Cache visibility of decls.

This unifies the linkage and visibility caching. I first implemented this when
working on pr13844, but the previous fixes removed the performance advantage of
this one.

This is still a step in the right direction for making linkage and visibility
cheap to use.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171048 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 76 insertions, 48 deletions

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index e00779844c..bb75895df5 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -228,6 +228,12 @@ public:
              "Enum truncated!");
     }
 
+    bool operator==(const LinkageInfo &Other) {
+      return linkage_ == Other.linkage_ &&
+	visibility_ == Other.visibility_ &&
+	explicit_ == Other.explicit_;
+    }
+
     static LinkageInfo external() {
       return LinkageInfo();
     }
@@ -323,7 +329,7 @@ public:
 
   /// \brief Clear the linkage cache in response to a change
   /// to the declaration.
-  void ClearLinkageCache();
+  void ClearLVCache();
 
   /// \brief Looks through UsingDecls and ObjCCompatibleAliasDecls for
   /// the underlying named decl.
@@ -3319,7 +3325,7 @@ void Redeclarable<decl_type>::setPreviousDeclaration(decl_type *PrevDecl) {
   // First one will point to this one as latest.
   First->RedeclLink = LatestDeclLink(static_cast<decl_type*>(this));
   if (NamedDecl *ND = dyn_cast<NamedDecl>(static_cast<decl_type*>(this)))
-    ND->ClearLinkageCache();
+    ND->ClearLVCache();
 }
 
 // Inline function definitions.
diff --git a/include/clang/AST/DeclBase.h b/include/clang/AST/DeclBase.h
index e3fa41ef31..823340aeaf 100644
--- a/include/clang/AST/DeclBase.h
+++ b/include/clang/AST/DeclBase.h
@@ -241,7 +241,7 @@ private:
   SourceLocation Loc;
 
   /// DeclKind - This indicates which class this is.
-  unsigned DeclKind : 8;
+  unsigned DeclKind : 6;
 
   /// InvalidDecl - This indicates a semantic error occurred.
   unsigned InvalidDecl :  1;
@@ -283,15 +283,16 @@ protected:
   /// IdentifierNamespace - This specifies what IDNS_* namespace this lives in.
   unsigned IdentifierNamespace : 12;
 
-  /// \brief Whether the \c CachedLinkage field is active.
-  ///
-  /// This field is only valid for NamedDecls subclasses.
-  mutable unsigned HasCachedLinkage : 1;
-
-  /// \brief If \c HasCachedLinkage, the linkage of this declaration.
+  /// These fields are only valid for NamedDecls subclasses.
   ///
-  /// This field is only valid for NamedDecls subclasses.
+  /// \brief Nonzero if the cache (i.e. the bitfields here starting
+  /// with 'Cache') is valid.  If so, then this is a
+  /// LangOptions::VisibilityMode+1.
+  mutable unsigned CacheValidAndVisibility : 2;
+  /// \brief the linkage of this declaration.
   mutable unsigned CachedLinkage : 2;
+  /// \brief true if the visibility is explicit.
+  mutable unsigned CachedVisibilityExplicit : 1;
 
   friend class ASTDeclWriter;
   friend class ASTDeclReader;
@@ -308,7 +309,7 @@ protected:
       HasAttrs(false), Implicit(false), Used(false), Referenced(false),
       Access(AS_none), FromASTFile(0), Hidden(0),
       IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
-      HasCachedLinkage(0)
+      CacheValidAndVisibility(0)
   {
     if (StatisticsEnabled) add(DK);
   }
@@ -318,7 +319,7 @@ protected:
       HasAttrs(false), Implicit(false), Used(false), Referenced(false),
       Access(AS_none), FromASTFile(0), Hidden(0),
       IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
-      HasCachedLinkage(0)
+      CacheValidAndVisibility(0)
   {
     if (StatisticsEnabled) add(DK);
   }
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index cf3b565fc3..7277f0fc68 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1786,7 +1786,7 @@ public:
   std::pair<Linkage,Visibility> getLinkageAndVisibility() const;
 
   /// \brief Note that the linkage is no longer known.
-  void ClearLinkageCache();
+  void ClearLVCache();
 
   const char *getTypeClassName() const;
 
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index a2c6da67f0..a3cdb401ea 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -104,8 +104,14 @@ getLVForTemplateParameterList(const TemplateParameterList *Params) {
   return LV;
 }
 
-/// getLVForDecl - Get the linkage and visibility for the given declaration.
-static LinkageInfo getLVForDecl(const NamedDecl *D, bool OnlyTemplate);
+/// Compute the linkage and visibility for the given declaration.
+static LinkageInfo computeLVForDecl(const NamedDecl *D, bool OnlyTemplate);
+
+static LinkageInfo getLVForDecl(const NamedDecl *D, bool OnlyTemplate) {
+  if (!OnlyTemplate)
+    return D->getLinkageAndVisibility();
+  return computeLVForDecl(D, OnlyTemplate);
+}
 
 /// \brief Get the most restrictive linkage for the types and
 /// declarations in the given template argument list.
@@ -569,18 +575,18 @@ static void clearLinkageForClass(const CXXRecordDecl *record) {
          i = record->decls_begin(), e = record->decls_end(); i != e; ++i) {
     Decl *child = *i;
     if (isa<NamedDecl>(child))
-      cast<NamedDecl>(child)->ClearLinkageCache();
+      cast<NamedDecl>(child)->ClearLVCache();
   }
 }
 
 void NamedDecl::anchor() { }
 
-void NamedDecl::ClearLinkageCache() {
+void NamedDecl::ClearLVCache() {
   // Note that we can't skip clearing the linkage of children just
   // because the parent doesn't have cached linkage:  we don't cache
   // when computing linkage for parent contexts.
 
-  HasCachedLinkage = 0;
+  CacheValidAndVisibility = 0;
 
   // If we're changing the linkage of a class, we need to reset the
   // linkage of child declarations, too.
@@ -591,44 +597,44 @@ void NamedDecl::ClearLinkageCache() {
         dyn_cast<ClassTemplateDecl>(const_cast<NamedDecl*>(this))) {
     // Clear linkage for the template pattern.
     CXXRecordDecl *record = temp->getTemplatedDecl();
-    record->HasCachedLinkage = 0;
+    record->CacheValidAndVisibility = 0;
     clearLinkageForClass(record);
 
     // We need to clear linkage for specializations, too.
     for (ClassTemplateDecl::spec_iterator
            i = temp->spec_begin(), e = temp->spec_end(); i != e; ++i)
-      i->ClearLinkageCache();
+      i->ClearLVCache();
   }
 
   // Clear cached linkage for function template decls, too.
   if (FunctionTemplateDecl *temp =
         dyn_cast<FunctionTemplateDecl>(const_cast<NamedDecl*>(this))) {
-    temp->getTemplatedDecl()->ClearLinkageCache();
+    temp->getTemplatedDecl()->ClearLVCache();
     for (FunctionTemplateDecl::spec_iterator
            i = temp->spec_begin(), e = temp->spec_end(); i != e; ++i)
-      i->ClearLinkageCache();
+      i->ClearLVCache();
   }
     
 }
 
 Linkage NamedDecl::getLinkage() const {
-  if (HasCachedLinkage) {
-    assert(Linkage(CachedLinkage) ==
-             getLVForDecl(this, true).linkage());
-    return Linkage(CachedLinkage);
-  }
-
-  CachedLinkage = getLVForDecl(this, true).linkage();
-  HasCachedLinkage = 1;
-  return Linkage(CachedLinkage);
+  return getLinkageAndVisibility().linkage();
 }
 
 LinkageInfo NamedDecl::getLinkageAndVisibility() const {
-  LinkageInfo LI = getLVForDecl(this, false);
-  assert(!HasCachedLinkage || Linkage(CachedLinkage) == LI.linkage());
-  HasCachedLinkage = 1;
-  CachedLinkage = LI.linkage();
-  return LI;
+  if (CacheValidAndVisibility) {
+    Linkage L = static_cast<Linkage>(CachedLinkage);
+    Visibility V = static_cast<Visibility>(CacheValidAndVisibility - 1);
+    bool Explicit = CachedVisibilityExplicit;
+    LinkageInfo LV(L, V, Explicit);
+    assert(LV == computeLVForDecl(this, false));
+    return LV;
+  }
+  LinkageInfo LV = computeLVForDecl(this, false);
+  CachedLinkage = LV.linkage();
+  CacheValidAndVisibility = LV.visibility() + 1;
+  CachedVisibilityExplicit = LV.visibilityExplicit();
+  return LV;
 }
 
 llvm::Optional<Visibility> NamedDecl::getExplicitVisibility() const {
@@ -692,7 +698,7 @@ llvm::Optional<Visibility> NamedDecl::getExplicitVisibility() const {
   return llvm::Optional<Visibility>();
 }
 
-static LinkageInfo getLVForDecl(const NamedDecl *D, bool OnlyTemplate) {
+static LinkageInfo computeLVForDecl(const NamedDecl *D, bool OnlyTemplate) {
   // Objective-C: treat all Objective-C declarations as having external
   // linkage.
   switch (D->getKind()) {
@@ -1157,7 +1163,7 @@ VarDecl *VarDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
 void VarDecl::setStorageClass(StorageClass SC) {
   assert(isLegalForVariable(SC));
   if (getStorageClass() != SC)
-    ClearLinkageCache();
+    ClearLVCache();
   
   VarDeclBits.SClass = SC;
 }
@@ -1653,6 +1659,7 @@ void FunctionDecl::setBody(Stmt *B) {
   Body = B;
   if (B)
     EndRangeLoc = B->getLocEnd();
+  ClearLVCache();
 }
 
 void FunctionDecl::setPure(bool P) {
@@ -1757,7 +1764,7 @@ FunctionDecl *FunctionDecl::getCanonicalDecl() {
 void FunctionDecl::setStorageClass(StorageClass SC) {
   assert(isLegalForFunction(SC));
   if (getStorageClass() != SC)
-    ClearLinkageCache();
+    ClearLVCache();
   
   SClass = SC;
 }
@@ -2527,8 +2534,8 @@ TagDecl* TagDecl::getCanonicalDecl() {
 void TagDecl::setTypedefNameForAnonDecl(TypedefNameDecl *TDD) { 
   TypedefNameDeclOrQualifier = TDD; 
   if (TypeForDecl)
-    const_cast<Type*>(TypeForDecl)->ClearLinkageCache();
-  ClearLinkageCache();
+    const_cast<Type*>(TypeForDecl)->ClearLVCache();
+  ClearLVCache();
 }
 
 void TagDecl::startDefinition() {
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 26eee2d74a..673528ada0 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -2186,7 +2186,7 @@ std::pair<Linkage,Visibility> Type::getLinkageAndVisibility() const {
   return std::make_pair(TypeBits.getLinkage(), TypeBits.getVisibility());
 }
 
-void Type::ClearLinkageCache() {
+void Type::ClearLVCache() {
   TypeBits.CacheValidAndVisibility = 0;
   if (QualType(this, 0) != CanonicalType)
     CanonicalType->TypeBits.CacheValidAndVisibility = 0;
diff --git a/lib/Sema/SemaAttr.cpp b/lib/Sema/SemaAttr.cpp
index 4406f2d956..3bfb8f22b4 100644
--- a/lib/Sema/SemaAttr.cpp
+++ b/lib/Sema/SemaAttr.cpp
@@ -309,7 +309,8 @@ void Sema::AddPushedVisibilityAttribute(Decl *D) {
   if (!VisContext)
     return;
 
-  if (isa<NamedDecl>(D) && cast<NamedDecl>(D)->getExplicitVisibility())
+  NamedDecl *ND = dyn_cast<NamedDecl>(D);
+  if (ND && ND->getExplicitVisibility())
     return;
 
   VisStack *Stack = static_cast<VisStack*>(VisContext);
@@ -320,6 +321,7 @@ void Sema::AddPushedVisibilityAttribute(Decl *D) {
     = (VisibilityAttr::VisibilityType) rawType;
   SourceLocation loc = Stack->back().second;
 
+  ND->ClearLVCache();
   D->addAttr(::new (Context) VisibilityAttr(loc, Context, type));
 }
 
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 105ef49bd8..e1d772b084 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1775,9 +1775,13 @@ bool Sema::mergeDeclAttribute(Decl *D, InheritableAttr *Attr) {
                                     AA->getIntroduced(), AA->getDeprecated(),
                                     AA->getObsoleted(), AA->getUnavailable(),
                                     AA->getMessage());
-  else if (VisibilityAttr *VA = dyn_cast<VisibilityAttr>(Attr))
+  else if (VisibilityAttr *VA = dyn_cast<VisibilityAttr>(Attr)) {
     NewAttr = mergeVisibilityAttr(D, VA->getRange(), VA->getVisibility());
-  else if (DLLImportAttr *ImportA = dyn_cast<DLLImportAttr>(Attr))
+    if (NewAttr) {
+      NamedDecl *ND = cast<NamedDecl>(D);
+      ND->ClearLVCache();
+    }
+  } else if (DLLImportAttr *ImportA = dyn_cast<DLLImportAttr>(Attr))
     NewAttr = mergeDLLImportAttr(D, ImportA->getRange());
   else if (DLLExportAttr *ExportA = dyn_cast<DLLExportAttr>(Attr))
     NewAttr = mergeDLLExportAttr(D, ExportA->getRange());
@@ -6611,7 +6615,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
     }
     VDecl->setTypeSourceInfo(DeducedType);
     VDecl->setType(DeducedType->getType());
-    VDecl->ClearLinkageCache();
+    VDecl->ClearLVCache();
     
     // In ARC, infer lifetime.
     if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 22aad165e9..437e2a826b 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -2147,8 +2147,11 @@ static void handleAvailabilityAttr(Sema &S, Decl *D,
                                                       Deprecated.Version,
                                                       Obsoleted.Version,
                                                       IsUnavailable, Str);
-  if (NewAttr)
+  if (NewAttr) {
     D->addAttr(NewAttr);
+    NamedDecl *ND = cast<NamedDecl>(D);
+    ND->ClearLVCache();
+  }
 }
 
 VisibilityAttr *Sema::mergeVisibilityAttr(Decl *D, SourceRange Range,
@@ -2165,6 +2168,8 @@ VisibilityAttr *Sema::mergeVisibilityAttr(Decl *D, SourceRange Range,
     Diag(ExistingAttr->getLocation(), diag::err_mismatched_visibility);
     Diag(Range.getBegin(), diag::note_previous_attribute);
     D->dropAttr<VisibilityAttr>();
+    NamedDecl *ND = cast<NamedDecl>(D);
+    ND->ClearLVCache();
   }
   return ::new (Context) VisibilityAttr(Range, Context, Vis);
 }
@@ -2208,8 +2213,11 @@ static void handleVisibilityAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   }
 
   VisibilityAttr *NewAttr = S.mergeVisibilityAttr(D, Attr.getRange(), type);
-  if (NewAttr)
+  if (NewAttr) {
     D->addAttr(NewAttr);
+    NamedDecl *ND = cast<NamedDecl>(D);
+    ND->ClearLVCache();
+  }
 }
 
 static void handleObjCMethodFamilyAttr(Sema &S, Decl *decl,