xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 4595a915f6d1e782e3e297eb611cbcac46af9bcb)
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   RawFlags |= (Flags.DSOLocal << 2);
959 
960   // Linkage don't need to be remapped at that time for the summary. Any future
961   // change to the getEncodedLinkage() function will need to be taken into
962   // account here as well.
963   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
964 
965   return RawFlags;
966 }
967 
968 static unsigned getEncodedVisibility(const GlobalValue &GV) {
969   switch (GV.getVisibility()) {
970   case GlobalValue::DefaultVisibility:   return 0;
971   case GlobalValue::HiddenVisibility:    return 1;
972   case GlobalValue::ProtectedVisibility: return 2;
973   }
974   llvm_unreachable("Invalid visibility");
975 }
976 
977 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
978   switch (GV.getDLLStorageClass()) {
979   case GlobalValue::DefaultStorageClass:   return 0;
980   case GlobalValue::DLLImportStorageClass: return 1;
981   case GlobalValue::DLLExportStorageClass: return 2;
982   }
983   llvm_unreachable("Invalid DLL storage class");
984 }
985 
986 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
987   switch (GV.getThreadLocalMode()) {
988     case GlobalVariable::NotThreadLocal:         return 0;
989     case GlobalVariable::GeneralDynamicTLSModel: return 1;
990     case GlobalVariable::LocalDynamicTLSModel:   return 2;
991     case GlobalVariable::InitialExecTLSModel:    return 3;
992     case GlobalVariable::LocalExecTLSModel:      return 4;
993   }
994   llvm_unreachable("Invalid TLS model");
995 }
996 
997 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
998   switch (C.getSelectionKind()) {
999   case Comdat::Any:
1000     return bitc::COMDAT_SELECTION_KIND_ANY;
1001   case Comdat::ExactMatch:
1002     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1003   case Comdat::Largest:
1004     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1005   case Comdat::NoDuplicates:
1006     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1007   case Comdat::SameSize:
1008     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1009   }
1010   llvm_unreachable("Invalid selection kind");
1011 }
1012 
1013 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1014   switch (GV.getUnnamedAddr()) {
1015   case GlobalValue::UnnamedAddr::None:   return 0;
1016   case GlobalValue::UnnamedAddr::Local:  return 2;
1017   case GlobalValue::UnnamedAddr::Global: return 1;
1018   }
1019   llvm_unreachable("Invalid unnamed_addr");
1020 }
1021 
1022 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1023   if (GenerateHash)
1024     Hasher.update(Str);
1025   return StrtabBuilder.add(Str);
1026 }
1027 
1028 void ModuleBitcodeWriter::writeComdats() {
1029   SmallVector<unsigned, 64> Vals;
1030   for (const Comdat *C : VE.getComdats()) {
1031     // COMDAT: [strtab offset, strtab size, selection_kind]
1032     Vals.push_back(addToStrtab(C->getName()));
1033     Vals.push_back(C->getName().size());
1034     Vals.push_back(getEncodedComdatSelectionKind(*C));
1035     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1036     Vals.clear();
1037   }
1038 }
1039 
1040 /// Write a record that will eventually hold the word offset of the
1041 /// module-level VST. For now the offset is 0, which will be backpatched
1042 /// after the real VST is written. Saves the bit offset to backpatch.
1043 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1044   // Write a placeholder value in for the offset of the real VST,
1045   // which is written after the function blocks so that it can include
1046   // the offset of each function. The placeholder offset will be
1047   // updated when the real VST is written.
1048   auto Abbv = std::make_shared<BitCodeAbbrev>();
1049   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1050   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1051   // hold the real VST offset. Must use fixed instead of VBR as we don't
1052   // know how many VBR chunks to reserve ahead of time.
1053   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1054   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1055 
1056   // Emit the placeholder
1057   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1058   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1059 
1060   // Compute and save the bit offset to the placeholder, which will be
1061   // patched when the real VST is written. We can simply subtract the 32-bit
1062   // fixed size from the current bit number to get the location to backpatch.
1063   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1064 }
1065 
1066 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1067 
1068 /// Determine the encoding to use for the given string name and length.
1069 static StringEncoding getStringEncoding(StringRef Str) {
1070   bool isChar6 = true;
1071   for (char C : Str) {
1072     if (isChar6)
1073       isChar6 = BitCodeAbbrevOp::isChar6(C);
1074     if ((unsigned char)C & 128)
1075       // don't bother scanning the rest.
1076       return SE_Fixed8;
1077   }
1078   if (isChar6)
1079     return SE_Char6;
1080   return SE_Fixed7;
1081 }
1082 
1083 /// Emit top-level description of module, including target triple, inline asm,
1084 /// descriptors for global variables, and function prototype info.
1085 /// Returns the bit offset to backpatch with the location of the real VST.
1086 void ModuleBitcodeWriter::writeModuleInfo() {
1087   // Emit various pieces of data attached to a module.
1088   if (!M.getTargetTriple().empty())
1089     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1090                       0 /*TODO*/);
1091   const std::string &DL = M.getDataLayoutStr();
1092   if (!DL.empty())
1093     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1094   if (!M.getModuleInlineAsm().empty())
1095     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1096                       0 /*TODO*/);
1097 
1098   // Emit information about sections and GC, computing how many there are. Also
1099   // compute the maximum alignment value.
1100   std::map<std::string, unsigned> SectionMap;
1101   std::map<std::string, unsigned> GCMap;
1102   unsigned MaxAlignment = 0;
1103   unsigned MaxGlobalType = 0;
1104   for (const GlobalValue &GV : M.globals()) {
1105     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1106     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1107     if (GV.hasSection()) {
1108       // Give section names unique ID's.
1109       unsigned &Entry = SectionMap[GV.getSection()];
1110       if (!Entry) {
1111         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1112                           0 /*TODO*/);
1113         Entry = SectionMap.size();
1114       }
1115     }
1116   }
1117   for (const Function &F : M) {
1118     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1119     if (F.hasSection()) {
1120       // Give section names unique ID's.
1121       unsigned &Entry = SectionMap[F.getSection()];
1122       if (!Entry) {
1123         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1124                           0 /*TODO*/);
1125         Entry = SectionMap.size();
1126       }
1127     }
1128     if (F.hasGC()) {
1129       // Same for GC names.
1130       unsigned &Entry = GCMap[F.getGC()];
1131       if (!Entry) {
1132         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1133                           0 /*TODO*/);
1134         Entry = GCMap.size();
1135       }
1136     }
1137   }
1138 
1139   // Emit abbrev for globals, now that we know # sections and max alignment.
1140   unsigned SimpleGVarAbbrev = 0;
1141   if (!M.global_empty()) {
1142     // Add an abbrev for common globals with no visibility or thread localness.
1143     auto Abbv = std::make_shared<BitCodeAbbrev>();
1144     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1146     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1147     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1148                               Log2_32_Ceil(MaxGlobalType+1)));
1149     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1150                                                            //| explicitType << 1
1151                                                            //| constant
1152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1153     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1154     if (MaxAlignment == 0)                                 // Alignment.
1155       Abbv->Add(BitCodeAbbrevOp(0));
1156     else {
1157       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1158       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1159                                Log2_32_Ceil(MaxEncAlignment+1)));
1160     }
1161     if (SectionMap.empty())                                    // Section.
1162       Abbv->Add(BitCodeAbbrevOp(0));
1163     else
1164       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1165                                Log2_32_Ceil(SectionMap.size()+1)));
1166     // Don't bother emitting vis + thread local.
1167     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1168   }
1169 
1170   SmallVector<unsigned, 64> Vals;
1171   // Emit the module's source file name.
1172   {
1173     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1174     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1175     if (Bits == SE_Char6)
1176       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1177     else if (Bits == SE_Fixed7)
1178       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1179 
1180     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1181     auto Abbv = std::make_shared<BitCodeAbbrev>();
1182     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1183     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1184     Abbv->Add(AbbrevOpToUse);
1185     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1186 
1187     for (const auto P : M.getSourceFileName())
1188       Vals.push_back((unsigned char)P);
1189 
1190     // Emit the finished record.
1191     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1192     Vals.clear();
1193   }
1194 
1195   // Emit the global variable information.
1196   for (const GlobalVariable &GV : M.globals()) {
1197     unsigned AbbrevToUse = 0;
1198 
1199     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1200     //             linkage, alignment, section, visibility, threadlocal,
1201     //             unnamed_addr, externally_initialized, dllstorageclass,
1202     //             comdat, attributes, DSO_Local]
1203     Vals.push_back(addToStrtab(GV.getName()));
1204     Vals.push_back(GV.getName().size());
1205     Vals.push_back(VE.getTypeID(GV.getValueType()));
1206     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1207     Vals.push_back(GV.isDeclaration() ? 0 :
1208                    (VE.getValueID(GV.getInitializer()) + 1));
1209     Vals.push_back(getEncodedLinkage(GV));
1210     Vals.push_back(Log2_32(GV.getAlignment())+1);
1211     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1212     if (GV.isThreadLocal() ||
1213         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1214         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1215         GV.isExternallyInitialized() ||
1216         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1217         GV.hasComdat() ||
1218         GV.hasAttributes() ||
1219         GV.isDSOLocal()) {
1220       Vals.push_back(getEncodedVisibility(GV));
1221       Vals.push_back(getEncodedThreadLocalMode(GV));
1222       Vals.push_back(getEncodedUnnamedAddr(GV));
1223       Vals.push_back(GV.isExternallyInitialized());
1224       Vals.push_back(getEncodedDLLStorageClass(GV));
1225       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1226 
1227       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1228       Vals.push_back(VE.getAttributeListID(AL));
1229 
1230       Vals.push_back(GV.isDSOLocal());
1231     } else {
1232       AbbrevToUse = SimpleGVarAbbrev;
1233     }
1234 
1235     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1236     Vals.clear();
1237   }
1238 
1239   // Emit the function proto information.
1240   for (const Function &F : M) {
1241     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1242     //             linkage, paramattrs, alignment, section, visibility, gc,
1243     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1244     //             prefixdata, personalityfn, DSO_Local]
1245     Vals.push_back(addToStrtab(F.getName()));
1246     Vals.push_back(F.getName().size());
1247     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1248     Vals.push_back(F.getCallingConv());
1249     Vals.push_back(F.isDeclaration());
1250     Vals.push_back(getEncodedLinkage(F));
1251     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1252     Vals.push_back(Log2_32(F.getAlignment())+1);
1253     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1254     Vals.push_back(getEncodedVisibility(F));
1255     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1256     Vals.push_back(getEncodedUnnamedAddr(F));
1257     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1258                                        : 0);
1259     Vals.push_back(getEncodedDLLStorageClass(F));
1260     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1261     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1262                                      : 0);
1263     Vals.push_back(
1264         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1265 
1266     Vals.push_back(F.isDSOLocal());
1267     unsigned AbbrevToUse = 0;
1268     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1269     Vals.clear();
1270   }
1271 
1272   // Emit the alias information.
1273   for (const GlobalAlias &A : M.aliases()) {
1274     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1275     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1276     //         DSO_Local]
1277     Vals.push_back(addToStrtab(A.getName()));
1278     Vals.push_back(A.getName().size());
1279     Vals.push_back(VE.getTypeID(A.getValueType()));
1280     Vals.push_back(A.getType()->getAddressSpace());
1281     Vals.push_back(VE.getValueID(A.getAliasee()));
1282     Vals.push_back(getEncodedLinkage(A));
1283     Vals.push_back(getEncodedVisibility(A));
1284     Vals.push_back(getEncodedDLLStorageClass(A));
1285     Vals.push_back(getEncodedThreadLocalMode(A));
1286     Vals.push_back(getEncodedUnnamedAddr(A));
1287     Vals.push_back(A.isDSOLocal());
1288 
1289     unsigned AbbrevToUse = 0;
1290     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1291     Vals.clear();
1292   }
1293 
1294   // Emit the ifunc information.
1295   for (const GlobalIFunc &I : M.ifuncs()) {
1296     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1297     //         val#, linkage, visibility]
1298     Vals.push_back(addToStrtab(I.getName()));
1299     Vals.push_back(I.getName().size());
1300     Vals.push_back(VE.getTypeID(I.getValueType()));
1301     Vals.push_back(I.getType()->getAddressSpace());
1302     Vals.push_back(VE.getValueID(I.getResolver()));
1303     Vals.push_back(getEncodedLinkage(I));
1304     Vals.push_back(getEncodedVisibility(I));
1305     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1306     Vals.clear();
1307   }
1308 
1309   writeValueSymbolTableForwardDecl();
1310 }
1311 
1312 static uint64_t getOptimizationFlags(const Value *V) {
1313   uint64_t Flags = 0;
1314 
1315   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1316     if (OBO->hasNoSignedWrap())
1317       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1318     if (OBO->hasNoUnsignedWrap())
1319       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1320   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1321     if (PEO->isExact())
1322       Flags |= 1 << bitc::PEO_EXACT;
1323   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1324     if (FPMO->hasUnsafeAlgebra())
1325       Flags |= FastMathFlags::UnsafeAlgebra;
1326     if (FPMO->hasNoNaNs())
1327       Flags |= FastMathFlags::NoNaNs;
1328     if (FPMO->hasNoInfs())
1329       Flags |= FastMathFlags::NoInfs;
1330     if (FPMO->hasNoSignedZeros())
1331       Flags |= FastMathFlags::NoSignedZeros;
1332     if (FPMO->hasAllowReciprocal())
1333       Flags |= FastMathFlags::AllowReciprocal;
1334     if (FPMO->hasAllowContract())
1335       Flags |= FastMathFlags::AllowContract;
1336   }
1337 
1338   return Flags;
1339 }
1340 
1341 void ModuleBitcodeWriter::writeValueAsMetadata(
1342     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1343   // Mimic an MDNode with a value as one operand.
1344   Value *V = MD->getValue();
1345   Record.push_back(VE.getTypeID(V->getType()));
1346   Record.push_back(VE.getValueID(V));
1347   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1348   Record.clear();
1349 }
1350 
1351 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1352                                        SmallVectorImpl<uint64_t> &Record,
1353                                        unsigned Abbrev) {
1354   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1355     Metadata *MD = N->getOperand(i);
1356     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1357            "Unexpected function-local metadata");
1358     Record.push_back(VE.getMetadataOrNullID(MD));
1359   }
1360   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1361                                     : bitc::METADATA_NODE,
1362                     Record, Abbrev);
1363   Record.clear();
1364 }
1365 
1366 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1367   // Assume the column is usually under 128, and always output the inlined-at
1368   // location (it's never more expensive than building an array size 1).
1369   auto Abbv = std::make_shared<BitCodeAbbrev>();
1370   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1374   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1375   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1376   return Stream.EmitAbbrev(std::move(Abbv));
1377 }
1378 
1379 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1380                                           SmallVectorImpl<uint64_t> &Record,
1381                                           unsigned &Abbrev) {
1382   if (!Abbrev)
1383     Abbrev = createDILocationAbbrev();
1384 
1385   Record.push_back(N->isDistinct());
1386   Record.push_back(N->getLine());
1387   Record.push_back(N->getColumn());
1388   Record.push_back(VE.getMetadataID(N->getScope()));
1389   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1390 
1391   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1392   Record.clear();
1393 }
1394 
1395 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1396   // Assume the column is usually under 128, and always output the inlined-at
1397   // location (it's never more expensive than building an array size 1).
1398   auto Abbv = std::make_shared<BitCodeAbbrev>();
1399   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1400   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1401   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1402   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1403   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1404   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1405   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1406   return Stream.EmitAbbrev(std::move(Abbv));
1407 }
1408 
1409 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1410                                              SmallVectorImpl<uint64_t> &Record,
1411                                              unsigned &Abbrev) {
1412   if (!Abbrev)
1413     Abbrev = createGenericDINodeAbbrev();
1414 
1415   Record.push_back(N->isDistinct());
1416   Record.push_back(N->getTag());
1417   Record.push_back(0); // Per-tag version field; unused for now.
1418 
1419   for (auto &I : N->operands())
1420     Record.push_back(VE.getMetadataOrNullID(I));
1421 
1422   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1423   Record.clear();
1424 }
1425 
1426 static uint64_t rotateSign(int64_t I) {
1427   uint64_t U = I;
1428   return I < 0 ? ~(U << 1) : U << 1;
1429 }
1430 
1431 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1432                                           SmallVectorImpl<uint64_t> &Record,
1433                                           unsigned Abbrev) {
1434   Record.push_back(N->isDistinct());
1435   Record.push_back(N->getCount());
1436   Record.push_back(rotateSign(N->getLowerBound()));
1437 
1438   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1439   Record.clear();
1440 }
1441 
1442 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1443                                             SmallVectorImpl<uint64_t> &Record,
1444                                             unsigned Abbrev) {
1445   Record.push_back(N->isDistinct());
1446   Record.push_back(rotateSign(N->getValue()));
1447   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1448 
1449   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1450   Record.clear();
1451 }
1452 
1453 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1454                                            SmallVectorImpl<uint64_t> &Record,
1455                                            unsigned Abbrev) {
1456   Record.push_back(N->isDistinct());
1457   Record.push_back(N->getTag());
1458   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1459   Record.push_back(N->getSizeInBits());
1460   Record.push_back(N->getAlignInBits());
1461   Record.push_back(N->getEncoding());
1462 
1463   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1464   Record.clear();
1465 }
1466 
1467 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1468                                              SmallVectorImpl<uint64_t> &Record,
1469                                              unsigned Abbrev) {
1470   Record.push_back(N->isDistinct());
1471   Record.push_back(N->getTag());
1472   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1473   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1474   Record.push_back(N->getLine());
1475   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1476   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1477   Record.push_back(N->getSizeInBits());
1478   Record.push_back(N->getAlignInBits());
1479   Record.push_back(N->getOffsetInBits());
1480   Record.push_back(N->getFlags());
1481   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1482 
1483   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1484   // that there is no DWARF address space associated with DIDerivedType.
1485   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1486     Record.push_back(*DWARFAddressSpace + 1);
1487   else
1488     Record.push_back(0);
1489 
1490   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1491   Record.clear();
1492 }
1493 
1494 void ModuleBitcodeWriter::writeDICompositeType(
1495     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1496     unsigned Abbrev) {
1497   const unsigned IsNotUsedInOldTypeRef = 0x2;
1498   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1499   Record.push_back(N->getTag());
1500   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1501   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1502   Record.push_back(N->getLine());
1503   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1504   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1505   Record.push_back(N->getSizeInBits());
1506   Record.push_back(N->getAlignInBits());
1507   Record.push_back(N->getOffsetInBits());
1508   Record.push_back(N->getFlags());
1509   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1510   Record.push_back(N->getRuntimeLang());
1511   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1512   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1513   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1514 
1515   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1516   Record.clear();
1517 }
1518 
1519 void ModuleBitcodeWriter::writeDISubroutineType(
1520     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1521     unsigned Abbrev) {
1522   const unsigned HasNoOldTypeRefs = 0x2;
1523   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1524   Record.push_back(N->getFlags());
1525   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1526   Record.push_back(N->getCC());
1527 
1528   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1529   Record.clear();
1530 }
1531 
1532 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1533                                       SmallVectorImpl<uint64_t> &Record,
1534                                       unsigned Abbrev) {
1535   Record.push_back(N->isDistinct());
1536   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1537   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1538   Record.push_back(N->getChecksumKind());
1539   Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()));
1540 
1541   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1542   Record.clear();
1543 }
1544 
1545 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1546                                              SmallVectorImpl<uint64_t> &Record,
1547                                              unsigned Abbrev) {
1548   assert(N->isDistinct() && "Expected distinct compile units");
1549   Record.push_back(/* IsDistinct */ true);
1550   Record.push_back(N->getSourceLanguage());
1551   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1552   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1553   Record.push_back(N->isOptimized());
1554   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1555   Record.push_back(N->getRuntimeVersion());
1556   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1557   Record.push_back(N->getEmissionKind());
1558   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1559   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1560   Record.push_back(/* subprograms */ 0);
1561   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1562   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1563   Record.push_back(N->getDWOId());
1564   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1565   Record.push_back(N->getSplitDebugInlining());
1566   Record.push_back(N->getDebugInfoForProfiling());
1567   Record.push_back(N->getGnuPubnames());
1568 
1569   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1570   Record.clear();
1571 }
1572 
1573 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1574                                             SmallVectorImpl<uint64_t> &Record,
1575                                             unsigned Abbrev) {
1576   uint64_t HasUnitFlag = 1 << 1;
1577   Record.push_back(N->isDistinct() | HasUnitFlag);
1578   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1579   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1580   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1581   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1582   Record.push_back(N->getLine());
1583   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1584   Record.push_back(N->isLocalToUnit());
1585   Record.push_back(N->isDefinition());
1586   Record.push_back(N->getScopeLine());
1587   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1588   Record.push_back(N->getVirtuality());
1589   Record.push_back(N->getVirtualIndex());
1590   Record.push_back(N->getFlags());
1591   Record.push_back(N->isOptimized());
1592   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1593   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1594   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1595   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1596   Record.push_back(N->getThisAdjustment());
1597   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1598 
1599   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1600   Record.clear();
1601 }
1602 
1603 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1604                                               SmallVectorImpl<uint64_t> &Record,
1605                                               unsigned Abbrev) {
1606   Record.push_back(N->isDistinct());
1607   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1608   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1609   Record.push_back(N->getLine());
1610   Record.push_back(N->getColumn());
1611 
1612   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1613   Record.clear();
1614 }
1615 
1616 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1617     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1618     unsigned Abbrev) {
1619   Record.push_back(N->isDistinct());
1620   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1621   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1622   Record.push_back(N->getDiscriminator());
1623 
1624   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1625   Record.clear();
1626 }
1627 
1628 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1629                                            SmallVectorImpl<uint64_t> &Record,
1630                                            unsigned Abbrev) {
1631   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1632   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1633   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1634 
1635   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1636   Record.clear();
1637 }
1638 
1639 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1640                                        SmallVectorImpl<uint64_t> &Record,
1641                                        unsigned Abbrev) {
1642   Record.push_back(N->isDistinct());
1643   Record.push_back(N->getMacinfoType());
1644   Record.push_back(N->getLine());
1645   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1646   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1647 
1648   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1649   Record.clear();
1650 }
1651 
1652 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1653                                            SmallVectorImpl<uint64_t> &Record,
1654                                            unsigned Abbrev) {
1655   Record.push_back(N->isDistinct());
1656   Record.push_back(N->getMacinfoType());
1657   Record.push_back(N->getLine());
1658   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1659   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1660 
1661   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1662   Record.clear();
1663 }
1664 
1665 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1666                                         SmallVectorImpl<uint64_t> &Record,
1667                                         unsigned Abbrev) {
1668   Record.push_back(N->isDistinct());
1669   for (auto &I : N->operands())
1670     Record.push_back(VE.getMetadataOrNullID(I));
1671 
1672   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1673   Record.clear();
1674 }
1675 
1676 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1677     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1678     unsigned Abbrev) {
1679   Record.push_back(N->isDistinct());
1680   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1681   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1682 
1683   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1684   Record.clear();
1685 }
1686 
1687 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1688     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1689     unsigned Abbrev) {
1690   Record.push_back(N->isDistinct());
1691   Record.push_back(N->getTag());
1692   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1693   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1694   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1695 
1696   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1697   Record.clear();
1698 }
1699 
1700 void ModuleBitcodeWriter::writeDIGlobalVariable(
1701     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1702     unsigned Abbrev) {
1703   const uint64_t Version = 1 << 1;
1704   Record.push_back((uint64_t)N->isDistinct() | Version);
1705   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1706   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1707   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1708   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1709   Record.push_back(N->getLine());
1710   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1711   Record.push_back(N->isLocalToUnit());
1712   Record.push_back(N->isDefinition());
1713   Record.push_back(/* expr */ 0);
1714   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1715   Record.push_back(N->getAlignInBits());
1716 
1717   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1718   Record.clear();
1719 }
1720 
1721 void ModuleBitcodeWriter::writeDILocalVariable(
1722     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1723     unsigned Abbrev) {
1724   // In order to support all possible bitcode formats in BitcodeReader we need
1725   // to distinguish the following cases:
1726   // 1) Record has no artificial tag (Record[1]),
1727   //   has no obsolete inlinedAt field (Record[9]).
1728   //   In this case Record size will be 8, HasAlignment flag is false.
1729   // 2) Record has artificial tag (Record[1]),
1730   //   has no obsolete inlignedAt field (Record[9]).
1731   //   In this case Record size will be 9, HasAlignment flag is false.
1732   // 3) Record has both artificial tag (Record[1]) and
1733   //   obsolete inlignedAt field (Record[9]).
1734   //   In this case Record size will be 10, HasAlignment flag is false.
1735   // 4) Record has neither artificial tag, nor inlignedAt field, but
1736   //   HasAlignment flag is true and Record[8] contains alignment value.
1737   const uint64_t HasAlignmentFlag = 1 << 1;
1738   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1739   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1740   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1741   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1742   Record.push_back(N->getLine());
1743   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1744   Record.push_back(N->getArg());
1745   Record.push_back(N->getFlags());
1746   Record.push_back(N->getAlignInBits());
1747 
1748   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1749   Record.clear();
1750 }
1751 
1752 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1753                                             SmallVectorImpl<uint64_t> &Record,
1754                                             unsigned Abbrev) {
1755   Record.reserve(N->getElements().size() + 1);
1756   const uint64_t Version = 3 << 1;
1757   Record.push_back((uint64_t)N->isDistinct() | Version);
1758   Record.append(N->elements_begin(), N->elements_end());
1759 
1760   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1761   Record.clear();
1762 }
1763 
1764 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1765     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1766     unsigned Abbrev) {
1767   Record.push_back(N->isDistinct());
1768   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1769   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1770 
1771   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1772   Record.clear();
1773 }
1774 
1775 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1776                                               SmallVectorImpl<uint64_t> &Record,
1777                                               unsigned Abbrev) {
1778   Record.push_back(N->isDistinct());
1779   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1780   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1781   Record.push_back(N->getLine());
1782   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1783   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1784   Record.push_back(N->getAttributes());
1785   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1786 
1787   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1788   Record.clear();
1789 }
1790 
1791 void ModuleBitcodeWriter::writeDIImportedEntity(
1792     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1793     unsigned Abbrev) {
1794   Record.push_back(N->isDistinct());
1795   Record.push_back(N->getTag());
1796   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1797   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1798   Record.push_back(N->getLine());
1799   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1800   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1801 
1802   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1803   Record.clear();
1804 }
1805 
1806 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1807   auto Abbv = std::make_shared<BitCodeAbbrev>();
1808   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1809   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1810   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1811   return Stream.EmitAbbrev(std::move(Abbv));
1812 }
1813 
1814 void ModuleBitcodeWriter::writeNamedMetadata(
1815     SmallVectorImpl<uint64_t> &Record) {
1816   if (M.named_metadata_empty())
1817     return;
1818 
1819   unsigned Abbrev = createNamedMetadataAbbrev();
1820   for (const NamedMDNode &NMD : M.named_metadata()) {
1821     // Write name.
1822     StringRef Str = NMD.getName();
1823     Record.append(Str.bytes_begin(), Str.bytes_end());
1824     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1825     Record.clear();
1826 
1827     // Write named metadata operands.
1828     for (const MDNode *N : NMD.operands())
1829       Record.push_back(VE.getMetadataID(N));
1830     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1831     Record.clear();
1832   }
1833 }
1834 
1835 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1836   auto Abbv = std::make_shared<BitCodeAbbrev>();
1837   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1838   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1839   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1840   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1841   return Stream.EmitAbbrev(std::move(Abbv));
1842 }
1843 
1844 /// Write out a record for MDString.
1845 ///
1846 /// All the metadata strings in a metadata block are emitted in a single
1847 /// record.  The sizes and strings themselves are shoved into a blob.
1848 void ModuleBitcodeWriter::writeMetadataStrings(
1849     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1850   if (Strings.empty())
1851     return;
1852 
1853   // Start the record with the number of strings.
1854   Record.push_back(bitc::METADATA_STRINGS);
1855   Record.push_back(Strings.size());
1856 
1857   // Emit the sizes of the strings in the blob.
1858   SmallString<256> Blob;
1859   {
1860     BitstreamWriter W(Blob);
1861     for (const Metadata *MD : Strings)
1862       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1863     W.FlushToWord();
1864   }
1865 
1866   // Add the offset to the strings to the record.
1867   Record.push_back(Blob.size());
1868 
1869   // Add the strings to the blob.
1870   for (const Metadata *MD : Strings)
1871     Blob.append(cast<MDString>(MD)->getString());
1872 
1873   // Emit the final record.
1874   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1875   Record.clear();
1876 }
1877 
1878 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1879 enum MetadataAbbrev : unsigned {
1880 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1881 #include "llvm/IR/Metadata.def"
1882   LastPlusOne
1883 };
1884 
1885 void ModuleBitcodeWriter::writeMetadataRecords(
1886     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1887     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1888   if (MDs.empty())
1889     return;
1890 
1891   // Initialize MDNode abbreviations.
1892 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1893 #include "llvm/IR/Metadata.def"
1894 
1895   for (const Metadata *MD : MDs) {
1896     if (IndexPos)
1897       IndexPos->push_back(Stream.GetCurrentBitNo());
1898     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1899       assert(N->isResolved() && "Expected forward references to be resolved");
1900 
1901       switch (N->getMetadataID()) {
1902       default:
1903         llvm_unreachable("Invalid MDNode subclass");
1904 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1905   case Metadata::CLASS##Kind:                                                  \
1906     if (MDAbbrevs)                                                             \
1907       write##CLASS(cast<CLASS>(N), Record,                                     \
1908                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1909     else                                                                       \
1910       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1911     continue;
1912 #include "llvm/IR/Metadata.def"
1913       }
1914     }
1915     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1916   }
1917 }
1918 
1919 void ModuleBitcodeWriter::writeModuleMetadata() {
1920   if (!VE.hasMDs() && M.named_metadata_empty())
1921     return;
1922 
1923   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1924   SmallVector<uint64_t, 64> Record;
1925 
1926   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1927   // block and load any metadata.
1928   std::vector<unsigned> MDAbbrevs;
1929 
1930   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1931   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1932   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1933       createGenericDINodeAbbrev();
1934 
1935   auto Abbv = std::make_shared<BitCodeAbbrev>();
1936   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1937   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1938   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1939   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1940 
1941   Abbv = std::make_shared<BitCodeAbbrev>();
1942   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1943   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1944   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1945   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1946 
1947   // Emit MDStrings together upfront.
1948   writeMetadataStrings(VE.getMDStrings(), Record);
1949 
1950   // We only emit an index for the metadata record if we have more than a given
1951   // (naive) threshold of metadatas, otherwise it is not worth it.
1952   if (VE.getNonMDStrings().size() > IndexThreshold) {
1953     // Write a placeholder value in for the offset of the metadata index,
1954     // which is written after the records, so that it can include
1955     // the offset of each entry. The placeholder offset will be
1956     // updated after all records are emitted.
1957     uint64_t Vals[] = {0, 0};
1958     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
1959   }
1960 
1961   // Compute and save the bit offset to the current position, which will be
1962   // patched when we emit the index later. We can simply subtract the 64-bit
1963   // fixed size from the current bit number to get the location to backpatch.
1964   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
1965 
1966   // This index will contain the bitpos for each individual record.
1967   std::vector<uint64_t> IndexPos;
1968   IndexPos.reserve(VE.getNonMDStrings().size());
1969 
1970   // Write all the records
1971   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
1972 
1973   if (VE.getNonMDStrings().size() > IndexThreshold) {
1974     // Now that we have emitted all the records we will emit the index. But
1975     // first
1976     // backpatch the forward reference so that the reader can skip the records
1977     // efficiently.
1978     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
1979                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
1980 
1981     // Delta encode the index.
1982     uint64_t PreviousValue = IndexOffsetRecordBitPos;
1983     for (auto &Elt : IndexPos) {
1984       auto EltDelta = Elt - PreviousValue;
1985       PreviousValue = Elt;
1986       Elt = EltDelta;
1987     }
1988     // Emit the index record.
1989     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
1990     IndexPos.clear();
1991   }
1992 
1993   // Write the named metadata now.
1994   writeNamedMetadata(Record);
1995 
1996   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
1997     SmallVector<uint64_t, 4> Record;
1998     Record.push_back(VE.getValueID(&GO));
1999     pushGlobalMetadataAttachment(Record, GO);
2000     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2001   };
2002   for (const Function &F : M)
2003     if (F.isDeclaration() && F.hasMetadata())
2004       AddDeclAttachedMetadata(F);
2005   // FIXME: Only store metadata for declarations here, and move data for global
2006   // variable definitions to a separate block (PR28134).
2007   for (const GlobalVariable &GV : M.globals())
2008     if (GV.hasMetadata())
2009       AddDeclAttachedMetadata(GV);
2010 
2011   Stream.ExitBlock();
2012 }
2013 
2014 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2015   if (!VE.hasMDs())
2016     return;
2017 
2018   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2019   SmallVector<uint64_t, 64> Record;
2020   writeMetadataStrings(VE.getMDStrings(), Record);
2021   writeMetadataRecords(VE.getNonMDStrings(), Record);
2022   Stream.ExitBlock();
2023 }
2024 
2025 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2026     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2027   // [n x [id, mdnode]]
2028   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2029   GO.getAllMetadata(MDs);
2030   for (const auto &I : MDs) {
2031     Record.push_back(I.first);
2032     Record.push_back(VE.getMetadataID(I.second));
2033   }
2034 }
2035 
2036 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2037   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2038 
2039   SmallVector<uint64_t, 64> Record;
2040 
2041   if (F.hasMetadata()) {
2042     pushGlobalMetadataAttachment(Record, F);
2043     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2044     Record.clear();
2045   }
2046 
2047   // Write metadata attachments
2048   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2049   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2050   for (const BasicBlock &BB : F)
2051     for (const Instruction &I : BB) {
2052       MDs.clear();
2053       I.getAllMetadataOtherThanDebugLoc(MDs);
2054 
2055       // If no metadata, ignore instruction.
2056       if (MDs.empty()) continue;
2057 
2058       Record.push_back(VE.getInstructionID(&I));
2059 
2060       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2061         Record.push_back(MDs[i].first);
2062         Record.push_back(VE.getMetadataID(MDs[i].second));
2063       }
2064       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2065       Record.clear();
2066     }
2067 
2068   Stream.ExitBlock();
2069 }
2070 
2071 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2072   SmallVector<uint64_t, 64> Record;
2073 
2074   // Write metadata kinds
2075   // METADATA_KIND - [n x [id, name]]
2076   SmallVector<StringRef, 8> Names;
2077   M.getMDKindNames(Names);
2078 
2079   if (Names.empty()) return;
2080 
2081   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2082 
2083   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2084     Record.push_back(MDKindID);
2085     StringRef KName = Names[MDKindID];
2086     Record.append(KName.begin(), KName.end());
2087 
2088     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2089     Record.clear();
2090   }
2091 
2092   Stream.ExitBlock();
2093 }
2094 
2095 void ModuleBitcodeWriter::writeOperandBundleTags() {
2096   // Write metadata kinds
2097   //
2098   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2099   //
2100   // OPERAND_BUNDLE_TAG - [strchr x N]
2101 
2102   SmallVector<StringRef, 8> Tags;
2103   M.getOperandBundleTags(Tags);
2104 
2105   if (Tags.empty())
2106     return;
2107 
2108   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2109 
2110   SmallVector<uint64_t, 64> Record;
2111 
2112   for (auto Tag : Tags) {
2113     Record.append(Tag.begin(), Tag.end());
2114 
2115     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2116     Record.clear();
2117   }
2118 
2119   Stream.ExitBlock();
2120 }
2121 
2122 void ModuleBitcodeWriter::writeSyncScopeNames() {
2123   SmallVector<StringRef, 8> SSNs;
2124   M.getContext().getSyncScopeNames(SSNs);
2125   if (SSNs.empty())
2126     return;
2127 
2128   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2129 
2130   SmallVector<uint64_t, 64> Record;
2131   for (auto SSN : SSNs) {
2132     Record.append(SSN.begin(), SSN.end());
2133     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2134     Record.clear();
2135   }
2136 
2137   Stream.ExitBlock();
2138 }
2139 
2140 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2141   if ((int64_t)V >= 0)
2142     Vals.push_back(V << 1);
2143   else
2144     Vals.push_back((-V << 1) | 1);
2145 }
2146 
2147 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2148                                          bool isGlobal) {
2149   if (FirstVal == LastVal) return;
2150 
2151   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2152 
2153   unsigned AggregateAbbrev = 0;
2154   unsigned String8Abbrev = 0;
2155   unsigned CString7Abbrev = 0;
2156   unsigned CString6Abbrev = 0;
2157   // If this is a constant pool for the module, emit module-specific abbrevs.
2158   if (isGlobal) {
2159     // Abbrev for CST_CODE_AGGREGATE.
2160     auto Abbv = std::make_shared<BitCodeAbbrev>();
2161     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2162     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2163     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2164     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2165 
2166     // Abbrev for CST_CODE_STRING.
2167     Abbv = std::make_shared<BitCodeAbbrev>();
2168     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2169     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2170     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2171     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2172     // Abbrev for CST_CODE_CSTRING.
2173     Abbv = std::make_shared<BitCodeAbbrev>();
2174     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2175     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2177     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2178     // Abbrev for CST_CODE_CSTRING.
2179     Abbv = std::make_shared<BitCodeAbbrev>();
2180     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2181     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2182     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2183     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2184   }
2185 
2186   SmallVector<uint64_t, 64> Record;
2187 
2188   const ValueEnumerator::ValueList &Vals = VE.getValues();
2189   Type *LastTy = nullptr;
2190   for (unsigned i = FirstVal; i != LastVal; ++i) {
2191     const Value *V = Vals[i].first;
2192     // If we need to switch types, do so now.
2193     if (V->getType() != LastTy) {
2194       LastTy = V->getType();
2195       Record.push_back(VE.getTypeID(LastTy));
2196       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2197                         CONSTANTS_SETTYPE_ABBREV);
2198       Record.clear();
2199     }
2200 
2201     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2202       Record.push_back(unsigned(IA->hasSideEffects()) |
2203                        unsigned(IA->isAlignStack()) << 1 |
2204                        unsigned(IA->getDialect()&1) << 2);
2205 
2206       // Add the asm string.
2207       const std::string &AsmStr = IA->getAsmString();
2208       Record.push_back(AsmStr.size());
2209       Record.append(AsmStr.begin(), AsmStr.end());
2210 
2211       // Add the constraint string.
2212       const std::string &ConstraintStr = IA->getConstraintString();
2213       Record.push_back(ConstraintStr.size());
2214       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2215       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2216       Record.clear();
2217       continue;
2218     }
2219     const Constant *C = cast<Constant>(V);
2220     unsigned Code = -1U;
2221     unsigned AbbrevToUse = 0;
2222     if (C->isNullValue()) {
2223       Code = bitc::CST_CODE_NULL;
2224     } else if (isa<UndefValue>(C)) {
2225       Code = bitc::CST_CODE_UNDEF;
2226     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2227       if (IV->getBitWidth() <= 64) {
2228         uint64_t V = IV->getSExtValue();
2229         emitSignedInt64(Record, V);
2230         Code = bitc::CST_CODE_INTEGER;
2231         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2232       } else {                             // Wide integers, > 64 bits in size.
2233         // We have an arbitrary precision integer value to write whose
2234         // bit width is > 64. However, in canonical unsigned integer
2235         // format it is likely that the high bits are going to be zero.
2236         // So, we only write the number of active words.
2237         unsigned NWords = IV->getValue().getActiveWords();
2238         const uint64_t *RawWords = IV->getValue().getRawData();
2239         for (unsigned i = 0; i != NWords; ++i) {
2240           emitSignedInt64(Record, RawWords[i]);
2241         }
2242         Code = bitc::CST_CODE_WIDE_INTEGER;
2243       }
2244     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2245       Code = bitc::CST_CODE_FLOAT;
2246       Type *Ty = CFP->getType();
2247       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2248         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2249       } else if (Ty->isX86_FP80Ty()) {
2250         // api needed to prevent premature destruction
2251         // bits are not in the same order as a normal i80 APInt, compensate.
2252         APInt api = CFP->getValueAPF().bitcastToAPInt();
2253         const uint64_t *p = api.getRawData();
2254         Record.push_back((p[1] << 48) | (p[0] >> 16));
2255         Record.push_back(p[0] & 0xffffLL);
2256       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2257         APInt api = CFP->getValueAPF().bitcastToAPInt();
2258         const uint64_t *p = api.getRawData();
2259         Record.push_back(p[0]);
2260         Record.push_back(p[1]);
2261       } else {
2262         assert(0 && "Unknown FP type!");
2263       }
2264     } else if (isa<ConstantDataSequential>(C) &&
2265                cast<ConstantDataSequential>(C)->isString()) {
2266       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2267       // Emit constant strings specially.
2268       unsigned NumElts = Str->getNumElements();
2269       // If this is a null-terminated string, use the denser CSTRING encoding.
2270       if (Str->isCString()) {
2271         Code = bitc::CST_CODE_CSTRING;
2272         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2273       } else {
2274         Code = bitc::CST_CODE_STRING;
2275         AbbrevToUse = String8Abbrev;
2276       }
2277       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2278       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2279       for (unsigned i = 0; i != NumElts; ++i) {
2280         unsigned char V = Str->getElementAsInteger(i);
2281         Record.push_back(V);
2282         isCStr7 &= (V & 128) == 0;
2283         if (isCStrChar6)
2284           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2285       }
2286 
2287       if (isCStrChar6)
2288         AbbrevToUse = CString6Abbrev;
2289       else if (isCStr7)
2290         AbbrevToUse = CString7Abbrev;
2291     } else if (const ConstantDataSequential *CDS =
2292                   dyn_cast<ConstantDataSequential>(C)) {
2293       Code = bitc::CST_CODE_DATA;
2294       Type *EltTy = CDS->getType()->getElementType();
2295       if (isa<IntegerType>(EltTy)) {
2296         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2297           Record.push_back(CDS->getElementAsInteger(i));
2298       } else {
2299         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2300           Record.push_back(
2301               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2302       }
2303     } else if (isa<ConstantAggregate>(C)) {
2304       Code = bitc::CST_CODE_AGGREGATE;
2305       for (const Value *Op : C->operands())
2306         Record.push_back(VE.getValueID(Op));
2307       AbbrevToUse = AggregateAbbrev;
2308     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2309       switch (CE->getOpcode()) {
2310       default:
2311         if (Instruction::isCast(CE->getOpcode())) {
2312           Code = bitc::CST_CODE_CE_CAST;
2313           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2314           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2315           Record.push_back(VE.getValueID(C->getOperand(0)));
2316           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2317         } else {
2318           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2319           Code = bitc::CST_CODE_CE_BINOP;
2320           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2321           Record.push_back(VE.getValueID(C->getOperand(0)));
2322           Record.push_back(VE.getValueID(C->getOperand(1)));
2323           uint64_t Flags = getOptimizationFlags(CE);
2324           if (Flags != 0)
2325             Record.push_back(Flags);
2326         }
2327         break;
2328       case Instruction::GetElementPtr: {
2329         Code = bitc::CST_CODE_CE_GEP;
2330         const auto *GO = cast<GEPOperator>(C);
2331         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2332         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2333           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2334           Record.push_back((*Idx << 1) | GO->isInBounds());
2335         } else if (GO->isInBounds())
2336           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2337         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2338           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2339           Record.push_back(VE.getValueID(C->getOperand(i)));
2340         }
2341         break;
2342       }
2343       case Instruction::Select:
2344         Code = bitc::CST_CODE_CE_SELECT;
2345         Record.push_back(VE.getValueID(C->getOperand(0)));
2346         Record.push_back(VE.getValueID(C->getOperand(1)));
2347         Record.push_back(VE.getValueID(C->getOperand(2)));
2348         break;
2349       case Instruction::ExtractElement:
2350         Code = bitc::CST_CODE_CE_EXTRACTELT;
2351         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2352         Record.push_back(VE.getValueID(C->getOperand(0)));
2353         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2354         Record.push_back(VE.getValueID(C->getOperand(1)));
2355         break;
2356       case Instruction::InsertElement:
2357         Code = bitc::CST_CODE_CE_INSERTELT;
2358         Record.push_back(VE.getValueID(C->getOperand(0)));
2359         Record.push_back(VE.getValueID(C->getOperand(1)));
2360         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2361         Record.push_back(VE.getValueID(C->getOperand(2)));
2362         break;
2363       case Instruction::ShuffleVector:
2364         // If the return type and argument types are the same, this is a
2365         // standard shufflevector instruction.  If the types are different,
2366         // then the shuffle is widening or truncating the input vectors, and
2367         // the argument type must also be encoded.
2368         if (C->getType() == C->getOperand(0)->getType()) {
2369           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2370         } else {
2371           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2372           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2373         }
2374         Record.push_back(VE.getValueID(C->getOperand(0)));
2375         Record.push_back(VE.getValueID(C->getOperand(1)));
2376         Record.push_back(VE.getValueID(C->getOperand(2)));
2377         break;
2378       case Instruction::ICmp:
2379       case Instruction::FCmp:
2380         Code = bitc::CST_CODE_CE_CMP;
2381         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2382         Record.push_back(VE.getValueID(C->getOperand(0)));
2383         Record.push_back(VE.getValueID(C->getOperand(1)));
2384         Record.push_back(CE->getPredicate());
2385         break;
2386       }
2387     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2388       Code = bitc::CST_CODE_BLOCKADDRESS;
2389       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2390       Record.push_back(VE.getValueID(BA->getFunction()));
2391       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2392     } else {
2393 #ifndef NDEBUG
2394       C->dump();
2395 #endif
2396       llvm_unreachable("Unknown constant!");
2397     }
2398     Stream.EmitRecord(Code, Record, AbbrevToUse);
2399     Record.clear();
2400   }
2401 
2402   Stream.ExitBlock();
2403 }
2404 
2405 void ModuleBitcodeWriter::writeModuleConstants() {
2406   const ValueEnumerator::ValueList &Vals = VE.getValues();
2407 
2408   // Find the first constant to emit, which is the first non-globalvalue value.
2409   // We know globalvalues have been emitted by WriteModuleInfo.
2410   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2411     if (!isa<GlobalValue>(Vals[i].first)) {
2412       writeConstants(i, Vals.size(), true);
2413       return;
2414     }
2415   }
2416 }
2417 
2418 /// pushValueAndType - The file has to encode both the value and type id for
2419 /// many values, because we need to know what type to create for forward
2420 /// references.  However, most operands are not forward references, so this type
2421 /// field is not needed.
2422 ///
2423 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2424 /// instruction ID, then it is a forward reference, and it also includes the
2425 /// type ID.  The value ID that is written is encoded relative to the InstID.
2426 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2427                                            SmallVectorImpl<unsigned> &Vals) {
2428   unsigned ValID = VE.getValueID(V);
2429   // Make encoding relative to the InstID.
2430   Vals.push_back(InstID - ValID);
2431   if (ValID >= InstID) {
2432     Vals.push_back(VE.getTypeID(V->getType()));
2433     return true;
2434   }
2435   return false;
2436 }
2437 
2438 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2439                                               unsigned InstID) {
2440   SmallVector<unsigned, 64> Record;
2441   LLVMContext &C = CS.getInstruction()->getContext();
2442 
2443   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2444     const auto &Bundle = CS.getOperandBundleAt(i);
2445     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2446 
2447     for (auto &Input : Bundle.Inputs)
2448       pushValueAndType(Input, InstID, Record);
2449 
2450     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2451     Record.clear();
2452   }
2453 }
2454 
2455 /// pushValue - Like pushValueAndType, but where the type of the value is
2456 /// omitted (perhaps it was already encoded in an earlier operand).
2457 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2458                                     SmallVectorImpl<unsigned> &Vals) {
2459   unsigned ValID = VE.getValueID(V);
2460   Vals.push_back(InstID - ValID);
2461 }
2462 
2463 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2464                                           SmallVectorImpl<uint64_t> &Vals) {
2465   unsigned ValID = VE.getValueID(V);
2466   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2467   emitSignedInt64(Vals, diff);
2468 }
2469 
2470 /// WriteInstruction - Emit an instruction to the specified stream.
2471 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2472                                            unsigned InstID,
2473                                            SmallVectorImpl<unsigned> &Vals) {
2474   unsigned Code = 0;
2475   unsigned AbbrevToUse = 0;
2476   VE.setInstructionID(&I);
2477   switch (I.getOpcode()) {
2478   default:
2479     if (Instruction::isCast(I.getOpcode())) {
2480       Code = bitc::FUNC_CODE_INST_CAST;
2481       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2482         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2483       Vals.push_back(VE.getTypeID(I.getType()));
2484       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2485     } else {
2486       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2487       Code = bitc::FUNC_CODE_INST_BINOP;
2488       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2489         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2490       pushValue(I.getOperand(1), InstID, Vals);
2491       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2492       uint64_t Flags = getOptimizationFlags(&I);
2493       if (Flags != 0) {
2494         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2495           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2496         Vals.push_back(Flags);
2497       }
2498     }
2499     break;
2500 
2501   case Instruction::GetElementPtr: {
2502     Code = bitc::FUNC_CODE_INST_GEP;
2503     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2504     auto &GEPInst = cast<GetElementPtrInst>(I);
2505     Vals.push_back(GEPInst.isInBounds());
2506     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2507     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2508       pushValueAndType(I.getOperand(i), InstID, Vals);
2509     break;
2510   }
2511   case Instruction::ExtractValue: {
2512     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2513     pushValueAndType(I.getOperand(0), InstID, Vals);
2514     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2515     Vals.append(EVI->idx_begin(), EVI->idx_end());
2516     break;
2517   }
2518   case Instruction::InsertValue: {
2519     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2520     pushValueAndType(I.getOperand(0), InstID, Vals);
2521     pushValueAndType(I.getOperand(1), InstID, Vals);
2522     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2523     Vals.append(IVI->idx_begin(), IVI->idx_end());
2524     break;
2525   }
2526   case Instruction::Select:
2527     Code = bitc::FUNC_CODE_INST_VSELECT;
2528     pushValueAndType(I.getOperand(1), InstID, Vals);
2529     pushValue(I.getOperand(2), InstID, Vals);
2530     pushValueAndType(I.getOperand(0), InstID, Vals);
2531     break;
2532   case Instruction::ExtractElement:
2533     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2534     pushValueAndType(I.getOperand(0), InstID, Vals);
2535     pushValueAndType(I.getOperand(1), InstID, Vals);
2536     break;
2537   case Instruction::InsertElement:
2538     Code = bitc::FUNC_CODE_INST_INSERTELT;
2539     pushValueAndType(I.getOperand(0), InstID, Vals);
2540     pushValue(I.getOperand(1), InstID, Vals);
2541     pushValueAndType(I.getOperand(2), InstID, Vals);
2542     break;
2543   case Instruction::ShuffleVector:
2544     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2545     pushValueAndType(I.getOperand(0), InstID, Vals);
2546     pushValue(I.getOperand(1), InstID, Vals);
2547     pushValue(I.getOperand(2), InstID, Vals);
2548     break;
2549   case Instruction::ICmp:
2550   case Instruction::FCmp: {
2551     // compare returning Int1Ty or vector of Int1Ty
2552     Code = bitc::FUNC_CODE_INST_CMP2;
2553     pushValueAndType(I.getOperand(0), InstID, Vals);
2554     pushValue(I.getOperand(1), InstID, Vals);
2555     Vals.push_back(cast<CmpInst>(I).getPredicate());
2556     uint64_t Flags = getOptimizationFlags(&I);
2557     if (Flags != 0)
2558       Vals.push_back(Flags);
2559     break;
2560   }
2561 
2562   case Instruction::Ret:
2563     {
2564       Code = bitc::FUNC_CODE_INST_RET;
2565       unsigned NumOperands = I.getNumOperands();
2566       if (NumOperands == 0)
2567         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2568       else if (NumOperands == 1) {
2569         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2570           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2571       } else {
2572         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2573           pushValueAndType(I.getOperand(i), InstID, Vals);
2574       }
2575     }
2576     break;
2577   case Instruction::Br:
2578     {
2579       Code = bitc::FUNC_CODE_INST_BR;
2580       const BranchInst &II = cast<BranchInst>(I);
2581       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2582       if (II.isConditional()) {
2583         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2584         pushValue(II.getCondition(), InstID, Vals);
2585       }
2586     }
2587     break;
2588   case Instruction::Switch:
2589     {
2590       Code = bitc::FUNC_CODE_INST_SWITCH;
2591       const SwitchInst &SI = cast<SwitchInst>(I);
2592       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2593       pushValue(SI.getCondition(), InstID, Vals);
2594       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2595       for (auto Case : SI.cases()) {
2596         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2597         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2598       }
2599     }
2600     break;
2601   case Instruction::IndirectBr:
2602     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2603     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2604     // Encode the address operand as relative, but not the basic blocks.
2605     pushValue(I.getOperand(0), InstID, Vals);
2606     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2607       Vals.push_back(VE.getValueID(I.getOperand(i)));
2608     break;
2609 
2610   case Instruction::Invoke: {
2611     const InvokeInst *II = cast<InvokeInst>(&I);
2612     const Value *Callee = II->getCalledValue();
2613     FunctionType *FTy = II->getFunctionType();
2614 
2615     if (II->hasOperandBundles())
2616       writeOperandBundles(II, InstID);
2617 
2618     Code = bitc::FUNC_CODE_INST_INVOKE;
2619 
2620     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2621     Vals.push_back(II->getCallingConv() | 1 << 13);
2622     Vals.push_back(VE.getValueID(II->getNormalDest()));
2623     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2624     Vals.push_back(VE.getTypeID(FTy));
2625     pushValueAndType(Callee, InstID, Vals);
2626 
2627     // Emit value #'s for the fixed parameters.
2628     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2629       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2630 
2631     // Emit type/value pairs for varargs params.
2632     if (FTy->isVarArg()) {
2633       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2634            i != e; ++i)
2635         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2636     }
2637     break;
2638   }
2639   case Instruction::Resume:
2640     Code = bitc::FUNC_CODE_INST_RESUME;
2641     pushValueAndType(I.getOperand(0), InstID, Vals);
2642     break;
2643   case Instruction::CleanupRet: {
2644     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2645     const auto &CRI = cast<CleanupReturnInst>(I);
2646     pushValue(CRI.getCleanupPad(), InstID, Vals);
2647     if (CRI.hasUnwindDest())
2648       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2649     break;
2650   }
2651   case Instruction::CatchRet: {
2652     Code = bitc::FUNC_CODE_INST_CATCHRET;
2653     const auto &CRI = cast<CatchReturnInst>(I);
2654     pushValue(CRI.getCatchPad(), InstID, Vals);
2655     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2656     break;
2657   }
2658   case Instruction::CleanupPad:
2659   case Instruction::CatchPad: {
2660     const auto &FuncletPad = cast<FuncletPadInst>(I);
2661     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2662                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2663     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2664 
2665     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2666     Vals.push_back(NumArgOperands);
2667     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2668       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2669     break;
2670   }
2671   case Instruction::CatchSwitch: {
2672     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2673     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2674 
2675     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2676 
2677     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2678     Vals.push_back(NumHandlers);
2679     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2680       Vals.push_back(VE.getValueID(CatchPadBB));
2681 
2682     if (CatchSwitch.hasUnwindDest())
2683       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2684     break;
2685   }
2686   case Instruction::Unreachable:
2687     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2688     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2689     break;
2690 
2691   case Instruction::PHI: {
2692     const PHINode &PN = cast<PHINode>(I);
2693     Code = bitc::FUNC_CODE_INST_PHI;
2694     // With the newer instruction encoding, forward references could give
2695     // negative valued IDs.  This is most common for PHIs, so we use
2696     // signed VBRs.
2697     SmallVector<uint64_t, 128> Vals64;
2698     Vals64.push_back(VE.getTypeID(PN.getType()));
2699     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2700       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2701       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2702     }
2703     // Emit a Vals64 vector and exit.
2704     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2705     Vals64.clear();
2706     return;
2707   }
2708 
2709   case Instruction::LandingPad: {
2710     const LandingPadInst &LP = cast<LandingPadInst>(I);
2711     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2712     Vals.push_back(VE.getTypeID(LP.getType()));
2713     Vals.push_back(LP.isCleanup());
2714     Vals.push_back(LP.getNumClauses());
2715     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2716       if (LP.isCatch(I))
2717         Vals.push_back(LandingPadInst::Catch);
2718       else
2719         Vals.push_back(LandingPadInst::Filter);
2720       pushValueAndType(LP.getClause(I), InstID, Vals);
2721     }
2722     break;
2723   }
2724 
2725   case Instruction::Alloca: {
2726     Code = bitc::FUNC_CODE_INST_ALLOCA;
2727     const AllocaInst &AI = cast<AllocaInst>(I);
2728     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2729     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2730     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2731     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2732     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2733            "not enough bits for maximum alignment");
2734     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2735     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2736     AlignRecord |= 1 << 6;
2737     AlignRecord |= AI.isSwiftError() << 7;
2738     Vals.push_back(AlignRecord);
2739     break;
2740   }
2741 
2742   case Instruction::Load:
2743     if (cast<LoadInst>(I).isAtomic()) {
2744       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2745       pushValueAndType(I.getOperand(0), InstID, Vals);
2746     } else {
2747       Code = bitc::FUNC_CODE_INST_LOAD;
2748       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2749         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2750     }
2751     Vals.push_back(VE.getTypeID(I.getType()));
2752     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2753     Vals.push_back(cast<LoadInst>(I).isVolatile());
2754     if (cast<LoadInst>(I).isAtomic()) {
2755       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2756       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2757     }
2758     break;
2759   case Instruction::Store:
2760     if (cast<StoreInst>(I).isAtomic())
2761       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2762     else
2763       Code = bitc::FUNC_CODE_INST_STORE;
2764     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2765     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2766     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2767     Vals.push_back(cast<StoreInst>(I).isVolatile());
2768     if (cast<StoreInst>(I).isAtomic()) {
2769       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2770       Vals.push_back(
2771           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2772     }
2773     break;
2774   case Instruction::AtomicCmpXchg:
2775     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2776     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2777     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2778     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2779     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2780     Vals.push_back(
2781         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2782     Vals.push_back(
2783         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2784     Vals.push_back(
2785         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2786     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2787     break;
2788   case Instruction::AtomicRMW:
2789     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2790     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2791     pushValue(I.getOperand(1), InstID, Vals);        // val.
2792     Vals.push_back(
2793         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2794     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2795     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2796     Vals.push_back(
2797         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2798     break;
2799   case Instruction::Fence:
2800     Code = bitc::FUNC_CODE_INST_FENCE;
2801     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2802     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2803     break;
2804   case Instruction::Call: {
2805     const CallInst &CI = cast<CallInst>(I);
2806     FunctionType *FTy = CI.getFunctionType();
2807 
2808     if (CI.hasOperandBundles())
2809       writeOperandBundles(&CI, InstID);
2810 
2811     Code = bitc::FUNC_CODE_INST_CALL;
2812 
2813     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2814 
2815     unsigned Flags = getOptimizationFlags(&I);
2816     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2817                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2818                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2819                    1 << bitc::CALL_EXPLICIT_TYPE |
2820                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2821                    unsigned(Flags != 0) << bitc::CALL_FMF);
2822     if (Flags != 0)
2823       Vals.push_back(Flags);
2824 
2825     Vals.push_back(VE.getTypeID(FTy));
2826     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2827 
2828     // Emit value #'s for the fixed parameters.
2829     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2830       // Check for labels (can happen with asm labels).
2831       if (FTy->getParamType(i)->isLabelTy())
2832         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2833       else
2834         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2835     }
2836 
2837     // Emit type/value pairs for varargs params.
2838     if (FTy->isVarArg()) {
2839       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2840            i != e; ++i)
2841         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2842     }
2843     break;
2844   }
2845   case Instruction::VAArg:
2846     Code = bitc::FUNC_CODE_INST_VAARG;
2847     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2848     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2849     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2850     break;
2851   }
2852 
2853   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2854   Vals.clear();
2855 }
2856 
2857 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2858 /// to allow clients to efficiently find the function body.
2859 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2860   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2861   // Get the offset of the VST we are writing, and backpatch it into
2862   // the VST forward declaration record.
2863   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2864   // The BitcodeStartBit was the stream offset of the identification block.
2865   VSTOffset -= bitcodeStartBit();
2866   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2867   // Note that we add 1 here because the offset is relative to one word
2868   // before the start of the identification block, which was historically
2869   // always the start of the regular bitcode header.
2870   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2871 
2872   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2873 
2874   auto Abbv = std::make_shared<BitCodeAbbrev>();
2875   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2876   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2877   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2878   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2879 
2880   for (const Function &F : M) {
2881     uint64_t Record[2];
2882 
2883     if (F.isDeclaration())
2884       continue;
2885 
2886     Record[0] = VE.getValueID(&F);
2887 
2888     // Save the word offset of the function (from the start of the
2889     // actual bitcode written to the stream).
2890     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2891     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2892     // Note that we add 1 here because the offset is relative to one word
2893     // before the start of the identification block, which was historically
2894     // always the start of the regular bitcode header.
2895     Record[1] = BitcodeIndex / 32 + 1;
2896 
2897     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2898   }
2899 
2900   Stream.ExitBlock();
2901 }
2902 
2903 /// Emit names for arguments, instructions and basic blocks in a function.
2904 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2905     const ValueSymbolTable &VST) {
2906   if (VST.empty())
2907     return;
2908 
2909   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2910 
2911   // FIXME: Set up the abbrev, we know how many values there are!
2912   // FIXME: We know if the type names can use 7-bit ascii.
2913   SmallVector<uint64_t, 64> NameVals;
2914 
2915   for (const ValueName &Name : VST) {
2916     // Figure out the encoding to use for the name.
2917     StringEncoding Bits = getStringEncoding(Name.getKey());
2918 
2919     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2920     NameVals.push_back(VE.getValueID(Name.getValue()));
2921 
2922     // VST_CODE_ENTRY:   [valueid, namechar x N]
2923     // VST_CODE_BBENTRY: [bbid, namechar x N]
2924     unsigned Code;
2925     if (isa<BasicBlock>(Name.getValue())) {
2926       Code = bitc::VST_CODE_BBENTRY;
2927       if (Bits == SE_Char6)
2928         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2929     } else {
2930       Code = bitc::VST_CODE_ENTRY;
2931       if (Bits == SE_Char6)
2932         AbbrevToUse = VST_ENTRY_6_ABBREV;
2933       else if (Bits == SE_Fixed7)
2934         AbbrevToUse = VST_ENTRY_7_ABBREV;
2935     }
2936 
2937     for (const auto P : Name.getKey())
2938       NameVals.push_back((unsigned char)P);
2939 
2940     // Emit the finished record.
2941     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2942     NameVals.clear();
2943   }
2944 
2945   Stream.ExitBlock();
2946 }
2947 
2948 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
2949   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2950   unsigned Code;
2951   if (isa<BasicBlock>(Order.V))
2952     Code = bitc::USELIST_CODE_BB;
2953   else
2954     Code = bitc::USELIST_CODE_DEFAULT;
2955 
2956   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2957   Record.push_back(VE.getValueID(Order.V));
2958   Stream.EmitRecord(Code, Record);
2959 }
2960 
2961 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
2962   assert(VE.shouldPreserveUseListOrder() &&
2963          "Expected to be preserving use-list order");
2964 
2965   auto hasMore = [&]() {
2966     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2967   };
2968   if (!hasMore())
2969     // Nothing to do.
2970     return;
2971 
2972   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2973   while (hasMore()) {
2974     writeUseList(std::move(VE.UseListOrders.back()));
2975     VE.UseListOrders.pop_back();
2976   }
2977   Stream.ExitBlock();
2978 }
2979 
2980 /// Emit a function body to the module stream.
2981 void ModuleBitcodeWriter::writeFunction(
2982     const Function &F,
2983     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2984   // Save the bitcode index of the start of this function block for recording
2985   // in the VST.
2986   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
2987 
2988   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2989   VE.incorporateFunction(F);
2990 
2991   SmallVector<unsigned, 64> Vals;
2992 
2993   // Emit the number of basic blocks, so the reader can create them ahead of
2994   // time.
2995   Vals.push_back(VE.getBasicBlocks().size());
2996   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2997   Vals.clear();
2998 
2999   // If there are function-local constants, emit them now.
3000   unsigned CstStart, CstEnd;
3001   VE.getFunctionConstantRange(CstStart, CstEnd);
3002   writeConstants(CstStart, CstEnd, false);
3003 
3004   // If there is function-local metadata, emit it now.
3005   writeFunctionMetadata(F);
3006 
3007   // Keep a running idea of what the instruction ID is.
3008   unsigned InstID = CstEnd;
3009 
3010   bool NeedsMetadataAttachment = F.hasMetadata();
3011 
3012   DILocation *LastDL = nullptr;
3013   // Finally, emit all the instructions, in order.
3014   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3015     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3016          I != E; ++I) {
3017       writeInstruction(*I, InstID, Vals);
3018 
3019       if (!I->getType()->isVoidTy())
3020         ++InstID;
3021 
3022       // If the instruction has metadata, write a metadata attachment later.
3023       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3024 
3025       // If the instruction has a debug location, emit it.
3026       DILocation *DL = I->getDebugLoc();
3027       if (!DL)
3028         continue;
3029 
3030       if (DL == LastDL) {
3031         // Just repeat the same debug loc as last time.
3032         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3033         continue;
3034       }
3035 
3036       Vals.push_back(DL->getLine());
3037       Vals.push_back(DL->getColumn());
3038       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3039       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3040       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3041       Vals.clear();
3042 
3043       LastDL = DL;
3044     }
3045 
3046   // Emit names for all the instructions etc.
3047   if (auto *Symtab = F.getValueSymbolTable())
3048     writeFunctionLevelValueSymbolTable(*Symtab);
3049 
3050   if (NeedsMetadataAttachment)
3051     writeFunctionMetadataAttachment(F);
3052   if (VE.shouldPreserveUseListOrder())
3053     writeUseListBlock(&F);
3054   VE.purgeFunction();
3055   Stream.ExitBlock();
3056 }
3057 
3058 // Emit blockinfo, which defines the standard abbreviations etc.
3059 void ModuleBitcodeWriter::writeBlockInfo() {
3060   // We only want to emit block info records for blocks that have multiple
3061   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3062   // Other blocks can define their abbrevs inline.
3063   Stream.EnterBlockInfoBlock();
3064 
3065   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3066     auto Abbv = std::make_shared<BitCodeAbbrev>();
3067     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3068     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3069     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3070     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3071     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3072         VST_ENTRY_8_ABBREV)
3073       llvm_unreachable("Unexpected abbrev ordering!");
3074   }
3075 
3076   { // 7-bit fixed width VST_CODE_ENTRY strings.
3077     auto Abbv = std::make_shared<BitCodeAbbrev>();
3078     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3079     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3080     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3081     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3082     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3083         VST_ENTRY_7_ABBREV)
3084       llvm_unreachable("Unexpected abbrev ordering!");
3085   }
3086   { // 6-bit char6 VST_CODE_ENTRY strings.
3087     auto Abbv = std::make_shared<BitCodeAbbrev>();
3088     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3089     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3090     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3091     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3092     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3093         VST_ENTRY_6_ABBREV)
3094       llvm_unreachable("Unexpected abbrev ordering!");
3095   }
3096   { // 6-bit char6 VST_CODE_BBENTRY strings.
3097     auto Abbv = std::make_shared<BitCodeAbbrev>();
3098     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3099     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3100     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3101     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3102     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3103         VST_BBENTRY_6_ABBREV)
3104       llvm_unreachable("Unexpected abbrev ordering!");
3105   }
3106 
3107   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3108     auto Abbv = std::make_shared<BitCodeAbbrev>();
3109     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3110     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3111                               VE.computeBitsRequiredForTypeIndicies()));
3112     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3113         CONSTANTS_SETTYPE_ABBREV)
3114       llvm_unreachable("Unexpected abbrev ordering!");
3115   }
3116 
3117   { // INTEGER abbrev for CONSTANTS_BLOCK.
3118     auto Abbv = std::make_shared<BitCodeAbbrev>();
3119     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3120     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3121     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3122         CONSTANTS_INTEGER_ABBREV)
3123       llvm_unreachable("Unexpected abbrev ordering!");
3124   }
3125 
3126   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3127     auto Abbv = std::make_shared<BitCodeAbbrev>();
3128     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3129     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3130     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3131                               VE.computeBitsRequiredForTypeIndicies()));
3132     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3133 
3134     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3135         CONSTANTS_CE_CAST_Abbrev)
3136       llvm_unreachable("Unexpected abbrev ordering!");
3137   }
3138   { // NULL abbrev for CONSTANTS_BLOCK.
3139     auto Abbv = std::make_shared<BitCodeAbbrev>();
3140     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3141     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3142         CONSTANTS_NULL_Abbrev)
3143       llvm_unreachable("Unexpected abbrev ordering!");
3144   }
3145 
3146   // FIXME: This should only use space for first class types!
3147 
3148   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3149     auto Abbv = std::make_shared<BitCodeAbbrev>();
3150     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3151     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3152     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3153                               VE.computeBitsRequiredForTypeIndicies()));
3154     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3156     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3157         FUNCTION_INST_LOAD_ABBREV)
3158       llvm_unreachable("Unexpected abbrev ordering!");
3159   }
3160   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3161     auto Abbv = std::make_shared<BitCodeAbbrev>();
3162     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3163     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3164     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3165     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3166     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3167         FUNCTION_INST_BINOP_ABBREV)
3168       llvm_unreachable("Unexpected abbrev ordering!");
3169   }
3170   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3171     auto Abbv = std::make_shared<BitCodeAbbrev>();
3172     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3173     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3175     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
3177     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3178         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3179       llvm_unreachable("Unexpected abbrev ordering!");
3180   }
3181   { // INST_CAST abbrev for FUNCTION_BLOCK.
3182     auto Abbv = std::make_shared<BitCodeAbbrev>();
3183     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3184     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3185     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3186                               VE.computeBitsRequiredForTypeIndicies()));
3187     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3188     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3189         FUNCTION_INST_CAST_ABBREV)
3190       llvm_unreachable("Unexpected abbrev ordering!");
3191   }
3192 
3193   { // INST_RET abbrev for FUNCTION_BLOCK.
3194     auto Abbv = std::make_shared<BitCodeAbbrev>();
3195     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3196     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3197         FUNCTION_INST_RET_VOID_ABBREV)
3198       llvm_unreachable("Unexpected abbrev ordering!");
3199   }
3200   { // INST_RET abbrev for FUNCTION_BLOCK.
3201     auto Abbv = std::make_shared<BitCodeAbbrev>();
3202     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3203     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3204     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3205         FUNCTION_INST_RET_VAL_ABBREV)
3206       llvm_unreachable("Unexpected abbrev ordering!");
3207   }
3208   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3209     auto Abbv = std::make_shared<BitCodeAbbrev>();
3210     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3211     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3212         FUNCTION_INST_UNREACHABLE_ABBREV)
3213       llvm_unreachable("Unexpected abbrev ordering!");
3214   }
3215   {
3216     auto Abbv = std::make_shared<BitCodeAbbrev>();
3217     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3218     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3220                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3222     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3223     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3224         FUNCTION_INST_GEP_ABBREV)
3225       llvm_unreachable("Unexpected abbrev ordering!");
3226   }
3227 
3228   Stream.ExitBlock();
3229 }
3230 
3231 /// Write the module path strings, currently only used when generating
3232 /// a combined index file.
3233 void IndexBitcodeWriter::writeModStrings() {
3234   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3235 
3236   // TODO: See which abbrev sizes we actually need to emit
3237 
3238   // 8-bit fixed-width MST_ENTRY strings.
3239   auto Abbv = std::make_shared<BitCodeAbbrev>();
3240   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3241   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3242   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3243   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3244   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3245 
3246   // 7-bit fixed width MST_ENTRY strings.
3247   Abbv = std::make_shared<BitCodeAbbrev>();
3248   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3249   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3250   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3251   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3252   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3253 
3254   // 6-bit char6 MST_ENTRY strings.
3255   Abbv = std::make_shared<BitCodeAbbrev>();
3256   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3257   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3258   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3259   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3260   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3261 
3262   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3263   Abbv = std::make_shared<BitCodeAbbrev>();
3264   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3265   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3266   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3267   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3268   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3269   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3270   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3271 
3272   SmallVector<unsigned, 64> Vals;
3273   forEachModule(
3274       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3275         StringRef Key = MPSE.getKey();
3276         const auto &Value = MPSE.getValue();
3277         StringEncoding Bits = getStringEncoding(Key);
3278         unsigned AbbrevToUse = Abbrev8Bit;
3279         if (Bits == SE_Char6)
3280           AbbrevToUse = Abbrev6Bit;
3281         else if (Bits == SE_Fixed7)
3282           AbbrevToUse = Abbrev7Bit;
3283 
3284         Vals.push_back(Value.first);
3285         Vals.append(Key.begin(), Key.end());
3286 
3287         // Emit the finished record.
3288         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3289 
3290         // Emit an optional hash for the module now
3291         const auto &Hash = Value.second;
3292         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3293           Vals.assign(Hash.begin(), Hash.end());
3294           // Emit the hash record.
3295           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3296         }
3297 
3298         Vals.clear();
3299       });
3300   Stream.ExitBlock();
3301 }
3302 
3303 /// Write the function type metadata related records that need to appear before
3304 /// a function summary entry (whether per-module or combined).
3305 static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
3306                                              FunctionSummary *FS) {
3307   if (!FS->type_tests().empty())
3308     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3309 
3310   SmallVector<uint64_t, 64> Record;
3311 
3312   auto WriteVFuncIdVec = [&](uint64_t Ty,
3313                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3314     if (VFs.empty())
3315       return;
3316     Record.clear();
3317     for (auto &VF : VFs) {
3318       Record.push_back(VF.GUID);
3319       Record.push_back(VF.Offset);
3320     }
3321     Stream.EmitRecord(Ty, Record);
3322   };
3323 
3324   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3325                   FS->type_test_assume_vcalls());
3326   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3327                   FS->type_checked_load_vcalls());
3328 
3329   auto WriteConstVCallVec = [&](uint64_t Ty,
3330                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3331     for (auto &VC : VCs) {
3332       Record.clear();
3333       Record.push_back(VC.VFunc.GUID);
3334       Record.push_back(VC.VFunc.Offset);
3335       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3336       Stream.EmitRecord(Ty, Record);
3337     }
3338   };
3339 
3340   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3341                      FS->type_test_assume_const_vcalls());
3342   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3343                      FS->type_checked_load_const_vcalls());
3344 }
3345 
3346 // Helper to emit a single function summary record.
3347 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3348     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3349     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3350     const Function &F) {
3351   NameVals.push_back(ValueID);
3352 
3353   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3354   writeFunctionTypeMetadataRecords(Stream, FS);
3355 
3356   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3357   NameVals.push_back(FS->instCount());
3358   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3359   NameVals.push_back(FS->refs().size());
3360 
3361   for (auto &RI : FS->refs())
3362     NameVals.push_back(VE.getValueID(RI.getValue()));
3363 
3364   bool HasProfileData = F.getEntryCount().hasValue();
3365   for (auto &ECI : FS->calls()) {
3366     NameVals.push_back(getValueId(ECI.first));
3367     if (HasProfileData)
3368       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3369   }
3370 
3371   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3372   unsigned Code =
3373       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
3374 
3375   // Emit the finished record.
3376   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3377   NameVals.clear();
3378 }
3379 
3380 // Collect the global value references in the given variable's initializer,
3381 // and emit them in a summary record.
3382 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3383     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3384     unsigned FSModRefsAbbrev) {
3385   auto VI = Index->getValueInfo(GlobalValue::getGUID(V.getName()));
3386   if (!VI || VI.getSummaryList().empty()) {
3387     // Only declarations should not have a summary (a declaration might however
3388     // have a summary if the def was in module level asm).
3389     assert(V.isDeclaration());
3390     return;
3391   }
3392   auto *Summary = VI.getSummaryList()[0].get();
3393   NameVals.push_back(VE.getValueID(&V));
3394   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3395   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3396 
3397   unsigned SizeBeforeRefs = NameVals.size();
3398   for (auto &RI : VS->refs())
3399     NameVals.push_back(VE.getValueID(RI.getValue()));
3400   // Sort the refs for determinism output, the vector returned by FS->refs() has
3401   // been initialized from a DenseSet.
3402   std::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3403 
3404   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3405                     FSModRefsAbbrev);
3406   NameVals.clear();
3407 }
3408 
3409 // Current version for the summary.
3410 // This is bumped whenever we introduce changes in the way some record are
3411 // interpreted, like flags for instance.
3412 static const uint64_t INDEX_VERSION = 4;
3413 
3414 /// Emit the per-module summary section alongside the rest of
3415 /// the module's bitcode.
3416 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3417   // By default we compile with ThinLTO if the module has a summary, but the
3418   // client can request full LTO with a module flag.
3419   bool IsThinLTO = true;
3420   if (auto *MD =
3421           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3422     IsThinLTO = MD->getZExtValue();
3423   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3424                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3425                        4);
3426 
3427   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3428 
3429   if (Index->begin() == Index->end()) {
3430     Stream.ExitBlock();
3431     return;
3432   }
3433 
3434   for (const auto &GVI : valueIds()) {
3435     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3436                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3437   }
3438 
3439   // Abbrev for FS_PERMODULE.
3440   auto Abbv = std::make_shared<BitCodeAbbrev>();
3441   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3442   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3443   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3444   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3445   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3446   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3447   // numrefs x valueid, n x (valueid)
3448   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3449   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3450   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3451 
3452   // Abbrev for FS_PERMODULE_PROFILE.
3453   Abbv = std::make_shared<BitCodeAbbrev>();
3454   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3455   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3456   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3457   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3458   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3459   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3460   // numrefs x valueid, n x (valueid, hotness)
3461   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3462   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3463   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3464 
3465   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3466   Abbv = std::make_shared<BitCodeAbbrev>();
3467   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3468   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3469   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3470   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3471   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3472   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3473 
3474   // Abbrev for FS_ALIAS.
3475   Abbv = std::make_shared<BitCodeAbbrev>();
3476   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3477   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3478   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3479   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3480   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3481 
3482   SmallVector<uint64_t, 64> NameVals;
3483   // Iterate over the list of functions instead of the Index to
3484   // ensure the ordering is stable.
3485   for (const Function &F : M) {
3486     // Summary emission does not support anonymous functions, they have to
3487     // renamed using the anonymous function renaming pass.
3488     if (!F.hasName())
3489       report_fatal_error("Unexpected anonymous function when writing summary");
3490 
3491     ValueInfo VI = Index->getValueInfo(GlobalValue::getGUID(F.getName()));
3492     if (!VI || VI.getSummaryList().empty()) {
3493       // Only declarations should not have a summary (a declaration might
3494       // however have a summary if the def was in module level asm).
3495       assert(F.isDeclaration());
3496       continue;
3497     }
3498     auto *Summary = VI.getSummaryList()[0].get();
3499     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3500                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3501   }
3502 
3503   // Capture references from GlobalVariable initializers, which are outside
3504   // of a function scope.
3505   for (const GlobalVariable &G : M.globals())
3506     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3507 
3508   for (const GlobalAlias &A : M.aliases()) {
3509     auto *Aliasee = A.getBaseObject();
3510     if (!Aliasee->hasName())
3511       // Nameless function don't have an entry in the summary, skip it.
3512       continue;
3513     auto AliasId = VE.getValueID(&A);
3514     auto AliaseeId = VE.getValueID(Aliasee);
3515     NameVals.push_back(AliasId);
3516     auto *Summary = Index->getGlobalValueSummary(A);
3517     AliasSummary *AS = cast<AliasSummary>(Summary);
3518     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3519     NameVals.push_back(AliaseeId);
3520     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3521     NameVals.clear();
3522   }
3523 
3524   Stream.ExitBlock();
3525 }
3526 
3527 /// Emit the combined summary section into the combined index file.
3528 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3529   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3530   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3531 
3532   for (const auto &GVI : valueIds()) {
3533     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3534                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3535   }
3536 
3537   // Abbrev for FS_COMBINED.
3538   auto Abbv = std::make_shared<BitCodeAbbrev>();
3539   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3540   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3541   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3542   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3543   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3544   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3545   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3546   // numrefs x valueid, n x (valueid)
3547   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3548   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3549   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3550 
3551   // Abbrev for FS_COMBINED_PROFILE.
3552   Abbv = std::make_shared<BitCodeAbbrev>();
3553   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3556   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3558   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3559   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3560   // numrefs x valueid, n x (valueid, hotness)
3561   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3562   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3563   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3564 
3565   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3566   Abbv = std::make_shared<BitCodeAbbrev>();
3567   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3568   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3569   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3570   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3571   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3572   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3573   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3574 
3575   // Abbrev for FS_COMBINED_ALIAS.
3576   Abbv = std::make_shared<BitCodeAbbrev>();
3577   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3578   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3579   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3580   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3581   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3582   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3583 
3584   // The aliases are emitted as a post-pass, and will point to the value
3585   // id of the aliasee. Save them in a vector for post-processing.
3586   SmallVector<AliasSummary *, 64> Aliases;
3587 
3588   // Save the value id for each summary for alias emission.
3589   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3590 
3591   SmallVector<uint64_t, 64> NameVals;
3592 
3593   // For local linkage, we also emit the original name separately
3594   // immediately after the record.
3595   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3596     if (!GlobalValue::isLocalLinkage(S.linkage()))
3597       return;
3598     NameVals.push_back(S.getOriginalName());
3599     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3600     NameVals.clear();
3601   };
3602 
3603   forEachSummary([&](GVInfo I) {
3604     GlobalValueSummary *S = I.second;
3605     assert(S);
3606 
3607     auto ValueId = getValueId(I.first);
3608     assert(ValueId);
3609     SummaryToValueIdMap[S] = *ValueId;
3610 
3611     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3612       // Will process aliases as a post-pass because the reader wants all
3613       // global to be loaded first.
3614       Aliases.push_back(AS);
3615       return;
3616     }
3617 
3618     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3619       NameVals.push_back(*ValueId);
3620       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3621       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3622       for (auto &RI : VS->refs()) {
3623         auto RefValueId = getValueId(RI.getGUID());
3624         if (!RefValueId)
3625           continue;
3626         NameVals.push_back(*RefValueId);
3627       }
3628 
3629       // Emit the finished record.
3630       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3631                         FSModRefsAbbrev);
3632       NameVals.clear();
3633       MaybeEmitOriginalName(*S);
3634       return;
3635     }
3636 
3637     auto *FS = cast<FunctionSummary>(S);
3638     writeFunctionTypeMetadataRecords(Stream, FS);
3639 
3640     NameVals.push_back(*ValueId);
3641     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3642     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3643     NameVals.push_back(FS->instCount());
3644     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3645     // Fill in below
3646     NameVals.push_back(0);
3647 
3648     unsigned Count = 0;
3649     for (auto &RI : FS->refs()) {
3650       auto RefValueId = getValueId(RI.getGUID());
3651       if (!RefValueId)
3652         continue;
3653       NameVals.push_back(*RefValueId);
3654       Count++;
3655     }
3656     NameVals[5] = Count;
3657 
3658     bool HasProfileData = false;
3659     for (auto &EI : FS->calls()) {
3660       HasProfileData |= EI.second.Hotness != CalleeInfo::HotnessType::Unknown;
3661       if (HasProfileData)
3662         break;
3663     }
3664 
3665     for (auto &EI : FS->calls()) {
3666       // If this GUID doesn't have a value id, it doesn't have a function
3667       // summary and we don't need to record any calls to it.
3668       GlobalValue::GUID GUID = EI.first.getGUID();
3669       auto CallValueId = getValueId(GUID);
3670       if (!CallValueId) {
3671         // For SamplePGO, the indirect call targets for local functions will
3672         // have its original name annotated in profile. We try to find the
3673         // corresponding PGOFuncName as the GUID.
3674         GUID = Index.getGUIDFromOriginalID(GUID);
3675         if (GUID == 0)
3676           continue;
3677         CallValueId = getValueId(GUID);
3678         if (!CallValueId)
3679           continue;
3680         // The mapping from OriginalId to GUID may return a GUID
3681         // that corresponds to a static variable. Filter it out here.
3682         // This can happen when
3683         // 1) There is a call to a library function which does not have
3684         // a CallValidId;
3685         // 2) There is a static variable with the  OriginalGUID identical
3686         // to the GUID of the library function in 1);
3687         // When this happens, the logic for SamplePGO kicks in and
3688         // the static variable in 2) will be found, which needs to be
3689         // filtered out.
3690         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3691         if (GVSum &&
3692             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3693           continue;
3694       }
3695       NameVals.push_back(*CallValueId);
3696       if (HasProfileData)
3697         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3698     }
3699 
3700     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3701     unsigned Code =
3702         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3703 
3704     // Emit the finished record.
3705     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3706     NameVals.clear();
3707     MaybeEmitOriginalName(*S);
3708   });
3709 
3710   for (auto *AS : Aliases) {
3711     auto AliasValueId = SummaryToValueIdMap[AS];
3712     assert(AliasValueId);
3713     NameVals.push_back(AliasValueId);
3714     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3715     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3716     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3717     assert(AliaseeValueId);
3718     NameVals.push_back(AliaseeValueId);
3719 
3720     // Emit the finished record.
3721     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3722     NameVals.clear();
3723     MaybeEmitOriginalName(*AS);
3724   }
3725 
3726   if (!Index.cfiFunctionDefs().empty()) {
3727     for (auto &S : Index.cfiFunctionDefs()) {
3728       NameVals.push_back(StrtabBuilder.add(S));
3729       NameVals.push_back(S.size());
3730     }
3731     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3732     NameVals.clear();
3733   }
3734 
3735   if (!Index.cfiFunctionDecls().empty()) {
3736     for (auto &S : Index.cfiFunctionDecls()) {
3737       NameVals.push_back(StrtabBuilder.add(S));
3738       NameVals.push_back(S.size());
3739     }
3740     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3741     NameVals.clear();
3742   }
3743 
3744   Stream.ExitBlock();
3745 }
3746 
3747 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3748 /// current llvm version, and a record for the epoch number.
3749 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3750   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3751 
3752   // Write the "user readable" string identifying the bitcode producer
3753   auto Abbv = std::make_shared<BitCodeAbbrev>();
3754   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3755   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3756   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3757   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3758   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3759                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3760 
3761   // Write the epoch version
3762   Abbv = std::make_shared<BitCodeAbbrev>();
3763   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3764   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3765   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3766   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3767   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3768   Stream.ExitBlock();
3769 }
3770 
3771 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3772   // Emit the module's hash.
3773   // MODULE_CODE_HASH: [5*i32]
3774   if (GenerateHash) {
3775     uint32_t Vals[5];
3776     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3777                                     Buffer.size() - BlockStartPos));
3778     StringRef Hash = Hasher.result();
3779     for (int Pos = 0; Pos < 20; Pos += 4) {
3780       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3781     }
3782 
3783     // Emit the finished record.
3784     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3785 
3786     if (ModHash)
3787       // Save the written hash value.
3788       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3789   }
3790 }
3791 
3792 void ModuleBitcodeWriter::write() {
3793   writeIdentificationBlock(Stream);
3794 
3795   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3796   size_t BlockStartPos = Buffer.size();
3797 
3798   writeModuleVersion();
3799 
3800   // Emit blockinfo, which defines the standard abbreviations etc.
3801   writeBlockInfo();
3802 
3803   // Emit information about attribute groups.
3804   writeAttributeGroupTable();
3805 
3806   // Emit information about parameter attributes.
3807   writeAttributeTable();
3808 
3809   // Emit information describing all of the types in the module.
3810   writeTypeTable();
3811 
3812   writeComdats();
3813 
3814   // Emit top-level description of module, including target triple, inline asm,
3815   // descriptors for global variables, and function prototype info.
3816   writeModuleInfo();
3817 
3818   // Emit constants.
3819   writeModuleConstants();
3820 
3821   // Emit metadata kind names.
3822   writeModuleMetadataKinds();
3823 
3824   // Emit metadata.
3825   writeModuleMetadata();
3826 
3827   // Emit module-level use-lists.
3828   if (VE.shouldPreserveUseListOrder())
3829     writeUseListBlock(nullptr);
3830 
3831   writeOperandBundleTags();
3832   writeSyncScopeNames();
3833 
3834   // Emit function bodies.
3835   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3836   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3837     if (!F->isDeclaration())
3838       writeFunction(*F, FunctionToBitcodeIndex);
3839 
3840   // Need to write after the above call to WriteFunction which populates
3841   // the summary information in the index.
3842   if (Index)
3843     writePerModuleGlobalValueSummary();
3844 
3845   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3846 
3847   writeModuleHash(BlockStartPos);
3848 
3849   Stream.ExitBlock();
3850 }
3851 
3852 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3853                                uint32_t &Position) {
3854   support::endian::write32le(&Buffer[Position], Value);
3855   Position += 4;
3856 }
3857 
3858 /// If generating a bc file on darwin, we have to emit a
3859 /// header and trailer to make it compatible with the system archiver.  To do
3860 /// this we emit the following header, and then emit a trailer that pads the
3861 /// file out to be a multiple of 16 bytes.
3862 ///
3863 /// struct bc_header {
3864 ///   uint32_t Magic;         // 0x0B17C0DE
3865 ///   uint32_t Version;       // Version, currently always 0.
3866 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3867 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3868 ///   uint32_t CPUType;       // CPU specifier.
3869 ///   ... potentially more later ...
3870 /// };
3871 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3872                                          const Triple &TT) {
3873   unsigned CPUType = ~0U;
3874 
3875   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3876   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3877   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3878   // specific constants here because they are implicitly part of the Darwin ABI.
3879   enum {
3880     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3881     DARWIN_CPU_TYPE_X86        = 7,
3882     DARWIN_CPU_TYPE_ARM        = 12,
3883     DARWIN_CPU_TYPE_POWERPC    = 18
3884   };
3885 
3886   Triple::ArchType Arch = TT.getArch();
3887   if (Arch == Triple::x86_64)
3888     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3889   else if (Arch == Triple::x86)
3890     CPUType = DARWIN_CPU_TYPE_X86;
3891   else if (Arch == Triple::ppc)
3892     CPUType = DARWIN_CPU_TYPE_POWERPC;
3893   else if (Arch == Triple::ppc64)
3894     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3895   else if (Arch == Triple::arm || Arch == Triple::thumb)
3896     CPUType = DARWIN_CPU_TYPE_ARM;
3897 
3898   // Traditional Bitcode starts after header.
3899   assert(Buffer.size() >= BWH_HeaderSize &&
3900          "Expected header size to be reserved");
3901   unsigned BCOffset = BWH_HeaderSize;
3902   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3903 
3904   // Write the magic and version.
3905   unsigned Position = 0;
3906   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
3907   writeInt32ToBuffer(0, Buffer, Position); // Version.
3908   writeInt32ToBuffer(BCOffset, Buffer, Position);
3909   writeInt32ToBuffer(BCSize, Buffer, Position);
3910   writeInt32ToBuffer(CPUType, Buffer, Position);
3911 
3912   // If the file is not a multiple of 16 bytes, insert dummy padding.
3913   while (Buffer.size() & 15)
3914     Buffer.push_back(0);
3915 }
3916 
3917 /// Helper to write the header common to all bitcode files.
3918 static void writeBitcodeHeader(BitstreamWriter &Stream) {
3919   // Emit the file header.
3920   Stream.Emit((unsigned)'B', 8);
3921   Stream.Emit((unsigned)'C', 8);
3922   Stream.Emit(0x0, 4);
3923   Stream.Emit(0xC, 4);
3924   Stream.Emit(0xE, 4);
3925   Stream.Emit(0xD, 4);
3926 }
3927 
3928 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
3929     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
3930   writeBitcodeHeader(*Stream);
3931 }
3932 
3933 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
3934 
3935 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
3936   Stream->EnterSubblock(Block, 3);
3937 
3938   auto Abbv = std::make_shared<BitCodeAbbrev>();
3939   Abbv->Add(BitCodeAbbrevOp(Record));
3940   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
3941   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
3942 
3943   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
3944 
3945   Stream->ExitBlock();
3946 }
3947 
3948 void BitcodeWriter::writeSymtab() {
3949   assert(!WroteStrtab && !WroteSymtab);
3950 
3951   // If any module has module-level inline asm, we will require a registered asm
3952   // parser for the target so that we can create an accurate symbol table for
3953   // the module.
3954   for (Module *M : Mods) {
3955     if (M->getModuleInlineAsm().empty())
3956       continue;
3957 
3958     std::string Err;
3959     const Triple TT(M->getTargetTriple());
3960     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
3961     if (!T || !T->hasMCAsmParser())
3962       return;
3963   }
3964 
3965   WroteSymtab = true;
3966   SmallVector<char, 0> Symtab;
3967   // The irsymtab::build function may be unable to create a symbol table if the
3968   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
3969   // table is not required for correctness, but we still want to be able to
3970   // write malformed modules to bitcode files, so swallow the error.
3971   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
3972     consumeError(std::move(E));
3973     return;
3974   }
3975 
3976   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
3977             {Symtab.data(), Symtab.size()});
3978 }
3979 
3980 void BitcodeWriter::writeStrtab() {
3981   assert(!WroteStrtab);
3982 
3983   std::vector<char> Strtab;
3984   StrtabBuilder.finalizeInOrder();
3985   Strtab.resize(StrtabBuilder.getSize());
3986   StrtabBuilder.write((uint8_t *)Strtab.data());
3987 
3988   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
3989             {Strtab.data(), Strtab.size()});
3990 
3991   WroteStrtab = true;
3992 }
3993 
3994 void BitcodeWriter::copyStrtab(StringRef Strtab) {
3995   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
3996   WroteStrtab = true;
3997 }
3998 
3999 void BitcodeWriter::writeModule(const Module *M,
4000                                 bool ShouldPreserveUseListOrder,
4001                                 const ModuleSummaryIndex *Index,
4002                                 bool GenerateHash, ModuleHash *ModHash) {
4003   assert(!WroteStrtab);
4004 
4005   // The Mods vector is used by irsymtab::build, which requires non-const
4006   // Modules in case it needs to materialize metadata. But the bitcode writer
4007   // requires that the module is materialized, so we can cast to non-const here,
4008   // after checking that it is in fact materialized.
4009   assert(M->isMaterialized());
4010   Mods.push_back(const_cast<Module *>(M));
4011 
4012   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4013                                    ShouldPreserveUseListOrder, Index,
4014                                    GenerateHash, ModHash);
4015   ModuleWriter.write();
4016 }
4017 
4018 void BitcodeWriter::writeIndex(
4019     const ModuleSummaryIndex *Index,
4020     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4021   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4022                                  ModuleToSummariesForIndex);
4023   IndexWriter.write();
4024 }
4025 
4026 /// WriteBitcodeToFile - Write the specified module to the specified output
4027 /// stream.
4028 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
4029                               bool ShouldPreserveUseListOrder,
4030                               const ModuleSummaryIndex *Index,
4031                               bool GenerateHash, ModuleHash *ModHash) {
4032   SmallVector<char, 0> Buffer;
4033   Buffer.reserve(256*1024);
4034 
4035   // If this is darwin or another generic macho target, reserve space for the
4036   // header.
4037   Triple TT(M->getTargetTriple());
4038   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4039     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4040 
4041   BitcodeWriter Writer(Buffer);
4042   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4043                      ModHash);
4044   Writer.writeSymtab();
4045   Writer.writeStrtab();
4046 
4047   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4048     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4049 
4050   // Write the generated bitstream to "Out".
4051   Out.write((char*)&Buffer.front(), Buffer.size());
4052 }
4053 
4054 void IndexBitcodeWriter::write() {
4055   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4056 
4057   writeModuleVersion();
4058 
4059   // Write the module paths in the combined index.
4060   writeModStrings();
4061 
4062   // Write the summary combined index records.
4063   writeCombinedGlobalValueSummary();
4064 
4065   Stream.ExitBlock();
4066 }
4067 
4068 // Write the specified module summary index to the given raw output stream,
4069 // where it will be written in a new bitcode block. This is used when
4070 // writing the combined index file for ThinLTO. When writing a subset of the
4071 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4072 void llvm::WriteIndexToFile(
4073     const ModuleSummaryIndex &Index, raw_ostream &Out,
4074     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4075   SmallVector<char, 0> Buffer;
4076   Buffer.reserve(256 * 1024);
4077 
4078   BitcodeWriter Writer(Buffer);
4079   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4080   Writer.writeStrtab();
4081 
4082   Out.write((char *)&Buffer.front(), Buffer.size());
4083 }
4084 
4085 namespace {
4086 
4087 /// Class to manage the bitcode writing for a thin link bitcode file.
4088 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4089   /// ModHash is for use in ThinLTO incremental build, generated while writing
4090   /// the module bitcode file.
4091   const ModuleHash *ModHash;
4092 
4093 public:
4094   ThinLinkBitcodeWriter(const Module *M, StringTableBuilder &StrtabBuilder,
4095                         BitstreamWriter &Stream,
4096                         const ModuleSummaryIndex &Index,
4097                         const ModuleHash &ModHash)
4098       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4099                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4100         ModHash(&ModHash) {}
4101 
4102   void write();
4103 
4104 private:
4105   void writeSimplifiedModuleInfo();
4106 };
4107 
4108 } // end anonymous namespace
4109 
4110 // This function writes a simpilified module info for thin link bitcode file.
4111 // It only contains the source file name along with the name(the offset and
4112 // size in strtab) and linkage for global values. For the global value info
4113 // entry, in order to keep linkage at offset 5, there are three zeros used
4114 // as padding.
4115 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4116   SmallVector<unsigned, 64> Vals;
4117   // Emit the module's source file name.
4118   {
4119     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4120     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4121     if (Bits == SE_Char6)
4122       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4123     else if (Bits == SE_Fixed7)
4124       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4125 
4126     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4127     auto Abbv = std::make_shared<BitCodeAbbrev>();
4128     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4129     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4130     Abbv->Add(AbbrevOpToUse);
4131     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4132 
4133     for (const auto P : M.getSourceFileName())
4134       Vals.push_back((unsigned char)P);
4135 
4136     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4137     Vals.clear();
4138   }
4139 
4140   // Emit the global variable information.
4141   for (const GlobalVariable &GV : M.globals()) {
4142     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4143     Vals.push_back(StrtabBuilder.add(GV.getName()));
4144     Vals.push_back(GV.getName().size());
4145     Vals.push_back(0);
4146     Vals.push_back(0);
4147     Vals.push_back(0);
4148     Vals.push_back(getEncodedLinkage(GV));
4149 
4150     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4151     Vals.clear();
4152   }
4153 
4154   // Emit the function proto information.
4155   for (const Function &F : M) {
4156     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4157     Vals.push_back(StrtabBuilder.add(F.getName()));
4158     Vals.push_back(F.getName().size());
4159     Vals.push_back(0);
4160     Vals.push_back(0);
4161     Vals.push_back(0);
4162     Vals.push_back(getEncodedLinkage(F));
4163 
4164     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4165     Vals.clear();
4166   }
4167 
4168   // Emit the alias information.
4169   for (const GlobalAlias &A : M.aliases()) {
4170     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4171     Vals.push_back(StrtabBuilder.add(A.getName()));
4172     Vals.push_back(A.getName().size());
4173     Vals.push_back(0);
4174     Vals.push_back(0);
4175     Vals.push_back(0);
4176     Vals.push_back(getEncodedLinkage(A));
4177 
4178     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4179     Vals.clear();
4180   }
4181 
4182   // Emit the ifunc information.
4183   for (const GlobalIFunc &I : M.ifuncs()) {
4184     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4185     Vals.push_back(StrtabBuilder.add(I.getName()));
4186     Vals.push_back(I.getName().size());
4187     Vals.push_back(0);
4188     Vals.push_back(0);
4189     Vals.push_back(0);
4190     Vals.push_back(getEncodedLinkage(I));
4191 
4192     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4193     Vals.clear();
4194   }
4195 }
4196 
4197 void ThinLinkBitcodeWriter::write() {
4198   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4199 
4200   writeModuleVersion();
4201 
4202   writeSimplifiedModuleInfo();
4203 
4204   writePerModuleGlobalValueSummary();
4205 
4206   // Write module hash.
4207   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4208 
4209   Stream.ExitBlock();
4210 }
4211 
4212 void BitcodeWriter::writeThinLinkBitcode(const Module *M,
4213                                          const ModuleSummaryIndex &Index,
4214                                          const ModuleHash &ModHash) {
4215   assert(!WroteStrtab);
4216 
4217   // The Mods vector is used by irsymtab::build, which requires non-const
4218   // Modules in case it needs to materialize metadata. But the bitcode writer
4219   // requires that the module is materialized, so we can cast to non-const here,
4220   // after checking that it is in fact materialized.
4221   assert(M->isMaterialized());
4222   Mods.push_back(const_cast<Module *>(M));
4223 
4224   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4225                                        ModHash);
4226   ThinLinkWriter.write();
4227 }
4228 
4229 // Write the specified thin link bitcode file to the given raw output stream,
4230 // where it will be written in a new bitcode block. This is used when
4231 // writing the per-module index file for ThinLTO.
4232 void llvm::WriteThinLinkBitcodeToFile(const Module *M, raw_ostream &Out,
4233                                       const ModuleSummaryIndex &Index,
4234                                       const ModuleHash &ModHash) {
4235   SmallVector<char, 0> Buffer;
4236   Buffer.reserve(256 * 1024);
4237 
4238   BitcodeWriter Writer(Buffer);
4239   Writer.writeThinLinkBitcode(M, Index, ModHash);
4240   Writer.writeSymtab();
4241   Writer.writeStrtab();
4242 
4243   Out.write((char *)&Buffer.front(), Buffer.size());
4244 }
4245