Small RemoteAST fixes

include/swift/Remote/MetadataReader.h

@@ -202,6 +202,7 @@ class MetadataReader {
   StoredPointer TaggedPointerExtendedSlotShift;
   StoredPointer TaggedPointerExtendedSlotMask;
   StoredPointer TaggedPointerExtendedClasses;
+  StoredPointer TaggedPointerObfuscator;
 
   Demangle::NodeFactory Factory;
 
@@ -502,14 +503,14 @@ class MetadataReader {
         if (!readObjCClassName(MetadataAddress, className))
           return BuiltType();
 
-        auto BuiltObjCClass = Builder.createObjCClassType(std::move(className));
+        BuiltType BuiltObjCClass = Builder.createObjCClassType(std::move(className));
         if (!BuiltObjCClass) {
           // Try the superclass.
           if (!classMeta->Superclass)
             return BuiltType();
 
-          return readTypeFromMetadata(classMeta->Superclass,
-                                      skipArtificialSubclasses);
+          BuiltObjCClass = readTypeFromMetadata(classMeta->Superclass,
+                                                skipArtificialSubclasses);
         }
 
         TypeCache[MetadataAddress] = BuiltObjCClass;
@@ -711,7 +712,7 @@ class MetadataReader {
     if (getTaggedPointerEncoding() != TaggedPointerEncodingKind::Extended)
       return false;
 
-    return objectAddress & TaggedPointerMask;
+    return (objectAddress ^ TaggedPointerObfuscator) & TaggedPointerMask;
   }
 
   /// Read the isa pointer of an Object-C tagged pointer value.
@@ -728,8 +729,8 @@ class MetadataReader {
 
     // Extended pointers have a tag of 0b111, using 8 additional bits
     // to specify the class.
-    if (TaggedPointerExtendedMask != 0  &&
-        ((objectAddress & TaggedPointerExtendedMask)
+    if (TaggedPointerExtendedMask != 0 &&
+        (((objectAddress ^ TaggedPointerObfuscator) & TaggedPointerExtendedMask)
            == TaggedPointerExtendedMask)) {
       auto tag = ((objectAddress >> TaggedPointerExtendedSlotShift) &
                   TaggedPointerExtendedSlotMask);
@@ -2436,6 +2437,9 @@ class MetadataReader {
     TaggedPointerExtendedClasses =
         TaggedPointerExtendedClassesAddr.getAddressData();
 
+    tryFindAndReadSymbol(TaggedPointerObfuscator,
+                         "objc_debug_taggedpointer_obfuscator");
+
 #   undef tryFindSymbol
 #   undef tryReadSymbol
 #   undef tryFindAndReadSymbol

test/RemoteAST/existentials_objc.swift

@@ -12,5 +12,22 @@ func printDynamicTypeAndAddressForExistential<T>(_: T)
 // CHECK: NSObject
 printDynamicTypeAndAddressForExistential(NSObject() as AnyObject)
 
+// Print tagged pointer types three times to ensure the caching works.
+
+// CHECK: NSNumber
+printDynamicTypeAndAddressForExistential(NSNumber(123) as AnyObject)
+
+// CHECK: NSNumber
+printDynamicTypeAndAddressForExistential(NSNumber(123) as AnyObject)
+
 // CHECK: NSNumber
 printDynamicTypeAndAddressForExistential(NSNumber(123) as AnyObject)
+
+// CHECK: NSString
+printDynamicTypeAndAddressForExistential(NSString("hello") as AnyObject)
+
+// CHECK: NSString
+printDynamicTypeAndAddressForExistential(NSString("hello") as AnyObject)
+
+// CHECK: NSString
+printDynamicTypeAndAddressForExistential(NSString("hello") as AnyObject)

tools/swift-remoteast-test/swift-remoteast-test.cpp

@@ -40,15 +40,24 @@ using namespace swift::remoteAST;
 /// The context for the code we're running.  Set by the observer.
 static ASTContext *Context = nullptr;
 
+/// The RemoteAST for the code we're running.
+std::shared_ptr<MemoryReader> reader;
+std::unique_ptr<RemoteASTContext> remoteContext;
+
+static RemoteASTContext &getRemoteASTContext() {
+  if (remoteContext)
+    return *remoteContext;
+
+  std::shared_ptr<MemoryReader> reader(new InProcessMemoryReader());
+  remoteContext.reset(new RemoteASTContext(*Context, std::move(reader)));
+  return *remoteContext;
+}
+
 // FIXME: swiftcall
 /// func printType(forMetadata: Any.Type)
 LLVM_ATTRIBUTE_USED extern "C" void SWIFT_REMOTEAST_TEST_ABI
 printMetadataType(const Metadata *typeMetadata) {
-  assert(Context && "context was not set");
-
-  std::shared_ptr<MemoryReader> reader(new InProcessMemoryReader());
-  RemoteASTContext remoteAST(*Context, std::move(reader));
-
+  auto &remoteAST = getRemoteASTContext();
   auto &out = llvm::outs();
 
   auto result =
@@ -66,11 +75,7 @@ printMetadataType(const Metadata *typeMetadata) {
 /// func printDynamicType(_: AnyObject)
 LLVM_ATTRIBUTE_USED extern "C" void SWIFT_REMOTEAST_TEST_ABI
 printHeapMetadataType(void *object) {
-  assert(Context && "context was not set");
-
-  std::shared_ptr<MemoryReader> reader(new InProcessMemoryReader());
-  RemoteASTContext remoteAST(*Context, std::move(reader));
-
+  auto &remoteAST = getRemoteASTContext();
   auto &out = llvm::outs();
 
   auto metadataResult =
@@ -94,11 +99,7 @@ printHeapMetadataType(void *object) {
 
 static void printMemberOffset(const Metadata *typeMetadata,
                               StringRef memberName, bool passMetadata) {
-  assert(Context && "context was not set");
-
-  std::shared_ptr<MemoryReader> reader(new InProcessMemoryReader());
-  RemoteASTContext remoteAST(*Context, std::move(reader));
-
+  auto &remoteAST = getRemoteASTContext();
   auto &out = llvm::outs();
 
   // The first thing we have to do is get the type.
@@ -147,10 +148,7 @@ printTypeMetadataMemberOffset(const Metadata *typeMetadata,
 LLVM_ATTRIBUTE_USED extern "C" void SWIFT_REMOTEAST_TEST_ABI
 printDynamicTypeAndAddressForExistential(void *object,
                                          const Metadata *typeMetadata) {
-  assert(Context && "context was not set");
-  std::shared_ptr<MemoryReader> reader(new InProcessMemoryReader());
-  RemoteASTContext remoteAST(*Context, std::move(reader));
-
+  auto &remoteAST = getRemoteASTContext();
   auto &out = llvm::outs();
 
   // First, retrieve the static type of the existential, so we can understand