xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 8f65e7b917c580d1b58b024db6fc889cbcd964c7)
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/STLExtras.h"
20 #include "llvm/ADT/SetVector.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/StringMap.h"
25 #include "llvm/ADT/StringRef.h"
26 #include "llvm/Bitcode/BitcodeCommon.h"
27 #include "llvm/Bitcode/BitcodeReader.h"
28 #include "llvm/Bitcode/LLVMBitCodes.h"
29 #include "llvm/Bitstream/BitCodes.h"
30 #include "llvm/Bitstream/BitstreamWriter.h"
31 #include "llvm/Config/llvm-config.h"
32 #include "llvm/IR/Attributes.h"
33 #include "llvm/IR/BasicBlock.h"
34 #include "llvm/IR/Comdat.h"
35 #include "llvm/IR/Constant.h"
36 #include "llvm/IR/Constants.h"
37 #include "llvm/IR/DebugInfoMetadata.h"
38 #include "llvm/IR/DebugLoc.h"
39 #include "llvm/IR/DerivedTypes.h"
40 #include "llvm/IR/Function.h"
41 #include "llvm/IR/GlobalAlias.h"
42 #include "llvm/IR/GlobalIFunc.h"
43 #include "llvm/IR/GlobalObject.h"
44 #include "llvm/IR/GlobalValue.h"
45 #include "llvm/IR/GlobalVariable.h"
46 #include "llvm/IR/InlineAsm.h"
47 #include "llvm/IR/InstrTypes.h"
48 #include "llvm/IR/Instruction.h"
49 #include "llvm/IR/Instructions.h"
50 #include "llvm/IR/LLVMContext.h"
51 #include "llvm/IR/Metadata.h"
52 #include "llvm/IR/Module.h"
53 #include "llvm/IR/ModuleSummaryIndex.h"
54 #include "llvm/IR/Operator.h"
55 #include "llvm/IR/Type.h"
56 #include "llvm/IR/UseListOrder.h"
57 #include "llvm/IR/Value.h"
58 #include "llvm/IR/ValueSymbolTable.h"
59 #include "llvm/MC/StringTableBuilder.h"
60 #include "llvm/MC/TargetRegistry.h"
61 #include "llvm/Object/IRSymtab.h"
62 #include "llvm/Support/AtomicOrdering.h"
63 #include "llvm/Support/Casting.h"
64 #include "llvm/Support/CommandLine.h"
65 #include "llvm/Support/Endian.h"
66 #include "llvm/Support/Error.h"
67 #include "llvm/Support/ErrorHandling.h"
68 #include "llvm/Support/MathExtras.h"
69 #include "llvm/Support/SHA1.h"
70 #include "llvm/Support/raw_ostream.h"
71 #include "llvm/TargetParser/Triple.h"
72 #include <algorithm>
73 #include <cassert>
74 #include <cstddef>
75 #include <cstdint>
76 #include <iterator>
77 #include <map>
78 #include <memory>
79 #include <optional>
80 #include <string>
81 #include <utility>
82 #include <vector>
83 
84 using namespace llvm;
85 
86 static cl::opt<unsigned>
87     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
88                    cl::desc("Number of metadatas above which we emit an index "
89                             "to enable lazy-loading"));
90 static cl::opt<uint32_t> FlushThreshold(
91     "bitcode-flush-threshold", cl::Hidden, cl::init(512),
92     cl::desc("The threshold (unit M) for flushing LLVM bitcode."));
93 
94 static cl::opt<bool> WriteRelBFToSummary(
95     "write-relbf-to-summary", cl::Hidden, cl::init(false),
96     cl::desc("Write relative block frequency to function summary "));
97 
98 namespace llvm {
99 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
100 }
101 
102 namespace {
103 
104 /// These are manifest constants used by the bitcode writer. They do not need to
105 /// be kept in sync with the reader, but need to be consistent within this file.
106 enum {
107   // VALUE_SYMTAB_BLOCK abbrev id's.
108   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
109   VST_ENTRY_7_ABBREV,
110   VST_ENTRY_6_ABBREV,
111   VST_BBENTRY_6_ABBREV,
112 
113   // CONSTANTS_BLOCK abbrev id's.
114   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
115   CONSTANTS_INTEGER_ABBREV,
116   CONSTANTS_CE_CAST_Abbrev,
117   CONSTANTS_NULL_Abbrev,
118 
119   // FUNCTION_BLOCK abbrev id's.
120   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
121   FUNCTION_INST_UNOP_ABBREV,
122   FUNCTION_INST_UNOP_FLAGS_ABBREV,
123   FUNCTION_INST_BINOP_ABBREV,
124   FUNCTION_INST_BINOP_FLAGS_ABBREV,
125   FUNCTION_INST_CAST_ABBREV,
126   FUNCTION_INST_CAST_FLAGS_ABBREV,
127   FUNCTION_INST_RET_VOID_ABBREV,
128   FUNCTION_INST_RET_VAL_ABBREV,
129   FUNCTION_INST_UNREACHABLE_ABBREV,
130   FUNCTION_INST_GEP_ABBREV,
131 };
132 
133 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
134 /// file type.
135 class BitcodeWriterBase {
136 protected:
137   /// The stream created and owned by the client.
138   BitstreamWriter &Stream;
139 
140   StringTableBuilder &StrtabBuilder;
141 
142 public:
143   /// Constructs a BitcodeWriterBase object that writes to the provided
144   /// \p Stream.
145   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
146       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
147 
148 protected:
149   void writeModuleVersion();
150 };
151 
152 void BitcodeWriterBase::writeModuleVersion() {
153   // VERSION: [version#]
154   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
155 }
156 
157 /// Base class to manage the module bitcode writing, currently subclassed for
158 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
159 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
160 protected:
161   /// The Module to write to bitcode.
162   const Module &M;
163 
164   /// Enumerates ids for all values in the module.
165   ValueEnumerator VE;
166 
167   /// Optional per-module index to write for ThinLTO.
168   const ModuleSummaryIndex *Index;
169 
170   /// Map that holds the correspondence between GUIDs in the summary index,
171   /// that came from indirect call profiles, and a value id generated by this
172   /// class to use in the VST and summary block records.
173   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
174 
175   /// Tracks the last value id recorded in the GUIDToValueMap.
176   unsigned GlobalValueId;
177 
178   /// Saves the offset of the VSTOffset record that must eventually be
179   /// backpatched with the offset of the actual VST.
180   uint64_t VSTOffsetPlaceholder = 0;
181 
182 public:
183   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
184   /// writing to the provided \p Buffer.
185   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
186                           BitstreamWriter &Stream,
187                           bool ShouldPreserveUseListOrder,
188                           const ModuleSummaryIndex *Index)
189       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
190         VE(M, ShouldPreserveUseListOrder), Index(Index) {
191     // Assign ValueIds to any callee values in the index that came from
192     // indirect call profiles and were recorded as a GUID not a Value*
193     // (which would have been assigned an ID by the ValueEnumerator).
194     // The starting ValueId is just after the number of values in the
195     // ValueEnumerator, so that they can be emitted in the VST.
196     GlobalValueId = VE.getValues().size();
197     if (!Index)
198       return;
199     for (const auto &GUIDSummaryLists : *Index)
200       // Examine all summaries for this GUID.
201       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
202         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
203           // For each call in the function summary, see if the call
204           // is to a GUID (which means it is for an indirect call,
205           // otherwise we would have a Value for it). If so, synthesize
206           // a value id.
207           for (auto &CallEdge : FS->calls())
208             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
209               assignValueId(CallEdge.first.getGUID());
210   }
211 
212 protected:
213   void writePerModuleGlobalValueSummary();
214 
215 private:
216   void writePerModuleFunctionSummaryRecord(
217       SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
218       unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
219       unsigned CallsiteAbbrev, unsigned AllocAbbrev, 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   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
341                      unsigned Abbrev);
342   void writeDIAssignID(const DIAssignID *N, SmallVectorImpl<uint64_t> &Record,
343                        unsigned Abbrev);
344   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
345                                     SmallVectorImpl<uint64_t> &Record,
346                                     unsigned Abbrev);
347   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
348                                      SmallVectorImpl<uint64_t> &Record,
349                                      unsigned Abbrev);
350   void writeDIGlobalVariable(const DIGlobalVariable *N,
351                              SmallVectorImpl<uint64_t> &Record,
352                              unsigned Abbrev);
353   void writeDILocalVariable(const DILocalVariable *N,
354                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
355   void writeDILabel(const DILabel *N,
356                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
357   void writeDIExpression(const DIExpression *N,
358                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
359   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
360                                        SmallVectorImpl<uint64_t> &Record,
361                                        unsigned Abbrev);
362   void writeDIObjCProperty(const DIObjCProperty *N,
363                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
364   void writeDIImportedEntity(const DIImportedEntity *N,
365                              SmallVectorImpl<uint64_t> &Record,
366                              unsigned Abbrev);
367   unsigned createNamedMetadataAbbrev();
368   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
369   unsigned createMetadataStringsAbbrev();
370   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
371                             SmallVectorImpl<uint64_t> &Record);
372   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
373                             SmallVectorImpl<uint64_t> &Record,
374                             std::vector<unsigned> *MDAbbrevs = nullptr,
375                             std::vector<uint64_t> *IndexPos = nullptr);
376   void writeModuleMetadata();
377   void writeFunctionMetadata(const Function &F);
378   void writeFunctionMetadataAttachment(const Function &F);
379   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
380                                     const GlobalObject &GO);
381   void writeModuleMetadataKinds();
382   void writeOperandBundleTags();
383   void writeSyncScopeNames();
384   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
385   void writeModuleConstants();
386   bool pushValueAndType(const Value *V, unsigned InstID,
387                         SmallVectorImpl<unsigned> &Vals);
388   void writeOperandBundles(const CallBase &CB, unsigned InstID);
389   void pushValue(const Value *V, unsigned InstID,
390                  SmallVectorImpl<unsigned> &Vals);
391   void pushValueSigned(const Value *V, unsigned InstID,
392                        SmallVectorImpl<uint64_t> &Vals);
393   void writeInstruction(const Instruction &I, unsigned InstID,
394                         SmallVectorImpl<unsigned> &Vals);
395   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
396   void writeGlobalValueSymbolTable(
397       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
398   void writeUseList(UseListOrder &&Order);
399   void writeUseListBlock(const Function *F);
400   void
401   writeFunction(const Function &F,
402                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
403   void writeBlockInfo();
404   void writeModuleHash(size_t BlockStartPos);
405 
406   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
407     return unsigned(SSID);
408   }
409 
410   unsigned getEncodedAlign(MaybeAlign Alignment) { return encode(Alignment); }
411 };
412 
413 /// Class to manage the bitcode writing for a combined index.
414 class IndexBitcodeWriter : public BitcodeWriterBase {
415   /// The combined index to write to bitcode.
416   const ModuleSummaryIndex &Index;
417 
418   /// When writing a subset of the index for distributed backends, client
419   /// provides a map of modules to the corresponding GUIDs/summaries to write.
420   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
421 
422   /// Map that holds the correspondence between the GUID used in the combined
423   /// index and a value id generated by this class to use in references.
424   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
425 
426   // The sorted stack id indices actually used in the summary entries being
427   // written, which will be a subset of those in the full index in the case of
428   // distributed indexes.
429   std::vector<unsigned> StackIdIndices;
430 
431   /// Tracks the last value id recorded in the GUIDToValueMap.
432   unsigned GlobalValueId = 0;
433 
434   /// Tracks the assignment of module paths in the module path string table to
435   /// an id assigned for use in summary references to the module path.
436   DenseMap<StringRef, uint64_t> ModuleIdMap;
437 
438 public:
439   /// Constructs a IndexBitcodeWriter object for the given combined index,
440   /// writing to the provided \p Buffer. When writing a subset of the index
441   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
442   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
443                      const ModuleSummaryIndex &Index,
444                      const std::map<std::string, GVSummaryMapTy>
445                          *ModuleToSummariesForIndex = nullptr)
446       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
447         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
448     // Assign unique value ids to all summaries to be written, for use
449     // in writing out the call graph edges. Save the mapping from GUID
450     // to the new global value id to use when writing those edges, which
451     // are currently saved in the index in terms of GUID.
452     forEachSummary([&](GVInfo I, bool IsAliasee) {
453       GUIDToValueIdMap[I.first] = ++GlobalValueId;
454       if (IsAliasee)
455         return;
456       auto *FS = dyn_cast<FunctionSummary>(I.second);
457       if (!FS)
458         return;
459       // Record all stack id indices actually used in the summary entries being
460       // written, so that we can compact them in the case of distributed ThinLTO
461       // indexes.
462       for (auto &CI : FS->callsites()) {
463         // If the stack id list is empty, this callsite info was synthesized for
464         // a missing tail call frame. Ensure that the callee's GUID gets a value
465         // id. Normally we only generate these for defined summaries, which in
466         // the case of distributed ThinLTO is only the functions already defined
467         // in the module or that we want to import. We don't bother to include
468         // all the callee symbols as they aren't normally needed in the backend.
469         // However, for the synthesized callsite infos we do need the callee
470         // GUID in the backend so that we can correlate the identified callee
471         // with this callsite info (which for non-tail calls is done by the
472         // ordering of the callsite infos and verified via stack ids).
473         if (CI.StackIdIndices.empty()) {
474           GUIDToValueIdMap[CI.Callee.getGUID()] = ++GlobalValueId;
475           continue;
476         }
477         for (auto Idx : CI.StackIdIndices)
478           StackIdIndices.push_back(Idx);
479       }
480       for (auto &AI : FS->allocs())
481         for (auto &MIB : AI.MIBs)
482           for (auto Idx : MIB.StackIdIndices)
483             StackIdIndices.push_back(Idx);
484     });
485     llvm::sort(StackIdIndices);
486     StackIdIndices.erase(
487         std::unique(StackIdIndices.begin(), StackIdIndices.end()),
488         StackIdIndices.end());
489   }
490 
491   /// The below iterator returns the GUID and associated summary.
492   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
493 
494   /// Calls the callback for each value GUID and summary to be written to
495   /// bitcode. This hides the details of whether they are being pulled from the
496   /// entire index or just those in a provided ModuleToSummariesForIndex map.
497   template<typename Functor>
498   void forEachSummary(Functor Callback) {
499     if (ModuleToSummariesForIndex) {
500       for (auto &M : *ModuleToSummariesForIndex)
501         for (auto &Summary : M.second) {
502           Callback(Summary, false);
503           // Ensure aliasee is handled, e.g. for assigning a valueId,
504           // even if we are not importing the aliasee directly (the
505           // imported alias will contain a copy of aliasee).
506           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
507             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
508         }
509     } else {
510       for (auto &Summaries : Index)
511         for (auto &Summary : Summaries.second.SummaryList)
512           Callback({Summaries.first, Summary.get()}, false);
513     }
514   }
515 
516   /// Calls the callback for each entry in the modulePaths StringMap that
517   /// should be written to the module path string table. This hides the details
518   /// of whether they are being pulled from the entire index or just those in a
519   /// provided ModuleToSummariesForIndex map.
520   template <typename Functor> void forEachModule(Functor Callback) {
521     if (ModuleToSummariesForIndex) {
522       for (const auto &M : *ModuleToSummariesForIndex) {
523         const auto &MPI = Index.modulePaths().find(M.first);
524         if (MPI == Index.modulePaths().end()) {
525           // This should only happen if the bitcode file was empty, in which
526           // case we shouldn't be importing (the ModuleToSummariesForIndex
527           // would only include the module we are writing and index for).
528           assert(ModuleToSummariesForIndex->size() == 1);
529           continue;
530         }
531         Callback(*MPI);
532       }
533     } else {
534       // Since StringMap iteration order isn't guaranteed, order by path string
535       // first.
536       // FIXME: Make this a vector of StringMapEntry instead to avoid the later
537       // map lookup.
538       std::vector<StringRef> ModulePaths;
539       for (auto &[ModPath, _] : Index.modulePaths())
540         ModulePaths.push_back(ModPath);
541       llvm::sort(ModulePaths.begin(), ModulePaths.end());
542       for (auto &ModPath : ModulePaths)
543         Callback(*Index.modulePaths().find(ModPath));
544     }
545   }
546 
547   /// Main entry point for writing a combined index to bitcode.
548   void write();
549 
550 private:
551   void writeModStrings();
552   void writeCombinedGlobalValueSummary();
553 
554   std::optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
555     auto VMI = GUIDToValueIdMap.find(ValGUID);
556     if (VMI == GUIDToValueIdMap.end())
557       return std::nullopt;
558     return VMI->second;
559   }
560 
561   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
562 };
563 
564 } // end anonymous namespace
565 
566 static unsigned getEncodedCastOpcode(unsigned Opcode) {
567   switch (Opcode) {
568   default: llvm_unreachable("Unknown cast instruction!");
569   case Instruction::Trunc   : return bitc::CAST_TRUNC;
570   case Instruction::ZExt    : return bitc::CAST_ZEXT;
571   case Instruction::SExt    : return bitc::CAST_SEXT;
572   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
573   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
574   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
575   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
576   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
577   case Instruction::FPExt   : return bitc::CAST_FPEXT;
578   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
579   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
580   case Instruction::BitCast : return bitc::CAST_BITCAST;
581   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
582   }
583 }
584 
585 static unsigned getEncodedUnaryOpcode(unsigned Opcode) {
586   switch (Opcode) {
587   default: llvm_unreachable("Unknown binary instruction!");
588   case Instruction::FNeg: return bitc::UNOP_FNEG;
589   }
590 }
591 
592 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
593   switch (Opcode) {
594   default: llvm_unreachable("Unknown binary instruction!");
595   case Instruction::Add:
596   case Instruction::FAdd: return bitc::BINOP_ADD;
597   case Instruction::Sub:
598   case Instruction::FSub: return bitc::BINOP_SUB;
599   case Instruction::Mul:
600   case Instruction::FMul: return bitc::BINOP_MUL;
601   case Instruction::UDiv: return bitc::BINOP_UDIV;
602   case Instruction::FDiv:
603   case Instruction::SDiv: return bitc::BINOP_SDIV;
604   case Instruction::URem: return bitc::BINOP_UREM;
605   case Instruction::FRem:
606   case Instruction::SRem: return bitc::BINOP_SREM;
607   case Instruction::Shl:  return bitc::BINOP_SHL;
608   case Instruction::LShr: return bitc::BINOP_LSHR;
609   case Instruction::AShr: return bitc::BINOP_ASHR;
610   case Instruction::And:  return bitc::BINOP_AND;
611   case Instruction::Or:   return bitc::BINOP_OR;
612   case Instruction::Xor:  return bitc::BINOP_XOR;
613   }
614 }
615 
616 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
617   switch (Op) {
618   default: llvm_unreachable("Unknown RMW operation!");
619   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
620   case AtomicRMWInst::Add: return bitc::RMW_ADD;
621   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
622   case AtomicRMWInst::And: return bitc::RMW_AND;
623   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
624   case AtomicRMWInst::Or: return bitc::RMW_OR;
625   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
626   case AtomicRMWInst::Max: return bitc::RMW_MAX;
627   case AtomicRMWInst::Min: return bitc::RMW_MIN;
628   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
629   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
630   case AtomicRMWInst::FAdd: return bitc::RMW_FADD;
631   case AtomicRMWInst::FSub: return bitc::RMW_FSUB;
632   case AtomicRMWInst::FMax: return bitc::RMW_FMAX;
633   case AtomicRMWInst::FMin: return bitc::RMW_FMIN;
634   case AtomicRMWInst::UIncWrap:
635     return bitc::RMW_UINC_WRAP;
636   case AtomicRMWInst::UDecWrap:
637     return bitc::RMW_UDEC_WRAP;
638   }
639 }
640 
641 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
642   switch (Ordering) {
643   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
644   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
645   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
646   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
647   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
648   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
649   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
650   }
651   llvm_unreachable("Invalid ordering");
652 }
653 
654 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
655                               StringRef Str, unsigned AbbrevToUse) {
656   SmallVector<unsigned, 64> Vals;
657 
658   // Code: [strchar x N]
659   for (char C : Str) {
660     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(C))
661       AbbrevToUse = 0;
662     Vals.push_back(C);
663   }
664 
665   // Emit the finished record.
666   Stream.EmitRecord(Code, Vals, AbbrevToUse);
667 }
668 
669 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
670   switch (Kind) {
671   case Attribute::Alignment:
672     return bitc::ATTR_KIND_ALIGNMENT;
673   case Attribute::AllocAlign:
674     return bitc::ATTR_KIND_ALLOC_ALIGN;
675   case Attribute::AllocSize:
676     return bitc::ATTR_KIND_ALLOC_SIZE;
677   case Attribute::AlwaysInline:
678     return bitc::ATTR_KIND_ALWAYS_INLINE;
679   case Attribute::Builtin:
680     return bitc::ATTR_KIND_BUILTIN;
681   case Attribute::ByVal:
682     return bitc::ATTR_KIND_BY_VAL;
683   case Attribute::Convergent:
684     return bitc::ATTR_KIND_CONVERGENT;
685   case Attribute::InAlloca:
686     return bitc::ATTR_KIND_IN_ALLOCA;
687   case Attribute::Cold:
688     return bitc::ATTR_KIND_COLD;
689   case Attribute::DisableSanitizerInstrumentation:
690     return bitc::ATTR_KIND_DISABLE_SANITIZER_INSTRUMENTATION;
691   case Attribute::FnRetThunkExtern:
692     return bitc::ATTR_KIND_FNRETTHUNK_EXTERN;
693   case Attribute::Hot:
694     return bitc::ATTR_KIND_HOT;
695   case Attribute::ElementType:
696     return bitc::ATTR_KIND_ELEMENTTYPE;
697   case Attribute::InlineHint:
698     return bitc::ATTR_KIND_INLINE_HINT;
699   case Attribute::InReg:
700     return bitc::ATTR_KIND_IN_REG;
701   case Attribute::JumpTable:
702     return bitc::ATTR_KIND_JUMP_TABLE;
703   case Attribute::MinSize:
704     return bitc::ATTR_KIND_MIN_SIZE;
705   case Attribute::AllocatedPointer:
706     return bitc::ATTR_KIND_ALLOCATED_POINTER;
707   case Attribute::AllocKind:
708     return bitc::ATTR_KIND_ALLOC_KIND;
709   case Attribute::Memory:
710     return bitc::ATTR_KIND_MEMORY;
711   case Attribute::NoFPClass:
712     return bitc::ATTR_KIND_NOFPCLASS;
713   case Attribute::Naked:
714     return bitc::ATTR_KIND_NAKED;
715   case Attribute::Nest:
716     return bitc::ATTR_KIND_NEST;
717   case Attribute::NoAlias:
718     return bitc::ATTR_KIND_NO_ALIAS;
719   case Attribute::NoBuiltin:
720     return bitc::ATTR_KIND_NO_BUILTIN;
721   case Attribute::NoCallback:
722     return bitc::ATTR_KIND_NO_CALLBACK;
723   case Attribute::NoCapture:
724     return bitc::ATTR_KIND_NO_CAPTURE;
725   case Attribute::NoDuplicate:
726     return bitc::ATTR_KIND_NO_DUPLICATE;
727   case Attribute::NoFree:
728     return bitc::ATTR_KIND_NOFREE;
729   case Attribute::NoImplicitFloat:
730     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
731   case Attribute::NoInline:
732     return bitc::ATTR_KIND_NO_INLINE;
733   case Attribute::NoRecurse:
734     return bitc::ATTR_KIND_NO_RECURSE;
735   case Attribute::NoMerge:
736     return bitc::ATTR_KIND_NO_MERGE;
737   case Attribute::NonLazyBind:
738     return bitc::ATTR_KIND_NON_LAZY_BIND;
739   case Attribute::NonNull:
740     return bitc::ATTR_KIND_NON_NULL;
741   case Attribute::Dereferenceable:
742     return bitc::ATTR_KIND_DEREFERENCEABLE;
743   case Attribute::DereferenceableOrNull:
744     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
745   case Attribute::NoRedZone:
746     return bitc::ATTR_KIND_NO_RED_ZONE;
747   case Attribute::NoReturn:
748     return bitc::ATTR_KIND_NO_RETURN;
749   case Attribute::NoSync:
750     return bitc::ATTR_KIND_NOSYNC;
751   case Attribute::NoCfCheck:
752     return bitc::ATTR_KIND_NOCF_CHECK;
753   case Attribute::NoProfile:
754     return bitc::ATTR_KIND_NO_PROFILE;
755   case Attribute::SkipProfile:
756     return bitc::ATTR_KIND_SKIP_PROFILE;
757   case Attribute::NoUnwind:
758     return bitc::ATTR_KIND_NO_UNWIND;
759   case Attribute::NoSanitizeBounds:
760     return bitc::ATTR_KIND_NO_SANITIZE_BOUNDS;
761   case Attribute::NoSanitizeCoverage:
762     return bitc::ATTR_KIND_NO_SANITIZE_COVERAGE;
763   case Attribute::NullPointerIsValid:
764     return bitc::ATTR_KIND_NULL_POINTER_IS_VALID;
765   case Attribute::OptimizeForDebugging:
766     return bitc::ATTR_KIND_OPTIMIZE_FOR_DEBUGGING;
767   case Attribute::OptForFuzzing:
768     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
769   case Attribute::OptimizeForSize:
770     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
771   case Attribute::OptimizeNone:
772     return bitc::ATTR_KIND_OPTIMIZE_NONE;
773   case Attribute::ReadNone:
774     return bitc::ATTR_KIND_READ_NONE;
775   case Attribute::ReadOnly:
776     return bitc::ATTR_KIND_READ_ONLY;
777   case Attribute::Returned:
778     return bitc::ATTR_KIND_RETURNED;
779   case Attribute::ReturnsTwice:
780     return bitc::ATTR_KIND_RETURNS_TWICE;
781   case Attribute::SExt:
782     return bitc::ATTR_KIND_S_EXT;
783   case Attribute::Speculatable:
784     return bitc::ATTR_KIND_SPECULATABLE;
785   case Attribute::StackAlignment:
786     return bitc::ATTR_KIND_STACK_ALIGNMENT;
787   case Attribute::StackProtect:
788     return bitc::ATTR_KIND_STACK_PROTECT;
789   case Attribute::StackProtectReq:
790     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
791   case Attribute::StackProtectStrong:
792     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
793   case Attribute::SafeStack:
794     return bitc::ATTR_KIND_SAFESTACK;
795   case Attribute::ShadowCallStack:
796     return bitc::ATTR_KIND_SHADOWCALLSTACK;
797   case Attribute::StrictFP:
798     return bitc::ATTR_KIND_STRICT_FP;
799   case Attribute::StructRet:
800     return bitc::ATTR_KIND_STRUCT_RET;
801   case Attribute::SanitizeAddress:
802     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
803   case Attribute::SanitizeHWAddress:
804     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
805   case Attribute::SanitizeThread:
806     return bitc::ATTR_KIND_SANITIZE_THREAD;
807   case Attribute::SanitizeMemory:
808     return bitc::ATTR_KIND_SANITIZE_MEMORY;
809   case Attribute::SpeculativeLoadHardening:
810     return bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING;
811   case Attribute::SwiftError:
812     return bitc::ATTR_KIND_SWIFT_ERROR;
813   case Attribute::SwiftSelf:
814     return bitc::ATTR_KIND_SWIFT_SELF;
815   case Attribute::SwiftAsync:
816     return bitc::ATTR_KIND_SWIFT_ASYNC;
817   case Attribute::UWTable:
818     return bitc::ATTR_KIND_UW_TABLE;
819   case Attribute::VScaleRange:
820     return bitc::ATTR_KIND_VSCALE_RANGE;
821   case Attribute::WillReturn:
822     return bitc::ATTR_KIND_WILLRETURN;
823   case Attribute::WriteOnly:
824     return bitc::ATTR_KIND_WRITEONLY;
825   case Attribute::ZExt:
826     return bitc::ATTR_KIND_Z_EXT;
827   case Attribute::ImmArg:
828     return bitc::ATTR_KIND_IMMARG;
829   case Attribute::SanitizeMemTag:
830     return bitc::ATTR_KIND_SANITIZE_MEMTAG;
831   case Attribute::Preallocated:
832     return bitc::ATTR_KIND_PREALLOCATED;
833   case Attribute::NoUndef:
834     return bitc::ATTR_KIND_NOUNDEF;
835   case Attribute::ByRef:
836     return bitc::ATTR_KIND_BYREF;
837   case Attribute::MustProgress:
838     return bitc::ATTR_KIND_MUSTPROGRESS;
839   case Attribute::PresplitCoroutine:
840     return bitc::ATTR_KIND_PRESPLIT_COROUTINE;
841   case Attribute::Writable:
842     return bitc::ATTR_KIND_WRITABLE;
843   case Attribute::CoroDestroyOnlyWhenComplete:
844     return bitc::ATTR_KIND_CORO_ONLY_DESTROY_WHEN_COMPLETE;
845   case Attribute::DeadOnUnwind:
846     return bitc::ATTR_KIND_DEAD_ON_UNWIND;
847   case Attribute::EndAttrKinds:
848     llvm_unreachable("Can not encode end-attribute kinds marker.");
849   case Attribute::None:
850     llvm_unreachable("Can not encode none-attribute.");
851   case Attribute::EmptyKey:
852   case Attribute::TombstoneKey:
853     llvm_unreachable("Trying to encode EmptyKey/TombstoneKey");
854   }
855 
856   llvm_unreachable("Trying to encode unknown attribute");
857 }
858 
859 void ModuleBitcodeWriter::writeAttributeGroupTable() {
860   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
861       VE.getAttributeGroups();
862   if (AttrGrps.empty()) return;
863 
864   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
865 
866   SmallVector<uint64_t, 64> Record;
867   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
868     unsigned AttrListIndex = Pair.first;
869     AttributeSet AS = Pair.second;
870     Record.push_back(VE.getAttributeGroupID(Pair));
871     Record.push_back(AttrListIndex);
872 
873     for (Attribute Attr : AS) {
874       if (Attr.isEnumAttribute()) {
875         Record.push_back(0);
876         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
877       } else if (Attr.isIntAttribute()) {
878         Record.push_back(1);
879         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
880         Record.push_back(Attr.getValueAsInt());
881       } else if (Attr.isStringAttribute()) {
882         StringRef Kind = Attr.getKindAsString();
883         StringRef Val = Attr.getValueAsString();
884 
885         Record.push_back(Val.empty() ? 3 : 4);
886         Record.append(Kind.begin(), Kind.end());
887         Record.push_back(0);
888         if (!Val.empty()) {
889           Record.append(Val.begin(), Val.end());
890           Record.push_back(0);
891         }
892       } else {
893         assert(Attr.isTypeAttribute());
894         Type *Ty = Attr.getValueAsType();
895         Record.push_back(Ty ? 6 : 5);
896         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
897         if (Ty)
898           Record.push_back(VE.getTypeID(Attr.getValueAsType()));
899       }
900     }
901 
902     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
903     Record.clear();
904   }
905 
906   Stream.ExitBlock();
907 }
908 
909 void ModuleBitcodeWriter::writeAttributeTable() {
910   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
911   if (Attrs.empty()) return;
912 
913   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
914 
915   SmallVector<uint64_t, 64> Record;
916   for (const AttributeList &AL : Attrs) {
917     for (unsigned i : AL.indexes()) {
918       AttributeSet AS = AL.getAttributes(i);
919       if (AS.hasAttributes())
920         Record.push_back(VE.getAttributeGroupID({i, AS}));
921     }
922 
923     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
924     Record.clear();
925   }
926 
927   Stream.ExitBlock();
928 }
929 
930 /// WriteTypeTable - Write out the type table for a module.
931 void ModuleBitcodeWriter::writeTypeTable() {
932   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
933 
934   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
935   SmallVector<uint64_t, 64> TypeVals;
936 
937   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
938 
939   // Abbrev for TYPE_CODE_OPAQUE_POINTER.
940   auto Abbv = std::make_shared<BitCodeAbbrev>();
941   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_OPAQUE_POINTER));
942   Abbv->Add(BitCodeAbbrevOp(0)); // Addrspace = 0
943   unsigned OpaquePtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
944 
945   // Abbrev for TYPE_CODE_FUNCTION.
946   Abbv = std::make_shared<BitCodeAbbrev>();
947   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
948   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
949   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
950   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
951   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
952 
953   // Abbrev for TYPE_CODE_STRUCT_ANON.
954   Abbv = std::make_shared<BitCodeAbbrev>();
955   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
956   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
957   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
958   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
959   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
960 
961   // Abbrev for TYPE_CODE_STRUCT_NAME.
962   Abbv = std::make_shared<BitCodeAbbrev>();
963   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
964   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
965   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
966   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
967 
968   // Abbrev for TYPE_CODE_STRUCT_NAMED.
969   Abbv = std::make_shared<BitCodeAbbrev>();
970   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
971   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
972   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
973   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
974   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
975 
976   // Abbrev for TYPE_CODE_ARRAY.
977   Abbv = std::make_shared<BitCodeAbbrev>();
978   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
979   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
980   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
981   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
982 
983   // Emit an entry count so the reader can reserve space.
984   TypeVals.push_back(TypeList.size());
985   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
986   TypeVals.clear();
987 
988   // Loop over all of the types, emitting each in turn.
989   for (Type *T : TypeList) {
990     int AbbrevToUse = 0;
991     unsigned Code = 0;
992 
993     switch (T->getTypeID()) {
994     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
995     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
996     case Type::BFloatTyID:    Code = bitc::TYPE_CODE_BFLOAT;    break;
997     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
998     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
999     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
1000     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
1001     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
1002     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
1003     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
1004     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
1005     case Type::X86_AMXTyID:   Code = bitc::TYPE_CODE_X86_AMX;   break;
1006     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
1007     case Type::IntegerTyID:
1008       // INTEGER: [width]
1009       Code = bitc::TYPE_CODE_INTEGER;
1010       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
1011       break;
1012     case Type::PointerTyID: {
1013       PointerType *PTy = cast<PointerType>(T);
1014       unsigned AddressSpace = PTy->getAddressSpace();
1015       // OPAQUE_POINTER: [address space]
1016       Code = bitc::TYPE_CODE_OPAQUE_POINTER;
1017       TypeVals.push_back(AddressSpace);
1018       if (AddressSpace == 0)
1019         AbbrevToUse = OpaquePtrAbbrev;
1020       break;
1021     }
1022     case Type::FunctionTyID: {
1023       FunctionType *FT = cast<FunctionType>(T);
1024       // FUNCTION: [isvararg, retty, paramty x N]
1025       Code = bitc::TYPE_CODE_FUNCTION;
1026       TypeVals.push_back(FT->isVarArg());
1027       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
1028       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
1029         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
1030       AbbrevToUse = FunctionAbbrev;
1031       break;
1032     }
1033     case Type::StructTyID: {
1034       StructType *ST = cast<StructType>(T);
1035       // STRUCT: [ispacked, eltty x N]
1036       TypeVals.push_back(ST->isPacked());
1037       // Output all of the element types.
1038       for (Type *ET : ST->elements())
1039         TypeVals.push_back(VE.getTypeID(ET));
1040 
1041       if (ST->isLiteral()) {
1042         Code = bitc::TYPE_CODE_STRUCT_ANON;
1043         AbbrevToUse = StructAnonAbbrev;
1044       } else {
1045         if (ST->isOpaque()) {
1046           Code = bitc::TYPE_CODE_OPAQUE;
1047         } else {
1048           Code = bitc::TYPE_CODE_STRUCT_NAMED;
1049           AbbrevToUse = StructNamedAbbrev;
1050         }
1051 
1052         // Emit the name if it is present.
1053         if (!ST->getName().empty())
1054           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
1055                             StructNameAbbrev);
1056       }
1057       break;
1058     }
1059     case Type::ArrayTyID: {
1060       ArrayType *AT = cast<ArrayType>(T);
1061       // ARRAY: [numelts, eltty]
1062       Code = bitc::TYPE_CODE_ARRAY;
1063       TypeVals.push_back(AT->getNumElements());
1064       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
1065       AbbrevToUse = ArrayAbbrev;
1066       break;
1067     }
1068     case Type::FixedVectorTyID:
1069     case Type::ScalableVectorTyID: {
1070       VectorType *VT = cast<VectorType>(T);
1071       // VECTOR [numelts, eltty] or
1072       //        [numelts, eltty, scalable]
1073       Code = bitc::TYPE_CODE_VECTOR;
1074       TypeVals.push_back(VT->getElementCount().getKnownMinValue());
1075       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
1076       if (isa<ScalableVectorType>(VT))
1077         TypeVals.push_back(true);
1078       break;
1079     }
1080     case Type::TargetExtTyID: {
1081       TargetExtType *TET = cast<TargetExtType>(T);
1082       Code = bitc::TYPE_CODE_TARGET_TYPE;
1083       writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, TET->getName(),
1084                         StructNameAbbrev);
1085       TypeVals.push_back(TET->getNumTypeParameters());
1086       for (Type *InnerTy : TET->type_params())
1087         TypeVals.push_back(VE.getTypeID(InnerTy));
1088       for (unsigned IntParam : TET->int_params())
1089         TypeVals.push_back(IntParam);
1090       break;
1091     }
1092     case Type::TypedPointerTyID:
1093       llvm_unreachable("Typed pointers cannot be added to IR modules");
1094     }
1095 
1096     // Emit the finished record.
1097     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
1098     TypeVals.clear();
1099   }
1100 
1101   Stream.ExitBlock();
1102 }
1103 
1104 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
1105   switch (Linkage) {
1106   case GlobalValue::ExternalLinkage:
1107     return 0;
1108   case GlobalValue::WeakAnyLinkage:
1109     return 16;
1110   case GlobalValue::AppendingLinkage:
1111     return 2;
1112   case GlobalValue::InternalLinkage:
1113     return 3;
1114   case GlobalValue::LinkOnceAnyLinkage:
1115     return 18;
1116   case GlobalValue::ExternalWeakLinkage:
1117     return 7;
1118   case GlobalValue::CommonLinkage:
1119     return 8;
1120   case GlobalValue::PrivateLinkage:
1121     return 9;
1122   case GlobalValue::WeakODRLinkage:
1123     return 17;
1124   case GlobalValue::LinkOnceODRLinkage:
1125     return 19;
1126   case GlobalValue::AvailableExternallyLinkage:
1127     return 12;
1128   }
1129   llvm_unreachable("Invalid linkage");
1130 }
1131 
1132 static unsigned getEncodedLinkage(const GlobalValue &GV) {
1133   return getEncodedLinkage(GV.getLinkage());
1134 }
1135 
1136 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
1137   uint64_t RawFlags = 0;
1138   RawFlags |= Flags.ReadNone;
1139   RawFlags |= (Flags.ReadOnly << 1);
1140   RawFlags |= (Flags.NoRecurse << 2);
1141   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
1142   RawFlags |= (Flags.NoInline << 4);
1143   RawFlags |= (Flags.AlwaysInline << 5);
1144   RawFlags |= (Flags.NoUnwind << 6);
1145   RawFlags |= (Flags.MayThrow << 7);
1146   RawFlags |= (Flags.HasUnknownCall << 8);
1147   RawFlags |= (Flags.MustBeUnreachable << 9);
1148   return RawFlags;
1149 }
1150 
1151 // Decode the flags for GlobalValue in the summary. See getDecodedGVSummaryFlags
1152 // in BitcodeReader.cpp.
1153 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
1154   uint64_t RawFlags = 0;
1155 
1156   RawFlags |= Flags.NotEligibleToImport; // bool
1157   RawFlags |= (Flags.Live << 1);
1158   RawFlags |= (Flags.DSOLocal << 2);
1159   RawFlags |= (Flags.CanAutoHide << 3);
1160 
1161   // Linkage don't need to be remapped at that time for the summary. Any future
1162   // change to the getEncodedLinkage() function will need to be taken into
1163   // account here as well.
1164   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
1165 
1166   RawFlags |= (Flags.Visibility << 8); // 2 bits
1167 
1168   return RawFlags;
1169 }
1170 
1171 static uint64_t getEncodedGVarFlags(GlobalVarSummary::GVarFlags Flags) {
1172   uint64_t RawFlags = Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) |
1173                       (Flags.Constant << 2) | Flags.VCallVisibility << 3;
1174   return RawFlags;
1175 }
1176 
1177 static uint64_t getEncodedHotnessCallEdgeInfo(const CalleeInfo &CI) {
1178   uint64_t RawFlags = 0;
1179 
1180   RawFlags |= CI.Hotness;            // 3 bits
1181   RawFlags |= (CI.HasTailCall << 3); // 1 bit
1182 
1183   return RawFlags;
1184 }
1185 
1186 static uint64_t getEncodedRelBFCallEdgeInfo(const CalleeInfo &CI) {
1187   uint64_t RawFlags = 0;
1188 
1189   RawFlags |= CI.RelBlockFreq; // CalleeInfo::RelBlockFreqBits bits
1190   RawFlags |= (CI.HasTailCall << CalleeInfo::RelBlockFreqBits); // 1 bit
1191 
1192   return RawFlags;
1193 }
1194 
1195 static unsigned getEncodedVisibility(const GlobalValue &GV) {
1196   switch (GV.getVisibility()) {
1197   case GlobalValue::DefaultVisibility:   return 0;
1198   case GlobalValue::HiddenVisibility:    return 1;
1199   case GlobalValue::ProtectedVisibility: return 2;
1200   }
1201   llvm_unreachable("Invalid visibility");
1202 }
1203 
1204 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1205   switch (GV.getDLLStorageClass()) {
1206   case GlobalValue::DefaultStorageClass:   return 0;
1207   case GlobalValue::DLLImportStorageClass: return 1;
1208   case GlobalValue::DLLExportStorageClass: return 2;
1209   }
1210   llvm_unreachable("Invalid DLL storage class");
1211 }
1212 
1213 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1214   switch (GV.getThreadLocalMode()) {
1215     case GlobalVariable::NotThreadLocal:         return 0;
1216     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1217     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1218     case GlobalVariable::InitialExecTLSModel:    return 3;
1219     case GlobalVariable::LocalExecTLSModel:      return 4;
1220   }
1221   llvm_unreachable("Invalid TLS model");
1222 }
1223 
1224 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1225   switch (C.getSelectionKind()) {
1226   case Comdat::Any:
1227     return bitc::COMDAT_SELECTION_KIND_ANY;
1228   case Comdat::ExactMatch:
1229     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1230   case Comdat::Largest:
1231     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1232   case Comdat::NoDeduplicate:
1233     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1234   case Comdat::SameSize:
1235     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1236   }
1237   llvm_unreachable("Invalid selection kind");
1238 }
1239 
1240 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1241   switch (GV.getUnnamedAddr()) {
1242   case GlobalValue::UnnamedAddr::None:   return 0;
1243   case GlobalValue::UnnamedAddr::Local:  return 2;
1244   case GlobalValue::UnnamedAddr::Global: return 1;
1245   }
1246   llvm_unreachable("Invalid unnamed_addr");
1247 }
1248 
1249 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1250   if (GenerateHash)
1251     Hasher.update(Str);
1252   return StrtabBuilder.add(Str);
1253 }
1254 
1255 void ModuleBitcodeWriter::writeComdats() {
1256   SmallVector<unsigned, 64> Vals;
1257   for (const Comdat *C : VE.getComdats()) {
1258     // COMDAT: [strtab offset, strtab size, selection_kind]
1259     Vals.push_back(addToStrtab(C->getName()));
1260     Vals.push_back(C->getName().size());
1261     Vals.push_back(getEncodedComdatSelectionKind(*C));
1262     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1263     Vals.clear();
1264   }
1265 }
1266 
1267 /// Write a record that will eventually hold the word offset of the
1268 /// module-level VST. For now the offset is 0, which will be backpatched
1269 /// after the real VST is written. Saves the bit offset to backpatch.
1270 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1271   // Write a placeholder value in for the offset of the real VST,
1272   // which is written after the function blocks so that it can include
1273   // the offset of each function. The placeholder offset will be
1274   // updated when the real VST is written.
1275   auto Abbv = std::make_shared<BitCodeAbbrev>();
1276   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1277   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1278   // hold the real VST offset. Must use fixed instead of VBR as we don't
1279   // know how many VBR chunks to reserve ahead of time.
1280   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1281   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1282 
1283   // Emit the placeholder
1284   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1285   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1286 
1287   // Compute and save the bit offset to the placeholder, which will be
1288   // patched when the real VST is written. We can simply subtract the 32-bit
1289   // fixed size from the current bit number to get the location to backpatch.
1290   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1291 }
1292 
1293 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1294 
1295 /// Determine the encoding to use for the given string name and length.
1296 static StringEncoding getStringEncoding(StringRef Str) {
1297   bool isChar6 = true;
1298   for (char C : Str) {
1299     if (isChar6)
1300       isChar6 = BitCodeAbbrevOp::isChar6(C);
1301     if ((unsigned char)C & 128)
1302       // don't bother scanning the rest.
1303       return SE_Fixed8;
1304   }
1305   if (isChar6)
1306     return SE_Char6;
1307   return SE_Fixed7;
1308 }
1309 
1310 static_assert(sizeof(GlobalValue::SanitizerMetadata) <= sizeof(unsigned),
1311               "Sanitizer Metadata is too large for naive serialization.");
1312 static unsigned
1313 serializeSanitizerMetadata(const GlobalValue::SanitizerMetadata &Meta) {
1314   return Meta.NoAddress | (Meta.NoHWAddress << 1) |
1315          (Meta.Memtag << 2) | (Meta.IsDynInit << 3);
1316 }
1317 
1318 /// Emit top-level description of module, including target triple, inline asm,
1319 /// descriptors for global variables, and function prototype info.
1320 /// Returns the bit offset to backpatch with the location of the real VST.
1321 void ModuleBitcodeWriter::writeModuleInfo() {
1322   // Emit various pieces of data attached to a module.
1323   if (!M.getTargetTriple().empty())
1324     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1325                       0 /*TODO*/);
1326   const std::string &DL = M.getDataLayoutStr();
1327   if (!DL.empty())
1328     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1329   if (!M.getModuleInlineAsm().empty())
1330     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1331                       0 /*TODO*/);
1332 
1333   // Emit information about sections and GC, computing how many there are. Also
1334   // compute the maximum alignment value.
1335   std::map<std::string, unsigned> SectionMap;
1336   std::map<std::string, unsigned> GCMap;
1337   MaybeAlign MaxAlignment;
1338   unsigned MaxGlobalType = 0;
1339   const auto UpdateMaxAlignment = [&MaxAlignment](const MaybeAlign A) {
1340     if (A)
1341       MaxAlignment = !MaxAlignment ? *A : std::max(*MaxAlignment, *A);
1342   };
1343   for (const GlobalVariable &GV : M.globals()) {
1344     UpdateMaxAlignment(GV.getAlign());
1345     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1346     if (GV.hasSection()) {
1347       // Give section names unique ID's.
1348       unsigned &Entry = SectionMap[std::string(GV.getSection())];
1349       if (!Entry) {
1350         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1351                           0 /*TODO*/);
1352         Entry = SectionMap.size();
1353       }
1354     }
1355   }
1356   for (const Function &F : M) {
1357     UpdateMaxAlignment(F.getAlign());
1358     if (F.hasSection()) {
1359       // Give section names unique ID's.
1360       unsigned &Entry = SectionMap[std::string(F.getSection())];
1361       if (!Entry) {
1362         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1363                           0 /*TODO*/);
1364         Entry = SectionMap.size();
1365       }
1366     }
1367     if (F.hasGC()) {
1368       // Same for GC names.
1369       unsigned &Entry = GCMap[F.getGC()];
1370       if (!Entry) {
1371         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1372                           0 /*TODO*/);
1373         Entry = GCMap.size();
1374       }
1375     }
1376   }
1377 
1378   // Emit abbrev for globals, now that we know # sections and max alignment.
1379   unsigned SimpleGVarAbbrev = 0;
1380   if (!M.global_empty()) {
1381     // Add an abbrev for common globals with no visibility or thread localness.
1382     auto Abbv = std::make_shared<BitCodeAbbrev>();
1383     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1384     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1385     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1386     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1387                               Log2_32_Ceil(MaxGlobalType+1)));
1388     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1389                                                            //| explicitType << 1
1390                                                            //| constant
1391     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1392     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1393     if (!MaxAlignment)                                     // Alignment.
1394       Abbv->Add(BitCodeAbbrevOp(0));
1395     else {
1396       unsigned MaxEncAlignment = getEncodedAlign(MaxAlignment);
1397       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1398                                Log2_32_Ceil(MaxEncAlignment+1)));
1399     }
1400     if (SectionMap.empty())                                    // Section.
1401       Abbv->Add(BitCodeAbbrevOp(0));
1402     else
1403       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1404                                Log2_32_Ceil(SectionMap.size()+1)));
1405     // Don't bother emitting vis + thread local.
1406     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1407   }
1408 
1409   SmallVector<unsigned, 64> Vals;
1410   // Emit the module's source file name.
1411   {
1412     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1413     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1414     if (Bits == SE_Char6)
1415       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1416     else if (Bits == SE_Fixed7)
1417       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1418 
1419     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1420     auto Abbv = std::make_shared<BitCodeAbbrev>();
1421     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1422     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1423     Abbv->Add(AbbrevOpToUse);
1424     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1425 
1426     for (const auto P : M.getSourceFileName())
1427       Vals.push_back((unsigned char)P);
1428 
1429     // Emit the finished record.
1430     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1431     Vals.clear();
1432   }
1433 
1434   // Emit the global variable information.
1435   for (const GlobalVariable &GV : M.globals()) {
1436     unsigned AbbrevToUse = 0;
1437 
1438     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1439     //             linkage, alignment, section, visibility, threadlocal,
1440     //             unnamed_addr, externally_initialized, dllstorageclass,
1441     //             comdat, attributes, DSO_Local, GlobalSanitizer, code_model]
1442     Vals.push_back(addToStrtab(GV.getName()));
1443     Vals.push_back(GV.getName().size());
1444     Vals.push_back(VE.getTypeID(GV.getValueType()));
1445     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1446     Vals.push_back(GV.isDeclaration() ? 0 :
1447                    (VE.getValueID(GV.getInitializer()) + 1));
1448     Vals.push_back(getEncodedLinkage(GV));
1449     Vals.push_back(getEncodedAlign(GV.getAlign()));
1450     Vals.push_back(GV.hasSection() ? SectionMap[std::string(GV.getSection())]
1451                                    : 0);
1452     if (GV.isThreadLocal() ||
1453         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1454         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1455         GV.isExternallyInitialized() ||
1456         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1457         GV.hasComdat() || GV.hasAttributes() || GV.isDSOLocal() ||
1458         GV.hasPartition() || GV.hasSanitizerMetadata() || GV.getCodeModel()) {
1459       Vals.push_back(getEncodedVisibility(GV));
1460       Vals.push_back(getEncodedThreadLocalMode(GV));
1461       Vals.push_back(getEncodedUnnamedAddr(GV));
1462       Vals.push_back(GV.isExternallyInitialized());
1463       Vals.push_back(getEncodedDLLStorageClass(GV));
1464       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1465 
1466       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1467       Vals.push_back(VE.getAttributeListID(AL));
1468 
1469       Vals.push_back(GV.isDSOLocal());
1470       Vals.push_back(addToStrtab(GV.getPartition()));
1471       Vals.push_back(GV.getPartition().size());
1472 
1473       Vals.push_back((GV.hasSanitizerMetadata() ? serializeSanitizerMetadata(
1474                                                       GV.getSanitizerMetadata())
1475                                                 : 0));
1476       Vals.push_back(GV.getCodeModelRaw());
1477     } else {
1478       AbbrevToUse = SimpleGVarAbbrev;
1479     }
1480 
1481     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1482     Vals.clear();
1483   }
1484 
1485   // Emit the function proto information.
1486   for (const Function &F : M) {
1487     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1488     //             linkage, paramattrs, alignment, section, visibility, gc,
1489     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1490     //             prefixdata, personalityfn, DSO_Local, addrspace]
1491     Vals.push_back(addToStrtab(F.getName()));
1492     Vals.push_back(F.getName().size());
1493     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1494     Vals.push_back(F.getCallingConv());
1495     Vals.push_back(F.isDeclaration());
1496     Vals.push_back(getEncodedLinkage(F));
1497     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1498     Vals.push_back(getEncodedAlign(F.getAlign()));
1499     Vals.push_back(F.hasSection() ? SectionMap[std::string(F.getSection())]
1500                                   : 0);
1501     Vals.push_back(getEncodedVisibility(F));
1502     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1503     Vals.push_back(getEncodedUnnamedAddr(F));
1504     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1505                                        : 0);
1506     Vals.push_back(getEncodedDLLStorageClass(F));
1507     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1508     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1509                                      : 0);
1510     Vals.push_back(
1511         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1512 
1513     Vals.push_back(F.isDSOLocal());
1514     Vals.push_back(F.getAddressSpace());
1515     Vals.push_back(addToStrtab(F.getPartition()));
1516     Vals.push_back(F.getPartition().size());
1517 
1518     unsigned AbbrevToUse = 0;
1519     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1520     Vals.clear();
1521   }
1522 
1523   // Emit the alias information.
1524   for (const GlobalAlias &A : M.aliases()) {
1525     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1526     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1527     //         DSO_Local]
1528     Vals.push_back(addToStrtab(A.getName()));
1529     Vals.push_back(A.getName().size());
1530     Vals.push_back(VE.getTypeID(A.getValueType()));
1531     Vals.push_back(A.getType()->getAddressSpace());
1532     Vals.push_back(VE.getValueID(A.getAliasee()));
1533     Vals.push_back(getEncodedLinkage(A));
1534     Vals.push_back(getEncodedVisibility(A));
1535     Vals.push_back(getEncodedDLLStorageClass(A));
1536     Vals.push_back(getEncodedThreadLocalMode(A));
1537     Vals.push_back(getEncodedUnnamedAddr(A));
1538     Vals.push_back(A.isDSOLocal());
1539     Vals.push_back(addToStrtab(A.getPartition()));
1540     Vals.push_back(A.getPartition().size());
1541 
1542     unsigned AbbrevToUse = 0;
1543     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1544     Vals.clear();
1545   }
1546 
1547   // Emit the ifunc information.
1548   for (const GlobalIFunc &I : M.ifuncs()) {
1549     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1550     //         val#, linkage, visibility, DSO_Local]
1551     Vals.push_back(addToStrtab(I.getName()));
1552     Vals.push_back(I.getName().size());
1553     Vals.push_back(VE.getTypeID(I.getValueType()));
1554     Vals.push_back(I.getType()->getAddressSpace());
1555     Vals.push_back(VE.getValueID(I.getResolver()));
1556     Vals.push_back(getEncodedLinkage(I));
1557     Vals.push_back(getEncodedVisibility(I));
1558     Vals.push_back(I.isDSOLocal());
1559     Vals.push_back(addToStrtab(I.getPartition()));
1560     Vals.push_back(I.getPartition().size());
1561     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1562     Vals.clear();
1563   }
1564 
1565   writeValueSymbolTableForwardDecl();
1566 }
1567 
1568 static uint64_t getOptimizationFlags(const Value *V) {
1569   uint64_t Flags = 0;
1570 
1571   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1572     if (OBO->hasNoSignedWrap())
1573       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1574     if (OBO->hasNoUnsignedWrap())
1575       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1576   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1577     if (PEO->isExact())
1578       Flags |= 1 << bitc::PEO_EXACT;
1579   } else if (const auto *PDI = dyn_cast<PossiblyDisjointInst>(V)) {
1580     if (PDI->isDisjoint())
1581       Flags |= 1 << bitc::PDI_DISJOINT;
1582   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1583     if (FPMO->hasAllowReassoc())
1584       Flags |= bitc::AllowReassoc;
1585     if (FPMO->hasNoNaNs())
1586       Flags |= bitc::NoNaNs;
1587     if (FPMO->hasNoInfs())
1588       Flags |= bitc::NoInfs;
1589     if (FPMO->hasNoSignedZeros())
1590       Flags |= bitc::NoSignedZeros;
1591     if (FPMO->hasAllowReciprocal())
1592       Flags |= bitc::AllowReciprocal;
1593     if (FPMO->hasAllowContract())
1594       Flags |= bitc::AllowContract;
1595     if (FPMO->hasApproxFunc())
1596       Flags |= bitc::ApproxFunc;
1597   } else if (const auto *NNI = dyn_cast<PossiblyNonNegInst>(V)) {
1598     if (NNI->hasNonNeg())
1599       Flags |= 1 << bitc::PNNI_NON_NEG;
1600   }
1601 
1602   return Flags;
1603 }
1604 
1605 void ModuleBitcodeWriter::writeValueAsMetadata(
1606     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1607   // Mimic an MDNode with a value as one operand.
1608   Value *V = MD->getValue();
1609   Record.push_back(VE.getTypeID(V->getType()));
1610   Record.push_back(VE.getValueID(V));
1611   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1612   Record.clear();
1613 }
1614 
1615 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1616                                        SmallVectorImpl<uint64_t> &Record,
1617                                        unsigned Abbrev) {
1618   for (const MDOperand &MDO : N->operands()) {
1619     Metadata *MD = MDO;
1620     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1621            "Unexpected function-local metadata");
1622     Record.push_back(VE.getMetadataOrNullID(MD));
1623   }
1624   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1625                                     : bitc::METADATA_NODE,
1626                     Record, Abbrev);
1627   Record.clear();
1628 }
1629 
1630 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1631   // Assume the column is usually under 128, and always output the inlined-at
1632   // location (it's never more expensive than building an array size 1).
1633   auto Abbv = std::make_shared<BitCodeAbbrev>();
1634   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1635   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1636   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1637   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1638   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1639   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1640   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1641   return Stream.EmitAbbrev(std::move(Abbv));
1642 }
1643 
1644 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1645                                           SmallVectorImpl<uint64_t> &Record,
1646                                           unsigned &Abbrev) {
1647   if (!Abbrev)
1648     Abbrev = createDILocationAbbrev();
1649 
1650   Record.push_back(N->isDistinct());
1651   Record.push_back(N->getLine());
1652   Record.push_back(N->getColumn());
1653   Record.push_back(VE.getMetadataID(N->getScope()));
1654   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1655   Record.push_back(N->isImplicitCode());
1656 
1657   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1658   Record.clear();
1659 }
1660 
1661 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1662   // Assume the column is usually under 128, and always output the inlined-at
1663   // location (it's never more expensive than building an array size 1).
1664   auto Abbv = std::make_shared<BitCodeAbbrev>();
1665   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1666   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1667   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1668   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1669   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1670   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1671   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1672   return Stream.EmitAbbrev(std::move(Abbv));
1673 }
1674 
1675 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1676                                              SmallVectorImpl<uint64_t> &Record,
1677                                              unsigned &Abbrev) {
1678   if (!Abbrev)
1679     Abbrev = createGenericDINodeAbbrev();
1680 
1681   Record.push_back(N->isDistinct());
1682   Record.push_back(N->getTag());
1683   Record.push_back(0); // Per-tag version field; unused for now.
1684 
1685   for (auto &I : N->operands())
1686     Record.push_back(VE.getMetadataOrNullID(I));
1687 
1688   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1689   Record.clear();
1690 }
1691 
1692 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1693                                           SmallVectorImpl<uint64_t> &Record,
1694                                           unsigned Abbrev) {
1695   const uint64_t Version = 2 << 1;
1696   Record.push_back((uint64_t)N->isDistinct() | Version);
1697   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1698   Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
1699   Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
1700   Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
1701 
1702   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1703   Record.clear();
1704 }
1705 
1706 void ModuleBitcodeWriter::writeDIGenericSubrange(
1707     const DIGenericSubrange *N, SmallVectorImpl<uint64_t> &Record,
1708     unsigned Abbrev) {
1709   Record.push_back((uint64_t)N->isDistinct());
1710   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1711   Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
1712   Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
1713   Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
1714 
1715   Stream.EmitRecord(bitc::METADATA_GENERIC_SUBRANGE, Record, Abbrev);
1716   Record.clear();
1717 }
1718 
1719 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1720   if ((int64_t)V >= 0)
1721     Vals.push_back(V << 1);
1722   else
1723     Vals.push_back((-V << 1) | 1);
1724 }
1725 
1726 static void emitWideAPInt(SmallVectorImpl<uint64_t> &Vals, const APInt &A) {
1727   // We have an arbitrary precision integer value to write whose
1728   // bit width is > 64. However, in canonical unsigned integer
1729   // format it is likely that the high bits are going to be zero.
1730   // So, we only write the number of active words.
1731   unsigned NumWords = A.getActiveWords();
1732   const uint64_t *RawData = A.getRawData();
1733   for (unsigned i = 0; i < NumWords; i++)
1734     emitSignedInt64(Vals, RawData[i]);
1735 }
1736 
1737 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1738                                             SmallVectorImpl<uint64_t> &Record,
1739                                             unsigned Abbrev) {
1740   const uint64_t IsBigInt = 1 << 2;
1741   Record.push_back(IsBigInt | (N->isUnsigned() << 1) | N->isDistinct());
1742   Record.push_back(N->getValue().getBitWidth());
1743   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1744   emitWideAPInt(Record, N->getValue());
1745 
1746   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1747   Record.clear();
1748 }
1749 
1750 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1751                                            SmallVectorImpl<uint64_t> &Record,
1752                                            unsigned Abbrev) {
1753   Record.push_back(N->isDistinct());
1754   Record.push_back(N->getTag());
1755   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1756   Record.push_back(N->getSizeInBits());
1757   Record.push_back(N->getAlignInBits());
1758   Record.push_back(N->getEncoding());
1759   Record.push_back(N->getFlags());
1760 
1761   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1762   Record.clear();
1763 }
1764 
1765 void ModuleBitcodeWriter::writeDIStringType(const DIStringType *N,
1766                                             SmallVectorImpl<uint64_t> &Record,
1767                                             unsigned Abbrev) {
1768   Record.push_back(N->isDistinct());
1769   Record.push_back(N->getTag());
1770   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1771   Record.push_back(VE.getMetadataOrNullID(N->getStringLength()));
1772   Record.push_back(VE.getMetadataOrNullID(N->getStringLengthExp()));
1773   Record.push_back(VE.getMetadataOrNullID(N->getStringLocationExp()));
1774   Record.push_back(N->getSizeInBits());
1775   Record.push_back(N->getAlignInBits());
1776   Record.push_back(N->getEncoding());
1777 
1778   Stream.EmitRecord(bitc::METADATA_STRING_TYPE, Record, Abbrev);
1779   Record.clear();
1780 }
1781 
1782 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1783                                              SmallVectorImpl<uint64_t> &Record,
1784                                              unsigned Abbrev) {
1785   Record.push_back(N->isDistinct());
1786   Record.push_back(N->getTag());
1787   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1788   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1789   Record.push_back(N->getLine());
1790   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1791   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1792   Record.push_back(N->getSizeInBits());
1793   Record.push_back(N->getAlignInBits());
1794   Record.push_back(N->getOffsetInBits());
1795   Record.push_back(N->getFlags());
1796   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1797 
1798   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1799   // that there is no DWARF address space associated with DIDerivedType.
1800   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1801     Record.push_back(*DWARFAddressSpace + 1);
1802   else
1803     Record.push_back(0);
1804 
1805   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1806 
1807   if (auto PtrAuthData = N->getPtrAuthData())
1808     Record.push_back(PtrAuthData->Payload.RawData);
1809   else
1810     Record.push_back(0);
1811 
1812   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1813   Record.clear();
1814 }
1815 
1816 void ModuleBitcodeWriter::writeDICompositeType(
1817     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1818     unsigned Abbrev) {
1819   const unsigned IsNotUsedInOldTypeRef = 0x2;
1820   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1821   Record.push_back(N->getTag());
1822   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1823   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1824   Record.push_back(N->getLine());
1825   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1826   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1827   Record.push_back(N->getSizeInBits());
1828   Record.push_back(N->getAlignInBits());
1829   Record.push_back(N->getOffsetInBits());
1830   Record.push_back(N->getFlags());
1831   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1832   Record.push_back(N->getRuntimeLang());
1833   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1834   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1835   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1836   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1837   Record.push_back(VE.getMetadataOrNullID(N->getRawDataLocation()));
1838   Record.push_back(VE.getMetadataOrNullID(N->getRawAssociated()));
1839   Record.push_back(VE.getMetadataOrNullID(N->getRawAllocated()));
1840   Record.push_back(VE.getMetadataOrNullID(N->getRawRank()));
1841   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1842 
1843   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1844   Record.clear();
1845 }
1846 
1847 void ModuleBitcodeWriter::writeDISubroutineType(
1848     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1849     unsigned Abbrev) {
1850   const unsigned HasNoOldTypeRefs = 0x2;
1851   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1852   Record.push_back(N->getFlags());
1853   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1854   Record.push_back(N->getCC());
1855 
1856   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1857   Record.clear();
1858 }
1859 
1860 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1861                                       SmallVectorImpl<uint64_t> &Record,
1862                                       unsigned Abbrev) {
1863   Record.push_back(N->isDistinct());
1864   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1865   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1866   if (N->getRawChecksum()) {
1867     Record.push_back(N->getRawChecksum()->Kind);
1868     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1869   } else {
1870     // Maintain backwards compatibility with the old internal representation of
1871     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1872     Record.push_back(0);
1873     Record.push_back(VE.getMetadataOrNullID(nullptr));
1874   }
1875   auto Source = N->getRawSource();
1876   if (Source)
1877     Record.push_back(VE.getMetadataOrNullID(Source));
1878 
1879   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1880   Record.clear();
1881 }
1882 
1883 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1884                                              SmallVectorImpl<uint64_t> &Record,
1885                                              unsigned Abbrev) {
1886   assert(N->isDistinct() && "Expected distinct compile units");
1887   Record.push_back(/* IsDistinct */ true);
1888   Record.push_back(N->getSourceLanguage());
1889   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1890   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1891   Record.push_back(N->isOptimized());
1892   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1893   Record.push_back(N->getRuntimeVersion());
1894   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1895   Record.push_back(N->getEmissionKind());
1896   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1897   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1898   Record.push_back(/* subprograms */ 0);
1899   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1900   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1901   Record.push_back(N->getDWOId());
1902   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1903   Record.push_back(N->getSplitDebugInlining());
1904   Record.push_back(N->getDebugInfoForProfiling());
1905   Record.push_back((unsigned)N->getNameTableKind());
1906   Record.push_back(N->getRangesBaseAddress());
1907   Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
1908   Record.push_back(VE.getMetadataOrNullID(N->getRawSDK()));
1909 
1910   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1911   Record.clear();
1912 }
1913 
1914 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1915                                             SmallVectorImpl<uint64_t> &Record,
1916                                             unsigned Abbrev) {
1917   const uint64_t HasUnitFlag = 1 << 1;
1918   const uint64_t HasSPFlagsFlag = 1 << 2;
1919   Record.push_back(uint64_t(N->isDistinct()) | HasUnitFlag | HasSPFlagsFlag);
1920   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1921   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1922   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1923   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1924   Record.push_back(N->getLine());
1925   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1926   Record.push_back(N->getScopeLine());
1927   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1928   Record.push_back(N->getSPFlags());
1929   Record.push_back(N->getVirtualIndex());
1930   Record.push_back(N->getFlags());
1931   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1932   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1933   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1934   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1935   Record.push_back(N->getThisAdjustment());
1936   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1937   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
1938   Record.push_back(VE.getMetadataOrNullID(N->getRawTargetFuncName()));
1939 
1940   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1941   Record.clear();
1942 }
1943 
1944 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1945                                               SmallVectorImpl<uint64_t> &Record,
1946                                               unsigned Abbrev) {
1947   Record.push_back(N->isDistinct());
1948   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1949   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1950   Record.push_back(N->getLine());
1951   Record.push_back(N->getColumn());
1952 
1953   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1954   Record.clear();
1955 }
1956 
1957 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1958     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1959     unsigned Abbrev) {
1960   Record.push_back(N->isDistinct());
1961   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1962   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1963   Record.push_back(N->getDiscriminator());
1964 
1965   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1966   Record.clear();
1967 }
1968 
1969 void ModuleBitcodeWriter::writeDICommonBlock(const DICommonBlock *N,
1970                                              SmallVectorImpl<uint64_t> &Record,
1971                                              unsigned Abbrev) {
1972   Record.push_back(N->isDistinct());
1973   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1974   Record.push_back(VE.getMetadataOrNullID(N->getDecl()));
1975   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1976   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1977   Record.push_back(N->getLineNo());
1978 
1979   Stream.EmitRecord(bitc::METADATA_COMMON_BLOCK, Record, Abbrev);
1980   Record.clear();
1981 }
1982 
1983 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1984                                            SmallVectorImpl<uint64_t> &Record,
1985                                            unsigned Abbrev) {
1986   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1987   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1988   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1989 
1990   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1991   Record.clear();
1992 }
1993 
1994 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1995                                        SmallVectorImpl<uint64_t> &Record,
1996                                        unsigned Abbrev) {
1997   Record.push_back(N->isDistinct());
1998   Record.push_back(N->getMacinfoType());
1999   Record.push_back(N->getLine());
2000   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2001   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
2002 
2003   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
2004   Record.clear();
2005 }
2006 
2007 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
2008                                            SmallVectorImpl<uint64_t> &Record,
2009                                            unsigned Abbrev) {
2010   Record.push_back(N->isDistinct());
2011   Record.push_back(N->getMacinfoType());
2012   Record.push_back(N->getLine());
2013   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2014   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
2015 
2016   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
2017   Record.clear();
2018 }
2019 
2020 void ModuleBitcodeWriter::writeDIArgList(const DIArgList *N,
2021                                          SmallVectorImpl<uint64_t> &Record) {
2022   Record.reserve(N->getArgs().size());
2023   for (ValueAsMetadata *MD : N->getArgs())
2024     Record.push_back(VE.getMetadataID(MD));
2025 
2026   Stream.EmitRecord(bitc::METADATA_ARG_LIST, Record);
2027   Record.clear();
2028 }
2029 
2030 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
2031                                         SmallVectorImpl<uint64_t> &Record,
2032                                         unsigned Abbrev) {
2033   Record.push_back(N->isDistinct());
2034   for (auto &I : N->operands())
2035     Record.push_back(VE.getMetadataOrNullID(I));
2036   Record.push_back(N->getLineNo());
2037   Record.push_back(N->getIsDecl());
2038 
2039   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
2040   Record.clear();
2041 }
2042 
2043 void ModuleBitcodeWriter::writeDIAssignID(const DIAssignID *N,
2044                                           SmallVectorImpl<uint64_t> &Record,
2045                                           unsigned Abbrev) {
2046   // There are no arguments for this metadata type.
2047   Record.push_back(N->isDistinct());
2048   Stream.EmitRecord(bitc::METADATA_ASSIGN_ID, Record, Abbrev);
2049   Record.clear();
2050 }
2051 
2052 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
2053     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
2054     unsigned Abbrev) {
2055   Record.push_back(N->isDistinct());
2056   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2057   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2058   Record.push_back(N->isDefault());
2059 
2060   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
2061   Record.clear();
2062 }
2063 
2064 void ModuleBitcodeWriter::writeDITemplateValueParameter(
2065     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
2066     unsigned Abbrev) {
2067   Record.push_back(N->isDistinct());
2068   Record.push_back(N->getTag());
2069   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2070   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2071   Record.push_back(N->isDefault());
2072   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
2073 
2074   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
2075   Record.clear();
2076 }
2077 
2078 void ModuleBitcodeWriter::writeDIGlobalVariable(
2079     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
2080     unsigned Abbrev) {
2081   const uint64_t Version = 2 << 1;
2082   Record.push_back((uint64_t)N->isDistinct() | Version);
2083   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2084   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2085   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
2086   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2087   Record.push_back(N->getLine());
2088   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2089   Record.push_back(N->isLocalToUnit());
2090   Record.push_back(N->isDefinition());
2091   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
2092   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
2093   Record.push_back(N->getAlignInBits());
2094   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
2095 
2096   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
2097   Record.clear();
2098 }
2099 
2100 void ModuleBitcodeWriter::writeDILocalVariable(
2101     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
2102     unsigned Abbrev) {
2103   // In order to support all possible bitcode formats in BitcodeReader we need
2104   // to distinguish the following cases:
2105   // 1) Record has no artificial tag (Record[1]),
2106   //   has no obsolete inlinedAt field (Record[9]).
2107   //   In this case Record size will be 8, HasAlignment flag is false.
2108   // 2) Record has artificial tag (Record[1]),
2109   //   has no obsolete inlignedAt field (Record[9]).
2110   //   In this case Record size will be 9, HasAlignment flag is false.
2111   // 3) Record has both artificial tag (Record[1]) and
2112   //   obsolete inlignedAt field (Record[9]).
2113   //   In this case Record size will be 10, HasAlignment flag is false.
2114   // 4) Record has neither artificial tag, nor inlignedAt field, but
2115   //   HasAlignment flag is true and Record[8] contains alignment value.
2116   const uint64_t HasAlignmentFlag = 1 << 1;
2117   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
2118   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2119   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2120   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2121   Record.push_back(N->getLine());
2122   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2123   Record.push_back(N->getArg());
2124   Record.push_back(N->getFlags());
2125   Record.push_back(N->getAlignInBits());
2126   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
2127 
2128   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
2129   Record.clear();
2130 }
2131 
2132 void ModuleBitcodeWriter::writeDILabel(
2133     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
2134     unsigned Abbrev) {
2135   Record.push_back((uint64_t)N->isDistinct());
2136   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2137   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2138   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2139   Record.push_back(N->getLine());
2140 
2141   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
2142   Record.clear();
2143 }
2144 
2145 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
2146                                             SmallVectorImpl<uint64_t> &Record,
2147                                             unsigned Abbrev) {
2148   Record.reserve(N->getElements().size() + 1);
2149   const uint64_t Version = 3 << 1;
2150   Record.push_back((uint64_t)N->isDistinct() | Version);
2151   Record.append(N->elements_begin(), N->elements_end());
2152 
2153   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
2154   Record.clear();
2155 }
2156 
2157 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
2158     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
2159     unsigned Abbrev) {
2160   Record.push_back(N->isDistinct());
2161   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
2162   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
2163 
2164   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
2165   Record.clear();
2166 }
2167 
2168 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
2169                                               SmallVectorImpl<uint64_t> &Record,
2170                                               unsigned Abbrev) {
2171   Record.push_back(N->isDistinct());
2172   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2173   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
2174   Record.push_back(N->getLine());
2175   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
2176   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
2177   Record.push_back(N->getAttributes());
2178   Record.push_back(VE.getMetadataOrNullID(N->getType()));
2179 
2180   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
2181   Record.clear();
2182 }
2183 
2184 void ModuleBitcodeWriter::writeDIImportedEntity(
2185     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
2186     unsigned Abbrev) {
2187   Record.push_back(N->isDistinct());
2188   Record.push_back(N->getTag());
2189   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
2190   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
2191   Record.push_back(N->getLine());
2192   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
2193   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
2194   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
2195 
2196   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
2197   Record.clear();
2198 }
2199 
2200 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
2201   auto Abbv = std::make_shared<BitCodeAbbrev>();
2202   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
2203   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2204   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2205   return Stream.EmitAbbrev(std::move(Abbv));
2206 }
2207 
2208 void ModuleBitcodeWriter::writeNamedMetadata(
2209     SmallVectorImpl<uint64_t> &Record) {
2210   if (M.named_metadata_empty())
2211     return;
2212 
2213   unsigned Abbrev = createNamedMetadataAbbrev();
2214   for (const NamedMDNode &NMD : M.named_metadata()) {
2215     // Write name.
2216     StringRef Str = NMD.getName();
2217     Record.append(Str.bytes_begin(), Str.bytes_end());
2218     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
2219     Record.clear();
2220 
2221     // Write named metadata operands.
2222     for (const MDNode *N : NMD.operands())
2223       Record.push_back(VE.getMetadataID(N));
2224     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
2225     Record.clear();
2226   }
2227 }
2228 
2229 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
2230   auto Abbv = std::make_shared<BitCodeAbbrev>();
2231   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
2232   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
2233   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
2234   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2235   return Stream.EmitAbbrev(std::move(Abbv));
2236 }
2237 
2238 /// Write out a record for MDString.
2239 ///
2240 /// All the metadata strings in a metadata block are emitted in a single
2241 /// record.  The sizes and strings themselves are shoved into a blob.
2242 void ModuleBitcodeWriter::writeMetadataStrings(
2243     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
2244   if (Strings.empty())
2245     return;
2246 
2247   // Start the record with the number of strings.
2248   Record.push_back(bitc::METADATA_STRINGS);
2249   Record.push_back(Strings.size());
2250 
2251   // Emit the sizes of the strings in the blob.
2252   SmallString<256> Blob;
2253   {
2254     BitstreamWriter W(Blob);
2255     for (const Metadata *MD : Strings)
2256       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
2257     W.FlushToWord();
2258   }
2259 
2260   // Add the offset to the strings to the record.
2261   Record.push_back(Blob.size());
2262 
2263   // Add the strings to the blob.
2264   for (const Metadata *MD : Strings)
2265     Blob.append(cast<MDString>(MD)->getString());
2266 
2267   // Emit the final record.
2268   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
2269   Record.clear();
2270 }
2271 
2272 // Generates an enum to use as an index in the Abbrev array of Metadata record.
2273 enum MetadataAbbrev : unsigned {
2274 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
2275 #include "llvm/IR/Metadata.def"
2276   LastPlusOne
2277 };
2278 
2279 void ModuleBitcodeWriter::writeMetadataRecords(
2280     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
2281     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
2282   if (MDs.empty())
2283     return;
2284 
2285   // Initialize MDNode abbreviations.
2286 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
2287 #include "llvm/IR/Metadata.def"
2288 
2289   for (const Metadata *MD : MDs) {
2290     if (IndexPos)
2291       IndexPos->push_back(Stream.GetCurrentBitNo());
2292     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
2293       assert(N->isResolved() && "Expected forward references to be resolved");
2294 
2295       switch (N->getMetadataID()) {
2296       default:
2297         llvm_unreachable("Invalid MDNode subclass");
2298 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
2299   case Metadata::CLASS##Kind:                                                  \
2300     if (MDAbbrevs)                                                             \
2301       write##CLASS(cast<CLASS>(N), Record,                                     \
2302                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
2303     else                                                                       \
2304       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
2305     continue;
2306 #include "llvm/IR/Metadata.def"
2307       }
2308     }
2309     if (auto *AL = dyn_cast<DIArgList>(MD)) {
2310       writeDIArgList(AL, Record);
2311       continue;
2312     }
2313     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
2314   }
2315 }
2316 
2317 void ModuleBitcodeWriter::writeModuleMetadata() {
2318   if (!VE.hasMDs() && M.named_metadata_empty())
2319     return;
2320 
2321   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
2322   SmallVector<uint64_t, 64> Record;
2323 
2324   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
2325   // block and load any metadata.
2326   std::vector<unsigned> MDAbbrevs;
2327 
2328   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
2329   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
2330   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
2331       createGenericDINodeAbbrev();
2332 
2333   auto Abbv = std::make_shared<BitCodeAbbrev>();
2334   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
2335   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2336   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2337   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2338 
2339   Abbv = std::make_shared<BitCodeAbbrev>();
2340   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
2341   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2342   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2343   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2344 
2345   // Emit MDStrings together upfront.
2346   writeMetadataStrings(VE.getMDStrings(), Record);
2347 
2348   // We only emit an index for the metadata record if we have more than a given
2349   // (naive) threshold of metadatas, otherwise it is not worth it.
2350   if (VE.getNonMDStrings().size() > IndexThreshold) {
2351     // Write a placeholder value in for the offset of the metadata index,
2352     // which is written after the records, so that it can include
2353     // the offset of each entry. The placeholder offset will be
2354     // updated after all records are emitted.
2355     uint64_t Vals[] = {0, 0};
2356     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2357   }
2358 
2359   // Compute and save the bit offset to the current position, which will be
2360   // patched when we emit the index later. We can simply subtract the 64-bit
2361   // fixed size from the current bit number to get the location to backpatch.
2362   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2363 
2364   // This index will contain the bitpos for each individual record.
2365   std::vector<uint64_t> IndexPos;
2366   IndexPos.reserve(VE.getNonMDStrings().size());
2367 
2368   // Write all the records
2369   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2370 
2371   if (VE.getNonMDStrings().size() > IndexThreshold) {
2372     // Now that we have emitted all the records we will emit the index. But
2373     // first
2374     // backpatch the forward reference so that the reader can skip the records
2375     // efficiently.
2376     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2377                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2378 
2379     // Delta encode the index.
2380     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2381     for (auto &Elt : IndexPos) {
2382       auto EltDelta = Elt - PreviousValue;
2383       PreviousValue = Elt;
2384       Elt = EltDelta;
2385     }
2386     // Emit the index record.
2387     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2388     IndexPos.clear();
2389   }
2390 
2391   // Write the named metadata now.
2392   writeNamedMetadata(Record);
2393 
2394   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2395     SmallVector<uint64_t, 4> Record;
2396     Record.push_back(VE.getValueID(&GO));
2397     pushGlobalMetadataAttachment(Record, GO);
2398     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2399   };
2400   for (const Function &F : M)
2401     if (F.isDeclaration() && F.hasMetadata())
2402       AddDeclAttachedMetadata(F);
2403   // FIXME: Only store metadata for declarations here, and move data for global
2404   // variable definitions to a separate block (PR28134).
2405   for (const GlobalVariable &GV : M.globals())
2406     if (GV.hasMetadata())
2407       AddDeclAttachedMetadata(GV);
2408 
2409   Stream.ExitBlock();
2410 }
2411 
2412 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2413   if (!VE.hasMDs())
2414     return;
2415 
2416   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2417   SmallVector<uint64_t, 64> Record;
2418   writeMetadataStrings(VE.getMDStrings(), Record);
2419   writeMetadataRecords(VE.getNonMDStrings(), Record);
2420   Stream.ExitBlock();
2421 }
2422 
2423 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2424     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2425   // [n x [id, mdnode]]
2426   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2427   GO.getAllMetadata(MDs);
2428   for (const auto &I : MDs) {
2429     Record.push_back(I.first);
2430     Record.push_back(VE.getMetadataID(I.second));
2431   }
2432 }
2433 
2434 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2435   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2436 
2437   SmallVector<uint64_t, 64> Record;
2438 
2439   if (F.hasMetadata()) {
2440     pushGlobalMetadataAttachment(Record, F);
2441     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2442     Record.clear();
2443   }
2444 
2445   // Write metadata attachments
2446   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2447   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2448   for (const BasicBlock &BB : F)
2449     for (const Instruction &I : BB) {
2450       MDs.clear();
2451       I.getAllMetadataOtherThanDebugLoc(MDs);
2452 
2453       // If no metadata, ignore instruction.
2454       if (MDs.empty()) continue;
2455 
2456       Record.push_back(VE.getInstructionID(&I));
2457 
2458       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2459         Record.push_back(MDs[i].first);
2460         Record.push_back(VE.getMetadataID(MDs[i].second));
2461       }
2462       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2463       Record.clear();
2464     }
2465 
2466   Stream.ExitBlock();
2467 }
2468 
2469 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2470   SmallVector<uint64_t, 64> Record;
2471 
2472   // Write metadata kinds
2473   // METADATA_KIND - [n x [id, name]]
2474   SmallVector<StringRef, 8> Names;
2475   M.getMDKindNames(Names);
2476 
2477   if (Names.empty()) return;
2478 
2479   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2480 
2481   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2482     Record.push_back(MDKindID);
2483     StringRef KName = Names[MDKindID];
2484     Record.append(KName.begin(), KName.end());
2485 
2486     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2487     Record.clear();
2488   }
2489 
2490   Stream.ExitBlock();
2491 }
2492 
2493 void ModuleBitcodeWriter::writeOperandBundleTags() {
2494   // Write metadata kinds
2495   //
2496   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2497   //
2498   // OPERAND_BUNDLE_TAG - [strchr x N]
2499 
2500   SmallVector<StringRef, 8> Tags;
2501   M.getOperandBundleTags(Tags);
2502 
2503   if (Tags.empty())
2504     return;
2505 
2506   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2507 
2508   SmallVector<uint64_t, 64> Record;
2509 
2510   for (auto Tag : Tags) {
2511     Record.append(Tag.begin(), Tag.end());
2512 
2513     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2514     Record.clear();
2515   }
2516 
2517   Stream.ExitBlock();
2518 }
2519 
2520 void ModuleBitcodeWriter::writeSyncScopeNames() {
2521   SmallVector<StringRef, 8> SSNs;
2522   M.getContext().getSyncScopeNames(SSNs);
2523   if (SSNs.empty())
2524     return;
2525 
2526   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2527 
2528   SmallVector<uint64_t, 64> Record;
2529   for (auto SSN : SSNs) {
2530     Record.append(SSN.begin(), SSN.end());
2531     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2532     Record.clear();
2533   }
2534 
2535   Stream.ExitBlock();
2536 }
2537 
2538 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2539                                          bool isGlobal) {
2540   if (FirstVal == LastVal) return;
2541 
2542   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2543 
2544   unsigned AggregateAbbrev = 0;
2545   unsigned String8Abbrev = 0;
2546   unsigned CString7Abbrev = 0;
2547   unsigned CString6Abbrev = 0;
2548   // If this is a constant pool for the module, emit module-specific abbrevs.
2549   if (isGlobal) {
2550     // Abbrev for CST_CODE_AGGREGATE.
2551     auto Abbv = std::make_shared<BitCodeAbbrev>();
2552     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2553     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2554     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2555     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2556 
2557     // Abbrev for CST_CODE_STRING.
2558     Abbv = std::make_shared<BitCodeAbbrev>();
2559     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2560     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2561     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2562     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2563     // Abbrev for CST_CODE_CSTRING.
2564     Abbv = std::make_shared<BitCodeAbbrev>();
2565     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2566     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2567     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2568     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2569     // Abbrev for CST_CODE_CSTRING.
2570     Abbv = std::make_shared<BitCodeAbbrev>();
2571     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2572     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2573     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2574     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2575   }
2576 
2577   SmallVector<uint64_t, 64> Record;
2578 
2579   const ValueEnumerator::ValueList &Vals = VE.getValues();
2580   Type *LastTy = nullptr;
2581   for (unsigned i = FirstVal; i != LastVal; ++i) {
2582     const Value *V = Vals[i].first;
2583     // If we need to switch types, do so now.
2584     if (V->getType() != LastTy) {
2585       LastTy = V->getType();
2586       Record.push_back(VE.getTypeID(LastTy));
2587       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2588                         CONSTANTS_SETTYPE_ABBREV);
2589       Record.clear();
2590     }
2591 
2592     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2593       Record.push_back(VE.getTypeID(IA->getFunctionType()));
2594       Record.push_back(
2595           unsigned(IA->hasSideEffects()) | unsigned(IA->isAlignStack()) << 1 |
2596           unsigned(IA->getDialect() & 1) << 2 | unsigned(IA->canThrow()) << 3);
2597 
2598       // Add the asm string.
2599       const std::string &AsmStr = IA->getAsmString();
2600       Record.push_back(AsmStr.size());
2601       Record.append(AsmStr.begin(), AsmStr.end());
2602 
2603       // Add the constraint string.
2604       const std::string &ConstraintStr = IA->getConstraintString();
2605       Record.push_back(ConstraintStr.size());
2606       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2607       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2608       Record.clear();
2609       continue;
2610     }
2611     const Constant *C = cast<Constant>(V);
2612     unsigned Code = -1U;
2613     unsigned AbbrevToUse = 0;
2614     if (C->isNullValue()) {
2615       Code = bitc::CST_CODE_NULL;
2616     } else if (isa<PoisonValue>(C)) {
2617       Code = bitc::CST_CODE_POISON;
2618     } else if (isa<UndefValue>(C)) {
2619       Code = bitc::CST_CODE_UNDEF;
2620     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2621       if (IV->getBitWidth() <= 64) {
2622         uint64_t V = IV->getSExtValue();
2623         emitSignedInt64(Record, V);
2624         Code = bitc::CST_CODE_INTEGER;
2625         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2626       } else {                             // Wide integers, > 64 bits in size.
2627         emitWideAPInt(Record, IV->getValue());
2628         Code = bitc::CST_CODE_WIDE_INTEGER;
2629       }
2630     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2631       Code = bitc::CST_CODE_FLOAT;
2632       Type *Ty = CFP->getType()->getScalarType();
2633       if (Ty->isHalfTy() || Ty->isBFloatTy() || Ty->isFloatTy() ||
2634           Ty->isDoubleTy()) {
2635         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2636       } else if (Ty->isX86_FP80Ty()) {
2637         // api needed to prevent premature destruction
2638         // bits are not in the same order as a normal i80 APInt, compensate.
2639         APInt api = CFP->getValueAPF().bitcastToAPInt();
2640         const uint64_t *p = api.getRawData();
2641         Record.push_back((p[1] << 48) | (p[0] >> 16));
2642         Record.push_back(p[0] & 0xffffLL);
2643       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2644         APInt api = CFP->getValueAPF().bitcastToAPInt();
2645         const uint64_t *p = api.getRawData();
2646         Record.push_back(p[0]);
2647         Record.push_back(p[1]);
2648       } else {
2649         assert(0 && "Unknown FP type!");
2650       }
2651     } else if (isa<ConstantDataSequential>(C) &&
2652                cast<ConstantDataSequential>(C)->isString()) {
2653       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2654       // Emit constant strings specially.
2655       unsigned NumElts = Str->getNumElements();
2656       // If this is a null-terminated string, use the denser CSTRING encoding.
2657       if (Str->isCString()) {
2658         Code = bitc::CST_CODE_CSTRING;
2659         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2660       } else {
2661         Code = bitc::CST_CODE_STRING;
2662         AbbrevToUse = String8Abbrev;
2663       }
2664       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2665       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2666       for (unsigned i = 0; i != NumElts; ++i) {
2667         unsigned char V = Str->getElementAsInteger(i);
2668         Record.push_back(V);
2669         isCStr7 &= (V & 128) == 0;
2670         if (isCStrChar6)
2671           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2672       }
2673 
2674       if (isCStrChar6)
2675         AbbrevToUse = CString6Abbrev;
2676       else if (isCStr7)
2677         AbbrevToUse = CString7Abbrev;
2678     } else if (const ConstantDataSequential *CDS =
2679                   dyn_cast<ConstantDataSequential>(C)) {
2680       Code = bitc::CST_CODE_DATA;
2681       Type *EltTy = CDS->getElementType();
2682       if (isa<IntegerType>(EltTy)) {
2683         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2684           Record.push_back(CDS->getElementAsInteger(i));
2685       } else {
2686         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2687           Record.push_back(
2688               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2689       }
2690     } else if (isa<ConstantAggregate>(C)) {
2691       Code = bitc::CST_CODE_AGGREGATE;
2692       for (const Value *Op : C->operands())
2693         Record.push_back(VE.getValueID(Op));
2694       AbbrevToUse = AggregateAbbrev;
2695     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2696       switch (CE->getOpcode()) {
2697       default:
2698         if (Instruction::isCast(CE->getOpcode())) {
2699           Code = bitc::CST_CODE_CE_CAST;
2700           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2701           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2702           Record.push_back(VE.getValueID(C->getOperand(0)));
2703           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2704         } else {
2705           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2706           Code = bitc::CST_CODE_CE_BINOP;
2707           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2708           Record.push_back(VE.getValueID(C->getOperand(0)));
2709           Record.push_back(VE.getValueID(C->getOperand(1)));
2710           uint64_t Flags = getOptimizationFlags(CE);
2711           if (Flags != 0)
2712             Record.push_back(Flags);
2713         }
2714         break;
2715       case Instruction::FNeg: {
2716         assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
2717         Code = bitc::CST_CODE_CE_UNOP;
2718         Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
2719         Record.push_back(VE.getValueID(C->getOperand(0)));
2720         uint64_t Flags = getOptimizationFlags(CE);
2721         if (Flags != 0)
2722           Record.push_back(Flags);
2723         break;
2724       }
2725       case Instruction::GetElementPtr: {
2726         Code = bitc::CST_CODE_CE_GEP;
2727         const auto *GO = cast<GEPOperator>(C);
2728         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2729         if (std::optional<unsigned> Idx = GO->getInRangeIndex()) {
2730           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2731           Record.push_back((*Idx << 1) | GO->isInBounds());
2732         } else if (GO->isInBounds())
2733           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2734         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2735           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2736           Record.push_back(VE.getValueID(C->getOperand(i)));
2737         }
2738         break;
2739       }
2740       case Instruction::ExtractElement:
2741         Code = bitc::CST_CODE_CE_EXTRACTELT;
2742         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2743         Record.push_back(VE.getValueID(C->getOperand(0)));
2744         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2745         Record.push_back(VE.getValueID(C->getOperand(1)));
2746         break;
2747       case Instruction::InsertElement:
2748         Code = bitc::CST_CODE_CE_INSERTELT;
2749         Record.push_back(VE.getValueID(C->getOperand(0)));
2750         Record.push_back(VE.getValueID(C->getOperand(1)));
2751         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2752         Record.push_back(VE.getValueID(C->getOperand(2)));
2753         break;
2754       case Instruction::ShuffleVector:
2755         // If the return type and argument types are the same, this is a
2756         // standard shufflevector instruction.  If the types are different,
2757         // then the shuffle is widening or truncating the input vectors, and
2758         // the argument type must also be encoded.
2759         if (C->getType() == C->getOperand(0)->getType()) {
2760           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2761         } else {
2762           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2763           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2764         }
2765         Record.push_back(VE.getValueID(C->getOperand(0)));
2766         Record.push_back(VE.getValueID(C->getOperand(1)));
2767         Record.push_back(VE.getValueID(CE->getShuffleMaskForBitcode()));
2768         break;
2769       case Instruction::ICmp:
2770       case Instruction::FCmp:
2771         Code = bitc::CST_CODE_CE_CMP;
2772         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2773         Record.push_back(VE.getValueID(C->getOperand(0)));
2774         Record.push_back(VE.getValueID(C->getOperand(1)));
2775         Record.push_back(CE->getPredicate());
2776         break;
2777       }
2778     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2779       Code = bitc::CST_CODE_BLOCKADDRESS;
2780       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2781       Record.push_back(VE.getValueID(BA->getFunction()));
2782       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2783     } else if (const auto *Equiv = dyn_cast<DSOLocalEquivalent>(C)) {
2784       Code = bitc::CST_CODE_DSO_LOCAL_EQUIVALENT;
2785       Record.push_back(VE.getTypeID(Equiv->getGlobalValue()->getType()));
2786       Record.push_back(VE.getValueID(Equiv->getGlobalValue()));
2787     } else if (const auto *NC = dyn_cast<NoCFIValue>(C)) {
2788       Code = bitc::CST_CODE_NO_CFI_VALUE;
2789       Record.push_back(VE.getTypeID(NC->getGlobalValue()->getType()));
2790       Record.push_back(VE.getValueID(NC->getGlobalValue()));
2791     } else {
2792 #ifndef NDEBUG
2793       C->dump();
2794 #endif
2795       llvm_unreachable("Unknown constant!");
2796     }
2797     Stream.EmitRecord(Code, Record, AbbrevToUse);
2798     Record.clear();
2799   }
2800 
2801   Stream.ExitBlock();
2802 }
2803 
2804 void ModuleBitcodeWriter::writeModuleConstants() {
2805   const ValueEnumerator::ValueList &Vals = VE.getValues();
2806 
2807   // Find the first constant to emit, which is the first non-globalvalue value.
2808   // We know globalvalues have been emitted by WriteModuleInfo.
2809   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2810     if (!isa<GlobalValue>(Vals[i].first)) {
2811       writeConstants(i, Vals.size(), true);
2812       return;
2813     }
2814   }
2815 }
2816 
2817 /// pushValueAndType - The file has to encode both the value and type id for
2818 /// many values, because we need to know what type to create for forward
2819 /// references.  However, most operands are not forward references, so this type
2820 /// field is not needed.
2821 ///
2822 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2823 /// instruction ID, then it is a forward reference, and it also includes the
2824 /// type ID.  The value ID that is written is encoded relative to the InstID.
2825 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2826                                            SmallVectorImpl<unsigned> &Vals) {
2827   unsigned ValID = VE.getValueID(V);
2828   // Make encoding relative to the InstID.
2829   Vals.push_back(InstID - ValID);
2830   if (ValID >= InstID) {
2831     Vals.push_back(VE.getTypeID(V->getType()));
2832     return true;
2833   }
2834   return false;
2835 }
2836 
2837 void ModuleBitcodeWriter::writeOperandBundles(const CallBase &CS,
2838                                               unsigned InstID) {
2839   SmallVector<unsigned, 64> Record;
2840   LLVMContext &C = CS.getContext();
2841 
2842   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2843     const auto &Bundle = CS.getOperandBundleAt(i);
2844     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2845 
2846     for (auto &Input : Bundle.Inputs)
2847       pushValueAndType(Input, InstID, Record);
2848 
2849     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2850     Record.clear();
2851   }
2852 }
2853 
2854 /// pushValue - Like pushValueAndType, but where the type of the value is
2855 /// omitted (perhaps it was already encoded in an earlier operand).
2856 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2857                                     SmallVectorImpl<unsigned> &Vals) {
2858   unsigned ValID = VE.getValueID(V);
2859   Vals.push_back(InstID - ValID);
2860 }
2861 
2862 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2863                                           SmallVectorImpl<uint64_t> &Vals) {
2864   unsigned ValID = VE.getValueID(V);
2865   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2866   emitSignedInt64(Vals, diff);
2867 }
2868 
2869 /// WriteInstruction - Emit an instruction to the specified stream.
2870 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2871                                            unsigned InstID,
2872                                            SmallVectorImpl<unsigned> &Vals) {
2873   unsigned Code = 0;
2874   unsigned AbbrevToUse = 0;
2875   VE.setInstructionID(&I);
2876   switch (I.getOpcode()) {
2877   default:
2878     if (Instruction::isCast(I.getOpcode())) {
2879       Code = bitc::FUNC_CODE_INST_CAST;
2880       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2881         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2882       Vals.push_back(VE.getTypeID(I.getType()));
2883       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2884       uint64_t Flags = getOptimizationFlags(&I);
2885       if (Flags != 0) {
2886         if (AbbrevToUse == FUNCTION_INST_CAST_ABBREV)
2887           AbbrevToUse = FUNCTION_INST_CAST_FLAGS_ABBREV;
2888         Vals.push_back(Flags);
2889       }
2890     } else {
2891       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2892       Code = bitc::FUNC_CODE_INST_BINOP;
2893       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2894         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2895       pushValue(I.getOperand(1), InstID, Vals);
2896       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2897       uint64_t Flags = getOptimizationFlags(&I);
2898       if (Flags != 0) {
2899         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2900           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2901         Vals.push_back(Flags);
2902       }
2903     }
2904     break;
2905   case Instruction::FNeg: {
2906     Code = bitc::FUNC_CODE_INST_UNOP;
2907     if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2908       AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
2909     Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
2910     uint64_t Flags = getOptimizationFlags(&I);
2911     if (Flags != 0) {
2912       if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
2913         AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
2914       Vals.push_back(Flags);
2915     }
2916     break;
2917   }
2918   case Instruction::GetElementPtr: {
2919     Code = bitc::FUNC_CODE_INST_GEP;
2920     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2921     auto &GEPInst = cast<GetElementPtrInst>(I);
2922     Vals.push_back(GEPInst.isInBounds());
2923     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2924     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2925       pushValueAndType(I.getOperand(i), InstID, Vals);
2926     break;
2927   }
2928   case Instruction::ExtractValue: {
2929     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2930     pushValueAndType(I.getOperand(0), InstID, Vals);
2931     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2932     Vals.append(EVI->idx_begin(), EVI->idx_end());
2933     break;
2934   }
2935   case Instruction::InsertValue: {
2936     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2937     pushValueAndType(I.getOperand(0), InstID, Vals);
2938     pushValueAndType(I.getOperand(1), InstID, Vals);
2939     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2940     Vals.append(IVI->idx_begin(), IVI->idx_end());
2941     break;
2942   }
2943   case Instruction::Select: {
2944     Code = bitc::FUNC_CODE_INST_VSELECT;
2945     pushValueAndType(I.getOperand(1), InstID, Vals);
2946     pushValue(I.getOperand(2), InstID, Vals);
2947     pushValueAndType(I.getOperand(0), InstID, Vals);
2948     uint64_t Flags = getOptimizationFlags(&I);
2949     if (Flags != 0)
2950       Vals.push_back(Flags);
2951     break;
2952   }
2953   case Instruction::ExtractElement:
2954     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2955     pushValueAndType(I.getOperand(0), InstID, Vals);
2956     pushValueAndType(I.getOperand(1), InstID, Vals);
2957     break;
2958   case Instruction::InsertElement:
2959     Code = bitc::FUNC_CODE_INST_INSERTELT;
2960     pushValueAndType(I.getOperand(0), InstID, Vals);
2961     pushValue(I.getOperand(1), InstID, Vals);
2962     pushValueAndType(I.getOperand(2), InstID, Vals);
2963     break;
2964   case Instruction::ShuffleVector:
2965     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2966     pushValueAndType(I.getOperand(0), InstID, Vals);
2967     pushValue(I.getOperand(1), InstID, Vals);
2968     pushValue(cast<ShuffleVectorInst>(I).getShuffleMaskForBitcode(), InstID,
2969               Vals);
2970     break;
2971   case Instruction::ICmp:
2972   case Instruction::FCmp: {
2973     // compare returning Int1Ty or vector of Int1Ty
2974     Code = bitc::FUNC_CODE_INST_CMP2;
2975     pushValueAndType(I.getOperand(0), InstID, Vals);
2976     pushValue(I.getOperand(1), InstID, Vals);
2977     Vals.push_back(cast<CmpInst>(I).getPredicate());
2978     uint64_t Flags = getOptimizationFlags(&I);
2979     if (Flags != 0)
2980       Vals.push_back(Flags);
2981     break;
2982   }
2983 
2984   case Instruction::Ret:
2985     {
2986       Code = bitc::FUNC_CODE_INST_RET;
2987       unsigned NumOperands = I.getNumOperands();
2988       if (NumOperands == 0)
2989         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2990       else if (NumOperands == 1) {
2991         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2992           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2993       } else {
2994         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2995           pushValueAndType(I.getOperand(i), InstID, Vals);
2996       }
2997     }
2998     break;
2999   case Instruction::Br:
3000     {
3001       Code = bitc::FUNC_CODE_INST_BR;
3002       const BranchInst &II = cast<BranchInst>(I);
3003       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
3004       if (II.isConditional()) {
3005         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
3006         pushValue(II.getCondition(), InstID, Vals);
3007       }
3008     }
3009     break;
3010   case Instruction::Switch:
3011     {
3012       Code = bitc::FUNC_CODE_INST_SWITCH;
3013       const SwitchInst &SI = cast<SwitchInst>(I);
3014       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
3015       pushValue(SI.getCondition(), InstID, Vals);
3016       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
3017       for (auto Case : SI.cases()) {
3018         Vals.push_back(VE.getValueID(Case.getCaseValue()));
3019         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
3020       }
3021     }
3022     break;
3023   case Instruction::IndirectBr:
3024     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
3025     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
3026     // Encode the address operand as relative, but not the basic blocks.
3027     pushValue(I.getOperand(0), InstID, Vals);
3028     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
3029       Vals.push_back(VE.getValueID(I.getOperand(i)));
3030     break;
3031 
3032   case Instruction::Invoke: {
3033     const InvokeInst *II = cast<InvokeInst>(&I);
3034     const Value *Callee = II->getCalledOperand();
3035     FunctionType *FTy = II->getFunctionType();
3036 
3037     if (II->hasOperandBundles())
3038       writeOperandBundles(*II, InstID);
3039 
3040     Code = bitc::FUNC_CODE_INST_INVOKE;
3041 
3042     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
3043     Vals.push_back(II->getCallingConv() | 1 << 13);
3044     Vals.push_back(VE.getValueID(II->getNormalDest()));
3045     Vals.push_back(VE.getValueID(II->getUnwindDest()));
3046     Vals.push_back(VE.getTypeID(FTy));
3047     pushValueAndType(Callee, InstID, Vals);
3048 
3049     // Emit value #'s for the fixed parameters.
3050     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
3051       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
3052 
3053     // Emit type/value pairs for varargs params.
3054     if (FTy->isVarArg()) {
3055       for (unsigned i = FTy->getNumParams(), e = II->arg_size(); i != e; ++i)
3056         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
3057     }
3058     break;
3059   }
3060   case Instruction::Resume:
3061     Code = bitc::FUNC_CODE_INST_RESUME;
3062     pushValueAndType(I.getOperand(0), InstID, Vals);
3063     break;
3064   case Instruction::CleanupRet: {
3065     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
3066     const auto &CRI = cast<CleanupReturnInst>(I);
3067     pushValue(CRI.getCleanupPad(), InstID, Vals);
3068     if (CRI.hasUnwindDest())
3069       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
3070     break;
3071   }
3072   case Instruction::CatchRet: {
3073     Code = bitc::FUNC_CODE_INST_CATCHRET;
3074     const auto &CRI = cast<CatchReturnInst>(I);
3075     pushValue(CRI.getCatchPad(), InstID, Vals);
3076     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
3077     break;
3078   }
3079   case Instruction::CleanupPad:
3080   case Instruction::CatchPad: {
3081     const auto &FuncletPad = cast<FuncletPadInst>(I);
3082     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
3083                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
3084     pushValue(FuncletPad.getParentPad(), InstID, Vals);
3085 
3086     unsigned NumArgOperands = FuncletPad.arg_size();
3087     Vals.push_back(NumArgOperands);
3088     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
3089       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
3090     break;
3091   }
3092   case Instruction::CatchSwitch: {
3093     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
3094     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
3095 
3096     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
3097 
3098     unsigned NumHandlers = CatchSwitch.getNumHandlers();
3099     Vals.push_back(NumHandlers);
3100     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
3101       Vals.push_back(VE.getValueID(CatchPadBB));
3102 
3103     if (CatchSwitch.hasUnwindDest())
3104       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
3105     break;
3106   }
3107   case Instruction::CallBr: {
3108     const CallBrInst *CBI = cast<CallBrInst>(&I);
3109     const Value *Callee = CBI->getCalledOperand();
3110     FunctionType *FTy = CBI->getFunctionType();
3111 
3112     if (CBI->hasOperandBundles())
3113       writeOperandBundles(*CBI, InstID);
3114 
3115     Code = bitc::FUNC_CODE_INST_CALLBR;
3116 
3117     Vals.push_back(VE.getAttributeListID(CBI->getAttributes()));
3118 
3119     Vals.push_back(CBI->getCallingConv() << bitc::CALL_CCONV |
3120                    1 << bitc::CALL_EXPLICIT_TYPE);
3121 
3122     Vals.push_back(VE.getValueID(CBI->getDefaultDest()));
3123     Vals.push_back(CBI->getNumIndirectDests());
3124     for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
3125       Vals.push_back(VE.getValueID(CBI->getIndirectDest(i)));
3126 
3127     Vals.push_back(VE.getTypeID(FTy));
3128     pushValueAndType(Callee, InstID, Vals);
3129 
3130     // Emit value #'s for the fixed parameters.
3131     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
3132       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
3133 
3134     // Emit type/value pairs for varargs params.
3135     if (FTy->isVarArg()) {
3136       for (unsigned i = FTy->getNumParams(), e = CBI->arg_size(); i != e; ++i)
3137         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
3138     }
3139     break;
3140   }
3141   case Instruction::Unreachable:
3142     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
3143     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
3144     break;
3145 
3146   case Instruction::PHI: {
3147     const PHINode &PN = cast<PHINode>(I);
3148     Code = bitc::FUNC_CODE_INST_PHI;
3149     // With the newer instruction encoding, forward references could give
3150     // negative valued IDs.  This is most common for PHIs, so we use
3151     // signed VBRs.
3152     SmallVector<uint64_t, 128> Vals64;
3153     Vals64.push_back(VE.getTypeID(PN.getType()));
3154     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
3155       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
3156       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
3157     }
3158 
3159     uint64_t Flags = getOptimizationFlags(&I);
3160     if (Flags != 0)
3161       Vals64.push_back(Flags);
3162 
3163     // Emit a Vals64 vector and exit.
3164     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
3165     Vals64.clear();
3166     return;
3167   }
3168 
3169   case Instruction::LandingPad: {
3170     const LandingPadInst &LP = cast<LandingPadInst>(I);
3171     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
3172     Vals.push_back(VE.getTypeID(LP.getType()));
3173     Vals.push_back(LP.isCleanup());
3174     Vals.push_back(LP.getNumClauses());
3175     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
3176       if (LP.isCatch(I))
3177         Vals.push_back(LandingPadInst::Catch);
3178       else
3179         Vals.push_back(LandingPadInst::Filter);
3180       pushValueAndType(LP.getClause(I), InstID, Vals);
3181     }
3182     break;
3183   }
3184 
3185   case Instruction::Alloca: {
3186     Code = bitc::FUNC_CODE_INST_ALLOCA;
3187     const AllocaInst &AI = cast<AllocaInst>(I);
3188     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
3189     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
3190     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
3191     using APV = AllocaPackedValues;
3192     unsigned Record = 0;
3193     unsigned EncodedAlign = getEncodedAlign(AI.getAlign());
3194     Bitfield::set<APV::AlignLower>(
3195         Record, EncodedAlign & ((1 << APV::AlignLower::Bits) - 1));
3196     Bitfield::set<APV::AlignUpper>(Record,
3197                                    EncodedAlign >> APV::AlignLower::Bits);
3198     Bitfield::set<APV::UsedWithInAlloca>(Record, AI.isUsedWithInAlloca());
3199     Bitfield::set<APV::ExplicitType>(Record, true);
3200     Bitfield::set<APV::SwiftError>(Record, AI.isSwiftError());
3201     Vals.push_back(Record);
3202 
3203     unsigned AS = AI.getAddressSpace();
3204     if (AS != M.getDataLayout().getAllocaAddrSpace())
3205       Vals.push_back(AS);
3206     break;
3207   }
3208 
3209   case Instruction::Load:
3210     if (cast<LoadInst>(I).isAtomic()) {
3211       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
3212       pushValueAndType(I.getOperand(0), InstID, Vals);
3213     } else {
3214       Code = bitc::FUNC_CODE_INST_LOAD;
3215       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
3216         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
3217     }
3218     Vals.push_back(VE.getTypeID(I.getType()));
3219     Vals.push_back(getEncodedAlign(cast<LoadInst>(I).getAlign()));
3220     Vals.push_back(cast<LoadInst>(I).isVolatile());
3221     if (cast<LoadInst>(I).isAtomic()) {
3222       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
3223       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
3224     }
3225     break;
3226   case Instruction::Store:
3227     if (cast<StoreInst>(I).isAtomic())
3228       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
3229     else
3230       Code = bitc::FUNC_CODE_INST_STORE;
3231     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
3232     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
3233     Vals.push_back(getEncodedAlign(cast<StoreInst>(I).getAlign()));
3234     Vals.push_back(cast<StoreInst>(I).isVolatile());
3235     if (cast<StoreInst>(I).isAtomic()) {
3236       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
3237       Vals.push_back(
3238           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
3239     }
3240     break;
3241   case Instruction::AtomicCmpXchg:
3242     Code = bitc::FUNC_CODE_INST_CMPXCHG;
3243     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3244     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
3245     pushValue(I.getOperand(2), InstID, Vals);        // newval.
3246     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
3247     Vals.push_back(
3248         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
3249     Vals.push_back(
3250         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
3251     Vals.push_back(
3252         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
3253     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
3254     Vals.push_back(getEncodedAlign(cast<AtomicCmpXchgInst>(I).getAlign()));
3255     break;
3256   case Instruction::AtomicRMW:
3257     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
3258     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3259     pushValueAndType(I.getOperand(1), InstID, Vals); // valty + val
3260     Vals.push_back(
3261         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
3262     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
3263     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
3264     Vals.push_back(
3265         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
3266     Vals.push_back(getEncodedAlign(cast<AtomicRMWInst>(I).getAlign()));
3267     break;
3268   case Instruction::Fence:
3269     Code = bitc::FUNC_CODE_INST_FENCE;
3270     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
3271     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
3272     break;
3273   case Instruction::Call: {
3274     const CallInst &CI = cast<CallInst>(I);
3275     FunctionType *FTy = CI.getFunctionType();
3276 
3277     if (CI.hasOperandBundles())
3278       writeOperandBundles(CI, InstID);
3279 
3280     Code = bitc::FUNC_CODE_INST_CALL;
3281 
3282     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
3283 
3284     unsigned Flags = getOptimizationFlags(&I);
3285     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
3286                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
3287                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
3288                    1 << bitc::CALL_EXPLICIT_TYPE |
3289                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
3290                    unsigned(Flags != 0) << bitc::CALL_FMF);
3291     if (Flags != 0)
3292       Vals.push_back(Flags);
3293 
3294     Vals.push_back(VE.getTypeID(FTy));
3295     pushValueAndType(CI.getCalledOperand(), InstID, Vals); // Callee
3296 
3297     // Emit value #'s for the fixed parameters.
3298     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
3299       // Check for labels (can happen with asm labels).
3300       if (FTy->getParamType(i)->isLabelTy())
3301         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
3302       else
3303         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
3304     }
3305 
3306     // Emit type/value pairs for varargs params.
3307     if (FTy->isVarArg()) {
3308       for (unsigned i = FTy->getNumParams(), e = CI.arg_size(); i != e; ++i)
3309         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
3310     }
3311     break;
3312   }
3313   case Instruction::VAArg:
3314     Code = bitc::FUNC_CODE_INST_VAARG;
3315     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
3316     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
3317     Vals.push_back(VE.getTypeID(I.getType())); // restype.
3318     break;
3319   case Instruction::Freeze:
3320     Code = bitc::FUNC_CODE_INST_FREEZE;
3321     pushValueAndType(I.getOperand(0), InstID, Vals);
3322     break;
3323   }
3324 
3325   Stream.EmitRecord(Code, Vals, AbbrevToUse);
3326   Vals.clear();
3327 }
3328 
3329 /// Write a GlobalValue VST to the module. The purpose of this data structure is
3330 /// to allow clients to efficiently find the function body.
3331 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
3332   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3333   // Get the offset of the VST we are writing, and backpatch it into
3334   // the VST forward declaration record.
3335   uint64_t VSTOffset = Stream.GetCurrentBitNo();
3336   // The BitcodeStartBit was the stream offset of the identification block.
3337   VSTOffset -= bitcodeStartBit();
3338   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
3339   // Note that we add 1 here because the offset is relative to one word
3340   // before the start of the identification block, which was historically
3341   // always the start of the regular bitcode header.
3342   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
3343 
3344   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3345 
3346   auto Abbv = std::make_shared<BitCodeAbbrev>();
3347   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
3348   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
3349   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
3350   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3351 
3352   for (const Function &F : M) {
3353     uint64_t Record[2];
3354 
3355     if (F.isDeclaration())
3356       continue;
3357 
3358     Record[0] = VE.getValueID(&F);
3359 
3360     // Save the word offset of the function (from the start of the
3361     // actual bitcode written to the stream).
3362     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
3363     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
3364     // Note that we add 1 here because the offset is relative to one word
3365     // before the start of the identification block, which was historically
3366     // always the start of the regular bitcode header.
3367     Record[1] = BitcodeIndex / 32 + 1;
3368 
3369     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
3370   }
3371 
3372   Stream.ExitBlock();
3373 }
3374 
3375 /// Emit names for arguments, instructions and basic blocks in a function.
3376 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
3377     const ValueSymbolTable &VST) {
3378   if (VST.empty())
3379     return;
3380 
3381   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3382 
3383   // FIXME: Set up the abbrev, we know how many values there are!
3384   // FIXME: We know if the type names can use 7-bit ascii.
3385   SmallVector<uint64_t, 64> NameVals;
3386 
3387   for (const ValueName &Name : VST) {
3388     // Figure out the encoding to use for the name.
3389     StringEncoding Bits = getStringEncoding(Name.getKey());
3390 
3391     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
3392     NameVals.push_back(VE.getValueID(Name.getValue()));
3393 
3394     // VST_CODE_ENTRY:   [valueid, namechar x N]
3395     // VST_CODE_BBENTRY: [bbid, namechar x N]
3396     unsigned Code;
3397     if (isa<BasicBlock>(Name.getValue())) {
3398       Code = bitc::VST_CODE_BBENTRY;
3399       if (Bits == SE_Char6)
3400         AbbrevToUse = VST_BBENTRY_6_ABBREV;
3401     } else {
3402       Code = bitc::VST_CODE_ENTRY;
3403       if (Bits == SE_Char6)
3404         AbbrevToUse = VST_ENTRY_6_ABBREV;
3405       else if (Bits == SE_Fixed7)
3406         AbbrevToUse = VST_ENTRY_7_ABBREV;
3407     }
3408 
3409     for (const auto P : Name.getKey())
3410       NameVals.push_back((unsigned char)P);
3411 
3412     // Emit the finished record.
3413     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
3414     NameVals.clear();
3415   }
3416 
3417   Stream.ExitBlock();
3418 }
3419 
3420 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3421   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3422   unsigned Code;
3423   if (isa<BasicBlock>(Order.V))
3424     Code = bitc::USELIST_CODE_BB;
3425   else
3426     Code = bitc::USELIST_CODE_DEFAULT;
3427 
3428   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3429   Record.push_back(VE.getValueID(Order.V));
3430   Stream.EmitRecord(Code, Record);
3431 }
3432 
3433 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3434   assert(VE.shouldPreserveUseListOrder() &&
3435          "Expected to be preserving use-list order");
3436 
3437   auto hasMore = [&]() {
3438     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3439   };
3440   if (!hasMore())
3441     // Nothing to do.
3442     return;
3443 
3444   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3445   while (hasMore()) {
3446     writeUseList(std::move(VE.UseListOrders.back()));
3447     VE.UseListOrders.pop_back();
3448   }
3449   Stream.ExitBlock();
3450 }
3451 
3452 /// Emit a function body to the module stream.
3453 void ModuleBitcodeWriter::writeFunction(
3454     const Function &F,
3455     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3456   // Save the bitcode index of the start of this function block for recording
3457   // in the VST.
3458   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3459 
3460   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3461   VE.incorporateFunction(F);
3462 
3463   SmallVector<unsigned, 64> Vals;
3464 
3465   // Emit the number of basic blocks, so the reader can create them ahead of
3466   // time.
3467   Vals.push_back(VE.getBasicBlocks().size());
3468   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3469   Vals.clear();
3470 
3471   // If there are function-local constants, emit them now.
3472   unsigned CstStart, CstEnd;
3473   VE.getFunctionConstantRange(CstStart, CstEnd);
3474   writeConstants(CstStart, CstEnd, false);
3475 
3476   // If there is function-local metadata, emit it now.
3477   writeFunctionMetadata(F);
3478 
3479   // Keep a running idea of what the instruction ID is.
3480   unsigned InstID = CstEnd;
3481 
3482   bool NeedsMetadataAttachment = F.hasMetadata();
3483 
3484   DILocation *LastDL = nullptr;
3485   SmallSetVector<Function *, 4> BlockAddressUsers;
3486 
3487   // Finally, emit all the instructions, in order.
3488   for (const BasicBlock &BB : F) {
3489     for (const Instruction &I : BB) {
3490       writeInstruction(I, InstID, Vals);
3491 
3492       if (!I.getType()->isVoidTy())
3493         ++InstID;
3494 
3495       // If the instruction has metadata, write a metadata attachment later.
3496       NeedsMetadataAttachment |= I.hasMetadataOtherThanDebugLoc();
3497 
3498       // If the instruction has a debug location, emit it.
3499       DILocation *DL = I.getDebugLoc();
3500       if (!DL)
3501         continue;
3502 
3503       if (DL == LastDL) {
3504         // Just repeat the same debug loc as last time.
3505         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3506         continue;
3507       }
3508 
3509       Vals.push_back(DL->getLine());
3510       Vals.push_back(DL->getColumn());
3511       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3512       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3513       Vals.push_back(DL->isImplicitCode());
3514       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3515       Vals.clear();
3516 
3517       LastDL = DL;
3518     }
3519 
3520     if (BlockAddress *BA = BlockAddress::lookup(&BB)) {
3521       SmallVector<Value *> Worklist{BA};
3522       SmallPtrSet<Value *, 8> Visited{BA};
3523       while (!Worklist.empty()) {
3524         Value *V = Worklist.pop_back_val();
3525         for (User *U : V->users()) {
3526           if (auto *I = dyn_cast<Instruction>(U)) {
3527             Function *P = I->getFunction();
3528             if (P != &F)
3529               BlockAddressUsers.insert(P);
3530           } else if (isa<Constant>(U) && !isa<GlobalValue>(U) &&
3531                      Visited.insert(U).second)
3532             Worklist.push_back(U);
3533         }
3534       }
3535     }
3536   }
3537 
3538   if (!BlockAddressUsers.empty()) {
3539     Vals.resize(BlockAddressUsers.size());
3540     for (auto I : llvm::enumerate(BlockAddressUsers))
3541       Vals[I.index()] = VE.getValueID(I.value());
3542     Stream.EmitRecord(bitc::FUNC_CODE_BLOCKADDR_USERS, Vals);
3543     Vals.clear();
3544   }
3545 
3546   // Emit names for all the instructions etc.
3547   if (auto *Symtab = F.getValueSymbolTable())
3548     writeFunctionLevelValueSymbolTable(*Symtab);
3549 
3550   if (NeedsMetadataAttachment)
3551     writeFunctionMetadataAttachment(F);
3552   if (VE.shouldPreserveUseListOrder())
3553     writeUseListBlock(&F);
3554   VE.purgeFunction();
3555   Stream.ExitBlock();
3556 }
3557 
3558 // Emit blockinfo, which defines the standard abbreviations etc.
3559 void ModuleBitcodeWriter::writeBlockInfo() {
3560   // We only want to emit block info records for blocks that have multiple
3561   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3562   // Other blocks can define their abbrevs inline.
3563   Stream.EnterBlockInfoBlock();
3564 
3565   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3566     auto Abbv = std::make_shared<BitCodeAbbrev>();
3567     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3568     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3569     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3570     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3571     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3572         VST_ENTRY_8_ABBREV)
3573       llvm_unreachable("Unexpected abbrev ordering!");
3574   }
3575 
3576   { // 7-bit fixed width VST_CODE_ENTRY strings.
3577     auto Abbv = std::make_shared<BitCodeAbbrev>();
3578     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3579     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3580     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3581     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3582     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3583         VST_ENTRY_7_ABBREV)
3584       llvm_unreachable("Unexpected abbrev ordering!");
3585   }
3586   { // 6-bit char6 VST_CODE_ENTRY strings.
3587     auto Abbv = std::make_shared<BitCodeAbbrev>();
3588     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3589     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3590     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3591     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3592     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3593         VST_ENTRY_6_ABBREV)
3594       llvm_unreachable("Unexpected abbrev ordering!");
3595   }
3596   { // 6-bit char6 VST_CODE_BBENTRY strings.
3597     auto Abbv = std::make_shared<BitCodeAbbrev>();
3598     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3599     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3600     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3601     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3602     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3603         VST_BBENTRY_6_ABBREV)
3604       llvm_unreachable("Unexpected abbrev ordering!");
3605   }
3606 
3607   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3608     auto Abbv = std::make_shared<BitCodeAbbrev>();
3609     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3610     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3611                               VE.computeBitsRequiredForTypeIndicies()));
3612     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3613         CONSTANTS_SETTYPE_ABBREV)
3614       llvm_unreachable("Unexpected abbrev ordering!");
3615   }
3616 
3617   { // INTEGER abbrev for CONSTANTS_BLOCK.
3618     auto Abbv = std::make_shared<BitCodeAbbrev>();
3619     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3620     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3621     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3622         CONSTANTS_INTEGER_ABBREV)
3623       llvm_unreachable("Unexpected abbrev ordering!");
3624   }
3625 
3626   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3627     auto Abbv = std::make_shared<BitCodeAbbrev>();
3628     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3629     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3630     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3631                               VE.computeBitsRequiredForTypeIndicies()));
3632     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3633 
3634     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3635         CONSTANTS_CE_CAST_Abbrev)
3636       llvm_unreachable("Unexpected abbrev ordering!");
3637   }
3638   { // NULL abbrev for CONSTANTS_BLOCK.
3639     auto Abbv = std::make_shared<BitCodeAbbrev>();
3640     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3641     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3642         CONSTANTS_NULL_Abbrev)
3643       llvm_unreachable("Unexpected abbrev ordering!");
3644   }
3645 
3646   // FIXME: This should only use space for first class types!
3647 
3648   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3649     auto Abbv = std::make_shared<BitCodeAbbrev>();
3650     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3651     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3652     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3653                               VE.computeBitsRequiredForTypeIndicies()));
3654     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3655     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3656     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3657         FUNCTION_INST_LOAD_ABBREV)
3658       llvm_unreachable("Unexpected abbrev ordering!");
3659   }
3660   { // INST_UNOP abbrev for FUNCTION_BLOCK.
3661     auto Abbv = std::make_shared<BitCodeAbbrev>();
3662     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3663     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3664     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3665     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3666         FUNCTION_INST_UNOP_ABBREV)
3667       llvm_unreachable("Unexpected abbrev ordering!");
3668   }
3669   { // INST_UNOP_FLAGS abbrev for FUNCTION_BLOCK.
3670     auto Abbv = std::make_shared<BitCodeAbbrev>();
3671     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3672     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3673     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3674     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3675     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3676         FUNCTION_INST_UNOP_FLAGS_ABBREV)
3677       llvm_unreachable("Unexpected abbrev ordering!");
3678   }
3679   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3680     auto Abbv = std::make_shared<BitCodeAbbrev>();
3681     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3682     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3683     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3684     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3685     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3686         FUNCTION_INST_BINOP_ABBREV)
3687       llvm_unreachable("Unexpected abbrev ordering!");
3688   }
3689   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3690     auto Abbv = std::make_shared<BitCodeAbbrev>();
3691     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3692     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3693     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3694     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3695     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3696     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3697         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3698       llvm_unreachable("Unexpected abbrev ordering!");
3699   }
3700   { // INST_CAST abbrev for FUNCTION_BLOCK.
3701     auto Abbv = std::make_shared<BitCodeAbbrev>();
3702     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3703     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3704     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3705                               VE.computeBitsRequiredForTypeIndicies()));
3706     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3707     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3708         FUNCTION_INST_CAST_ABBREV)
3709       llvm_unreachable("Unexpected abbrev ordering!");
3710   }
3711   { // INST_CAST_FLAGS abbrev for FUNCTION_BLOCK.
3712     auto Abbv = std::make_shared<BitCodeAbbrev>();
3713     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3714     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // OpVal
3715     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3716                               VE.computeBitsRequiredForTypeIndicies()));
3717     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3718     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3719     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3720         FUNCTION_INST_CAST_FLAGS_ABBREV)
3721       llvm_unreachable("Unexpected abbrev ordering!");
3722   }
3723 
3724   { // INST_RET abbrev for FUNCTION_BLOCK.
3725     auto Abbv = std::make_shared<BitCodeAbbrev>();
3726     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3727     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3728         FUNCTION_INST_RET_VOID_ABBREV)
3729       llvm_unreachable("Unexpected abbrev ordering!");
3730   }
3731   { // INST_RET abbrev for FUNCTION_BLOCK.
3732     auto Abbv = std::make_shared<BitCodeAbbrev>();
3733     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3734     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3735     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3736         FUNCTION_INST_RET_VAL_ABBREV)
3737       llvm_unreachable("Unexpected abbrev ordering!");
3738   }
3739   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3740     auto Abbv = std::make_shared<BitCodeAbbrev>();
3741     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3742     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3743         FUNCTION_INST_UNREACHABLE_ABBREV)
3744       llvm_unreachable("Unexpected abbrev ordering!");
3745   }
3746   {
3747     auto Abbv = std::make_shared<BitCodeAbbrev>();
3748     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3749     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3750     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3751                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3752     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3753     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3754     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3755         FUNCTION_INST_GEP_ABBREV)
3756       llvm_unreachable("Unexpected abbrev ordering!");
3757   }
3758 
3759   Stream.ExitBlock();
3760 }
3761 
3762 /// Write the module path strings, currently only used when generating
3763 /// a combined index file.
3764 void IndexBitcodeWriter::writeModStrings() {
3765   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3766 
3767   // TODO: See which abbrev sizes we actually need to emit
3768 
3769   // 8-bit fixed-width MST_ENTRY strings.
3770   auto Abbv = std::make_shared<BitCodeAbbrev>();
3771   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3772   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3773   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3774   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3775   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3776 
3777   // 7-bit fixed width MST_ENTRY strings.
3778   Abbv = std::make_shared<BitCodeAbbrev>();
3779   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3780   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3781   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3782   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3783   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3784 
3785   // 6-bit char6 MST_ENTRY strings.
3786   Abbv = std::make_shared<BitCodeAbbrev>();
3787   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3788   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3789   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3790   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3791   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3792 
3793   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3794   Abbv = std::make_shared<BitCodeAbbrev>();
3795   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3796   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3797   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3798   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3799   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3800   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3801   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3802 
3803   SmallVector<unsigned, 64> Vals;
3804   forEachModule([&](const StringMapEntry<ModuleHash> &MPSE) {
3805     StringRef Key = MPSE.getKey();
3806     const auto &Hash = MPSE.getValue();
3807     StringEncoding Bits = getStringEncoding(Key);
3808     unsigned AbbrevToUse = Abbrev8Bit;
3809     if (Bits == SE_Char6)
3810       AbbrevToUse = Abbrev6Bit;
3811     else if (Bits == SE_Fixed7)
3812       AbbrevToUse = Abbrev7Bit;
3813 
3814     auto ModuleId = ModuleIdMap.size();
3815     ModuleIdMap[Key] = ModuleId;
3816     Vals.push_back(ModuleId);
3817     Vals.append(Key.begin(), Key.end());
3818 
3819     // Emit the finished record.
3820     Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3821 
3822     // Emit an optional hash for the module now
3823     if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3824       Vals.assign(Hash.begin(), Hash.end());
3825       // Emit the hash record.
3826       Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3827     }
3828 
3829     Vals.clear();
3830   });
3831   Stream.ExitBlock();
3832 }
3833 
3834 /// Write the function type metadata related records that need to appear before
3835 /// a function summary entry (whether per-module or combined).
3836 template <typename Fn>
3837 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3838                                              FunctionSummary *FS,
3839                                              Fn GetValueID) {
3840   if (!FS->type_tests().empty())
3841     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3842 
3843   SmallVector<uint64_t, 64> Record;
3844 
3845   auto WriteVFuncIdVec = [&](uint64_t Ty,
3846                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3847     if (VFs.empty())
3848       return;
3849     Record.clear();
3850     for (auto &VF : VFs) {
3851       Record.push_back(VF.GUID);
3852       Record.push_back(VF.Offset);
3853     }
3854     Stream.EmitRecord(Ty, Record);
3855   };
3856 
3857   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3858                   FS->type_test_assume_vcalls());
3859   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3860                   FS->type_checked_load_vcalls());
3861 
3862   auto WriteConstVCallVec = [&](uint64_t Ty,
3863                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3864     for (auto &VC : VCs) {
3865       Record.clear();
3866       Record.push_back(VC.VFunc.GUID);
3867       Record.push_back(VC.VFunc.Offset);
3868       llvm::append_range(Record, VC.Args);
3869       Stream.EmitRecord(Ty, Record);
3870     }
3871   };
3872 
3873   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3874                      FS->type_test_assume_const_vcalls());
3875   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3876                      FS->type_checked_load_const_vcalls());
3877 
3878   auto WriteRange = [&](ConstantRange Range) {
3879     Range = Range.sextOrTrunc(FunctionSummary::ParamAccess::RangeWidth);
3880     assert(Range.getLower().getNumWords() == 1);
3881     assert(Range.getUpper().getNumWords() == 1);
3882     emitSignedInt64(Record, *Range.getLower().getRawData());
3883     emitSignedInt64(Record, *Range.getUpper().getRawData());
3884   };
3885 
3886   if (!FS->paramAccesses().empty()) {
3887     Record.clear();
3888     for (auto &Arg : FS->paramAccesses()) {
3889       size_t UndoSize = Record.size();
3890       Record.push_back(Arg.ParamNo);
3891       WriteRange(Arg.Use);
3892       Record.push_back(Arg.Calls.size());
3893       for (auto &Call : Arg.Calls) {
3894         Record.push_back(Call.ParamNo);
3895         std::optional<unsigned> ValueID = GetValueID(Call.Callee);
3896         if (!ValueID) {
3897           // If ValueID is unknown we can't drop just this call, we must drop
3898           // entire parameter.
3899           Record.resize(UndoSize);
3900           break;
3901         }
3902         Record.push_back(*ValueID);
3903         WriteRange(Call.Offsets);
3904       }
3905     }
3906     if (!Record.empty())
3907       Stream.EmitRecord(bitc::FS_PARAM_ACCESS, Record);
3908   }
3909 }
3910 
3911 /// Collect type IDs from type tests used by function.
3912 static void
3913 getReferencedTypeIds(FunctionSummary *FS,
3914                      std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3915   if (!FS->type_tests().empty())
3916     for (auto &TT : FS->type_tests())
3917       ReferencedTypeIds.insert(TT);
3918 
3919   auto GetReferencedTypesFromVFuncIdVec =
3920       [&](ArrayRef<FunctionSummary::VFuncId> VFs) {
3921         for (auto &VF : VFs)
3922           ReferencedTypeIds.insert(VF.GUID);
3923       };
3924 
3925   GetReferencedTypesFromVFuncIdVec(FS->type_test_assume_vcalls());
3926   GetReferencedTypesFromVFuncIdVec(FS->type_checked_load_vcalls());
3927 
3928   auto GetReferencedTypesFromConstVCallVec =
3929       [&](ArrayRef<FunctionSummary::ConstVCall> VCs) {
3930         for (auto &VC : VCs)
3931           ReferencedTypeIds.insert(VC.VFunc.GUID);
3932       };
3933 
3934   GetReferencedTypesFromConstVCallVec(FS->type_test_assume_const_vcalls());
3935   GetReferencedTypesFromConstVCallVec(FS->type_checked_load_const_vcalls());
3936 }
3937 
3938 static void writeWholeProgramDevirtResolutionByArg(
3939     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3940     const WholeProgramDevirtResolution::ByArg &ByArg) {
3941   NameVals.push_back(args.size());
3942   llvm::append_range(NameVals, args);
3943 
3944   NameVals.push_back(ByArg.TheKind);
3945   NameVals.push_back(ByArg.Info);
3946   NameVals.push_back(ByArg.Byte);
3947   NameVals.push_back(ByArg.Bit);
3948 }
3949 
3950 static void writeWholeProgramDevirtResolution(
3951     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3952     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3953   NameVals.push_back(Id);
3954 
3955   NameVals.push_back(Wpd.TheKind);
3956   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3957   NameVals.push_back(Wpd.SingleImplName.size());
3958 
3959   NameVals.push_back(Wpd.ResByArg.size());
3960   for (auto &A : Wpd.ResByArg)
3961     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3962 }
3963 
3964 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3965                                      StringTableBuilder &StrtabBuilder,
3966                                      const std::string &Id,
3967                                      const TypeIdSummary &Summary) {
3968   NameVals.push_back(StrtabBuilder.add(Id));
3969   NameVals.push_back(Id.size());
3970 
3971   NameVals.push_back(Summary.TTRes.TheKind);
3972   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3973   NameVals.push_back(Summary.TTRes.AlignLog2);
3974   NameVals.push_back(Summary.TTRes.SizeM1);
3975   NameVals.push_back(Summary.TTRes.BitMask);
3976   NameVals.push_back(Summary.TTRes.InlineBits);
3977 
3978   for (auto &W : Summary.WPDRes)
3979     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3980                                       W.second);
3981 }
3982 
3983 static void writeTypeIdCompatibleVtableSummaryRecord(
3984     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3985     const std::string &Id, const TypeIdCompatibleVtableInfo &Summary,
3986     ValueEnumerator &VE) {
3987   NameVals.push_back(StrtabBuilder.add(Id));
3988   NameVals.push_back(Id.size());
3989 
3990   for (auto &P : Summary) {
3991     NameVals.push_back(P.AddressPointOffset);
3992     NameVals.push_back(VE.getValueID(P.VTableVI.getValue()));
3993   }
3994 }
3995 
3996 static void writeFunctionHeapProfileRecords(
3997     BitstreamWriter &Stream, FunctionSummary *FS, unsigned CallsiteAbbrev,
3998     unsigned AllocAbbrev, bool PerModule,
3999     std::function<unsigned(const ValueInfo &VI)> GetValueID,
4000     std::function<unsigned(unsigned)> GetStackIndex) {
4001   SmallVector<uint64_t> Record;
4002 
4003   for (auto &CI : FS->callsites()) {
4004     Record.clear();
4005     // Per module callsite clones should always have a single entry of
4006     // value 0.
4007     assert(!PerModule || (CI.Clones.size() == 1 && CI.Clones[0] == 0));
4008     Record.push_back(GetValueID(CI.Callee));
4009     if (!PerModule) {
4010       Record.push_back(CI.StackIdIndices.size());
4011       Record.push_back(CI.Clones.size());
4012     }
4013     for (auto Id : CI.StackIdIndices)
4014       Record.push_back(GetStackIndex(Id));
4015     if (!PerModule) {
4016       for (auto V : CI.Clones)
4017         Record.push_back(V);
4018     }
4019     Stream.EmitRecord(PerModule ? bitc::FS_PERMODULE_CALLSITE_INFO
4020                                 : bitc::FS_COMBINED_CALLSITE_INFO,
4021                       Record, CallsiteAbbrev);
4022   }
4023 
4024   for (auto &AI : FS->allocs()) {
4025     Record.clear();
4026     // Per module alloc versions should always have a single entry of
4027     // value 0.
4028     assert(!PerModule || (AI.Versions.size() == 1 && AI.Versions[0] == 0));
4029     if (!PerModule) {
4030       Record.push_back(AI.MIBs.size());
4031       Record.push_back(AI.Versions.size());
4032     }
4033     for (auto &MIB : AI.MIBs) {
4034       Record.push_back((uint8_t)MIB.AllocType);
4035       Record.push_back(MIB.StackIdIndices.size());
4036       for (auto Id : MIB.StackIdIndices)
4037         Record.push_back(GetStackIndex(Id));
4038     }
4039     if (!PerModule) {
4040       for (auto V : AI.Versions)
4041         Record.push_back(V);
4042     }
4043     Stream.EmitRecord(PerModule ? bitc::FS_PERMODULE_ALLOC_INFO
4044                                 : bitc::FS_COMBINED_ALLOC_INFO,
4045                       Record, AllocAbbrev);
4046   }
4047 }
4048 
4049 // Helper to emit a single function summary record.
4050 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
4051     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
4052     unsigned ValueID, unsigned FSCallsRelBFAbbrev,
4053     unsigned FSCallsProfileAbbrev, unsigned CallsiteAbbrev,
4054     unsigned AllocAbbrev, const Function &F) {
4055   NameVals.push_back(ValueID);
4056 
4057   FunctionSummary *FS = cast<FunctionSummary>(Summary);
4058 
4059   writeFunctionTypeMetadataRecords(
4060       Stream, FS, [&](const ValueInfo &VI) -> std::optional<unsigned> {
4061         return {VE.getValueID(VI.getValue())};
4062       });
4063 
4064   writeFunctionHeapProfileRecords(
4065       Stream, FS, CallsiteAbbrev, AllocAbbrev,
4066       /*PerModule*/ true,
4067       /*GetValueId*/ [&](const ValueInfo &VI) { return getValueId(VI); },
4068       /*GetStackIndex*/ [&](unsigned I) { return I; });
4069 
4070   auto SpecialRefCnts = FS->specialRefCounts();
4071   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
4072   NameVals.push_back(FS->instCount());
4073   NameVals.push_back(getEncodedFFlags(FS->fflags()));
4074   NameVals.push_back(FS->refs().size());
4075   NameVals.push_back(SpecialRefCnts.first);  // rorefcnt
4076   NameVals.push_back(SpecialRefCnts.second); // worefcnt
4077 
4078   for (auto &RI : FS->refs())
4079     NameVals.push_back(VE.getValueID(RI.getValue()));
4080 
4081   const bool UseRelBFRecord =
4082       WriteRelBFToSummary && !F.hasProfileData() &&
4083       ForceSummaryEdgesCold == FunctionSummary::FSHT_None;
4084   for (auto &ECI : FS->calls()) {
4085     NameVals.push_back(getValueId(ECI.first));
4086     if (UseRelBFRecord)
4087       NameVals.push_back(getEncodedRelBFCallEdgeInfo(ECI.second));
4088     else
4089       NameVals.push_back(getEncodedHotnessCallEdgeInfo(ECI.second));
4090   }
4091 
4092   unsigned FSAbbrev =
4093       (UseRelBFRecord ? FSCallsRelBFAbbrev : FSCallsProfileAbbrev);
4094   unsigned Code =
4095       (UseRelBFRecord ? bitc::FS_PERMODULE_RELBF : bitc::FS_PERMODULE_PROFILE);
4096 
4097   // Emit the finished record.
4098   Stream.EmitRecord(Code, NameVals, FSAbbrev);
4099   NameVals.clear();
4100 }
4101 
4102 // Collect the global value references in the given variable's initializer,
4103 // and emit them in a summary record.
4104 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
4105     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
4106     unsigned FSModRefsAbbrev, unsigned FSModVTableRefsAbbrev) {
4107   auto VI = Index->getValueInfo(V.getGUID());
4108   if (!VI || VI.getSummaryList().empty()) {
4109     // Only declarations should not have a summary (a declaration might however
4110     // have a summary if the def was in module level asm).
4111     assert(V.isDeclaration());
4112     return;
4113   }
4114   auto *Summary = VI.getSummaryList()[0].get();
4115   NameVals.push_back(VE.getValueID(&V));
4116   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
4117   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
4118   NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
4119 
4120   auto VTableFuncs = VS->vTableFuncs();
4121   if (!VTableFuncs.empty())
4122     NameVals.push_back(VS->refs().size());
4123 
4124   unsigned SizeBeforeRefs = NameVals.size();
4125   for (auto &RI : VS->refs())
4126     NameVals.push_back(VE.getValueID(RI.getValue()));
4127   // Sort the refs for determinism output, the vector returned by FS->refs() has
4128   // been initialized from a DenseSet.
4129   llvm::sort(drop_begin(NameVals, SizeBeforeRefs));
4130 
4131   if (VTableFuncs.empty())
4132     Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
4133                       FSModRefsAbbrev);
4134   else {
4135     // VTableFuncs pairs should already be sorted by offset.
4136     for (auto &P : VTableFuncs) {
4137       NameVals.push_back(VE.getValueID(P.FuncVI.getValue()));
4138       NameVals.push_back(P.VTableOffset);
4139     }
4140 
4141     Stream.EmitRecord(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS, NameVals,
4142                       FSModVTableRefsAbbrev);
4143   }
4144   NameVals.clear();
4145 }
4146 
4147 /// Emit the per-module summary section alongside the rest of
4148 /// the module's bitcode.
4149 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
4150   // By default we compile with ThinLTO if the module has a summary, but the
4151   // client can request full LTO with a module flag.
4152   bool IsThinLTO = true;
4153   if (auto *MD =
4154           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
4155     IsThinLTO = MD->getZExtValue();
4156   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
4157                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
4158                        4);
4159 
4160   Stream.EmitRecord(
4161       bitc::FS_VERSION,
4162       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
4163 
4164   // Write the index flags.
4165   uint64_t Flags = 0;
4166   // Bits 1-3 are set only in the combined index, skip them.
4167   if (Index->enableSplitLTOUnit())
4168     Flags |= 0x8;
4169   if (Index->hasUnifiedLTO())
4170     Flags |= 0x200;
4171 
4172   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
4173 
4174   if (Index->begin() == Index->end()) {
4175     Stream.ExitBlock();
4176     return;
4177   }
4178 
4179   for (const auto &GVI : valueIds()) {
4180     Stream.EmitRecord(bitc::FS_VALUE_GUID,
4181                       ArrayRef<uint64_t>{GVI.second, GVI.first});
4182   }
4183 
4184   if (!Index->stackIds().empty()) {
4185     auto StackIdAbbv = std::make_shared<BitCodeAbbrev>();
4186     StackIdAbbv->Add(BitCodeAbbrevOp(bitc::FS_STACK_IDS));
4187     // numids x stackid
4188     StackIdAbbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4189     StackIdAbbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4190     unsigned StackIdAbbvId = Stream.EmitAbbrev(std::move(StackIdAbbv));
4191     Stream.EmitRecord(bitc::FS_STACK_IDS, Index->stackIds(), StackIdAbbvId);
4192   }
4193 
4194   // Abbrev for FS_PERMODULE_PROFILE.
4195   auto Abbv = std::make_shared<BitCodeAbbrev>();
4196   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
4197   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4198   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // flags
4199   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4200   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4201   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4202   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4203   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4204   // numrefs x valueid, n x (valueid, hotness+tailcall flags)
4205   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4206   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4207   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4208 
4209   // Abbrev for FS_PERMODULE_RELBF.
4210   Abbv = std::make_shared<BitCodeAbbrev>();
4211   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
4212   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4213   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4214   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4215   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4216   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4217   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4218   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4219   // numrefs x valueid, n x (valueid, rel_block_freq+tailcall])
4220   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4221   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4222   unsigned FSCallsRelBFAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4223 
4224   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
4225   Abbv = std::make_shared<BitCodeAbbrev>();
4226   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
4227   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4228   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
4229   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
4230   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4231   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4232 
4233   // Abbrev for FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS.
4234   Abbv = std::make_shared<BitCodeAbbrev>();
4235   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS));
4236   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4237   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
4238   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numrefs
4239   // numrefs x valueid, n x (valueid , offset)
4240   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4241   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4242   unsigned FSModVTableRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4243 
4244   // Abbrev for FS_ALIAS.
4245   Abbv = std::make_shared<BitCodeAbbrev>();
4246   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
4247   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4248   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4249   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4250   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4251 
4252   // Abbrev for FS_TYPE_ID_METADATA
4253   Abbv = std::make_shared<BitCodeAbbrev>();
4254   Abbv->Add(BitCodeAbbrevOp(bitc::FS_TYPE_ID_METADATA));
4255   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid strtab index
4256   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid length
4257   // n x (valueid , offset)
4258   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4259   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4260   unsigned TypeIdCompatibleVtableAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4261 
4262   Abbv = std::make_shared<BitCodeAbbrev>();
4263   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_CALLSITE_INFO));
4264   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4265   // n x stackidindex
4266   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4267   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4268   unsigned CallsiteAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4269 
4270   Abbv = std::make_shared<BitCodeAbbrev>();
4271   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_ALLOC_INFO));
4272   // n x (alloc type, numstackids, numstackids x stackidindex)
4273   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4274   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4275   unsigned AllocAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4276 
4277   SmallVector<uint64_t, 64> NameVals;
4278   // Iterate over the list of functions instead of the Index to
4279   // ensure the ordering is stable.
4280   for (const Function &F : M) {
4281     // Summary emission does not support anonymous functions, they have to
4282     // renamed using the anonymous function renaming pass.
4283     if (!F.hasName())
4284       report_fatal_error("Unexpected anonymous function when writing summary");
4285 
4286     ValueInfo VI = Index->getValueInfo(F.getGUID());
4287     if (!VI || VI.getSummaryList().empty()) {
4288       // Only declarations should not have a summary (a declaration might
4289       // however have a summary if the def was in module level asm).
4290       assert(F.isDeclaration());
4291       continue;
4292     }
4293     auto *Summary = VI.getSummaryList()[0].get();
4294     writePerModuleFunctionSummaryRecord(
4295         NameVals, Summary, VE.getValueID(&F), FSCallsRelBFAbbrev,
4296         FSCallsProfileAbbrev, CallsiteAbbrev, AllocAbbrev, F);
4297   }
4298 
4299   // Capture references from GlobalVariable initializers, which are outside
4300   // of a function scope.
4301   for (const GlobalVariable &G : M.globals())
4302     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev,
4303                                FSModVTableRefsAbbrev);
4304 
4305   for (const GlobalAlias &A : M.aliases()) {
4306     auto *Aliasee = A.getAliaseeObject();
4307     // Skip ifunc and nameless functions which don't have an entry in the
4308     // summary.
4309     if (!Aliasee->hasName() || isa<GlobalIFunc>(Aliasee))
4310       continue;
4311     auto AliasId = VE.getValueID(&A);
4312     auto AliaseeId = VE.getValueID(Aliasee);
4313     NameVals.push_back(AliasId);
4314     auto *Summary = Index->getGlobalValueSummary(A);
4315     AliasSummary *AS = cast<AliasSummary>(Summary);
4316     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4317     NameVals.push_back(AliaseeId);
4318     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
4319     NameVals.clear();
4320   }
4321 
4322   for (auto &S : Index->typeIdCompatibleVtableMap()) {
4323     writeTypeIdCompatibleVtableSummaryRecord(NameVals, StrtabBuilder, S.first,
4324                                              S.second, VE);
4325     Stream.EmitRecord(bitc::FS_TYPE_ID_METADATA, NameVals,
4326                       TypeIdCompatibleVtableAbbrev);
4327     NameVals.clear();
4328   }
4329 
4330   if (Index->getBlockCount())
4331     Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
4332                       ArrayRef<uint64_t>{Index->getBlockCount()});
4333 
4334   Stream.ExitBlock();
4335 }
4336 
4337 /// Emit the combined summary section into the combined index file.
4338 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
4339   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 4);
4340   Stream.EmitRecord(
4341       bitc::FS_VERSION,
4342       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
4343 
4344   // Write the index flags.
4345   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Index.getFlags()});
4346 
4347   for (const auto &GVI : valueIds()) {
4348     Stream.EmitRecord(bitc::FS_VALUE_GUID,
4349                       ArrayRef<uint64_t>{GVI.second, GVI.first});
4350   }
4351 
4352   if (!StackIdIndices.empty()) {
4353     auto StackIdAbbv = std::make_shared<BitCodeAbbrev>();
4354     StackIdAbbv->Add(BitCodeAbbrevOp(bitc::FS_STACK_IDS));
4355     // numids x stackid
4356     StackIdAbbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4357     StackIdAbbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4358     unsigned StackIdAbbvId = Stream.EmitAbbrev(std::move(StackIdAbbv));
4359     // Write the stack ids used by this index, which will be a subset of those in
4360     // the full index in the case of distributed indexes.
4361     std::vector<uint64_t> StackIds;
4362     for (auto &I : StackIdIndices)
4363       StackIds.push_back(Index.getStackIdAtIndex(I));
4364     Stream.EmitRecord(bitc::FS_STACK_IDS, StackIds, StackIdAbbvId);
4365   }
4366 
4367   // Abbrev for FS_COMBINED_PROFILE.
4368   auto Abbv = std::make_shared<BitCodeAbbrev>();
4369   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
4370   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4374   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4375   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
4376   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4377   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4378   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4379   // numrefs x valueid, n x (valueid, hotness+tailcall flags)
4380   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4381   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4382   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4383 
4384   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
4385   Abbv = std::make_shared<BitCodeAbbrev>();
4386   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
4387   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4388   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4390   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
4391   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4392   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4393 
4394   // Abbrev for FS_COMBINED_ALIAS.
4395   Abbv = std::make_shared<BitCodeAbbrev>();
4396   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
4397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4399   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4400   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4401   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4402 
4403   Abbv = std::make_shared<BitCodeAbbrev>();
4404   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_CALLSITE_INFO));
4405   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
4406   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numstackindices
4407   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numver
4408   // numstackindices x stackidindex, numver x version
4409   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4410   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4411   unsigned CallsiteAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4412 
4413   Abbv = std::make_shared<BitCodeAbbrev>();
4414   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALLOC_INFO));
4415   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // nummib
4416   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numver
4417   // nummib x (alloc type, numstackids, numstackids x stackidindex),
4418   // numver x version
4419   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4420   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4421   unsigned AllocAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4422 
4423   // The aliases are emitted as a post-pass, and will point to the value
4424   // id of the aliasee. Save them in a vector for post-processing.
4425   SmallVector<AliasSummary *, 64> Aliases;
4426 
4427   // Save the value id for each summary for alias emission.
4428   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
4429 
4430   SmallVector<uint64_t, 64> NameVals;
4431 
4432   // Set that will be populated during call to writeFunctionTypeMetadataRecords
4433   // with the type ids referenced by this index file.
4434   std::set<GlobalValue::GUID> ReferencedTypeIds;
4435 
4436   // For local linkage, we also emit the original name separately
4437   // immediately after the record.
4438   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
4439     // We don't need to emit the original name if we are writing the index for
4440     // distributed backends (in which case ModuleToSummariesForIndex is
4441     // non-null). The original name is only needed during the thin link, since
4442     // for SamplePGO the indirect call targets for local functions have
4443     // have the original name annotated in profile.
4444     // Continue to emit it when writing out the entire combined index, which is
4445     // used in testing the thin link via llvm-lto.
4446     if (ModuleToSummariesForIndex || !GlobalValue::isLocalLinkage(S.linkage()))
4447       return;
4448     NameVals.push_back(S.getOriginalName());
4449     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
4450     NameVals.clear();
4451   };
4452 
4453   std::set<GlobalValue::GUID> DefOrUseGUIDs;
4454   forEachSummary([&](GVInfo I, bool IsAliasee) {
4455     GlobalValueSummary *S = I.second;
4456     assert(S);
4457     DefOrUseGUIDs.insert(I.first);
4458     for (const ValueInfo &VI : S->refs())
4459       DefOrUseGUIDs.insert(VI.getGUID());
4460 
4461     auto ValueId = getValueId(I.first);
4462     assert(ValueId);
4463     SummaryToValueIdMap[S] = *ValueId;
4464 
4465     // If this is invoked for an aliasee, we want to record the above
4466     // mapping, but then not emit a summary entry (if the aliasee is
4467     // to be imported, we will invoke this separately with IsAliasee=false).
4468     if (IsAliasee)
4469       return;
4470 
4471     if (auto *AS = dyn_cast<AliasSummary>(S)) {
4472       // Will process aliases as a post-pass because the reader wants all
4473       // global to be loaded first.
4474       Aliases.push_back(AS);
4475       return;
4476     }
4477 
4478     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
4479       NameVals.push_back(*ValueId);
4480       assert(ModuleIdMap.count(VS->modulePath()));
4481       NameVals.push_back(ModuleIdMap[VS->modulePath()]);
4482       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
4483       NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
4484       for (auto &RI : VS->refs()) {
4485         auto RefValueId = getValueId(RI.getGUID());
4486         if (!RefValueId)
4487           continue;
4488         NameVals.push_back(*RefValueId);
4489       }
4490 
4491       // Emit the finished record.
4492       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
4493                         FSModRefsAbbrev);
4494       NameVals.clear();
4495       MaybeEmitOriginalName(*S);
4496       return;
4497     }
4498 
4499     auto GetValueId = [&](const ValueInfo &VI) -> std::optional<unsigned> {
4500       if (!VI)
4501         return std::nullopt;
4502       return getValueId(VI.getGUID());
4503     };
4504 
4505     auto *FS = cast<FunctionSummary>(S);
4506     writeFunctionTypeMetadataRecords(Stream, FS, GetValueId);
4507     getReferencedTypeIds(FS, ReferencedTypeIds);
4508 
4509     writeFunctionHeapProfileRecords(
4510         Stream, FS, CallsiteAbbrev, AllocAbbrev,
4511         /*PerModule*/ false,
4512         /*GetValueId*/ [&](const ValueInfo &VI) -> unsigned {
4513           std::optional<unsigned> ValueID = GetValueId(VI);
4514           // This can happen in shared index files for distributed ThinLTO if
4515           // the callee function summary is not included. Record 0 which we
4516           // will have to deal with conservatively when doing any kind of
4517           // validation in the ThinLTO backends.
4518           if (!ValueID)
4519             return 0;
4520           return *ValueID;
4521         },
4522         /*GetStackIndex*/ [&](unsigned I) {
4523           // Get the corresponding index into the list of StackIdIndices
4524           // actually being written for this combined index (which may be a
4525           // subset in the case of distributed indexes).
4526           auto Lower = llvm::lower_bound(StackIdIndices, I);
4527           return std::distance(StackIdIndices.begin(), Lower);
4528         });
4529 
4530     NameVals.push_back(*ValueId);
4531     assert(ModuleIdMap.count(FS->modulePath()));
4532     NameVals.push_back(ModuleIdMap[FS->modulePath()]);
4533     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
4534     NameVals.push_back(FS->instCount());
4535     NameVals.push_back(getEncodedFFlags(FS->fflags()));
4536     NameVals.push_back(FS->entryCount());
4537 
4538     // Fill in below
4539     NameVals.push_back(0); // numrefs
4540     NameVals.push_back(0); // rorefcnt
4541     NameVals.push_back(0); // worefcnt
4542 
4543     unsigned Count = 0, RORefCnt = 0, WORefCnt = 0;
4544     for (auto &RI : FS->refs()) {
4545       auto RefValueId = getValueId(RI.getGUID());
4546       if (!RefValueId)
4547         continue;
4548       NameVals.push_back(*RefValueId);
4549       if (RI.isReadOnly())
4550         RORefCnt++;
4551       else if (RI.isWriteOnly())
4552         WORefCnt++;
4553       Count++;
4554     }
4555     NameVals[6] = Count;
4556     NameVals[7] = RORefCnt;
4557     NameVals[8] = WORefCnt;
4558 
4559     for (auto &EI : FS->calls()) {
4560       // If this GUID doesn't have a value id, it doesn't have a function
4561       // summary and we don't need to record any calls to it.
4562       std::optional<unsigned> CallValueId = GetValueId(EI.first);
4563       if (!CallValueId)
4564         continue;
4565       NameVals.push_back(*CallValueId);
4566       NameVals.push_back(getEncodedHotnessCallEdgeInfo(EI.second));
4567     }
4568 
4569     // Emit the finished record.
4570     Stream.EmitRecord(bitc::FS_COMBINED_PROFILE, NameVals,
4571                       FSCallsProfileAbbrev);
4572     NameVals.clear();
4573     MaybeEmitOriginalName(*S);
4574   });
4575 
4576   for (auto *AS : Aliases) {
4577     auto AliasValueId = SummaryToValueIdMap[AS];
4578     assert(AliasValueId);
4579     NameVals.push_back(AliasValueId);
4580     assert(ModuleIdMap.count(AS->modulePath()));
4581     NameVals.push_back(ModuleIdMap[AS->modulePath()]);
4582     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4583     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
4584     assert(AliaseeValueId);
4585     NameVals.push_back(AliaseeValueId);
4586 
4587     // Emit the finished record.
4588     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
4589     NameVals.clear();
4590     MaybeEmitOriginalName(*AS);
4591 
4592     if (auto *FS = dyn_cast<FunctionSummary>(&AS->getAliasee()))
4593       getReferencedTypeIds(FS, ReferencedTypeIds);
4594   }
4595 
4596   if (!Index.cfiFunctionDefs().empty()) {
4597     for (auto &S : Index.cfiFunctionDefs()) {
4598       if (DefOrUseGUIDs.count(
4599               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4600         NameVals.push_back(StrtabBuilder.add(S));
4601         NameVals.push_back(S.size());
4602       }
4603     }
4604     if (!NameVals.empty()) {
4605       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
4606       NameVals.clear();
4607     }
4608   }
4609 
4610   if (!Index.cfiFunctionDecls().empty()) {
4611     for (auto &S : Index.cfiFunctionDecls()) {
4612       if (DefOrUseGUIDs.count(
4613               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4614         NameVals.push_back(StrtabBuilder.add(S));
4615         NameVals.push_back(S.size());
4616       }
4617     }
4618     if (!NameVals.empty()) {
4619       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
4620       NameVals.clear();
4621     }
4622   }
4623 
4624   // Walk the GUIDs that were referenced, and write the
4625   // corresponding type id records.
4626   for (auto &T : ReferencedTypeIds) {
4627     auto TidIter = Index.typeIds().equal_range(T);
4628     for (auto It = TidIter.first; It != TidIter.second; ++It) {
4629       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, It->second.first,
4630                                It->second.second);
4631       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
4632       NameVals.clear();
4633     }
4634   }
4635 
4636   if (Index.getBlockCount())
4637     Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
4638                       ArrayRef<uint64_t>{Index.getBlockCount()});
4639 
4640   Stream.ExitBlock();
4641 }
4642 
4643 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
4644 /// current llvm version, and a record for the epoch number.
4645 static void writeIdentificationBlock(BitstreamWriter &Stream) {
4646   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
4647 
4648   // Write the "user readable" string identifying the bitcode producer
4649   auto Abbv = std::make_shared<BitCodeAbbrev>();
4650   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
4651   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4652   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
4653   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4654   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
4655                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
4656 
4657   // Write the epoch version
4658   Abbv = std::make_shared<BitCodeAbbrev>();
4659   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
4660   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
4661   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4662   constexpr std::array<unsigned, 1> Vals = {{bitc::BITCODE_CURRENT_EPOCH}};
4663   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
4664   Stream.ExitBlock();
4665 }
4666 
4667 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
4668   // Emit the module's hash.
4669   // MODULE_CODE_HASH: [5*i32]
4670   if (GenerateHash) {
4671     uint32_t Vals[5];
4672     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
4673                                     Buffer.size() - BlockStartPos));
4674     std::array<uint8_t, 20> Hash = Hasher.result();
4675     for (int Pos = 0; Pos < 20; Pos += 4) {
4676       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
4677     }
4678 
4679     // Emit the finished record.
4680     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
4681 
4682     if (ModHash)
4683       // Save the written hash value.
4684       llvm::copy(Vals, std::begin(*ModHash));
4685   }
4686 }
4687 
4688 void ModuleBitcodeWriter::write() {
4689   writeIdentificationBlock(Stream);
4690 
4691   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4692   size_t BlockStartPos = Buffer.size();
4693 
4694   writeModuleVersion();
4695 
4696   // Emit blockinfo, which defines the standard abbreviations etc.
4697   writeBlockInfo();
4698 
4699   // Emit information describing all of the types in the module.
4700   writeTypeTable();
4701 
4702   // Emit information about attribute groups.
4703   writeAttributeGroupTable();
4704 
4705   // Emit information about parameter attributes.
4706   writeAttributeTable();
4707 
4708   writeComdats();
4709 
4710   // Emit top-level description of module, including target triple, inline asm,
4711   // descriptors for global variables, and function prototype info.
4712   writeModuleInfo();
4713 
4714   // Emit constants.
4715   writeModuleConstants();
4716 
4717   // Emit metadata kind names.
4718   writeModuleMetadataKinds();
4719 
4720   // Emit metadata.
4721   writeModuleMetadata();
4722 
4723   // Emit module-level use-lists.
4724   if (VE.shouldPreserveUseListOrder())
4725     writeUseListBlock(nullptr);
4726 
4727   writeOperandBundleTags();
4728   writeSyncScopeNames();
4729 
4730   // Emit function bodies.
4731   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
4732   for (const Function &F : M)
4733     if (!F.isDeclaration())
4734       writeFunction(F, FunctionToBitcodeIndex);
4735 
4736   // Need to write after the above call to WriteFunction which populates
4737   // the summary information in the index.
4738   if (Index)
4739     writePerModuleGlobalValueSummary();
4740 
4741   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
4742 
4743   writeModuleHash(BlockStartPos);
4744 
4745   Stream.ExitBlock();
4746 }
4747 
4748 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
4749                                uint32_t &Position) {
4750   support::endian::write32le(&Buffer[Position], Value);
4751   Position += 4;
4752 }
4753 
4754 /// If generating a bc file on darwin, we have to emit a
4755 /// header and trailer to make it compatible with the system archiver.  To do
4756 /// this we emit the following header, and then emit a trailer that pads the
4757 /// file out to be a multiple of 16 bytes.
4758 ///
4759 /// struct bc_header {
4760 ///   uint32_t Magic;         // 0x0B17C0DE
4761 ///   uint32_t Version;       // Version, currently always 0.
4762 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4763 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4764 ///   uint32_t CPUType;       // CPU specifier.
4765 ///   ... potentially more later ...
4766 /// };
4767 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4768                                          const Triple &TT) {
4769   unsigned CPUType = ~0U;
4770 
4771   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4772   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4773   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4774   // specific constants here because they are implicitly part of the Darwin ABI.
4775   enum {
4776     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4777     DARWIN_CPU_TYPE_X86        = 7,
4778     DARWIN_CPU_TYPE_ARM        = 12,
4779     DARWIN_CPU_TYPE_POWERPC    = 18
4780   };
4781 
4782   Triple::ArchType Arch = TT.getArch();
4783   if (Arch == Triple::x86_64)
4784     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4785   else if (Arch == Triple::x86)
4786     CPUType = DARWIN_CPU_TYPE_X86;
4787   else if (Arch == Triple::ppc)
4788     CPUType = DARWIN_CPU_TYPE_POWERPC;
4789   else if (Arch == Triple::ppc64)
4790     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4791   else if (Arch == Triple::arm || Arch == Triple::thumb)
4792     CPUType = DARWIN_CPU_TYPE_ARM;
4793 
4794   // Traditional Bitcode starts after header.
4795   assert(Buffer.size() >= BWH_HeaderSize &&
4796          "Expected header size to be reserved");
4797   unsigned BCOffset = BWH_HeaderSize;
4798   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4799 
4800   // Write the magic and version.
4801   unsigned Position = 0;
4802   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4803   writeInt32ToBuffer(0, Buffer, Position); // Version.
4804   writeInt32ToBuffer(BCOffset, Buffer, Position);
4805   writeInt32ToBuffer(BCSize, Buffer, Position);
4806   writeInt32ToBuffer(CPUType, Buffer, Position);
4807 
4808   // If the file is not a multiple of 16 bytes, insert dummy padding.
4809   while (Buffer.size() & 15)
4810     Buffer.push_back(0);
4811 }
4812 
4813 /// Helper to write the header common to all bitcode files.
4814 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4815   // Emit the file header.
4816   Stream.Emit((unsigned)'B', 8);
4817   Stream.Emit((unsigned)'C', 8);
4818   Stream.Emit(0x0, 4);
4819   Stream.Emit(0xC, 4);
4820   Stream.Emit(0xE, 4);
4821   Stream.Emit(0xD, 4);
4822 }
4823 
4824 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer, raw_fd_stream *FS)
4825     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer, FS, FlushThreshold)) {
4826   writeBitcodeHeader(*Stream);
4827 }
4828 
4829 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4830 
4831 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4832   Stream->EnterSubblock(Block, 3);
4833 
4834   auto Abbv = std::make_shared<BitCodeAbbrev>();
4835   Abbv->Add(BitCodeAbbrevOp(Record));
4836   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4837   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4838 
4839   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4840 
4841   Stream->ExitBlock();
4842 }
4843 
4844 void BitcodeWriter::writeSymtab() {
4845   assert(!WroteStrtab && !WroteSymtab);
4846 
4847   // If any module has module-level inline asm, we will require a registered asm
4848   // parser for the target so that we can create an accurate symbol table for
4849   // the module.
4850   for (Module *M : Mods) {
4851     if (M->getModuleInlineAsm().empty())
4852       continue;
4853 
4854     std::string Err;
4855     const Triple TT(M->getTargetTriple());
4856     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4857     if (!T || !T->hasMCAsmParser())
4858       return;
4859   }
4860 
4861   WroteSymtab = true;
4862   SmallVector<char, 0> Symtab;
4863   // The irsymtab::build function may be unable to create a symbol table if the
4864   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4865   // table is not required for correctness, but we still want to be able to
4866   // write malformed modules to bitcode files, so swallow the error.
4867   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4868     consumeError(std::move(E));
4869     return;
4870   }
4871 
4872   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4873             {Symtab.data(), Symtab.size()});
4874 }
4875 
4876 void BitcodeWriter::writeStrtab() {
4877   assert(!WroteStrtab);
4878 
4879   std::vector<char> Strtab;
4880   StrtabBuilder.finalizeInOrder();
4881   Strtab.resize(StrtabBuilder.getSize());
4882   StrtabBuilder.write((uint8_t *)Strtab.data());
4883 
4884   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4885             {Strtab.data(), Strtab.size()});
4886 
4887   WroteStrtab = true;
4888 }
4889 
4890 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4891   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4892   WroteStrtab = true;
4893 }
4894 
4895 void BitcodeWriter::writeModule(const Module &M,
4896                                 bool ShouldPreserveUseListOrder,
4897                                 const ModuleSummaryIndex *Index,
4898                                 bool GenerateHash, ModuleHash *ModHash) {
4899   assert(!WroteStrtab);
4900 
4901   // The Mods vector is used by irsymtab::build, which requires non-const
4902   // Modules in case it needs to materialize metadata. But the bitcode writer
4903   // requires that the module is materialized, so we can cast to non-const here,
4904   // after checking that it is in fact materialized.
4905   assert(M.isMaterialized());
4906   Mods.push_back(const_cast<Module *>(&M));
4907 
4908   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4909                                    ShouldPreserveUseListOrder, Index,
4910                                    GenerateHash, ModHash);
4911   ModuleWriter.write();
4912 }
4913 
4914 void BitcodeWriter::writeIndex(
4915     const ModuleSummaryIndex *Index,
4916     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4917   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4918                                  ModuleToSummariesForIndex);
4919   IndexWriter.write();
4920 }
4921 
4922 /// Write the specified module to the specified output stream.
4923 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4924                               bool ShouldPreserveUseListOrder,
4925                               const ModuleSummaryIndex *Index,
4926                               bool GenerateHash, ModuleHash *ModHash) {
4927   SmallVector<char, 0> Buffer;
4928   Buffer.reserve(256*1024);
4929 
4930   // If this is darwin or another generic macho target, reserve space for the
4931   // header.
4932   Triple TT(M.getTargetTriple());
4933   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4934     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4935 
4936   BitcodeWriter Writer(Buffer, dyn_cast<raw_fd_stream>(&Out));
4937   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4938                      ModHash);
4939   Writer.writeSymtab();
4940   Writer.writeStrtab();
4941 
4942   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4943     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4944 
4945   // Write the generated bitstream to "Out".
4946   if (!Buffer.empty())
4947     Out.write((char *)&Buffer.front(), Buffer.size());
4948 }
4949 
4950 void IndexBitcodeWriter::write() {
4951   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4952 
4953   writeModuleVersion();
4954 
4955   // Write the module paths in the combined index.
4956   writeModStrings();
4957 
4958   // Write the summary combined index records.
4959   writeCombinedGlobalValueSummary();
4960 
4961   Stream.ExitBlock();
4962 }
4963 
4964 // Write the specified module summary index to the given raw output stream,
4965 // where it will be written in a new bitcode block. This is used when
4966 // writing the combined index file for ThinLTO. When writing a subset of the
4967 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4968 void llvm::writeIndexToFile(
4969     const ModuleSummaryIndex &Index, raw_ostream &Out,
4970     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4971   SmallVector<char, 0> Buffer;
4972   Buffer.reserve(256 * 1024);
4973 
4974   BitcodeWriter Writer(Buffer);
4975   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4976   Writer.writeStrtab();
4977 
4978   Out.write((char *)&Buffer.front(), Buffer.size());
4979 }
4980 
4981 namespace {
4982 
4983 /// Class to manage the bitcode writing for a thin link bitcode file.
4984 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4985   /// ModHash is for use in ThinLTO incremental build, generated while writing
4986   /// the module bitcode file.
4987   const ModuleHash *ModHash;
4988 
4989 public:
4990   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4991                         BitstreamWriter &Stream,
4992                         const ModuleSummaryIndex &Index,
4993                         const ModuleHash &ModHash)
4994       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4995                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4996         ModHash(&ModHash) {}
4997 
4998   void write();
4999 
5000 private:
5001   void writeSimplifiedModuleInfo();
5002 };
5003 
5004 } // end anonymous namespace
5005 
5006 // This function writes a simpilified module info for thin link bitcode file.
5007 // It only contains the source file name along with the name(the offset and
5008 // size in strtab) and linkage for global values. For the global value info
5009 // entry, in order to keep linkage at offset 5, there are three zeros used
5010 // as padding.
5011 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
5012   SmallVector<unsigned, 64> Vals;
5013   // Emit the module's source file name.
5014   {
5015     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
5016     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
5017     if (Bits == SE_Char6)
5018       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
5019     else if (Bits == SE_Fixed7)
5020       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
5021 
5022     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
5023     auto Abbv = std::make_shared<BitCodeAbbrev>();
5024     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
5025     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
5026     Abbv->Add(AbbrevOpToUse);
5027     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
5028 
5029     for (const auto P : M.getSourceFileName())
5030       Vals.push_back((unsigned char)P);
5031 
5032     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
5033     Vals.clear();
5034   }
5035 
5036   // Emit the global variable information.
5037   for (const GlobalVariable &GV : M.globals()) {
5038     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
5039     Vals.push_back(StrtabBuilder.add(GV.getName()));
5040     Vals.push_back(GV.getName().size());
5041     Vals.push_back(0);
5042     Vals.push_back(0);
5043     Vals.push_back(0);
5044     Vals.push_back(getEncodedLinkage(GV));
5045 
5046     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
5047     Vals.clear();
5048   }
5049 
5050   // Emit the function proto information.
5051   for (const Function &F : M) {
5052     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
5053     Vals.push_back(StrtabBuilder.add(F.getName()));
5054     Vals.push_back(F.getName().size());
5055     Vals.push_back(0);
5056     Vals.push_back(0);
5057     Vals.push_back(0);
5058     Vals.push_back(getEncodedLinkage(F));
5059 
5060     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
5061     Vals.clear();
5062   }
5063 
5064   // Emit the alias information.
5065   for (const GlobalAlias &A : M.aliases()) {
5066     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
5067     Vals.push_back(StrtabBuilder.add(A.getName()));
5068     Vals.push_back(A.getName().size());
5069     Vals.push_back(0);
5070     Vals.push_back(0);
5071     Vals.push_back(0);
5072     Vals.push_back(getEncodedLinkage(A));
5073 
5074     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
5075     Vals.clear();
5076   }
5077 
5078   // Emit the ifunc information.
5079   for (const GlobalIFunc &I : M.ifuncs()) {
5080     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
5081     Vals.push_back(StrtabBuilder.add(I.getName()));
5082     Vals.push_back(I.getName().size());
5083     Vals.push_back(0);
5084     Vals.push_back(0);
5085     Vals.push_back(0);
5086     Vals.push_back(getEncodedLinkage(I));
5087 
5088     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
5089     Vals.clear();
5090   }
5091 }
5092 
5093 void ThinLinkBitcodeWriter::write() {
5094   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
5095 
5096   writeModuleVersion();
5097 
5098   writeSimplifiedModuleInfo();
5099 
5100   writePerModuleGlobalValueSummary();
5101 
5102   // Write module hash.
5103   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
5104 
5105   Stream.ExitBlock();
5106 }
5107 
5108 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
5109                                          const ModuleSummaryIndex &Index,
5110                                          const ModuleHash &ModHash) {
5111   assert(!WroteStrtab);
5112 
5113   // The Mods vector is used by irsymtab::build, which requires non-const
5114   // Modules in case it needs to materialize metadata. But the bitcode writer
5115   // requires that the module is materialized, so we can cast to non-const here,
5116   // after checking that it is in fact materialized.
5117   assert(M.isMaterialized());
5118   Mods.push_back(const_cast<Module *>(&M));
5119 
5120   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
5121                                        ModHash);
5122   ThinLinkWriter.write();
5123 }
5124 
5125 // Write the specified thin link bitcode file to the given raw output stream,
5126 // where it will be written in a new bitcode block. This is used when
5127 // writing the per-module index file for ThinLTO.
5128 void llvm::writeThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
5129                                       const ModuleSummaryIndex &Index,
5130                                       const ModuleHash &ModHash) {
5131   SmallVector<char, 0> Buffer;
5132   Buffer.reserve(256 * 1024);
5133 
5134   BitcodeWriter Writer(Buffer);
5135   Writer.writeThinLinkBitcode(M, Index, ModHash);
5136   Writer.writeSymtab();
5137   Writer.writeStrtab();
5138 
5139   Out.write((char *)&Buffer.front(), Buffer.size());
5140 }
5141 
5142 static const char *getSectionNameForBitcode(const Triple &T) {
5143   switch (T.getObjectFormat()) {
5144   case Triple::MachO:
5145     return "__LLVM,__bitcode";
5146   case Triple::COFF:
5147   case Triple::ELF:
5148   case Triple::Wasm:
5149   case Triple::UnknownObjectFormat:
5150     return ".llvmbc";
5151   case Triple::GOFF:
5152     llvm_unreachable("GOFF is not yet implemented");
5153     break;
5154   case Triple::SPIRV:
5155     llvm_unreachable("SPIRV is not yet implemented");
5156     break;
5157   case Triple::XCOFF:
5158     llvm_unreachable("XCOFF is not yet implemented");
5159     break;
5160   case Triple::DXContainer:
5161     llvm_unreachable("DXContainer is not yet implemented");
5162     break;
5163   }
5164   llvm_unreachable("Unimplemented ObjectFormatType");
5165 }
5166 
5167 static const char *getSectionNameForCommandline(const Triple &T) {
5168   switch (T.getObjectFormat()) {
5169   case Triple::MachO:
5170     return "__LLVM,__cmdline";
5171   case Triple::COFF:
5172   case Triple::ELF:
5173   case Triple::Wasm:
5174   case Triple::UnknownObjectFormat:
5175     return ".llvmcmd";
5176   case Triple::GOFF:
5177     llvm_unreachable("GOFF is not yet implemented");
5178     break;
5179   case Triple::SPIRV:
5180     llvm_unreachable("SPIRV is not yet implemented");
5181     break;
5182   case Triple::XCOFF:
5183     llvm_unreachable("XCOFF is not yet implemented");
5184     break;
5185   case Triple::DXContainer:
5186     llvm_unreachable("DXC is not yet implemented");
5187     break;
5188   }
5189   llvm_unreachable("Unimplemented ObjectFormatType");
5190 }
5191 
5192 void llvm::embedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
5193                                 bool EmbedBitcode, bool EmbedCmdline,
5194                                 const std::vector<uint8_t> &CmdArgs) {
5195   // Save llvm.compiler.used and remove it.
5196   SmallVector<Constant *, 2> UsedArray;
5197   SmallVector<GlobalValue *, 4> UsedGlobals;
5198   Type *UsedElementType = PointerType::getUnqual(M.getContext());
5199   GlobalVariable *Used = collectUsedGlobalVariables(M, UsedGlobals, true);
5200   for (auto *GV : UsedGlobals) {
5201     if (GV->getName() != "llvm.embedded.module" &&
5202         GV->getName() != "llvm.cmdline")
5203       UsedArray.push_back(
5204           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
5205   }
5206   if (Used)
5207     Used->eraseFromParent();
5208 
5209   // Embed the bitcode for the llvm module.
5210   std::string Data;
5211   ArrayRef<uint8_t> ModuleData;
5212   Triple T(M.getTargetTriple());
5213 
5214   if (EmbedBitcode) {
5215     if (Buf.getBufferSize() == 0 ||
5216         !isBitcode((const unsigned char *)Buf.getBufferStart(),
5217                    (const unsigned char *)Buf.getBufferEnd())) {
5218       // If the input is LLVM Assembly, bitcode is produced by serializing
5219       // the module. Use-lists order need to be preserved in this case.
5220       llvm::raw_string_ostream OS(Data);
5221       llvm::WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
5222       ModuleData =
5223           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
5224     } else
5225       // If the input is LLVM bitcode, write the input byte stream directly.
5226       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
5227                                      Buf.getBufferSize());
5228   }
5229   llvm::Constant *ModuleConstant =
5230       llvm::ConstantDataArray::get(M.getContext(), ModuleData);
5231   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
5232       M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
5233       ModuleConstant);
5234   GV->setSection(getSectionNameForBitcode(T));
5235   // Set alignment to 1 to prevent padding between two contributions from input
5236   // sections after linking.
5237   GV->setAlignment(Align(1));
5238   UsedArray.push_back(
5239       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
5240   if (llvm::GlobalVariable *Old =
5241           M.getGlobalVariable("llvm.embedded.module", true)) {
5242     assert(Old->hasZeroLiveUses() &&
5243            "llvm.embedded.module can only be used once in llvm.compiler.used");
5244     GV->takeName(Old);
5245     Old->eraseFromParent();
5246   } else {
5247     GV->setName("llvm.embedded.module");
5248   }
5249 
5250   // Skip if only bitcode needs to be embedded.
5251   if (EmbedCmdline) {
5252     // Embed command-line options.
5253     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CmdArgs.data()),
5254                               CmdArgs.size());
5255     llvm::Constant *CmdConstant =
5256         llvm::ConstantDataArray::get(M.getContext(), CmdData);
5257     GV = new llvm::GlobalVariable(M, CmdConstant->getType(), true,
5258                                   llvm::GlobalValue::PrivateLinkage,
5259                                   CmdConstant);
5260     GV->setSection(getSectionNameForCommandline(T));
5261     GV->setAlignment(Align(1));
5262     UsedArray.push_back(
5263         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
5264     if (llvm::GlobalVariable *Old = M.getGlobalVariable("llvm.cmdline", true)) {
5265       assert(Old->hasZeroLiveUses() &&
5266              "llvm.cmdline can only be used once in llvm.compiler.used");
5267       GV->takeName(Old);
5268       Old->eraseFromParent();
5269     } else {
5270       GV->setName("llvm.cmdline");
5271     }
5272   }
5273 
5274   if (UsedArray.empty())
5275     return;
5276 
5277   // Recreate llvm.compiler.used.
5278   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
5279   auto *NewUsed = new GlobalVariable(
5280       M, ATy, false, llvm::GlobalValue::AppendingLinkage,
5281       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
5282   NewUsed->setSection("llvm.metadata");
5283 }
5284