Merge pull request #30433 from aschwaighofer/irgen_no_duplicate_objc_method_descriptor_entries

IRGen: Unique method descriptors in objc method lists

Author: aschwaighofer

lib/IRGen/GenClass.cpp

@@ -1521,27 +1521,33 @@ namespace {
     }
 
     void buildMethod(ConstantArrayBuilder &descriptors,
-                     MethodDescriptor descriptor) {
+                     MethodDescriptor descriptor,
+                     llvm::StringSet<> &uniqueSelectors) {
       switch (descriptor.getKind()) {
       case MethodDescriptor::Kind::Method:
-        return buildMethod(descriptors, descriptor.getMethod());
+        return buildMethod(descriptors, descriptor.getMethod(),
+                           uniqueSelectors);
       case MethodDescriptor::Kind::IVarInitializer:
         emitObjCIVarInitDestroyDescriptor(IGM, descriptors, getClass(),
-                                          descriptor.getImpl(), false);
+                                          descriptor.getImpl(), false,
+                                          uniqueSelectors);
         return;
       case MethodDescriptor::Kind::IVarDestroyer:
         emitObjCIVarInitDestroyDescriptor(IGM, descriptors, getClass(),
-                                          descriptor.getImpl(), true);
+                                          descriptor.getImpl(), true,
+                                          uniqueSelectors);
         return;
       }
       llvm_unreachable("bad method descriptor kind");
     }
 
     void buildMethod(ConstantArrayBuilder &descriptors,
-                     AbstractFunctionDecl *method) {
+                     AbstractFunctionDecl *method,
+                     llvm::StringSet<> &uniqueSelectors) {
       auto accessor = dyn_cast<AccessorDecl>(method);
       if (!accessor)
-        return emitObjCMethodDescriptor(IGM, descriptors, method);
+        return emitObjCMethodDescriptor(IGM, descriptors, method,
+                                        uniqueSelectors);
 
       switch (accessor->getAccessorKind()) {
       case AccessorKind::Get:
@@ -1610,7 +1616,9 @@ namespace {
         namePrefix = "_PROTOCOL_INSTANCE_METHODS_OPT_";
         break;
       }
-      llvm::Constant *methodListPtr = buildMethodList(methods, namePrefix);
+      llvm::StringSet<> uniqueSelectors;
+      llvm::Constant *methodListPtr =
+          buildMethodList(methods, namePrefix, uniqueSelectors);
       builder.add(methodListPtr);
     }
 
@@ -1653,11 +1661,12 @@ namespace {
     ///
     /// This method does not return a value of a predictable type.
     llvm::Constant *buildMethodList(ArrayRef<MethodDescriptor> methods,
-                                    StringRef name) {
+                                    StringRef name,
+                                    llvm::StringSet<> &uniqueSelectors) {
       return buildOptionalList(methods, 3 * IGM.getPointerSize(), name,
                                [&](ConstantArrayBuilder &descriptors,
                                    MethodDescriptor descriptor) {
-        buildMethod(descriptors, descriptor);
+        buildMethod(descriptors, descriptor, uniqueSelectors);
       });
     }
 

lib/IRGen/GenObjC.cpp

@@ -1323,24 +1323,34 @@ static void emitObjCDescriptor(IRGenModule &IGM,
 /// };
 void irgen::emitObjCMethodDescriptor(IRGenModule &IGM,
                                      ConstantArrayBuilder &descriptors,
-                                     AbstractFunctionDecl *method) {
+                                     AbstractFunctionDecl *method,
+                                     llvm::StringSet<> &uniqueSelectors) {
+  // Don't emit a selector twice.
+  Selector selector(method);
+  if (!uniqueSelectors.insert(selector.str()).second)
+    return;
+
   ObjCMethodDescriptor descriptor(
     emitObjCMethodDescriptorParts(IGM, method, /*concrete*/ true));
   emitObjCDescriptor(IGM, descriptors, descriptor);
 }
 
-void irgen::emitObjCIVarInitDestroyDescriptor(IRGenModule &IGM,
-                                              ConstantArrayBuilder &descriptors,
-                                              ClassDecl *cd,
-                                              llvm::Function *objcImpl,
-                                              bool isDestroyer) {
+void irgen::emitObjCIVarInitDestroyDescriptor(
+    IRGenModule &IGM, ConstantArrayBuilder &descriptors, ClassDecl *cd,
+    llvm::Function *objcImpl, bool isDestroyer,
+    llvm::StringSet<> &uniqueSelectors) {
   /// The first element is the selector.
   SILDeclRef declRef = SILDeclRef(cd, 
                                   isDestroyer? SILDeclRef::Kind::IVarDestroyer
                                              : SILDeclRef::Kind::IVarInitializer,
                                   1, 
                                   /*foreign*/ true);
   Selector selector(declRef);
+
+  // Don't emit a selector twice.
+  if (!uniqueSelectors.insert(selector.str()).second)
+    return;
+
   ObjCMethodDescriptor descriptor{};
   descriptor.selectorRef = IGM.getAddrOfObjCMethodName(selector.str());
 

lib/IRGen/GenObjC.h

@@ -155,15 +155,17 @@ namespace irgen {
   /// constructor, or destructor implementation.
   void emitObjCMethodDescriptor(IRGenModule &IGM,
                                 ConstantArrayBuilder &descriptors,
-                                AbstractFunctionDecl *method);
+                                AbstractFunctionDecl *method,
+                                llvm::StringSet<> &uniqueSelectors);
 
   /// Build an Objective-C method descriptor for the ivar initializer
   /// or destroyer of a class (-.cxx_construct or -.cxx_destruct).
   void emitObjCIVarInitDestroyDescriptor(IRGenModule &IGM,
                                          ConstantArrayBuilder &descriptors,
                                          ClassDecl *cd,
                                          llvm::Function *impl,
-                                         bool isDestroyer);
+                                         bool isDestroyer,
+                                         llvm::StringSet<> &uniqueSelectors);
 
   /// Get the type encoding for an ObjC property.
   void getObjCEncodingForPropertyType(IRGenModule &IGM, VarDecl *property,

test/IRGen/objc_protocol_instance_methods.swift

@@ -0,0 +1,13 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-ir %s | %FileCheck %s
+
+// REQUIRES: OS=macosx
+
+
+// Make sure we don't emit duplicate method descriptors
+
+// CHECK-NOT: _PROTOCOL_INSTANCE_METHODS_NSObject{{.*}}"\01L_selector_data(conformsToProtocol:)"{{.*}}"\01L_selector_data(conformsToProtocol:)"
+
+import Foundation
+
+@objc protocol P: NSObjectProtocol {}
+class C: NSObject, P {}