xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 664aa868f57119e06dd56ad90625219ad1bb973a)
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::SpeculativeLoadHardening:
694     return bitc::ATTR_KIND_SPECULATIVE_LOAD_HARDENING;
695   case Attribute::SwiftError:
696     return bitc::ATTR_KIND_SWIFT_ERROR;
697   case Attribute::SwiftSelf:
698     return bitc::ATTR_KIND_SWIFT_SELF;
699   case Attribute::UWTable:
700     return bitc::ATTR_KIND_UW_TABLE;
701   case Attribute::WriteOnly:
702     return bitc::ATTR_KIND_WRITEONLY;
703   case Attribute::ZExt:
704     return bitc::ATTR_KIND_Z_EXT;
705   case Attribute::EndAttrKinds:
706     llvm_unreachable("Can not encode end-attribute kinds marker.");
707   case Attribute::None:
708     llvm_unreachable("Can not encode none-attribute.");
709   }
710 
711   llvm_unreachable("Trying to encode unknown attribute");
712 }
713 
714 void ModuleBitcodeWriter::writeAttributeGroupTable() {
715   const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
716       VE.getAttributeGroups();
717   if (AttrGrps.empty()) return;
718 
719   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
720 
721   SmallVector<uint64_t, 64> Record;
722   for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
723     unsigned AttrListIndex = Pair.first;
724     AttributeSet AS = Pair.second;
725     Record.push_back(VE.getAttributeGroupID(Pair));
726     Record.push_back(AttrListIndex);
727 
728     for (Attribute Attr : AS) {
729       if (Attr.isEnumAttribute()) {
730         Record.push_back(0);
731         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
732       } else if (Attr.isIntAttribute()) {
733         Record.push_back(1);
734         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
735         Record.push_back(Attr.getValueAsInt());
736       } else {
737         StringRef Kind = Attr.getKindAsString();
738         StringRef Val = Attr.getValueAsString();
739 
740         Record.push_back(Val.empty() ? 3 : 4);
741         Record.append(Kind.begin(), Kind.end());
742         Record.push_back(0);
743         if (!Val.empty()) {
744           Record.append(Val.begin(), Val.end());
745           Record.push_back(0);
746         }
747       }
748     }
749 
750     Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
751     Record.clear();
752   }
753 
754   Stream.ExitBlock();
755 }
756 
757 void ModuleBitcodeWriter::writeAttributeTable() {
758   const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
759   if (Attrs.empty()) return;
760 
761   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
762 
763   SmallVector<uint64_t, 64> Record;
764   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
765     AttributeList AL = Attrs[i];
766     for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
767       AttributeSet AS = AL.getAttributes(i);
768       if (AS.hasAttributes())
769         Record.push_back(VE.getAttributeGroupID({i, AS}));
770     }
771 
772     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
773     Record.clear();
774   }
775 
776   Stream.ExitBlock();
777 }
778 
779 /// WriteTypeTable - Write out the type table for a module.
780 void ModuleBitcodeWriter::writeTypeTable() {
781   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
782 
783   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
784   SmallVector<uint64_t, 64> TypeVals;
785 
786   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
787 
788   // Abbrev for TYPE_CODE_POINTER.
789   auto Abbv = std::make_shared<BitCodeAbbrev>();
790   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
791   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
792   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
793   unsigned PtrAbbrev = Stream.EmitAbbrev(std::move(Abbv));
794 
795   // Abbrev for TYPE_CODE_FUNCTION.
796   Abbv = std::make_shared<BitCodeAbbrev>();
797   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
798   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
799   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
800   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
801   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
802 
803   // Abbrev for TYPE_CODE_STRUCT_ANON.
804   Abbv = std::make_shared<BitCodeAbbrev>();
805   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
806   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
807   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
808   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
809   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
810 
811   // Abbrev for TYPE_CODE_STRUCT_NAME.
812   Abbv = std::make_shared<BitCodeAbbrev>();
813   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
814   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
815   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
816   unsigned StructNameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
817 
818   // Abbrev for TYPE_CODE_STRUCT_NAMED.
819   Abbv = std::make_shared<BitCodeAbbrev>();
820   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
821   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
822   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
823   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
824   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
825 
826   // Abbrev for TYPE_CODE_ARRAY.
827   Abbv = std::make_shared<BitCodeAbbrev>();
828   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
829   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
830   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
831   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
832 
833   // Emit an entry count so the reader can reserve space.
834   TypeVals.push_back(TypeList.size());
835   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
836   TypeVals.clear();
837 
838   // Loop over all of the types, emitting each in turn.
839   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
840     Type *T = TypeList[i];
841     int AbbrevToUse = 0;
842     unsigned Code = 0;
843 
844     switch (T->getTypeID()) {
845     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
846     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
847     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
848     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
849     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
850     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
851     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
852     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
853     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
854     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
855     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
856     case Type::IntegerTyID:
857       // INTEGER: [width]
858       Code = bitc::TYPE_CODE_INTEGER;
859       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
860       break;
861     case Type::PointerTyID: {
862       PointerType *PTy = cast<PointerType>(T);
863       // POINTER: [pointee type, address space]
864       Code = bitc::TYPE_CODE_POINTER;
865       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
866       unsigned AddressSpace = PTy->getAddressSpace();
867       TypeVals.push_back(AddressSpace);
868       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
869       break;
870     }
871     case Type::FunctionTyID: {
872       FunctionType *FT = cast<FunctionType>(T);
873       // FUNCTION: [isvararg, retty, paramty x N]
874       Code = bitc::TYPE_CODE_FUNCTION;
875       TypeVals.push_back(FT->isVarArg());
876       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
877       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
878         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
879       AbbrevToUse = FunctionAbbrev;
880       break;
881     }
882     case Type::StructTyID: {
883       StructType *ST = cast<StructType>(T);
884       // STRUCT: [ispacked, eltty x N]
885       TypeVals.push_back(ST->isPacked());
886       // Output all of the element types.
887       for (StructType::element_iterator I = ST->element_begin(),
888            E = ST->element_end(); I != E; ++I)
889         TypeVals.push_back(VE.getTypeID(*I));
890 
891       if (ST->isLiteral()) {
892         Code = bitc::TYPE_CODE_STRUCT_ANON;
893         AbbrevToUse = StructAnonAbbrev;
894       } else {
895         if (ST->isOpaque()) {
896           Code = bitc::TYPE_CODE_OPAQUE;
897         } else {
898           Code = bitc::TYPE_CODE_STRUCT_NAMED;
899           AbbrevToUse = StructNamedAbbrev;
900         }
901 
902         // Emit the name if it is present.
903         if (!ST->getName().empty())
904           writeStringRecord(Stream, bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
905                             StructNameAbbrev);
906       }
907       break;
908     }
909     case Type::ArrayTyID: {
910       ArrayType *AT = cast<ArrayType>(T);
911       // ARRAY: [numelts, eltty]
912       Code = bitc::TYPE_CODE_ARRAY;
913       TypeVals.push_back(AT->getNumElements());
914       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
915       AbbrevToUse = ArrayAbbrev;
916       break;
917     }
918     case Type::VectorTyID: {
919       VectorType *VT = cast<VectorType>(T);
920       // VECTOR [numelts, eltty]
921       Code = bitc::TYPE_CODE_VECTOR;
922       TypeVals.push_back(VT->getNumElements());
923       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
924       break;
925     }
926     }
927 
928     // Emit the finished record.
929     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
930     TypeVals.clear();
931   }
932 
933   Stream.ExitBlock();
934 }
935 
936 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
937   switch (Linkage) {
938   case GlobalValue::ExternalLinkage:
939     return 0;
940   case GlobalValue::WeakAnyLinkage:
941     return 16;
942   case GlobalValue::AppendingLinkage:
943     return 2;
944   case GlobalValue::InternalLinkage:
945     return 3;
946   case GlobalValue::LinkOnceAnyLinkage:
947     return 18;
948   case GlobalValue::ExternalWeakLinkage:
949     return 7;
950   case GlobalValue::CommonLinkage:
951     return 8;
952   case GlobalValue::PrivateLinkage:
953     return 9;
954   case GlobalValue::WeakODRLinkage:
955     return 17;
956   case GlobalValue::LinkOnceODRLinkage:
957     return 19;
958   case GlobalValue::AvailableExternallyLinkage:
959     return 12;
960   }
961   llvm_unreachable("Invalid linkage");
962 }
963 
964 static unsigned getEncodedLinkage(const GlobalValue &GV) {
965   return getEncodedLinkage(GV.getLinkage());
966 }
967 
968 static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
969   uint64_t RawFlags = 0;
970   RawFlags |= Flags.ReadNone;
971   RawFlags |= (Flags.ReadOnly << 1);
972   RawFlags |= (Flags.NoRecurse << 2);
973   RawFlags |= (Flags.ReturnDoesNotAlias << 3);
974   return RawFlags;
975 }
976 
977 // Decode the flags for GlobalValue in the summary
978 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
979   uint64_t RawFlags = 0;
980 
981   RawFlags |= Flags.NotEligibleToImport; // bool
982   RawFlags |= (Flags.Live << 1);
983   RawFlags |= (Flags.DSOLocal << 2);
984 
985   // Linkage don't need to be remapped at that time for the summary. Any future
986   // change to the getEncodedLinkage() function will need to be taken into
987   // account here as well.
988   RawFlags = (RawFlags << 4) | Flags.Linkage; // 4 bits
989 
990   return RawFlags;
991 }
992 
993 static unsigned getEncodedVisibility(const GlobalValue &GV) {
994   switch (GV.getVisibility()) {
995   case GlobalValue::DefaultVisibility:   return 0;
996   case GlobalValue::HiddenVisibility:    return 1;
997   case GlobalValue::ProtectedVisibility: return 2;
998   }
999   llvm_unreachable("Invalid visibility");
1000 }
1001 
1002 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
1003   switch (GV.getDLLStorageClass()) {
1004   case GlobalValue::DefaultStorageClass:   return 0;
1005   case GlobalValue::DLLImportStorageClass: return 1;
1006   case GlobalValue::DLLExportStorageClass: return 2;
1007   }
1008   llvm_unreachable("Invalid DLL storage class");
1009 }
1010 
1011 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
1012   switch (GV.getThreadLocalMode()) {
1013     case GlobalVariable::NotThreadLocal:         return 0;
1014     case GlobalVariable::GeneralDynamicTLSModel: return 1;
1015     case GlobalVariable::LocalDynamicTLSModel:   return 2;
1016     case GlobalVariable::InitialExecTLSModel:    return 3;
1017     case GlobalVariable::LocalExecTLSModel:      return 4;
1018   }
1019   llvm_unreachable("Invalid TLS model");
1020 }
1021 
1022 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
1023   switch (C.getSelectionKind()) {
1024   case Comdat::Any:
1025     return bitc::COMDAT_SELECTION_KIND_ANY;
1026   case Comdat::ExactMatch:
1027     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
1028   case Comdat::Largest:
1029     return bitc::COMDAT_SELECTION_KIND_LARGEST;
1030   case Comdat::NoDuplicates:
1031     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
1032   case Comdat::SameSize:
1033     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
1034   }
1035   llvm_unreachable("Invalid selection kind");
1036 }
1037 
1038 static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
1039   switch (GV.getUnnamedAddr()) {
1040   case GlobalValue::UnnamedAddr::None:   return 0;
1041   case GlobalValue::UnnamedAddr::Local:  return 2;
1042   case GlobalValue::UnnamedAddr::Global: return 1;
1043   }
1044   llvm_unreachable("Invalid unnamed_addr");
1045 }
1046 
1047 size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
1048   if (GenerateHash)
1049     Hasher.update(Str);
1050   return StrtabBuilder.add(Str);
1051 }
1052 
1053 void ModuleBitcodeWriter::writeComdats() {
1054   SmallVector<unsigned, 64> Vals;
1055   for (const Comdat *C : VE.getComdats()) {
1056     // COMDAT: [strtab offset, strtab size, selection_kind]
1057     Vals.push_back(addToStrtab(C->getName()));
1058     Vals.push_back(C->getName().size());
1059     Vals.push_back(getEncodedComdatSelectionKind(*C));
1060     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
1061     Vals.clear();
1062   }
1063 }
1064 
1065 /// Write a record that will eventually hold the word offset of the
1066 /// module-level VST. For now the offset is 0, which will be backpatched
1067 /// after the real VST is written. Saves the bit offset to backpatch.
1068 void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
1069   // Write a placeholder value in for the offset of the real VST,
1070   // which is written after the function blocks so that it can include
1071   // the offset of each function. The placeholder offset will be
1072   // updated when the real VST is written.
1073   auto Abbv = std::make_shared<BitCodeAbbrev>();
1074   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
1075   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
1076   // hold the real VST offset. Must use fixed instead of VBR as we don't
1077   // know how many VBR chunks to reserve ahead of time.
1078   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1079   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1080 
1081   // Emit the placeholder
1082   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
1083   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
1084 
1085   // Compute and save the bit offset to the placeholder, which will be
1086   // patched when the real VST is written. We can simply subtract the 32-bit
1087   // fixed size from the current bit number to get the location to backpatch.
1088   VSTOffsetPlaceholder = Stream.GetCurrentBitNo() - 32;
1089 }
1090 
1091 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
1092 
1093 /// Determine the encoding to use for the given string name and length.
1094 static StringEncoding getStringEncoding(StringRef Str) {
1095   bool isChar6 = true;
1096   for (char C : Str) {
1097     if (isChar6)
1098       isChar6 = BitCodeAbbrevOp::isChar6(C);
1099     if ((unsigned char)C & 128)
1100       // don't bother scanning the rest.
1101       return SE_Fixed8;
1102   }
1103   if (isChar6)
1104     return SE_Char6;
1105   return SE_Fixed7;
1106 }
1107 
1108 /// Emit top-level description of module, including target triple, inline asm,
1109 /// descriptors for global variables, and function prototype info.
1110 /// Returns the bit offset to backpatch with the location of the real VST.
1111 void ModuleBitcodeWriter::writeModuleInfo() {
1112   // Emit various pieces of data attached to a module.
1113   if (!M.getTargetTriple().empty())
1114     writeStringRecord(Stream, bitc::MODULE_CODE_TRIPLE, M.getTargetTriple(),
1115                       0 /*TODO*/);
1116   const std::string &DL = M.getDataLayoutStr();
1117   if (!DL.empty())
1118     writeStringRecord(Stream, bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/);
1119   if (!M.getModuleInlineAsm().empty())
1120     writeStringRecord(Stream, bitc::MODULE_CODE_ASM, M.getModuleInlineAsm(),
1121                       0 /*TODO*/);
1122 
1123   // Emit information about sections and GC, computing how many there are. Also
1124   // compute the maximum alignment value.
1125   std::map<std::string, unsigned> SectionMap;
1126   std::map<std::string, unsigned> GCMap;
1127   unsigned MaxAlignment = 0;
1128   unsigned MaxGlobalType = 0;
1129   for (const GlobalValue &GV : M.globals()) {
1130     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
1131     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
1132     if (GV.hasSection()) {
1133       // Give section names unique ID's.
1134       unsigned &Entry = SectionMap[GV.getSection()];
1135       if (!Entry) {
1136         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
1137                           0 /*TODO*/);
1138         Entry = SectionMap.size();
1139       }
1140     }
1141   }
1142   for (const Function &F : M) {
1143     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
1144     if (F.hasSection()) {
1145       // Give section names unique ID's.
1146       unsigned &Entry = SectionMap[F.getSection()];
1147       if (!Entry) {
1148         writeStringRecord(Stream, bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
1149                           0 /*TODO*/);
1150         Entry = SectionMap.size();
1151       }
1152     }
1153     if (F.hasGC()) {
1154       // Same for GC names.
1155       unsigned &Entry = GCMap[F.getGC()];
1156       if (!Entry) {
1157         writeStringRecord(Stream, bitc::MODULE_CODE_GCNAME, F.getGC(),
1158                           0 /*TODO*/);
1159         Entry = GCMap.size();
1160       }
1161     }
1162   }
1163 
1164   // Emit abbrev for globals, now that we know # sections and max alignment.
1165   unsigned SimpleGVarAbbrev = 0;
1166   if (!M.global_empty()) {
1167     // Add an abbrev for common globals with no visibility or thread localness.
1168     auto Abbv = std::make_shared<BitCodeAbbrev>();
1169     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
1170     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1171     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1172     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1173                               Log2_32_Ceil(MaxGlobalType+1)));
1174     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
1175                                                            //| explicitType << 1
1176                                                            //| constant
1177     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
1178     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
1179     if (MaxAlignment == 0)                                 // Alignment.
1180       Abbv->Add(BitCodeAbbrevOp(0));
1181     else {
1182       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
1183       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1184                                Log2_32_Ceil(MaxEncAlignment+1)));
1185     }
1186     if (SectionMap.empty())                                    // Section.
1187       Abbv->Add(BitCodeAbbrevOp(0));
1188     else
1189       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
1190                                Log2_32_Ceil(SectionMap.size()+1)));
1191     // Don't bother emitting vis + thread local.
1192     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1193   }
1194 
1195   SmallVector<unsigned, 64> Vals;
1196   // Emit the module's source file name.
1197   {
1198     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
1199     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
1200     if (Bits == SE_Char6)
1201       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
1202     else if (Bits == SE_Fixed7)
1203       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
1204 
1205     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
1206     auto Abbv = std::make_shared<BitCodeAbbrev>();
1207     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
1208     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1209     Abbv->Add(AbbrevOpToUse);
1210     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1211 
1212     for (const auto P : M.getSourceFileName())
1213       Vals.push_back((unsigned char)P);
1214 
1215     // Emit the finished record.
1216     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
1217     Vals.clear();
1218   }
1219 
1220   // Emit the global variable information.
1221   for (const GlobalVariable &GV : M.globals()) {
1222     unsigned AbbrevToUse = 0;
1223 
1224     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
1225     //             linkage, alignment, section, visibility, threadlocal,
1226     //             unnamed_addr, externally_initialized, dllstorageclass,
1227     //             comdat, attributes, DSO_Local]
1228     Vals.push_back(addToStrtab(GV.getName()));
1229     Vals.push_back(GV.getName().size());
1230     Vals.push_back(VE.getTypeID(GV.getValueType()));
1231     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
1232     Vals.push_back(GV.isDeclaration() ? 0 :
1233                    (VE.getValueID(GV.getInitializer()) + 1));
1234     Vals.push_back(getEncodedLinkage(GV));
1235     Vals.push_back(Log2_32(GV.getAlignment())+1);
1236     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
1237     if (GV.isThreadLocal() ||
1238         GV.getVisibility() != GlobalValue::DefaultVisibility ||
1239         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
1240         GV.isExternallyInitialized() ||
1241         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
1242         GV.hasComdat() ||
1243         GV.hasAttributes() ||
1244         GV.isDSOLocal()) {
1245       Vals.push_back(getEncodedVisibility(GV));
1246       Vals.push_back(getEncodedThreadLocalMode(GV));
1247       Vals.push_back(getEncodedUnnamedAddr(GV));
1248       Vals.push_back(GV.isExternallyInitialized());
1249       Vals.push_back(getEncodedDLLStorageClass(GV));
1250       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
1251 
1252       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
1253       Vals.push_back(VE.getAttributeListID(AL));
1254 
1255       Vals.push_back(GV.isDSOLocal());
1256     } else {
1257       AbbrevToUse = SimpleGVarAbbrev;
1258     }
1259 
1260     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
1261     Vals.clear();
1262   }
1263 
1264   // Emit the function proto information.
1265   for (const Function &F : M) {
1266     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
1267     //             linkage, paramattrs, alignment, section, visibility, gc,
1268     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
1269     //             prefixdata, personalityfn, DSO_Local, addrspace]
1270     Vals.push_back(addToStrtab(F.getName()));
1271     Vals.push_back(F.getName().size());
1272     Vals.push_back(VE.getTypeID(F.getFunctionType()));
1273     Vals.push_back(F.getCallingConv());
1274     Vals.push_back(F.isDeclaration());
1275     Vals.push_back(getEncodedLinkage(F));
1276     Vals.push_back(VE.getAttributeListID(F.getAttributes()));
1277     Vals.push_back(Log2_32(F.getAlignment())+1);
1278     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
1279     Vals.push_back(getEncodedVisibility(F));
1280     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
1281     Vals.push_back(getEncodedUnnamedAddr(F));
1282     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
1283                                        : 0);
1284     Vals.push_back(getEncodedDLLStorageClass(F));
1285     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
1286     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
1287                                      : 0);
1288     Vals.push_back(
1289         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
1290 
1291     Vals.push_back(F.isDSOLocal());
1292     Vals.push_back(F.getAddressSpace());
1293 
1294     unsigned AbbrevToUse = 0;
1295     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
1296     Vals.clear();
1297   }
1298 
1299   // Emit the alias information.
1300   for (const GlobalAlias &A : M.aliases()) {
1301     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
1302     //         visibility, dllstorageclass, threadlocal, unnamed_addr,
1303     //         DSO_Local]
1304     Vals.push_back(addToStrtab(A.getName()));
1305     Vals.push_back(A.getName().size());
1306     Vals.push_back(VE.getTypeID(A.getValueType()));
1307     Vals.push_back(A.getType()->getAddressSpace());
1308     Vals.push_back(VE.getValueID(A.getAliasee()));
1309     Vals.push_back(getEncodedLinkage(A));
1310     Vals.push_back(getEncodedVisibility(A));
1311     Vals.push_back(getEncodedDLLStorageClass(A));
1312     Vals.push_back(getEncodedThreadLocalMode(A));
1313     Vals.push_back(getEncodedUnnamedAddr(A));
1314     Vals.push_back(A.isDSOLocal());
1315 
1316     unsigned AbbrevToUse = 0;
1317     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
1318     Vals.clear();
1319   }
1320 
1321   // Emit the ifunc information.
1322   for (const GlobalIFunc &I : M.ifuncs()) {
1323     // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
1324     //         val#, linkage, visibility, DSO_Local]
1325     Vals.push_back(addToStrtab(I.getName()));
1326     Vals.push_back(I.getName().size());
1327     Vals.push_back(VE.getTypeID(I.getValueType()));
1328     Vals.push_back(I.getType()->getAddressSpace());
1329     Vals.push_back(VE.getValueID(I.getResolver()));
1330     Vals.push_back(getEncodedLinkage(I));
1331     Vals.push_back(getEncodedVisibility(I));
1332     Vals.push_back(I.isDSOLocal());
1333     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
1334     Vals.clear();
1335   }
1336 
1337   writeValueSymbolTableForwardDecl();
1338 }
1339 
1340 static uint64_t getOptimizationFlags(const Value *V) {
1341   uint64_t Flags = 0;
1342 
1343   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
1344     if (OBO->hasNoSignedWrap())
1345       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
1346     if (OBO->hasNoUnsignedWrap())
1347       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
1348   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
1349     if (PEO->isExact())
1350       Flags |= 1 << bitc::PEO_EXACT;
1351   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
1352     if (FPMO->hasAllowReassoc())
1353       Flags |= bitc::AllowReassoc;
1354     if (FPMO->hasNoNaNs())
1355       Flags |= bitc::NoNaNs;
1356     if (FPMO->hasNoInfs())
1357       Flags |= bitc::NoInfs;
1358     if (FPMO->hasNoSignedZeros())
1359       Flags |= bitc::NoSignedZeros;
1360     if (FPMO->hasAllowReciprocal())
1361       Flags |= bitc::AllowReciprocal;
1362     if (FPMO->hasAllowContract())
1363       Flags |= bitc::AllowContract;
1364     if (FPMO->hasApproxFunc())
1365       Flags |= bitc::ApproxFunc;
1366   }
1367 
1368   return Flags;
1369 }
1370 
1371 void ModuleBitcodeWriter::writeValueAsMetadata(
1372     const ValueAsMetadata *MD, SmallVectorImpl<uint64_t> &Record) {
1373   // Mimic an MDNode with a value as one operand.
1374   Value *V = MD->getValue();
1375   Record.push_back(VE.getTypeID(V->getType()));
1376   Record.push_back(VE.getValueID(V));
1377   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
1378   Record.clear();
1379 }
1380 
1381 void ModuleBitcodeWriter::writeMDTuple(const MDTuple *N,
1382                                        SmallVectorImpl<uint64_t> &Record,
1383                                        unsigned Abbrev) {
1384   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
1385     Metadata *MD = N->getOperand(i);
1386     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
1387            "Unexpected function-local metadata");
1388     Record.push_back(VE.getMetadataOrNullID(MD));
1389   }
1390   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
1391                                     : bitc::METADATA_NODE,
1392                     Record, Abbrev);
1393   Record.clear();
1394 }
1395 
1396 unsigned ModuleBitcodeWriter::createDILocationAbbrev() {
1397   // Assume the column is usually under 128, and always output the inlined-at
1398   // location (it's never more expensive than building an array size 1).
1399   auto Abbv = std::make_shared<BitCodeAbbrev>();
1400   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
1401   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1402   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1403   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
1404   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1405   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1406   return Stream.EmitAbbrev(std::move(Abbv));
1407 }
1408 
1409 void ModuleBitcodeWriter::writeDILocation(const DILocation *N,
1410                                           SmallVectorImpl<uint64_t> &Record,
1411                                           unsigned &Abbrev) {
1412   if (!Abbrev)
1413     Abbrev = createDILocationAbbrev();
1414 
1415   Record.push_back(N->isDistinct());
1416   Record.push_back(N->getLine());
1417   Record.push_back(N->getColumn());
1418   Record.push_back(VE.getMetadataID(N->getScope()));
1419   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
1420 
1421   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
1422   Record.clear();
1423 }
1424 
1425 unsigned ModuleBitcodeWriter::createGenericDINodeAbbrev() {
1426   // Assume the column is usually under 128, and always output the inlined-at
1427   // location (it's never more expensive than building an array size 1).
1428   auto Abbv = std::make_shared<BitCodeAbbrev>();
1429   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1430   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1431   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1432   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1433   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1434   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1435   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1436   return Stream.EmitAbbrev(std::move(Abbv));
1437 }
1438 
1439 void ModuleBitcodeWriter::writeGenericDINode(const GenericDINode *N,
1440                                              SmallVectorImpl<uint64_t> &Record,
1441                                              unsigned &Abbrev) {
1442   if (!Abbrev)
1443     Abbrev = createGenericDINodeAbbrev();
1444 
1445   Record.push_back(N->isDistinct());
1446   Record.push_back(N->getTag());
1447   Record.push_back(0); // Per-tag version field; unused for now.
1448 
1449   for (auto &I : N->operands())
1450     Record.push_back(VE.getMetadataOrNullID(I));
1451 
1452   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
1453   Record.clear();
1454 }
1455 
1456 static uint64_t rotateSign(int64_t I) {
1457   uint64_t U = I;
1458   return I < 0 ? ~(U << 1) : U << 1;
1459 }
1460 
1461 void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
1462                                           SmallVectorImpl<uint64_t> &Record,
1463                                           unsigned Abbrev) {
1464   const uint64_t Version = 1 << 1;
1465   Record.push_back((uint64_t)N->isDistinct() | Version);
1466   Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
1467   Record.push_back(rotateSign(N->getLowerBound()));
1468 
1469   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
1470   Record.clear();
1471 }
1472 
1473 void ModuleBitcodeWriter::writeDIEnumerator(const DIEnumerator *N,
1474                                             SmallVectorImpl<uint64_t> &Record,
1475                                             unsigned Abbrev) {
1476   Record.push_back((N->isUnsigned() << 1) | N->isDistinct());
1477   Record.push_back(rotateSign(N->getValue()));
1478   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1479 
1480   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
1481   Record.clear();
1482 }
1483 
1484 void ModuleBitcodeWriter::writeDIBasicType(const DIBasicType *N,
1485                                            SmallVectorImpl<uint64_t> &Record,
1486                                            unsigned Abbrev) {
1487   Record.push_back(N->isDistinct());
1488   Record.push_back(N->getTag());
1489   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1490   Record.push_back(N->getSizeInBits());
1491   Record.push_back(N->getAlignInBits());
1492   Record.push_back(N->getEncoding());
1493   Record.push_back(N->getFlags());
1494 
1495   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
1496   Record.clear();
1497 }
1498 
1499 void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
1500                                              SmallVectorImpl<uint64_t> &Record,
1501                                              unsigned Abbrev) {
1502   Record.push_back(N->isDistinct());
1503   Record.push_back(N->getTag());
1504   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1505   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1506   Record.push_back(N->getLine());
1507   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1508   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1509   Record.push_back(N->getSizeInBits());
1510   Record.push_back(N->getAlignInBits());
1511   Record.push_back(N->getOffsetInBits());
1512   Record.push_back(N->getFlags());
1513   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1514 
1515   // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
1516   // that there is no DWARF address space associated with DIDerivedType.
1517   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
1518     Record.push_back(*DWARFAddressSpace + 1);
1519   else
1520     Record.push_back(0);
1521 
1522   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1523   Record.clear();
1524 }
1525 
1526 void ModuleBitcodeWriter::writeDICompositeType(
1527     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
1528     unsigned Abbrev) {
1529   const unsigned IsNotUsedInOldTypeRef = 0x2;
1530   Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
1531   Record.push_back(N->getTag());
1532   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1533   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1534   Record.push_back(N->getLine());
1535   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1536   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1537   Record.push_back(N->getSizeInBits());
1538   Record.push_back(N->getAlignInBits());
1539   Record.push_back(N->getOffsetInBits());
1540   Record.push_back(N->getFlags());
1541   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1542   Record.push_back(N->getRuntimeLang());
1543   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1544   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1545   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1546   Record.push_back(VE.getMetadataOrNullID(N->getDiscriminator()));
1547 
1548   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1549   Record.clear();
1550 }
1551 
1552 void ModuleBitcodeWriter::writeDISubroutineType(
1553     const DISubroutineType *N, SmallVectorImpl<uint64_t> &Record,
1554     unsigned Abbrev) {
1555   const unsigned HasNoOldTypeRefs = 0x2;
1556   Record.push_back(HasNoOldTypeRefs | (unsigned)N->isDistinct());
1557   Record.push_back(N->getFlags());
1558   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1559   Record.push_back(N->getCC());
1560 
1561   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1562   Record.clear();
1563 }
1564 
1565 void ModuleBitcodeWriter::writeDIFile(const DIFile *N,
1566                                       SmallVectorImpl<uint64_t> &Record,
1567                                       unsigned Abbrev) {
1568   Record.push_back(N->isDistinct());
1569   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1570   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1571   if (N->getRawChecksum()) {
1572     Record.push_back(N->getRawChecksum()->Kind);
1573     Record.push_back(VE.getMetadataOrNullID(N->getRawChecksum()->Value));
1574   } else {
1575     // Maintain backwards compatibility with the old internal representation of
1576     // CSK_None in ChecksumKind by writing nulls here when Checksum is None.
1577     Record.push_back(0);
1578     Record.push_back(VE.getMetadataOrNullID(nullptr));
1579   }
1580   auto Source = N->getRawSource();
1581   if (Source)
1582     Record.push_back(VE.getMetadataOrNullID(*Source));
1583 
1584   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1585   Record.clear();
1586 }
1587 
1588 void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
1589                                              SmallVectorImpl<uint64_t> &Record,
1590                                              unsigned Abbrev) {
1591   assert(N->isDistinct() && "Expected distinct compile units");
1592   Record.push_back(/* IsDistinct */ true);
1593   Record.push_back(N->getSourceLanguage());
1594   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1595   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1596   Record.push_back(N->isOptimized());
1597   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1598   Record.push_back(N->getRuntimeVersion());
1599   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1600   Record.push_back(N->getEmissionKind());
1601   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1602   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1603   Record.push_back(/* subprograms */ 0);
1604   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1605   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1606   Record.push_back(N->getDWOId());
1607   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1608   Record.push_back(N->getSplitDebugInlining());
1609   Record.push_back(N->getDebugInfoForProfiling());
1610   Record.push_back((unsigned)N->getNameTableKind());
1611 
1612   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1613   Record.clear();
1614 }
1615 
1616 void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
1617                                             SmallVectorImpl<uint64_t> &Record,
1618                                             unsigned Abbrev) {
1619   uint64_t HasUnitFlag = 1 << 1;
1620   Record.push_back(N->isDistinct() | HasUnitFlag);
1621   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1622   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1623   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1624   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1625   Record.push_back(N->getLine());
1626   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1627   Record.push_back(N->isLocalToUnit());
1628   Record.push_back(N->isDefinition());
1629   Record.push_back(N->getScopeLine());
1630   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1631   Record.push_back(N->getVirtuality());
1632   Record.push_back(N->getVirtualIndex());
1633   Record.push_back(N->getFlags());
1634   Record.push_back(N->isOptimized());
1635   Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
1636   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1637   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1638   Record.push_back(VE.getMetadataOrNullID(N->getRetainedNodes().get()));
1639   Record.push_back(N->getThisAdjustment());
1640   Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
1641 
1642   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1643   Record.clear();
1644 }
1645 
1646 void ModuleBitcodeWriter::writeDILexicalBlock(const DILexicalBlock *N,
1647                                               SmallVectorImpl<uint64_t> &Record,
1648                                               unsigned Abbrev) {
1649   Record.push_back(N->isDistinct());
1650   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1651   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1652   Record.push_back(N->getLine());
1653   Record.push_back(N->getColumn());
1654 
1655   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1656   Record.clear();
1657 }
1658 
1659 void ModuleBitcodeWriter::writeDILexicalBlockFile(
1660     const DILexicalBlockFile *N, SmallVectorImpl<uint64_t> &Record,
1661     unsigned Abbrev) {
1662   Record.push_back(N->isDistinct());
1663   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1664   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1665   Record.push_back(N->getDiscriminator());
1666 
1667   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1668   Record.clear();
1669 }
1670 
1671 void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
1672                                            SmallVectorImpl<uint64_t> &Record,
1673                                            unsigned Abbrev) {
1674   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
1675   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1676   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1677 
1678   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1679   Record.clear();
1680 }
1681 
1682 void ModuleBitcodeWriter::writeDIMacro(const DIMacro *N,
1683                                        SmallVectorImpl<uint64_t> &Record,
1684                                        unsigned Abbrev) {
1685   Record.push_back(N->isDistinct());
1686   Record.push_back(N->getMacinfoType());
1687   Record.push_back(N->getLine());
1688   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1689   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1690 
1691   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1692   Record.clear();
1693 }
1694 
1695 void ModuleBitcodeWriter::writeDIMacroFile(const DIMacroFile *N,
1696                                            SmallVectorImpl<uint64_t> &Record,
1697                                            unsigned Abbrev) {
1698   Record.push_back(N->isDistinct());
1699   Record.push_back(N->getMacinfoType());
1700   Record.push_back(N->getLine());
1701   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1702   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1703 
1704   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1705   Record.clear();
1706 }
1707 
1708 void ModuleBitcodeWriter::writeDIModule(const DIModule *N,
1709                                         SmallVectorImpl<uint64_t> &Record,
1710                                         unsigned Abbrev) {
1711   Record.push_back(N->isDistinct());
1712   for (auto &I : N->operands())
1713     Record.push_back(VE.getMetadataOrNullID(I));
1714 
1715   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1716   Record.clear();
1717 }
1718 
1719 void ModuleBitcodeWriter::writeDITemplateTypeParameter(
1720     const DITemplateTypeParameter *N, SmallVectorImpl<uint64_t> &Record,
1721     unsigned Abbrev) {
1722   Record.push_back(N->isDistinct());
1723   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1724   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1725 
1726   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1727   Record.clear();
1728 }
1729 
1730 void ModuleBitcodeWriter::writeDITemplateValueParameter(
1731     const DITemplateValueParameter *N, SmallVectorImpl<uint64_t> &Record,
1732     unsigned Abbrev) {
1733   Record.push_back(N->isDistinct());
1734   Record.push_back(N->getTag());
1735   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1736   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1737   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1738 
1739   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1740   Record.clear();
1741 }
1742 
1743 void ModuleBitcodeWriter::writeDIGlobalVariable(
1744     const DIGlobalVariable *N, SmallVectorImpl<uint64_t> &Record,
1745     unsigned Abbrev) {
1746   const uint64_t Version = 1 << 1;
1747   Record.push_back((uint64_t)N->isDistinct() | Version);
1748   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1749   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1750   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1751   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1752   Record.push_back(N->getLine());
1753   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1754   Record.push_back(N->isLocalToUnit());
1755   Record.push_back(N->isDefinition());
1756   Record.push_back(/* expr */ 0);
1757   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1758   Record.push_back(N->getAlignInBits());
1759 
1760   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1761   Record.clear();
1762 }
1763 
1764 void ModuleBitcodeWriter::writeDILocalVariable(
1765     const DILocalVariable *N, SmallVectorImpl<uint64_t> &Record,
1766     unsigned Abbrev) {
1767   // In order to support all possible bitcode formats in BitcodeReader we need
1768   // to distinguish the following cases:
1769   // 1) Record has no artificial tag (Record[1]),
1770   //   has no obsolete inlinedAt field (Record[9]).
1771   //   In this case Record size will be 8, HasAlignment flag is false.
1772   // 2) Record has artificial tag (Record[1]),
1773   //   has no obsolete inlignedAt field (Record[9]).
1774   //   In this case Record size will be 9, HasAlignment flag is false.
1775   // 3) Record has both artificial tag (Record[1]) and
1776   //   obsolete inlignedAt field (Record[9]).
1777   //   In this case Record size will be 10, HasAlignment flag is false.
1778   // 4) Record has neither artificial tag, nor inlignedAt field, but
1779   //   HasAlignment flag is true and Record[8] contains alignment value.
1780   const uint64_t HasAlignmentFlag = 1 << 1;
1781   Record.push_back((uint64_t)N->isDistinct() | HasAlignmentFlag);
1782   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1783   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1784   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1785   Record.push_back(N->getLine());
1786   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1787   Record.push_back(N->getArg());
1788   Record.push_back(N->getFlags());
1789   Record.push_back(N->getAlignInBits());
1790 
1791   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1792   Record.clear();
1793 }
1794 
1795 void ModuleBitcodeWriter::writeDILabel(
1796     const DILabel *N, SmallVectorImpl<uint64_t> &Record,
1797     unsigned Abbrev) {
1798   Record.push_back((uint64_t)N->isDistinct());
1799   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1800   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1801   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1802   Record.push_back(N->getLine());
1803 
1804   Stream.EmitRecord(bitc::METADATA_LABEL, Record, Abbrev);
1805   Record.clear();
1806 }
1807 
1808 void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
1809                                             SmallVectorImpl<uint64_t> &Record,
1810                                             unsigned Abbrev) {
1811   Record.reserve(N->getElements().size() + 1);
1812   const uint64_t Version = 3 << 1;
1813   Record.push_back((uint64_t)N->isDistinct() | Version);
1814   Record.append(N->elements_begin(), N->elements_end());
1815 
1816   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1817   Record.clear();
1818 }
1819 
1820 void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
1821     const DIGlobalVariableExpression *N, SmallVectorImpl<uint64_t> &Record,
1822     unsigned Abbrev) {
1823   Record.push_back(N->isDistinct());
1824   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
1825   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
1826 
1827   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
1828   Record.clear();
1829 }
1830 
1831 void ModuleBitcodeWriter::writeDIObjCProperty(const DIObjCProperty *N,
1832                                               SmallVectorImpl<uint64_t> &Record,
1833                                               unsigned Abbrev) {
1834   Record.push_back(N->isDistinct());
1835   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1836   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1837   Record.push_back(N->getLine());
1838   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1839   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1840   Record.push_back(N->getAttributes());
1841   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1842 
1843   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1844   Record.clear();
1845 }
1846 
1847 void ModuleBitcodeWriter::writeDIImportedEntity(
1848     const DIImportedEntity *N, SmallVectorImpl<uint64_t> &Record,
1849     unsigned Abbrev) {
1850   Record.push_back(N->isDistinct());
1851   Record.push_back(N->getTag());
1852   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1853   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1854   Record.push_back(N->getLine());
1855   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1856   Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
1857 
1858   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1859   Record.clear();
1860 }
1861 
1862 unsigned ModuleBitcodeWriter::createNamedMetadataAbbrev() {
1863   auto Abbv = std::make_shared<BitCodeAbbrev>();
1864   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1865   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1866   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1867   return Stream.EmitAbbrev(std::move(Abbv));
1868 }
1869 
1870 void ModuleBitcodeWriter::writeNamedMetadata(
1871     SmallVectorImpl<uint64_t> &Record) {
1872   if (M.named_metadata_empty())
1873     return;
1874 
1875   unsigned Abbrev = createNamedMetadataAbbrev();
1876   for (const NamedMDNode &NMD : M.named_metadata()) {
1877     // Write name.
1878     StringRef Str = NMD.getName();
1879     Record.append(Str.bytes_begin(), Str.bytes_end());
1880     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1881     Record.clear();
1882 
1883     // Write named metadata operands.
1884     for (const MDNode *N : NMD.operands())
1885       Record.push_back(VE.getMetadataID(N));
1886     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1887     Record.clear();
1888   }
1889 }
1890 
1891 unsigned ModuleBitcodeWriter::createMetadataStringsAbbrev() {
1892   auto Abbv = std::make_shared<BitCodeAbbrev>();
1893   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1894   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1895   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1896   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1897   return Stream.EmitAbbrev(std::move(Abbv));
1898 }
1899 
1900 /// Write out a record for MDString.
1901 ///
1902 /// All the metadata strings in a metadata block are emitted in a single
1903 /// record.  The sizes and strings themselves are shoved into a blob.
1904 void ModuleBitcodeWriter::writeMetadataStrings(
1905     ArrayRef<const Metadata *> Strings, SmallVectorImpl<uint64_t> &Record) {
1906   if (Strings.empty())
1907     return;
1908 
1909   // Start the record with the number of strings.
1910   Record.push_back(bitc::METADATA_STRINGS);
1911   Record.push_back(Strings.size());
1912 
1913   // Emit the sizes of the strings in the blob.
1914   SmallString<256> Blob;
1915   {
1916     BitstreamWriter W(Blob);
1917     for (const Metadata *MD : Strings)
1918       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1919     W.FlushToWord();
1920   }
1921 
1922   // Add the offset to the strings to the record.
1923   Record.push_back(Blob.size());
1924 
1925   // Add the strings to the blob.
1926   for (const Metadata *MD : Strings)
1927     Blob.append(cast<MDString>(MD)->getString());
1928 
1929   // Emit the final record.
1930   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(), Record, Blob);
1931   Record.clear();
1932 }
1933 
1934 // Generates an enum to use as an index in the Abbrev array of Metadata record.
1935 enum MetadataAbbrev : unsigned {
1936 #define HANDLE_MDNODE_LEAF(CLASS) CLASS##AbbrevID,
1937 #include "llvm/IR/Metadata.def"
1938   LastPlusOne
1939 };
1940 
1941 void ModuleBitcodeWriter::writeMetadataRecords(
1942     ArrayRef<const Metadata *> MDs, SmallVectorImpl<uint64_t> &Record,
1943     std::vector<unsigned> *MDAbbrevs, std::vector<uint64_t> *IndexPos) {
1944   if (MDs.empty())
1945     return;
1946 
1947   // Initialize MDNode abbreviations.
1948 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1949 #include "llvm/IR/Metadata.def"
1950 
1951   for (const Metadata *MD : MDs) {
1952     if (IndexPos)
1953       IndexPos->push_back(Stream.GetCurrentBitNo());
1954     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1955       assert(N->isResolved() && "Expected forward references to be resolved");
1956 
1957       switch (N->getMetadataID()) {
1958       default:
1959         llvm_unreachable("Invalid MDNode subclass");
1960 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1961   case Metadata::CLASS##Kind:                                                  \
1962     if (MDAbbrevs)                                                             \
1963       write##CLASS(cast<CLASS>(N), Record,                                     \
1964                    (*MDAbbrevs)[MetadataAbbrev::CLASS##AbbrevID]);             \
1965     else                                                                       \
1966       write##CLASS(cast<CLASS>(N), Record, CLASS##Abbrev);                     \
1967     continue;
1968 #include "llvm/IR/Metadata.def"
1969       }
1970     }
1971     writeValueAsMetadata(cast<ValueAsMetadata>(MD), Record);
1972   }
1973 }
1974 
1975 void ModuleBitcodeWriter::writeModuleMetadata() {
1976   if (!VE.hasMDs() && M.named_metadata_empty())
1977     return;
1978 
1979   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 4);
1980   SmallVector<uint64_t, 64> Record;
1981 
1982   // Emit all abbrevs upfront, so that the reader can jump in the middle of the
1983   // block and load any metadata.
1984   std::vector<unsigned> MDAbbrevs;
1985 
1986   MDAbbrevs.resize(MetadataAbbrev::LastPlusOne);
1987   MDAbbrevs[MetadataAbbrev::DILocationAbbrevID] = createDILocationAbbrev();
1988   MDAbbrevs[MetadataAbbrev::GenericDINodeAbbrevID] =
1989       createGenericDINodeAbbrev();
1990 
1991   auto Abbv = std::make_shared<BitCodeAbbrev>();
1992   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX_OFFSET));
1993   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1994   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
1995   unsigned OffsetAbbrev = Stream.EmitAbbrev(std::move(Abbv));
1996 
1997   Abbv = std::make_shared<BitCodeAbbrev>();
1998   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_INDEX));
1999   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2000   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2001   unsigned IndexAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2002 
2003   // Emit MDStrings together upfront.
2004   writeMetadataStrings(VE.getMDStrings(), Record);
2005 
2006   // We only emit an index for the metadata record if we have more than a given
2007   // (naive) threshold of metadatas, otherwise it is not worth it.
2008   if (VE.getNonMDStrings().size() > IndexThreshold) {
2009     // Write a placeholder value in for the offset of the metadata index,
2010     // which is written after the records, so that it can include
2011     // the offset of each entry. The placeholder offset will be
2012     // updated after all records are emitted.
2013     uint64_t Vals[] = {0, 0};
2014     Stream.EmitRecord(bitc::METADATA_INDEX_OFFSET, Vals, OffsetAbbrev);
2015   }
2016 
2017   // Compute and save the bit offset to the current position, which will be
2018   // patched when we emit the index later. We can simply subtract the 64-bit
2019   // fixed size from the current bit number to get the location to backpatch.
2020   uint64_t IndexOffsetRecordBitPos = Stream.GetCurrentBitNo();
2021 
2022   // This index will contain the bitpos for each individual record.
2023   std::vector<uint64_t> IndexPos;
2024   IndexPos.reserve(VE.getNonMDStrings().size());
2025 
2026   // Write all the records
2027   writeMetadataRecords(VE.getNonMDStrings(), Record, &MDAbbrevs, &IndexPos);
2028 
2029   if (VE.getNonMDStrings().size() > IndexThreshold) {
2030     // Now that we have emitted all the records we will emit the index. But
2031     // first
2032     // backpatch the forward reference so that the reader can skip the records
2033     // efficiently.
2034     Stream.BackpatchWord64(IndexOffsetRecordBitPos - 64,
2035                            Stream.GetCurrentBitNo() - IndexOffsetRecordBitPos);
2036 
2037     // Delta encode the index.
2038     uint64_t PreviousValue = IndexOffsetRecordBitPos;
2039     for (auto &Elt : IndexPos) {
2040       auto EltDelta = Elt - PreviousValue;
2041       PreviousValue = Elt;
2042       Elt = EltDelta;
2043     }
2044     // Emit the index record.
2045     Stream.EmitRecord(bitc::METADATA_INDEX, IndexPos, IndexAbbrev);
2046     IndexPos.clear();
2047   }
2048 
2049   // Write the named metadata now.
2050   writeNamedMetadata(Record);
2051 
2052   auto AddDeclAttachedMetadata = [&](const GlobalObject &GO) {
2053     SmallVector<uint64_t, 4> Record;
2054     Record.push_back(VE.getValueID(&GO));
2055     pushGlobalMetadataAttachment(Record, GO);
2056     Stream.EmitRecord(bitc::METADATA_GLOBAL_DECL_ATTACHMENT, Record);
2057   };
2058   for (const Function &F : M)
2059     if (F.isDeclaration() && F.hasMetadata())
2060       AddDeclAttachedMetadata(F);
2061   // FIXME: Only store metadata for declarations here, and move data for global
2062   // variable definitions to a separate block (PR28134).
2063   for (const GlobalVariable &GV : M.globals())
2064     if (GV.hasMetadata())
2065       AddDeclAttachedMetadata(GV);
2066 
2067   Stream.ExitBlock();
2068 }
2069 
2070 void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
2071   if (!VE.hasMDs())
2072     return;
2073 
2074   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
2075   SmallVector<uint64_t, 64> Record;
2076   writeMetadataStrings(VE.getMDStrings(), Record);
2077   writeMetadataRecords(VE.getNonMDStrings(), Record);
2078   Stream.ExitBlock();
2079 }
2080 
2081 void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
2082     SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
2083   // [n x [id, mdnode]]
2084   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2085   GO.getAllMetadata(MDs);
2086   for (const auto &I : MDs) {
2087     Record.push_back(I.first);
2088     Record.push_back(VE.getMetadataID(I.second));
2089   }
2090 }
2091 
2092 void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
2093   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
2094 
2095   SmallVector<uint64_t, 64> Record;
2096 
2097   if (F.hasMetadata()) {
2098     pushGlobalMetadataAttachment(Record, F);
2099     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2100     Record.clear();
2101   }
2102 
2103   // Write metadata attachments
2104   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
2105   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
2106   for (const BasicBlock &BB : F)
2107     for (const Instruction &I : BB) {
2108       MDs.clear();
2109       I.getAllMetadataOtherThanDebugLoc(MDs);
2110 
2111       // If no metadata, ignore instruction.
2112       if (MDs.empty()) continue;
2113 
2114       Record.push_back(VE.getInstructionID(&I));
2115 
2116       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
2117         Record.push_back(MDs[i].first);
2118         Record.push_back(VE.getMetadataID(MDs[i].second));
2119       }
2120       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
2121       Record.clear();
2122     }
2123 
2124   Stream.ExitBlock();
2125 }
2126 
2127 void ModuleBitcodeWriter::writeModuleMetadataKinds() {
2128   SmallVector<uint64_t, 64> Record;
2129 
2130   // Write metadata kinds
2131   // METADATA_KIND - [n x [id, name]]
2132   SmallVector<StringRef, 8> Names;
2133   M.getMDKindNames(Names);
2134 
2135   if (Names.empty()) return;
2136 
2137   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
2138 
2139   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
2140     Record.push_back(MDKindID);
2141     StringRef KName = Names[MDKindID];
2142     Record.append(KName.begin(), KName.end());
2143 
2144     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
2145     Record.clear();
2146   }
2147 
2148   Stream.ExitBlock();
2149 }
2150 
2151 void ModuleBitcodeWriter::writeOperandBundleTags() {
2152   // Write metadata kinds
2153   //
2154   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
2155   //
2156   // OPERAND_BUNDLE_TAG - [strchr x N]
2157 
2158   SmallVector<StringRef, 8> Tags;
2159   M.getOperandBundleTags(Tags);
2160 
2161   if (Tags.empty())
2162     return;
2163 
2164   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
2165 
2166   SmallVector<uint64_t, 64> Record;
2167 
2168   for (auto Tag : Tags) {
2169     Record.append(Tag.begin(), Tag.end());
2170 
2171     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
2172     Record.clear();
2173   }
2174 
2175   Stream.ExitBlock();
2176 }
2177 
2178 void ModuleBitcodeWriter::writeSyncScopeNames() {
2179   SmallVector<StringRef, 8> SSNs;
2180   M.getContext().getSyncScopeNames(SSNs);
2181   if (SSNs.empty())
2182     return;
2183 
2184   Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
2185 
2186   SmallVector<uint64_t, 64> Record;
2187   for (auto SSN : SSNs) {
2188     Record.append(SSN.begin(), SSN.end());
2189     Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
2190     Record.clear();
2191   }
2192 
2193   Stream.ExitBlock();
2194 }
2195 
2196 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
2197   if ((int64_t)V >= 0)
2198     Vals.push_back(V << 1);
2199   else
2200     Vals.push_back((-V << 1) | 1);
2201 }
2202 
2203 void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
2204                                          bool isGlobal) {
2205   if (FirstVal == LastVal) return;
2206 
2207   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
2208 
2209   unsigned AggregateAbbrev = 0;
2210   unsigned String8Abbrev = 0;
2211   unsigned CString7Abbrev = 0;
2212   unsigned CString6Abbrev = 0;
2213   // If this is a constant pool for the module, emit module-specific abbrevs.
2214   if (isGlobal) {
2215     // Abbrev for CST_CODE_AGGREGATE.
2216     auto Abbv = std::make_shared<BitCodeAbbrev>();
2217     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
2218     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
2220     AggregateAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2221 
2222     // Abbrev for CST_CODE_STRING.
2223     Abbv = std::make_shared<BitCodeAbbrev>();
2224     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
2225     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2226     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2227     String8Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2228     // Abbrev for CST_CODE_CSTRING.
2229     Abbv = std::make_shared<BitCodeAbbrev>();
2230     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2231     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2233     CString7Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2234     // Abbrev for CST_CODE_CSTRING.
2235     Abbv = std::make_shared<BitCodeAbbrev>();
2236     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
2237     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2238     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2239     CString6Abbrev = Stream.EmitAbbrev(std::move(Abbv));
2240   }
2241 
2242   SmallVector<uint64_t, 64> Record;
2243 
2244   const ValueEnumerator::ValueList &Vals = VE.getValues();
2245   Type *LastTy = nullptr;
2246   for (unsigned i = FirstVal; i != LastVal; ++i) {
2247     const Value *V = Vals[i].first;
2248     // If we need to switch types, do so now.
2249     if (V->getType() != LastTy) {
2250       LastTy = V->getType();
2251       Record.push_back(VE.getTypeID(LastTy));
2252       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
2253                         CONSTANTS_SETTYPE_ABBREV);
2254       Record.clear();
2255     }
2256 
2257     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
2258       Record.push_back(unsigned(IA->hasSideEffects()) |
2259                        unsigned(IA->isAlignStack()) << 1 |
2260                        unsigned(IA->getDialect()&1) << 2);
2261 
2262       // Add the asm string.
2263       const std::string &AsmStr = IA->getAsmString();
2264       Record.push_back(AsmStr.size());
2265       Record.append(AsmStr.begin(), AsmStr.end());
2266 
2267       // Add the constraint string.
2268       const std::string &ConstraintStr = IA->getConstraintString();
2269       Record.push_back(ConstraintStr.size());
2270       Record.append(ConstraintStr.begin(), ConstraintStr.end());
2271       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
2272       Record.clear();
2273       continue;
2274     }
2275     const Constant *C = cast<Constant>(V);
2276     unsigned Code = -1U;
2277     unsigned AbbrevToUse = 0;
2278     if (C->isNullValue()) {
2279       Code = bitc::CST_CODE_NULL;
2280     } else if (isa<UndefValue>(C)) {
2281       Code = bitc::CST_CODE_UNDEF;
2282     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
2283       if (IV->getBitWidth() <= 64) {
2284         uint64_t V = IV->getSExtValue();
2285         emitSignedInt64(Record, V);
2286         Code = bitc::CST_CODE_INTEGER;
2287         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
2288       } else {                             // Wide integers, > 64 bits in size.
2289         // We have an arbitrary precision integer value to write whose
2290         // bit width is > 64. However, in canonical unsigned integer
2291         // format it is likely that the high bits are going to be zero.
2292         // So, we only write the number of active words.
2293         unsigned NWords = IV->getValue().getActiveWords();
2294         const uint64_t *RawWords = IV->getValue().getRawData();
2295         for (unsigned i = 0; i != NWords; ++i) {
2296           emitSignedInt64(Record, RawWords[i]);
2297         }
2298         Code = bitc::CST_CODE_WIDE_INTEGER;
2299       }
2300     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
2301       Code = bitc::CST_CODE_FLOAT;
2302       Type *Ty = CFP->getType();
2303       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
2304         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
2305       } else if (Ty->isX86_FP80Ty()) {
2306         // api needed to prevent premature destruction
2307         // bits are not in the same order as a normal i80 APInt, compensate.
2308         APInt api = CFP->getValueAPF().bitcastToAPInt();
2309         const uint64_t *p = api.getRawData();
2310         Record.push_back((p[1] << 48) | (p[0] >> 16));
2311         Record.push_back(p[0] & 0xffffLL);
2312       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
2313         APInt api = CFP->getValueAPF().bitcastToAPInt();
2314         const uint64_t *p = api.getRawData();
2315         Record.push_back(p[0]);
2316         Record.push_back(p[1]);
2317       } else {
2318         assert(0 && "Unknown FP type!");
2319       }
2320     } else if (isa<ConstantDataSequential>(C) &&
2321                cast<ConstantDataSequential>(C)->isString()) {
2322       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
2323       // Emit constant strings specially.
2324       unsigned NumElts = Str->getNumElements();
2325       // If this is a null-terminated string, use the denser CSTRING encoding.
2326       if (Str->isCString()) {
2327         Code = bitc::CST_CODE_CSTRING;
2328         --NumElts;  // Don't encode the null, which isn't allowed by char6.
2329       } else {
2330         Code = bitc::CST_CODE_STRING;
2331         AbbrevToUse = String8Abbrev;
2332       }
2333       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
2334       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
2335       for (unsigned i = 0; i != NumElts; ++i) {
2336         unsigned char V = Str->getElementAsInteger(i);
2337         Record.push_back(V);
2338         isCStr7 &= (V & 128) == 0;
2339         if (isCStrChar6)
2340           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
2341       }
2342 
2343       if (isCStrChar6)
2344         AbbrevToUse = CString6Abbrev;
2345       else if (isCStr7)
2346         AbbrevToUse = CString7Abbrev;
2347     } else if (const ConstantDataSequential *CDS =
2348                   dyn_cast<ConstantDataSequential>(C)) {
2349       Code = bitc::CST_CODE_DATA;
2350       Type *EltTy = CDS->getType()->getElementType();
2351       if (isa<IntegerType>(EltTy)) {
2352         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2353           Record.push_back(CDS->getElementAsInteger(i));
2354       } else {
2355         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
2356           Record.push_back(
2357               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
2358       }
2359     } else if (isa<ConstantAggregate>(C)) {
2360       Code = bitc::CST_CODE_AGGREGATE;
2361       for (const Value *Op : C->operands())
2362         Record.push_back(VE.getValueID(Op));
2363       AbbrevToUse = AggregateAbbrev;
2364     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
2365       switch (CE->getOpcode()) {
2366       default:
2367         if (Instruction::isCast(CE->getOpcode())) {
2368           Code = bitc::CST_CODE_CE_CAST;
2369           Record.push_back(getEncodedCastOpcode(CE->getOpcode()));
2370           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2371           Record.push_back(VE.getValueID(C->getOperand(0)));
2372           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
2373         } else {
2374           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
2375           Code = bitc::CST_CODE_CE_BINOP;
2376           Record.push_back(getEncodedBinaryOpcode(CE->getOpcode()));
2377           Record.push_back(VE.getValueID(C->getOperand(0)));
2378           Record.push_back(VE.getValueID(C->getOperand(1)));
2379           uint64_t Flags = getOptimizationFlags(CE);
2380           if (Flags != 0)
2381             Record.push_back(Flags);
2382         }
2383         break;
2384       case Instruction::GetElementPtr: {
2385         Code = bitc::CST_CODE_CE_GEP;
2386         const auto *GO = cast<GEPOperator>(C);
2387         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
2388         if (Optional<unsigned> Idx = GO->getInRangeIndex()) {
2389           Code = bitc::CST_CODE_CE_GEP_WITH_INRANGE_INDEX;
2390           Record.push_back((*Idx << 1) | GO->isInBounds());
2391         } else if (GO->isInBounds())
2392           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
2393         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
2394           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
2395           Record.push_back(VE.getValueID(C->getOperand(i)));
2396         }
2397         break;
2398       }
2399       case Instruction::Select:
2400         Code = bitc::CST_CODE_CE_SELECT;
2401         Record.push_back(VE.getValueID(C->getOperand(0)));
2402         Record.push_back(VE.getValueID(C->getOperand(1)));
2403         Record.push_back(VE.getValueID(C->getOperand(2)));
2404         break;
2405       case Instruction::ExtractElement:
2406         Code = bitc::CST_CODE_CE_EXTRACTELT;
2407         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2408         Record.push_back(VE.getValueID(C->getOperand(0)));
2409         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
2410         Record.push_back(VE.getValueID(C->getOperand(1)));
2411         break;
2412       case Instruction::InsertElement:
2413         Code = bitc::CST_CODE_CE_INSERTELT;
2414         Record.push_back(VE.getValueID(C->getOperand(0)));
2415         Record.push_back(VE.getValueID(C->getOperand(1)));
2416         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
2417         Record.push_back(VE.getValueID(C->getOperand(2)));
2418         break;
2419       case Instruction::ShuffleVector:
2420         // If the return type and argument types are the same, this is a
2421         // standard shufflevector instruction.  If the types are different,
2422         // then the shuffle is widening or truncating the input vectors, and
2423         // the argument type must also be encoded.
2424         if (C->getType() == C->getOperand(0)->getType()) {
2425           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
2426         } else {
2427           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
2428           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2429         }
2430         Record.push_back(VE.getValueID(C->getOperand(0)));
2431         Record.push_back(VE.getValueID(C->getOperand(1)));
2432         Record.push_back(VE.getValueID(C->getOperand(2)));
2433         break;
2434       case Instruction::ICmp:
2435       case Instruction::FCmp:
2436         Code = bitc::CST_CODE_CE_CMP;
2437         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
2438         Record.push_back(VE.getValueID(C->getOperand(0)));
2439         Record.push_back(VE.getValueID(C->getOperand(1)));
2440         Record.push_back(CE->getPredicate());
2441         break;
2442       }
2443     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
2444       Code = bitc::CST_CODE_BLOCKADDRESS;
2445       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
2446       Record.push_back(VE.getValueID(BA->getFunction()));
2447       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
2448     } else {
2449 #ifndef NDEBUG
2450       C->dump();
2451 #endif
2452       llvm_unreachable("Unknown constant!");
2453     }
2454     Stream.EmitRecord(Code, Record, AbbrevToUse);
2455     Record.clear();
2456   }
2457 
2458   Stream.ExitBlock();
2459 }
2460 
2461 void ModuleBitcodeWriter::writeModuleConstants() {
2462   const ValueEnumerator::ValueList &Vals = VE.getValues();
2463 
2464   // Find the first constant to emit, which is the first non-globalvalue value.
2465   // We know globalvalues have been emitted by WriteModuleInfo.
2466   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
2467     if (!isa<GlobalValue>(Vals[i].first)) {
2468       writeConstants(i, Vals.size(), true);
2469       return;
2470     }
2471   }
2472 }
2473 
2474 /// pushValueAndType - The file has to encode both the value and type id for
2475 /// many values, because we need to know what type to create for forward
2476 /// references.  However, most operands are not forward references, so this type
2477 /// field is not needed.
2478 ///
2479 /// This function adds V's value ID to Vals.  If the value ID is higher than the
2480 /// instruction ID, then it is a forward reference, and it also includes the
2481 /// type ID.  The value ID that is written is encoded relative to the InstID.
2482 bool ModuleBitcodeWriter::pushValueAndType(const Value *V, unsigned InstID,
2483                                            SmallVectorImpl<unsigned> &Vals) {
2484   unsigned ValID = VE.getValueID(V);
2485   // Make encoding relative to the InstID.
2486   Vals.push_back(InstID - ValID);
2487   if (ValID >= InstID) {
2488     Vals.push_back(VE.getTypeID(V->getType()));
2489     return true;
2490   }
2491   return false;
2492 }
2493 
2494 void ModuleBitcodeWriter::writeOperandBundles(ImmutableCallSite CS,
2495                                               unsigned InstID) {
2496   SmallVector<unsigned, 64> Record;
2497   LLVMContext &C = CS.getInstruction()->getContext();
2498 
2499   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
2500     const auto &Bundle = CS.getOperandBundleAt(i);
2501     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
2502 
2503     for (auto &Input : Bundle.Inputs)
2504       pushValueAndType(Input, InstID, Record);
2505 
2506     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
2507     Record.clear();
2508   }
2509 }
2510 
2511 /// pushValue - Like pushValueAndType, but where the type of the value is
2512 /// omitted (perhaps it was already encoded in an earlier operand).
2513 void ModuleBitcodeWriter::pushValue(const Value *V, unsigned InstID,
2514                                     SmallVectorImpl<unsigned> &Vals) {
2515   unsigned ValID = VE.getValueID(V);
2516   Vals.push_back(InstID - ValID);
2517 }
2518 
2519 void ModuleBitcodeWriter::pushValueSigned(const Value *V, unsigned InstID,
2520                                           SmallVectorImpl<uint64_t> &Vals) {
2521   unsigned ValID = VE.getValueID(V);
2522   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
2523   emitSignedInt64(Vals, diff);
2524 }
2525 
2526 /// WriteInstruction - Emit an instruction to the specified stream.
2527 void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
2528                                            unsigned InstID,
2529                                            SmallVectorImpl<unsigned> &Vals) {
2530   unsigned Code = 0;
2531   unsigned AbbrevToUse = 0;
2532   VE.setInstructionID(&I);
2533   switch (I.getOpcode()) {
2534   default:
2535     if (Instruction::isCast(I.getOpcode())) {
2536       Code = bitc::FUNC_CODE_INST_CAST;
2537       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2538         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
2539       Vals.push_back(VE.getTypeID(I.getType()));
2540       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
2541     } else {
2542       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
2543       Code = bitc::FUNC_CODE_INST_BINOP;
2544       if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2545         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
2546       pushValue(I.getOperand(1), InstID, Vals);
2547       Vals.push_back(getEncodedBinaryOpcode(I.getOpcode()));
2548       uint64_t Flags = getOptimizationFlags(&I);
2549       if (Flags != 0) {
2550         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
2551           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
2552         Vals.push_back(Flags);
2553       }
2554     }
2555     break;
2556 
2557   case Instruction::GetElementPtr: {
2558     Code = bitc::FUNC_CODE_INST_GEP;
2559     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
2560     auto &GEPInst = cast<GetElementPtrInst>(I);
2561     Vals.push_back(GEPInst.isInBounds());
2562     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
2563     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
2564       pushValueAndType(I.getOperand(i), InstID, Vals);
2565     break;
2566   }
2567   case Instruction::ExtractValue: {
2568     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
2569     pushValueAndType(I.getOperand(0), InstID, Vals);
2570     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
2571     Vals.append(EVI->idx_begin(), EVI->idx_end());
2572     break;
2573   }
2574   case Instruction::InsertValue: {
2575     Code = bitc::FUNC_CODE_INST_INSERTVAL;
2576     pushValueAndType(I.getOperand(0), InstID, Vals);
2577     pushValueAndType(I.getOperand(1), InstID, Vals);
2578     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
2579     Vals.append(IVI->idx_begin(), IVI->idx_end());
2580     break;
2581   }
2582   case Instruction::Select:
2583     Code = bitc::FUNC_CODE_INST_VSELECT;
2584     pushValueAndType(I.getOperand(1), InstID, Vals);
2585     pushValue(I.getOperand(2), InstID, Vals);
2586     pushValueAndType(I.getOperand(0), InstID, Vals);
2587     break;
2588   case Instruction::ExtractElement:
2589     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
2590     pushValueAndType(I.getOperand(0), InstID, Vals);
2591     pushValueAndType(I.getOperand(1), InstID, Vals);
2592     break;
2593   case Instruction::InsertElement:
2594     Code = bitc::FUNC_CODE_INST_INSERTELT;
2595     pushValueAndType(I.getOperand(0), InstID, Vals);
2596     pushValue(I.getOperand(1), InstID, Vals);
2597     pushValueAndType(I.getOperand(2), InstID, Vals);
2598     break;
2599   case Instruction::ShuffleVector:
2600     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
2601     pushValueAndType(I.getOperand(0), InstID, Vals);
2602     pushValue(I.getOperand(1), InstID, Vals);
2603     pushValue(I.getOperand(2), InstID, Vals);
2604     break;
2605   case Instruction::ICmp:
2606   case Instruction::FCmp: {
2607     // compare returning Int1Ty or vector of Int1Ty
2608     Code = bitc::FUNC_CODE_INST_CMP2;
2609     pushValueAndType(I.getOperand(0), InstID, Vals);
2610     pushValue(I.getOperand(1), InstID, Vals);
2611     Vals.push_back(cast<CmpInst>(I).getPredicate());
2612     uint64_t Flags = getOptimizationFlags(&I);
2613     if (Flags != 0)
2614       Vals.push_back(Flags);
2615     break;
2616   }
2617 
2618   case Instruction::Ret:
2619     {
2620       Code = bitc::FUNC_CODE_INST_RET;
2621       unsigned NumOperands = I.getNumOperands();
2622       if (NumOperands == 0)
2623         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
2624       else if (NumOperands == 1) {
2625         if (!pushValueAndType(I.getOperand(0), InstID, Vals))
2626           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
2627       } else {
2628         for (unsigned i = 0, e = NumOperands; i != e; ++i)
2629           pushValueAndType(I.getOperand(i), InstID, Vals);
2630       }
2631     }
2632     break;
2633   case Instruction::Br:
2634     {
2635       Code = bitc::FUNC_CODE_INST_BR;
2636       const BranchInst &II = cast<BranchInst>(I);
2637       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
2638       if (II.isConditional()) {
2639         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2640         pushValue(II.getCondition(), InstID, Vals);
2641       }
2642     }
2643     break;
2644   case Instruction::Switch:
2645     {
2646       Code = bitc::FUNC_CODE_INST_SWITCH;
2647       const SwitchInst &SI = cast<SwitchInst>(I);
2648       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2649       pushValue(SI.getCondition(), InstID, Vals);
2650       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2651       for (auto Case : SI.cases()) {
2652         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2653         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2654       }
2655     }
2656     break;
2657   case Instruction::IndirectBr:
2658     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2659     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2660     // Encode the address operand as relative, but not the basic blocks.
2661     pushValue(I.getOperand(0), InstID, Vals);
2662     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2663       Vals.push_back(VE.getValueID(I.getOperand(i)));
2664     break;
2665 
2666   case Instruction::Invoke: {
2667     const InvokeInst *II = cast<InvokeInst>(&I);
2668     const Value *Callee = II->getCalledValue();
2669     FunctionType *FTy = II->getFunctionType();
2670 
2671     if (II->hasOperandBundles())
2672       writeOperandBundles(II, InstID);
2673 
2674     Code = bitc::FUNC_CODE_INST_INVOKE;
2675 
2676     Vals.push_back(VE.getAttributeListID(II->getAttributes()));
2677     Vals.push_back(II->getCallingConv() | 1 << 13);
2678     Vals.push_back(VE.getValueID(II->getNormalDest()));
2679     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2680     Vals.push_back(VE.getTypeID(FTy));
2681     pushValueAndType(Callee, InstID, Vals);
2682 
2683     // Emit value #'s for the fixed parameters.
2684     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2685       pushValue(I.getOperand(i), InstID, Vals); // fixed param.
2686 
2687     // Emit type/value pairs for varargs params.
2688     if (FTy->isVarArg()) {
2689       for (unsigned i = FTy->getNumParams(), e = II->getNumArgOperands();
2690            i != e; ++i)
2691         pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
2692     }
2693     break;
2694   }
2695   case Instruction::Resume:
2696     Code = bitc::FUNC_CODE_INST_RESUME;
2697     pushValueAndType(I.getOperand(0), InstID, Vals);
2698     break;
2699   case Instruction::CleanupRet: {
2700     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2701     const auto &CRI = cast<CleanupReturnInst>(I);
2702     pushValue(CRI.getCleanupPad(), InstID, Vals);
2703     if (CRI.hasUnwindDest())
2704       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2705     break;
2706   }
2707   case Instruction::CatchRet: {
2708     Code = bitc::FUNC_CODE_INST_CATCHRET;
2709     const auto &CRI = cast<CatchReturnInst>(I);
2710     pushValue(CRI.getCatchPad(), InstID, Vals);
2711     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2712     break;
2713   }
2714   case Instruction::CleanupPad:
2715   case Instruction::CatchPad: {
2716     const auto &FuncletPad = cast<FuncletPadInst>(I);
2717     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2718                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2719     pushValue(FuncletPad.getParentPad(), InstID, Vals);
2720 
2721     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2722     Vals.push_back(NumArgOperands);
2723     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2724       pushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals);
2725     break;
2726   }
2727   case Instruction::CatchSwitch: {
2728     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2729     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2730 
2731     pushValue(CatchSwitch.getParentPad(), InstID, Vals);
2732 
2733     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2734     Vals.push_back(NumHandlers);
2735     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2736       Vals.push_back(VE.getValueID(CatchPadBB));
2737 
2738     if (CatchSwitch.hasUnwindDest())
2739       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2740     break;
2741   }
2742   case Instruction::Unreachable:
2743     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2744     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2745     break;
2746 
2747   case Instruction::PHI: {
2748     const PHINode &PN = cast<PHINode>(I);
2749     Code = bitc::FUNC_CODE_INST_PHI;
2750     // With the newer instruction encoding, forward references could give
2751     // negative valued IDs.  This is most common for PHIs, so we use
2752     // signed VBRs.
2753     SmallVector<uint64_t, 128> Vals64;
2754     Vals64.push_back(VE.getTypeID(PN.getType()));
2755     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2756       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64);
2757       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2758     }
2759     // Emit a Vals64 vector and exit.
2760     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2761     Vals64.clear();
2762     return;
2763   }
2764 
2765   case Instruction::LandingPad: {
2766     const LandingPadInst &LP = cast<LandingPadInst>(I);
2767     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2768     Vals.push_back(VE.getTypeID(LP.getType()));
2769     Vals.push_back(LP.isCleanup());
2770     Vals.push_back(LP.getNumClauses());
2771     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2772       if (LP.isCatch(I))
2773         Vals.push_back(LandingPadInst::Catch);
2774       else
2775         Vals.push_back(LandingPadInst::Filter);
2776       pushValueAndType(LP.getClause(I), InstID, Vals);
2777     }
2778     break;
2779   }
2780 
2781   case Instruction::Alloca: {
2782     Code = bitc::FUNC_CODE_INST_ALLOCA;
2783     const AllocaInst &AI = cast<AllocaInst>(I);
2784     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2785     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2786     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2787     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2788     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2789            "not enough bits for maximum alignment");
2790     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2791     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2792     AlignRecord |= 1 << 6;
2793     AlignRecord |= AI.isSwiftError() << 7;
2794     Vals.push_back(AlignRecord);
2795     break;
2796   }
2797 
2798   case Instruction::Load:
2799     if (cast<LoadInst>(I).isAtomic()) {
2800       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2801       pushValueAndType(I.getOperand(0), InstID, Vals);
2802     } else {
2803       Code = bitc::FUNC_CODE_INST_LOAD;
2804       if (!pushValueAndType(I.getOperand(0), InstID, Vals)) // ptr
2805         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2806     }
2807     Vals.push_back(VE.getTypeID(I.getType()));
2808     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2809     Vals.push_back(cast<LoadInst>(I).isVolatile());
2810     if (cast<LoadInst>(I).isAtomic()) {
2811       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2812       Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
2813     }
2814     break;
2815   case Instruction::Store:
2816     if (cast<StoreInst>(I).isAtomic())
2817       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2818     else
2819       Code = bitc::FUNC_CODE_INST_STORE;
2820     pushValueAndType(I.getOperand(1), InstID, Vals); // ptrty + ptr
2821     pushValueAndType(I.getOperand(0), InstID, Vals); // valty + val
2822     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2823     Vals.push_back(cast<StoreInst>(I).isVolatile());
2824     if (cast<StoreInst>(I).isAtomic()) {
2825       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2826       Vals.push_back(
2827           getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
2828     }
2829     break;
2830   case Instruction::AtomicCmpXchg:
2831     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2832     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2833     pushValueAndType(I.getOperand(1), InstID, Vals); // cmp.
2834     pushValue(I.getOperand(2), InstID, Vals);        // newval.
2835     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2836     Vals.push_back(
2837         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2838     Vals.push_back(
2839         getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
2840     Vals.push_back(
2841         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2842     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2843     break;
2844   case Instruction::AtomicRMW:
2845     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2846     pushValueAndType(I.getOperand(0), InstID, Vals); // ptrty + ptr
2847     pushValue(I.getOperand(1), InstID, Vals);        // val.
2848     Vals.push_back(
2849         getEncodedRMWOperation(cast<AtomicRMWInst>(I).getOperation()));
2850     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2851     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2852     Vals.push_back(
2853         getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
2854     break;
2855   case Instruction::Fence:
2856     Code = bitc::FUNC_CODE_INST_FENCE;
2857     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2858     Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
2859     break;
2860   case Instruction::Call: {
2861     const CallInst &CI = cast<CallInst>(I);
2862     FunctionType *FTy = CI.getFunctionType();
2863 
2864     if (CI.hasOperandBundles())
2865       writeOperandBundles(&CI, InstID);
2866 
2867     Code = bitc::FUNC_CODE_INST_CALL;
2868 
2869     Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
2870 
2871     unsigned Flags = getOptimizationFlags(&I);
2872     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2873                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2874                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2875                    1 << bitc::CALL_EXPLICIT_TYPE |
2876                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2877                    unsigned(Flags != 0) << bitc::CALL_FMF);
2878     if (Flags != 0)
2879       Vals.push_back(Flags);
2880 
2881     Vals.push_back(VE.getTypeID(FTy));
2882     pushValueAndType(CI.getCalledValue(), InstID, Vals); // Callee
2883 
2884     // Emit value #'s for the fixed parameters.
2885     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2886       // Check for labels (can happen with asm labels).
2887       if (FTy->getParamType(i)->isLabelTy())
2888         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2889       else
2890         pushValue(CI.getArgOperand(i), InstID, Vals); // fixed param.
2891     }
2892 
2893     // Emit type/value pairs for varargs params.
2894     if (FTy->isVarArg()) {
2895       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2896            i != e; ++i)
2897         pushValueAndType(CI.getArgOperand(i), InstID, Vals); // varargs
2898     }
2899     break;
2900   }
2901   case Instruction::VAArg:
2902     Code = bitc::FUNC_CODE_INST_VAARG;
2903     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2904     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
2905     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2906     break;
2907   }
2908 
2909   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2910   Vals.clear();
2911 }
2912 
2913 /// Write a GlobalValue VST to the module. The purpose of this data structure is
2914 /// to allow clients to efficiently find the function body.
2915 void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
2916   DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
2917   // Get the offset of the VST we are writing, and backpatch it into
2918   // the VST forward declaration record.
2919   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2920   // The BitcodeStartBit was the stream offset of the identification block.
2921   VSTOffset -= bitcodeStartBit();
2922   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2923   // Note that we add 1 here because the offset is relative to one word
2924   // before the start of the identification block, which was historically
2925   // always the start of the regular bitcode header.
2926   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
2927 
2928   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2929 
2930   auto Abbv = std::make_shared<BitCodeAbbrev>();
2931   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2933   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2934   unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
2935 
2936   for (const Function &F : M) {
2937     uint64_t Record[2];
2938 
2939     if (F.isDeclaration())
2940       continue;
2941 
2942     Record[0] = VE.getValueID(&F);
2943 
2944     // Save the word offset of the function (from the start of the
2945     // actual bitcode written to the stream).
2946     uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
2947     assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2948     // Note that we add 1 here because the offset is relative to one word
2949     // before the start of the identification block, which was historically
2950     // always the start of the regular bitcode header.
2951     Record[1] = BitcodeIndex / 32 + 1;
2952 
2953     Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
2954   }
2955 
2956   Stream.ExitBlock();
2957 }
2958 
2959 /// Emit names for arguments, instructions and basic blocks in a function.
2960 void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
2961     const ValueSymbolTable &VST) {
2962   if (VST.empty())
2963     return;
2964 
2965   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2966 
2967   // FIXME: Set up the abbrev, we know how many values there are!
2968   // FIXME: We know if the type names can use 7-bit ascii.
2969   SmallVector<uint64_t, 64> NameVals;
2970 
2971   for (const ValueName &Name : VST) {
2972     // Figure out the encoding to use for the name.
2973     StringEncoding Bits = getStringEncoding(Name.getKey());
2974 
2975     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2976     NameVals.push_back(VE.getValueID(Name.getValue()));
2977 
2978     // VST_CODE_ENTRY:   [valueid, namechar x N]
2979     // VST_CODE_BBENTRY: [bbid, namechar x N]
2980     unsigned Code;
2981     if (isa<BasicBlock>(Name.getValue())) {
2982       Code = bitc::VST_CODE_BBENTRY;
2983       if (Bits == SE_Char6)
2984         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2985     } else {
2986       Code = bitc::VST_CODE_ENTRY;
2987       if (Bits == SE_Char6)
2988         AbbrevToUse = VST_ENTRY_6_ABBREV;
2989       else if (Bits == SE_Fixed7)
2990         AbbrevToUse = VST_ENTRY_7_ABBREV;
2991     }
2992 
2993     for (const auto P : Name.getKey())
2994       NameVals.push_back((unsigned char)P);
2995 
2996     // Emit the finished record.
2997     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2998     NameVals.clear();
2999   }
3000 
3001   Stream.ExitBlock();
3002 }
3003 
3004 void ModuleBitcodeWriter::writeUseList(UseListOrder &&Order) {
3005   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
3006   unsigned Code;
3007   if (isa<BasicBlock>(Order.V))
3008     Code = bitc::USELIST_CODE_BB;
3009   else
3010     Code = bitc::USELIST_CODE_DEFAULT;
3011 
3012   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
3013   Record.push_back(VE.getValueID(Order.V));
3014   Stream.EmitRecord(Code, Record);
3015 }
3016 
3017 void ModuleBitcodeWriter::writeUseListBlock(const Function *F) {
3018   assert(VE.shouldPreserveUseListOrder() &&
3019          "Expected to be preserving use-list order");
3020 
3021   auto hasMore = [&]() {
3022     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
3023   };
3024   if (!hasMore())
3025     // Nothing to do.
3026     return;
3027 
3028   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
3029   while (hasMore()) {
3030     writeUseList(std::move(VE.UseListOrders.back()));
3031     VE.UseListOrders.pop_back();
3032   }
3033   Stream.ExitBlock();
3034 }
3035 
3036 /// Emit a function body to the module stream.
3037 void ModuleBitcodeWriter::writeFunction(
3038     const Function &F,
3039     DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
3040   // Save the bitcode index of the start of this function block for recording
3041   // in the VST.
3042   FunctionToBitcodeIndex[&F] = Stream.GetCurrentBitNo();
3043 
3044   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
3045   VE.incorporateFunction(F);
3046 
3047   SmallVector<unsigned, 64> Vals;
3048 
3049   // Emit the number of basic blocks, so the reader can create them ahead of
3050   // time.
3051   Vals.push_back(VE.getBasicBlocks().size());
3052   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
3053   Vals.clear();
3054 
3055   // If there are function-local constants, emit them now.
3056   unsigned CstStart, CstEnd;
3057   VE.getFunctionConstantRange(CstStart, CstEnd);
3058   writeConstants(CstStart, CstEnd, false);
3059 
3060   // If there is function-local metadata, emit it now.
3061   writeFunctionMetadata(F);
3062 
3063   // Keep a running idea of what the instruction ID is.
3064   unsigned InstID = CstEnd;
3065 
3066   bool NeedsMetadataAttachment = F.hasMetadata();
3067 
3068   DILocation *LastDL = nullptr;
3069   // Finally, emit all the instructions, in order.
3070   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
3071     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
3072          I != E; ++I) {
3073       writeInstruction(*I, InstID, Vals);
3074 
3075       if (!I->getType()->isVoidTy())
3076         ++InstID;
3077 
3078       // If the instruction has metadata, write a metadata attachment later.
3079       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
3080 
3081       // If the instruction has a debug location, emit it.
3082       DILocation *DL = I->getDebugLoc();
3083       if (!DL)
3084         continue;
3085 
3086       if (DL == LastDL) {
3087         // Just repeat the same debug loc as last time.
3088         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
3089         continue;
3090       }
3091 
3092       Vals.push_back(DL->getLine());
3093       Vals.push_back(DL->getColumn());
3094       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
3095       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
3096       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
3097       Vals.clear();
3098 
3099       LastDL = DL;
3100     }
3101 
3102   // Emit names for all the instructions etc.
3103   if (auto *Symtab = F.getValueSymbolTable())
3104     writeFunctionLevelValueSymbolTable(*Symtab);
3105 
3106   if (NeedsMetadataAttachment)
3107     writeFunctionMetadataAttachment(F);
3108   if (VE.shouldPreserveUseListOrder())
3109     writeUseListBlock(&F);
3110   VE.purgeFunction();
3111   Stream.ExitBlock();
3112 }
3113 
3114 // Emit blockinfo, which defines the standard abbreviations etc.
3115 void ModuleBitcodeWriter::writeBlockInfo() {
3116   // We only want to emit block info records for blocks that have multiple
3117   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
3118   // Other blocks can define their abbrevs inline.
3119   Stream.EnterBlockInfoBlock();
3120 
3121   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
3122     auto Abbv = std::make_shared<BitCodeAbbrev>();
3123     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
3124     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3125     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3126     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3127     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3128         VST_ENTRY_8_ABBREV)
3129       llvm_unreachable("Unexpected abbrev ordering!");
3130   }
3131 
3132   { // 7-bit fixed width VST_CODE_ENTRY strings.
3133     auto Abbv = std::make_shared<BitCodeAbbrev>();
3134     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3135     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3136     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3137     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3138     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3139         VST_ENTRY_7_ABBREV)
3140       llvm_unreachable("Unexpected abbrev ordering!");
3141   }
3142   { // 6-bit char6 VST_CODE_ENTRY strings.
3143     auto Abbv = std::make_shared<BitCodeAbbrev>();
3144     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
3145     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3146     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3147     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3148     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3149         VST_ENTRY_6_ABBREV)
3150       llvm_unreachable("Unexpected abbrev ordering!");
3151   }
3152   { // 6-bit char6 VST_CODE_BBENTRY strings.
3153     auto Abbv = std::make_shared<BitCodeAbbrev>();
3154     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
3155     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3156     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3157     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3158     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID, Abbv) !=
3159         VST_BBENTRY_6_ABBREV)
3160       llvm_unreachable("Unexpected abbrev ordering!");
3161   }
3162 
3163   { // SETTYPE abbrev for CONSTANTS_BLOCK.
3164     auto Abbv = std::make_shared<BitCodeAbbrev>();
3165     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
3166     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
3167                               VE.computeBitsRequiredForTypeIndicies()));
3168     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3169         CONSTANTS_SETTYPE_ABBREV)
3170       llvm_unreachable("Unexpected abbrev ordering!");
3171   }
3172 
3173   { // INTEGER abbrev for CONSTANTS_BLOCK.
3174     auto Abbv = std::make_shared<BitCodeAbbrev>();
3175     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
3176     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3177     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3178         CONSTANTS_INTEGER_ABBREV)
3179       llvm_unreachable("Unexpected abbrev ordering!");
3180   }
3181 
3182   { // CE_CAST abbrev for CONSTANTS_BLOCK.
3183     auto Abbv = std::make_shared<BitCodeAbbrev>();
3184     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
3185     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
3186     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
3187                               VE.computeBitsRequiredForTypeIndicies()));
3188     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
3189 
3190     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3191         CONSTANTS_CE_CAST_Abbrev)
3192       llvm_unreachable("Unexpected abbrev ordering!");
3193   }
3194   { // NULL abbrev for CONSTANTS_BLOCK.
3195     auto Abbv = std::make_shared<BitCodeAbbrev>();
3196     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
3197     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID, Abbv) !=
3198         CONSTANTS_NULL_Abbrev)
3199       llvm_unreachable("Unexpected abbrev ordering!");
3200   }
3201 
3202   // FIXME: This should only use space for first class types!
3203 
3204   { // INST_LOAD abbrev for FUNCTION_BLOCK.
3205     auto Abbv = std::make_shared<BitCodeAbbrev>();
3206     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
3207     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
3208     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
3209                               VE.computeBitsRequiredForTypeIndicies()));
3210     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
3211     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
3212     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3213         FUNCTION_INST_LOAD_ABBREV)
3214       llvm_unreachable("Unexpected abbrev ordering!");
3215   }
3216   { // INST_BINOP abbrev for FUNCTION_BLOCK.
3217     auto Abbv = std::make_shared<BitCodeAbbrev>();
3218     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3219     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3220     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3221     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3222     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3223         FUNCTION_INST_BINOP_ABBREV)
3224       llvm_unreachable("Unexpected abbrev ordering!");
3225   }
3226   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
3227     auto Abbv = std::make_shared<BitCodeAbbrev>();
3228     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
3229     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
3230     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
3231     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
3232     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8)); // flags
3233     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3234         FUNCTION_INST_BINOP_FLAGS_ABBREV)
3235       llvm_unreachable("Unexpected abbrev ordering!");
3236   }
3237   { // INST_CAST abbrev for FUNCTION_BLOCK.
3238     auto Abbv = std::make_shared<BitCodeAbbrev>();
3239     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
3240     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
3241     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
3242                               VE.computeBitsRequiredForTypeIndicies()));
3243     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
3244     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3245         FUNCTION_INST_CAST_ABBREV)
3246       llvm_unreachable("Unexpected abbrev ordering!");
3247   }
3248 
3249   { // INST_RET abbrev for FUNCTION_BLOCK.
3250     auto Abbv = std::make_shared<BitCodeAbbrev>();
3251     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3252     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3253         FUNCTION_INST_RET_VOID_ABBREV)
3254       llvm_unreachable("Unexpected abbrev ordering!");
3255   }
3256   { // INST_RET abbrev for FUNCTION_BLOCK.
3257     auto Abbv = std::make_shared<BitCodeAbbrev>();
3258     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
3259     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
3260     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3261         FUNCTION_INST_RET_VAL_ABBREV)
3262       llvm_unreachable("Unexpected abbrev ordering!");
3263   }
3264   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
3265     auto Abbv = std::make_shared<BitCodeAbbrev>();
3266     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
3267     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3268         FUNCTION_INST_UNREACHABLE_ABBREV)
3269       llvm_unreachable("Unexpected abbrev ordering!");
3270   }
3271   {
3272     auto Abbv = std::make_shared<BitCodeAbbrev>();
3273     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
3274     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
3275     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
3276                               Log2_32_Ceil(VE.getTypes().size() + 1)));
3277     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3278     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3279     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
3280         FUNCTION_INST_GEP_ABBREV)
3281       llvm_unreachable("Unexpected abbrev ordering!");
3282   }
3283 
3284   Stream.ExitBlock();
3285 }
3286 
3287 /// Write the module path strings, currently only used when generating
3288 /// a combined index file.
3289 void IndexBitcodeWriter::writeModStrings() {
3290   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
3291 
3292   // TODO: See which abbrev sizes we actually need to emit
3293 
3294   // 8-bit fixed-width MST_ENTRY strings.
3295   auto Abbv = std::make_shared<BitCodeAbbrev>();
3296   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3297   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3298   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3299   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
3300   unsigned Abbrev8Bit = Stream.EmitAbbrev(std::move(Abbv));
3301 
3302   // 7-bit fixed width MST_ENTRY strings.
3303   Abbv = std::make_shared<BitCodeAbbrev>();
3304   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3305   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3306   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3307   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
3308   unsigned Abbrev7Bit = Stream.EmitAbbrev(std::move(Abbv));
3309 
3310   // 6-bit char6 MST_ENTRY strings.
3311   Abbv = std::make_shared<BitCodeAbbrev>();
3312   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
3313   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3314   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3315   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3316   unsigned Abbrev6Bit = Stream.EmitAbbrev(std::move(Abbv));
3317 
3318   // Module Hash, 160 bits SHA1. Optionally, emitted after each MST_CODE_ENTRY.
3319   Abbv = std::make_shared<BitCodeAbbrev>();
3320   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_HASH));
3321   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3322   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3324   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3325   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
3326   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
3327 
3328   SmallVector<unsigned, 64> Vals;
3329   forEachModule(
3330       [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
3331         StringRef Key = MPSE.getKey();
3332         const auto &Value = MPSE.getValue();
3333         StringEncoding Bits = getStringEncoding(Key);
3334         unsigned AbbrevToUse = Abbrev8Bit;
3335         if (Bits == SE_Char6)
3336           AbbrevToUse = Abbrev6Bit;
3337         else if (Bits == SE_Fixed7)
3338           AbbrevToUse = Abbrev7Bit;
3339 
3340         Vals.push_back(Value.first);
3341         Vals.append(Key.begin(), Key.end());
3342 
3343         // Emit the finished record.
3344         Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
3345 
3346         // Emit an optional hash for the module now
3347         const auto &Hash = Value.second;
3348         if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
3349           Vals.assign(Hash.begin(), Hash.end());
3350           // Emit the hash record.
3351           Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
3352         }
3353 
3354         Vals.clear();
3355       });
3356   Stream.ExitBlock();
3357 }
3358 
3359 /// Write the function type metadata related records that need to appear before
3360 /// a function summary entry (whether per-module or combined).
3361 static void writeFunctionTypeMetadataRecords(
3362     BitstreamWriter &Stream, FunctionSummary *FS,
3363     std::set<GlobalValue::GUID> &ReferencedTypeIds) {
3364   if (!FS->type_tests().empty()) {
3365     Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
3366     for (auto &TT : FS->type_tests())
3367       ReferencedTypeIds.insert(TT);
3368   }
3369 
3370   SmallVector<uint64_t, 64> Record;
3371 
3372   auto WriteVFuncIdVec = [&](uint64_t Ty,
3373                              ArrayRef<FunctionSummary::VFuncId> VFs) {
3374     if (VFs.empty())
3375       return;
3376     Record.clear();
3377     for (auto &VF : VFs) {
3378       Record.push_back(VF.GUID);
3379       Record.push_back(VF.Offset);
3380       ReferencedTypeIds.insert(VF.GUID);
3381     }
3382     Stream.EmitRecord(Ty, Record);
3383   };
3384 
3385   WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
3386                   FS->type_test_assume_vcalls());
3387   WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
3388                   FS->type_checked_load_vcalls());
3389 
3390   auto WriteConstVCallVec = [&](uint64_t Ty,
3391                                 ArrayRef<FunctionSummary::ConstVCall> VCs) {
3392     for (auto &VC : VCs) {
3393       Record.clear();
3394       Record.push_back(VC.VFunc.GUID);
3395       ReferencedTypeIds.insert(VC.VFunc.GUID);
3396       Record.push_back(VC.VFunc.Offset);
3397       Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
3398       Stream.EmitRecord(Ty, Record);
3399     }
3400   };
3401 
3402   WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
3403                      FS->type_test_assume_const_vcalls());
3404   WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
3405                      FS->type_checked_load_const_vcalls());
3406 }
3407 
3408 static void writeWholeProgramDevirtResolutionByArg(
3409     SmallVector<uint64_t, 64> &NameVals, const std::vector<uint64_t> &args,
3410     const WholeProgramDevirtResolution::ByArg &ByArg) {
3411   NameVals.push_back(args.size());
3412   NameVals.insert(NameVals.end(), args.begin(), args.end());
3413 
3414   NameVals.push_back(ByArg.TheKind);
3415   NameVals.push_back(ByArg.Info);
3416   NameVals.push_back(ByArg.Byte);
3417   NameVals.push_back(ByArg.Bit);
3418 }
3419 
3420 static void writeWholeProgramDevirtResolution(
3421     SmallVector<uint64_t, 64> &NameVals, StringTableBuilder &StrtabBuilder,
3422     uint64_t Id, const WholeProgramDevirtResolution &Wpd) {
3423   NameVals.push_back(Id);
3424 
3425   NameVals.push_back(Wpd.TheKind);
3426   NameVals.push_back(StrtabBuilder.add(Wpd.SingleImplName));
3427   NameVals.push_back(Wpd.SingleImplName.size());
3428 
3429   NameVals.push_back(Wpd.ResByArg.size());
3430   for (auto &A : Wpd.ResByArg)
3431     writeWholeProgramDevirtResolutionByArg(NameVals, A.first, A.second);
3432 }
3433 
3434 static void writeTypeIdSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
3435                                      StringTableBuilder &StrtabBuilder,
3436                                      const std::string &Id,
3437                                      const TypeIdSummary &Summary) {
3438   NameVals.push_back(StrtabBuilder.add(Id));
3439   NameVals.push_back(Id.size());
3440 
3441   NameVals.push_back(Summary.TTRes.TheKind);
3442   NameVals.push_back(Summary.TTRes.SizeM1BitWidth);
3443   NameVals.push_back(Summary.TTRes.AlignLog2);
3444   NameVals.push_back(Summary.TTRes.SizeM1);
3445   NameVals.push_back(Summary.TTRes.BitMask);
3446   NameVals.push_back(Summary.TTRes.InlineBits);
3447 
3448   for (auto &W : Summary.WPDRes)
3449     writeWholeProgramDevirtResolution(NameVals, StrtabBuilder, W.first,
3450                                       W.second);
3451 }
3452 
3453 // Helper to emit a single function summary record.
3454 void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
3455     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
3456     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
3457     const Function &F) {
3458   NameVals.push_back(ValueID);
3459 
3460   FunctionSummary *FS = cast<FunctionSummary>(Summary);
3461   std::set<GlobalValue::GUID> ReferencedTypeIds;
3462   writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3463 
3464   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3465   NameVals.push_back(FS->instCount());
3466   NameVals.push_back(getEncodedFFlags(FS->fflags()));
3467   NameVals.push_back(FS->refs().size());
3468 
3469   for (auto &RI : FS->refs())
3470     NameVals.push_back(VE.getValueID(RI.getValue()));
3471 
3472   bool HasProfileData =
3473       F.hasProfileData() || ForceSummaryEdgesCold != FunctionSummary::FSHT_None;
3474   for (auto &ECI : FS->calls()) {
3475     NameVals.push_back(getValueId(ECI.first));
3476     if (HasProfileData)
3477       NameVals.push_back(static_cast<uint8_t>(ECI.second.Hotness));
3478     else if (WriteRelBFToSummary)
3479       NameVals.push_back(ECI.second.RelBlockFreq);
3480   }
3481 
3482   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3483   unsigned Code =
3484       (HasProfileData ? bitc::FS_PERMODULE_PROFILE
3485                       : (WriteRelBFToSummary ? bitc::FS_PERMODULE_RELBF
3486                                              : bitc::FS_PERMODULE));
3487 
3488   // Emit the finished record.
3489   Stream.EmitRecord(Code, NameVals, FSAbbrev);
3490   NameVals.clear();
3491 }
3492 
3493 // Collect the global value references in the given variable's initializer,
3494 // and emit them in a summary record.
3495 void ModuleBitcodeWriterBase::writeModuleLevelReferences(
3496     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
3497     unsigned FSModRefsAbbrev) {
3498   auto VI = Index->getValueInfo(V.getGUID());
3499   if (!VI || VI.getSummaryList().empty()) {
3500     // Only declarations should not have a summary (a declaration might however
3501     // have a summary if the def was in module level asm).
3502     assert(V.isDeclaration());
3503     return;
3504   }
3505   auto *Summary = VI.getSummaryList()[0].get();
3506   NameVals.push_back(VE.getValueID(&V));
3507   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
3508   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3509 
3510   unsigned SizeBeforeRefs = NameVals.size();
3511   for (auto &RI : VS->refs())
3512     NameVals.push_back(VE.getValueID(RI.getValue()));
3513   // Sort the refs for determinism output, the vector returned by FS->refs() has
3514   // been initialized from a DenseSet.
3515   llvm::sort(NameVals.begin() + SizeBeforeRefs, NameVals.end());
3516 
3517   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
3518                     FSModRefsAbbrev);
3519   NameVals.clear();
3520 }
3521 
3522 // Current version for the summary.
3523 // This is bumped whenever we introduce changes in the way some record are
3524 // interpreted, like flags for instance.
3525 static const uint64_t INDEX_VERSION = 4;
3526 
3527 /// Emit the per-module summary section alongside the rest of
3528 /// the module's bitcode.
3529 void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
3530   // By default we compile with ThinLTO if the module has a summary, but the
3531   // client can request full LTO with a module flag.
3532   bool IsThinLTO = true;
3533   if (auto *MD =
3534           mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
3535     IsThinLTO = MD->getZExtValue();
3536   Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
3537                                  : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
3538                        4);
3539 
3540   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3541 
3542   if (Index->begin() == Index->end()) {
3543     Stream.ExitBlock();
3544     return;
3545   }
3546 
3547   for (const auto &GVI : valueIds()) {
3548     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3549                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3550   }
3551 
3552   // Abbrev for FS_PERMODULE_PROFILE.
3553   auto Abbv = std::make_shared<BitCodeAbbrev>();
3554   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
3555   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3556   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3557   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3558   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3559   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3560   // numrefs x valueid, n x (valueid, hotness)
3561   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3562   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3563   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3564 
3565   // Abbrev for FS_PERMODULE or FS_PERMODULE_RELBF.
3566   Abbv = std::make_shared<BitCodeAbbrev>();
3567   if (WriteRelBFToSummary)
3568     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_RELBF));
3569   else
3570     Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
3571   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3572   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3573   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3574   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3575   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3576   // numrefs x valueid, n x (valueid [, rel_block_freq])
3577   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3578   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3579   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3580 
3581   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
3582   Abbv = std::make_shared<BitCodeAbbrev>();
3583   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
3584   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
3585   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // flags
3586   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
3587   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3588   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3589 
3590   // Abbrev for FS_ALIAS.
3591   Abbv = std::make_shared<BitCodeAbbrev>();
3592   Abbv->Add(BitCodeAbbrevOp(bitc::FS_ALIAS));
3593   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3594   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3595   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3596   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3597 
3598   SmallVector<uint64_t, 64> NameVals;
3599   // Iterate over the list of functions instead of the Index to
3600   // ensure the ordering is stable.
3601   for (const Function &F : M) {
3602     // Summary emission does not support anonymous functions, they have to
3603     // renamed using the anonymous function renaming pass.
3604     if (!F.hasName())
3605       report_fatal_error("Unexpected anonymous function when writing summary");
3606 
3607     ValueInfo VI = Index->getValueInfo(F.getGUID());
3608     if (!VI || VI.getSummaryList().empty()) {
3609       // Only declarations should not have a summary (a declaration might
3610       // however have a summary if the def was in module level asm).
3611       assert(F.isDeclaration());
3612       continue;
3613     }
3614     auto *Summary = VI.getSummaryList()[0].get();
3615     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
3616                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
3617   }
3618 
3619   // Capture references from GlobalVariable initializers, which are outside
3620   // of a function scope.
3621   for (const GlobalVariable &G : M.globals())
3622     writeModuleLevelReferences(G, NameVals, FSModRefsAbbrev);
3623 
3624   for (const GlobalAlias &A : M.aliases()) {
3625     auto *Aliasee = A.getBaseObject();
3626     if (!Aliasee->hasName())
3627       // Nameless function don't have an entry in the summary, skip it.
3628       continue;
3629     auto AliasId = VE.getValueID(&A);
3630     auto AliaseeId = VE.getValueID(Aliasee);
3631     NameVals.push_back(AliasId);
3632     auto *Summary = Index->getGlobalValueSummary(A);
3633     AliasSummary *AS = cast<AliasSummary>(Summary);
3634     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3635     NameVals.push_back(AliaseeId);
3636     Stream.EmitRecord(bitc::FS_ALIAS, NameVals, FSAliasAbbrev);
3637     NameVals.clear();
3638   }
3639 
3640   Stream.ExitBlock();
3641 }
3642 
3643 /// Emit the combined summary section into the combined index file.
3644 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
3645   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3646   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
3647 
3648   // Write the index flags.
3649   uint64_t Flags = 0;
3650   if (Index.withGlobalValueDeadStripping())
3651     Flags |= 0x1;
3652   if (Index.skipModuleByDistributedBackend())
3653     Flags |= 0x2;
3654   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Flags});
3655 
3656   for (const auto &GVI : valueIds()) {
3657     Stream.EmitRecord(bitc::FS_VALUE_GUID,
3658                       ArrayRef<uint64_t>{GVI.second, GVI.first});
3659   }
3660 
3661   // Abbrev for FS_COMBINED.
3662   auto Abbv = std::make_shared<BitCodeAbbrev>();
3663   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3664   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3665   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3666   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3667   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3668   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3669   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3670   // numrefs x valueid, n x (valueid)
3671   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3672   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3673   unsigned FSCallsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3674 
3675   // Abbrev for FS_COMBINED_PROFILE.
3676   Abbv = std::make_shared<BitCodeAbbrev>();
3677   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3678   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3679   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3680   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3681   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3682   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
3683   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3684   // numrefs x valueid, n x (valueid, hotness)
3685   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3686   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3687   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3688 
3689   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3690   Abbv = std::make_shared<BitCodeAbbrev>();
3691   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3692   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3693   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3694   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3695   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3696   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3697   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3698 
3699   // Abbrev for FS_COMBINED_ALIAS.
3700   Abbv = std::make_shared<BitCodeAbbrev>();
3701   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_ALIAS));
3702   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3703   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3704   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
3705   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
3706   unsigned FSAliasAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3707 
3708   // The aliases are emitted as a post-pass, and will point to the value
3709   // id of the aliasee. Save them in a vector for post-processing.
3710   SmallVector<AliasSummary *, 64> Aliases;
3711 
3712   // Save the value id for each summary for alias emission.
3713   DenseMap<const GlobalValueSummary *, unsigned> SummaryToValueIdMap;
3714 
3715   SmallVector<uint64_t, 64> NameVals;
3716 
3717   // Set that will be populated during call to writeFunctionTypeMetadataRecords
3718   // with the type ids referenced by this index file.
3719   std::set<GlobalValue::GUID> ReferencedTypeIds;
3720 
3721   // For local linkage, we also emit the original name separately
3722   // immediately after the record.
3723   auto MaybeEmitOriginalName = [&](GlobalValueSummary &S) {
3724     if (!GlobalValue::isLocalLinkage(S.linkage()))
3725       return;
3726     NameVals.push_back(S.getOriginalName());
3727     Stream.EmitRecord(bitc::FS_COMBINED_ORIGINAL_NAME, NameVals);
3728     NameVals.clear();
3729   };
3730 
3731   forEachSummary([&](GVInfo I, bool IsAliasee) {
3732     GlobalValueSummary *S = I.second;
3733     assert(S);
3734 
3735     auto ValueId = getValueId(I.first);
3736     assert(ValueId);
3737     SummaryToValueIdMap[S] = *ValueId;
3738 
3739     // If this is invoked for an aliasee, we want to record the above
3740     // mapping, but then not emit a summary entry (if the aliasee is
3741     // to be imported, we will invoke this separately with IsAliasee=false).
3742     if (IsAliasee)
3743       return;
3744 
3745     if (auto *AS = dyn_cast<AliasSummary>(S)) {
3746       // Will process aliases as a post-pass because the reader wants all
3747       // global to be loaded first.
3748       Aliases.push_back(AS);
3749       return;
3750     }
3751 
3752     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3753       NameVals.push_back(*ValueId);
3754       NameVals.push_back(Index.getModuleId(VS->modulePath()));
3755       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
3756       for (auto &RI : VS->refs()) {
3757         auto RefValueId = getValueId(RI.getGUID());
3758         if (!RefValueId)
3759           continue;
3760         NameVals.push_back(*RefValueId);
3761       }
3762 
3763       // Emit the finished record.
3764       Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3765                         FSModRefsAbbrev);
3766       NameVals.clear();
3767       MaybeEmitOriginalName(*S);
3768       return;
3769     }
3770 
3771     auto *FS = cast<FunctionSummary>(S);
3772     writeFunctionTypeMetadataRecords(Stream, FS, ReferencedTypeIds);
3773 
3774     NameVals.push_back(*ValueId);
3775     NameVals.push_back(Index.getModuleId(FS->modulePath()));
3776     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
3777     NameVals.push_back(FS->instCount());
3778     NameVals.push_back(getEncodedFFlags(FS->fflags()));
3779     // Fill in below
3780     NameVals.push_back(0);
3781 
3782     unsigned Count = 0;
3783     for (auto &RI : FS->refs()) {
3784       auto RefValueId = getValueId(RI.getGUID());
3785       if (!RefValueId)
3786         continue;
3787       NameVals.push_back(*RefValueId);
3788       Count++;
3789     }
3790     NameVals[5] = Count;
3791 
3792     bool HasProfileData = false;
3793     for (auto &EI : FS->calls()) {
3794       HasProfileData |=
3795           EI.second.getHotness() != CalleeInfo::HotnessType::Unknown;
3796       if (HasProfileData)
3797         break;
3798     }
3799 
3800     for (auto &EI : FS->calls()) {
3801       // If this GUID doesn't have a value id, it doesn't have a function
3802       // summary and we don't need to record any calls to it.
3803       GlobalValue::GUID GUID = EI.first.getGUID();
3804       auto CallValueId = getValueId(GUID);
3805       if (!CallValueId) {
3806         // For SamplePGO, the indirect call targets for local functions will
3807         // have its original name annotated in profile. We try to find the
3808         // corresponding PGOFuncName as the GUID.
3809         GUID = Index.getGUIDFromOriginalID(GUID);
3810         if (GUID == 0)
3811           continue;
3812         CallValueId = getValueId(GUID);
3813         if (!CallValueId)
3814           continue;
3815         // The mapping from OriginalId to GUID may return a GUID
3816         // that corresponds to a static variable. Filter it out here.
3817         // This can happen when
3818         // 1) There is a call to a library function which does not have
3819         // a CallValidId;
3820         // 2) There is a static variable with the  OriginalGUID identical
3821         // to the GUID of the library function in 1);
3822         // When this happens, the logic for SamplePGO kicks in and
3823         // the static variable in 2) will be found, which needs to be
3824         // filtered out.
3825         auto *GVSum = Index.getGlobalValueSummary(GUID, false);
3826         if (GVSum &&
3827             GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
3828           continue;
3829       }
3830       NameVals.push_back(*CallValueId);
3831       if (HasProfileData)
3832         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
3833     }
3834 
3835     unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3836     unsigned Code =
3837         (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3838 
3839     // Emit the finished record.
3840     Stream.EmitRecord(Code, NameVals, FSAbbrev);
3841     NameVals.clear();
3842     MaybeEmitOriginalName(*S);
3843   });
3844 
3845   for (auto *AS : Aliases) {
3846     auto AliasValueId = SummaryToValueIdMap[AS];
3847     assert(AliasValueId);
3848     NameVals.push_back(AliasValueId);
3849     NameVals.push_back(Index.getModuleId(AS->modulePath()));
3850     NameVals.push_back(getEncodedGVSummaryFlags(AS->flags()));
3851     auto AliaseeValueId = SummaryToValueIdMap[&AS->getAliasee()];
3852     assert(AliaseeValueId);
3853     NameVals.push_back(AliaseeValueId);
3854 
3855     // Emit the finished record.
3856     Stream.EmitRecord(bitc::FS_COMBINED_ALIAS, NameVals, FSAliasAbbrev);
3857     NameVals.clear();
3858     MaybeEmitOriginalName(*AS);
3859   }
3860 
3861   if (!Index.cfiFunctionDefs().empty()) {
3862     for (auto &S : Index.cfiFunctionDefs()) {
3863       NameVals.push_back(StrtabBuilder.add(S));
3864       NameVals.push_back(S.size());
3865     }
3866     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
3867     NameVals.clear();
3868   }
3869 
3870   if (!Index.cfiFunctionDecls().empty()) {
3871     for (auto &S : Index.cfiFunctionDecls()) {
3872       NameVals.push_back(StrtabBuilder.add(S));
3873       NameVals.push_back(S.size());
3874     }
3875     Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
3876     NameVals.clear();
3877   }
3878 
3879   if (!Index.typeIds().empty()) {
3880     for (auto &S : Index.typeIds()) {
3881       // Skip if not referenced in any GV summary within this index file.
3882       if (!ReferencedTypeIds.count(GlobalValue::getGUID(S.first)))
3883         continue;
3884       writeTypeIdSummaryRecord(NameVals, StrtabBuilder, S.first, S.second);
3885       Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals);
3886       NameVals.clear();
3887     }
3888   }
3889 
3890   Stream.ExitBlock();
3891 }
3892 
3893 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3894 /// current llvm version, and a record for the epoch number.
3895 static void writeIdentificationBlock(BitstreamWriter &Stream) {
3896   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3897 
3898   // Write the "user readable" string identifying the bitcode producer
3899   auto Abbv = std::make_shared<BitCodeAbbrev>();
3900   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3901   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3902   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3903   auto StringAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3904   writeStringRecord(Stream, bitc::IDENTIFICATION_CODE_STRING,
3905                     "LLVM" LLVM_VERSION_STRING, StringAbbrev);
3906 
3907   // Write the epoch version
3908   Abbv = std::make_shared<BitCodeAbbrev>();
3909   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3910   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3911   auto EpochAbbrev = Stream.EmitAbbrev(std::move(Abbv));
3912   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3913   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3914   Stream.ExitBlock();
3915 }
3916 
3917 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
3918   // Emit the module's hash.
3919   // MODULE_CODE_HASH: [5*i32]
3920   if (GenerateHash) {
3921     uint32_t Vals[5];
3922     Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
3923                                     Buffer.size() - BlockStartPos));
3924     StringRef Hash = Hasher.result();
3925     for (int Pos = 0; Pos < 20; Pos += 4) {
3926       Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
3927     }
3928 
3929     // Emit the finished record.
3930     Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
3931 
3932     if (ModHash)
3933       // Save the written hash value.
3934       std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
3935   }
3936 }
3937 
3938 void ModuleBitcodeWriter::write() {
3939   writeIdentificationBlock(Stream);
3940 
3941   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3942   size_t BlockStartPos = Buffer.size();
3943 
3944   writeModuleVersion();
3945 
3946   // Emit blockinfo, which defines the standard abbreviations etc.
3947   writeBlockInfo();
3948 
3949   // Emit information about attribute groups.
3950   writeAttributeGroupTable();
3951 
3952   // Emit information about parameter attributes.
3953   writeAttributeTable();
3954 
3955   // Emit information describing all of the types in the module.
3956   writeTypeTable();
3957 
3958   writeComdats();
3959 
3960   // Emit top-level description of module, including target triple, inline asm,
3961   // descriptors for global variables, and function prototype info.
3962   writeModuleInfo();
3963 
3964   // Emit constants.
3965   writeModuleConstants();
3966 
3967   // Emit metadata kind names.
3968   writeModuleMetadataKinds();
3969 
3970   // Emit metadata.
3971   writeModuleMetadata();
3972 
3973   // Emit module-level use-lists.
3974   if (VE.shouldPreserveUseListOrder())
3975     writeUseListBlock(nullptr);
3976 
3977   writeOperandBundleTags();
3978   writeSyncScopeNames();
3979 
3980   // Emit function bodies.
3981   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
3982   for (Module::const_iterator F = M.begin(), E = M.end(); F != E; ++F)
3983     if (!F->isDeclaration())
3984       writeFunction(*F, FunctionToBitcodeIndex);
3985 
3986   // Need to write after the above call to WriteFunction which populates
3987   // the summary information in the index.
3988   if (Index)
3989     writePerModuleGlobalValueSummary();
3990 
3991   writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
3992 
3993   writeModuleHash(BlockStartPos);
3994 
3995   Stream.ExitBlock();
3996 }
3997 
3998 static void writeInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3999                                uint32_t &Position) {
4000   support::endian::write32le(&Buffer[Position], Value);
4001   Position += 4;
4002 }
4003 
4004 /// If generating a bc file on darwin, we have to emit a
4005 /// header and trailer to make it compatible with the system archiver.  To do
4006 /// this we emit the following header, and then emit a trailer that pads the
4007 /// file out to be a multiple of 16 bytes.
4008 ///
4009 /// struct bc_header {
4010 ///   uint32_t Magic;         // 0x0B17C0DE
4011 ///   uint32_t Version;       // Version, currently always 0.
4012 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
4013 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
4014 ///   uint32_t CPUType;       // CPU specifier.
4015 ///   ... potentially more later ...
4016 /// };
4017 static void emitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
4018                                          const Triple &TT) {
4019   unsigned CPUType = ~0U;
4020 
4021   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
4022   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
4023   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
4024   // specific constants here because they are implicitly part of the Darwin ABI.
4025   enum {
4026     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
4027     DARWIN_CPU_TYPE_X86        = 7,
4028     DARWIN_CPU_TYPE_ARM        = 12,
4029     DARWIN_CPU_TYPE_POWERPC    = 18
4030   };
4031 
4032   Triple::ArchType Arch = TT.getArch();
4033   if (Arch == Triple::x86_64)
4034     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
4035   else if (Arch == Triple::x86)
4036     CPUType = DARWIN_CPU_TYPE_X86;
4037   else if (Arch == Triple::ppc)
4038     CPUType = DARWIN_CPU_TYPE_POWERPC;
4039   else if (Arch == Triple::ppc64)
4040     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
4041   else if (Arch == Triple::arm || Arch == Triple::thumb)
4042     CPUType = DARWIN_CPU_TYPE_ARM;
4043 
4044   // Traditional Bitcode starts after header.
4045   assert(Buffer.size() >= BWH_HeaderSize &&
4046          "Expected header size to be reserved");
4047   unsigned BCOffset = BWH_HeaderSize;
4048   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
4049 
4050   // Write the magic and version.
4051   unsigned Position = 0;
4052   writeInt32ToBuffer(0x0B17C0DE, Buffer, Position);
4053   writeInt32ToBuffer(0, Buffer, Position); // Version.
4054   writeInt32ToBuffer(BCOffset, Buffer, Position);
4055   writeInt32ToBuffer(BCSize, Buffer, Position);
4056   writeInt32ToBuffer(CPUType, Buffer, Position);
4057 
4058   // If the file is not a multiple of 16 bytes, insert dummy padding.
4059   while (Buffer.size() & 15)
4060     Buffer.push_back(0);
4061 }
4062 
4063 /// Helper to write the header common to all bitcode files.
4064 static void writeBitcodeHeader(BitstreamWriter &Stream) {
4065   // Emit the file header.
4066   Stream.Emit((unsigned)'B', 8);
4067   Stream.Emit((unsigned)'C', 8);
4068   Stream.Emit(0x0, 4);
4069   Stream.Emit(0xC, 4);
4070   Stream.Emit(0xE, 4);
4071   Stream.Emit(0xD, 4);
4072 }
4073 
4074 BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
4075     : Buffer(Buffer), Stream(new BitstreamWriter(Buffer)) {
4076   writeBitcodeHeader(*Stream);
4077 }
4078 
4079 BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
4080 
4081 void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
4082   Stream->EnterSubblock(Block, 3);
4083 
4084   auto Abbv = std::make_shared<BitCodeAbbrev>();
4085   Abbv->Add(BitCodeAbbrevOp(Record));
4086   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
4087   auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
4088 
4089   Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
4090 
4091   Stream->ExitBlock();
4092 }
4093 
4094 void BitcodeWriter::writeSymtab() {
4095   assert(!WroteStrtab && !WroteSymtab);
4096 
4097   // If any module has module-level inline asm, we will require a registered asm
4098   // parser for the target so that we can create an accurate symbol table for
4099   // the module.
4100   for (Module *M : Mods) {
4101     if (M->getModuleInlineAsm().empty())
4102       continue;
4103 
4104     std::string Err;
4105     const Triple TT(M->getTargetTriple());
4106     const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
4107     if (!T || !T->hasMCAsmParser())
4108       return;
4109   }
4110 
4111   WroteSymtab = true;
4112   SmallVector<char, 0> Symtab;
4113   // The irsymtab::build function may be unable to create a symbol table if the
4114   // module is malformed (e.g. it contains an invalid alias). Writing a symbol
4115   // table is not required for correctness, but we still want to be able to
4116   // write malformed modules to bitcode files, so swallow the error.
4117   if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
4118     consumeError(std::move(E));
4119     return;
4120   }
4121 
4122   writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
4123             {Symtab.data(), Symtab.size()});
4124 }
4125 
4126 void BitcodeWriter::writeStrtab() {
4127   assert(!WroteStrtab);
4128 
4129   std::vector<char> Strtab;
4130   StrtabBuilder.finalizeInOrder();
4131   Strtab.resize(StrtabBuilder.getSize());
4132   StrtabBuilder.write((uint8_t *)Strtab.data());
4133 
4134   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
4135             {Strtab.data(), Strtab.size()});
4136 
4137   WroteStrtab = true;
4138 }
4139 
4140 void BitcodeWriter::copyStrtab(StringRef Strtab) {
4141   writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
4142   WroteStrtab = true;
4143 }
4144 
4145 void BitcodeWriter::writeModule(const Module &M,
4146                                 bool ShouldPreserveUseListOrder,
4147                                 const ModuleSummaryIndex *Index,
4148                                 bool GenerateHash, ModuleHash *ModHash) {
4149   assert(!WroteStrtab);
4150 
4151   // The Mods vector is used by irsymtab::build, which requires non-const
4152   // Modules in case it needs to materialize metadata. But the bitcode writer
4153   // requires that the module is materialized, so we can cast to non-const here,
4154   // after checking that it is in fact materialized.
4155   assert(M.isMaterialized());
4156   Mods.push_back(const_cast<Module *>(&M));
4157 
4158   ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
4159                                    ShouldPreserveUseListOrder, Index,
4160                                    GenerateHash, ModHash);
4161   ModuleWriter.write();
4162 }
4163 
4164 void BitcodeWriter::writeIndex(
4165     const ModuleSummaryIndex *Index,
4166     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4167   IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
4168                                  ModuleToSummariesForIndex);
4169   IndexWriter.write();
4170 }
4171 
4172 /// Write the specified module to the specified output stream.
4173 void llvm::WriteBitcodeToFile(const Module &M, raw_ostream &Out,
4174                               bool ShouldPreserveUseListOrder,
4175                               const ModuleSummaryIndex *Index,
4176                               bool GenerateHash, ModuleHash *ModHash) {
4177   SmallVector<char, 0> Buffer;
4178   Buffer.reserve(256*1024);
4179 
4180   // If this is darwin or another generic macho target, reserve space for the
4181   // header.
4182   Triple TT(M.getTargetTriple());
4183   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4184     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
4185 
4186   BitcodeWriter Writer(Buffer);
4187   Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
4188                      ModHash);
4189   Writer.writeSymtab();
4190   Writer.writeStrtab();
4191 
4192   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
4193     emitDarwinBCHeaderAndTrailer(Buffer, TT);
4194 
4195   // Write the generated bitstream to "Out".
4196   Out.write((char*)&Buffer.front(), Buffer.size());
4197 }
4198 
4199 void IndexBitcodeWriter::write() {
4200   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4201 
4202   writeModuleVersion();
4203 
4204   // Write the module paths in the combined index.
4205   writeModStrings();
4206 
4207   // Write the summary combined index records.
4208   writeCombinedGlobalValueSummary();
4209 
4210   Stream.ExitBlock();
4211 }
4212 
4213 // Write the specified module summary index to the given raw output stream,
4214 // where it will be written in a new bitcode block. This is used when
4215 // writing the combined index file for ThinLTO. When writing a subset of the
4216 // index for a distributed backend, provide a \p ModuleToSummariesForIndex map.
4217 void llvm::WriteIndexToFile(
4218     const ModuleSummaryIndex &Index, raw_ostream &Out,
4219     const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
4220   SmallVector<char, 0> Buffer;
4221   Buffer.reserve(256 * 1024);
4222 
4223   BitcodeWriter Writer(Buffer);
4224   Writer.writeIndex(&Index, ModuleToSummariesForIndex);
4225   Writer.writeStrtab();
4226 
4227   Out.write((char *)&Buffer.front(), Buffer.size());
4228 }
4229 
4230 namespace {
4231 
4232 /// Class to manage the bitcode writing for a thin link bitcode file.
4233 class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
4234   /// ModHash is for use in ThinLTO incremental build, generated while writing
4235   /// the module bitcode file.
4236   const ModuleHash *ModHash;
4237 
4238 public:
4239   ThinLinkBitcodeWriter(const Module &M, StringTableBuilder &StrtabBuilder,
4240                         BitstreamWriter &Stream,
4241                         const ModuleSummaryIndex &Index,
4242                         const ModuleHash &ModHash)
4243       : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
4244                                 /*ShouldPreserveUseListOrder=*/false, &Index),
4245         ModHash(&ModHash) {}
4246 
4247   void write();
4248 
4249 private:
4250   void writeSimplifiedModuleInfo();
4251 };
4252 
4253 } // end anonymous namespace
4254 
4255 // This function writes a simpilified module info for thin link bitcode file.
4256 // It only contains the source file name along with the name(the offset and
4257 // size in strtab) and linkage for global values. For the global value info
4258 // entry, in order to keep linkage at offset 5, there are three zeros used
4259 // as padding.
4260 void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
4261   SmallVector<unsigned, 64> Vals;
4262   // Emit the module's source file name.
4263   {
4264     StringEncoding Bits = getStringEncoding(M.getSourceFileName());
4265     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
4266     if (Bits == SE_Char6)
4267       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
4268     else if (Bits == SE_Fixed7)
4269       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
4270 
4271     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
4272     auto Abbv = std::make_shared<BitCodeAbbrev>();
4273     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
4274     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
4275     Abbv->Add(AbbrevOpToUse);
4276     unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
4277 
4278     for (const auto P : M.getSourceFileName())
4279       Vals.push_back((unsigned char)P);
4280 
4281     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
4282     Vals.clear();
4283   }
4284 
4285   // Emit the global variable information.
4286   for (const GlobalVariable &GV : M.globals()) {
4287     // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
4288     Vals.push_back(StrtabBuilder.add(GV.getName()));
4289     Vals.push_back(GV.getName().size());
4290     Vals.push_back(0);
4291     Vals.push_back(0);
4292     Vals.push_back(0);
4293     Vals.push_back(getEncodedLinkage(GV));
4294 
4295     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
4296     Vals.clear();
4297   }
4298 
4299   // Emit the function proto information.
4300   for (const Function &F : M) {
4301     // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
4302     Vals.push_back(StrtabBuilder.add(F.getName()));
4303     Vals.push_back(F.getName().size());
4304     Vals.push_back(0);
4305     Vals.push_back(0);
4306     Vals.push_back(0);
4307     Vals.push_back(getEncodedLinkage(F));
4308 
4309     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
4310     Vals.clear();
4311   }
4312 
4313   // Emit the alias information.
4314   for (const GlobalAlias &A : M.aliases()) {
4315     // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
4316     Vals.push_back(StrtabBuilder.add(A.getName()));
4317     Vals.push_back(A.getName().size());
4318     Vals.push_back(0);
4319     Vals.push_back(0);
4320     Vals.push_back(0);
4321     Vals.push_back(getEncodedLinkage(A));
4322 
4323     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
4324     Vals.clear();
4325   }
4326 
4327   // Emit the ifunc information.
4328   for (const GlobalIFunc &I : M.ifuncs()) {
4329     // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
4330     Vals.push_back(StrtabBuilder.add(I.getName()));
4331     Vals.push_back(I.getName().size());
4332     Vals.push_back(0);
4333     Vals.push_back(0);
4334     Vals.push_back(0);
4335     Vals.push_back(getEncodedLinkage(I));
4336 
4337     Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
4338     Vals.clear();
4339   }
4340 }
4341 
4342 void ThinLinkBitcodeWriter::write() {
4343   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
4344 
4345   writeModuleVersion();
4346 
4347   writeSimplifiedModuleInfo();
4348 
4349   writePerModuleGlobalValueSummary();
4350 
4351   // Write module hash.
4352   Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
4353 
4354   Stream.ExitBlock();
4355 }
4356 
4357 void BitcodeWriter::writeThinLinkBitcode(const Module &M,
4358                                          const ModuleSummaryIndex &Index,
4359                                          const ModuleHash &ModHash) {
4360   assert(!WroteStrtab);
4361 
4362   // The Mods vector is used by irsymtab::build, which requires non-const
4363   // Modules in case it needs to materialize metadata. But the bitcode writer
4364   // requires that the module is materialized, so we can cast to non-const here,
4365   // after checking that it is in fact materialized.
4366   assert(M.isMaterialized());
4367   Mods.push_back(const_cast<Module *>(&M));
4368 
4369   ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
4370                                        ModHash);
4371   ThinLinkWriter.write();
4372 }
4373 
4374 // Write the specified thin link bitcode file to the given raw output stream,
4375 // where it will be written in a new bitcode block. This is used when
4376 // writing the per-module index file for ThinLTO.
4377 void llvm::WriteThinLinkBitcodeToFile(const Module &M, raw_ostream &Out,
4378                                       const ModuleSummaryIndex &Index,
4379                                       const ModuleHash &ModHash) {
4380   SmallVector<char, 0> Buffer;
4381   Buffer.reserve(256 * 1024);
4382 
4383   BitcodeWriter Writer(Buffer);
4384   Writer.writeThinLinkBitcode(M, Index, ModHash);
4385   Writer.writeSymtab();
4386   Writer.writeStrtab();
4387 
4388   Out.write((char *)&Buffer.front(), Buffer.size());
4389 }
4390