This document describes the ABI interface to the Swift runtime, which provides the following core functionality for Swift programs:
It is intended to describe only the runtime interface that compiler-generated code should conform to, not details of how things are implemented.
The final runtime interface is currently a work-in-progress; it is a goal of Swift 3 to stabilize it. This document attempts to describe both the current state of the runtime and the intended endpoint of the stable interface. Changes that are intended to be made before stabilization are marked with ABI TODO. Entry points that only exist on Darwin platforms with ObjC interop, and information that only pertains to ObjC interop, are marked ObjC-only.
Entry points in this section are intended to be removed or internalized before ABI stabilization.
ABI TODO: Any exported C++ symbols are implementation details that are not intended to be part of the stable runtime interface.
ABI TODO: These functions are implementation details of the standard library reflect interface. They will be superseded by a low-level runtime reflection API.
@convention(thin) (string: UnsafePointer<UInt8>,
length: UInt,
@out String) -> ()
Given a pointer to a Swift mangled symbol name as a byte string of length characters, returns the demangled name as a Swift.String.
ABI TODO: Decouple from the standard library Swift.String implementation. Rename with a non-stdlib naming scheme.
000000000001cb30 T _swift_allocBox 000000000001cb30 T _swift_allocEmptyBox 000000000001c990 T _swift_allocObject 000000000001ca60 T _swift_bufferAllocate 000000000001ca90 T _swift_bufferHeaderSize 000000000001cd30 T _swift_deallocBox 000000000001d490 T _swift_deallocClassInstance 000000000001cd60 T _swift_deallocObject 000000000001cd60 T _swift_deallocUninitializedObject 000000000001d4c0 T _swift_deallocPartialClassInstance 000000000001d400 T _swift_rootObjCDealloc 000000000001c960 T _swift_slowAlloc 000000000001c980 T _swift_slowDealloc 000000000001ce10 T _swift_projectBox 000000000001ca00 T _swift_initStackObject
@convention(c) (@unowned NativeObject) -> UInt
Returns a random number. Only used by allocation profiling tools.
0000000000027ba0 T _swift_bridgeObjectRelease 0000000000027c50 T _swift_bridgeObjectRelease_n 0000000000027b50 T _swift_bridgeObjectRetain 0000000000027be0 T _swift_bridgeObjectRetain_n 000000000001ce70 T _swift_release 000000000001cee0 T _swift_release_n 000000000001ce30 T _swift_retain 000000000001ce50 T _swift_retain_n 000000000001d240 T _swift_tryRetain 0000000000027b10 T _swift_unknownObjectRelease 0000000000027a70 T _swift_unknownObjectRelease_n 0000000000027ad0 T _swift_unknownObjectRetain 0000000000027a10 T _swift_unknownObjectRetain_n 0000000000027d50 T _swift_unknownObjectUnownedAssign 00000000000280a0 T _swift_unknownObjectUnownedCopyAssign 0000000000027fd0 T _swift_unknownObjectUnownedCopyInit 0000000000027ed0 T _swift_unknownObjectUnownedDestroy 0000000000027cb0 T _swift_unknownObjectUnownedInit 0000000000027f20 T _swift_unknownObjectUnownedLoadStrong 00000000000281f0 T _swift_unknownObjectUnownedTakeAssign 0000000000028070 T _swift_unknownObjectUnownedTakeInit 0000000000027f70 T _swift_unknownObjectUnownedTakeStrong 00000000000282b0 T _swift_unknownObjectWeakAssign 0000000000028560 T _swift_unknownObjectWeakCopyAssign 00000000000284e0 T _swift_unknownObjectWeakCopyInit 00000000000283e0 T _swift_unknownObjectWeakDestroy 0000000000028270 T _swift_unknownObjectWeakInit 0000000000028420 T _swift_unknownObjectWeakLoadStrong 0000000000028610 T _swift_unknownObjectWeakTakeAssign 0000000000028520 T _swift_unknownObjectWeakTakeInit 0000000000028470 T _swift_unknownObjectWeakTakeStrong 000000000001d3c0 T _swift_unownedCheck 000000000001cfb0 T _swift_unownedRelease 000000000001d0a0 T _swift_unownedRelease_n 000000000001cf70 T _swift_unownedRetain 000000000001cf60 T _swift_unownedRetainCount 000000000001d2b0 T _swift_unownedRetainStrong 000000000001d310 T _swift_unownedRetainStrongAndRelease 000000000001d060 T _swift_unownedRetain_n 000000000001ca20 T _swift_verifyEndOfLifetime 000000000001d680 T _swift_weakAssign 000000000001d830 T _swift_weakCopyAssign 000000000001d790 T _swift_weakCopyInit 000000000001d770 T _swift_weakDestroy 000000000001d640 T _swift_weakInit 000000000001d6d0 T _swift_weakLoadStrong 000000000001d8b0 T _swift_weakTakeAssign 000000000001d800 T _swift_weakTakeInit 000000000001d710 T _swift_weakTakeStrong 000000000002afe0 T _swift_isUniquelyReferencedNonObjC 000000000002af50 T _swift_isUniquelyReferencedNonObjC_nonNull 000000000002b060 T _swift_isUniquelyReferencedNonObjC_nonNull_bridgeObject 000000000002af00 T _swift_isUniquelyReferenced_native 000000000002aea0 T _swift_isUniquelyReferenced_nonNull_native 00000000000????? T _swift_setDeallocating 000000000001d280 T _swift_isDeallocating
ABI TODO: _unsynchronized r/r entry points
The ErrorType existential type uses a special single-word, reference- counted representation.
ObjC-only: The representation is internal to the runtime in order to provide efficient bridging with the platform NSError and CFError implementations. On non-ObjC platforms this bridging is unnecessary, and the error object interface could be made more fragile.
To preserve the encapsulation of the ErrorType representation, and allow for future representation optimizations, the runtime provides special entry points for allocating, projecting, and reference counting error values.
00000000000268e0 T _swift_allocError 0000000000026d50 T _swift_bridgeErrorTypeToNSError 0000000000026900 T _swift_deallocError 0000000000027120 T _swift_errorRelease 0000000000027100 T _swift_errorRetain 0000000000026b80 T _swift_getErrorValue
ABI TODO: _unsynchronized r/r entry points
ABI TODO: _n r/r entry points
@convention(thin) (Builtin.RawPointer, @convention(thin) () -> ()) -> ()
Used to lazily initialize global variables. The first parameter must point to a word-sized memory location that was initialized to zero at process start. It is undefined behavior to reference memory that has been initialized to something other than zero or written to by anything other than swift_once in the current process's lifetime. The function referenced by the second parameter will have been run exactly once in the time between process start and the function returns.
0000000000001470 T _swift_dynamicCast 0000000000000a60 T _swift_dynamicCastClass 0000000000000ae0 T _swift_dynamicCastClassUnconditional 0000000000028750 T _swift_dynamicCastForeignClass 000000000002ae20 T _swift_dynamicCastForeignClassMetatype 000000000002ae30 T _swift_dynamicCastForeignClassMetatypeUnconditional 0000000000028760 T _swift_dynamicCastForeignClassUnconditional 00000000000011c0 T _swift_dynamicCastMetatype 0000000000000cf0 T _swift_dynamicCastMetatypeToObjectConditional 0000000000000d20 T _swift_dynamicCastMetatypeToObjectUnconditional 00000000000012e0 T _swift_dynamicCastMetatypeUnconditional 00000000000286c0 T _swift_dynamicCastObjCClass 0000000000028bd0 T _swift_dynamicCastObjCClassMetatype 0000000000028c00 T _swift_dynamicCastObjCClassMetatypeUnconditional 0000000000028700 T _swift_dynamicCastObjCClassUnconditional 0000000000028af0 T _swift_dynamicCastObjCProtocolConditional 0000000000028a50 T _swift_dynamicCastObjCProtocolUnconditional 0000000000028960 T _swift_dynamicCastTypeToObjCProtocolConditional 00000000000287d0 T _swift_dynamicCastTypeToObjCProtocolUnconditional 0000000000000de0 T _swift_dynamicCastUnknownClass 0000000000000fd0 T _swift_dynamicCastUnknownClassUnconditional
0000000000027140 T _swift_willThrow
ObjC-only.
ABI TODO: Decouple from the runtime as much as possible. Much of this should be implementable in the standard library now.
0000000000003c80 T _swift_bridgeNonVerbatimFromObjectiveCConditional 00000000000037e0 T _swift_bridgeNonVerbatimToObjectiveC 00000000000039c0 T _swift_getBridgedNonVerbatimObjectiveCType 0000000000003d90 T _swift_isBridgedNonVerbatimToObjectiveC
Certain common code paths are implemented in the runtime as a code size optimization.
0000000000023a40 T _swift_assignExistentialWithCopy 000000000001dbf0 T _swift_copyPOD 000000000001c560 T _swift_getEnumCaseMultiPayload 000000000001be60 T _swift_getEnumCaseSinglePayload 000000000001c400 T _swift_storeEnumTagMultiPayload 000000000001bf90 T _swift_storeEnumTagSinglePayload
These functions look up metadata for types that potentially require runtime instantiation or initialization, including structural types, generics, classes, and metadata for imported C and Objective-C types.
ABI TODO: Instantiation APIs under flux as part of resilience work. For nominal types, getGenericMetadata is likely to become an implementation detail used to implement resilient per-type metadata accessor functions.
0000000000023230 T _swift_getExistentialMetatypeMetadata 0000000000023630 T _swift_getExistentialTypeMetadata 0000000000023b90 T _swift_getForeignTypeMetadata 000000000001ef30 T _swift_getFunctionTypeMetadata 000000000001eed0 T _swift_getFunctionTypeMetadata1 000000000001f1f0 T _swift_getFunctionTypeMetadata2 000000000001f250 T _swift_getFunctionTypeMetadata3 000000000001e940 T _swift_getGenericMetadata 0000000000022fd0 T _swift_getMetatypeMetadata 000000000001ec50 T _swift_getObjCClassMetadata 000000000001e6b0 T _swift_getResilientMetadata 0000000000022260 T _swift_getTupleTypeMetadata 00000000000225a0 T _swift_getTupleTypeMetadata2 00000000000225d0 T _swift_getTupleTypeMetadata3 0000000000028bc0 T _swift_getInitializedObjCClass
ABI TODO: Fast entry points for getExistential*TypeMetadata1-3. Static metadata for Any and AnyObject is probably worth considering too.
Calls to these entry points are emitted when instantiating type metadata at runtime.
ABI TODO: Initialization APIs under flux as part of resilience work.
000000000001e3e0 T _swift_allocateGenericClassMetadata 000000000001e620 T _swift_allocateGenericValueMetadata 0000000000022be0 T _swift_initClassMetadata_UniversalStrategy 000000000001c100 T _swift_initEnumMetadataMultiPayload 000000000001bd60 T _swift_initEnumMetadataSingleCase 000000000001bd60 T _swift_initEnumMetadataSinglePayload 0000000000022a20 T _swift_initStructMetadata 0000000000024230 T _swift_initializeSuperclass 0000000000028b60 T _swift_instantiateObjCClass
0000000000000b60 T _swift_getDynamicType 0000000000022fb0 T _swift_getObjectType 00000000000006f0 T _swift_getTypeName 00000000000040c0 T _swift_isClassType 0000000000003f50 T _swift_isClassOrObjCExistentialType 0000000000004130 T _swift_isOptionalType 00000000000279f0 T _swift_objc_class_usesNativeSwiftReferenceCounting 000000000002b340 T _swift_objc_class_unknownGetInstanceExtents 000000000002b350 T _swift_class_getInstanceExtents 0000000000004080 T _swift_class_getSuperclass
ABI TODO: getTypeByName entry point.
ABI TODO: Should have a getTypeKind entry point with well-defined enum constants to supersede swift_is*Type.
ABI TODO: Rename class metadata queries with a consistent naming scheme.
0000000000002ef0 T _swift_registerProtocolConformances 0000000000003060 T _swift_conformsToProtocol
000000000001c7d0 T _swift_reportError 000000000001c940 T _swift_deletedMethodError
The Swift runtime exports standard metadata objects for Builtin types as well as standard value witness tables that can be freely adopted by types with common layout attributes. Note that, unlike public-facing types, the runtime does not guarantee a 1:1 mapping of Builtin types to metadata objects, and will reuse metadata objects to represent builtins with the same layout characteristics.
000000000004faa8 S __TMBB 000000000004fab8 S __TMBO 000000000004f9f8 S __TMBb 000000000004f9c8 S __TMBi128_ 000000000004f998 S __TMBi16_ 000000000004f9d8 S __TMBi256_ 000000000004f9a8 S __TMBi32_ 000000000004f9b8 S __TMBi64_ 000000000004f988 S __TMBi8_ 000000000004f9e8 S __TMBo 000000000004fac8 S __TMT_ 000000000004f568 S __TWVBO 000000000004f4b0 S __TWVBb 000000000004f0a8 S __TWVBi128_ 000000000004eec8 S __TWVBi16_ 000000000004f148 S __TWVBi256_ 000000000004ef68 S __TWVBi32_ 000000000004f008 S __TWVBi64_ 000000000004ee28 S __TWVBi8_ 000000000004f1e8 S __TWVBo 000000000004f778 S __TWVFT_T_ 000000000004f3f8 S __TWVMBo 000000000004f8e8 S __TWVT_ 000000000004f830 S __TWVXfT_T_ 000000000004f620 S __TWVXoBO 000000000004f2a0 S __TWVXoBo 000000000004f6d8 S __TWVXwGSqBO_ 000000000004f358 S __TWVXwGSqBo_
Moving to per-type instantiation functions instead of using getGenericMetadata directly
swift_objc_ naming convention for ObjC
Alternative ABIs for retain/release
Unsynchronized retain/release
Nonnull retain/release
Decouple dynamic casting, bridging, and reflection from the standard library