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