xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 6bcf2ba2f0fff179602fd60b5e0127cd20fc907e)
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/Config/llvm-config.h"
32 #include "llvm/IR/Attributes.h"
33 #include "llvm/IR/BasicBlock.h"
34 #include "llvm/IR/CallSite.h"
35 #include "llvm/IR/Comdat.h"
36 #include "llvm/IR/Constant.h"
37 #include "llvm/IR/Constants.h"
38 #include "llvm/IR/DebugInfoMetadata.h"
39 #include "llvm/IR/DebugLoc.h"
40 #include "llvm/IR/DerivedTypes.h"
41 #include "llvm/IR/Function.h"
42 #include "llvm/IR/GlobalAlias.h"
43 #include "llvm/IR/GlobalIFunc.h"
44 #include "llvm/IR/GlobalObject.h"
45 #include "llvm/IR/GlobalValue.h"
46 #include "llvm/IR/GlobalVariable.h"
47 #include "llvm/IR/InlineAsm.h"
48 #include "llvm/IR/InstrTypes.h"
49 #include "llvm/IR/Instruction.h"
50 #include "llvm/IR/Instructions.h"
51 #include "llvm/IR/LLVMContext.h"
52 #include "llvm/IR/Metadata.h"
53 #include "llvm/IR/Module.h"
54 #include "llvm/IR/ModuleSummaryIndex.h"
55 #include "llvm/IR/Operator.h"
56 #include "llvm/IR/Type.h"
57 #include "llvm/IR/UseListOrder.h"
58 #include "llvm/IR/Value.h"
59 #include "llvm/IR/ValueSymbolTable.h"
60 #include "llvm/MC/StringTableBuilder.h"
61 #include "llvm/Object/IRSymtab.h"
62 #include "llvm/Support/AtomicOrdering.h"
63 #include "llvm/Support/Casting.h"
64 #include "llvm/Support/CommandLine.h"
65 #include "llvm/Support/Endian.h"
66 #include "llvm/Support/Error.h"
67 #include "llvm/Support/ErrorHandling.h"
68 #include "llvm/Support/MathExtras.h"
69 #include "llvm/Support/SHA1.h"
70 #include "llvm/Support/TargetRegistry.h"
71 #include "llvm/Support/raw_ostream.h"
72 #include <algorithm>
73 #include <cassert>
74 #include <cstddef>
75 #include <cstdint>
76 #include <iterator>
77 #include <map>
78 #include <memory>
79 #include <string>
80 #include <utility>
81 #include <vector>
82 
83 using namespace llvm;
84 
85 static cl::opt<unsigned>
86     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
87                    cl::desc("Number of metadatas above which we emit an index "
88                             "to enable lazy-loading"));
89 
90 cl::opt<bool> WriteRelBFToSummary(
91     "write-relbf-to-summary", cl::Hidden, cl::init(false),
92     cl::desc("Write relative block frequency to function summary "));
93 
94 extern FunctionSummary::ForceSummaryHotnessType ForceSummaryEdgesCold;
95 
96 namespace {
97 
98 /// These are manifest constants used by the bitcode writer. They do not need to
99 /// be kept in sync with the reader, but need to be consistent within this file.
100 enum {
101   // VALUE_SYMTAB_BLOCK abbrev id's.
102   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
103   VST_ENTRY_7_ABBREV,
104   VST_ENTRY_6_ABBREV,
105   VST_BBENTRY_6_ABBREV,
106 
107   // CONSTANTS_BLOCK abbrev id's.
108   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
109   CONSTANTS_INTEGER_ABBREV,
110   CONSTANTS_CE_CAST_Abbrev,
111   CONSTANTS_NULL_Abbrev,
112 
113   // FUNCTION_BLOCK abbrev id's.
114   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
115   FUNCTION_INST_BINOP_ABBREV,
116   FUNCTION_INST_BINOP_FLAGS_ABBREV,
117   FUNCTION_INST_CAST_ABBREV,
118   FUNCTION_INST_RET_VOID_ABBREV,
119   FUNCTION_INST_RET_VAL_ABBREV,
120   FUNCTION_INST_UNREACHABLE_ABBREV,
121   FUNCTION_INST_GEP_ABBREV,
122 };
123 
124 /// Abstract class to manage the bitcode writing, subclassed for each bitcode
125 /// file type.
126 class BitcodeWriterBase {
127 protected:
128   /// The stream created and owned by the client.
129   BitstreamWriter &Stream;
130 
131   StringTableBuilder &StrtabBuilder;
132 
133 public:
134   /// Constructs a BitcodeWriterBase object that writes to the provided
135   /// \p Stream.
136   BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
137       : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
138 
139 protected:
140   void writeBitcodeHeader();
141   void writeModuleVersion();
142 };
143 
144 void BitcodeWriterBase::writeModuleVersion() {
145   // VERSION: [version#]
146   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
147 }
148 
149 /// Base class to manage the module bitcode writing, currently subclassed for
150 /// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
151 class ModuleBitcodeWriterBase : public BitcodeWriterBase {
152 protected:
153   /// The Module to write to bitcode.
154   const Module &M;
155 
156   /// Enumerates ids for all values in the module.
157   ValueEnumerator VE;
158 
159   /// Optional per-module index to write for ThinLTO.
160   const ModuleSummaryIndex *Index;
161 
162   /// Map that holds the correspondence between GUIDs in the summary index,
163   /// that came from indirect call profiles, and a value id generated by this
164   /// class to use in the VST and summary block records.
165   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
166 
167   /// Tracks the last value id recorded in the GUIDToValueMap.
168   unsigned GlobalValueId;
169 
170   /// Saves the offset of the VSTOffset record that must eventually be
171   /// backpatched with the offset of the actual VST.
172   uint64_t VSTOffsetPlaceholder = 0;
173 
174 public:
175   /// Constructs a ModuleBitcodeWriterBase object for the given Module,
176   /// writing to the provided \p Buffer.
177   ModuleBitcodeWriterBase(const Module &M, StringTableBuilder &StrtabBuilder,
178                           BitstreamWriter &Stream,
179                           bool ShouldPreserveUseListOrder,
180                           const ModuleSummaryIndex *Index)
181       : BitcodeWriterBase(Stream, StrtabBuilder), M(M),
182         VE(M, ShouldPreserveUseListOrder), Index(Index) {
183     // Assign ValueIds to any callee values in the index that came from
184     // indirect call profiles and were recorded as a GUID not a Value*
185     // (which would have been assigned an ID by the ValueEnumerator).
186     // The starting ValueId is just after the number of values in the
187     // ValueEnumerator, so that they can be emitted in the VST.
188     GlobalValueId = VE.getValues().size();
189     if (!Index)
190       return;
191     for (const auto &GUIDSummaryLists : *Index)
192       // Examine all summaries for this GUID.
193       for (auto &Summary : GUIDSummaryLists.second.SummaryList)
194         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
195           // For each call in the function summary, see if the call
196           // is to a GUID (which means it is for an indirect call,
197           // otherwise we would have a Value for it). If so, synthesize
198           // a value id.
199           for (auto &CallEdge : FS->calls())
200             if (!CallEdge.first.haveGVs() || !CallEdge.first.getValue())
201               assignValueId(CallEdge.first.getGUID());
202   }
203 
204 protected:
205   void writePerModuleGlobalValueSummary();
206 
207 private:
208   void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
209                                            GlobalValueSummary *Summary,
210                                            unsigned ValueID,
211                                            unsigned FSCallsAbbrev,
212                                            unsigned FSCallsProfileAbbrev,
213                                            const Function &F);
214   void writeModuleLevelReferences(const GlobalVariable &V,
215                                   SmallVector<uint64_t, 64> &NameVals,
216                                   unsigned FSModRefsAbbrev);
217 
218   void assignValueId(GlobalValue::GUID ValGUID) {
219     GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
220   }
221 
222   unsigned getValueId(GlobalValue::GUID ValGUID) {
223     const auto &VMI = GUIDToValueIdMap.find(ValGUID);
224     // Expect that any GUID value had a value Id assigned by an
225     // earlier call to assignValueId.
226     assert(VMI != GUIDToValueIdMap.end() &&
227            "GUID does not have assigned value Id");
228     return VMI->second;
229   }
230 
231   // Helper to get the valueId for the type of value recorded in VI.
232   unsigned getValueId(ValueInfo VI) {
233     if (!VI.haveGVs() || !VI.getValue())
234       return getValueId(VI.getGUID());
235     return VE.getValueID(VI.getValue());
236   }
237 
238   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
239 };
240 
241 /// Class to manage the bitcode writing for a module.
242 class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
243   /// Pointer to the buffer allocated by caller for bitcode writing.
244   const SmallVectorImpl<char> &Buffer;
245 
246   /// True if a module hash record should be written.
247   bool GenerateHash;
248 
249   /// If non-null, when GenerateHash is true, the resulting hash is written
250   /// into ModHash.
251   ModuleHash *ModHash;
252 
253   SHA1 Hasher;
254 
255   /// The start bit of the identification block.
256   uint64_t BitcodeStartBit;
257 
258 public:
259   /// Constructs a ModuleBitcodeWriter object for the given Module,
260   /// writing to the provided \p Buffer.
261   ModuleBitcodeWriter(const Module &M, SmallVectorImpl<char> &Buffer,
262                       StringTableBuilder &StrtabBuilder,
263                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
264                       const ModuleSummaryIndex *Index, bool GenerateHash,
265                       ModuleHash *ModHash = nullptr)
266       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
267                                 ShouldPreserveUseListOrder, Index),
268         Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
269         BitcodeStartBit(Stream.GetCurrentBitNo()) {}
270 
271   /// Emit the current module to the bitstream.
272   void write();
273 
274 private:
275   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
276 
277   size_t addToStrtab(StringRef Str);
278 
279   void writeAttributeGroupTable();
280   void writeAttributeTable();
281   void writeTypeTable();
282   void writeComdats();
283   void writeValueSymbolTableForwardDecl();
284   void writeModuleInfo();
285   void writeValueAsMetadata(const ValueAsMetadata *MD,
286                             SmallVectorImpl<uint64_t> &Record);
287   void writeMDTuple(const MDTuple *N, SmallVectorImpl<uint64_t> &Record,
288                     unsigned Abbrev);
289   unsigned createDILocationAbbrev();
290   void writeDILocation(const DILocation *N, SmallVectorImpl<uint64_t> &Record,
291                        unsigned &Abbrev);
292   unsigned createGenericDINodeAbbrev();
293   void writeGenericDINode(const GenericDINode *N,
294                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
295   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
296                        unsigned Abbrev);
297   void writeDIEnumerator(const DIEnumerator *N,
298                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
299   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
300                         unsigned Abbrev);
301   void writeDIDerivedType(const DIDerivedType *N,
302                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
303   void writeDICompositeType(const DICompositeType *N,
304                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
305   void writeDISubroutineType(const DISubroutineType *N,
306                              SmallVectorImpl<uint64_t> &Record,
307                              unsigned Abbrev);
308   void writeDIFile(const DIFile *N, SmallVectorImpl<uint64_t> &Record,
309                    unsigned Abbrev);
310   void writeDICompileUnit(const DICompileUnit *N,
311                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
312   void writeDISubprogram(const DISubprogram *N,
313                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
314   void writeDILexicalBlock(const DILexicalBlock *N,
315                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
316   void writeDILexicalBlockFile(const DILexicalBlockFile *N,
317                                SmallVectorImpl<uint64_t> &Record,
318                                unsigned Abbrev);
319   void writeDINamespace(const DINamespace *N, SmallVectorImpl<uint64_t> &Record,
320                         unsigned Abbrev);
321   void writeDIMacro(const DIMacro *N, SmallVectorImpl<uint64_t> &Record,
322                     unsigned Abbrev);
323   void writeDIMacroFile(const DIMacroFile *N, SmallVectorImpl<uint64_t> &Record,
324                         unsigned Abbrev);
325   void writeDIModule(const DIModule *N, SmallVectorImpl<uint64_t> &Record,
326                      unsigned Abbrev);
327   void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
328                                     SmallVectorImpl<uint64_t> &Record,
329                                     unsigned Abbrev);
330   void writeDITemplateValueParameter(const DITemplateValueParameter *N,
331                                      SmallVectorImpl<uint64_t> &Record,
332                                      unsigned Abbrev);
333   void writeDIGlobalVariable(const DIGlobalVariable *N,
334                              SmallVectorImpl<uint64_t> &Record,
335                              unsigned Abbrev);
336   void writeDILocalVariable(const DILocalVariable *N,
337                             SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
338   void writeDILabel(const DILabel *N,
339                     SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
340   void writeDIExpression(const DIExpression *N,
341                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
342   void writeDIGlobalVariableExpression(const DIGlobalVariableExpression *N,
343                                        SmallVectorImpl<uint64_t> &Record,
344                                        unsigned Abbrev);
345   void writeDIObjCProperty(const DIObjCProperty *N,
346                            SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
347   void writeDIImportedEntity(const DIImportedEntity *N,
348                              SmallVectorImpl<uint64_t> &Record,
349                              unsigned Abbrev);
350   unsigned createNamedMetadataAbbrev();
351   void writeNamedMetadata(SmallVectorImpl<uint64_t> &Record);
352   unsigned createMetadataStringsAbbrev();
353   void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
354                             SmallVectorImpl<uint64_t> &Record);
355   void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
356                             SmallVectorImpl<uint64_t> &Record,
357                             std::vector<unsigned> *MDAbbrevs = nullptr,
358                             std::vector<uint64_t> *IndexPos = nullptr);
359   void writeModuleMetadata();
360   void writeFunctionMetadata(const Function &F);
361   void writeFunctionMetadataAttachment(const Function &F);
362   void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
363   void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
364                                     const GlobalObject &GO);
365   void writeModuleMetadataKinds();
366   void writeOperandBundleTags();
367   void writeSyncScopeNames();
368   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
369   void writeModuleConstants();
370   bool pushValueAndType(const Value *V, unsigned InstID,
371                         SmallVectorImpl<unsigned> &Vals);
372   void writeOperandBundles(ImmutableCallSite CS, unsigned InstID);
373   void pushValue(const Value *V, unsigned InstID,
374                  SmallVectorImpl<unsigned> &Vals);
375   void pushValueSigned(const Value *V, unsigned InstID,
376                        SmallVectorImpl<uint64_t> &Vals);
377   void writeInstruction(const Instruction &I, unsigned InstID,
378                         SmallVectorImpl<unsigned> &Vals);
379   void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
380   void writeGlobalValueSymbolTable(
381       DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
382   void writeUseList(UseListOrder &&Order);
383   void writeUseListBlock(const Function *F);
384   void
385   writeFunction(const Function &F,
386                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
387   void writeBlockInfo();
388   void writeModuleHash(size_t BlockStartPos);
389 
390   unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
391     return unsigned(SSID);
392   }
393 };
394 
395 /// Class to manage the bitcode writing for a combined index.
396 class IndexBitcodeWriter : public BitcodeWriterBase {
397   /// The combined index to write to bitcode.
398   const ModuleSummaryIndex &Index;
399 
400   /// When writing a subset of the index for distributed backends, client
401   /// provides a map of modules to the corresponding GUIDs/summaries to write.
402   const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex;
403 
404   /// Map that holds the correspondence between the GUID used in the combined
405   /// index and a value id generated by this class to use in references.
406   std::map<GlobalValue::GUID, unsigned> GUIDToValueIdMap;
407 
408   /// Tracks the last value id recorded in the GUIDToValueMap.
409   unsigned GlobalValueId = 0;
410 
411 public:
412   /// Constructs a IndexBitcodeWriter object for the given combined index,
413   /// writing to the provided \p Buffer. When writing a subset of the index
414   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
415   IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
416                      const ModuleSummaryIndex &Index,
417                      const std::map<std::string, GVSummaryMapTy>
418                          *ModuleToSummariesForIndex = nullptr)
419       : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
420         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
421     // Assign unique value ids to all summaries to be written, for use
422     // in writing out the call graph edges. Save the mapping from GUID
423     // to the new global value id to use when writing those edges, which
424     // are currently saved in the index in terms of GUID.
425     forEachSummary([&](GVInfo I, bool) {
426       GUIDToValueIdMap[I.first] = ++GlobalValueId;
427     });
428   }
429 
430   /// The below iterator returns the GUID and associated summary.
431   using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
432 
433   /// Calls the callback for each value GUID and summary to be written to
434   /// bitcode. This hides the details of whether they are being pulled from the
435   /// entire index or just those in a provided ModuleToSummariesForIndex map.
436   template<typename Functor>
437   void forEachSummary(Functor Callback) {
438     if (ModuleToSummariesForIndex) {
439       for (auto &M : *ModuleToSummariesForIndex)
440         for (auto &Summary : M.second) {
441           Callback(Summary, false);
442           // Ensure aliasee is handled, e.g. for assigning a valueId,
443           // even if we are not importing the aliasee directly (the
444           // imported alias will contain a copy of aliasee).
445           if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
446             Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
447         }
448     } else {
449       for (auto &Summaries : Index)
450         for (auto &Summary : Summaries.second.SummaryList)
451           Callback({Summaries.first, Summary.get()}, false);
452     }
453   }
454 
455   /// Calls the callback for each entry in the modulePaths StringMap that
456   /// should be written to the module path string table. This hides the details
457   /// of whether they are being pulled from the entire index or just those in a
458   /// provided ModuleToSummariesForIndex map.
459   template <typename Functor> void forEachModule(Functor Callback) {
460     if (ModuleToSummariesForIndex) {
461       for (const auto &M : *ModuleToSummariesForIndex) {
462         const auto &MPI = Index.modulePaths().find(M.first);
463         if (MPI == Index.modulePaths().end()) {
464           // This should only happen if the bitcode file was empty, in which
465           // case we shouldn't be importing (the ModuleToSummariesForIndex
466           // would only include the module we are writing and index for).
467           assert(ModuleToSummariesForIndex->size() == 1);
468           continue;
469         }
470         Callback(*MPI);
471       }
472     } else {
473       for (const auto &MPSE : Index.modulePaths())
474         Callback(MPSE);
475     }
476   }
477 
478   /// Main entry point for writing a combined index to bitcode.
479   void write();
480 
481 private:
482   void writeModStrings();
483   void writeCombinedGlobalValueSummary();
484 
485   Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
486     auto VMI = GUIDToValueIdMap.find(ValGUID);
487     if (VMI == GUIDToValueIdMap.end())
488       return None;
489     return VMI->second;
490   }
491 
492   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
493 };
494 
495 } // end anonymous namespace
496 
497 static unsigned getEncodedCastOpcode(unsigned Opcode) {
498   switch (Opcode) {
499   default: llvm_unreachable("Unknown cast instruction!");
500   case Instruction::Trunc   : return bitc::CAST_TRUNC;
501   case Instruction::ZExt    : return bitc::CAST_ZEXT;
502   case Instruction::SExt    : return bitc::CAST_SEXT;
503   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
504   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
505   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
506   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
507   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
508   case Instruction::FPExt   : return bitc::CAST_FPEXT;
509   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
510   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
511   case Instruction::BitCast : return bitc::CAST_BITCAST;
512   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
513   }
514 }
515 
516 static unsigned getEncodedBinaryOpcode(unsigned Opcode) {
517   switch (Opcode) {
518   default: llvm_unreachable("Unknown binary instruction!");
519   case Instruction::Add:
520   case Instruction::FAdd: return bitc::BINOP_ADD;
521   case Instruction::Sub:
522   case Instruction::FSub: return bitc::BINOP_SUB;
523   case Instruction::Mul:
524   case Instruction::FMul: return bitc::BINOP_MUL;
525   case Instruction::UDiv: return bitc::BINOP_UDIV;
526   case Instruction::FDiv:
527   case Instruction::SDiv: return bitc::BINOP_SDIV;
528   case Instruction::URem: return bitc::BINOP_UREM;
529   case Instruction::FRem:
530   case Instruction::SRem: return bitc::BINOP_SREM;
531   case Instruction::Shl:  return bitc::BINOP_SHL;
532   case Instruction::LShr: return bitc::BINOP_LSHR;
533   case Instruction::AShr: return bitc::BINOP_ASHR;
534   case Instruction::And:  return bitc::BINOP_AND;
535   case Instruction::Or:   return bitc::BINOP_OR;
536   case Instruction::Xor:  return bitc::BINOP_XOR;
537   }
538 }
539 
540 static unsigned getEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
541   switch (Op) {
542   default: llvm_unreachable("Unknown RMW operation!");
543   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
544   case AtomicRMWInst::Add: return bitc::RMW_ADD;
545   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
546   case AtomicRMWInst::And: return bitc::RMW_AND;
547   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
548   case AtomicRMWInst::Or: return bitc::RMW_OR;
549   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
550   case AtomicRMWInst::Max: return bitc::RMW_MAX;
551   case AtomicRMWInst::Min: return bitc::RMW_MIN;
552   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
553   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
554   }
555 }
556 
557 static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
558   switch (Ordering) {
559   case AtomicOrdering::NotAtomic: return bitc::ORDERING_NOTATOMIC;
560   case AtomicOrdering::Unordered: return bitc::ORDERING_UNORDERED;
561   case AtomicOrdering::Monotonic: return bitc::ORDERING_MONOTONIC;
562   case AtomicOrdering::Acquire: return bitc::ORDERING_ACQUIRE;
563   case AtomicOrdering::Release: return bitc::ORDERING_RELEASE;
564   case AtomicOrdering::AcquireRelease: return bitc::ORDERING_ACQREL;
565   case AtomicOrdering::SequentiallyConsistent: return bitc::ORDERING_SEQCST;
566   }
567   llvm_unreachable("Invalid ordering");
568 }
569 
570 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
571                               StringRef Str, unsigned AbbrevToUse) {
572   SmallVector<unsigned, 64> Vals;
573 
574   // Code: [strchar x N]
575   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
576     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
577       AbbrevToUse = 0;
578     Vals.push_back(Str[i]);
579   }
580 
581   // Emit the finished record.
582   Stream.EmitRecord(Code, Vals, AbbrevToUse);
583 }
584 
585 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
586   switch (Kind) {
587   case Attribute::Alignment:
588     return bitc::ATTR_KIND_ALIGNMENT;
589   case Attribute::AllocSize:
590     return bitc::ATTR_KIND_ALLOC_SIZE;
591   case Attribute::AlwaysInline:
592     return bitc::ATTR_KIND_ALWAYS_INLINE;
593   case Attribute::ArgMemOnly:
594     return bitc::ATTR_KIND_ARGMEMONLY;
595   case Attribute::Builtin:
596     return bitc::ATTR_KIND_BUILTIN;
597   case Attribute::ByVal:
598     return bitc::ATTR_KIND_BY_VAL;
599   case Attribute::Convergent:
600     return bitc::ATTR_KIND_CONVERGENT;
601   case Attribute::InAlloca:
602     return bitc::ATTR_KIND_IN_ALLOCA;
603   case Attribute::Cold:
604     return bitc::ATTR_KIND_COLD;
605   case Attribute::InaccessibleMemOnly:
606     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
607   case Attribute::InaccessibleMemOrArgMemOnly:
608     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
609   case Attribute::InlineHint:
610     return bitc::ATTR_KIND_INLINE_HINT;
611   case Attribute::InReg:
612     return bitc::ATTR_KIND_IN_REG;
613   case Attribute::JumpTable:
614     return bitc::ATTR_KIND_JUMP_TABLE;
615   case Attribute::MinSize:
616     return bitc::ATTR_KIND_MIN_SIZE;
617   case Attribute::Naked:
618     return bitc::ATTR_KIND_NAKED;
619   case Attribute::Nest:
620     return bitc::ATTR_KIND_NEST;
621   case Attribute::NoAlias:
622     return bitc::ATTR_KIND_NO_ALIAS;
623   case Attribute::NoBuiltin:
624     return bitc::ATTR_KIND_NO_BUILTIN;
625   case Attribute::NoCapture:
626     return bitc::ATTR_KIND_NO_CAPTURE;
627   case Attribute::NoDuplicate:
628     return bitc::ATTR_KIND_NO_DUPLICATE;
629   case Attribute::NoImplicitFloat:
630     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
631   case Attribute::NoInline:
632     return bitc::ATTR_KIND_NO_INLINE;
633   case Attribute::NoRecurse:
634     return bitc::ATTR_KIND_NO_RECURSE;
635   case Attribute::NonLazyBind:
636     return bitc::ATTR_KIND_NON_LAZY_BIND;
637   case Attribute::NonNull:
638     return bitc::ATTR_KIND_NON_NULL;
639   case Attribute::Dereferenceable:
640     return bitc::ATTR_KIND_DEREFERENCEABLE;
641   case Attribute::DereferenceableOrNull:
642     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
643   case Attribute::NoRedZone:
644     return bitc::ATTR_KIND_NO_RED_ZONE;
645   case Attribute::NoReturn:
646     return bitc::ATTR_KIND_NO_RETURN;
647   case Attribute::NoCfCheck:
648     return bitc::ATTR_KIND_NOCF_CHECK;
649   case Attribute::NoUnwind:
650     return bitc::ATTR_KIND_NO_UNWIND;
651   case Attribute::OptForFuzzing:
652     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
653   case Attribute::OptimizeForSize:
654     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
655   case Attribute::OptimizeNone:
656     return bitc::ATTR_KIND_OPTIMIZE_NONE;
657   case Attribute::ReadNone:
658     return bitc::ATTR_KIND_READ_NONE;
659   case Attribute::ReadOnly:
660     return bitc::ATTR_KIND_READ_ONLY;
661   case Attribute::Returned:
662     return bitc::ATTR_KIND_RETURNED;
663   case Attribute::ReturnsTwice:
664     return bitc::ATTR_KIND_RETURNS_TWICE;
665   case Attribute::SExt:
666     return bitc::ATTR_KIND_S_EXT;
667   case Attribute::Speculatable:
668     return bitc::ATTR_KIND_SPECULATABLE;
669   case Attribute::StackAlignment:
670     return bitc::ATTR_KIND_STACK_ALIGNMENT;
671   case Attribute::StackProtect:
672     return bitc::ATTR_KIND_STACK_PROTECT;
673   case Attribute::StackProtectReq:
674     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
675   case Attribute::StackProtectStrong:
676     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
677   case Attribute::SafeStack:
678     return bitc::ATTR_KIND_SAFESTACK;
679   case Attribute::ShadowCallStack:
680     return bitc::ATTR_KIND_SHADOWCALLSTACK;
681   case Attribute::StrictFP:
682     return bitc::ATTR_KIND_STRICT_FP;
683   case Attribute::StructRet:
684     return bitc::ATTR_KIND_STRUCT_RET;
685   case Attribute::SanitizeAddress:
686     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
687   case Attribute::SanitizeHWAddress:
688     return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
689   case Attribute::SanitizeThread:
690     return bitc::ATTR_KIND_SANITIZE_THREAD;
691   case Attribute::SanitizeMemory:
692     return bitc::ATTR_KIND_SANITIZE_MEMORY;
693   case Attribute::SwiftError:
694     return bitc::ATTR_KIND_SWIFT_ERROR;
695   case Attribute::SwiftSelf:
696     return bitc::ATTR_KIND_SWIFT_SELF;
697   case Attribute::UWTable:
698     return bitc::ATTR_KIND_UW_TABLE;
699   case Attribute::WriteOnly:
700     return bitc::ATTR_KIND_WRITEONLY;
701   case Attribute::ZExt:
702     return bitc::ATTR_KIND_Z_EXT;
703   case Attribute::EndAttrKinds:
704     llvm_unreachable("Can not encode end-attribute kinds marker.");
705   case Attribute::None:
706     llvm_unreachable("Can not encode none-attribute.");
707   }
708 
709   llvm_unreachable("Trying to encode unknown attribute");
710 }
711 
712 void ModuleBitcodeWriter::writeAttributeGroupTable() {
713   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
714       VE.getAttributeGroups();
715   if (AttrGrps.empty()) return;
716 
717   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
718 
719   SmallVector<uint64_t, 64> Record;
720   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
721     unsigned AttrListIndex = Pair.first;
722     AttributeSet AS = Pair.second;
723     Record.push_back(VE.getAttributeGroupID(Pair));
724     Record.push_back(AttrListIndex);
725 
726     for (Attribute Attr : AS) {
727       if (Attr.isEnumAttribute()) {
728         Record.push_back(0);
729         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
730       } else if (Attr.isIntAttribute()) {
731         Record.push_back(1);
732         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
733         Record.push_back(Attr.getValueAsInt());
734       } else {
735         StringRef Kind = Attr.getKindAsString();
736         StringRef Val = Attr.getValueAsString();
737 
738         Record.push_back(Val.empty() ? 3 : 4);
739         Record.append(Kind.begin(), Kind.end());
740         Record.push_back(0);
741         if (!Val.empty()) {
742           Record.append(Val.begin(), Val.end());
743           Record.push_back(0);
744         }
745       }
746     }
747 
748     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
749     Record.clear();
750   }
751 
752   Stream.ExitBlock();
753 }
754 
755 void ModuleBitcodeWriter::writeAttributeTable() {
756   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
757   if (Attrs.empty()) return;
758 
759   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
760 
761   SmallVector<uint64_t, 64> Record;
762   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
763     AttributeList AL = Attrs[i];
764     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
765       AttributeSet AS = AL.getAttributes(i);
766       if (AS.hasAttributes())
767         Record.push_back(VE.getAttributeGroupID({i, AS}));
768     }
769 
770     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
771     Record.clear();
772   }
773 
774   Stream.ExitBlock();
775 }
776 
777 /// WriteTypeTable - Write out the type table for a module.
778 void ModuleBitcodeWriter::writeTypeTable() {
779   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
780 
781   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
782   SmallVector<uint64_t, 64> TypeVals;
783 
784   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
785 
786   // Abbrev for TYPE_CODE_POINTER.
787   auto Abbv = std::make_shared<BitCodeAbbrev>();
788   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
789   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
790   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
791   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
792 
793   // Abbrev for TYPE_CODE_FUNCTION.
794   Abbv = std::make_shared<BitCodeAbbrev>();
795   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
796   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
797   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
798   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
799   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
800 
801   // Abbrev for TYPE_CODE_STRUCT_ANON.
802   Abbv = std::make_shared<BitCodeAbbrev>();
803   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
804   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
805   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
806   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
807   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
808 
809   // Abbrev for TYPE_CODE_STRUCT_NAME.
810   Abbv = std::make_shared<BitCodeAbbrev>();
811   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
812   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
813   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
814   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
815 
816   // Abbrev for TYPE_CODE_STRUCT_NAMED.
817   Abbv = std::make_shared<BitCodeAbbrev>();
818   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
819   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
820   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
822   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
823 
824   // Abbrev for TYPE_CODE_ARRAY.
825   Abbv = std::make_shared<BitCodeAbbrev>();
826   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
827   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
828   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
829   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
830 
831   // Emit an entry count so the reader can reserve space.
832   TypeVals.push_back(TypeList.size());
833   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
834   TypeVals.clear();
835 
836   // Loop over all of the types, emitting each in turn.
837   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
838     Type *T = TypeList[i];
839     int AbbrevToUse = 0;
840     unsigned Code = 0;
841 
842     switch (T->getTypeID()) {
843     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
844     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
845     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
846     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
847     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
848     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
849     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
850     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
851     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
852     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
853     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
854     case Type::IntegerTyID:
855       // INTEGER: [width]
856       Code = bitc::TYPE_CODE_INTEGER;
857       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
858       break;
859     case Type::PointerTyID: {
860       PointerType *PTy = cast<PointerType>(T);
861       // POINTER: [pointee type, address space]
862       Code = bitc::TYPE_CODE_POINTER;
863       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
864       unsigned AddressSpace = PTy->getAddressSpace();
865       TypeVals.push_back(AddressSpace);
866       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
867       break;
868     }
869     case Type::FunctionTyID: {
870       FunctionType *FT = cast<FunctionType>(T);
871       // FUNCTION: [isvararg, retty, paramty x N]
872       Code = bitc::TYPE_CODE_FUNCTION;
873       TypeVals.push_back(FT->isVarArg());
874       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
875       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
876         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
877       AbbrevToUse = FunctionAbbrev;
878       break;
879     }
880     case Type::StructTyID: {
881       StructType *ST = cast<StructType>(T);
882       // STRUCT: [ispacked, eltty x N]
883       TypeVals.push_back(ST->isPacked());
884       // Output all of the element types.
885       for (StructType::element_iterator I = ST->element_begin(),
886            E = ST->element_end(); I != E; ++I)
887         TypeVals.push_back(VE.getTypeID(*I));
888 
889       if (ST->isLiteral()) {
890         Code = bitc::TYPE_CODE_STRUCT_ANON;
891         AbbrevToUse = StructAnonAbbrev;
892       } else {
893         if (ST->isOpaque()) {
894           Code = bitc::TYPE_CODE_OPAQUE;
895         } else {
896           Code = bitc::TYPE_CODE_STRUCT_NAMED;
897           AbbrevToUse = StructNamedAbbrev;
898         }
899 
900         // Emit the name if it is present.
901         if (!ST->getName().empty())
902           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
903                             StructNameAbbrev);
904       }
905       break;
906     }
907     case Type::ArrayTyID: {
908       ArrayType *AT = cast<ArrayType>(T);
909       // ARRAY: [numelts, eltty]
910       Code = bitc::TYPE_CODE_ARRAY;
911       TypeVals.push_back(AT->getNumElements());
912       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
913       AbbrevToUse = ArrayAbbrev;
914       break;
915     }
916     case Type::VectorTyID: {
917       VectorType *VT = cast<VectorType>(T);
918       // VECTOR [numelts, eltty]
919       Code = bitc::TYPE_CODE_VECTOR;
920       TypeVals.push_back(VT->getNumElements());
921       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
922       break;
923     }
924     }
925 
926     // Emit the finished record.
927     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
928     TypeVals.clear();
929   }
930 
931   Stream.ExitBlock();
932 }
933 
934 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
935   switch (Linkage) {
936   case GlobalValue::ExternalLinkage:
937     return 0;
938   case GlobalValue::WeakAnyLinkage:
939     return 16;
940   case GlobalValue::AppendingLinkage:
941     return 2;
942   case GlobalValue::InternalLinkage:
943     return 3;
944   case GlobalValue::LinkOnceAnyLinkage:
945     return 18;
946   case GlobalValue::ExternalWeakLinkage:
947     return 7;
948   case GlobalValue::CommonLinkage:
949     return 8;
950   case GlobalValue::PrivateLinkage:
951     return 9;
952   case GlobalValue::WeakODRLinkage:
953     return 17;
954   case GlobalValue::LinkOnceODRLinkage:
955     return 19;
956   case GlobalValue::AvailableExternallyLinkage:
957     return 12;
958   }
959   llvm_unreachable("Invalid linkage");
960 }
961 
962 static unsigned getEncodedLinkage(const GlobalValue &GV) {
963   return getEncodedLinkage(GV.getLinkage());
964 }
965 
966 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
967   uint64_t RawFlags = 0;
968   RawFlags |= Flags.ReadNone;
969   RawFlags |= (Flags.ReadOnly << 1);
970   RawFlags |= (Flags.NoRecurse << 2);
971   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
972   return RawFlags;
973 }
974 
975 // Decode the flags for GlobalValue in the summary
976 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
977   uint64_t RawFlags = 0;
978 
979   RawFlags |= Flags.NotEligibleToImport; // bool
980   RawFlags |= (Flags.Live << 1);
981   RawFlags |= (Flags.DSOLocal << 2);
982 
983   // Linkage don't need to be remapped at that time for the summary. Any future
984   // change to the getEncodedLinkage() function will need to be taken into
985   // account here as well.
986   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
987 
988   return RawFlags;
989 }
990 
991 static unsigned getEncodedVisibility(const GlobalValue &GV) {
992   switch (GV.getVisibility()) {
993   case GlobalValue::DefaultVisibility:   return 0;
994   case GlobalValue::HiddenVisibility:    return 1;
995   case GlobalValue::ProtectedVisibility: return 2;
996   }
997   llvm_unreachable("Invalid visibility");
998 }
999 
1000 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1001   switch (GV.getDLLStorageClass()) {
1002   case GlobalValue::DefaultStorageClass:   return 0;
1003   case GlobalValue::DLLImportStorageClass: return 1;
1004   case GlobalValue::DLLExportStorageClass: return 2;
1005   }
1006   llvm_unreachable("Invalid DLL storage class");
1007 }
1008 
1009 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1010   switch (GV.getThreadLocalMode()) {
1011     case GlobalVariable::NotThreadLocal:         return 0;
1012     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1013     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1014     case GlobalVariable::InitialExecTLSModel:    return 3;
1015     case GlobalVariable::LocalExecTLSModel:      return 4;
1016   }
1017   llvm_unreachable("Invalid TLS model");
1018 }
1019 
1020 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1021   switch (C.getSelectionKind()) {
1022   case Comdat::Any:
1023     return bitc::COMDAT_SELECTION_KIND_ANY;
1024   case Comdat::ExactMatch:
1025     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1026   case Comdat::Largest:
1027     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1028   case Comdat::NoDuplicates:
1029     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1030   case Comdat::SameSize:
1031     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1032   }
1033   llvm_unreachable("Invalid selection kind");
1034 }
1035 
1036 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1037   switch (GV.getUnnamedAddr()) {
1038   case GlobalValue::UnnamedAddr::None:   return 0;
1039   case GlobalValue::UnnamedAddr::Local:  return 2;
1040   case GlobalValue::UnnamedAddr::Global: return 1;
1041   }
1042   llvm_unreachable("Invalid unnamed_addr");
1043 }
1044 
1045 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1046   if (GenerateHash)
1047     Hasher.update(Str);
1048   return StrtabBuilder.add(Str);
1049 }
1050 
1051 void ModuleBitcodeWriter::writeComdats() {
1052   SmallVector<unsigned, 64> Vals;
1053   for (const Comdat *C : VE.getComdats()) {
1054     // COMDAT: [strtab offset, strtab size, selection_kind]
1055     Vals.push_back(addToStrtab(C->getName()));
1056     Vals.push_back(C->getName().size());
1057     Vals.push_back(getEncodedComdatSelectionKind(*C));
1058     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1059     Vals.clear();
1060   }
1061 }
1062 
1063 /// Write a record that will eventually hold the word offset of the
1064 /// module-level VST. For now the offset is 0, which will be backpatched
1065 /// after the real VST is written. Saves the bit offset to backpatch.
1066 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1067   // Write a placeholder value in for the offset of the real VST,
1068   // which is written after the function blocks so that it can include
1069   // the offset of each function. The placeholder offset will be
1070   // updated when the real VST is written.
1071   auto Abbv = std::make_shared<BitCodeAbbrev>();
1072   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1073   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1074   // hold the real VST offset. Must use fixed instead of VBR as we don't
1075   // know how many VBR chunks to reserve ahead of time.
1076   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1077   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1078 
1079   // Emit the placeholder
1080   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1081   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1082 
1083   // Compute and save the bit offset to the placeholder, which will be
1084   // patched when the real VST is written. We can simply subtract the 32-bit
1085   // fixed size from the current bit number to get the location to backpatch.
1086   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1087 }
1088 
1089 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1090 
1091 /// Determine the encoding to use for the given string name and length.
1092 static StringEncoding getStringEncoding(StringRef Str) {
1093   bool isChar6 = true;
1094   for (char C : Str) {
1095     if (isChar6)
1096       isChar6 = BitCodeAbbrevOp::isChar6(C);
1097     if ((unsigned char)C & 128)
1098       // don't bother scanning the rest.
1099       return SE_Fixed8;
1100   }
1101   if (isChar6)
1102     return SE_Char6;
1103   return SE_Fixed7;
1104 }
1105 
1106 /// Emit top-level description of module, including target triple, inline asm,
1107 /// descriptors for global variables, and function prototype info.
1108 /// Returns the bit offset to backpatch with the location of the real VST.
1109 void ModuleBitcodeWriter::writeModuleInfo() {
1110   // Emit various pieces of data attached to a module.
1111   if (!M.getTargetTriple().empty())
1112     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1113                       0 /*TODO*/);
1114   const std::string &DL = M.getDataLayoutStr();
1115   if (!DL.empty())
1116     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1117   if (!M.getModuleInlineAsm().empty())
1118     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1119                       0 /*TODO*/);
1120 
1121   // Emit information about sections and GC, computing how many there are. Also
1122   // compute the maximum alignment value.
1123   std::map<std::string, unsigned> SectionMap;
1124   std::map<std::string, unsigned> GCMap;
1125   unsigned MaxAlignment = 0;
1126   unsigned MaxGlobalType = 0;
1127   for (const GlobalValue &GV : M.globals()) {
1128     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1129     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1130     if (GV.hasSection()) {
1131       // Give section names unique ID's.
1132       unsigned &Entry = SectionMap[GV.getSection()];
1133       if (!Entry) {
1134         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1135                           0 /*TODO*/);
1136         Entry = SectionMap.size();
1137       }
1138     }
1139   }
1140   for (const Function &F : M) {
1141     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1142     if (F.hasSection()) {
1143       // Give section names unique ID's.
1144       unsigned &Entry = SectionMap[F.getSection()];
1145       if (!Entry) {
1146         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1147                           0 /*TODO*/);
1148         Entry = SectionMap.size();
1149       }
1150     }
1151     if (F.hasGC()) {
1152       // Same for GC names.
1153       unsigned &Entry = GCMap[F.getGC()];
1154       if (!Entry) {
1155         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1156                           0 /*TODO*/);
1157         Entry = GCMap.size();
1158       }
1159     }
1160   }
1161 
1162   // Emit abbrev for globals, now that we know # sections and max alignment.
1163   unsigned SimpleGVarAbbrev = 0;
1164   if (!M.global_empty()) {
1165     // Add an abbrev for common globals with no visibility or thread localness.
1166     auto Abbv = std::make_shared<BitCodeAbbrev>();
1167     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1168     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1169     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1170     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1171                               Log2_32_Ceil(MaxGlobalType+1)));
1172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1173                                                            //| explicitType << 1
1174                                                            //| constant
1175     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1177     if (MaxAlignment == 0)                                 // Alignment.
1178       Abbv->Add(BitCodeAbbrevOp(0));
1179     else {
1180       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1181       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1182                                Log2_32_Ceil(MaxEncAlignment+1)));
1183     }
1184     if (SectionMap.empty())                                    // Section.
1185       Abbv->Add(BitCodeAbbrevOp(0));
1186     else
1187       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1188                                Log2_32_Ceil(SectionMap.size()+1)));
1189     // Don't bother emitting vis + thread local.
1190     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1191   }
1192 
1193   SmallVector<unsigned, 64> Vals;
1194   // Emit the module's source file name.
1195   {
1196     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1197     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1198     if (Bits == SE_Char6)
1199       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1200     else if (Bits == SE_Fixed7)
1201       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1202 
1203     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1204     auto Abbv = std::make_shared<BitCodeAbbrev>();
1205     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1206     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1207     Abbv->Add(AbbrevOpToUse);
1208     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1209 
1210     for (const auto P : M.getSourceFileName())
1211       Vals.push_back((unsigned char)P);
1212 
1213     // Emit the finished record.
1214     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1215     Vals.clear();
1216   }
1217 
1218   // Emit the global variable information.
1219   for (const GlobalVariable &GV : M.globals()) {
1220     unsigned AbbrevToUse = 0;
1221 
1222     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1223     //             linkage, alignment, section, visibility, threadlocal,
1224     //             unnamed_addr, externally_initialized, dllstorageclass,
1225     //             comdat, attributes, DSO_Local]
1226     Vals.push_back(addToStrtab(GV.getName()));
1227     Vals.push_back(GV.getName().size());
1228     Vals.push_back(VE.getTypeID(GV.getValueType()));
1229     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1230     Vals.push_back(GV.isDeclaration() ? 0 :
1231                    (VE.getValueID(GV.getInitializer()) + 1));
1232     Vals.push_back(getEncodedLinkage(GV));
1233     Vals.push_back(Log2_32(GV.getAlignment())+1);
1234     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1235     if (GV.isThreadLocal() ||
1236         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1237         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1238         GV.isExternallyInitialized() ||
1239         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1240         GV.hasComdat() ||
1241         GV.hasAttributes() ||
1242         GV.isDSOLocal()) {
1243       Vals.push_back(getEncodedVisibility(GV));
1244       Vals.push_back(getEncodedThreadLocalMode(GV));
1245       Vals.push_back(getEncodedUnnamedAddr(GV));
1246       Vals.push_back(GV.isExternallyInitialized());
1247       Vals.push_back(getEncodedDLLStorageClass(GV));
1248       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1249 
1250       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1251       Vals.push_back(VE.getAttributeListID(AL));
1252 
1253       Vals.push_back(GV.isDSOLocal());
1254     } else {
1255       AbbrevToUse = SimpleGVarAbbrev;
1256     }
1257 
1258     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1259     Vals.clear();
1260   }
1261 
1262   // Emit the function proto information.
1263   for (const Function &F : M) {
1264     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1265     //             linkage, paramattrs, alignment, section, visibility, gc,
1266     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1267     //             prefixdata, personalityfn, DSO_Local, addrspace]
1268     Vals.push_back(addToStrtab(F.getName()));
1269     Vals.push_back(F.getName().size());
1270     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1271     Vals.push_back(F.getCallingConv());
1272     Vals.push_back(F.isDeclaration());
1273     Vals.push_back(getEncodedLinkage(F));
1274     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1275     Vals.push_back(Log2_32(F.getAlignment())+1);
1276     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1277     Vals.push_back(getEncodedVisibility(F));
1278     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1279     Vals.push_back(getEncodedUnnamedAddr(F));
1280     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1281                                        : 0);
1282     Vals.push_back(getEncodedDLLStorageClass(F));
1283     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1284     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1285                                      : 0);
1286     Vals.push_back(
1287         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1288 
1289     Vals.push_back(F.isDSOLocal());
1290     Vals.push_back(F.getAddressSpace());
1291 
1292     unsigned AbbrevToUse = 0;
1293     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1294     Vals.clear();
1295   }
1296 
1297   // Emit the alias information.
1298   for (const GlobalAlias &A : M.aliases()) {
1299     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1300     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1301     //         DSO_Local]
1302     Vals.push_back(addToStrtab(A.getName()));
1303     Vals.push_back(A.getName().size());
1304     Vals.push_back(VE.getTypeID(A.getValueType()));
1305     Vals.push_back(A.getType()->getAddressSpace());
1306     Vals.push_back(VE.getValueID(A.getAliasee()));
1307     Vals.push_back(getEncodedLinkage(A));
1308     Vals.push_back(getEncodedVisibility(A));
1309     Vals.push_back(getEncodedDLLStorageClass(A));
1310     Vals.push_back(getEncodedThreadLocalMode(A));
1311     Vals.push_back(getEncodedUnnamedAddr(A));
1312     Vals.push_back(A.isDSOLocal());
1313 
1314     unsigned AbbrevToUse = 0;
1315     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1316     Vals.clear();
1317   }
1318 
1319   // Emit the ifunc information.
1320   for (const GlobalIFunc &I : M.ifuncs()) {
1321     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1322     //         val#, linkage, visibility, DSO_Local]
1323     Vals.push_back(addToStrtab(I.getName()));
1324     Vals.push_back(I.getName().size());
1325     Vals.push_back(VE.getTypeID(I.getValueType()));
1326     Vals.push_back(I.getType()->getAddressSpace());
1327     Vals.push_back(VE.getValueID(I.getResolver()));
1328     Vals.push_back(getEncodedLinkage(I));
1329     Vals.push_back(getEncodedVisibility(I));
1330     Vals.push_back(I.isDSOLocal());
1331     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1332     Vals.clear();
1333   }
1334 
1335   writeValueSymbolTableForwardDecl();
1336 }
1337 
1338 static uint64_t getOptimizationFlags(const Value *V) {
1339   uint64_t Flags = 0;
1340 
1341   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1342     if (OBO->hasNoSignedWrap())
1343       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1344     if (OBO->hasNoUnsignedWrap())
1345       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1346   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1347     if (PEO->isExact())
1348       Flags |= 1 << bitc::PEO_EXACT;
1349   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1350     if (FPMO->hasAllowReassoc())
1351       Flags |= bitc::AllowReassoc;
1352     if (FPMO->hasNoNaNs())
1353       Flags |= bitc::NoNaNs;
1354     if (FPMO->hasNoInfs())
1355       Flags |= bitc::NoInfs;
1356     if (FPMO->hasNoSignedZeros())
1357       Flags |= bitc::NoSignedZeros;
1358     if (FPMO->hasAllowReciprocal())
1359       Flags |= bitc::AllowReciprocal;
1360     if (FPMO->hasAllowContract())
1361       Flags |= bitc::AllowContract;
1362     if (FPMO->hasApproxFunc())
1363       Flags |= bitc::ApproxFunc;
1364   }
1365 
1366   return Flags;
1367 }
1368 
1369 void ModuleBitcodeWriter::writeValueAsMetadata(
1370     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1371   // Mimic an MDNode with a value as one operand.
1372   Value *V = MD->getValue();
1373   Record.push_back(VE.getTypeID(V->getType()));
1374   Record.push_back(VE.getValueID(V));
1375   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1376   Record.clear();
1377 }
1378 
1379 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1380                                        SmallVectorImpl<uint64_t> &Record,
1381                                        unsigned Abbrev) {
1382   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1383     Metadata *MD = N->getOperand(i);
1384     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1385            "Unexpected function-local metadata");
1386     Record.push_back(VE.getMetadataOrNullID(MD));
1387   }
1388   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1389                                     : bitc::METADATA_NODE,
1390                     Record, Abbrev);
1391   Record.clear();
1392 }
1393 
1394 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1395   // Assume the column is usually under 128, and always output the inlined-at
1396   // location (it's never more expensive than building an array size 1).
1397   auto Abbv = std::make_shared<BitCodeAbbrev>();
1398   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1399   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1400   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1401   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1402   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1403   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1404   return Stream.EmitAbbrev(std::move(Abbv));
1405 }
1406 
1407 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1408                                           SmallVectorImpl<uint64_t> &Record,
1409                                           unsigned &Abbrev) {
1410   if (!Abbrev)
1411     Abbrev = createDILocationAbbrev();
1412 
1413   Record.push_back(N->isDistinct());
1414   Record.push_back(N->getLine());
1415   Record.push_back(N->getColumn());
1416   Record.push_back(VE.getMetadataID(N->getScope()));
1417   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1418 
1419   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1420   Record.clear();
1421 }
1422 
1423 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1424   // Assume the column is usually under 128, and always output the inlined-at
1425   // location (it's never more expensive than building an array size 1).
1426   auto Abbv = std::make_shared<BitCodeAbbrev>();
1427   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1428   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1429   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1430   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1431   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1432   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1433   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1434   return Stream.EmitAbbrev(std::move(Abbv));
1435 }
1436 
1437 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1438                                              SmallVectorImpl<uint64_t> &Record,
1439                                              unsigned &Abbrev) {
1440   if (!Abbrev)
1441     Abbrev = createGenericDINodeAbbrev();
1442 
1443   Record.push_back(N->isDistinct());
1444   Record.push_back(N->getTag());
1445   Record.push_back(0); // Per-tag version field; unused for now.
1446 
1447   for (auto &I : N->operands())
1448     Record.push_back(VE.getMetadataOrNullID(I));
1449 
1450   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1451   Record.clear();
1452 }
1453 
1454 static uint64_t rotateSign(int64_t I) {
1455   uint64_t U = I;
1456   return I < 0 ? ~(U << 1) : U << 1;
1457 }
1458 
1459 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1460                                           SmallVectorImpl<uint64_t> &Record,
1461                                           unsigned Abbrev) {
1462   const uint64_t Version = 1 << 1;
1463   Record.push_back((uint64_t)N->isDistinct() | Version);
1464   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1465   Record.push_back(rotateSign(N->getLowerBound()));
1466 
1467   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1468   Record.clear();
1469 }
1470 
1471 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1472                                             SmallVectorImpl<uint64_t> &Record,
1473                                             unsigned Abbrev) {
1474   Record.push_back((N->isUnsigned() << 1) | N->isDistinct());
1475   Record.push_back(rotateSign(N->getValue()));
1476   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1477 
1478   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1479   Record.clear();
1480 }
1481 
1482 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1483                                            SmallVectorImpl<uint64_t> &Record,
1484                                            unsigned Abbrev) {
1485   Record.push_back(N->isDistinct());
1486   Record.push_back(N->getTag());
1487   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1488   Record.push_back(N->getSizeInBits());
1489   Record.push_back(N->getAlignInBits());
1490   Record.push_back(N->getEncoding());
1491   Record.push_back(N->getFlags());
1492 
1493   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1494   Record.clear();
1495 }
1496 
1497 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1498                                              SmallVectorImpl<uint64_t> &Record,
1499                                              unsigned Abbrev) {
1500   Record.push_back(N->isDistinct());
1501   Record.push_back(N->getTag());
1502   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1503   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1504   Record.push_back(N->getLine());
1505   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1506   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1507   Record.push_back(N->getSizeInBits());
1508   Record.push_back(N->getAlignInBits());
1509   Record.push_back(N->getOffsetInBits());
1510   Record.push_back(N->getFlags());
1511   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1512 
1513   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1514   // that there is no DWARF address space associated with DIDerivedType.
1515   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1516     Record.push_back(*DWARFAddressSpace + 1);
1517   else
1518     Record.push_back(0);
1519 
1520   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1521   Record.clear();
1522 }
1523 
1524 void ModuleBitcodeWriter::writeDICompositeType(
1525     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1526     unsigned Abbrev) {
1527   const unsigned IsNotUsedInOldTypeRef = 0x2;
1528   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1529   Record.push_back(N->getTag());
1530   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1531   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1532   Record.push_back(N->getLine());
1533   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1534   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1535   Record.push_back(N->getSizeInBits());
1536   Record.push_back(N->getAlignInBits());
1537   Record.push_back(N->getOffsetInBits());
1538   Record.push_back(N->getFlags());
1539   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1540   Record.push_back(N->getRuntimeLang());
1541   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1542   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1543   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1544   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1545 
1546   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1547   Record.clear();
1548 }
1549 
1550 void ModuleBitcodeWriter::writeDISubroutineType(
1551     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1552     unsigned Abbrev) {
1553   const unsigned HasNoOldTypeRefs = 0x2;
1554   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1555   Record.push_back(N->getFlags());
1556   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1557   Record.push_back(N->getCC());
1558 
1559   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1560   Record.clear();
1561 }
1562 
1563 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1564                                       SmallVectorImpl<uint64_t> &Record,
1565                                       unsigned Abbrev) {
1566   Record.push_back(N->isDistinct());
1567   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1568   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1569   if (N->getRawChecksum()) {
1570     Record.push_back(N->getRawChecksum()->Kind);
1571     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1572   } else {
1573     // Maintain backwards compatibility with the old internal representation of
1574     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1575     Record.push_back(0);
1576     Record.push_back(VE.getMetadataOrNullID(nullptr));
1577   }
1578   auto Source = N->getRawSource();
1579   if (Source)
1580     Record.push_back(VE.getMetadataOrNullID(*Source));
1581 
1582   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1583   Record.clear();
1584 }
1585 
1586 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1587                                              SmallVectorImpl<uint64_t> &Record,
1588                                              unsigned Abbrev) {
1589   assert(N->isDistinct() && "Expected distinct compile units");
1590   Record.push_back(/* IsDistinct */ true);
1591   Record.push_back(N->getSourceLanguage());
1592   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1593   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1594   Record.push_back(N->isOptimized());
1595   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1596   Record.push_back(N->getRuntimeVersion());
1597   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1598   Record.push_back(N->getEmissionKind());
1599   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1600   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1601   Record.push_back(/* subprograms */ 0);
1602   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1603   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1604   Record.push_back(N->getDWOId());
1605   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1606   Record.push_back(N->getSplitDebugInlining());
1607   Record.push_back(N->getDebugInfoForProfiling());
1608   Record.push_back((unsigned)N->getNameTableKind());
1609 
1610   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1611   Record.clear();
1612 }
1613 
1614 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1615                                             SmallVectorImpl<uint64_t> &Record,
1616                                             unsigned Abbrev) {
1617   uint64_t HasUnitFlag = 1 << 1;
1618   Record.push_back(N->isDistinct() | HasUnitFlag);
1619   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1620   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1621   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1622   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1623   Record.push_back(N->getLine());
1624   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1625   Record.push_back(N->isLocalToUnit());
1626   Record.push_back(N->isDefinition());
1627   Record.push_back(N->getScopeLine());
1628   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1629   Record.push_back(N->getVirtuality());
1630   Record.push_back(N->getVirtualIndex());
1631   Record.push_back(N->getFlags());
1632   Record.push_back(N->isOptimized());
1633   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1634   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1635   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1636   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1637   Record.push_back(N->getThisAdjustment());
1638   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1639 
1640   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1641   Record.clear();
1642 }
1643 
1644 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1645                                               SmallVectorImpl<uint64_t> &Record,
1646                                               unsigned Abbrev) {
1647   Record.push_back(N->isDistinct());
1648   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1649   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1650   Record.push_back(N->getLine());
1651   Record.push_back(N->getColumn());
1652 
1653   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1654   Record.clear();
1655 }
1656 
1657 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1658     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1659     unsigned Abbrev) {
1660   Record.push_back(N->isDistinct());
1661   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1662   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1663   Record.push_back(N->getDiscriminator());
1664 
1665   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1666   Record.clear();
1667 }
1668 
1669 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1670                                            SmallVectorImpl<uint64_t> &Record,
1671                                            unsigned Abbrev) {
1672   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1673   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1674   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1675 
1676   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1677   Record.clear();
1678 }
1679 
1680 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1681                                        SmallVectorImpl<uint64_t> &Record,
1682                                        unsigned Abbrev) {
1683   Record.push_back(N->isDistinct());
1684   Record.push_back(N->getMacinfoType());
1685   Record.push_back(N->getLine());
1686   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1687   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1688 
1689   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1690   Record.clear();
1691 }
1692 
1693 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1694                                            SmallVectorImpl<uint64_t> &Record,
1695                                            unsigned Abbrev) {
1696   Record.push_back(N->isDistinct());
1697   Record.push_back(N->getMacinfoType());
1698   Record.push_back(N->getLine());
1699   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1700   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1701 
1702   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1703   Record.clear();
1704 }
1705 
1706 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1707                                         SmallVectorImpl<uint64_t> &Record,
1708                                         unsigned Abbrev) {
1709   Record.push_back(N->isDistinct());
1710   for (auto &I : N->operands())
1711     Record.push_back(VE.getMetadataOrNullID(I));
1712 
1713   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1714   Record.clear();
1715 }
1716 
1717 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1718     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1719     unsigned Abbrev) {
1720   Record.push_back(N->isDistinct());
1721   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1722   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1723 
1724   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1725   Record.clear();
1726 }
1727 
1728 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1729     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1730     unsigned Abbrev) {
1731   Record.push_back(N->isDistinct());
1732   Record.push_back(N->getTag());
1733   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1734   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1735   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1736 
1737   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1738   Record.clear();
1739 }
1740 
1741 void ModuleBitcodeWriter::writeDIGlobalVariable(
1742     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1743     unsigned Abbrev) {
1744   const uint64_t Version = 1 << 1;
1745   Record.push_back((uint64_t)N->isDistinct() | Version);
1746   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1747   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1748   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1749   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1750   Record.push_back(N->getLine());
1751   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1752   Record.push_back(N->isLocalToUnit());
1753   Record.push_back(N->isDefinition());
1754   Record.push_back(/* expr */ 0);
1755   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1756   Record.push_back(N->getAlignInBits());
1757 
1758   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1759   Record.clear();
1760 }
1761 
1762 void ModuleBitcodeWriter::writeDILocalVariable(
1763     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1764     unsigned Abbrev) {
1765   // In order to support all possible bitcode formats in BitcodeReader we need
1766   // to distinguish the following cases:
1767   // 1) Record has no artificial tag (Record[1]),
1768   //   has no obsolete inlinedAt field (Record[9]).
1769   //   In this case Record size will be 8, HasAlignment flag is false.
1770   // 2) Record has artificial tag (Record[1]),
1771   //   has no obsolete inlignedAt field (Record[9]).
1772   //   In this case Record size will be 9, HasAlignment flag is false.
1773   // 3) Record has both artificial tag (Record[1]) and
1774   //   obsolete inlignedAt field (Record[9]).
1775   //   In this case Record size will be 10, HasAlignment flag is false.
1776   // 4) Record has neither artificial tag, nor inlignedAt field, but
1777   //   HasAlignment flag is true and Record[8] contains alignment value.
1778   const uint64_t HasAlignmentFlag = 1 << 1;
1779   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1780   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1781   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1782   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1783   Record.push_back(N->getLine());
1784   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1785   Record.push_back(N->getArg());
1786   Record.push_back(N->getFlags());
1787   Record.push_back(N->getAlignInBits());
1788 
1789   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1790   Record.clear();
1791 }
1792 
1793 void ModuleBitcodeWriter::writeDILabel(
1794     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
1795     unsigned Abbrev) {
1796   Record.push_back((uint64_t)N->isDistinct());
1797   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1798   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1799   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1800   Record.push_back(N->getLine());
1801 
1802   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
1803   Record.clear();
1804 }
1805 
1806 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1807                                             SmallVectorImpl<uint64_t> &Record,
1808                                             unsigned Abbrev) {
1809   Record.reserve(N->getElements().size() + 1);
1810   const uint64_t Version = 3 << 1;
1811   Record.push_back((uint64_t)N->isDistinct() | Version);
1812   Record.append(N->elements_begin(), N->elements_end());
1813 
1814   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1815   Record.clear();
1816 }
1817 
1818 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1819     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1820     unsigned Abbrev) {
1821   Record.push_back(N->isDistinct());
1822   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1823   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1824 
1825   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1826   Record.clear();
1827 }
1828 
1829 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1830                                               SmallVectorImpl<uint64_t> &Record,
1831                                               unsigned Abbrev) {
1832   Record.push_back(N->isDistinct());
1833   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1834   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1835   Record.push_back(N->getLine());
1836   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1837   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1838   Record.push_back(N->getAttributes());
1839   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1840 
1841   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1842   Record.clear();
1843 }
1844 
1845 void ModuleBitcodeWriter::writeDIImportedEntity(
1846     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1847     unsigned Abbrev) {
1848   Record.push_back(N->isDistinct());
1849   Record.push_back(N->getTag());
1850   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1851   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1852   Record.push_back(N->getLine());
1853   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1854   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1855 
1856   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1857   Record.clear();
1858 }
1859 
1860 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1861   auto Abbv = std::make_shared<BitCodeAbbrev>();
1862   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1863   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1864   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1865   return Stream.EmitAbbrev(std::move(Abbv));
1866 }
1867 
1868 void ModuleBitcodeWriter::writeNamedMetadata(
1869     SmallVectorImpl<uint64_t> &Record) {
1870   if (M.named_metadata_empty())
1871     return;
1872 
1873   unsigned Abbrev = createNamedMetadataAbbrev();
1874   for (const NamedMDNode &NMD : M.named_metadata()) {
1875     // Write name.
1876     StringRef Str = NMD.getName();
1877     Record.append(Str.bytes_begin(), Str.bytes_end());
1878     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1879     Record.clear();
1880 
1881     // Write named metadata operands.
1882     for (const MDNode *N : NMD.operands())
1883       Record.push_back(VE.getMetadataID(N));
1884     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1885     Record.clear();
1886   }
1887 }
1888 
1889 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1890   auto Abbv = std::make_shared<BitCodeAbbrev>();
1891   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1892   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1893   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1894   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1895   return Stream.EmitAbbrev(std::move(Abbv));
1896 }
1897 
1898 /// Write out a record for MDString.
1899 ///
1900 /// All the metadata strings in a metadata block are emitted in a single
1901 /// record.  The sizes and strings themselves are shoved into a blob.
1902 void ModuleBitcodeWriter::writeMetadataStrings(
1903     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1904   if (Strings.empty())
1905     return;
1906 
1907   // Start the record with the number of strings.
1908   Record.push_back(bitc::METADATA_STRINGS);
1909   Record.push_back(Strings.size());
1910 
1911   // Emit the sizes of the strings in the blob.
1912   SmallString<256> Blob;
1913   {
1914     BitstreamWriter W(Blob);
1915     for (const Metadata *MD : Strings)
1916       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1917     W.FlushToWord();
1918   }
1919 
1920   // Add the offset to the strings to the record.
1921   Record.push_back(Blob.size());
1922 
1923   // Add the strings to the blob.
1924   for (const Metadata *MD : Strings)
1925     Blob.append(cast<MDString>(MD)->getString());
1926 
1927   // Emit the final record.
1928   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1929   Record.clear();
1930 }
1931 
1932 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1933 enum MetadataAbbrev : unsigned {
1934 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1935 #include "llvm/IR/Metadata.def"
1936   LastPlusOne
1937 };
1938 
1939 void ModuleBitcodeWriter::writeMetadataRecords(
1940     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1941     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1942   if (MDs.empty())
1943     return;
1944 
1945   // Initialize MDNode abbreviations.
1946 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1947 #include "llvm/IR/Metadata.def"
1948 
1949   for (const Metadata *MD : MDs) {
1950     if (IndexPos)
1951       IndexPos->push_back(Stream.GetCurrentBitNo());
1952     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1953       assert(N->isResolved() && "Expected forward references to be resolved");
1954 
1955       switch (N->getMetadataID()) {
1956       default:
1957         llvm_unreachable("Invalid MDNode subclass");
1958 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1959   case Metadata::CLASS##Kind:                                                  \
1960     if (MDAbbrevs)                                                             \
1961       write##CLASS(cast<CLASS>(N), Record,                                     \
1962                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1963     else                                                                       \
1964       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1965     continue;
1966 #include "llvm/IR/Metadata.def"
1967       }
1968     }
1969     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1970   }
1971 }
1972 
1973 void ModuleBitcodeWriter::writeModuleMetadata() {
1974   if (!VE.hasMDs() && M.named_metadata_empty())
1975     return;
1976 
1977   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1978   SmallVector<uint64_t, 64> Record;
1979 
1980   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1981   // block and load any metadata.
1982   std::vector<unsigned> MDAbbrevs;
1983 
1984   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1985   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1986   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1987       createGenericDINodeAbbrev();
1988 
1989   auto Abbv = std::make_shared<BitCodeAbbrev>();
1990   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1991   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1992   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1993   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1994 
1995   Abbv = std::make_shared<BitCodeAbbrev>();
1996   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1997   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1998   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1999   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2000 
2001   // Emit MDStrings together upfront.
2002   writeMetadataStrings(VE.getMDStrings(), Record);
2003 
2004   // We only emit an index for the metadata record if we have more than a given
2005   // (naive) threshold of metadatas, otherwise it is not worth it.
2006   if (VE.getNonMDStrings().size() > IndexThreshold) {
2007     // Write a placeholder value in for the offset of the metadata index,
2008     // which is written after the records, so that it can include
2009     // the offset of each entry. The placeholder offset will be
2010     // updated after all records are emitted.
2011     uint64_t Vals[] = {0, 0};
2012     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2013   }
2014 
2015   // Compute and save the bit offset to the current position, which will be
2016   // patched when we emit the index later. We can simply subtract the 64-bit
2017   // fixed size from the current bit number to get the location to backpatch.
2018   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2019 
2020   // This index will contain the bitpos for each individual record.
2021   std::vector<uint64_t> IndexPos;
2022   IndexPos.reserve(VE.getNonMDStrings().size());
2023 
2024   // Write all the records
2025   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2026 
2027   if (VE.getNonMDStrings().size() > IndexThreshold) {
2028     // Now that we have emitted all the records we will emit the index. But
2029     // first
2030     // backpatch the forward reference so that the reader can skip the records
2031     // efficiently.
2032     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2033                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2034 
2035     // Delta encode the index.
2036     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2037     for (auto &Elt : IndexPos) {
2038       auto EltDelta = Elt - PreviousValue;
2039       PreviousValue = Elt;
2040       Elt = EltDelta;
2041     }
2042     // Emit the index record.
2043     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2044     IndexPos.clear();
2045   }
2046 
2047   // Write the named metadata now.
2048   writeNamedMetadata(Record);
2049 
2050   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2051     SmallVector<uint64_t, 4> Record;
2052     Record.push_back(VE.getValueID(&GO));
2053     pushGlobalMetadataAttachment(Record, GO);
2054     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2055   };
2056   for (const Function &F : M)
2057     if (F.isDeclaration() && F.hasMetadata())
2058       AddDeclAttachedMetadata(F);
2059   // FIXME: Only store metadata for declarations here, and move data for global
2060   // variable definitions to a separate block (PR28134).
2061   for (const GlobalVariable &GV : M.globals())
2062     if (GV.hasMetadata())
2063       AddDeclAttachedMetadata(GV);
2064 
2065   Stream.ExitBlock();
2066 }
2067 
2068 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2069   if (!VE.hasMDs())
2070     return;
2071 
2072   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2073   SmallVector<uint64_t, 64> Record;
2074   writeMetadataStrings(VE.getMDStrings(), Record);
2075   writeMetadataRecords(VE.getNonMDStrings(), Record);
2076   Stream.ExitBlock();
2077 }
2078 
2079 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2080     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2081   // [n x [id, mdnode]]
2082   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2083   GO.getAllMetadata(MDs);
2084   for (const auto &I : MDs) {
2085     Record.push_back(I.first);
2086     Record.push_back(VE.getMetadataID(I.second));
2087   }
2088 }
2089 
2090 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2091   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2092 
2093   SmallVector<uint64_t, 64> Record;
2094 
2095   if (F.hasMetadata()) {
2096     pushGlobalMetadataAttachment(Record, F);
2097     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2098     Record.clear();
2099   }
2100 
2101   // Write metadata attachments
2102   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2103   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2104   for (const BasicBlock &BB : F)
2105     for (const Instruction &I : BB) {
2106       MDs.clear();
2107       I.getAllMetadataOtherThanDebugLoc(MDs);
2108 
2109       // If no metadata, ignore instruction.
2110       if (MDs.empty()) continue;
2111 
2112       Record.push_back(VE.getInstructionID(&I));
2113 
2114       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2115         Record.push_back(MDs[i].first);
2116         Record.push_back(VE.getMetadataID(MDs[i].second));
2117       }
2118       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2119       Record.clear();
2120     }
2121 
2122   Stream.ExitBlock();
2123 }
2124 
2125 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2126   SmallVector<uint64_t, 64> Record;
2127 
2128   // Write metadata kinds
2129   // METADATA_KIND - [n x [id, name]]
2130   SmallVector<StringRef, 8> Names;
2131   M.getMDKindNames(Names);
2132 
2133   if (Names.empty()) return;
2134 
2135   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2136 
2137   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2138     Record.push_back(MDKindID);
2139     StringRef KName = Names[MDKindID];
2140     Record.append(KName.begin(), KName.end());
2141 
2142     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2143     Record.clear();
2144   }
2145 
2146   Stream.ExitBlock();
2147 }
2148 
2149 void ModuleBitcodeWriter::writeOperandBundleTags() {
2150   // Write metadata kinds
2151   //
2152   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2153   //
2154   // OPERAND_BUNDLE_TAG - [strchr x N]
2155 
2156   SmallVector<StringRef, 8> Tags;
2157   M.getOperandBundleTags(Tags);
2158 
2159   if (Tags.empty())
2160     return;
2161 
2162   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2163 
2164   SmallVector<uint64_t, 64> Record;
2165 
2166   for (auto Tag : Tags) {
2167     Record.append(Tag.begin(), Tag.end());
2168 
2169     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2170     Record.clear();
2171   }
2172 
2173   Stream.ExitBlock();
2174 }
2175 
2176 void ModuleBitcodeWriter::writeSyncScopeNames() {
2177   SmallVector<StringRef, 8> SSNs;
2178   M.getContext().getSyncScopeNames(SSNs);
2179   if (SSNs.empty())
2180     return;
2181 
2182   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2183 
2184   SmallVector<uint64_t, 64> Record;
2185   for (auto SSN : SSNs) {
2186     Record.append(SSN.begin(), SSN.end());
2187     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2188     Record.clear();
2189   }
2190 
2191   Stream.ExitBlock();
2192 }
2193 
2194 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2195   if ((int64_t)V >= 0)
2196     Vals.push_back(V << 1);
2197   else
2198     Vals.push_back((-V << 1) | 1);
2199 }
2200 
2201 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2202                                          bool isGlobal) {
2203   if (FirstVal == LastVal) return;
2204 
2205   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2206 
2207   unsigned AggregateAbbrev = 0;
2208   unsigned String8Abbrev = 0;
2209   unsigned CString7Abbrev = 0;
2210   unsigned CString6Abbrev = 0;
2211   // If this is a constant pool for the module, emit module-specific abbrevs.
2212   if (isGlobal) {
2213     // Abbrev for CST_CODE_AGGREGATE.
2214     auto Abbv = std::make_shared<BitCodeAbbrev>();
2215     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2216     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2217     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2218     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2219 
2220     // Abbrev for CST_CODE_STRING.
2221     Abbv = std::make_shared<BitCodeAbbrev>();
2222     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2223     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2224     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2225     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2226     // Abbrev for CST_CODE_CSTRING.
2227     Abbv = std::make_shared<BitCodeAbbrev>();
2228     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2229     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2230     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2231     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2232     // Abbrev for CST_CODE_CSTRING.
2233     Abbv = std::make_shared<BitCodeAbbrev>();
2234     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2235     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2236     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2237     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2238   }
2239 
2240   SmallVector<uint64_t, 64> Record;
2241 
2242   const ValueEnumerator::ValueList &Vals = VE.getValues();
2243   Type *LastTy = nullptr;
2244   for (unsigned i = FirstVal; i != LastVal; ++i) {
2245     const Value *V = Vals[i].first;
2246     // If we need to switch types, do so now.
2247     if (V->getType() != LastTy) {
2248       LastTy = V->getType();
2249       Record.push_back(VE.getTypeID(LastTy));
2250       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2251                         CONSTANTS_SETTYPE_ABBREV);
2252       Record.clear();
2253     }
2254 
2255     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2256       Record.push_back(unsigned(IA->hasSideEffects()) |
2257                        unsigned(IA->isAlignStack()) << 1 |
2258                        unsigned(IA->getDialect()&1) << 2);
2259 
2260       // Add the asm string.
2261       const std::string &AsmStr = IA->getAsmString();
2262       Record.push_back(AsmStr.size());
2263       Record.append(AsmStr.begin(), AsmStr.end());
2264 
2265       // Add the constraint string.
2266       const std::string &ConstraintStr = IA->getConstraintString();
2267       Record.push_back(ConstraintStr.size());
2268       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2269       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2270       Record.clear();
2271       continue;
2272     }
2273     const Constant *C = cast<Constant>(V);
2274     unsigned Code = -1U;
2275     unsigned AbbrevToUse = 0;
2276     if (C->isNullValue()) {
2277       Code = bitc::CST_CODE_NULL;
2278     } else if (isa<UndefValue>(C)) {
2279       Code = bitc::CST_CODE_UNDEF;
2280     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2281       if (IV->getBitWidth() <= 64) {
2282         uint64_t V = IV->getSExtValue();
2283         emitSignedInt64(Record, V);
2284         Code = bitc::CST_CODE_INTEGER;
2285         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2286       } else {                             // Wide integers, > 64 bits in size.
2287         // We have an arbitrary precision integer value to write whose
2288         // bit width is > 64. However, in canonical unsigned integer
2289         // format it is likely that the high bits are going to be zero.
2290         // So, we only write the number of active words.
2291         unsigned NWords = IV->getValue().getActiveWords();
2292         const uint64_t *RawWords = IV->getValue().getRawData();
2293         for (unsigned i = 0; i != NWords; ++i) {
2294           emitSignedInt64(Record, RawWords[i]);
2295         }
2296         Code = bitc::CST_CODE_WIDE_INTEGER;
2297       }
2298     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2299       Code = bitc::CST_CODE_FLOAT;
2300       Type *Ty = CFP->getType();
2301       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2302         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2303       } else if (Ty->isX86_FP80Ty()) {
2304         // api needed to prevent premature destruction
2305         // bits are not in the same order as a normal i80 APInt, compensate.
2306         APInt api = CFP->getValueAPF().bitcastToAPInt();
2307         const uint64_t *p = api.getRawData();
2308         Record.push_back((p[1] << 48) | (p[0] >> 16));
2309         Record.push_back(p[0] & 0xffffLL);
2310       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2311         APInt api = CFP->getValueAPF().bitcastToAPInt();
2312         const uint64_t *p = api.getRawData();
2313         Record.push_back(p[0]);
2314         Record.push_back(p[1]);
2315       } else {
2316         assert(0 && "Unknown FP type!");
2317       }
2318     } else if (isa<ConstantDataSequential>(C) &&
2319                cast<ConstantDataSequential>(C)->isString()) {
2320       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2321       // Emit constant strings specially.
2322       unsigned NumElts = Str->getNumElements();
2323       // If this is a null-terminated string, use the denser CSTRING encoding.
2324       if (Str->isCString()) {
2325         Code = bitc::CST_CODE_CSTRING;
2326         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2327       } else {
2328         Code = bitc::CST_CODE_STRING;
2329         AbbrevToUse = String8Abbrev;
2330       }
2331       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2332       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2333       for (unsigned i = 0; i != NumElts; ++i) {
2334         unsigned char V = Str->getElementAsInteger(i);
2335         Record.push_back(V);
2336         isCStr7 &= (V & 128) == 0;
2337         if (isCStrChar6)
2338           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2339       }
2340 
2341       if (isCStrChar6)
2342         AbbrevToUse = CString6Abbrev;
2343       else if (isCStr7)
2344         AbbrevToUse = CString7Abbrev;
2345     } else if (const ConstantDataSequential *CDS =
2346                   dyn_cast<ConstantDataSequential>(C)) {
2347       Code = bitc::CST_CODE_DATA;
2348       Type *EltTy = CDS->getType()->getElementType();
2349       if (isa<IntegerType>(EltTy)) {
2350         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2351           Record.push_back(CDS->getElementAsInteger(i));
2352       } else {
2353         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2354           Record.push_back(
2355               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2356       }
2357     } else if (isa<ConstantAggregate>(C)) {
2358       Code = bitc::CST_CODE_AGGREGATE;
2359       for (const Value *Op : C->operands())
2360         Record.push_back(VE.getValueID(Op));
2361       AbbrevToUse = AggregateAbbrev;
2362     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2363       switch (CE->getOpcode()) {
2364       default:
2365         if (Instruction::isCast(CE->getOpcode())) {
2366           Code = bitc::CST_CODE_CE_CAST;
2367           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2368           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2369           Record.push_back(VE.getValueID(C->getOperand(0)));
2370           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2371         } else {
2372           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2373           Code = bitc::CST_CODE_CE_BINOP;
2374           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2375           Record.push_back(VE.getValueID(C->getOperand(0)));
2376           Record.push_back(VE.getValueID(C->getOperand(1)));
2377           uint64_t Flags = getOptimizationFlags(CE);
2378           if (Flags != 0)
2379             Record.push_back(Flags);
2380         }
2381         break;
2382       case Instruction::GetElementPtr: {
2383         Code = bitc::CST_CODE_CE_GEP;
2384         const auto *GO = cast<GEPOperator>(C);
2385         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2386         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2387           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2388           Record.push_back((*Idx << 1) | GO->isInBounds());
2389         } else if (GO->isInBounds())
2390           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2391         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2392           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2393           Record.push_back(VE.getValueID(C->getOperand(i)));
2394         }
2395         break;
2396       }
2397       case Instruction::Select:
2398         Code = bitc::CST_CODE_CE_SELECT;
2399         Record.push_back(VE.getValueID(C->getOperand(0)));
2400         Record.push_back(VE.getValueID(C->getOperand(1)));
2401         Record.push_back(VE.getValueID(C->getOperand(2)));
2402         break;
2403       case Instruction::ExtractElement:
2404         Code = bitc::CST_CODE_CE_EXTRACTELT;
2405         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2406         Record.push_back(VE.getValueID(C->getOperand(0)));
2407         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2408         Record.push_back(VE.getValueID(C->getOperand(1)));
2409         break;
2410       case Instruction::InsertElement:
2411         Code = bitc::CST_CODE_CE_INSERTELT;
2412         Record.push_back(VE.getValueID(C->getOperand(0)));
2413         Record.push_back(VE.getValueID(C->getOperand(1)));
2414         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2415         Record.push_back(VE.getValueID(C->getOperand(2)));
2416         break;
2417       case Instruction::ShuffleVector:
2418         // If the return type and argument types are the same, this is a
2419         // standard shufflevector instruction.  If the types are different,
2420         // then the shuffle is widening or truncating the input vectors, and
2421         // the argument type must also be encoded.
2422         if (C->getType() == C->getOperand(0)->getType()) {
2423           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2424         } else {
2425           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2426           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2427         }
2428         Record.push_back(VE.getValueID(C->getOperand(0)));
2429         Record.push_back(VE.getValueID(C->getOperand(1)));
2430         Record.push_back(VE.getValueID(C->getOperand(2)));
2431         break;
2432       case Instruction::ICmp:
2433       case Instruction::FCmp:
2434         Code = bitc::CST_CODE_CE_CMP;
2435         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2436         Record.push_back(VE.getValueID(C->getOperand(0)));
2437         Record.push_back(VE.getValueID(C->getOperand(1)));
2438         Record.push_back(CE->getPredicate());
2439         break;
2440       }
2441     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2442       Code = bitc::CST_CODE_BLOCKADDRESS;
2443       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2444       Record.push_back(VE.getValueID(BA->getFunction()));
2445       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2446     } else {
2447 #ifndef NDEBUG
2448       C->dump();
2449 #endif
2450       llvm_unreachable("Unknown constant!");
2451     }
2452     Stream.EmitRecord(Code, Record, AbbrevToUse);
2453     Record.clear();
2454   }
2455 
2456   Stream.ExitBlock();
2457 }
2458 
2459 void ModuleBitcodeWriter::writeModuleConstants() {
2460   const ValueEnumerator::ValueList &Vals = VE.getValues();
2461 
2462   // Find the first constant to emit, which is the first non-globalvalue value.
2463   // We know globalvalues have been emitted by WriteModuleInfo.
2464   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2465     if (!isa<GlobalValue>(Vals[i].first)) {
2466       writeConstants(i, Vals.size(), true);
2467       return;
2468     }
2469   }
2470 }
2471 
2472 /// pushValueAndType - The file has to encode both the value and type id for
2473 /// many values, because we need to know what type to create for forward
2474 /// references.  However, most operands are not forward references, so this type
2475 /// field is not needed.
2476 ///
2477 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2478 /// instruction ID, then it is a forward reference, and it also includes the
2479 /// type ID.  The value ID that is written is encoded relative to the InstID.
2480 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2481                                            SmallVectorImpl<unsigned> &Vals) {
2482   unsigned ValID = VE.getValueID(V);
2483   // Make encoding relative to the InstID.
2484   Vals.push_back(InstID - ValID);
2485   if (ValID >= InstID) {
2486     Vals.push_back(VE.getTypeID(V->getType()));
2487     return true;
2488   }
2489   return false;
2490 }
2491 
2492 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2493                                               unsigned InstID) {
2494   SmallVector<unsigned, 64> Record;
2495   LLVMContext &C = CS.getInstruction()->getContext();
2496 
2497   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2498     const auto &Bundle = CS.getOperandBundleAt(i);
2499     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2500 
2501     for (auto &Input : Bundle.Inputs)
2502       pushValueAndType(Input, InstID, Record);
2503 
2504     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2505     Record.clear();
2506   }
2507 }
2508 
2509 /// pushValue - Like pushValueAndType, but where the type of the value is
2510 /// omitted (perhaps it was already encoded in an earlier operand).
2511 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2512                                     SmallVectorImpl<unsigned> &Vals) {
2513   unsigned ValID = VE.getValueID(V);
2514   Vals.push_back(InstID - ValID);
2515 }
2516 
2517 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2518                                           SmallVectorImpl<uint64_t> &Vals) {
2519   unsigned ValID = VE.getValueID(V);
2520   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2521   emitSignedInt64(Vals, diff);
2522 }
2523 
2524 /// WriteInstruction - Emit an instruction to the specified stream.
2525 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2526                                            unsigned InstID,
2527                                            SmallVectorImpl<unsigned> &Vals) {
2528   unsigned Code = 0;
2529   unsigned AbbrevToUse = 0;
2530   VE.setInstructionID(&I);
2531   switch (I.getOpcode()) {
2532   default:
2533     if (Instruction::isCast(I.getOpcode())) {
2534       Code = bitc::FUNC_CODE_INST_CAST;
2535       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2536         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2537       Vals.push_back(VE.getTypeID(I.getType()));
2538       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2539     } else {
2540       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2541       Code = bitc::FUNC_CODE_INST_BINOP;
2542       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2543         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2544       pushValue(I.getOperand(1), InstID, Vals);
2545       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2546       uint64_t Flags = getOptimizationFlags(&I);
2547       if (Flags != 0) {
2548         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2549           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2550         Vals.push_back(Flags);
2551       }
2552     }
2553     break;
2554 
2555   case Instruction::GetElementPtr: {
2556     Code = bitc::FUNC_CODE_INST_GEP;
2557     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2558     auto &GEPInst = cast<GetElementPtrInst>(I);
2559     Vals.push_back(GEPInst.isInBounds());
2560     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2561     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2562       pushValueAndType(I.getOperand(i), InstID, Vals);
2563     break;
2564   }
2565   case Instruction::ExtractValue: {
2566     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2567     pushValueAndType(I.getOperand(0), InstID, Vals);
2568     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2569     Vals.append(EVI->idx_begin(), EVI->idx_end());
2570     break;
2571   }
2572   case Instruction::InsertValue: {
2573     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2574     pushValueAndType(I.getOperand(0), InstID, Vals);
2575     pushValueAndType(I.getOperand(1), InstID, Vals);
2576     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2577     Vals.append(IVI->idx_begin(), IVI->idx_end());
2578     break;
2579   }
2580   case Instruction::Select:
2581     Code = bitc::FUNC_CODE_INST_VSELECT;
2582     pushValueAndType(I.getOperand(1), InstID, Vals);
2583     pushValue(I.getOperand(2), InstID, Vals);
2584     pushValueAndType(I.getOperand(0), InstID, Vals);
2585     break;
2586   case Instruction::ExtractElement:
2587     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2588     pushValueAndType(I.getOperand(0), InstID, Vals);
2589     pushValueAndType(I.getOperand(1), InstID, Vals);
2590     break;
2591   case Instruction::InsertElement:
2592     Code = bitc::FUNC_CODE_INST_INSERTELT;
2593     pushValueAndType(I.getOperand(0), InstID, Vals);
2594     pushValue(I.getOperand(1), InstID, Vals);
2595     pushValueAndType(I.getOperand(2), InstID, Vals);
2596     break;
2597   case Instruction::ShuffleVector:
2598     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2599     pushValueAndType(I.getOperand(0), InstID, Vals);
2600     pushValue(I.getOperand(1), InstID, Vals);
2601     pushValue(I.getOperand(2), InstID, Vals);
2602     break;
2603   case Instruction::ICmp:
2604   case Instruction::FCmp: {
2605     // compare returning Int1Ty or vector of Int1Ty
2606     Code = bitc::FUNC_CODE_INST_CMP2;
2607     pushValueAndType(I.getOperand(0), InstID, Vals);
2608     pushValue(I.getOperand(1), InstID, Vals);
2609     Vals.push_back(cast<CmpInst>(I).getPredicate());
2610     uint64_t Flags = getOptimizationFlags(&I);
2611     if (Flags != 0)
2612       Vals.push_back(Flags);
2613     break;
2614   }
2615 
2616   case Instruction::Ret:
2617     {
2618       Code = bitc::FUNC_CODE_INST_RET;
2619       unsigned NumOperands = I.getNumOperands();
2620       if (NumOperands == 0)
2621         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2622       else if (NumOperands == 1) {
2623         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2624           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2625       } else {
2626         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2627           pushValueAndType(I.getOperand(i), InstID, Vals);
2628       }
2629     }
2630     break;
2631   case Instruction::Br:
2632     {
2633       Code = bitc::FUNC_CODE_INST_BR;
2634       const BranchInst &II = cast<BranchInst>(I);
2635       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2636       if (II.isConditional()) {
2637         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2638         pushValue(II.getCondition(), InstID, Vals);
2639       }
2640     }
2641     break;
2642   case Instruction::Switch:
2643     {
2644       Code = bitc::FUNC_CODE_INST_SWITCH;
2645       const SwitchInst &SI = cast<SwitchInst>(I);
2646       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2647       pushValue(SI.getCondition(), InstID, Vals);
2648       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2649       for (auto Case : SI.cases()) {
2650         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2651         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2652       }
2653     }
2654     break;
2655   case Instruction::IndirectBr:
2656     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2657     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2658     // Encode the address operand as relative, but not the basic blocks.
2659     pushValue(I.getOperand(0), InstID, Vals);
2660     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2661       Vals.push_back(VE.getValueID(I.getOperand(i)));
2662     break;
2663 
2664   case Instruction::Invoke: {
2665     const InvokeInst *II = cast<InvokeInst>(&I);
2666     const Value *Callee = II->getCalledValue();
2667     FunctionType *FTy = II->getFunctionType();
2668 
2669     if (II->hasOperandBundles())
2670       writeOperandBundles(II, InstID);
2671 
2672     Code = bitc::FUNC_CODE_INST_INVOKE;
2673 
2674     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2675     Vals.push_back(II->getCallingConv() | 1 << 13);
2676     Vals.push_back(VE.getValueID(II->getNormalDest()));
2677     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2678     Vals.push_back(VE.getTypeID(FTy));
2679     pushValueAndType(Callee, InstID, Vals);
2680 
2681     // Emit value #'s for the fixed parameters.
2682     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2683       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2684 
2685     // Emit type/value pairs for varargs params.
2686     if (FTy->isVarArg()) {
2687       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2688            i != e; ++i)
2689         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2690     }
2691     break;
2692   }
2693   case Instruction::Resume:
2694     Code = bitc::FUNC_CODE_INST_RESUME;
2695     pushValueAndType(I.getOperand(0), InstID, Vals);
2696     break;
2697   case Instruction::CleanupRet: {
2698     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2699     const auto &CRI = cast<CleanupReturnInst>(I);
2700     pushValue(CRI.getCleanupPad(), InstID, Vals);
2701     if (CRI.hasUnwindDest())
2702       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2703     break;
2704   }
2705   case Instruction::CatchRet: {
2706     Code = bitc::FUNC_CODE_INST_CATCHRET;
2707     const auto &CRI = cast<CatchReturnInst>(I);
2708     pushValue(CRI.getCatchPad(), InstID, Vals);
2709     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2710     break;
2711   }
2712   case Instruction::CleanupPad:
2713   case Instruction::CatchPad: {
2714     const auto &FuncletPad = cast<FuncletPadInst>(I);
2715     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2716                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2717     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2718 
2719     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2720     Vals.push_back(NumArgOperands);
2721     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2722       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2723     break;
2724   }
2725   case Instruction::CatchSwitch: {
2726     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2727     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2728 
2729     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2730 
2731     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2732     Vals.push_back(NumHandlers);
2733     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2734       Vals.push_back(VE.getValueID(CatchPadBB));
2735 
2736     if (CatchSwitch.hasUnwindDest())
2737       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2738     break;
2739   }
2740   case Instruction::Unreachable:
2741     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2742     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2743     break;
2744 
2745   case Instruction::PHI: {
2746     const PHINode &PN = cast<PHINode>(I);
2747     Code = bitc::FUNC_CODE_INST_PHI;
2748     // With the newer instruction encoding, forward references could give
2749     // negative valued IDs.  This is most common for PHIs, so we use
2750     // signed VBRs.
2751     SmallVector<uint64_t, 128> Vals64;
2752     Vals64.push_back(VE.getTypeID(PN.getType()));
2753     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2754       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2755       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2756     }
2757     // Emit a Vals64 vector and exit.
2758     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2759     Vals64.clear();
2760     return;
2761   }
2762 
2763   case Instruction::LandingPad: {
2764     const LandingPadInst &LP = cast<LandingPadInst>(I);
2765     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2766     Vals.push_back(VE.getTypeID(LP.getType()));
2767     Vals.push_back(LP.isCleanup());
2768     Vals.push_back(LP.getNumClauses());
2769     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2770       if (LP.isCatch(I))
2771         Vals.push_back(LandingPadInst::Catch);
2772       else
2773         Vals.push_back(LandingPadInst::Filter);
2774       pushValueAndType(LP.getClause(I), InstID, Vals);
2775     }
2776     break;
2777   }
2778 
2779   case Instruction::Alloca: {
2780     Code = bitc::FUNC_CODE_INST_ALLOCA;
2781     const AllocaInst &AI = cast<AllocaInst>(I);
2782     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2783     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2784     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2785     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2786     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2787            "not enough bits for maximum alignment");
2788     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2789     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2790     AlignRecord |= 1 << 6;
2791     AlignRecord |= AI.isSwiftError() << 7;
2792     Vals.push_back(AlignRecord);
2793     break;
2794   }
2795 
2796   case Instruction::Load:
2797     if (cast<LoadInst>(I).isAtomic()) {
2798       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2799       pushValueAndType(I.getOperand(0), InstID, Vals);
2800     } else {
2801       Code = bitc::FUNC_CODE_INST_LOAD;
2802       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2803         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2804     }
2805     Vals.push_back(VE.getTypeID(I.getType()));
2806     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2807     Vals.push_back(cast<LoadInst>(I).isVolatile());
2808     if (cast<LoadInst>(I).isAtomic()) {
2809       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2810       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2811     }
2812     break;
2813   case Instruction::Store:
2814     if (cast<StoreInst>(I).isAtomic())
2815       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2816     else
2817       Code = bitc::FUNC_CODE_INST_STORE;
2818     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2819     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2820     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2821     Vals.push_back(cast<StoreInst>(I).isVolatile());
2822     if (cast<StoreInst>(I).isAtomic()) {
2823       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2824       Vals.push_back(
2825           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2826     }
2827     break;
2828   case Instruction::AtomicCmpXchg:
2829     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2830     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2831     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2832     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2833     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2834     Vals.push_back(
2835         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2836     Vals.push_back(
2837         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2838     Vals.push_back(
2839         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2840     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2841     break;
2842   case Instruction::AtomicRMW:
2843     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2844     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2845     pushValue(I.getOperand(1), InstID, Vals);        // val.
2846     Vals.push_back(
2847         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2848     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2849     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2850     Vals.push_back(
2851         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2852     break;
2853   case Instruction::Fence:
2854     Code = bitc::FUNC_CODE_INST_FENCE;
2855     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2856     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2857     break;
2858   case Instruction::Call: {
2859     const CallInst &CI = cast<CallInst>(I);
2860     FunctionType *FTy = CI.getFunctionType();
2861 
2862     if (CI.hasOperandBundles())
2863       writeOperandBundles(&CI, InstID);
2864 
2865     Code = bitc::FUNC_CODE_INST_CALL;
2866 
2867     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2868 
2869     unsigned Flags = getOptimizationFlags(&I);
2870     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2871                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2872                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2873                    1 << bitc::CALL_EXPLICIT_TYPE |
2874                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2875                    unsigned(Flags != 0) << bitc::CALL_FMF);
2876     if (Flags != 0)
2877       Vals.push_back(Flags);
2878 
2879     Vals.push_back(VE.getTypeID(FTy));
2880     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2881 
2882     // Emit value #'s for the fixed parameters.
2883     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2884       // Check for labels (can happen with asm labels).
2885       if (FTy->getParamType(i)->isLabelTy())
2886         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2887       else
2888         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2889     }
2890 
2891     // Emit type/value pairs for varargs params.
2892     if (FTy->isVarArg()) {
2893       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2894            i != e; ++i)
2895         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2896     }
2897     break;
2898   }
2899   case Instruction::VAArg:
2900     Code = bitc::FUNC_CODE_INST_VAARG;
2901     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2902     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2903     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2904     break;
2905   }
2906 
2907   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2908   Vals.clear();
2909 }
2910 
2911 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2912 /// to allow clients to efficiently find the function body.
2913 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2914   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2915   // Get the offset of the VST we are writing, and backpatch it into
2916   // the VST forward declaration record.
2917   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2918   // The BitcodeStartBit was the stream offset of the identification block.
2919   VSTOffset -= bitcodeStartBit();
2920   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2921   // Note that we add 1 here because the offset is relative to one word
2922   // before the start of the identification block, which was historically
2923   // always the start of the regular bitcode header.
2924   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2925 
2926   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2927 
2928   auto Abbv = std::make_shared<BitCodeAbbrev>();
2929   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2932   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2933 
2934   for (const Function &F : M) {
2935     uint64_t Record[2];
2936 
2937     if (F.isDeclaration())
2938       continue;
2939 
2940     Record[0] = VE.getValueID(&F);
2941 
2942     // Save the word offset of the function (from the start of the
2943     // actual bitcode written to the stream).
2944     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2945     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2946     // Note that we add 1 here because the offset is relative to one word
2947     // before the start of the identification block, which was historically
2948     // always the start of the regular bitcode header.
2949     Record[1] = BitcodeIndex / 32 + 1;
2950 
2951     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2952   }
2953 
2954   Stream.ExitBlock();
2955 }
2956 
2957 /// Emit names for arguments, instructions and basic blocks in a function.
2958 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2959     const ValueSymbolTable &VST) {
2960   if (VST.empty())
2961     return;
2962 
2963   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2964 
2965   // FIXME: Set up the abbrev, we know how many values there are!
2966   // FIXME: We know if the type names can use 7-bit ascii.
2967   SmallVector<uint64_t, 64> NameVals;
2968 
2969   for (const ValueName &Name : VST) {
2970     // Figure out the encoding to use for the name.
2971     StringEncoding Bits = getStringEncoding(Name.getKey());
2972 
2973     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2974     NameVals.push_back(VE.getValueID(Name.getValue()));
2975 
2976     // VST_CODE_ENTRY:   [valueid, namechar x N]
2977     // VST_CODE_BBENTRY: [bbid, namechar x N]
2978     unsigned Code;
2979     if (isa<BasicBlock>(Name.getValue())) {
2980       Code = bitc::VST_CODE_BBENTRY;
2981       if (Bits == SE_Char6)
2982         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2983     } else {
2984       Code = bitc::VST_CODE_ENTRY;
2985       if (Bits == SE_Char6)
2986         AbbrevToUse = VST_ENTRY_6_ABBREV;
2987       else if (Bits == SE_Fixed7)
2988         AbbrevToUse = VST_ENTRY_7_ABBREV;
2989     }
2990 
2991     for (const auto P : Name.getKey())
2992       NameVals.push_back((unsigned char)P);
2993 
2994     // Emit the finished record.
2995     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2996     NameVals.clear();
2997   }
2998 
2999   Stream.ExitBlock();
3000 }
3001 
3002 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3003   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3004   unsigned Code;
3005   if (isa<BasicBlock>(Order.V))
3006     Code = bitc::USELIST_CODE_BB;
3007   else
3008     Code = bitc::USELIST_CODE_DEFAULT;
3009 
3010   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3011   Record.push_back(VE.getValueID(Order.V));
3012   Stream.EmitRecord(Code, Record);
3013 }
3014 
3015 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3016   assert(VE.shouldPreserveUseListOrder() &&
3017          "Expected to be preserving use-list order");
3018 
3019   auto hasMore = [&]() {
3020     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3021   };
3022   if (!hasMore())
3023     // Nothing to do.
3024     return;
3025 
3026   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3027   while (hasMore()) {
3028     writeUseList(std::move(VE.UseListOrders.back()));
3029     VE.UseListOrders.pop_back();
3030   }
3031   Stream.ExitBlock();
3032 }
3033 
3034 /// Emit a function body to the module stream.
3035 void ModuleBitcodeWriter::writeFunction(
3036     const Function &F,
3037     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3038   // Save the bitcode index of the start of this function block for recording
3039   // in the VST.
3040   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3041 
3042   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3043   VE.incorporateFunction(F);
3044 
3045   SmallVector<unsigned, 64> Vals;
3046 
3047   // Emit the number of basic blocks, so the reader can create them ahead of
3048   // time.
3049   Vals.push_back(VE.getBasicBlocks().size());
3050   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3051   Vals.clear();
3052 
3053   // If there are function-local constants, emit them now.
3054   unsigned CstStart, CstEnd;
3055   VE.getFunctionConstantRange(CstStart, CstEnd);
3056   writeConstants(CstStart, CstEnd, false);
3057 
3058   // If there is function-local metadata, emit it now.
3059   writeFunctionMetadata(F);
3060 
3061   // Keep a running idea of what the instruction ID is.
3062   unsigned InstID = CstEnd;
3063 
3064   bool NeedsMetadataAttachment = F.hasMetadata();
3065 
3066   DILocation *LastDL = nullptr;
3067   // Finally, emit all the instructions, in order.
3068   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3069     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3070          I != E; ++I) {
3071       writeInstruction(*I, InstID, Vals);
3072 
3073       if (!I->getType()->isVoidTy())
3074         ++InstID;
3075 
3076       // If the instruction has metadata, write a metadata attachment later.
3077       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3078 
3079       // If the instruction has a debug location, emit it.
3080       DILocation *DL = I->getDebugLoc();
3081       if (!DL)
3082         continue;
3083 
3084       if (DL == LastDL) {
3085         // Just repeat the same debug loc as last time.
3086         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3087         continue;
3088       }
3089 
3090       Vals.push_back(DL->getLine());
3091       Vals.push_back(DL->getColumn());
3092       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3093       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3094       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3095       Vals.clear();
3096 
3097       LastDL = DL;
3098     }
3099 
3100   // Emit names for all the instructions etc.
3101   if (auto *Symtab = F.getValueSymbolTable())
3102     writeFunctionLevelValueSymbolTable(*Symtab);
3103 
3104   if (NeedsMetadataAttachment)
3105     writeFunctionMetadataAttachment(F);
3106   if (VE.shouldPreserveUseListOrder())
3107     writeUseListBlock(&F);
3108   VE.purgeFunction();
3109   Stream.ExitBlock();
3110 }
3111 
3112 // Emit blockinfo, which defines the standard abbreviations etc.
3113 void ModuleBitcodeWriter::writeBlockInfo() {
3114   // We only want to emit block info records for blocks that have multiple
3115   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3116   // Other blocks can define their abbrevs inline.
3117   Stream.EnterBlockInfoBlock();
3118 
3119   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3120     auto Abbv = std::make_shared<BitCodeAbbrev>();
3121     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3122     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3123     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3125     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3126         VST_ENTRY_8_ABBREV)
3127       llvm_unreachable("Unexpected abbrev ordering!");
3128   }
3129 
3130   { // 7-bit fixed width VST_CODE_ENTRY strings.
3131     auto Abbv = std::make_shared<BitCodeAbbrev>();
3132     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3133     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3134     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3135     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3136     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3137         VST_ENTRY_7_ABBREV)
3138       llvm_unreachable("Unexpected abbrev ordering!");
3139   }
3140   { // 6-bit char6 VST_CODE_ENTRY strings.
3141     auto Abbv = std::make_shared<BitCodeAbbrev>();
3142     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3143     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3144     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3146     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3147         VST_ENTRY_6_ABBREV)
3148       llvm_unreachable("Unexpected abbrev ordering!");
3149   }
3150   { // 6-bit char6 VST_CODE_BBENTRY strings.
3151     auto Abbv = std::make_shared<BitCodeAbbrev>();
3152     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3153     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3154     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3156     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3157         VST_BBENTRY_6_ABBREV)
3158       llvm_unreachable("Unexpected abbrev ordering!");
3159   }
3160 
3161   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3162     auto Abbv = std::make_shared<BitCodeAbbrev>();
3163     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3164     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3165                               VE.computeBitsRequiredForTypeIndicies()));
3166     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3167         CONSTANTS_SETTYPE_ABBREV)
3168       llvm_unreachable("Unexpected abbrev ordering!");
3169   }
3170 
3171   { // INTEGER abbrev for CONSTANTS_BLOCK.
3172     auto Abbv = std::make_shared<BitCodeAbbrev>();
3173     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3175     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3176         CONSTANTS_INTEGER_ABBREV)
3177       llvm_unreachable("Unexpected abbrev ordering!");
3178   }
3179 
3180   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3181     auto Abbv = std::make_shared<BitCodeAbbrev>();
3182     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3183     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3184     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3185                               VE.computeBitsRequiredForTypeIndicies()));
3186     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3187 
3188     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3189         CONSTANTS_CE_CAST_Abbrev)
3190       llvm_unreachable("Unexpected abbrev ordering!");
3191   }
3192   { // NULL abbrev for CONSTANTS_BLOCK.
3193     auto Abbv = std::make_shared<BitCodeAbbrev>();
3194     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3195     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3196         CONSTANTS_NULL_Abbrev)
3197       llvm_unreachable("Unexpected abbrev ordering!");
3198   }
3199 
3200   // FIXME: This should only use space for first class types!
3201 
3202   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3203     auto Abbv = std::make_shared<BitCodeAbbrev>();
3204     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3205     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3206     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3207                               VE.computeBitsRequiredForTypeIndicies()));
3208     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3209     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3210     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3211         FUNCTION_INST_LOAD_ABBREV)
3212       llvm_unreachable("Unexpected abbrev ordering!");
3213   }
3214   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3215     auto Abbv = std::make_shared<BitCodeAbbrev>();
3216     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3217     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3218     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3220     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3221         FUNCTION_INST_BINOP_ABBREV)
3222       llvm_unreachable("Unexpected abbrev ordering!");
3223   }
3224   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3225     auto Abbv = std::make_shared<BitCodeAbbrev>();
3226     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3227     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3228     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3229     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3230     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3231     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3232         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3233       llvm_unreachable("Unexpected abbrev ordering!");
3234   }
3235   { // INST_CAST abbrev for FUNCTION_BLOCK.
3236     auto Abbv = std::make_shared<BitCodeAbbrev>();
3237     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3238     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3239     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3240                               VE.computeBitsRequiredForTypeIndicies()));
3241     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3242     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3243         FUNCTION_INST_CAST_ABBREV)
3244       llvm_unreachable("Unexpected abbrev ordering!");
3245   }
3246 
3247   { // INST_RET abbrev for FUNCTION_BLOCK.
3248     auto Abbv = std::make_shared<BitCodeAbbrev>();
3249     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3250     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3251         FUNCTION_INST_RET_VOID_ABBREV)
3252       llvm_unreachable("Unexpected abbrev ordering!");
3253   }
3254   { // INST_RET abbrev for FUNCTION_BLOCK.
3255     auto Abbv = std::make_shared<BitCodeAbbrev>();
3256     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3257     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3258     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3259         FUNCTION_INST_RET_VAL_ABBREV)
3260       llvm_unreachable("Unexpected abbrev ordering!");
3261   }
3262   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3263     auto Abbv = std::make_shared<BitCodeAbbrev>();
3264     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3265     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3266         FUNCTION_INST_UNREACHABLE_ABBREV)
3267       llvm_unreachable("Unexpected abbrev ordering!");
3268   }
3269   {
3270     auto Abbv = std::make_shared<BitCodeAbbrev>();
3271     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3272     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3273     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3274                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3275     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3276     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3277     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3278         FUNCTION_INST_GEP_ABBREV)
3279       llvm_unreachable("Unexpected abbrev ordering!");
3280   }
3281 
3282   Stream.ExitBlock();
3283 }
3284 
3285 /// Write the module path strings, currently only used when generating
3286 /// a combined index file.
3287 void IndexBitcodeWriter::writeModStrings() {
3288   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3289 
3290   // TODO: See which abbrev sizes we actually need to emit
3291 
3292   // 8-bit fixed-width MST_ENTRY strings.
3293   auto Abbv = std::make_shared<BitCodeAbbrev>();
3294   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3295   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3296   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3297   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3298   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3299 
3300   // 7-bit fixed width MST_ENTRY strings.
3301   Abbv = std::make_shared<BitCodeAbbrev>();
3302   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3303   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3304   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3305   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3306   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3307 
3308   // 6-bit char6 MST_ENTRY strings.
3309   Abbv = std::make_shared<BitCodeAbbrev>();
3310   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3311   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3312   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3313   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3314   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3315 
3316   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3317   Abbv = std::make_shared<BitCodeAbbrev>();
3318   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3319   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3320   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3321   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3322   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3324   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3325 
3326   SmallVector<unsigned, 64> Vals;
3327   forEachModule(
3328       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3329         StringRef Key = MPSE.getKey();
3330         const auto &Value = MPSE.getValue();
3331         StringEncoding Bits = getStringEncoding(Key);
3332         unsigned AbbrevToUse = Abbrev8Bit;
3333         if (Bits == SE_Char6)
3334           AbbrevToUse = Abbrev6Bit;
3335         else if (Bits == SE_Fixed7)
3336           AbbrevToUse = Abbrev7Bit;
3337 
3338         Vals.push_back(Value.first);
3339         Vals.append(Key.begin(), Key.end());
3340 
3341         // Emit the finished record.
3342         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3343 
3344         // Emit an optional hash for the module now
3345         const auto &Hash = Value.second;
3346         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3347           Vals.assign(Hash.begin(), Hash.end());
3348           // Emit the hash record.
3349           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3350         }
3351 
3352         Vals.clear();
3353       });
3354   Stream.ExitBlock();
3355 }
3356 
3357 /// Write the function type metadata related records that need to appear before
3358 /// a function summary entry (whether per-module or combined).
3359 static void writeFunctionTypeMetadataRecords(
3360     BitstreamWriter &Stream, FunctionSummary *FS,
3361     std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3362   if (!FS->type_tests().empty()) {
3363     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3364     for (auto &TT : FS->type_tests())
3365       ReferencedTypeIds.insert(TT);
3366   }
3367 
3368   SmallVector<uint64_t, 64> Record;
3369 
3370   auto WriteVFuncIdVec = [&](uint64_t Ty,
3371                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3372     if (VFs.empty())
3373       return;
3374     Record.clear();
3375     for (auto &VF : VFs) {
3376       Record.push_back(VF.GUID);
3377       Record.push_back(VF.Offset);
3378       ReferencedTypeIds.insert(VF.GUID);
3379     }
3380     Stream.EmitRecord(Ty, Record);
3381   };
3382 
3383   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3384                   FS->type_test_assume_vcalls());
3385   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3386                   FS->type_checked_load_vcalls());
3387 
3388   auto WriteConstVCallVec = [&](uint64_t Ty,
3389                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3390     for (auto &VC : VCs) {
3391       Record.clear();
3392       Record.push_back(VC.VFunc.GUID);
3393       ReferencedTypeIds.insert(VC.VFunc.GUID);
3394       Record.push_back(VC.VFunc.Offset);
3395       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3396       Stream.EmitRecord(Ty, Record);
3397     }
3398   };
3399 
3400   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3401                      FS->type_test_assume_const_vcalls());
3402   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3403                      FS->type_checked_load_const_vcalls());
3404 }
3405 
3406 static void writeWholeProgramDevirtResolutionByArg(
3407     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3408     const WholeProgramDevirtResolution::ByArg &ByArg) {
3409   NameVals.push_back(args.size());
3410   NameVals.insert(NameVals.end(), args.begin(), args.end());
3411 
3412   NameVals.push_back(ByArg.TheKind);
3413   NameVals.push_back(ByArg.Info);
3414   NameVals.push_back(ByArg.Byte);
3415   NameVals.push_back(ByArg.Bit);
3416 }
3417 
3418 static void writeWholeProgramDevirtResolution(
3419     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3420     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3421   NameVals.push_back(Id);
3422 
3423   NameVals.push_back(Wpd.TheKind);
3424   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3425   NameVals.push_back(Wpd.SingleImplName.size());
3426 
3427   NameVals.push_back(Wpd.ResByArg.size());
3428   for (auto &A : Wpd.ResByArg)
3429     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3430 }
3431 
3432 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3433                                      StringTableBuilder &StrtabBuilder,
3434                                      const std::string &Id,
3435                                      const TypeIdSummary &Summary) {
3436   NameVals.push_back(StrtabBuilder.add(Id));
3437   NameVals.push_back(Id.size());
3438 
3439   NameVals.push_back(Summary.TTRes.TheKind);
3440   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3441   NameVals.push_back(Summary.TTRes.AlignLog2);
3442   NameVals.push_back(Summary.TTRes.SizeM1);
3443   NameVals.push_back(Summary.TTRes.BitMask);
3444   NameVals.push_back(Summary.TTRes.InlineBits);
3445 
3446   for (auto &W : Summary.WPDRes)
3447     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3448                                       W.second);
3449 }
3450 
3451 // Helper to emit a single function summary record.
3452 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3453     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3454     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3455     const Function &F) {
3456   NameVals.push_back(ValueID);
3457 
3458   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3459   std::set<GlobalValue::GUID> ReferencedTypeIds;
3460   writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3461 
3462   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3463   NameVals.push_back(FS->instCount());
3464   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3465   NameVals.push_back(FS->refs().size());
3466 
3467   for (auto &RI : FS->refs())
3468     NameVals.push_back(VE.getValueID(RI.getValue()));
3469 
3470   bool HasProfileData =
3471       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3472   for (auto &ECI : FS->calls()) {
3473     NameVals.push_back(getValueId(ECI.first));
3474     if (HasProfileData)
3475       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3476     else if (WriteRelBFToSummary)
3477       NameVals.push_back(ECI.second.RelBlockFreq);
3478   }
3479 
3480   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3481   unsigned Code =
3482       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3483                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3484                                              : bitc::FS_PERMODULE));
3485 
3486   // Emit the finished record.
3487   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3488   NameVals.clear();
3489 }
3490 
3491 // Collect the global value references in the given variable's initializer,
3492 // and emit them in a summary record.
3493 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3494     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3495     unsigned FSModRefsAbbrev) {
3496   auto VI = Index->getValueInfo(V.getGUID());
3497   if (!VI || VI.getSummaryList().empty()) {
3498     // Only declarations should not have a summary (a declaration might however
3499     // have a summary if the def was in module level asm).
3500     assert(V.isDeclaration());
3501     return;
3502   }
3503   auto *Summary = VI.getSummaryList()[0].get();
3504   NameVals.push_back(VE.getValueID(&V));
3505   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3506   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3507 
3508   unsigned SizeBeforeRefs = NameVals.size();
3509   for (auto &RI : VS->refs())
3510     NameVals.push_back(VE.getValueID(RI.getValue()));
3511   // Sort the refs for determinism output, the vector returned by FS->refs() has
3512   // been initialized from a DenseSet.
3513   llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3514 
3515   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3516                     FSModRefsAbbrev);
3517   NameVals.clear();
3518 }
3519 
3520 // Current version for the summary.
3521 // This is bumped whenever we introduce changes in the way some record are
3522 // interpreted, like flags for instance.
3523 static const uint64_t INDEX_VERSION = 4;
3524 
3525 /// Emit the per-module summary section alongside the rest of
3526 /// the module's bitcode.
3527 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3528   // By default we compile with ThinLTO if the module has a summary, but the
3529   // client can request full LTO with a module flag.
3530   bool IsThinLTO = true;
3531   if (auto *MD =
3532           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3533     IsThinLTO = MD->getZExtValue();
3534   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3535                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3536                        4);
3537 
3538   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3539 
3540   if (Index->begin() == Index->end()) {
3541     Stream.ExitBlock();
3542     return;
3543   }
3544 
3545   for (const auto &GVI : valueIds()) {
3546     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3547                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3548   }
3549 
3550   // Abbrev for FS_PERMODULE_PROFILE.
3551   auto Abbv = std::make_shared<BitCodeAbbrev>();
3552   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3553   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3554   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3556   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3558   // numrefs x valueid, n x (valueid, hotness)
3559   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3560   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3561   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3562 
3563   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
3564   Abbv = std::make_shared<BitCodeAbbrev>();
3565   if (WriteRelBFToSummary)
3566     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
3567   else
3568     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3569   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3570   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3571   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3572   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3573   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3574   // numrefs x valueid, n x (valueid [, rel_block_freq])
3575   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3576   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3577   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3578 
3579   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3580   Abbv = std::make_shared<BitCodeAbbrev>();
3581   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3582   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3583   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3584   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3585   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3586   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3587 
3588   // Abbrev for FS_ALIAS.
3589   Abbv = std::make_shared<BitCodeAbbrev>();
3590   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3591   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3592   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3593   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3594   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3595 
3596   SmallVector<uint64_t, 64> NameVals;
3597   // Iterate over the list of functions instead of the Index to
3598   // ensure the ordering is stable.
3599   for (const Function &F : M) {
3600     // Summary emission does not support anonymous functions, they have to
3601     // renamed using the anonymous function renaming pass.
3602     if (!F.hasName())
3603       report_fatal_error("Unexpected anonymous function when writing summary");
3604 
3605     ValueInfo VI = Index->getValueInfo(F.getGUID());
3606     if (!VI || VI.getSummaryList().empty()) {
3607       // Only declarations should not have a summary (a declaration might
3608       // however have a summary if the def was in module level asm).
3609       assert(F.isDeclaration());
3610       continue;
3611     }
3612     auto *Summary = VI.getSummaryList()[0].get();
3613     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3614                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3615   }
3616 
3617   // Capture references from GlobalVariable initializers, which are outside
3618   // of a function scope.
3619   for (const GlobalVariable &G : M.globals())
3620     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3621 
3622   for (const GlobalAlias &A : M.aliases()) {
3623     auto *Aliasee = A.getBaseObject();
3624     if (!Aliasee->hasName())
3625       // Nameless function don't have an entry in the summary, skip it.
3626       continue;
3627     auto AliasId = VE.getValueID(&A);
3628     auto AliaseeId = VE.getValueID(Aliasee);
3629     NameVals.push_back(AliasId);
3630     auto *Summary = Index->getGlobalValueSummary(A);
3631     AliasSummary *AS = cast<AliasSummary>(Summary);
3632     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3633     NameVals.push_back(AliaseeId);
3634     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3635     NameVals.clear();
3636   }
3637 
3638   Stream.ExitBlock();
3639 }
3640 
3641 /// Emit the combined summary section into the combined index file.
3642 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3643   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3644   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3645 
3646   // Write the index flags.
3647   uint64_t Flags = 0;
3648   if (Index.withGlobalValueDeadStripping())
3649     Flags |= 0x1;
3650   if (Index.skipModuleByDistributedBackend())
3651     Flags |= 0x2;
3652   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
3653 
3654   for (const auto &GVI : valueIds()) {
3655     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3656                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3657   }
3658 
3659   // Abbrev for FS_COMBINED.
3660   auto Abbv = std::make_shared<BitCodeAbbrev>();
3661   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3662   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3663   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3664   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3665   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3666   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3667   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3668   // numrefs x valueid, n x (valueid)
3669   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3670   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3671   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3672 
3673   // Abbrev for FS_COMBINED_PROFILE.
3674   Abbv = std::make_shared<BitCodeAbbrev>();
3675   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3676   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3677   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3678   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3679   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3680   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3681   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3682   // numrefs x valueid, n x (valueid, hotness)
3683   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3684   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3685   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3686 
3687   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3688   Abbv = std::make_shared<BitCodeAbbrev>();
3689   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3690   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3691   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3692   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3693   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3694   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3695   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3696 
3697   // Abbrev for FS_COMBINED_ALIAS.
3698   Abbv = std::make_shared<BitCodeAbbrev>();
3699   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3700   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3701   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3702   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3703   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3704   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3705 
3706   // The aliases are emitted as a post-pass, and will point to the value
3707   // id of the aliasee. Save them in a vector for post-processing.
3708   SmallVector<AliasSummary *, 64> Aliases;
3709 
3710   // Save the value id for each summary for alias emission.
3711   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3712 
3713   SmallVector<uint64_t, 64> NameVals;
3714 
3715   // Set that will be populated during call to writeFunctionTypeMetadataRecords
3716   // with the type ids referenced by this index file.
3717   std::set<GlobalValue::GUID> ReferencedTypeIds;
3718 
3719   // For local linkage, we also emit the original name separately
3720   // immediately after the record.
3721   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3722     if (!GlobalValue::isLocalLinkage(S.linkage()))
3723       return;
3724     NameVals.push_back(S.getOriginalName());
3725     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3726     NameVals.clear();
3727   };
3728 
3729   forEachSummary([&](GVInfo I, bool IsAliasee) {
3730     GlobalValueSummary *S = I.second;
3731     assert(S);
3732 
3733     auto ValueId = getValueId(I.first);
3734     assert(ValueId);
3735     SummaryToValueIdMap[S] = *ValueId;
3736 
3737     // If this is invoked for an aliasee, we want to record the above
3738     // mapping, but then not emit a summary entry (if the aliasee is
3739     // to be imported, we will invoke this separately with IsAliasee=false).
3740     if (IsAliasee)
3741       return;
3742 
3743     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3744       // Will process aliases as a post-pass because the reader wants all
3745       // global to be loaded first.
3746       Aliases.push_back(AS);
3747       return;
3748     }
3749 
3750     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3751       NameVals.push_back(*ValueId);
3752       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3753       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3754       for (auto &RI : VS->refs()) {
3755         auto RefValueId = getValueId(RI.getGUID());
3756         if (!RefValueId)
3757           continue;
3758         NameVals.push_back(*RefValueId);
3759       }
3760 
3761       // Emit the finished record.
3762       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3763                         FSModRefsAbbrev);
3764       NameVals.clear();
3765       MaybeEmitOriginalName(*S);
3766       return;
3767     }
3768 
3769     auto *FS = cast<FunctionSummary>(S);
3770     writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3771 
3772     NameVals.push_back(*ValueId);
3773     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3774     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3775     NameVals.push_back(FS->instCount());
3776     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3777     // Fill in below
3778     NameVals.push_back(0);
3779 
3780     unsigned Count = 0;
3781     for (auto &RI : FS->refs()) {
3782       auto RefValueId = getValueId(RI.getGUID());
3783       if (!RefValueId)
3784         continue;
3785       NameVals.push_back(*RefValueId);
3786       Count++;
3787     }
3788     NameVals[5] = Count;
3789 
3790     bool HasProfileData = false;
3791     for (auto &EI : FS->calls()) {
3792       HasProfileData |=
3793           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
3794       if (HasProfileData)
3795         break;
3796     }
3797 
3798     for (auto &EI : FS->calls()) {
3799       // If this GUID doesn't have a value id, it doesn't have a function
3800       // summary and we don't need to record any calls to it.
3801       GlobalValue::GUID GUID = EI.first.getGUID();
3802       auto CallValueId = getValueId(GUID);
3803       if (!CallValueId) {
3804         // For SamplePGO, the indirect call targets for local functions will
3805         // have its original name annotated in profile. We try to find the
3806         // corresponding PGOFuncName as the GUID.
3807         GUID = Index.getGUIDFromOriginalID(GUID);
3808         if (GUID == 0)
3809           continue;
3810         CallValueId = getValueId(GUID);
3811         if (!CallValueId)
3812           continue;
3813         // The mapping from OriginalId to GUID may return a GUID
3814         // that corresponds to a static variable. Filter it out here.
3815         // This can happen when
3816         // 1) There is a call to a library function which does not have
3817         // a CallValidId;
3818         // 2) There is a static variable with the  OriginalGUID identical
3819         // to the GUID of the library function in 1);
3820         // When this happens, the logic for SamplePGO kicks in and
3821         // the static variable in 2) will be found, which needs to be
3822         // filtered out.
3823         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3824         if (GVSum &&
3825             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3826           continue;
3827       }
3828       NameVals.push_back(*CallValueId);
3829       if (HasProfileData)
3830         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3831     }
3832 
3833     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3834     unsigned Code =
3835         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3836 
3837     // Emit the finished record.
3838     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3839     NameVals.clear();
3840     MaybeEmitOriginalName(*S);
3841   });
3842 
3843   for (auto *AS : Aliases) {
3844     auto AliasValueId = SummaryToValueIdMap[AS];
3845     assert(AliasValueId);
3846     NameVals.push_back(AliasValueId);
3847     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3848     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3849     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3850     assert(AliaseeValueId);
3851     NameVals.push_back(AliaseeValueId);
3852 
3853     // Emit the finished record.
3854     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3855     NameVals.clear();
3856     MaybeEmitOriginalName(*AS);
3857   }
3858 
3859   if (!Index.cfiFunctionDefs().empty()) {
3860     for (auto &S : Index.cfiFunctionDefs()) {
3861       NameVals.push_back(StrtabBuilder.add(S));
3862       NameVals.push_back(S.size());
3863     }
3864     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3865     NameVals.clear();
3866   }
3867 
3868   if (!Index.cfiFunctionDecls().empty()) {
3869     for (auto &S : Index.cfiFunctionDecls()) {
3870       NameVals.push_back(StrtabBuilder.add(S));
3871       NameVals.push_back(S.size());
3872     }
3873     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3874     NameVals.clear();
3875   }
3876 
3877   if (!Index.typeIds().empty()) {
3878     for (auto &S : Index.typeIds()) {
3879       // Skip if not referenced in any GV summary within this index file.
3880       if (!ReferencedTypeIds.count(GlobalValue::getGUID(S.first)))
3881         continue;
3882       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, S.first, S.second);
3883       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
3884       NameVals.clear();
3885     }
3886   }
3887 
3888   Stream.ExitBlock();
3889 }
3890 
3891 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3892 /// current llvm version, and a record for the epoch number.
3893 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3894   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3895 
3896   // Write the "user readable" string identifying the bitcode producer
3897   auto Abbv = std::make_shared<BitCodeAbbrev>();
3898   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3899   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3900   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3901   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3902   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3903                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3904 
3905   // Write the epoch version
3906   Abbv = std::make_shared<BitCodeAbbrev>();
3907   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3908   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3909   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3910   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3911   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3912   Stream.ExitBlock();
3913 }
3914 
3915 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3916   // Emit the module's hash.
3917   // MODULE_CODE_HASH: [5*i32]
3918   if (GenerateHash) {
3919     uint32_t Vals[5];
3920     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3921                                     Buffer.size() - BlockStartPos));
3922     StringRef Hash = Hasher.result();
3923     for (int Pos = 0; Pos < 20; Pos += 4) {
3924       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3925     }
3926 
3927     // Emit the finished record.
3928     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3929 
3930     if (ModHash)
3931       // Save the written hash value.
3932       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3933   }
3934 }
3935 
3936 void ModuleBitcodeWriter::write() {
3937   writeIdentificationBlock(Stream);
3938 
3939   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3940   size_t BlockStartPos = Buffer.size();
3941 
3942   writeModuleVersion();
3943 
3944   // Emit blockinfo, which defines the standard abbreviations etc.
3945   writeBlockInfo();
3946 
3947   // Emit information about attribute groups.
3948   writeAttributeGroupTable();
3949 
3950   // Emit information about parameter attributes.
3951   writeAttributeTable();
3952 
3953   // Emit information describing all of the types in the module.
3954   writeTypeTable();
3955 
3956   writeComdats();
3957 
3958   // Emit top-level description of module, including target triple, inline asm,
3959   // descriptors for global variables, and function prototype info.
3960   writeModuleInfo();
3961 
3962   // Emit constants.
3963   writeModuleConstants();
3964 
3965   // Emit metadata kind names.
3966   writeModuleMetadataKinds();
3967 
3968   // Emit metadata.
3969   writeModuleMetadata();
3970 
3971   // Emit module-level use-lists.
3972   if (VE.shouldPreserveUseListOrder())
3973     writeUseListBlock(nullptr);
3974 
3975   writeOperandBundleTags();
3976   writeSyncScopeNames();
3977 
3978   // Emit function bodies.
3979   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3980   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3981     if (!F->isDeclaration())
3982       writeFunction(*F, FunctionToBitcodeIndex);
3983 
3984   // Need to write after the above call to WriteFunction which populates
3985   // the summary information in the index.
3986   if (Index)
3987     writePerModuleGlobalValueSummary();
3988 
3989   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3990 
3991   writeModuleHash(BlockStartPos);
3992 
3993   Stream.ExitBlock();
3994 }
3995 
3996 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3997                                uint32_t &Position) {
3998   support::endian::write32le(&Buffer[Position], Value);
3999   Position += 4;
4000 }
4001 
4002 /// If generating a bc file on darwin, we have to emit a
4003 /// header and trailer to make it compatible with the system archiver.  To do
4004 /// this we emit the following header, and then emit a trailer that pads the
4005 /// file out to be a multiple of 16 bytes.
4006 ///
4007 /// struct bc_header {
4008 ///   uint32_t Magic;         // 0x0B17C0DE
4009 ///   uint32_t Version;       // Version, currently always 0.
4010 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4011 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4012 ///   uint32_t CPUType;       // CPU specifier.
4013 ///   ... potentially more later ...
4014 /// };
4015 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4016                                          const Triple &TT) {
4017   unsigned CPUType = ~0U;
4018 
4019   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4020   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4021   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4022   // specific constants here because they are implicitly part of the Darwin ABI.
4023   enum {
4024     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4025     DARWIN_CPU_TYPE_X86        = 7,
4026     DARWIN_CPU_TYPE_ARM        = 12,
4027     DARWIN_CPU_TYPE_POWERPC    = 18
4028   };
4029 
4030   Triple::ArchType Arch = TT.getArch();
4031   if (Arch == Triple::x86_64)
4032     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4033   else if (Arch == Triple::x86)
4034     CPUType = DARWIN_CPU_TYPE_X86;
4035   else if (Arch == Triple::ppc)
4036     CPUType = DARWIN_CPU_TYPE_POWERPC;
4037   else if (Arch == Triple::ppc64)
4038     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4039   else if (Arch == Triple::arm || Arch == Triple::thumb)
4040     CPUType = DARWIN_CPU_TYPE_ARM;
4041 
4042   // Traditional Bitcode starts after header.
4043   assert(Buffer.size() >= BWH_HeaderSize &&
4044          "Expected header size to be reserved");
4045   unsigned BCOffset = BWH_HeaderSize;
4046   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4047 
4048   // Write the magic and version.
4049   unsigned Position = 0;
4050   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4051   writeInt32ToBuffer(0, Buffer, Position); // Version.
4052   writeInt32ToBuffer(BCOffset, Buffer, Position);
4053   writeInt32ToBuffer(BCSize, Buffer, Position);
4054   writeInt32ToBuffer(CPUType, Buffer, Position);
4055 
4056   // If the file is not a multiple of 16 bytes, insert dummy padding.
4057   while (Buffer.size() & 15)
4058     Buffer.push_back(0);
4059 }
4060 
4061 /// Helper to write the header common to all bitcode files.
4062 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4063   // Emit the file header.
4064   Stream.Emit((unsigned)'B', 8);
4065   Stream.Emit((unsigned)'C', 8);
4066   Stream.Emit(0x0, 4);
4067   Stream.Emit(0xC, 4);
4068   Stream.Emit(0xE, 4);
4069   Stream.Emit(0xD, 4);
4070 }
4071 
4072 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
4073     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
4074   writeBitcodeHeader(*Stream);
4075 }
4076 
4077 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4078 
4079 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4080   Stream->EnterSubblock(Block, 3);
4081 
4082   auto Abbv = std::make_shared<BitCodeAbbrev>();
4083   Abbv->Add(BitCodeAbbrevOp(Record));
4084   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4085   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4086 
4087   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4088 
4089   Stream->ExitBlock();
4090 }
4091 
4092 void BitcodeWriter::writeSymtab() {
4093   assert(!WroteStrtab && !WroteSymtab);
4094 
4095   // If any module has module-level inline asm, we will require a registered asm
4096   // parser for the target so that we can create an accurate symbol table for
4097   // the module.
4098   for (Module *M : Mods) {
4099     if (M->getModuleInlineAsm().empty())
4100       continue;
4101 
4102     std::string Err;
4103     const Triple TT(M->getTargetTriple());
4104     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4105     if (!T || !T->hasMCAsmParser())
4106       return;
4107   }
4108 
4109   WroteSymtab = true;
4110   SmallVector<char, 0> Symtab;
4111   // The irsymtab::build function may be unable to create a symbol table if the
4112   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4113   // table is not required for correctness, but we still want to be able to
4114   // write malformed modules to bitcode files, so swallow the error.
4115   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4116     consumeError(std::move(E));
4117     return;
4118   }
4119 
4120   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4121             {Symtab.data(), Symtab.size()});
4122 }
4123 
4124 void BitcodeWriter::writeStrtab() {
4125   assert(!WroteStrtab);
4126 
4127   std::vector<char> Strtab;
4128   StrtabBuilder.finalizeInOrder();
4129   Strtab.resize(StrtabBuilder.getSize());
4130   StrtabBuilder.write((uint8_t *)Strtab.data());
4131 
4132   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4133             {Strtab.data(), Strtab.size()});
4134 
4135   WroteStrtab = true;
4136 }
4137 
4138 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4139   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4140   WroteStrtab = true;
4141 }
4142 
4143 void BitcodeWriter::writeModule(const Module &M,
4144                                 bool ShouldPreserveUseListOrder,
4145                                 const ModuleSummaryIndex *Index,
4146                                 bool GenerateHash, ModuleHash *ModHash) {
4147   assert(!WroteStrtab);
4148 
4149   // The Mods vector is used by irsymtab::build, which requires non-const
4150   // Modules in case it needs to materialize metadata. But the bitcode writer
4151   // requires that the module is materialized, so we can cast to non-const here,
4152   // after checking that it is in fact materialized.
4153   assert(M.isMaterialized());
4154   Mods.push_back(const_cast<Module *>(&M));
4155 
4156   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4157                                    ShouldPreserveUseListOrder, Index,
4158                                    GenerateHash, ModHash);
4159   ModuleWriter.write();
4160 }
4161 
4162 void BitcodeWriter::writeIndex(
4163     const ModuleSummaryIndex *Index,
4164     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4165   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4166                                  ModuleToSummariesForIndex);
4167   IndexWriter.write();
4168 }
4169 
4170 /// Write the specified module to the specified output stream.
4171 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4172                               bool ShouldPreserveUseListOrder,
4173                               const ModuleSummaryIndex *Index,
4174                               bool GenerateHash, ModuleHash *ModHash) {
4175   SmallVector<char, 0> Buffer;
4176   Buffer.reserve(256*1024);
4177 
4178   // If this is darwin or another generic macho target, reserve space for the
4179   // header.
4180   Triple TT(M.getTargetTriple());
4181   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4182     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4183 
4184   BitcodeWriter Writer(Buffer);
4185   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4186                      ModHash);
4187   Writer.writeSymtab();
4188   Writer.writeStrtab();
4189 
4190   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4191     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4192 
4193   // Write the generated bitstream to "Out".
4194   Out.write((char*)&Buffer.front(), Buffer.size());
4195 }
4196 
4197 void IndexBitcodeWriter::write() {
4198   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4199 
4200   writeModuleVersion();
4201 
4202   // Write the module paths in the combined index.
4203   writeModStrings();
4204 
4205   // Write the summary combined index records.
4206   writeCombinedGlobalValueSummary();
4207 
4208   Stream.ExitBlock();
4209 }
4210 
4211 // Write the specified module summary index to the given raw output stream,
4212 // where it will be written in a new bitcode block. This is used when
4213 // writing the combined index file for ThinLTO. When writing a subset of the
4214 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4215 void llvm::WriteIndexToFile(
4216     const ModuleSummaryIndex &Index, raw_ostream &Out,
4217     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4218   SmallVector<char, 0> Buffer;
4219   Buffer.reserve(256 * 1024);
4220 
4221   BitcodeWriter Writer(Buffer);
4222   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4223   Writer.writeStrtab();
4224 
4225   Out.write((char *)&Buffer.front(), Buffer.size());
4226 }
4227 
4228 namespace {
4229 
4230 /// Class to manage the bitcode writing for a thin link bitcode file.
4231 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4232   /// ModHash is for use in ThinLTO incremental build, generated while writing
4233   /// the module bitcode file.
4234   const ModuleHash *ModHash;
4235 
4236 public:
4237   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4238                         BitstreamWriter &Stream,
4239                         const ModuleSummaryIndex &Index,
4240                         const ModuleHash &ModHash)
4241       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4242                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4243         ModHash(&ModHash) {}
4244 
4245   void write();
4246 
4247 private:
4248   void writeSimplifiedModuleInfo();
4249 };
4250 
4251 } // end anonymous namespace
4252 
4253 // This function writes a simpilified module info for thin link bitcode file.
4254 // It only contains the source file name along with the name(the offset and
4255 // size in strtab) and linkage for global values. For the global value info
4256 // entry, in order to keep linkage at offset 5, there are three zeros used
4257 // as padding.
4258 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4259   SmallVector<unsigned, 64> Vals;
4260   // Emit the module's source file name.
4261   {
4262     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4263     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4264     if (Bits == SE_Char6)
4265       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4266     else if (Bits == SE_Fixed7)
4267       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4268 
4269     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4270     auto Abbv = std::make_shared<BitCodeAbbrev>();
4271     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4272     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4273     Abbv->Add(AbbrevOpToUse);
4274     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4275 
4276     for (const auto P : M.getSourceFileName())
4277       Vals.push_back((unsigned char)P);
4278 
4279     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4280     Vals.clear();
4281   }
4282 
4283   // Emit the global variable information.
4284   for (const GlobalVariable &GV : M.globals()) {
4285     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4286     Vals.push_back(StrtabBuilder.add(GV.getName()));
4287     Vals.push_back(GV.getName().size());
4288     Vals.push_back(0);
4289     Vals.push_back(0);
4290     Vals.push_back(0);
4291     Vals.push_back(getEncodedLinkage(GV));
4292 
4293     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4294     Vals.clear();
4295   }
4296 
4297   // Emit the function proto information.
4298   for (const Function &F : M) {
4299     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4300     Vals.push_back(StrtabBuilder.add(F.getName()));
4301     Vals.push_back(F.getName().size());
4302     Vals.push_back(0);
4303     Vals.push_back(0);
4304     Vals.push_back(0);
4305     Vals.push_back(getEncodedLinkage(F));
4306 
4307     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4308     Vals.clear();
4309   }
4310 
4311   // Emit the alias information.
4312   for (const GlobalAlias &A : M.aliases()) {
4313     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4314     Vals.push_back(StrtabBuilder.add(A.getName()));
4315     Vals.push_back(A.getName().size());
4316     Vals.push_back(0);
4317     Vals.push_back(0);
4318     Vals.push_back(0);
4319     Vals.push_back(getEncodedLinkage(A));
4320 
4321     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4322     Vals.clear();
4323   }
4324 
4325   // Emit the ifunc information.
4326   for (const GlobalIFunc &I : M.ifuncs()) {
4327     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4328     Vals.push_back(StrtabBuilder.add(I.getName()));
4329     Vals.push_back(I.getName().size());
4330     Vals.push_back(0);
4331     Vals.push_back(0);
4332     Vals.push_back(0);
4333     Vals.push_back(getEncodedLinkage(I));
4334 
4335     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4336     Vals.clear();
4337   }
4338 }
4339 
4340 void ThinLinkBitcodeWriter::write() {
4341   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4342 
4343   writeModuleVersion();
4344 
4345   writeSimplifiedModuleInfo();
4346 
4347   writePerModuleGlobalValueSummary();
4348 
4349   // Write module hash.
4350   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4351 
4352   Stream.ExitBlock();
4353 }
4354 
4355 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4356                                          const ModuleSummaryIndex &Index,
4357                                          const ModuleHash &ModHash) {
4358   assert(!WroteStrtab);
4359 
4360   // The Mods vector is used by irsymtab::build, which requires non-const
4361   // Modules in case it needs to materialize metadata. But the bitcode writer
4362   // requires that the module is materialized, so we can cast to non-const here,
4363   // after checking that it is in fact materialized.
4364   assert(M.isMaterialized());
4365   Mods.push_back(const_cast<Module *>(&M));
4366 
4367   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4368                                        ModHash);
4369   ThinLinkWriter.write();
4370 }
4371 
4372 // Write the specified thin link bitcode file to the given raw output stream,
4373 // where it will be written in a new bitcode block. This is used when
4374 // writing the per-module index file for ThinLTO.
4375 void llvm::WriteThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4376                                       const ModuleSummaryIndex &Index,
4377                                       const ModuleHash &ModHash) {
4378   SmallVector<char, 0> Buffer;
4379   Buffer.reserve(256 * 1024);
4380 
4381   BitcodeWriter Writer(Buffer);
4382   Writer.writeThinLinkBitcode(M, Index, ModHash);
4383   Writer.writeSymtab();
4384   Writer.writeStrtab();
4385 
4386   Out.write((char *)&Buffer.front(), Buffer.size());
4387 }
4388