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[Runtime] Fix copying in extended existential value witnesses. #85346

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Merged
merged 1 commit into from
Nov 10, 2025
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[Runtime] Fix copying in extended existential value witnesses. #85346

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99 changes: 45 additions & 54 deletions stdlib/public/runtime/ExistentialMetadataImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,20 @@ namespace swift {
namespace metadataimpl {

/// A common base class for opaque-existential and class-existential boxes.
template <typename Impl> struct SWIFT_LIBRARY_VISIBILITY ExistentialBoxBase {};
template <typename Impl>
struct SWIFT_LIBRARY_VISIBILITY ExistentialBoxBase {
template <class Container, class... A>
static void copyBytes(Container *dest, Container *src, A... args) {
memcpy(dest, src, src->getContainerStride(args...));
}

template <class Container, class... A>
static void copyTypeBytes(Container *dest, Container *src, A...args) {
auto valueBytes = src->getValueSize();
auto toCopy = src->getContainerStride(args...) - valueBytes;
memcpy((char *)dest + valueBytes, (char *)src + valueBytes, toCopy);
}
};

/// A common base class for fixed and non-fixed opaque-existential box
/// implementations.
Expand Down Expand Up @@ -83,7 +96,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
template <class Container, class... A>
static Container *initializeWithCopy(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
copyTypeBytes(dest, src, args...);
auto *type = src->getType();
auto *vwt = type->getValueWitnesses();

Expand All @@ -104,10 +117,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
template <class Container, class... A>
static Container *initializeWithTake(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
auto from = src->getBuffer(args...);
auto to = dest->getBuffer(args...);
memcpy(to, from, sizeof(ValueBuffer));
copyBytes(dest, src, args...);
return dest;
}

Expand Down Expand Up @@ -151,7 +161,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
// Move dest value aside so we can destroy it later.
destType->vw_initializeWithTake(opaqueTmpBuffer, destValue);

src->copyTypeInto(dest, args...);
copyTypeBytes(dest, src, args...);
if (srcVwt->isValueInline()) {
// Inline src value.

Expand All @@ -172,7 +182,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
auto *destRef =
*reinterpret_cast<HeapObject **>(dest->getBuffer(args...));

src->copyTypeInto(dest, args...);
copyTypeBytes(dest, src, args...);
if (srcVwt->isValueInline()) {

// initWithCopy.
Expand Down Expand Up @@ -239,7 +249,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
// Move dest value aside.
destType->vw_initializeWithTake(opaqueTmpBuffer, destValue);

src->copyTypeInto(dest, args...);
copyTypeBytes(dest, src, args...);
if (srcVwt->isValueInline()) {
// Inline src value.

Expand All @@ -260,7 +270,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBoxBase
auto *destRef =
*reinterpret_cast<HeapObject **>(dest->getBuffer(args...));

src->copyTypeInto(dest, args...);
copyTypeBytes(dest, src, args...);
if (srcVwt->isValueInline()) {
// initWithCopy.

Expand Down Expand Up @@ -291,12 +301,20 @@ template <unsigned NumWitnessTables>
struct SWIFT_LIBRARY_VISIBILITY FixedOpaqueExistentialContainer {
OpaqueExistentialContainer Header;
const void *WitnessTables[NumWitnessTables];

static size_t getValueSize() {
return sizeof(Header.Buffer);
}
};
// We need to be able to instantiate for NumWitnessTables==0, which
// requires an explicit specialization.
template <>
struct FixedOpaqueExistentialContainer<0> {
OpaqueExistentialContainer Header;

static size_t getValueSize() {
return sizeof(Header.Buffer);
}
};

/// A box implementation class for an opaque existential type with
Expand All @@ -311,10 +329,7 @@ struct SWIFT_LIBRARY_VISIBILITY OpaqueExistentialBox
ValueBuffer *getBuffer() {
return &this->Header.Buffer;
}
void copyTypeInto(Container *dest) const {
this->Header.copyTypeInto(&dest->Header, NumWitnessTables);
}


static size_t getContainerStride() {
return sizeof(Container);
}
Expand Down Expand Up @@ -355,9 +370,6 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedOpaqueExistentialBox
ValueBuffer *getBuffer(const Metadata *self) {
return &Header.Buffer;
}
void copyTypeInto(Container *dest, const Metadata *self) {
Header.copyTypeInto(&dest->Header, getNumWitnessTables(self));
}

static unsigned getNumWitnessTables(const Metadata *self) {
auto castSelf = static_cast<const ExistentialTypeMetadata*>(self);
Expand All @@ -377,7 +389,11 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedOpaqueExistentialBox
}

static size_t getContainerStride(const Metadata *self) {
return getStride(getNumWitnessTables(self));
return self->vw_stride();
}

static size_t getValueSize() {
return sizeof(Header.Buffer);
}
};

Expand Down Expand Up @@ -411,28 +427,25 @@ struct SWIFT_LIBRARY_VISIBILITY ClassExistentialBoxBase
template <class Container, class... A>
static Container *initializeWithCopy(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
auto newValue = *src->getValueSlot();
*dest->getValueSlot() = newValue;
copyBytes(dest, src, args...);
swift_unknownObjectRetain(newValue);
return dest;
}

template <class Container, class... A>
static Container *initializeWithTake(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
*dest->getValueSlot() = *src->getValueSlot();
copyBytes(dest, src, args...);
return dest;
}

template <class Container, class... A>
static Container *assignWithCopy(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
auto newValue = *src->getValueSlot();
auto oldValue = *dest->getValueSlot();
*dest->getValueSlot() = newValue;
copyBytes(dest, src, args...);
swift_unknownObjectRetain(newValue);
swift_unknownObjectRelease(oldValue);
return dest;
Expand All @@ -441,10 +454,8 @@ struct SWIFT_LIBRARY_VISIBILITY ClassExistentialBoxBase
template <class Container, class... A>
static Container *assignWithTake(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
auto newValue = *src->getValueSlot();
auto oldValue = *dest->getValueSlot();
*dest->getValueSlot() = newValue;
copyBytes(dest, src, args...);
swift_unknownObjectRelease(oldValue);
return dest;
}
Expand All @@ -470,10 +481,6 @@ struct SWIFT_LIBRARY_VISIBILITY ClassExistentialBox : ClassExistentialBoxBase {
ClassExistentialContainer Header;
const void *TypeInfo[NumWitnessTables];

void copyTypeInto(Container *dest) const {
for (unsigned i = 0; i != NumWitnessTables; ++i)
dest->TypeInfo[i] = TypeInfo[i];
}
void **getValueSlot() { return &Header.Value; }
void * const *getValueSlot() const { return &Header.Value; }

Expand Down Expand Up @@ -501,10 +508,6 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedClassExistentialBox
return castSelf->Flags.getNumWitnessTables();
}

void copyTypeInto(Container *dest, const Metadata *self) {
Header.copyTypeInto(&dest->Header, getNumWitnessTables(self));
}

void **getValueSlot() { return &Header.Value; }
void * const *getValueSlot() const { return &Header.Value; }

Expand All @@ -520,7 +523,7 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedClassExistentialBox
return getSize(numWitnessTables);
}
static size_t getContainerStride(const Metadata *self) {
return getStride(getNumWitnessTables(self));
return self->vw_stride();
}
};
using type = Container;
Expand All @@ -540,32 +543,28 @@ struct SWIFT_LIBRARY_VISIBILITY ExistentialMetatypeBoxBase
template <class Container, class... A>
static Container *initializeWithCopy(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
*dest->getValueSlot() = *src->getValueSlot();
return dest;
copyBytes(dest, src, args...);
return dest;
}

template <class Container, class... A>
static Container *initializeWithTake(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
*dest->getValueSlot() = *src->getValueSlot();
copyBytes(dest, src, args...);
return dest;
}

template <class Container, class... A>
static Container *assignWithCopy(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
*dest->getValueSlot() = *src->getValueSlot();
copyBytes(dest, src, args...);
return dest;
}

template <class Container, class... A>
static Container *assignWithTake(Container *dest, Container *src,
A... args) {
src->copyTypeInto(dest, args...);
*dest->getValueSlot() = *src->getValueSlot();
copyBytes(dest, src, args...);
return dest;
}

Expand Down Expand Up @@ -593,10 +592,6 @@ struct SWIFT_LIBRARY_VISIBILITY ExistentialMetatypeBox
ExistentialMetatypeContainer Header;
const void *TypeInfo[NumWitnessTables];

void copyTypeInto(Container *dest) const {
for (unsigned i = 0; i != NumWitnessTables; ++i)
dest->TypeInfo[i] = TypeInfo[i];
}
const Metadata **getValueSlot() { return &Header.Value; }
const Metadata * const *getValueSlot() const { return &Header.Value; }

Expand Down Expand Up @@ -624,10 +619,6 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedExistentialMetatypeBox
return castSelf->Flags.getNumWitnessTables();
}

void copyTypeInto(Container *dest, const Metadata *self) {
Header.copyTypeInto(&dest->Header, getNumWitnessTables(self));
}

const Metadata **getValueSlot() { return &Header.Value; }
const Metadata * const *getValueSlot() const { return &Header.Value; }

Expand All @@ -643,7 +634,7 @@ struct SWIFT_LIBRARY_VISIBILITY NonFixedExistentialMetatypeBox
return getSize(numWitnessTables);
}
static size_t getContainerStride(const Metadata *self) {
return getStride(getNumWitnessTables(self));
return self->vw_stride();
}
};
using type = Container;
Expand Down
88 changes: 88 additions & 0 deletions test/Interpreter/extended_existential_copying.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,88 @@
// RUN: %target-run-simple-swift | %FileCheck %s

// UNSUPPORTED: use_os_stdlib
// UNSUPPORTED: back_deployment_runtime
// REQUIRES: OS=macosx
// REQUIRES: executable_test

protocol P1<P1T> {
associatedtype P1T

func printValue()
}

protocol P2<P2T> {
associatedtype P2T
}

protocol P3<P3T> {
associatedtype P3T
}

struct Small: P1, P2, P3 {
typealias P1T = Int
typealias P2T = Int
typealias P3T = Int

var str = "I am Small"

func printValue() { print(str) }
}

struct Big: P1, P2, P3 {
typealias P1T = Int
typealias P2T = Int
typealias P3T = Int

var str = "I am Big"
var str2 = ""
var str3 = ""

func printValue() { print(str) }
}

class Class: P1, P2, P3 {
typealias P1T = Int
typealias P2T = Int
typealias P3T = Int

var str = "I am Class"

func printValue() { print(str) }
}

func test<T>(_ value: T) {
var array: [T] = []
array.append(value)
for v in array {
(v as? P1)?.printValue()
}
}

// CHECK: I am Small
test(Small() as any P1<Int>)
// CHECK: I am Small
test(Small() as any P1<Int> & P2<Int>)
// CHECK: I am Small
test(Small() as any P1<Int> & P2<Int> & P3<Int>)

// CHECK: I am Big
test(Big() as any P1<Int>)
// CHECK: I am Big
test(Big() as any P1<Int> & P2<Int>)
// CHECK: I am Big
test(Big() as any P1<Int> & P2<Int> & P3<Int>)

// CHECK: I am Class
test(Class() as any P1<Int>)
// CHECK: I am Class
test(Class() as any P1<Int> & P2<Int>)
// CHECK: I am Class
test(Class() as any P1<Int> & P2<Int> & P3<Int>)

// CHECK: I am Class
test(Class() as any AnyObject & P1<Int>)
// CHECK: I am Class
test(Class() as any AnyObject & P1<Int> & P2<Int>)
// CHECK: I am Class
test(Class() as any AnyObject & P1<Int> & P2<Int> & P3<Int>)