Method Pool in modules: we make sure that if a module contains an entry for

a selector, the entry should be complete, containing everything introduced by
that module and all modules it imports.

Before writing out the method pool of a module, we sync up the out of date
selectors by pulling in methods for the selectors, from all modules it imports.

In ReadMethodPool, after pulling in the method pool entry for module A, this
lets us skip the modules that module A imports.

rdar://problem/25900131

llvm-svn: 268091

clang/include/clang/Sema/ExternalSemaSource.h

@@ -70,6 +70,10 @@ public:
   /// selector.
   virtual void ReadMethodPool(Selector Sel);
 
+  /// Load the contents of the global method pool for a given
+  /// selector if necessary.
+  virtual void updateOutOfDateSelector(Selector Sel);
+
   /// \brief Load the set of namespaces that are known to the external source,
   /// which will be used during typo correction.
   virtual void ReadKnownNamespaces(

clang/include/clang/Sema/MultiplexExternalSemaSource.h

@@ -203,6 +203,10 @@ public:
   /// selector.
   void ReadMethodPool(Selector Sel) override;
 
+  /// Load the contents of the global method pool for a given
+  /// selector if necessary.
+  void updateOutOfDateSelector(Selector Sel) override;
+
   /// \brief Load the set of namespaces that are known to the external source,
   /// which will be used during typo correction.
   void

clang/include/clang/Sema/Sema.h

@@ -1017,6 +1017,7 @@ public:
   llvm::SmallSet<SpecialMemberDecl, 4> SpecialMembersBeingDeclared;
 
   void ReadMethodPool(Selector Sel);
+  void updateOutOfDateSelector(Selector Sel);
 
   /// Private Helper predicate to check for 'self'.
   bool isSelfExpr(Expr *RExpr);

clang/include/clang/Serialization/ASTReader.h

@@ -653,6 +653,10 @@ private:
   /// global method pool for this selector.
   llvm::DenseMap<Selector, unsigned> SelectorGeneration;
 
+  /// Whether a selector is out of date. We mark a selector as out of date
+  /// if we load another module after the method pool entry was pulled in.
+  llvm::DenseMap<Selector, bool> SelectorOutOfDate;
+
   struct PendingMacroInfo {
     ModuleFile *M;
     uint64_t MacroDirectivesOffset;
@@ -1781,6 +1785,10 @@ public:
   /// selector.
   void ReadMethodPool(Selector Sel) override;
 
+  /// Load the contents of the global method pool for a given
+  /// selector if necessary.
+  void updateOutOfDateSelector(Selector Sel) override;
+
   /// \brief Load the set of namespaces that are known to the external source,
   /// which will be used during typo correction.
   void ReadKnownNamespaces(

clang/lib/Sema/MultiplexExternalSemaSource.cpp

@@ -197,6 +197,11 @@ void MultiplexExternalSemaSource::ReadMethodPool(Selector Sel) {
     Sources[i]->ReadMethodPool(Sel);
 }
 
+void MultiplexExternalSemaSource::updateOutOfDateSelector(Selector Sel) {
+  for(size_t i = 0; i < Sources.size(); ++i)
+    Sources[i]->updateOutOfDateSelector(Sel);
+}
+
 void MultiplexExternalSemaSource::ReadKnownNamespaces(
                                    SmallVectorImpl<NamespaceDecl*> &Namespaces){
   for(size_t i = 0; i < Sources.size(); ++i)

clang/lib/Sema/Sema.cpp

@@ -1237,6 +1237,7 @@ void Sema::ActOnComment(SourceRange Comment) {
 ExternalSemaSource::~ExternalSemaSource() {}
 
 void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
+void ExternalSemaSource::updateOutOfDateSelector(Selector Sel) { }
 
 void ExternalSemaSource::ReadKnownNamespaces(
                            SmallVectorImpl<NamespaceDecl *> &Namespaces) {

clang/lib/Sema/SemaDeclObjC.cpp

@@ -3305,6 +3305,12 @@ void Sema::ReadMethodPool(Selector Sel) {
   ExternalSource->ReadMethodPool(Sel);
 }
 
+void Sema::updateOutOfDateSelector(Selector Sel) {
+  if (!ExternalSource)
+    return;
+  ExternalSource->updateOutOfDateSelector(Sel);
+}
+
 void Sema::AddMethodToGlobalPool(ObjCMethodDecl *Method, bool impl,
                                  bool instance) {
   // Ignore methods of invalid containers.

clang/lib/Serialization/ASTReader.cpp

@@ -3606,6 +3606,9 @@ ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName,
          Id != IdEnd; ++Id)
       Id->second->setOutOfDate(true);
   }
+  // Mark selectors as out of date.
+  for (auto Sel : SelectorGeneration)
+    SelectorOutOfDate[Sel.first] = true;
   
   // Resolve any unresolved module exports.
   for (unsigned I = 0, N = UnresolvedModuleRefs.size(); I != N; ++I) {
@@ -7139,6 +7142,7 @@ void ASTReader::ReadMethodPool(Selector Sel) {
   unsigned &Generation = SelectorGeneration[Sel];
   unsigned PriorGeneration = Generation;
   Generation = getGeneration();
+  SelectorOutOfDate[Sel] = false;
   
   // Search for methods defined with this selector.
   ++NumMethodPoolLookups;
@@ -7170,6 +7174,11 @@ void ASTReader::ReadMethodPool(Selector Sel) {
   addMethodsToPool(S, Visitor.getFactoryMethods(), Pos->second.second);
 }
 
+void ASTReader::updateOutOfDateSelector(Selector Sel) {
+  if (SelectorOutOfDate[Sel])
+    ReadMethodPool(Sel);
+}
+
 void ASTReader::ReadKnownNamespaces(
                           SmallVectorImpl<NamespaceDecl *> &Namespaces) {
   Namespaces.clear();

clang/lib/Serialization/ASTWriter.cpp

@@ -4387,6 +4387,19 @@ uint64_t ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
     }
   }
 
+  // For method pool in the module, if it contains an entry for a selector,
+  // the entry should be complete, containing everything introduced by that
+  // module and all modules it imports. It's possible that the entry is out of
+  // date, so we need to pull in the new content here.
+
+  // It's possible that updateOutOfDateSelector can update SelectorIDs. To be
+  // safe, we copy all selectors out.
+  llvm::SmallVector<Selector, 256> AllSelectors;
+  for (auto &SelectorAndID : SelectorIDs)
+    AllSelectors.push_back(SelectorAndID.first);
+  for (auto &Selector : AllSelectors)
+    SemaRef.updateOutOfDateSelector(Selector);
+
   // Form the record of special types.
   RecordData SpecialTypes;
   AddTypeRef(Context.getRawCFConstantStringType(), SpecialTypes);

clang/test/Modules/Inputs/MethodPoolCombined1.h

@@ -0,0 +1,6 @@
+
+@import MethodPoolString1;
+@interface A
+- (int)stringValue;
+@end
+

clang/test/Modules/Inputs/MethodPoolCombined2.h

@@ -0,0 +1 @@
+@import MethodPoolString2;

clang/test/Modules/Inputs/MethodPoolString1.h

@@ -0,0 +1,4 @@
+
+@interface S1
+- (int)stringValue;
+@end

clang/test/Modules/Inputs/MethodPoolString2.h

@@ -0,0 +1,4 @@
+
+@interface S2
+- (int)stringValue;
+@end

clang/test/Modules/Inputs/module.map

@@ -393,3 +393,20 @@ module ElaboratedTypeStructs {
     header "elaborated-type-structs.h"
   }
 }
+
+// We import a module, then declare a method with selector stringValue in
+// MethodPoolCombined1.h. In MethodPoolCombined2.h, we import another module
+// that also contains a method for selector stringValue. We make sure that
+// the method pool entry for stringValue in this module is complete.
+module MethodPoolCombined {
+  header "MethodPoolCombined1.h"
+  header "MethodPoolCombined2.h"
+}
+
+module MethodPoolString1 {
+  header "MethodPoolString1.h"
+}
+
+module MethodPoolString2 {
+  header "MethodPoolString2.h"
+}

clang/test/Modules/method_pool_write.m

@@ -0,0 +1,11 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -fsyntax-only -I %S/Inputs %s -verify
+// expected-no-diagnostics
+
+@import MethodPoolCombined;
+@import MethodPoolString2;
+
+void message_kindof_object(__kindof S2 *kindof_S2) {
+  [kindof_S2 stringValue];
+}
+