xref: /freebsd/contrib/llvm-project/clang/lib/Serialization/ASTWriterDecl.cpp (revision 770cf0a5f02dc8983a89c6568d741fbc25baa999)
1 //===--- ASTWriterDecl.cpp - Declaration Serialization --------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file implements serialization for Declarations.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "ASTCommon.h"
14 #include "clang/AST/Attr.h"
15 #include "clang/AST/DeclCXX.h"
16 #include "clang/AST/DeclTemplate.h"
17 #include "clang/AST/DeclVisitor.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/OpenMPClause.h"
20 #include "clang/AST/PrettyDeclStackTrace.h"
21 #include "clang/Basic/SourceManager.h"
22 #include "clang/Serialization/ASTReader.h"
23 #include "clang/Serialization/ASTRecordWriter.h"
24 #include "llvm/Bitstream/BitstreamWriter.h"
25 #include "llvm/Support/ErrorHandling.h"
26 using namespace clang;
27 using namespace serialization;
28 
29 //===----------------------------------------------------------------------===//
30 // Utility functions
31 //===----------------------------------------------------------------------===//
32 
33 namespace {
34 
35 // Helper function that returns true if the decl passed in the argument is
36 // a defintion in dependent contxt.
37 template <typename DT> bool isDefinitionInDependentContext(DT *D) {
38   return D->isDependentContext() && D->isThisDeclarationADefinition();
39 }
40 
41 } // namespace
42 
43 //===----------------------------------------------------------------------===//
44 // Declaration serialization
45 //===----------------------------------------------------------------------===//
46 
47 namespace clang {
48   class ASTDeclWriter : public DeclVisitor<ASTDeclWriter, void> {
49     ASTWriter &Writer;
50     ASTRecordWriter Record;
51 
52     serialization::DeclCode Code;
53     unsigned AbbrevToUse;
54 
55     bool GeneratingReducedBMI = false;
56 
57   public:
58     ASTDeclWriter(ASTWriter &Writer, ASTContext &Context,
59                   ASTWriter::RecordDataImpl &Record, bool GeneratingReducedBMI)
60         : Writer(Writer), Record(Context, Writer, Record),
61           Code((serialization::DeclCode)0), AbbrevToUse(0),
62           GeneratingReducedBMI(GeneratingReducedBMI) {}
63 
64     uint64_t Emit(Decl *D) {
65       if (!Code)
66         llvm::report_fatal_error(StringRef("unexpected declaration kind '") +
67             D->getDeclKindName() + "'");
68       return Record.Emit(Code, AbbrevToUse);
69     }
70 
71     void Visit(Decl *D);
72 
73     void VisitDecl(Decl *D);
74     void VisitPragmaCommentDecl(PragmaCommentDecl *D);
75     void VisitPragmaDetectMismatchDecl(PragmaDetectMismatchDecl *D);
76     void VisitTranslationUnitDecl(TranslationUnitDecl *D);
77     void VisitNamedDecl(NamedDecl *D);
78     void VisitLabelDecl(LabelDecl *LD);
79     void VisitNamespaceDecl(NamespaceDecl *D);
80     void VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
81     void VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
82     void VisitTypeDecl(TypeDecl *D);
83     void VisitTypedefNameDecl(TypedefNameDecl *D);
84     void VisitTypedefDecl(TypedefDecl *D);
85     void VisitTypeAliasDecl(TypeAliasDecl *D);
86     void VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
87     void VisitUnresolvedUsingIfExistsDecl(UnresolvedUsingIfExistsDecl *D);
88     void VisitTagDecl(TagDecl *D);
89     void VisitEnumDecl(EnumDecl *D);
90     void VisitRecordDecl(RecordDecl *D);
91     void VisitCXXRecordDecl(CXXRecordDecl *D);
92     void VisitClassTemplateSpecializationDecl(
93                                             ClassTemplateSpecializationDecl *D);
94     void VisitClassTemplatePartialSpecializationDecl(
95                                      ClassTemplatePartialSpecializationDecl *D);
96     void VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D);
97     void VisitVarTemplatePartialSpecializationDecl(
98         VarTemplatePartialSpecializationDecl *D);
99     void VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
100     void VisitValueDecl(ValueDecl *D);
101     void VisitEnumConstantDecl(EnumConstantDecl *D);
102     void VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
103     void VisitDeclaratorDecl(DeclaratorDecl *D);
104     void VisitFunctionDecl(FunctionDecl *D);
105     void VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D);
106     void VisitCXXMethodDecl(CXXMethodDecl *D);
107     void VisitCXXConstructorDecl(CXXConstructorDecl *D);
108     void VisitCXXDestructorDecl(CXXDestructorDecl *D);
109     void VisitCXXConversionDecl(CXXConversionDecl *D);
110     void VisitFieldDecl(FieldDecl *D);
111     void VisitMSPropertyDecl(MSPropertyDecl *D);
112     void VisitMSGuidDecl(MSGuidDecl *D);
113     void VisitUnnamedGlobalConstantDecl(UnnamedGlobalConstantDecl *D);
114     void VisitTemplateParamObjectDecl(TemplateParamObjectDecl *D);
115     void VisitIndirectFieldDecl(IndirectFieldDecl *D);
116     void VisitVarDecl(VarDecl *D);
117     void VisitImplicitParamDecl(ImplicitParamDecl *D);
118     void VisitParmVarDecl(ParmVarDecl *D);
119     void VisitDecompositionDecl(DecompositionDecl *D);
120     void VisitBindingDecl(BindingDecl *D);
121     void VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
122     void VisitTemplateDecl(TemplateDecl *D);
123     void VisitConceptDecl(ConceptDecl *D);
124     void VisitImplicitConceptSpecializationDecl(
125         ImplicitConceptSpecializationDecl *D);
126     void VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D);
127     void VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D);
128     void VisitClassTemplateDecl(ClassTemplateDecl *D);
129     void VisitVarTemplateDecl(VarTemplateDecl *D);
130     void VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
131     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
132     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
133     void VisitUsingDecl(UsingDecl *D);
134     void VisitUsingEnumDecl(UsingEnumDecl *D);
135     void VisitUsingPackDecl(UsingPackDecl *D);
136     void VisitUsingShadowDecl(UsingShadowDecl *D);
137     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
138     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
139     void VisitExportDecl(ExportDecl *D);
140     void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
141     void VisitTopLevelStmtDecl(TopLevelStmtDecl *D);
142     void VisitImportDecl(ImportDecl *D);
143     void VisitAccessSpecDecl(AccessSpecDecl *D);
144     void VisitFriendDecl(FriendDecl *D);
145     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
146     void VisitStaticAssertDecl(StaticAssertDecl *D);
147     void VisitBlockDecl(BlockDecl *D);
148     void VisitOutlinedFunctionDecl(OutlinedFunctionDecl *D);
149     void VisitCapturedDecl(CapturedDecl *D);
150     void VisitEmptyDecl(EmptyDecl *D);
151     void VisitLifetimeExtendedTemporaryDecl(LifetimeExtendedTemporaryDecl *D);
152     void VisitDeclContext(DeclContext *DC);
153     template <typename T> void VisitRedeclarable(Redeclarable<T> *D);
154     void VisitHLSLBufferDecl(HLSLBufferDecl *D);
155 
156     // FIXME: Put in the same order is DeclNodes.td?
157     void VisitObjCMethodDecl(ObjCMethodDecl *D);
158     void VisitObjCTypeParamDecl(ObjCTypeParamDecl *D);
159     void VisitObjCContainerDecl(ObjCContainerDecl *D);
160     void VisitObjCInterfaceDecl(ObjCInterfaceDecl *D);
161     void VisitObjCIvarDecl(ObjCIvarDecl *D);
162     void VisitObjCProtocolDecl(ObjCProtocolDecl *D);
163     void VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D);
164     void VisitObjCCategoryDecl(ObjCCategoryDecl *D);
165     void VisitObjCImplDecl(ObjCImplDecl *D);
166     void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D);
167     void VisitObjCImplementationDecl(ObjCImplementationDecl *D);
168     void VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D);
169     void VisitObjCPropertyDecl(ObjCPropertyDecl *D);
170     void VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D);
171     void VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D);
172     void VisitOMPAllocateDecl(OMPAllocateDecl *D);
173     void VisitOMPRequiresDecl(OMPRequiresDecl *D);
174     void VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D);
175     void VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D);
176     void VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D);
177 
178     void VisitOpenACCDeclareDecl(OpenACCDeclareDecl *D);
179     void VisitOpenACCRoutineDecl(OpenACCRoutineDecl *D);
180 
181     /// Add an Objective-C type parameter list to the given record.
182     void AddObjCTypeParamList(ObjCTypeParamList *typeParams) {
183       // Empty type parameter list.
184       if (!typeParams) {
185         Record.push_back(0);
186         return;
187       }
188 
189       Record.push_back(typeParams->size());
190       for (auto *typeParam : *typeParams) {
191         Record.AddDeclRef(typeParam);
192       }
193       Record.AddSourceLocation(typeParams->getLAngleLoc());
194       Record.AddSourceLocation(typeParams->getRAngleLoc());
195     }
196 
197     /// Collect the first declaration from each module file that provides a
198     /// declaration of D.
199     void CollectFirstDeclFromEachModule(
200         const Decl *D, bool IncludeLocal,
201         llvm::MapVector<ModuleFile *, const Decl *> &Firsts) {
202 
203       // FIXME: We can skip entries that we know are implied by others.
204       for (const Decl *R = D->getMostRecentDecl(); R; R = R->getPreviousDecl()) {
205         if (R->isFromASTFile())
206           Firsts[Writer.Chain->getOwningModuleFile(R)] = R;
207         else if (IncludeLocal)
208           Firsts[nullptr] = R;
209       }
210     }
211 
212     /// Add to the record the first declaration from each module file that
213     /// provides a declaration of D. The intent is to provide a sufficient
214     /// set such that reloading this set will load all current redeclarations.
215     void AddFirstDeclFromEachModule(const Decl *D, bool IncludeLocal) {
216       llvm::MapVector<ModuleFile *, const Decl *> Firsts;
217       CollectFirstDeclFromEachModule(D, IncludeLocal, Firsts);
218 
219       for (const auto &F : Firsts)
220         Record.AddDeclRef(F.second);
221     }
222 
223     template <typename T> bool shouldSkipWritingSpecializations(T *Spec) {
224       // Now we will only avoid writing specializations if we're generating
225       // reduced BMI.
226       if (!GeneratingReducedBMI)
227         return false;
228 
229       assert((isa<FunctionDecl, ClassTemplateSpecializationDecl,
230                   VarTemplateSpecializationDecl>(Spec)));
231 
232       ArrayRef<TemplateArgument> Args;
233       if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(Spec))
234         Args = CTSD->getTemplateArgs().asArray();
235       else if (auto *VTSD = dyn_cast<VarTemplateSpecializationDecl>(Spec))
236         Args = VTSD->getTemplateArgs().asArray();
237       else
238         Args = cast<FunctionDecl>(Spec)
239                    ->getTemplateSpecializationArgs()
240                    ->asArray();
241 
242       // If there is any template argument is TULocal, we can avoid writing the
243       // specialization since the consumers of reduced BMI won't get the
244       // specialization anyway.
245       for (const TemplateArgument &TA : Args) {
246         switch (TA.getKind()) {
247         case TemplateArgument::Type: {
248           Linkage L = TA.getAsType()->getLinkage();
249           if (!isExternallyVisible(L))
250             return true;
251           break;
252         }
253         case TemplateArgument::Declaration:
254           if (!TA.getAsDecl()->isExternallyVisible())
255             return true;
256           break;
257         default:
258           break;
259         }
260       }
261 
262       return false;
263     }
264 
265     /// Add to the record the first template specialization from each module
266     /// file that provides a declaration of D. We store the DeclId and an
267     /// ODRHash of the template arguments of D which should provide enough
268     /// information to load D only if the template instantiator needs it.
269     void AddFirstSpecializationDeclFromEachModule(
270         const Decl *D, llvm::SmallVectorImpl<const Decl *> &SpecsInMap,
271         llvm::SmallVectorImpl<const Decl *> &PartialSpecsInMap) {
272       assert((isa<ClassTemplateSpecializationDecl>(D) ||
273               isa<VarTemplateSpecializationDecl>(D) || isa<FunctionDecl>(D)) &&
274              "Must not be called with other decls");
275       llvm::MapVector<ModuleFile *, const Decl *> Firsts;
276       CollectFirstDeclFromEachModule(D, /*IncludeLocal*/ true, Firsts);
277 
278       for (const auto &F : Firsts) {
279         if (shouldSkipWritingSpecializations(F.second))
280           continue;
281 
282         if (isa<ClassTemplatePartialSpecializationDecl,
283                 VarTemplatePartialSpecializationDecl>(F.second))
284           PartialSpecsInMap.push_back(F.second);
285         else
286           SpecsInMap.push_back(F.second);
287       }
288     }
289 
290     /// Get the specialization decl from an entry in the specialization list.
291     template <typename EntryType>
292     typename RedeclarableTemplateDecl::SpecEntryTraits<EntryType>::DeclType *
293     getSpecializationDecl(EntryType &T) {
294       return RedeclarableTemplateDecl::SpecEntryTraits<EntryType>::getDecl(&T);
295     }
296 
297     /// Get the list of partial specializations from a template's common ptr.
298     template<typename T>
299     decltype(T::PartialSpecializations) &getPartialSpecializations(T *Common) {
300       return Common->PartialSpecializations;
301     }
302     MutableArrayRef<FunctionTemplateSpecializationInfo>
303     getPartialSpecializations(FunctionTemplateDecl::Common *) {
304       return {};
305     }
306 
307     template<typename DeclTy>
308     void AddTemplateSpecializations(DeclTy *D) {
309       auto *Common = D->getCommonPtr();
310 
311       // If we have any lazy specializations, and the external AST source is
312       // our chained AST reader, we can just write out the DeclIDs. Otherwise,
313       // we need to resolve them to actual declarations.
314       if (Writer.Chain != Record.getASTContext().getExternalSource() &&
315           Writer.Chain && Writer.Chain->haveUnloadedSpecializations(D)) {
316         D->LoadLazySpecializations();
317         assert(!Writer.Chain->haveUnloadedSpecializations(D));
318       }
319 
320       // AddFirstSpecializationDeclFromEachModule might trigger deserialization,
321       // invalidating *Specializations iterators.
322       llvm::SmallVector<const Decl *, 16> AllSpecs;
323       for (auto &Entry : Common->Specializations)
324         AllSpecs.push_back(getSpecializationDecl(Entry));
325       for (auto &Entry : getPartialSpecializations(Common))
326         AllSpecs.push_back(getSpecializationDecl(Entry));
327 
328       llvm::SmallVector<const Decl *, 16> Specs;
329       llvm::SmallVector<const Decl *, 16> PartialSpecs;
330       for (auto *D : AllSpecs) {
331         assert(D->isCanonicalDecl() && "non-canonical decl in set");
332         AddFirstSpecializationDeclFromEachModule(D, Specs, PartialSpecs);
333       }
334 
335       Record.AddOffset(Writer.WriteSpecializationInfoLookupTable(
336           D, Specs, /*IsPartial=*/false));
337 
338       // Function Template Decl doesn't have partial decls.
339       if (isa<FunctionTemplateDecl>(D)) {
340         assert(PartialSpecs.empty());
341         return;
342       }
343 
344       Record.AddOffset(Writer.WriteSpecializationInfoLookupTable(
345           D, PartialSpecs, /*IsPartial=*/true));
346     }
347 
348     /// Ensure that this template specialization is associated with the specified
349     /// template on reload.
350     void RegisterTemplateSpecialization(const Decl *Template,
351                                         const Decl *Specialization) {
352       Template = Template->getCanonicalDecl();
353 
354       // If the canonical template is local, we'll write out this specialization
355       // when we emit it.
356       // FIXME: We can do the same thing if there is any local declaration of
357       // the template, to avoid emitting an update record.
358       if (!Template->isFromASTFile())
359         return;
360 
361       // We only need to associate the first local declaration of the
362       // specialization. The other declarations will get pulled in by it.
363       if (Writer.getFirstLocalDecl(Specialization) != Specialization)
364         return;
365 
366       if (isa<ClassTemplatePartialSpecializationDecl,
367               VarTemplatePartialSpecializationDecl>(Specialization))
368         Writer.PartialSpecializationsUpdates[cast<NamedDecl>(Template)]
369             .push_back(cast<NamedDecl>(Specialization));
370       else
371         Writer.SpecializationsUpdates[cast<NamedDecl>(Template)].push_back(
372             cast<NamedDecl>(Specialization));
373     }
374   };
375 }
376 
377 // When building a C++20 module interface unit or a partition unit, a
378 // strong definition in the module interface is provided by the
379 // compilation of that unit, not by its users. (Inline variables are still
380 // emitted in module users.)
381 static bool shouldVarGenerateHereOnly(const VarDecl *VD) {
382   if (VD->getStorageDuration() != SD_Static)
383     return false;
384 
385   if (VD->getDescribedVarTemplate())
386     return false;
387 
388   Module *M = VD->getOwningModule();
389   if (!M)
390     return false;
391 
392   M = M->getTopLevelModule();
393   ASTContext &Ctx = VD->getASTContext();
394   if (!M->isInterfaceOrPartition() &&
395       (!VD->hasAttr<DLLExportAttr>() ||
396        !Ctx.getLangOpts().BuildingPCHWithObjectFile))
397     return false;
398 
399   return Ctx.GetGVALinkageForVariable(VD) >= GVA_StrongExternal;
400 }
401 
402 static bool shouldFunctionGenerateHereOnly(const FunctionDecl *FD) {
403   if (FD->isDependentContext())
404     return false;
405 
406   ASTContext &Ctx = FD->getASTContext();
407   auto Linkage = Ctx.GetGVALinkageForFunction(FD);
408   if (Ctx.getLangOpts().ModulesCodegen ||
409       (FD->hasAttr<DLLExportAttr>() &&
410        Ctx.getLangOpts().BuildingPCHWithObjectFile))
411     // Under -fmodules-codegen, codegen is performed for all non-internal,
412     // non-always_inline functions, unless they are available elsewhere.
413     if (!FD->hasAttr<AlwaysInlineAttr>() && Linkage != GVA_Internal &&
414         Linkage != GVA_AvailableExternally)
415       return true;
416 
417   Module *M = FD->getOwningModule();
418   if (!M)
419     return false;
420 
421   M = M->getTopLevelModule();
422   if (M->isInterfaceOrPartition())
423     if (Linkage >= GVA_StrongExternal)
424       return true;
425 
426   return false;
427 }
428 
429 bool clang::CanElideDeclDef(const Decl *D) {
430   if (auto *FD = dyn_cast<FunctionDecl>(D)) {
431     if (FD->isInlined() || FD->isConstexpr() || FD->isConsteval())
432       return false;
433 
434     // If the function should be generated somewhere else, we shouldn't elide
435     // it.
436     if (!shouldFunctionGenerateHereOnly(FD))
437       return false;
438   }
439 
440   if (auto *VD = dyn_cast<VarDecl>(D)) {
441     if (VD->getDeclContext()->isDependentContext())
442       return false;
443 
444     // Constant initialized variable may not affect the ABI, but they
445     // may be used in constant evaluation in the frontend, so we have
446     // to remain them.
447     if (VD->hasConstantInitialization() || VD->isConstexpr())
448       return false;
449 
450     // If the variable should be generated somewhere else, we shouldn't elide
451     // it.
452     if (!shouldVarGenerateHereOnly(VD))
453       return false;
454   }
455 
456   return true;
457 }
458 
459 void ASTDeclWriter::Visit(Decl *D) {
460   DeclVisitor<ASTDeclWriter>::Visit(D);
461 
462   // Source locations require array (variable-length) abbreviations.  The
463   // abbreviation infrastructure requires that arrays are encoded last, so
464   // we handle it here in the case of those classes derived from DeclaratorDecl
465   if (auto *DD = dyn_cast<DeclaratorDecl>(D)) {
466     if (auto *TInfo = DD->getTypeSourceInfo())
467       Record.AddTypeLoc(TInfo->getTypeLoc());
468   }
469 
470   // Handle FunctionDecl's body here and write it after all other Stmts/Exprs
471   // have been written. We want it last because we will not read it back when
472   // retrieving it from the AST, we'll just lazily set the offset.
473   if (auto *FD = dyn_cast<FunctionDecl>(D)) {
474     if (!GeneratingReducedBMI || !CanElideDeclDef(FD)) {
475       Record.push_back(FD->doesThisDeclarationHaveABody());
476       if (FD->doesThisDeclarationHaveABody())
477         Record.AddFunctionDefinition(FD);
478     } else
479       Record.push_back(0);
480   }
481 
482   // Similar to FunctionDecls, handle VarDecl's initializer here and write it
483   // after all other Stmts/Exprs. We will not read the initializer until after
484   // we have finished recursive deserialization, because it can recursively
485   // refer back to the variable.
486   if (auto *VD = dyn_cast<VarDecl>(D)) {
487     if (!GeneratingReducedBMI || !CanElideDeclDef(VD))
488       Record.AddVarDeclInit(VD);
489     else
490       Record.push_back(0);
491   }
492 
493   // And similarly for FieldDecls. We already serialized whether there is a
494   // default member initializer.
495   if (auto *FD = dyn_cast<FieldDecl>(D)) {
496     if (FD->hasInClassInitializer()) {
497       if (Expr *Init = FD->getInClassInitializer()) {
498         Record.push_back(1);
499         Record.AddStmt(Init);
500       } else {
501         Record.push_back(0);
502         // Initializer has not been instantiated yet.
503       }
504     }
505   }
506 
507   // If this declaration is also a DeclContext, write blocks for the
508   // declarations that lexically stored inside its context and those
509   // declarations that are visible from its context.
510   if (auto *DC = dyn_cast<DeclContext>(D))
511     VisitDeclContext(DC);
512 }
513 
514 void ASTDeclWriter::VisitDecl(Decl *D) {
515   BitsPacker DeclBits;
516 
517   // The order matters here. It will be better to put the bit with higher
518   // probability to be 0 in the end of the bits.
519   //
520   // Since we're using VBR6 format to store it.
521   // It will be pretty effient if all the higher bits are 0.
522   // For example, if we need to pack 8 bits into a value and the stored value
523   // is 0xf0, the actual stored value will be 0b000111'110000, which takes 12
524   // bits actually. However, if we changed the order to be 0x0f, then we can
525   // store it as 0b001111, which takes 6 bits only now.
526   DeclBits.addBits((uint64_t)D->getModuleOwnershipKind(), /*BitWidth=*/3);
527   DeclBits.addBit(D->isReferenced());
528   DeclBits.addBit(D->isUsed(false));
529   DeclBits.addBits(D->getAccess(), /*BitWidth=*/2);
530   DeclBits.addBit(D->isImplicit());
531   DeclBits.addBit(D->getDeclContext() != D->getLexicalDeclContext());
532   DeclBits.addBit(D->hasAttrs());
533   DeclBits.addBit(D->isTopLevelDeclInObjCContainer());
534   DeclBits.addBit(D->isInvalidDecl());
535   Record.push_back(DeclBits);
536 
537   Record.AddDeclRef(cast_or_null<Decl>(D->getDeclContext()));
538   if (D->getDeclContext() != D->getLexicalDeclContext())
539     Record.AddDeclRef(cast_or_null<Decl>(D->getLexicalDeclContext()));
540 
541   if (D->hasAttrs())
542     Record.AddAttributes(D->getAttrs());
543 
544   Record.push_back(Writer.getSubmoduleID(D->getOwningModule()));
545 
546   // If this declaration injected a name into a context different from its
547   // lexical context, and that context is an imported namespace, we need to
548   // update its visible declarations to include this name.
549   //
550   // This happens when we instantiate a class with a friend declaration or a
551   // function with a local extern declaration, for instance.
552   //
553   // FIXME: Can we handle this in AddedVisibleDecl instead?
554   if (D->isOutOfLine()) {
555     auto *DC = D->getDeclContext();
556     while (auto *NS = dyn_cast<NamespaceDecl>(DC->getRedeclContext())) {
557       if (!NS->isFromASTFile())
558         break;
559       Writer.UpdatedDeclContexts.insert(NS->getPrimaryContext());
560       if (!NS->isInlineNamespace())
561         break;
562       DC = NS->getParent();
563     }
564   }
565 }
566 
567 void ASTDeclWriter::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
568   StringRef Arg = D->getArg();
569   Record.push_back(Arg.size());
570   VisitDecl(D);
571   Record.AddSourceLocation(D->getBeginLoc());
572   Record.push_back(D->getCommentKind());
573   Record.AddString(Arg);
574   Code = serialization::DECL_PRAGMA_COMMENT;
575 }
576 
577 void ASTDeclWriter::VisitPragmaDetectMismatchDecl(
578     PragmaDetectMismatchDecl *D) {
579   StringRef Name = D->getName();
580   StringRef Value = D->getValue();
581   Record.push_back(Name.size() + 1 + Value.size());
582   VisitDecl(D);
583   Record.AddSourceLocation(D->getBeginLoc());
584   Record.AddString(Name);
585   Record.AddString(Value);
586   Code = serialization::DECL_PRAGMA_DETECT_MISMATCH;
587 }
588 
589 void ASTDeclWriter::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
590   llvm_unreachable("Translation units aren't directly serialized");
591 }
592 
593 void ASTDeclWriter::VisitNamedDecl(NamedDecl *D) {
594   VisitDecl(D);
595   Record.AddDeclarationName(D->getDeclName());
596   Record.push_back(needsAnonymousDeclarationNumber(D)
597                        ? Writer.getAnonymousDeclarationNumber(D)
598                        : 0);
599 }
600 
601 void ASTDeclWriter::VisitTypeDecl(TypeDecl *D) {
602   VisitNamedDecl(D);
603   Record.AddSourceLocation(D->getBeginLoc());
604   Record.AddTypeRef(QualType(D->getTypeForDecl(), 0));
605 }
606 
607 void ASTDeclWriter::VisitTypedefNameDecl(TypedefNameDecl *D) {
608   VisitRedeclarable(D);
609   VisitTypeDecl(D);
610   Record.AddTypeSourceInfo(D->getTypeSourceInfo());
611   Record.push_back(D->isModed());
612   if (D->isModed())
613     Record.AddTypeRef(D->getUnderlyingType());
614   Record.AddDeclRef(D->getAnonDeclWithTypedefName(false));
615 }
616 
617 void ASTDeclWriter::VisitTypedefDecl(TypedefDecl *D) {
618   VisitTypedefNameDecl(D);
619   if (D->getDeclContext() == D->getLexicalDeclContext() &&
620       !D->hasAttrs() &&
621       !D->isImplicit() &&
622       D->getFirstDecl() == D->getMostRecentDecl() &&
623       !D->isInvalidDecl() &&
624       !D->isTopLevelDeclInObjCContainer() &&
625       !D->isModulePrivate() &&
626       !needsAnonymousDeclarationNumber(D) &&
627       D->getDeclName().getNameKind() == DeclarationName::Identifier)
628     AbbrevToUse = Writer.getDeclTypedefAbbrev();
629 
630   Code = serialization::DECL_TYPEDEF;
631 }
632 
633 void ASTDeclWriter::VisitTypeAliasDecl(TypeAliasDecl *D) {
634   VisitTypedefNameDecl(D);
635   Record.AddDeclRef(D->getDescribedAliasTemplate());
636   Code = serialization::DECL_TYPEALIAS;
637 }
638 
639 void ASTDeclWriter::VisitTagDecl(TagDecl *D) {
640   static_assert(DeclContext::NumTagDeclBits == 23,
641                 "You need to update the serializer after you change the "
642                 "TagDeclBits");
643 
644   VisitRedeclarable(D);
645   VisitTypeDecl(D);
646   Record.push_back(D->getIdentifierNamespace());
647 
648   BitsPacker TagDeclBits;
649   TagDeclBits.addBits(llvm::to_underlying(D->getTagKind()), /*BitWidth=*/3);
650   TagDeclBits.addBit(!isa<CXXRecordDecl>(D) ? D->isCompleteDefinition() : 0);
651   TagDeclBits.addBit(D->isEmbeddedInDeclarator());
652   TagDeclBits.addBit(D->isFreeStanding());
653   TagDeclBits.addBit(D->isCompleteDefinitionRequired());
654   TagDeclBits.addBits(
655       D->hasExtInfo() ? 1 : (D->getTypedefNameForAnonDecl() ? 2 : 0),
656       /*BitWidth=*/2);
657   Record.push_back(TagDeclBits);
658 
659   Record.AddSourceRange(D->getBraceRange());
660 
661   if (D->hasExtInfo()) {
662     Record.AddQualifierInfo(*D->getExtInfo());
663   } else if (auto *TD = D->getTypedefNameForAnonDecl()) {
664     Record.AddDeclRef(TD);
665     Record.AddIdentifierRef(TD->getDeclName().getAsIdentifierInfo());
666   }
667 }
668 
669 void ASTDeclWriter::VisitEnumDecl(EnumDecl *D) {
670   static_assert(DeclContext::NumEnumDeclBits == 43,
671                 "You need to update the serializer after you change the "
672                 "EnumDeclBits");
673 
674   VisitTagDecl(D);
675   Record.AddTypeSourceInfo(D->getIntegerTypeSourceInfo());
676   if (!D->getIntegerTypeSourceInfo())
677     Record.AddTypeRef(D->getIntegerType());
678   Record.AddTypeRef(D->getPromotionType());
679 
680   BitsPacker EnumDeclBits;
681   EnumDeclBits.addBits(D->getNumPositiveBits(), /*BitWidth=*/8);
682   EnumDeclBits.addBits(D->getNumNegativeBits(), /*BitWidth=*/8);
683   EnumDeclBits.addBit(D->isScoped());
684   EnumDeclBits.addBit(D->isScopedUsingClassTag());
685   EnumDeclBits.addBit(D->isFixed());
686   Record.push_back(EnumDeclBits);
687 
688   Record.push_back(D->getODRHash());
689 
690   if (MemberSpecializationInfo *MemberInfo = D->getMemberSpecializationInfo()) {
691     Record.AddDeclRef(MemberInfo->getInstantiatedFrom());
692     Record.push_back(MemberInfo->getTemplateSpecializationKind());
693     Record.AddSourceLocation(MemberInfo->getPointOfInstantiation());
694   } else {
695     Record.AddDeclRef(nullptr);
696   }
697 
698   if (D->getDeclContext() == D->getLexicalDeclContext() && !D->hasAttrs() &&
699       !D->isInvalidDecl() && !D->isImplicit() && !D->hasExtInfo() &&
700       !D->getTypedefNameForAnonDecl() &&
701       D->getFirstDecl() == D->getMostRecentDecl() &&
702       !D->isTopLevelDeclInObjCContainer() &&
703       !CXXRecordDecl::classofKind(D->getKind()) &&
704       !D->getIntegerTypeSourceInfo() && !D->getMemberSpecializationInfo() &&
705       !needsAnonymousDeclarationNumber(D) &&
706       D->getDeclName().getNameKind() == DeclarationName::Identifier)
707     AbbrevToUse = Writer.getDeclEnumAbbrev();
708 
709   Code = serialization::DECL_ENUM;
710 }
711 
712 void ASTDeclWriter::VisitRecordDecl(RecordDecl *D) {
713   static_assert(DeclContext::NumRecordDeclBits == 64,
714                 "You need to update the serializer after you change the "
715                 "RecordDeclBits");
716 
717   VisitTagDecl(D);
718 
719   BitsPacker RecordDeclBits;
720   RecordDeclBits.addBit(D->hasFlexibleArrayMember());
721   RecordDeclBits.addBit(D->isAnonymousStructOrUnion());
722   RecordDeclBits.addBit(D->hasObjectMember());
723   RecordDeclBits.addBit(D->hasVolatileMember());
724   RecordDeclBits.addBit(D->isNonTrivialToPrimitiveDefaultInitialize());
725   RecordDeclBits.addBit(D->isNonTrivialToPrimitiveCopy());
726   RecordDeclBits.addBit(D->isNonTrivialToPrimitiveDestroy());
727   RecordDeclBits.addBit(D->hasNonTrivialToPrimitiveDefaultInitializeCUnion());
728   RecordDeclBits.addBit(D->hasNonTrivialToPrimitiveDestructCUnion());
729   RecordDeclBits.addBit(D->hasNonTrivialToPrimitiveCopyCUnion());
730   RecordDeclBits.addBit(D->hasUninitializedExplicitInitFields());
731   RecordDeclBits.addBit(D->isParamDestroyedInCallee());
732   RecordDeclBits.addBits(llvm::to_underlying(D->getArgPassingRestrictions()), 2);
733   Record.push_back(RecordDeclBits);
734 
735   // Only compute this for C/Objective-C, in C++ this is computed as part
736   // of CXXRecordDecl.
737   if (!isa<CXXRecordDecl>(D))
738     Record.push_back(D->getODRHash());
739 
740   if (D->getDeclContext() == D->getLexicalDeclContext() && !D->hasAttrs() &&
741       !D->isImplicit() && !D->isInvalidDecl() && !D->hasExtInfo() &&
742       !D->getTypedefNameForAnonDecl() &&
743       D->getFirstDecl() == D->getMostRecentDecl() &&
744       !D->isTopLevelDeclInObjCContainer() &&
745       !CXXRecordDecl::classofKind(D->getKind()) &&
746       !needsAnonymousDeclarationNumber(D) &&
747       D->getDeclName().getNameKind() == DeclarationName::Identifier)
748     AbbrevToUse = Writer.getDeclRecordAbbrev();
749 
750   Code = serialization::DECL_RECORD;
751 }
752 
753 void ASTDeclWriter::VisitValueDecl(ValueDecl *D) {
754   VisitNamedDecl(D);
755   Record.AddTypeRef(D->getType());
756 }
757 
758 void ASTDeclWriter::VisitEnumConstantDecl(EnumConstantDecl *D) {
759   VisitValueDecl(D);
760   Record.push_back(D->getInitExpr()? 1 : 0);
761   if (D->getInitExpr())
762     Record.AddStmt(D->getInitExpr());
763   Record.AddAPSInt(D->getInitVal());
764 
765   Code = serialization::DECL_ENUM_CONSTANT;
766 }
767 
768 void ASTDeclWriter::VisitDeclaratorDecl(DeclaratorDecl *D) {
769   VisitValueDecl(D);
770   Record.AddSourceLocation(D->getInnerLocStart());
771   Record.push_back(D->hasExtInfo());
772   if (D->hasExtInfo()) {
773     DeclaratorDecl::ExtInfo *Info = D->getExtInfo();
774     Record.AddQualifierInfo(*Info);
775     Record.AddStmt(
776         const_cast<Expr *>(Info->TrailingRequiresClause.ConstraintExpr));
777     Record.writeUnsignedOrNone(Info->TrailingRequiresClause.ArgPackSubstIndex);
778   }
779   // The location information is deferred until the end of the record.
780   Record.AddTypeRef(D->getTypeSourceInfo() ? D->getTypeSourceInfo()->getType()
781                                            : QualType());
782 }
783 
784 void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
785   static_assert(DeclContext::NumFunctionDeclBits == 45,
786                 "You need to update the serializer after you change the "
787                 "FunctionDeclBits");
788 
789   VisitRedeclarable(D);
790 
791   Record.push_back(D->getTemplatedKind());
792   switch (D->getTemplatedKind()) {
793   case FunctionDecl::TK_NonTemplate:
794     break;
795   case FunctionDecl::TK_DependentNonTemplate:
796     Record.AddDeclRef(D->getInstantiatedFromDecl());
797     break;
798   case FunctionDecl::TK_FunctionTemplate:
799     Record.AddDeclRef(D->getDescribedFunctionTemplate());
800     break;
801   case FunctionDecl::TK_MemberSpecialization: {
802     MemberSpecializationInfo *MemberInfo = D->getMemberSpecializationInfo();
803     Record.AddDeclRef(MemberInfo->getInstantiatedFrom());
804     Record.push_back(MemberInfo->getTemplateSpecializationKind());
805     Record.AddSourceLocation(MemberInfo->getPointOfInstantiation());
806     break;
807   }
808   case FunctionDecl::TK_FunctionTemplateSpecialization: {
809     FunctionTemplateSpecializationInfo *
810       FTSInfo = D->getTemplateSpecializationInfo();
811 
812     RegisterTemplateSpecialization(FTSInfo->getTemplate(), D);
813 
814     Record.AddDeclRef(FTSInfo->getTemplate());
815     Record.push_back(FTSInfo->getTemplateSpecializationKind());
816 
817     // Template arguments.
818     Record.AddTemplateArgumentList(FTSInfo->TemplateArguments);
819 
820     // Template args as written.
821     Record.push_back(FTSInfo->TemplateArgumentsAsWritten != nullptr);
822     if (FTSInfo->TemplateArgumentsAsWritten)
823       Record.AddASTTemplateArgumentListInfo(
824           FTSInfo->TemplateArgumentsAsWritten);
825 
826     Record.AddSourceLocation(FTSInfo->getPointOfInstantiation());
827 
828     if (MemberSpecializationInfo *MemberInfo =
829         FTSInfo->getMemberSpecializationInfo()) {
830       Record.push_back(1);
831       Record.AddDeclRef(MemberInfo->getInstantiatedFrom());
832       Record.push_back(MemberInfo->getTemplateSpecializationKind());
833       Record.AddSourceLocation(MemberInfo->getPointOfInstantiation());
834     } else {
835       Record.push_back(0);
836     }
837 
838     if (D->isCanonicalDecl()) {
839       // Write the template that contains the specializations set. We will
840       // add a FunctionTemplateSpecializationInfo to it when reading.
841       Record.AddDeclRef(FTSInfo->getTemplate()->getCanonicalDecl());
842     }
843     break;
844   }
845   case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {
846     DependentFunctionTemplateSpecializationInfo *
847       DFTSInfo = D->getDependentSpecializationInfo();
848 
849     // Candidates.
850     Record.push_back(DFTSInfo->getCandidates().size());
851     for (FunctionTemplateDecl *FTD : DFTSInfo->getCandidates())
852       Record.AddDeclRef(FTD);
853 
854     // Templates args.
855     Record.push_back(DFTSInfo->TemplateArgumentsAsWritten != nullptr);
856     if (DFTSInfo->TemplateArgumentsAsWritten)
857       Record.AddASTTemplateArgumentListInfo(
858           DFTSInfo->TemplateArgumentsAsWritten);
859     break;
860   }
861   }
862 
863   VisitDeclaratorDecl(D);
864   Record.AddDeclarationNameLoc(D->DNLoc, D->getDeclName());
865   Record.push_back(D->getIdentifierNamespace());
866 
867   // The order matters here. It will be better to put the bit with higher
868   // probability to be 0 in the end of the bits. See the comments in VisitDecl
869   // for details.
870   BitsPacker FunctionDeclBits;
871   // FIXME: stable encoding
872   FunctionDeclBits.addBits(llvm::to_underlying(D->getLinkageInternal()), 3);
873   FunctionDeclBits.addBits((uint32_t)D->getStorageClass(), /*BitWidth=*/3);
874   FunctionDeclBits.addBit(D->isInlineSpecified());
875   FunctionDeclBits.addBit(D->isInlined());
876   FunctionDeclBits.addBit(D->hasSkippedBody());
877   FunctionDeclBits.addBit(D->isVirtualAsWritten());
878   FunctionDeclBits.addBit(D->isPureVirtual());
879   FunctionDeclBits.addBit(D->hasInheritedPrototype());
880   FunctionDeclBits.addBit(D->hasWrittenPrototype());
881   FunctionDeclBits.addBit(D->isDeletedBit());
882   FunctionDeclBits.addBit(D->isTrivial());
883   FunctionDeclBits.addBit(D->isTrivialForCall());
884   FunctionDeclBits.addBit(D->isDefaulted());
885   FunctionDeclBits.addBit(D->isExplicitlyDefaulted());
886   FunctionDeclBits.addBit(D->isIneligibleOrNotSelected());
887   FunctionDeclBits.addBits((uint64_t)(D->getConstexprKind()), /*BitWidth=*/2);
888   FunctionDeclBits.addBit(D->hasImplicitReturnZero());
889   FunctionDeclBits.addBit(D->isMultiVersion());
890   FunctionDeclBits.addBit(D->isLateTemplateParsed());
891   FunctionDeclBits.addBit(D->isInstantiatedFromMemberTemplate());
892   FunctionDeclBits.addBit(D->FriendConstraintRefersToEnclosingTemplate());
893   FunctionDeclBits.addBit(D->usesSEHTry());
894   FunctionDeclBits.addBit(D->isDestroyingOperatorDelete());
895   FunctionDeclBits.addBit(D->isTypeAwareOperatorNewOrDelete());
896   Record.push_back(FunctionDeclBits);
897 
898   Record.AddSourceLocation(D->getEndLoc());
899   if (D->isExplicitlyDefaulted())
900     Record.AddSourceLocation(D->getDefaultLoc());
901 
902   Record.push_back(D->getODRHash());
903 
904   if (D->isDefaulted() || D->isDeletedAsWritten()) {
905     if (auto *FDI = D->getDefalutedOrDeletedInfo()) {
906       // Store both that there is an DefaultedOrDeletedInfo and whether it
907       // contains a DeletedMessage.
908       StringLiteral *DeletedMessage = FDI->getDeletedMessage();
909       Record.push_back(1 | (DeletedMessage ? 2 : 0));
910       if (DeletedMessage)
911         Record.AddStmt(DeletedMessage);
912 
913       Record.push_back(FDI->getUnqualifiedLookups().size());
914       for (DeclAccessPair P : FDI->getUnqualifiedLookups()) {
915         Record.AddDeclRef(P.getDecl());
916         Record.push_back(P.getAccess());
917       }
918     } else {
919       Record.push_back(0);
920     }
921   }
922 
923   if (D->getFriendObjectKind()) {
924     // For a friend function defined inline within a class template, we have to
925     // force the definition to be the one inside the definition of the template
926     // class. Remember this relation to deserialize them together.
927     if (auto *RD = dyn_cast<CXXRecordDecl>(D->getLexicalParent());
928         RD && isDefinitionInDependentContext(RD)) {
929       Writer.RelatedDeclsMap[Writer.GetDeclRef(RD)].push_back(
930           Writer.GetDeclRef(D));
931     }
932   }
933 
934   Record.push_back(D->param_size());
935   for (auto *P : D->parameters())
936     Record.AddDeclRef(P);
937   Code = serialization::DECL_FUNCTION;
938 }
939 
940 static void addExplicitSpecifier(ExplicitSpecifier ES,
941                                  ASTRecordWriter &Record) {
942   uint64_t Kind = static_cast<uint64_t>(ES.getKind());
943   Kind = Kind << 1 | static_cast<bool>(ES.getExpr());
944   Record.push_back(Kind);
945   if (ES.getExpr()) {
946     Record.AddStmt(ES.getExpr());
947   }
948 }
949 
950 void ASTDeclWriter::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
951   addExplicitSpecifier(D->getExplicitSpecifier(), Record);
952   Record.AddDeclRef(D->Ctor);
953   VisitFunctionDecl(D);
954   Record.push_back(static_cast<unsigned char>(D->getDeductionCandidateKind()));
955   Record.AddDeclRef(D->getSourceDeductionGuide());
956   Record.push_back(
957       static_cast<unsigned char>(D->getSourceDeductionGuideKind()));
958   Code = serialization::DECL_CXX_DEDUCTION_GUIDE;
959 }
960 
961 void ASTDeclWriter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
962   static_assert(DeclContext::NumObjCMethodDeclBits == 37,
963                 "You need to update the serializer after you change the "
964                 "ObjCMethodDeclBits");
965 
966   VisitNamedDecl(D);
967   // FIXME: convert to LazyStmtPtr?
968   // Unlike C/C++, method bodies will never be in header files.
969   bool HasBodyStuff = D->getBody() != nullptr;
970   Record.push_back(HasBodyStuff);
971   if (HasBodyStuff) {
972     Record.AddStmt(D->getBody());
973   }
974   Record.AddDeclRef(D->getSelfDecl());
975   Record.AddDeclRef(D->getCmdDecl());
976   Record.push_back(D->isInstanceMethod());
977   Record.push_back(D->isVariadic());
978   Record.push_back(D->isPropertyAccessor());
979   Record.push_back(D->isSynthesizedAccessorStub());
980   Record.push_back(D->isDefined());
981   Record.push_back(D->isOverriding());
982   Record.push_back(D->hasSkippedBody());
983 
984   Record.push_back(D->isRedeclaration());
985   Record.push_back(D->hasRedeclaration());
986   if (D->hasRedeclaration()) {
987     assert(Record.getASTContext().getObjCMethodRedeclaration(D));
988     Record.AddDeclRef(Record.getASTContext().getObjCMethodRedeclaration(D));
989   }
990 
991   // FIXME: stable encoding for @required/@optional
992   Record.push_back(llvm::to_underlying(D->getImplementationControl()));
993   // FIXME: stable encoding for in/out/inout/bycopy/byref/oneway/nullability
994   Record.push_back(D->getObjCDeclQualifier());
995   Record.push_back(D->hasRelatedResultType());
996   Record.AddTypeRef(D->getReturnType());
997   Record.AddTypeSourceInfo(D->getReturnTypeSourceInfo());
998   Record.AddSourceLocation(D->getEndLoc());
999   Record.push_back(D->param_size());
1000   for (const auto *P : D->parameters())
1001     Record.AddDeclRef(P);
1002 
1003   Record.push_back(D->getSelLocsKind());
1004   unsigned NumStoredSelLocs = D->getNumStoredSelLocs();
1005   SourceLocation *SelLocs = D->getStoredSelLocs();
1006   Record.push_back(NumStoredSelLocs);
1007   for (unsigned i = 0; i != NumStoredSelLocs; ++i)
1008     Record.AddSourceLocation(SelLocs[i]);
1009 
1010   Code = serialization::DECL_OBJC_METHOD;
1011 }
1012 
1013 void ASTDeclWriter::VisitObjCTypeParamDecl(ObjCTypeParamDecl *D) {
1014   VisitTypedefNameDecl(D);
1015   Record.push_back(D->Variance);
1016   Record.push_back(D->Index);
1017   Record.AddSourceLocation(D->VarianceLoc);
1018   Record.AddSourceLocation(D->ColonLoc);
1019 
1020   Code = serialization::DECL_OBJC_TYPE_PARAM;
1021 }
1022 
1023 void ASTDeclWriter::VisitObjCContainerDecl(ObjCContainerDecl *D) {
1024   static_assert(DeclContext::NumObjCContainerDeclBits == 64,
1025                 "You need to update the serializer after you change the "
1026                 "ObjCContainerDeclBits");
1027 
1028   VisitNamedDecl(D);
1029   Record.AddSourceLocation(D->getAtStartLoc());
1030   Record.AddSourceRange(D->getAtEndRange());
1031   // Abstract class (no need to define a stable serialization::DECL code).
1032 }
1033 
1034 void ASTDeclWriter::VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
1035   VisitRedeclarable(D);
1036   VisitObjCContainerDecl(D);
1037   Record.AddTypeRef(QualType(D->getTypeForDecl(), 0));
1038   AddObjCTypeParamList(D->TypeParamList);
1039 
1040   Record.push_back(D->isThisDeclarationADefinition());
1041   if (D->isThisDeclarationADefinition()) {
1042     // Write the DefinitionData
1043     ObjCInterfaceDecl::DefinitionData &Data = D->data();
1044 
1045     Record.AddTypeSourceInfo(D->getSuperClassTInfo());
1046     Record.AddSourceLocation(D->getEndOfDefinitionLoc());
1047     Record.push_back(Data.HasDesignatedInitializers);
1048     Record.push_back(D->getODRHash());
1049 
1050     // Write out the protocols that are directly referenced by the @interface.
1051     Record.push_back(Data.ReferencedProtocols.size());
1052     for (const auto *P : D->protocols())
1053       Record.AddDeclRef(P);
1054     for (const auto &PL : D->protocol_locs())
1055       Record.AddSourceLocation(PL);
1056 
1057     // Write out the protocols that are transitively referenced.
1058     Record.push_back(Data.AllReferencedProtocols.size());
1059     for (ObjCList<ObjCProtocolDecl>::iterator
1060               P = Data.AllReferencedProtocols.begin(),
1061            PEnd = Data.AllReferencedProtocols.end();
1062          P != PEnd; ++P)
1063       Record.AddDeclRef(*P);
1064 
1065 
1066     if (ObjCCategoryDecl *Cat = D->getCategoryListRaw()) {
1067       // Ensure that we write out the set of categories for this class.
1068       Writer.ObjCClassesWithCategories.insert(D);
1069 
1070       // Make sure that the categories get serialized.
1071       for (; Cat; Cat = Cat->getNextClassCategoryRaw())
1072         (void)Writer.GetDeclRef(Cat);
1073     }
1074   }
1075 
1076   Code = serialization::DECL_OBJC_INTERFACE;
1077 }
1078 
1079 void ASTDeclWriter::VisitObjCIvarDecl(ObjCIvarDecl *D) {
1080   VisitFieldDecl(D);
1081   // FIXME: stable encoding for @public/@private/@protected/@package
1082   Record.push_back(D->getAccessControl());
1083   Record.push_back(D->getSynthesize());
1084 
1085   if (D->getDeclContext() == D->getLexicalDeclContext() &&
1086       !D->hasAttrs() &&
1087       !D->isImplicit() &&
1088       !D->isUsed(false) &&
1089       !D->isInvalidDecl() &&
1090       !D->isReferenced() &&
1091       !D->isModulePrivate() &&
1092       !D->getBitWidth() &&
1093       !D->hasExtInfo() &&
1094       D->getDeclName())
1095     AbbrevToUse = Writer.getDeclObjCIvarAbbrev();
1096 
1097   Code = serialization::DECL_OBJC_IVAR;
1098 }
1099 
1100 void ASTDeclWriter::VisitObjCProtocolDecl(ObjCProtocolDecl *D) {
1101   VisitRedeclarable(D);
1102   VisitObjCContainerDecl(D);
1103 
1104   Record.push_back(D->isThisDeclarationADefinition());
1105   if (D->isThisDeclarationADefinition()) {
1106     Record.push_back(D->protocol_size());
1107     for (const auto *I : D->protocols())
1108       Record.AddDeclRef(I);
1109     for (const auto &PL : D->protocol_locs())
1110       Record.AddSourceLocation(PL);
1111     Record.push_back(D->getODRHash());
1112   }
1113 
1114   Code = serialization::DECL_OBJC_PROTOCOL;
1115 }
1116 
1117 void ASTDeclWriter::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D) {
1118   VisitFieldDecl(D);
1119   Code = serialization::DECL_OBJC_AT_DEFS_FIELD;
1120 }
1121 
1122 void ASTDeclWriter::VisitObjCCategoryDecl(ObjCCategoryDecl *D) {
1123   VisitObjCContainerDecl(D);
1124   Record.AddSourceLocation(D->getCategoryNameLoc());
1125   Record.AddSourceLocation(D->getIvarLBraceLoc());
1126   Record.AddSourceLocation(D->getIvarRBraceLoc());
1127   Record.AddDeclRef(D->getClassInterface());
1128   AddObjCTypeParamList(D->TypeParamList);
1129   Record.push_back(D->protocol_size());
1130   for (const auto *I : D->protocols())
1131     Record.AddDeclRef(I);
1132   for (const auto &PL : D->protocol_locs())
1133     Record.AddSourceLocation(PL);
1134   Code = serialization::DECL_OBJC_CATEGORY;
1135 }
1136 
1137 void ASTDeclWriter::VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *D) {
1138   VisitNamedDecl(D);
1139   Record.AddDeclRef(D->getClassInterface());
1140   Code = serialization::DECL_OBJC_COMPATIBLE_ALIAS;
1141 }
1142 
1143 void ASTDeclWriter::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
1144   VisitNamedDecl(D);
1145   Record.AddSourceLocation(D->getAtLoc());
1146   Record.AddSourceLocation(D->getLParenLoc());
1147   Record.AddTypeRef(D->getType());
1148   Record.AddTypeSourceInfo(D->getTypeSourceInfo());
1149   // FIXME: stable encoding
1150   Record.push_back((unsigned)D->getPropertyAttributes());
1151   Record.push_back((unsigned)D->getPropertyAttributesAsWritten());
1152   // FIXME: stable encoding
1153   Record.push_back((unsigned)D->getPropertyImplementation());
1154   Record.AddDeclarationName(D->getGetterName());
1155   Record.AddSourceLocation(D->getGetterNameLoc());
1156   Record.AddDeclarationName(D->getSetterName());
1157   Record.AddSourceLocation(D->getSetterNameLoc());
1158   Record.AddDeclRef(D->getGetterMethodDecl());
1159   Record.AddDeclRef(D->getSetterMethodDecl());
1160   Record.AddDeclRef(D->getPropertyIvarDecl());
1161   Code = serialization::DECL_OBJC_PROPERTY;
1162 }
1163 
1164 void ASTDeclWriter::VisitObjCImplDecl(ObjCImplDecl *D) {
1165   VisitObjCContainerDecl(D);
1166   Record.AddDeclRef(D->getClassInterface());
1167   // Abstract class (no need to define a stable serialization::DECL code).
1168 }
1169 
1170 void ASTDeclWriter::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
1171   VisitObjCImplDecl(D);
1172   Record.AddSourceLocation(D->getCategoryNameLoc());
1173   Code = serialization::DECL_OBJC_CATEGORY_IMPL;
1174 }
1175 
1176 void ASTDeclWriter::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
1177   VisitObjCImplDecl(D);
1178   Record.AddDeclRef(D->getSuperClass());
1179   Record.AddSourceLocation(D->getSuperClassLoc());
1180   Record.AddSourceLocation(D->getIvarLBraceLoc());
1181   Record.AddSourceLocation(D->getIvarRBraceLoc());
1182   Record.push_back(D->hasNonZeroConstructors());
1183   Record.push_back(D->hasDestructors());
1184   Record.push_back(D->NumIvarInitializers);
1185   if (D->NumIvarInitializers)
1186     Record.AddCXXCtorInitializers(
1187         llvm::ArrayRef(D->init_begin(), D->init_end()));
1188   Code = serialization::DECL_OBJC_IMPLEMENTATION;
1189 }
1190 
1191 void ASTDeclWriter::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
1192   VisitDecl(D);
1193   Record.AddSourceLocation(D->getBeginLoc());
1194   Record.AddDeclRef(D->getPropertyDecl());
1195   Record.AddDeclRef(D->getPropertyIvarDecl());
1196   Record.AddSourceLocation(D->getPropertyIvarDeclLoc());
1197   Record.AddDeclRef(D->getGetterMethodDecl());
1198   Record.AddDeclRef(D->getSetterMethodDecl());
1199   Record.AddStmt(D->getGetterCXXConstructor());
1200   Record.AddStmt(D->getSetterCXXAssignment());
1201   Code = serialization::DECL_OBJC_PROPERTY_IMPL;
1202 }
1203 
1204 void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
1205   VisitDeclaratorDecl(D);
1206   Record.push_back(D->isMutable());
1207 
1208   Record.push_back((D->StorageKind << 1) | D->BitField);
1209   if (D->StorageKind == FieldDecl::ISK_CapturedVLAType)
1210     Record.AddTypeRef(QualType(D->getCapturedVLAType(), 0));
1211   else if (D->BitField)
1212     Record.AddStmt(D->getBitWidth());
1213 
1214   if (!D->getDeclName() || D->isPlaceholderVar(Writer.getLangOpts()))
1215     Record.AddDeclRef(
1216         Record.getASTContext().getInstantiatedFromUnnamedFieldDecl(D));
1217 
1218   if (D->getDeclContext() == D->getLexicalDeclContext() &&
1219       !D->hasAttrs() &&
1220       !D->isImplicit() &&
1221       !D->isUsed(false) &&
1222       !D->isInvalidDecl() &&
1223       !D->isReferenced() &&
1224       !D->isTopLevelDeclInObjCContainer() &&
1225       !D->isModulePrivate() &&
1226       !D->getBitWidth() &&
1227       !D->hasInClassInitializer() &&
1228       !D->hasCapturedVLAType() &&
1229       !D->hasExtInfo() &&
1230       !ObjCIvarDecl::classofKind(D->getKind()) &&
1231       !ObjCAtDefsFieldDecl::classofKind(D->getKind()) &&
1232       D->getDeclName())
1233     AbbrevToUse = Writer.getDeclFieldAbbrev();
1234 
1235   Code = serialization::DECL_FIELD;
1236 }
1237 
1238 void ASTDeclWriter::VisitMSPropertyDecl(MSPropertyDecl *D) {
1239   VisitDeclaratorDecl(D);
1240   Record.AddIdentifierRef(D->getGetterId());
1241   Record.AddIdentifierRef(D->getSetterId());
1242   Code = serialization::DECL_MS_PROPERTY;
1243 }
1244 
1245 void ASTDeclWriter::VisitMSGuidDecl(MSGuidDecl *D) {
1246   VisitValueDecl(D);
1247   MSGuidDecl::Parts Parts = D->getParts();
1248   Record.push_back(Parts.Part1);
1249   Record.push_back(Parts.Part2);
1250   Record.push_back(Parts.Part3);
1251   Record.append(std::begin(Parts.Part4And5), std::end(Parts.Part4And5));
1252   Code = serialization::DECL_MS_GUID;
1253 }
1254 
1255 void ASTDeclWriter::VisitUnnamedGlobalConstantDecl(
1256     UnnamedGlobalConstantDecl *D) {
1257   VisitValueDecl(D);
1258   Record.AddAPValue(D->getValue());
1259   Code = serialization::DECL_UNNAMED_GLOBAL_CONSTANT;
1260 }
1261 
1262 void ASTDeclWriter::VisitTemplateParamObjectDecl(TemplateParamObjectDecl *D) {
1263   VisitValueDecl(D);
1264   Record.AddAPValue(D->getValue());
1265   Code = serialization::DECL_TEMPLATE_PARAM_OBJECT;
1266 }
1267 
1268 void ASTDeclWriter::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
1269   VisitValueDecl(D);
1270   Record.push_back(D->getChainingSize());
1271 
1272   for (const auto *P : D->chain())
1273     Record.AddDeclRef(P);
1274   Code = serialization::DECL_INDIRECTFIELD;
1275 }
1276 
1277 void ASTDeclWriter::VisitVarDecl(VarDecl *D) {
1278   VisitRedeclarable(D);
1279   VisitDeclaratorDecl(D);
1280 
1281   // The order matters here. It will be better to put the bit with higher
1282   // probability to be 0 in the end of the bits. See the comments in VisitDecl
1283   // for details.
1284   BitsPacker VarDeclBits;
1285   VarDeclBits.addBits(llvm::to_underlying(D->getLinkageInternal()),
1286                       /*BitWidth=*/3);
1287 
1288   bool ModulesCodegen = shouldVarGenerateHereOnly(D);
1289   VarDeclBits.addBit(ModulesCodegen);
1290 
1291   VarDeclBits.addBits(D->getStorageClass(), /*BitWidth=*/3);
1292   VarDeclBits.addBits(D->getTSCSpec(), /*BitWidth=*/2);
1293   VarDeclBits.addBits(D->getInitStyle(), /*BitWidth=*/2);
1294   VarDeclBits.addBit(D->isARCPseudoStrong());
1295 
1296   bool HasDeducedType = false;
1297   if (!isa<ParmVarDecl>(D)) {
1298     VarDeclBits.addBit(D->isThisDeclarationADemotedDefinition());
1299     VarDeclBits.addBit(D->isExceptionVariable());
1300     VarDeclBits.addBit(D->isNRVOVariable());
1301     VarDeclBits.addBit(D->isCXXForRangeDecl());
1302 
1303     VarDeclBits.addBit(D->isInline());
1304     VarDeclBits.addBit(D->isInlineSpecified());
1305     VarDeclBits.addBit(D->isConstexpr());
1306     VarDeclBits.addBit(D->isInitCapture());
1307     VarDeclBits.addBit(D->isPreviousDeclInSameBlockScope());
1308 
1309     VarDeclBits.addBit(D->isEscapingByref());
1310     HasDeducedType = D->getType()->getContainedDeducedType();
1311     VarDeclBits.addBit(HasDeducedType);
1312 
1313     if (const auto *IPD = dyn_cast<ImplicitParamDecl>(D))
1314       VarDeclBits.addBits(llvm::to_underlying(IPD->getParameterKind()),
1315                           /*Width=*/3);
1316     else
1317       VarDeclBits.addBits(0, /*Width=*/3);
1318 
1319     VarDeclBits.addBit(D->isObjCForDecl());
1320     VarDeclBits.addBit(D->isCXXForRangeImplicitVar());
1321   }
1322 
1323   Record.push_back(VarDeclBits);
1324 
1325   if (ModulesCodegen)
1326     Writer.AddDeclRef(D, Writer.ModularCodegenDecls);
1327 
1328   if (D->hasAttr<BlocksAttr>()) {
1329     BlockVarCopyInit Init = Record.getASTContext().getBlockVarCopyInit(D);
1330     Record.AddStmt(Init.getCopyExpr());
1331     if (Init.getCopyExpr())
1332       Record.push_back(Init.canThrow());
1333   }
1334 
1335   enum {
1336     VarNotTemplate = 0, VarTemplate, StaticDataMemberSpecialization
1337   };
1338   if (VarTemplateDecl *TemplD = D->getDescribedVarTemplate()) {
1339     Record.push_back(VarTemplate);
1340     Record.AddDeclRef(TemplD);
1341   } else if (MemberSpecializationInfo *SpecInfo
1342                = D->getMemberSpecializationInfo()) {
1343     Record.push_back(StaticDataMemberSpecialization);
1344     Record.AddDeclRef(SpecInfo->getInstantiatedFrom());
1345     Record.push_back(SpecInfo->getTemplateSpecializationKind());
1346     Record.AddSourceLocation(SpecInfo->getPointOfInstantiation());
1347   } else {
1348     Record.push_back(VarNotTemplate);
1349   }
1350 
1351   if (D->getDeclContext() == D->getLexicalDeclContext() && !D->hasAttrs() &&
1352       !D->isTopLevelDeclInObjCContainer() &&
1353       !needsAnonymousDeclarationNumber(D) &&
1354       D->getDeclName().getNameKind() == DeclarationName::Identifier &&
1355       !D->hasExtInfo() && D->getFirstDecl() == D->getMostRecentDecl() &&
1356       D->getKind() == Decl::Var && !D->isInline() && !D->isConstexpr() &&
1357       !D->isInitCapture() && !D->isPreviousDeclInSameBlockScope() &&
1358       !D->hasInitWithSideEffects() && !D->isEscapingByref() &&
1359       !HasDeducedType && D->getStorageDuration() != SD_Static &&
1360       !D->getDescribedVarTemplate() && !D->getMemberSpecializationInfo() &&
1361       !D->isObjCForDecl() && !isa<ImplicitParamDecl>(D) &&
1362       !D->isEscapingByref())
1363     AbbrevToUse = Writer.getDeclVarAbbrev();
1364 
1365   Code = serialization::DECL_VAR;
1366 }
1367 
1368 void ASTDeclWriter::VisitImplicitParamDecl(ImplicitParamDecl *D) {
1369   VisitVarDecl(D);
1370   Code = serialization::DECL_IMPLICIT_PARAM;
1371 }
1372 
1373 void ASTDeclWriter::VisitParmVarDecl(ParmVarDecl *D) {
1374   VisitVarDecl(D);
1375 
1376   // See the implementation of `ParmVarDecl::getParameterIndex()`, which may
1377   // exceed the size of the normal bitfield. So it may be better to not pack
1378   // these bits.
1379   Record.push_back(D->getFunctionScopeIndex());
1380 
1381   BitsPacker ParmVarDeclBits;
1382   ParmVarDeclBits.addBit(D->isObjCMethodParameter());
1383   ParmVarDeclBits.addBits(D->getFunctionScopeDepth(), /*BitsWidth=*/7);
1384   // FIXME: stable encoding
1385   ParmVarDeclBits.addBits(D->getObjCDeclQualifier(), /*BitsWidth=*/7);
1386   ParmVarDeclBits.addBit(D->isKNRPromoted());
1387   ParmVarDeclBits.addBit(D->hasInheritedDefaultArg());
1388   ParmVarDeclBits.addBit(D->hasUninstantiatedDefaultArg());
1389   ParmVarDeclBits.addBit(D->getExplicitObjectParamThisLoc().isValid());
1390   Record.push_back(ParmVarDeclBits);
1391 
1392   if (D->hasUninstantiatedDefaultArg())
1393     Record.AddStmt(D->getUninstantiatedDefaultArg());
1394   if (D->getExplicitObjectParamThisLoc().isValid())
1395     Record.AddSourceLocation(D->getExplicitObjectParamThisLoc());
1396   Code = serialization::DECL_PARM_VAR;
1397 
1398   // If the assumptions about the DECL_PARM_VAR abbrev are true, use it.  Here
1399   // we dynamically check for the properties that we optimize for, but don't
1400   // know are true of all PARM_VAR_DECLs.
1401   if (D->getDeclContext() == D->getLexicalDeclContext() && !D->hasAttrs() &&
1402       !D->hasExtInfo() && D->getStorageClass() == 0 && !D->isInvalidDecl() &&
1403       !D->isTopLevelDeclInObjCContainer() &&
1404       D->getInitStyle() == VarDecl::CInit && // Can params have anything else?
1405       D->getInit() == nullptr)               // No default expr.
1406     AbbrevToUse = Writer.getDeclParmVarAbbrev();
1407 
1408   // Check things we know are true of *every* PARM_VAR_DECL, which is more than
1409   // just us assuming it.
1410   assert(!D->getTSCSpec() && "PARM_VAR_DECL can't use TLS");
1411   assert(!D->isThisDeclarationADemotedDefinition()
1412          && "PARM_VAR_DECL can't be demoted definition.");
1413   assert(D->getAccess() == AS_none && "PARM_VAR_DECL can't be public/private");
1414   assert(!D->isExceptionVariable() && "PARM_VAR_DECL can't be exception var");
1415   assert(D->getPreviousDecl() == nullptr && "PARM_VAR_DECL can't be redecl");
1416   assert(!D->isStaticDataMember() &&
1417          "PARM_VAR_DECL can't be static data member");
1418 }
1419 
1420 void ASTDeclWriter::VisitDecompositionDecl(DecompositionDecl *D) {
1421   // Record the number of bindings first to simplify deserialization.
1422   Record.push_back(D->bindings().size());
1423 
1424   VisitVarDecl(D);
1425   for (auto *B : D->bindings())
1426     Record.AddDeclRef(B);
1427   Code = serialization::DECL_DECOMPOSITION;
1428 }
1429 
1430 void ASTDeclWriter::VisitBindingDecl(BindingDecl *D) {
1431   VisitValueDecl(D);
1432   Record.AddStmt(D->getBinding());
1433   Code = serialization::DECL_BINDING;
1434 }
1435 
1436 void ASTDeclWriter::VisitFileScopeAsmDecl(FileScopeAsmDecl *D) {
1437   VisitDecl(D);
1438   Record.AddStmt(D->getAsmStringExpr());
1439   Record.AddSourceLocation(D->getRParenLoc());
1440   Code = serialization::DECL_FILE_SCOPE_ASM;
1441 }
1442 
1443 void ASTDeclWriter::VisitTopLevelStmtDecl(TopLevelStmtDecl *D) {
1444   VisitDecl(D);
1445   Record.AddStmt(D->getStmt());
1446   Code = serialization::DECL_TOP_LEVEL_STMT_DECL;
1447 }
1448 
1449 void ASTDeclWriter::VisitEmptyDecl(EmptyDecl *D) {
1450   VisitDecl(D);
1451   Code = serialization::DECL_EMPTY;
1452 }
1453 
1454 void ASTDeclWriter::VisitLifetimeExtendedTemporaryDecl(
1455     LifetimeExtendedTemporaryDecl *D) {
1456   VisitDecl(D);
1457   Record.AddDeclRef(D->getExtendingDecl());
1458   Record.AddStmt(D->getTemporaryExpr());
1459   Record.push_back(static_cast<bool>(D->getValue()));
1460   if (D->getValue())
1461     Record.AddAPValue(*D->getValue());
1462   Record.push_back(D->getManglingNumber());
1463   Code = serialization::DECL_LIFETIME_EXTENDED_TEMPORARY;
1464 }
1465 void ASTDeclWriter::VisitBlockDecl(BlockDecl *D) {
1466   VisitDecl(D);
1467   Record.AddStmt(D->getBody());
1468   Record.AddTypeSourceInfo(D->getSignatureAsWritten());
1469   Record.push_back(D->param_size());
1470   for (ParmVarDecl *P : D->parameters())
1471     Record.AddDeclRef(P);
1472   Record.push_back(D->isVariadic());
1473   Record.push_back(D->blockMissingReturnType());
1474   Record.push_back(D->isConversionFromLambda());
1475   Record.push_back(D->doesNotEscape());
1476   Record.push_back(D->canAvoidCopyToHeap());
1477   Record.push_back(D->capturesCXXThis());
1478   Record.push_back(D->getNumCaptures());
1479   for (const auto &capture : D->captures()) {
1480     Record.AddDeclRef(capture.getVariable());
1481 
1482     unsigned flags = 0;
1483     if (capture.isByRef()) flags |= 1;
1484     if (capture.isNested()) flags |= 2;
1485     if (capture.hasCopyExpr()) flags |= 4;
1486     Record.push_back(flags);
1487 
1488     if (capture.hasCopyExpr()) Record.AddStmt(capture.getCopyExpr());
1489   }
1490 
1491   Code = serialization::DECL_BLOCK;
1492 }
1493 
1494 void ASTDeclWriter::VisitOutlinedFunctionDecl(OutlinedFunctionDecl *D) {
1495   Record.push_back(D->getNumParams());
1496   VisitDecl(D);
1497   for (unsigned I = 0; I < D->getNumParams(); ++I)
1498     Record.AddDeclRef(D->getParam(I));
1499   Record.push_back(D->isNothrow() ? 1 : 0);
1500   Record.AddStmt(D->getBody());
1501   Code = serialization::DECL_OUTLINEDFUNCTION;
1502 }
1503 
1504 void ASTDeclWriter::VisitCapturedDecl(CapturedDecl *CD) {
1505   Record.push_back(CD->getNumParams());
1506   VisitDecl(CD);
1507   Record.push_back(CD->getContextParamPosition());
1508   Record.push_back(CD->isNothrow() ? 1 : 0);
1509   // Body is stored by VisitCapturedStmt.
1510   for (unsigned I = 0; I < CD->getNumParams(); ++I)
1511     Record.AddDeclRef(CD->getParam(I));
1512   Code = serialization::DECL_CAPTURED;
1513 }
1514 
1515 void ASTDeclWriter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
1516   static_assert(DeclContext::NumLinkageSpecDeclBits == 17,
1517                 "You need to update the serializer after you change the"
1518                 "LinkageSpecDeclBits");
1519 
1520   VisitDecl(D);
1521   Record.push_back(llvm::to_underlying(D->getLanguage()));
1522   Record.AddSourceLocation(D->getExternLoc());
1523   Record.AddSourceLocation(D->getRBraceLoc());
1524   Code = serialization::DECL_LINKAGE_SPEC;
1525 }
1526 
1527 void ASTDeclWriter::VisitExportDecl(ExportDecl *D) {
1528   VisitDecl(D);
1529   Record.AddSourceLocation(D->getRBraceLoc());
1530   Code = serialization::DECL_EXPORT;
1531 }
1532 
1533 void ASTDeclWriter::VisitLabelDecl(LabelDecl *D) {
1534   VisitNamedDecl(D);
1535   Record.AddSourceLocation(D->getBeginLoc());
1536   Code = serialization::DECL_LABEL;
1537 }
1538 
1539 
1540 void ASTDeclWriter::VisitNamespaceDecl(NamespaceDecl *D) {
1541   VisitRedeclarable(D);
1542   VisitNamedDecl(D);
1543 
1544   BitsPacker NamespaceDeclBits;
1545   NamespaceDeclBits.addBit(D->isInline());
1546   NamespaceDeclBits.addBit(D->isNested());
1547   Record.push_back(NamespaceDeclBits);
1548 
1549   Record.AddSourceLocation(D->getBeginLoc());
1550   Record.AddSourceLocation(D->getRBraceLoc());
1551 
1552   if (D->isFirstDecl())
1553     Record.AddDeclRef(D->getAnonymousNamespace());
1554   Code = serialization::DECL_NAMESPACE;
1555 
1556   if (Writer.hasChain() && D->isAnonymousNamespace() &&
1557       D == D->getMostRecentDecl()) {
1558     // This is a most recent reopening of the anonymous namespace. If its parent
1559     // is in a previous PCH (or is the TU), mark that parent for update, because
1560     // the original namespace always points to the latest re-opening of its
1561     // anonymous namespace.
1562     Decl *Parent = cast<Decl>(
1563         D->getParent()->getRedeclContext()->getPrimaryContext());
1564     if (Parent->isFromASTFile() || isa<TranslationUnitDecl>(Parent)) {
1565       Writer.DeclUpdates[Parent].push_back(
1566           ASTWriter::DeclUpdate(DeclUpdateKind::CXXAddedAnonymousNamespace, D));
1567     }
1568   }
1569 }
1570 
1571 void ASTDeclWriter::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
1572   VisitRedeclarable(D);
1573   VisitNamedDecl(D);
1574   Record.AddSourceLocation(D->getNamespaceLoc());
1575   Record.AddSourceLocation(D->getTargetNameLoc());
1576   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
1577   Record.AddDeclRef(D->getNamespace());
1578   Code = serialization::DECL_NAMESPACE_ALIAS;
1579 }
1580 
1581 void ASTDeclWriter::VisitUsingDecl(UsingDecl *D) {
1582   VisitNamedDecl(D);
1583   Record.AddSourceLocation(D->getUsingLoc());
1584   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
1585   Record.AddDeclarationNameLoc(D->DNLoc, D->getDeclName());
1586   Record.AddDeclRef(D->FirstUsingShadow.getPointer());
1587   Record.push_back(D->hasTypename());
1588   Record.AddDeclRef(Record.getASTContext().getInstantiatedFromUsingDecl(D));
1589   Code = serialization::DECL_USING;
1590 }
1591 
1592 void ASTDeclWriter::VisitUsingEnumDecl(UsingEnumDecl *D) {
1593   VisitNamedDecl(D);
1594   Record.AddSourceLocation(D->getUsingLoc());
1595   Record.AddSourceLocation(D->getEnumLoc());
1596   Record.AddTypeSourceInfo(D->getEnumType());
1597   Record.AddDeclRef(D->FirstUsingShadow.getPointer());
1598   Record.AddDeclRef(Record.getASTContext().getInstantiatedFromUsingEnumDecl(D));
1599   Code = serialization::DECL_USING_ENUM;
1600 }
1601 
1602 void ASTDeclWriter::VisitUsingPackDecl(UsingPackDecl *D) {
1603   Record.push_back(D->NumExpansions);
1604   VisitNamedDecl(D);
1605   Record.AddDeclRef(D->getInstantiatedFromUsingDecl());
1606   for (auto *E : D->expansions())
1607     Record.AddDeclRef(E);
1608   Code = serialization::DECL_USING_PACK;
1609 }
1610 
1611 void ASTDeclWriter::VisitUsingShadowDecl(UsingShadowDecl *D) {
1612   VisitRedeclarable(D);
1613   VisitNamedDecl(D);
1614   Record.AddDeclRef(D->getTargetDecl());
1615   Record.push_back(D->getIdentifierNamespace());
1616   Record.AddDeclRef(D->UsingOrNextShadow);
1617   Record.AddDeclRef(
1618       Record.getASTContext().getInstantiatedFromUsingShadowDecl(D));
1619 
1620   if (D->getDeclContext() == D->getLexicalDeclContext() &&
1621       D->getFirstDecl() == D->getMostRecentDecl() && !D->hasAttrs() &&
1622       !needsAnonymousDeclarationNumber(D) &&
1623       D->getDeclName().getNameKind() == DeclarationName::Identifier)
1624     AbbrevToUse = Writer.getDeclUsingShadowAbbrev();
1625 
1626   Code = serialization::DECL_USING_SHADOW;
1627 }
1628 
1629 void ASTDeclWriter::VisitConstructorUsingShadowDecl(
1630     ConstructorUsingShadowDecl *D) {
1631   VisitUsingShadowDecl(D);
1632   Record.AddDeclRef(D->NominatedBaseClassShadowDecl);
1633   Record.AddDeclRef(D->ConstructedBaseClassShadowDecl);
1634   Record.push_back(D->IsVirtual);
1635   Code = serialization::DECL_CONSTRUCTOR_USING_SHADOW;
1636 }
1637 
1638 void ASTDeclWriter::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
1639   VisitNamedDecl(D);
1640   Record.AddSourceLocation(D->getUsingLoc());
1641   Record.AddSourceLocation(D->getNamespaceKeyLocation());
1642   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
1643   Record.AddDeclRef(D->getNominatedNamespace());
1644   Record.AddDeclRef(dyn_cast<Decl>(D->getCommonAncestor()));
1645   Code = serialization::DECL_USING_DIRECTIVE;
1646 }
1647 
1648 void ASTDeclWriter::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
1649   VisitValueDecl(D);
1650   Record.AddSourceLocation(D->getUsingLoc());
1651   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
1652   Record.AddDeclarationNameLoc(D->DNLoc, D->getDeclName());
1653   Record.AddSourceLocation(D->getEllipsisLoc());
1654   Code = serialization::DECL_UNRESOLVED_USING_VALUE;
1655 }
1656 
1657 void ASTDeclWriter::VisitUnresolvedUsingTypenameDecl(
1658                                                UnresolvedUsingTypenameDecl *D) {
1659   VisitTypeDecl(D);
1660   Record.AddSourceLocation(D->getTypenameLoc());
1661   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
1662   Record.AddSourceLocation(D->getEllipsisLoc());
1663   Code = serialization::DECL_UNRESOLVED_USING_TYPENAME;
1664 }
1665 
1666 void ASTDeclWriter::VisitUnresolvedUsingIfExistsDecl(
1667     UnresolvedUsingIfExistsDecl *D) {
1668   VisitNamedDecl(D);
1669   Code = serialization::DECL_UNRESOLVED_USING_IF_EXISTS;
1670 }
1671 
1672 void ASTDeclWriter::VisitCXXRecordDecl(CXXRecordDecl *D) {
1673   VisitRecordDecl(D);
1674 
1675   enum {
1676     CXXRecNotTemplate = 0,
1677     CXXRecTemplate,
1678     CXXRecMemberSpecialization,
1679     CXXLambda
1680   };
1681   if (ClassTemplateDecl *TemplD = D->getDescribedClassTemplate()) {
1682     Record.push_back(CXXRecTemplate);
1683     Record.AddDeclRef(TemplD);
1684   } else if (MemberSpecializationInfo *MSInfo
1685                = D->getMemberSpecializationInfo()) {
1686     Record.push_back(CXXRecMemberSpecialization);
1687     Record.AddDeclRef(MSInfo->getInstantiatedFrom());
1688     Record.push_back(MSInfo->getTemplateSpecializationKind());
1689     Record.AddSourceLocation(MSInfo->getPointOfInstantiation());
1690   } else if (D->isLambda()) {
1691     // For a lambda, we need some information early for merging.
1692     Record.push_back(CXXLambda);
1693     if (auto *Context = D->getLambdaContextDecl()) {
1694       Record.AddDeclRef(Context);
1695       Record.push_back(D->getLambdaIndexInContext());
1696     } else {
1697       Record.push_back(0);
1698     }
1699     // For lambdas inside template functions, remember the mapping to
1700     // deserialize them together.
1701     if (auto *FD = llvm::dyn_cast_or_null<FunctionDecl>(D->getDeclContext());
1702         FD && isDefinitionInDependentContext(FD)) {
1703       Writer.RelatedDeclsMap[Writer.GetDeclRef(FD)].push_back(
1704           Writer.GetDeclRef(D->getLambdaCallOperator()));
1705     }
1706   } else {
1707     Record.push_back(CXXRecNotTemplate);
1708   }
1709 
1710   Record.push_back(D->isThisDeclarationADefinition());
1711   if (D->isThisDeclarationADefinition())
1712     Record.AddCXXDefinitionData(D);
1713 
1714   if (D->isCompleteDefinition() && D->isInNamedModule())
1715     Writer.AddDeclRef(D, Writer.ModularCodegenDecls);
1716 
1717   // Store (what we currently believe to be) the key function to avoid
1718   // deserializing every method so we can compute it.
1719   //
1720   // FIXME: Avoid adding the key function if the class is defined in
1721   // module purview since in that case the key function is meaningless.
1722   if (D->isCompleteDefinition())
1723     Record.AddDeclRef(Record.getASTContext().getCurrentKeyFunction(D));
1724 
1725   Code = serialization::DECL_CXX_RECORD;
1726 }
1727 
1728 void ASTDeclWriter::VisitCXXMethodDecl(CXXMethodDecl *D) {
1729   VisitFunctionDecl(D);
1730   if (D->isCanonicalDecl()) {
1731     Record.push_back(D->size_overridden_methods());
1732     for (const CXXMethodDecl *MD : D->overridden_methods())
1733       Record.AddDeclRef(MD);
1734   } else {
1735     // We only need to record overridden methods once for the canonical decl.
1736     Record.push_back(0);
1737   }
1738 
1739   if (D->getDeclContext() == D->getLexicalDeclContext() &&
1740       D->getFirstDecl() == D->getMostRecentDecl() && !D->isInvalidDecl() &&
1741       !D->hasAttrs() && !D->isTopLevelDeclInObjCContainer() &&
1742       D->getDeclName().getNameKind() == DeclarationName::Identifier &&
1743       !D->hasExtInfo() && !D->isExplicitlyDefaulted()) {
1744     if (D->getTemplatedKind() == FunctionDecl::TK_NonTemplate ||
1745         D->getTemplatedKind() == FunctionDecl::TK_FunctionTemplate ||
1746         D->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization ||
1747         D->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate)
1748       AbbrevToUse = Writer.getDeclCXXMethodAbbrev(D->getTemplatedKind());
1749     else if (D->getTemplatedKind() ==
1750              FunctionDecl::TK_FunctionTemplateSpecialization) {
1751       FunctionTemplateSpecializationInfo *FTSInfo =
1752           D->getTemplateSpecializationInfo();
1753 
1754       if (FTSInfo->TemplateArguments->size() == 1) {
1755         const TemplateArgument &TA = FTSInfo->TemplateArguments->get(0);
1756         if (TA.getKind() == TemplateArgument::Type &&
1757             !FTSInfo->TemplateArgumentsAsWritten &&
1758             !FTSInfo->getMemberSpecializationInfo())
1759           AbbrevToUse = Writer.getDeclCXXMethodAbbrev(D->getTemplatedKind());
1760       }
1761     } else if (D->getTemplatedKind() ==
1762                FunctionDecl::TK_DependentFunctionTemplateSpecialization) {
1763       DependentFunctionTemplateSpecializationInfo *DFTSInfo =
1764           D->getDependentSpecializationInfo();
1765       if (!DFTSInfo->TemplateArgumentsAsWritten)
1766         AbbrevToUse = Writer.getDeclCXXMethodAbbrev(D->getTemplatedKind());
1767     }
1768   }
1769 
1770   Code = serialization::DECL_CXX_METHOD;
1771 }
1772 
1773 void ASTDeclWriter::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
1774   static_assert(DeclContext::NumCXXConstructorDeclBits == 64,
1775                 "You need to update the serializer after you change the "
1776                 "CXXConstructorDeclBits");
1777 
1778   Record.push_back(D->getTrailingAllocKind());
1779   addExplicitSpecifier(D->getExplicitSpecifierInternal(), Record);
1780   if (auto Inherited = D->getInheritedConstructor()) {
1781     Record.AddDeclRef(Inherited.getShadowDecl());
1782     Record.AddDeclRef(Inherited.getConstructor());
1783   }
1784 
1785   VisitCXXMethodDecl(D);
1786   Code = serialization::DECL_CXX_CONSTRUCTOR;
1787 }
1788 
1789 void ASTDeclWriter::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
1790   VisitCXXMethodDecl(D);
1791 
1792   Record.AddDeclRef(D->getOperatorDelete());
1793   if (D->getOperatorDelete())
1794     Record.AddStmt(D->getOperatorDeleteThisArg());
1795 
1796   Code = serialization::DECL_CXX_DESTRUCTOR;
1797 }
1798 
1799 void ASTDeclWriter::VisitCXXConversionDecl(CXXConversionDecl *D) {
1800   addExplicitSpecifier(D->getExplicitSpecifier(), Record);
1801   VisitCXXMethodDecl(D);
1802   Code = serialization::DECL_CXX_CONVERSION;
1803 }
1804 
1805 void ASTDeclWriter::VisitImportDecl(ImportDecl *D) {
1806   VisitDecl(D);
1807   Record.push_back(Writer.getSubmoduleID(D->getImportedModule()));
1808   ArrayRef<SourceLocation> IdentifierLocs = D->getIdentifierLocs();
1809   Record.push_back(!IdentifierLocs.empty());
1810   if (IdentifierLocs.empty()) {
1811     Record.AddSourceLocation(D->getEndLoc());
1812     Record.push_back(1);
1813   } else {
1814     for (unsigned I = 0, N = IdentifierLocs.size(); I != N; ++I)
1815       Record.AddSourceLocation(IdentifierLocs[I]);
1816     Record.push_back(IdentifierLocs.size());
1817   }
1818   // Note: the number of source locations must always be the last element in
1819   // the record.
1820   Code = serialization::DECL_IMPORT;
1821 }
1822 
1823 void ASTDeclWriter::VisitAccessSpecDecl(AccessSpecDecl *D) {
1824   VisitDecl(D);
1825   Record.AddSourceLocation(D->getColonLoc());
1826   Code = serialization::DECL_ACCESS_SPEC;
1827 }
1828 
1829 void ASTDeclWriter::VisitFriendDecl(FriendDecl *D) {
1830   // Record the number of friend type template parameter lists here
1831   // so as to simplify memory allocation during deserialization.
1832   Record.push_back(D->NumTPLists);
1833   VisitDecl(D);
1834   bool hasFriendDecl = isa<NamedDecl *>(D->Friend);
1835   Record.push_back(hasFriendDecl);
1836   if (hasFriendDecl)
1837     Record.AddDeclRef(D->getFriendDecl());
1838   else
1839     Record.AddTypeSourceInfo(D->getFriendType());
1840   for (unsigned i = 0; i < D->NumTPLists; ++i)
1841     Record.AddTemplateParameterList(D->getFriendTypeTemplateParameterList(i));
1842   Record.AddDeclRef(D->getNextFriend());
1843   Record.push_back(D->UnsupportedFriend);
1844   Record.AddSourceLocation(D->FriendLoc);
1845   Record.AddSourceLocation(D->EllipsisLoc);
1846   Code = serialization::DECL_FRIEND;
1847 }
1848 
1849 void ASTDeclWriter::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
1850   VisitDecl(D);
1851   Record.push_back(D->getNumTemplateParameters());
1852   for (unsigned i = 0, e = D->getNumTemplateParameters(); i != e; ++i)
1853     Record.AddTemplateParameterList(D->getTemplateParameterList(i));
1854   Record.push_back(D->getFriendDecl() != nullptr);
1855   if (D->getFriendDecl())
1856     Record.AddDeclRef(D->getFriendDecl());
1857   else
1858     Record.AddTypeSourceInfo(D->getFriendType());
1859   Record.AddSourceLocation(D->getFriendLoc());
1860   Code = serialization::DECL_FRIEND_TEMPLATE;
1861 }
1862 
1863 void ASTDeclWriter::VisitTemplateDecl(TemplateDecl *D) {
1864   VisitNamedDecl(D);
1865 
1866   Record.AddTemplateParameterList(D->getTemplateParameters());
1867   Record.AddDeclRef(D->getTemplatedDecl());
1868 }
1869 
1870 void ASTDeclWriter::VisitConceptDecl(ConceptDecl *D) {
1871   VisitTemplateDecl(D);
1872   Record.AddStmt(D->getConstraintExpr());
1873   Code = serialization::DECL_CONCEPT;
1874 }
1875 
1876 void ASTDeclWriter::VisitImplicitConceptSpecializationDecl(
1877     ImplicitConceptSpecializationDecl *D) {
1878   Record.push_back(D->getTemplateArguments().size());
1879   VisitDecl(D);
1880   for (const TemplateArgument &Arg : D->getTemplateArguments())
1881     Record.AddTemplateArgument(Arg);
1882   Code = serialization::DECL_IMPLICIT_CONCEPT_SPECIALIZATION;
1883 }
1884 
1885 void ASTDeclWriter::VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D) {
1886   Code = serialization::DECL_REQUIRES_EXPR_BODY;
1887 }
1888 
1889 void ASTDeclWriter::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
1890   VisitRedeclarable(D);
1891 
1892   // Emit data to initialize CommonOrPrev before VisitTemplateDecl so that
1893   // getCommonPtr() can be used while this is still initializing.
1894   if (D->isFirstDecl()) {
1895     // This declaration owns the 'common' pointer, so serialize that data now.
1896     Record.AddDeclRef(D->getInstantiatedFromMemberTemplate());
1897     if (D->getInstantiatedFromMemberTemplate())
1898       Record.push_back(D->isMemberSpecialization());
1899   }
1900 
1901   VisitTemplateDecl(D);
1902   Record.push_back(D->getIdentifierNamespace());
1903 }
1904 
1905 void ASTDeclWriter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
1906   VisitRedeclarableTemplateDecl(D);
1907 
1908   if (D->isFirstDecl())
1909     AddTemplateSpecializations(D);
1910 
1911   // Force emitting the corresponding deduction guide in reduced BMI mode.
1912   // Otherwise, the deduction guide may be optimized out incorrectly.
1913   if (Writer.isGeneratingReducedBMI()) {
1914     auto Name =
1915         Record.getASTContext().DeclarationNames.getCXXDeductionGuideName(D);
1916     for (auto *DG : D->getDeclContext()->noload_lookup(Name))
1917       Writer.GetDeclRef(DG->getCanonicalDecl());
1918   }
1919 
1920   Code = serialization::DECL_CLASS_TEMPLATE;
1921 }
1922 
1923 void ASTDeclWriter::VisitClassTemplateSpecializationDecl(
1924                                            ClassTemplateSpecializationDecl *D) {
1925   RegisterTemplateSpecialization(D->getSpecializedTemplate(), D);
1926 
1927   VisitCXXRecordDecl(D);
1928 
1929   llvm::PointerUnion<ClassTemplateDecl *,
1930                      ClassTemplatePartialSpecializationDecl *> InstFrom
1931     = D->getSpecializedTemplateOrPartial();
1932   if (Decl *InstFromD = InstFrom.dyn_cast<ClassTemplateDecl *>()) {
1933     Record.AddDeclRef(InstFromD);
1934   } else {
1935     Record.AddDeclRef(cast<ClassTemplatePartialSpecializationDecl *>(InstFrom));
1936     Record.AddTemplateArgumentList(&D->getTemplateInstantiationArgs());
1937   }
1938 
1939   Record.AddTemplateArgumentList(&D->getTemplateArgs());
1940   Record.AddSourceLocation(D->getPointOfInstantiation());
1941   Record.push_back(D->getSpecializationKind());
1942   Record.push_back(D->hasStrictPackMatch());
1943   Record.push_back(D->isCanonicalDecl());
1944 
1945   if (D->isCanonicalDecl()) {
1946     // When reading, we'll add it to the folding set of the following template.
1947     Record.AddDeclRef(D->getSpecializedTemplate()->getCanonicalDecl());
1948   }
1949 
1950   bool ExplicitInstantiation =
1951       D->getTemplateSpecializationKind() ==
1952           TSK_ExplicitInstantiationDeclaration ||
1953       D->getTemplateSpecializationKind() == TSK_ExplicitInstantiationDefinition;
1954   Record.push_back(ExplicitInstantiation);
1955   if (ExplicitInstantiation) {
1956     Record.AddSourceLocation(D->getExternKeywordLoc());
1957     Record.AddSourceLocation(D->getTemplateKeywordLoc());
1958   }
1959 
1960   const ASTTemplateArgumentListInfo *ArgsWritten =
1961       D->getTemplateArgsAsWritten();
1962   Record.push_back(!!ArgsWritten);
1963   if (ArgsWritten)
1964     Record.AddASTTemplateArgumentListInfo(ArgsWritten);
1965 
1966   // Mention the implicitly generated C++ deduction guide to make sure the
1967   // deduction guide will be rewritten as expected.
1968   //
1969   // FIXME: Would it be more efficient to add a callback register function
1970   // in sema to register the deduction guide?
1971   if (Writer.isWritingStdCXXNamedModules()) {
1972     auto Name =
1973         Record.getASTContext().DeclarationNames.getCXXDeductionGuideName(
1974             D->getSpecializedTemplate());
1975     for (auto *DG : D->getDeclContext()->noload_lookup(Name))
1976       Writer.GetDeclRef(DG->getCanonicalDecl());
1977   }
1978 
1979   Code = serialization::DECL_CLASS_TEMPLATE_SPECIALIZATION;
1980 }
1981 
1982 void ASTDeclWriter::VisitClassTemplatePartialSpecializationDecl(
1983                                     ClassTemplatePartialSpecializationDecl *D) {
1984   Record.AddTemplateParameterList(D->getTemplateParameters());
1985 
1986   VisitClassTemplateSpecializationDecl(D);
1987 
1988   // These are read/set from/to the first declaration.
1989   if (D->getPreviousDecl() == nullptr) {
1990     Record.AddDeclRef(D->getInstantiatedFromMember());
1991     Record.push_back(D->isMemberSpecialization());
1992   }
1993 
1994   Code = serialization::DECL_CLASS_TEMPLATE_PARTIAL_SPECIALIZATION;
1995 }
1996 
1997 void ASTDeclWriter::VisitVarTemplateDecl(VarTemplateDecl *D) {
1998   VisitRedeclarableTemplateDecl(D);
1999 
2000   if (D->isFirstDecl())
2001     AddTemplateSpecializations(D);
2002   Code = serialization::DECL_VAR_TEMPLATE;
2003 }
2004 
2005 void ASTDeclWriter::VisitVarTemplateSpecializationDecl(
2006     VarTemplateSpecializationDecl *D) {
2007   RegisterTemplateSpecialization(D->getSpecializedTemplate(), D);
2008 
2009   llvm::PointerUnion<VarTemplateDecl *, VarTemplatePartialSpecializationDecl *>
2010   InstFrom = D->getSpecializedTemplateOrPartial();
2011   if (Decl *InstFromD = InstFrom.dyn_cast<VarTemplateDecl *>()) {
2012     Record.AddDeclRef(InstFromD);
2013   } else {
2014     Record.AddDeclRef(cast<VarTemplatePartialSpecializationDecl *>(InstFrom));
2015     Record.AddTemplateArgumentList(&D->getTemplateInstantiationArgs());
2016   }
2017 
2018   bool ExplicitInstantiation =
2019       D->getTemplateSpecializationKind() ==
2020           TSK_ExplicitInstantiationDeclaration ||
2021       D->getTemplateSpecializationKind() == TSK_ExplicitInstantiationDefinition;
2022   Record.push_back(ExplicitInstantiation);
2023   if (ExplicitInstantiation) {
2024     Record.AddSourceLocation(D->getExternKeywordLoc());
2025     Record.AddSourceLocation(D->getTemplateKeywordLoc());
2026   }
2027 
2028   const ASTTemplateArgumentListInfo *ArgsWritten =
2029       D->getTemplateArgsAsWritten();
2030   Record.push_back(!!ArgsWritten);
2031   if (ArgsWritten)
2032     Record.AddASTTemplateArgumentListInfo(ArgsWritten);
2033 
2034   Record.AddTemplateArgumentList(&D->getTemplateArgs());
2035   Record.AddSourceLocation(D->getPointOfInstantiation());
2036   Record.push_back(D->getSpecializationKind());
2037   Record.push_back(D->IsCompleteDefinition);
2038 
2039   VisitVarDecl(D);
2040 
2041   Record.push_back(D->isCanonicalDecl());
2042 
2043   if (D->isCanonicalDecl()) {
2044     // When reading, we'll add it to the folding set of the following template.
2045     Record.AddDeclRef(D->getSpecializedTemplate()->getCanonicalDecl());
2046   }
2047 
2048   Code = serialization::DECL_VAR_TEMPLATE_SPECIALIZATION;
2049 }
2050 
2051 void ASTDeclWriter::VisitVarTemplatePartialSpecializationDecl(
2052     VarTemplatePartialSpecializationDecl *D) {
2053   Record.AddTemplateParameterList(D->getTemplateParameters());
2054 
2055   VisitVarTemplateSpecializationDecl(D);
2056 
2057   // These are read/set from/to the first declaration.
2058   if (D->getPreviousDecl() == nullptr) {
2059     Record.AddDeclRef(D->getInstantiatedFromMember());
2060     Record.push_back(D->isMemberSpecialization());
2061   }
2062 
2063   Code = serialization::DECL_VAR_TEMPLATE_PARTIAL_SPECIALIZATION;
2064 }
2065 
2066 void ASTDeclWriter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
2067   VisitRedeclarableTemplateDecl(D);
2068 
2069   if (D->isFirstDecl())
2070     AddTemplateSpecializations(D);
2071   Code = serialization::DECL_FUNCTION_TEMPLATE;
2072 }
2073 
2074 void ASTDeclWriter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
2075   Record.push_back(D->hasTypeConstraint());
2076   VisitTypeDecl(D);
2077 
2078   Record.push_back(D->wasDeclaredWithTypename());
2079 
2080   const TypeConstraint *TC = D->getTypeConstraint();
2081   if (D->hasTypeConstraint())
2082     Record.push_back(/*TypeConstraintInitialized=*/TC != nullptr);
2083   if (TC) {
2084     auto *CR = TC->getConceptReference();
2085     Record.push_back(CR != nullptr);
2086     if (CR)
2087       Record.AddConceptReference(CR);
2088     Record.AddStmt(TC->getImmediatelyDeclaredConstraint());
2089     Record.writeUnsignedOrNone(TC->getArgPackSubstIndex());
2090     Record.writeUnsignedOrNone(D->getNumExpansionParameters());
2091   }
2092 
2093   bool OwnsDefaultArg = D->hasDefaultArgument() &&
2094                         !D->defaultArgumentWasInherited();
2095   Record.push_back(OwnsDefaultArg);
2096   if (OwnsDefaultArg)
2097     Record.AddTemplateArgumentLoc(D->getDefaultArgument());
2098 
2099   if (!D->hasTypeConstraint() && !OwnsDefaultArg &&
2100       D->getDeclContext() == D->getLexicalDeclContext() &&
2101       !D->isInvalidDecl() && !D->hasAttrs() &&
2102       !D->isTopLevelDeclInObjCContainer() && !D->isImplicit() &&
2103       D->getDeclName().getNameKind() == DeclarationName::Identifier)
2104     AbbrevToUse = Writer.getDeclTemplateTypeParmAbbrev();
2105 
2106   Code = serialization::DECL_TEMPLATE_TYPE_PARM;
2107 }
2108 
2109 void ASTDeclWriter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
2110   // For an expanded parameter pack, record the number of expansion types here
2111   // so that it's easier for deserialization to allocate the right amount of
2112   // memory.
2113   Record.push_back(D->hasPlaceholderTypeConstraint());
2114   if (D->isExpandedParameterPack())
2115     Record.push_back(D->getNumExpansionTypes());
2116 
2117   VisitDeclaratorDecl(D);
2118   // TemplateParmPosition.
2119   Record.push_back(D->getDepth());
2120   Record.push_back(D->getPosition());
2121 
2122   if (D->hasPlaceholderTypeConstraint())
2123     Record.AddStmt(D->getPlaceholderTypeConstraint());
2124 
2125   if (D->isExpandedParameterPack()) {
2126     for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
2127       Record.AddTypeRef(D->getExpansionType(I));
2128       Record.AddTypeSourceInfo(D->getExpansionTypeSourceInfo(I));
2129     }
2130 
2131     Code = serialization::DECL_EXPANDED_NON_TYPE_TEMPLATE_PARM_PACK;
2132   } else {
2133     // Rest of NonTypeTemplateParmDecl.
2134     Record.push_back(D->isParameterPack());
2135     bool OwnsDefaultArg = D->hasDefaultArgument() &&
2136                           !D->defaultArgumentWasInherited();
2137     Record.push_back(OwnsDefaultArg);
2138     if (OwnsDefaultArg)
2139       Record.AddTemplateArgumentLoc(D->getDefaultArgument());
2140     Code = serialization::DECL_NON_TYPE_TEMPLATE_PARM;
2141   }
2142 }
2143 
2144 void ASTDeclWriter::VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
2145   // For an expanded parameter pack, record the number of expansion types here
2146   // so that it's easier for deserialization to allocate the right amount of
2147   // memory.
2148   if (D->isExpandedParameterPack())
2149     Record.push_back(D->getNumExpansionTemplateParameters());
2150 
2151   VisitTemplateDecl(D);
2152   Record.push_back(D->wasDeclaredWithTypename());
2153   // TemplateParmPosition.
2154   Record.push_back(D->getDepth());
2155   Record.push_back(D->getPosition());
2156 
2157   if (D->isExpandedParameterPack()) {
2158     for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
2159          I != N; ++I)
2160       Record.AddTemplateParameterList(D->getExpansionTemplateParameters(I));
2161     Code = serialization::DECL_EXPANDED_TEMPLATE_TEMPLATE_PARM_PACK;
2162   } else {
2163     // Rest of TemplateTemplateParmDecl.
2164     Record.push_back(D->isParameterPack());
2165     bool OwnsDefaultArg = D->hasDefaultArgument() &&
2166                           !D->defaultArgumentWasInherited();
2167     Record.push_back(OwnsDefaultArg);
2168     if (OwnsDefaultArg)
2169       Record.AddTemplateArgumentLoc(D->getDefaultArgument());
2170     Code = serialization::DECL_TEMPLATE_TEMPLATE_PARM;
2171   }
2172 }
2173 
2174 void ASTDeclWriter::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
2175   VisitRedeclarableTemplateDecl(D);
2176   Code = serialization::DECL_TYPE_ALIAS_TEMPLATE;
2177 }
2178 
2179 void ASTDeclWriter::VisitStaticAssertDecl(StaticAssertDecl *D) {
2180   VisitDecl(D);
2181   Record.AddStmt(D->getAssertExpr());
2182   Record.push_back(D->isFailed());
2183   Record.AddStmt(D->getMessage());
2184   Record.AddSourceLocation(D->getRParenLoc());
2185   Code = serialization::DECL_STATIC_ASSERT;
2186 }
2187 
2188 /// Emit the DeclContext part of a declaration context decl.
2189 void ASTDeclWriter::VisitDeclContext(DeclContext *DC) {
2190   static_assert(DeclContext::NumDeclContextBits == 13,
2191                 "You need to update the serializer after you change the "
2192                 "DeclContextBits");
2193   LookupBlockOffsets Offsets;
2194 
2195   if (Writer.isGeneratingReducedBMI() && isa<NamespaceDecl>(DC) &&
2196       cast<NamespaceDecl>(DC)->isFromExplicitGlobalModule()) {
2197     // In reduced BMI, delay writing lexical and visible block for namespace
2198     // in the global module fragment. See the comments of DelayedNamespace for
2199     // details.
2200     Writer.DelayedNamespace.push_back(cast<NamespaceDecl>(DC));
2201   } else {
2202     Offsets.LexicalOffset =
2203         Writer.WriteDeclContextLexicalBlock(Record.getASTContext(), DC);
2204     Writer.WriteDeclContextVisibleBlock(Record.getASTContext(), DC, Offsets);
2205   }
2206 
2207   Record.AddLookupOffsets(Offsets);
2208 }
2209 
2210 const Decl *ASTWriter::getFirstLocalDecl(const Decl *D) {
2211   assert(IsLocalDecl(D) && "expected a local declaration");
2212 
2213   const Decl *Canon = D->getCanonicalDecl();
2214   if (IsLocalDecl(Canon))
2215     return Canon;
2216 
2217   const Decl *&CacheEntry = FirstLocalDeclCache[Canon];
2218   if (CacheEntry)
2219     return CacheEntry;
2220 
2221   for (const Decl *Redecl = D; Redecl; Redecl = Redecl->getPreviousDecl())
2222     if (IsLocalDecl(Redecl))
2223       D = Redecl;
2224   return CacheEntry = D;
2225 }
2226 
2227 template <typename T>
2228 void ASTDeclWriter::VisitRedeclarable(Redeclarable<T> *D) {
2229   T *First = D->getFirstDecl();
2230   T *MostRecent = First->getMostRecentDecl();
2231   T *DAsT = static_cast<T *>(D);
2232   if (MostRecent != First) {
2233     assert(isRedeclarableDeclKind(DAsT->getKind()) &&
2234            "Not considered redeclarable?");
2235 
2236     Record.AddDeclRef(First);
2237 
2238     // Write out a list of local redeclarations of this declaration if it's the
2239     // first local declaration in the chain.
2240     const Decl *FirstLocal = Writer.getFirstLocalDecl(DAsT);
2241     if (DAsT == FirstLocal) {
2242       // Emit a list of all imported first declarations so that we can be sure
2243       // that all redeclarations visible to this module are before D in the
2244       // redecl chain.
2245       unsigned I = Record.size();
2246       Record.push_back(0);
2247       if (Writer.Chain)
2248         AddFirstDeclFromEachModule(DAsT, /*IncludeLocal*/false);
2249       // This is the number of imported first declarations + 1.
2250       Record[I] = Record.size() - I;
2251 
2252       // Collect the set of local redeclarations of this declaration, from
2253       // newest to oldest.
2254       ASTWriter::RecordData LocalRedecls;
2255       ASTRecordWriter LocalRedeclWriter(Record, LocalRedecls);
2256       for (const Decl *Prev = FirstLocal->getMostRecentDecl();
2257            Prev != FirstLocal; Prev = Prev->getPreviousDecl())
2258         if (!Prev->isFromASTFile())
2259           LocalRedeclWriter.AddDeclRef(Prev);
2260 
2261       // If we have any redecls, write them now as a separate record preceding
2262       // the declaration itself.
2263       if (LocalRedecls.empty())
2264         Record.push_back(0);
2265       else
2266         Record.AddOffset(LocalRedeclWriter.Emit(LOCAL_REDECLARATIONS));
2267     } else {
2268       Record.push_back(0);
2269       Record.AddDeclRef(FirstLocal);
2270     }
2271 
2272     // Make sure that we serialize both the previous and the most-recent
2273     // declarations, which (transitively) ensures that all declarations in the
2274     // chain get serialized.
2275     //
2276     // FIXME: This is not correct; when we reach an imported declaration we
2277     // won't emit its previous declaration.
2278     (void)Writer.GetDeclRef(D->getPreviousDecl());
2279     (void)Writer.GetDeclRef(MostRecent);
2280   } else {
2281     // We use the sentinel value 0 to indicate an only declaration.
2282     Record.push_back(0);
2283   }
2284 }
2285 
2286 void ASTDeclWriter::VisitHLSLBufferDecl(HLSLBufferDecl *D) {
2287   VisitNamedDecl(D);
2288   VisitDeclContext(D);
2289   Record.push_back(D->isCBuffer());
2290   Record.AddSourceLocation(D->getLocStart());
2291   Record.AddSourceLocation(D->getLBraceLoc());
2292   Record.AddSourceLocation(D->getRBraceLoc());
2293 
2294   Code = serialization::DECL_HLSL_BUFFER;
2295 }
2296 
2297 void ASTDeclWriter::VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D) {
2298   Record.writeOMPChildren(D->Data);
2299   VisitDecl(D);
2300   Code = serialization::DECL_OMP_THREADPRIVATE;
2301 }
2302 
2303 void ASTDeclWriter::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
2304   Record.writeOMPChildren(D->Data);
2305   VisitDecl(D);
2306   Code = serialization::DECL_OMP_ALLOCATE;
2307 }
2308 
2309 void ASTDeclWriter::VisitOMPRequiresDecl(OMPRequiresDecl *D) {
2310   Record.writeOMPChildren(D->Data);
2311   VisitDecl(D);
2312   Code = serialization::DECL_OMP_REQUIRES;
2313 }
2314 
2315 void ASTDeclWriter::VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D) {
2316   static_assert(DeclContext::NumOMPDeclareReductionDeclBits == 15,
2317                 "You need to update the serializer after you change the "
2318                 "NumOMPDeclareReductionDeclBits");
2319 
2320   VisitValueDecl(D);
2321   Record.AddSourceLocation(D->getBeginLoc());
2322   Record.AddStmt(D->getCombinerIn());
2323   Record.AddStmt(D->getCombinerOut());
2324   Record.AddStmt(D->getCombiner());
2325   Record.AddStmt(D->getInitOrig());
2326   Record.AddStmt(D->getInitPriv());
2327   Record.AddStmt(D->getInitializer());
2328   Record.push_back(llvm::to_underlying(D->getInitializerKind()));
2329   Record.AddDeclRef(D->getPrevDeclInScope());
2330   Code = serialization::DECL_OMP_DECLARE_REDUCTION;
2331 }
2332 
2333 void ASTDeclWriter::VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D) {
2334   Record.writeOMPChildren(D->Data);
2335   VisitValueDecl(D);
2336   Record.AddDeclarationName(D->getVarName());
2337   Record.AddDeclRef(D->getPrevDeclInScope());
2338   Code = serialization::DECL_OMP_DECLARE_MAPPER;
2339 }
2340 
2341 void ASTDeclWriter::VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D) {
2342   VisitVarDecl(D);
2343   Code = serialization::DECL_OMP_CAPTUREDEXPR;
2344 }
2345 
2346 void ASTDeclWriter::VisitOpenACCDeclareDecl(OpenACCDeclareDecl *D) {
2347   Record.writeUInt32(D->clauses().size());
2348   VisitDecl(D);
2349   Record.writeEnum(D->DirKind);
2350   Record.AddSourceLocation(D->DirectiveLoc);
2351   Record.AddSourceLocation(D->EndLoc);
2352   Record.writeOpenACCClauseList(D->clauses());
2353   Code = serialization::DECL_OPENACC_DECLARE;
2354 }
2355 void ASTDeclWriter::VisitOpenACCRoutineDecl(OpenACCRoutineDecl *D) {
2356   Record.writeUInt32(D->clauses().size());
2357   VisitDecl(D);
2358   Record.writeEnum(D->DirKind);
2359   Record.AddSourceLocation(D->DirectiveLoc);
2360   Record.AddSourceLocation(D->EndLoc);
2361   Record.AddSourceRange(D->ParensLoc);
2362   Record.AddStmt(D->FuncRef);
2363   Record.writeOpenACCClauseList(D->clauses());
2364   Code = serialization::DECL_OPENACC_ROUTINE;
2365 }
2366 
2367 //===----------------------------------------------------------------------===//
2368 // ASTWriter Implementation
2369 //===----------------------------------------------------------------------===//
2370 
2371 namespace {
2372 template <FunctionDecl::TemplatedKind Kind>
2373 std::shared_ptr<llvm::BitCodeAbbrev>
2374 getFunctionDeclAbbrev(serialization::DeclCode Code) {
2375   using namespace llvm;
2376 
2377   auto Abv = std::make_shared<BitCodeAbbrev>();
2378   Abv->Add(BitCodeAbbrevOp(Code));
2379   // RedeclarableDecl
2380   Abv->Add(BitCodeAbbrevOp(0)); // CanonicalDecl
2381   Abv->Add(BitCodeAbbrevOp(Kind));
2382   if constexpr (Kind == FunctionDecl::TK_NonTemplate) {
2383 
2384   } else if constexpr (Kind == FunctionDecl::TK_FunctionTemplate) {
2385     // DescribedFunctionTemplate
2386     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2387   } else if constexpr (Kind == FunctionDecl::TK_DependentNonTemplate) {
2388     // Instantiated From Decl
2389     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2390   } else if constexpr (Kind == FunctionDecl::TK_MemberSpecialization) {
2391     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InstantiatedFrom
2392     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2393                              3)); // TemplateSpecializationKind
2394     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Specialized Location
2395   } else if constexpr (Kind ==
2396                        FunctionDecl::TK_FunctionTemplateSpecialization) {
2397     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Template
2398     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2399                              3)); // TemplateSpecializationKind
2400     Abv->Add(BitCodeAbbrevOp(1)); // Template Argument Size
2401     Abv->Add(BitCodeAbbrevOp(TemplateArgument::Type)); // Template Argument Kind
2402     Abv->Add(
2403         BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Template Argument Type
2404     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Is Defaulted
2405     Abv->Add(BitCodeAbbrevOp(0)); // TemplateArgumentsAsWritten
2406     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SourceLocation
2407     Abv->Add(BitCodeAbbrevOp(0));
2408     Abv->Add(
2409         BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Canonical Decl of template
2410   } else if constexpr (Kind == FunctionDecl::
2411                                    TK_DependentFunctionTemplateSpecialization) {
2412     // Candidates of specialization
2413     Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2414     Abv->Add(BitCodeAbbrevOp(0)); // TemplateArgumentsAsWritten
2415   } else {
2416     llvm_unreachable("Unknown templated kind?");
2417   }
2418   // Decl
2419   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2420                            8)); // Packed DeclBits: ModuleOwnershipKind,
2421                                 // isUsed, isReferenced,  AccessSpecifier,
2422                                 // isImplicit
2423                                 //
2424                                 // The following bits should be 0:
2425                                 // HasStandaloneLexicalDC, HasAttrs,
2426                                 // TopLevelDeclInObjCContainer,
2427                                 // isInvalidDecl
2428   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2429   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2430   // NamedDecl
2431   Abv->Add(BitCodeAbbrevOp(DeclarationName::Identifier)); // NameKind
2432   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));     // Identifier
2433   Abv->Add(BitCodeAbbrevOp(0));                           // AnonDeclNumber
2434   // ValueDecl
2435   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2436   // DeclaratorDecl
2437   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerLocStart
2438   Abv->Add(BitCodeAbbrevOp(0));                       // HasExtInfo
2439   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TSIType
2440   // FunctionDecl
2441   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 11)); // IDNS
2442   Abv->Add(BitCodeAbbrevOp(
2443       BitCodeAbbrevOp::Fixed,
2444       28)); // Packed Function Bits: StorageClass, Inline, InlineSpecified,
2445             // VirtualAsWritten, Pure, HasInheritedProto, HasWrittenProto,
2446             // Deleted, Trivial, TrivialForCall, Defaulted, ExplicitlyDefaulted,
2447             // IsIneligibleOrNotSelected, ImplicitReturnZero, Constexpr,
2448             // UsesSEHTry, SkippedBody, MultiVersion, LateParsed,
2449             // FriendConstraintRefersToEnclosingTemplate, Linkage,
2450             // ShouldSkipCheckingODR
2451   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // LocEnd
2452   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // ODRHash
2453   // This Array slurps the rest of the record. Fortunately we want to encode
2454   // (nearly) all the remaining (variable number of) fields in the same way.
2455   //
2456   // This is:
2457   //         NumParams and Params[] from FunctionDecl, and
2458   //         NumOverriddenMethods, OverriddenMethods[] from CXXMethodDecl.
2459   //
2460   //  Add an AbbrevOp for 'size then elements' and use it here.
2461   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2462   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2463   return Abv;
2464 }
2465 
2466 template <FunctionDecl::TemplatedKind Kind>
2467 std::shared_ptr<llvm::BitCodeAbbrev> getCXXMethodAbbrev() {
2468   return getFunctionDeclAbbrev<Kind>(serialization::DECL_CXX_METHOD);
2469 }
2470 } // namespace
2471 
2472 void ASTWriter::WriteDeclAbbrevs() {
2473   using namespace llvm;
2474 
2475   std::shared_ptr<BitCodeAbbrev> Abv;
2476 
2477   // Abbreviation for DECL_FIELD
2478   Abv = std::make_shared<BitCodeAbbrev>();
2479   Abv->Add(BitCodeAbbrevOp(serialization::DECL_FIELD));
2480   // Decl
2481   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2482                            7)); // Packed DeclBits: ModuleOwnershipKind,
2483                                 // isUsed, isReferenced,  AccessSpecifier,
2484                                 //
2485                                 // The following bits should be 0:
2486                                 // isImplicit, HasStandaloneLexicalDC, HasAttrs,
2487                                 // TopLevelDeclInObjCContainer,
2488                                 // isInvalidDecl
2489   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2490   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2491   // NamedDecl
2492   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2493   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2494   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2495   // ValueDecl
2496   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2497   // DeclaratorDecl
2498   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
2499   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
2500   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TSIType
2501   // FieldDecl
2502   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
2503   Abv->Add(BitCodeAbbrevOp(0));                       // StorageKind
2504   // Type Source Info
2505   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2506   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
2507   DeclFieldAbbrev = Stream.EmitAbbrev(std::move(Abv));
2508 
2509   // Abbreviation for DECL_OBJC_IVAR
2510   Abv = std::make_shared<BitCodeAbbrev>();
2511   Abv->Add(BitCodeAbbrevOp(serialization::DECL_OBJC_IVAR));
2512   // Decl
2513   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2514                            12)); // Packed DeclBits: HasStandaloneLexicalDC,
2515                                  // isInvalidDecl, HasAttrs, isImplicit, isUsed,
2516                                  // isReferenced, TopLevelDeclInObjCContainer,
2517                                  // AccessSpecifier, ModuleOwnershipKind
2518   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2519   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2520   // NamedDecl
2521   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2522   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2523   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2524   // ValueDecl
2525   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2526   // DeclaratorDecl
2527   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
2528   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
2529   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TSIType
2530   // FieldDecl
2531   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
2532   Abv->Add(BitCodeAbbrevOp(0));                       // InitStyle
2533   // ObjC Ivar
2534   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getAccessControl
2535   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getSynthesize
2536   // Type Source Info
2537   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2538   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
2539   DeclObjCIvarAbbrev = Stream.EmitAbbrev(std::move(Abv));
2540 
2541   // Abbreviation for DECL_ENUM
2542   Abv = std::make_shared<BitCodeAbbrev>();
2543   Abv->Add(BitCodeAbbrevOp(serialization::DECL_ENUM));
2544   // Redeclarable
2545   Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
2546   // Decl
2547   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2548                            7)); // Packed DeclBits: ModuleOwnershipKind,
2549                                 // isUsed, isReferenced,  AccessSpecifier,
2550                                 //
2551                                 // The following bits should be 0:
2552                                 // isImplicit, HasStandaloneLexicalDC, HasAttrs,
2553                                 // TopLevelDeclInObjCContainer,
2554                                 // isInvalidDecl
2555   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2556   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2557   // NamedDecl
2558   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2559   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2560   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2561   // TypeDecl
2562   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2563   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
2564   // TagDecl
2565   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IdentifierNamespace
2566   Abv->Add(BitCodeAbbrevOp(
2567       BitCodeAbbrevOp::Fixed,
2568       9)); // Packed Tag Decl Bits: getTagKind, isCompleteDefinition,
2569            // EmbeddedInDeclarator, IsFreeStanding,
2570            // isCompleteDefinitionRequired, ExtInfoKind
2571   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
2572   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
2573   // EnumDecl
2574   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddTypeRef
2575   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IntegerType
2576   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // getPromotionType
2577   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 20)); // Enum Decl Bits
2578   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));// ODRHash
2579   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // InstantiatedMembEnum
2580   // DC
2581   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LexicalOffset
2582   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // VisibleOffset
2583   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // ModuleLocalOffset
2584   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // TULocalOffset
2585   DeclEnumAbbrev = Stream.EmitAbbrev(std::move(Abv));
2586 
2587   // Abbreviation for DECL_RECORD
2588   Abv = std::make_shared<BitCodeAbbrev>();
2589   Abv->Add(BitCodeAbbrevOp(serialization::DECL_RECORD));
2590   // Redeclarable
2591   Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
2592   // Decl
2593   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2594                            7)); // Packed DeclBits: ModuleOwnershipKind,
2595                                 // isUsed, isReferenced,  AccessSpecifier,
2596                                 //
2597                                 // The following bits should be 0:
2598                                 // isImplicit, HasStandaloneLexicalDC, HasAttrs,
2599                                 // TopLevelDeclInObjCContainer,
2600                                 // isInvalidDecl
2601   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2602   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2603   // NamedDecl
2604   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2605   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2606   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2607   // TypeDecl
2608   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2609   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
2610   // TagDecl
2611   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // IdentifierNamespace
2612   Abv->Add(BitCodeAbbrevOp(
2613       BitCodeAbbrevOp::Fixed,
2614       9)); // Packed Tag Decl Bits: getTagKind, isCompleteDefinition,
2615            // EmbeddedInDeclarator, IsFreeStanding,
2616            // isCompleteDefinitionRequired, ExtInfoKind
2617   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
2618   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // SourceLocation
2619   // RecordDecl
2620   Abv->Add(BitCodeAbbrevOp(
2621       BitCodeAbbrevOp::Fixed,
2622       14)); // Packed Record Decl Bits: FlexibleArrayMember,
2623             // AnonymousStructUnion, hasObjectMember, hasVolatileMember,
2624             // isNonTrivialToPrimitiveDefaultInitialize,
2625             // isNonTrivialToPrimitiveCopy, isNonTrivialToPrimitiveDestroy,
2626             // hasNonTrivialToPrimitiveDefaultInitializeCUnion,
2627             // hasNonTrivialToPrimitiveDestructCUnion,
2628             // hasNonTrivialToPrimitiveCopyCUnion,
2629             // hasUninitializedExplicitInitFields, isParamDestroyedInCallee,
2630             // getArgPassingRestrictions
2631   // ODRHash
2632   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 26));
2633 
2634   // DC
2635   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // LexicalOffset
2636   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // VisibleOffset
2637   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // ModuleLocalOffset
2638   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // TULocalOffset
2639   DeclRecordAbbrev = Stream.EmitAbbrev(std::move(Abv));
2640 
2641   // Abbreviation for DECL_PARM_VAR
2642   Abv = std::make_shared<BitCodeAbbrev>();
2643   Abv->Add(BitCodeAbbrevOp(serialization::DECL_PARM_VAR));
2644   // Redeclarable
2645   Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
2646   // Decl
2647   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2648                            8)); // Packed DeclBits: ModuleOwnershipKind, isUsed,
2649                                 // isReferenced, AccessSpecifier,
2650                                 // HasStandaloneLexicalDC, HasAttrs, isImplicit,
2651                                 // TopLevelDeclInObjCContainer,
2652                                 // isInvalidDecl,
2653   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2654   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2655   // NamedDecl
2656   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2657   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2658   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2659   // ValueDecl
2660   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2661   // DeclaratorDecl
2662   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
2663   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
2664   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TSIType
2665   // VarDecl
2666   Abv->Add(
2667       BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2668                       12)); // Packed Var Decl bits: SClass, TSCSpec, InitStyle,
2669                             // isARCPseudoStrong, Linkage, ModulesCodegen
2670   Abv->Add(BitCodeAbbrevOp(0));                          // VarKind (local enum)
2671   // ParmVarDecl
2672   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ScopeIndex
2673   Abv->Add(BitCodeAbbrevOp(
2674       BitCodeAbbrevOp::Fixed,
2675       19)); // Packed Parm Var Decl bits: IsObjCMethodParameter, ScopeDepth,
2676             // ObjCDeclQualifier, KNRPromoted,
2677             // HasInheritedDefaultArg, HasUninstantiatedDefaultArg
2678   // Type Source Info
2679   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2680   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
2681   DeclParmVarAbbrev = Stream.EmitAbbrev(std::move(Abv));
2682 
2683   // Abbreviation for DECL_TYPEDEF
2684   Abv = std::make_shared<BitCodeAbbrev>();
2685   Abv->Add(BitCodeAbbrevOp(serialization::DECL_TYPEDEF));
2686   // Redeclarable
2687   Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
2688   // Decl
2689   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2690                            7)); // Packed DeclBits: ModuleOwnershipKind,
2691                                 // isReferenced, isUsed, AccessSpecifier. Other
2692                                 // higher bits should be 0: isImplicit,
2693                                 // HasStandaloneLexicalDC, HasAttrs,
2694                                 // TopLevelDeclInObjCContainer, isInvalidDecl
2695   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2696   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2697   // NamedDecl
2698   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2699   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2700   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2701   // TypeDecl
2702   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2703   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
2704   // TypedefDecl
2705   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2706   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
2707   DeclTypedefAbbrev = Stream.EmitAbbrev(std::move(Abv));
2708 
2709   // Abbreviation for DECL_VAR
2710   Abv = std::make_shared<BitCodeAbbrev>();
2711   Abv->Add(BitCodeAbbrevOp(serialization::DECL_VAR));
2712   // Redeclarable
2713   Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
2714   // Decl
2715   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2716                            12)); // Packed DeclBits: HasStandaloneLexicalDC,
2717                                  // isInvalidDecl, HasAttrs, isImplicit, isUsed,
2718                                  // isReferenced, TopLevelDeclInObjCContainer,
2719                                  // AccessSpecifier, ModuleOwnershipKind
2720   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2721   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2722   // NamedDecl
2723   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2724   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2725   Abv->Add(BitCodeAbbrevOp(0));                       // AnonDeclNumber
2726   // ValueDecl
2727   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2728   // DeclaratorDecl
2729   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
2730   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
2731   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TSIType
2732   // VarDecl
2733   Abv->Add(BitCodeAbbrevOp(
2734       BitCodeAbbrevOp::Fixed,
2735       22)); // Packed Var Decl bits:  Linkage, ModulesCodegen,
2736             // SClass, TSCSpec, InitStyle,
2737             // isARCPseudoStrong, IsThisDeclarationADemotedDefinition,
2738             // isExceptionVariable, isNRVOVariable, isCXXForRangeDecl,
2739             // isInline, isInlineSpecified, isConstexpr,
2740             // isInitCapture, isPrevDeclInSameScope, hasInitWithSideEffects,
2741             // EscapingByref, HasDeducedType, ImplicitParamKind, isObjCForDecl
2742             // IsCXXForRangeImplicitVar
2743   Abv->Add(BitCodeAbbrevOp(0));                         // VarKind (local enum)
2744   // Type Source Info
2745   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2746   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
2747   DeclVarAbbrev = Stream.EmitAbbrev(std::move(Abv));
2748 
2749   // Abbreviation for DECL_CXX_METHOD
2750   DeclCXXMethodAbbrev =
2751       Stream.EmitAbbrev(getCXXMethodAbbrev<FunctionDecl::TK_NonTemplate>());
2752   DeclTemplateCXXMethodAbbrev = Stream.EmitAbbrev(
2753       getCXXMethodAbbrev<FunctionDecl::TK_FunctionTemplate>());
2754   DeclDependentNonTemplateCXXMethodAbbrev = Stream.EmitAbbrev(
2755       getCXXMethodAbbrev<FunctionDecl::TK_DependentNonTemplate>());
2756   DeclMemberSpecializedCXXMethodAbbrev = Stream.EmitAbbrev(
2757       getCXXMethodAbbrev<FunctionDecl::TK_MemberSpecialization>());
2758   DeclTemplateSpecializedCXXMethodAbbrev = Stream.EmitAbbrev(
2759       getCXXMethodAbbrev<FunctionDecl::TK_FunctionTemplateSpecialization>());
2760   DeclDependentSpecializationCXXMethodAbbrev = Stream.EmitAbbrev(
2761       getCXXMethodAbbrev<
2762           FunctionDecl::TK_DependentFunctionTemplateSpecialization>());
2763 
2764   // Abbreviation for DECL_TEMPLATE_TYPE_PARM
2765   Abv = std::make_shared<BitCodeAbbrev>();
2766   Abv->Add(BitCodeAbbrevOp(serialization::DECL_TEMPLATE_TYPE_PARM));
2767   Abv->Add(BitCodeAbbrevOp(0)); // hasTypeConstraint
2768   // Decl
2769   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2770                            7)); // Packed DeclBits: ModuleOwnershipKind,
2771                                 // isReferenced, isUsed, AccessSpecifier. Other
2772                                 // higher bits should be 0: isImplicit,
2773                                 // HasStandaloneLexicalDC, HasAttrs,
2774                                 // TopLevelDeclInObjCContainer, isInvalidDecl
2775   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2776   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2777   // NamedDecl
2778   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2779   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2780   Abv->Add(BitCodeAbbrevOp(0));
2781   // TypeDecl
2782   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2783   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type Ref
2784   // TemplateTypeParmDecl
2785   Abv->Add(
2786       BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // wasDeclaredWithTypename
2787   Abv->Add(BitCodeAbbrevOp(0));                    // OwnsDefaultArg
2788   DeclTemplateTypeParmAbbrev = Stream.EmitAbbrev(std::move(Abv));
2789 
2790   // Abbreviation for DECL_USING_SHADOW
2791   Abv = std::make_shared<BitCodeAbbrev>();
2792   Abv->Add(BitCodeAbbrevOp(serialization::DECL_USING_SHADOW));
2793   // Redeclarable
2794   Abv->Add(BitCodeAbbrevOp(0)); // No redeclaration
2795   // Decl
2796   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2797                            12)); // Packed DeclBits: HasStandaloneLexicalDC,
2798                                  // isInvalidDecl, HasAttrs, isImplicit, isUsed,
2799                                  // isReferenced, TopLevelDeclInObjCContainer,
2800                                  // AccessSpecifier, ModuleOwnershipKind
2801   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
2802   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // SubmoduleID
2803   // NamedDecl
2804   Abv->Add(BitCodeAbbrevOp(0));                       // NameKind = Identifier
2805   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Name
2806   Abv->Add(BitCodeAbbrevOp(0));
2807   // UsingShadowDecl
2808   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // TargetDecl
2809   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 11)); // IDNS
2810   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // UsingOrNextShadow
2811   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR,
2812                            6)); // InstantiatedFromUsingShadowDecl
2813   DeclUsingShadowAbbrev = Stream.EmitAbbrev(std::move(Abv));
2814 
2815   // Abbreviation for EXPR_DECL_REF
2816   Abv = std::make_shared<BitCodeAbbrev>();
2817   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_DECL_REF));
2818   // Stmt
2819   //  Expr
2820   //  PackingBits: DependenceKind, ValueKind. ObjectKind should be 0.
2821   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2822   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2823   // DeclRefExpr
2824   // Packing Bits: , HadMultipleCandidates, RefersToEnclosingVariableOrCapture,
2825   // IsImmediateEscalating, NonOdrUseReason.
2826   // GetDeclFound, HasQualifier and ExplicitTemplateArgs should be 0.
2827   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5));
2828   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclRef
2829   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
2830   DeclRefExprAbbrev = Stream.EmitAbbrev(std::move(Abv));
2831 
2832   // Abbreviation for EXPR_INTEGER_LITERAL
2833   Abv = std::make_shared<BitCodeAbbrev>();
2834   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_INTEGER_LITERAL));
2835   //Stmt
2836   // Expr
2837   // DependenceKind, ValueKind, ObjectKind
2838   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2839   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2840   // Integer Literal
2841   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
2842   Abv->Add(BitCodeAbbrevOp(32));                      // Bit Width
2843   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Value
2844   IntegerLiteralAbbrev = Stream.EmitAbbrev(std::move(Abv));
2845 
2846   // Abbreviation for EXPR_CHARACTER_LITERAL
2847   Abv = std::make_shared<BitCodeAbbrev>();
2848   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_CHARACTER_LITERAL));
2849   //Stmt
2850   // Expr
2851   // DependenceKind, ValueKind, ObjectKind
2852   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2853   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2854   // Character Literal
2855   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getValue
2856   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Location
2857   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); // getKind
2858   CharacterLiteralAbbrev = Stream.EmitAbbrev(std::move(Abv));
2859 
2860   // Abbreviation for EXPR_IMPLICIT_CAST
2861   Abv = std::make_shared<BitCodeAbbrev>();
2862   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_IMPLICIT_CAST));
2863   // Stmt
2864   // Expr
2865   // Packing Bits: DependenceKind, ValueKind, ObjectKind,
2866   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2867   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2868   // CastExpr
2869   Abv->Add(BitCodeAbbrevOp(0)); // PathSize
2870   // Packing Bits: CastKind, StoredFPFeatures, isPartOfExplicitCast
2871   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 9));
2872   // ImplicitCastExpr
2873   ExprImplicitCastAbbrev = Stream.EmitAbbrev(std::move(Abv));
2874 
2875   // Abbreviation for EXPR_BINARY_OPERATOR
2876   Abv = std::make_shared<BitCodeAbbrev>();
2877   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_BINARY_OPERATOR));
2878   // Stmt
2879   // Expr
2880   // Packing Bits: DependenceKind. ValueKind and ObjectKind should
2881   // be 0 in this case.
2882   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5));
2883   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2884   // BinaryOperator
2885   Abv->Add(
2886       BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // OpCode and HasFPFeatures
2887   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2888   BinaryOperatorAbbrev = Stream.EmitAbbrev(std::move(Abv));
2889 
2890   // Abbreviation for EXPR_COMPOUND_ASSIGN_OPERATOR
2891   Abv = std::make_shared<BitCodeAbbrev>();
2892   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_COMPOUND_ASSIGN_OPERATOR));
2893   // Stmt
2894   // Expr
2895   // Packing Bits: DependenceKind. ValueKind and ObjectKind should
2896   // be 0 in this case.
2897   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5));
2898   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2899   // BinaryOperator
2900   // Packing Bits: OpCode. The HasFPFeatures bit should be 0
2901   Abv->Add(
2902       BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // OpCode and HasFPFeatures
2903   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2904   // CompoundAssignOperator
2905   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHSType
2906   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Result Type
2907   CompoundAssignOperatorAbbrev = Stream.EmitAbbrev(std::move(Abv));
2908 
2909   // Abbreviation for EXPR_CALL
2910   Abv = std::make_shared<BitCodeAbbrev>();
2911   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_CALL));
2912   // Stmt
2913   // Expr
2914   // Packing Bits: DependenceKind, ValueKind, ObjectKind,
2915   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2916   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2917   // CallExpr
2918   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // NumArgs
2919   Abv->Add(BitCodeAbbrevOp(0));                       // ADLCallKind
2920   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2921   CallExprAbbrev = Stream.EmitAbbrev(std::move(Abv));
2922 
2923   // Abbreviation for EXPR_CXX_OPERATOR_CALL
2924   Abv = std::make_shared<BitCodeAbbrev>();
2925   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_CXX_OPERATOR_CALL));
2926   // Stmt
2927   // Expr
2928   // Packing Bits: DependenceKind, ValueKind, ObjectKind,
2929   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2930   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2931   // CallExpr
2932   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // NumArgs
2933   Abv->Add(BitCodeAbbrevOp(0));                       // ADLCallKind
2934   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2935   // CXXOperatorCallExpr
2936   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Operator Kind
2937   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2938   CXXOperatorCallExprAbbrev = Stream.EmitAbbrev(std::move(Abv));
2939 
2940   // Abbreviation for EXPR_CXX_MEMBER_CALL
2941   Abv = std::make_shared<BitCodeAbbrev>();
2942   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_CXX_MEMBER_CALL));
2943   // Stmt
2944   // Expr
2945   // Packing Bits: DependenceKind, ValueKind, ObjectKind,
2946   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 10));
2947   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
2948   // CallExpr
2949   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // NumArgs
2950   Abv->Add(BitCodeAbbrevOp(0));                       // ADLCallKind
2951   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2952   // CXXMemberCallExpr
2953   CXXMemberCallExprAbbrev = Stream.EmitAbbrev(std::move(Abv));
2954 
2955   // Abbreviation for STMT_COMPOUND
2956   Abv = std::make_shared<BitCodeAbbrev>();
2957   Abv->Add(BitCodeAbbrevOp(serialization::STMT_COMPOUND));
2958   // Stmt
2959   // CompoundStmt
2960   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Num Stmts
2961   Abv->Add(BitCodeAbbrevOp(0));                       // hasStoredFPFeatures
2962   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2963   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Source Location
2964   CompoundStmtAbbrev = Stream.EmitAbbrev(std::move(Abv));
2965 
2966   Abv = std::make_shared<BitCodeAbbrev>();
2967   Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_LEXICAL));
2968   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2969   DeclContextLexicalAbbrev = Stream.EmitAbbrev(std::move(Abv));
2970 
2971   Abv = std::make_shared<BitCodeAbbrev>();
2972   Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_VISIBLE));
2973   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2974   DeclContextVisibleLookupAbbrev = Stream.EmitAbbrev(std::move(Abv));
2975 
2976   Abv = std::make_shared<BitCodeAbbrev>();
2977   Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_MODULE_LOCAL_VISIBLE));
2978   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2979   DeclModuleLocalVisibleLookupAbbrev = Stream.EmitAbbrev(std::move(Abv));
2980 
2981   Abv = std::make_shared<BitCodeAbbrev>();
2982   Abv->Add(BitCodeAbbrevOp(serialization::DECL_CONTEXT_TU_LOCAL_VISIBLE));
2983   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2984   DeclTULocalLookupAbbrev = Stream.EmitAbbrev(std::move(Abv));
2985 
2986   Abv = std::make_shared<BitCodeAbbrev>();
2987   Abv->Add(BitCodeAbbrevOp(serialization::DECL_SPECIALIZATIONS));
2988   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2989   DeclSpecializationsAbbrev = Stream.EmitAbbrev(std::move(Abv));
2990 
2991   Abv = std::make_shared<BitCodeAbbrev>();
2992   Abv->Add(BitCodeAbbrevOp(serialization::DECL_PARTIAL_SPECIALIZATIONS));
2993   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
2994   DeclPartialSpecializationsAbbrev = Stream.EmitAbbrev(std::move(Abv));
2995 }
2996 
2997 /// isRequiredDecl - Check if this is a "required" Decl, which must be seen by
2998 /// consumers of the AST.
2999 ///
3000 /// Such decls will always be deserialized from the AST file, so we would like
3001 /// this to be as restrictive as possible. Currently the predicate is driven by
3002 /// code generation requirements, if other clients have a different notion of
3003 /// what is "required" then we may have to consider an alternate scheme where
3004 /// clients can iterate over the top-level decls and get information on them,
3005 /// without necessary deserializing them. We could explicitly require such
3006 /// clients to use a separate API call to "realize" the decl. This should be
3007 /// relatively painless since they would presumably only do it for top-level
3008 /// decls.
3009 static bool isRequiredDecl(const Decl *D, ASTContext &Context,
3010                            Module *WritingModule) {
3011   // Named modules have different semantics than header modules. Every named
3012   // module units owns a translation unit. So the importer of named modules
3013   // doesn't need to deserilize everything ahead of time.
3014   if (WritingModule && WritingModule->isNamedModule()) {
3015     // The PragmaCommentDecl and PragmaDetectMismatchDecl are MSVC's extension.
3016     // And the behavior of MSVC for such cases will leak this to the module
3017     // users. Given pragma is not a standard thing, the compiler has the space
3018     // to do their own decision. Let's follow MSVC here.
3019     if (isa<PragmaCommentDecl, PragmaDetectMismatchDecl>(D))
3020       return true;
3021     return false;
3022   }
3023 
3024   // An ObjCMethodDecl is never considered as "required" because its
3025   // implementation container always is.
3026 
3027   // File scoped assembly or obj-c or OMP declare target implementation must be
3028   // seen.
3029   if (isa<FileScopeAsmDecl, TopLevelStmtDecl, ObjCImplDecl>(D))
3030     return true;
3031 
3032   if (WritingModule && isPartOfPerModuleInitializer(D)) {
3033     // These declarations are part of the module initializer, and are emitted
3034     // if and when the module is imported, rather than being emitted eagerly.
3035     return false;
3036   }
3037 
3038   return Context.DeclMustBeEmitted(D);
3039 }
3040 
3041 void ASTWriter::WriteDecl(ASTContext &Context, Decl *D) {
3042   PrettyDeclStackTraceEntry CrashInfo(Context, D, SourceLocation(),
3043                                       "serializing");
3044 
3045   // Determine the ID for this declaration.
3046   LocalDeclID ID;
3047   assert(!D->isFromASTFile() && "should not be emitting imported decl");
3048   LocalDeclID &IDR = DeclIDs[D];
3049   if (IDR.isInvalid())
3050     IDR = NextDeclID++;
3051 
3052   ID = IDR;
3053 
3054   assert(ID >= FirstDeclID && "invalid decl ID");
3055 
3056   RecordData Record;
3057   ASTDeclWriter W(*this, Context, Record, GeneratingReducedBMI);
3058 
3059   // Build a record for this declaration
3060   W.Visit(D);
3061 
3062   // Emit this declaration to the bitstream.
3063   uint64_t Offset = W.Emit(D);
3064 
3065   // Record the offset for this declaration
3066   SourceLocation Loc = D->getLocation();
3067   SourceLocationEncoding::RawLocEncoding RawLoc =
3068       getRawSourceLocationEncoding(getAdjustedLocation(Loc));
3069 
3070   unsigned Index = ID.getRawValue() - FirstDeclID.getRawValue();
3071   if (DeclOffsets.size() == Index)
3072     DeclOffsets.emplace_back(RawLoc, Offset, DeclTypesBlockStartOffset);
3073   else if (DeclOffsets.size() < Index) {
3074     // FIXME: Can/should this happen?
3075     DeclOffsets.resize(Index+1);
3076     DeclOffsets[Index].setRawLoc(RawLoc);
3077     DeclOffsets[Index].setBitOffset(Offset, DeclTypesBlockStartOffset);
3078   } else {
3079     llvm_unreachable("declarations should be emitted in ID order");
3080   }
3081 
3082   SourceManager &SM = Context.getSourceManager();
3083   if (Loc.isValid() && SM.isLocalSourceLocation(Loc))
3084     associateDeclWithFile(D, ID);
3085 
3086   // Note declarations that should be deserialized eagerly so that we can add
3087   // them to a record in the AST file later.
3088   if (isRequiredDecl(D, Context, WritingModule))
3089     AddDeclRef(D, EagerlyDeserializedDecls);
3090 }
3091 
3092 void ASTRecordWriter::AddFunctionDefinition(const FunctionDecl *FD) {
3093   // Switch case IDs are per function body.
3094   Writer->ClearSwitchCaseIDs();
3095 
3096   assert(FD->doesThisDeclarationHaveABody());
3097   bool ModulesCodegen = shouldFunctionGenerateHereOnly(FD);
3098   Record->push_back(ModulesCodegen);
3099   if (ModulesCodegen)
3100     Writer->AddDeclRef(FD, Writer->ModularCodegenDecls);
3101   if (auto *CD = dyn_cast<CXXConstructorDecl>(FD)) {
3102     Record->push_back(CD->getNumCtorInitializers());
3103     if (CD->getNumCtorInitializers())
3104       AddCXXCtorInitializers(llvm::ArrayRef(CD->init_begin(), CD->init_end()));
3105   }
3106   AddStmt(FD->getBody());
3107 }
3108