xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 96bd4d34a220359662d21b0a60e74e15c3d19663)
1 //===- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Bitcode writer implementation.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/Bitcode/BitcodeWriter.h"
14 #include "ValueEnumerator.h"
15 #include "llvm/ADT/APFloat.h"
16 #include "llvm/ADT/APInt.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/None.h"
20 #include "llvm/ADT/Optional.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/StringMap.h"
25 #include "llvm/ADT/StringRef.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/Bitcode/BitcodeCommon.h"
28 #include "llvm/Bitcode/BitcodeReader.h"
29 #include "llvm/Bitcode/LLVMBitCodes.h"
30 #include "llvm/Bitstream/BitCodes.h"
31 #include "llvm/Bitstream/BitstreamWriter.h"
32 #include "llvm/Config/llvm-config.h"
33 #include "llvm/IR/Attributes.h"
34 #include "llvm/IR/BasicBlock.h"
35 #include "llvm/IR/Comdat.h"
36 #include "llvm/IR/Constant.h"
37 #include "llvm/IR/Constants.h"
38 #include "llvm/IR/DebugInfoMetadata.h"
39 #include "llvm/IR/DebugLoc.h"
40 #include "llvm/IR/DerivedTypes.h"
41 #include "llvm/IR/Function.h"
42 #include "llvm/IR/GlobalAlias.h"
43 #include "llvm/IR/GlobalIFunc.h"
44 #include "llvm/IR/GlobalObject.h"
45 #include "llvm/IR/GlobalValue.h"
46 #include "llvm/IR/GlobalVariable.h"
47 #include "llvm/IR/InlineAsm.h"
48 #include "llvm/IR/InstrTypes.h"
49 #include "llvm/IR/Instruction.h"
50 #include "llvm/IR/Instructions.h"
51 #include "llvm/IR/LLVMContext.h"
52 #include "llvm/IR/Metadata.h"
53 #include "llvm/IR/Module.h"
54 #include "llvm/IR/ModuleSummaryIndex.h"
55 #include "llvm/IR/Operator.h"
56 #include "llvm/IR/Type.h"
57 #include "llvm/IR/UseListOrder.h"
58 #include "llvm/IR/Value.h"
59 #include "llvm/IR/ValueSymbolTable.h"
60 #include "llvm/MC/StringTableBuilder.h"
61 #include "llvm/Object/IRSymtab.h"
62 #include "llvm/Support/AtomicOrdering.h"
63 #include "llvm/Support/Casting.h"
64 #include "llvm/Support/CommandLine.h"
65 #include "llvm/Support/Endian.h"
66 #include "llvm/Support/Error.h"
67 #include "llvm/Support/ErrorHandling.h"
68 #include "llvm/Support/MathExtras.h"
69 #include "llvm/Support/SHA1.h"
70 #include "llvm/Support/TargetRegistry.h"
71 #include "llvm/Support/raw_ostream.h"
72 #include <algorithm>
73 #include <cassert>
74 #include <cstddef>
75 #include <cstdint>
76 #include <iterator>
77 #include <map>
78 #include <memory>
79 #include <string>
80 #include <utility>
81 #include <vector>
82 
83 using namespace llvm;
84 
85 static cl::opt<unsigned>
86     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
87                    cl::desc("Number of metadatas above which we emit an index "
88                             "to enable lazy-loading"));
89 static cl::opt<uint32_t> FlushThreshold(
90     "bitcode-flush-threshold", cl::Hidden, cl::init(512),
91     cl::desc("The threshold (unit M) for flushing LLVM bitcode."));
92 
93 static cl::opt<bool> WriteRelBFToSummary(
94     "write-relbf-to-summary", cl::Hidden, cl::init(false),
95     cl::desc("Write relative block frequency to function summary "));
96 
97 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
98 
99 namespace {
100 
101 /// These are manifest constants used by the bitcode writer. They do not need to
102 /// be kept in sync with the reader, but need to be consistent within this file.
103 enum {
104   // VALUE_SYMTAB_BLOCK abbrev id's.
105   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
106   VST_ENTRY_7_ABBREV,
107   VST_ENTRY_6_ABBREV,
108   VST_BBENTRY_6_ABBREV,
109 
110   // CONSTANTS_BLOCK abbrev id's.
111   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
112   CONSTANTS_INTEGER_ABBREV,
113   CONSTANTS_CE_CAST_Abbrev,
114   CONSTANTS_NULL_Abbrev,
115 
116   // FUNCTION_BLOCK abbrev id's.
117   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
118   FUNCTION_INST_UNOP_ABBREV,
119   FUNCTION_INST_UNOP_FLAGS_ABBREV,
120   FUNCTION_INST_BINOP_ABBREV,
121   FUNCTION_INST_BINOP_FLAGS_ABBREV,
122   FUNCTION_INST_CAST_ABBREV,
123   FUNCTION_INST_RET_VOID_ABBREV,
124   FUNCTION_INST_RET_VAL_ABBREV,
125   FUNCTION_INST_UNREACHABLE_ABBREV,
126   FUNCTION_INST_GEP_ABBREV,
127 };
128 
129 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
130 /// file type.
131 class BitcodeWriterBase {
132 protected:
133   /// The stream created and owned by the client.
134   BitstreamWriter &Stream;
135 
136   StringTableBuilder &StrtabBuilder;
137 
138 public:
139   /// Constructs a BitcodeWriterBase object that writes to the provided
140   /// \p Stream.
141   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
142       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
143 
144 protected:
145   void writeBitcodeHeader();
146   void writeModuleVersion();
147 };
148 
149 void BitcodeWriterBase::writeModuleVersion() {
150   // VERSION: [version#]
151   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
152 }
153 
154 /// Base class to manage the module bitcode writing, currently subclassed for
155 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
156 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
157 protected:
158   /// The Module to write to bitcode.
159   const Module &M;
160 
161   /// Enumerates ids for all values in the module.
162   ValueEnumerator VE;
163 
164   /// Optional per-module index to write for ThinLTO.
165   const ModuleSummaryIndex *Index;
166 
167   /// Map that holds the correspondence between GUIDs in the summary index,
168   /// that came from indirect call profiles, and a value id generated by this
169   /// class to use in the VST and summary block records.
170   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
171 
172   /// Tracks the last value id recorded in the GUIDToValueMap.
173   unsigned GlobalValueId;
174 
175   /// Saves the offset of the VSTOffset record that must eventually be
176   /// backpatched with the offset of the actual VST.
177   uint64_t VSTOffsetPlaceholder = 0;
178 
179 public:
180   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
181   /// writing to the provided \p Buffer.
182   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
183                           BitstreamWriter &Stream,
184                           bool ShouldPreserveUseListOrder,
185                           const ModuleSummaryIndex *Index)
186       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
187         VE(M, ShouldPreserveUseListOrder), Index(Index) {
188     // Assign ValueIds to any callee values in the index that came from
189     // indirect call profiles and were recorded as a GUID not a Value*
190     // (which would have been assigned an ID by the ValueEnumerator).
191     // The starting ValueId is just after the number of values in the
192     // ValueEnumerator, so that they can be emitted in the VST.
193     GlobalValueId = VE.getValues().size();
194     if (!Index)
195       return;
196     for (const auto &GUIDSummaryLists : *Index)
197       // Examine all summaries for this GUID.
198       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
199         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
200           // For each call in the function summary, see if the call
201           // is to a GUID (which means it is for an indirect call,
202           // otherwise we would have a Value for it). If so, synthesize
203           // a value id.
204           for (auto &CallEdge : FS->calls())
205             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
206               assignValueId(CallEdge.first.getGUID());
207   }
208 
209 protected:
210   void writePerModuleGlobalValueSummary();
211 
212 private:
213   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
214                                            GlobalValueSummary *Summary,
215                                            unsigned ValueID,
216                                            unsigned FSCallsAbbrev,
217                                            unsigned FSCallsProfileAbbrev,
218                                            const Function &F);
219   void writeModuleLevelReferences(const GlobalVariable &V,
220                                   SmallVector<uint64_t, 64> &NameVals,
221                                   unsigned FSModRefsAbbrev,
222                                   unsigned FSModVTableRefsAbbrev);
223 
224   void assignValueId(GlobalValue::GUID ValGUID) {
225     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
226   }
227 
228   unsigned getValueId(GlobalValue::GUID ValGUID) {
229     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
230     // Expect that any GUID value had a value Id assigned by an
231     // earlier call to assignValueId.
232     assert(VMI != GUIDToValueIdMap.end() &&
233            "GUID does not have assigned value Id");
234     return VMI->second;
235   }
236 
237   // Helper to get the valueId for the type of value recorded in VI.
238   unsigned getValueId(ValueInfo VI) {
239     if (!VI.haveGVs() || !VI.getValue())
240       return getValueId(VI.getGUID());
241     return VE.getValueID(VI.getValue());
242   }
243 
244   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
245 };
246 
247 /// Class to manage the bitcode writing for a module.
248 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
249   /// Pointer to the buffer allocated by caller for bitcode writing.
250   const SmallVectorImpl<char> &Buffer;
251 
252   /// True if a module hash record should be written.
253   bool GenerateHash;
254 
255   /// If non-null, when GenerateHash is true, the resulting hash is written
256   /// into ModHash.
257   ModuleHash *ModHash;
258 
259   SHA1 Hasher;
260 
261   /// The start bit of the identification block.
262   uint64_t BitcodeStartBit;
263 
264 public:
265   /// Constructs a ModuleBitcodeWriter object for the given Module,
266   /// writing to the provided \p Buffer.
267   ModuleBitcodeWriter(const Module &M, SmallVectorImpl<char> &Buffer,
268                       StringTableBuilder &StrtabBuilder,
269                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
270                       const ModuleSummaryIndex *Index, bool GenerateHash,
271                       ModuleHash *ModHash = nullptr)
272       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
273                                 ShouldPreserveUseListOrder, Index),
274         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
275         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
276 
277   /// Emit the current module to the bitstream.
278   void write();
279 
280 private:
281   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
282 
283   size_t addToStrtab(StringRef Str);
284 
285   void writeAttributeGroupTable();
286   void writeAttributeTable();
287   void writeTypeTable();
288   void writeComdats();
289   void writeValueSymbolTableForwardDecl();
290   void writeModuleInfo();
291   void writeValueAsMetadata(const ValueAsMetadata *MD,
292                             SmallVectorImpl<uint64_t> &Record);
293   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
294                     unsigned Abbrev);
295   unsigned createDILocationAbbrev();
296   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
297                        unsigned &Abbrev);
298   unsigned createGenericDINodeAbbrev();
299   void writeGenericDINode(const GenericDINode *N,
300                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
301   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
302                        unsigned Abbrev);
303   void writeDIEnumerator(const DIEnumerator *N,
304                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
305   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
306                         unsigned Abbrev);
307   void writeDIStringType(const DIStringType *N,
308                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
309   void writeDIDerivedType(const DIDerivedType *N,
310                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
311   void writeDICompositeType(const DICompositeType *N,
312                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
313   void writeDISubroutineType(const DISubroutineType *N,
314                              SmallVectorImpl<uint64_t> &Record,
315                              unsigned Abbrev);
316   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
317                    unsigned Abbrev);
318   void writeDICompileUnit(const DICompileUnit *N,
319                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
320   void writeDISubprogram(const DISubprogram *N,
321                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
322   void writeDILexicalBlock(const DILexicalBlock *N,
323                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
324   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
325                                SmallVectorImpl<uint64_t> &Record,
326                                unsigned Abbrev);
327   void writeDICommonBlock(const DICommonBlock *N,
328                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
329   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
330                         unsigned Abbrev);
331   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
332                     unsigned Abbrev);
333   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
334                         unsigned Abbrev);
335   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
336                      unsigned Abbrev);
337   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
338                                     SmallVectorImpl<uint64_t> &Record,
339                                     unsigned Abbrev);
340   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
341                                      SmallVectorImpl<uint64_t> &Record,
342                                      unsigned Abbrev);
343   void writeDIGlobalVariable(const DIGlobalVariable *N,
344                              SmallVectorImpl<uint64_t> &Record,
345                              unsigned Abbrev);
346   void writeDILocalVariable(const DILocalVariable *N,
347                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
348   void writeDILabel(const DILabel *N,
349                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
350   void writeDIExpression(const DIExpression *N,
351                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
352   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
353                                        SmallVectorImpl<uint64_t> &Record,
354                                        unsigned Abbrev);
355   void writeDIObjCProperty(const DIObjCProperty *N,
356                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
357   void writeDIImportedEntity(const DIImportedEntity *N,
358                              SmallVectorImpl<uint64_t> &Record,
359                              unsigned Abbrev);
360   unsigned createNamedMetadataAbbrev();
361   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
362   unsigned createMetadataStringsAbbrev();
363   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
364                             SmallVectorImpl<uint64_t> &Record);
365   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
366                             SmallVectorImpl<uint64_t> &Record,
367                             std::vector<unsigned> *MDAbbrevs = nullptr,
368                             std::vector<uint64_t> *IndexPos = nullptr);
369   void writeModuleMetadata();
370   void writeFunctionMetadata(const Function &F);
371   void writeFunctionMetadataAttachment(const Function &F);
372   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
373   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
374                                     const GlobalObject &GO);
375   void writeModuleMetadataKinds();
376   void writeOperandBundleTags();
377   void writeSyncScopeNames();
378   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
379   void writeModuleConstants();
380   bool pushValueAndType(const Value *V, unsigned InstID,
381                         SmallVectorImpl<unsigned> &Vals);
382   void writeOperandBundles(const CallBase &CB, unsigned InstID);
383   void pushValue(const Value *V, unsigned InstID,
384                  SmallVectorImpl<unsigned> &Vals);
385   void pushValueSigned(const Value *V, unsigned InstID,
386                        SmallVectorImpl<uint64_t> &Vals);
387   void writeInstruction(const Instruction &I, unsigned InstID,
388                         SmallVectorImpl<unsigned> &Vals);
389   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
390   void writeGlobalValueSymbolTable(
391       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
392   void writeUseList(UseListOrder &&Order);
393   void writeUseListBlock(const Function *F);
394   void
395   writeFunction(const Function &F,
396                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
397   void writeBlockInfo();
398   void writeModuleHash(size_t BlockStartPos);
399 
400   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
401     return unsigned(SSID);
402   }
403 
404   unsigned getEncodedAlign(MaybeAlign Alignment) { return encode(Alignment); }
405 };
406 
407 /// Class to manage the bitcode writing for a combined index.
408 class IndexBitcodeWriter : public BitcodeWriterBase {
409   /// The combined index to write to bitcode.
410   const ModuleSummaryIndex &Index;
411 
412   /// When writing a subset of the index for distributed backends, client
413   /// provides a map of modules to the corresponding GUIDs/summaries to write.
414   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
415 
416   /// Map that holds the correspondence between the GUID used in the combined
417   /// index and a value id generated by this class to use in references.
418   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
419 
420   /// Tracks the last value id recorded in the GUIDToValueMap.
421   unsigned GlobalValueId = 0;
422 
423 public:
424   /// Constructs a IndexBitcodeWriter object for the given combined index,
425   /// writing to the provided \p Buffer. When writing a subset of the index
426   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
427   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
428                      const ModuleSummaryIndex &Index,
429                      const std::map<std::string, GVSummaryMapTy>
430                          *ModuleToSummariesForIndex = nullptr)
431       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
432         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
433     // Assign unique value ids to all summaries to be written, for use
434     // in writing out the call graph edges. Save the mapping from GUID
435     // to the new global value id to use when writing those edges, which
436     // are currently saved in the index in terms of GUID.
437     forEachSummary([&](GVInfo I, bool) {
438       GUIDToValueIdMap[I.first] = ++GlobalValueId;
439     });
440   }
441 
442   /// The below iterator returns the GUID and associated summary.
443   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
444 
445   /// Calls the callback for each value GUID and summary to be written to
446   /// bitcode. This hides the details of whether they are being pulled from the
447   /// entire index or just those in a provided ModuleToSummariesForIndex map.
448   template<typename Functor>
449   void forEachSummary(Functor Callback) {
450     if (ModuleToSummariesForIndex) {
451       for (auto &M : *ModuleToSummariesForIndex)
452         for (auto &Summary : M.second) {
453           Callback(Summary, false);
454           // Ensure aliasee is handled, e.g. for assigning a valueId,
455           // even if we are not importing the aliasee directly (the
456           // imported alias will contain a copy of aliasee).
457           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
458             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
459         }
460     } else {
461       for (auto &Summaries : Index)
462         for (auto &Summary : Summaries.second.SummaryList)
463           Callback({Summaries.first, Summary.get()}, false);
464     }
465   }
466 
467   /// Calls the callback for each entry in the modulePaths StringMap that
468   /// should be written to the module path string table. This hides the details
469   /// of whether they are being pulled from the entire index or just those in a
470   /// provided ModuleToSummariesForIndex map.
471   template <typename Functor> void forEachModule(Functor Callback) {
472     if (ModuleToSummariesForIndex) {
473       for (const auto &M : *ModuleToSummariesForIndex) {
474         const auto &MPI = Index.modulePaths().find(M.first);
475         if (MPI == Index.modulePaths().end()) {
476           // This should only happen if the bitcode file was empty, in which
477           // case we shouldn't be importing (the ModuleToSummariesForIndex
478           // would only include the module we are writing and index for).
479           assert(ModuleToSummariesForIndex->size() == 1);
480           continue;
481         }
482         Callback(*MPI);
483       }
484     } else {
485       for (const auto &MPSE : Index.modulePaths())
486         Callback(MPSE);
487     }
488   }
489 
490   /// Main entry point for writing a combined index to bitcode.
491   void write();
492 
493 private:
494   void writeModStrings();
495   void writeCombinedGlobalValueSummary();
496 
497   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
498     auto VMI = GUIDToValueIdMap.find(ValGUID);
499     if (VMI == GUIDToValueIdMap.end())
500       return None;
501     return VMI->second;
502   }
503 
504   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
505 };
506 
507 } // end anonymous namespace
508 
509 static unsigned getEncodedCastOpcode(unsigned Opcode) {
510   switch (Opcode) {
511   default: llvm_unreachable("Unknown cast instruction!");
512   case Instruction::Trunc   : return bitc::CAST_TRUNC;
513   case Instruction::ZExt    : return bitc::CAST_ZEXT;
514   case Instruction::SExt    : return bitc::CAST_SEXT;
515   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
516   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
517   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
518   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
519   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
520   case Instruction::FPExt   : return bitc::CAST_FPEXT;
521   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
522   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
523   case Instruction::BitCast : return bitc::CAST_BITCAST;
524   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
525   }
526 }
527 
528 static unsigned getEncodedUnaryOpcode(unsigned Opcode) {
529   switch (Opcode) {
530   default: llvm_unreachable("Unknown binary instruction!");
531   case Instruction::FNeg: return bitc::UNOP_FNEG;
532   }
533 }
534 
535 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
536   switch (Opcode) {
537   default: llvm_unreachable("Unknown binary instruction!");
538   case Instruction::Add:
539   case Instruction::FAdd: return bitc::BINOP_ADD;
540   case Instruction::Sub:
541   case Instruction::FSub: return bitc::BINOP_SUB;
542   case Instruction::Mul:
543   case Instruction::FMul: return bitc::BINOP_MUL;
544   case Instruction::UDiv: return bitc::BINOP_UDIV;
545   case Instruction::FDiv:
546   case Instruction::SDiv: return bitc::BINOP_SDIV;
547   case Instruction::URem: return bitc::BINOP_UREM;
548   case Instruction::FRem:
549   case Instruction::SRem: return bitc::BINOP_SREM;
550   case Instruction::Shl:  return bitc::BINOP_SHL;
551   case Instruction::LShr: return bitc::BINOP_LSHR;
552   case Instruction::AShr: return bitc::BINOP_ASHR;
553   case Instruction::And:  return bitc::BINOP_AND;
554   case Instruction::Or:   return bitc::BINOP_OR;
555   case Instruction::Xor:  return bitc::BINOP_XOR;
556   }
557 }
558 
559 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
560   switch (Op) {
561   default: llvm_unreachable("Unknown RMW operation!");
562   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
563   case AtomicRMWInst::Add: return bitc::RMW_ADD;
564   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
565   case AtomicRMWInst::And: return bitc::RMW_AND;
566   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
567   case AtomicRMWInst::Or: return bitc::RMW_OR;
568   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
569   case AtomicRMWInst::Max: return bitc::RMW_MAX;
570   case AtomicRMWInst::Min: return bitc::RMW_MIN;
571   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
572   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
573   case AtomicRMWInst::FAdd: return bitc::RMW_FADD;
574   case AtomicRMWInst::FSub: return bitc::RMW_FSUB;
575   }
576 }
577 
578 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
579   switch (Ordering) {
580   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
581   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
582   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
583   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
584   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
585   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
586   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
587   }
588   llvm_unreachable("Invalid ordering");
589 }
590 
591 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
592                               StringRef Str, unsigned AbbrevToUse) {
593   SmallVector<unsigned, 64> Vals;
594 
595   // Code: [strchar x N]
596   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
597     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
598       AbbrevToUse = 0;
599     Vals.push_back(Str[i]);
600   }
601 
602   // Emit the finished record.
603   Stream.EmitRecord(Code, Vals, AbbrevToUse);
604 }
605 
606 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
607   switch (Kind) {
608   case Attribute::Alignment:
609     return bitc::ATTR_KIND_ALIGNMENT;
610   case Attribute::AllocSize:
611     return bitc::ATTR_KIND_ALLOC_SIZE;
612   case Attribute::AlwaysInline:
613     return bitc::ATTR_KIND_ALWAYS_INLINE;
614   case Attribute::ArgMemOnly:
615     return bitc::ATTR_KIND_ARGMEMONLY;
616   case Attribute::Builtin:
617     return bitc::ATTR_KIND_BUILTIN;
618   case Attribute::ByVal:
619     return bitc::ATTR_KIND_BY_VAL;
620   case Attribute::Convergent:
621     return bitc::ATTR_KIND_CONVERGENT;
622   case Attribute::InAlloca:
623     return bitc::ATTR_KIND_IN_ALLOCA;
624   case Attribute::Cold:
625     return bitc::ATTR_KIND_COLD;
626   case Attribute::InaccessibleMemOnly:
627     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
628   case Attribute::InaccessibleMemOrArgMemOnly:
629     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
630   case Attribute::InlineHint:
631     return bitc::ATTR_KIND_INLINE_HINT;
632   case Attribute::InReg:
633     return bitc::ATTR_KIND_IN_REG;
634   case Attribute::JumpTable:
635     return bitc::ATTR_KIND_JUMP_TABLE;
636   case Attribute::MinSize:
637     return bitc::ATTR_KIND_MIN_SIZE;
638   case Attribute::Naked:
639     return bitc::ATTR_KIND_NAKED;
640   case Attribute::Nest:
641     return bitc::ATTR_KIND_NEST;
642   case Attribute::NoAlias:
643     return bitc::ATTR_KIND_NO_ALIAS;
644   case Attribute::NoBuiltin:
645     return bitc::ATTR_KIND_NO_BUILTIN;
646   case Attribute::NoCapture:
647     return bitc::ATTR_KIND_NO_CAPTURE;
648   case Attribute::NoDuplicate:
649     return bitc::ATTR_KIND_NO_DUPLICATE;
650   case Attribute::NoFree:
651     return bitc::ATTR_KIND_NOFREE;
652   case Attribute::NoImplicitFloat:
653     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
654   case Attribute::NoInline:
655     return bitc::ATTR_KIND_NO_INLINE;
656   case Attribute::NoRecurse:
657     return bitc::ATTR_KIND_NO_RECURSE;
658   case Attribute::NoMerge:
659     return bitc::ATTR_KIND_NO_MERGE;
660   case Attribute::NonLazyBind:
661     return bitc::ATTR_KIND_NON_LAZY_BIND;
662   case Attribute::NonNull:
663     return bitc::ATTR_KIND_NON_NULL;
664   case Attribute::Dereferenceable:
665     return bitc::ATTR_KIND_DEREFERENCEABLE;
666   case Attribute::DereferenceableOrNull:
667     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
668   case Attribute::NoRedZone:
669     return bitc::ATTR_KIND_NO_RED_ZONE;
670   case Attribute::NoReturn:
671     return bitc::ATTR_KIND_NO_RETURN;
672   case Attribute::NoSync:
673     return bitc::ATTR_KIND_NOSYNC;
674   case Attribute::NoCfCheck:
675     return bitc::ATTR_KIND_NOCF_CHECK;
676   case Attribute::NoUnwind:
677     return bitc::ATTR_KIND_NO_UNWIND;
678   case Attribute::NullPointerIsValid:
679     return bitc::ATTR_KIND_NULL_POINTER_IS_VALID;
680   case Attribute::OptForFuzzing:
681     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
682   case Attribute::OptimizeForSize:
683     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
684   case Attribute::OptimizeNone:
685     return bitc::ATTR_KIND_OPTIMIZE_NONE;
686   case Attribute::ReadNone:
687     return bitc::ATTR_KIND_READ_NONE;
688   case Attribute::ReadOnly:
689     return bitc::ATTR_KIND_READ_ONLY;
690   case Attribute::Returned:
691     return bitc::ATTR_KIND_RETURNED;
692   case Attribute::ReturnsTwice:
693     return bitc::ATTR_KIND_RETURNS_TWICE;
694   case Attribute::SExt:
695     return bitc::ATTR_KIND_S_EXT;
696   case Attribute::Speculatable:
697     return bitc::ATTR_KIND_SPECULATABLE;
698   case Attribute::StackAlignment:
699     return bitc::ATTR_KIND_STACK_ALIGNMENT;
700   case Attribute::StackProtect:
701     return bitc::ATTR_KIND_STACK_PROTECT;
702   case Attribute::StackProtectReq:
703     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
704   case Attribute::StackProtectStrong:
705     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
706   case Attribute::SafeStack:
707     return bitc::ATTR_KIND_SAFESTACK;
708   case Attribute::ShadowCallStack:
709     return bitc::ATTR_KIND_SHADOWCALLSTACK;
710   case Attribute::StrictFP:
711     return bitc::ATTR_KIND_STRICT_FP;
712   case Attribute::StructRet:
713     return bitc::ATTR_KIND_STRUCT_RET;
714   case Attribute::SanitizeAddress:
715     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
716   case Attribute::SanitizeHWAddress:
717     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
718   case Attribute::SanitizeThread:
719     return bitc::ATTR_KIND_SANITIZE_THREAD;
720   case Attribute::SanitizeMemory:
721     return bitc::ATTR_KIND_SANITIZE_MEMORY;
722   case Attribute::SpeculativeLoadHardening:
723     return bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING;
724   case Attribute::SwiftError:
725     return bitc::ATTR_KIND_SWIFT_ERROR;
726   case Attribute::SwiftSelf:
727     return bitc::ATTR_KIND_SWIFT_SELF;
728   case Attribute::UWTable:
729     return bitc::ATTR_KIND_UW_TABLE;
730   case Attribute::WillReturn:
731     return bitc::ATTR_KIND_WILLRETURN;
732   case Attribute::WriteOnly:
733     return bitc::ATTR_KIND_WRITEONLY;
734   case Attribute::ZExt:
735     return bitc::ATTR_KIND_Z_EXT;
736   case Attribute::ImmArg:
737     return bitc::ATTR_KIND_IMMARG;
738   case Attribute::SanitizeMemTag:
739     return bitc::ATTR_KIND_SANITIZE_MEMTAG;
740   case Attribute::Preallocated:
741     return bitc::ATTR_KIND_PREALLOCATED;
742   case Attribute::NoUndef:
743     return bitc::ATTR_KIND_NOUNDEF;
744   case Attribute::ByRef:
745     return bitc::ATTR_KIND_BYREF;
746   case Attribute::EndAttrKinds:
747     llvm_unreachable("Can not encode end-attribute kinds marker.");
748   case Attribute::None:
749     llvm_unreachable("Can not encode none-attribute.");
750   case Attribute::EmptyKey:
751   case Attribute::TombstoneKey:
752     llvm_unreachable("Trying to encode EmptyKey/TombstoneKey");
753   }
754 
755   llvm_unreachable("Trying to encode unknown attribute");
756 }
757 
758 void ModuleBitcodeWriter::writeAttributeGroupTable() {
759   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
760       VE.getAttributeGroups();
761   if (AttrGrps.empty()) return;
762 
763   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
764 
765   SmallVector<uint64_t, 64> Record;
766   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
767     unsigned AttrListIndex = Pair.first;
768     AttributeSet AS = Pair.second;
769     Record.push_back(VE.getAttributeGroupID(Pair));
770     Record.push_back(AttrListIndex);
771 
772     for (Attribute Attr : AS) {
773       if (Attr.isEnumAttribute()) {
774         Record.push_back(0);
775         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
776       } else if (Attr.isIntAttribute()) {
777         Record.push_back(1);
778         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
779         Record.push_back(Attr.getValueAsInt());
780       } else if (Attr.isStringAttribute()) {
781         StringRef Kind = Attr.getKindAsString();
782         StringRef Val = Attr.getValueAsString();
783 
784         Record.push_back(Val.empty() ? 3 : 4);
785         Record.append(Kind.begin(), Kind.end());
786         Record.push_back(0);
787         if (!Val.empty()) {
788           Record.append(Val.begin(), Val.end());
789           Record.push_back(0);
790         }
791       } else {
792         assert(Attr.isTypeAttribute());
793         Type *Ty = Attr.getValueAsType();
794         Record.push_back(Ty ? 6 : 5);
795         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
796         if (Ty)
797           Record.push_back(VE.getTypeID(Attr.getValueAsType()));
798       }
799     }
800 
801     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
802     Record.clear();
803   }
804 
805   Stream.ExitBlock();
806 }
807 
808 void ModuleBitcodeWriter::writeAttributeTable() {
809   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
810   if (Attrs.empty()) return;
811 
812   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
813 
814   SmallVector<uint64_t, 64> Record;
815   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
816     AttributeList AL = Attrs[i];
817     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
818       AttributeSet AS = AL.getAttributes(i);
819       if (AS.hasAttributes())
820         Record.push_back(VE.getAttributeGroupID({i, AS}));
821     }
822 
823     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
824     Record.clear();
825   }
826 
827   Stream.ExitBlock();
828 }
829 
830 /// WriteTypeTable - Write out the type table for a module.
831 void ModuleBitcodeWriter::writeTypeTable() {
832   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
833 
834   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
835   SmallVector<uint64_t, 64> TypeVals;
836 
837   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
838 
839   // Abbrev for TYPE_CODE_POINTER.
840   auto Abbv = std::make_shared<BitCodeAbbrev>();
841   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
842   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
843   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
844   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
845 
846   // Abbrev for TYPE_CODE_FUNCTION.
847   Abbv = std::make_shared<BitCodeAbbrev>();
848   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
849   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
850   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
851   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
852   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
853 
854   // Abbrev for TYPE_CODE_STRUCT_ANON.
855   Abbv = std::make_shared<BitCodeAbbrev>();
856   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
857   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
858   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
859   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
860   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
861 
862   // Abbrev for TYPE_CODE_STRUCT_NAME.
863   Abbv = std::make_shared<BitCodeAbbrev>();
864   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
865   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
866   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
867   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
868 
869   // Abbrev for TYPE_CODE_STRUCT_NAMED.
870   Abbv = std::make_shared<BitCodeAbbrev>();
871   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
872   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
873   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
874   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
875   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
876 
877   // Abbrev for TYPE_CODE_ARRAY.
878   Abbv = std::make_shared<BitCodeAbbrev>();
879   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
880   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
881   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
882   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
883 
884   // Emit an entry count so the reader can reserve space.
885   TypeVals.push_back(TypeList.size());
886   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
887   TypeVals.clear();
888 
889   // Loop over all of the types, emitting each in turn.
890   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
891     Type *T = TypeList[i];
892     int AbbrevToUse = 0;
893     unsigned Code = 0;
894 
895     switch (T->getTypeID()) {
896     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
897     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
898     case Type::BFloatTyID:    Code = bitc::TYPE_CODE_BFLOAT;    break;
899     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
900     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
901     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
902     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
903     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
904     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
905     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
906     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
907     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
908     case Type::IntegerTyID:
909       // INTEGER: [width]
910       Code = bitc::TYPE_CODE_INTEGER;
911       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
912       break;
913     case Type::PointerTyID: {
914       PointerType *PTy = cast<PointerType>(T);
915       // POINTER: [pointee type, address space]
916       Code = bitc::TYPE_CODE_POINTER;
917       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
918       unsigned AddressSpace = PTy->getAddressSpace();
919       TypeVals.push_back(AddressSpace);
920       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
921       break;
922     }
923     case Type::FunctionTyID: {
924       FunctionType *FT = cast<FunctionType>(T);
925       // FUNCTION: [isvararg, retty, paramty x N]
926       Code = bitc::TYPE_CODE_FUNCTION;
927       TypeVals.push_back(FT->isVarArg());
928       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
929       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
930         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
931       AbbrevToUse = FunctionAbbrev;
932       break;
933     }
934     case Type::StructTyID: {
935       StructType *ST = cast<StructType>(T);
936       // STRUCT: [ispacked, eltty x N]
937       TypeVals.push_back(ST->isPacked());
938       // Output all of the element types.
939       for (StructType::element_iterator I = ST->element_begin(),
940            E = ST->element_end(); I != E; ++I)
941         TypeVals.push_back(VE.getTypeID(*I));
942 
943       if (ST->isLiteral()) {
944         Code = bitc::TYPE_CODE_STRUCT_ANON;
945         AbbrevToUse = StructAnonAbbrev;
946       } else {
947         if (ST->isOpaque()) {
948           Code = bitc::TYPE_CODE_OPAQUE;
949         } else {
950           Code = bitc::TYPE_CODE_STRUCT_NAMED;
951           AbbrevToUse = StructNamedAbbrev;
952         }
953 
954         // Emit the name if it is present.
955         if (!ST->getName().empty())
956           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
957                             StructNameAbbrev);
958       }
959       break;
960     }
961     case Type::ArrayTyID: {
962       ArrayType *AT = cast<ArrayType>(T);
963       // ARRAY: [numelts, eltty]
964       Code = bitc::TYPE_CODE_ARRAY;
965       TypeVals.push_back(AT->getNumElements());
966       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
967       AbbrevToUse = ArrayAbbrev;
968       break;
969     }
970     case Type::FixedVectorTyID:
971     case Type::ScalableVectorTyID: {
972       VectorType *VT = cast<VectorType>(T);
973       // VECTOR [numelts, eltty] or
974       //        [numelts, eltty, scalable]
975       Code = bitc::TYPE_CODE_VECTOR;
976       TypeVals.push_back(VT->getElementCount().getKnownMinValue());
977       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
978       if (isa<ScalableVectorType>(VT))
979         TypeVals.push_back(true);
980       break;
981     }
982     }
983 
984     // Emit the finished record.
985     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
986     TypeVals.clear();
987   }
988 
989   Stream.ExitBlock();
990 }
991 
992 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
993   switch (Linkage) {
994   case GlobalValue::ExternalLinkage:
995     return 0;
996   case GlobalValue::WeakAnyLinkage:
997     return 16;
998   case GlobalValue::AppendingLinkage:
999     return 2;
1000   case GlobalValue::InternalLinkage:
1001     return 3;
1002   case GlobalValue::LinkOnceAnyLinkage:
1003     return 18;
1004   case GlobalValue::ExternalWeakLinkage:
1005     return 7;
1006   case GlobalValue::CommonLinkage:
1007     return 8;
1008   case GlobalValue::PrivateLinkage:
1009     return 9;
1010   case GlobalValue::WeakODRLinkage:
1011     return 17;
1012   case GlobalValue::LinkOnceODRLinkage:
1013     return 19;
1014   case GlobalValue::AvailableExternallyLinkage:
1015     return 12;
1016   }
1017   llvm_unreachable("Invalid linkage");
1018 }
1019 
1020 static unsigned getEncodedLinkage(const GlobalValue &GV) {
1021   return getEncodedLinkage(GV.getLinkage());
1022 }
1023 
1024 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
1025   uint64_t RawFlags = 0;
1026   RawFlags |= Flags.ReadNone;
1027   RawFlags |= (Flags.ReadOnly << 1);
1028   RawFlags |= (Flags.NoRecurse << 2);
1029   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
1030   RawFlags |= (Flags.NoInline << 4);
1031   RawFlags |= (Flags.AlwaysInline << 5);
1032   return RawFlags;
1033 }
1034 
1035 // Decode the flags for GlobalValue in the summary
1036 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
1037   uint64_t RawFlags = 0;
1038 
1039   RawFlags |= Flags.NotEligibleToImport; // bool
1040   RawFlags |= (Flags.Live << 1);
1041   RawFlags |= (Flags.DSOLocal << 2);
1042   RawFlags |= (Flags.CanAutoHide << 3);
1043 
1044   // Linkage don't need to be remapped at that time for the summary. Any future
1045   // change to the getEncodedLinkage() function will need to be taken into
1046   // account here as well.
1047   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
1048 
1049   return RawFlags;
1050 }
1051 
1052 static uint64_t getEncodedGVarFlags(GlobalVarSummary::GVarFlags Flags) {
1053   uint64_t RawFlags = Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) |
1054                       (Flags.Constant << 2) | Flags.VCallVisibility << 3;
1055   return RawFlags;
1056 }
1057 
1058 static unsigned getEncodedVisibility(const GlobalValue &GV) {
1059   switch (GV.getVisibility()) {
1060   case GlobalValue::DefaultVisibility:   return 0;
1061   case GlobalValue::HiddenVisibility:    return 1;
1062   case GlobalValue::ProtectedVisibility: return 2;
1063   }
1064   llvm_unreachable("Invalid visibility");
1065 }
1066 
1067 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1068   switch (GV.getDLLStorageClass()) {
1069   case GlobalValue::DefaultStorageClass:   return 0;
1070   case GlobalValue::DLLImportStorageClass: return 1;
1071   case GlobalValue::DLLExportStorageClass: return 2;
1072   }
1073   llvm_unreachable("Invalid DLL storage class");
1074 }
1075 
1076 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1077   switch (GV.getThreadLocalMode()) {
1078     case GlobalVariable::NotThreadLocal:         return 0;
1079     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1080     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1081     case GlobalVariable::InitialExecTLSModel:    return 3;
1082     case GlobalVariable::LocalExecTLSModel:      return 4;
1083   }
1084   llvm_unreachable("Invalid TLS model");
1085 }
1086 
1087 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1088   switch (C.getSelectionKind()) {
1089   case Comdat::Any:
1090     return bitc::COMDAT_SELECTION_KIND_ANY;
1091   case Comdat::ExactMatch:
1092     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1093   case Comdat::Largest:
1094     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1095   case Comdat::NoDuplicates:
1096     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1097   case Comdat::SameSize:
1098     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1099   }
1100   llvm_unreachable("Invalid selection kind");
1101 }
1102 
1103 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1104   switch (GV.getUnnamedAddr()) {
1105   case GlobalValue::UnnamedAddr::None:   return 0;
1106   case GlobalValue::UnnamedAddr::Local:  return 2;
1107   case GlobalValue::UnnamedAddr::Global: return 1;
1108   }
1109   llvm_unreachable("Invalid unnamed_addr");
1110 }
1111 
1112 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1113   if (GenerateHash)
1114     Hasher.update(Str);
1115   return StrtabBuilder.add(Str);
1116 }
1117 
1118 void ModuleBitcodeWriter::writeComdats() {
1119   SmallVector<unsigned, 64> Vals;
1120   for (const Comdat *C : VE.getComdats()) {
1121     // COMDAT: [strtab offset, strtab size, selection_kind]
1122     Vals.push_back(addToStrtab(C->getName()));
1123     Vals.push_back(C->getName().size());
1124     Vals.push_back(getEncodedComdatSelectionKind(*C));
1125     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1126     Vals.clear();
1127   }
1128 }
1129 
1130 /// Write a record that will eventually hold the word offset of the
1131 /// module-level VST. For now the offset is 0, which will be backpatched
1132 /// after the real VST is written. Saves the bit offset to backpatch.
1133 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1134   // Write a placeholder value in for the offset of the real VST,
1135   // which is written after the function blocks so that it can include
1136   // the offset of each function. The placeholder offset will be
1137   // updated when the real VST is written.
1138   auto Abbv = std::make_shared<BitCodeAbbrev>();
1139   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1140   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1141   // hold the real VST offset. Must use fixed instead of VBR as we don't
1142   // know how many VBR chunks to reserve ahead of time.
1143   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1144   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1145 
1146   // Emit the placeholder
1147   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1148   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1149 
1150   // Compute and save the bit offset to the placeholder, which will be
1151   // patched when the real VST is written. We can simply subtract the 32-bit
1152   // fixed size from the current bit number to get the location to backpatch.
1153   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1154 }
1155 
1156 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1157 
1158 /// Determine the encoding to use for the given string name and length.
1159 static StringEncoding getStringEncoding(StringRef Str) {
1160   bool isChar6 = true;
1161   for (char C : Str) {
1162     if (isChar6)
1163       isChar6 = BitCodeAbbrevOp::isChar6(C);
1164     if ((unsigned char)C & 128)
1165       // don't bother scanning the rest.
1166       return SE_Fixed8;
1167   }
1168   if (isChar6)
1169     return SE_Char6;
1170   return SE_Fixed7;
1171 }
1172 
1173 /// Emit top-level description of module, including target triple, inline asm,
1174 /// descriptors for global variables, and function prototype info.
1175 /// Returns the bit offset to backpatch with the location of the real VST.
1176 void ModuleBitcodeWriter::writeModuleInfo() {
1177   // Emit various pieces of data attached to a module.
1178   if (!M.getTargetTriple().empty())
1179     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1180                       0 /*TODO*/);
1181   const std::string &DL = M.getDataLayoutStr();
1182   if (!DL.empty())
1183     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1184   if (!M.getModuleInlineAsm().empty())
1185     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1186                       0 /*TODO*/);
1187 
1188   // Emit information about sections and GC, computing how many there are. Also
1189   // compute the maximum alignment value.
1190   std::map<std::string, unsigned> SectionMap;
1191   std::map<std::string, unsigned> GCMap;
1192   MaybeAlign MaxAlignment;
1193   unsigned MaxGlobalType = 0;
1194   const auto UpdateMaxAlignment = [&MaxAlignment](const MaybeAlign A) {
1195     if (A)
1196       MaxAlignment = !MaxAlignment ? *A : std::max(*MaxAlignment, *A);
1197   };
1198   for (const GlobalVariable &GV : M.globals()) {
1199     UpdateMaxAlignment(GV.getAlign());
1200     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1201     if (GV.hasSection()) {
1202       // Give section names unique ID's.
1203       unsigned &Entry = SectionMap[std::string(GV.getSection())];
1204       if (!Entry) {
1205         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1206                           0 /*TODO*/);
1207         Entry = SectionMap.size();
1208       }
1209     }
1210   }
1211   for (const Function &F : M) {
1212     UpdateMaxAlignment(F.getAlign());
1213     if (F.hasSection()) {
1214       // Give section names unique ID's.
1215       unsigned &Entry = SectionMap[std::string(F.getSection())];
1216       if (!Entry) {
1217         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1218                           0 /*TODO*/);
1219         Entry = SectionMap.size();
1220       }
1221     }
1222     if (F.hasGC()) {
1223       // Same for GC names.
1224       unsigned &Entry = GCMap[F.getGC()];
1225       if (!Entry) {
1226         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1227                           0 /*TODO*/);
1228         Entry = GCMap.size();
1229       }
1230     }
1231   }
1232 
1233   // Emit abbrev for globals, now that we know # sections and max alignment.
1234   unsigned SimpleGVarAbbrev = 0;
1235   if (!M.global_empty()) {
1236     // Add an abbrev for common globals with no visibility or thread localness.
1237     auto Abbv = std::make_shared<BitCodeAbbrev>();
1238     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1239     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1240     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1241     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1242                               Log2_32_Ceil(MaxGlobalType+1)));
1243     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1244                                                            //| explicitType << 1
1245                                                            //| constant
1246     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1247     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1248     if (!MaxAlignment)                                     // Alignment.
1249       Abbv->Add(BitCodeAbbrevOp(0));
1250     else {
1251       unsigned MaxEncAlignment = getEncodedAlign(MaxAlignment);
1252       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1253                                Log2_32_Ceil(MaxEncAlignment+1)));
1254     }
1255     if (SectionMap.empty())                                    // Section.
1256       Abbv->Add(BitCodeAbbrevOp(0));
1257     else
1258       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1259                                Log2_32_Ceil(SectionMap.size()+1)));
1260     // Don't bother emitting vis + thread local.
1261     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1262   }
1263 
1264   SmallVector<unsigned, 64> Vals;
1265   // Emit the module's source file name.
1266   {
1267     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1268     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1269     if (Bits == SE_Char6)
1270       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1271     else if (Bits == SE_Fixed7)
1272       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1273 
1274     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1275     auto Abbv = std::make_shared<BitCodeAbbrev>();
1276     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1277     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1278     Abbv->Add(AbbrevOpToUse);
1279     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1280 
1281     for (const auto P : M.getSourceFileName())
1282       Vals.push_back((unsigned char)P);
1283 
1284     // Emit the finished record.
1285     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1286     Vals.clear();
1287   }
1288 
1289   // Emit the global variable information.
1290   for (const GlobalVariable &GV : M.globals()) {
1291     unsigned AbbrevToUse = 0;
1292 
1293     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1294     //             linkage, alignment, section, visibility, threadlocal,
1295     //             unnamed_addr, externally_initialized, dllstorageclass,
1296     //             comdat, attributes, DSO_Local]
1297     Vals.push_back(addToStrtab(GV.getName()));
1298     Vals.push_back(GV.getName().size());
1299     Vals.push_back(VE.getTypeID(GV.getValueType()));
1300     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1301     Vals.push_back(GV.isDeclaration() ? 0 :
1302                    (VE.getValueID(GV.getInitializer()) + 1));
1303     Vals.push_back(getEncodedLinkage(GV));
1304     Vals.push_back(getEncodedAlign(GV.getAlign()));
1305     Vals.push_back(GV.hasSection() ? SectionMap[std::string(GV.getSection())]
1306                                    : 0);
1307     if (GV.isThreadLocal() ||
1308         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1309         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1310         GV.isExternallyInitialized() ||
1311         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1312         GV.hasComdat() ||
1313         GV.hasAttributes() ||
1314         GV.isDSOLocal() ||
1315         GV.hasPartition()) {
1316       Vals.push_back(getEncodedVisibility(GV));
1317       Vals.push_back(getEncodedThreadLocalMode(GV));
1318       Vals.push_back(getEncodedUnnamedAddr(GV));
1319       Vals.push_back(GV.isExternallyInitialized());
1320       Vals.push_back(getEncodedDLLStorageClass(GV));
1321       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1322 
1323       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1324       Vals.push_back(VE.getAttributeListID(AL));
1325 
1326       Vals.push_back(GV.isDSOLocal());
1327       Vals.push_back(addToStrtab(GV.getPartition()));
1328       Vals.push_back(GV.getPartition().size());
1329     } else {
1330       AbbrevToUse = SimpleGVarAbbrev;
1331     }
1332 
1333     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1334     Vals.clear();
1335   }
1336 
1337   // Emit the function proto information.
1338   for (const Function &F : M) {
1339     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1340     //             linkage, paramattrs, alignment, section, visibility, gc,
1341     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1342     //             prefixdata, personalityfn, DSO_Local, addrspace]
1343     Vals.push_back(addToStrtab(F.getName()));
1344     Vals.push_back(F.getName().size());
1345     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1346     Vals.push_back(F.getCallingConv());
1347     Vals.push_back(F.isDeclaration());
1348     Vals.push_back(getEncodedLinkage(F));
1349     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1350     Vals.push_back(getEncodedAlign(F.getAlign()));
1351     Vals.push_back(F.hasSection() ? SectionMap[std::string(F.getSection())]
1352                                   : 0);
1353     Vals.push_back(getEncodedVisibility(F));
1354     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1355     Vals.push_back(getEncodedUnnamedAddr(F));
1356     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1357                                        : 0);
1358     Vals.push_back(getEncodedDLLStorageClass(F));
1359     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1360     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1361                                      : 0);
1362     Vals.push_back(
1363         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1364 
1365     Vals.push_back(F.isDSOLocal());
1366     Vals.push_back(F.getAddressSpace());
1367     Vals.push_back(addToStrtab(F.getPartition()));
1368     Vals.push_back(F.getPartition().size());
1369 
1370     unsigned AbbrevToUse = 0;
1371     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1372     Vals.clear();
1373   }
1374 
1375   // Emit the alias information.
1376   for (const GlobalAlias &A : M.aliases()) {
1377     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1378     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1379     //         DSO_Local]
1380     Vals.push_back(addToStrtab(A.getName()));
1381     Vals.push_back(A.getName().size());
1382     Vals.push_back(VE.getTypeID(A.getValueType()));
1383     Vals.push_back(A.getType()->getAddressSpace());
1384     Vals.push_back(VE.getValueID(A.getAliasee()));
1385     Vals.push_back(getEncodedLinkage(A));
1386     Vals.push_back(getEncodedVisibility(A));
1387     Vals.push_back(getEncodedDLLStorageClass(A));
1388     Vals.push_back(getEncodedThreadLocalMode(A));
1389     Vals.push_back(getEncodedUnnamedAddr(A));
1390     Vals.push_back(A.isDSOLocal());
1391     Vals.push_back(addToStrtab(A.getPartition()));
1392     Vals.push_back(A.getPartition().size());
1393 
1394     unsigned AbbrevToUse = 0;
1395     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1396     Vals.clear();
1397   }
1398 
1399   // Emit the ifunc information.
1400   for (const GlobalIFunc &I : M.ifuncs()) {
1401     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1402     //         val#, linkage, visibility, DSO_Local]
1403     Vals.push_back(addToStrtab(I.getName()));
1404     Vals.push_back(I.getName().size());
1405     Vals.push_back(VE.getTypeID(I.getValueType()));
1406     Vals.push_back(I.getType()->getAddressSpace());
1407     Vals.push_back(VE.getValueID(I.getResolver()));
1408     Vals.push_back(getEncodedLinkage(I));
1409     Vals.push_back(getEncodedVisibility(I));
1410     Vals.push_back(I.isDSOLocal());
1411     Vals.push_back(addToStrtab(I.getPartition()));
1412     Vals.push_back(I.getPartition().size());
1413     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1414     Vals.clear();
1415   }
1416 
1417   writeValueSymbolTableForwardDecl();
1418 }
1419 
1420 static uint64_t getOptimizationFlags(const Value *V) {
1421   uint64_t Flags = 0;
1422 
1423   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1424     if (OBO->hasNoSignedWrap())
1425       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1426     if (OBO->hasNoUnsignedWrap())
1427       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1428   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1429     if (PEO->isExact())
1430       Flags |= 1 << bitc::PEO_EXACT;
1431   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1432     if (FPMO->hasAllowReassoc())
1433       Flags |= bitc::AllowReassoc;
1434     if (FPMO->hasNoNaNs())
1435       Flags |= bitc::NoNaNs;
1436     if (FPMO->hasNoInfs())
1437       Flags |= bitc::NoInfs;
1438     if (FPMO->hasNoSignedZeros())
1439       Flags |= bitc::NoSignedZeros;
1440     if (FPMO->hasAllowReciprocal())
1441       Flags |= bitc::AllowReciprocal;
1442     if (FPMO->hasAllowContract())
1443       Flags |= bitc::AllowContract;
1444     if (FPMO->hasApproxFunc())
1445       Flags |= bitc::ApproxFunc;
1446   }
1447 
1448   return Flags;
1449 }
1450 
1451 void ModuleBitcodeWriter::writeValueAsMetadata(
1452     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1453   // Mimic an MDNode with a value as one operand.
1454   Value *V = MD->getValue();
1455   Record.push_back(VE.getTypeID(V->getType()));
1456   Record.push_back(VE.getValueID(V));
1457   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1458   Record.clear();
1459 }
1460 
1461 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1462                                        SmallVectorImpl<uint64_t> &Record,
1463                                        unsigned Abbrev) {
1464   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1465     Metadata *MD = N->getOperand(i);
1466     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1467            "Unexpected function-local metadata");
1468     Record.push_back(VE.getMetadataOrNullID(MD));
1469   }
1470   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1471                                     : bitc::METADATA_NODE,
1472                     Record, Abbrev);
1473   Record.clear();
1474 }
1475 
1476 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1477   // Assume the column is usually under 128, and always output the inlined-at
1478   // location (it's never more expensive than building an array size 1).
1479   auto Abbv = std::make_shared<BitCodeAbbrev>();
1480   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1481   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1482   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1483   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1484   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1485   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1486   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1487   return Stream.EmitAbbrev(std::move(Abbv));
1488 }
1489 
1490 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1491                                           SmallVectorImpl<uint64_t> &Record,
1492                                           unsigned &Abbrev) {
1493   if (!Abbrev)
1494     Abbrev = createDILocationAbbrev();
1495 
1496   Record.push_back(N->isDistinct());
1497   Record.push_back(N->getLine());
1498   Record.push_back(N->getColumn());
1499   Record.push_back(VE.getMetadataID(N->getScope()));
1500   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1501   Record.push_back(N->isImplicitCode());
1502 
1503   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1504   Record.clear();
1505 }
1506 
1507 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1508   // Assume the column is usually under 128, and always output the inlined-at
1509   // location (it's never more expensive than building an array size 1).
1510   auto Abbv = std::make_shared<BitCodeAbbrev>();
1511   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1512   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1513   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1514   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1515   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1516   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1517   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1518   return Stream.EmitAbbrev(std::move(Abbv));
1519 }
1520 
1521 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1522                                              SmallVectorImpl<uint64_t> &Record,
1523                                              unsigned &Abbrev) {
1524   if (!Abbrev)
1525     Abbrev = createGenericDINodeAbbrev();
1526 
1527   Record.push_back(N->isDistinct());
1528   Record.push_back(N->getTag());
1529   Record.push_back(0); // Per-tag version field; unused for now.
1530 
1531   for (auto &I : N->operands())
1532     Record.push_back(VE.getMetadataOrNullID(I));
1533 
1534   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1535   Record.clear();
1536 }
1537 
1538 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1539                                           SmallVectorImpl<uint64_t> &Record,
1540                                           unsigned Abbrev) {
1541   const uint64_t Version = 2 << 1;
1542   Record.push_back((uint64_t)N->isDistinct() | Version);
1543   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1544   Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
1545   Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
1546   Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
1547 
1548   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1549   Record.clear();
1550 }
1551 
1552 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1553   if ((int64_t)V >= 0)
1554     Vals.push_back(V << 1);
1555   else
1556     Vals.push_back((-V << 1) | 1);
1557 }
1558 
1559 static void emitWideAPInt(SmallVectorImpl<uint64_t> &Vals, const APInt &A) {
1560   // We have an arbitrary precision integer value to write whose
1561   // bit width is > 64. However, in canonical unsigned integer
1562   // format it is likely that the high bits are going to be zero.
1563   // So, we only write the number of active words.
1564   unsigned NumWords = A.getActiveWords();
1565   const uint64_t *RawData = A.getRawData();
1566   for (unsigned i = 0; i < NumWords; i++)
1567     emitSignedInt64(Vals, RawData[i]);
1568 }
1569 
1570 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1571                                             SmallVectorImpl<uint64_t> &Record,
1572                                             unsigned Abbrev) {
1573   const uint64_t IsBigInt = 1 << 2;
1574   Record.push_back(IsBigInt | (N->isUnsigned() << 1) | N->isDistinct());
1575   Record.push_back(N->getValue().getBitWidth());
1576   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1577   emitWideAPInt(Record, N->getValue());
1578 
1579   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1580   Record.clear();
1581 }
1582 
1583 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1584                                            SmallVectorImpl<uint64_t> &Record,
1585                                            unsigned Abbrev) {
1586   Record.push_back(N->isDistinct());
1587   Record.push_back(N->getTag());
1588   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1589   Record.push_back(N->getSizeInBits());
1590   Record.push_back(N->getAlignInBits());
1591   Record.push_back(N->getEncoding());
1592   Record.push_back(N->getFlags());
1593 
1594   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1595   Record.clear();
1596 }
1597 
1598 void ModuleBitcodeWriter::writeDIStringType(const DIStringType *N,
1599                                             SmallVectorImpl<uint64_t> &Record,
1600                                             unsigned Abbrev) {
1601   Record.push_back(N->isDistinct());
1602   Record.push_back(N->getTag());
1603   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1604   Record.push_back(VE.getMetadataOrNullID(N->getStringLength()));
1605   Record.push_back(VE.getMetadataOrNullID(N->getStringLengthExp()));
1606   Record.push_back(N->getSizeInBits());
1607   Record.push_back(N->getAlignInBits());
1608   Record.push_back(N->getEncoding());
1609 
1610   Stream.EmitRecord(bitc::METADATA_STRING_TYPE, Record, Abbrev);
1611   Record.clear();
1612 }
1613 
1614 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1615                                              SmallVectorImpl<uint64_t> &Record,
1616                                              unsigned Abbrev) {
1617   Record.push_back(N->isDistinct());
1618   Record.push_back(N->getTag());
1619   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1620   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1621   Record.push_back(N->getLine());
1622   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1623   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1624   Record.push_back(N->getSizeInBits());
1625   Record.push_back(N->getAlignInBits());
1626   Record.push_back(N->getOffsetInBits());
1627   Record.push_back(N->getFlags());
1628   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1629 
1630   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1631   // that there is no DWARF address space associated with DIDerivedType.
1632   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1633     Record.push_back(*DWARFAddressSpace + 1);
1634   else
1635     Record.push_back(0);
1636 
1637   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1638   Record.clear();
1639 }
1640 
1641 void ModuleBitcodeWriter::writeDICompositeType(
1642     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1643     unsigned Abbrev) {
1644   const unsigned IsNotUsedInOldTypeRef = 0x2;
1645   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1646   Record.push_back(N->getTag());
1647   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1648   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1649   Record.push_back(N->getLine());
1650   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1651   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1652   Record.push_back(N->getSizeInBits());
1653   Record.push_back(N->getAlignInBits());
1654   Record.push_back(N->getOffsetInBits());
1655   Record.push_back(N->getFlags());
1656   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1657   Record.push_back(N->getRuntimeLang());
1658   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1659   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1660   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1661   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1662   Record.push_back(VE.getMetadataOrNullID(N->getRawDataLocation()));
1663   Record.push_back(VE.getMetadataOrNullID(N->getRawAssociated()));
1664   Record.push_back(VE.getMetadataOrNullID(N->getRawAllocated()));
1665   Record.push_back(VE.getMetadataOrNullID(N->getRawRank()));
1666 
1667   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1668   Record.clear();
1669 }
1670 
1671 void ModuleBitcodeWriter::writeDISubroutineType(
1672     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1673     unsigned Abbrev) {
1674   const unsigned HasNoOldTypeRefs = 0x2;
1675   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1676   Record.push_back(N->getFlags());
1677   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1678   Record.push_back(N->getCC());
1679 
1680   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1681   Record.clear();
1682 }
1683 
1684 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1685                                       SmallVectorImpl<uint64_t> &Record,
1686                                       unsigned Abbrev) {
1687   Record.push_back(N->isDistinct());
1688   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1689   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1690   if (N->getRawChecksum()) {
1691     Record.push_back(N->getRawChecksum()->Kind);
1692     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1693   } else {
1694     // Maintain backwards compatibility with the old internal representation of
1695     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1696     Record.push_back(0);
1697     Record.push_back(VE.getMetadataOrNullID(nullptr));
1698   }
1699   auto Source = N->getRawSource();
1700   if (Source)
1701     Record.push_back(VE.getMetadataOrNullID(*Source));
1702 
1703   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1704   Record.clear();
1705 }
1706 
1707 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1708                                              SmallVectorImpl<uint64_t> &Record,
1709                                              unsigned Abbrev) {
1710   assert(N->isDistinct() && "Expected distinct compile units");
1711   Record.push_back(/* IsDistinct */ true);
1712   Record.push_back(N->getSourceLanguage());
1713   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1714   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1715   Record.push_back(N->isOptimized());
1716   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1717   Record.push_back(N->getRuntimeVersion());
1718   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1719   Record.push_back(N->getEmissionKind());
1720   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1721   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1722   Record.push_back(/* subprograms */ 0);
1723   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1724   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1725   Record.push_back(N->getDWOId());
1726   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1727   Record.push_back(N->getSplitDebugInlining());
1728   Record.push_back(N->getDebugInfoForProfiling());
1729   Record.push_back((unsigned)N->getNameTableKind());
1730   Record.push_back(N->getRangesBaseAddress());
1731   Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
1732   Record.push_back(VE.getMetadataOrNullID(N->getRawSDK()));
1733 
1734   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1735   Record.clear();
1736 }
1737 
1738 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1739                                             SmallVectorImpl<uint64_t> &Record,
1740                                             unsigned Abbrev) {
1741   const uint64_t HasUnitFlag = 1 << 1;
1742   const uint64_t HasSPFlagsFlag = 1 << 2;
1743   Record.push_back(uint64_t(N->isDistinct()) | HasUnitFlag | HasSPFlagsFlag);
1744   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1745   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1746   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1747   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1748   Record.push_back(N->getLine());
1749   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1750   Record.push_back(N->getScopeLine());
1751   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1752   Record.push_back(N->getSPFlags());
1753   Record.push_back(N->getVirtualIndex());
1754   Record.push_back(N->getFlags());
1755   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1756   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1757   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1758   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1759   Record.push_back(N->getThisAdjustment());
1760   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1761 
1762   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1763   Record.clear();
1764 }
1765 
1766 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1767                                               SmallVectorImpl<uint64_t> &Record,
1768                                               unsigned Abbrev) {
1769   Record.push_back(N->isDistinct());
1770   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1771   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1772   Record.push_back(N->getLine());
1773   Record.push_back(N->getColumn());
1774 
1775   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1776   Record.clear();
1777 }
1778 
1779 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1780     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1781     unsigned Abbrev) {
1782   Record.push_back(N->isDistinct());
1783   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1784   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1785   Record.push_back(N->getDiscriminator());
1786 
1787   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1788   Record.clear();
1789 }
1790 
1791 void ModuleBitcodeWriter::writeDICommonBlock(const DICommonBlock *N,
1792                                              SmallVectorImpl<uint64_t> &Record,
1793                                              unsigned Abbrev) {
1794   Record.push_back(N->isDistinct());
1795   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1796   Record.push_back(VE.getMetadataOrNullID(N->getDecl()));
1797   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1798   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1799   Record.push_back(N->getLineNo());
1800 
1801   Stream.EmitRecord(bitc::METADATA_COMMON_BLOCK, Record, Abbrev);
1802   Record.clear();
1803 }
1804 
1805 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1806                                            SmallVectorImpl<uint64_t> &Record,
1807                                            unsigned Abbrev) {
1808   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1809   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1810   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1811 
1812   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1813   Record.clear();
1814 }
1815 
1816 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1817                                        SmallVectorImpl<uint64_t> &Record,
1818                                        unsigned Abbrev) {
1819   Record.push_back(N->isDistinct());
1820   Record.push_back(N->getMacinfoType());
1821   Record.push_back(N->getLine());
1822   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1823   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1824 
1825   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1826   Record.clear();
1827 }
1828 
1829 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1830                                            SmallVectorImpl<uint64_t> &Record,
1831                                            unsigned Abbrev) {
1832   Record.push_back(N->isDistinct());
1833   Record.push_back(N->getMacinfoType());
1834   Record.push_back(N->getLine());
1835   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1836   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1837 
1838   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1839   Record.clear();
1840 }
1841 
1842 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1843                                         SmallVectorImpl<uint64_t> &Record,
1844                                         unsigned Abbrev) {
1845   Record.push_back(N->isDistinct());
1846   for (auto &I : N->operands())
1847     Record.push_back(VE.getMetadataOrNullID(I));
1848   Record.push_back(N->getLineNo());
1849 
1850   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1851   Record.clear();
1852 }
1853 
1854 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1855     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1856     unsigned Abbrev) {
1857   Record.push_back(N->isDistinct());
1858   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1859   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1860   Record.push_back(N->isDefault());
1861 
1862   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1863   Record.clear();
1864 }
1865 
1866 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1867     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1868     unsigned Abbrev) {
1869   Record.push_back(N->isDistinct());
1870   Record.push_back(N->getTag());
1871   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1872   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1873   Record.push_back(N->isDefault());
1874   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1875 
1876   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1877   Record.clear();
1878 }
1879 
1880 void ModuleBitcodeWriter::writeDIGlobalVariable(
1881     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1882     unsigned Abbrev) {
1883   const uint64_t Version = 2 << 1;
1884   Record.push_back((uint64_t)N->isDistinct() | Version);
1885   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1886   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1887   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1888   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1889   Record.push_back(N->getLine());
1890   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1891   Record.push_back(N->isLocalToUnit());
1892   Record.push_back(N->isDefinition());
1893   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1894   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
1895   Record.push_back(N->getAlignInBits());
1896 
1897   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1898   Record.clear();
1899 }
1900 
1901 void ModuleBitcodeWriter::writeDILocalVariable(
1902     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1903     unsigned Abbrev) {
1904   // In order to support all possible bitcode formats in BitcodeReader we need
1905   // to distinguish the following cases:
1906   // 1) Record has no artificial tag (Record[1]),
1907   //   has no obsolete inlinedAt field (Record[9]).
1908   //   In this case Record size will be 8, HasAlignment flag is false.
1909   // 2) Record has artificial tag (Record[1]),
1910   //   has no obsolete inlignedAt field (Record[9]).
1911   //   In this case Record size will be 9, HasAlignment flag is false.
1912   // 3) Record has both artificial tag (Record[1]) and
1913   //   obsolete inlignedAt field (Record[9]).
1914   //   In this case Record size will be 10, HasAlignment flag is false.
1915   // 4) Record has neither artificial tag, nor inlignedAt field, but
1916   //   HasAlignment flag is true and Record[8] contains alignment value.
1917   const uint64_t HasAlignmentFlag = 1 << 1;
1918   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1919   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1920   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1921   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1922   Record.push_back(N->getLine());
1923   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1924   Record.push_back(N->getArg());
1925   Record.push_back(N->getFlags());
1926   Record.push_back(N->getAlignInBits());
1927 
1928   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1929   Record.clear();
1930 }
1931 
1932 void ModuleBitcodeWriter::writeDILabel(
1933     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
1934     unsigned Abbrev) {
1935   Record.push_back((uint64_t)N->isDistinct());
1936   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1937   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1938   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1939   Record.push_back(N->getLine());
1940 
1941   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
1942   Record.clear();
1943 }
1944 
1945 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1946                                             SmallVectorImpl<uint64_t> &Record,
1947                                             unsigned Abbrev) {
1948   Record.reserve(N->getElements().size() + 1);
1949   const uint64_t Version = 3 << 1;
1950   Record.push_back((uint64_t)N->isDistinct() | Version);
1951   Record.append(N->elements_begin(), N->elements_end());
1952 
1953   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1954   Record.clear();
1955 }
1956 
1957 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1958     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1959     unsigned Abbrev) {
1960   Record.push_back(N->isDistinct());
1961   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1962   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1963 
1964   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1965   Record.clear();
1966 }
1967 
1968 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1969                                               SmallVectorImpl<uint64_t> &Record,
1970                                               unsigned Abbrev) {
1971   Record.push_back(N->isDistinct());
1972   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1973   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1974   Record.push_back(N->getLine());
1975   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1976   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1977   Record.push_back(N->getAttributes());
1978   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1979 
1980   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1981   Record.clear();
1982 }
1983 
1984 void ModuleBitcodeWriter::writeDIImportedEntity(
1985     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1986     unsigned Abbrev) {
1987   Record.push_back(N->isDistinct());
1988   Record.push_back(N->getTag());
1989   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1990   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1991   Record.push_back(N->getLine());
1992   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1993   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1994 
1995   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1996   Record.clear();
1997 }
1998 
1999 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
2000   auto Abbv = std::make_shared<BitCodeAbbrev>();
2001   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
2002   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2003   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2004   return Stream.EmitAbbrev(std::move(Abbv));
2005 }
2006 
2007 void ModuleBitcodeWriter::writeNamedMetadata(
2008     SmallVectorImpl<uint64_t> &Record) {
2009   if (M.named_metadata_empty())
2010     return;
2011 
2012   unsigned Abbrev = createNamedMetadataAbbrev();
2013   for (const NamedMDNode &NMD : M.named_metadata()) {
2014     // Write name.
2015     StringRef Str = NMD.getName();
2016     Record.append(Str.bytes_begin(), Str.bytes_end());
2017     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
2018     Record.clear();
2019 
2020     // Write named metadata operands.
2021     for (const MDNode *N : NMD.operands())
2022       Record.push_back(VE.getMetadataID(N));
2023     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
2024     Record.clear();
2025   }
2026 }
2027 
2028 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
2029   auto Abbv = std::make_shared<BitCodeAbbrev>();
2030   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
2031   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
2032   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
2033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2034   return Stream.EmitAbbrev(std::move(Abbv));
2035 }
2036 
2037 /// Write out a record for MDString.
2038 ///
2039 /// All the metadata strings in a metadata block are emitted in a single
2040 /// record.  The sizes and strings themselves are shoved into a blob.
2041 void ModuleBitcodeWriter::writeMetadataStrings(
2042     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
2043   if (Strings.empty())
2044     return;
2045 
2046   // Start the record with the number of strings.
2047   Record.push_back(bitc::METADATA_STRINGS);
2048   Record.push_back(Strings.size());
2049 
2050   // Emit the sizes of the strings in the blob.
2051   SmallString<256> Blob;
2052   {
2053     BitstreamWriter W(Blob);
2054     for (const Metadata *MD : Strings)
2055       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
2056     W.FlushToWord();
2057   }
2058 
2059   // Add the offset to the strings to the record.
2060   Record.push_back(Blob.size());
2061 
2062   // Add the strings to the blob.
2063   for (const Metadata *MD : Strings)
2064     Blob.append(cast<MDString>(MD)->getString());
2065 
2066   // Emit the final record.
2067   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
2068   Record.clear();
2069 }
2070 
2071 // Generates an enum to use as an index in the Abbrev array of Metadata record.
2072 enum MetadataAbbrev : unsigned {
2073 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
2074 #include "llvm/IR/Metadata.def"
2075   LastPlusOne
2076 };
2077 
2078 void ModuleBitcodeWriter::writeMetadataRecords(
2079     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
2080     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
2081   if (MDs.empty())
2082     return;
2083 
2084   // Initialize MDNode abbreviations.
2085 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
2086 #include "llvm/IR/Metadata.def"
2087 
2088   for (const Metadata *MD : MDs) {
2089     if (IndexPos)
2090       IndexPos->push_back(Stream.GetCurrentBitNo());
2091     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
2092       assert(N->isResolved() && "Expected forward references to be resolved");
2093 
2094       switch (N->getMetadataID()) {
2095       default:
2096         llvm_unreachable("Invalid MDNode subclass");
2097 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
2098   case Metadata::CLASS##Kind:                                                  \
2099     if (MDAbbrevs)                                                             \
2100       write##CLASS(cast<CLASS>(N), Record,                                     \
2101                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
2102     else                                                                       \
2103       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
2104     continue;
2105 #include "llvm/IR/Metadata.def"
2106       }
2107     }
2108     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
2109   }
2110 }
2111 
2112 void ModuleBitcodeWriter::writeModuleMetadata() {
2113   if (!VE.hasMDs() && M.named_metadata_empty())
2114     return;
2115 
2116   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
2117   SmallVector<uint64_t, 64> Record;
2118 
2119   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
2120   // block and load any metadata.
2121   std::vector<unsigned> MDAbbrevs;
2122 
2123   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
2124   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
2125   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
2126       createGenericDINodeAbbrev();
2127 
2128   auto Abbv = std::make_shared<BitCodeAbbrev>();
2129   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
2130   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2131   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2132   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2133 
2134   Abbv = std::make_shared<BitCodeAbbrev>();
2135   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
2136   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2137   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2138   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2139 
2140   // Emit MDStrings together upfront.
2141   writeMetadataStrings(VE.getMDStrings(), Record);
2142 
2143   // We only emit an index for the metadata record if we have more than a given
2144   // (naive) threshold of metadatas, otherwise it is not worth it.
2145   if (VE.getNonMDStrings().size() > IndexThreshold) {
2146     // Write a placeholder value in for the offset of the metadata index,
2147     // which is written after the records, so that it can include
2148     // the offset of each entry. The placeholder offset will be
2149     // updated after all records are emitted.
2150     uint64_t Vals[] = {0, 0};
2151     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2152   }
2153 
2154   // Compute and save the bit offset to the current position, which will be
2155   // patched when we emit the index later. We can simply subtract the 64-bit
2156   // fixed size from the current bit number to get the location to backpatch.
2157   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2158 
2159   // This index will contain the bitpos for each individual record.
2160   std::vector<uint64_t> IndexPos;
2161   IndexPos.reserve(VE.getNonMDStrings().size());
2162 
2163   // Write all the records
2164   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2165 
2166   if (VE.getNonMDStrings().size() > IndexThreshold) {
2167     // Now that we have emitted all the records we will emit the index. But
2168     // first
2169     // backpatch the forward reference so that the reader can skip the records
2170     // efficiently.
2171     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2172                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2173 
2174     // Delta encode the index.
2175     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2176     for (auto &Elt : IndexPos) {
2177       auto EltDelta = Elt - PreviousValue;
2178       PreviousValue = Elt;
2179       Elt = EltDelta;
2180     }
2181     // Emit the index record.
2182     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2183     IndexPos.clear();
2184   }
2185 
2186   // Write the named metadata now.
2187   writeNamedMetadata(Record);
2188 
2189   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2190     SmallVector<uint64_t, 4> Record;
2191     Record.push_back(VE.getValueID(&GO));
2192     pushGlobalMetadataAttachment(Record, GO);
2193     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2194   };
2195   for (const Function &F : M)
2196     if (F.isDeclaration() && F.hasMetadata())
2197       AddDeclAttachedMetadata(F);
2198   // FIXME: Only store metadata for declarations here, and move data for global
2199   // variable definitions to a separate block (PR28134).
2200   for (const GlobalVariable &GV : M.globals())
2201     if (GV.hasMetadata())
2202       AddDeclAttachedMetadata(GV);
2203 
2204   Stream.ExitBlock();
2205 }
2206 
2207 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2208   if (!VE.hasMDs())
2209     return;
2210 
2211   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2212   SmallVector<uint64_t, 64> Record;
2213   writeMetadataStrings(VE.getMDStrings(), Record);
2214   writeMetadataRecords(VE.getNonMDStrings(), Record);
2215   Stream.ExitBlock();
2216 }
2217 
2218 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2219     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2220   // [n x [id, mdnode]]
2221   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2222   GO.getAllMetadata(MDs);
2223   for (const auto &I : MDs) {
2224     Record.push_back(I.first);
2225     Record.push_back(VE.getMetadataID(I.second));
2226   }
2227 }
2228 
2229 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2230   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2231 
2232   SmallVector<uint64_t, 64> Record;
2233 
2234   if (F.hasMetadata()) {
2235     pushGlobalMetadataAttachment(Record, F);
2236     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2237     Record.clear();
2238   }
2239 
2240   // Write metadata attachments
2241   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2242   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2243   for (const BasicBlock &BB : F)
2244     for (const Instruction &I : BB) {
2245       MDs.clear();
2246       I.getAllMetadataOtherThanDebugLoc(MDs);
2247 
2248       // If no metadata, ignore instruction.
2249       if (MDs.empty()) continue;
2250 
2251       Record.push_back(VE.getInstructionID(&I));
2252 
2253       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2254         Record.push_back(MDs[i].first);
2255         Record.push_back(VE.getMetadataID(MDs[i].second));
2256       }
2257       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2258       Record.clear();
2259     }
2260 
2261   Stream.ExitBlock();
2262 }
2263 
2264 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2265   SmallVector<uint64_t, 64> Record;
2266 
2267   // Write metadata kinds
2268   // METADATA_KIND - [n x [id, name]]
2269   SmallVector<StringRef, 8> Names;
2270   M.getMDKindNames(Names);
2271 
2272   if (Names.empty()) return;
2273 
2274   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2275 
2276   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2277     Record.push_back(MDKindID);
2278     StringRef KName = Names[MDKindID];
2279     Record.append(KName.begin(), KName.end());
2280 
2281     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2282     Record.clear();
2283   }
2284 
2285   Stream.ExitBlock();
2286 }
2287 
2288 void ModuleBitcodeWriter::writeOperandBundleTags() {
2289   // Write metadata kinds
2290   //
2291   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2292   //
2293   // OPERAND_BUNDLE_TAG - [strchr x N]
2294 
2295   SmallVector<StringRef, 8> Tags;
2296   M.getOperandBundleTags(Tags);
2297 
2298   if (Tags.empty())
2299     return;
2300 
2301   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2302 
2303   SmallVector<uint64_t, 64> Record;
2304 
2305   for (auto Tag : Tags) {
2306     Record.append(Tag.begin(), Tag.end());
2307 
2308     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2309     Record.clear();
2310   }
2311 
2312   Stream.ExitBlock();
2313 }
2314 
2315 void ModuleBitcodeWriter::writeSyncScopeNames() {
2316   SmallVector<StringRef, 8> SSNs;
2317   M.getContext().getSyncScopeNames(SSNs);
2318   if (SSNs.empty())
2319     return;
2320 
2321   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2322 
2323   SmallVector<uint64_t, 64> Record;
2324   for (auto SSN : SSNs) {
2325     Record.append(SSN.begin(), SSN.end());
2326     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2327     Record.clear();
2328   }
2329 
2330   Stream.ExitBlock();
2331 }
2332 
2333 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2334                                          bool isGlobal) {
2335   if (FirstVal == LastVal) return;
2336 
2337   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2338 
2339   unsigned AggregateAbbrev = 0;
2340   unsigned String8Abbrev = 0;
2341   unsigned CString7Abbrev = 0;
2342   unsigned CString6Abbrev = 0;
2343   // If this is a constant pool for the module, emit module-specific abbrevs.
2344   if (isGlobal) {
2345     // Abbrev for CST_CODE_AGGREGATE.
2346     auto Abbv = std::make_shared<BitCodeAbbrev>();
2347     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2348     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2349     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2350     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2351 
2352     // Abbrev for CST_CODE_STRING.
2353     Abbv = std::make_shared<BitCodeAbbrev>();
2354     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2355     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2356     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2357     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2358     // Abbrev for CST_CODE_CSTRING.
2359     Abbv = std::make_shared<BitCodeAbbrev>();
2360     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2361     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2362     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2363     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2364     // Abbrev for CST_CODE_CSTRING.
2365     Abbv = std::make_shared<BitCodeAbbrev>();
2366     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2367     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2368     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2369     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2370   }
2371 
2372   SmallVector<uint64_t, 64> Record;
2373 
2374   const ValueEnumerator::ValueList &Vals = VE.getValues();
2375   Type *LastTy = nullptr;
2376   for (unsigned i = FirstVal; i != LastVal; ++i) {
2377     const Value *V = Vals[i].first;
2378     // If we need to switch types, do so now.
2379     if (V->getType() != LastTy) {
2380       LastTy = V->getType();
2381       Record.push_back(VE.getTypeID(LastTy));
2382       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2383                         CONSTANTS_SETTYPE_ABBREV);
2384       Record.clear();
2385     }
2386 
2387     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2388       Record.push_back(unsigned(IA->hasSideEffects()) |
2389                        unsigned(IA->isAlignStack()) << 1 |
2390                        unsigned(IA->getDialect()&1) << 2);
2391 
2392       // Add the asm string.
2393       const std::string &AsmStr = IA->getAsmString();
2394       Record.push_back(AsmStr.size());
2395       Record.append(AsmStr.begin(), AsmStr.end());
2396 
2397       // Add the constraint string.
2398       const std::string &ConstraintStr = IA->getConstraintString();
2399       Record.push_back(ConstraintStr.size());
2400       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2401       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2402       Record.clear();
2403       continue;
2404     }
2405     const Constant *C = cast<Constant>(V);
2406     unsigned Code = -1U;
2407     unsigned AbbrevToUse = 0;
2408     if (C->isNullValue()) {
2409       Code = bitc::CST_CODE_NULL;
2410     } else if (isa<UndefValue>(C)) {
2411       Code = bitc::CST_CODE_UNDEF;
2412     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2413       if (IV->getBitWidth() <= 64) {
2414         uint64_t V = IV->getSExtValue();
2415         emitSignedInt64(Record, V);
2416         Code = bitc::CST_CODE_INTEGER;
2417         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2418       } else {                             // Wide integers, > 64 bits in size.
2419         emitWideAPInt(Record, IV->getValue());
2420         Code = bitc::CST_CODE_WIDE_INTEGER;
2421       }
2422     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2423       Code = bitc::CST_CODE_FLOAT;
2424       Type *Ty = CFP->getType();
2425       if (Ty->isHalfTy() || Ty->isBFloatTy() || Ty->isFloatTy() ||
2426           Ty->isDoubleTy()) {
2427         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2428       } else if (Ty->isX86_FP80Ty()) {
2429         // api needed to prevent premature destruction
2430         // bits are not in the same order as a normal i80 APInt, compensate.
2431         APInt api = CFP->getValueAPF().bitcastToAPInt();
2432         const uint64_t *p = api.getRawData();
2433         Record.push_back((p[1] << 48) | (p[0] >> 16));
2434         Record.push_back(p[0] & 0xffffLL);
2435       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2436         APInt api = CFP->getValueAPF().bitcastToAPInt();
2437         const uint64_t *p = api.getRawData();
2438         Record.push_back(p[0]);
2439         Record.push_back(p[1]);
2440       } else {
2441         assert(0 && "Unknown FP type!");
2442       }
2443     } else if (isa<ConstantDataSequential>(C) &&
2444                cast<ConstantDataSequential>(C)->isString()) {
2445       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2446       // Emit constant strings specially.
2447       unsigned NumElts = Str->getNumElements();
2448       // If this is a null-terminated string, use the denser CSTRING encoding.
2449       if (Str->isCString()) {
2450         Code = bitc::CST_CODE_CSTRING;
2451         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2452       } else {
2453         Code = bitc::CST_CODE_STRING;
2454         AbbrevToUse = String8Abbrev;
2455       }
2456       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2457       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2458       for (unsigned i = 0; i != NumElts; ++i) {
2459         unsigned char V = Str->getElementAsInteger(i);
2460         Record.push_back(V);
2461         isCStr7 &= (V & 128) == 0;
2462         if (isCStrChar6)
2463           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2464       }
2465 
2466       if (isCStrChar6)
2467         AbbrevToUse = CString6Abbrev;
2468       else if (isCStr7)
2469         AbbrevToUse = CString7Abbrev;
2470     } else if (const ConstantDataSequential *CDS =
2471                   dyn_cast<ConstantDataSequential>(C)) {
2472       Code = bitc::CST_CODE_DATA;
2473       Type *EltTy = CDS->getElementType();
2474       if (isa<IntegerType>(EltTy)) {
2475         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2476           Record.push_back(CDS->getElementAsInteger(i));
2477       } else {
2478         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2479           Record.push_back(
2480               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2481       }
2482     } else if (isa<ConstantAggregate>(C)) {
2483       Code = bitc::CST_CODE_AGGREGATE;
2484       for (const Value *Op : C->operands())
2485         Record.push_back(VE.getValueID(Op));
2486       AbbrevToUse = AggregateAbbrev;
2487     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2488       switch (CE->getOpcode()) {
2489       default:
2490         if (Instruction::isCast(CE->getOpcode())) {
2491           Code = bitc::CST_CODE_CE_CAST;
2492           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2493           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2494           Record.push_back(VE.getValueID(C->getOperand(0)));
2495           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2496         } else {
2497           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2498           Code = bitc::CST_CODE_CE_BINOP;
2499           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2500           Record.push_back(VE.getValueID(C->getOperand(0)));
2501           Record.push_back(VE.getValueID(C->getOperand(1)));
2502           uint64_t Flags = getOptimizationFlags(CE);
2503           if (Flags != 0)
2504             Record.push_back(Flags);
2505         }
2506         break;
2507       case Instruction::FNeg: {
2508         assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
2509         Code = bitc::CST_CODE_CE_UNOP;
2510         Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
2511         Record.push_back(VE.getValueID(C->getOperand(0)));
2512         uint64_t Flags = getOptimizationFlags(CE);
2513         if (Flags != 0)
2514           Record.push_back(Flags);
2515         break;
2516       }
2517       case Instruction::GetElementPtr: {
2518         Code = bitc::CST_CODE_CE_GEP;
2519         const auto *GO = cast<GEPOperator>(C);
2520         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2521         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2522           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2523           Record.push_back((*Idx << 1) | GO->isInBounds());
2524         } else if (GO->isInBounds())
2525           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2526         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2527           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2528           Record.push_back(VE.getValueID(C->getOperand(i)));
2529         }
2530         break;
2531       }
2532       case Instruction::Select:
2533         Code = bitc::CST_CODE_CE_SELECT;
2534         Record.push_back(VE.getValueID(C->getOperand(0)));
2535         Record.push_back(VE.getValueID(C->getOperand(1)));
2536         Record.push_back(VE.getValueID(C->getOperand(2)));
2537         break;
2538       case Instruction::ExtractElement:
2539         Code = bitc::CST_CODE_CE_EXTRACTELT;
2540         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2541         Record.push_back(VE.getValueID(C->getOperand(0)));
2542         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2543         Record.push_back(VE.getValueID(C->getOperand(1)));
2544         break;
2545       case Instruction::InsertElement:
2546         Code = bitc::CST_CODE_CE_INSERTELT;
2547         Record.push_back(VE.getValueID(C->getOperand(0)));
2548         Record.push_back(VE.getValueID(C->getOperand(1)));
2549         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2550         Record.push_back(VE.getValueID(C->getOperand(2)));
2551         break;
2552       case Instruction::ShuffleVector:
2553         // If the return type and argument types are the same, this is a
2554         // standard shufflevector instruction.  If the types are different,
2555         // then the shuffle is widening or truncating the input vectors, and
2556         // the argument type must also be encoded.
2557         if (C->getType() == C->getOperand(0)->getType()) {
2558           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2559         } else {
2560           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2561           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2562         }
2563         Record.push_back(VE.getValueID(C->getOperand(0)));
2564         Record.push_back(VE.getValueID(C->getOperand(1)));
2565         Record.push_back(VE.getValueID(CE->getShuffleMaskForBitcode()));
2566         break;
2567       case Instruction::ICmp:
2568       case Instruction::FCmp:
2569         Code = bitc::CST_CODE_CE_CMP;
2570         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2571         Record.push_back(VE.getValueID(C->getOperand(0)));
2572         Record.push_back(VE.getValueID(C->getOperand(1)));
2573         Record.push_back(CE->getPredicate());
2574         break;
2575       }
2576     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2577       Code = bitc::CST_CODE_BLOCKADDRESS;
2578       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2579       Record.push_back(VE.getValueID(BA->getFunction()));
2580       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2581     } else {
2582 #ifndef NDEBUG
2583       C->dump();
2584 #endif
2585       llvm_unreachable("Unknown constant!");
2586     }
2587     Stream.EmitRecord(Code, Record, AbbrevToUse);
2588     Record.clear();
2589   }
2590 
2591   Stream.ExitBlock();
2592 }
2593 
2594 void ModuleBitcodeWriter::writeModuleConstants() {
2595   const ValueEnumerator::ValueList &Vals = VE.getValues();
2596 
2597   // Find the first constant to emit, which is the first non-globalvalue value.
2598   // We know globalvalues have been emitted by WriteModuleInfo.
2599   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2600     if (!isa<GlobalValue>(Vals[i].first)) {
2601       writeConstants(i, Vals.size(), true);
2602       return;
2603     }
2604   }
2605 }
2606 
2607 /// pushValueAndType - The file has to encode both the value and type id for
2608 /// many values, because we need to know what type to create for forward
2609 /// references.  However, most operands are not forward references, so this type
2610 /// field is not needed.
2611 ///
2612 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2613 /// instruction ID, then it is a forward reference, and it also includes the
2614 /// type ID.  The value ID that is written is encoded relative to the InstID.
2615 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2616                                            SmallVectorImpl<unsigned> &Vals) {
2617   unsigned ValID = VE.getValueID(V);
2618   // Make encoding relative to the InstID.
2619   Vals.push_back(InstID - ValID);
2620   if (ValID >= InstID) {
2621     Vals.push_back(VE.getTypeID(V->getType()));
2622     return true;
2623   }
2624   return false;
2625 }
2626 
2627 void ModuleBitcodeWriter::writeOperandBundles(const CallBase &CS,
2628                                               unsigned InstID) {
2629   SmallVector<unsigned, 64> Record;
2630   LLVMContext &C = CS.getContext();
2631 
2632   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2633     const auto &Bundle = CS.getOperandBundleAt(i);
2634     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2635 
2636     for (auto &Input : Bundle.Inputs)
2637       pushValueAndType(Input, InstID, Record);
2638 
2639     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2640     Record.clear();
2641   }
2642 }
2643 
2644 /// pushValue - Like pushValueAndType, but where the type of the value is
2645 /// omitted (perhaps it was already encoded in an earlier operand).
2646 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2647                                     SmallVectorImpl<unsigned> &Vals) {
2648   unsigned ValID = VE.getValueID(V);
2649   Vals.push_back(InstID - ValID);
2650 }
2651 
2652 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2653                                           SmallVectorImpl<uint64_t> &Vals) {
2654   unsigned ValID = VE.getValueID(V);
2655   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2656   emitSignedInt64(Vals, diff);
2657 }
2658 
2659 /// WriteInstruction - Emit an instruction to the specified stream.
2660 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2661                                            unsigned InstID,
2662                                            SmallVectorImpl<unsigned> &Vals) {
2663   unsigned Code = 0;
2664   unsigned AbbrevToUse = 0;
2665   VE.setInstructionID(&I);
2666   switch (I.getOpcode()) {
2667   default:
2668     if (Instruction::isCast(I.getOpcode())) {
2669       Code = bitc::FUNC_CODE_INST_CAST;
2670       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2671         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2672       Vals.push_back(VE.getTypeID(I.getType()));
2673       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2674     } else {
2675       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2676       Code = bitc::FUNC_CODE_INST_BINOP;
2677       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2678         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2679       pushValue(I.getOperand(1), InstID, Vals);
2680       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2681       uint64_t Flags = getOptimizationFlags(&I);
2682       if (Flags != 0) {
2683         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2684           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2685         Vals.push_back(Flags);
2686       }
2687     }
2688     break;
2689   case Instruction::FNeg: {
2690     Code = bitc::FUNC_CODE_INST_UNOP;
2691     if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2692       AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
2693     Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
2694     uint64_t Flags = getOptimizationFlags(&I);
2695     if (Flags != 0) {
2696       if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
2697         AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
2698       Vals.push_back(Flags);
2699     }
2700     break;
2701   }
2702   case Instruction::GetElementPtr: {
2703     Code = bitc::FUNC_CODE_INST_GEP;
2704     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2705     auto &GEPInst = cast<GetElementPtrInst>(I);
2706     Vals.push_back(GEPInst.isInBounds());
2707     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2708     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2709       pushValueAndType(I.getOperand(i), InstID, Vals);
2710     break;
2711   }
2712   case Instruction::ExtractValue: {
2713     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2714     pushValueAndType(I.getOperand(0), InstID, Vals);
2715     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2716     Vals.append(EVI->idx_begin(), EVI->idx_end());
2717     break;
2718   }
2719   case Instruction::InsertValue: {
2720     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2721     pushValueAndType(I.getOperand(0), InstID, Vals);
2722     pushValueAndType(I.getOperand(1), InstID, Vals);
2723     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2724     Vals.append(IVI->idx_begin(), IVI->idx_end());
2725     break;
2726   }
2727   case Instruction::Select: {
2728     Code = bitc::FUNC_CODE_INST_VSELECT;
2729     pushValueAndType(I.getOperand(1), InstID, Vals);
2730     pushValue(I.getOperand(2), InstID, Vals);
2731     pushValueAndType(I.getOperand(0), InstID, Vals);
2732     uint64_t Flags = getOptimizationFlags(&I);
2733     if (Flags != 0)
2734       Vals.push_back(Flags);
2735     break;
2736   }
2737   case Instruction::ExtractElement:
2738     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2739     pushValueAndType(I.getOperand(0), InstID, Vals);
2740     pushValueAndType(I.getOperand(1), InstID, Vals);
2741     break;
2742   case Instruction::InsertElement:
2743     Code = bitc::FUNC_CODE_INST_INSERTELT;
2744     pushValueAndType(I.getOperand(0), InstID, Vals);
2745     pushValue(I.getOperand(1), InstID, Vals);
2746     pushValueAndType(I.getOperand(2), InstID, Vals);
2747     break;
2748   case Instruction::ShuffleVector:
2749     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2750     pushValueAndType(I.getOperand(0), InstID, Vals);
2751     pushValue(I.getOperand(1), InstID, Vals);
2752     pushValue(cast<ShuffleVectorInst>(I).getShuffleMaskForBitcode(), InstID,
2753               Vals);
2754     break;
2755   case Instruction::ICmp:
2756   case Instruction::FCmp: {
2757     // compare returning Int1Ty or vector of Int1Ty
2758     Code = bitc::FUNC_CODE_INST_CMP2;
2759     pushValueAndType(I.getOperand(0), InstID, Vals);
2760     pushValue(I.getOperand(1), InstID, Vals);
2761     Vals.push_back(cast<CmpInst>(I).getPredicate());
2762     uint64_t Flags = getOptimizationFlags(&I);
2763     if (Flags != 0)
2764       Vals.push_back(Flags);
2765     break;
2766   }
2767 
2768   case Instruction::Ret:
2769     {
2770       Code = bitc::FUNC_CODE_INST_RET;
2771       unsigned NumOperands = I.getNumOperands();
2772       if (NumOperands == 0)
2773         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2774       else if (NumOperands == 1) {
2775         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2776           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2777       } else {
2778         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2779           pushValueAndType(I.getOperand(i), InstID, Vals);
2780       }
2781     }
2782     break;
2783   case Instruction::Br:
2784     {
2785       Code = bitc::FUNC_CODE_INST_BR;
2786       const BranchInst &II = cast<BranchInst>(I);
2787       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2788       if (II.isConditional()) {
2789         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2790         pushValue(II.getCondition(), InstID, Vals);
2791       }
2792     }
2793     break;
2794   case Instruction::Switch:
2795     {
2796       Code = bitc::FUNC_CODE_INST_SWITCH;
2797       const SwitchInst &SI = cast<SwitchInst>(I);
2798       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2799       pushValue(SI.getCondition(), InstID, Vals);
2800       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2801       for (auto Case : SI.cases()) {
2802         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2803         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2804       }
2805     }
2806     break;
2807   case Instruction::IndirectBr:
2808     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2809     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2810     // Encode the address operand as relative, but not the basic blocks.
2811     pushValue(I.getOperand(0), InstID, Vals);
2812     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2813       Vals.push_back(VE.getValueID(I.getOperand(i)));
2814     break;
2815 
2816   case Instruction::Invoke: {
2817     const InvokeInst *II = cast<InvokeInst>(&I);
2818     const Value *Callee = II->getCalledOperand();
2819     FunctionType *FTy = II->getFunctionType();
2820 
2821     if (II->hasOperandBundles())
2822       writeOperandBundles(*II, InstID);
2823 
2824     Code = bitc::FUNC_CODE_INST_INVOKE;
2825 
2826     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2827     Vals.push_back(II->getCallingConv() | 1 << 13);
2828     Vals.push_back(VE.getValueID(II->getNormalDest()));
2829     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2830     Vals.push_back(VE.getTypeID(FTy));
2831     pushValueAndType(Callee, InstID, Vals);
2832 
2833     // Emit value #'s for the fixed parameters.
2834     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2835       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2836 
2837     // Emit type/value pairs for varargs params.
2838     if (FTy->isVarArg()) {
2839       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2840            i != e; ++i)
2841         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2842     }
2843     break;
2844   }
2845   case Instruction::Resume:
2846     Code = bitc::FUNC_CODE_INST_RESUME;
2847     pushValueAndType(I.getOperand(0), InstID, Vals);
2848     break;
2849   case Instruction::CleanupRet: {
2850     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2851     const auto &CRI = cast<CleanupReturnInst>(I);
2852     pushValue(CRI.getCleanupPad(), InstID, Vals);
2853     if (CRI.hasUnwindDest())
2854       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2855     break;
2856   }
2857   case Instruction::CatchRet: {
2858     Code = bitc::FUNC_CODE_INST_CATCHRET;
2859     const auto &CRI = cast<CatchReturnInst>(I);
2860     pushValue(CRI.getCatchPad(), InstID, Vals);
2861     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2862     break;
2863   }
2864   case Instruction::CleanupPad:
2865   case Instruction::CatchPad: {
2866     const auto &FuncletPad = cast<FuncletPadInst>(I);
2867     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2868                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2869     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2870 
2871     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2872     Vals.push_back(NumArgOperands);
2873     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2874       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2875     break;
2876   }
2877   case Instruction::CatchSwitch: {
2878     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2879     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2880 
2881     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2882 
2883     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2884     Vals.push_back(NumHandlers);
2885     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2886       Vals.push_back(VE.getValueID(CatchPadBB));
2887 
2888     if (CatchSwitch.hasUnwindDest())
2889       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2890     break;
2891   }
2892   case Instruction::CallBr: {
2893     const CallBrInst *CBI = cast<CallBrInst>(&I);
2894     const Value *Callee = CBI->getCalledOperand();
2895     FunctionType *FTy = CBI->getFunctionType();
2896 
2897     if (CBI->hasOperandBundles())
2898       writeOperandBundles(*CBI, InstID);
2899 
2900     Code = bitc::FUNC_CODE_INST_CALLBR;
2901 
2902     Vals.push_back(VE.getAttributeListID(CBI->getAttributes()));
2903 
2904     Vals.push_back(CBI->getCallingConv() << bitc::CALL_CCONV |
2905                    1 << bitc::CALL_EXPLICIT_TYPE);
2906 
2907     Vals.push_back(VE.getValueID(CBI->getDefaultDest()));
2908     Vals.push_back(CBI->getNumIndirectDests());
2909     for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
2910       Vals.push_back(VE.getValueID(CBI->getIndirectDest(i)));
2911 
2912     Vals.push_back(VE.getTypeID(FTy));
2913     pushValueAndType(Callee, InstID, Vals);
2914 
2915     // Emit value #'s for the fixed parameters.
2916     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2917       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2918 
2919     // Emit type/value pairs for varargs params.
2920     if (FTy->isVarArg()) {
2921       for (unsigned i = FTy->getNumParams(), e = CBI->getNumArgOperands();
2922            i != e; ++i)
2923         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2924     }
2925     break;
2926   }
2927   case Instruction::Unreachable:
2928     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2929     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2930     break;
2931 
2932   case Instruction::PHI: {
2933     const PHINode &PN = cast<PHINode>(I);
2934     Code = bitc::FUNC_CODE_INST_PHI;
2935     // With the newer instruction encoding, forward references could give
2936     // negative valued IDs.  This is most common for PHIs, so we use
2937     // signed VBRs.
2938     SmallVector<uint64_t, 128> Vals64;
2939     Vals64.push_back(VE.getTypeID(PN.getType()));
2940     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2941       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2942       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2943     }
2944 
2945     uint64_t Flags = getOptimizationFlags(&I);
2946     if (Flags != 0)
2947       Vals64.push_back(Flags);
2948 
2949     // Emit a Vals64 vector and exit.
2950     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2951     Vals64.clear();
2952     return;
2953   }
2954 
2955   case Instruction::LandingPad: {
2956     const LandingPadInst &LP = cast<LandingPadInst>(I);
2957     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2958     Vals.push_back(VE.getTypeID(LP.getType()));
2959     Vals.push_back(LP.isCleanup());
2960     Vals.push_back(LP.getNumClauses());
2961     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2962       if (LP.isCatch(I))
2963         Vals.push_back(LandingPadInst::Catch);
2964       else
2965         Vals.push_back(LandingPadInst::Filter);
2966       pushValueAndType(LP.getClause(I), InstID, Vals);
2967     }
2968     break;
2969   }
2970 
2971   case Instruction::Alloca: {
2972     Code = bitc::FUNC_CODE_INST_ALLOCA;
2973     const AllocaInst &AI = cast<AllocaInst>(I);
2974     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2975     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2976     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2977     using APV = AllocaPackedValues;
2978     unsigned Record = 0;
2979     Bitfield::set<APV::Align>(Record, getEncodedAlign(AI.getAlign()));
2980     Bitfield::set<APV::UsedWithInAlloca>(Record, AI.isUsedWithInAlloca());
2981     Bitfield::set<APV::ExplicitType>(Record, true);
2982     Bitfield::set<APV::SwiftError>(Record, AI.isSwiftError());
2983     Vals.push_back(Record);
2984     break;
2985   }
2986 
2987   case Instruction::Load:
2988     if (cast<LoadInst>(I).isAtomic()) {
2989       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2990       pushValueAndType(I.getOperand(0), InstID, Vals);
2991     } else {
2992       Code = bitc::FUNC_CODE_INST_LOAD;
2993       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2994         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2995     }
2996     Vals.push_back(VE.getTypeID(I.getType()));
2997     Vals.push_back(getEncodedAlign(cast<LoadInst>(I).getAlign()));
2998     Vals.push_back(cast<LoadInst>(I).isVolatile());
2999     if (cast<LoadInst>(I).isAtomic()) {
3000       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
3001       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
3002     }
3003     break;
3004   case Instruction::Store:
3005     if (cast<StoreInst>(I).isAtomic())
3006       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
3007     else
3008       Code = bitc::FUNC_CODE_INST_STORE;
3009     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
3010     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
3011     Vals.push_back(getEncodedAlign(cast<StoreInst>(I).getAlign()));
3012     Vals.push_back(cast<StoreInst>(I).isVolatile());
3013     if (cast<StoreInst>(I).isAtomic()) {
3014       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
3015       Vals.push_back(
3016           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
3017     }
3018     break;
3019   case Instruction::AtomicCmpXchg:
3020     Code = bitc::FUNC_CODE_INST_CMPXCHG;
3021     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3022     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
3023     pushValue(I.getOperand(2), InstID, Vals);        // newval.
3024     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
3025     Vals.push_back(
3026         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
3027     Vals.push_back(
3028         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
3029     Vals.push_back(
3030         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
3031     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
3032     break;
3033   case Instruction::AtomicRMW:
3034     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
3035     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
3036     pushValue(I.getOperand(1), InstID, Vals);        // val.
3037     Vals.push_back(
3038         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
3039     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
3040     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
3041     Vals.push_back(
3042         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
3043     break;
3044   case Instruction::Fence:
3045     Code = bitc::FUNC_CODE_INST_FENCE;
3046     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
3047     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
3048     break;
3049   case Instruction::Call: {
3050     const CallInst &CI = cast<CallInst>(I);
3051     FunctionType *FTy = CI.getFunctionType();
3052 
3053     if (CI.hasOperandBundles())
3054       writeOperandBundles(CI, InstID);
3055 
3056     Code = bitc::FUNC_CODE_INST_CALL;
3057 
3058     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
3059 
3060     unsigned Flags = getOptimizationFlags(&I);
3061     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
3062                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
3063                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
3064                    1 << bitc::CALL_EXPLICIT_TYPE |
3065                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
3066                    unsigned(Flags != 0) << bitc::CALL_FMF);
3067     if (Flags != 0)
3068       Vals.push_back(Flags);
3069 
3070     Vals.push_back(VE.getTypeID(FTy));
3071     pushValueAndType(CI.getCalledOperand(), InstID, Vals); // Callee
3072 
3073     // Emit value #'s for the fixed parameters.
3074     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
3075       // Check for labels (can happen with asm labels).
3076       if (FTy->getParamType(i)->isLabelTy())
3077         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
3078       else
3079         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
3080     }
3081 
3082     // Emit type/value pairs for varargs params.
3083     if (FTy->isVarArg()) {
3084       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
3085            i != e; ++i)
3086         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
3087     }
3088     break;
3089   }
3090   case Instruction::VAArg:
3091     Code = bitc::FUNC_CODE_INST_VAARG;
3092     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
3093     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
3094     Vals.push_back(VE.getTypeID(I.getType())); // restype.
3095     break;
3096   case Instruction::Freeze:
3097     Code = bitc::FUNC_CODE_INST_FREEZE;
3098     pushValueAndType(I.getOperand(0), InstID, Vals);
3099     break;
3100   }
3101 
3102   Stream.EmitRecord(Code, Vals, AbbrevToUse);
3103   Vals.clear();
3104 }
3105 
3106 /// Write a GlobalValue VST to the module. The purpose of this data structure is
3107 /// to allow clients to efficiently find the function body.
3108 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
3109   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3110   // Get the offset of the VST we are writing, and backpatch it into
3111   // the VST forward declaration record.
3112   uint64_t VSTOffset = Stream.GetCurrentBitNo();
3113   // The BitcodeStartBit was the stream offset of the identification block.
3114   VSTOffset -= bitcodeStartBit();
3115   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
3116   // Note that we add 1 here because the offset is relative to one word
3117   // before the start of the identification block, which was historically
3118   // always the start of the regular bitcode header.
3119   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
3120 
3121   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3122 
3123   auto Abbv = std::make_shared<BitCodeAbbrev>();
3124   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
3125   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
3126   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
3127   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3128 
3129   for (const Function &F : M) {
3130     uint64_t Record[2];
3131 
3132     if (F.isDeclaration())
3133       continue;
3134 
3135     Record[0] = VE.getValueID(&F);
3136 
3137     // Save the word offset of the function (from the start of the
3138     // actual bitcode written to the stream).
3139     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
3140     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
3141     // Note that we add 1 here because the offset is relative to one word
3142     // before the start of the identification block, which was historically
3143     // always the start of the regular bitcode header.
3144     Record[1] = BitcodeIndex / 32 + 1;
3145 
3146     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
3147   }
3148 
3149   Stream.ExitBlock();
3150 }
3151 
3152 /// Emit names for arguments, instructions and basic blocks in a function.
3153 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
3154     const ValueSymbolTable &VST) {
3155   if (VST.empty())
3156     return;
3157 
3158   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3159 
3160   // FIXME: Set up the abbrev, we know how many values there are!
3161   // FIXME: We know if the type names can use 7-bit ascii.
3162   SmallVector<uint64_t, 64> NameVals;
3163 
3164   for (const ValueName &Name : VST) {
3165     // Figure out the encoding to use for the name.
3166     StringEncoding Bits = getStringEncoding(Name.getKey());
3167 
3168     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
3169     NameVals.push_back(VE.getValueID(Name.getValue()));
3170 
3171     // VST_CODE_ENTRY:   [valueid, namechar x N]
3172     // VST_CODE_BBENTRY: [bbid, namechar x N]
3173     unsigned Code;
3174     if (isa<BasicBlock>(Name.getValue())) {
3175       Code = bitc::VST_CODE_BBENTRY;
3176       if (Bits == SE_Char6)
3177         AbbrevToUse = VST_BBENTRY_6_ABBREV;
3178     } else {
3179       Code = bitc::VST_CODE_ENTRY;
3180       if (Bits == SE_Char6)
3181         AbbrevToUse = VST_ENTRY_6_ABBREV;
3182       else if (Bits == SE_Fixed7)
3183         AbbrevToUse = VST_ENTRY_7_ABBREV;
3184     }
3185 
3186     for (const auto P : Name.getKey())
3187       NameVals.push_back((unsigned char)P);
3188 
3189     // Emit the finished record.
3190     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
3191     NameVals.clear();
3192   }
3193 
3194   Stream.ExitBlock();
3195 }
3196 
3197 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3198   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3199   unsigned Code;
3200   if (isa<BasicBlock>(Order.V))
3201     Code = bitc::USELIST_CODE_BB;
3202   else
3203     Code = bitc::USELIST_CODE_DEFAULT;
3204 
3205   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3206   Record.push_back(VE.getValueID(Order.V));
3207   Stream.EmitRecord(Code, Record);
3208 }
3209 
3210 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3211   assert(VE.shouldPreserveUseListOrder() &&
3212          "Expected to be preserving use-list order");
3213 
3214   auto hasMore = [&]() {
3215     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3216   };
3217   if (!hasMore())
3218     // Nothing to do.
3219     return;
3220 
3221   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3222   while (hasMore()) {
3223     writeUseList(std::move(VE.UseListOrders.back()));
3224     VE.UseListOrders.pop_back();
3225   }
3226   Stream.ExitBlock();
3227 }
3228 
3229 /// Emit a function body to the module stream.
3230 void ModuleBitcodeWriter::writeFunction(
3231     const Function &F,
3232     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3233   // Save the bitcode index of the start of this function block for recording
3234   // in the VST.
3235   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3236 
3237   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3238   VE.incorporateFunction(F);
3239 
3240   SmallVector<unsigned, 64> Vals;
3241 
3242   // Emit the number of basic blocks, so the reader can create them ahead of
3243   // time.
3244   Vals.push_back(VE.getBasicBlocks().size());
3245   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3246   Vals.clear();
3247 
3248   // If there are function-local constants, emit them now.
3249   unsigned CstStart, CstEnd;
3250   VE.getFunctionConstantRange(CstStart, CstEnd);
3251   writeConstants(CstStart, CstEnd, false);
3252 
3253   // If there is function-local metadata, emit it now.
3254   writeFunctionMetadata(F);
3255 
3256   // Keep a running idea of what the instruction ID is.
3257   unsigned InstID = CstEnd;
3258 
3259   bool NeedsMetadataAttachment = F.hasMetadata();
3260 
3261   DILocation *LastDL = nullptr;
3262   // Finally, emit all the instructions, in order.
3263   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3264     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3265          I != E; ++I) {
3266       writeInstruction(*I, InstID, Vals);
3267 
3268       if (!I->getType()->isVoidTy())
3269         ++InstID;
3270 
3271       // If the instruction has metadata, write a metadata attachment later.
3272       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3273 
3274       // If the instruction has a debug location, emit it.
3275       DILocation *DL = I->getDebugLoc();
3276       if (!DL)
3277         continue;
3278 
3279       if (DL == LastDL) {
3280         // Just repeat the same debug loc as last time.
3281         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3282         continue;
3283       }
3284 
3285       Vals.push_back(DL->getLine());
3286       Vals.push_back(DL->getColumn());
3287       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3288       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3289       Vals.push_back(DL->isImplicitCode());
3290       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3291       Vals.clear();
3292 
3293       LastDL = DL;
3294     }
3295 
3296   // Emit names for all the instructions etc.
3297   if (auto *Symtab = F.getValueSymbolTable())
3298     writeFunctionLevelValueSymbolTable(*Symtab);
3299 
3300   if (NeedsMetadataAttachment)
3301     writeFunctionMetadataAttachment(F);
3302   if (VE.shouldPreserveUseListOrder())
3303     writeUseListBlock(&F);
3304   VE.purgeFunction();
3305   Stream.ExitBlock();
3306 }
3307 
3308 // Emit blockinfo, which defines the standard abbreviations etc.
3309 void ModuleBitcodeWriter::writeBlockInfo() {
3310   // We only want to emit block info records for blocks that have multiple
3311   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3312   // Other blocks can define their abbrevs inline.
3313   Stream.EnterBlockInfoBlock();
3314 
3315   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3316     auto Abbv = std::make_shared<BitCodeAbbrev>();
3317     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3318     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3319     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3320     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3321     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3322         VST_ENTRY_8_ABBREV)
3323       llvm_unreachable("Unexpected abbrev ordering!");
3324   }
3325 
3326   { // 7-bit fixed width VST_CODE_ENTRY strings.
3327     auto Abbv = std::make_shared<BitCodeAbbrev>();
3328     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3329     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3330     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3331     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3332     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3333         VST_ENTRY_7_ABBREV)
3334       llvm_unreachable("Unexpected abbrev ordering!");
3335   }
3336   { // 6-bit char6 VST_CODE_ENTRY strings.
3337     auto Abbv = std::make_shared<BitCodeAbbrev>();
3338     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3339     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3340     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3341     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3342     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3343         VST_ENTRY_6_ABBREV)
3344       llvm_unreachable("Unexpected abbrev ordering!");
3345   }
3346   { // 6-bit char6 VST_CODE_BBENTRY strings.
3347     auto Abbv = std::make_shared<BitCodeAbbrev>();
3348     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3349     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3350     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3351     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3352     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3353         VST_BBENTRY_6_ABBREV)
3354       llvm_unreachable("Unexpected abbrev ordering!");
3355   }
3356 
3357   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3358     auto Abbv = std::make_shared<BitCodeAbbrev>();
3359     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3360     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3361                               VE.computeBitsRequiredForTypeIndicies()));
3362     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3363         CONSTANTS_SETTYPE_ABBREV)
3364       llvm_unreachable("Unexpected abbrev ordering!");
3365   }
3366 
3367   { // INTEGER abbrev for CONSTANTS_BLOCK.
3368     auto Abbv = std::make_shared<BitCodeAbbrev>();
3369     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3370     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3371     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3372         CONSTANTS_INTEGER_ABBREV)
3373       llvm_unreachable("Unexpected abbrev ordering!");
3374   }
3375 
3376   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3377     auto Abbv = std::make_shared<BitCodeAbbrev>();
3378     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3379     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3380     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3381                               VE.computeBitsRequiredForTypeIndicies()));
3382     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3383 
3384     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3385         CONSTANTS_CE_CAST_Abbrev)
3386       llvm_unreachable("Unexpected abbrev ordering!");
3387   }
3388   { // NULL abbrev for CONSTANTS_BLOCK.
3389     auto Abbv = std::make_shared<BitCodeAbbrev>();
3390     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3391     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3392         CONSTANTS_NULL_Abbrev)
3393       llvm_unreachable("Unexpected abbrev ordering!");
3394   }
3395 
3396   // FIXME: This should only use space for first class types!
3397 
3398   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3399     auto Abbv = std::make_shared<BitCodeAbbrev>();
3400     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3401     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3402     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3403                               VE.computeBitsRequiredForTypeIndicies()));
3404     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3405     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3406     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3407         FUNCTION_INST_LOAD_ABBREV)
3408       llvm_unreachable("Unexpected abbrev ordering!");
3409   }
3410   { // INST_UNOP abbrev for FUNCTION_BLOCK.
3411     auto Abbv = std::make_shared<BitCodeAbbrev>();
3412     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3413     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3414     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3415     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3416         FUNCTION_INST_UNOP_ABBREV)
3417       llvm_unreachable("Unexpected abbrev ordering!");
3418   }
3419   { // INST_UNOP_FLAGS abbrev for FUNCTION_BLOCK.
3420     auto Abbv = std::make_shared<BitCodeAbbrev>();
3421     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3422     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3423     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3424     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3425     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3426         FUNCTION_INST_UNOP_FLAGS_ABBREV)
3427       llvm_unreachable("Unexpected abbrev ordering!");
3428   }
3429   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3430     auto Abbv = std::make_shared<BitCodeAbbrev>();
3431     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3432     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3433     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3434     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3435     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3436         FUNCTION_INST_BINOP_ABBREV)
3437       llvm_unreachable("Unexpected abbrev ordering!");
3438   }
3439   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3440     auto Abbv = std::make_shared<BitCodeAbbrev>();
3441     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3442     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3443     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3444     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3445     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3446     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3447         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3448       llvm_unreachable("Unexpected abbrev ordering!");
3449   }
3450   { // INST_CAST abbrev for FUNCTION_BLOCK.
3451     auto Abbv = std::make_shared<BitCodeAbbrev>();
3452     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3453     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3454     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3455                               VE.computeBitsRequiredForTypeIndicies()));
3456     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3457     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3458         FUNCTION_INST_CAST_ABBREV)
3459       llvm_unreachable("Unexpected abbrev ordering!");
3460   }
3461 
3462   { // INST_RET abbrev for FUNCTION_BLOCK.
3463     auto Abbv = std::make_shared<BitCodeAbbrev>();
3464     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3465     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3466         FUNCTION_INST_RET_VOID_ABBREV)
3467       llvm_unreachable("Unexpected abbrev ordering!");
3468   }
3469   { // INST_RET abbrev for FUNCTION_BLOCK.
3470     auto Abbv = std::make_shared<BitCodeAbbrev>();
3471     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3472     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3473     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3474         FUNCTION_INST_RET_VAL_ABBREV)
3475       llvm_unreachable("Unexpected abbrev ordering!");
3476   }
3477   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3478     auto Abbv = std::make_shared<BitCodeAbbrev>();
3479     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3480     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3481         FUNCTION_INST_UNREACHABLE_ABBREV)
3482       llvm_unreachable("Unexpected abbrev ordering!");
3483   }
3484   {
3485     auto Abbv = std::make_shared<BitCodeAbbrev>();
3486     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3487     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3488     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3489                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3490     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3491     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3492     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3493         FUNCTION_INST_GEP_ABBREV)
3494       llvm_unreachable("Unexpected abbrev ordering!");
3495   }
3496 
3497   Stream.ExitBlock();
3498 }
3499 
3500 /// Write the module path strings, currently only used when generating
3501 /// a combined index file.
3502 void IndexBitcodeWriter::writeModStrings() {
3503   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3504 
3505   // TODO: See which abbrev sizes we actually need to emit
3506 
3507   // 8-bit fixed-width MST_ENTRY strings.
3508   auto Abbv = std::make_shared<BitCodeAbbrev>();
3509   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3510   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3511   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3512   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3513   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3514 
3515   // 7-bit fixed width MST_ENTRY strings.
3516   Abbv = std::make_shared<BitCodeAbbrev>();
3517   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3518   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3519   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3520   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3521   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3522 
3523   // 6-bit char6 MST_ENTRY strings.
3524   Abbv = std::make_shared<BitCodeAbbrev>();
3525   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3526   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3527   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3528   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3529   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3530 
3531   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3532   Abbv = std::make_shared<BitCodeAbbrev>();
3533   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3534   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3535   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3536   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3537   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3538   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3539   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3540 
3541   SmallVector<unsigned, 64> Vals;
3542   forEachModule(
3543       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3544         StringRef Key = MPSE.getKey();
3545         const auto &Value = MPSE.getValue();
3546         StringEncoding Bits = getStringEncoding(Key);
3547         unsigned AbbrevToUse = Abbrev8Bit;
3548         if (Bits == SE_Char6)
3549           AbbrevToUse = Abbrev6Bit;
3550         else if (Bits == SE_Fixed7)
3551           AbbrevToUse = Abbrev7Bit;
3552 
3553         Vals.push_back(Value.first);
3554         Vals.append(Key.begin(), Key.end());
3555 
3556         // Emit the finished record.
3557         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3558 
3559         // Emit an optional hash for the module now
3560         const auto &Hash = Value.second;
3561         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3562           Vals.assign(Hash.begin(), Hash.end());
3563           // Emit the hash record.
3564           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3565         }
3566 
3567         Vals.clear();
3568       });
3569   Stream.ExitBlock();
3570 }
3571 
3572 /// Write the function type metadata related records that need to appear before
3573 /// a function summary entry (whether per-module or combined).
3574 template <typename Fn>
3575 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3576                                              FunctionSummary *FS,
3577                                              Fn GetValueID) {
3578   if (!FS->type_tests().empty())
3579     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3580 
3581   SmallVector<uint64_t, 64> Record;
3582 
3583   auto WriteVFuncIdVec = [&](uint64_t Ty,
3584                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3585     if (VFs.empty())
3586       return;
3587     Record.clear();
3588     for (auto &VF : VFs) {
3589       Record.push_back(VF.GUID);
3590       Record.push_back(VF.Offset);
3591     }
3592     Stream.EmitRecord(Ty, Record);
3593   };
3594 
3595   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3596                   FS->type_test_assume_vcalls());
3597   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3598                   FS->type_checked_load_vcalls());
3599 
3600   auto WriteConstVCallVec = [&](uint64_t Ty,
3601                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3602     for (auto &VC : VCs) {
3603       Record.clear();
3604       Record.push_back(VC.VFunc.GUID);
3605       Record.push_back(VC.VFunc.Offset);
3606       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3607       Stream.EmitRecord(Ty, Record);
3608     }
3609   };
3610 
3611   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3612                      FS->type_test_assume_const_vcalls());
3613   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3614                      FS->type_checked_load_const_vcalls());
3615 
3616   auto WriteRange = [&](ConstantRange Range) {
3617     Range = Range.sextOrTrunc(FunctionSummary::ParamAccess::RangeWidth);
3618     assert(Range.getLower().getNumWords() == 1);
3619     assert(Range.getUpper().getNumWords() == 1);
3620     emitSignedInt64(Record, *Range.getLower().getRawData());
3621     emitSignedInt64(Record, *Range.getUpper().getRawData());
3622   };
3623 
3624   if (!FS->paramAccesses().empty()) {
3625     Record.clear();
3626     for (auto &Arg : FS->paramAccesses()) {
3627       size_t UndoSize = Record.size();
3628       Record.push_back(Arg.ParamNo);
3629       WriteRange(Arg.Use);
3630       Record.push_back(Arg.Calls.size());
3631       for (auto &Call : Arg.Calls) {
3632         Record.push_back(Call.ParamNo);
3633         Optional<unsigned> ValueID = GetValueID(Call.Callee);
3634         if (!ValueID) {
3635           // If ValueID is unknown we can't drop just this call, we must drop
3636           // entire parameter.
3637           Record.resize(UndoSize);
3638           break;
3639         }
3640         Record.push_back(*ValueID);
3641         WriteRange(Call.Offsets);
3642       }
3643     }
3644     if (!Record.empty())
3645       Stream.EmitRecord(bitc::FS_PARAM_ACCESS, Record);
3646   }
3647 }
3648 
3649 /// Collect type IDs from type tests used by function.
3650 static void
3651 getReferencedTypeIds(FunctionSummary *FS,
3652                      std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3653   if (!FS->type_tests().empty())
3654     for (auto &TT : FS->type_tests())
3655       ReferencedTypeIds.insert(TT);
3656 
3657   auto GetReferencedTypesFromVFuncIdVec =
3658       [&](ArrayRef<FunctionSummary::VFuncId> VFs) {
3659         for (auto &VF : VFs)
3660           ReferencedTypeIds.insert(VF.GUID);
3661       };
3662 
3663   GetReferencedTypesFromVFuncIdVec(FS->type_test_assume_vcalls());
3664   GetReferencedTypesFromVFuncIdVec(FS->type_checked_load_vcalls());
3665 
3666   auto GetReferencedTypesFromConstVCallVec =
3667       [&](ArrayRef<FunctionSummary::ConstVCall> VCs) {
3668         for (auto &VC : VCs)
3669           ReferencedTypeIds.insert(VC.VFunc.GUID);
3670       };
3671 
3672   GetReferencedTypesFromConstVCallVec(FS->type_test_assume_const_vcalls());
3673   GetReferencedTypesFromConstVCallVec(FS->type_checked_load_const_vcalls());
3674 }
3675 
3676 static void writeWholeProgramDevirtResolutionByArg(
3677     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3678     const WholeProgramDevirtResolution::ByArg &ByArg) {
3679   NameVals.push_back(args.size());
3680   NameVals.insert(NameVals.end(), args.begin(), args.end());
3681 
3682   NameVals.push_back(ByArg.TheKind);
3683   NameVals.push_back(ByArg.Info);
3684   NameVals.push_back(ByArg.Byte);
3685   NameVals.push_back(ByArg.Bit);
3686 }
3687 
3688 static void writeWholeProgramDevirtResolution(
3689     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3690     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3691   NameVals.push_back(Id);
3692 
3693   NameVals.push_back(Wpd.TheKind);
3694   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3695   NameVals.push_back(Wpd.SingleImplName.size());
3696 
3697   NameVals.push_back(Wpd.ResByArg.size());
3698   for (auto &A : Wpd.ResByArg)
3699     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3700 }
3701 
3702 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3703                                      StringTableBuilder &StrtabBuilder,
3704                                      const std::string &Id,
3705                                      const TypeIdSummary &Summary) {
3706   NameVals.push_back(StrtabBuilder.add(Id));
3707   NameVals.push_back(Id.size());
3708 
3709   NameVals.push_back(Summary.TTRes.TheKind);
3710   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3711   NameVals.push_back(Summary.TTRes.AlignLog2);
3712   NameVals.push_back(Summary.TTRes.SizeM1);
3713   NameVals.push_back(Summary.TTRes.BitMask);
3714   NameVals.push_back(Summary.TTRes.InlineBits);
3715 
3716   for (auto &W : Summary.WPDRes)
3717     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3718                                       W.second);
3719 }
3720 
3721 static void writeTypeIdCompatibleVtableSummaryRecord(
3722     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3723     const std::string &Id, const TypeIdCompatibleVtableInfo &Summary,
3724     ValueEnumerator &VE) {
3725   NameVals.push_back(StrtabBuilder.add(Id));
3726   NameVals.push_back(Id.size());
3727 
3728   for (auto &P : Summary) {
3729     NameVals.push_back(P.AddressPointOffset);
3730     NameVals.push_back(VE.getValueID(P.VTableVI.getValue()));
3731   }
3732 }
3733 
3734 // Helper to emit a single function summary record.
3735 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3736     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3737     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3738     const Function &F) {
3739   NameVals.push_back(ValueID);
3740 
3741   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3742 
3743   writeFunctionTypeMetadataRecords(
3744       Stream, FS, [&](const ValueInfo &VI) -> Optional<unsigned> {
3745         return {VE.getValueID(VI.getValue())};
3746       });
3747 
3748   auto SpecialRefCnts = FS->specialRefCounts();
3749   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3750   NameVals.push_back(FS->instCount());
3751   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3752   NameVals.push_back(FS->refs().size());
3753   NameVals.push_back(SpecialRefCnts.first);  // rorefcnt
3754   NameVals.push_back(SpecialRefCnts.second); // worefcnt
3755 
3756   for (auto &RI : FS->refs())
3757     NameVals.push_back(VE.getValueID(RI.getValue()));
3758 
3759   bool HasProfileData =
3760       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3761   for (auto &ECI : FS->calls()) {
3762     NameVals.push_back(getValueId(ECI.first));
3763     if (HasProfileData)
3764       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3765     else if (WriteRelBFToSummary)
3766       NameVals.push_back(ECI.second.RelBlockFreq);
3767   }
3768 
3769   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3770   unsigned Code =
3771       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3772                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3773                                              : bitc::FS_PERMODULE));
3774 
3775   // Emit the finished record.
3776   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3777   NameVals.clear();
3778 }
3779 
3780 // Collect the global value references in the given variable's initializer,
3781 // and emit them in a summary record.
3782 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3783     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3784     unsigned FSModRefsAbbrev, unsigned FSModVTableRefsAbbrev) {
3785   auto VI = Index->getValueInfo(V.getGUID());
3786   if (!VI || VI.getSummaryList().empty()) {
3787     // Only declarations should not have a summary (a declaration might however
3788     // have a summary if the def was in module level asm).
3789     assert(V.isDeclaration());
3790     return;
3791   }
3792   auto *Summary = VI.getSummaryList()[0].get();
3793   NameVals.push_back(VE.getValueID(&V));
3794   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3795   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3796   NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
3797 
3798   auto VTableFuncs = VS->vTableFuncs();
3799   if (!VTableFuncs.empty())
3800     NameVals.push_back(VS->refs().size());
3801 
3802   unsigned SizeBeforeRefs = NameVals.size();
3803   for (auto &RI : VS->refs())
3804     NameVals.push_back(VE.getValueID(RI.getValue()));
3805   // Sort the refs for determinism output, the vector returned by FS->refs() has
3806   // been initialized from a DenseSet.
3807   llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3808 
3809   if (VTableFuncs.empty())
3810     Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3811                       FSModRefsAbbrev);
3812   else {
3813     // VTableFuncs pairs should already be sorted by offset.
3814     for (auto &P : VTableFuncs) {
3815       NameVals.push_back(VE.getValueID(P.FuncVI.getValue()));
3816       NameVals.push_back(P.VTableOffset);
3817     }
3818 
3819     Stream.EmitRecord(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS, NameVals,
3820                       FSModVTableRefsAbbrev);
3821   }
3822   NameVals.clear();
3823 }
3824 
3825 /// Emit the per-module summary section alongside the rest of
3826 /// the module's bitcode.
3827 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3828   // By default we compile with ThinLTO if the module has a summary, but the
3829   // client can request full LTO with a module flag.
3830   bool IsThinLTO = true;
3831   if (auto *MD =
3832           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3833     IsThinLTO = MD->getZExtValue();
3834   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3835                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3836                        4);
3837 
3838   Stream.EmitRecord(
3839       bitc::FS_VERSION,
3840       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
3841 
3842   // Write the index flags.
3843   uint64_t Flags = 0;
3844   // Bits 1-3 are set only in the combined index, skip them.
3845   if (Index->enableSplitLTOUnit())
3846     Flags |= 0x8;
3847   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
3848 
3849   if (Index->begin() == Index->end()) {
3850     Stream.ExitBlock();
3851     return;
3852   }
3853 
3854   for (const auto &GVI : valueIds()) {
3855     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3856                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3857   }
3858 
3859   // Abbrev for FS_PERMODULE_PROFILE.
3860   auto Abbv = std::make_shared<BitCodeAbbrev>();
3861   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3862   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3863   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3864   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3865   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3866   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3867   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3868   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3869   // numrefs x valueid, n x (valueid, hotness)
3870   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3871   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3872   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3873 
3874   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
3875   Abbv = std::make_shared<BitCodeAbbrev>();
3876   if (WriteRelBFToSummary)
3877     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
3878   else
3879     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3880   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3881   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3882   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3883   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3884   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3885   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3886   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3887   // numrefs x valueid, n x (valueid [, rel_block_freq])
3888   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3889   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3890   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3891 
3892   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3893   Abbv = std::make_shared<BitCodeAbbrev>();
3894   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3895   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3896   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3897   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3898   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3899   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3900 
3901   // Abbrev for FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS.
3902   Abbv = std::make_shared<BitCodeAbbrev>();
3903   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS));
3904   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3905   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3906   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numrefs
3907   // numrefs x valueid, n x (valueid , offset)
3908   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3909   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3910   unsigned FSModVTableRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3911 
3912   // Abbrev for FS_ALIAS.
3913   Abbv = std::make_shared<BitCodeAbbrev>();
3914   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3915   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3916   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3917   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3918   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3919 
3920   // Abbrev for FS_TYPE_ID_METADATA
3921   Abbv = std::make_shared<BitCodeAbbrev>();
3922   Abbv->Add(BitCodeAbbrevOp(bitc::FS_TYPE_ID_METADATA));
3923   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid strtab index
3924   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid length
3925   // n x (valueid , offset)
3926   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3927   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3928   unsigned TypeIdCompatibleVtableAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3929 
3930   SmallVector<uint64_t, 64> NameVals;
3931   // Iterate over the list of functions instead of the Index to
3932   // ensure the ordering is stable.
3933   for (const Function &F : M) {
3934     // Summary emission does not support anonymous functions, they have to
3935     // renamed using the anonymous function renaming pass.
3936     if (!F.hasName())
3937       report_fatal_error("Unexpected anonymous function when writing summary");
3938 
3939     ValueInfo VI = Index->getValueInfo(F.getGUID());
3940     if (!VI || VI.getSummaryList().empty()) {
3941       // Only declarations should not have a summary (a declaration might
3942       // however have a summary if the def was in module level asm).
3943       assert(F.isDeclaration());
3944       continue;
3945     }
3946     auto *Summary = VI.getSummaryList()[0].get();
3947     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3948                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3949   }
3950 
3951   // Capture references from GlobalVariable initializers, which are outside
3952   // of a function scope.
3953   for (const GlobalVariable &G : M.globals())
3954     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev,
3955                                FSModVTableRefsAbbrev);
3956 
3957   for (const GlobalAlias &A : M.aliases()) {
3958     auto *Aliasee = A.getBaseObject();
3959     if (!Aliasee->hasName())
3960       // Nameless function don't have an entry in the summary, skip it.
3961       continue;
3962     auto AliasId = VE.getValueID(&A);
3963     auto AliaseeId = VE.getValueID(Aliasee);
3964     NameVals.push_back(AliasId);
3965     auto *Summary = Index->getGlobalValueSummary(A);
3966     AliasSummary *AS = cast<AliasSummary>(Summary);
3967     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3968     NameVals.push_back(AliaseeId);
3969     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3970     NameVals.clear();
3971   }
3972 
3973   for (auto &S : Index->typeIdCompatibleVtableMap()) {
3974     writeTypeIdCompatibleVtableSummaryRecord(NameVals, StrtabBuilder, S.first,
3975                                              S.second, VE);
3976     Stream.EmitRecord(bitc::FS_TYPE_ID_METADATA, NameVals,
3977                       TypeIdCompatibleVtableAbbrev);
3978     NameVals.clear();
3979   }
3980 
3981   Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
3982                     ArrayRef<uint64_t>{Index->getBlockCount()});
3983 
3984   Stream.ExitBlock();
3985 }
3986 
3987 /// Emit the combined summary section into the combined index file.
3988 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3989   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3990   Stream.EmitRecord(
3991       bitc::FS_VERSION,
3992       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
3993 
3994   // Write the index flags.
3995   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Index.getFlags()});
3996 
3997   for (const auto &GVI : valueIds()) {
3998     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3999                       ArrayRef<uint64_t>{GVI.second, GVI.first});
4000   }
4001 
4002   // Abbrev for FS_COMBINED.
4003   auto Abbv = std::make_shared<BitCodeAbbrev>();
4004   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
4005   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4006   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4007   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4008   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4009   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4010   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
4011   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4012   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4013   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4014   // numrefs x valueid, n x (valueid)
4015   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4016   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4017   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4018 
4019   // Abbrev for FS_COMBINED_PROFILE.
4020   Abbv = std::make_shared<BitCodeAbbrev>();
4021   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
4022   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4023   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4024   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4025   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
4026   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
4027   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
4028   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
4029   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
4030   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
4031   // numrefs x valueid, n x (valueid, hotness)
4032   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4034   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4035 
4036   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
4037   Abbv = std::make_shared<BitCodeAbbrev>();
4038   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
4039   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4040   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4041   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4042   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
4043   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
4044   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4045 
4046   // Abbrev for FS_COMBINED_ALIAS.
4047   Abbv = std::make_shared<BitCodeAbbrev>();
4048   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
4049   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4050   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
4051   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
4052   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
4053   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4054 
4055   // The aliases are emitted as a post-pass, and will point to the value
4056   // id of the aliasee. Save them in a vector for post-processing.
4057   SmallVector<AliasSummary *, 64> Aliases;
4058 
4059   // Save the value id for each summary for alias emission.
4060   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
4061 
4062   SmallVector<uint64_t, 64> NameVals;
4063 
4064   // Set that will be populated during call to writeFunctionTypeMetadataRecords
4065   // with the type ids referenced by this index file.
4066   std::set<GlobalValue::GUID> ReferencedTypeIds;
4067 
4068   // For local linkage, we also emit the original name separately
4069   // immediately after the record.
4070   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
4071     if (!GlobalValue::isLocalLinkage(S.linkage()))
4072       return;
4073     NameVals.push_back(S.getOriginalName());
4074     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
4075     NameVals.clear();
4076   };
4077 
4078   std::set<GlobalValue::GUID> DefOrUseGUIDs;
4079   forEachSummary([&](GVInfo I, bool IsAliasee) {
4080     GlobalValueSummary *S = I.second;
4081     assert(S);
4082     DefOrUseGUIDs.insert(I.first);
4083     for (const ValueInfo &VI : S->refs())
4084       DefOrUseGUIDs.insert(VI.getGUID());
4085 
4086     auto ValueId = getValueId(I.first);
4087     assert(ValueId);
4088     SummaryToValueIdMap[S] = *ValueId;
4089 
4090     // If this is invoked for an aliasee, we want to record the above
4091     // mapping, but then not emit a summary entry (if the aliasee is
4092     // to be imported, we will invoke this separately with IsAliasee=false).
4093     if (IsAliasee)
4094       return;
4095 
4096     if (auto *AS = dyn_cast<AliasSummary>(S)) {
4097       // Will process aliases as a post-pass because the reader wants all
4098       // global to be loaded first.
4099       Aliases.push_back(AS);
4100       return;
4101     }
4102 
4103     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
4104       NameVals.push_back(*ValueId);
4105       NameVals.push_back(Index.getModuleId(VS->modulePath()));
4106       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
4107       NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
4108       for (auto &RI : VS->refs()) {
4109         auto RefValueId = getValueId(RI.getGUID());
4110         if (!RefValueId)
4111           continue;
4112         NameVals.push_back(*RefValueId);
4113       }
4114 
4115       // Emit the finished record.
4116       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
4117                         FSModRefsAbbrev);
4118       NameVals.clear();
4119       MaybeEmitOriginalName(*S);
4120       return;
4121     }
4122 
4123     auto GetValueId = [&](const ValueInfo &VI) -> Optional<unsigned> {
4124       GlobalValue::GUID GUID = VI.getGUID();
4125       Optional<unsigned> CallValueId = getValueId(GUID);
4126       if (CallValueId)
4127         return CallValueId;
4128       // For SamplePGO, the indirect call targets for local functions will
4129       // have its original name annotated in profile. We try to find the
4130       // corresponding PGOFuncName as the GUID.
4131       GUID = Index.getGUIDFromOriginalID(GUID);
4132       if (!GUID)
4133         return None;
4134       CallValueId = getValueId(GUID);
4135       if (!CallValueId)
4136         return None;
4137       // The mapping from OriginalId to GUID may return a GUID
4138       // that corresponds to a static variable. Filter it out here.
4139       // This can happen when
4140       // 1) There is a call to a library function which does not have
4141       // a CallValidId;
4142       // 2) There is a static variable with the  OriginalGUID identical
4143       // to the GUID of the library function in 1);
4144       // When this happens, the logic for SamplePGO kicks in and
4145       // the static variable in 2) will be found, which needs to be
4146       // filtered out.
4147       auto *GVSum = Index.getGlobalValueSummary(GUID, false);
4148       if (GVSum && GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
4149         return None;
4150       return CallValueId;
4151     };
4152 
4153     auto *FS = cast<FunctionSummary>(S);
4154     writeFunctionTypeMetadataRecords(Stream, FS, GetValueId);
4155     getReferencedTypeIds(FS, ReferencedTypeIds);
4156 
4157     NameVals.push_back(*ValueId);
4158     NameVals.push_back(Index.getModuleId(FS->modulePath()));
4159     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
4160     NameVals.push_back(FS->instCount());
4161     NameVals.push_back(getEncodedFFlags(FS->fflags()));
4162     NameVals.push_back(FS->entryCount());
4163 
4164     // Fill in below
4165     NameVals.push_back(0); // numrefs
4166     NameVals.push_back(0); // rorefcnt
4167     NameVals.push_back(0); // worefcnt
4168 
4169     unsigned Count = 0, RORefCnt = 0, WORefCnt = 0;
4170     for (auto &RI : FS->refs()) {
4171       auto RefValueId = getValueId(RI.getGUID());
4172       if (!RefValueId)
4173         continue;
4174       NameVals.push_back(*RefValueId);
4175       if (RI.isReadOnly())
4176         RORefCnt++;
4177       else if (RI.isWriteOnly())
4178         WORefCnt++;
4179       Count++;
4180     }
4181     NameVals[6] = Count;
4182     NameVals[7] = RORefCnt;
4183     NameVals[8] = WORefCnt;
4184 
4185     bool HasProfileData = false;
4186     for (auto &EI : FS->calls()) {
4187       HasProfileData |=
4188           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
4189       if (HasProfileData)
4190         break;
4191     }
4192 
4193     for (auto &EI : FS->calls()) {
4194       // If this GUID doesn't have a value id, it doesn't have a function
4195       // summary and we don't need to record any calls to it.
4196       Optional<unsigned> CallValueId = GetValueId(EI.first);
4197       if (!CallValueId)
4198         continue;
4199       NameVals.push_back(*CallValueId);
4200       if (HasProfileData)
4201         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
4202     }
4203 
4204     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
4205     unsigned Code =
4206         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
4207 
4208     // Emit the finished record.
4209     Stream.EmitRecord(Code, NameVals, FSAbbrev);
4210     NameVals.clear();
4211     MaybeEmitOriginalName(*S);
4212   });
4213 
4214   for (auto *AS : Aliases) {
4215     auto AliasValueId = SummaryToValueIdMap[AS];
4216     assert(AliasValueId);
4217     NameVals.push_back(AliasValueId);
4218     NameVals.push_back(Index.getModuleId(AS->modulePath()));
4219     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4220     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
4221     assert(AliaseeValueId);
4222     NameVals.push_back(AliaseeValueId);
4223 
4224     // Emit the finished record.
4225     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
4226     NameVals.clear();
4227     MaybeEmitOriginalName(*AS);
4228 
4229     if (auto *FS = dyn_cast<FunctionSummary>(&AS->getAliasee()))
4230       getReferencedTypeIds(FS, ReferencedTypeIds);
4231   }
4232 
4233   if (!Index.cfiFunctionDefs().empty()) {
4234     for (auto &S : Index.cfiFunctionDefs()) {
4235       if (DefOrUseGUIDs.count(
4236               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4237         NameVals.push_back(StrtabBuilder.add(S));
4238         NameVals.push_back(S.size());
4239       }
4240     }
4241     if (!NameVals.empty()) {
4242       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
4243       NameVals.clear();
4244     }
4245   }
4246 
4247   if (!Index.cfiFunctionDecls().empty()) {
4248     for (auto &S : Index.cfiFunctionDecls()) {
4249       if (DefOrUseGUIDs.count(
4250               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4251         NameVals.push_back(StrtabBuilder.add(S));
4252         NameVals.push_back(S.size());
4253       }
4254     }
4255     if (!NameVals.empty()) {
4256       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
4257       NameVals.clear();
4258     }
4259   }
4260 
4261   // Walk the GUIDs that were referenced, and write the
4262   // corresponding type id records.
4263   for (auto &T : ReferencedTypeIds) {
4264     auto TidIter = Index.typeIds().equal_range(T);
4265     for (auto It = TidIter.first; It != TidIter.second; ++It) {
4266       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, It->second.first,
4267                                It->second.second);
4268       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
4269       NameVals.clear();
4270     }
4271   }
4272 
4273   Stream.EmitRecord(bitc::FS_BLOCK_COUNT,
4274                     ArrayRef<uint64_t>{Index.getBlockCount()});
4275 
4276   Stream.ExitBlock();
4277 }
4278 
4279 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
4280 /// current llvm version, and a record for the epoch number.
4281 static void writeIdentificationBlock(BitstreamWriter &Stream) {
4282   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
4283 
4284   // Write the "user readable" string identifying the bitcode producer
4285   auto Abbv = std::make_shared<BitCodeAbbrev>();
4286   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
4287   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4288   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
4289   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4290   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
4291                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
4292 
4293   // Write the epoch version
4294   Abbv = std::make_shared<BitCodeAbbrev>();
4295   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
4296   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
4297   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4298   constexpr std::array<unsigned, 1> Vals = {{bitc::BITCODE_CURRENT_EPOCH}};
4299   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
4300   Stream.ExitBlock();
4301 }
4302 
4303 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
4304   // Emit the module's hash.
4305   // MODULE_CODE_HASH: [5*i32]
4306   if (GenerateHash) {
4307     uint32_t Vals[5];
4308     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
4309                                     Buffer.size() - BlockStartPos));
4310     StringRef Hash = Hasher.result();
4311     for (int Pos = 0; Pos < 20; Pos += 4) {
4312       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
4313     }
4314 
4315     // Emit the finished record.
4316     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
4317 
4318     if (ModHash)
4319       // Save the written hash value.
4320       llvm::copy(Vals, std::begin(*ModHash));
4321   }
4322 }
4323 
4324 void ModuleBitcodeWriter::write() {
4325   writeIdentificationBlock(Stream);
4326 
4327   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4328   size_t BlockStartPos = Buffer.size();
4329 
4330   writeModuleVersion();
4331 
4332   // Emit blockinfo, which defines the standard abbreviations etc.
4333   writeBlockInfo();
4334 
4335   // Emit information describing all of the types in the module.
4336   writeTypeTable();
4337 
4338   // Emit information about attribute groups.
4339   writeAttributeGroupTable();
4340 
4341   // Emit information about parameter attributes.
4342   writeAttributeTable();
4343 
4344   writeComdats();
4345 
4346   // Emit top-level description of module, including target triple, inline asm,
4347   // descriptors for global variables, and function prototype info.
4348   writeModuleInfo();
4349 
4350   // Emit constants.
4351   writeModuleConstants();
4352 
4353   // Emit metadata kind names.
4354   writeModuleMetadataKinds();
4355 
4356   // Emit metadata.
4357   writeModuleMetadata();
4358 
4359   // Emit module-level use-lists.
4360   if (VE.shouldPreserveUseListOrder())
4361     writeUseListBlock(nullptr);
4362 
4363   writeOperandBundleTags();
4364   writeSyncScopeNames();
4365 
4366   // Emit function bodies.
4367   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
4368   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
4369     if (!F->isDeclaration())
4370       writeFunction(*F, FunctionToBitcodeIndex);
4371 
4372   // Need to write after the above call to WriteFunction which populates
4373   // the summary information in the index.
4374   if (Index)
4375     writePerModuleGlobalValueSummary();
4376 
4377   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
4378 
4379   writeModuleHash(BlockStartPos);
4380 
4381   Stream.ExitBlock();
4382 }
4383 
4384 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
4385                                uint32_t &Position) {
4386   support::endian::write32le(&Buffer[Position], Value);
4387   Position += 4;
4388 }
4389 
4390 /// If generating a bc file on darwin, we have to emit a
4391 /// header and trailer to make it compatible with the system archiver.  To do
4392 /// this we emit the following header, and then emit a trailer that pads the
4393 /// file out to be a multiple of 16 bytes.
4394 ///
4395 /// struct bc_header {
4396 ///   uint32_t Magic;         // 0x0B17C0DE
4397 ///   uint32_t Version;       // Version, currently always 0.
4398 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4399 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4400 ///   uint32_t CPUType;       // CPU specifier.
4401 ///   ... potentially more later ...
4402 /// };
4403 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4404                                          const Triple &TT) {
4405   unsigned CPUType = ~0U;
4406 
4407   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4408   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4409   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4410   // specific constants here because they are implicitly part of the Darwin ABI.
4411   enum {
4412     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4413     DARWIN_CPU_TYPE_X86        = 7,
4414     DARWIN_CPU_TYPE_ARM        = 12,
4415     DARWIN_CPU_TYPE_POWERPC    = 18
4416   };
4417 
4418   Triple::ArchType Arch = TT.getArch();
4419   if (Arch == Triple::x86_64)
4420     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4421   else if (Arch == Triple::x86)
4422     CPUType = DARWIN_CPU_TYPE_X86;
4423   else if (Arch == Triple::ppc)
4424     CPUType = DARWIN_CPU_TYPE_POWERPC;
4425   else if (Arch == Triple::ppc64)
4426     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4427   else if (Arch == Triple::arm || Arch == Triple::thumb)
4428     CPUType = DARWIN_CPU_TYPE_ARM;
4429 
4430   // Traditional Bitcode starts after header.
4431   assert(Buffer.size() >= BWH_HeaderSize &&
4432          "Expected header size to be reserved");
4433   unsigned BCOffset = BWH_HeaderSize;
4434   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4435 
4436   // Write the magic and version.
4437   unsigned Position = 0;
4438   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4439   writeInt32ToBuffer(0, Buffer, Position); // Version.
4440   writeInt32ToBuffer(BCOffset, Buffer, Position);
4441   writeInt32ToBuffer(BCSize, Buffer, Position);
4442   writeInt32ToBuffer(CPUType, Buffer, Position);
4443 
4444   // If the file is not a multiple of 16 bytes, insert dummy padding.
4445   while (Buffer.size() & 15)
4446     Buffer.push_back(0);
4447 }
4448 
4449 /// Helper to write the header common to all bitcode files.
4450 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4451   // Emit the file header.
4452   Stream.Emit((unsigned)'B', 8);
4453   Stream.Emit((unsigned)'C', 8);
4454   Stream.Emit(0x0, 4);
4455   Stream.Emit(0xC, 4);
4456   Stream.Emit(0xE, 4);
4457   Stream.Emit(0xD, 4);
4458 }
4459 
4460 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer, raw_fd_stream *FS)
4461     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer, FS, FlushThreshold)) {
4462   writeBitcodeHeader(*Stream);
4463 }
4464 
4465 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4466 
4467 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4468   Stream->EnterSubblock(Block, 3);
4469 
4470   auto Abbv = std::make_shared<BitCodeAbbrev>();
4471   Abbv->Add(BitCodeAbbrevOp(Record));
4472   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4473   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4474 
4475   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4476 
4477   Stream->ExitBlock();
4478 }
4479 
4480 void BitcodeWriter::writeSymtab() {
4481   assert(!WroteStrtab && !WroteSymtab);
4482 
4483   // If any module has module-level inline asm, we will require a registered asm
4484   // parser for the target so that we can create an accurate symbol table for
4485   // the module.
4486   for (Module *M : Mods) {
4487     if (M->getModuleInlineAsm().empty())
4488       continue;
4489 
4490     std::string Err;
4491     const Triple TT(M->getTargetTriple());
4492     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4493     if (!T || !T->hasMCAsmParser())
4494       return;
4495   }
4496 
4497   WroteSymtab = true;
4498   SmallVector<char, 0> Symtab;
4499   // The irsymtab::build function may be unable to create a symbol table if the
4500   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4501   // table is not required for correctness, but we still want to be able to
4502   // write malformed modules to bitcode files, so swallow the error.
4503   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4504     consumeError(std::move(E));
4505     return;
4506   }
4507 
4508   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4509             {Symtab.data(), Symtab.size()});
4510 }
4511 
4512 void BitcodeWriter::writeStrtab() {
4513   assert(!WroteStrtab);
4514 
4515   std::vector<char> Strtab;
4516   StrtabBuilder.finalizeInOrder();
4517   Strtab.resize(StrtabBuilder.getSize());
4518   StrtabBuilder.write((uint8_t *)Strtab.data());
4519 
4520   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4521             {Strtab.data(), Strtab.size()});
4522 
4523   WroteStrtab = true;
4524 }
4525 
4526 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4527   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4528   WroteStrtab = true;
4529 }
4530 
4531 void BitcodeWriter::writeModule(const Module &M,
4532                                 bool ShouldPreserveUseListOrder,
4533                                 const ModuleSummaryIndex *Index,
4534                                 bool GenerateHash, ModuleHash *ModHash) {
4535   assert(!WroteStrtab);
4536 
4537   // The Mods vector is used by irsymtab::build, which requires non-const
4538   // Modules in case it needs to materialize metadata. But the bitcode writer
4539   // requires that the module is materialized, so we can cast to non-const here,
4540   // after checking that it is in fact materialized.
4541   assert(M.isMaterialized());
4542   Mods.push_back(const_cast<Module *>(&M));
4543 
4544   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4545                                    ShouldPreserveUseListOrder, Index,
4546                                    GenerateHash, ModHash);
4547   ModuleWriter.write();
4548 }
4549 
4550 void BitcodeWriter::writeIndex(
4551     const ModuleSummaryIndex *Index,
4552     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4553   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4554                                  ModuleToSummariesForIndex);
4555   IndexWriter.write();
4556 }
4557 
4558 /// Write the specified module to the specified output stream.
4559 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4560                               bool ShouldPreserveUseListOrder,
4561                               const ModuleSummaryIndex *Index,
4562                               bool GenerateHash, ModuleHash *ModHash) {
4563   SmallVector<char, 0> Buffer;
4564   Buffer.reserve(256*1024);
4565 
4566   // If this is darwin or another generic macho target, reserve space for the
4567   // header.
4568   Triple TT(M.getTargetTriple());
4569   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4570     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4571 
4572   BitcodeWriter Writer(Buffer, dyn_cast<raw_fd_stream>(&Out));
4573   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4574                      ModHash);
4575   Writer.writeSymtab();
4576   Writer.writeStrtab();
4577 
4578   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4579     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4580 
4581   // Write the generated bitstream to "Out".
4582   if (!Buffer.empty())
4583     Out.write((char *)&Buffer.front(), Buffer.size());
4584 }
4585 
4586 void IndexBitcodeWriter::write() {
4587   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4588 
4589   writeModuleVersion();
4590 
4591   // Write the module paths in the combined index.
4592   writeModStrings();
4593 
4594   // Write the summary combined index records.
4595   writeCombinedGlobalValueSummary();
4596 
4597   Stream.ExitBlock();
4598 }
4599 
4600 // Write the specified module summary index to the given raw output stream,
4601 // where it will be written in a new bitcode block. This is used when
4602 // writing the combined index file for ThinLTO. When writing a subset of the
4603 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4604 void llvm::WriteIndexToFile(
4605     const ModuleSummaryIndex &Index, raw_ostream &Out,
4606     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4607   SmallVector<char, 0> Buffer;
4608   Buffer.reserve(256 * 1024);
4609 
4610   BitcodeWriter Writer(Buffer);
4611   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4612   Writer.writeStrtab();
4613 
4614   Out.write((char *)&Buffer.front(), Buffer.size());
4615 }
4616 
4617 namespace {
4618 
4619 /// Class to manage the bitcode writing for a thin link bitcode file.
4620 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4621   /// ModHash is for use in ThinLTO incremental build, generated while writing
4622   /// the module bitcode file.
4623   const ModuleHash *ModHash;
4624 
4625 public:
4626   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4627                         BitstreamWriter &Stream,
4628                         const ModuleSummaryIndex &Index,
4629                         const ModuleHash &ModHash)
4630       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4631                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4632         ModHash(&ModHash) {}
4633 
4634   void write();
4635 
4636 private:
4637   void writeSimplifiedModuleInfo();
4638 };
4639 
4640 } // end anonymous namespace
4641 
4642 // This function writes a simpilified module info for thin link bitcode file.
4643 // It only contains the source file name along with the name(the offset and
4644 // size in strtab) and linkage for global values. For the global value info
4645 // entry, in order to keep linkage at offset 5, there are three zeros used
4646 // as padding.
4647 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4648   SmallVector<unsigned, 64> Vals;
4649   // Emit the module's source file name.
4650   {
4651     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4652     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4653     if (Bits == SE_Char6)
4654       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4655     else if (Bits == SE_Fixed7)
4656       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4657 
4658     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4659     auto Abbv = std::make_shared<BitCodeAbbrev>();
4660     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4661     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4662     Abbv->Add(AbbrevOpToUse);
4663     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4664 
4665     for (const auto P : M.getSourceFileName())
4666       Vals.push_back((unsigned char)P);
4667 
4668     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4669     Vals.clear();
4670   }
4671 
4672   // Emit the global variable information.
4673   for (const GlobalVariable &GV : M.globals()) {
4674     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4675     Vals.push_back(StrtabBuilder.add(GV.getName()));
4676     Vals.push_back(GV.getName().size());
4677     Vals.push_back(0);
4678     Vals.push_back(0);
4679     Vals.push_back(0);
4680     Vals.push_back(getEncodedLinkage(GV));
4681 
4682     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4683     Vals.clear();
4684   }
4685 
4686   // Emit the function proto information.
4687   for (const Function &F : M) {
4688     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4689     Vals.push_back(StrtabBuilder.add(F.getName()));
4690     Vals.push_back(F.getName().size());
4691     Vals.push_back(0);
4692     Vals.push_back(0);
4693     Vals.push_back(0);
4694     Vals.push_back(getEncodedLinkage(F));
4695 
4696     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4697     Vals.clear();
4698   }
4699 
4700   // Emit the alias information.
4701   for (const GlobalAlias &A : M.aliases()) {
4702     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4703     Vals.push_back(StrtabBuilder.add(A.getName()));
4704     Vals.push_back(A.getName().size());
4705     Vals.push_back(0);
4706     Vals.push_back(0);
4707     Vals.push_back(0);
4708     Vals.push_back(getEncodedLinkage(A));
4709 
4710     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4711     Vals.clear();
4712   }
4713 
4714   // Emit the ifunc information.
4715   for (const GlobalIFunc &I : M.ifuncs()) {
4716     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4717     Vals.push_back(StrtabBuilder.add(I.getName()));
4718     Vals.push_back(I.getName().size());
4719     Vals.push_back(0);
4720     Vals.push_back(0);
4721     Vals.push_back(0);
4722     Vals.push_back(getEncodedLinkage(I));
4723 
4724     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4725     Vals.clear();
4726   }
4727 }
4728 
4729 void ThinLinkBitcodeWriter::write() {
4730   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4731 
4732   writeModuleVersion();
4733 
4734   writeSimplifiedModuleInfo();
4735 
4736   writePerModuleGlobalValueSummary();
4737 
4738   // Write module hash.
4739   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4740 
4741   Stream.ExitBlock();
4742 }
4743 
4744 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4745                                          const ModuleSummaryIndex &Index,
4746                                          const ModuleHash &ModHash) {
4747   assert(!WroteStrtab);
4748 
4749   // The Mods vector is used by irsymtab::build, which requires non-const
4750   // Modules in case it needs to materialize metadata. But the bitcode writer
4751   // requires that the module is materialized, so we can cast to non-const here,
4752   // after checking that it is in fact materialized.
4753   assert(M.isMaterialized());
4754   Mods.push_back(const_cast<Module *>(&M));
4755 
4756   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4757                                        ModHash);
4758   ThinLinkWriter.write();
4759 }
4760 
4761 // Write the specified thin link bitcode file to the given raw output stream,
4762 // where it will be written in a new bitcode block. This is used when
4763 // writing the per-module index file for ThinLTO.
4764 void llvm::WriteThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4765                                       const ModuleSummaryIndex &Index,
4766                                       const ModuleHash &ModHash) {
4767   SmallVector<char, 0> Buffer;
4768   Buffer.reserve(256 * 1024);
4769 
4770   BitcodeWriter Writer(Buffer);
4771   Writer.writeThinLinkBitcode(M, Index, ModHash);
4772   Writer.writeSymtab();
4773   Writer.writeStrtab();
4774 
4775   Out.write((char *)&Buffer.front(), Buffer.size());
4776 }
4777 
4778 static const char *getSectionNameForBitcode(const Triple &T) {
4779   switch (T.getObjectFormat()) {
4780   case Triple::MachO:
4781     return "__LLVM,__bitcode";
4782   case Triple::COFF:
4783   case Triple::ELF:
4784   case Triple::Wasm:
4785   case Triple::UnknownObjectFormat:
4786     return ".llvmbc";
4787   case Triple::GOFF:
4788     llvm_unreachable("GOFF is not yet implemented");
4789     break;
4790   case Triple::XCOFF:
4791     llvm_unreachable("XCOFF is not yet implemented");
4792     break;
4793   }
4794   llvm_unreachable("Unimplemented ObjectFormatType");
4795 }
4796 
4797 static const char *getSectionNameForCommandline(const Triple &T) {
4798   switch (T.getObjectFormat()) {
4799   case Triple::MachO:
4800     return "__LLVM,__cmdline";
4801   case Triple::COFF:
4802   case Triple::ELF:
4803   case Triple::Wasm:
4804   case Triple::UnknownObjectFormat:
4805     return ".llvmcmd";
4806   case Triple::GOFF:
4807     llvm_unreachable("GOFF is not yet implemented");
4808     break;
4809   case Triple::XCOFF:
4810     llvm_unreachable("XCOFF is not yet implemented");
4811     break;
4812   }
4813   llvm_unreachable("Unimplemented ObjectFormatType");
4814 }
4815 
4816 void llvm::EmbedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
4817                                 bool EmbedBitcode, bool EmbedMarker,
4818                                 const std::vector<uint8_t> *CmdArgs) {
4819   // Save llvm.compiler.used and remove it.
4820   SmallVector<Constant *, 2> UsedArray;
4821   SmallPtrSet<GlobalValue *, 4> UsedGlobals;
4822   Type *UsedElementType = Type::getInt8Ty(M.getContext())->getPointerTo(0);
4823   GlobalVariable *Used = collectUsedGlobalVariables(M, UsedGlobals, true);
4824   for (auto *GV : UsedGlobals) {
4825     if (GV->getName() != "llvm.embedded.module" &&
4826         GV->getName() != "llvm.cmdline")
4827       UsedArray.push_back(
4828           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4829   }
4830   if (Used)
4831     Used->eraseFromParent();
4832 
4833   // Embed the bitcode for the llvm module.
4834   std::string Data;
4835   ArrayRef<uint8_t> ModuleData;
4836   Triple T(M.getTargetTriple());
4837 
4838   if (EmbedBitcode) {
4839     if (Buf.getBufferSize() == 0 ||
4840         !isBitcode((const unsigned char *)Buf.getBufferStart(),
4841                    (const unsigned char *)Buf.getBufferEnd())) {
4842       // If the input is LLVM Assembly, bitcode is produced by serializing
4843       // the module. Use-lists order need to be preserved in this case.
4844       llvm::raw_string_ostream OS(Data);
4845       llvm::WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
4846       ModuleData =
4847           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
4848     } else
4849       // If the input is LLVM bitcode, write the input byte stream directly.
4850       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
4851                                      Buf.getBufferSize());
4852   }
4853   llvm::Constant *ModuleConstant =
4854       llvm::ConstantDataArray::get(M.getContext(), ModuleData);
4855   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
4856       M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
4857       ModuleConstant);
4858   GV->setSection(getSectionNameForBitcode(T));
4859   // Set alignment to 1 to prevent padding between two contributions from input
4860   // sections after linking.
4861   GV->setAlignment(Align(1));
4862   UsedArray.push_back(
4863       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4864   if (llvm::GlobalVariable *Old =
4865           M.getGlobalVariable("llvm.embedded.module", true)) {
4866     assert(Old->hasOneUse() &&
4867            "llvm.embedded.module can only be used once in llvm.compiler.used");
4868     GV->takeName(Old);
4869     Old->eraseFromParent();
4870   } else {
4871     GV->setName("llvm.embedded.module");
4872   }
4873 
4874   // Skip if only bitcode needs to be embedded.
4875   if (EmbedMarker) {
4876     // Embed command-line options.
4877     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CmdArgs->data()),
4878                               CmdArgs->size());
4879     llvm::Constant *CmdConstant =
4880         llvm::ConstantDataArray::get(M.getContext(), CmdData);
4881     GV = new llvm::GlobalVariable(M, CmdConstant->getType(), true,
4882                                   llvm::GlobalValue::PrivateLinkage,
4883                                   CmdConstant);
4884     GV->setSection(getSectionNameForCommandline(T));
4885     GV->setAlignment(Align(1));
4886     UsedArray.push_back(
4887         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4888     if (llvm::GlobalVariable *Old = M.getGlobalVariable("llvm.cmdline", true)) {
4889       assert(Old->hasOneUse() &&
4890              "llvm.cmdline can only be used once in llvm.compiler.used");
4891       GV->takeName(Old);
4892       Old->eraseFromParent();
4893     } else {
4894       GV->setName("llvm.cmdline");
4895     }
4896   }
4897 
4898   if (UsedArray.empty())
4899     return;
4900 
4901   // Recreate llvm.compiler.used.
4902   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
4903   auto *NewUsed = new GlobalVariable(
4904       M, ATy, false, llvm::GlobalValue::AppendingLinkage,
4905       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
4906   NewUsed->setSection("llvm.metadata");
4907 }
4908