xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 39770ca0a11c4cd19c38f51a1ffda6b07ab8b90d)
1 //===- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Bitcode writer implementation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Bitcode/BitcodeWriter.h"
15 #include "ValueEnumerator.h"
16 #include "llvm/ADT/APFloat.h"
17 #include "llvm/ADT/APInt.h"
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/None.h"
21 #include "llvm/ADT/Optional.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/StringMap.h"
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/Bitcode/BitCodes.h"
29 #include "llvm/Bitcode/BitstreamWriter.h"
30 #include "llvm/Bitcode/LLVMBitCodes.h"
31 #include "llvm/IR/Attributes.h"
32 #include "llvm/IR/BasicBlock.h"
33 #include "llvm/IR/CallSite.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 namespace {
90 
91 /// These are manifest constants used by the bitcode writer. They do not need to
92 /// be kept in sync with the reader, but need to be consistent within this file.
93 enum {
94   // VALUE_SYMTAB_BLOCK abbrev id's.
95   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
96   VST_ENTRY_7_ABBREV,
97   VST_ENTRY_6_ABBREV,
98   VST_BBENTRY_6_ABBREV,
99 
100   // CONSTANTS_BLOCK abbrev id's.
101   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
102   CONSTANTS_INTEGER_ABBREV,
103   CONSTANTS_CE_CAST_Abbrev,
104   CONSTANTS_NULL_Abbrev,
105 
106   // FUNCTION_BLOCK abbrev id's.
107   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
108   FUNCTION_INST_BINOP_ABBREV,
109   FUNCTION_INST_BINOP_FLAGS_ABBREV,
110   FUNCTION_INST_CAST_ABBREV,
111   FUNCTION_INST_RET_VOID_ABBREV,
112   FUNCTION_INST_RET_VAL_ABBREV,
113   FUNCTION_INST_UNREACHABLE_ABBREV,
114   FUNCTION_INST_GEP_ABBREV,
115 };
116 
117 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
118 /// file type.
119 class BitcodeWriterBase {
120 protected:
121   /// The stream created and owned by the client.
122   BitstreamWriter &Stream;
123 
124   StringTableBuilder &StrtabBuilder;
125 
126 public:
127   /// Constructs a BitcodeWriterBase object that writes to the provided
128   /// \p Stream.
129   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
130       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
131 
132 protected:
133   void writeBitcodeHeader();
134   void writeModuleVersion();
135 };
136 
137 void BitcodeWriterBase::writeModuleVersion() {
138   // VERSION: [version#]
139   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
140 }
141 
142 /// Base class to manage the module bitcode writing, currently subclassed for
143 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
144 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
145 protected:
146   /// The Module to write to bitcode.
147   const Module &M;
148 
149   /// Enumerates ids for all values in the module.
150   ValueEnumerator VE;
151 
152   /// Optional per-module index to write for ThinLTO.
153   const ModuleSummaryIndex *Index;
154 
155   /// Map that holds the correspondence between GUIDs in the summary index,
156   /// that came from indirect call profiles, and a value id generated by this
157   /// class to use in the VST and summary block records.
158   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
159 
160   /// Tracks the last value id recorded in the GUIDToValueMap.
161   unsigned GlobalValueId;
162 
163   /// Saves the offset of the VSTOffset record that must eventually be
164   /// backpatched with the offset of the actual VST.
165   uint64_t VSTOffsetPlaceholder = 0;
166 
167 public:
168   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
169   /// writing to the provided \p Buffer.
170   ModuleBitcodeWriterBase(const Module *M, StringTableBuilder &StrtabBuilder,
171                           BitstreamWriter &Stream,
172                           bool ShouldPreserveUseListOrder,
173                           const ModuleSummaryIndex *Index)
174       : BitcodeWriterBase(Stream, StrtabBuilder), M(*M),
175         VE(*M, ShouldPreserveUseListOrder), Index(Index) {
176     // Assign ValueIds to any callee values in the index that came from
177     // indirect call profiles and were recorded as a GUID not a Value*
178     // (which would have been assigned an ID by the ValueEnumerator).
179     // The starting ValueId is just after the number of values in the
180     // ValueEnumerator, so that they can be emitted in the VST.
181     GlobalValueId = VE.getValues().size();
182     if (!Index)
183       return;
184     for (const auto &GUIDSummaryLists : *Index)
185       // Examine all summaries for this GUID.
186       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
187         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
188           // For each call in the function summary, see if the call
189           // is to a GUID (which means it is for an indirect call,
190           // otherwise we would have a Value for it). If so, synthesize
191           // a value id.
192           for (auto &CallEdge : FS->calls())
193             if (!CallEdge.first.getValue())
194               assignValueId(CallEdge.first.getGUID());
195   }
196 
197 protected:
198   void writePerModuleGlobalValueSummary();
199 
200 private:
201   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
202                                            GlobalValueSummary *Summary,
203                                            unsigned ValueID,
204                                            unsigned FSCallsAbbrev,
205                                            unsigned FSCallsProfileAbbrev,
206                                            const Function &F);
207   void writeModuleLevelReferences(const GlobalVariable &V,
208                                   SmallVector<uint64_t, 64> &NameVals,
209                                   unsigned FSModRefsAbbrev);
210 
211   void assignValueId(GlobalValue::GUID ValGUID) {
212     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
213   }
214 
215   unsigned getValueId(GlobalValue::GUID ValGUID) {
216     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
217     // Expect that any GUID value had a value Id assigned by an
218     // earlier call to assignValueId.
219     assert(VMI != GUIDToValueIdMap.end() &&
220            "GUID does not have assigned value Id");
221     return VMI->second;
222   }
223 
224   // Helper to get the valueId for the type of value recorded in VI.
225   unsigned getValueId(ValueInfo VI) {
226     if (!VI.getValue())
227       return getValueId(VI.getGUID());
228     return VE.getValueID(VI.getValue());
229   }
230 
231   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
232 };
233 
234 /// Class to manage the bitcode writing for a module.
235 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
236   /// Pointer to the buffer allocated by caller for bitcode writing.
237   const SmallVectorImpl<char> &Buffer;
238 
239   /// True if a module hash record should be written.
240   bool GenerateHash;
241 
242   /// If non-null, when GenerateHash is true, the resulting hash is written
243   /// into ModHash.
244   ModuleHash *ModHash;
245 
246   SHA1 Hasher;
247 
248   /// The start bit of the identification block.
249   uint64_t BitcodeStartBit;
250 
251 public:
252   /// Constructs a ModuleBitcodeWriter object for the given Module,
253   /// writing to the provided \p Buffer.
254   ModuleBitcodeWriter(const Module *M, SmallVectorImpl<char> &Buffer,
255                       StringTableBuilder &StrtabBuilder,
256                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
257                       const ModuleSummaryIndex *Index, bool GenerateHash,
258                       ModuleHash *ModHash = nullptr)
259       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
260                                 ShouldPreserveUseListOrder, Index),
261         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
262         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
263 
264   /// Emit the current module to the bitstream.
265   void write();
266 
267 private:
268   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
269 
270   size_t addToStrtab(StringRef Str);
271 
272   void writeAttributeGroupTable();
273   void writeAttributeTable();
274   void writeTypeTable();
275   void writeComdats();
276   void writeValueSymbolTableForwardDecl();
277   void writeModuleInfo();
278   void writeValueAsMetadata(const ValueAsMetadata *MD,
279                             SmallVectorImpl<uint64_t> &Record);
280   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
281                     unsigned Abbrev);
282   unsigned createDILocationAbbrev();
283   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
284                        unsigned &Abbrev);
285   unsigned createGenericDINodeAbbrev();
286   void writeGenericDINode(const GenericDINode *N,
287                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
288   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
289                        unsigned Abbrev);
290   void writeDIEnumerator(const DIEnumerator *N,
291                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
292   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
293                         unsigned Abbrev);
294   void writeDIDerivedType(const DIDerivedType *N,
295                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
296   void writeDICompositeType(const DICompositeType *N,
297                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
298   void writeDISubroutineType(const DISubroutineType *N,
299                              SmallVectorImpl<uint64_t> &Record,
300                              unsigned Abbrev);
301   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
302                    unsigned Abbrev);
303   void writeDICompileUnit(const DICompileUnit *N,
304                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
305   void writeDISubprogram(const DISubprogram *N,
306                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
307   void writeDILexicalBlock(const DILexicalBlock *N,
308                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
309   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
310                                SmallVectorImpl<uint64_t> &Record,
311                                unsigned Abbrev);
312   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
313                         unsigned Abbrev);
314   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
315                     unsigned Abbrev);
316   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
317                         unsigned Abbrev);
318   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
319                      unsigned Abbrev);
320   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
321                                     SmallVectorImpl<uint64_t> &Record,
322                                     unsigned Abbrev);
323   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
324                                      SmallVectorImpl<uint64_t> &Record,
325                                      unsigned Abbrev);
326   void writeDIGlobalVariable(const DIGlobalVariable *N,
327                              SmallVectorImpl<uint64_t> &Record,
328                              unsigned Abbrev);
329   void writeDILocalVariable(const DILocalVariable *N,
330                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
331   void writeDIExpression(const DIExpression *N,
332                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
333   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
334                                        SmallVectorImpl<uint64_t> &Record,
335                                        unsigned Abbrev);
336   void writeDIObjCProperty(const DIObjCProperty *N,
337                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
338   void writeDIImportedEntity(const DIImportedEntity *N,
339                              SmallVectorImpl<uint64_t> &Record,
340                              unsigned Abbrev);
341   unsigned createNamedMetadataAbbrev();
342   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
343   unsigned createMetadataStringsAbbrev();
344   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
345                             SmallVectorImpl<uint64_t> &Record);
346   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
347                             SmallVectorImpl<uint64_t> &Record,
348                             std::vector<unsigned> *MDAbbrevs = nullptr,
349                             std::vector<uint64_t> *IndexPos = nullptr);
350   void writeModuleMetadata();
351   void writeFunctionMetadata(const Function &F);
352   void writeFunctionMetadataAttachment(const Function &F);
353   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
354   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
355                                     const GlobalObject &GO);
356   void writeModuleMetadataKinds();
357   void writeOperandBundleTags();
358   void writeSyncScopeNames();
359   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
360   void writeModuleConstants();
361   bool pushValueAndType(const Value *V, unsigned InstID,
362                         SmallVectorImpl<unsigned> &Vals);
363   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
364   void pushValue(const Value *V, unsigned InstID,
365                  SmallVectorImpl<unsigned> &Vals);
366   void pushValueSigned(const Value *V, unsigned InstID,
367                        SmallVectorImpl<uint64_t> &Vals);
368   void writeInstruction(const Instruction &I, unsigned InstID,
369                         SmallVectorImpl<unsigned> &Vals);
370   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
371   void writeGlobalValueSymbolTable(
372       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
373   void writeUseList(UseListOrder &&Order);
374   void writeUseListBlock(const Function *F);
375   void
376   writeFunction(const Function &F,
377                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
378   void writeBlockInfo();
379   void writeModuleHash(size_t BlockStartPos);
380 
381   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
382     return unsigned(SSID);
383   }
384 };
385 
386 /// Class to manage the bitcode writing for a combined index.
387 class IndexBitcodeWriter : public BitcodeWriterBase {
388   /// The combined index to write to bitcode.
389   const ModuleSummaryIndex &Index;
390 
391   /// When writing a subset of the index for distributed backends, client
392   /// provides a map of modules to the corresponding GUIDs/summaries to write.
393   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
394 
395   /// Map that holds the correspondence between the GUID used in the combined
396   /// index and a value id generated by this class to use in references.
397   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
398 
399   /// Tracks the last value id recorded in the GUIDToValueMap.
400   unsigned GlobalValueId = 0;
401 
402 public:
403   /// Constructs a IndexBitcodeWriter object for the given combined index,
404   /// writing to the provided \p Buffer. When writing a subset of the index
405   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
406   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
407                      const ModuleSummaryIndex &Index,
408                      const std::map<std::string, GVSummaryMapTy>
409                          *ModuleToSummariesForIndex = nullptr)
410       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
411         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
412     // Assign unique value ids to all summaries to be written, for use
413     // in writing out the call graph edges. Save the mapping from GUID
414     // to the new global value id to use when writing those edges, which
415     // are currently saved in the index in terms of GUID.
416     forEachSummary([&](GVInfo I) {
417       GUIDToValueIdMap[I.first] = ++GlobalValueId;
418     });
419   }
420 
421   /// The below iterator returns the GUID and associated summary.
422   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
423 
424   /// Calls the callback for each value GUID and summary to be written to
425   /// bitcode. This hides the details of whether they are being pulled from the
426   /// entire index or just those in a provided ModuleToSummariesForIndex map.
427   template<typename Functor>
428   void forEachSummary(Functor Callback) {
429     if (ModuleToSummariesForIndex) {
430       for (auto &M : *ModuleToSummariesForIndex)
431         for (auto &Summary : M.second)
432           Callback(Summary);
433     } else {
434       for (auto &Summaries : Index)
435         for (auto &Summary : Summaries.second.SummaryList)
436           Callback({Summaries.first, Summary.get()});
437     }
438   }
439 
440   /// Calls the callback for each entry in the modulePaths StringMap that
441   /// should be written to the module path string table. This hides the details
442   /// of whether they are being pulled from the entire index or just those in a
443   /// provided ModuleToSummariesForIndex map.
444   template <typename Functor> void forEachModule(Functor Callback) {
445     if (ModuleToSummariesForIndex) {
446       for (const auto &M : *ModuleToSummariesForIndex) {
447         const auto &MPI = Index.modulePaths().find(M.first);
448         if (MPI == Index.modulePaths().end()) {
449           // This should only happen if the bitcode file was empty, in which
450           // case we shouldn't be importing (the ModuleToSummariesForIndex
451           // would only include the module we are writing and index for).
452           assert(ModuleToSummariesForIndex->size() == 1);
453           continue;
454         }
455         Callback(*MPI);
456       }
457     } else {
458       for (const auto &MPSE : Index.modulePaths())
459         Callback(MPSE);
460     }
461   }
462 
463   /// Main entry point for writing a combined index to bitcode.
464   void write();
465 
466 private:
467   void writeModStrings();
468   void writeCombinedGlobalValueSummary();
469 
470   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
471     auto VMI = GUIDToValueIdMap.find(ValGUID);
472     if (VMI == GUIDToValueIdMap.end())
473       return None;
474     return VMI->second;
475   }
476 
477   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
478 };
479 
480 } // end anonymous namespace
481 
482 static unsigned getEncodedCastOpcode(unsigned Opcode) {
483   switch (Opcode) {
484   default: llvm_unreachable("Unknown cast instruction!");
485   case Instruction::Trunc   : return bitc::CAST_TRUNC;
486   case Instruction::ZExt    : return bitc::CAST_ZEXT;
487   case Instruction::SExt    : return bitc::CAST_SEXT;
488   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
489   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
490   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
491   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
492   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
493   case Instruction::FPExt   : return bitc::CAST_FPEXT;
494   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
495   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
496   case Instruction::BitCast : return bitc::CAST_BITCAST;
497   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
498   }
499 }
500 
501 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
502   switch (Opcode) {
503   default: llvm_unreachable("Unknown binary instruction!");
504   case Instruction::Add:
505   case Instruction::FAdd: return bitc::BINOP_ADD;
506   case Instruction::Sub:
507   case Instruction::FSub: return bitc::BINOP_SUB;
508   case Instruction::Mul:
509   case Instruction::FMul: return bitc::BINOP_MUL;
510   case Instruction::UDiv: return bitc::BINOP_UDIV;
511   case Instruction::FDiv:
512   case Instruction::SDiv: return bitc::BINOP_SDIV;
513   case Instruction::URem: return bitc::BINOP_UREM;
514   case Instruction::FRem:
515   case Instruction::SRem: return bitc::BINOP_SREM;
516   case Instruction::Shl:  return bitc::BINOP_SHL;
517   case Instruction::LShr: return bitc::BINOP_LSHR;
518   case Instruction::AShr: return bitc::BINOP_ASHR;
519   case Instruction::And:  return bitc::BINOP_AND;
520   case Instruction::Or:   return bitc::BINOP_OR;
521   case Instruction::Xor:  return bitc::BINOP_XOR;
522   }
523 }
524 
525 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
526   switch (Op) {
527   default: llvm_unreachable("Unknown RMW operation!");
528   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
529   case AtomicRMWInst::Add: return bitc::RMW_ADD;
530   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
531   case AtomicRMWInst::And: return bitc::RMW_AND;
532   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
533   case AtomicRMWInst::Or: return bitc::RMW_OR;
534   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
535   case AtomicRMWInst::Max: return bitc::RMW_MAX;
536   case AtomicRMWInst::Min: return bitc::RMW_MIN;
537   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
538   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
539   }
540 }
541 
542 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
543   switch (Ordering) {
544   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
545   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
546   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
547   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
548   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
549   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
550   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
551   }
552   llvm_unreachable("Invalid ordering");
553 }
554 
555 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
556                               StringRef Str, unsigned AbbrevToUse) {
557   SmallVector<unsigned, 64> Vals;
558 
559   // Code: [strchar x N]
560   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
561     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
562       AbbrevToUse = 0;
563     Vals.push_back(Str[i]);
564   }
565 
566   // Emit the finished record.
567   Stream.EmitRecord(Code, Vals, AbbrevToUse);
568 }
569 
570 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
571   switch (Kind) {
572   case Attribute::Alignment:
573     return bitc::ATTR_KIND_ALIGNMENT;
574   case Attribute::AllocSize:
575     return bitc::ATTR_KIND_ALLOC_SIZE;
576   case Attribute::AlwaysInline:
577     return bitc::ATTR_KIND_ALWAYS_INLINE;
578   case Attribute::ArgMemOnly:
579     return bitc::ATTR_KIND_ARGMEMONLY;
580   case Attribute::Builtin:
581     return bitc::ATTR_KIND_BUILTIN;
582   case Attribute::ByVal:
583     return bitc::ATTR_KIND_BY_VAL;
584   case Attribute::Convergent:
585     return bitc::ATTR_KIND_CONVERGENT;
586   case Attribute::InAlloca:
587     return bitc::ATTR_KIND_IN_ALLOCA;
588   case Attribute::Cold:
589     return bitc::ATTR_KIND_COLD;
590   case Attribute::InaccessibleMemOnly:
591     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
592   case Attribute::InaccessibleMemOrArgMemOnly:
593     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
594   case Attribute::InlineHint:
595     return bitc::ATTR_KIND_INLINE_HINT;
596   case Attribute::InReg:
597     return bitc::ATTR_KIND_IN_REG;
598   case Attribute::JumpTable:
599     return bitc::ATTR_KIND_JUMP_TABLE;
600   case Attribute::MinSize:
601     return bitc::ATTR_KIND_MIN_SIZE;
602   case Attribute::Naked:
603     return bitc::ATTR_KIND_NAKED;
604   case Attribute::Nest:
605     return bitc::ATTR_KIND_NEST;
606   case Attribute::NoAlias:
607     return bitc::ATTR_KIND_NO_ALIAS;
608   case Attribute::NoBuiltin:
609     return bitc::ATTR_KIND_NO_BUILTIN;
610   case Attribute::NoCapture:
611     return bitc::ATTR_KIND_NO_CAPTURE;
612   case Attribute::NoDuplicate:
613     return bitc::ATTR_KIND_NO_DUPLICATE;
614   case Attribute::NoImplicitFloat:
615     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
616   case Attribute::NoInline:
617     return bitc::ATTR_KIND_NO_INLINE;
618   case Attribute::NoRecurse:
619     return bitc::ATTR_KIND_NO_RECURSE;
620   case Attribute::NonLazyBind:
621     return bitc::ATTR_KIND_NON_LAZY_BIND;
622   case Attribute::NonNull:
623     return bitc::ATTR_KIND_NON_NULL;
624   case Attribute::Dereferenceable:
625     return bitc::ATTR_KIND_DEREFERENCEABLE;
626   case Attribute::DereferenceableOrNull:
627     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
628   case Attribute::NoRedZone:
629     return bitc::ATTR_KIND_NO_RED_ZONE;
630   case Attribute::NoReturn:
631     return bitc::ATTR_KIND_NO_RETURN;
632   case Attribute::NoUnwind:
633     return bitc::ATTR_KIND_NO_UNWIND;
634   case Attribute::OptimizeForSize:
635     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
636   case Attribute::OptimizeNone:
637     return bitc::ATTR_KIND_OPTIMIZE_NONE;
638   case Attribute::ReadNone:
639     return bitc::ATTR_KIND_READ_NONE;
640   case Attribute::ReadOnly:
641     return bitc::ATTR_KIND_READ_ONLY;
642   case Attribute::Returned:
643     return bitc::ATTR_KIND_RETURNED;
644   case Attribute::ReturnsTwice:
645     return bitc::ATTR_KIND_RETURNS_TWICE;
646   case Attribute::SExt:
647     return bitc::ATTR_KIND_S_EXT;
648   case Attribute::Speculatable:
649     return bitc::ATTR_KIND_SPECULATABLE;
650   case Attribute::StackAlignment:
651     return bitc::ATTR_KIND_STACK_ALIGNMENT;
652   case Attribute::StackProtect:
653     return bitc::ATTR_KIND_STACK_PROTECT;
654   case Attribute::StackProtectReq:
655     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
656   case Attribute::StackProtectStrong:
657     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
658   case Attribute::SafeStack:
659     return bitc::ATTR_KIND_SAFESTACK;
660   case Attribute::StrictFP:
661     return bitc::ATTR_KIND_STRICT_FP;
662   case Attribute::StructRet:
663     return bitc::ATTR_KIND_STRUCT_RET;
664   case Attribute::SanitizeAddress:
665     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
666   case Attribute::SanitizeThread:
667     return bitc::ATTR_KIND_SANITIZE_THREAD;
668   case Attribute::SanitizeMemory:
669     return bitc::ATTR_KIND_SANITIZE_MEMORY;
670   case Attribute::SwiftError:
671     return bitc::ATTR_KIND_SWIFT_ERROR;
672   case Attribute::SwiftSelf:
673     return bitc::ATTR_KIND_SWIFT_SELF;
674   case Attribute::UWTable:
675     return bitc::ATTR_KIND_UW_TABLE;
676   case Attribute::WriteOnly:
677     return bitc::ATTR_KIND_WRITEONLY;
678   case Attribute::ZExt:
679     return bitc::ATTR_KIND_Z_EXT;
680   case Attribute::EndAttrKinds:
681     llvm_unreachable("Can not encode end-attribute kinds marker.");
682   case Attribute::None:
683     llvm_unreachable("Can not encode none-attribute.");
684   }
685 
686   llvm_unreachable("Trying to encode unknown attribute");
687 }
688 
689 void ModuleBitcodeWriter::writeAttributeGroupTable() {
690   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
691       VE.getAttributeGroups();
692   if (AttrGrps.empty()) return;
693 
694   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
695 
696   SmallVector<uint64_t, 64> Record;
697   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
698     unsigned AttrListIndex = Pair.first;
699     AttributeSet AS = Pair.second;
700     Record.push_back(VE.getAttributeGroupID(Pair));
701     Record.push_back(AttrListIndex);
702 
703     for (Attribute Attr : AS) {
704       if (Attr.isEnumAttribute()) {
705         Record.push_back(0);
706         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
707       } else if (Attr.isIntAttribute()) {
708         Record.push_back(1);
709         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
710         Record.push_back(Attr.getValueAsInt());
711       } else {
712         StringRef Kind = Attr.getKindAsString();
713         StringRef Val = Attr.getValueAsString();
714 
715         Record.push_back(Val.empty() ? 3 : 4);
716         Record.append(Kind.begin(), Kind.end());
717         Record.push_back(0);
718         if (!Val.empty()) {
719           Record.append(Val.begin(), Val.end());
720           Record.push_back(0);
721         }
722       }
723     }
724 
725     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
726     Record.clear();
727   }
728 
729   Stream.ExitBlock();
730 }
731 
732 void ModuleBitcodeWriter::writeAttributeTable() {
733   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
734   if (Attrs.empty()) return;
735 
736   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
737 
738   SmallVector<uint64_t, 64> Record;
739   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
740     AttributeList AL = Attrs[i];
741     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
742       AttributeSet AS = AL.getAttributes(i);
743       if (AS.hasAttributes())
744         Record.push_back(VE.getAttributeGroupID({i, AS}));
745     }
746 
747     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
748     Record.clear();
749   }
750 
751   Stream.ExitBlock();
752 }
753 
754 /// WriteTypeTable - Write out the type table for a module.
755 void ModuleBitcodeWriter::writeTypeTable() {
756   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
757 
758   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
759   SmallVector<uint64_t, 64> TypeVals;
760 
761   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
762 
763   // Abbrev for TYPE_CODE_POINTER.
764   auto Abbv = std::make_shared<BitCodeAbbrev>();
765   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
766   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
767   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
768   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
769 
770   // Abbrev for TYPE_CODE_FUNCTION.
771   Abbv = std::make_shared<BitCodeAbbrev>();
772   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
773   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
774   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
775   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
776   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
777 
778   // Abbrev for TYPE_CODE_STRUCT_ANON.
779   Abbv = std::make_shared<BitCodeAbbrev>();
780   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
781   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
782   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
783   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
784   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
785 
786   // Abbrev for TYPE_CODE_STRUCT_NAME.
787   Abbv = std::make_shared<BitCodeAbbrev>();
788   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
789   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
790   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
791   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
792 
793   // Abbrev for TYPE_CODE_STRUCT_NAMED.
794   Abbv = std::make_shared<BitCodeAbbrev>();
795   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
796   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
797   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
798   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
799   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
800 
801   // Abbrev for TYPE_CODE_ARRAY.
802   Abbv = std::make_shared<BitCodeAbbrev>();
803   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
804   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
805   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
806   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
807 
808   // Emit an entry count so the reader can reserve space.
809   TypeVals.push_back(TypeList.size());
810   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
811   TypeVals.clear();
812 
813   // Loop over all of the types, emitting each in turn.
814   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
815     Type *T = TypeList[i];
816     int AbbrevToUse = 0;
817     unsigned Code = 0;
818 
819     switch (T->getTypeID()) {
820     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
821     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
822     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
823     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
824     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
825     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
826     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
827     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
828     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
829     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
830     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
831     case Type::IntegerTyID:
832       // INTEGER: [width]
833       Code = bitc::TYPE_CODE_INTEGER;
834       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
835       break;
836     case Type::PointerTyID: {
837       PointerType *PTy = cast<PointerType>(T);
838       // POINTER: [pointee type, address space]
839       Code = bitc::TYPE_CODE_POINTER;
840       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
841       unsigned AddressSpace = PTy->getAddressSpace();
842       TypeVals.push_back(AddressSpace);
843       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
844       break;
845     }
846     case Type::FunctionTyID: {
847       FunctionType *FT = cast<FunctionType>(T);
848       // FUNCTION: [isvararg, retty, paramty x N]
849       Code = bitc::TYPE_CODE_FUNCTION;
850       TypeVals.push_back(FT->isVarArg());
851       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
852       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
853         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
854       AbbrevToUse = FunctionAbbrev;
855       break;
856     }
857     case Type::StructTyID: {
858       StructType *ST = cast<StructType>(T);
859       // STRUCT: [ispacked, eltty x N]
860       TypeVals.push_back(ST->isPacked());
861       // Output all of the element types.
862       for (StructType::element_iterator I = ST->element_begin(),
863            E = ST->element_end(); I != E; ++I)
864         TypeVals.push_back(VE.getTypeID(*I));
865 
866       if (ST->isLiteral()) {
867         Code = bitc::TYPE_CODE_STRUCT_ANON;
868         AbbrevToUse = StructAnonAbbrev;
869       } else {
870         if (ST->isOpaque()) {
871           Code = bitc::TYPE_CODE_OPAQUE;
872         } else {
873           Code = bitc::TYPE_CODE_STRUCT_NAMED;
874           AbbrevToUse = StructNamedAbbrev;
875         }
876 
877         // Emit the name if it is present.
878         if (!ST->getName().empty())
879           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
880                             StructNameAbbrev);
881       }
882       break;
883     }
884     case Type::ArrayTyID: {
885       ArrayType *AT = cast<ArrayType>(T);
886       // ARRAY: [numelts, eltty]
887       Code = bitc::TYPE_CODE_ARRAY;
888       TypeVals.push_back(AT->getNumElements());
889       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
890       AbbrevToUse = ArrayAbbrev;
891       break;
892     }
893     case Type::VectorTyID: {
894       VectorType *VT = cast<VectorType>(T);
895       // VECTOR [numelts, eltty]
896       Code = bitc::TYPE_CODE_VECTOR;
897       TypeVals.push_back(VT->getNumElements());
898       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
899       break;
900     }
901     }
902 
903     // Emit the finished record.
904     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
905     TypeVals.clear();
906   }
907 
908   Stream.ExitBlock();
909 }
910 
911 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
912   switch (Linkage) {
913   case GlobalValue::ExternalLinkage:
914     return 0;
915   case GlobalValue::WeakAnyLinkage:
916     return 16;
917   case GlobalValue::AppendingLinkage:
918     return 2;
919   case GlobalValue::InternalLinkage:
920     return 3;
921   case GlobalValue::LinkOnceAnyLinkage:
922     return 18;
923   case GlobalValue::ExternalWeakLinkage:
924     return 7;
925   case GlobalValue::CommonLinkage:
926     return 8;
927   case GlobalValue::PrivateLinkage:
928     return 9;
929   case GlobalValue::WeakODRLinkage:
930     return 17;
931   case GlobalValue::LinkOnceODRLinkage:
932     return 19;
933   case GlobalValue::AvailableExternallyLinkage:
934     return 12;
935   }
936   llvm_unreachable("Invalid linkage");
937 }
938 
939 static unsigned getEncodedLinkage(const GlobalValue &GV) {
940   return getEncodedLinkage(GV.getLinkage());
941 }
942 
943 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
944   uint64_t RawFlags = 0;
945   RawFlags |= Flags.ReadNone;
946   RawFlags |= (Flags.ReadOnly << 1);
947   RawFlags |= (Flags.NoRecurse << 2);
948   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
949   return RawFlags;
950 }
951 
952 // Decode the flags for GlobalValue in the summary
953 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
954   uint64_t RawFlags = 0;
955 
956   RawFlags |= Flags.NotEligibleToImport; // bool
957   RawFlags |= (Flags.Live << 1);
958   // Linkage don't need to be remapped at that time for the summary. Any future
959   // change to the getEncodedLinkage() function will need to be taken into
960   // account here as well.
961   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
962 
963   return RawFlags;
964 }
965 
966 static unsigned getEncodedVisibility(const GlobalValue &GV) {
967   switch (GV.getVisibility()) {
968   case GlobalValue::DefaultVisibility:   return 0;
969   case GlobalValue::HiddenVisibility:    return 1;
970   case GlobalValue::ProtectedVisibility: return 2;
971   }
972   llvm_unreachable("Invalid visibility");
973 }
974 
975 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
976   switch (GV.getDLLStorageClass()) {
977   case GlobalValue::DefaultStorageClass:   return 0;
978   case GlobalValue::DLLImportStorageClass: return 1;
979   case GlobalValue::DLLExportStorageClass: return 2;
980   }
981   llvm_unreachable("Invalid DLL storage class");
982 }
983 
984 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
985   switch (GV.getThreadLocalMode()) {
986     case GlobalVariable::NotThreadLocal:         return 0;
987     case GlobalVariable::GeneralDynamicTLSModel: return 1;
988     case GlobalVariable::LocalDynamicTLSModel:   return 2;
989     case GlobalVariable::InitialExecTLSModel:    return 3;
990     case GlobalVariable::LocalExecTLSModel:      return 4;
991   }
992   llvm_unreachable("Invalid TLS model");
993 }
994 
995 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
996   switch (C.getSelectionKind()) {
997   case Comdat::Any:
998     return bitc::COMDAT_SELECTION_KIND_ANY;
999   case Comdat::ExactMatch:
1000     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1001   case Comdat::Largest:
1002     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1003   case Comdat::NoDuplicates:
1004     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1005   case Comdat::SameSize:
1006     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1007   }
1008   llvm_unreachable("Invalid selection kind");
1009 }
1010 
1011 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1012   switch (GV.getUnnamedAddr()) {
1013   case GlobalValue::UnnamedAddr::None:   return 0;
1014   case GlobalValue::UnnamedAddr::Local:  return 2;
1015   case GlobalValue::UnnamedAddr::Global: return 1;
1016   }
1017   llvm_unreachable("Invalid unnamed_addr");
1018 }
1019 
1020 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1021   if (GenerateHash)
1022     Hasher.update(Str);
1023   return StrtabBuilder.add(Str);
1024 }
1025 
1026 void ModuleBitcodeWriter::writeComdats() {
1027   SmallVector<unsigned, 64> Vals;
1028   for (const Comdat *C : VE.getComdats()) {
1029     // COMDAT: [strtab offset, strtab size, selection_kind]
1030     Vals.push_back(addToStrtab(C->getName()));
1031     Vals.push_back(C->getName().size());
1032     Vals.push_back(getEncodedComdatSelectionKind(*C));
1033     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1034     Vals.clear();
1035   }
1036 }
1037 
1038 /// Write a record that will eventually hold the word offset of the
1039 /// module-level VST. For now the offset is 0, which will be backpatched
1040 /// after the real VST is written. Saves the bit offset to backpatch.
1041 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1042   // Write a placeholder value in for the offset of the real VST,
1043   // which is written after the function blocks so that it can include
1044   // the offset of each function. The placeholder offset will be
1045   // updated when the real VST is written.
1046   auto Abbv = std::make_shared<BitCodeAbbrev>();
1047   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1048   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1049   // hold the real VST offset. Must use fixed instead of VBR as we don't
1050   // know how many VBR chunks to reserve ahead of time.
1051   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1052   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1053 
1054   // Emit the placeholder
1055   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1056   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1057 
1058   // Compute and save the bit offset to the placeholder, which will be
1059   // patched when the real VST is written. We can simply subtract the 32-bit
1060   // fixed size from the current bit number to get the location to backpatch.
1061   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1062 }
1063 
1064 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1065 
1066 /// Determine the encoding to use for the given string name and length.
1067 static StringEncoding getStringEncoding(StringRef Str) {
1068   bool isChar6 = true;
1069   for (char C : Str) {
1070     if (isChar6)
1071       isChar6 = BitCodeAbbrevOp::isChar6(C);
1072     if ((unsigned char)C & 128)
1073       // don't bother scanning the rest.
1074       return SE_Fixed8;
1075   }
1076   if (isChar6)
1077     return SE_Char6;
1078   return SE_Fixed7;
1079 }
1080 
1081 /// Emit top-level description of module, including target triple, inline asm,
1082 /// descriptors for global variables, and function prototype info.
1083 /// Returns the bit offset to backpatch with the location of the real VST.
1084 void ModuleBitcodeWriter::writeModuleInfo() {
1085   // Emit various pieces of data attached to a module.
1086   if (!M.getTargetTriple().empty())
1087     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1088                       0 /*TODO*/);
1089   const std::string &DL = M.getDataLayoutStr();
1090   if (!DL.empty())
1091     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1092   if (!M.getModuleInlineAsm().empty())
1093     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1094                       0 /*TODO*/);
1095 
1096   // Emit information about sections and GC, computing how many there are. Also
1097   // compute the maximum alignment value.
1098   std::map<std::string, unsigned> SectionMap;
1099   std::map<std::string, unsigned> GCMap;
1100   unsigned MaxAlignment = 0;
1101   unsigned MaxGlobalType = 0;
1102   for (const GlobalValue &GV : M.globals()) {
1103     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1104     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1105     if (GV.hasSection()) {
1106       // Give section names unique ID's.
1107       unsigned &Entry = SectionMap[GV.getSection()];
1108       if (!Entry) {
1109         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1110                           0 /*TODO*/);
1111         Entry = SectionMap.size();
1112       }
1113     }
1114   }
1115   for (const Function &F : M) {
1116     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1117     if (F.hasSection()) {
1118       // Give section names unique ID's.
1119       unsigned &Entry = SectionMap[F.getSection()];
1120       if (!Entry) {
1121         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1122                           0 /*TODO*/);
1123         Entry = SectionMap.size();
1124       }
1125     }
1126     if (F.hasGC()) {
1127       // Same for GC names.
1128       unsigned &Entry = GCMap[F.getGC()];
1129       if (!Entry) {
1130         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1131                           0 /*TODO*/);
1132         Entry = GCMap.size();
1133       }
1134     }
1135   }
1136 
1137   // Emit abbrev for globals, now that we know # sections and max alignment.
1138   unsigned SimpleGVarAbbrev = 0;
1139   if (!M.global_empty()) {
1140     // Add an abbrev for common globals with no visibility or thread localness.
1141     auto Abbv = std::make_shared<BitCodeAbbrev>();
1142     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1143     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1144     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1146                               Log2_32_Ceil(MaxGlobalType+1)));
1147     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1148                                                            //| explicitType << 1
1149                                                            //| constant
1150     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1151     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1152     if (MaxAlignment == 0)                                 // Alignment.
1153       Abbv->Add(BitCodeAbbrevOp(0));
1154     else {
1155       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1156       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1157                                Log2_32_Ceil(MaxEncAlignment+1)));
1158     }
1159     if (SectionMap.empty())                                    // Section.
1160       Abbv->Add(BitCodeAbbrevOp(0));
1161     else
1162       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1163                                Log2_32_Ceil(SectionMap.size()+1)));
1164     // Don't bother emitting vis + thread local.
1165     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1166   }
1167 
1168   SmallVector<unsigned, 64> Vals;
1169   // Emit the module's source file name.
1170   {
1171     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1172     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1173     if (Bits == SE_Char6)
1174       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1175     else if (Bits == SE_Fixed7)
1176       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1177 
1178     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1179     auto Abbv = std::make_shared<BitCodeAbbrev>();
1180     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1181     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1182     Abbv->Add(AbbrevOpToUse);
1183     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1184 
1185     for (const auto P : M.getSourceFileName())
1186       Vals.push_back((unsigned char)P);
1187 
1188     // Emit the finished record.
1189     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1190     Vals.clear();
1191   }
1192 
1193   // Emit the global variable information.
1194   for (const GlobalVariable &GV : M.globals()) {
1195     unsigned AbbrevToUse = 0;
1196 
1197     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1198     //             linkage, alignment, section, visibility, threadlocal,
1199     //             unnamed_addr, externally_initialized, dllstorageclass,
1200     //             comdat, attributes, DSO_Local]
1201     Vals.push_back(addToStrtab(GV.getName()));
1202     Vals.push_back(GV.getName().size());
1203     Vals.push_back(VE.getTypeID(GV.getValueType()));
1204     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1205     Vals.push_back(GV.isDeclaration() ? 0 :
1206                    (VE.getValueID(GV.getInitializer()) + 1));
1207     Vals.push_back(getEncodedLinkage(GV));
1208     Vals.push_back(Log2_32(GV.getAlignment())+1);
1209     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1210     if (GV.isThreadLocal() ||
1211         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1212         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1213         GV.isExternallyInitialized() ||
1214         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1215         GV.hasComdat() ||
1216         GV.hasAttributes() ||
1217         GV.isDSOLocal()) {
1218       Vals.push_back(getEncodedVisibility(GV));
1219       Vals.push_back(getEncodedThreadLocalMode(GV));
1220       Vals.push_back(getEncodedUnnamedAddr(GV));
1221       Vals.push_back(GV.isExternallyInitialized());
1222       Vals.push_back(getEncodedDLLStorageClass(GV));
1223       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1224 
1225       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1226       Vals.push_back(VE.getAttributeListID(AL));
1227 
1228       Vals.push_back(GV.isDSOLocal());
1229     } else {
1230       AbbrevToUse = SimpleGVarAbbrev;
1231     }
1232 
1233     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1234     Vals.clear();
1235   }
1236 
1237   // Emit the function proto information.
1238   for (const Function &F : M) {
1239     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1240     //             linkage, paramattrs, alignment, section, visibility, gc,
1241     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1242     //             prefixdata, personalityfn, DSO_Local]
1243     Vals.push_back(addToStrtab(F.getName()));
1244     Vals.push_back(F.getName().size());
1245     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1246     Vals.push_back(F.getCallingConv());
1247     Vals.push_back(F.isDeclaration());
1248     Vals.push_back(getEncodedLinkage(F));
1249     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1250     Vals.push_back(Log2_32(F.getAlignment())+1);
1251     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1252     Vals.push_back(getEncodedVisibility(F));
1253     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1254     Vals.push_back(getEncodedUnnamedAddr(F));
1255     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1256                                        : 0);
1257     Vals.push_back(getEncodedDLLStorageClass(F));
1258     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1259     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1260                                      : 0);
1261     Vals.push_back(
1262         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1263 
1264     Vals.push_back(F.isDSOLocal());
1265     unsigned AbbrevToUse = 0;
1266     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1267     Vals.clear();
1268   }
1269 
1270   // Emit the alias information.
1271   for (const GlobalAlias &A : M.aliases()) {
1272     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1273     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1274     //         DSO_Local]
1275     Vals.push_back(addToStrtab(A.getName()));
1276     Vals.push_back(A.getName().size());
1277     Vals.push_back(VE.getTypeID(A.getValueType()));
1278     Vals.push_back(A.getType()->getAddressSpace());
1279     Vals.push_back(VE.getValueID(A.getAliasee()));
1280     Vals.push_back(getEncodedLinkage(A));
1281     Vals.push_back(getEncodedVisibility(A));
1282     Vals.push_back(getEncodedDLLStorageClass(A));
1283     Vals.push_back(getEncodedThreadLocalMode(A));
1284     Vals.push_back(getEncodedUnnamedAddr(A));
1285     Vals.push_back(A.isDSOLocal());
1286 
1287     unsigned AbbrevToUse = 0;
1288     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1289     Vals.clear();
1290   }
1291 
1292   // Emit the ifunc information.
1293   for (const GlobalIFunc &I : M.ifuncs()) {
1294     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1295     //         val#, linkage, visibility]
1296     Vals.push_back(addToStrtab(I.getName()));
1297     Vals.push_back(I.getName().size());
1298     Vals.push_back(VE.getTypeID(I.getValueType()));
1299     Vals.push_back(I.getType()->getAddressSpace());
1300     Vals.push_back(VE.getValueID(I.getResolver()));
1301     Vals.push_back(getEncodedLinkage(I));
1302     Vals.push_back(getEncodedVisibility(I));
1303     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1304     Vals.clear();
1305   }
1306 
1307   writeValueSymbolTableForwardDecl();
1308 }
1309 
1310 static uint64_t getOptimizationFlags(const Value *V) {
1311   uint64_t Flags = 0;
1312 
1313   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1314     if (OBO->hasNoSignedWrap())
1315       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1316     if (OBO->hasNoUnsignedWrap())
1317       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1318   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1319     if (PEO->isExact())
1320       Flags |= 1 << bitc::PEO_EXACT;
1321   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1322     if (FPMO->hasUnsafeAlgebra())
1323       Flags |= FastMathFlags::UnsafeAlgebra;
1324     if (FPMO->hasNoNaNs())
1325       Flags |= FastMathFlags::NoNaNs;
1326     if (FPMO->hasNoInfs())
1327       Flags |= FastMathFlags::NoInfs;
1328     if (FPMO->hasNoSignedZeros())
1329       Flags |= FastMathFlags::NoSignedZeros;
1330     if (FPMO->hasAllowReciprocal())
1331       Flags |= FastMathFlags::AllowReciprocal;
1332     if (FPMO->hasAllowContract())
1333       Flags |= FastMathFlags::AllowContract;
1334   }
1335 
1336   return Flags;
1337 }
1338 
1339 void ModuleBitcodeWriter::writeValueAsMetadata(
1340     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1341   // Mimic an MDNode with a value as one operand.
1342   Value *V = MD->getValue();
1343   Record.push_back(VE.getTypeID(V->getType()));
1344   Record.push_back(VE.getValueID(V));
1345   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1346   Record.clear();
1347 }
1348 
1349 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1350                                        SmallVectorImpl<uint64_t> &Record,
1351                                        unsigned Abbrev) {
1352   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1353     Metadata *MD = N->getOperand(i);
1354     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1355            "Unexpected function-local metadata");
1356     Record.push_back(VE.getMetadataOrNullID(MD));
1357   }
1358   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1359                                     : bitc::METADATA_NODE,
1360                     Record, Abbrev);
1361   Record.clear();
1362 }
1363 
1364 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1365   // Assume the column is usually under 128, and always output the inlined-at
1366   // location (it's never more expensive than building an array size 1).
1367   auto Abbv = std::make_shared<BitCodeAbbrev>();
1368   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1369   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1370   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1374   return Stream.EmitAbbrev(std::move(Abbv));
1375 }
1376 
1377 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1378                                           SmallVectorImpl<uint64_t> &Record,
1379                                           unsigned &Abbrev) {
1380   if (!Abbrev)
1381     Abbrev = createDILocationAbbrev();
1382 
1383   Record.push_back(N->isDistinct());
1384   Record.push_back(N->getLine());
1385   Record.push_back(N->getColumn());
1386   Record.push_back(VE.getMetadataID(N->getScope()));
1387   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1388 
1389   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1390   Record.clear();
1391 }
1392 
1393 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1394   // Assume the column is usually under 128, and always output the inlined-at
1395   // location (it's never more expensive than building an array size 1).
1396   auto Abbv = std::make_shared<BitCodeAbbrev>();
1397   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1399   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1400   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1401   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1402   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1403   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1404   return Stream.EmitAbbrev(std::move(Abbv));
1405 }
1406 
1407 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1408                                              SmallVectorImpl<uint64_t> &Record,
1409                                              unsigned &Abbrev) {
1410   if (!Abbrev)
1411     Abbrev = createGenericDINodeAbbrev();
1412 
1413   Record.push_back(N->isDistinct());
1414   Record.push_back(N->getTag());
1415   Record.push_back(0); // Per-tag version field; unused for now.
1416 
1417   for (auto &I : N->operands())
1418     Record.push_back(VE.getMetadataOrNullID(I));
1419 
1420   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1421   Record.clear();
1422 }
1423 
1424 static uint64_t rotateSign(int64_t I) {
1425   uint64_t U = I;
1426   return I < 0 ? ~(U << 1) : U << 1;
1427 }
1428 
1429 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1430                                           SmallVectorImpl<uint64_t> &Record,
1431                                           unsigned Abbrev) {
1432   Record.push_back(N->isDistinct());
1433   Record.push_back(N->getCount());
1434   Record.push_back(rotateSign(N->getLowerBound()));
1435 
1436   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1437   Record.clear();
1438 }
1439 
1440 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1441                                             SmallVectorImpl<uint64_t> &Record,
1442                                             unsigned Abbrev) {
1443   Record.push_back(N->isDistinct());
1444   Record.push_back(rotateSign(N->getValue()));
1445   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1446 
1447   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1448   Record.clear();
1449 }
1450 
1451 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1452                                            SmallVectorImpl<uint64_t> &Record,
1453                                            unsigned Abbrev) {
1454   Record.push_back(N->isDistinct());
1455   Record.push_back(N->getTag());
1456   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1457   Record.push_back(N->getSizeInBits());
1458   Record.push_back(N->getAlignInBits());
1459   Record.push_back(N->getEncoding());
1460 
1461   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1462   Record.clear();
1463 }
1464 
1465 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1466                                              SmallVectorImpl<uint64_t> &Record,
1467                                              unsigned Abbrev) {
1468   Record.push_back(N->isDistinct());
1469   Record.push_back(N->getTag());
1470   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1471   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1472   Record.push_back(N->getLine());
1473   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1474   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1475   Record.push_back(N->getSizeInBits());
1476   Record.push_back(N->getAlignInBits());
1477   Record.push_back(N->getOffsetInBits());
1478   Record.push_back(N->getFlags());
1479   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1480 
1481   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1482   // that there is no DWARF address space associated with DIDerivedType.
1483   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1484     Record.push_back(*DWARFAddressSpace + 1);
1485   else
1486     Record.push_back(0);
1487 
1488   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1489   Record.clear();
1490 }
1491 
1492 void ModuleBitcodeWriter::writeDICompositeType(
1493     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1494     unsigned Abbrev) {
1495   const unsigned IsNotUsedInOldTypeRef = 0x2;
1496   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1497   Record.push_back(N->getTag());
1498   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1499   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1500   Record.push_back(N->getLine());
1501   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1502   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1503   Record.push_back(N->getSizeInBits());
1504   Record.push_back(N->getAlignInBits());
1505   Record.push_back(N->getOffsetInBits());
1506   Record.push_back(N->getFlags());
1507   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1508   Record.push_back(N->getRuntimeLang());
1509   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1510   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1511   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1512 
1513   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1514   Record.clear();
1515 }
1516 
1517 void ModuleBitcodeWriter::writeDISubroutineType(
1518     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1519     unsigned Abbrev) {
1520   const unsigned HasNoOldTypeRefs = 0x2;
1521   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1522   Record.push_back(N->getFlags());
1523   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1524   Record.push_back(N->getCC());
1525 
1526   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1527   Record.clear();
1528 }
1529 
1530 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1531                                       SmallVectorImpl<uint64_t> &Record,
1532                                       unsigned Abbrev) {
1533   Record.push_back(N->isDistinct());
1534   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1535   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1536   Record.push_back(N->getChecksumKind());
1537   Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()));
1538 
1539   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1540   Record.clear();
1541 }
1542 
1543 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1544                                              SmallVectorImpl<uint64_t> &Record,
1545                                              unsigned Abbrev) {
1546   assert(N->isDistinct() && "Expected distinct compile units");
1547   Record.push_back(/* IsDistinct */ true);
1548   Record.push_back(N->getSourceLanguage());
1549   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1550   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1551   Record.push_back(N->isOptimized());
1552   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1553   Record.push_back(N->getRuntimeVersion());
1554   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1555   Record.push_back(N->getEmissionKind());
1556   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1557   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1558   Record.push_back(/* subprograms */ 0);
1559   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1560   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1561   Record.push_back(N->getDWOId());
1562   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1563   Record.push_back(N->getSplitDebugInlining());
1564   Record.push_back(N->getDebugInfoForProfiling());
1565   Record.push_back(N->getGnuPubnames());
1566 
1567   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1568   Record.clear();
1569 }
1570 
1571 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1572                                             SmallVectorImpl<uint64_t> &Record,
1573                                             unsigned Abbrev) {
1574   uint64_t HasUnitFlag = 1 << 1;
1575   Record.push_back(N->isDistinct() | HasUnitFlag);
1576   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1577   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1578   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1579   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1580   Record.push_back(N->getLine());
1581   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1582   Record.push_back(N->isLocalToUnit());
1583   Record.push_back(N->isDefinition());
1584   Record.push_back(N->getScopeLine());
1585   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1586   Record.push_back(N->getVirtuality());
1587   Record.push_back(N->getVirtualIndex());
1588   Record.push_back(N->getFlags());
1589   Record.push_back(N->isOptimized());
1590   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1591   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1592   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1593   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1594   Record.push_back(N->getThisAdjustment());
1595   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1596 
1597   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1598   Record.clear();
1599 }
1600 
1601 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1602                                               SmallVectorImpl<uint64_t> &Record,
1603                                               unsigned Abbrev) {
1604   Record.push_back(N->isDistinct());
1605   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1606   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1607   Record.push_back(N->getLine());
1608   Record.push_back(N->getColumn());
1609 
1610   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1611   Record.clear();
1612 }
1613 
1614 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1615     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1616     unsigned Abbrev) {
1617   Record.push_back(N->isDistinct());
1618   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1619   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1620   Record.push_back(N->getDiscriminator());
1621 
1622   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1623   Record.clear();
1624 }
1625 
1626 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1627                                            SmallVectorImpl<uint64_t> &Record,
1628                                            unsigned Abbrev) {
1629   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1630   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1631   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1632 
1633   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1634   Record.clear();
1635 }
1636 
1637 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1638                                        SmallVectorImpl<uint64_t> &Record,
1639                                        unsigned Abbrev) {
1640   Record.push_back(N->isDistinct());
1641   Record.push_back(N->getMacinfoType());
1642   Record.push_back(N->getLine());
1643   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1644   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1645 
1646   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1647   Record.clear();
1648 }
1649 
1650 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1651                                            SmallVectorImpl<uint64_t> &Record,
1652                                            unsigned Abbrev) {
1653   Record.push_back(N->isDistinct());
1654   Record.push_back(N->getMacinfoType());
1655   Record.push_back(N->getLine());
1656   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1657   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1658 
1659   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1660   Record.clear();
1661 }
1662 
1663 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1664                                         SmallVectorImpl<uint64_t> &Record,
1665                                         unsigned Abbrev) {
1666   Record.push_back(N->isDistinct());
1667   for (auto &I : N->operands())
1668     Record.push_back(VE.getMetadataOrNullID(I));
1669 
1670   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1671   Record.clear();
1672 }
1673 
1674 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1675     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1676     unsigned Abbrev) {
1677   Record.push_back(N->isDistinct());
1678   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1679   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1680 
1681   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1682   Record.clear();
1683 }
1684 
1685 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1686     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1687     unsigned Abbrev) {
1688   Record.push_back(N->isDistinct());
1689   Record.push_back(N->getTag());
1690   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1691   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1692   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1693 
1694   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1695   Record.clear();
1696 }
1697 
1698 void ModuleBitcodeWriter::writeDIGlobalVariable(
1699     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1700     unsigned Abbrev) {
1701   const uint64_t Version = 1 << 1;
1702   Record.push_back((uint64_t)N->isDistinct() | Version);
1703   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1704   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1705   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1706   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1707   Record.push_back(N->getLine());
1708   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1709   Record.push_back(N->isLocalToUnit());
1710   Record.push_back(N->isDefinition());
1711   Record.push_back(/* expr */ 0);
1712   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1713   Record.push_back(N->getAlignInBits());
1714 
1715   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1716   Record.clear();
1717 }
1718 
1719 void ModuleBitcodeWriter::writeDILocalVariable(
1720     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1721     unsigned Abbrev) {
1722   // In order to support all possible bitcode formats in BitcodeReader we need
1723   // to distinguish the following cases:
1724   // 1) Record has no artificial tag (Record[1]),
1725   //   has no obsolete inlinedAt field (Record[9]).
1726   //   In this case Record size will be 8, HasAlignment flag is false.
1727   // 2) Record has artificial tag (Record[1]),
1728   //   has no obsolete inlignedAt field (Record[9]).
1729   //   In this case Record size will be 9, HasAlignment flag is false.
1730   // 3) Record has both artificial tag (Record[1]) and
1731   //   obsolete inlignedAt field (Record[9]).
1732   //   In this case Record size will be 10, HasAlignment flag is false.
1733   // 4) Record has neither artificial tag, nor inlignedAt field, but
1734   //   HasAlignment flag is true and Record[8] contains alignment value.
1735   const uint64_t HasAlignmentFlag = 1 << 1;
1736   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1737   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1738   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1739   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1740   Record.push_back(N->getLine());
1741   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1742   Record.push_back(N->getArg());
1743   Record.push_back(N->getFlags());
1744   Record.push_back(N->getAlignInBits());
1745 
1746   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1747   Record.clear();
1748 }
1749 
1750 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1751                                             SmallVectorImpl<uint64_t> &Record,
1752                                             unsigned Abbrev) {
1753   Record.reserve(N->getElements().size() + 1);
1754   const uint64_t Version = 3 << 1;
1755   Record.push_back((uint64_t)N->isDistinct() | Version);
1756   Record.append(N->elements_begin(), N->elements_end());
1757 
1758   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1759   Record.clear();
1760 }
1761 
1762 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1763     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1764     unsigned Abbrev) {
1765   Record.push_back(N->isDistinct());
1766   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1767   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1768 
1769   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1770   Record.clear();
1771 }
1772 
1773 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1774                                               SmallVectorImpl<uint64_t> &Record,
1775                                               unsigned Abbrev) {
1776   Record.push_back(N->isDistinct());
1777   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1778   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1779   Record.push_back(N->getLine());
1780   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1781   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1782   Record.push_back(N->getAttributes());
1783   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1784 
1785   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1786   Record.clear();
1787 }
1788 
1789 void ModuleBitcodeWriter::writeDIImportedEntity(
1790     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1791     unsigned Abbrev) {
1792   Record.push_back(N->isDistinct());
1793   Record.push_back(N->getTag());
1794   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1795   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1796   Record.push_back(N->getLine());
1797   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1798   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1799 
1800   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1801   Record.clear();
1802 }
1803 
1804 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1805   auto Abbv = std::make_shared<BitCodeAbbrev>();
1806   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1807   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1808   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1809   return Stream.EmitAbbrev(std::move(Abbv));
1810 }
1811 
1812 void ModuleBitcodeWriter::writeNamedMetadata(
1813     SmallVectorImpl<uint64_t> &Record) {
1814   if (M.named_metadata_empty())
1815     return;
1816 
1817   unsigned Abbrev = createNamedMetadataAbbrev();
1818   for (const NamedMDNode &NMD : M.named_metadata()) {
1819     // Write name.
1820     StringRef Str = NMD.getName();
1821     Record.append(Str.bytes_begin(), Str.bytes_end());
1822     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1823     Record.clear();
1824 
1825     // Write named metadata operands.
1826     for (const MDNode *N : NMD.operands())
1827       Record.push_back(VE.getMetadataID(N));
1828     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1829     Record.clear();
1830   }
1831 }
1832 
1833 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1834   auto Abbv = std::make_shared<BitCodeAbbrev>();
1835   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1836   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1837   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1838   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1839   return Stream.EmitAbbrev(std::move(Abbv));
1840 }
1841 
1842 /// Write out a record for MDString.
1843 ///
1844 /// All the metadata strings in a metadata block are emitted in a single
1845 /// record.  The sizes and strings themselves are shoved into a blob.
1846 void ModuleBitcodeWriter::writeMetadataStrings(
1847     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1848   if (Strings.empty())
1849     return;
1850 
1851   // Start the record with the number of strings.
1852   Record.push_back(bitc::METADATA_STRINGS);
1853   Record.push_back(Strings.size());
1854 
1855   // Emit the sizes of the strings in the blob.
1856   SmallString<256> Blob;
1857   {
1858     BitstreamWriter W(Blob);
1859     for (const Metadata *MD : Strings)
1860       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1861     W.FlushToWord();
1862   }
1863 
1864   // Add the offset to the strings to the record.
1865   Record.push_back(Blob.size());
1866 
1867   // Add the strings to the blob.
1868   for (const Metadata *MD : Strings)
1869     Blob.append(cast<MDString>(MD)->getString());
1870 
1871   // Emit the final record.
1872   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1873   Record.clear();
1874 }
1875 
1876 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1877 enum MetadataAbbrev : unsigned {
1878 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1879 #include "llvm/IR/Metadata.def"
1880   LastPlusOne
1881 };
1882 
1883 void ModuleBitcodeWriter::writeMetadataRecords(
1884     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1885     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1886   if (MDs.empty())
1887     return;
1888 
1889   // Initialize MDNode abbreviations.
1890 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1891 #include "llvm/IR/Metadata.def"
1892 
1893   for (const Metadata *MD : MDs) {
1894     if (IndexPos)
1895       IndexPos->push_back(Stream.GetCurrentBitNo());
1896     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1897       assert(N->isResolved() && "Expected forward references to be resolved");
1898 
1899       switch (N->getMetadataID()) {
1900       default:
1901         llvm_unreachable("Invalid MDNode subclass");
1902 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1903   case Metadata::CLASS##Kind:                                                  \
1904     if (MDAbbrevs)                                                             \
1905       write##CLASS(cast<CLASS>(N), Record,                                     \
1906                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1907     else                                                                       \
1908       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1909     continue;
1910 #include "llvm/IR/Metadata.def"
1911       }
1912     }
1913     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1914   }
1915 }
1916 
1917 void ModuleBitcodeWriter::writeModuleMetadata() {
1918   if (!VE.hasMDs() && M.named_metadata_empty())
1919     return;
1920 
1921   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1922   SmallVector<uint64_t, 64> Record;
1923 
1924   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1925   // block and load any metadata.
1926   std::vector<unsigned> MDAbbrevs;
1927 
1928   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1929   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1930   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1931       createGenericDINodeAbbrev();
1932 
1933   auto Abbv = std::make_shared<BitCodeAbbrev>();
1934   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1935   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1936   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1937   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1938 
1939   Abbv = std::make_shared<BitCodeAbbrev>();
1940   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1941   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1942   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1943   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1944 
1945   // Emit MDStrings together upfront.
1946   writeMetadataStrings(VE.getMDStrings(), Record);
1947 
1948   // We only emit an index for the metadata record if we have more than a given
1949   // (naive) threshold of metadatas, otherwise it is not worth it.
1950   if (VE.getNonMDStrings().size() > IndexThreshold) {
1951     // Write a placeholder value in for the offset of the metadata index,
1952     // which is written after the records, so that it can include
1953     // the offset of each entry. The placeholder offset will be
1954     // updated after all records are emitted.
1955     uint64_t Vals[] = {0, 0};
1956     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
1957   }
1958 
1959   // Compute and save the bit offset to the current position, which will be
1960   // patched when we emit the index later. We can simply subtract the 64-bit
1961   // fixed size from the current bit number to get the location to backpatch.
1962   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
1963 
1964   // This index will contain the bitpos for each individual record.
1965   std::vector<uint64_t> IndexPos;
1966   IndexPos.reserve(VE.getNonMDStrings().size());
1967 
1968   // Write all the records
1969   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
1970 
1971   if (VE.getNonMDStrings().size() > IndexThreshold) {
1972     // Now that we have emitted all the records we will emit the index. But
1973     // first
1974     // backpatch the forward reference so that the reader can skip the records
1975     // efficiently.
1976     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
1977                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
1978 
1979     // Delta encode the index.
1980     uint64_t PreviousValue = IndexOffsetRecordBitPos;
1981     for (auto &Elt : IndexPos) {
1982       auto EltDelta = Elt - PreviousValue;
1983       PreviousValue = Elt;
1984       Elt = EltDelta;
1985     }
1986     // Emit the index record.
1987     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
1988     IndexPos.clear();
1989   }
1990 
1991   // Write the named metadata now.
1992   writeNamedMetadata(Record);
1993 
1994   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
1995     SmallVector<uint64_t, 4> Record;
1996     Record.push_back(VE.getValueID(&GO));
1997     pushGlobalMetadataAttachment(Record, GO);
1998     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
1999   };
2000   for (const Function &F : M)
2001     if (F.isDeclaration() && F.hasMetadata())
2002       AddDeclAttachedMetadata(F);
2003   // FIXME: Only store metadata for declarations here, and move data for global
2004   // variable definitions to a separate block (PR28134).
2005   for (const GlobalVariable &GV : M.globals())
2006     if (GV.hasMetadata())
2007       AddDeclAttachedMetadata(GV);
2008 
2009   Stream.ExitBlock();
2010 }
2011 
2012 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2013   if (!VE.hasMDs())
2014     return;
2015 
2016   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2017   SmallVector<uint64_t, 64> Record;
2018   writeMetadataStrings(VE.getMDStrings(), Record);
2019   writeMetadataRecords(VE.getNonMDStrings(), Record);
2020   Stream.ExitBlock();
2021 }
2022 
2023 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2024     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2025   // [n x [id, mdnode]]
2026   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2027   GO.getAllMetadata(MDs);
2028   for (const auto &I : MDs) {
2029     Record.push_back(I.first);
2030     Record.push_back(VE.getMetadataID(I.second));
2031   }
2032 }
2033 
2034 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2035   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2036 
2037   SmallVector<uint64_t, 64> Record;
2038 
2039   if (F.hasMetadata()) {
2040     pushGlobalMetadataAttachment(Record, F);
2041     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2042     Record.clear();
2043   }
2044 
2045   // Write metadata attachments
2046   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2047   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2048   for (const BasicBlock &BB : F)
2049     for (const Instruction &I : BB) {
2050       MDs.clear();
2051       I.getAllMetadataOtherThanDebugLoc(MDs);
2052 
2053       // If no metadata, ignore instruction.
2054       if (MDs.empty()) continue;
2055 
2056       Record.push_back(VE.getInstructionID(&I));
2057 
2058       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2059         Record.push_back(MDs[i].first);
2060         Record.push_back(VE.getMetadataID(MDs[i].second));
2061       }
2062       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2063       Record.clear();
2064     }
2065 
2066   Stream.ExitBlock();
2067 }
2068 
2069 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2070   SmallVector<uint64_t, 64> Record;
2071 
2072   // Write metadata kinds
2073   // METADATA_KIND - [n x [id, name]]
2074   SmallVector<StringRef, 8> Names;
2075   M.getMDKindNames(Names);
2076 
2077   if (Names.empty()) return;
2078 
2079   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2080 
2081   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2082     Record.push_back(MDKindID);
2083     StringRef KName = Names[MDKindID];
2084     Record.append(KName.begin(), KName.end());
2085 
2086     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2087     Record.clear();
2088   }
2089 
2090   Stream.ExitBlock();
2091 }
2092 
2093 void ModuleBitcodeWriter::writeOperandBundleTags() {
2094   // Write metadata kinds
2095   //
2096   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2097   //
2098   // OPERAND_BUNDLE_TAG - [strchr x N]
2099 
2100   SmallVector<StringRef, 8> Tags;
2101   M.getOperandBundleTags(Tags);
2102 
2103   if (Tags.empty())
2104     return;
2105 
2106   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2107 
2108   SmallVector<uint64_t, 64> Record;
2109 
2110   for (auto Tag : Tags) {
2111     Record.append(Tag.begin(), Tag.end());
2112 
2113     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2114     Record.clear();
2115   }
2116 
2117   Stream.ExitBlock();
2118 }
2119 
2120 void ModuleBitcodeWriter::writeSyncScopeNames() {
2121   SmallVector<StringRef, 8> SSNs;
2122   M.getContext().getSyncScopeNames(SSNs);
2123   if (SSNs.empty())
2124     return;
2125 
2126   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2127 
2128   SmallVector<uint64_t, 64> Record;
2129   for (auto SSN : SSNs) {
2130     Record.append(SSN.begin(), SSN.end());
2131     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2132     Record.clear();
2133   }
2134 
2135   Stream.ExitBlock();
2136 }
2137 
2138 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2139   if ((int64_t)V >= 0)
2140     Vals.push_back(V << 1);
2141   else
2142     Vals.push_back((-V << 1) | 1);
2143 }
2144 
2145 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2146                                          bool isGlobal) {
2147   if (FirstVal == LastVal) return;
2148 
2149   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2150 
2151   unsigned AggregateAbbrev = 0;
2152   unsigned String8Abbrev = 0;
2153   unsigned CString7Abbrev = 0;
2154   unsigned CString6Abbrev = 0;
2155   // If this is a constant pool for the module, emit module-specific abbrevs.
2156   if (isGlobal) {
2157     // Abbrev for CST_CODE_AGGREGATE.
2158     auto Abbv = std::make_shared<BitCodeAbbrev>();
2159     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2160     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2161     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2162     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2163 
2164     // Abbrev for CST_CODE_STRING.
2165     Abbv = std::make_shared<BitCodeAbbrev>();
2166     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2167     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2168     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2169     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2170     // Abbrev for CST_CODE_CSTRING.
2171     Abbv = std::make_shared<BitCodeAbbrev>();
2172     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2173     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2175     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2176     // Abbrev for CST_CODE_CSTRING.
2177     Abbv = std::make_shared<BitCodeAbbrev>();
2178     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2179     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2180     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2181     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2182   }
2183 
2184   SmallVector<uint64_t, 64> Record;
2185 
2186   const ValueEnumerator::ValueList &Vals = VE.getValues();
2187   Type *LastTy = nullptr;
2188   for (unsigned i = FirstVal; i != LastVal; ++i) {
2189     const Value *V = Vals[i].first;
2190     // If we need to switch types, do so now.
2191     if (V->getType() != LastTy) {
2192       LastTy = V->getType();
2193       Record.push_back(VE.getTypeID(LastTy));
2194       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2195                         CONSTANTS_SETTYPE_ABBREV);
2196       Record.clear();
2197     }
2198 
2199     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2200       Record.push_back(unsigned(IA->hasSideEffects()) |
2201                        unsigned(IA->isAlignStack()) << 1 |
2202                        unsigned(IA->getDialect()&1) << 2);
2203 
2204       // Add the asm string.
2205       const std::string &AsmStr = IA->getAsmString();
2206       Record.push_back(AsmStr.size());
2207       Record.append(AsmStr.begin(), AsmStr.end());
2208 
2209       // Add the constraint string.
2210       const std::string &ConstraintStr = IA->getConstraintString();
2211       Record.push_back(ConstraintStr.size());
2212       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2213       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2214       Record.clear();
2215       continue;
2216     }
2217     const Constant *C = cast<Constant>(V);
2218     unsigned Code = -1U;
2219     unsigned AbbrevToUse = 0;
2220     if (C->isNullValue()) {
2221       Code = bitc::CST_CODE_NULL;
2222     } else if (isa<UndefValue>(C)) {
2223       Code = bitc::CST_CODE_UNDEF;
2224     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2225       if (IV->getBitWidth() <= 64) {
2226         uint64_t V = IV->getSExtValue();
2227         emitSignedInt64(Record, V);
2228         Code = bitc::CST_CODE_INTEGER;
2229         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2230       } else {                             // Wide integers, > 64 bits in size.
2231         // We have an arbitrary precision integer value to write whose
2232         // bit width is > 64. However, in canonical unsigned integer
2233         // format it is likely that the high bits are going to be zero.
2234         // So, we only write the number of active words.
2235         unsigned NWords = IV->getValue().getActiveWords();
2236         const uint64_t *RawWords = IV->getValue().getRawData();
2237         for (unsigned i = 0; i != NWords; ++i) {
2238           emitSignedInt64(Record, RawWords[i]);
2239         }
2240         Code = bitc::CST_CODE_WIDE_INTEGER;
2241       }
2242     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2243       Code = bitc::CST_CODE_FLOAT;
2244       Type *Ty = CFP->getType();
2245       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2246         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2247       } else if (Ty->isX86_FP80Ty()) {
2248         // api needed to prevent premature destruction
2249         // bits are not in the same order as a normal i80 APInt, compensate.
2250         APInt api = CFP->getValueAPF().bitcastToAPInt();
2251         const uint64_t *p = api.getRawData();
2252         Record.push_back((p[1] << 48) | (p[0] >> 16));
2253         Record.push_back(p[0] & 0xffffLL);
2254       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2255         APInt api = CFP->getValueAPF().bitcastToAPInt();
2256         const uint64_t *p = api.getRawData();
2257         Record.push_back(p[0]);
2258         Record.push_back(p[1]);
2259       } else {
2260         assert(0 && "Unknown FP type!");
2261       }
2262     } else if (isa<ConstantDataSequential>(C) &&
2263                cast<ConstantDataSequential>(C)->isString()) {
2264       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2265       // Emit constant strings specially.
2266       unsigned NumElts = Str->getNumElements();
2267       // If this is a null-terminated string, use the denser CSTRING encoding.
2268       if (Str->isCString()) {
2269         Code = bitc::CST_CODE_CSTRING;
2270         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2271       } else {
2272         Code = bitc::CST_CODE_STRING;
2273         AbbrevToUse = String8Abbrev;
2274       }
2275       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2276       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2277       for (unsigned i = 0; i != NumElts; ++i) {
2278         unsigned char V = Str->getElementAsInteger(i);
2279         Record.push_back(V);
2280         isCStr7 &= (V & 128) == 0;
2281         if (isCStrChar6)
2282           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2283       }
2284 
2285       if (isCStrChar6)
2286         AbbrevToUse = CString6Abbrev;
2287       else if (isCStr7)
2288         AbbrevToUse = CString7Abbrev;
2289     } else if (const ConstantDataSequential *CDS =
2290                   dyn_cast<ConstantDataSequential>(C)) {
2291       Code = bitc::CST_CODE_DATA;
2292       Type *EltTy = CDS->getType()->getElementType();
2293       if (isa<IntegerType>(EltTy)) {
2294         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2295           Record.push_back(CDS->getElementAsInteger(i));
2296       } else {
2297         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2298           Record.push_back(
2299               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2300       }
2301     } else if (isa<ConstantAggregate>(C)) {
2302       Code = bitc::CST_CODE_AGGREGATE;
2303       for (const Value *Op : C->operands())
2304         Record.push_back(VE.getValueID(Op));
2305       AbbrevToUse = AggregateAbbrev;
2306     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2307       switch (CE->getOpcode()) {
2308       default:
2309         if (Instruction::isCast(CE->getOpcode())) {
2310           Code = bitc::CST_CODE_CE_CAST;
2311           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2312           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2313           Record.push_back(VE.getValueID(C->getOperand(0)));
2314           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2315         } else {
2316           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2317           Code = bitc::CST_CODE_CE_BINOP;
2318           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2319           Record.push_back(VE.getValueID(C->getOperand(0)));
2320           Record.push_back(VE.getValueID(C->getOperand(1)));
2321           uint64_t Flags = getOptimizationFlags(CE);
2322           if (Flags != 0)
2323             Record.push_back(Flags);
2324         }
2325         break;
2326       case Instruction::GetElementPtr: {
2327         Code = bitc::CST_CODE_CE_GEP;
2328         const auto *GO = cast<GEPOperator>(C);
2329         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2330         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2331           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2332           Record.push_back((*Idx << 1) | GO->isInBounds());
2333         } else if (GO->isInBounds())
2334           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2335         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2336           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2337           Record.push_back(VE.getValueID(C->getOperand(i)));
2338         }
2339         break;
2340       }
2341       case Instruction::Select:
2342         Code = bitc::CST_CODE_CE_SELECT;
2343         Record.push_back(VE.getValueID(C->getOperand(0)));
2344         Record.push_back(VE.getValueID(C->getOperand(1)));
2345         Record.push_back(VE.getValueID(C->getOperand(2)));
2346         break;
2347       case Instruction::ExtractElement:
2348         Code = bitc::CST_CODE_CE_EXTRACTELT;
2349         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2350         Record.push_back(VE.getValueID(C->getOperand(0)));
2351         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2352         Record.push_back(VE.getValueID(C->getOperand(1)));
2353         break;
2354       case Instruction::InsertElement:
2355         Code = bitc::CST_CODE_CE_INSERTELT;
2356         Record.push_back(VE.getValueID(C->getOperand(0)));
2357         Record.push_back(VE.getValueID(C->getOperand(1)));
2358         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2359         Record.push_back(VE.getValueID(C->getOperand(2)));
2360         break;
2361       case Instruction::ShuffleVector:
2362         // If the return type and argument types are the same, this is a
2363         // standard shufflevector instruction.  If the types are different,
2364         // then the shuffle is widening or truncating the input vectors, and
2365         // the argument type must also be encoded.
2366         if (C->getType() == C->getOperand(0)->getType()) {
2367           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2368         } else {
2369           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2370           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2371         }
2372         Record.push_back(VE.getValueID(C->getOperand(0)));
2373         Record.push_back(VE.getValueID(C->getOperand(1)));
2374         Record.push_back(VE.getValueID(C->getOperand(2)));
2375         break;
2376       case Instruction::ICmp:
2377       case Instruction::FCmp:
2378         Code = bitc::CST_CODE_CE_CMP;
2379         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2380         Record.push_back(VE.getValueID(C->getOperand(0)));
2381         Record.push_back(VE.getValueID(C->getOperand(1)));
2382         Record.push_back(CE->getPredicate());
2383         break;
2384       }
2385     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2386       Code = bitc::CST_CODE_BLOCKADDRESS;
2387       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2388       Record.push_back(VE.getValueID(BA->getFunction()));
2389       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2390     } else {
2391 #ifndef NDEBUG
2392       C->dump();
2393 #endif
2394       llvm_unreachable("Unknown constant!");
2395     }
2396     Stream.EmitRecord(Code, Record, AbbrevToUse);
2397     Record.clear();
2398   }
2399 
2400   Stream.ExitBlock();
2401 }
2402 
2403 void ModuleBitcodeWriter::writeModuleConstants() {
2404   const ValueEnumerator::ValueList &Vals = VE.getValues();
2405 
2406   // Find the first constant to emit, which is the first non-globalvalue value.
2407   // We know globalvalues have been emitted by WriteModuleInfo.
2408   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2409     if (!isa<GlobalValue>(Vals[i].first)) {
2410       writeConstants(i, Vals.size(), true);
2411       return;
2412     }
2413   }
2414 }
2415 
2416 /// pushValueAndType - The file has to encode both the value and type id for
2417 /// many values, because we need to know what type to create for forward
2418 /// references.  However, most operands are not forward references, so this type
2419 /// field is not needed.
2420 ///
2421 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2422 /// instruction ID, then it is a forward reference, and it also includes the
2423 /// type ID.  The value ID that is written is encoded relative to the InstID.
2424 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2425                                            SmallVectorImpl<unsigned> &Vals) {
2426   unsigned ValID = VE.getValueID(V);
2427   // Make encoding relative to the InstID.
2428   Vals.push_back(InstID - ValID);
2429   if (ValID >= InstID) {
2430     Vals.push_back(VE.getTypeID(V->getType()));
2431     return true;
2432   }
2433   return false;
2434 }
2435 
2436 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2437                                               unsigned InstID) {
2438   SmallVector<unsigned, 64> Record;
2439   LLVMContext &C = CS.getInstruction()->getContext();
2440 
2441   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2442     const auto &Bundle = CS.getOperandBundleAt(i);
2443     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2444 
2445     for (auto &Input : Bundle.Inputs)
2446       pushValueAndType(Input, InstID, Record);
2447 
2448     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2449     Record.clear();
2450   }
2451 }
2452 
2453 /// pushValue - Like pushValueAndType, but where the type of the value is
2454 /// omitted (perhaps it was already encoded in an earlier operand).
2455 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2456                                     SmallVectorImpl<unsigned> &Vals) {
2457   unsigned ValID = VE.getValueID(V);
2458   Vals.push_back(InstID - ValID);
2459 }
2460 
2461 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2462                                           SmallVectorImpl<uint64_t> &Vals) {
2463   unsigned ValID = VE.getValueID(V);
2464   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2465   emitSignedInt64(Vals, diff);
2466 }
2467 
2468 /// WriteInstruction - Emit an instruction to the specified stream.
2469 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2470                                            unsigned InstID,
2471                                            SmallVectorImpl<unsigned> &Vals) {
2472   unsigned Code = 0;
2473   unsigned AbbrevToUse = 0;
2474   VE.setInstructionID(&I);
2475   switch (I.getOpcode()) {
2476   default:
2477     if (Instruction::isCast(I.getOpcode())) {
2478       Code = bitc::FUNC_CODE_INST_CAST;
2479       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2480         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2481       Vals.push_back(VE.getTypeID(I.getType()));
2482       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2483     } else {
2484       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2485       Code = bitc::FUNC_CODE_INST_BINOP;
2486       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2487         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2488       pushValue(I.getOperand(1), InstID, Vals);
2489       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2490       uint64_t Flags = getOptimizationFlags(&I);
2491       if (Flags != 0) {
2492         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2493           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2494         Vals.push_back(Flags);
2495       }
2496     }
2497     break;
2498 
2499   case Instruction::GetElementPtr: {
2500     Code = bitc::FUNC_CODE_INST_GEP;
2501     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2502     auto &GEPInst = cast<GetElementPtrInst>(I);
2503     Vals.push_back(GEPInst.isInBounds());
2504     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2505     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2506       pushValueAndType(I.getOperand(i), InstID, Vals);
2507     break;
2508   }
2509   case Instruction::ExtractValue: {
2510     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2511     pushValueAndType(I.getOperand(0), InstID, Vals);
2512     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2513     Vals.append(EVI->idx_begin(), EVI->idx_end());
2514     break;
2515   }
2516   case Instruction::InsertValue: {
2517     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2518     pushValueAndType(I.getOperand(0), InstID, Vals);
2519     pushValueAndType(I.getOperand(1), InstID, Vals);
2520     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2521     Vals.append(IVI->idx_begin(), IVI->idx_end());
2522     break;
2523   }
2524   case Instruction::Select:
2525     Code = bitc::FUNC_CODE_INST_VSELECT;
2526     pushValueAndType(I.getOperand(1), InstID, Vals);
2527     pushValue(I.getOperand(2), InstID, Vals);
2528     pushValueAndType(I.getOperand(0), InstID, Vals);
2529     break;
2530   case Instruction::ExtractElement:
2531     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2532     pushValueAndType(I.getOperand(0), InstID, Vals);
2533     pushValueAndType(I.getOperand(1), InstID, Vals);
2534     break;
2535   case Instruction::InsertElement:
2536     Code = bitc::FUNC_CODE_INST_INSERTELT;
2537     pushValueAndType(I.getOperand(0), InstID, Vals);
2538     pushValue(I.getOperand(1), InstID, Vals);
2539     pushValueAndType(I.getOperand(2), InstID, Vals);
2540     break;
2541   case Instruction::ShuffleVector:
2542     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2543     pushValueAndType(I.getOperand(0), InstID, Vals);
2544     pushValue(I.getOperand(1), InstID, Vals);
2545     pushValue(I.getOperand(2), InstID, Vals);
2546     break;
2547   case Instruction::ICmp:
2548   case Instruction::FCmp: {
2549     // compare returning Int1Ty or vector of Int1Ty
2550     Code = bitc::FUNC_CODE_INST_CMP2;
2551     pushValueAndType(I.getOperand(0), InstID, Vals);
2552     pushValue(I.getOperand(1), InstID, Vals);
2553     Vals.push_back(cast<CmpInst>(I).getPredicate());
2554     uint64_t Flags = getOptimizationFlags(&I);
2555     if (Flags != 0)
2556       Vals.push_back(Flags);
2557     break;
2558   }
2559 
2560   case Instruction::Ret:
2561     {
2562       Code = bitc::FUNC_CODE_INST_RET;
2563       unsigned NumOperands = I.getNumOperands();
2564       if (NumOperands == 0)
2565         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2566       else if (NumOperands == 1) {
2567         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2568           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2569       } else {
2570         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2571           pushValueAndType(I.getOperand(i), InstID, Vals);
2572       }
2573     }
2574     break;
2575   case Instruction::Br:
2576     {
2577       Code = bitc::FUNC_CODE_INST_BR;
2578       const BranchInst &II = cast<BranchInst>(I);
2579       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2580       if (II.isConditional()) {
2581         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2582         pushValue(II.getCondition(), InstID, Vals);
2583       }
2584     }
2585     break;
2586   case Instruction::Switch:
2587     {
2588       Code = bitc::FUNC_CODE_INST_SWITCH;
2589       const SwitchInst &SI = cast<SwitchInst>(I);
2590       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2591       pushValue(SI.getCondition(), InstID, Vals);
2592       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2593       for (auto Case : SI.cases()) {
2594         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2595         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2596       }
2597     }
2598     break;
2599   case Instruction::IndirectBr:
2600     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2601     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2602     // Encode the address operand as relative, but not the basic blocks.
2603     pushValue(I.getOperand(0), InstID, Vals);
2604     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2605       Vals.push_back(VE.getValueID(I.getOperand(i)));
2606     break;
2607 
2608   case Instruction::Invoke: {
2609     const InvokeInst *II = cast<InvokeInst>(&I);
2610     const Value *Callee = II->getCalledValue();
2611     FunctionType *FTy = II->getFunctionType();
2612 
2613     if (II->hasOperandBundles())
2614       writeOperandBundles(II, InstID);
2615 
2616     Code = bitc::FUNC_CODE_INST_INVOKE;
2617 
2618     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2619     Vals.push_back(II->getCallingConv() | 1 << 13);
2620     Vals.push_back(VE.getValueID(II->getNormalDest()));
2621     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2622     Vals.push_back(VE.getTypeID(FTy));
2623     pushValueAndType(Callee, InstID, Vals);
2624 
2625     // Emit value #'s for the fixed parameters.
2626     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2627       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2628 
2629     // Emit type/value pairs for varargs params.
2630     if (FTy->isVarArg()) {
2631       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2632            i != e; ++i)
2633         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2634     }
2635     break;
2636   }
2637   case Instruction::Resume:
2638     Code = bitc::FUNC_CODE_INST_RESUME;
2639     pushValueAndType(I.getOperand(0), InstID, Vals);
2640     break;
2641   case Instruction::CleanupRet: {
2642     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2643     const auto &CRI = cast<CleanupReturnInst>(I);
2644     pushValue(CRI.getCleanupPad(), InstID, Vals);
2645     if (CRI.hasUnwindDest())
2646       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2647     break;
2648   }
2649   case Instruction::CatchRet: {
2650     Code = bitc::FUNC_CODE_INST_CATCHRET;
2651     const auto &CRI = cast<CatchReturnInst>(I);
2652     pushValue(CRI.getCatchPad(), InstID, Vals);
2653     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2654     break;
2655   }
2656   case Instruction::CleanupPad:
2657   case Instruction::CatchPad: {
2658     const auto &FuncletPad = cast<FuncletPadInst>(I);
2659     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2660                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2661     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2662 
2663     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2664     Vals.push_back(NumArgOperands);
2665     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2666       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2667     break;
2668   }
2669   case Instruction::CatchSwitch: {
2670     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2671     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2672 
2673     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2674 
2675     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2676     Vals.push_back(NumHandlers);
2677     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2678       Vals.push_back(VE.getValueID(CatchPadBB));
2679 
2680     if (CatchSwitch.hasUnwindDest())
2681       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2682     break;
2683   }
2684   case Instruction::Unreachable:
2685     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2686     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2687     break;
2688 
2689   case Instruction::PHI: {
2690     const PHINode &PN = cast<PHINode>(I);
2691     Code = bitc::FUNC_CODE_INST_PHI;
2692     // With the newer instruction encoding, forward references could give
2693     // negative valued IDs.  This is most common for PHIs, so we use
2694     // signed VBRs.
2695     SmallVector<uint64_t, 128> Vals64;
2696     Vals64.push_back(VE.getTypeID(PN.getType()));
2697     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2698       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2699       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2700     }
2701     // Emit a Vals64 vector and exit.
2702     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2703     Vals64.clear();
2704     return;
2705   }
2706 
2707   case Instruction::LandingPad: {
2708     const LandingPadInst &LP = cast<LandingPadInst>(I);
2709     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2710     Vals.push_back(VE.getTypeID(LP.getType()));
2711     Vals.push_back(LP.isCleanup());
2712     Vals.push_back(LP.getNumClauses());
2713     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2714       if (LP.isCatch(I))
2715         Vals.push_back(LandingPadInst::Catch);
2716       else
2717         Vals.push_back(LandingPadInst::Filter);
2718       pushValueAndType(LP.getClause(I), InstID, Vals);
2719     }
2720     break;
2721   }
2722 
2723   case Instruction::Alloca: {
2724     Code = bitc::FUNC_CODE_INST_ALLOCA;
2725     const AllocaInst &AI = cast<AllocaInst>(I);
2726     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2727     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2728     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2729     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2730     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2731            "not enough bits for maximum alignment");
2732     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2733     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2734     AlignRecord |= 1 << 6;
2735     AlignRecord |= AI.isSwiftError() << 7;
2736     Vals.push_back(AlignRecord);
2737     break;
2738   }
2739 
2740   case Instruction::Load:
2741     if (cast<LoadInst>(I).isAtomic()) {
2742       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2743       pushValueAndType(I.getOperand(0), InstID, Vals);
2744     } else {
2745       Code = bitc::FUNC_CODE_INST_LOAD;
2746       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2747         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2748     }
2749     Vals.push_back(VE.getTypeID(I.getType()));
2750     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2751     Vals.push_back(cast<LoadInst>(I).isVolatile());
2752     if (cast<LoadInst>(I).isAtomic()) {
2753       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2754       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2755     }
2756     break;
2757   case Instruction::Store:
2758     if (cast<StoreInst>(I).isAtomic())
2759       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2760     else
2761       Code = bitc::FUNC_CODE_INST_STORE;
2762     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2763     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2764     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2765     Vals.push_back(cast<StoreInst>(I).isVolatile());
2766     if (cast<StoreInst>(I).isAtomic()) {
2767       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2768       Vals.push_back(
2769           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2770     }
2771     break;
2772   case Instruction::AtomicCmpXchg:
2773     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2774     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2775     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2776     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2777     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2778     Vals.push_back(
2779         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2780     Vals.push_back(
2781         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2782     Vals.push_back(
2783         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2784     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2785     break;
2786   case Instruction::AtomicRMW:
2787     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2788     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2789     pushValue(I.getOperand(1), InstID, Vals);        // val.
2790     Vals.push_back(
2791         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2792     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2793     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2794     Vals.push_back(
2795         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2796     break;
2797   case Instruction::Fence:
2798     Code = bitc::FUNC_CODE_INST_FENCE;
2799     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2800     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2801     break;
2802   case Instruction::Call: {
2803     const CallInst &CI = cast<CallInst>(I);
2804     FunctionType *FTy = CI.getFunctionType();
2805 
2806     if (CI.hasOperandBundles())
2807       writeOperandBundles(&CI, InstID);
2808 
2809     Code = bitc::FUNC_CODE_INST_CALL;
2810 
2811     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2812 
2813     unsigned Flags = getOptimizationFlags(&I);
2814     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2815                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2816                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2817                    1 << bitc::CALL_EXPLICIT_TYPE |
2818                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2819                    unsigned(Flags != 0) << bitc::CALL_FMF);
2820     if (Flags != 0)
2821       Vals.push_back(Flags);
2822 
2823     Vals.push_back(VE.getTypeID(FTy));
2824     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2825 
2826     // Emit value #'s for the fixed parameters.
2827     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2828       // Check for labels (can happen with asm labels).
2829       if (FTy->getParamType(i)->isLabelTy())
2830         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2831       else
2832         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2833     }
2834 
2835     // Emit type/value pairs for varargs params.
2836     if (FTy->isVarArg()) {
2837       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2838            i != e; ++i)
2839         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2840     }
2841     break;
2842   }
2843   case Instruction::VAArg:
2844     Code = bitc::FUNC_CODE_INST_VAARG;
2845     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2846     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2847     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2848     break;
2849   }
2850 
2851   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2852   Vals.clear();
2853 }
2854 
2855 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2856 /// to allow clients to efficiently find the function body.
2857 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2858   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2859   // Get the offset of the VST we are writing, and backpatch it into
2860   // the VST forward declaration record.
2861   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2862   // The BitcodeStartBit was the stream offset of the identification block.
2863   VSTOffset -= bitcodeStartBit();
2864   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2865   // Note that we add 1 here because the offset is relative to one word
2866   // before the start of the identification block, which was historically
2867   // always the start of the regular bitcode header.
2868   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2869 
2870   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2871 
2872   auto Abbv = std::make_shared<BitCodeAbbrev>();
2873   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2874   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2875   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2876   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2877 
2878   for (const Function &F : M) {
2879     uint64_t Record[2];
2880 
2881     if (F.isDeclaration())
2882       continue;
2883 
2884     Record[0] = VE.getValueID(&F);
2885 
2886     // Save the word offset of the function (from the start of the
2887     // actual bitcode written to the stream).
2888     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2889     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2890     // Note that we add 1 here because the offset is relative to one word
2891     // before the start of the identification block, which was historically
2892     // always the start of the regular bitcode header.
2893     Record[1] = BitcodeIndex / 32 + 1;
2894 
2895     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2896   }
2897 
2898   Stream.ExitBlock();
2899 }
2900 
2901 /// Emit names for arguments, instructions and basic blocks in a function.
2902 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2903     const ValueSymbolTable &VST) {
2904   if (VST.empty())
2905     return;
2906 
2907   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2908 
2909   // FIXME: Set up the abbrev, we know how many values there are!
2910   // FIXME: We know if the type names can use 7-bit ascii.
2911   SmallVector<uint64_t, 64> NameVals;
2912 
2913   for (const ValueName &Name : VST) {
2914     // Figure out the encoding to use for the name.
2915     StringEncoding Bits = getStringEncoding(Name.getKey());
2916 
2917     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2918     NameVals.push_back(VE.getValueID(Name.getValue()));
2919 
2920     // VST_CODE_ENTRY:   [valueid, namechar x N]
2921     // VST_CODE_BBENTRY: [bbid, namechar x N]
2922     unsigned Code;
2923     if (isa<BasicBlock>(Name.getValue())) {
2924       Code = bitc::VST_CODE_BBENTRY;
2925       if (Bits == SE_Char6)
2926         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2927     } else {
2928       Code = bitc::VST_CODE_ENTRY;
2929       if (Bits == SE_Char6)
2930         AbbrevToUse = VST_ENTRY_6_ABBREV;
2931       else if (Bits == SE_Fixed7)
2932         AbbrevToUse = VST_ENTRY_7_ABBREV;
2933     }
2934 
2935     for (const auto P : Name.getKey())
2936       NameVals.push_back((unsigned char)P);
2937 
2938     // Emit the finished record.
2939     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2940     NameVals.clear();
2941   }
2942 
2943   Stream.ExitBlock();
2944 }
2945 
2946 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
2947   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2948   unsigned Code;
2949   if (isa<BasicBlock>(Order.V))
2950     Code = bitc::USELIST_CODE_BB;
2951   else
2952     Code = bitc::USELIST_CODE_DEFAULT;
2953 
2954   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2955   Record.push_back(VE.getValueID(Order.V));
2956   Stream.EmitRecord(Code, Record);
2957 }
2958 
2959 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
2960   assert(VE.shouldPreserveUseListOrder() &&
2961          "Expected to be preserving use-list order");
2962 
2963   auto hasMore = [&]() {
2964     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2965   };
2966   if (!hasMore())
2967     // Nothing to do.
2968     return;
2969 
2970   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2971   while (hasMore()) {
2972     writeUseList(std::move(VE.UseListOrders.back()));
2973     VE.UseListOrders.pop_back();
2974   }
2975   Stream.ExitBlock();
2976 }
2977 
2978 /// Emit a function body to the module stream.
2979 void ModuleBitcodeWriter::writeFunction(
2980     const Function &F,
2981     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2982   // Save the bitcode index of the start of this function block for recording
2983   // in the VST.
2984   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
2985 
2986   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2987   VE.incorporateFunction(F);
2988 
2989   SmallVector<unsigned, 64> Vals;
2990 
2991   // Emit the number of basic blocks, so the reader can create them ahead of
2992   // time.
2993   Vals.push_back(VE.getBasicBlocks().size());
2994   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2995   Vals.clear();
2996 
2997   // If there are function-local constants, emit them now.
2998   unsigned CstStart, CstEnd;
2999   VE.getFunctionConstantRange(CstStart, CstEnd);
3000   writeConstants(CstStart, CstEnd, false);
3001 
3002   // If there is function-local metadata, emit it now.
3003   writeFunctionMetadata(F);
3004 
3005   // Keep a running idea of what the instruction ID is.
3006   unsigned InstID = CstEnd;
3007 
3008   bool NeedsMetadataAttachment = F.hasMetadata();
3009 
3010   DILocation *LastDL = nullptr;
3011   // Finally, emit all the instructions, in order.
3012   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3013     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3014          I != E; ++I) {
3015       writeInstruction(*I, InstID, Vals);
3016 
3017       if (!I->getType()->isVoidTy())
3018         ++InstID;
3019 
3020       // If the instruction has metadata, write a metadata attachment later.
3021       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3022 
3023       // If the instruction has a debug location, emit it.
3024       DILocation *DL = I->getDebugLoc();
3025       if (!DL)
3026         continue;
3027 
3028       if (DL == LastDL) {
3029         // Just repeat the same debug loc as last time.
3030         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3031         continue;
3032       }
3033 
3034       Vals.push_back(DL->getLine());
3035       Vals.push_back(DL->getColumn());
3036       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3037       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3038       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3039       Vals.clear();
3040 
3041       LastDL = DL;
3042     }
3043 
3044   // Emit names for all the instructions etc.
3045   if (auto *Symtab = F.getValueSymbolTable())
3046     writeFunctionLevelValueSymbolTable(*Symtab);
3047 
3048   if (NeedsMetadataAttachment)
3049     writeFunctionMetadataAttachment(F);
3050   if (VE.shouldPreserveUseListOrder())
3051     writeUseListBlock(&F);
3052   VE.purgeFunction();
3053   Stream.ExitBlock();
3054 }
3055 
3056 // Emit blockinfo, which defines the standard abbreviations etc.
3057 void ModuleBitcodeWriter::writeBlockInfo() {
3058   // We only want to emit block info records for blocks that have multiple
3059   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3060   // Other blocks can define their abbrevs inline.
3061   Stream.EnterBlockInfoBlock();
3062 
3063   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3064     auto Abbv = std::make_shared<BitCodeAbbrev>();
3065     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3066     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3067     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3068     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3069     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3070         VST_ENTRY_8_ABBREV)
3071       llvm_unreachable("Unexpected abbrev ordering!");
3072   }
3073 
3074   { // 7-bit fixed width VST_CODE_ENTRY strings.
3075     auto Abbv = std::make_shared<BitCodeAbbrev>();
3076     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3077     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3078     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3079     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3080     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3081         VST_ENTRY_7_ABBREV)
3082       llvm_unreachable("Unexpected abbrev ordering!");
3083   }
3084   { // 6-bit char6 VST_CODE_ENTRY strings.
3085     auto Abbv = std::make_shared<BitCodeAbbrev>();
3086     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3087     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3088     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3089     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3090     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3091         VST_ENTRY_6_ABBREV)
3092       llvm_unreachable("Unexpected abbrev ordering!");
3093   }
3094   { // 6-bit char6 VST_CODE_BBENTRY strings.
3095     auto Abbv = std::make_shared<BitCodeAbbrev>();
3096     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3097     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3098     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3099     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3100     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3101         VST_BBENTRY_6_ABBREV)
3102       llvm_unreachable("Unexpected abbrev ordering!");
3103   }
3104 
3105   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3106     auto Abbv = std::make_shared<BitCodeAbbrev>();
3107     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3108     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3109                               VE.computeBitsRequiredForTypeIndicies()));
3110     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3111         CONSTANTS_SETTYPE_ABBREV)
3112       llvm_unreachable("Unexpected abbrev ordering!");
3113   }
3114 
3115   { // INTEGER abbrev for CONSTANTS_BLOCK.
3116     auto Abbv = std::make_shared<BitCodeAbbrev>();
3117     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3118     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3119     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3120         CONSTANTS_INTEGER_ABBREV)
3121       llvm_unreachable("Unexpected abbrev ordering!");
3122   }
3123 
3124   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3125     auto Abbv = std::make_shared<BitCodeAbbrev>();
3126     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3127     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3128     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3129                               VE.computeBitsRequiredForTypeIndicies()));
3130     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3131 
3132     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3133         CONSTANTS_CE_CAST_Abbrev)
3134       llvm_unreachable("Unexpected abbrev ordering!");
3135   }
3136   { // NULL abbrev for CONSTANTS_BLOCK.
3137     auto Abbv = std::make_shared<BitCodeAbbrev>();
3138     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3139     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3140         CONSTANTS_NULL_Abbrev)
3141       llvm_unreachable("Unexpected abbrev ordering!");
3142   }
3143 
3144   // FIXME: This should only use space for first class types!
3145 
3146   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3147     auto Abbv = std::make_shared<BitCodeAbbrev>();
3148     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3149     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3150     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3151                               VE.computeBitsRequiredForTypeIndicies()));
3152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3153     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3154     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3155         FUNCTION_INST_LOAD_ABBREV)
3156       llvm_unreachable("Unexpected abbrev ordering!");
3157   }
3158   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3159     auto Abbv = std::make_shared<BitCodeAbbrev>();
3160     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3161     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3162     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3163     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3164     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3165         FUNCTION_INST_BINOP_ABBREV)
3166       llvm_unreachable("Unexpected abbrev ordering!");
3167   }
3168   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3169     auto Abbv = std::make_shared<BitCodeAbbrev>();
3170     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3171     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3173     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
3175     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3176         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3177       llvm_unreachable("Unexpected abbrev ordering!");
3178   }
3179   { // INST_CAST abbrev for FUNCTION_BLOCK.
3180     auto Abbv = std::make_shared<BitCodeAbbrev>();
3181     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3182     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3183     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3184                               VE.computeBitsRequiredForTypeIndicies()));
3185     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3186     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3187         FUNCTION_INST_CAST_ABBREV)
3188       llvm_unreachable("Unexpected abbrev ordering!");
3189   }
3190 
3191   { // INST_RET abbrev for FUNCTION_BLOCK.
3192     auto Abbv = std::make_shared<BitCodeAbbrev>();
3193     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3194     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3195         FUNCTION_INST_RET_VOID_ABBREV)
3196       llvm_unreachable("Unexpected abbrev ordering!");
3197   }
3198   { // INST_RET abbrev for FUNCTION_BLOCK.
3199     auto Abbv = std::make_shared<BitCodeAbbrev>();
3200     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3201     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3202     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3203         FUNCTION_INST_RET_VAL_ABBREV)
3204       llvm_unreachable("Unexpected abbrev ordering!");
3205   }
3206   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3207     auto Abbv = std::make_shared<BitCodeAbbrev>();
3208     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3209     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3210         FUNCTION_INST_UNREACHABLE_ABBREV)
3211       llvm_unreachable("Unexpected abbrev ordering!");
3212   }
3213   {
3214     auto Abbv = std::make_shared<BitCodeAbbrev>();
3215     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3216     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3217     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3218                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3220     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3221     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3222         FUNCTION_INST_GEP_ABBREV)
3223       llvm_unreachable("Unexpected abbrev ordering!");
3224   }
3225 
3226   Stream.ExitBlock();
3227 }
3228 
3229 /// Write the module path strings, currently only used when generating
3230 /// a combined index file.
3231 void IndexBitcodeWriter::writeModStrings() {
3232   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3233 
3234   // TODO: See which abbrev sizes we actually need to emit
3235 
3236   // 8-bit fixed-width MST_ENTRY strings.
3237   auto Abbv = std::make_shared<BitCodeAbbrev>();
3238   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3239   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3240   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3241   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3242   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3243 
3244   // 7-bit fixed width MST_ENTRY strings.
3245   Abbv = std::make_shared<BitCodeAbbrev>();
3246   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3247   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3248   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3249   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3250   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3251 
3252   // 6-bit char6 MST_ENTRY strings.
3253   Abbv = std::make_shared<BitCodeAbbrev>();
3254   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3255   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3256   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3257   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3258   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3259 
3260   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3261   Abbv = std::make_shared<BitCodeAbbrev>();
3262   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3263   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3264   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3265   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3266   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3267   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3268   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3269 
3270   SmallVector<unsigned, 64> Vals;
3271   forEachModule(
3272       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3273         StringRef Key = MPSE.getKey();
3274         const auto &Value = MPSE.getValue();
3275         StringEncoding Bits = getStringEncoding(Key);
3276         unsigned AbbrevToUse = Abbrev8Bit;
3277         if (Bits == SE_Char6)
3278           AbbrevToUse = Abbrev6Bit;
3279         else if (Bits == SE_Fixed7)
3280           AbbrevToUse = Abbrev7Bit;
3281 
3282         Vals.push_back(Value.first);
3283         Vals.append(Key.begin(), Key.end());
3284 
3285         // Emit the finished record.
3286         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3287 
3288         // Emit an optional hash for the module now
3289         const auto &Hash = Value.second;
3290         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3291           Vals.assign(Hash.begin(), Hash.end());
3292           // Emit the hash record.
3293           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3294         }
3295 
3296         Vals.clear();
3297       });
3298   Stream.ExitBlock();
3299 }
3300 
3301 /// Write the function type metadata related records that need to appear before
3302 /// a function summary entry (whether per-module or combined).
3303 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3304                                              FunctionSummary *FS) {
3305   if (!FS->type_tests().empty())
3306     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3307 
3308   SmallVector<uint64_t, 64> Record;
3309 
3310   auto WriteVFuncIdVec = [&](uint64_t Ty,
3311                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3312     if (VFs.empty())
3313       return;
3314     Record.clear();
3315     for (auto &VF : VFs) {
3316       Record.push_back(VF.GUID);
3317       Record.push_back(VF.Offset);
3318     }
3319     Stream.EmitRecord(Ty, Record);
3320   };
3321 
3322   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3323                   FS->type_test_assume_vcalls());
3324   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3325                   FS->type_checked_load_vcalls());
3326 
3327   auto WriteConstVCallVec = [&](uint64_t Ty,
3328                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3329     for (auto &VC : VCs) {
3330       Record.clear();
3331       Record.push_back(VC.VFunc.GUID);
3332       Record.push_back(VC.VFunc.Offset);
3333       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3334       Stream.EmitRecord(Ty, Record);
3335     }
3336   };
3337 
3338   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3339                      FS->type_test_assume_const_vcalls());
3340   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3341                      FS->type_checked_load_const_vcalls());
3342 }
3343 
3344 // Helper to emit a single function summary record.
3345 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3346     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3347     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3348     const Function &F) {
3349   NameVals.push_back(ValueID);
3350 
3351   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3352   writeFunctionTypeMetadataRecords(Stream, FS);
3353 
3354   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3355   NameVals.push_back(FS->instCount());
3356   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3357   NameVals.push_back(FS->refs().size());
3358 
3359   for (auto &RI : FS->refs())
3360     NameVals.push_back(VE.getValueID(RI.getValue()));
3361 
3362   bool HasProfileData = F.getEntryCount().hasValue();
3363   for (auto &ECI : FS->calls()) {
3364     NameVals.push_back(getValueId(ECI.first));
3365     if (HasProfileData)
3366       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3367   }
3368 
3369   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3370   unsigned Code =
3371       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
3372 
3373   // Emit the finished record.
3374   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3375   NameVals.clear();
3376 }
3377 
3378 // Collect the global value references in the given variable's initializer,
3379 // and emit them in a summary record.
3380 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3381     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3382     unsigned FSModRefsAbbrev) {
3383   auto VI = Index->getValueInfo(GlobalValue::getGUID(V.getName()));
3384   if (!VI || VI.getSummaryList().empty()) {
3385     // Only declarations should not have a summary (a declaration might however
3386     // have a summary if the def was in module level asm).
3387     assert(V.isDeclaration());
3388     return;
3389   }
3390   auto *Summary = VI.getSummaryList()[0].get();
3391   NameVals.push_back(VE.getValueID(&V));
3392   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3393   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3394 
3395   unsigned SizeBeforeRefs = NameVals.size();
3396   for (auto &RI : VS->refs())
3397     NameVals.push_back(VE.getValueID(RI.getValue()));
3398   // Sort the refs for determinism output, the vector returned by FS->refs() has
3399   // been initialized from a DenseSet.
3400   std::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3401 
3402   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3403                     FSModRefsAbbrev);
3404   NameVals.clear();
3405 }
3406 
3407 // Current version for the summary.
3408 // This is bumped whenever we introduce changes in the way some record are
3409 // interpreted, like flags for instance.
3410 static const uint64_t INDEX_VERSION = 4;
3411 
3412 /// Emit the per-module summary section alongside the rest of
3413 /// the module's bitcode.
3414 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3415   // By default we compile with ThinLTO if the module has a summary, but the
3416   // client can request full LTO with a module flag.
3417   bool IsThinLTO = true;
3418   if (auto *MD =
3419           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3420     IsThinLTO = MD->getZExtValue();
3421   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3422                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3423                        4);
3424 
3425   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3426 
3427   if (Index->begin() == Index->end()) {
3428     Stream.ExitBlock();
3429     return;
3430   }
3431 
3432   for (const auto &GVI : valueIds()) {
3433     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3434                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3435   }
3436 
3437   // Abbrev for FS_PERMODULE.
3438   auto Abbv = std::make_shared<BitCodeAbbrev>();
3439   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3440   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3441   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3442   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3443   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3444   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3445   // numrefs x valueid, n x (valueid)
3446   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3447   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3448   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3449 
3450   // Abbrev for FS_PERMODULE_PROFILE.
3451   Abbv = std::make_shared<BitCodeAbbrev>();
3452   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3453   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3454   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3455   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3456   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3457   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3458   // numrefs x valueid, n x (valueid, hotness)
3459   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3460   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3461   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3462 
3463   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3464   Abbv = std::make_shared<BitCodeAbbrev>();
3465   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3466   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3467   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3468   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3469   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3470   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3471 
3472   // Abbrev for FS_ALIAS.
3473   Abbv = std::make_shared<BitCodeAbbrev>();
3474   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3475   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3476   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3477   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3478   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3479 
3480   SmallVector<uint64_t, 64> NameVals;
3481   // Iterate over the list of functions instead of the Index to
3482   // ensure the ordering is stable.
3483   for (const Function &F : M) {
3484     // Summary emission does not support anonymous functions, they have to
3485     // renamed using the anonymous function renaming pass.
3486     if (!F.hasName())
3487       report_fatal_error("Unexpected anonymous function when writing summary");
3488 
3489     ValueInfo VI = Index->getValueInfo(GlobalValue::getGUID(F.getName()));
3490     if (!VI || VI.getSummaryList().empty()) {
3491       // Only declarations should not have a summary (a declaration might
3492       // however have a summary if the def was in module level asm).
3493       assert(F.isDeclaration());
3494       continue;
3495     }
3496     auto *Summary = VI.getSummaryList()[0].get();
3497     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3498                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3499   }
3500 
3501   // Capture references from GlobalVariable initializers, which are outside
3502   // of a function scope.
3503   for (const GlobalVariable &G : M.globals())
3504     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3505 
3506   for (const GlobalAlias &A : M.aliases()) {
3507     auto *Aliasee = A.getBaseObject();
3508     if (!Aliasee->hasName())
3509       // Nameless function don't have an entry in the summary, skip it.
3510       continue;
3511     auto AliasId = VE.getValueID(&A);
3512     auto AliaseeId = VE.getValueID(Aliasee);
3513     NameVals.push_back(AliasId);
3514     auto *Summary = Index->getGlobalValueSummary(A);
3515     AliasSummary *AS = cast<AliasSummary>(Summary);
3516     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3517     NameVals.push_back(AliaseeId);
3518     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3519     NameVals.clear();
3520   }
3521 
3522   Stream.ExitBlock();
3523 }
3524 
3525 /// Emit the combined summary section into the combined index file.
3526 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3527   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3528   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3529 
3530   for (const auto &GVI : valueIds()) {
3531     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3532                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3533   }
3534 
3535   // Abbrev for FS_COMBINED.
3536   auto Abbv = std::make_shared<BitCodeAbbrev>();
3537   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3538   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3539   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3540   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3541   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3542   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3543   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3544   // numrefs x valueid, n x (valueid)
3545   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3546   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3547   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3548 
3549   // Abbrev for FS_COMBINED_PROFILE.
3550   Abbv = std::make_shared<BitCodeAbbrev>();
3551   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3552   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3553   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3556   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3558   // numrefs x valueid, n x (valueid, hotness)
3559   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3560   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3561   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3562 
3563   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3564   Abbv = std::make_shared<BitCodeAbbrev>();
3565   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3566   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3567   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3568   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3569   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3570   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3571   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3572 
3573   // Abbrev for FS_COMBINED_ALIAS.
3574   Abbv = std::make_shared<BitCodeAbbrev>();
3575   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3576   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3577   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3578   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3579   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3580   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3581 
3582   // The aliases are emitted as a post-pass, and will point to the value
3583   // id of the aliasee. Save them in a vector for post-processing.
3584   SmallVector<AliasSummary *, 64> Aliases;
3585 
3586   // Save the value id for each summary for alias emission.
3587   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3588 
3589   SmallVector<uint64_t, 64> NameVals;
3590 
3591   // For local linkage, we also emit the original name separately
3592   // immediately after the record.
3593   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3594     if (!GlobalValue::isLocalLinkage(S.linkage()))
3595       return;
3596     NameVals.push_back(S.getOriginalName());
3597     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3598     NameVals.clear();
3599   };
3600 
3601   forEachSummary([&](GVInfo I) {
3602     GlobalValueSummary *S = I.second;
3603     assert(S);
3604 
3605     auto ValueId = getValueId(I.first);
3606     assert(ValueId);
3607     SummaryToValueIdMap[S] = *ValueId;
3608 
3609     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3610       // Will process aliases as a post-pass because the reader wants all
3611       // global to be loaded first.
3612       Aliases.push_back(AS);
3613       return;
3614     }
3615 
3616     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3617       NameVals.push_back(*ValueId);
3618       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3619       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3620       for (auto &RI : VS->refs()) {
3621         auto RefValueId = getValueId(RI.getGUID());
3622         if (!RefValueId)
3623           continue;
3624         NameVals.push_back(*RefValueId);
3625       }
3626 
3627       // Emit the finished record.
3628       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3629                         FSModRefsAbbrev);
3630       NameVals.clear();
3631       MaybeEmitOriginalName(*S);
3632       return;
3633     }
3634 
3635     auto *FS = cast<FunctionSummary>(S);
3636     writeFunctionTypeMetadataRecords(Stream, FS);
3637 
3638     NameVals.push_back(*ValueId);
3639     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3640     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3641     NameVals.push_back(FS->instCount());
3642     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3643     // Fill in below
3644     NameVals.push_back(0);
3645 
3646     unsigned Count = 0;
3647     for (auto &RI : FS->refs()) {
3648       auto RefValueId = getValueId(RI.getGUID());
3649       if (!RefValueId)
3650         continue;
3651       NameVals.push_back(*RefValueId);
3652       Count++;
3653     }
3654     NameVals[5] = Count;
3655 
3656     bool HasProfileData = false;
3657     for (auto &EI : FS->calls()) {
3658       HasProfileData |= EI.second.Hotness != CalleeInfo::HotnessType::Unknown;
3659       if (HasProfileData)
3660         break;
3661     }
3662 
3663     for (auto &EI : FS->calls()) {
3664       // If this GUID doesn't have a value id, it doesn't have a function
3665       // summary and we don't need to record any calls to it.
3666       GlobalValue::GUID GUID = EI.first.getGUID();
3667       auto CallValueId = getValueId(GUID);
3668       if (!CallValueId) {
3669         // For SamplePGO, the indirect call targets for local functions will
3670         // have its original name annotated in profile. We try to find the
3671         // corresponding PGOFuncName as the GUID.
3672         GUID = Index.getGUIDFromOriginalID(GUID);
3673         if (GUID == 0)
3674           continue;
3675         CallValueId = getValueId(GUID);
3676         if (!CallValueId)
3677           continue;
3678         // The mapping from OriginalId to GUID may return a GUID
3679         // that corresponds to a static variable. Filter it out here.
3680         // This can happen when
3681         // 1) There is a call to a library function which does not have
3682         // a CallValidId;
3683         // 2) There is a static variable with the  OriginalGUID identical
3684         // to the GUID of the library function in 1);
3685         // When this happens, the logic for SamplePGO kicks in and
3686         // the static variable in 2) will be found, which needs to be
3687         // filtered out.
3688         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3689         if (GVSum &&
3690             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3691           continue;
3692       }
3693       NameVals.push_back(*CallValueId);
3694       if (HasProfileData)
3695         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3696     }
3697 
3698     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3699     unsigned Code =
3700         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3701 
3702     // Emit the finished record.
3703     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3704     NameVals.clear();
3705     MaybeEmitOriginalName(*S);
3706   });
3707 
3708   for (auto *AS : Aliases) {
3709     auto AliasValueId = SummaryToValueIdMap[AS];
3710     assert(AliasValueId);
3711     NameVals.push_back(AliasValueId);
3712     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3713     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3714     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3715     assert(AliaseeValueId);
3716     NameVals.push_back(AliaseeValueId);
3717 
3718     // Emit the finished record.
3719     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3720     NameVals.clear();
3721     MaybeEmitOriginalName(*AS);
3722   }
3723 
3724   if (!Index.cfiFunctionDefs().empty()) {
3725     for (auto &S : Index.cfiFunctionDefs()) {
3726       NameVals.push_back(StrtabBuilder.add(S));
3727       NameVals.push_back(S.size());
3728     }
3729     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3730     NameVals.clear();
3731   }
3732 
3733   if (!Index.cfiFunctionDecls().empty()) {
3734     for (auto &S : Index.cfiFunctionDecls()) {
3735       NameVals.push_back(StrtabBuilder.add(S));
3736       NameVals.push_back(S.size());
3737     }
3738     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3739     NameVals.clear();
3740   }
3741 
3742   Stream.ExitBlock();
3743 }
3744 
3745 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3746 /// current llvm version, and a record for the epoch number.
3747 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3748   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3749 
3750   // Write the "user readable" string identifying the bitcode producer
3751   auto Abbv = std::make_shared<BitCodeAbbrev>();
3752   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3753   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3754   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3755   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3756   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3757                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3758 
3759   // Write the epoch version
3760   Abbv = std::make_shared<BitCodeAbbrev>();
3761   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3762   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3763   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3764   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3765   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3766   Stream.ExitBlock();
3767 }
3768 
3769 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3770   // Emit the module's hash.
3771   // MODULE_CODE_HASH: [5*i32]
3772   if (GenerateHash) {
3773     uint32_t Vals[5];
3774     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3775                                     Buffer.size() - BlockStartPos));
3776     StringRef Hash = Hasher.result();
3777     for (int Pos = 0; Pos < 20; Pos += 4) {
3778       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3779     }
3780 
3781     // Emit the finished record.
3782     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3783 
3784     if (ModHash)
3785       // Save the written hash value.
3786       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3787   }
3788 }
3789 
3790 void ModuleBitcodeWriter::write() {
3791   writeIdentificationBlock(Stream);
3792 
3793   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3794   size_t BlockStartPos = Buffer.size();
3795 
3796   writeModuleVersion();
3797 
3798   // Emit blockinfo, which defines the standard abbreviations etc.
3799   writeBlockInfo();
3800 
3801   // Emit information about attribute groups.
3802   writeAttributeGroupTable();
3803 
3804   // Emit information about parameter attributes.
3805   writeAttributeTable();
3806 
3807   // Emit information describing all of the types in the module.
3808   writeTypeTable();
3809 
3810   writeComdats();
3811 
3812   // Emit top-level description of module, including target triple, inline asm,
3813   // descriptors for global variables, and function prototype info.
3814   writeModuleInfo();
3815 
3816   // Emit constants.
3817   writeModuleConstants();
3818 
3819   // Emit metadata kind names.
3820   writeModuleMetadataKinds();
3821 
3822   // Emit metadata.
3823   writeModuleMetadata();
3824 
3825   // Emit module-level use-lists.
3826   if (VE.shouldPreserveUseListOrder())
3827     writeUseListBlock(nullptr);
3828 
3829   writeOperandBundleTags();
3830   writeSyncScopeNames();
3831 
3832   // Emit function bodies.
3833   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3834   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3835     if (!F->isDeclaration())
3836       writeFunction(*F, FunctionToBitcodeIndex);
3837 
3838   // Need to write after the above call to WriteFunction which populates
3839   // the summary information in the index.
3840   if (Index)
3841     writePerModuleGlobalValueSummary();
3842 
3843   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3844 
3845   writeModuleHash(BlockStartPos);
3846 
3847   Stream.ExitBlock();
3848 }
3849 
3850 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3851                                uint32_t &Position) {
3852   support::endian::write32le(&Buffer[Position], Value);
3853   Position += 4;
3854 }
3855 
3856 /// If generating a bc file on darwin, we have to emit a
3857 /// header and trailer to make it compatible with the system archiver.  To do
3858 /// this we emit the following header, and then emit a trailer that pads the
3859 /// file out to be a multiple of 16 bytes.
3860 ///
3861 /// struct bc_header {
3862 ///   uint32_t Magic;         // 0x0B17C0DE
3863 ///   uint32_t Version;       // Version, currently always 0.
3864 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3865 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3866 ///   uint32_t CPUType;       // CPU specifier.
3867 ///   ... potentially more later ...
3868 /// };
3869 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3870                                          const Triple &TT) {
3871   unsigned CPUType = ~0U;
3872 
3873   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3874   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3875   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3876   // specific constants here because they are implicitly part of the Darwin ABI.
3877   enum {
3878     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3879     DARWIN_CPU_TYPE_X86        = 7,
3880     DARWIN_CPU_TYPE_ARM        = 12,
3881     DARWIN_CPU_TYPE_POWERPC    = 18
3882   };
3883 
3884   Triple::ArchType Arch = TT.getArch();
3885   if (Arch == Triple::x86_64)
3886     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3887   else if (Arch == Triple::x86)
3888     CPUType = DARWIN_CPU_TYPE_X86;
3889   else if (Arch == Triple::ppc)
3890     CPUType = DARWIN_CPU_TYPE_POWERPC;
3891   else if (Arch == Triple::ppc64)
3892     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3893   else if (Arch == Triple::arm || Arch == Triple::thumb)
3894     CPUType = DARWIN_CPU_TYPE_ARM;
3895 
3896   // Traditional Bitcode starts after header.
3897   assert(Buffer.size() >= BWH_HeaderSize &&
3898          "Expected header size to be reserved");
3899   unsigned BCOffset = BWH_HeaderSize;
3900   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3901 
3902   // Write the magic and version.
3903   unsigned Position = 0;
3904   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
3905   writeInt32ToBuffer(0, Buffer, Position); // Version.
3906   writeInt32ToBuffer(BCOffset, Buffer, Position);
3907   writeInt32ToBuffer(BCSize, Buffer, Position);
3908   writeInt32ToBuffer(CPUType, Buffer, Position);
3909 
3910   // If the file is not a multiple of 16 bytes, insert dummy padding.
3911   while (Buffer.size() & 15)
3912     Buffer.push_back(0);
3913 }
3914 
3915 /// Helper to write the header common to all bitcode files.
3916 static void writeBitcodeHeader(BitstreamWriter &Stream) {
3917   // Emit the file header.
3918   Stream.Emit((unsigned)'B', 8);
3919   Stream.Emit((unsigned)'C', 8);
3920   Stream.Emit(0x0, 4);
3921   Stream.Emit(0xC, 4);
3922   Stream.Emit(0xE, 4);
3923   Stream.Emit(0xD, 4);
3924 }
3925 
3926 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
3927     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
3928   writeBitcodeHeader(*Stream);
3929 }
3930 
3931 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
3932 
3933 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
3934   Stream->EnterSubblock(Block, 3);
3935 
3936   auto Abbv = std::make_shared<BitCodeAbbrev>();
3937   Abbv->Add(BitCodeAbbrevOp(Record));
3938   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
3939   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
3940 
3941   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
3942 
3943   Stream->ExitBlock();
3944 }
3945 
3946 void BitcodeWriter::writeSymtab() {
3947   assert(!WroteStrtab && !WroteSymtab);
3948 
3949   // If any module has module-level inline asm, we will require a registered asm
3950   // parser for the target so that we can create an accurate symbol table for
3951   // the module.
3952   for (Module *M : Mods) {
3953     if (M->getModuleInlineAsm().empty())
3954       continue;
3955 
3956     std::string Err;
3957     const Triple TT(M->getTargetTriple());
3958     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
3959     if (!T || !T->hasMCAsmParser())
3960       return;
3961   }
3962 
3963   WroteSymtab = true;
3964   SmallVector<char, 0> Symtab;
3965   // The irsymtab::build function may be unable to create a symbol table if the
3966   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
3967   // table is not required for correctness, but we still want to be able to
3968   // write malformed modules to bitcode files, so swallow the error.
3969   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
3970     consumeError(std::move(E));
3971     return;
3972   }
3973 
3974   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
3975             {Symtab.data(), Symtab.size()});
3976 }
3977 
3978 void BitcodeWriter::writeStrtab() {
3979   assert(!WroteStrtab);
3980 
3981   std::vector<char> Strtab;
3982   StrtabBuilder.finalizeInOrder();
3983   Strtab.resize(StrtabBuilder.getSize());
3984   StrtabBuilder.write((uint8_t *)Strtab.data());
3985 
3986   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
3987             {Strtab.data(), Strtab.size()});
3988 
3989   WroteStrtab = true;
3990 }
3991 
3992 void BitcodeWriter::copyStrtab(StringRef Strtab) {
3993   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
3994   WroteStrtab = true;
3995 }
3996 
3997 void BitcodeWriter::writeModule(const Module *M,
3998                                 bool ShouldPreserveUseListOrder,
3999                                 const ModuleSummaryIndex *Index,
4000                                 bool GenerateHash, ModuleHash *ModHash) {
4001   assert(!WroteStrtab);
4002 
4003   // The Mods vector is used by irsymtab::build, which requires non-const
4004   // Modules in case it needs to materialize metadata. But the bitcode writer
4005   // requires that the module is materialized, so we can cast to non-const here,
4006   // after checking that it is in fact materialized.
4007   assert(M->isMaterialized());
4008   Mods.push_back(const_cast<Module *>(M));
4009 
4010   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4011                                    ShouldPreserveUseListOrder, Index,
4012                                    GenerateHash, ModHash);
4013   ModuleWriter.write();
4014 }
4015 
4016 void BitcodeWriter::writeIndex(
4017     const ModuleSummaryIndex *Index,
4018     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4019   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4020                                  ModuleToSummariesForIndex);
4021   IndexWriter.write();
4022 }
4023 
4024 /// WriteBitcodeToFile - Write the specified module to the specified output
4025 /// stream.
4026 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
4027                               bool ShouldPreserveUseListOrder,
4028                               const ModuleSummaryIndex *Index,
4029                               bool GenerateHash, ModuleHash *ModHash) {
4030   SmallVector<char, 0> Buffer;
4031   Buffer.reserve(256*1024);
4032 
4033   // If this is darwin or another generic macho target, reserve space for the
4034   // header.
4035   Triple TT(M->getTargetTriple());
4036   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4037     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4038 
4039   BitcodeWriter Writer(Buffer);
4040   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4041                      ModHash);
4042   Writer.writeSymtab();
4043   Writer.writeStrtab();
4044 
4045   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4046     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4047 
4048   // Write the generated bitstream to "Out".
4049   Out.write((char*)&Buffer.front(), Buffer.size());
4050 }
4051 
4052 void IndexBitcodeWriter::write() {
4053   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4054 
4055   writeModuleVersion();
4056 
4057   // Write the module paths in the combined index.
4058   writeModStrings();
4059 
4060   // Write the summary combined index records.
4061   writeCombinedGlobalValueSummary();
4062 
4063   Stream.ExitBlock();
4064 }
4065 
4066 // Write the specified module summary index to the given raw output stream,
4067 // where it will be written in a new bitcode block. This is used when
4068 // writing the combined index file for ThinLTO. When writing a subset of the
4069 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4070 void llvm::WriteIndexToFile(
4071     const ModuleSummaryIndex &Index, raw_ostream &Out,
4072     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4073   SmallVector<char, 0> Buffer;
4074   Buffer.reserve(256 * 1024);
4075 
4076   BitcodeWriter Writer(Buffer);
4077   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4078   Writer.writeStrtab();
4079 
4080   Out.write((char *)&Buffer.front(), Buffer.size());
4081 }
4082 
4083 namespace {
4084 
4085 /// Class to manage the bitcode writing for a thin link bitcode file.
4086 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4087   /// ModHash is for use in ThinLTO incremental build, generated while writing
4088   /// the module bitcode file.
4089   const ModuleHash *ModHash;
4090 
4091 public:
4092   ThinLinkBitcodeWriter(const Module *M, StringTableBuilder &StrtabBuilder,
4093                         BitstreamWriter &Stream,
4094                         const ModuleSummaryIndex &Index,
4095                         const ModuleHash &ModHash)
4096       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4097                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4098         ModHash(&ModHash) {}
4099 
4100   void write();
4101 
4102 private:
4103   void writeSimplifiedModuleInfo();
4104 };
4105 
4106 } // end anonymous namespace
4107 
4108 // This function writes a simpilified module info for thin link bitcode file.
4109 // It only contains the source file name along with the name(the offset and
4110 // size in strtab) and linkage for global values. For the global value info
4111 // entry, in order to keep linkage at offset 5, there are three zeros used
4112 // as padding.
4113 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4114   SmallVector<unsigned, 64> Vals;
4115   // Emit the module's source file name.
4116   {
4117     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4118     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4119     if (Bits == SE_Char6)
4120       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4121     else if (Bits == SE_Fixed7)
4122       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4123 
4124     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4125     auto Abbv = std::make_shared<BitCodeAbbrev>();
4126     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4127     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4128     Abbv->Add(AbbrevOpToUse);
4129     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4130 
4131     for (const auto P : M.getSourceFileName())
4132       Vals.push_back((unsigned char)P);
4133 
4134     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4135     Vals.clear();
4136   }
4137 
4138   // Emit the global variable information.
4139   for (const GlobalVariable &GV : M.globals()) {
4140     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4141     Vals.push_back(StrtabBuilder.add(GV.getName()));
4142     Vals.push_back(GV.getName().size());
4143     Vals.push_back(0);
4144     Vals.push_back(0);
4145     Vals.push_back(0);
4146     Vals.push_back(getEncodedLinkage(GV));
4147 
4148     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4149     Vals.clear();
4150   }
4151 
4152   // Emit the function proto information.
4153   for (const Function &F : M) {
4154     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4155     Vals.push_back(StrtabBuilder.add(F.getName()));
4156     Vals.push_back(F.getName().size());
4157     Vals.push_back(0);
4158     Vals.push_back(0);
4159     Vals.push_back(0);
4160     Vals.push_back(getEncodedLinkage(F));
4161 
4162     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4163     Vals.clear();
4164   }
4165 
4166   // Emit the alias information.
4167   for (const GlobalAlias &A : M.aliases()) {
4168     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4169     Vals.push_back(StrtabBuilder.add(A.getName()));
4170     Vals.push_back(A.getName().size());
4171     Vals.push_back(0);
4172     Vals.push_back(0);
4173     Vals.push_back(0);
4174     Vals.push_back(getEncodedLinkage(A));
4175 
4176     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4177     Vals.clear();
4178   }
4179 
4180   // Emit the ifunc information.
4181   for (const GlobalIFunc &I : M.ifuncs()) {
4182     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4183     Vals.push_back(StrtabBuilder.add(I.getName()));
4184     Vals.push_back(I.getName().size());
4185     Vals.push_back(0);
4186     Vals.push_back(0);
4187     Vals.push_back(0);
4188     Vals.push_back(getEncodedLinkage(I));
4189 
4190     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4191     Vals.clear();
4192   }
4193 }
4194 
4195 void ThinLinkBitcodeWriter::write() {
4196   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4197 
4198   writeModuleVersion();
4199 
4200   writeSimplifiedModuleInfo();
4201 
4202   writePerModuleGlobalValueSummary();
4203 
4204   // Write module hash.
4205   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4206 
4207   Stream.ExitBlock();
4208 }
4209 
4210 void BitcodeWriter::writeThinLinkBitcode(const Module *M,
4211                                          const ModuleSummaryIndex &Index,
4212                                          const ModuleHash &ModHash) {
4213   assert(!WroteStrtab);
4214 
4215   // The Mods vector is used by irsymtab::build, which requires non-const
4216   // Modules in case it needs to materialize metadata. But the bitcode writer
4217   // requires that the module is materialized, so we can cast to non-const here,
4218   // after checking that it is in fact materialized.
4219   assert(M->isMaterialized());
4220   Mods.push_back(const_cast<Module *>(M));
4221 
4222   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4223                                        ModHash);
4224   ThinLinkWriter.write();
4225 }
4226 
4227 // Write the specified thin link bitcode file to the given raw output stream,
4228 // where it will be written in a new bitcode block. This is used when
4229 // writing the per-module index file for ThinLTO.
4230 void llvm::WriteThinLinkBitcodeToFile(const Module *M, raw_ostream &Out,
4231                                       const ModuleSummaryIndex &Index,
4232                                       const ModuleHash &ModHash) {
4233   SmallVector<char, 0> Buffer;
4234   Buffer.reserve(256 * 1024);
4235 
4236   BitcodeWriter Writer(Buffer);
4237   Writer.writeThinLinkBitcode(M, Index, ModHash);
4238   Writer.writeSymtab();
4239   Writer.writeStrtab();
4240 
4241   Out.write((char *)&Buffer.front(), Buffer.size());
4242 }
4243