xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision cb22ab7403557941fd672a8fc3a16b1ef75a7842)
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/BitcodeReader.h"
28 #include "llvm/Bitcode/LLVMBitCodes.h"
29 #include "llvm/Bitstream/BitCodes.h"
30 #include "llvm/Bitstream/BitstreamWriter.h"
31 #include "llvm/Config/llvm-config.h"
32 #include "llvm/IR/Attributes.h"
33 #include "llvm/IR/BasicBlock.h"
34 #include "llvm/IR/Comdat.h"
35 #include "llvm/IR/Constant.h"
36 #include "llvm/IR/Constants.h"
37 #include "llvm/IR/DebugInfoMetadata.h"
38 #include "llvm/IR/DebugLoc.h"
39 #include "llvm/IR/DerivedTypes.h"
40 #include "llvm/IR/Function.h"
41 #include "llvm/IR/GlobalAlias.h"
42 #include "llvm/IR/GlobalIFunc.h"
43 #include "llvm/IR/GlobalObject.h"
44 #include "llvm/IR/GlobalValue.h"
45 #include "llvm/IR/GlobalVariable.h"
46 #include "llvm/IR/InlineAsm.h"
47 #include "llvm/IR/InstrTypes.h"
48 #include "llvm/IR/Instruction.h"
49 #include "llvm/IR/Instructions.h"
50 #include "llvm/IR/LLVMContext.h"
51 #include "llvm/IR/Metadata.h"
52 #include "llvm/IR/Module.h"
53 #include "llvm/IR/ModuleSummaryIndex.h"
54 #include "llvm/IR/Operator.h"
55 #include "llvm/IR/Type.h"
56 #include "llvm/IR/UseListOrder.h"
57 #include "llvm/IR/Value.h"
58 #include "llvm/IR/ValueSymbolTable.h"
59 #include "llvm/MC/StringTableBuilder.h"
60 #include "llvm/Object/IRSymtab.h"
61 #include "llvm/Support/AtomicOrdering.h"
62 #include "llvm/Support/Casting.h"
63 #include "llvm/Support/CommandLine.h"
64 #include "llvm/Support/Endian.h"
65 #include "llvm/Support/Error.h"
66 #include "llvm/Support/ErrorHandling.h"
67 #include "llvm/Support/MathExtras.h"
68 #include "llvm/Support/SHA1.h"
69 #include "llvm/Support/TargetRegistry.h"
70 #include "llvm/Support/raw_ostream.h"
71 #include <algorithm>
72 #include <cassert>
73 #include <cstddef>
74 #include <cstdint>
75 #include <iterator>
76 #include <map>
77 #include <memory>
78 #include <string>
79 #include <utility>
80 #include <vector>
81 
82 using namespace llvm;
83 
84 static cl::opt<unsigned>
85     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
86                    cl::desc("Number of metadatas above which we emit an index "
87                             "to enable lazy-loading"));
88 
89 static cl::opt<bool> WriteRelBFToSummary(
90     "write-relbf-to-summary", cl::Hidden, cl::init(false),
91     cl::desc("Write relative block frequency to function summary "));
92 
93 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
94 
95 namespace {
96 
97 /// These are manifest constants used by the bitcode writer. They do not need to
98 /// be kept in sync with the reader, but need to be consistent within this file.
99 enum {
100   // VALUE_SYMTAB_BLOCK abbrev id's.
101   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
102   VST_ENTRY_7_ABBREV,
103   VST_ENTRY_6_ABBREV,
104   VST_BBENTRY_6_ABBREV,
105 
106   // CONSTANTS_BLOCK abbrev id's.
107   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
108   CONSTANTS_INTEGER_ABBREV,
109   CONSTANTS_CE_CAST_Abbrev,
110   CONSTANTS_NULL_Abbrev,
111 
112   // FUNCTION_BLOCK abbrev id's.
113   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
114   FUNCTION_INST_UNOP_ABBREV,
115   FUNCTION_INST_UNOP_FLAGS_ABBREV,
116   FUNCTION_INST_BINOP_ABBREV,
117   FUNCTION_INST_BINOP_FLAGS_ABBREV,
118   FUNCTION_INST_CAST_ABBREV,
119   FUNCTION_INST_RET_VOID_ABBREV,
120   FUNCTION_INST_RET_VAL_ABBREV,
121   FUNCTION_INST_UNREACHABLE_ABBREV,
122   FUNCTION_INST_GEP_ABBREV,
123 };
124 
125 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
126 /// file type.
127 class BitcodeWriterBase {
128 protected:
129   /// The stream created and owned by the client.
130   BitstreamWriter &Stream;
131 
132   StringTableBuilder &StrtabBuilder;
133 
134 public:
135   /// Constructs a BitcodeWriterBase object that writes to the provided
136   /// \p Stream.
137   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
138       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
139 
140 protected:
141   void writeBitcodeHeader();
142   void writeModuleVersion();
143 };
144 
145 void BitcodeWriterBase::writeModuleVersion() {
146   // VERSION: [version#]
147   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
148 }
149 
150 /// Base class to manage the module bitcode writing, currently subclassed for
151 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
152 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
153 protected:
154   /// The Module to write to bitcode.
155   const Module &M;
156 
157   /// Enumerates ids for all values in the module.
158   ValueEnumerator VE;
159 
160   /// Optional per-module index to write for ThinLTO.
161   const ModuleSummaryIndex *Index;
162 
163   /// Map that holds the correspondence between GUIDs in the summary index,
164   /// that came from indirect call profiles, and a value id generated by this
165   /// class to use in the VST and summary block records.
166   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
167 
168   /// Tracks the last value id recorded in the GUIDToValueMap.
169   unsigned GlobalValueId;
170 
171   /// Saves the offset of the VSTOffset record that must eventually be
172   /// backpatched with the offset of the actual VST.
173   uint64_t VSTOffsetPlaceholder = 0;
174 
175 public:
176   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
177   /// writing to the provided \p Buffer.
178   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
179                           BitstreamWriter &Stream,
180                           bool ShouldPreserveUseListOrder,
181                           const ModuleSummaryIndex *Index)
182       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
183         VE(M, ShouldPreserveUseListOrder), Index(Index) {
184     // Assign ValueIds to any callee values in the index that came from
185     // indirect call profiles and were recorded as a GUID not a Value*
186     // (which would have been assigned an ID by the ValueEnumerator).
187     // The starting ValueId is just after the number of values in the
188     // ValueEnumerator, so that they can be emitted in the VST.
189     GlobalValueId = VE.getValues().size();
190     if (!Index)
191       return;
192     for (const auto &GUIDSummaryLists : *Index)
193       // Examine all summaries for this GUID.
194       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
195         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
196           // For each call in the function summary, see if the call
197           // is to a GUID (which means it is for an indirect call,
198           // otherwise we would have a Value for it). If so, synthesize
199           // a value id.
200           for (auto &CallEdge : FS->calls())
201             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
202               assignValueId(CallEdge.first.getGUID());
203   }
204 
205 protected:
206   void writePerModuleGlobalValueSummary();
207 
208 private:
209   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
210                                            GlobalValueSummary *Summary,
211                                            unsigned ValueID,
212                                            unsigned FSCallsAbbrev,
213                                            unsigned FSCallsProfileAbbrev,
214                                            const Function &F);
215   void writeModuleLevelReferences(const GlobalVariable &V,
216                                   SmallVector<uint64_t, 64> &NameVals,
217                                   unsigned FSModRefsAbbrev,
218                                   unsigned FSModVTableRefsAbbrev);
219 
220   void assignValueId(GlobalValue::GUID ValGUID) {
221     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
222   }
223 
224   unsigned getValueId(GlobalValue::GUID ValGUID) {
225     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
226     // Expect that any GUID value had a value Id assigned by an
227     // earlier call to assignValueId.
228     assert(VMI != GUIDToValueIdMap.end() &&
229            "GUID does not have assigned value Id");
230     return VMI->second;
231   }
232 
233   // Helper to get the valueId for the type of value recorded in VI.
234   unsigned getValueId(ValueInfo VI) {
235     if (!VI.haveGVs() || !VI.getValue())
236       return getValueId(VI.getGUID());
237     return VE.getValueID(VI.getValue());
238   }
239 
240   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
241 };
242 
243 /// Class to manage the bitcode writing for a module.
244 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
245   /// Pointer to the buffer allocated by caller for bitcode writing.
246   const SmallVectorImpl<char> &Buffer;
247 
248   /// True if a module hash record should be written.
249   bool GenerateHash;
250 
251   /// If non-null, when GenerateHash is true, the resulting hash is written
252   /// into ModHash.
253   ModuleHash *ModHash;
254 
255   SHA1 Hasher;
256 
257   /// The start bit of the identification block.
258   uint64_t BitcodeStartBit;
259 
260 public:
261   /// Constructs a ModuleBitcodeWriter object for the given Module,
262   /// writing to the provided \p Buffer.
263   ModuleBitcodeWriter(const Module &M, SmallVectorImpl<char> &Buffer,
264                       StringTableBuilder &StrtabBuilder,
265                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
266                       const ModuleSummaryIndex *Index, bool GenerateHash,
267                       ModuleHash *ModHash = nullptr)
268       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
269                                 ShouldPreserveUseListOrder, Index),
270         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
271         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
272 
273   /// Emit the current module to the bitstream.
274   void write();
275 
276 private:
277   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
278 
279   size_t addToStrtab(StringRef Str);
280 
281   void writeAttributeGroupTable();
282   void writeAttributeTable();
283   void writeTypeTable();
284   void writeComdats();
285   void writeValueSymbolTableForwardDecl();
286   void writeModuleInfo();
287   void writeValueAsMetadata(const ValueAsMetadata *MD,
288                             SmallVectorImpl<uint64_t> &Record);
289   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
290                     unsigned Abbrev);
291   unsigned createDILocationAbbrev();
292   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
293                        unsigned &Abbrev);
294   unsigned createGenericDINodeAbbrev();
295   void writeGenericDINode(const GenericDINode *N,
296                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
297   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
298                        unsigned Abbrev);
299   void writeDIEnumerator(const DIEnumerator *N,
300                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
301   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
302                         unsigned Abbrev);
303   void writeDIDerivedType(const DIDerivedType *N,
304                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
305   void writeDICompositeType(const DICompositeType *N,
306                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
307   void writeDISubroutineType(const DISubroutineType *N,
308                              SmallVectorImpl<uint64_t> &Record,
309                              unsigned Abbrev);
310   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
311                    unsigned Abbrev);
312   void writeDICompileUnit(const DICompileUnit *N,
313                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
314   void writeDISubprogram(const DISubprogram *N,
315                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
316   void writeDILexicalBlock(const DILexicalBlock *N,
317                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
318   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
319                                SmallVectorImpl<uint64_t> &Record,
320                                unsigned Abbrev);
321   void writeDICommonBlock(const DICommonBlock *N,
322                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
323   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
324                         unsigned Abbrev);
325   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
326                     unsigned Abbrev);
327   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
328                         unsigned Abbrev);
329   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
330                      unsigned Abbrev);
331   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
332                                     SmallVectorImpl<uint64_t> &Record,
333                                     unsigned Abbrev);
334   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
335                                      SmallVectorImpl<uint64_t> &Record,
336                                      unsigned Abbrev);
337   void writeDIGlobalVariable(const DIGlobalVariable *N,
338                              SmallVectorImpl<uint64_t> &Record,
339                              unsigned Abbrev);
340   void writeDILocalVariable(const DILocalVariable *N,
341                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
342   void writeDILabel(const DILabel *N,
343                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
344   void writeDIExpression(const DIExpression *N,
345                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
346   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
347                                        SmallVectorImpl<uint64_t> &Record,
348                                        unsigned Abbrev);
349   void writeDIObjCProperty(const DIObjCProperty *N,
350                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
351   void writeDIImportedEntity(const DIImportedEntity *N,
352                              SmallVectorImpl<uint64_t> &Record,
353                              unsigned Abbrev);
354   unsigned createNamedMetadataAbbrev();
355   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
356   unsigned createMetadataStringsAbbrev();
357   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
358                             SmallVectorImpl<uint64_t> &Record);
359   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
360                             SmallVectorImpl<uint64_t> &Record,
361                             std::vector<unsigned> *MDAbbrevs = nullptr,
362                             std::vector<uint64_t> *IndexPos = nullptr);
363   void writeModuleMetadata();
364   void writeFunctionMetadata(const Function &F);
365   void writeFunctionMetadataAttachment(const Function &F);
366   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
367   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
368                                     const GlobalObject &GO);
369   void writeModuleMetadataKinds();
370   void writeOperandBundleTags();
371   void writeSyncScopeNames();
372   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
373   void writeModuleConstants();
374   bool pushValueAndType(const Value *V, unsigned InstID,
375                         SmallVectorImpl<unsigned> &Vals);
376   void writeOperandBundles(const CallBase &CB, unsigned InstID);
377   void pushValue(const Value *V, unsigned InstID,
378                  SmallVectorImpl<unsigned> &Vals);
379   void pushValueSigned(const Value *V, unsigned InstID,
380                        SmallVectorImpl<uint64_t> &Vals);
381   void writeInstruction(const Instruction &I, unsigned InstID,
382                         SmallVectorImpl<unsigned> &Vals);
383   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
384   void writeGlobalValueSymbolTable(
385       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
386   void writeUseList(UseListOrder &&Order);
387   void writeUseListBlock(const Function *F);
388   void
389   writeFunction(const Function &F,
390                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
391   void writeBlockInfo();
392   void writeModuleHash(size_t BlockStartPos);
393 
394   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
395     return unsigned(SSID);
396   }
397 };
398 
399 /// Class to manage the bitcode writing for a combined index.
400 class IndexBitcodeWriter : public BitcodeWriterBase {
401   /// The combined index to write to bitcode.
402   const ModuleSummaryIndex &Index;
403 
404   /// When writing a subset of the index for distributed backends, client
405   /// provides a map of modules to the corresponding GUIDs/summaries to write.
406   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
407 
408   /// Map that holds the correspondence between the GUID used in the combined
409   /// index and a value id generated by this class to use in references.
410   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
411 
412   /// Tracks the last value id recorded in the GUIDToValueMap.
413   unsigned GlobalValueId = 0;
414 
415 public:
416   /// Constructs a IndexBitcodeWriter object for the given combined index,
417   /// writing to the provided \p Buffer. When writing a subset of the index
418   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
419   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
420                      const ModuleSummaryIndex &Index,
421                      const std::map<std::string, GVSummaryMapTy>
422                          *ModuleToSummariesForIndex = nullptr)
423       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
424         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
425     // Assign unique value ids to all summaries to be written, for use
426     // in writing out the call graph edges. Save the mapping from GUID
427     // to the new global value id to use when writing those edges, which
428     // are currently saved in the index in terms of GUID.
429     forEachSummary([&](GVInfo I, bool) {
430       GUIDToValueIdMap[I.first] = ++GlobalValueId;
431     });
432   }
433 
434   /// The below iterator returns the GUID and associated summary.
435   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
436 
437   /// Calls the callback for each value GUID and summary to be written to
438   /// bitcode. This hides the details of whether they are being pulled from the
439   /// entire index or just those in a provided ModuleToSummariesForIndex map.
440   template<typename Functor>
441   void forEachSummary(Functor Callback) {
442     if (ModuleToSummariesForIndex) {
443       for (auto &M : *ModuleToSummariesForIndex)
444         for (auto &Summary : M.second) {
445           Callback(Summary, false);
446           // Ensure aliasee is handled, e.g. for assigning a valueId,
447           // even if we are not importing the aliasee directly (the
448           // imported alias will contain a copy of aliasee).
449           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
450             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
451         }
452     } else {
453       for (auto &Summaries : Index)
454         for (auto &Summary : Summaries.second.SummaryList)
455           Callback({Summaries.first, Summary.get()}, false);
456     }
457   }
458 
459   /// Calls the callback for each entry in the modulePaths StringMap that
460   /// should be written to the module path string table. This hides the details
461   /// of whether they are being pulled from the entire index or just those in a
462   /// provided ModuleToSummariesForIndex map.
463   template <typename Functor> void forEachModule(Functor Callback) {
464     if (ModuleToSummariesForIndex) {
465       for (const auto &M : *ModuleToSummariesForIndex) {
466         const auto &MPI = Index.modulePaths().find(M.first);
467         if (MPI == Index.modulePaths().end()) {
468           // This should only happen if the bitcode file was empty, in which
469           // case we shouldn't be importing (the ModuleToSummariesForIndex
470           // would only include the module we are writing and index for).
471           assert(ModuleToSummariesForIndex->size() == 1);
472           continue;
473         }
474         Callback(*MPI);
475       }
476     } else {
477       for (const auto &MPSE : Index.modulePaths())
478         Callback(MPSE);
479     }
480   }
481 
482   /// Main entry point for writing a combined index to bitcode.
483   void write();
484 
485 private:
486   void writeModStrings();
487   void writeCombinedGlobalValueSummary();
488 
489   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
490     auto VMI = GUIDToValueIdMap.find(ValGUID);
491     if (VMI == GUIDToValueIdMap.end())
492       return None;
493     return VMI->second;
494   }
495 
496   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
497 };
498 
499 } // end anonymous namespace
500 
501 static unsigned getEncodedCastOpcode(unsigned Opcode) {
502   switch (Opcode) {
503   default: llvm_unreachable("Unknown cast instruction!");
504   case Instruction::Trunc   : return bitc::CAST_TRUNC;
505   case Instruction::ZExt    : return bitc::CAST_ZEXT;
506   case Instruction::SExt    : return bitc::CAST_SEXT;
507   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
508   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
509   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
510   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
511   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
512   case Instruction::FPExt   : return bitc::CAST_FPEXT;
513   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
514   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
515   case Instruction::BitCast : return bitc::CAST_BITCAST;
516   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
517   }
518 }
519 
520 static unsigned getEncodedUnaryOpcode(unsigned Opcode) {
521   switch (Opcode) {
522   default: llvm_unreachable("Unknown binary instruction!");
523   case Instruction::FNeg: return bitc::UNOP_FNEG;
524   }
525 }
526 
527 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
528   switch (Opcode) {
529   default: llvm_unreachable("Unknown binary instruction!");
530   case Instruction::Add:
531   case Instruction::FAdd: return bitc::BINOP_ADD;
532   case Instruction::Sub:
533   case Instruction::FSub: return bitc::BINOP_SUB;
534   case Instruction::Mul:
535   case Instruction::FMul: return bitc::BINOP_MUL;
536   case Instruction::UDiv: return bitc::BINOP_UDIV;
537   case Instruction::FDiv:
538   case Instruction::SDiv: return bitc::BINOP_SDIV;
539   case Instruction::URem: return bitc::BINOP_UREM;
540   case Instruction::FRem:
541   case Instruction::SRem: return bitc::BINOP_SREM;
542   case Instruction::Shl:  return bitc::BINOP_SHL;
543   case Instruction::LShr: return bitc::BINOP_LSHR;
544   case Instruction::AShr: return bitc::BINOP_ASHR;
545   case Instruction::And:  return bitc::BINOP_AND;
546   case Instruction::Or:   return bitc::BINOP_OR;
547   case Instruction::Xor:  return bitc::BINOP_XOR;
548   }
549 }
550 
551 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
552   switch (Op) {
553   default: llvm_unreachable("Unknown RMW operation!");
554   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
555   case AtomicRMWInst::Add: return bitc::RMW_ADD;
556   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
557   case AtomicRMWInst::And: return bitc::RMW_AND;
558   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
559   case AtomicRMWInst::Or: return bitc::RMW_OR;
560   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
561   case AtomicRMWInst::Max: return bitc::RMW_MAX;
562   case AtomicRMWInst::Min: return bitc::RMW_MIN;
563   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
564   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
565   case AtomicRMWInst::FAdd: return bitc::RMW_FADD;
566   case AtomicRMWInst::FSub: return bitc::RMW_FSUB;
567   }
568 }
569 
570 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
571   switch (Ordering) {
572   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
573   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
574   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
575   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
576   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
577   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
578   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
579   }
580   llvm_unreachable("Invalid ordering");
581 }
582 
583 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
584                               StringRef Str, unsigned AbbrevToUse) {
585   SmallVector<unsigned, 64> Vals;
586 
587   // Code: [strchar x N]
588   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
589     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
590       AbbrevToUse = 0;
591     Vals.push_back(Str[i]);
592   }
593 
594   // Emit the finished record.
595   Stream.EmitRecord(Code, Vals, AbbrevToUse);
596 }
597 
598 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
599   switch (Kind) {
600   case Attribute::Alignment:
601     return bitc::ATTR_KIND_ALIGNMENT;
602   case Attribute::AllocSize:
603     return bitc::ATTR_KIND_ALLOC_SIZE;
604   case Attribute::AlwaysInline:
605     return bitc::ATTR_KIND_ALWAYS_INLINE;
606   case Attribute::ArgMemOnly:
607     return bitc::ATTR_KIND_ARGMEMONLY;
608   case Attribute::Builtin:
609     return bitc::ATTR_KIND_BUILTIN;
610   case Attribute::ByVal:
611     return bitc::ATTR_KIND_BY_VAL;
612   case Attribute::Convergent:
613     return bitc::ATTR_KIND_CONVERGENT;
614   case Attribute::InAlloca:
615     return bitc::ATTR_KIND_IN_ALLOCA;
616   case Attribute::Cold:
617     return bitc::ATTR_KIND_COLD;
618   case Attribute::InaccessibleMemOnly:
619     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
620   case Attribute::InaccessibleMemOrArgMemOnly:
621     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
622   case Attribute::InlineHint:
623     return bitc::ATTR_KIND_INLINE_HINT;
624   case Attribute::InReg:
625     return bitc::ATTR_KIND_IN_REG;
626   case Attribute::JumpTable:
627     return bitc::ATTR_KIND_JUMP_TABLE;
628   case Attribute::MinSize:
629     return bitc::ATTR_KIND_MIN_SIZE;
630   case Attribute::Naked:
631     return bitc::ATTR_KIND_NAKED;
632   case Attribute::Nest:
633     return bitc::ATTR_KIND_NEST;
634   case Attribute::NoAlias:
635     return bitc::ATTR_KIND_NO_ALIAS;
636   case Attribute::NoBuiltin:
637     return bitc::ATTR_KIND_NO_BUILTIN;
638   case Attribute::NoCapture:
639     return bitc::ATTR_KIND_NO_CAPTURE;
640   case Attribute::NoDuplicate:
641     return bitc::ATTR_KIND_NO_DUPLICATE;
642   case Attribute::NoFree:
643     return bitc::ATTR_KIND_NOFREE;
644   case Attribute::NoImplicitFloat:
645     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
646   case Attribute::NoInline:
647     return bitc::ATTR_KIND_NO_INLINE;
648   case Attribute::NoRecurse:
649     return bitc::ATTR_KIND_NO_RECURSE;
650   case Attribute::NoMerge:
651     return bitc::ATTR_KIND_NO_MERGE;
652   case Attribute::NonLazyBind:
653     return bitc::ATTR_KIND_NON_LAZY_BIND;
654   case Attribute::NonNull:
655     return bitc::ATTR_KIND_NON_NULL;
656   case Attribute::Dereferenceable:
657     return bitc::ATTR_KIND_DEREFERENCEABLE;
658   case Attribute::DereferenceableOrNull:
659     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
660   case Attribute::NoRedZone:
661     return bitc::ATTR_KIND_NO_RED_ZONE;
662   case Attribute::NoReturn:
663     return bitc::ATTR_KIND_NO_RETURN;
664   case Attribute::NoSync:
665     return bitc::ATTR_KIND_NOSYNC;
666   case Attribute::NoCfCheck:
667     return bitc::ATTR_KIND_NOCF_CHECK;
668   case Attribute::NoUnwind:
669     return bitc::ATTR_KIND_NO_UNWIND;
670   case Attribute::OptForFuzzing:
671     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
672   case Attribute::OptimizeForSize:
673     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
674   case Attribute::OptimizeNone:
675     return bitc::ATTR_KIND_OPTIMIZE_NONE;
676   case Attribute::ReadNone:
677     return bitc::ATTR_KIND_READ_NONE;
678   case Attribute::ReadOnly:
679     return bitc::ATTR_KIND_READ_ONLY;
680   case Attribute::Returned:
681     return bitc::ATTR_KIND_RETURNED;
682   case Attribute::ReturnsTwice:
683     return bitc::ATTR_KIND_RETURNS_TWICE;
684   case Attribute::SExt:
685     return bitc::ATTR_KIND_S_EXT;
686   case Attribute::Speculatable:
687     return bitc::ATTR_KIND_SPECULATABLE;
688   case Attribute::StackAlignment:
689     return bitc::ATTR_KIND_STACK_ALIGNMENT;
690   case Attribute::StackProtect:
691     return bitc::ATTR_KIND_STACK_PROTECT;
692   case Attribute::StackProtectReq:
693     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
694   case Attribute::StackProtectStrong:
695     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
696   case Attribute::SafeStack:
697     return bitc::ATTR_KIND_SAFESTACK;
698   case Attribute::ShadowCallStack:
699     return bitc::ATTR_KIND_SHADOWCALLSTACK;
700   case Attribute::StrictFP:
701     return bitc::ATTR_KIND_STRICT_FP;
702   case Attribute::StructRet:
703     return bitc::ATTR_KIND_STRUCT_RET;
704   case Attribute::SanitizeAddress:
705     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
706   case Attribute::SanitizeHWAddress:
707     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
708   case Attribute::SanitizeThread:
709     return bitc::ATTR_KIND_SANITIZE_THREAD;
710   case Attribute::SanitizeMemory:
711     return bitc::ATTR_KIND_SANITIZE_MEMORY;
712   case Attribute::SpeculativeLoadHardening:
713     return bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING;
714   case Attribute::SwiftError:
715     return bitc::ATTR_KIND_SWIFT_ERROR;
716   case Attribute::SwiftSelf:
717     return bitc::ATTR_KIND_SWIFT_SELF;
718   case Attribute::UWTable:
719     return bitc::ATTR_KIND_UW_TABLE;
720   case Attribute::WillReturn:
721     return bitc::ATTR_KIND_WILLRETURN;
722   case Attribute::WriteOnly:
723     return bitc::ATTR_KIND_WRITEONLY;
724   case Attribute::ZExt:
725     return bitc::ATTR_KIND_Z_EXT;
726   case Attribute::ImmArg:
727     return bitc::ATTR_KIND_IMMARG;
728   case Attribute::SanitizeMemTag:
729     return bitc::ATTR_KIND_SANITIZE_MEMTAG;
730   case Attribute::Preallocated:
731     return bitc::ATTR_KIND_PREALLOCATED;
732   case Attribute::EndAttrKinds:
733     llvm_unreachable("Can not encode end-attribute kinds marker.");
734   case Attribute::None:
735     llvm_unreachable("Can not encode none-attribute.");
736   case Attribute::EmptyKey:
737   case Attribute::TombstoneKey:
738     llvm_unreachable("Trying to encode EmptyKey/TombstoneKey");
739   }
740 
741   llvm_unreachable("Trying to encode unknown attribute");
742 }
743 
744 void ModuleBitcodeWriter::writeAttributeGroupTable() {
745   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
746       VE.getAttributeGroups();
747   if (AttrGrps.empty()) return;
748 
749   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
750 
751   SmallVector<uint64_t, 64> Record;
752   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
753     unsigned AttrListIndex = Pair.first;
754     AttributeSet AS = Pair.second;
755     Record.push_back(VE.getAttributeGroupID(Pair));
756     Record.push_back(AttrListIndex);
757 
758     for (Attribute Attr : AS) {
759       if (Attr.isEnumAttribute()) {
760         Record.push_back(0);
761         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
762       } else if (Attr.isIntAttribute()) {
763         Record.push_back(1);
764         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
765         Record.push_back(Attr.getValueAsInt());
766       } else if (Attr.isStringAttribute()) {
767         StringRef Kind = Attr.getKindAsString();
768         StringRef Val = Attr.getValueAsString();
769 
770         Record.push_back(Val.empty() ? 3 : 4);
771         Record.append(Kind.begin(), Kind.end());
772         Record.push_back(0);
773         if (!Val.empty()) {
774           Record.append(Val.begin(), Val.end());
775           Record.push_back(0);
776         }
777       } else {
778         assert(Attr.isTypeAttribute());
779         Type *Ty = Attr.getValueAsType();
780         Record.push_back(Ty ? 6 : 5);
781         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
782         if (Ty)
783           Record.push_back(VE.getTypeID(Attr.getValueAsType()));
784       }
785     }
786 
787     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
788     Record.clear();
789   }
790 
791   Stream.ExitBlock();
792 }
793 
794 void ModuleBitcodeWriter::writeAttributeTable() {
795   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
796   if (Attrs.empty()) return;
797 
798   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
799 
800   SmallVector<uint64_t, 64> Record;
801   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
802     AttributeList AL = Attrs[i];
803     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
804       AttributeSet AS = AL.getAttributes(i);
805       if (AS.hasAttributes())
806         Record.push_back(VE.getAttributeGroupID({i, AS}));
807     }
808 
809     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
810     Record.clear();
811   }
812 
813   Stream.ExitBlock();
814 }
815 
816 /// WriteTypeTable - Write out the type table for a module.
817 void ModuleBitcodeWriter::writeTypeTable() {
818   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
819 
820   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
821   SmallVector<uint64_t, 64> TypeVals;
822 
823   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
824 
825   // Abbrev for TYPE_CODE_POINTER.
826   auto Abbv = std::make_shared<BitCodeAbbrev>();
827   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
828   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
829   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
830   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
831 
832   // Abbrev for TYPE_CODE_FUNCTION.
833   Abbv = std::make_shared<BitCodeAbbrev>();
834   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
835   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
836   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
837   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
838   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
839 
840   // Abbrev for TYPE_CODE_STRUCT_ANON.
841   Abbv = std::make_shared<BitCodeAbbrev>();
842   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
843   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
844   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
845   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
846   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
847 
848   // Abbrev for TYPE_CODE_STRUCT_NAME.
849   Abbv = std::make_shared<BitCodeAbbrev>();
850   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
851   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
852   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
853   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
854 
855   // Abbrev for TYPE_CODE_STRUCT_NAMED.
856   Abbv = std::make_shared<BitCodeAbbrev>();
857   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
858   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
859   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
860   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
861   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
862 
863   // Abbrev for TYPE_CODE_ARRAY.
864   Abbv = std::make_shared<BitCodeAbbrev>();
865   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
866   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
867   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
868   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
869 
870   // Emit an entry count so the reader can reserve space.
871   TypeVals.push_back(TypeList.size());
872   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
873   TypeVals.clear();
874 
875   // Loop over all of the types, emitting each in turn.
876   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
877     Type *T = TypeList[i];
878     int AbbrevToUse = 0;
879     unsigned Code = 0;
880 
881     switch (T->getTypeID()) {
882     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
883     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
884     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
885     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
886     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
887     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
888     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
889     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
890     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
891     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
892     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
893     case Type::IntegerTyID:
894       // INTEGER: [width]
895       Code = bitc::TYPE_CODE_INTEGER;
896       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
897       break;
898     case Type::PointerTyID: {
899       PointerType *PTy = cast<PointerType>(T);
900       // POINTER: [pointee type, address space]
901       Code = bitc::TYPE_CODE_POINTER;
902       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
903       unsigned AddressSpace = PTy->getAddressSpace();
904       TypeVals.push_back(AddressSpace);
905       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
906       break;
907     }
908     case Type::FunctionTyID: {
909       FunctionType *FT = cast<FunctionType>(T);
910       // FUNCTION: [isvararg, retty, paramty x N]
911       Code = bitc::TYPE_CODE_FUNCTION;
912       TypeVals.push_back(FT->isVarArg());
913       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
914       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
915         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
916       AbbrevToUse = FunctionAbbrev;
917       break;
918     }
919     case Type::StructTyID: {
920       StructType *ST = cast<StructType>(T);
921       // STRUCT: [ispacked, eltty x N]
922       TypeVals.push_back(ST->isPacked());
923       // Output all of the element types.
924       for (StructType::element_iterator I = ST->element_begin(),
925            E = ST->element_end(); I != E; ++I)
926         TypeVals.push_back(VE.getTypeID(*I));
927 
928       if (ST->isLiteral()) {
929         Code = bitc::TYPE_CODE_STRUCT_ANON;
930         AbbrevToUse = StructAnonAbbrev;
931       } else {
932         if (ST->isOpaque()) {
933           Code = bitc::TYPE_CODE_OPAQUE;
934         } else {
935           Code = bitc::TYPE_CODE_STRUCT_NAMED;
936           AbbrevToUse = StructNamedAbbrev;
937         }
938 
939         // Emit the name if it is present.
940         if (!ST->getName().empty())
941           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
942                             StructNameAbbrev);
943       }
944       break;
945     }
946     case Type::ArrayTyID: {
947       ArrayType *AT = cast<ArrayType>(T);
948       // ARRAY: [numelts, eltty]
949       Code = bitc::TYPE_CODE_ARRAY;
950       TypeVals.push_back(AT->getNumElements());
951       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
952       AbbrevToUse = ArrayAbbrev;
953       break;
954     }
955     case Type::FixedVectorTyID:
956     case Type::ScalableVectorTyID: {
957       VectorType *VT = cast<VectorType>(T);
958       // VECTOR [numelts, eltty] or
959       //        [numelts, eltty, scalable]
960       Code = bitc::TYPE_CODE_VECTOR;
961       TypeVals.push_back(VT->getNumElements());
962       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
963       if (isa<ScalableVectorType>(VT))
964         TypeVals.push_back(true);
965       break;
966     }
967     }
968 
969     // Emit the finished record.
970     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
971     TypeVals.clear();
972   }
973 
974   Stream.ExitBlock();
975 }
976 
977 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
978   switch (Linkage) {
979   case GlobalValue::ExternalLinkage:
980     return 0;
981   case GlobalValue::WeakAnyLinkage:
982     return 16;
983   case GlobalValue::AppendingLinkage:
984     return 2;
985   case GlobalValue::InternalLinkage:
986     return 3;
987   case GlobalValue::LinkOnceAnyLinkage:
988     return 18;
989   case GlobalValue::ExternalWeakLinkage:
990     return 7;
991   case GlobalValue::CommonLinkage:
992     return 8;
993   case GlobalValue::PrivateLinkage:
994     return 9;
995   case GlobalValue::WeakODRLinkage:
996     return 17;
997   case GlobalValue::LinkOnceODRLinkage:
998     return 19;
999   case GlobalValue::AvailableExternallyLinkage:
1000     return 12;
1001   }
1002   llvm_unreachable("Invalid linkage");
1003 }
1004 
1005 static unsigned getEncodedLinkage(const GlobalValue &GV) {
1006   return getEncodedLinkage(GV.getLinkage());
1007 }
1008 
1009 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
1010   uint64_t RawFlags = 0;
1011   RawFlags |= Flags.ReadNone;
1012   RawFlags |= (Flags.ReadOnly << 1);
1013   RawFlags |= (Flags.NoRecurse << 2);
1014   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
1015   RawFlags |= (Flags.NoInline << 4);
1016   RawFlags |= (Flags.AlwaysInline << 5);
1017   return RawFlags;
1018 }
1019 
1020 // Decode the flags for GlobalValue in the summary
1021 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
1022   uint64_t RawFlags = 0;
1023 
1024   RawFlags |= Flags.NotEligibleToImport; // bool
1025   RawFlags |= (Flags.Live << 1);
1026   RawFlags |= (Flags.DSOLocal << 2);
1027   RawFlags |= (Flags.CanAutoHide << 3);
1028 
1029   // Linkage don't need to be remapped at that time for the summary. Any future
1030   // change to the getEncodedLinkage() function will need to be taken into
1031   // account here as well.
1032   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
1033 
1034   return RawFlags;
1035 }
1036 
1037 static uint64_t getEncodedGVarFlags(GlobalVarSummary::GVarFlags Flags) {
1038   uint64_t RawFlags = Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) |
1039                       (Flags.Constant << 2) | Flags.VCallVisibility << 3;
1040   return RawFlags;
1041 }
1042 
1043 static unsigned getEncodedVisibility(const GlobalValue &GV) {
1044   switch (GV.getVisibility()) {
1045   case GlobalValue::DefaultVisibility:   return 0;
1046   case GlobalValue::HiddenVisibility:    return 1;
1047   case GlobalValue::ProtectedVisibility: return 2;
1048   }
1049   llvm_unreachable("Invalid visibility");
1050 }
1051 
1052 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1053   switch (GV.getDLLStorageClass()) {
1054   case GlobalValue::DefaultStorageClass:   return 0;
1055   case GlobalValue::DLLImportStorageClass: return 1;
1056   case GlobalValue::DLLExportStorageClass: return 2;
1057   }
1058   llvm_unreachable("Invalid DLL storage class");
1059 }
1060 
1061 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1062   switch (GV.getThreadLocalMode()) {
1063     case GlobalVariable::NotThreadLocal:         return 0;
1064     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1065     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1066     case GlobalVariable::InitialExecTLSModel:    return 3;
1067     case GlobalVariable::LocalExecTLSModel:      return 4;
1068   }
1069   llvm_unreachable("Invalid TLS model");
1070 }
1071 
1072 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1073   switch (C.getSelectionKind()) {
1074   case Comdat::Any:
1075     return bitc::COMDAT_SELECTION_KIND_ANY;
1076   case Comdat::ExactMatch:
1077     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1078   case Comdat::Largest:
1079     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1080   case Comdat::NoDuplicates:
1081     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1082   case Comdat::SameSize:
1083     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1084   }
1085   llvm_unreachable("Invalid selection kind");
1086 }
1087 
1088 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1089   switch (GV.getUnnamedAddr()) {
1090   case GlobalValue::UnnamedAddr::None:   return 0;
1091   case GlobalValue::UnnamedAddr::Local:  return 2;
1092   case GlobalValue::UnnamedAddr::Global: return 1;
1093   }
1094   llvm_unreachable("Invalid unnamed_addr");
1095 }
1096 
1097 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1098   if (GenerateHash)
1099     Hasher.update(Str);
1100   return StrtabBuilder.add(Str);
1101 }
1102 
1103 void ModuleBitcodeWriter::writeComdats() {
1104   SmallVector<unsigned, 64> Vals;
1105   for (const Comdat *C : VE.getComdats()) {
1106     // COMDAT: [strtab offset, strtab size, selection_kind]
1107     Vals.push_back(addToStrtab(C->getName()));
1108     Vals.push_back(C->getName().size());
1109     Vals.push_back(getEncodedComdatSelectionKind(*C));
1110     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1111     Vals.clear();
1112   }
1113 }
1114 
1115 /// Write a record that will eventually hold the word offset of the
1116 /// module-level VST. For now the offset is 0, which will be backpatched
1117 /// after the real VST is written. Saves the bit offset to backpatch.
1118 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1119   // Write a placeholder value in for the offset of the real VST,
1120   // which is written after the function blocks so that it can include
1121   // the offset of each function. The placeholder offset will be
1122   // updated when the real VST is written.
1123   auto Abbv = std::make_shared<BitCodeAbbrev>();
1124   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1125   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1126   // hold the real VST offset. Must use fixed instead of VBR as we don't
1127   // know how many VBR chunks to reserve ahead of time.
1128   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1129   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1130 
1131   // Emit the placeholder
1132   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1133   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1134 
1135   // Compute and save the bit offset to the placeholder, which will be
1136   // patched when the real VST is written. We can simply subtract the 32-bit
1137   // fixed size from the current bit number to get the location to backpatch.
1138   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1139 }
1140 
1141 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1142 
1143 /// Determine the encoding to use for the given string name and length.
1144 static StringEncoding getStringEncoding(StringRef Str) {
1145   bool isChar6 = true;
1146   for (char C : Str) {
1147     if (isChar6)
1148       isChar6 = BitCodeAbbrevOp::isChar6(C);
1149     if ((unsigned char)C & 128)
1150       // don't bother scanning the rest.
1151       return SE_Fixed8;
1152   }
1153   if (isChar6)
1154     return SE_Char6;
1155   return SE_Fixed7;
1156 }
1157 
1158 /// Emit top-level description of module, including target triple, inline asm,
1159 /// descriptors for global variables, and function prototype info.
1160 /// Returns the bit offset to backpatch with the location of the real VST.
1161 void ModuleBitcodeWriter::writeModuleInfo() {
1162   // Emit various pieces of data attached to a module.
1163   if (!M.getTargetTriple().empty())
1164     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1165                       0 /*TODO*/);
1166   const std::string &DL = M.getDataLayoutStr();
1167   if (!DL.empty())
1168     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1169   if (!M.getModuleInlineAsm().empty())
1170     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1171                       0 /*TODO*/);
1172 
1173   // Emit information about sections and GC, computing how many there are. Also
1174   // compute the maximum alignment value.
1175   std::map<std::string, unsigned> SectionMap;
1176   std::map<std::string, unsigned> GCMap;
1177   unsigned MaxAlignment = 0;
1178   unsigned MaxGlobalType = 0;
1179   for (const GlobalValue &GV : M.globals()) {
1180     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1181     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1182     if (GV.hasSection()) {
1183       // Give section names unique ID's.
1184       unsigned &Entry = SectionMap[std::string(GV.getSection())];
1185       if (!Entry) {
1186         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1187                           0 /*TODO*/);
1188         Entry = SectionMap.size();
1189       }
1190     }
1191   }
1192   for (const Function &F : M) {
1193     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1194     if (F.hasSection()) {
1195       // Give section names unique ID's.
1196       unsigned &Entry = SectionMap[std::string(F.getSection())];
1197       if (!Entry) {
1198         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1199                           0 /*TODO*/);
1200         Entry = SectionMap.size();
1201       }
1202     }
1203     if (F.hasGC()) {
1204       // Same for GC names.
1205       unsigned &Entry = GCMap[F.getGC()];
1206       if (!Entry) {
1207         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1208                           0 /*TODO*/);
1209         Entry = GCMap.size();
1210       }
1211     }
1212   }
1213 
1214   // Emit abbrev for globals, now that we know # sections and max alignment.
1215   unsigned SimpleGVarAbbrev = 0;
1216   if (!M.global_empty()) {
1217     // Add an abbrev for common globals with no visibility or thread localness.
1218     auto Abbv = std::make_shared<BitCodeAbbrev>();
1219     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1220     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1223                               Log2_32_Ceil(MaxGlobalType+1)));
1224     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1225                                                            //| explicitType << 1
1226                                                            //| constant
1227     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1228     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1229     if (MaxAlignment == 0)                                 // Alignment.
1230       Abbv->Add(BitCodeAbbrevOp(0));
1231     else {
1232       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1233       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1234                                Log2_32_Ceil(MaxEncAlignment+1)));
1235     }
1236     if (SectionMap.empty())                                    // Section.
1237       Abbv->Add(BitCodeAbbrevOp(0));
1238     else
1239       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1240                                Log2_32_Ceil(SectionMap.size()+1)));
1241     // Don't bother emitting vis + thread local.
1242     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1243   }
1244 
1245   SmallVector<unsigned, 64> Vals;
1246   // Emit the module's source file name.
1247   {
1248     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1249     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1250     if (Bits == SE_Char6)
1251       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1252     else if (Bits == SE_Fixed7)
1253       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1254 
1255     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1256     auto Abbv = std::make_shared<BitCodeAbbrev>();
1257     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1258     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1259     Abbv->Add(AbbrevOpToUse);
1260     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1261 
1262     for (const auto P : M.getSourceFileName())
1263       Vals.push_back((unsigned char)P);
1264 
1265     // Emit the finished record.
1266     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1267     Vals.clear();
1268   }
1269 
1270   // Emit the global variable information.
1271   for (const GlobalVariable &GV : M.globals()) {
1272     unsigned AbbrevToUse = 0;
1273 
1274     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1275     //             linkage, alignment, section, visibility, threadlocal,
1276     //             unnamed_addr, externally_initialized, dllstorageclass,
1277     //             comdat, attributes, DSO_Local]
1278     Vals.push_back(addToStrtab(GV.getName()));
1279     Vals.push_back(GV.getName().size());
1280     Vals.push_back(VE.getTypeID(GV.getValueType()));
1281     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1282     Vals.push_back(GV.isDeclaration() ? 0 :
1283                    (VE.getValueID(GV.getInitializer()) + 1));
1284     Vals.push_back(getEncodedLinkage(GV));
1285     Vals.push_back(Log2_32(GV.getAlignment())+1);
1286     Vals.push_back(GV.hasSection() ? SectionMap[std::string(GV.getSection())]
1287                                    : 0);
1288     if (GV.isThreadLocal() ||
1289         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1290         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1291         GV.isExternallyInitialized() ||
1292         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1293         GV.hasComdat() ||
1294         GV.hasAttributes() ||
1295         GV.isDSOLocal() ||
1296         GV.hasPartition()) {
1297       Vals.push_back(getEncodedVisibility(GV));
1298       Vals.push_back(getEncodedThreadLocalMode(GV));
1299       Vals.push_back(getEncodedUnnamedAddr(GV));
1300       Vals.push_back(GV.isExternallyInitialized());
1301       Vals.push_back(getEncodedDLLStorageClass(GV));
1302       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1303 
1304       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1305       Vals.push_back(VE.getAttributeListID(AL));
1306 
1307       Vals.push_back(GV.isDSOLocal());
1308       Vals.push_back(addToStrtab(GV.getPartition()));
1309       Vals.push_back(GV.getPartition().size());
1310     } else {
1311       AbbrevToUse = SimpleGVarAbbrev;
1312     }
1313 
1314     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1315     Vals.clear();
1316   }
1317 
1318   // Emit the function proto information.
1319   for (const Function &F : M) {
1320     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1321     //             linkage, paramattrs, alignment, section, visibility, gc,
1322     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1323     //             prefixdata, personalityfn, DSO_Local, addrspace]
1324     Vals.push_back(addToStrtab(F.getName()));
1325     Vals.push_back(F.getName().size());
1326     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1327     Vals.push_back(F.getCallingConv());
1328     Vals.push_back(F.isDeclaration());
1329     Vals.push_back(getEncodedLinkage(F));
1330     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1331     Vals.push_back(Log2_32(F.getAlignment())+1);
1332     Vals.push_back(F.hasSection() ? SectionMap[std::string(F.getSection())]
1333                                   : 0);
1334     Vals.push_back(getEncodedVisibility(F));
1335     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1336     Vals.push_back(getEncodedUnnamedAddr(F));
1337     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1338                                        : 0);
1339     Vals.push_back(getEncodedDLLStorageClass(F));
1340     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1341     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1342                                      : 0);
1343     Vals.push_back(
1344         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1345 
1346     Vals.push_back(F.isDSOLocal());
1347     Vals.push_back(F.getAddressSpace());
1348     Vals.push_back(addToStrtab(F.getPartition()));
1349     Vals.push_back(F.getPartition().size());
1350 
1351     unsigned AbbrevToUse = 0;
1352     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1353     Vals.clear();
1354   }
1355 
1356   // Emit the alias information.
1357   for (const GlobalAlias &A : M.aliases()) {
1358     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1359     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1360     //         DSO_Local]
1361     Vals.push_back(addToStrtab(A.getName()));
1362     Vals.push_back(A.getName().size());
1363     Vals.push_back(VE.getTypeID(A.getValueType()));
1364     Vals.push_back(A.getType()->getAddressSpace());
1365     Vals.push_back(VE.getValueID(A.getAliasee()));
1366     Vals.push_back(getEncodedLinkage(A));
1367     Vals.push_back(getEncodedVisibility(A));
1368     Vals.push_back(getEncodedDLLStorageClass(A));
1369     Vals.push_back(getEncodedThreadLocalMode(A));
1370     Vals.push_back(getEncodedUnnamedAddr(A));
1371     Vals.push_back(A.isDSOLocal());
1372     Vals.push_back(addToStrtab(A.getPartition()));
1373     Vals.push_back(A.getPartition().size());
1374 
1375     unsigned AbbrevToUse = 0;
1376     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1377     Vals.clear();
1378   }
1379 
1380   // Emit the ifunc information.
1381   for (const GlobalIFunc &I : M.ifuncs()) {
1382     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1383     //         val#, linkage, visibility, DSO_Local]
1384     Vals.push_back(addToStrtab(I.getName()));
1385     Vals.push_back(I.getName().size());
1386     Vals.push_back(VE.getTypeID(I.getValueType()));
1387     Vals.push_back(I.getType()->getAddressSpace());
1388     Vals.push_back(VE.getValueID(I.getResolver()));
1389     Vals.push_back(getEncodedLinkage(I));
1390     Vals.push_back(getEncodedVisibility(I));
1391     Vals.push_back(I.isDSOLocal());
1392     Vals.push_back(addToStrtab(I.getPartition()));
1393     Vals.push_back(I.getPartition().size());
1394     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1395     Vals.clear();
1396   }
1397 
1398   writeValueSymbolTableForwardDecl();
1399 }
1400 
1401 static uint64_t getOptimizationFlags(const Value *V) {
1402   uint64_t Flags = 0;
1403 
1404   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1405     if (OBO->hasNoSignedWrap())
1406       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1407     if (OBO->hasNoUnsignedWrap())
1408       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1409   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1410     if (PEO->isExact())
1411       Flags |= 1 << bitc::PEO_EXACT;
1412   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1413     if (FPMO->hasAllowReassoc())
1414       Flags |= bitc::AllowReassoc;
1415     if (FPMO->hasNoNaNs())
1416       Flags |= bitc::NoNaNs;
1417     if (FPMO->hasNoInfs())
1418       Flags |= bitc::NoInfs;
1419     if (FPMO->hasNoSignedZeros())
1420       Flags |= bitc::NoSignedZeros;
1421     if (FPMO->hasAllowReciprocal())
1422       Flags |= bitc::AllowReciprocal;
1423     if (FPMO->hasAllowContract())
1424       Flags |= bitc::AllowContract;
1425     if (FPMO->hasApproxFunc())
1426       Flags |= bitc::ApproxFunc;
1427   }
1428 
1429   return Flags;
1430 }
1431 
1432 void ModuleBitcodeWriter::writeValueAsMetadata(
1433     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1434   // Mimic an MDNode with a value as one operand.
1435   Value *V = MD->getValue();
1436   Record.push_back(VE.getTypeID(V->getType()));
1437   Record.push_back(VE.getValueID(V));
1438   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1439   Record.clear();
1440 }
1441 
1442 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1443                                        SmallVectorImpl<uint64_t> &Record,
1444                                        unsigned Abbrev) {
1445   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1446     Metadata *MD = N->getOperand(i);
1447     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1448            "Unexpected function-local metadata");
1449     Record.push_back(VE.getMetadataOrNullID(MD));
1450   }
1451   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1452                                     : bitc::METADATA_NODE,
1453                     Record, Abbrev);
1454   Record.clear();
1455 }
1456 
1457 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1458   // Assume the column is usually under 128, and always output the inlined-at
1459   // location (it's never more expensive than building an array size 1).
1460   auto Abbv = std::make_shared<BitCodeAbbrev>();
1461   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1462   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1463   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1464   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1465   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1466   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1467   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1468   return Stream.EmitAbbrev(std::move(Abbv));
1469 }
1470 
1471 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1472                                           SmallVectorImpl<uint64_t> &Record,
1473                                           unsigned &Abbrev) {
1474   if (!Abbrev)
1475     Abbrev = createDILocationAbbrev();
1476 
1477   Record.push_back(N->isDistinct());
1478   Record.push_back(N->getLine());
1479   Record.push_back(N->getColumn());
1480   Record.push_back(VE.getMetadataID(N->getScope()));
1481   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1482   Record.push_back(N->isImplicitCode());
1483 
1484   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1485   Record.clear();
1486 }
1487 
1488 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1489   // Assume the column is usually under 128, and always output the inlined-at
1490   // location (it's never more expensive than building an array size 1).
1491   auto Abbv = std::make_shared<BitCodeAbbrev>();
1492   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1493   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1494   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1495   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1496   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1497   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1498   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1499   return Stream.EmitAbbrev(std::move(Abbv));
1500 }
1501 
1502 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1503                                              SmallVectorImpl<uint64_t> &Record,
1504                                              unsigned &Abbrev) {
1505   if (!Abbrev)
1506     Abbrev = createGenericDINodeAbbrev();
1507 
1508   Record.push_back(N->isDistinct());
1509   Record.push_back(N->getTag());
1510   Record.push_back(0); // Per-tag version field; unused for now.
1511 
1512   for (auto &I : N->operands())
1513     Record.push_back(VE.getMetadataOrNullID(I));
1514 
1515   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1516   Record.clear();
1517 }
1518 
1519 static uint64_t rotateSign(int64_t I) {
1520   uint64_t U = I;
1521   return I < 0 ? ~(U << 1) : U << 1;
1522 }
1523 
1524 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1525                                           SmallVectorImpl<uint64_t> &Record,
1526                                           unsigned Abbrev) {
1527   const uint64_t Version = 1 << 1;
1528   Record.push_back((uint64_t)N->isDistinct() | Version);
1529   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1530   Record.push_back(rotateSign(N->getLowerBound()));
1531 
1532   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1533   Record.clear();
1534 }
1535 
1536 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1537   if ((int64_t)V >= 0)
1538     Vals.push_back(V << 1);
1539   else
1540     Vals.push_back((-V << 1) | 1);
1541 }
1542 
1543 static void emitWideAPInt(SmallVectorImpl<uint64_t> &Vals, const APInt &A) {
1544   // We have an arbitrary precision integer value to write whose
1545   // bit width is > 64. However, in canonical unsigned integer
1546   // format it is likely that the high bits are going to be zero.
1547   // So, we only write the number of active words.
1548   unsigned NumWords = A.getActiveWords();
1549   const uint64_t *RawData = A.getRawData();
1550   for (unsigned i = 0; i < NumWords; i++)
1551     emitSignedInt64(Vals, RawData[i]);
1552 }
1553 
1554 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1555                                             SmallVectorImpl<uint64_t> &Record,
1556                                             unsigned Abbrev) {
1557   const uint64_t IsBigInt = 1 << 2;
1558   Record.push_back(IsBigInt | (N->isUnsigned() << 1) | N->isDistinct());
1559   Record.push_back(N->getValue().getBitWidth());
1560   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1561   emitWideAPInt(Record, N->getValue());
1562 
1563   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1564   Record.clear();
1565 }
1566 
1567 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1568                                            SmallVectorImpl<uint64_t> &Record,
1569                                            unsigned Abbrev) {
1570   Record.push_back(N->isDistinct());
1571   Record.push_back(N->getTag());
1572   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1573   Record.push_back(N->getSizeInBits());
1574   Record.push_back(N->getAlignInBits());
1575   Record.push_back(N->getEncoding());
1576   Record.push_back(N->getFlags());
1577 
1578   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1579   Record.clear();
1580 }
1581 
1582 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1583                                              SmallVectorImpl<uint64_t> &Record,
1584                                              unsigned Abbrev) {
1585   Record.push_back(N->isDistinct());
1586   Record.push_back(N->getTag());
1587   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1588   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1589   Record.push_back(N->getLine());
1590   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1591   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1592   Record.push_back(N->getSizeInBits());
1593   Record.push_back(N->getAlignInBits());
1594   Record.push_back(N->getOffsetInBits());
1595   Record.push_back(N->getFlags());
1596   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1597 
1598   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1599   // that there is no DWARF address space associated with DIDerivedType.
1600   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1601     Record.push_back(*DWARFAddressSpace + 1);
1602   else
1603     Record.push_back(0);
1604 
1605   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1606   Record.clear();
1607 }
1608 
1609 void ModuleBitcodeWriter::writeDICompositeType(
1610     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1611     unsigned Abbrev) {
1612   const unsigned IsNotUsedInOldTypeRef = 0x2;
1613   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1614   Record.push_back(N->getTag());
1615   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1616   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1617   Record.push_back(N->getLine());
1618   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1619   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1620   Record.push_back(N->getSizeInBits());
1621   Record.push_back(N->getAlignInBits());
1622   Record.push_back(N->getOffsetInBits());
1623   Record.push_back(N->getFlags());
1624   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1625   Record.push_back(N->getRuntimeLang());
1626   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1627   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1628   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1629   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1630 
1631   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1632   Record.clear();
1633 }
1634 
1635 void ModuleBitcodeWriter::writeDISubroutineType(
1636     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1637     unsigned Abbrev) {
1638   const unsigned HasNoOldTypeRefs = 0x2;
1639   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1640   Record.push_back(N->getFlags());
1641   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1642   Record.push_back(N->getCC());
1643 
1644   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1645   Record.clear();
1646 }
1647 
1648 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1649                                       SmallVectorImpl<uint64_t> &Record,
1650                                       unsigned Abbrev) {
1651   Record.push_back(N->isDistinct());
1652   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1653   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1654   if (N->getRawChecksum()) {
1655     Record.push_back(N->getRawChecksum()->Kind);
1656     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1657   } else {
1658     // Maintain backwards compatibility with the old internal representation of
1659     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1660     Record.push_back(0);
1661     Record.push_back(VE.getMetadataOrNullID(nullptr));
1662   }
1663   auto Source = N->getRawSource();
1664   if (Source)
1665     Record.push_back(VE.getMetadataOrNullID(*Source));
1666 
1667   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1668   Record.clear();
1669 }
1670 
1671 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1672                                              SmallVectorImpl<uint64_t> &Record,
1673                                              unsigned Abbrev) {
1674   assert(N->isDistinct() && "Expected distinct compile units");
1675   Record.push_back(/* IsDistinct */ true);
1676   Record.push_back(N->getSourceLanguage());
1677   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1678   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1679   Record.push_back(N->isOptimized());
1680   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1681   Record.push_back(N->getRuntimeVersion());
1682   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1683   Record.push_back(N->getEmissionKind());
1684   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1685   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1686   Record.push_back(/* subprograms */ 0);
1687   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1688   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1689   Record.push_back(N->getDWOId());
1690   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1691   Record.push_back(N->getSplitDebugInlining());
1692   Record.push_back(N->getDebugInfoForProfiling());
1693   Record.push_back((unsigned)N->getNameTableKind());
1694   Record.push_back(N->getRangesBaseAddress());
1695   Record.push_back(VE.getMetadataOrNullID(N->getRawSysRoot()));
1696   Record.push_back(VE.getMetadataOrNullID(N->getRawSDK()));
1697 
1698   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1699   Record.clear();
1700 }
1701 
1702 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1703                                             SmallVectorImpl<uint64_t> &Record,
1704                                             unsigned Abbrev) {
1705   const uint64_t HasUnitFlag = 1 << 1;
1706   const uint64_t HasSPFlagsFlag = 1 << 2;
1707   Record.push_back(uint64_t(N->isDistinct()) | HasUnitFlag | HasSPFlagsFlag);
1708   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1709   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1710   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1711   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1712   Record.push_back(N->getLine());
1713   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1714   Record.push_back(N->getScopeLine());
1715   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1716   Record.push_back(N->getSPFlags());
1717   Record.push_back(N->getVirtualIndex());
1718   Record.push_back(N->getFlags());
1719   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1720   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1721   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1722   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1723   Record.push_back(N->getThisAdjustment());
1724   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1725 
1726   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1727   Record.clear();
1728 }
1729 
1730 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1731                                               SmallVectorImpl<uint64_t> &Record,
1732                                               unsigned Abbrev) {
1733   Record.push_back(N->isDistinct());
1734   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1735   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1736   Record.push_back(N->getLine());
1737   Record.push_back(N->getColumn());
1738 
1739   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1740   Record.clear();
1741 }
1742 
1743 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1744     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1745     unsigned Abbrev) {
1746   Record.push_back(N->isDistinct());
1747   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1748   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1749   Record.push_back(N->getDiscriminator());
1750 
1751   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1752   Record.clear();
1753 }
1754 
1755 void ModuleBitcodeWriter::writeDICommonBlock(const DICommonBlock *N,
1756                                              SmallVectorImpl<uint64_t> &Record,
1757                                              unsigned Abbrev) {
1758   Record.push_back(N->isDistinct());
1759   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1760   Record.push_back(VE.getMetadataOrNullID(N->getDecl()));
1761   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1762   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1763   Record.push_back(N->getLineNo());
1764 
1765   Stream.EmitRecord(bitc::METADATA_COMMON_BLOCK, Record, Abbrev);
1766   Record.clear();
1767 }
1768 
1769 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1770                                            SmallVectorImpl<uint64_t> &Record,
1771                                            unsigned Abbrev) {
1772   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1773   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1774   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1775 
1776   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1777   Record.clear();
1778 }
1779 
1780 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1781                                        SmallVectorImpl<uint64_t> &Record,
1782                                        unsigned Abbrev) {
1783   Record.push_back(N->isDistinct());
1784   Record.push_back(N->getMacinfoType());
1785   Record.push_back(N->getLine());
1786   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1787   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1788 
1789   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1790   Record.clear();
1791 }
1792 
1793 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1794                                            SmallVectorImpl<uint64_t> &Record,
1795                                            unsigned Abbrev) {
1796   Record.push_back(N->isDistinct());
1797   Record.push_back(N->getMacinfoType());
1798   Record.push_back(N->getLine());
1799   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1800   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1801 
1802   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1803   Record.clear();
1804 }
1805 
1806 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1807                                         SmallVectorImpl<uint64_t> &Record,
1808                                         unsigned Abbrev) {
1809   Record.push_back(N->isDistinct());
1810   for (auto &I : N->operands())
1811     Record.push_back(VE.getMetadataOrNullID(I));
1812 
1813   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1814   Record.clear();
1815 }
1816 
1817 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1818     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1819     unsigned Abbrev) {
1820   Record.push_back(N->isDistinct());
1821   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1822   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1823   Record.push_back(N->isDefault());
1824 
1825   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1826   Record.clear();
1827 }
1828 
1829 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1830     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1831     unsigned Abbrev) {
1832   Record.push_back(N->isDistinct());
1833   Record.push_back(N->getTag());
1834   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1835   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1836   Record.push_back(N->isDefault());
1837   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1838 
1839   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1840   Record.clear();
1841 }
1842 
1843 void ModuleBitcodeWriter::writeDIGlobalVariable(
1844     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1845     unsigned Abbrev) {
1846   const uint64_t Version = 2 << 1;
1847   Record.push_back((uint64_t)N->isDistinct() | Version);
1848   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1849   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1850   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1851   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1852   Record.push_back(N->getLine());
1853   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1854   Record.push_back(N->isLocalToUnit());
1855   Record.push_back(N->isDefinition());
1856   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1857   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams()));
1858   Record.push_back(N->getAlignInBits());
1859 
1860   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1861   Record.clear();
1862 }
1863 
1864 void ModuleBitcodeWriter::writeDILocalVariable(
1865     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1866     unsigned Abbrev) {
1867   // In order to support all possible bitcode formats in BitcodeReader we need
1868   // to distinguish the following cases:
1869   // 1) Record has no artificial tag (Record[1]),
1870   //   has no obsolete inlinedAt field (Record[9]).
1871   //   In this case Record size will be 8, HasAlignment flag is false.
1872   // 2) Record has artificial tag (Record[1]),
1873   //   has no obsolete inlignedAt field (Record[9]).
1874   //   In this case Record size will be 9, HasAlignment flag is false.
1875   // 3) Record has both artificial tag (Record[1]) and
1876   //   obsolete inlignedAt field (Record[9]).
1877   //   In this case Record size will be 10, HasAlignment flag is false.
1878   // 4) Record has neither artificial tag, nor inlignedAt field, but
1879   //   HasAlignment flag is true and Record[8] contains alignment value.
1880   const uint64_t HasAlignmentFlag = 1 << 1;
1881   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1882   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1883   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1884   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1885   Record.push_back(N->getLine());
1886   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1887   Record.push_back(N->getArg());
1888   Record.push_back(N->getFlags());
1889   Record.push_back(N->getAlignInBits());
1890 
1891   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1892   Record.clear();
1893 }
1894 
1895 void ModuleBitcodeWriter::writeDILabel(
1896     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
1897     unsigned Abbrev) {
1898   Record.push_back((uint64_t)N->isDistinct());
1899   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1900   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1901   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1902   Record.push_back(N->getLine());
1903 
1904   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
1905   Record.clear();
1906 }
1907 
1908 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1909                                             SmallVectorImpl<uint64_t> &Record,
1910                                             unsigned Abbrev) {
1911   Record.reserve(N->getElements().size() + 1);
1912   const uint64_t Version = 3 << 1;
1913   Record.push_back((uint64_t)N->isDistinct() | Version);
1914   Record.append(N->elements_begin(), N->elements_end());
1915 
1916   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1917   Record.clear();
1918 }
1919 
1920 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1921     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1922     unsigned Abbrev) {
1923   Record.push_back(N->isDistinct());
1924   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1925   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1926 
1927   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1928   Record.clear();
1929 }
1930 
1931 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1932                                               SmallVectorImpl<uint64_t> &Record,
1933                                               unsigned Abbrev) {
1934   Record.push_back(N->isDistinct());
1935   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1936   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1937   Record.push_back(N->getLine());
1938   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1939   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1940   Record.push_back(N->getAttributes());
1941   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1942 
1943   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1944   Record.clear();
1945 }
1946 
1947 void ModuleBitcodeWriter::writeDIImportedEntity(
1948     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1949     unsigned Abbrev) {
1950   Record.push_back(N->isDistinct());
1951   Record.push_back(N->getTag());
1952   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1953   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1954   Record.push_back(N->getLine());
1955   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1956   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1957 
1958   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1959   Record.clear();
1960 }
1961 
1962 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1963   auto Abbv = std::make_shared<BitCodeAbbrev>();
1964   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1965   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1966   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1967   return Stream.EmitAbbrev(std::move(Abbv));
1968 }
1969 
1970 void ModuleBitcodeWriter::writeNamedMetadata(
1971     SmallVectorImpl<uint64_t> &Record) {
1972   if (M.named_metadata_empty())
1973     return;
1974 
1975   unsigned Abbrev = createNamedMetadataAbbrev();
1976   for (const NamedMDNode &NMD : M.named_metadata()) {
1977     // Write name.
1978     StringRef Str = NMD.getName();
1979     Record.append(Str.bytes_begin(), Str.bytes_end());
1980     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1981     Record.clear();
1982 
1983     // Write named metadata operands.
1984     for (const MDNode *N : NMD.operands())
1985       Record.push_back(VE.getMetadataID(N));
1986     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1987     Record.clear();
1988   }
1989 }
1990 
1991 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1992   auto Abbv = std::make_shared<BitCodeAbbrev>();
1993   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1994   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1995   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1996   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1997   return Stream.EmitAbbrev(std::move(Abbv));
1998 }
1999 
2000 /// Write out a record for MDString.
2001 ///
2002 /// All the metadata strings in a metadata block are emitted in a single
2003 /// record.  The sizes and strings themselves are shoved into a blob.
2004 void ModuleBitcodeWriter::writeMetadataStrings(
2005     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
2006   if (Strings.empty())
2007     return;
2008 
2009   // Start the record with the number of strings.
2010   Record.push_back(bitc::METADATA_STRINGS);
2011   Record.push_back(Strings.size());
2012 
2013   // Emit the sizes of the strings in the blob.
2014   SmallString<256> Blob;
2015   {
2016     BitstreamWriter W(Blob);
2017     for (const Metadata *MD : Strings)
2018       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
2019     W.FlushToWord();
2020   }
2021 
2022   // Add the offset to the strings to the record.
2023   Record.push_back(Blob.size());
2024 
2025   // Add the strings to the blob.
2026   for (const Metadata *MD : Strings)
2027     Blob.append(cast<MDString>(MD)->getString());
2028 
2029   // Emit the final record.
2030   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
2031   Record.clear();
2032 }
2033 
2034 // Generates an enum to use as an index in the Abbrev array of Metadata record.
2035 enum MetadataAbbrev : unsigned {
2036 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
2037 #include "llvm/IR/Metadata.def"
2038   LastPlusOne
2039 };
2040 
2041 void ModuleBitcodeWriter::writeMetadataRecords(
2042     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
2043     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
2044   if (MDs.empty())
2045     return;
2046 
2047   // Initialize MDNode abbreviations.
2048 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
2049 #include "llvm/IR/Metadata.def"
2050 
2051   for (const Metadata *MD : MDs) {
2052     if (IndexPos)
2053       IndexPos->push_back(Stream.GetCurrentBitNo());
2054     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
2055       assert(N->isResolved() && "Expected forward references to be resolved");
2056 
2057       switch (N->getMetadataID()) {
2058       default:
2059         llvm_unreachable("Invalid MDNode subclass");
2060 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
2061   case Metadata::CLASS##Kind:                                                  \
2062     if (MDAbbrevs)                                                             \
2063       write##CLASS(cast<CLASS>(N), Record,                                     \
2064                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
2065     else                                                                       \
2066       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
2067     continue;
2068 #include "llvm/IR/Metadata.def"
2069       }
2070     }
2071     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
2072   }
2073 }
2074 
2075 void ModuleBitcodeWriter::writeModuleMetadata() {
2076   if (!VE.hasMDs() && M.named_metadata_empty())
2077     return;
2078 
2079   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
2080   SmallVector<uint64_t, 64> Record;
2081 
2082   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
2083   // block and load any metadata.
2084   std::vector<unsigned> MDAbbrevs;
2085 
2086   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
2087   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
2088   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
2089       createGenericDINodeAbbrev();
2090 
2091   auto Abbv = std::make_shared<BitCodeAbbrev>();
2092   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
2093   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2094   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
2095   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2096 
2097   Abbv = std::make_shared<BitCodeAbbrev>();
2098   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
2099   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2100   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2101   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2102 
2103   // Emit MDStrings together upfront.
2104   writeMetadataStrings(VE.getMDStrings(), Record);
2105 
2106   // We only emit an index for the metadata record if we have more than a given
2107   // (naive) threshold of metadatas, otherwise it is not worth it.
2108   if (VE.getNonMDStrings().size() > IndexThreshold) {
2109     // Write a placeholder value in for the offset of the metadata index,
2110     // which is written after the records, so that it can include
2111     // the offset of each entry. The placeholder offset will be
2112     // updated after all records are emitted.
2113     uint64_t Vals[] = {0, 0};
2114     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2115   }
2116 
2117   // Compute and save the bit offset to the current position, which will be
2118   // patched when we emit the index later. We can simply subtract the 64-bit
2119   // fixed size from the current bit number to get the location to backpatch.
2120   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2121 
2122   // This index will contain the bitpos for each individual record.
2123   std::vector<uint64_t> IndexPos;
2124   IndexPos.reserve(VE.getNonMDStrings().size());
2125 
2126   // Write all the records
2127   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2128 
2129   if (VE.getNonMDStrings().size() > IndexThreshold) {
2130     // Now that we have emitted all the records we will emit the index. But
2131     // first
2132     // backpatch the forward reference so that the reader can skip the records
2133     // efficiently.
2134     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2135                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2136 
2137     // Delta encode the index.
2138     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2139     for (auto &Elt : IndexPos) {
2140       auto EltDelta = Elt - PreviousValue;
2141       PreviousValue = Elt;
2142       Elt = EltDelta;
2143     }
2144     // Emit the index record.
2145     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2146     IndexPos.clear();
2147   }
2148 
2149   // Write the named metadata now.
2150   writeNamedMetadata(Record);
2151 
2152   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2153     SmallVector<uint64_t, 4> Record;
2154     Record.push_back(VE.getValueID(&GO));
2155     pushGlobalMetadataAttachment(Record, GO);
2156     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2157   };
2158   for (const Function &F : M)
2159     if (F.isDeclaration() && F.hasMetadata())
2160       AddDeclAttachedMetadata(F);
2161   // FIXME: Only store metadata for declarations here, and move data for global
2162   // variable definitions to a separate block (PR28134).
2163   for (const GlobalVariable &GV : M.globals())
2164     if (GV.hasMetadata())
2165       AddDeclAttachedMetadata(GV);
2166 
2167   Stream.ExitBlock();
2168 }
2169 
2170 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2171   if (!VE.hasMDs())
2172     return;
2173 
2174   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2175   SmallVector<uint64_t, 64> Record;
2176   writeMetadataStrings(VE.getMDStrings(), Record);
2177   writeMetadataRecords(VE.getNonMDStrings(), Record);
2178   Stream.ExitBlock();
2179 }
2180 
2181 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2182     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2183   // [n x [id, mdnode]]
2184   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2185   GO.getAllMetadata(MDs);
2186   for (const auto &I : MDs) {
2187     Record.push_back(I.first);
2188     Record.push_back(VE.getMetadataID(I.second));
2189   }
2190 }
2191 
2192 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2193   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2194 
2195   SmallVector<uint64_t, 64> Record;
2196 
2197   if (F.hasMetadata()) {
2198     pushGlobalMetadataAttachment(Record, F);
2199     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2200     Record.clear();
2201   }
2202 
2203   // Write metadata attachments
2204   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2205   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2206   for (const BasicBlock &BB : F)
2207     for (const Instruction &I : BB) {
2208       MDs.clear();
2209       I.getAllMetadataOtherThanDebugLoc(MDs);
2210 
2211       // If no metadata, ignore instruction.
2212       if (MDs.empty()) continue;
2213 
2214       Record.push_back(VE.getInstructionID(&I));
2215 
2216       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2217         Record.push_back(MDs[i].first);
2218         Record.push_back(VE.getMetadataID(MDs[i].second));
2219       }
2220       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2221       Record.clear();
2222     }
2223 
2224   Stream.ExitBlock();
2225 }
2226 
2227 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2228   SmallVector<uint64_t, 64> Record;
2229 
2230   // Write metadata kinds
2231   // METADATA_KIND - [n x [id, name]]
2232   SmallVector<StringRef, 8> Names;
2233   M.getMDKindNames(Names);
2234 
2235   if (Names.empty()) return;
2236 
2237   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2238 
2239   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2240     Record.push_back(MDKindID);
2241     StringRef KName = Names[MDKindID];
2242     Record.append(KName.begin(), KName.end());
2243 
2244     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2245     Record.clear();
2246   }
2247 
2248   Stream.ExitBlock();
2249 }
2250 
2251 void ModuleBitcodeWriter::writeOperandBundleTags() {
2252   // Write metadata kinds
2253   //
2254   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2255   //
2256   // OPERAND_BUNDLE_TAG - [strchr x N]
2257 
2258   SmallVector<StringRef, 8> Tags;
2259   M.getOperandBundleTags(Tags);
2260 
2261   if (Tags.empty())
2262     return;
2263 
2264   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2265 
2266   SmallVector<uint64_t, 64> Record;
2267 
2268   for (auto Tag : Tags) {
2269     Record.append(Tag.begin(), Tag.end());
2270 
2271     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2272     Record.clear();
2273   }
2274 
2275   Stream.ExitBlock();
2276 }
2277 
2278 void ModuleBitcodeWriter::writeSyncScopeNames() {
2279   SmallVector<StringRef, 8> SSNs;
2280   M.getContext().getSyncScopeNames(SSNs);
2281   if (SSNs.empty())
2282     return;
2283 
2284   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2285 
2286   SmallVector<uint64_t, 64> Record;
2287   for (auto SSN : SSNs) {
2288     Record.append(SSN.begin(), SSN.end());
2289     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2290     Record.clear();
2291   }
2292 
2293   Stream.ExitBlock();
2294 }
2295 
2296 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2297                                          bool isGlobal) {
2298   if (FirstVal == LastVal) return;
2299 
2300   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2301 
2302   unsigned AggregateAbbrev = 0;
2303   unsigned String8Abbrev = 0;
2304   unsigned CString7Abbrev = 0;
2305   unsigned CString6Abbrev = 0;
2306   // If this is a constant pool for the module, emit module-specific abbrevs.
2307   if (isGlobal) {
2308     // Abbrev for CST_CODE_AGGREGATE.
2309     auto Abbv = std::make_shared<BitCodeAbbrev>();
2310     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2311     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2313     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2314 
2315     // Abbrev for CST_CODE_STRING.
2316     Abbv = std::make_shared<BitCodeAbbrev>();
2317     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2318     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2319     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2320     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2321     // Abbrev for CST_CODE_CSTRING.
2322     Abbv = std::make_shared<BitCodeAbbrev>();
2323     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2324     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2325     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2326     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2327     // Abbrev for CST_CODE_CSTRING.
2328     Abbv = std::make_shared<BitCodeAbbrev>();
2329     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2330     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2331     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2332     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2333   }
2334 
2335   SmallVector<uint64_t, 64> Record;
2336 
2337   const ValueEnumerator::ValueList &Vals = VE.getValues();
2338   Type *LastTy = nullptr;
2339   for (unsigned i = FirstVal; i != LastVal; ++i) {
2340     const Value *V = Vals[i].first;
2341     // If we need to switch types, do so now.
2342     if (V->getType() != LastTy) {
2343       LastTy = V->getType();
2344       Record.push_back(VE.getTypeID(LastTy));
2345       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2346                         CONSTANTS_SETTYPE_ABBREV);
2347       Record.clear();
2348     }
2349 
2350     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2351       Record.push_back(unsigned(IA->hasSideEffects()) |
2352                        unsigned(IA->isAlignStack()) << 1 |
2353                        unsigned(IA->getDialect()&1) << 2);
2354 
2355       // Add the asm string.
2356       const std::string &AsmStr = IA->getAsmString();
2357       Record.push_back(AsmStr.size());
2358       Record.append(AsmStr.begin(), AsmStr.end());
2359 
2360       // Add the constraint string.
2361       const std::string &ConstraintStr = IA->getConstraintString();
2362       Record.push_back(ConstraintStr.size());
2363       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2364       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2365       Record.clear();
2366       continue;
2367     }
2368     const Constant *C = cast<Constant>(V);
2369     unsigned Code = -1U;
2370     unsigned AbbrevToUse = 0;
2371     if (C->isNullValue()) {
2372       Code = bitc::CST_CODE_NULL;
2373     } else if (isa<UndefValue>(C)) {
2374       Code = bitc::CST_CODE_UNDEF;
2375     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2376       if (IV->getBitWidth() <= 64) {
2377         uint64_t V = IV->getSExtValue();
2378         emitSignedInt64(Record, V);
2379         Code = bitc::CST_CODE_INTEGER;
2380         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2381       } else {                             // Wide integers, > 64 bits in size.
2382         emitWideAPInt(Record, IV->getValue());
2383         Code = bitc::CST_CODE_WIDE_INTEGER;
2384       }
2385     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2386       Code = bitc::CST_CODE_FLOAT;
2387       Type *Ty = CFP->getType();
2388       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2389         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2390       } else if (Ty->isX86_FP80Ty()) {
2391         // api needed to prevent premature destruction
2392         // bits are not in the same order as a normal i80 APInt, compensate.
2393         APInt api = CFP->getValueAPF().bitcastToAPInt();
2394         const uint64_t *p = api.getRawData();
2395         Record.push_back((p[1] << 48) | (p[0] >> 16));
2396         Record.push_back(p[0] & 0xffffLL);
2397       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2398         APInt api = CFP->getValueAPF().bitcastToAPInt();
2399         const uint64_t *p = api.getRawData();
2400         Record.push_back(p[0]);
2401         Record.push_back(p[1]);
2402       } else {
2403         assert(0 && "Unknown FP type!");
2404       }
2405     } else if (isa<ConstantDataSequential>(C) &&
2406                cast<ConstantDataSequential>(C)->isString()) {
2407       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2408       // Emit constant strings specially.
2409       unsigned NumElts = Str->getNumElements();
2410       // If this is a null-terminated string, use the denser CSTRING encoding.
2411       if (Str->isCString()) {
2412         Code = bitc::CST_CODE_CSTRING;
2413         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2414       } else {
2415         Code = bitc::CST_CODE_STRING;
2416         AbbrevToUse = String8Abbrev;
2417       }
2418       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2419       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2420       for (unsigned i = 0; i != NumElts; ++i) {
2421         unsigned char V = Str->getElementAsInteger(i);
2422         Record.push_back(V);
2423         isCStr7 &= (V & 128) == 0;
2424         if (isCStrChar6)
2425           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2426       }
2427 
2428       if (isCStrChar6)
2429         AbbrevToUse = CString6Abbrev;
2430       else if (isCStr7)
2431         AbbrevToUse = CString7Abbrev;
2432     } else if (const ConstantDataSequential *CDS =
2433                   dyn_cast<ConstantDataSequential>(C)) {
2434       Code = bitc::CST_CODE_DATA;
2435       Type *EltTy = CDS->getElementType();
2436       if (isa<IntegerType>(EltTy)) {
2437         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2438           Record.push_back(CDS->getElementAsInteger(i));
2439       } else {
2440         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2441           Record.push_back(
2442               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2443       }
2444     } else if (isa<ConstantAggregate>(C)) {
2445       Code = bitc::CST_CODE_AGGREGATE;
2446       for (const Value *Op : C->operands())
2447         Record.push_back(VE.getValueID(Op));
2448       AbbrevToUse = AggregateAbbrev;
2449     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2450       switch (CE->getOpcode()) {
2451       default:
2452         if (Instruction::isCast(CE->getOpcode())) {
2453           Code = bitc::CST_CODE_CE_CAST;
2454           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2455           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2456           Record.push_back(VE.getValueID(C->getOperand(0)));
2457           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2458         } else {
2459           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2460           Code = bitc::CST_CODE_CE_BINOP;
2461           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2462           Record.push_back(VE.getValueID(C->getOperand(0)));
2463           Record.push_back(VE.getValueID(C->getOperand(1)));
2464           uint64_t Flags = getOptimizationFlags(CE);
2465           if (Flags != 0)
2466             Record.push_back(Flags);
2467         }
2468         break;
2469       case Instruction::FNeg: {
2470         assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
2471         Code = bitc::CST_CODE_CE_UNOP;
2472         Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
2473         Record.push_back(VE.getValueID(C->getOperand(0)));
2474         uint64_t Flags = getOptimizationFlags(CE);
2475         if (Flags != 0)
2476           Record.push_back(Flags);
2477         break;
2478       }
2479       case Instruction::GetElementPtr: {
2480         Code = bitc::CST_CODE_CE_GEP;
2481         const auto *GO = cast<GEPOperator>(C);
2482         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2483         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2484           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2485           Record.push_back((*Idx << 1) | GO->isInBounds());
2486         } else if (GO->isInBounds())
2487           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2488         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2489           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2490           Record.push_back(VE.getValueID(C->getOperand(i)));
2491         }
2492         break;
2493       }
2494       case Instruction::Select:
2495         Code = bitc::CST_CODE_CE_SELECT;
2496         Record.push_back(VE.getValueID(C->getOperand(0)));
2497         Record.push_back(VE.getValueID(C->getOperand(1)));
2498         Record.push_back(VE.getValueID(C->getOperand(2)));
2499         break;
2500       case Instruction::ExtractElement:
2501         Code = bitc::CST_CODE_CE_EXTRACTELT;
2502         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2503         Record.push_back(VE.getValueID(C->getOperand(0)));
2504         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2505         Record.push_back(VE.getValueID(C->getOperand(1)));
2506         break;
2507       case Instruction::InsertElement:
2508         Code = bitc::CST_CODE_CE_INSERTELT;
2509         Record.push_back(VE.getValueID(C->getOperand(0)));
2510         Record.push_back(VE.getValueID(C->getOperand(1)));
2511         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2512         Record.push_back(VE.getValueID(C->getOperand(2)));
2513         break;
2514       case Instruction::ShuffleVector:
2515         // If the return type and argument types are the same, this is a
2516         // standard shufflevector instruction.  If the types are different,
2517         // then the shuffle is widening or truncating the input vectors, and
2518         // the argument type must also be encoded.
2519         if (C->getType() == C->getOperand(0)->getType()) {
2520           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2521         } else {
2522           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2523           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2524         }
2525         Record.push_back(VE.getValueID(C->getOperand(0)));
2526         Record.push_back(VE.getValueID(C->getOperand(1)));
2527         Record.push_back(VE.getValueID(CE->getShuffleMaskForBitcode()));
2528         break;
2529       case Instruction::ICmp:
2530       case Instruction::FCmp:
2531         Code = bitc::CST_CODE_CE_CMP;
2532         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2533         Record.push_back(VE.getValueID(C->getOperand(0)));
2534         Record.push_back(VE.getValueID(C->getOperand(1)));
2535         Record.push_back(CE->getPredicate());
2536         break;
2537       }
2538     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2539       Code = bitc::CST_CODE_BLOCKADDRESS;
2540       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2541       Record.push_back(VE.getValueID(BA->getFunction()));
2542       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2543     } else {
2544 #ifndef NDEBUG
2545       C->dump();
2546 #endif
2547       llvm_unreachable("Unknown constant!");
2548     }
2549     Stream.EmitRecord(Code, Record, AbbrevToUse);
2550     Record.clear();
2551   }
2552 
2553   Stream.ExitBlock();
2554 }
2555 
2556 void ModuleBitcodeWriter::writeModuleConstants() {
2557   const ValueEnumerator::ValueList &Vals = VE.getValues();
2558 
2559   // Find the first constant to emit, which is the first non-globalvalue value.
2560   // We know globalvalues have been emitted by WriteModuleInfo.
2561   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2562     if (!isa<GlobalValue>(Vals[i].first)) {
2563       writeConstants(i, Vals.size(), true);
2564       return;
2565     }
2566   }
2567 }
2568 
2569 /// pushValueAndType - The file has to encode both the value and type id for
2570 /// many values, because we need to know what type to create for forward
2571 /// references.  However, most operands are not forward references, so this type
2572 /// field is not needed.
2573 ///
2574 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2575 /// instruction ID, then it is a forward reference, and it also includes the
2576 /// type ID.  The value ID that is written is encoded relative to the InstID.
2577 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2578                                            SmallVectorImpl<unsigned> &Vals) {
2579   unsigned ValID = VE.getValueID(V);
2580   // Make encoding relative to the InstID.
2581   Vals.push_back(InstID - ValID);
2582   if (ValID >= InstID) {
2583     Vals.push_back(VE.getTypeID(V->getType()));
2584     return true;
2585   }
2586   return false;
2587 }
2588 
2589 void ModuleBitcodeWriter::writeOperandBundles(const CallBase &CS,
2590                                               unsigned InstID) {
2591   SmallVector<unsigned, 64> Record;
2592   LLVMContext &C = CS.getContext();
2593 
2594   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2595     const auto &Bundle = CS.getOperandBundleAt(i);
2596     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2597 
2598     for (auto &Input : Bundle.Inputs)
2599       pushValueAndType(Input, InstID, Record);
2600 
2601     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2602     Record.clear();
2603   }
2604 }
2605 
2606 /// pushValue - Like pushValueAndType, but where the type of the value is
2607 /// omitted (perhaps it was already encoded in an earlier operand).
2608 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2609                                     SmallVectorImpl<unsigned> &Vals) {
2610   unsigned ValID = VE.getValueID(V);
2611   Vals.push_back(InstID - ValID);
2612 }
2613 
2614 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2615                                           SmallVectorImpl<uint64_t> &Vals) {
2616   unsigned ValID = VE.getValueID(V);
2617   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2618   emitSignedInt64(Vals, diff);
2619 }
2620 
2621 /// WriteInstruction - Emit an instruction to the specified stream.
2622 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2623                                            unsigned InstID,
2624                                            SmallVectorImpl<unsigned> &Vals) {
2625   unsigned Code = 0;
2626   unsigned AbbrevToUse = 0;
2627   VE.setInstructionID(&I);
2628   switch (I.getOpcode()) {
2629   default:
2630     if (Instruction::isCast(I.getOpcode())) {
2631       Code = bitc::FUNC_CODE_INST_CAST;
2632       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2633         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2634       Vals.push_back(VE.getTypeID(I.getType()));
2635       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2636     } else {
2637       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2638       Code = bitc::FUNC_CODE_INST_BINOP;
2639       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2640         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2641       pushValue(I.getOperand(1), InstID, Vals);
2642       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2643       uint64_t Flags = getOptimizationFlags(&I);
2644       if (Flags != 0) {
2645         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2646           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2647         Vals.push_back(Flags);
2648       }
2649     }
2650     break;
2651   case Instruction::FNeg: {
2652     Code = bitc::FUNC_CODE_INST_UNOP;
2653     if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2654       AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
2655     Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
2656     uint64_t Flags = getOptimizationFlags(&I);
2657     if (Flags != 0) {
2658       if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
2659         AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
2660       Vals.push_back(Flags);
2661     }
2662     break;
2663   }
2664   case Instruction::GetElementPtr: {
2665     Code = bitc::FUNC_CODE_INST_GEP;
2666     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2667     auto &GEPInst = cast<GetElementPtrInst>(I);
2668     Vals.push_back(GEPInst.isInBounds());
2669     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2670     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2671       pushValueAndType(I.getOperand(i), InstID, Vals);
2672     break;
2673   }
2674   case Instruction::ExtractValue: {
2675     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2676     pushValueAndType(I.getOperand(0), InstID, Vals);
2677     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2678     Vals.append(EVI->idx_begin(), EVI->idx_end());
2679     break;
2680   }
2681   case Instruction::InsertValue: {
2682     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2683     pushValueAndType(I.getOperand(0), InstID, Vals);
2684     pushValueAndType(I.getOperand(1), InstID, Vals);
2685     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2686     Vals.append(IVI->idx_begin(), IVI->idx_end());
2687     break;
2688   }
2689   case Instruction::Select: {
2690     Code = bitc::FUNC_CODE_INST_VSELECT;
2691     pushValueAndType(I.getOperand(1), InstID, Vals);
2692     pushValue(I.getOperand(2), InstID, Vals);
2693     pushValueAndType(I.getOperand(0), InstID, Vals);
2694     uint64_t Flags = getOptimizationFlags(&I);
2695     if (Flags != 0)
2696       Vals.push_back(Flags);
2697     break;
2698   }
2699   case Instruction::ExtractElement:
2700     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2701     pushValueAndType(I.getOperand(0), InstID, Vals);
2702     pushValueAndType(I.getOperand(1), InstID, Vals);
2703     break;
2704   case Instruction::InsertElement:
2705     Code = bitc::FUNC_CODE_INST_INSERTELT;
2706     pushValueAndType(I.getOperand(0), InstID, Vals);
2707     pushValue(I.getOperand(1), InstID, Vals);
2708     pushValueAndType(I.getOperand(2), InstID, Vals);
2709     break;
2710   case Instruction::ShuffleVector:
2711     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2712     pushValueAndType(I.getOperand(0), InstID, Vals);
2713     pushValue(I.getOperand(1), InstID, Vals);
2714     pushValue(cast<ShuffleVectorInst>(I).getShuffleMaskForBitcode(), InstID,
2715               Vals);
2716     break;
2717   case Instruction::ICmp:
2718   case Instruction::FCmp: {
2719     // compare returning Int1Ty or vector of Int1Ty
2720     Code = bitc::FUNC_CODE_INST_CMP2;
2721     pushValueAndType(I.getOperand(0), InstID, Vals);
2722     pushValue(I.getOperand(1), InstID, Vals);
2723     Vals.push_back(cast<CmpInst>(I).getPredicate());
2724     uint64_t Flags = getOptimizationFlags(&I);
2725     if (Flags != 0)
2726       Vals.push_back(Flags);
2727     break;
2728   }
2729 
2730   case Instruction::Ret:
2731     {
2732       Code = bitc::FUNC_CODE_INST_RET;
2733       unsigned NumOperands = I.getNumOperands();
2734       if (NumOperands == 0)
2735         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2736       else if (NumOperands == 1) {
2737         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2738           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2739       } else {
2740         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2741           pushValueAndType(I.getOperand(i), InstID, Vals);
2742       }
2743     }
2744     break;
2745   case Instruction::Br:
2746     {
2747       Code = bitc::FUNC_CODE_INST_BR;
2748       const BranchInst &II = cast<BranchInst>(I);
2749       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2750       if (II.isConditional()) {
2751         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2752         pushValue(II.getCondition(), InstID, Vals);
2753       }
2754     }
2755     break;
2756   case Instruction::Switch:
2757     {
2758       Code = bitc::FUNC_CODE_INST_SWITCH;
2759       const SwitchInst &SI = cast<SwitchInst>(I);
2760       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2761       pushValue(SI.getCondition(), InstID, Vals);
2762       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2763       for (auto Case : SI.cases()) {
2764         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2765         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2766       }
2767     }
2768     break;
2769   case Instruction::IndirectBr:
2770     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2771     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2772     // Encode the address operand as relative, but not the basic blocks.
2773     pushValue(I.getOperand(0), InstID, Vals);
2774     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2775       Vals.push_back(VE.getValueID(I.getOperand(i)));
2776     break;
2777 
2778   case Instruction::Invoke: {
2779     const InvokeInst *II = cast<InvokeInst>(&I);
2780     const Value *Callee = II->getCalledOperand();
2781     FunctionType *FTy = II->getFunctionType();
2782 
2783     if (II->hasOperandBundles())
2784       writeOperandBundles(*II, InstID);
2785 
2786     Code = bitc::FUNC_CODE_INST_INVOKE;
2787 
2788     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2789     Vals.push_back(II->getCallingConv() | 1 << 13);
2790     Vals.push_back(VE.getValueID(II->getNormalDest()));
2791     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2792     Vals.push_back(VE.getTypeID(FTy));
2793     pushValueAndType(Callee, InstID, Vals);
2794 
2795     // Emit value #'s for the fixed parameters.
2796     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2797       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2798 
2799     // Emit type/value pairs for varargs params.
2800     if (FTy->isVarArg()) {
2801       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2802            i != e; ++i)
2803         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2804     }
2805     break;
2806   }
2807   case Instruction::Resume:
2808     Code = bitc::FUNC_CODE_INST_RESUME;
2809     pushValueAndType(I.getOperand(0), InstID, Vals);
2810     break;
2811   case Instruction::CleanupRet: {
2812     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2813     const auto &CRI = cast<CleanupReturnInst>(I);
2814     pushValue(CRI.getCleanupPad(), InstID, Vals);
2815     if (CRI.hasUnwindDest())
2816       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2817     break;
2818   }
2819   case Instruction::CatchRet: {
2820     Code = bitc::FUNC_CODE_INST_CATCHRET;
2821     const auto &CRI = cast<CatchReturnInst>(I);
2822     pushValue(CRI.getCatchPad(), InstID, Vals);
2823     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2824     break;
2825   }
2826   case Instruction::CleanupPad:
2827   case Instruction::CatchPad: {
2828     const auto &FuncletPad = cast<FuncletPadInst>(I);
2829     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2830                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2831     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2832 
2833     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2834     Vals.push_back(NumArgOperands);
2835     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2836       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2837     break;
2838   }
2839   case Instruction::CatchSwitch: {
2840     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2841     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2842 
2843     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2844 
2845     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2846     Vals.push_back(NumHandlers);
2847     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2848       Vals.push_back(VE.getValueID(CatchPadBB));
2849 
2850     if (CatchSwitch.hasUnwindDest())
2851       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2852     break;
2853   }
2854   case Instruction::CallBr: {
2855     const CallBrInst *CBI = cast<CallBrInst>(&I);
2856     const Value *Callee = CBI->getCalledOperand();
2857     FunctionType *FTy = CBI->getFunctionType();
2858 
2859     if (CBI->hasOperandBundles())
2860       writeOperandBundles(*CBI, InstID);
2861 
2862     Code = bitc::FUNC_CODE_INST_CALLBR;
2863 
2864     Vals.push_back(VE.getAttributeListID(CBI->getAttributes()));
2865 
2866     Vals.push_back(CBI->getCallingConv() << bitc::CALL_CCONV |
2867                    1 << bitc::CALL_EXPLICIT_TYPE);
2868 
2869     Vals.push_back(VE.getValueID(CBI->getDefaultDest()));
2870     Vals.push_back(CBI->getNumIndirectDests());
2871     for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
2872       Vals.push_back(VE.getValueID(CBI->getIndirectDest(i)));
2873 
2874     Vals.push_back(VE.getTypeID(FTy));
2875     pushValueAndType(Callee, InstID, Vals);
2876 
2877     // Emit value #'s for the fixed parameters.
2878     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2879       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2880 
2881     // Emit type/value pairs for varargs params.
2882     if (FTy->isVarArg()) {
2883       for (unsigned i = FTy->getNumParams(), e = CBI->getNumArgOperands();
2884            i != e; ++i)
2885         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2886     }
2887     break;
2888   }
2889   case Instruction::Unreachable:
2890     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2891     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2892     break;
2893 
2894   case Instruction::PHI: {
2895     const PHINode &PN = cast<PHINode>(I);
2896     Code = bitc::FUNC_CODE_INST_PHI;
2897     // With the newer instruction encoding, forward references could give
2898     // negative valued IDs.  This is most common for PHIs, so we use
2899     // signed VBRs.
2900     SmallVector<uint64_t, 128> Vals64;
2901     Vals64.push_back(VE.getTypeID(PN.getType()));
2902     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2903       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2904       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2905     }
2906 
2907     uint64_t Flags = getOptimizationFlags(&I);
2908     if (Flags != 0)
2909       Vals64.push_back(Flags);
2910 
2911     // Emit a Vals64 vector and exit.
2912     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2913     Vals64.clear();
2914     return;
2915   }
2916 
2917   case Instruction::LandingPad: {
2918     const LandingPadInst &LP = cast<LandingPadInst>(I);
2919     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2920     Vals.push_back(VE.getTypeID(LP.getType()));
2921     Vals.push_back(LP.isCleanup());
2922     Vals.push_back(LP.getNumClauses());
2923     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2924       if (LP.isCatch(I))
2925         Vals.push_back(LandingPadInst::Catch);
2926       else
2927         Vals.push_back(LandingPadInst::Filter);
2928       pushValueAndType(LP.getClause(I), InstID, Vals);
2929     }
2930     break;
2931   }
2932 
2933   case Instruction::Alloca: {
2934     Code = bitc::FUNC_CODE_INST_ALLOCA;
2935     const AllocaInst &AI = cast<AllocaInst>(I);
2936     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2937     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2938     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2939     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2940     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2941            "not enough bits for maximum alignment");
2942     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2943     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2944     AlignRecord |= 1 << 6;
2945     AlignRecord |= AI.isSwiftError() << 7;
2946     Vals.push_back(AlignRecord);
2947     break;
2948   }
2949 
2950   case Instruction::Load:
2951     if (cast<LoadInst>(I).isAtomic()) {
2952       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2953       pushValueAndType(I.getOperand(0), InstID, Vals);
2954     } else {
2955       Code = bitc::FUNC_CODE_INST_LOAD;
2956       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2957         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2958     }
2959     Vals.push_back(VE.getTypeID(I.getType()));
2960     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2961     Vals.push_back(cast<LoadInst>(I).isVolatile());
2962     if (cast<LoadInst>(I).isAtomic()) {
2963       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2964       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2965     }
2966     break;
2967   case Instruction::Store:
2968     if (cast<StoreInst>(I).isAtomic())
2969       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2970     else
2971       Code = bitc::FUNC_CODE_INST_STORE;
2972     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2973     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2974     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2975     Vals.push_back(cast<StoreInst>(I).isVolatile());
2976     if (cast<StoreInst>(I).isAtomic()) {
2977       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2978       Vals.push_back(
2979           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2980     }
2981     break;
2982   case Instruction::AtomicCmpXchg:
2983     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2984     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2985     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2986     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2987     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2988     Vals.push_back(
2989         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2990     Vals.push_back(
2991         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2992     Vals.push_back(
2993         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2994     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2995     break;
2996   case Instruction::AtomicRMW:
2997     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2998     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2999     pushValue(I.getOperand(1), InstID, Vals);        // val.
3000     Vals.push_back(
3001         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
3002     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
3003     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
3004     Vals.push_back(
3005         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
3006     break;
3007   case Instruction::Fence:
3008     Code = bitc::FUNC_CODE_INST_FENCE;
3009     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
3010     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
3011     break;
3012   case Instruction::Call: {
3013     const CallInst &CI = cast<CallInst>(I);
3014     FunctionType *FTy = CI.getFunctionType();
3015 
3016     if (CI.hasOperandBundles())
3017       writeOperandBundles(CI, InstID);
3018 
3019     Code = bitc::FUNC_CODE_INST_CALL;
3020 
3021     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
3022 
3023     unsigned Flags = getOptimizationFlags(&I);
3024     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
3025                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
3026                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
3027                    1 << bitc::CALL_EXPLICIT_TYPE |
3028                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
3029                    unsigned(Flags != 0) << bitc::CALL_FMF);
3030     if (Flags != 0)
3031       Vals.push_back(Flags);
3032 
3033     Vals.push_back(VE.getTypeID(FTy));
3034     pushValueAndType(CI.getCalledOperand(), InstID, Vals); // Callee
3035 
3036     // Emit value #'s for the fixed parameters.
3037     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
3038       // Check for labels (can happen with asm labels).
3039       if (FTy->getParamType(i)->isLabelTy())
3040         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
3041       else
3042         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
3043     }
3044 
3045     // Emit type/value pairs for varargs params.
3046     if (FTy->isVarArg()) {
3047       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
3048            i != e; ++i)
3049         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
3050     }
3051     break;
3052   }
3053   case Instruction::VAArg:
3054     Code = bitc::FUNC_CODE_INST_VAARG;
3055     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
3056     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
3057     Vals.push_back(VE.getTypeID(I.getType())); // restype.
3058     break;
3059   case Instruction::Freeze:
3060     Code = bitc::FUNC_CODE_INST_FREEZE;
3061     pushValueAndType(I.getOperand(0), InstID, Vals);
3062     break;
3063   }
3064 
3065   Stream.EmitRecord(Code, Vals, AbbrevToUse);
3066   Vals.clear();
3067 }
3068 
3069 /// Write a GlobalValue VST to the module. The purpose of this data structure is
3070 /// to allow clients to efficiently find the function body.
3071 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
3072   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3073   // Get the offset of the VST we are writing, and backpatch it into
3074   // the VST forward declaration record.
3075   uint64_t VSTOffset = Stream.GetCurrentBitNo();
3076   // The BitcodeStartBit was the stream offset of the identification block.
3077   VSTOffset -= bitcodeStartBit();
3078   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
3079   // Note that we add 1 here because the offset is relative to one word
3080   // before the start of the identification block, which was historically
3081   // always the start of the regular bitcode header.
3082   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
3083 
3084   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3085 
3086   auto Abbv = std::make_shared<BitCodeAbbrev>();
3087   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
3088   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
3089   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
3090   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3091 
3092   for (const Function &F : M) {
3093     uint64_t Record[2];
3094 
3095     if (F.isDeclaration())
3096       continue;
3097 
3098     Record[0] = VE.getValueID(&F);
3099 
3100     // Save the word offset of the function (from the start of the
3101     // actual bitcode written to the stream).
3102     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
3103     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
3104     // Note that we add 1 here because the offset is relative to one word
3105     // before the start of the identification block, which was historically
3106     // always the start of the regular bitcode header.
3107     Record[1] = BitcodeIndex / 32 + 1;
3108 
3109     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
3110   }
3111 
3112   Stream.ExitBlock();
3113 }
3114 
3115 /// Emit names for arguments, instructions and basic blocks in a function.
3116 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
3117     const ValueSymbolTable &VST) {
3118   if (VST.empty())
3119     return;
3120 
3121   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
3122 
3123   // FIXME: Set up the abbrev, we know how many values there are!
3124   // FIXME: We know if the type names can use 7-bit ascii.
3125   SmallVector<uint64_t, 64> NameVals;
3126 
3127   for (const ValueName &Name : VST) {
3128     // Figure out the encoding to use for the name.
3129     StringEncoding Bits = getStringEncoding(Name.getKey());
3130 
3131     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
3132     NameVals.push_back(VE.getValueID(Name.getValue()));
3133 
3134     // VST_CODE_ENTRY:   [valueid, namechar x N]
3135     // VST_CODE_BBENTRY: [bbid, namechar x N]
3136     unsigned Code;
3137     if (isa<BasicBlock>(Name.getValue())) {
3138       Code = bitc::VST_CODE_BBENTRY;
3139       if (Bits == SE_Char6)
3140         AbbrevToUse = VST_BBENTRY_6_ABBREV;
3141     } else {
3142       Code = bitc::VST_CODE_ENTRY;
3143       if (Bits == SE_Char6)
3144         AbbrevToUse = VST_ENTRY_6_ABBREV;
3145       else if (Bits == SE_Fixed7)
3146         AbbrevToUse = VST_ENTRY_7_ABBREV;
3147     }
3148 
3149     for (const auto P : Name.getKey())
3150       NameVals.push_back((unsigned char)P);
3151 
3152     // Emit the finished record.
3153     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
3154     NameVals.clear();
3155   }
3156 
3157   Stream.ExitBlock();
3158 }
3159 
3160 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3161   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3162   unsigned Code;
3163   if (isa<BasicBlock>(Order.V))
3164     Code = bitc::USELIST_CODE_BB;
3165   else
3166     Code = bitc::USELIST_CODE_DEFAULT;
3167 
3168   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3169   Record.push_back(VE.getValueID(Order.V));
3170   Stream.EmitRecord(Code, Record);
3171 }
3172 
3173 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3174   assert(VE.shouldPreserveUseListOrder() &&
3175          "Expected to be preserving use-list order");
3176 
3177   auto hasMore = [&]() {
3178     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3179   };
3180   if (!hasMore())
3181     // Nothing to do.
3182     return;
3183 
3184   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3185   while (hasMore()) {
3186     writeUseList(std::move(VE.UseListOrders.back()));
3187     VE.UseListOrders.pop_back();
3188   }
3189   Stream.ExitBlock();
3190 }
3191 
3192 /// Emit a function body to the module stream.
3193 void ModuleBitcodeWriter::writeFunction(
3194     const Function &F,
3195     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3196   // Save the bitcode index of the start of this function block for recording
3197   // in the VST.
3198   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3199 
3200   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3201   VE.incorporateFunction(F);
3202 
3203   SmallVector<unsigned, 64> Vals;
3204 
3205   // Emit the number of basic blocks, so the reader can create them ahead of
3206   // time.
3207   Vals.push_back(VE.getBasicBlocks().size());
3208   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3209   Vals.clear();
3210 
3211   // If there are function-local constants, emit them now.
3212   unsigned CstStart, CstEnd;
3213   VE.getFunctionConstantRange(CstStart, CstEnd);
3214   writeConstants(CstStart, CstEnd, false);
3215 
3216   // If there is function-local metadata, emit it now.
3217   writeFunctionMetadata(F);
3218 
3219   // Keep a running idea of what the instruction ID is.
3220   unsigned InstID = CstEnd;
3221 
3222   bool NeedsMetadataAttachment = F.hasMetadata();
3223 
3224   DILocation *LastDL = nullptr;
3225   // Finally, emit all the instructions, in order.
3226   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3227     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3228          I != E; ++I) {
3229       writeInstruction(*I, InstID, Vals);
3230 
3231       if (!I->getType()->isVoidTy())
3232         ++InstID;
3233 
3234       // If the instruction has metadata, write a metadata attachment later.
3235       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3236 
3237       // If the instruction has a debug location, emit it.
3238       DILocation *DL = I->getDebugLoc();
3239       if (!DL)
3240         continue;
3241 
3242       if (DL == LastDL) {
3243         // Just repeat the same debug loc as last time.
3244         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3245         continue;
3246       }
3247 
3248       Vals.push_back(DL->getLine());
3249       Vals.push_back(DL->getColumn());
3250       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3251       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3252       Vals.push_back(DL->isImplicitCode());
3253       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3254       Vals.clear();
3255 
3256       LastDL = DL;
3257     }
3258 
3259   // Emit names for all the instructions etc.
3260   if (auto *Symtab = F.getValueSymbolTable())
3261     writeFunctionLevelValueSymbolTable(*Symtab);
3262 
3263   if (NeedsMetadataAttachment)
3264     writeFunctionMetadataAttachment(F);
3265   if (VE.shouldPreserveUseListOrder())
3266     writeUseListBlock(&F);
3267   VE.purgeFunction();
3268   Stream.ExitBlock();
3269 }
3270 
3271 // Emit blockinfo, which defines the standard abbreviations etc.
3272 void ModuleBitcodeWriter::writeBlockInfo() {
3273   // We only want to emit block info records for blocks that have multiple
3274   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3275   // Other blocks can define their abbrevs inline.
3276   Stream.EnterBlockInfoBlock();
3277 
3278   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3279     auto Abbv = std::make_shared<BitCodeAbbrev>();
3280     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3281     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3282     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3283     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3284     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3285         VST_ENTRY_8_ABBREV)
3286       llvm_unreachable("Unexpected abbrev ordering!");
3287   }
3288 
3289   { // 7-bit fixed width VST_CODE_ENTRY strings.
3290     auto Abbv = std::make_shared<BitCodeAbbrev>();
3291     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3292     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3293     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3294     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3295     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3296         VST_ENTRY_7_ABBREV)
3297       llvm_unreachable("Unexpected abbrev ordering!");
3298   }
3299   { // 6-bit char6 VST_CODE_ENTRY strings.
3300     auto Abbv = std::make_shared<BitCodeAbbrev>();
3301     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3302     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3303     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3304     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3305     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3306         VST_ENTRY_6_ABBREV)
3307       llvm_unreachable("Unexpected abbrev ordering!");
3308   }
3309   { // 6-bit char6 VST_CODE_BBENTRY strings.
3310     auto Abbv = std::make_shared<BitCodeAbbrev>();
3311     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3313     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3314     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3315     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3316         VST_BBENTRY_6_ABBREV)
3317       llvm_unreachable("Unexpected abbrev ordering!");
3318   }
3319 
3320   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3321     auto Abbv = std::make_shared<BitCodeAbbrev>();
3322     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3323     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3324                               VE.computeBitsRequiredForTypeIndicies()));
3325     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3326         CONSTANTS_SETTYPE_ABBREV)
3327       llvm_unreachable("Unexpected abbrev ordering!");
3328   }
3329 
3330   { // INTEGER abbrev for CONSTANTS_BLOCK.
3331     auto Abbv = std::make_shared<BitCodeAbbrev>();
3332     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3333     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3334     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3335         CONSTANTS_INTEGER_ABBREV)
3336       llvm_unreachable("Unexpected abbrev ordering!");
3337   }
3338 
3339   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3340     auto Abbv = std::make_shared<BitCodeAbbrev>();
3341     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3342     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3343     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3344                               VE.computeBitsRequiredForTypeIndicies()));
3345     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3346 
3347     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3348         CONSTANTS_CE_CAST_Abbrev)
3349       llvm_unreachable("Unexpected abbrev ordering!");
3350   }
3351   { // NULL abbrev for CONSTANTS_BLOCK.
3352     auto Abbv = std::make_shared<BitCodeAbbrev>();
3353     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3354     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3355         CONSTANTS_NULL_Abbrev)
3356       llvm_unreachable("Unexpected abbrev ordering!");
3357   }
3358 
3359   // FIXME: This should only use space for first class types!
3360 
3361   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3362     auto Abbv = std::make_shared<BitCodeAbbrev>();
3363     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3364     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3365     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3366                               VE.computeBitsRequiredForTypeIndicies()));
3367     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3368     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3369     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3370         FUNCTION_INST_LOAD_ABBREV)
3371       llvm_unreachable("Unexpected abbrev ordering!");
3372   }
3373   { // INST_UNOP abbrev for FUNCTION_BLOCK.
3374     auto Abbv = std::make_shared<BitCodeAbbrev>();
3375     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3376     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3377     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3378     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3379         FUNCTION_INST_UNOP_ABBREV)
3380       llvm_unreachable("Unexpected abbrev ordering!");
3381   }
3382   { // INST_UNOP_FLAGS abbrev for FUNCTION_BLOCK.
3383     auto Abbv = std::make_shared<BitCodeAbbrev>();
3384     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNOP));
3385     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3386     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3387     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3388     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3389         FUNCTION_INST_UNOP_FLAGS_ABBREV)
3390       llvm_unreachable("Unexpected abbrev ordering!");
3391   }
3392   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3393     auto Abbv = std::make_shared<BitCodeAbbrev>();
3394     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3395     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3396     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3397     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3398     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3399         FUNCTION_INST_BINOP_ABBREV)
3400       llvm_unreachable("Unexpected abbrev ordering!");
3401   }
3402   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3403     auto Abbv = std::make_shared<BitCodeAbbrev>();
3404     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3405     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3406     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3407     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3408     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3409     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3410         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3411       llvm_unreachable("Unexpected abbrev ordering!");
3412   }
3413   { // INST_CAST abbrev for FUNCTION_BLOCK.
3414     auto Abbv = std::make_shared<BitCodeAbbrev>();
3415     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3416     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3417     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3418                               VE.computeBitsRequiredForTypeIndicies()));
3419     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3420     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3421         FUNCTION_INST_CAST_ABBREV)
3422       llvm_unreachable("Unexpected abbrev ordering!");
3423   }
3424 
3425   { // INST_RET abbrev for FUNCTION_BLOCK.
3426     auto Abbv = std::make_shared<BitCodeAbbrev>();
3427     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3428     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3429         FUNCTION_INST_RET_VOID_ABBREV)
3430       llvm_unreachable("Unexpected abbrev ordering!");
3431   }
3432   { // INST_RET abbrev for FUNCTION_BLOCK.
3433     auto Abbv = std::make_shared<BitCodeAbbrev>();
3434     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3435     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3436     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3437         FUNCTION_INST_RET_VAL_ABBREV)
3438       llvm_unreachable("Unexpected abbrev ordering!");
3439   }
3440   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3441     auto Abbv = std::make_shared<BitCodeAbbrev>();
3442     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3443     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3444         FUNCTION_INST_UNREACHABLE_ABBREV)
3445       llvm_unreachable("Unexpected abbrev ordering!");
3446   }
3447   {
3448     auto Abbv = std::make_shared<BitCodeAbbrev>();
3449     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3450     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3451     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3452                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3453     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3454     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3455     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3456         FUNCTION_INST_GEP_ABBREV)
3457       llvm_unreachable("Unexpected abbrev ordering!");
3458   }
3459 
3460   Stream.ExitBlock();
3461 }
3462 
3463 /// Write the module path strings, currently only used when generating
3464 /// a combined index file.
3465 void IndexBitcodeWriter::writeModStrings() {
3466   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3467 
3468   // TODO: See which abbrev sizes we actually need to emit
3469 
3470   // 8-bit fixed-width MST_ENTRY strings.
3471   auto Abbv = std::make_shared<BitCodeAbbrev>();
3472   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3473   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3474   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3475   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3476   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3477 
3478   // 7-bit fixed width MST_ENTRY strings.
3479   Abbv = std::make_shared<BitCodeAbbrev>();
3480   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3481   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3482   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3483   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3484   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3485 
3486   // 6-bit char6 MST_ENTRY strings.
3487   Abbv = std::make_shared<BitCodeAbbrev>();
3488   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3489   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3490   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3491   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3492   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3493 
3494   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3495   Abbv = std::make_shared<BitCodeAbbrev>();
3496   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3497   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3498   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3499   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3500   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3501   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3502   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3503 
3504   SmallVector<unsigned, 64> Vals;
3505   forEachModule(
3506       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3507         StringRef Key = MPSE.getKey();
3508         const auto &Value = MPSE.getValue();
3509         StringEncoding Bits = getStringEncoding(Key);
3510         unsigned AbbrevToUse = Abbrev8Bit;
3511         if (Bits == SE_Char6)
3512           AbbrevToUse = Abbrev6Bit;
3513         else if (Bits == SE_Fixed7)
3514           AbbrevToUse = Abbrev7Bit;
3515 
3516         Vals.push_back(Value.first);
3517         Vals.append(Key.begin(), Key.end());
3518 
3519         // Emit the finished record.
3520         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3521 
3522         // Emit an optional hash for the module now
3523         const auto &Hash = Value.second;
3524         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3525           Vals.assign(Hash.begin(), Hash.end());
3526           // Emit the hash record.
3527           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3528         }
3529 
3530         Vals.clear();
3531       });
3532   Stream.ExitBlock();
3533 }
3534 
3535 /// Write the function type metadata related records that need to appear before
3536 /// a function summary entry (whether per-module or combined).
3537 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3538                                              FunctionSummary *FS) {
3539   if (!FS->type_tests().empty())
3540     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3541 
3542   SmallVector<uint64_t, 64> Record;
3543 
3544   auto WriteVFuncIdVec = [&](uint64_t Ty,
3545                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3546     if (VFs.empty())
3547       return;
3548     Record.clear();
3549     for (auto &VF : VFs) {
3550       Record.push_back(VF.GUID);
3551       Record.push_back(VF.Offset);
3552     }
3553     Stream.EmitRecord(Ty, Record);
3554   };
3555 
3556   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3557                   FS->type_test_assume_vcalls());
3558   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3559                   FS->type_checked_load_vcalls());
3560 
3561   auto WriteConstVCallVec = [&](uint64_t Ty,
3562                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3563     for (auto &VC : VCs) {
3564       Record.clear();
3565       Record.push_back(VC.VFunc.GUID);
3566       Record.push_back(VC.VFunc.Offset);
3567       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3568       Stream.EmitRecord(Ty, Record);
3569     }
3570   };
3571 
3572   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3573                      FS->type_test_assume_const_vcalls());
3574   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3575                      FS->type_checked_load_const_vcalls());
3576 }
3577 
3578 /// Collect type IDs from type tests used by function.
3579 static void
3580 getReferencedTypeIds(FunctionSummary *FS,
3581                      std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3582   if (!FS->type_tests().empty())
3583     for (auto &TT : FS->type_tests())
3584       ReferencedTypeIds.insert(TT);
3585 
3586   auto GetReferencedTypesFromVFuncIdVec =
3587       [&](ArrayRef<FunctionSummary::VFuncId> VFs) {
3588         for (auto &VF : VFs)
3589           ReferencedTypeIds.insert(VF.GUID);
3590       };
3591 
3592   GetReferencedTypesFromVFuncIdVec(FS->type_test_assume_vcalls());
3593   GetReferencedTypesFromVFuncIdVec(FS->type_checked_load_vcalls());
3594 
3595   auto GetReferencedTypesFromConstVCallVec =
3596       [&](ArrayRef<FunctionSummary::ConstVCall> VCs) {
3597         for (auto &VC : VCs)
3598           ReferencedTypeIds.insert(VC.VFunc.GUID);
3599       };
3600 
3601   GetReferencedTypesFromConstVCallVec(FS->type_test_assume_const_vcalls());
3602   GetReferencedTypesFromConstVCallVec(FS->type_checked_load_const_vcalls());
3603 }
3604 
3605 static void writeWholeProgramDevirtResolutionByArg(
3606     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3607     const WholeProgramDevirtResolution::ByArg &ByArg) {
3608   NameVals.push_back(args.size());
3609   NameVals.insert(NameVals.end(), args.begin(), args.end());
3610 
3611   NameVals.push_back(ByArg.TheKind);
3612   NameVals.push_back(ByArg.Info);
3613   NameVals.push_back(ByArg.Byte);
3614   NameVals.push_back(ByArg.Bit);
3615 }
3616 
3617 static void writeWholeProgramDevirtResolution(
3618     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3619     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3620   NameVals.push_back(Id);
3621 
3622   NameVals.push_back(Wpd.TheKind);
3623   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3624   NameVals.push_back(Wpd.SingleImplName.size());
3625 
3626   NameVals.push_back(Wpd.ResByArg.size());
3627   for (auto &A : Wpd.ResByArg)
3628     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3629 }
3630 
3631 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3632                                      StringTableBuilder &StrtabBuilder,
3633                                      const std::string &Id,
3634                                      const TypeIdSummary &Summary) {
3635   NameVals.push_back(StrtabBuilder.add(Id));
3636   NameVals.push_back(Id.size());
3637 
3638   NameVals.push_back(Summary.TTRes.TheKind);
3639   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3640   NameVals.push_back(Summary.TTRes.AlignLog2);
3641   NameVals.push_back(Summary.TTRes.SizeM1);
3642   NameVals.push_back(Summary.TTRes.BitMask);
3643   NameVals.push_back(Summary.TTRes.InlineBits);
3644 
3645   for (auto &W : Summary.WPDRes)
3646     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3647                                       W.second);
3648 }
3649 
3650 static void writeTypeIdCompatibleVtableSummaryRecord(
3651     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3652     const std::string &Id, const TypeIdCompatibleVtableInfo &Summary,
3653     ValueEnumerator &VE) {
3654   NameVals.push_back(StrtabBuilder.add(Id));
3655   NameVals.push_back(Id.size());
3656 
3657   for (auto &P : Summary) {
3658     NameVals.push_back(P.AddressPointOffset);
3659     NameVals.push_back(VE.getValueID(P.VTableVI.getValue()));
3660   }
3661 }
3662 
3663 // Helper to emit a single function summary record.
3664 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3665     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3666     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3667     const Function &F) {
3668   NameVals.push_back(ValueID);
3669 
3670   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3671   writeFunctionTypeMetadataRecords(Stream, FS);
3672 
3673   auto SpecialRefCnts = FS->specialRefCounts();
3674   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3675   NameVals.push_back(FS->instCount());
3676   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3677   NameVals.push_back(FS->refs().size());
3678   NameVals.push_back(SpecialRefCnts.first);  // rorefcnt
3679   NameVals.push_back(SpecialRefCnts.second); // worefcnt
3680 
3681   for (auto &RI : FS->refs())
3682     NameVals.push_back(VE.getValueID(RI.getValue()));
3683 
3684   bool HasProfileData =
3685       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3686   for (auto &ECI : FS->calls()) {
3687     NameVals.push_back(getValueId(ECI.first));
3688     if (HasProfileData)
3689       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3690     else if (WriteRelBFToSummary)
3691       NameVals.push_back(ECI.second.RelBlockFreq);
3692   }
3693 
3694   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3695   unsigned Code =
3696       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3697                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3698                                              : bitc::FS_PERMODULE));
3699 
3700   // Emit the finished record.
3701   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3702   NameVals.clear();
3703 }
3704 
3705 // Collect the global value references in the given variable's initializer,
3706 // and emit them in a summary record.
3707 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3708     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3709     unsigned FSModRefsAbbrev, unsigned FSModVTableRefsAbbrev) {
3710   auto VI = Index->getValueInfo(V.getGUID());
3711   if (!VI || VI.getSummaryList().empty()) {
3712     // Only declarations should not have a summary (a declaration might however
3713     // have a summary if the def was in module level asm).
3714     assert(V.isDeclaration());
3715     return;
3716   }
3717   auto *Summary = VI.getSummaryList()[0].get();
3718   NameVals.push_back(VE.getValueID(&V));
3719   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3720   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3721   NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
3722 
3723   auto VTableFuncs = VS->vTableFuncs();
3724   if (!VTableFuncs.empty())
3725     NameVals.push_back(VS->refs().size());
3726 
3727   unsigned SizeBeforeRefs = NameVals.size();
3728   for (auto &RI : VS->refs())
3729     NameVals.push_back(VE.getValueID(RI.getValue()));
3730   // Sort the refs for determinism output, the vector returned by FS->refs() has
3731   // been initialized from a DenseSet.
3732   llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3733 
3734   if (VTableFuncs.empty())
3735     Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3736                       FSModRefsAbbrev);
3737   else {
3738     // VTableFuncs pairs should already be sorted by offset.
3739     for (auto &P : VTableFuncs) {
3740       NameVals.push_back(VE.getValueID(P.FuncVI.getValue()));
3741       NameVals.push_back(P.VTableOffset);
3742     }
3743 
3744     Stream.EmitRecord(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS, NameVals,
3745                       FSModVTableRefsAbbrev);
3746   }
3747   NameVals.clear();
3748 }
3749 
3750 /// Emit the per-module summary section alongside the rest of
3751 /// the module's bitcode.
3752 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3753   // By default we compile with ThinLTO if the module has a summary, but the
3754   // client can request full LTO with a module flag.
3755   bool IsThinLTO = true;
3756   if (auto *MD =
3757           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3758     IsThinLTO = MD->getZExtValue();
3759   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3760                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3761                        4);
3762 
3763   Stream.EmitRecord(
3764       bitc::FS_VERSION,
3765       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
3766 
3767   // Write the index flags.
3768   uint64_t Flags = 0;
3769   // Bits 1-3 are set only in the combined index, skip them.
3770   if (Index->enableSplitLTOUnit())
3771     Flags |= 0x8;
3772   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
3773 
3774   if (Index->begin() == Index->end()) {
3775     Stream.ExitBlock();
3776     return;
3777   }
3778 
3779   for (const auto &GVI : valueIds()) {
3780     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3781                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3782   }
3783 
3784   // Abbrev for FS_PERMODULE_PROFILE.
3785   auto Abbv = std::make_shared<BitCodeAbbrev>();
3786   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3787   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3788   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3789   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3790   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3791   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3792   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3793   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3794   // numrefs x valueid, n x (valueid, hotness)
3795   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3796   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3797   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3798 
3799   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
3800   Abbv = std::make_shared<BitCodeAbbrev>();
3801   if (WriteRelBFToSummary)
3802     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
3803   else
3804     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3805   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3806   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3807   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3808   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3809   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3810   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3811   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3812   // numrefs x valueid, n x (valueid [, rel_block_freq])
3813   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3814   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3815   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3816 
3817   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3818   Abbv = std::make_shared<BitCodeAbbrev>();
3819   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3820   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3822   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3823   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3824   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3825 
3826   // Abbrev for FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS.
3827   Abbv = std::make_shared<BitCodeAbbrev>();
3828   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_VTABLE_GLOBALVAR_INIT_REFS));
3829   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3830   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3831   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // numrefs
3832   // numrefs x valueid, n x (valueid , offset)
3833   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3834   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3835   unsigned FSModVTableRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3836 
3837   // Abbrev for FS_ALIAS.
3838   Abbv = std::make_shared<BitCodeAbbrev>();
3839   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3840   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3841   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3842   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3843   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3844 
3845   // Abbrev for FS_TYPE_ID_METADATA
3846   Abbv = std::make_shared<BitCodeAbbrev>();
3847   Abbv->Add(BitCodeAbbrevOp(bitc::FS_TYPE_ID_METADATA));
3848   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid strtab index
3849   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // typeid length
3850   // n x (valueid , offset)
3851   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3852   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3853   unsigned TypeIdCompatibleVtableAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3854 
3855   SmallVector<uint64_t, 64> NameVals;
3856   // Iterate over the list of functions instead of the Index to
3857   // ensure the ordering is stable.
3858   for (const Function &F : M) {
3859     // Summary emission does not support anonymous functions, they have to
3860     // renamed using the anonymous function renaming pass.
3861     if (!F.hasName())
3862       report_fatal_error("Unexpected anonymous function when writing summary");
3863 
3864     ValueInfo VI = Index->getValueInfo(F.getGUID());
3865     if (!VI || VI.getSummaryList().empty()) {
3866       // Only declarations should not have a summary (a declaration might
3867       // however have a summary if the def was in module level asm).
3868       assert(F.isDeclaration());
3869       continue;
3870     }
3871     auto *Summary = VI.getSummaryList()[0].get();
3872     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3873                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3874   }
3875 
3876   // Capture references from GlobalVariable initializers, which are outside
3877   // of a function scope.
3878   for (const GlobalVariable &G : M.globals())
3879     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev,
3880                                FSModVTableRefsAbbrev);
3881 
3882   for (const GlobalAlias &A : M.aliases()) {
3883     auto *Aliasee = A.getBaseObject();
3884     if (!Aliasee->hasName())
3885       // Nameless function don't have an entry in the summary, skip it.
3886       continue;
3887     auto AliasId = VE.getValueID(&A);
3888     auto AliaseeId = VE.getValueID(Aliasee);
3889     NameVals.push_back(AliasId);
3890     auto *Summary = Index->getGlobalValueSummary(A);
3891     AliasSummary *AS = cast<AliasSummary>(Summary);
3892     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3893     NameVals.push_back(AliaseeId);
3894     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3895     NameVals.clear();
3896   }
3897 
3898   for (auto &S : Index->typeIdCompatibleVtableMap()) {
3899     writeTypeIdCompatibleVtableSummaryRecord(NameVals, StrtabBuilder, S.first,
3900                                              S.second, VE);
3901     Stream.EmitRecord(bitc::FS_TYPE_ID_METADATA, NameVals,
3902                       TypeIdCompatibleVtableAbbrev);
3903     NameVals.clear();
3904   }
3905 
3906   Stream.ExitBlock();
3907 }
3908 
3909 /// Emit the combined summary section into the combined index file.
3910 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3911   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3912   Stream.EmitRecord(
3913       bitc::FS_VERSION,
3914       ArrayRef<uint64_t>{ModuleSummaryIndex::BitcodeSummaryVersion});
3915 
3916   // Write the index flags.
3917   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Index.getFlags()});
3918 
3919   for (const auto &GVI : valueIds()) {
3920     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3921                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3922   }
3923 
3924   // Abbrev for FS_COMBINED.
3925   auto Abbv = std::make_shared<BitCodeAbbrev>();
3926   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3927   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3928   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3929   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
3933   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3934   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3935   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3936   // numrefs x valueid, n x (valueid)
3937   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3938   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3939   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3940 
3941   // Abbrev for FS_COMBINED_PROFILE.
3942   Abbv = std::make_shared<BitCodeAbbrev>();
3943   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3944   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3945   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3946   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3947   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3948   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3949   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
3950   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3951   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // rorefcnt
3952   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // worefcnt
3953   // numrefs x valueid, n x (valueid, hotness)
3954   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3955   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3956   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3957 
3958   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3959   Abbv = std::make_shared<BitCodeAbbrev>();
3960   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3961   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3962   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3963   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3964   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3965   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3966   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3967 
3968   // Abbrev for FS_COMBINED_ALIAS.
3969   Abbv = std::make_shared<BitCodeAbbrev>();
3970   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3971   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3972   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3973   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3974   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3975   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3976 
3977   // The aliases are emitted as a post-pass, and will point to the value
3978   // id of the aliasee. Save them in a vector for post-processing.
3979   SmallVector<AliasSummary *, 64> Aliases;
3980 
3981   // Save the value id for each summary for alias emission.
3982   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3983 
3984   SmallVector<uint64_t, 64> NameVals;
3985 
3986   // Set that will be populated during call to writeFunctionTypeMetadataRecords
3987   // with the type ids referenced by this index file.
3988   std::set<GlobalValue::GUID> ReferencedTypeIds;
3989 
3990   // For local linkage, we also emit the original name separately
3991   // immediately after the record.
3992   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3993     if (!GlobalValue::isLocalLinkage(S.linkage()))
3994       return;
3995     NameVals.push_back(S.getOriginalName());
3996     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3997     NameVals.clear();
3998   };
3999 
4000   std::set<GlobalValue::GUID> DefOrUseGUIDs;
4001   forEachSummary([&](GVInfo I, bool IsAliasee) {
4002     GlobalValueSummary *S = I.second;
4003     assert(S);
4004     DefOrUseGUIDs.insert(I.first);
4005     for (const ValueInfo &VI : S->refs())
4006       DefOrUseGUIDs.insert(VI.getGUID());
4007 
4008     auto ValueId = getValueId(I.first);
4009     assert(ValueId);
4010     SummaryToValueIdMap[S] = *ValueId;
4011 
4012     // If this is invoked for an aliasee, we want to record the above
4013     // mapping, but then not emit a summary entry (if the aliasee is
4014     // to be imported, we will invoke this separately with IsAliasee=false).
4015     if (IsAliasee)
4016       return;
4017 
4018     if (auto *AS = dyn_cast<AliasSummary>(S)) {
4019       // Will process aliases as a post-pass because the reader wants all
4020       // global to be loaded first.
4021       Aliases.push_back(AS);
4022       return;
4023     }
4024 
4025     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
4026       NameVals.push_back(*ValueId);
4027       NameVals.push_back(Index.getModuleId(VS->modulePath()));
4028       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
4029       NameVals.push_back(getEncodedGVarFlags(VS->varflags()));
4030       for (auto &RI : VS->refs()) {
4031         auto RefValueId = getValueId(RI.getGUID());
4032         if (!RefValueId)
4033           continue;
4034         NameVals.push_back(*RefValueId);
4035       }
4036 
4037       // Emit the finished record.
4038       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
4039                         FSModRefsAbbrev);
4040       NameVals.clear();
4041       MaybeEmitOriginalName(*S);
4042       return;
4043     }
4044 
4045     auto *FS = cast<FunctionSummary>(S);
4046     writeFunctionTypeMetadataRecords(Stream, FS);
4047     getReferencedTypeIds(FS, ReferencedTypeIds);
4048 
4049     NameVals.push_back(*ValueId);
4050     NameVals.push_back(Index.getModuleId(FS->modulePath()));
4051     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
4052     NameVals.push_back(FS->instCount());
4053     NameVals.push_back(getEncodedFFlags(FS->fflags()));
4054     NameVals.push_back(FS->entryCount());
4055 
4056     // Fill in below
4057     NameVals.push_back(0); // numrefs
4058     NameVals.push_back(0); // rorefcnt
4059     NameVals.push_back(0); // worefcnt
4060 
4061     unsigned Count = 0, RORefCnt = 0, WORefCnt = 0;
4062     for (auto &RI : FS->refs()) {
4063       auto RefValueId = getValueId(RI.getGUID());
4064       if (!RefValueId)
4065         continue;
4066       NameVals.push_back(*RefValueId);
4067       if (RI.isReadOnly())
4068         RORefCnt++;
4069       else if (RI.isWriteOnly())
4070         WORefCnt++;
4071       Count++;
4072     }
4073     NameVals[6] = Count;
4074     NameVals[7] = RORefCnt;
4075     NameVals[8] = WORefCnt;
4076 
4077     bool HasProfileData = false;
4078     for (auto &EI : FS->calls()) {
4079       HasProfileData |=
4080           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
4081       if (HasProfileData)
4082         break;
4083     }
4084 
4085     for (auto &EI : FS->calls()) {
4086       // If this GUID doesn't have a value id, it doesn't have a function
4087       // summary and we don't need to record any calls to it.
4088       GlobalValue::GUID GUID = EI.first.getGUID();
4089       auto CallValueId = getValueId(GUID);
4090       if (!CallValueId) {
4091         // For SamplePGO, the indirect call targets for local functions will
4092         // have its original name annotated in profile. We try to find the
4093         // corresponding PGOFuncName as the GUID.
4094         GUID = Index.getGUIDFromOriginalID(GUID);
4095         if (GUID == 0)
4096           continue;
4097         CallValueId = getValueId(GUID);
4098         if (!CallValueId)
4099           continue;
4100         // The mapping from OriginalId to GUID may return a GUID
4101         // that corresponds to a static variable. Filter it out here.
4102         // This can happen when
4103         // 1) There is a call to a library function which does not have
4104         // a CallValidId;
4105         // 2) There is a static variable with the  OriginalGUID identical
4106         // to the GUID of the library function in 1);
4107         // When this happens, the logic for SamplePGO kicks in and
4108         // the static variable in 2) will be found, which needs to be
4109         // filtered out.
4110         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
4111         if (GVSum &&
4112             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
4113           continue;
4114       }
4115       NameVals.push_back(*CallValueId);
4116       if (HasProfileData)
4117         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
4118     }
4119 
4120     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
4121     unsigned Code =
4122         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
4123 
4124     // Emit the finished record.
4125     Stream.EmitRecord(Code, NameVals, FSAbbrev);
4126     NameVals.clear();
4127     MaybeEmitOriginalName(*S);
4128   });
4129 
4130   for (auto *AS : Aliases) {
4131     auto AliasValueId = SummaryToValueIdMap[AS];
4132     assert(AliasValueId);
4133     NameVals.push_back(AliasValueId);
4134     NameVals.push_back(Index.getModuleId(AS->modulePath()));
4135     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
4136     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
4137     assert(AliaseeValueId);
4138     NameVals.push_back(AliaseeValueId);
4139 
4140     // Emit the finished record.
4141     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
4142     NameVals.clear();
4143     MaybeEmitOriginalName(*AS);
4144 
4145     if (auto *FS = dyn_cast<FunctionSummary>(&AS->getAliasee()))
4146       getReferencedTypeIds(FS, ReferencedTypeIds);
4147   }
4148 
4149   if (!Index.cfiFunctionDefs().empty()) {
4150     for (auto &S : Index.cfiFunctionDefs()) {
4151       if (DefOrUseGUIDs.count(
4152               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4153         NameVals.push_back(StrtabBuilder.add(S));
4154         NameVals.push_back(S.size());
4155       }
4156     }
4157     if (!NameVals.empty()) {
4158       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
4159       NameVals.clear();
4160     }
4161   }
4162 
4163   if (!Index.cfiFunctionDecls().empty()) {
4164     for (auto &S : Index.cfiFunctionDecls()) {
4165       if (DefOrUseGUIDs.count(
4166               GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(S)))) {
4167         NameVals.push_back(StrtabBuilder.add(S));
4168         NameVals.push_back(S.size());
4169       }
4170     }
4171     if (!NameVals.empty()) {
4172       Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
4173       NameVals.clear();
4174     }
4175   }
4176 
4177   // Walk the GUIDs that were referenced, and write the
4178   // corresponding type id records.
4179   for (auto &T : ReferencedTypeIds) {
4180     auto TidIter = Index.typeIds().equal_range(T);
4181     for (auto It = TidIter.first; It != TidIter.second; ++It) {
4182       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, It->second.first,
4183                                It->second.second);
4184       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
4185       NameVals.clear();
4186     }
4187   }
4188 
4189   Stream.ExitBlock();
4190 }
4191 
4192 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
4193 /// current llvm version, and a record for the epoch number.
4194 static void writeIdentificationBlock(BitstreamWriter &Stream) {
4195   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
4196 
4197   // Write the "user readable" string identifying the bitcode producer
4198   auto Abbv = std::make_shared<BitCodeAbbrev>();
4199   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
4200   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4201   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
4202   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4203   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
4204                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
4205 
4206   // Write the epoch version
4207   Abbv = std::make_shared<BitCodeAbbrev>();
4208   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
4209   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
4210   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4211   constexpr std::array<unsigned, 1> Vals = {{bitc::BITCODE_CURRENT_EPOCH}};
4212   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
4213   Stream.ExitBlock();
4214 }
4215 
4216 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
4217   // Emit the module's hash.
4218   // MODULE_CODE_HASH: [5*i32]
4219   if (GenerateHash) {
4220     uint32_t Vals[5];
4221     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
4222                                     Buffer.size() - BlockStartPos));
4223     StringRef Hash = Hasher.result();
4224     for (int Pos = 0; Pos < 20; Pos += 4) {
4225       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
4226     }
4227 
4228     // Emit the finished record.
4229     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
4230 
4231     if (ModHash)
4232       // Save the written hash value.
4233       llvm::copy(Vals, std::begin(*ModHash));
4234   }
4235 }
4236 
4237 void ModuleBitcodeWriter::write() {
4238   writeIdentificationBlock(Stream);
4239 
4240   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4241   size_t BlockStartPos = Buffer.size();
4242 
4243   writeModuleVersion();
4244 
4245   // Emit blockinfo, which defines the standard abbreviations etc.
4246   writeBlockInfo();
4247 
4248   // Emit information describing all of the types in the module.
4249   writeTypeTable();
4250 
4251   // Emit information about attribute groups.
4252   writeAttributeGroupTable();
4253 
4254   // Emit information about parameter attributes.
4255   writeAttributeTable();
4256 
4257   writeComdats();
4258 
4259   // Emit top-level description of module, including target triple, inline asm,
4260   // descriptors for global variables, and function prototype info.
4261   writeModuleInfo();
4262 
4263   // Emit constants.
4264   writeModuleConstants();
4265 
4266   // Emit metadata kind names.
4267   writeModuleMetadataKinds();
4268 
4269   // Emit metadata.
4270   writeModuleMetadata();
4271 
4272   // Emit module-level use-lists.
4273   if (VE.shouldPreserveUseListOrder())
4274     writeUseListBlock(nullptr);
4275 
4276   writeOperandBundleTags();
4277   writeSyncScopeNames();
4278 
4279   // Emit function bodies.
4280   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
4281   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
4282     if (!F->isDeclaration())
4283       writeFunction(*F, FunctionToBitcodeIndex);
4284 
4285   // Need to write after the above call to WriteFunction which populates
4286   // the summary information in the index.
4287   if (Index)
4288     writePerModuleGlobalValueSummary();
4289 
4290   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
4291 
4292   writeModuleHash(BlockStartPos);
4293 
4294   Stream.ExitBlock();
4295 }
4296 
4297 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
4298                                uint32_t &Position) {
4299   support::endian::write32le(&Buffer[Position], Value);
4300   Position += 4;
4301 }
4302 
4303 /// If generating a bc file on darwin, we have to emit a
4304 /// header and trailer to make it compatible with the system archiver.  To do
4305 /// this we emit the following header, and then emit a trailer that pads the
4306 /// file out to be a multiple of 16 bytes.
4307 ///
4308 /// struct bc_header {
4309 ///   uint32_t Magic;         // 0x0B17C0DE
4310 ///   uint32_t Version;       // Version, currently always 0.
4311 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4312 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4313 ///   uint32_t CPUType;       // CPU specifier.
4314 ///   ... potentially more later ...
4315 /// };
4316 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4317                                          const Triple &TT) {
4318   unsigned CPUType = ~0U;
4319 
4320   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4321   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4322   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4323   // specific constants here because they are implicitly part of the Darwin ABI.
4324   enum {
4325     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4326     DARWIN_CPU_TYPE_X86        = 7,
4327     DARWIN_CPU_TYPE_ARM        = 12,
4328     DARWIN_CPU_TYPE_POWERPC    = 18
4329   };
4330 
4331   Triple::ArchType Arch = TT.getArch();
4332   if (Arch == Triple::x86_64)
4333     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4334   else if (Arch == Triple::x86)
4335     CPUType = DARWIN_CPU_TYPE_X86;
4336   else if (Arch == Triple::ppc)
4337     CPUType = DARWIN_CPU_TYPE_POWERPC;
4338   else if (Arch == Triple::ppc64)
4339     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4340   else if (Arch == Triple::arm || Arch == Triple::thumb)
4341     CPUType = DARWIN_CPU_TYPE_ARM;
4342 
4343   // Traditional Bitcode starts after header.
4344   assert(Buffer.size() >= BWH_HeaderSize &&
4345          "Expected header size to be reserved");
4346   unsigned BCOffset = BWH_HeaderSize;
4347   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4348 
4349   // Write the magic and version.
4350   unsigned Position = 0;
4351   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4352   writeInt32ToBuffer(0, Buffer, Position); // Version.
4353   writeInt32ToBuffer(BCOffset, Buffer, Position);
4354   writeInt32ToBuffer(BCSize, Buffer, Position);
4355   writeInt32ToBuffer(CPUType, Buffer, Position);
4356 
4357   // If the file is not a multiple of 16 bytes, insert dummy padding.
4358   while (Buffer.size() & 15)
4359     Buffer.push_back(0);
4360 }
4361 
4362 /// Helper to write the header common to all bitcode files.
4363 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4364   // Emit the file header.
4365   Stream.Emit((unsigned)'B', 8);
4366   Stream.Emit((unsigned)'C', 8);
4367   Stream.Emit(0x0, 4);
4368   Stream.Emit(0xC, 4);
4369   Stream.Emit(0xE, 4);
4370   Stream.Emit(0xD, 4);
4371 }
4372 
4373 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
4374     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
4375   writeBitcodeHeader(*Stream);
4376 }
4377 
4378 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4379 
4380 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4381   Stream->EnterSubblock(Block, 3);
4382 
4383   auto Abbv = std::make_shared<BitCodeAbbrev>();
4384   Abbv->Add(BitCodeAbbrevOp(Record));
4385   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4386   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4387 
4388   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4389 
4390   Stream->ExitBlock();
4391 }
4392 
4393 void BitcodeWriter::writeSymtab() {
4394   assert(!WroteStrtab && !WroteSymtab);
4395 
4396   // If any module has module-level inline asm, we will require a registered asm
4397   // parser for the target so that we can create an accurate symbol table for
4398   // the module.
4399   for (Module *M : Mods) {
4400     if (M->getModuleInlineAsm().empty())
4401       continue;
4402 
4403     std::string Err;
4404     const Triple TT(M->getTargetTriple());
4405     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4406     if (!T || !T->hasMCAsmParser())
4407       return;
4408   }
4409 
4410   WroteSymtab = true;
4411   SmallVector<char, 0> Symtab;
4412   // The irsymtab::build function may be unable to create a symbol table if the
4413   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4414   // table is not required for correctness, but we still want to be able to
4415   // write malformed modules to bitcode files, so swallow the error.
4416   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4417     consumeError(std::move(E));
4418     return;
4419   }
4420 
4421   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4422             {Symtab.data(), Symtab.size()});
4423 }
4424 
4425 void BitcodeWriter::writeStrtab() {
4426   assert(!WroteStrtab);
4427 
4428   std::vector<char> Strtab;
4429   StrtabBuilder.finalizeInOrder();
4430   Strtab.resize(StrtabBuilder.getSize());
4431   StrtabBuilder.write((uint8_t *)Strtab.data());
4432 
4433   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4434             {Strtab.data(), Strtab.size()});
4435 
4436   WroteStrtab = true;
4437 }
4438 
4439 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4440   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4441   WroteStrtab = true;
4442 }
4443 
4444 void BitcodeWriter::writeModule(const Module &M,
4445                                 bool ShouldPreserveUseListOrder,
4446                                 const ModuleSummaryIndex *Index,
4447                                 bool GenerateHash, ModuleHash *ModHash) {
4448   assert(!WroteStrtab);
4449 
4450   // The Mods vector is used by irsymtab::build, which requires non-const
4451   // Modules in case it needs to materialize metadata. But the bitcode writer
4452   // requires that the module is materialized, so we can cast to non-const here,
4453   // after checking that it is in fact materialized.
4454   assert(M.isMaterialized());
4455   Mods.push_back(const_cast<Module *>(&M));
4456 
4457   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4458                                    ShouldPreserveUseListOrder, Index,
4459                                    GenerateHash, ModHash);
4460   ModuleWriter.write();
4461 }
4462 
4463 void BitcodeWriter::writeIndex(
4464     const ModuleSummaryIndex *Index,
4465     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4466   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4467                                  ModuleToSummariesForIndex);
4468   IndexWriter.write();
4469 }
4470 
4471 /// Write the specified module to the specified output stream.
4472 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4473                               bool ShouldPreserveUseListOrder,
4474                               const ModuleSummaryIndex *Index,
4475                               bool GenerateHash, ModuleHash *ModHash) {
4476   SmallVector<char, 0> Buffer;
4477   Buffer.reserve(256*1024);
4478 
4479   // If this is darwin or another generic macho target, reserve space for the
4480   // header.
4481   Triple TT(M.getTargetTriple());
4482   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4483     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4484 
4485   BitcodeWriter Writer(Buffer);
4486   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4487                      ModHash);
4488   Writer.writeSymtab();
4489   Writer.writeStrtab();
4490 
4491   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4492     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4493 
4494   // Write the generated bitstream to "Out".
4495   Out.write((char*)&Buffer.front(), Buffer.size());
4496 }
4497 
4498 void IndexBitcodeWriter::write() {
4499   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4500 
4501   writeModuleVersion();
4502 
4503   // Write the module paths in the combined index.
4504   writeModStrings();
4505 
4506   // Write the summary combined index records.
4507   writeCombinedGlobalValueSummary();
4508 
4509   Stream.ExitBlock();
4510 }
4511 
4512 // Write the specified module summary index to the given raw output stream,
4513 // where it will be written in a new bitcode block. This is used when
4514 // writing the combined index file for ThinLTO. When writing a subset of the
4515 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4516 void llvm::WriteIndexToFile(
4517     const ModuleSummaryIndex &Index, raw_ostream &Out,
4518     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4519   SmallVector<char, 0> Buffer;
4520   Buffer.reserve(256 * 1024);
4521 
4522   BitcodeWriter Writer(Buffer);
4523   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4524   Writer.writeStrtab();
4525 
4526   Out.write((char *)&Buffer.front(), Buffer.size());
4527 }
4528 
4529 namespace {
4530 
4531 /// Class to manage the bitcode writing for a thin link bitcode file.
4532 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4533   /// ModHash is for use in ThinLTO incremental build, generated while writing
4534   /// the module bitcode file.
4535   const ModuleHash *ModHash;
4536 
4537 public:
4538   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4539                         BitstreamWriter &Stream,
4540                         const ModuleSummaryIndex &Index,
4541                         const ModuleHash &ModHash)
4542       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4543                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4544         ModHash(&ModHash) {}
4545 
4546   void write();
4547 
4548 private:
4549   void writeSimplifiedModuleInfo();
4550 };
4551 
4552 } // end anonymous namespace
4553 
4554 // This function writes a simpilified module info for thin link bitcode file.
4555 // It only contains the source file name along with the name(the offset and
4556 // size in strtab) and linkage for global values. For the global value info
4557 // entry, in order to keep linkage at offset 5, there are three zeros used
4558 // as padding.
4559 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4560   SmallVector<unsigned, 64> Vals;
4561   // Emit the module's source file name.
4562   {
4563     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4564     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4565     if (Bits == SE_Char6)
4566       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4567     else if (Bits == SE_Fixed7)
4568       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4569 
4570     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4571     auto Abbv = std::make_shared<BitCodeAbbrev>();
4572     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4573     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4574     Abbv->Add(AbbrevOpToUse);
4575     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4576 
4577     for (const auto P : M.getSourceFileName())
4578       Vals.push_back((unsigned char)P);
4579 
4580     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4581     Vals.clear();
4582   }
4583 
4584   // Emit the global variable information.
4585   for (const GlobalVariable &GV : M.globals()) {
4586     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4587     Vals.push_back(StrtabBuilder.add(GV.getName()));
4588     Vals.push_back(GV.getName().size());
4589     Vals.push_back(0);
4590     Vals.push_back(0);
4591     Vals.push_back(0);
4592     Vals.push_back(getEncodedLinkage(GV));
4593 
4594     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4595     Vals.clear();
4596   }
4597 
4598   // Emit the function proto information.
4599   for (const Function &F : M) {
4600     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4601     Vals.push_back(StrtabBuilder.add(F.getName()));
4602     Vals.push_back(F.getName().size());
4603     Vals.push_back(0);
4604     Vals.push_back(0);
4605     Vals.push_back(0);
4606     Vals.push_back(getEncodedLinkage(F));
4607 
4608     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4609     Vals.clear();
4610   }
4611 
4612   // Emit the alias information.
4613   for (const GlobalAlias &A : M.aliases()) {
4614     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4615     Vals.push_back(StrtabBuilder.add(A.getName()));
4616     Vals.push_back(A.getName().size());
4617     Vals.push_back(0);
4618     Vals.push_back(0);
4619     Vals.push_back(0);
4620     Vals.push_back(getEncodedLinkage(A));
4621 
4622     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4623     Vals.clear();
4624   }
4625 
4626   // Emit the ifunc information.
4627   for (const GlobalIFunc &I : M.ifuncs()) {
4628     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4629     Vals.push_back(StrtabBuilder.add(I.getName()));
4630     Vals.push_back(I.getName().size());
4631     Vals.push_back(0);
4632     Vals.push_back(0);
4633     Vals.push_back(0);
4634     Vals.push_back(getEncodedLinkage(I));
4635 
4636     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4637     Vals.clear();
4638   }
4639 }
4640 
4641 void ThinLinkBitcodeWriter::write() {
4642   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4643 
4644   writeModuleVersion();
4645 
4646   writeSimplifiedModuleInfo();
4647 
4648   writePerModuleGlobalValueSummary();
4649 
4650   // Write module hash.
4651   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4652 
4653   Stream.ExitBlock();
4654 }
4655 
4656 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4657                                          const ModuleSummaryIndex &Index,
4658                                          const ModuleHash &ModHash) {
4659   assert(!WroteStrtab);
4660 
4661   // The Mods vector is used by irsymtab::build, which requires non-const
4662   // Modules in case it needs to materialize metadata. But the bitcode writer
4663   // requires that the module is materialized, so we can cast to non-const here,
4664   // after checking that it is in fact materialized.
4665   assert(M.isMaterialized());
4666   Mods.push_back(const_cast<Module *>(&M));
4667 
4668   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4669                                        ModHash);
4670   ThinLinkWriter.write();
4671 }
4672 
4673 // Write the specified thin link bitcode file to the given raw output stream,
4674 // where it will be written in a new bitcode block. This is used when
4675 // writing the per-module index file for ThinLTO.
4676 void llvm::WriteThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4677                                       const ModuleSummaryIndex &Index,
4678                                       const ModuleHash &ModHash) {
4679   SmallVector<char, 0> Buffer;
4680   Buffer.reserve(256 * 1024);
4681 
4682   BitcodeWriter Writer(Buffer);
4683   Writer.writeThinLinkBitcode(M, Index, ModHash);
4684   Writer.writeSymtab();
4685   Writer.writeStrtab();
4686 
4687   Out.write((char *)&Buffer.front(), Buffer.size());
4688 }
4689 
4690 static const char *getSectionNameForBitcode(const Triple &T) {
4691   switch (T.getObjectFormat()) {
4692   case Triple::MachO:
4693     return "__LLVM,__bitcode";
4694   case Triple::COFF:
4695   case Triple::ELF:
4696   case Triple::Wasm:
4697   case Triple::UnknownObjectFormat:
4698     return ".llvmbc";
4699   case Triple::XCOFF:
4700     llvm_unreachable("XCOFF is not yet implemented");
4701     break;
4702   }
4703   llvm_unreachable("Unimplemented ObjectFormatType");
4704 }
4705 
4706 static const char *getSectionNameForCommandline(const Triple &T) {
4707   switch (T.getObjectFormat()) {
4708   case Triple::MachO:
4709     return "__LLVM,__cmdline";
4710   case Triple::COFF:
4711   case Triple::ELF:
4712   case Triple::Wasm:
4713   case Triple::UnknownObjectFormat:
4714     return ".llvmcmd";
4715   case Triple::XCOFF:
4716     llvm_unreachable("XCOFF is not yet implemented");
4717     break;
4718   }
4719   llvm_unreachable("Unimplemented ObjectFormatType");
4720 }
4721 
4722 void llvm::EmbedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
4723                                 bool EmbedBitcode, bool EmbedMarker,
4724                                 const std::vector<uint8_t> *CmdArgs) {
4725   // Save llvm.compiler.used and remove it.
4726   SmallVector<Constant *, 2> UsedArray;
4727   SmallPtrSet<GlobalValue *, 4> UsedGlobals;
4728   Type *UsedElementType = Type::getInt8Ty(M.getContext())->getPointerTo(0);
4729   GlobalVariable *Used = collectUsedGlobalVariables(M, UsedGlobals, true);
4730   for (auto *GV : UsedGlobals) {
4731     if (GV->getName() != "llvm.embedded.module" &&
4732         GV->getName() != "llvm.cmdline")
4733       UsedArray.push_back(
4734           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4735   }
4736   if (Used)
4737     Used->eraseFromParent();
4738 
4739   // Embed the bitcode for the llvm module.
4740   std::string Data;
4741   ArrayRef<uint8_t> ModuleData;
4742   Triple T(M.getTargetTriple());
4743   // Create a constant that contains the bitcode.
4744   // In case of embedding a marker, ignore the input Buf and use the empty
4745   // ArrayRef. It is also legal to create a bitcode marker even Buf is empty.
4746   if (EmbedBitcode) {
4747     if (!isBitcode((const unsigned char *)Buf.getBufferStart(),
4748                    (const unsigned char *)Buf.getBufferEnd())) {
4749       // If the input is LLVM Assembly, bitcode is produced by serializing
4750       // the module. Use-lists order need to be preserved in this case.
4751       llvm::raw_string_ostream OS(Data);
4752       llvm::WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
4753       ModuleData =
4754           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
4755     } else
4756       // If the input is LLVM bitcode, write the input byte stream directly.
4757       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
4758                                      Buf.getBufferSize());
4759   }
4760   llvm::Constant *ModuleConstant =
4761       llvm::ConstantDataArray::get(M.getContext(), ModuleData);
4762   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
4763       M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
4764       ModuleConstant);
4765   GV->setSection(getSectionNameForBitcode(T));
4766   UsedArray.push_back(
4767       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4768   if (llvm::GlobalVariable *Old =
4769           M.getGlobalVariable("llvm.embedded.module", true)) {
4770     assert(Old->hasOneUse() &&
4771            "llvm.embedded.module can only be used once in llvm.compiler.used");
4772     GV->takeName(Old);
4773     Old->eraseFromParent();
4774   } else {
4775     GV->setName("llvm.embedded.module");
4776   }
4777 
4778   // Skip if only bitcode needs to be embedded.
4779   if (EmbedMarker) {
4780     // Embed command-line options.
4781     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CmdArgs->data()),
4782                               CmdArgs->size());
4783     llvm::Constant *CmdConstant =
4784         llvm::ConstantDataArray::get(M.getContext(), CmdData);
4785     GV = new llvm::GlobalVariable(M, CmdConstant->getType(), true,
4786                                   llvm::GlobalValue::PrivateLinkage,
4787                                   CmdConstant);
4788     GV->setSection(getSectionNameForCommandline(T));
4789     UsedArray.push_back(
4790         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
4791     if (llvm::GlobalVariable *Old = M.getGlobalVariable("llvm.cmdline", true)) {
4792       assert(Old->hasOneUse() &&
4793              "llvm.cmdline can only be used once in llvm.compiler.used");
4794       GV->takeName(Old);
4795       Old->eraseFromParent();
4796     } else {
4797       GV->setName("llvm.cmdline");
4798     }
4799   }
4800 
4801   if (UsedArray.empty())
4802     return;
4803 
4804   // Recreate llvm.compiler.used.
4805   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
4806   auto *NewUsed = new GlobalVariable(
4807       M, ATy, false, llvm::GlobalValue::AppendingLinkage,
4808       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
4809   NewUsed->setSection("llvm.metadata");
4810 }
4811