[Runtime] Fix swift_retainCount for deiniting objects and BridgeObject tagged values. Make swift_bridgeObjectRetain/Release bail out early for tagged values.

The Allocations Instrument overrides swift_retain with a function that records the retain count by calling swift_retainCount. Its assert for bits.getIsDeiniting() is incorrect in that case, so remove it.

The recent change to ObjC tagged pointer bits on x86-64 also caused the various bridgeObjectRetain/Release functions to call through to swift_retain for BridgeObject tagged values on Mac. swift_retain ignored those values so there was no functional change, except when Instruments overrode it and passed them to swift_retainCount, which tried to dereference them and crashed. Modify bridgeObjectRetain/Release to bail out early again. Also modify swift_retainCount to ignore those values in case anything else expects retainCount to work on any pointer swift_retain accepts.

rdar://problem/45102538

Author: mikeash

stdlib/public/SwiftShims/RefCount.h

@@ -788,7 +788,6 @@ class RefCounts {
     if (bits.hasSideTable())
       return bits.getSideTable()->getCount();
 
-    assert(!bits.getIsDeiniting());  // FIXME: can we assert this?
     return bits.getStrongExtraRefCount() + 1;
   }
 

stdlib/public/runtime/HeapObject.cpp

@@ -365,7 +365,9 @@ void swift::swift_nonatomic_release_n(HeapObject *object, uint32_t n) {
 }
 
 size_t swift::swift_retainCount(HeapObject *object) {
-  return object->refCounts.getCount();
+  if (isValidPointerForNativeRetain(object))
+    return object->refCounts.getCount();
+  return 0;
 }
 
 size_t swift::swift_unownedRetainCount(HeapObject *object) {

stdlib/public/runtime/SwiftObject.mm

@@ -580,10 +580,16 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
   static_assert((heap_object_abi::SwiftSpareBitsMask & objectPointerIsObjCBit) ==
                 objectPointerIsObjCBit,
                 "isObjC bit not within spare bits");
-  return (uintptr_t(object) & objectPointerIsObjCBit) != 0 && (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) == 0;
+  return (uintptr_t(object) & objectPointerIsObjCBit) != 0
+      && (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) == 0;
 }
 #endif
 
+/// Return true iff the given BridgeObject is a tagged value.
+static bool isBridgeObjectTaggedPointer(void *object) {
+	return (uintptr_t(object) & heap_object_abi::BridgeObjectTagBitsMask) != 0;
+}
+
 // Mask out the spare bits in a bridgeObject, returning the object it
 // encodes.
 ///
@@ -594,7 +600,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void *swift::swift_bridgeObjectRetain(void *object) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return object;
 #endif
 
@@ -616,7 +622,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 SWIFT_RUNTIME_EXPORT
 void *swift::swift_nonatomic_bridgeObjectRetain(void *object) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return object;
 #endif
 
@@ -638,7 +644,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 SWIFT_RUNTIME_EXPORT
 void swift::swift_bridgeObjectRelease(void *object) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return;
 #endif
 
@@ -655,7 +661,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void swift::swift_nonatomic_bridgeObjectRelease(void *object) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return;
 #endif
 
@@ -672,7 +678,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void *swift::swift_bridgeObjectRetain_n(void *object, int n) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return object;
 #endif
 
@@ -695,7 +701,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void swift::swift_bridgeObjectRelease_n(void *object, int n) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return;
 #endif
 
@@ -713,7 +719,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void *swift::swift_nonatomic_bridgeObjectRetain_n(void *object, int n) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return object;
 #endif
 
@@ -736,7 +742,7 @@ static bool isNonNative_unTagged_bridgeObject(void *object) {
 
 void swift::swift_nonatomic_bridgeObjectRelease_n(void *object, int n) {
 #if SWIFT_OBJC_INTEROP
-  if (isObjCTaggedPointer(object))
+  if (isObjCTaggedPointer(object) || isBridgeObjectTaggedPointer(object))
     return;
 #endif