[Runtime] Add ObjC support to isKnownUniquelyReferenced.

Add code to support detecting uniquely referenced Objective-C and Core
Foundation objects.

rdar://47902425
rdar://66805490

include/swift/AST/ASTContext.h

@@ -748,6 +748,10 @@ public:
   /// tag single payloads.
   AvailabilityContext getMultiPayloadEnumTagSinglePayload();
 
+  /// Get the runtime availability of the Objective-C enabled
+  /// swift_isUniquelyReferenced functions.
+  AvailabilityContext getObjCIsUniquelyReferencedAvailability();
+
   /// Get the runtime availability of features introduced in the Swift 5.2
   /// compiler for the target platform.
   AvailabilityContext getSwift52Availability();

include/swift/Runtime/HeapObject.h

@@ -211,6 +211,18 @@ size_t swift_unownedRetainCount(HeapObject *object);
 SWIFT_RUNTIME_EXPORT
 size_t swift_weakRetainCount(HeapObject *object);
 
+/// Is this pointer a non-null unique reference to an object?
+SWIFT_RUNTIME_EXPORT
+bool swift_isUniquelyReferenced(const void *);
+
+/// Is this non-null pointer a unique reference to an object?
+SWIFT_RUNTIME_EXPORT
+bool swift_isUniquelyReferenced_nonNull(const void *);
+
+/// Is this non-null BridgeObject a unique reference to an object?
+SWIFT_RUNTIME_EXPORT
+bool swift_isUniquelyReferenced_nonNull_bridgeObject(uintptr_t bits);
+
 /// Is this pointer a non-null unique reference to an object
 /// that uses Swift reference counting?
 SWIFT_RUNTIME_EXPORT

include/swift/Runtime/RuntimeFunctions.def

@@ -473,6 +473,30 @@ FUNCTION(IsUniquelyReferencedNonObjC_nonNull_bridgeObject,
          ARGS(BridgeObjectPtrTy),
          ATTRS(NoUnwind, ZExt))
 
+// bool swift_isUniquelyReferenced(const void *);
+FUNCTION(IsUniquelyReferenced, swift_isUniquelyReferenced,
+         C_CC, ObjCIsUniquelyReferencedAvailability,
+         RETURNS(Int1Ty),
+         ARGS(UnknownRefCountedPtrTy),
+         ATTRS(NoUnwind, ZExt))
+
+// bool swift_isUniquelyReferenced_nonNull(const void *);
+FUNCTION(IsUniquelyReferenced_nonNull,
+         swift_isUniquelyReferenced_nonNull,
+         C_CC, ObjCIsUniquelyReferencedAvailability,
+         RETURNS(Int1Ty),
+         ARGS(UnknownRefCountedPtrTy),
+         ATTRS(NoUnwind, ZExt))
+
+// bool swift_isUniquelyReferenced_nonNull_bridgeObject(
+//   uintptr_t bits);
+FUNCTION(IsUniquelyReferenced_nonNull_bridgeObject,
+         swift_isUniquelyReferenced_nonNull_bridgeObject,
+         C_CC, ObjCIsUniquelyReferencedAvailability,
+         RETURNS(Int1Ty),
+         ARGS(BridgeObjectPtrTy),
+         ATTRS(NoUnwind, ZExt))
+
 // bool swift_isUniquelyReferenced_native(const struct HeapObject *);
 FUNCTION(IsUniquelyReferenced_native, swift_isUniquelyReferenced_native,
          C_CC, AlwaysAvailable,

lib/AST/Availability.cpp

@@ -338,6 +338,10 @@ AvailabilityContext ASTContext::getMultiPayloadEnumTagSinglePayload() {
   return getSwift56Availability();
 }
 
+AvailabilityContext ASTContext::getObjCIsUniquelyReferencedAvailability() {
+  return getSwift56Availability();
+}
+
 AvailabilityContext ASTContext::getSwift52Availability() {
   auto target = LangOpts.Target;
 

lib/IRGen/GenHeap.cpp

@@ -1343,21 +1343,34 @@ llvm::Value *IRGenFunction::emitLoadRefcountedPtr(Address addr,
 llvm::Value *IRGenFunction::
 emitIsUniqueCall(llvm::Value *value, SourceLoc loc, bool isNonNull) {
   llvm::Constant *fn;
+  bool nonObjC = !IGM.getAvailabilityContext().isContainedIn(
+      IGM.Context.getObjCIsUniquelyReferencedAvailability());
+
   if (value->getType() == IGM.RefCountedPtrTy) {
     if (isNonNull)
       fn = IGM.getIsUniquelyReferenced_nonNull_nativeFn();
     else
       fn = IGM.getIsUniquelyReferenced_nativeFn();
   } else if (value->getType() == IGM.UnknownRefCountedPtrTy) {
-    if (isNonNull)
-      fn = IGM.getIsUniquelyReferencedNonObjC_nonNullFn();
-    else
-      fn = IGM.getIsUniquelyReferencedNonObjCFn();
+    if (nonObjC) {
+      if (isNonNull)
+        fn = IGM.getIsUniquelyReferencedNonObjC_nonNullFn();
+      else
+        fn = IGM.getIsUniquelyReferencedNonObjCFn();
+    } else {
+      if (isNonNull)
+        fn = IGM.getIsUniquelyReferenced_nonNullFn();
+      else
+        fn = IGM.getIsUniquelyReferencedFn();
+    }
   } else if (value->getType() == IGM.BridgeObjectPtrTy) {
     if (!isNonNull)
       unimplemented(loc, "optional bridge ref");
 
-    fn = IGM.getIsUniquelyReferencedNonObjC_nonNull_bridgeObjectFn();
+    if (nonObjC)
+      fn = IGM.getIsUniquelyReferencedNonObjC_nonNull_bridgeObjectFn();
+    else
+      fn = IGM.getIsUniquelyReferenced_nonNull_bridgeObjectFn();
   } else {
     llvm_unreachable("Unexpected LLVM type for a refcounted pointer.");
   }

lib/IRGen/IRGenModule.cpp

@@ -802,6 +802,17 @@ namespace RuntimeConstants {
     }
     return RuntimeAvailability::AlwaysAvailable;
   }
+
+  RuntimeAvailability
+  ObjCIsUniquelyReferencedAvailability(ASTContext &context) {
+    auto featureAvailability =
+        context.getObjCIsUniquelyReferencedAvailability();
+    if (!isDeploymentAvailabilityContainedIn(context, featureAvailability)) {
+      return RuntimeAvailability::ConditionallyAvailable;
+    }
+    return RuntimeAvailability::AlwaysAvailable;
+  }
+
 } // namespace RuntimeConstants
 
 // We don't use enough attributes to justify generalizing the

stdlib/public/core/ArrayBuffer.swift

@@ -108,7 +108,7 @@ extension _ArrayBuffer {
     if !_isClassOrObjCExistential(Element.self) {
       return _storage.isUniquelyReferencedUnflaggedNative()
     }
-    return _storage.isUniquelyReferencedNative() && _isNative
+    return _storage.isUniquelyReferencedNative()
    }
   
   /// Returns `true` and puts the buffer in a mutable state iff the buffer's

stdlib/public/core/BridgeStorage.swift

@@ -72,7 +72,7 @@ internal struct _BridgeStorage<NativeClass: AnyObject> {
   @inlinable
   @inline(__always)
   internal mutating func isUniquelyReferencedNative() -> Bool {
-    return _isUnique(&rawValue)
+    return isNative && _isUnique(&rawValue)
   }
 
   @_alwaysEmitIntoClient

stdlib/public/runtime/SwiftObject.mm

@@ -76,7 +76,6 @@ const ClassMetadata *swift::_swift_getClass(const void *object) {
 }
 
 #if SWIFT_OBJC_INTEROP
-
 /// Replacement for ObjC object_isClass(), which is unavailable on
 /// deployment targets macOS 10.9 and iOS 7.
 static bool objcObjectIsClass(id object) {
@@ -1352,6 +1351,36 @@ bool swift::swift_isUniquelyReferencedNonObjC_nonNull(const void* object) {
     swift_isUniquelyReferenced_nonNull_native((const HeapObject*)object);
 }
 
+#if SWIFT_OBJC_INTEROP
+// It would be nice to weak link instead of doing this, but we can't do that
+// until the new API is in the versions of libobjc that we're linking against.
+static bool isUniquelyReferenced(id object) {
+#if OBJC_ISUNIQUELYREFERENCED_DEFINED
+  return objc_isUniquelyReferenced(object);
+#else
+  auto objcIsUniquelyRefd = SWIFT_LAZY_CONSTANT(reinterpret_cast<bool (*)(id)>(
+      dlsym(RTLD_NEXT, "objc_isUniquelyReferenced")));
+
+  return objcIsUniquelyRefd && objcIsUniquelyRefd(object);
+#endif /* OBJC_ISUNIQUELYREFERENCED_DEFINED */
+}
+#endif
+
+bool swift::swift_isUniquelyReferenced_nonNull(const void *object) {
+  assert(object != nullptr);
+
+#if SWIFT_OBJC_INTEROP
+  if (isObjCTaggedPointer(object))
+    return false;
+
+  if (!usesNativeSwiftReferenceCounting_nonNull(object)) {
+    return isUniquelyReferenced(id_const_cast(object));
+  }
+#endif
+  return swift_isUniquelyReferenced_nonNull_native(
+      static_cast<const HeapObject *>(object));
+}
+
 // Given an object reference, return true iff it is non-nil and refers
 // to a native swift object with strong reference count of 1.
 bool swift::swift_isUniquelyReferencedNonObjC(
@@ -1361,6 +1390,12 @@ bool swift::swift_isUniquelyReferencedNonObjC(
     && swift_isUniquelyReferencedNonObjC_nonNull(object);
 }
 
+// Given an object reference, return true if it is non-nil and refers
+// to an ObjC or native swift object with a strong reference count of 1.
+bool swift::swift_isUniquelyReferenced(const void *object) {
+  return object != nullptr && swift_isUniquelyReferenced_nonNull(object);
+}
+
 /// Return true if the given bits of a Builtin.BridgeObject refer to a
 /// native swift object whose strong reference count is 1.
 bool swift::swift_isUniquelyReferencedNonObjC_nonNull_bridgeObject(
@@ -1386,6 +1421,26 @@ bool swift::swift_isUniquelyReferencedNonObjC_nonNull_bridgeObject(
 #endif
 }
 
+/// Return true if the given bits of a Builtin.BridgeObject refer to
+/// an object whose strong reference count is 1.
+bool swift::swift_isUniquelyReferenced_nonNull_bridgeObject(uintptr_t bits) {
+  auto bridgeObject = reinterpret_cast<void *>(bits);
+
+  if (isObjCTaggedPointer(bridgeObject))
+    return false;
+
+  const auto object = toPlainObject_unTagged_bridgeObject(bridgeObject);
+
+#if SWIFT_OBJC_INTEROP
+  return !isNonNative_unTagged_bridgeObject(bridgeObject)
+             ? swift_isUniquelyReferenced_nonNull_native(
+                   (const HeapObject *)object)
+             : swift_isUniquelyReferenced_nonNull(object);
+#else
+  return swift_isUniquelyReferenced_nonNull_native((const HeapObject *)object);
+#endif
+}
+
 // Given a non-@objc object reference, return true iff the
 // object is non-nil and has a strong reference count greather than 1
 bool swift::swift_isEscapingClosureAtFileLocation(const HeapObject *object,

test/IRGen/builtins.swift

@@ -662,7 +662,7 @@ func acceptsAnyObject(_ ref: inout Builtin.AnyObject?) {}
 // CHECK-NEXT: [[ADDR:%.+]] = getelementptr inbounds [[OPTIONAL_ANYOBJECT_TY]], [[OPTIONAL_ANYOBJECT_TY]]* %0, i32 0, i32 0
 // CHECK-NEXT: [[CASTED:%.+]] = bitcast {{.+}}* [[ADDR]] to [[UNKNOWN_OBJECT:%objc_object|%swift\.refcounted]]**
 // CHECK-NEXT: [[REF:%.+]] = load [[UNKNOWN_OBJECT]]*, [[UNKNOWN_OBJECT]]** [[CASTED]]
-// CHECK-objc-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferencedNonObjC([[UNKNOWN_OBJECT]]* [[REF]])
+// CHECK-objc-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferenced{{(NonObjC)?}}([[UNKNOWN_OBJECT]]* [[REF]])
 // CHECK-native-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferenced_native([[UNKNOWN_OBJECT]]* [[REF]])
 // CHECK-NEXT: ret i1 [[RESULT]]
 func isUnique(_ ref: inout Builtin.AnyObject?) -> Bool {
@@ -675,7 +675,7 @@ func isUnique(_ ref: inout Builtin.AnyObject?) -> Bool {
 // CHECK-NEXT: entry:
 // CHECK-NEXT: [[ADDR:%.+]] = getelementptr inbounds %AnyObject, %AnyObject* %0, i32 0, i32 0
 // CHECK-NEXT: [[REF:%.+]] = load [[UNKNOWN_OBJECT]]*, [[UNKNOWN_OBJECT]]** [[ADDR]]
-// CHECK-objc-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferencedNonObjC_nonNull([[UNKNOWN_OBJECT]]* [[REF]])
+// CHECK-objc-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferenced{{(NonObjC)?}}_nonNull([[UNKNOWN_OBJECT]]* [[REF]])
 // CHECK-native-NEXT: [[RESULT:%.+]] = call i1 @swift_isUniquelyReferenced_nonNull_native([[UNKNOWN_OBJECT]]* [[REF]])
 // CHECK-NEXT: ret i1 [[RESULT]]
 func isUnique(_ ref: inout Builtin.AnyObject) -> Bool {
@@ -686,7 +686,7 @@ func isUnique(_ ref: inout Builtin.AnyObject) -> Bool {
 // CHECK-LABEL: define hidden {{.*}}i1 @"$s8builtins8isUniqueyBi1_BbzF"(%swift.bridge** nocapture dereferenceable({{.*}}) %0) {{.*}} {
 // CHECK-NEXT: entry:
 // CHECK-NEXT: load %swift.bridge*, %swift.bridge** %0
-// CHECK-NEXT: call i1 @swift_isUniquelyReferencedNonObjC_nonNull_bridgeObject(%swift.bridge* %1)
+// CHECK-NEXT: call i1 @swift_isUniquelyReferenced{{(NonObjC)?}}_nonNull_bridgeObject(%swift.bridge* %1)
 // CHECK-NEXT: ret i1 %2
 func isUnique(_ ref: inout Builtin.BridgeObject) -> Bool {
   return Builtin.isUnique(&ref)