Implement serialization/deserialization of feature variables

Author: ahatanaka

clang/include/clang/AST/ASTContext.h

@@ -808,10 +808,10 @@ class ASTContext : public RefCountedBase<ASTContext> {
     bool isInvalid() const { return Kind == FeatureAvailKind::None; }
   };
 
-  std::map<StringRef, AvailabilityDomainInfo> AvailabilityDomainMap;
+  std::map<StringRef, VarDecl *> AvailabilityDomainMap;
 
-  void addAvailabilityDomainMap(StringRef Name, AvailabilityDomainInfo Info) {
-    AvailabilityDomainMap[Name] = Info;
+  void addAvailabilityDomainMap(StringRef Name, VarDecl *VD) {
+    AvailabilityDomainMap[Name] = VD;
   }
 
   std::pair<DomainAvailabilityAttr *, bool>

clang/lib/AST/ASTContext.cpp

@@ -910,7 +910,7 @@ ASTContext::getFeatureAvailInfo(StringRef FeatureName) const {
 
   auto I = AvailabilityDomainMap.find(FeatureName);
   if (I != AvailabilityDomainMap.end())
-    return I->second;
+    return getFeatureAvailInfo(I->second).second;
 
   return {};
 }
@@ -13214,6 +13214,10 @@ bool ASTContext::DeclMustBeEmitted(const Decl *D) {
   const auto *VD = cast<VarDecl>(D);
   assert(VD->isFileVarDecl() && "Expected file scoped var");
 
+  // Variables annotated with availability_domain need to be deserialized.
+  if (VD->hasAttr<AvailabilityDomainAttr>())
+    return true;
+
   // If the decl is marked as `declare target to`, it should be emitted for the
   // host and for the device.
   if (LangOpts.OpenMP &&

clang/lib/Sema/SemaDecl.cpp

@@ -15649,11 +15649,8 @@ void Sema::FinalizeDeclaration(Decl *ThisDecl) {
     }
   }
 
-  std::pair<StringRef, ASTContext::AvailabilityDomainInfo> ADInfo =
-      getASTContext().getFeatureAvailInfo(VD);
-
-  if (!ADInfo.first.empty())
-    getASTContext().addAvailabilityDomainMap(ADInfo.first, ADInfo.second);
+  if (auto *Attr = VD->getAttr<AvailabilityDomainAttr>())
+    getASTContext().addAvailabilityDomainMap(Attr->getName()->getName(), VD);
 
   const DeclContext *DC = VD->getDeclContext();
   // If there's a #pragma GCC visibility in scope, and this isn't a class

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -1683,6 +1683,10 @@ ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) {
   }
   }
 
+  if (auto *Attr = VD->getAttr<AvailabilityDomainAttr>())
+    Reader.getContext().addAvailabilityDomainMap(Attr->getName()->getName(),
+                                                 VD);
+
   return Redecl;
 }