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[IRGen+Runtime] Fix tag bit mask handling for objc, unknown objects a… #77431

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Merged
merged 1 commit into from
Nov 7, 2024
+169 −17
Merged

[IRGen+Runtime] Fix tag bit mask handling for objc, unknown objects a… #77431

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8 changes: 6 additions & 2 deletions lib/IRGen/TypeLayout.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
//
//===----------------------------------------------------------------------===//
#include "TypeLayout.h"
#include "ClassTypeInfo.h"
#include "ConstantBuilder.h"
#include "EnumPayload.h"
#include "FixedTypeInfo.h"
Expand Down Expand Up @@ -1293,14 +1294,17 @@ bool ScalarTypeLayoutEntry::refCountString(IRGenModule &IGM,
case ScalarKind::BlockReference:
B.addRefCount(LayoutStringBuilder::RefCountingKind::Block, size);
break;
case ScalarKind::ObjCReference:
if (typeInfo.hasFixedSpareBits()) {
case ScalarKind::ObjCReference: {
auto *classTI = dyn_cast<ClassTypeInfo>(&typeInfo);
assert(classTI);
if (!classTI->getClass()->hasClangNode()) {
B.addRefCount(LayoutStringBuilder::RefCountingKind::NativeSwiftObjC,
size);
} else {
B.addRefCount(LayoutStringBuilder::RefCountingKind::ObjC, size);
}
break;
}
case ScalarKind::ThickFunc:
B.addSkip(IGM.getPointerSize().getValue());
B.addRefCount(LayoutStringBuilder::RefCountingKind::NativeStrong,
Expand Down
72 changes: 57 additions & 15 deletions stdlib/public/runtime/BytecodeLayouts.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,16 @@ static uint64_t readTagBytes(const uint8_t *addr, uint8_t byteCount) {
}
}

// This check is used to determine whether or not ObjC references can
// be tagged pointers. If they can't, they have the same spare bits
// as swift references, and we have to mask them out before passing the
// reference to ref counting operations.
static constexpr bool platformSupportsTaggedPointers() {
// Platforms that don't reserve bits for ObjC, don't support tagged
// pointers.
return _swift_abi_ObjCReservedBitsMask != 0;
}

#if defined(__APPLE__) && defined(__arm64__)

#define CONTINUE_WITH_COPY(METADATA, READER, ADDR_OFFSET, DEST, SRC) \
Expand Down Expand Up @@ -281,9 +291,12 @@ static void weakDestroy(const Metadata *metadata, LayoutStringReader1 &reader,
static void unknownDestroy(const Metadata *metadata,
LayoutStringReader1 &reader, uintptr_t &addrOffset,
uint8_t *addr) {
void *object = *(void**)(addr + addrOffset);
uintptr_t object = *(uintptr_t *)(addr + addrOffset);
addrOffset += sizeof(void*);
swift_unknownObjectRelease(object);
if (!platformSupportsTaggedPointers()) {
object &= ~_swift_abi_SwiftSpareBitsMask;
}
swift_unknownObjectRelease((void *)object);
}

static void unknownUnownedDestroy(const Metadata *metadata,
Expand Down Expand Up @@ -769,9 +782,10 @@ multiPayloadEnumGeneric(const Metadata *metadata, LayoutStringReader1 &reader,
static void blockDestroy(const Metadata *metadata, LayoutStringReader1 &reader,
uintptr_t &addrOffset, uint8_t *addr) {
#if SWIFT_OBJC_INTEROP
void* object = (void *)(addr + addrOffset);
uintptr_t object = *(uintptr_t *)(addr + addrOffset);
object &= ~_swift_abi_SwiftSpareBitsMask;
addrOffset += sizeof(void*);
_Block_release(object);
_Block_release((void *)object);
#else
swift_unreachable("Blocks are not available on this platform");
#endif
Expand All @@ -783,6 +797,11 @@ static void objcStrongDestroy(const Metadata *metadata,
#if SWIFT_OBJC_INTEROP
uintptr_t object = *(uintptr_t *)(addr + addrOffset);
addrOffset += sizeof(objc_object*);

if (!platformSupportsTaggedPointers()) {
object &= ~_swift_abi_SwiftSpareBitsMask;
}

objc_release((objc_object *)object);
#else
swift_unreachable("ObjC interop is not available on this platform");
Expand Down Expand Up @@ -959,10 +978,13 @@ static void weakCopyInit(const Metadata *metadata, LayoutStringReader1 &reader,
static void unknownRetain(const Metadata *metadata, LayoutStringReader1 &reader,
uintptr_t &addrOffset, uint8_t *dest, uint8_t *src) {
uintptr_t _addrOffset = addrOffset;
void *object = *(void **)(src + _addrOffset);
uintptr_t object = *(uintptr_t *)(src + _addrOffset);
memcpy(dest + _addrOffset, &object, sizeof(void*));
addrOffset = _addrOffset + sizeof(void *);
swift_unknownObjectRetain(object);
if (!platformSupportsTaggedPointers()) {
object &= ~_swift_abi_SwiftSpareBitsMask;
}
swift_unknownObjectRetain((void *)object);
}

static void unknownUnownedCopyInit(const Metadata *metadata,
Expand Down Expand Up @@ -1000,9 +1022,11 @@ static void blockCopy(const Metadata *metadata, LayoutStringReader1 &reader,
uintptr_t &addrOffset, uint8_t *dest, uint8_t *src) {
#if SWIFT_OBJC_INTEROP
uintptr_t _addrOffset = addrOffset;
auto *copy = _Block_copy(*(void**)(src + _addrOffset));
memcpy(dest + _addrOffset, &copy, sizeof(void*));
uintptr_t object = *(uintptr_t *)(src + _addrOffset);
memcpy(dest + _addrOffset, &object, sizeof(void *));
addrOffset = _addrOffset + sizeof(void*);
object &= ~_swift_abi_SwiftSpareBitsMask;
_Block_copy((void *)object);
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Do we know for sure that the block has been copied to the heap already? _Block_copy returns its parameter iff the block isn't still on the stack. I recall that the Swift compiler doesn't try too hard to avoid copying blocks so we may never see a stack block here, but this worries me a bit, especially if the compiler got smarter about not copying nonescaping blocks at some point.

#else
swift_unreachable("Blocks are not available on this platform");
#endif
Expand All @@ -1016,6 +1040,11 @@ static void objcStrongRetain(const Metadata *metadata,
uintptr_t object = *(uintptr_t *)(src + _addrOffset);
memcpy(dest + _addrOffset, &object, sizeof(objc_object *));
addrOffset = _addrOffset + sizeof(objc_object *);

if (!platformSupportsTaggedPointers()) {
object &= ~_swift_abi_SwiftSpareBitsMask;
}

objc_retain((objc_object *)object);
#else
swift_unreachable("ObjC interop is not available on this platform");
Expand Down Expand Up @@ -1368,12 +1397,16 @@ static void unknownAssignWithCopy(const Metadata *metadata,
uintptr_t &addrOffset, uint8_t *dest,
uint8_t *src) {
uintptr_t _addrOffset = addrOffset;
void *destObject = *(void **)(dest + _addrOffset);
void *srcObject = *(void **)(src + _addrOffset);
uintptr_t destObject = *(uintptr_t *)(dest + _addrOffset);
uintptr_t srcObject = *(uintptr_t *)(src + _addrOffset);
memcpy(dest + _addrOffset, &srcObject, sizeof(void *));
addrOffset = _addrOffset + sizeof(void *);
swift_unknownObjectRelease(destObject);
swift_unknownObjectRetain(srcObject);
if (!platformSupportsTaggedPointers()) {
destObject &= ~_swift_abi_SwiftSpareBitsMask;
srcObject &= ~_swift_abi_SwiftSpareBitsMask;
}
swift_unknownObjectRelease((void *)destObject);
swift_unknownObjectRetain((void *)srcObject);
}

static void bridgeAssignWithCopy(const Metadata *metadata,
Expand Down Expand Up @@ -1431,10 +1464,14 @@ static void blockAssignWithCopy(const Metadata *metadata,
uint8_t *src) {
#if SWIFT_OBJC_INTEROP
uintptr_t _addrOffset = addrOffset;
_Block_release(*(void **)(dest + _addrOffset));
auto *copy = _Block_copy(*(void **)(src + _addrOffset));
memcpy(dest + _addrOffset, &copy, sizeof(void*));
uintptr_t destObject = *(uintptr_t *)(dest + _addrOffset);
uintptr_t srcObject = *(uintptr_t *)(src + _addrOffset);
memcpy(dest + _addrOffset, &srcObject, sizeof(void *));
addrOffset = _addrOffset + sizeof(void*);
destObject &= ~_swift_abi_SwiftSpareBitsMask;
srcObject &= ~_swift_abi_SwiftSpareBitsMask;
_Block_release((void *)destObject);
_Block_copy((void *)srcObject);
#else
swift_unreachable("Blocks are not available on this platform");
#endif
Expand All @@ -1452,6 +1489,11 @@ static void objcStrongAssignWithCopy(const Metadata *metadata,
memcpy(dest + _addrOffset, &srcObject, sizeof(objc_object*));
addrOffset = _addrOffset + sizeof(objc_object*);

if (!platformSupportsTaggedPointers()) {
destObject &= ~_swift_abi_SwiftSpareBitsMask;
srcObject &= ~_swift_abi_SwiftSpareBitsMask;
}

objc_release((objc_object *)destObject);
objc_retain((objc_object *)srcObject);
#else
Expand Down
6 changes: 6 additions & 0 deletions test/Interpreter/Inputs/layout_string_witnesses_types.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -667,6 +667,12 @@ public enum ErrorWrapper {
case y(Error)
}

public enum MultiPayloadAnyObject {
case x(AnyObject)
case y(AnyObject)
case z(AnyObject)
}

@inline(never)
public func consume<T>(_ x: T.Type) {
withExtendedLifetime(x) {}
Expand Down
57 changes: 57 additions & 0 deletions test/Interpreter/layout_string_witnesses_objc.swift
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Expand Up @@ -133,3 +133,60 @@ func testMultiPayloadNativeSwiftObjC() {
}

testMultiPayloadNativeSwiftObjC()

public enum MultiPayloadBlock {
#if _pointerBitWidth(_32)
public typealias PaddingPayload = (Int16, Int8, Bool)
#else
public typealias PaddingPayload = (Int32, Int16, Int8, Bool)
#endif

case x(PaddingPayload)
case y(@convention(block) () -> Void)
}

func testMultiPayloadBlock() {
let ptr = UnsafeMutablePointer<MultiPayloadBlock>.allocate(capacity: 1)

// initWithCopy
do {
let instance = SimpleClass(x: 0)
let x = MultiPayloadBlock.y({ print(instance) })
testInit(ptr, to: x)
}

// assignWithTake
do {
let instance = SimpleClass(x: 1)
let y = MultiPayloadBlock.y({ print(instance) })

// CHECK-NEXT: Before deinit
print("Before deinit")

// CHECK-NEXT: SimpleClass deinitialized!
testAssign(ptr, from: y)
}

// assignWithCopy
do {
let instance = SimpleClass(x: 2)
var z = MultiPayloadBlock.y({ print(instance) })

// CHECK-NEXT: Before deinit
print("Before deinit")

// CHECK-NEXT: SimpleClass deinitialized!
testAssignCopy(ptr, from: &z)
}

// CHECK-NEXT: Before deinit
print("Before deinit")

// destroy
// CHECK-NEXT: SimpleClass deinitialized!
testDestroy(ptr)

ptr.deallocate()
}

testMultiPayloadBlock()
43 changes: 43 additions & 0 deletions test/Interpreter/layout_string_witnesses_static.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1363,6 +1363,49 @@ func testMultiPayloadOneExtraTagValue() {

testMultiPayloadOneExtraTagValue()

func testMultiPayloadAnyObject() {
let ptr = UnsafeMutablePointer<MultiPayloadAnyObject>.allocate(capacity: 1)

// initWithCopy
do {
let x = MultiPayloadAnyObject.y(SimpleClass(x: 0))
testInit(ptr, to: x)
}

// assignWithTake
do {
let y = MultiPayloadAnyObject.z(SimpleClass(x: 1))

// CHECK-NEXT: Before deinit
print("Before deinit")

// CHECK-NEXT: SimpleClass deinitialized!
testAssign(ptr, from: y)
}

// assignWithCopy
do {
var z = MultiPayloadAnyObject.z(SimpleClass(x: 2))

// CHECK-NEXT: Before deinit
print("Before deinit")

// CHECK-NEXT: SimpleClass deinitialized!
testAssignCopy(ptr, from: &z)
}

// CHECK-NEXT: Before deinit
print("Before deinit")

// destroy
// CHECK-NEXT: SimpleClass deinitialized!
testDestroy(ptr)

ptr.deallocate()
}

testMultiPayloadAnyObject()

#if os(macOS)
func testObjc() {
let ptr = UnsafeMutablePointer<ObjcWrapper>.allocate(capacity: 1)
Expand Down