AST: Cache SuperclassDeclRequest

This fixes a significant build time regression since 4.2.

Fixes <rdar://problem/47305605>.

Author: slavapestov

include/swift/AST/Decl.h

@@ -3562,11 +3562,16 @@ class ClassDecl final : public NominalTypeDecl {
   void createObjCMethodLookup();
 
   struct {
+    /// The superclass decl and a bit to indicate whether the
+    /// superclass was computed yet or not.
+    llvm::PointerIntPair<ClassDecl *, 1, bool> SuperclassDecl;
+
     /// The superclass type and a bit to indicate whether the
     /// superclass was computed yet or not.
-    llvm::PointerIntPair<Type, 1, bool> Superclass;
+    llvm::PointerIntPair<Type, 1, bool> SuperclassType;
   } LazySemanticInfo;
 
+  friend class SuperclassDeclRequest;
   friend class SuperclassTypeRequest;
   friend class TypeChecker;
 
@@ -3899,11 +3904,16 @@ class ProtocolDecl final : public NominalTypeDecl {
   bool existentialTypeSupportedSlow(LazyResolver *resolver);
 
   struct {
+    /// The superclass decl and a bit to indicate whether the
+    /// superclass was computed yet or not.
+    llvm::PointerIntPair<ClassDecl *, 1, bool> SuperclassDecl;
+
     /// The superclass type and a bit to indicate whether the
     /// superclass was computed yet or not.
-    llvm::PointerIntPair<Type, 1, bool> Superclass;
+    llvm::PointerIntPair<Type, 1, bool> SuperclassType;
   } LazySemanticInfo;
 
+  friend class SuperclassDeclRequest;
   friend class SuperclassTypeRequest;
   friend class TypeChecker;
 

include/swift/AST/NameLookupRequests.h

@@ -133,7 +133,7 @@ class UnderlyingTypeDeclsReferencedRequest :
 /// Request the superclass declaration for the given class.
 class SuperclassDeclRequest :
     public SimpleRequest<SuperclassDeclRequest,
-                         CacheKind::Uncached, // FIXME: Cache these
+                         CacheKind::SeparatelyCached,
                          ClassDecl *,
                          NominalTypeDecl *> {
 public:
@@ -149,6 +149,8 @@ class SuperclassDeclRequest :
 public:
   // Caching
   bool isCached() const { return true; }
+  Optional<ClassDecl *> getCachedResult() const;
+  void cacheResult(ClassDecl *value) const;
 
   // Cycle handling
   void diagnoseCycle(DiagnosticEngine &diags) const;

lib/AST/Decl.cpp

@@ -3973,7 +3973,10 @@ ClassDecl *ProtocolDecl::getSuperclassDecl() const {
 void ProtocolDecl::setSuperclass(Type superclass) {
   assert((!superclass || !superclass->hasArchetype())
          && "superclass must be interface type");
-  LazySemanticInfo.Superclass.setPointerAndInt(superclass, true);
+  LazySemanticInfo.SuperclassType.setPointerAndInt(superclass, true);
+  LazySemanticInfo.SuperclassDecl.setPointerAndInt(
+    superclass ? superclass->getClassOrBoundGenericClass() : nullptr,
+    true);
 }
 
 bool ProtocolDecl::walkInheritedProtocols(
@@ -6478,7 +6481,10 @@ ClassDecl *ClassDecl::getSuperclassDecl() const {
 void ClassDecl::setSuperclass(Type superclass) {
   assert((!superclass || !superclass->hasArchetype())
          && "superclass must be interface type");
-  LazySemanticInfo.Superclass.setPointerAndInt(superclass, true);
+  LazySemanticInfo.SuperclassType.setPointerAndInt(superclass, true);
+  LazySemanticInfo.SuperclassDecl.setPointerAndInt(
+    superclass ? superclass->getClassOrBoundGenericClass() : nullptr,
+    true);
 }
 
 ClangNode Decl::getClangNodeImpl() const {

lib/AST/NameLookupRequests.cpp

@@ -74,6 +74,30 @@ void UnderlyingTypeDeclsReferencedRequest::noteCycleStep(
 //----------------------------------------------------------------------------//
 // Superclass declaration computation.
 //----------------------------------------------------------------------------//
+Optional<ClassDecl *> SuperclassDeclRequest::getCachedResult() const {
+  auto nominalDecl = std::get<0>(getStorage());
+
+  if (auto *classDecl = dyn_cast<ClassDecl>(nominalDecl))
+    if (classDecl->LazySemanticInfo.SuperclassDecl.getInt())
+      return classDecl->LazySemanticInfo.SuperclassDecl.getPointer();
+
+  if (auto *protocolDecl = dyn_cast<ProtocolDecl>(nominalDecl))
+    if (protocolDecl->LazySemanticInfo.SuperclassDecl.getInt())
+      return protocolDecl->LazySemanticInfo.SuperclassDecl.getPointer();
+
+  return None;
+}
+
+void SuperclassDeclRequest::cacheResult(ClassDecl *value) const {
+  auto nominalDecl = std::get<0>(getStorage());
+
+  if (auto *classDecl = dyn_cast<ClassDecl>(nominalDecl))
+    classDecl->LazySemanticInfo.SuperclassDecl.setPointerAndInt(value, true);
+
+  if (auto *protocolDecl = dyn_cast<ProtocolDecl>(nominalDecl))
+    protocolDecl->LazySemanticInfo.SuperclassDecl.setPointerAndInt(value, true);
+}
+
 void SuperclassDeclRequest::diagnoseCycle(DiagnosticEngine &diags) const {
   // FIXME: Improve this diagnostic.
   auto subjectDecl = std::get<0>(getStorage());
@@ -87,7 +111,7 @@ void SuperclassDeclRequest::noteCycleStep(DiagnosticEngine &diags) const {
 }
 
 //----------------------------------------------------------------------------//
-// Superclass declaration computation.
+// Extended nominal computation.
 //----------------------------------------------------------------------------//
 Optional<NominalTypeDecl *> ExtendedNominalRequest::getCachedResult() const {
   // Note: if we fail to compute any nominal declaration, it's considered

lib/AST/TypeCheckRequests.cpp

@@ -125,12 +125,12 @@ Optional<Type> SuperclassTypeRequest::getCachedResult() const {
   auto nominalDecl = std::get<0>(getStorage());
 
   if (auto *classDecl = dyn_cast<ClassDecl>(nominalDecl))
-    if (classDecl->LazySemanticInfo.Superclass.getInt())
-      return classDecl->LazySemanticInfo.Superclass.getPointer();
+    if (classDecl->LazySemanticInfo.SuperclassType.getInt())
+      return classDecl->LazySemanticInfo.SuperclassType.getPointer();
 
   if (auto *protocolDecl = dyn_cast<ProtocolDecl>(nominalDecl))
-    if (protocolDecl->LazySemanticInfo.Superclass.getInt())
-      return protocolDecl->LazySemanticInfo.Superclass.getPointer();
+    if (protocolDecl->LazySemanticInfo.SuperclassType.getInt())
+      return protocolDecl->LazySemanticInfo.SuperclassType.getPointer();
 
   return None;
 }
@@ -139,10 +139,10 @@ void SuperclassTypeRequest::cacheResult(Type value) const {
   auto nominalDecl = std::get<0>(getStorage());
 
   if (auto *classDecl = dyn_cast<ClassDecl>(nominalDecl))
-    classDecl->LazySemanticInfo.Superclass.setPointerAndInt(value, true);
+    classDecl->LazySemanticInfo.SuperclassType.setPointerAndInt(value, true);
 
   if (auto *protocolDecl = dyn_cast<ProtocolDecl>(nominalDecl))
-    protocolDecl->LazySemanticInfo.Superclass.setPointerAndInt(value, true);
+    protocolDecl->LazySemanticInfo.SuperclassType.setPointerAndInt(value, true);
 }
 
 //----------------------------------------------------------------------------//

test/Misc/stats_dir_tracer.swift

@@ -2,9 +2,9 @@
 // RUN: %target-swiftc_driver -o %t/main -module-name main -stats-output-dir %t %s -trace-stats-events
 // RUN: %FileCheck -input-file %t/*.csv %s
 
-// CHECK: {{[0-9]+,[0-9]+,"exit","typecheck-expr","Sema.NumTypesDeserialized",[0-9]+,[0-9]+,"Call","\[.*stats_dir_tracer.swift.*\]"}}
-// CHECK: {{[0-9]+,[0-9]+,"exit","typecheck-expr","Sema.NumConstraintScopes",[0-9]+,[0-9]+,"Sequence","\[.*stats_dir_tracer.swift.*\]"}}
-// CHECK: {{[0-9]+,[0-9]+,"exit","SuperclassDeclRequest","Sema.SuperclassDeclRequest",[0-9]+,[0-9]+,"Bar","\[.*stats_dir_tracer.swift.*\]"}}
+// CHECK-DAG: {{[0-9]+,[0-9]+,"exit","typecheck-expr","Sema.NumTypesDeserialized",[0-9]+,[0-9]+,"Call","\[.*stats_dir_tracer.swift.*\]"}}
+// CHECK-DAG: {{[0-9]+,[0-9]+,"exit","typecheck-expr","Sema.NumConstraintScopes",[0-9]+,[0-9]+,"Sequence","\[.*stats_dir_tracer.swift.*\]"}}
+// CHECK-DAG: {{[0-9]+,[0-9]+,"exit","SuperclassDeclRequest","Sema.SuperclassDeclRequest",[0-9]+,[0-9]+,"Bar","\[.*stats_dir_tracer.swift.*\]"}}
 
 public func foo() {
     print("hello")