParamNo);
3781       WriteRange(Arg.Use);
3782       Record.push_back(Arg.Calls.size());
3783       for (auto &Call : Arg.Calls) {
3784         Record.push_back(Call.ParamNo);
3785         Optional<unsigned> ValueID = GetValueID(Call.Callee);
3786         if (!ValueID) {
3787           // If ValueID is unknown we can't drop just this call, we must drop
3788           // entire parameter.
3789           Record.resize(UndoSize);
3790           break;
3791         }
3792         Record.push_back(*ValueID);
3793         WriteRange(Call.Offsets);
3794       }
3795     }
3796     if (!Record.empty())
3797       Stream.EmitRecord(bitc::FS_PARAM_ACCESS, Record);
3798   }
3799 }
3800 
3801 /// Collect type IDs from type tests used by function.
3802 static void
3803 getReferencedTypeIds(FunctionSummary *FS,
3804                      std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3805   if (!FS->type_tests().empty())
3806     for (auto &TT : FS->type_tests())
3807       ReferencedTypeIds.insert(TT);
3808 
3809   auto GetReferencedTypesFromVFuncIdVec =
3810       [&](ArrayRef<FunctionSummary::VFuncId> VFs) {
3811         for (auto &VF : VFs)
3812           ReferencedTypeIds.insert(VF.GUID);
3813       };
3814 
3815   GetReferencedTypesFromVFuncIdVec(FS->type_test_assume_vcalls());
3816   GetReferencedTypesFromVFuncIdVec(FS->type_checked_load_vcalls());
3817 
3818   auto GetReferencedTypesFromConstVCallVec =
3819       [&](ArrayRef<FunctionSummary::ConstVCall> VCs) {
3820         for (auto &VC : VCs)
3821           ReferencedTypeIds.insert(VC.VFunc.GUID);
3822       };
3823 
3824   GetReferencedTypesFromConstVCallVec(FS->type_test_assume_const_vcalls());
3825   GetReferencedTypesFromConstVCallVec(FS->type_checked_load_const_vcalls());
3826 }
3827 
3828 static void writeWholeProgramDevirtResolutionByArg(
3829     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3830     const WholeProgramDevirtResolution::ByArg &ByArg) {
3831   NameVals.push_back(args.size());
3832   llvm::append_range(NameVals, args);
3833 
3834   NameVals.push_back(ByArg.TheKind);
3835   NameVals.push_back(ByArg.Info);
3836   NameVals.push_back(ByArg.Byte);
3837   NameVals.push_back(ByArg.Bit);
3838 }
3839 
3840 static void writeWholeProgramDevirtResolution(
3841     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3842     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3843   NameVals.push_back(Id);
3844 
3845   NameVals.push_back(Wpd.TheKind);
3846   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3847   NameVals.push_back(Wpd.SingleImplName.size());
3848 
3849   NameVals.push_back(Wpd.ResByArg.size());
3850   for (auto &A : Wpd.ResByArg)
3851     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3852 }
3853 
3854 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3855                                      StringTableBuilder &StrtabBuilder,
3856                                      const std::string &Id,
3857                                      const TypeIdSummary &Summary) {
3858   NameVals.push_back(StrtabBuilder.add(Id));
3859   NameVals.push_back(Id.size());
3860 
3861   NameVals.push_back(Summary.TTRes.TheKind);
3862   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3863   NameVals.push_back(Summary.TTRes.AlignLog2);
3864   NameVals.push_back(Summary.TTRes.SizeM1);
3865   NameVals.push_back(Summary.TTRes.BitMask);
3866   NameVals.push_back(Summary.TTRes.InlineBits);
3867 
3868   for (auto &W : Summary.WPDRes)
3869     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3870                                       W.second);
3871 }
3872 
3873 static void writeTypeIdCompatibleVtableSummaryRecord(
3874     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3875     const std::string &Id, const TypeIdCompatibleVtableInfo &Summary,
3876     ValueEnumerator &VE) {
3877   NameVals.push_back(StrtabBuilder.add(Id));
3878   NameVals.push_back(Id.size());
3879 
3880   for (auto &P : Summary) {
3881     NameVals.push_back(P.AddressPointOffset);
3882     NameVals.push_back(VE.getValueID(P.VTableVI.getValue()));
3883   }
3884 }
3885 
3886 // Helper to emit a single function summary record.
3887 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3888     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3889     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3890     const Function &F) {
3891   NameVals.push_back(ValueID);
3892 
3893   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3894 
3895   writeFunctionTypeMetadataRecords(
3896       Stream, FS, [&](const ValueInfo &VI) -> Optional<unsigned> {
3897         return {VE.getValueID(VI.getValue())};
3898       });
3899 
3900   auto SpecialRefCnts = FS->specialRefCounts();
3901   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3902   NameVals.push_back(FS->instCount());
3903   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3904   NameVals.push_back(FS->refs().size());
3905   NameVals.push_back(SpecialRefCnts.first);  // rorefcnt
3906   NameVals.push_back(SpecialRefCnts.second); // worefcnt
3907 
3908   for (auto &RI : FS->refs())
3909     NameVals.push_back(VE.getValueID(RI.getValue()));
3910 
3911   bool HasProfileData =
3912       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3913   for (auto &ECI : FS->calls()) {
3914     NameVals.push_back(getValueId(ECI.first));
3915     if (HasProfileData)
3916       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3917     else if (WriteRelBFToSummary)
3918       NameVals.push_back(ECI.second.RelBlockFreq);
3919   }
3920 
3921   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3922   unsigned Code =
3923       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3924                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3925                                              : bitc::FS_PERMODULE));
3926 
3927   // Emit the finished record.
3928   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3929   NameVals.clear();
3930 }
3931 
3932 // Collect the global value references in the given variable's initializer,
3933 // and emit them in a summary record.
3934 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3935     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3936     unsigned FSModRefsAbbrev, unsigned FSModVTableRefsAbbrev) {
3937   auto VI = Index->getValueInfo(V.getGUID());
3938   if (!VI || VI.getSummaryList().empty()) {
3939     // Only declarations should not have a summary (a declaration might however
3940     // have a summary if the def was in module level asm).
3941     assert(V.isDeclaration());
3942     return;
3943   }
3944   auto *Summary = VI.getSummaryList()[0].get();
3945   NameVals.push_back(VE.getValueID(&V));
3946   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3947   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3948   NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
3949 
3950   auto VTableFuncs = VS->vTableFuncs();
3951   if (!VTableFuncs.empty())
3952     NameVals.push_back(VS->refs().size());
3953 
3954   unsigned SizeBeforeRefs = NameVals.size();
3955   for (auto &RI : VS->refs())
3956     NameVals.push_back(VE.getValueID(RI.getValue()));
3957   // Sort the refs for determinism output, the vector returned by FS->refs() has
3958   // been initialized from a DenseSet.
3959   llvm::sort(drop_begin(NameVals, SizeBeforeRefs));
3960 
3961   if (VTableFuncs.empty())
3962     Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3963                       FSModRefsAbbrev);
3964   else {
3965     // VTableFuncs pairs should already be sorted by offset.
3966     for (auto &P : VTableFuncs) {
3967       NameVals.push_back(VE.getValueID(P.FuncVI.getValue()));
3968       NameVals.push_back(P.VTableOffset);
3969     }
3970 
3971     Stream.EmitRecord(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS, NameVals,
3972                       FSModVTableRefsAbbrev);
3973   }
3974   NameVals.clear();
3975 }
3976 
3977 /// Emit the per-module summary section alongside the rest of
3978 /// the module's bitcode.
3979 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3980   // By default we compile with ThinLTO if the module has a summary, but the
3981   // client can request full LTO with a module flag.
3982   bool IsThinLTO = true;
3983   if (auto *MD =
3984           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3985     IsThinLTO = MD->getZExtValue();
3986   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3987                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3988                        4);
3989 
3990   Stream.EmitRecord(
3991       bitc::FS_VERSION,
3992       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
3993 
3994   // Write the index flags.
3995   uint64_t Flags = 0;
3996   // Bits 1-3 are set only in the combined index, skip them.
3997   if (Index->enableSplitLTOUnit())
3998     Flags |= 0x8;
3999   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
4000 
4001   if (Index->begin() == Index->end()) {
4002     Stream.ExitBlock();
4003     return;
4004   }
4005 
4006   for (const auto &GVI : valueIds()) {
4007     Stream.EmitRecord(bitc::FS_VALUE_GUID,
4008                       ArrayRef<uint64_t>{GVI.second, GVI.first});
4009   }
4010 
4011   // Abbrev for FS_PERMODULE_PROFILE.
4012   auto Abbv = std::make_shared<BitCodeAbbrev>();
4013   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
4014   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4015   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4016   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4017   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4018   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4019   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4020   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4021   // numrefs x valueid, n x (valueid, hotness)
4022   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4023   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4024   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4025 
4026   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
4027   Abbv = std::make_shared<BitCodeAbbrev>();
4028   if (WriteRelBFToSummary)
4029     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
4030   else
4031     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
4032   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4034   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4035   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4036   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4037   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4038   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4039   // numrefs x valueid, n x (valueid [, rel_block_freq])
4040   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4041   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4042   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4043 
4044   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
4045   Abbv = std::make_shared<BitCodeAbbrev>();
4046   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
4047   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4048   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
4049   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
4050   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4051   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4052 
4053   // Abbrev for FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS.
4054   Abbv = std::make_shared<BitCodeAbbrev>();
4055   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS));
4056   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4057   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
4058   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numrefs
4059   // numrefs x valueid, n x (valueid , offset)
4060   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4061   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4062   unsigned FSModVTableRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4063 
4064   // Abbrev for FS_ALIAS.
4065   Abbv = std::make_shared<BitCodeAbbrev>();
4066   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
4067   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4068   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4069   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4070   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4071 
4072   // Abbrev for FS_TYPE_ID_METADATA
4073   Abbv = std::make_shared<BitCodeAbbrev>();
4074   Abbv->Add(BitCodeAbbrevOp(bitc::FS_TYPE_ID_METADATA));
4075   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid strtab index
4076   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid length
4077   // n x (valueid , offset)
4078   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4079   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4080   unsigned TypeIdCompatibleVtableAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4081 
4082   SmallVector<uint64_t, 64> NameVals;
4083   // Iterate over the list of functions instead of the Index to
4084   // ensure the ordering is stable.
4085   for (const Function &F : M) {
4086     // Summary emission does not support anonymous functions, they have to
4087     // renamed using the anonymous function renaming pass.
4088     if (!F.hasName())
4089       report_fatal_error("Unexpected anonymous function when writing summary");
4090 
4091     ValueInfo VI = Index->getValueInfo(F.getGUID());
4092     if (!VI || VI.getSummaryList().empty()) {
4093       // Only declarations should not have a summary (a declaration might
4094       // however have a summary if the def was in module level asm).
4095       assert(F.isDeclaration());
4096       continue;
4097     }
4098     auto *Summary = VI.getSummaryList()[0].get();
4099     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
4100                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
4101   }
4102 
4103   // Capture references from GlobalVariable initializers, which are outside
4104   // of a function scope.
4105   for (const GlobalVariable &G : M.globals())
4106     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev,
4107                                FSModVTableRefsAbbrev);
4108 
4109   for (const GlobalAlias &A : M.aliases()) {
4110     auto *Aliasee = A.getAliaseeObject();
4111     // Skip ifunc and nameless functions which don't have an entry in the
4112     // summary.
4113     if (!Aliasee->hasName() || isa<GlobalIFunc>(Aliasee))
4114       continue;
4115     auto AliasId = VE.getValueID(&A);
4116     auto AliaseeId = VE.getValueID(Aliasee);
4117     NameVals.push_back(AliasId);
4118     auto *Summary = Index->getGlobalValueSummary(A);
4119     AliasSummary *AS = cast<AliasSummary>(Summary);
4120     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4121     NameVals.push_back(AliaseeId);
4122     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
4123     NameVals.clear();
4124   }
4125 
4126   for (auto &S : Index->typeIdCompatibleVtableMap()) {
4127     writeTypeIdCompatibleVtableSummaryRecord(NameVals, StrtabBuilder, S.first,
4128                                              S.second, VE);
4129     Stream.EmitRecord(bitc::FS_TYPE_ID_METADATA, NameVals,
4130                       TypeIdCompatibleVtableAbbrev);
4131     NameVals.clear();
4132   }
4133 
4134   Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
4135                     ArrayRef<uint64_t>{Index->getBlockCount()});
4136 
4137   Stream.ExitBlock();
4138 }
4139 
4140 /// Emit the combined summary section into the combined index file.
4141 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
4142   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
4143   Stream.EmitRecord(
4144       bitc::FS_VERSION,
4145       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
4146 
4147   // Write the index flags.
4148   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Index.getFlags()});
4149 
4150   for (const auto &GVI : valueIds()) {
4151     Stream.EmitRecord(bitc::FS_VALUE_GUID,
4152                       ArrayRef<uint64_t>{GVI.second, GVI.first});
4153   }
4154 
4155   // Abbrev for FS_COMBINED.
4156   auto Abbv = std::make_shared<BitCodeAbbrev>();
4157   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
4158   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4159   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4160   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4161   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4162   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4163   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
4164   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4165   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4166   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4167   // numrefs x valueid, n x (valueid)
4168   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4169   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4170   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4171 
4172   // Abbrev for FS_COMBINED_PROFILE.
4173   Abbv = std::make_shared<BitCodeAbbrev>();
4174   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
4175   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4176   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4177   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4178   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4179   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4180   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
4181   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4182   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4183   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4184   // numrefs x valueid, n x (valueid, hotness)
4185   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4186   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4187   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4188 
4189   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
4190   Abbv = std::make_shared<BitCodeAbbrev>();
4191   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
4192   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4193   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4194   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4195   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
4196   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4197   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4198 
4199   // Abbrev for FS_COMBINED_ALIAS.
4200   Abbv = std::make_shared<BitCodeAbbrev>();
4201   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
4202   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4203   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4204   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4205   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4206   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4207 
4208   // The aliases are emitted as a post-pass, and will point to the value
4209   // id of the aliasee. Save them in a vector for post-processing.
4210   SmallVector<AliasSummary *, 64> Aliases;
4211 
4212   // Save the value id for each summary for alias emission.
4213   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
4214 
4215   SmallVector<uint64_t, 64> NameVals;
4216 
4217   // Set that will be populated during call to writeFunctionTypeMetadataRecords
4218   // with the type ids referenced by this index file.
4219   std::set<GlobalValue::GUID> ReferencedTypeIds;
4220 
4221   // For local linkage, we also emit the original name separately
4222   // immediately after the record.
4223   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
4224     // We don't need to emit the original name if we are writing the index for
4225     // distributed backends (in which case ModuleToSummariesForIndex is
4226     // non-null). The original name is only needed during the thin link, since
4227     // for SamplePGO the indirect call targets for local functions have
4228     // have the original name annotated in profile.
4229     // Continue to emit it when writing out the entire combined index, which is
4230     // used in testing the thin link via llvm-lto.
4231     if (ModuleToSummariesForIndex || !GlobalValue::isLocalLinkage(S.linkage()))
4232       return;
4233     NameVals.push_back(S.getOriginalName());
4234     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
4235     NameVals.clear();
4236   };
4237 
4238   std::set<GlobalValue::GUID> DefOrUseGUIDs;
4239   forEachSummary([&](GVInfo I, bool IsAliasee) {
4240     GlobalValueSummary *S = I.second;
4241     assert(S);
4242     DefOrUseGUIDs.insert(I.first);
4243     for (const ValueInfo &VI : S->refs())
4244       DefOrUseGUIDs.insert(VI.getGUID());
4245 
4246     auto ValueId = getValueId(I.first);
4247     assert(ValueId);
4248     SummaryToValueIdMap[S] = *ValueId;
4249 
4250     // If this is invoked for an aliasee, we want to record the above
4251     // mapping, but then not emit a summary entry (if the aliasee is
4252     // to be imported, we will invoke this separately with IsAliasee=false).
4253     if (IsAliasee)
4254       return;
4255 
4256     if (auto *AS = dyn_cast<AliasSummary>(S)) {
4257       // Will process aliases as a post-pass because the reader wants all
4258       // global to be loaded first.
4259       Aliases.push_back(AS);
4260       return;
4261     }
4262 
4263     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
4264       NameVals.push_back(*ValueId);
4265       NameVals.push_back(Index.getModuleId(VS->modulePath()));
4266       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
4267       NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
4268       for (auto &RI : VS->refs()) {
4269         auto RefValueId = getValueId(RI.getGUID());
4270         if (!RefValueId)
4271           continue;
4272         NameVals.push_back(*RefValueId);
4273       }
4274 
4275       // Emit the finished record.
4276       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
4277                         FSModRefsAbbrev);
4278       NameVals.clear();
4279       MaybeEmitOriginalName(*S);
4280       return;
4281     }
4282 
4283     auto GetValueId = [&](const ValueInfo &VI) -> Optional<unsigned> {
4284       return getValueId(VI.getGUID());
4285     };
4286 
4287     auto *FS = cast<FunctionSummary>(S);
4288     writeFunctionTypeMetadataRecords(Stream, FS, GetValueId);
4289     getReferencedTypeIds(FS, ReferencedTypeIds);
4290 
4291     NameVals.push_back(*ValueId);
4292     NameVals.push_back(Index.getModuleId(FS->modulePath()));
4293     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
4294     NameVals.push_back(FS->instCount());
4295     NameVals.push_back(getEncodedFFlags(FS->fflags()));
4296     NameVals.push_back(FS->entryCount());
4297 
4298     // Fill in below
4299     NameVals.push_back(0); // numrefs
4300     NameVals.push_back(0); // rorefcnt
4301     NameVals.push_back(0); // worefcnt
4302 
4303     unsigned Count = 0, RORefCnt = 0, WORefCnt = 0;
4304     for (auto &RI : FS->refs()) {
4305       auto RefValueId = getValueId(RI.getGUID());
4306       if (!RefValueId)
4307         continue;
4308       NameVals.push_back(*RefValueId);
4309       if (RI.isReadOnly())
4310         RORefCnt++;
4311       else if (RI.isWriteOnly())
4312         WORefCnt++;
4313       Count++;
4314     }
4315     NameVals[6] = Count;
4316     NameVals[7] = RORefCnt;
4317     NameVals[8] = WORefCnt;
4318 
4319     bool HasProfileData = false;
4320     for (auto &EI : FS->calls()) {
4321       HasProfileData |=
4322           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
4323       if (HasProfileData)
4324         break;
4325     }
4326 
4327     for (auto &EI : FS->calls()) {
4328       // If this GUID doesn't have a value id, it doesn't have a function
4329       // summary and we don't need to record any calls to it.
4330       Optional<unsigned> CallValueId = GetValueId(EI.first);
4331       if (!CallValueId)
4332         continue;
4333       NameVals.push_back(*CallValueId);
4334       if (HasProfileData)
4335         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
4336     }
4337 
4338     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
4339     unsigned Code =
4340         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
4341 
4342     // Emit the finished record.
4343     Stream.EmitRecord(Code, NameVals, FSAbbrev);
4344     NameVals.clear();
4345     MaybeEmitOriginalName(*S);
4346   });
4347 
4348   for (auto *AS : Aliases) {
4349     auto AliasValueId = SummaryToValueIdMap[AS];
4350     assert(AliasValueId);
4351     NameVals.push_back(AliasValueId);
4352     NameVals.push_back(Index.getModuleId(AS->modulePath()));
4353     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4354     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
4355     assert(AliaseeValueId);
4356     NameVals.push_back(AliaseeValueId);
4357 
4358     // Emit the finished record.
4359     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
4360     NameVals.clear();
4361     MaybeEmitOriginalName(*AS);
4362 
4363     if (auto *FS = dyn_cast<FunctionSummary>(&AS->getAliasee()))
4364       getReferencedTypeIds(FS, ReferencedTypeIds);
4365   }
4366 
4367   if (!Index.cfiFunctionDefs().empty()) {
4368     for (auto &S : Index.cfiFunctionDefs()) {
4369       if (DefOrUseGUIDs.count(
4370               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4371         NameVals.push_back(StrtabBuilder.add(S));
4372         NameVals.push_back(S.size());
4373       }
4374     }
4375     if (!NameVals.empty()) {
4376       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
4377       NameVals.clear();
4378     }
4379   }
4380 
4381   if (!Index.cfiFunctionDecls().empty()) {
4382     for (auto &S : Index.cfiFunctionDecls()) {
4383       if (DefOrUseGUIDs.count(
4384               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4385         NameVals.push_back(StrtabBuilder.add(S));
4386         NameVals.push_back(S.size());
4387       }
4388     }
4389     if (!NameVals.empty()) {
4390       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
4391       NameVals.clear();
4392     }
4393   }
4394 
4395   // Walk the GUIDs that were referenced, and write the
4396   // corresponding type id records.
4397   for (auto &T : ReferencedTypeIds) {
4398     auto TidIter = Index.typeIds().equal_range(T);
4399     for (auto It = TidIter.first; It != TidIter.second; ++It) {
4400       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, It->second.first,
4401                                It->second.second);
4402       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
4403       NameVals.clear();
4404     }
4405   }
4406 
4407   Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
4408                     ArrayRef<uint64_t>{Index.getBlockCount()});
4409 
4410   Stream.ExitBlock();
4411 }
4412 
4413 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
4414 /// current llvm version, and a record for the epoch number.
4415 static void writeIdentificationBlock(BitstreamWriter &Stream) {
4416   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
4417 
4418   // Write the "user readable" string identifying the bitcode producer
4419   auto Abbv = std::make_shared<BitCodeAbbrev>();
4420   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
4421   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4422   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
4423   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4424   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
4425                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
4426 
4427   // Write the epoch version
4428   Abbv = std::make_shared<BitCodeAbbrev>();
4429   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
4430   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
4431   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4432   constexpr std::array<unsigned, 1> Vals = {{bitc::BITCODE_CURRENT_EPOCH}};
4433   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
4434   Stream.ExitBlock();
4435 }
4436 
4437 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
4438   // Emit the module's hash.
4439   // MODULE_CODE_HASH: [5*i32]
4440   if (GenerateHash) {
4441     uint32_t Vals[5];
4442     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
4443                                     Buffer.size() - BlockStartPos));
4444     std::array<uint8_t, 20> Hash = Hasher.result();
4445     for (int Pos = 0; Pos < 20; Pos += 4) {
4446       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
4447     }
4448 
4449     // Emit the finished record.
4450     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
4451 
4452     if (ModHash)
4453       // Save the written hash value.
4454       llvm::copy(Vals, std::begin(*ModHash));
4455   }
4456 }
4457 
4458 void ModuleBitcodeWriter::write() {
4459   writeIdentificationBlock(Stream);
4460 
4461   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4462   size_t BlockStartPos = Buffer.size();
4463 
4464   writeModuleVersion();
4465 
4466   // Emit blockinfo, which defines the standard abbreviations etc.
4467   writeBlockInfo();
4468 
4469   // Emit information describing all of the types in the module.
4470   writeTypeTable();
4471 
4472   // Emit information about attribute groups.
4473   writeAttributeGroupTable();
4474 
4475   // Emit information about parameter attributes.
4476   writeAttributeTable();
4477 
4478   writeComdats();
4479 
4480   // Emit top-level description of module, including target triple, inline asm,
4481   // descriptors for global variables, and function prototype info.
4482   writeModuleInfo();
4483 
4484   // Emit constants.
4485   writeModuleConstants();
4486 
4487   // Emit metadata kind names.
4488   writeModuleMetadataKinds();
4489 
4490   // Emit metadata.
4491   writeModuleMetadata();
4492 
4493   // Emit module-level use-lists.
4494   if (VE.shouldPreserveUseListOrder())
4495     writeUseListBlock(nullptr);
4496 
4497   writeOperandBundleTags();
4498   writeSyncScopeNames();
4499 
4500   // Emit function bodies.
4501   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
4502   for (const Function &F : M)
4503     if (!F.isDeclaration())
4504       writeFunction(F, FunctionToBitcodeIndex);
4505 
4506   // Need to write after the above call to WriteFunction which populates
4507   // the summary information in the index.
4508   if (Index)
4509     writePerModuleGlobalValueSummary();
4510 
4511   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
4512 
4513   writeModuleHash(BlockStartPos);
4514 
4515   Stream.ExitBlock();
4516 }
4517 
4518 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
4519                                uint32_t &Position) {
4520   support::endian::write32le(&Buffer[Position], Value);
4521   Position += 4;
4522 }
4523 
4524 /// If generating a bc file on darwin, we have to emit a
4525 /// header and trailer to make it compatible with the system archiver.  To do
4526 /// this we emit the following header, and then emit a trailer that pads the
4527 /// file out to be a multiple of 16 bytes.
4528 ///
4529 /// struct bc_header {
4530 ///   uint32_t Magic;         // 0x0B17C0DE
4531 ///   uint32_t Version;       // Version, currently always 0.
4532 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4533 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4534 ///   uint32_t CPUType;       // CPU specifier.
4535 ///   ... potentially more later ...
4536 /// };
4537 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4538                                          const Triple &TT) {
4539   unsigned CPUType = ~0U;
4540 
4541   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4542   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4543   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4544   // specific constants here because they are implicitly part of the Darwin ABI.
4545   enum {
4546     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4547     DARWIN_CPU_TYPE_X86        = 7,
4548     DARWIN_CPU_TYPE_ARM        = 12,
4549     DARWIN_CPU_TYPE_POWERPC    = 18
4550   };
4551 
4552   Triple::ArchType Arch = TT.getArch();
4553   if (Arch == Triple::x86_64)
4554     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4555   else if (Arch == Triple::x86)
4556     CPUType = DARWIN_CPU_TYPE_X86;
4557   else if (Arch == Triple::ppc)
4558     CPUType = DARWIN_CPU_TYPE_POWERPC;
4559   else if (Arch == Triple::ppc64)
4560     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4561   else if (Arch == Triple::arm || Arch == Triple::thumb)
4562     CPUType = DARWIN_CPU_TYPE_ARM;
4563 
4564   // Traditional Bitcode starts after header.
4565   assert(Buffer.size() >= BWH_HeaderSize &&
4566          "Expected header size to be reserved");
4567   unsigned BCOffset = BWH_HeaderSize;
4568   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4569 
4570   // Write the magic and version.
4571   unsigned Position = 0;
4572   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4573   writeInt32ToBuffer(0, Buffer, Position); // Version.
4574   writeInt32ToBuffer(BCOffset, Buffer, Position);
4575   writeInt32ToBuffer(BCSize, Buffer, Position);
4576   writeInt32ToBuffer(CPUType, Buffer, Position);
4577 
4578   // If the file is not a multiple of 16 bytes, insert dummy padding.
4579   while (Buffer.size() & 15)
4580     Buffer.push_back(0);
4581 }
4582 
4583 /// Helper to write the header common to all bitcode files.
4584 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4585   // Emit the file header.
4586   Stream.Emit((unsigned)'B', 8);
4587   Stream.Emit((unsigned)'C', 8);
4588   Stream.Emit(0x0, 4);
4589   Stream.Emit(0xC, 4);
4590   Stream.Emit(0xE, 4);
4591   Stream.Emit(0xD, 4);
4592 }
4593 
4594 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer, raw_fd_stream *FS)
4595     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer, FS, FlushThreshold)) {
4596   writeBitcodeHeader(*Stream);
4597 }
4598 
4599 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4600 
4601 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4602   Stream->EnterSubblock(Block, 3);
4603 
4604   auto Abbv = std::make_shared<BitCodeAbbrev>();
4605   Abbv->Add(BitCodeAbbrevOp(Record));
4606   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4607   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4608 
4609   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4610 
4611   Stream->ExitBlock();
4612 }
4613 
4614 void BitcodeWriter::writeSymtab() {
4615   assert(!WroteStrtab && !WroteSymtab);
4616 
4617   // If any module has module-level inline asm, we will require a registered asm
4618   // parser for the target so that we can create an accurate symbol table for
4619   // the module.
4620   for (Module *M : Mods) {
4621     if (M->getModuleInlineAsm().empty())
4622       continue;
4623 
4624     std::string Err;
4625     const Triple TT(M->getTargetTriple());
4626     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4627     if (!T || !T->hasMCAsmParser())
4628       return;
4629   }
4630 
4631   WroteSymtab = true;
4632   SmallVector<char, 0> Symtab;
4633   // The irsymtab::build function may be unable to create a symbol table if the
4634   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4635   // table is not required for correctness, but we still want to be able to
4636   // write malformed modules to bitcode files, so swallow the error.
4637   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4638     consumeError(std::move(E));
4639     return;
4640   }
4641 
4642   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4643             {Symtab.data(), Symtab.size()});
4644 }
4645 
4646 void BitcodeWriter::writeStrtab() {
4647   assert(!WroteStrtab);
4648 
4649   std::vector<char> Strtab;
4650   StrtabBuilder.finalizeInOrder();
4651   Strtab.resize(StrtabBuilder.getSize());
4652   StrtabBuilder.write((uint8_t *)Strtab.data());
4653 
4654   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4655             {Strtab.data(), Strtab.size()});
4656 
4657   WroteStrtab = true;
4658 }
4659 
4660 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4661   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4662   WroteStrtab = true;
4663 }
4664 
4665 void BitcodeWriter::writeModule(const Module &M,
4666                                 bool ShouldPreserveUseListOrder,
4667                                 const ModuleSummaryIndex *Index,
4668                                 bool GenerateHash, ModuleHash *ModHash) {
4669   assert(!WroteStrtab);
4670 
4671   // The Mods vector is used by irsymtab::build, which requires non-const
4672   // Modules in case it needs to materialize metadata. But the bitcode writer
4673   // requires that the module is materialized, so we can cast to non-const here,
4674   // after checking that it is in fact materialized.
4675   assert(M.isMaterialized());
4676   Mods.push_back(const_cast<Module *>(&M));
4677 
4678   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4679                                    ShouldPreserveUseListOrder, Index,
4680                                    GenerateHash, ModHash);
4681   ModuleWriter.write();
4682 }
4683 
4684 void BitcodeWriter::writeIndex(
4685     const ModuleSummaryIndex *Index,
4686     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4687   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4688                                  ModuleToSummariesForIndex);
4689   IndexWriter.write();
4690 }
4691 
4692 /// Write the specified module to the specified output stream.
4693 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4694                               bool ShouldPreserveUseListOrder,
4695                               const ModuleSummaryIndex *Index,
4696                               bool GenerateHash, ModuleHash *ModHash) {
4697   SmallVector<char, 0> Buffer;
4698   Buffer.reserve(256*1024);
4699 
4700   // If this is darwin or another generic macho target, reserve space for the
4701   // header.
4702   Triple TT(M.getTargetTriple());
4703   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4704     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4705 
4706   BitcodeWriter Writer(Buffer, dyn_cast<raw_fd_stream>(&Out));
4707   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4708                      ModHash);
4709   Writer.writeSymtab();
4710   Writer.writeStrtab();
4711 
4712   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4713     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4714 
4715   // Write the generated bitstream to "Out".
4716   if (!Buffer.empty())
4717     Out.write((char *)&Buffer.front(), Buffer.size());
4718 }
4719 
4720 void IndexBitcodeWriter::write() {
4721   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4722 
4723   writeModuleVersion();
4724 
4725   // Write the module paths in the combined index.
4726   writeModStrings();
4727 
4728   // Write the summary combined index records.
4729   writeCombinedGlobalValueSummary();
4730 
4731   Stream.ExitBlock();
4732 }
4733 
4734 // Write the specified module summary index to the given raw output stream,
4735 // where it will be written in a new bitcode block. This is used when
4736 // writing the combined index file for ThinLTO. When writing a subset of the
4737 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4738 void llvm::writeIndexToFile(
4739     const ModuleSummaryIndex &Index, raw_ostream &Out,
4740     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4741   SmallVector<char, 0> Buffer;
4742   Buffer.reserve(256 * 1024);
4743 
4744   BitcodeWriter Writer(Buffer);
4745   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4746   Writer.writeStrtab();
4747 
4748   Out.write((char *)&Buffer.front(), Buffer.size());
4749 }
4750 
4751 namespace {
4752 
4753 /// Class to manage the bitcode writing for a thin link bitcode file.
4754 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4755   /// ModHash is for use in ThinLTO incremental build, generated while writing
4756   /// the module bitcode file.
4757   const ModuleHash *ModHash;
4758 
4759 public:
4760   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4761                         BitstreamWriter &Stream,
4762                         const ModuleSummaryIndex &Index,
4763                         const ModuleHash &ModHash)
4764       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4765                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4766         ModHash(&ModHash) {}
4767 
4768   void write();
4769 
4770 private:
4771   void writeSimplifiedModuleInfo();
4772 };
4773 
4774 } // end anonymous namespace
4775 
4776 // This function writes a simpilified module info for thin link bitcode file.
4777 // It only contains the source file name along with the name(the offset and
4778 // size in strtab) and linkage for global values. For the global value info
4779 // entry, in order to keep linkage at offset 5, there are three zeros used
4780 // as padding.
4781 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4782   SmallVector<unsigned, 64> Vals;
4783   // Emit the module's source file name.
4784   {
4785     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4786     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4787     if (Bits == SE_Char6)
4788       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4789     else if (Bits == SE_Fixed7)
4790       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4791 
4792     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4793     auto Abbv = std::make_shared<BitCodeAbbrev>();
4794     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4795     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4796     Abbv->Add(AbbrevOpToUse);
4797     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4798 
4799     for (const auto P : M.getSourceFileName())
4800       Vals.push_back((unsigned char)P);
4801 
4802     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4803     Vals.clear();
4804   }
4805 
4806   // Emit the global variable information.
4807   for (const GlobalVariable &GV : M.globals()) {
4808     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4809     Vals.push_back(StrtabBuilder.add(GV.getName()));
4810     Vals.push_back(GV.getName().size());
4811     Vals.push_back(0);
4812     Vals.push_back(0);
4813     Vals.push_back(0);
4814     Vals.push_back(getEncodedLinkage(GV));
4815 
4816     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4817     Vals.clear();
4818   }
4819 
4820   // Emit the function proto information.
4821   for (const Function &F : M) {
4822     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4823     Vals.push_back(StrtabBuilder.add(F.getName()));
4824     Vals.push_back(F.getName().size());
4825     Vals.push_back(0);
4826     Vals.push_back(0);
4827     Vals.push_back(0);
4828     Vals.push_back(getEncodedLinkage(F));
4829 
4830     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4831     Vals.clear();
4832   }
4833 
4834   // Emit the alias information.
4835   for (const GlobalAlias &A : M.aliases()) {
4836     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4837     Vals.push_back(StrtabBuilder.add(A.getName()));
4838     Vals.push_back(A.getName().size());
4839     Vals.push_back(0);
4840     Vals.push_back(0);
4841     Vals.push_back(0);
4842     Vals.push_back(getEncodedLinkage(A));
4843 
4844     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4845     Vals.clear();
4846   }
4847 
4848   // Emit the ifunc information.
4849   for (const GlobalIFunc &I : M.ifuncs()) {
4850     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4851     Vals.push_back(StrtabBuilder.add(I.getName()));
4852     Vals.push_back(I.getName().size());
4853     Vals.push_back(0);
4854     Vals.push_back(0);
4855     Vals.push_back(0);
4856     Vals.push_back(getEncodedLinkage(I));
4857 
4858     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4859     Vals.clear();
4860   }
4861 }
4862 
4863 void ThinLinkBitcodeWriter::write() {
4864   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4865 
4866   writeModuleVersion();
4867 
4868   writeSimplifiedModuleInfo();
4869 
4870   writePerModuleGlobalValueSummary();
4871 
4872   // Write module hash.
4873   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4874 
4875   Stream.ExitBlock();
4876 }
4877 
4878 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4879                                          const ModuleSummaryIndex &Index,
4880                                          const ModuleHash &ModHash) {
4881   assert(!WroteStrtab);
4882 
4883   // The Mods vector is used by irsymtab::build, which requires non-const
4884   // Modules in case it needs to materialize metadata. But the bitcode writer
4885   // requires that the module is materialized, so we can cast to non-const here,
4886   // after checking that it is in fact materialized.
4887   assert(M.isMaterialized());
4888   Mods.push_back(const_cast<Module *>(&M));
4889 
4890   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4891                                        ModHash);
4892   ThinLinkWriter.write();
4893 }
4894 
4895 // Write the specified thin link bitcode file to the given raw output stream,
4896 // where it will be written in a new bitcode block. This is used when
4897 // writing the per-module index file for ThinLTO.
4898 void llvm::writeThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4899                                       const ModuleSummaryIndex &Index,
4900                                       const ModuleHash &ModHash) {
4901   SmallVector<char, 0> Buffer;
4902   Buffer.reserve(256 * 1024);
4903 
4904   BitcodeWriter Writer(Buffer);
4905   Writer.writeThinLinkBitcode(M, Index, ModHash);
4906   Writer.writeSymtab();
4907   Writer.writeStrtab();
4908 
4909   Out.write((char *)&Buffer.front(), Buffer.size());
4910 }
4911 
4912 static const char *getSectionNameForBitcode(const Triple &T) {
4913   switch (T.getObjectFormat()) {
4914   case Triple::MachO:
4915     return "__LLVM,__bitcode";
4916   case Triple::COFF:
4917   case Triple::ELF:
4918   case Triple::Wasm:
4919   case Triple::UnknownObjectFormat:
4920     return ".llvmbc";
4921   case Triple::GOFF:
4922     llvm_unreachable("GOFF is not yet implemented");
4923     break;
4924   case Triple::SPIRV:
4925     llvm_unreachable("SPIRV is not yet implemented");
4926     break;
4927   case Triple::XCOFF:
4928     llvm_unreachable("XCOFF is not yet implemented");
4929     break;
4930   case Triple::DXContainer:
4931     llvm_unreachable("DXContainer is not yet implemented");
4932     break;
4933   }
4934   llvm_unreachable("Unimplemented ObjectFormatType");
4935 }
4936 
4937 static const char *getSectionNameForCommandline(const Triple &T) {
4938   switch (T.getObjectFormat()) {
4939   case Triple::MachO:
4940     return "__LLVM,__cmdline";
4941   case Triple::COFF:
4942   case Triple::ELF:
4943   case Triple::Wasm:
4944   case Triple::UnknownObjectFormat:
4945     return ".llvmcmd";
4946   case Triple::GOFF:
4947     llvm_unreachable("GOFF is not yet implemented");
4948     break;
4949   case Triple::SPIRV:
4950     llvm_unreachable("SPIRV is not yet implemented");
4951     break;
4952   case Triple::XCOFF:
4953     llvm_unreachable("XCOFF is not yet implemented");
4954     break;
4955   case Triple::DXContainer:
4956     llvm_unreachable("DXC is not yet implemented");
4957     break;
4958   }
4959   llvm_unreachable("Unimplemented ObjectFormatType");
4960 }
4961 
4962 void llvm::embedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
4963                                 bool EmbedBitcode, bool EmbedCmdline,
4964                                 const std::vector<uint8_t> &CmdArgs) {
4965   // Save llvm.compiler.used and remove it.
4966   SmallVector<Constant *, 2> UsedArray;
4967   SmallVector<GlobalValue *, 4> UsedGlobals;
4968   Type *UsedElementType = Type::getInt8Ty(M.getContext())->getPointerTo(0);
4969   GlobalVariable *Used = collectUsedGlobalVariables(M, UsedGlobals, true);
4970   for (auto *GV : UsedGlobals) {
4971     if (GV->getName() != "llvm.embedded.module" &&
4972         GV->getName() != "llvm.cmdline")
4973       UsedArray.push_back(
4974           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4975   }
4976   if (Used)
4977     Used->eraseFromParent();
4978 
4979   // Embed the bitcode for the llvm module.
4980   std::string Data;
4981   ArrayRef<uint8_t> ModuleData;
4982   Triple T(M.getTargetTriple());
4983 
4984   if (EmbedBitcode) {
4985     if (Buf.getBufferSize() == 0 ||
4986         !isBitcode((const unsigned char *)Buf.getBufferStart(),
4987                    (const unsigned char *)Buf.getBufferEnd())) {
4988       // If the input is LLVM Assembly, bitcode is produced by serializing
4989       // the module. Use-lists order need to be preserved in this case.
4990       llvm::raw_string_ostream OS(Data);
4991       llvm::WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
4992       ModuleData =
4993           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
4994     } else
4995       // If the input is LLVM bitcode, write the input byte stream directly.
4996       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
4997                                      Buf.getBufferSize());
4998   }
4999   llvm::Constant *ModuleConstant =
5000       llvm::ConstantDataArray::get(M.getContext(), ModuleData);
5001   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
5002       M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
5003       ModuleConstant);
5004   GV->setSection(getSectionNameForBitcode(T));
5005   // Set alignment to 1 to prevent padding between two contributions from input
5006   // sections after linking.
5007   GV->setAlignment(Align(1));
5008   UsedArray.push_back(
5009       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
5010   if (llvm::GlobalVariable *Old =
5011           M.getGlobalVariable("llvm.embedded.module", true)) {
5012     assert(Old->hasZeroLiveUses() &&
5013            "llvm.embedded.module can only be used once in llvm.compiler.used");
5014     GV->takeName(Old);
5015     Old->eraseFromParent();
5016   } else {
5017     GV->setName("llvm.embedded.module");
5018   }
5019 
5020   // Skip if only bitcode needs to be embedded.
5021   if (EmbedCmdline) {
5022     // Embed command-line options.
5023     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CmdArgs.data()),
5024                               CmdArgs.size());
5025     llvm::Constant *CmdConstant =
5026         llvm::ConstantDataArray::get(M.getContext(), CmdData);
5027     GV = new llvm::GlobalVariable(M, CmdConstant->getType(), true,
5028                                   llvm::GlobalValue::PrivateLinkage,
5029                                   CmdConstant);
5030     GV->setSection(getSectionNameForCommandline(T));
5031     GV->setAlignment(Align(1));
5032     UsedArray.push_back(
5033         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
5034     if (llvm::GlobalVariable *Old = M.getGlobalVariable("llvm.cmdline", true)) {
5035       assert(Old->hasZeroLiveUses() &&
5036              "llvm.cmdline can only be used once in llvm.compiler.used");
5037       GV->takeName(Old);
5038       Old->eraseFromParent();
5039     } else {
5040       GV->setName("llvm.cmdline");
5041     }
5042   }
5043 
5044   if (UsedArray.empty())
5045     return;
5046 
5047   // Recreate llvm.compiler.used.
5048   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
5049   auto *NewUsed = new GlobalVariable(
5050       M, ATy, false, llvm::GlobalValue::AppendingLinkage,
5051       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
5052   NewUsed->setSection("llvm.metadata");
5053 }
5054