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swift-mirror/stdlib/public/runtime/Metadata.cpp
Joe Groff 4f65ef92c2 Runtime: Don't clobber the compiler-emitted layout of empty fields. 
Otherwise, we try to dirty constant memory for classes emitted as constant-layout by the compiler. Fixes rdar://problem/27951346.
2016-08-22 13:37:13 -07:00

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//===--- Metadata.cpp - Swift Language ABI Metadata Support ---------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Implementations of the metadata ABI functions.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/MathExtras.h"
#include "swift/Basic/Demangle.h"
#include "swift/Basic/LLVM.h"
#include "swift/Basic/Range.h"
#include "swift/Basic/Lazy.h"
#include "swift/Runtime/HeapObject.h"
#include "swift/Runtime/Metadata.h"
#include "swift/Runtime/Mutex.h"
#include "swift/Strings.h"
#include "MetadataCache.h"
#include <algorithm>
#include <condition_variable>
#include <new>
#include <cctype>
#if defined(_MSC_VER)
#define WIN32_LEAN_AND_MEAN
// Avoid defining macro max(), min() which conflict with std::max(), std::min()
#define NOMINMAX
#include <windows.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#endif
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Hashing.h"
#include "ErrorObject.h"
#include "ExistentialMetadataImpl.h"
#include "swift/Runtime/Debug.h"
#include "Private.h"
#if defined(__APPLE__)
#include <mach/vm_page_size.h>
#endif
#if SWIFT_OBJC_INTEROP
#include <objc/runtime.h>
#endif
#include <cstdio>
#if defined(__APPLE__) && defined(VM_MEMORY_SWIFT_METADATA)
#define VM_TAG_FOR_SWIFT_METADATA VM_MAKE_TAG(VM_MEMORY_SWIFT_METADATA)
#else
#define VM_TAG_FOR_SWIFT_METADATA (-1)
#endif
using namespace swift;
using namespace metadataimpl;
static uintptr_t swift_pageSize() {
#if defined(__APPLE__)
return vm_page_size;
#elif defined(_MSC_VER)
SYSTEM_INFO SystemInfo;
GetSystemInfo(&SystemInfo);
return SystemInfo.dwPageSize;
#else
return sysconf(_SC_PAGESIZE);
#endif
}
// allocate memory up to a nearby page boundary
static void *swift_allocateMetadataRoundingToPage(size_t size) {
const uintptr_t PageSizeMask = SWIFT_LAZY_CONSTANT(swift_pageSize()) - 1;
size = (size + PageSizeMask) & ~PageSizeMask;
#if defined(_MSC_VER)
auto mem = VirtualAlloc(
nullptr, size, MEM_TOP_DOWN | MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
#else
auto mem = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE,
VM_TAG_FOR_SWIFT_METADATA, 0);
if (mem == MAP_FAILED)
mem = nullptr;
#endif
return mem;
}
// free memory allocated by swift_allocateMetadataRoundingToPage()
static void swift_freeMetadata(void *addr, size_t size) {
#if defined(_MSC_VER)
// On success, VirtualFree() returns nonzero, on failure 0
int result = VirtualFree(addr, 0, MEM_RELEASE);
if (result == 0)
fatalError(/* flags = */ 0, "swift_freePage: VirtualFree() failed");
#else
// On success, munmap() returns 0, on failure -1
int result = munmap(addr, size);
if (result != 0)
fatalError(/* flags = */ 0, "swift_freePage: munmap() failed");
#endif
}
void *MetadataAllocator::alloc(size_t size) {
const uintptr_t PageSize = SWIFT_LAZY_CONSTANT(swift_pageSize());
// If the requested size is a page or larger, map page(s) for it
// specifically.
if (LLVM_UNLIKELY(size >= PageSize)) {
void *mem = swift_allocateMetadataRoundingToPage(size);
if (!mem)
crash("unable to allocate memory for metadata cache");
return mem;
}
uintptr_t curValue = NextValue.load(std::memory_order_relaxed);
while (true) {
char *next = reinterpret_cast<char*>(curValue);
char *end = next + size;
// If we wrap over the end of the page, allocate a new page.
void *allocation = nullptr;
const uintptr_t PageSizeMask = PageSize - 1;
if (LLVM_UNLIKELY(((uintptr_t)next & ~PageSizeMask)
!= (((uintptr_t)end & ~PageSizeMask)))) {
// Allocate a new page if we haven't already.
allocation = swift_allocateMetadataRoundingToPage(PageSize);
if (!allocation)
crash("unable to allocate memory for metadata cache");
next = (char*) allocation;
end = next + size;
}
// Swap it into place.
if (LLVM_LIKELY(std::atomic_compare_exchange_weak_explicit(
&NextValue, &curValue, reinterpret_cast<uintptr_t>(end),
std::memory_order_relaxed, std::memory_order_relaxed))) {
return next;
}
// If that didn't succeed, and we allocated, free the allocation.
// This potentially causes us to perform multiple mmaps under contention,
// but it keeps the fast path pristine.
if (allocation) {
swift_freeMetadata(allocation, PageSize);
}
}
}
namespace {
struct GenericCacheEntry;
// The cache entries in a generic cache are laid out like this:
struct GenericCacheEntryHeader : CacheEntry<GenericCacheEntry> {
const Metadata *Value;
size_t NumArguments;
};
struct GenericCacheEntry
: CacheEntry<GenericCacheEntry, GenericCacheEntryHeader> {
static const char *getName() { return "GenericCache"; }
GenericCacheEntry(unsigned numArguments) {
NumArguments = numArguments;
}
size_t getNumArguments() const { return NumArguments; }
static GenericCacheEntry *getFromMetadata(GenericMetadata *pattern,
Metadata *metadata) {
char *bytes = (char*) metadata;
if (auto classType = dyn_cast<ClassMetadata>(metadata)) {
assert(classType->isTypeMetadata());
bytes -= classType->getClassAddressPoint();
} else {
bytes -= pattern->AddressPoint;
}
bytes -= sizeof(GenericCacheEntry);
return reinterpret_cast<GenericCacheEntry*>(bytes);
}
};
}
using GenericMetadataCache = MetadataCache<GenericCacheEntry>;
using LazyGenericMetadataCache = Lazy<GenericMetadataCache>;
/// Fetch the metadata cache for a generic metadata structure.
static GenericMetadataCache &getCache(GenericMetadata *metadata) {
// Keep this assert even if you change the representation above.
static_assert(sizeof(LazyGenericMetadataCache) <=
sizeof(GenericMetadata::PrivateData),
"metadata cache is larger than the allowed space");
auto lazyCache =
reinterpret_cast<LazyGenericMetadataCache*>(metadata->PrivateData);
return lazyCache->get();
}
/// Fetch the metadata cache for a generic metadata structure,
/// in a context where it must have already been initialized.
static GenericMetadataCache &unsafeGetInitializedCache(GenericMetadata *metadata) {
// Keep this assert even if you change the representation above.
static_assert(sizeof(LazyGenericMetadataCache) <=
sizeof(GenericMetadata::PrivateData),
"metadata cache is larger than the allowed space");
auto lazyCache =
reinterpret_cast<LazyGenericMetadataCache*>(metadata->PrivateData);
return lazyCache->unsafeGetAlreadyInitialized();
}
ClassMetadata *
swift::swift_allocateGenericClassMetadata(GenericMetadata *pattern,
const void *arguments,
ClassMetadata *superclass) {
void * const *argumentsAsArray = reinterpret_cast<void * const *>(arguments);
size_t numGenericArguments = pattern->NumKeyArguments;
// Right now, we only worry about there being a difference in prefix matter.
size_t metadataSize = pattern->MetadataSize;
size_t prefixSize = pattern->AddressPoint;
size_t extraPrefixSize = 0;
if (superclass && superclass->isTypeMetadata()) {
if (superclass->getClassAddressPoint() > prefixSize) {
extraPrefixSize = (superclass->getClassAddressPoint() - prefixSize);
prefixSize += extraPrefixSize;
metadataSize += extraPrefixSize;
}
}
assert(metadataSize == pattern->MetadataSize + extraPrefixSize);
assert(prefixSize == pattern->AddressPoint + extraPrefixSize);
char *bytes = GenericCacheEntry::allocate(
unsafeGetInitializedCache(pattern).getAllocator(),
argumentsAsArray,
numGenericArguments,
metadataSize)->getData<char>();
// Copy any extra prefix bytes in from the superclass.
if (extraPrefixSize) {
memcpy(bytes, (const char*) superclass - prefixSize, extraPrefixSize);
bytes += extraPrefixSize;
}
// Copy in the metadata template.
memcpy(bytes, pattern->getMetadataTemplate(), pattern->MetadataSize);
// Okay, move to the address point.
bytes += pattern->AddressPoint;
ClassMetadata *metadata = reinterpret_cast<ClassMetadata*>(bytes);
assert(metadata->isTypeMetadata());
// Overwrite the superclass field.
metadata->SuperClass = superclass;
// Adjust the relative reference to the nominal type descriptor.
if (!metadata->isArtificialSubclass()) {
auto patternBytes =
reinterpret_cast<const char*>(pattern->getMetadataTemplate()) +
pattern->AddressPoint;
metadata->setDescription(
reinterpret_cast<const ClassMetadata*>(patternBytes)->getDescription());
}
// Adjust the class object extents.
if (extraPrefixSize) {
metadata->setClassSize(metadata->getClassSize() + extraPrefixSize);
metadata->setClassAddressPoint(prefixSize);
}
assert(metadata->getClassAddressPoint() == prefixSize);
return metadata;
}
ValueMetadata *
swift::swift_allocateGenericValueMetadata(GenericMetadata *pattern,
const void *arguments) {
void * const *argumentsAsArray = reinterpret_cast<void * const *>(arguments);
size_t numGenericArguments = pattern->NumKeyArguments;
char *bytes =
GenericCacheEntry::allocate(
unsafeGetInitializedCache(pattern).getAllocator(),
argumentsAsArray, numGenericArguments,
pattern->MetadataSize)->getData<char>();
// Copy in the metadata template.
memcpy(bytes, pattern->getMetadataTemplate(), pattern->MetadataSize);
// Okay, move to the address point.
bytes += pattern->AddressPoint;
auto *metadata = reinterpret_cast<ValueMetadata*>(bytes);
// Adjust the relative references to the nominal type descriptor and
// parent type.
auto patternBytes =
reinterpret_cast<const char*>(pattern->getMetadataTemplate()) +
pattern->AddressPoint;
auto patternMetadata = reinterpret_cast<const ValueMetadata*>(patternBytes);
metadata->Description = patternMetadata->Description.get();
metadata->Parent = patternMetadata->Parent;
return metadata;
}
/// The primary entrypoint.
SWIFT_RT_ENTRY_VISIBILITY
const Metadata *
swift::swift_getGenericMetadata(GenericMetadata *pattern,
const void *arguments)
SWIFT_CC(RegisterPreservingCC_IMPL) {
auto genericArgs = (const void * const *) arguments;
size_t numGenericArgs = pattern->NumKeyArguments;
auto entry = getCache(pattern).findOrAdd(genericArgs, numGenericArgs,
[&]() -> GenericCacheEntry* {
// Create new metadata to cache.
auto metadata = pattern->CreateFunction(pattern, arguments);
auto entry = GenericCacheEntry::getFromMetadata(pattern, metadata);
entry->Value = metadata;
return entry;
});
return entry->Value;
}
namespace {
class ObjCClassCacheEntry : public CacheEntry<ObjCClassCacheEntry> {
FullMetadata<ObjCClassWrapperMetadata> Metadata;
public:
static const char *getName() { return "ObjCClassCache"; }
ObjCClassCacheEntry(size_t numArguments) {}
static constexpr size_t getNumArguments() {
return 1;
}
FullMetadata<ObjCClassWrapperMetadata> *getData() {
return &Metadata;
}
const FullMetadata<ObjCClassWrapperMetadata> *getData() const {
return &Metadata;
}
};
}
/// The uniquing structure for ObjC class-wrapper metadata.
static Lazy<MetadataCache<ObjCClassCacheEntry>> ObjCClassWrappers;
const Metadata *
swift::swift_getObjCClassMetadata(const ClassMetadata *theClass) {
// If the class pointer is valid as metadata, no translation is required.
if (theClass->isTypeMetadata()) {
return theClass;
}
#if SWIFT_OBJC_INTEROP
// Search the cache.
const size_t numGenericArgs = 1;
const void *args[] = { theClass };
auto &Wrappers = ObjCClassWrappers.get();
auto entry = Wrappers.findOrAdd(args, numGenericArgs,
[&]() -> ObjCClassCacheEntry* {
// Create a new entry for the cache.
auto entry = ObjCClassCacheEntry::allocate(Wrappers.getAllocator(),
args, numGenericArgs, 0);
auto metadata = entry->getData();
metadata->setKind(MetadataKind::ObjCClassWrapper);
metadata->ValueWitnesses = &_TWVBO;
metadata->Class = theClass;
return entry;
});
return entry->getData();
#else
fatalError(/* flags = */ 0,
"swift_getObjCClassMetadata: no Objective-C interop");
#endif
}
namespace {
class FunctionCacheEntry;
struct FunctionCacheEntryHeader : CacheEntryHeader<FunctionCacheEntry> {
size_t NumArguments;
};
class FunctionCacheEntry
: public CacheEntry<FunctionCacheEntry, FunctionCacheEntryHeader> {
public:
FullMetadata<FunctionTypeMetadata> Metadata;
static const char *getName() { return "FunctionCache"; }
FunctionCacheEntry(size_t numArguments) {
NumArguments = numArguments;
}
size_t getNumArguments() const {
return NumArguments;
}
FullMetadata<FunctionTypeMetadata> *getData() {
return &Metadata;
}
const FullMetadata<FunctionTypeMetadata> *getData() const {
return &Metadata;
}
};
}
/// The uniquing structure for function type metadata.
static Lazy<MetadataCache<FunctionCacheEntry>> FunctionTypes;
const FunctionTypeMetadata *
swift::swift_getFunctionTypeMetadata1(FunctionTypeFlags flags,
const void *arg0,
const Metadata *result) {
assert(flags.getNumArguments() == 1
&& "wrong number of arguments in function metadata flags?!");
const void *flagsArgsAndResult[] = {
reinterpret_cast<const void*>(flags.getIntValue()),
arg0,
static_cast<const void *>(result)
};
return swift_getFunctionTypeMetadata(flagsArgsAndResult);
}
const FunctionTypeMetadata *
swift::swift_getFunctionTypeMetadata2(FunctionTypeFlags flags,
const void *arg0,
const void *arg1,
const Metadata *result) {
assert(flags.getNumArguments() == 2
&& "wrong number of arguments in function metadata flags?!");
const void *flagsArgsAndResult[] = {
reinterpret_cast<const void*>(flags.getIntValue()),
arg0,
arg1,
static_cast<const void *>(result)
};
return swift_getFunctionTypeMetadata(flagsArgsAndResult);
}
const FunctionTypeMetadata *
swift::swift_getFunctionTypeMetadata3(FunctionTypeFlags flags,
const void *arg0,
const void *arg1,
const void *arg2,
const Metadata *result) {
assert(flags.getNumArguments() == 3
&& "wrong number of arguments in function metadata flags?!");
const void *flagsArgsAndResult[] = {
reinterpret_cast<const void*>(flags.getIntValue()),
arg0,
arg1,
arg2,
static_cast<const void *>(result)
};
return swift_getFunctionTypeMetadata(flagsArgsAndResult);
}
const FunctionTypeMetadata *
swift::swift_getFunctionTypeMetadata(const void *flagsArgsAndResult[]) {
auto flags = FunctionTypeFlags::fromIntValue(size_t(flagsArgsAndResult[0]));
unsigned numArguments = flags.getNumArguments();
// Pick a value witness table appropriate to the function convention.
// All function types of a given convention have the same value semantics,
// so they share a value witness table.
const ValueWitnessTable *valueWitnesses;
switch (flags.getConvention()) {
case FunctionMetadataConvention::Swift:
valueWitnesses = &_TWVFT_T_;
break;
case FunctionMetadataConvention::Thin:
case FunctionMetadataConvention::CFunctionPointer:
valueWitnesses = &_TWVXfT_T_;
break;
case FunctionMetadataConvention::Block:
#if SWIFT_OBJC_INTEROP
// Blocks are ObjC objects, so can share the Builtin.UnknownObject value
// witnesses.
valueWitnesses = &_TWVBO;
#else
assert(false && "objc block without objc interop?");
#endif
break;
}
// Search the cache.
unsigned numKeyArguments =
// 1 flags word,
1 +
// N argument types (with inout bit set),
numArguments +
// and 1 result type
1;
auto &Types = FunctionTypes.get();
auto entry = Types.findOrAdd(flagsArgsAndResult, numKeyArguments,
[&]() -> FunctionCacheEntry* {
// Create a new entry for the cache.
auto entry = FunctionCacheEntry::allocate(
Types.getAllocator(),
flagsArgsAndResult,
numKeyArguments,
numArguments * sizeof(FunctionTypeMetadata::Argument));
auto metadata = entry->getData();
metadata->setKind(MetadataKind::Function);
metadata->ValueWitnesses = valueWitnesses;
metadata->Flags = flags;
metadata->ResultType = reinterpret_cast<const Metadata *>(
flagsArgsAndResult[1 + numArguments]);
for (size_t i = 0; i < numArguments; ++i) {
auto arg = FunctionTypeMetadata::Argument::getFromOpaqueValue(
flagsArgsAndResult[i+1]);
metadata->getArguments()[i] = arg;
}
return entry;
});
return entry->getData();
}
/*** Tuples ****************************************************************/
namespace {
class TupleCacheEntry;
struct TupleCacheEntryHeader : CacheEntryHeader<TupleCacheEntry> {
size_t NumArguments;
};
class TupleCacheEntry
: public CacheEntry<TupleCacheEntry, TupleCacheEntryHeader> {
public:
// NOTE: if you change the layout of this type, you'll also need
// to update tuple_getValueWitnesses().
ExtraInhabitantsValueWitnessTable Witnesses;
FullMetadata<TupleTypeMetadata> Metadata;
static const char *getName() { return "TupleCache"; }
TupleCacheEntry(size_t numArguments) {
NumArguments = numArguments;
}
size_t getNumArguments() const {
return Metadata.NumElements;
}
FullMetadata<TupleTypeMetadata> *getData() {
return &Metadata;
}
const FullMetadata<TupleTypeMetadata> *getData() const {
return &Metadata;
}
};
}
/// The uniquing structure for tuple type metadata.
static Lazy<MetadataCache<TupleCacheEntry>> TupleTypes;
/// Given a metatype pointer, produce the value-witness table for it.
/// This is equivalent to metatype->ValueWitnesses but more efficient.
static const ValueWitnessTable *tuple_getValueWitnesses(const Metadata *metatype) {
return ((const ExtraInhabitantsValueWitnessTable*) asFullMetadata(metatype)) - 1;
}
/// Generic tuple value witness for 'projectBuffer'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_projectBuffer(ValueBuffer *buffer,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsInline)
return reinterpret_cast<OpaqueValue*>(buffer);
else
return *reinterpret_cast<OpaqueValue**>(buffer);
}
/// Generic tuple value witness for 'allocateBuffer'
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_allocateBuffer(ValueBuffer *buffer,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsInline)
return reinterpret_cast<OpaqueValue*>(buffer);
auto wtable = tuple_getValueWitnesses(metatype);
auto value = (OpaqueValue*) swift_slowAlloc(wtable->size,
wtable->getAlignmentMask());
*reinterpret_cast<OpaqueValue**>(buffer) = value;
return value;
}
/// Generic tuple value witness for 'deallocateBuffer'.
template <bool IsPOD, bool IsInline>
static void tuple_deallocateBuffer(ValueBuffer *buffer,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsInline)
return;
auto wtable = tuple_getValueWitnesses(metatype);
auto value = *reinterpret_cast<OpaqueValue**>(buffer);
swift_slowDealloc(value, wtable->size, wtable->getAlignmentMask());
}
/// Generic tuple value witness for 'destroy'.
template <bool IsPOD, bool IsInline>
static void tuple_destroy(OpaqueValue *tuple, const Metadata *_metadata) {
auto &metadata = *(const TupleTypeMetadata*) _metadata;
assert(IsPOD == tuple_getValueWitnesses(&metadata)->isPOD());
assert(IsInline == tuple_getValueWitnesses(&metadata)->isValueInline());
if (IsPOD) return;
for (size_t i = 0, e = metadata.NumElements; i != e; ++i) {
auto &eltInfo = metadata.getElements()[i];
OpaqueValue *elt = eltInfo.findIn(tuple);
auto eltWitnesses = eltInfo.Type->getValueWitnesses();
eltWitnesses->destroy(elt, eltInfo.Type);
}
}
/// Generic tuple value witness for 'destroyArray'.
template <bool IsPOD, bool IsInline>
static void tuple_destroyArray(OpaqueValue *array, size_t n,
const Metadata *_metadata) {
auto &metadata = *(const TupleTypeMetadata*) _metadata;
assert(IsPOD == tuple_getValueWitnesses(&metadata)->isPOD());
assert(IsInline == tuple_getValueWitnesses(&metadata)->isValueInline());
if (IsPOD) return;
size_t stride = tuple_getValueWitnesses(&metadata)->stride;
char *bytes = (char*)array;
while (n--) {
tuple_destroy<IsPOD, IsInline>((OpaqueValue*)bytes, _metadata);
bytes += stride;
}
}
/// Generic tuple value witness for 'destroyBuffer'.
template <bool IsPOD, bool IsInline>
static void tuple_destroyBuffer(ValueBuffer *buffer, const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
auto tuple = tuple_projectBuffer<IsPOD, IsInline>(buffer, metatype);
tuple_destroy<IsPOD, IsInline>(tuple, metatype);
tuple_deallocateBuffer<IsPOD, IsInline>(buffer, metatype);
}
// The operation doesn't have to be initializeWithCopy, but they all
// have basically the same type.
typedef value_witness_types::initializeWithCopy *
ValueWitnessTable::*forEachOperation;
/// Perform an operation for each field of two tuples.
static OpaqueValue *tuple_forEachField(OpaqueValue *destTuple,
OpaqueValue *srcTuple,
const Metadata *_metatype,
forEachOperation member) {
auto &metatype = *(const TupleTypeMetadata*) _metatype;
for (size_t i = 0, e = metatype.NumElements; i != e; ++i) {
auto &eltInfo = metatype.getElement(i);
auto eltValueWitnesses = eltInfo.Type->getValueWitnesses();
OpaqueValue *destElt = eltInfo.findIn(destTuple);
OpaqueValue *srcElt = eltInfo.findIn(srcTuple);
(eltValueWitnesses->*member)(destElt, srcElt, eltInfo.Type);
}
return destTuple;
}
/// Perform a naive memcpy of src into dest.
static OpaqueValue *tuple_memcpy(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(metatype->getValueWitnesses()->isPOD());
return (OpaqueValue*)
memcpy(dest, src, metatype->getValueWitnesses()->getSize());
}
/// Perform a naive memcpy of n tuples from src into dest.
static OpaqueValue *tuple_memcpy_array(OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *metatype) {
assert(metatype->getValueWitnesses()->isPOD());
return (OpaqueValue*)
memcpy(dest, src, metatype->getValueWitnesses()->stride * n);
}
/// Perform a naive memmove of n tuples from src into dest.
static OpaqueValue *tuple_memmove_array(OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *metatype) {
assert(metatype->getValueWitnesses()->isPOD());
return (OpaqueValue*)
memmove(dest, src, metatype->getValueWitnesses()->stride * n);
}
/// Generic tuple value witness for 'initializeWithCopy'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeWithCopy(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memcpy(dest, src, metatype);
return tuple_forEachField(dest, src, metatype,
&ValueWitnessTable::initializeWithCopy);
}
/// Generic tuple value witness for 'initializeArrayWithCopy'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeArrayWithCopy(OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memcpy_array(dest, src, n, metatype);
char *destBytes = (char*)dest;
char *srcBytes = (char*)src;
size_t stride = tuple_getValueWitnesses(metatype)->stride;
while (n--) {
tuple_initializeWithCopy<IsPOD, IsInline>((OpaqueValue*)destBytes,
(OpaqueValue*)srcBytes,
metatype);
destBytes += stride; srcBytes += stride;
}
return dest;
}
/// Generic tuple value witness for 'initializeWithTake'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeWithTake(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memcpy(dest, src, metatype);
return tuple_forEachField(dest, src, metatype,
&ValueWitnessTable::initializeWithTake);
}
/// Generic tuple value witness for 'initializeArrayWithTakeFrontToBack'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeArrayWithTakeFrontToBack(
OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memmove_array(dest, src, n, metatype);
char *destBytes = (char*)dest;
char *srcBytes = (char*)src;
size_t stride = tuple_getValueWitnesses(metatype)->stride;
while (n--) {
tuple_initializeWithTake<IsPOD, IsInline>((OpaqueValue*)destBytes,
(OpaqueValue*)srcBytes,
metatype);
destBytes += stride; srcBytes += stride;
}
return dest;
}
/// Generic tuple value witness for 'initializeArrayWithTakeBackToFront'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeArrayWithTakeBackToFront(
OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memmove_array(dest, src, n, metatype);
size_t stride = tuple_getValueWitnesses(metatype)->stride;
char *destBytes = (char*)dest + n * stride;
char *srcBytes = (char*)src + n * stride;
while (n--) {
destBytes -= stride; srcBytes -= stride;
tuple_initializeWithTake<IsPOD, IsInline>((OpaqueValue*)destBytes,
(OpaqueValue*)srcBytes,
metatype);
}
return dest;
}
/// Generic tuple value witness for 'assignWithCopy'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_assignWithCopy(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsPOD) return tuple_memcpy(dest, src, metatype);
return tuple_forEachField(dest, src, metatype,
&ValueWitnessTable::assignWithCopy);
}
/// Generic tuple value witness for 'assignWithTake'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_assignWithTake(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *metatype) {
if (IsPOD) return tuple_memcpy(dest, src, metatype);
return tuple_forEachField(dest, src, metatype,
&ValueWitnessTable::assignWithTake);
}
/// Generic tuple value witness for 'initializeBufferWithCopy'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeBufferWithCopy(ValueBuffer *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
return tuple_initializeWithCopy<IsPOD, IsInline>(
tuple_allocateBuffer<IsPOD, IsInline>(dest, metatype),
src,
metatype);
}
/// Generic tuple value witness for 'initializeBufferWithTake'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeBufferWithTake(ValueBuffer *dest,
OpaqueValue *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
return tuple_initializeWithTake<IsPOD, IsInline>(
tuple_allocateBuffer<IsPOD, IsInline>(dest, metatype),
src,
metatype);
}
/// Generic tuple value witness for 'initializeBufferWithCopyOfBuffer'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeBufferWithCopyOfBuffer(ValueBuffer *dest,
ValueBuffer *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
return tuple_initializeBufferWithCopy<IsPOD, IsInline>(
dest,
tuple_projectBuffer<IsPOD, IsInline>(src, metatype),
metatype);
}
/// Generic tuple value witness for 'initializeBufferWithTakeOfBuffer'.
template <bool IsPOD, bool IsInline>
static OpaqueValue *tuple_initializeBufferWithTakeOfBuffer(ValueBuffer *dest,
ValueBuffer *src,
const Metadata *metatype) {
assert(IsPOD == tuple_getValueWitnesses(metatype)->isPOD());
assert(IsInline == tuple_getValueWitnesses(metatype)->isValueInline());
if (IsInline) {
return tuple_initializeWithTake<IsPOD, IsInline>(
tuple_projectBuffer<IsPOD, IsInline>(dest, metatype),
tuple_projectBuffer<IsPOD, IsInline>(src, metatype),
metatype);
} else {
dest->PrivateData[0] = src->PrivateData[0];
return (OpaqueValue*) dest->PrivateData[0];
}
}
static void tuple_storeExtraInhabitant(OpaqueValue *tuple,
int index,
const Metadata *_metatype) {
auto &metatype = *(const TupleTypeMetadata*) _metatype;
auto &eltInfo = metatype.getElement(0);
assert(eltInfo.Offset == 0);
OpaqueValue *elt = tuple;
eltInfo.Type->vw_storeExtraInhabitant(elt, index);
}
static int tuple_getExtraInhabitantIndex(const OpaqueValue *tuple,
const Metadata *_metatype) {
auto &metatype = *(const TupleTypeMetadata*) _metatype;
auto &eltInfo = metatype.getElement(0);
assert(eltInfo.Offset == 0);
const OpaqueValue *elt = tuple;
return eltInfo.Type->vw_getExtraInhabitantIndex(elt);
}
/// Various standard witness table for tuples.
static const ValueWitnessTable tuple_witnesses_pod_inline = {
#define TUPLE_WITNESS(NAME) &tuple_##NAME<true, true>,
FOR_ALL_FUNCTION_VALUE_WITNESSES(TUPLE_WITNESS)
#undef TUPLE_WITNESS
0,
ValueWitnessFlags(),
0
};
static const ValueWitnessTable tuple_witnesses_nonpod_inline = {
#define TUPLE_WITNESS(NAME) &tuple_##NAME<false, true>,
FOR_ALL_FUNCTION_VALUE_WITNESSES(TUPLE_WITNESS)
#undef TUPLE_WITNESS
0,
ValueWitnessFlags(),
0
};
static const ValueWitnessTable tuple_witnesses_pod_noninline = {
#define TUPLE_WITNESS(NAME) &tuple_##NAME<true, false>,
FOR_ALL_FUNCTION_VALUE_WITNESSES(TUPLE_WITNESS)
#undef TUPLE_WITNESS
0,
ValueWitnessFlags(),
0
};
static const ValueWitnessTable tuple_witnesses_nonpod_noninline = {
#define TUPLE_WITNESS(NAME) &tuple_##NAME<false, false>,
FOR_ALL_FUNCTION_VALUE_WITNESSES(TUPLE_WITNESS)
#undef TUPLE_WITNESS
0,
ValueWitnessFlags(),
0
};
namespace {
struct BasicLayout {
size_t size;
ValueWitnessFlags flags;
size_t stride;
static constexpr BasicLayout initialForValueType() {
return {0, ValueWitnessFlags().withAlignment(1).withPOD(true), 0};
}
static constexpr BasicLayout initialForHeapObject() {
return {sizeof(HeapObject),
ValueWitnessFlags().withAlignment(alignof(HeapObject)),
sizeof(HeapObject)};
}
};
static size_t roundUpToAlignMask(size_t size, size_t alignMask) {
return (size + alignMask) & ~alignMask;
}
/// Perform basic sequential layout given a vector of metadata pointers,
/// calling a functor with the offset of each field, and returning the
/// final layout characteristics of the type.
/// FUNCTOR should have signature:
/// void (size_t index, const Metadata *type, size_t offset)
template<typename FUNCTOR, typename LAYOUT>
void performBasicLayout(BasicLayout &layout,
const LAYOUT * const *elements,
size_t numElements,
FUNCTOR &&f) {
size_t size = layout.size;
size_t alignMask = layout.flags.getAlignmentMask();
bool isPOD = layout.flags.isPOD();
bool isBitwiseTakable = layout.flags.isBitwiseTakable();
for (unsigned i = 0; i != numElements; ++i) {
auto elt = elements[i];
// Lay out this element.
const TypeLayout *eltLayout = elt->getTypeLayout();
size = roundUpToAlignMask(size, eltLayout->flags.getAlignmentMask());
// Report this record to the functor.
f(i, elt, size);
// Update the size and alignment of the aggregate..
size += eltLayout->size;
alignMask = std::max(alignMask, eltLayout->flags.getAlignmentMask());
if (!eltLayout->flags.isPOD()) isPOD = false;
if (!eltLayout->flags.isBitwiseTakable()) isBitwiseTakable = false;
}
bool isInline = ValueWitnessTable::isValueInline(size, alignMask + 1);
layout.size = size;
layout.flags = ValueWitnessFlags().withAlignmentMask(alignMask)
.withPOD(isPOD)
.withBitwiseTakable(isBitwiseTakable)
.withInlineStorage(isInline);
layout.stride = roundUpToAlignMask(size, alignMask);
}
} // end anonymous namespace
const TupleTypeMetadata *
swift::swift_getTupleTypeMetadata(size_t numElements,
const Metadata * const *elements,
const char *labels,
const ValueWitnessTable *proposedWitnesses) {
// Bypass the cache for the empty tuple. We might reasonably get called
// by generic code, like a demangler that produces type objects.
if (numElements == 0) return &_TMT_;
// Search the cache.
// FIXME: include labels when uniquing!
auto genericArgs = (const void * const *) elements;
auto &Types = TupleTypes.get();
auto entry = Types.findOrAdd(genericArgs, numElements,
[&]() -> TupleCacheEntry* {
// Create a new entry for the cache.
typedef TupleTypeMetadata::Element Element;
// Allocate the tuple cache entry, which includes space for both the
// metadata and a value-witness table.
auto entry = TupleCacheEntry::allocate(Types.getAllocator(),
genericArgs, numElements,
numElements * sizeof(Element));
auto witnesses = &entry->Witnesses;
auto metadata = entry->getData();
metadata->setKind(MetadataKind::Tuple);
metadata->ValueWitnesses = witnesses;
metadata->NumElements = numElements;
metadata->Labels = labels;
// Perform basic layout on the tuple.
auto layout = BasicLayout::initialForValueType();
performBasicLayout(layout, elements, numElements,
[&](size_t i, const Metadata *elt, size_t offset) {
metadata->getElement(i).Type = elt;
metadata->getElement(i).Offset = offset;
});
witnesses->size = layout.size;
witnesses->flags = layout.flags;
witnesses->stride = layout.stride;
// Copy the function witnesses in, either from the proposed
// witnesses or from the standard table.
if (!proposedWitnesses) {
// For a tuple with a single element, just use the witnesses for
// the element type.
if (numElements == 1) {
proposedWitnesses = elements[0]->getValueWitnesses();
// Otherwise, use generic witnesses (when we can't pattern-match
// into something better).
} else if (layout.flags.isInlineStorage()
&& layout.flags.isPOD()) {
if (layout.size == 8 && layout.flags.getAlignmentMask() == 7)
proposedWitnesses = &_TWVBi64_;
else if (layout.size == 4 && layout.flags.getAlignmentMask() == 3)
proposedWitnesses = &_TWVBi32_;
else if (layout.size == 2 && layout.flags.getAlignmentMask() == 1)
proposedWitnesses = &_TWVBi16_;
else if (layout.size == 1)
proposedWitnesses = &_TWVBi8_;
else
proposedWitnesses = &tuple_witnesses_pod_inline;
} else if (layout.flags.isInlineStorage()
&& !layout.flags.isPOD()) {
proposedWitnesses = &tuple_witnesses_nonpod_inline;
} else if (!layout.flags.isInlineStorage()
&& layout.flags.isPOD()) {
proposedWitnesses = &tuple_witnesses_pod_noninline;
} else {
assert(!layout.flags.isInlineStorage()
&& !layout.flags.isPOD());
proposedWitnesses = &tuple_witnesses_nonpod_noninline;
}
}
#define ASSIGN_TUPLE_WITNESS(NAME) \
witnesses->NAME = proposedWitnesses->NAME;
FOR_ALL_FUNCTION_VALUE_WITNESSES(ASSIGN_TUPLE_WITNESS)
#undef ASSIGN_TUPLE_WITNESS
// We have extra inhabitants if the first element does.
// FIXME: generalize this.
if (auto firstEltEIVWT = dyn_cast<ExtraInhabitantsValueWitnessTable>(
elements[0]->getValueWitnesses())) {
witnesses->flags = witnesses->flags.withExtraInhabitants(true);
witnesses->extraInhabitantFlags = firstEltEIVWT->extraInhabitantFlags;
witnesses->storeExtraInhabitant = tuple_storeExtraInhabitant;
witnesses->getExtraInhabitantIndex = tuple_getExtraInhabitantIndex;
}
return entry;
});
return entry->getData();
}
const TupleTypeMetadata *
swift::swift_getTupleTypeMetadata2(const Metadata *elt0, const Metadata *elt1,
const char *labels,
const ValueWitnessTable *proposedWitnesses) {
const Metadata *elts[] = { elt0, elt1 };
return swift_getTupleTypeMetadata(2, elts, labels, proposedWitnesses);
}
const TupleTypeMetadata *
swift::swift_getTupleTypeMetadata3(const Metadata *elt0, const Metadata *elt1,
const Metadata *elt2,
const char *labels,
const ValueWitnessTable *proposedWitnesses) {
const Metadata *elts[] = { elt0, elt1, elt2 };
return swift_getTupleTypeMetadata(3, elts, labels, proposedWitnesses);
}
/*** Common value witnesses ************************************************/
// Value witness methods for an arbitrary trivial type.
// The buffer operations assume that the value is stored indirectly, because
// installCommonValueWitnesses will install the direct equivalents instead.
namespace {
template<typename T>
struct pointer_function_cast_impl;
template<typename OutRet, typename...OutArgs>
struct pointer_function_cast_impl<OutRet * (OutArgs *...)> {
template<typename InRet, typename...InArgs>
static constexpr auto perform(InRet * (*function)(InArgs *...))
-> OutRet * (*)(OutArgs *...)
{
static_assert(sizeof...(InArgs) == sizeof...(OutArgs),
"cast changed number of arguments");
return (OutRet *(*)(OutArgs *...))function;
}
};
template<typename...OutArgs>
struct pointer_function_cast_impl<void (OutArgs *...)> {
template<typename...InArgs>
static constexpr auto perform(void (*function)(InArgs *...))
-> void (*)(OutArgs *...)
{
static_assert(sizeof...(InArgs) == sizeof...(OutArgs),
"cast changed number of arguments");
return (void (*)(OutArgs *...))function;
}
};
}
/// Cast a function that takes all pointer arguments and returns to a
/// function type that takes different pointer arguments and returns.
/// In any reasonable calling convention the input and output function types
/// should be ABI-compatible.
template<typename Out, typename In>
static constexpr Out *pointer_function_cast(In *function) {
return pointer_function_cast_impl<Out>::perform(function);
}
static void pod_indirect_deallocateBuffer(ValueBuffer *buffer,
const Metadata *self) {
auto value = *reinterpret_cast<OpaqueValue**>(buffer);
auto wtable = self->getValueWitnesses();
swift_slowDealloc(value, wtable->size, wtable->getAlignmentMask());
}
#define pod_indirect_destroyBuffer \
pointer_function_cast<value_witness_types::destroyBuffer>(pod_indirect_deallocateBuffer)
static OpaqueValue *pod_indirect_initializeBufferWithCopyOfBuffer(
ValueBuffer *dest, ValueBuffer *src, const Metadata *self) {
auto wtable = self->getValueWitnesses();
auto destBuf = (OpaqueValue*)swift_slowAlloc(wtable->size,
wtable->getAlignmentMask());
*reinterpret_cast<OpaqueValue**>(dest) = destBuf;
OpaqueValue *srcBuf = *reinterpret_cast<OpaqueValue**>(src);
memcpy(destBuf, srcBuf, wtable->size);
return destBuf;
}
static OpaqueValue *pod_indirect_initializeBufferWithTakeOfBuffer(
ValueBuffer *dest, ValueBuffer *src, const Metadata *self) {
memcpy(dest, src, sizeof(ValueBuffer));
return *reinterpret_cast<OpaqueValue**>(dest);
}
static OpaqueValue *pod_indirect_projectBuffer(ValueBuffer *buffer,
const Metadata *self) {
return *reinterpret_cast<OpaqueValue**>(buffer);
}
static OpaqueValue *pod_indirect_allocateBuffer(ValueBuffer *buffer,
const Metadata *self) {
auto wtable = self->getValueWitnesses();
auto destBuf = (OpaqueValue*)swift_slowAlloc(wtable->size,
wtable->getAlignmentMask());
*reinterpret_cast<OpaqueValue**>(buffer) = destBuf;
return destBuf;
}
static void pod_noop(void *object, const Metadata *self) {
}
#define pod_direct_destroy \
pointer_function_cast<value_witness_types::destroy>(pod_noop)
#define pod_indirect_destroy pod_direct_destroy
#define pod_direct_destroyBuffer \
pointer_function_cast<value_witness_types::destroyBuffer>(pod_noop)
#define pod_direct_deallocateBuffer \
pointer_function_cast<value_witness_types::deallocateBuffer>(pod_noop)
static void *pod_noop_return(void *object, const Metadata *self) {
return object;
}
#define pod_direct_projectBuffer \
pointer_function_cast<value_witness_types::projectBuffer>(pod_noop_return)
#define pod_direct_allocateBuffer \
pointer_function_cast<value_witness_types::allocateBuffer>(pod_noop_return)
static OpaqueValue *pod_indirect_initializeBufferWithCopy(ValueBuffer *dest,
OpaqueValue *src,
const Metadata *self){
auto wtable = self->getValueWitnesses();
auto destBuf = (OpaqueValue*)swift_slowAlloc(wtable->size,
wtable->getAlignmentMask());
*reinterpret_cast<OpaqueValue**>(dest) = destBuf;
memcpy(destBuf, src, wtable->size);
return destBuf;
}
#define pod_indirect_initializeBufferWithTake pod_indirect_initializeBufferWithCopy
static OpaqueValue *pod_direct_initializeWithCopy(OpaqueValue *dest,
OpaqueValue *src,
const Metadata *self) {
memcpy(dest, src, self->getValueWitnesses()->size);
return dest;
}
#define pod_indirect_initializeWithCopy pod_direct_initializeWithCopy
#define pod_direct_initializeBufferWithCopyOfBuffer \
pointer_function_cast<value_witness_types::initializeBufferWithCopyOfBuffer> \
(pod_direct_initializeWithCopy)
#define pod_direct_initializeBufferWithTakeOfBuffer \
pointer_function_cast<value_witness_types::initializeBufferWithTakeOfBuffer> \
(pod_direct_initializeWithCopy)
#define pod_direct_initializeBufferWithCopy \
pointer_function_cast<value_witness_types::initializeBufferWithCopy> \
(pod_direct_initializeWithCopy)
#define pod_direct_initializeBufferWithTake \
pointer_function_cast<value_witness_types::initializeBufferWithTake> \
(pod_direct_initializeWithCopy)
#define pod_direct_assignWithCopy pod_direct_initializeWithCopy
#define pod_indirect_assignWithCopy pod_direct_initializeWithCopy
#define pod_direct_initializeWithTake pod_direct_initializeWithCopy
#define pod_indirect_initializeWithTake pod_direct_initializeWithCopy
#define pod_direct_assignWithTake pod_direct_initializeWithCopy
#define pod_indirect_assignWithTake pod_direct_initializeWithCopy
static void pod_direct_destroyArray(OpaqueValue *, size_t, const Metadata *) {
// noop
}
#define pod_indirect_destroyArray pod_direct_destroyArray
static OpaqueValue *pod_direct_initializeArrayWithCopy(OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *self) {
auto totalSize = self->getValueWitnesses()->stride * n;
memcpy(dest, src, totalSize);
return dest;
}
#define pod_indirect_initializeArrayWithCopy pod_direct_initializeArrayWithCopy
static OpaqueValue *pod_direct_initializeArrayWithTakeFrontToBack(
OpaqueValue *dest,
OpaqueValue *src,
size_t n,
const Metadata *self) {
auto totalSize = self->getValueWitnesses()->stride * n;
memmove(dest, src, totalSize);
return dest;
}
#define pod_direct_initializeArrayWithTakeBackToFront \
pod_direct_initializeArrayWithTakeFrontToBack
#define pod_indirect_initializeArrayWithTakeFrontToBack \
pod_direct_initializeArrayWithTakeFrontToBack
#define pod_indirect_initializeArrayWithTakeBackToFront \
pod_direct_initializeArrayWithTakeFrontToBack
static constexpr uint64_t sizeWithAlignmentMask(uint64_t size,
uint64_t alignmentMask) {
return (size << 16) | alignmentMask;
}
void swift::installCommonValueWitnesses(ValueWitnessTable *vwtable) {
auto flags = vwtable->flags;
if (flags.isPOD()) {
// Use POD value witnesses.
// If the value has a common size and alignment, use specialized value
// witnesses we already have lying around for the builtin types.
const ValueWitnessTable *commonVWT;
switch (sizeWithAlignmentMask(vwtable->size, vwtable->getAlignmentMask())) {
default:
// For uncommon layouts, use value witnesses that work with an arbitrary
// size and alignment.
if (flags.isInlineStorage()) {
#define INSTALL_POD_DIRECT_WITNESS(NAME) vwtable->NAME = pod_direct_##NAME;
FOR_ALL_FUNCTION_VALUE_WITNESSES(INSTALL_POD_DIRECT_WITNESS)
#undef INSTALL_POD_DIRECT_WITNESS
} else {
#define INSTALL_POD_INDIRECT_WITNESS(NAME) vwtable->NAME = pod_indirect_##NAME;
FOR_ALL_FUNCTION_VALUE_WITNESSES(INSTALL_POD_INDIRECT_WITNESS)
#undef INSTALL_POD_INDIRECT_WITNESS
}
return;
case sizeWithAlignmentMask(1, 0):
commonVWT = &_TWVBi8_;
break;
case sizeWithAlignmentMask(2, 1):
commonVWT = &_TWVBi16_;
break;
case sizeWithAlignmentMask(4, 3):
commonVWT = &_TWVBi32_;
break;
case sizeWithAlignmentMask(8, 7):
commonVWT = &_TWVBi64_;
break;
case sizeWithAlignmentMask(16, 15):
commonVWT = &_TWVBi128_;
break;
case sizeWithAlignmentMask(32, 31):
commonVWT = &_TWVBi256_;
break;
}
#define INSTALL_POD_COMMON_WITNESS(NAME) vwtable->NAME = commonVWT->NAME;
FOR_ALL_FUNCTION_VALUE_WITNESSES(INSTALL_POD_COMMON_WITNESS)
#undef INSTALL_POD_COMMON_WITNESS
return;
}
if (flags.isBitwiseTakable()) {
// Use POD value witnesses for operations that do an initializeWithTake.
if (flags.isInlineStorage()) {
vwtable->initializeWithTake = pod_direct_initializeWithTake;
vwtable->initializeBufferWithTakeOfBuffer
= pod_direct_initializeBufferWithTakeOfBuffer;
vwtable->initializeArrayWithTakeFrontToBack
= pod_direct_initializeArrayWithTakeFrontToBack;
vwtable->initializeArrayWithTakeBackToFront
= pod_direct_initializeArrayWithTakeBackToFront;
} else {
vwtable->initializeWithTake = pod_indirect_initializeWithTake;
vwtable->initializeBufferWithTakeOfBuffer
= pod_indirect_initializeBufferWithTakeOfBuffer;
vwtable->initializeArrayWithTakeFrontToBack
= pod_indirect_initializeArrayWithTakeFrontToBack;
vwtable->initializeArrayWithTakeBackToFront
= pod_indirect_initializeArrayWithTakeBackToFront;
}
return;
}
if (!flags.isInlineStorage()) {
// For values stored out-of-line, initializeBufferWithTakeOfBuffer is
// always a memcpy.
vwtable->initializeBufferWithTakeOfBuffer
= pod_indirect_initializeBufferWithTakeOfBuffer;
return;
}
}
/*** Structs ***************************************************************/
/// Initialize the value witness table and struct field offset vector for a
/// struct, using the "Universal" layout strategy.
void swift::swift_initStructMetadata_UniversalStrategy(size_t numFields,
const TypeLayout * const *fieldTypes,
size_t *fieldOffsets,
ValueWitnessTable *vwtable) {
auto layout = BasicLayout::initialForValueType();
performBasicLayout(layout, fieldTypes, numFields,
[&](size_t i, const TypeLayout *fieldType, size_t offset) {
assignUnlessEqual(fieldOffsets[i], offset);
});
vwtable->size = layout.size;
vwtable->flags = layout.flags;
vwtable->stride = layout.stride;
// Substitute in better value witnesses if we have them.
installCommonValueWitnesses(vwtable);
// We have extra inhabitants if the first element does.
// FIXME: generalize this.
if (fieldTypes[0]->flags.hasExtraInhabitants()) {
vwtable->flags = vwtable->flags.withExtraInhabitants(true);
auto xiVWT = cast<ExtraInhabitantsValueWitnessTable>(vwtable);
xiVWT->extraInhabitantFlags = fieldTypes[0]->getExtraInhabitantFlags();
// The compiler should already have initialized these.
assert(xiVWT->storeExtraInhabitant);
assert(xiVWT->getExtraInhabitantIndex);
}
}
/*** Classes ***************************************************************/
namespace {
/// The structure of ObjC class ivars as emitted by compilers.
struct ClassIvarEntry {
size_t *Offset;
const char *Name;
const char *Type;
uint32_t Log2Alignment;
uint32_t Size;
};
/// The structure of ObjC class ivar lists as emitted by compilers.
struct ClassIvarList {
uint32_t EntrySize;
uint32_t Count;
ClassIvarEntry *getIvars() {
return reinterpret_cast<ClassIvarEntry*>(this+1);
}
const ClassIvarEntry *getIvars() const {
return reinterpret_cast<const ClassIvarEntry*>(this+1);
}
};
/// The structure of ObjC class rodata as emitted by compilers.
struct ClassROData {
uint32_t Flags;
uint32_t InstanceStart;
uint32_t InstanceSize;
#ifdef __LP64__
uint32_t Reserved;
#endif
const uint8_t *IvarLayout;
const char *Name;
const void *MethodList;
const void *ProtocolList;
ClassIvarList *IvarList;
const uint8_t *WeakIvarLayout;
const void *PropertyList;
};
}
#if SWIFT_OBJC_INTEROP
static uint32_t getLog2AlignmentFromMask(size_t alignMask) {
assert(((alignMask + 1) & alignMask) == 0 &&
"not an alignment mask!");
uint32_t log2 = 0;
while ((1 << log2) != (alignMask + 1))
log2++;
return log2;
}
static inline ClassROData *getROData(ClassMetadata *theClass) {
return (ClassROData*) (theClass->Data & ~uintptr_t(1));
}
static void _swift_initGenericClassObjCName(ClassMetadata *theClass) {
// Use the remangler to generate a mangled name from the type metadata.
auto demangling = _swift_buildDemanglingForMetadata(theClass);
// Remangle that into a new type mangling string.
auto typeNode
= Demangle::NodeFactory::create(Demangle::Node::Kind::TypeMangling);
typeNode->addChild(demangling);
auto globalNode
= Demangle::NodeFactory::create(Demangle::Node::Kind::Global);
globalNode->addChild(typeNode);
auto string = Demangle::mangleNode(globalNode);
auto fullNameBuf = (char*)swift_slowAlloc(string.size() + 1, 0);
memcpy(fullNameBuf, string.c_str(), string.size() + 1);
auto theMetaclass = (ClassMetadata *)object_getClass((id)theClass);
getROData(theClass)->Name = fullNameBuf;
getROData(theMetaclass)->Name = fullNameBuf;
}
#endif
/// Initialize the invariant superclass components of a class metadata,
/// such as the generic type arguments, field offsets, and so on.
///
/// This may also relocate the metadata object if it wasn't allocated
/// with enough space.
static ClassMetadata *_swift_initializeSuperclass(ClassMetadata *theClass,
bool copyFieldOffsetVectors) {
#if SWIFT_OBJC_INTEROP
// If the class is generic, we need to give it a name for Objective-C.
if (theClass->getDescription()->GenericParams.isGeneric())
_swift_initGenericClassObjCName(theClass);
#endif
const ClassMetadata *theSuperclass = theClass->SuperClass;
if (theSuperclass == nullptr)
return theClass;
// Relocate the metadata if necessary.
//
// For now, we assume that relocation is only required when the parent
// class has prefix matter we didn't know about. This isn't consistent
// with general class resilience, however.
if (theSuperclass->isTypeMetadata()) {
auto superAP = theSuperclass->getClassAddressPoint();
auto oldClassAP = theClass->getClassAddressPoint();
if (superAP > oldClassAP) {
size_t extraPrefixSize = superAP - oldClassAP;
size_t oldClassSize = theClass->getClassSize();
// Allocate a new metadata object.
auto rawNewClass = (char*) malloc(extraPrefixSize + oldClassSize);
auto rawOldClass = (const char*) theClass;
auto rawSuperclass = (const char*) theSuperclass;
// Copy the extra prefix from the superclass.
memcpy((void**) (rawNewClass),
(void* const *) (rawSuperclass - superAP),
extraPrefixSize);
// Copy the rest of the data from the derived class.
memcpy((void**) (rawNewClass + extraPrefixSize),
(void* const *) (rawOldClass - oldClassAP),
oldClassSize);
// Update the class extents on the new metadata object.
theClass = reinterpret_cast<ClassMetadata*>(rawNewClass + oldClassAP);
theClass->setClassAddressPoint(superAP);
theClass->setClassSize(extraPrefixSize + oldClassSize);
// The previous metadata should be global data, so we have no real
// choice but to drop it on the floor.
}
}
// If any ancestor classes have generic parameters or field offset
// vectors, inherit them.
auto ancestor = theSuperclass;
auto *classWords = reinterpret_cast<uintptr_t *>(theClass);
auto *superWords = reinterpret_cast<const uintptr_t *>(theSuperclass);
while (ancestor && ancestor->isTypeMetadata()) {
auto &description = ancestor->getDescription();
auto &genericParams = description->GenericParams;
// Copy the parent type.
if (genericParams.Flags.hasParent()) {
memcpy(classWords + genericParams.Offset - 1,
superWords + genericParams.Offset - 1,
sizeof(uintptr_t));
}
// Copy the generic requirements.
if (genericParams.hasGenericRequirements()) {
unsigned numParamWords = genericParams.NumGenericRequirements;
memcpy(classWords + genericParams.Offset,
superWords + genericParams.Offset,
numParamWords * sizeof(uintptr_t));
}
// Copy the field offsets.
if (copyFieldOffsetVectors &&
description->Class.hasFieldOffsetVector()) {
unsigned fieldOffsetVector = description->Class.FieldOffsetVectorOffset;
memcpy(classWords + fieldOffsetVector,
superWords + fieldOffsetVector,
description->Class.NumFields * sizeof(uintptr_t));
}
ancestor = ancestor->SuperClass;
}
#if SWIFT_OBJC_INTEROP
// Set up the superclass of the metaclass, which is the metaclass of the
// superclass.
auto theMetaclass = (ClassMetadata *)object_getClass((id)theClass);
auto theSuperMetaclass
= (const ClassMetadata *)object_getClass((id)theSuperclass);
theMetaclass->SuperClass = theSuperMetaclass;
#endif
return theClass;
}
#if SWIFT_OBJC_INTEROP
static MetadataAllocator &getResilientMetadataAllocator() {
// This should be constant-initialized, but this is safe.
static MetadataAllocator allocator;
return allocator;
}
#endif
/// Initialize the field offset vector for a dependent-layout class, using the
/// "Universal" layout strategy.
ClassMetadata *
swift::swift_initClassMetadata_UniversalStrategy(ClassMetadata *self,
size_t numFields,
const ClassFieldLayout *fieldLayouts,
size_t *fieldOffsets) {
self = _swift_initializeSuperclass(self, /*copyFieldOffsetVectors=*/true);
// Start layout by appending to a standard heap object header.
size_t size, alignMask;
#if SWIFT_OBJC_INTEROP
ClassROData *rodata = getROData(self);
#endif
// If we have a superclass, start from its size and alignment instead.
if (classHasSuperclass(self)) {
const ClassMetadata *super = self->SuperClass;
// This is straightforward if the superclass is Swift.
#if SWIFT_OBJC_INTEROP
if (super->isTypeMetadata()) {
#endif
size = super->getInstanceSize();
alignMask = super->getInstanceAlignMask();
#if SWIFT_OBJC_INTEROP
// If it's Objective-C, start layout from our static notion of
// where the superclass starts. Objective-C expects us to have
// generated a correct ivar layout, which it will simply slide if
// it needs to.
} else {
size = rodata->InstanceStart;
alignMask = 0xF; // malloc alignment guarantee
}
#endif
// If we don't have a formal superclass, start with the basic heap header.
} else {
auto heapLayout = BasicLayout::initialForHeapObject();
size = heapLayout.size;
alignMask = heapLayout.flags.getAlignmentMask();
}
#if SWIFT_OBJC_INTEROP
// In ObjC interop mode, we have up to two places we need each correct
// ivar offset to end up:
//
// - the global ivar offset in the RO-data; this should only exist
// if the class layout (up to this ivar) is not actually dependent
//
// - the field offset vector (fieldOffsets)
//
// When we ask the ObjC runtime to lay out this class, we need the
// RO-data to point to the field offset vector, even if the layout
// is not dependent. The RO-data is not shared between
// instantiations, but the global ivar offset is (by definition).
// If the compiler didn't have the correct static size for the
// superclass (i.e. if rodata->InstanceStart is wrong), a previous
// instantiation might have already slid the global offset to the
// correct place; we need the ObjC runtime to see a pre-slid value,
// and it's not safe to briefly unslide it and let the runtime slide
// it back because there might already be concurrent code relying on
// the global ivar offset.
//
// So we need to the remember the addresses of the global ivar offsets.
// We use this lazily-filled SmallVector to do so.
const unsigned NumInlineGlobalIvarOffsets = 8;
size_t *_inlineGlobalIvarOffsets[NumInlineGlobalIvarOffsets];
size_t **_globalIvarOffsets = nullptr;
auto getGlobalIvarOffsets = [&]() -> size_t** {
if (!_globalIvarOffsets) {
if (numFields <= NumInlineGlobalIvarOffsets) {
_globalIvarOffsets = _inlineGlobalIvarOffsets;
} else {
_globalIvarOffsets = new size_t*[numFields];
}
// Make sure all the entries start out null.
memset(_globalIvarOffsets, 0, sizeof(size_t*) * numFields);
}
return _globalIvarOffsets;
};
// Ensure that Objective-C does layout starting from the right
// offset. This needs to exactly match the superclass rodata's
// InstanceSize in cases where the compiler decided that we didn't
// really have a resilient ObjC superclass, because the compiler
// might hardcode offsets in that case, so we can't slide ivars.
// Fortunately, the cases where that happens are exactly the
// situations where our entire superclass hierarchy is defined
// in Swift. (But note that ObjC might think we have a superclass
// even if Swift doesn't, because of SwiftObject.)
rodata->InstanceStart = size;
auto genericPattern = self->getDescription()->getGenericMetadataPattern();
auto &allocator =
genericPattern ? unsafeGetInitializedCache(genericPattern).getAllocator()
: getResilientMetadataAllocator();
// Always clone the ivar descriptors.
if (numFields) {
const ClassIvarList *dependentIvars = rodata->IvarList;
assert(dependentIvars->Count == numFields);
assert(dependentIvars->EntrySize == sizeof(ClassIvarEntry));
auto ivarListSize = sizeof(ClassIvarList) +
numFields * sizeof(ClassIvarEntry);
auto ivars = (ClassIvarList*) allocator.alloc(ivarListSize);
memcpy(ivars, dependentIvars, ivarListSize);
rodata->IvarList = ivars;
for (unsigned i = 0; i != numFields; ++i) {
ClassIvarEntry &ivar = ivars->getIvars()[i];
// Remember the global ivar offset if present.
if (ivar.Offset) {
getGlobalIvarOffsets()[i] = ivar.Offset;
}
// Change the ivar offset to point to the respective entry of
// the field-offset vector, as discussed above.
ivar.Offset = &fieldOffsets[i];
// If the ivar's size doesn't match the field layout we
// computed, overwrite it and give it better type information.
if (ivar.Size != fieldLayouts[i].Size) {
ivar.Size = fieldLayouts[i].Size;
ivar.Type = nullptr;
ivar.Log2Alignment =
getLog2AlignmentFromMask(fieldLayouts[i].AlignMask);
}
}
}
#endif
// Okay, now do layout.
for (unsigned i = 0; i != numFields; ++i) {
// Skip empty fields.
if (fieldOffsets[i] == 0 && fieldLayouts[i].Size == 0)
continue;
auto offset = roundUpToAlignMask(size, fieldLayouts[i].AlignMask);
fieldOffsets[i] = offset;
size = offset + fieldLayouts[i].Size;
alignMask = std::max(alignMask, fieldLayouts[i].AlignMask);
}
// Save the final size and alignment into the metadata record.
assert(self->isTypeMetadata());
self->setInstanceSize(size);
self->setInstanceAlignMask(alignMask);
#if SWIFT_OBJC_INTEROP
// Save the size into the Objective-C metadata as well.
rodata->InstanceSize = size;
// Register this class with the runtime. This will also cause the
// runtime to lay us out.
swift_instantiateObjCClass(self);
// If we saved any global ivar offsets, make sure we write back to them.
if (_globalIvarOffsets) {
for (unsigned i = 0; i != numFields; ++i) {
if (!_globalIvarOffsets[i]) continue;
// To avoid dirtying memory, only write to the global ivar
// offset if it's actually wrong.
if (*_globalIvarOffsets[i] != fieldOffsets[i])
*_globalIvarOffsets[i] = fieldOffsets[i];
}
// Free the out-of-line if we allocated one.
if (_globalIvarOffsets != _inlineGlobalIvarOffsets) {
delete [] _globalIvarOffsets;
}
}
#endif
return self;
}
/// \brief Fetch the type metadata associated with the formal dynamic
/// type of the given (possibly Objective-C) object. The formal
/// dynamic type ignores dynamic subclasses such as those introduced
/// by KVO.
///
/// The object pointer may be a tagged pointer, but cannot be null.
const Metadata *swift::swift_getObjectType(HeapObject *object) {
auto classAsMetadata = _swift_getClass(object);
if (classAsMetadata->isTypeMetadata()) return classAsMetadata;
return swift_getObjCClassMetadata(classAsMetadata);
}
/*** Metatypes *************************************************************/
namespace {
class MetatypeCacheEntry : public CacheEntry<MetatypeCacheEntry> {
FullMetadata<MetatypeMetadata> Metadata;
public:
static const char *getName() { return "MetatypeCache"; }
MetatypeCacheEntry(size_t numArguments) {}
static constexpr size_t getNumArguments() {
return 1;
}
FullMetadata<MetatypeMetadata> *getData() {
return &Metadata;
}
const FullMetadata<MetatypeMetadata> *getData() const {
return &Metadata;
}
};
}
/// The uniquing structure for metatype type metadata.
static Lazy<MetadataCache<MetatypeCacheEntry>> MetatypeTypes;
/// \brief Find the appropriate value witness table for the given type.
static const ValueWitnessTable *
getMetatypeValueWitnesses(const Metadata *instanceType) {
// When metatypes are accessed opaquely, they always have a "thick"
// representation.
return &getUnmanagedPointerPointerValueWitnesses();
}
/// \brief Fetch a uniqued metadata for a metatype type.
SWIFT_RUNTIME_EXPORT
extern "C" const MetatypeMetadata *
swift::swift_getMetatypeMetadata(const Metadata *instanceMetadata) {
// Search the cache.
const size_t numGenericArgs = 1;
const void *args[] = { instanceMetadata };
auto &Types = MetatypeTypes.get();
auto entry = Types.findOrAdd(args, numGenericArgs,
[&]() -> MetatypeCacheEntry* {
// Create a new entry for the cache.
auto entry = MetatypeCacheEntry::allocate(Types.getAllocator(),
args, numGenericArgs, 0);
auto metadata = entry->getData();
metadata->setKind(MetadataKind::Metatype);
metadata->ValueWitnesses = getMetatypeValueWitnesses(instanceMetadata);
metadata->InstanceType = instanceMetadata;
return entry;
});
return entry->getData();
}
/*** Existential Metatypes *************************************************/
namespace {
class ExistentialMetatypeCacheEntry :
public CacheEntry<ExistentialMetatypeCacheEntry> {
FullMetadata<ExistentialMetatypeMetadata> Metadata;
public:
static const char *getName() { return "ExistentialMetatypeCache"; }
ExistentialMetatypeCacheEntry(size_t numArguments) {}
static constexpr size_t getNumArguments() {
return 1;
}
FullMetadata<ExistentialMetatypeMetadata> *getData() {
return &Metadata;
}
const FullMetadata<ExistentialMetatypeMetadata> *getData() const {
return &Metadata;
}
};
}
struct ExistentialMetatypeState {
MetadataCache<ExistentialMetatypeCacheEntry> Types;
llvm::DenseMap<unsigned, const ExtraInhabitantsValueWitnessTable*>
ValueWitnessTables;
};
/// The uniquing structure for existential metatype type metadata.
static Lazy<ExistentialMetatypeState> ExistentialMetatypes;
static const ExtraInhabitantsValueWitnessTable
ExistentialMetatypeValueWitnesses_1 =
ValueWitnessTableForBox<ExistentialMetatypeBox<1>>::table;
static const ExtraInhabitantsValueWitnessTable
ExistentialMetatypeValueWitnesses_2 =
ValueWitnessTableForBox<ExistentialMetatypeBox<2>>::table;
/// Instantiate a value witness table for an existential metatype
/// container with the given number of witness table pointers.
static const ExtraInhabitantsValueWitnessTable *
getExistentialMetatypeValueWitnesses(ExistentialMetatypeState &EM,
unsigned numWitnessTables) {
if (numWitnessTables == 0)
return &getUnmanagedPointerPointerValueWitnesses();
if (numWitnessTables == 1)
return &ExistentialMetatypeValueWitnesses_1;
if (numWitnessTables == 2)
return &ExistentialMetatypeValueWitnesses_2;
static_assert(3 * sizeof(void*) >= sizeof(ValueBuffer),
"not handling all possible inline-storage class existentials!");
auto found = EM.ValueWitnessTables.find(numWitnessTables);
if (found != EM.ValueWitnessTables.end())
return found->second;
using Box = NonFixedExistentialMetatypeBox;
using Witnesses = NonFixedValueWitnesses<Box, /*known allocated*/ true>;
auto *vwt = new ExtraInhabitantsValueWitnessTable;
#define STORE_VAR_EXISTENTIAL_METATYPE_WITNESS(WITNESS) \
vwt->WITNESS = Witnesses::WITNESS;
FOR_ALL_FUNCTION_VALUE_WITNESSES(STORE_VAR_EXISTENTIAL_METATYPE_WITNESS)
STORE_VAR_EXISTENTIAL_METATYPE_WITNESS(storeExtraInhabitant)
STORE_VAR_EXISTENTIAL_METATYPE_WITNESS(getExtraInhabitantIndex)
#undef STORE_VAR_EXISTENTIAL_METATYPE_WITNESS
vwt->size = Box::Container::getSize(numWitnessTables);
vwt->flags = ValueWitnessFlags()
.withAlignment(Box::Container::getAlignment(numWitnessTables))
.withPOD(true)
.withBitwiseTakable(true)
.withInlineStorage(false)
.withExtraInhabitants(true);
vwt->stride = Box::Container::getStride(numWitnessTables);
vwt->extraInhabitantFlags = ExtraInhabitantFlags()
.withNumExtraInhabitants(Witnesses::numExtraInhabitants);
EM.ValueWitnessTables.insert({numWitnessTables, vwt});
return vwt;
}
/// \brief Fetch a uniqued metadata for a metatype type.
SWIFT_RUNTIME_EXPORT
extern "C" const ExistentialMetatypeMetadata *
swift::swift_getExistentialMetatypeMetadata(const Metadata *instanceMetadata) {
// Search the cache.
const size_t numGenericArgs = 1;
const void *args[] = { instanceMetadata };
auto &EM = ExistentialMetatypes.get();
auto entry = EM.Types.findOrAdd(args, numGenericArgs,
[&]() -> ExistentialMetatypeCacheEntry* {
// Create a new entry for the cache.
auto entry =
ExistentialMetatypeCacheEntry::allocate(EM.Types.getAllocator(),
args, numGenericArgs, 0);
ExistentialTypeFlags flags;
if (instanceMetadata->getKind() == MetadataKind::Existential) {
flags = static_cast<const ExistentialTypeMetadata*>(instanceMetadata)->Flags;
} else {
assert(instanceMetadata->getKind()==MetadataKind::ExistentialMetatype);
flags = static_cast<const ExistentialMetatypeMetadata*>(instanceMetadata)->Flags;
}
auto metadata = entry->getData();
metadata->setKind(MetadataKind::ExistentialMetatype);
metadata->ValueWitnesses =
getExistentialMetatypeValueWitnesses(EM, flags.getNumWitnessTables());
metadata->InstanceType = instanceMetadata;
metadata->Flags = flags;
return entry;
});
return entry->getData();
}
/*** Existential types ********************************************************/
namespace {
class ExistentialCacheEntry : public CacheEntry<ExistentialCacheEntry> {
public:
FullMetadata<ExistentialTypeMetadata> Metadata;
static const char *getName() { return "ExistentialCache"; }
ExistentialCacheEntry(size_t numArguments) {
Metadata.Protocols.NumProtocols = numArguments;
}
size_t getNumArguments() const {
return Metadata.Protocols.NumProtocols;
}
FullMetadata<ExistentialTypeMetadata> *getData() {
return &Metadata;
}
const FullMetadata<ExistentialTypeMetadata> *getData() const {
return &Metadata;
}
};
}
struct ExistentialTypeState {
MetadataCache<ExistentialCacheEntry> Types;
llvm::DenseMap<unsigned, const ValueWitnessTable*> OpaqueValueWitnessTables;
llvm::DenseMap<unsigned, const ExtraInhabitantsValueWitnessTable*>
ClassValueWitnessTables;
};
/// The uniquing structure for existential type metadata.
static Lazy<ExistentialTypeState> Existentials;
static const ValueWitnessTable OpaqueExistentialValueWitnesses_0 =
ValueWitnessTableForBox<OpaqueExistentialBox<0>>::table;
static const ValueWitnessTable OpaqueExistentialValueWitnesses_1 =
ValueWitnessTableForBox<OpaqueExistentialBox<1>>::table;
/// Instantiate a value witness table for an opaque existential container with
/// the given number of witness table pointers.
static const ValueWitnessTable *
getOpaqueExistentialValueWitnesses(ExistentialTypeState &E,
unsigned numWitnessTables) {
// We pre-allocate a couple of important cases.
if (numWitnessTables == 0)
return &OpaqueExistentialValueWitnesses_0;
if (numWitnessTables == 1)
return &OpaqueExistentialValueWitnesses_1;
// FIXME: make thread-safe
auto found = E.OpaqueValueWitnessTables.find(numWitnessTables);
if (found != E.OpaqueValueWitnessTables.end())
return found->second;
using Box = NonFixedOpaqueExistentialBox;
using Witnesses = NonFixedValueWitnesses<Box, /*known allocated*/ true>;
static_assert(!Witnesses::hasExtraInhabitants, "no extra inhabitants");
auto *vwt = new ValueWitnessTable;
#define STORE_VAR_OPAQUE_EXISTENTIAL_WITNESS(WITNESS) \
vwt->WITNESS = Witnesses::WITNESS;
FOR_ALL_FUNCTION_VALUE_WITNESSES(STORE_VAR_OPAQUE_EXISTENTIAL_WITNESS)
#undef STORE_VAR_OPAQUE_EXISTENTIAL_WITNESS
vwt->size = Box::Container::getSize(numWitnessTables);
vwt->flags = ValueWitnessFlags()
.withAlignment(Box::Container::getAlignment(numWitnessTables))
.withPOD(false)
.withBitwiseTakable(false)
.withInlineStorage(false)
.withExtraInhabitants(false);
vwt->stride = Box::Container::getStride(numWitnessTables);
E.OpaqueValueWitnessTables.insert({numWitnessTables, vwt});
return vwt;
}
static const ExtraInhabitantsValueWitnessTable ClassExistentialValueWitnesses_1 =
ValueWitnessTableForBox<ClassExistentialBox<1>>::table;
static const ExtraInhabitantsValueWitnessTable ClassExistentialValueWitnesses_2 =
ValueWitnessTableForBox<ClassExistentialBox<2>>::table;
/// Instantiate a value witness table for a class-constrained existential
/// container with the given number of witness table pointers.
static const ExtraInhabitantsValueWitnessTable *
getClassExistentialValueWitnesses(ExistentialTypeState &E,
unsigned numWitnessTables) {
if (numWitnessTables == 0) {
#if SWIFT_OBJC_INTEROP
return &_TWVBO;
#else
return &_TWVBo;
#endif
}
if (numWitnessTables == 1)
return &ClassExistentialValueWitnesses_1;
if (numWitnessTables == 2)
return &ClassExistentialValueWitnesses_2;
static_assert(3 * sizeof(void*) >= sizeof(ValueBuffer),
"not handling all possible inline-storage class existentials!");
auto found = E.ClassValueWitnessTables.find(numWitnessTables);
if (found != E.ClassValueWitnessTables.end())
return found->second;
using Box = NonFixedClassExistentialBox;
using Witnesses = NonFixedValueWitnesses<Box, /*known allocated*/ true>;
auto *vwt = new ExtraInhabitantsValueWitnessTable;
#define STORE_VAR_CLASS_EXISTENTIAL_WITNESS(WITNESS) \
vwt->WITNESS = Witnesses::WITNESS;
FOR_ALL_FUNCTION_VALUE_WITNESSES(STORE_VAR_CLASS_EXISTENTIAL_WITNESS)
STORE_VAR_CLASS_EXISTENTIAL_WITNESS(storeExtraInhabitant)
STORE_VAR_CLASS_EXISTENTIAL_WITNESS(getExtraInhabitantIndex)
#undef STORE_VAR_CLASS_EXISTENTIAL_WITNESS
vwt->size = Box::Container::getSize(numWitnessTables);
vwt->flags = ValueWitnessFlags()
.withAlignment(Box::Container::getAlignment(numWitnessTables))
.withPOD(false)
.withBitwiseTakable(true)
.withInlineStorage(false)
.withExtraInhabitants(true);
vwt->stride = Box::Container::getStride(numWitnessTables);
vwt->extraInhabitantFlags = ExtraInhabitantFlags()
.withNumExtraInhabitants(Witnesses::numExtraInhabitants);
E.ClassValueWitnessTables.insert({numWitnessTables, vwt});
return vwt;
}
/// Get the value witness table for an existential type, first trying to use a
/// shared specialized table for common cases.
static const ValueWitnessTable *
getExistentialValueWitnesses(ExistentialTypeState &E,
ProtocolClassConstraint classConstraint,
unsigned numWitnessTables,
SpecialProtocol special) {
// Use special representation for special protocols.
switch (special) {
case SpecialProtocol::Error:
#if SWIFT_OBJC_INTEROP
// Error always has a single-ObjC-refcounted representation.
return &_TWVBO;
#else
// Without ObjC interop, Error is native-refcounted.
return &_TWVBo;
#endif
// Other existentials use standard representation.
case SpecialProtocol::AnyObject:
case SpecialProtocol::None:
break;
}
switch (classConstraint) {
case ProtocolClassConstraint::Class:
return getClassExistentialValueWitnesses(E, numWitnessTables);
case ProtocolClassConstraint::Any:
return getOpaqueExistentialValueWitnesses(E, numWitnessTables);
}
}
template<> ExistentialTypeRepresentation
ExistentialTypeMetadata::getRepresentation() const {
// Some existentials use special containers.
switch (Flags.getSpecialProtocol()) {
case SpecialProtocol::Error:
return ExistentialTypeRepresentation::Error;
case SpecialProtocol::AnyObject:
case SpecialProtocol::None:
break;
}
// The layout of standard containers depends on whether the existential is
// class-constrained.
if (isClassBounded())
return ExistentialTypeRepresentation::Class;
return ExistentialTypeRepresentation::Opaque;
}
template<> bool
ExistentialTypeMetadata::mayTakeValue(const OpaqueValue *container) const {
switch (getRepresentation()) {
// Owning a reference to a class existential is equivalent to owning a
// reference to the contained class instance.
case ExistentialTypeRepresentation::Class:
return true;
// Opaque existential containers uniquely own their contained value.
case ExistentialTypeRepresentation::Opaque:
return true;
// References to boxed existential containers may be shared.
case ExistentialTypeRepresentation::Error: {
// We can only take the value if the box is a bridged NSError, in which case
// owning a reference to the box is owning a reference to the NSError.
// TODO: Or if the box is uniquely referenced. We don't have intimate
// enough knowledge of CF refcounting to check for that dynamically yet.
const SwiftError *errorBox
= *reinterpret_cast<const SwiftError * const *>(container);
return errorBox->isPureNSError();
}
}
}
template<> void
ExistentialTypeMetadata::deinitExistentialContainer(OpaqueValue *container)
const {
switch (getRepresentation()) {
case ExistentialTypeRepresentation::Class:
// Nothing to clean up after taking the class reference.
break;
case ExistentialTypeRepresentation::Opaque: {
// Containing the value may require a side allocation, which we need
// to clean up.
auto opaque = reinterpret_cast<OpaqueExistentialContainer *>(container);
opaque->Type->vw_deallocateBuffer(&opaque->Buffer);
break;
}
case ExistentialTypeRepresentation::Error:
// TODO: If we were able to claim the value from a uniquely-owned
// existential box, we would want to deallocError here.
break;
}
}
template<> const OpaqueValue *
ExistentialTypeMetadata::projectValue(const OpaqueValue *container) const {
switch (getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto classContainer =
reinterpret_cast<const ClassExistentialContainer*>(container);
return reinterpret_cast<const OpaqueValue *>(&classContainer->Value);
}
case ExistentialTypeRepresentation::Opaque: {
auto opaqueContainer =
reinterpret_cast<const OpaqueExistentialContainer*>(container);
return opaqueContainer->Type->vw_projectBuffer(
const_cast<ValueBuffer*>(&opaqueContainer->Buffer));
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *errorBox
= *reinterpret_cast<const SwiftError * const *>(container);
// If the error is a bridged NSError, then the "box" is in fact itself
// the value.
if (errorBox->isPureNSError())
return container;
return errorBox->getValue();
}
}
}
template<> const Metadata *
ExistentialTypeMetadata::getDynamicType(const OpaqueValue *container) const {
switch (getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto classContainer =
reinterpret_cast<const ClassExistentialContainer*>(container);
void *obj = classContainer->Value;
return swift_getObjectType(reinterpret_cast<HeapObject*>(obj));
}
case ExistentialTypeRepresentation::Opaque: {
auto opaqueContainer =
reinterpret_cast<const OpaqueExistentialContainer*>(container);
return opaqueContainer->Type;
}
case ExistentialTypeRepresentation::Error: {
const SwiftError *errorBox
= *reinterpret_cast<const SwiftError * const *>(container);
return errorBox->getType();
}
}
}
template<> const WitnessTable *
ExistentialTypeMetadata::getWitnessTable(const OpaqueValue *container,
unsigned i) const {
assert(i < Flags.getNumWitnessTables());
// The layout of the container depends on whether it's class-constrained
// or a special protocol.
const WitnessTable * const *witnessTables;
switch (getRepresentation()) {
case ExistentialTypeRepresentation::Class: {
auto classContainer =
reinterpret_cast<const ClassExistentialContainer*>(container);
witnessTables = classContainer->getWitnessTables();
break;
}
case ExistentialTypeRepresentation::Opaque: {
auto opaqueContainer =
reinterpret_cast<const OpaqueExistentialContainer*>(container);
witnessTables = opaqueContainer->getWitnessTables();
break;
}
case ExistentialTypeRepresentation::Error: {
// Only one witness table we should be able to return, which is the
// Error.
assert(i == 0 && "only one witness table in an Error box");
const SwiftError *errorBox
= *reinterpret_cast<const SwiftError * const *>(container);
return errorBox->getErrorConformance();
}
}
// The return type here describes extra structure for the protocol
// witness table for some reason. We should probably have a nominal
// type for these, just for type safety reasons.
return witnessTables[i];
}
/// \brief Fetch a uniqued metadata for an existential type. The array
/// referenced by \c protocols will be sorted in-place.
SWIFT_RT_ENTRY_VISIBILITY
const ExistentialTypeMetadata *
swift::swift_getExistentialTypeMetadata(size_t numProtocols,
const ProtocolDescriptor **protocols)
SWIFT_CC(RegisterPreservingCC_IMPL) {
// Sort the protocol set.
std::sort(protocols, protocols + numProtocols);
// Calculate the class constraint and number of witness tables for the
// protocol set.
unsigned numWitnessTables = 0;
ProtocolClassConstraint classConstraint = ProtocolClassConstraint::Any;
for (auto p : make_range(protocols, protocols + numProtocols)) {
if (p->Flags.needsWitnessTable()) {
++numWitnessTables;
}
if (p->Flags.getClassConstraint() == ProtocolClassConstraint::Class)
classConstraint = ProtocolClassConstraint::Class;
}
// Search the cache.
auto protocolArgs = reinterpret_cast<const void * const *>(protocols);
auto &E = Existentials.get();
auto entry = E.Types.findOrAdd(protocolArgs, numProtocols,
[&]() -> ExistentialCacheEntry* {
// Create a new entry for the cache.
auto entry = ExistentialCacheEntry::allocate(E.Types.getAllocator(),
protocolArgs, numProtocols,
sizeof(const ProtocolDescriptor *) * numProtocols);
auto metadata = entry->getData();
// Get the special protocol kind for an uncomposed protocol existential.
// Protocol compositions are currently never special.
auto special = SpecialProtocol::None;
if (numProtocols == 1)
special = protocols[0]->Flags.getSpecialProtocol();
metadata->setKind(MetadataKind::Existential);
metadata->ValueWitnesses = getExistentialValueWitnesses(E,
classConstraint,
numWitnessTables,
special);
metadata->Flags = ExistentialTypeFlags()
.withNumWitnessTables(numWitnessTables)
.withClassConstraint(classConstraint)
.withSpecialProtocol(special);
metadata->Protocols.NumProtocols = numProtocols;
for (size_t i = 0; i < numProtocols; ++i)
metadata->Protocols[i] = protocols[i];
return entry;
});
return entry->getData();
}
/// \brief Perform a copy-assignment from one existential container to another.
/// Both containers must be of the same existential type representable with no
/// witness tables.
OpaqueValue *swift::swift_assignExistentialWithCopy0(OpaqueValue *dest,
const OpaqueValue *src,
const Metadata *type) {
using Witnesses = ValueWitnesses<OpaqueExistentialBox<0>>;
return Witnesses::assignWithCopy(dest, const_cast<OpaqueValue*>(src), type);
}
/// \brief Perform a copy-assignment from one existential container to another.
/// Both containers must be of the same existential type representable with one
/// witness table.
OpaqueValue *swift::swift_assignExistentialWithCopy1(OpaqueValue *dest,
const OpaqueValue *src,
const Metadata *type) {
using Witnesses = ValueWitnesses<OpaqueExistentialBox<1>>;
return Witnesses::assignWithCopy(dest, const_cast<OpaqueValue*>(src), type);
}
/// \brief Perform a copy-assignment from one existential container to another.
/// Both containers must be of the same existential type representable with the
/// same number of witness tables.
OpaqueValue *swift::swift_assignExistentialWithCopy(OpaqueValue *dest,
const OpaqueValue *src,
const Metadata *type) {
assert(!type->getValueWitnesses()->isValueInline());
using Witnesses = NonFixedValueWitnesses<NonFixedOpaqueExistentialBox,
/*known allocated*/ true>;
return Witnesses::assignWithCopy(dest, const_cast<OpaqueValue*>(src), type);
}
/*** Foreign types *********************************************************/
namespace {
/// A string whose data is globally-allocated.
struct GlobalString {
StringRef Data;
/*implicit*/ GlobalString(StringRef data) : Data(data) {}
};
}
template <>
struct llvm::DenseMapInfo<GlobalString> {
static GlobalString getEmptyKey() {
return StringRef((const char*) 0, 0);
}
static GlobalString getTombstoneKey() {
return StringRef((const char*) 1, 0);
}
static unsigned getHashValue(const GlobalString &val) {
// llvm::hash_value(StringRef) is, unfortunately, defined out of
// line in a library we otherwise would not need to link against.
return llvm::hash_combine_range(val.Data.begin(), val.Data.end());
}
static bool isEqual(const GlobalString &lhs, const GlobalString &rhs) {
return lhs.Data == rhs.Data;
}
};
// We use a DenseMap over what are essentially StringRefs instead of a
// StringMap because we don't need to actually copy the string.
namespace {
struct ForeignTypeState {
Mutex Lock;
ConditionVariable InitializationWaiters;
llvm::DenseMap<GlobalString, const ForeignTypeMetadata *> Types;
};
}
static Lazy<ForeignTypeState> ForeignTypes;
const ForeignTypeMetadata *
swift::swift_getForeignTypeMetadata(ForeignTypeMetadata *nonUnique) {
// Fast path: check the invasive cache.
if (auto unique = nonUnique->getCachedUniqueMetadata()) {
return unique;
}
// Okay, check the global map.
auto &foreignTypes = ForeignTypes.get();
GlobalString key(nonUnique->getName());
bool hasInit = nonUnique->hasInitializationFunction();
const ForeignTypeMetadata *uniqueMetadata;
bool inserted;
// A helper function to find the current entry for the key using the
// saved iterator if it's still valid. This should only be called
// while the lock is held.
decltype(foreignTypes.Types.begin()) savedIterator;
size_t savedSize;
auto getCurrentEntry = [&]() -> const ForeignTypeMetadata *& {
// The iterator may have been invalidated if the size of the map
// has changed since the last lookup.
if (foreignTypes.Types.size() != savedSize) {
savedSize = foreignTypes.Types.size();
savedIterator = foreignTypes.Types.find(key);
assert(savedIterator != foreignTypes.Types.end() &&
"entries cannot be removed from foreign types metadata map");
}
return savedIterator->second;
};
{
ScopedLock guard(foreignTypes.Lock);
// Try to create an entry in the map. The initial value of the entry
// is our copy of the metadata unless it has an initialization function,
// in which case we have to insert null as a placeholder to tell others
// to wait while we call the initializer.
auto valueToInsert = (hasInit ? nullptr : nonUnique);
auto insertResult = foreignTypes.Types.insert({key, valueToInsert});
inserted = insertResult.second;
savedIterator = insertResult.first;
savedSize = foreignTypes.Types.size();
uniqueMetadata = savedIterator->second;
// If we created the entry, then the unique metadata is our copy.
if (inserted) {
uniqueMetadata = nonUnique;
// If we didn't create the entry, but it's null, then we have to wait
// until it becomes non-null.
} else {
while (uniqueMetadata == nullptr) {
foreignTypes.Lock.wait(foreignTypes.InitializationWaiters);
uniqueMetadata = getCurrentEntry();
}
}
}
// If we inserted the entry and there's an initialization function,
// call it. This has to be done with the lock dropped.
if (inserted && hasInit) {
nonUnique->getInitializationFunction()(nonUnique);
// Update the cache entry:
// - Reacquire the lock.
ScopedLock guard(foreignTypes.Lock);
// - Change the entry.
auto &entry = getCurrentEntry();
assert(entry == nullptr);
entry = nonUnique;
// - Notify waiters.
foreignTypes.InitializationWaiters.notifyAll();
}
// Remember the unique result in the invasive cache. We don't want
// to do this until after the initialization completes; otherwise,
// it will be possible for code to fast-path through this function
// too soon.
nonUnique->setCachedUniqueMetadata(uniqueMetadata);
return uniqueMetadata;
}
/*** Other metadata routines ***********************************************/
template<> const GenericMetadata *
Metadata::getGenericPattern() const {
auto &ntd = getNominalTypeDescriptor();
if (!ntd)
return nullptr;
return ntd->getGenericMetadataPattern();
}
template<> const ClassMetadata *
Metadata::getClassObject() const {
switch (getKind()) {
case MetadataKind::Class: {
// Native Swift class metadata is also the class object.
return static_cast<const ClassMetadata *>(this);
}
case MetadataKind::ObjCClassWrapper: {
// Objective-C class objects are referenced by their Swift metadata wrapper.
auto wrapper = static_cast<const ObjCClassWrapperMetadata *>(this);
return wrapper->Class;
}
// Other kinds of types don't have class objects.
case MetadataKind::Struct:
case MetadataKind::Enum:
case MetadataKind::Optional:
case MetadataKind::ForeignClass:
case MetadataKind::Opaque:
case MetadataKind::Tuple:
case MetadataKind::Function:
case MetadataKind::Existential:
case MetadataKind::ExistentialMetatype:
case MetadataKind::Metatype:
case MetadataKind::HeapLocalVariable:
case MetadataKind::HeapGenericLocalVariable:
case MetadataKind::ErrorObject:
return nullptr;
}
}
#ifndef NDEBUG
SWIFT_RUNTIME_EXPORT
extern "C"
void _swift_debug_verifyTypeLayoutAttribute(Metadata *type,
const void *runtimeValue,
const void *staticValue,
size_t size,
const char *description) {
auto presentValue = [&](const void *value) {
if (size < sizeof(long long)) {
long long intValue = 0;
memcpy(&intValue, value, size);
fprintf(stderr, "%lld (%#llx)\n ", intValue, intValue);
}
auto bytes = reinterpret_cast<const uint8_t *>(value);
for (unsigned i = 0; i < size; ++i) {
fprintf(stderr, "%02x ", bytes[i]);
}
fprintf(stderr, "\n");
};
if (memcmp(runtimeValue, staticValue, size) != 0) {
auto typeName = nameForMetadata(type);
fprintf(stderr, "*** Type verification of %s %s failed ***\n",
typeName.c_str(), description);
fprintf(stderr, " runtime value: ");
presentValue(runtimeValue);
fprintf(stderr, " compiler value: ");
presentValue(staticValue);
}
}
#endif
/*** Protocol witness tables *************************************************/
namespace {
class WitnessTableCacheEntry : public CacheEntry<WitnessTableCacheEntry> {
public:
static const char *getName() { return "WitnessTableCache"; }
WitnessTableCacheEntry(size_t numArguments) {
assert(numArguments == getNumArguments());
}
static constexpr size_t getNumArguments() {
return 1;
}
/// Advance the address point to the end of the private storage area.
WitnessTable *get(GenericWitnessTable *genericTable) const {
return reinterpret_cast<WitnessTable *>(
const_cast<void **>(getData<void *>()) +
genericTable->WitnessTablePrivateSizeInWords);
}
};
}
using GenericWitnessTableCache = MetadataCache<WitnessTableCacheEntry>;
using LazyGenericWitnessTableCache = Lazy<GenericWitnessTableCache>;
/// Fetch the cache for a generic witness-table structure.
static GenericWitnessTableCache &getCache(GenericWitnessTable *gen) {
// Keep this assert even if you change the representation above.
static_assert(sizeof(LazyGenericWitnessTableCache) <=
sizeof(GenericWitnessTable::PrivateData),
"metadata cache is larger than the allowed space");
auto lazyCache =
reinterpret_cast<LazyGenericWitnessTableCache*>(gen->PrivateData);
return lazyCache->get();
}
/// If there's no initializer, no private storage, and all requirements
/// are present, we don't have to instantiate anything; just return the
/// witness table template.
///
/// Most of the time IRGen should be able to determine this statically;
/// the one case is with resilient conformances, where the resilient
/// protocol has not yet changed in a way that's incompatible with the
/// conformance.
static bool doesNotRequireInstantiation(GenericWitnessTable *genericTable) {
if (genericTable->Instantiator.isNull() &&
genericTable->WitnessTablePrivateSizeInWords == 0 &&
(genericTable->Protocol.isNull() ||
genericTable->WitnessTableSizeInWords -
genericTable->Protocol->MinimumWitnessTableSizeInWords ==
genericTable->Protocol->DefaultWitnessTableSizeInWords)) {
return true;
}
return false;
}
/// Instantiate a brand new witness table for a resilient or generic
/// protocol conformance.
static WitnessTableCacheEntry *
allocateWitnessTable(GenericWitnessTable *genericTable,
MetadataAllocator &allocator,
const void *args[],
size_t numGenericArgs) {
// Number of bytes for any private storage used by the conformance itself.
size_t privateSize = genericTable->WitnessTablePrivateSizeInWords * sizeof(void *);
size_t minWitnessTableSize, expectedWitnessTableSize;
size_t actualWitnessTableSize = genericTable->WitnessTableSizeInWords * sizeof(void *);
auto protocol = genericTable->Protocol.get();
if (protocol != nullptr && protocol->Flags.isResilient()) {
// The protocol and conforming type are in different resilience domains.
// Allocate the witness table with the correct size, and fill in default
// requirements at the end as needed.
minWitnessTableSize = (protocol->MinimumWitnessTableSizeInWords *
sizeof(void *));
expectedWitnessTableSize = ((protocol->MinimumWitnessTableSizeInWords +
protocol->DefaultWitnessTableSizeInWords) *
sizeof(void *));
assert(actualWitnessTableSize >= minWitnessTableSize &&
actualWitnessTableSize <= expectedWitnessTableSize);
} else {
// The protocol and conforming type are in the same resilience domain.
// Trust that the witness table template already has the correct size.
minWitnessTableSize = expectedWitnessTableSize = actualWitnessTableSize;
}
// Create a new entry for the cache.
auto entry = WitnessTableCacheEntry::allocate(
allocator, args, numGenericArgs,
privateSize + expectedWitnessTableSize);
char *fullTable = entry->getData<char>();
// Zero out the private storage area.
memset(fullTable, 0, privateSize);
// Advance the address point; the private storage area is accessed via
// negative offsets.
auto *table = entry->get(genericTable);
// Fill in the provided part of the requirements from the pattern.
memcpy(table, (void * const *) &*genericTable->Pattern,
actualWitnessTableSize);
// If this is a resilient conformance, copy in the rest.
if (protocol != nullptr && protocol->Flags.isResilient()) {
memcpy((char *) table + actualWitnessTableSize,
(char *) protocol->getDefaultWitnesses() +
(actualWitnessTableSize - minWitnessTableSize),
expectedWitnessTableSize - actualWitnessTableSize);
}
return entry;
}
SWIFT_RT_ENTRY_VISIBILITY
extern "C" const WitnessTable *
swift::swift_getGenericWitnessTable(GenericWitnessTable *genericTable,
const Metadata *type,
void * const *instantiationArgs)
SWIFT_CC(RegisterPreservingCC_IMPL) {
if (doesNotRequireInstantiation(genericTable)) {
return genericTable->Pattern;
}
// If type is not nullptr, the witness table depends on the substituted
// conforming type, so use that are the key.
constexpr const size_t numGenericArgs = 1;
const void *args[] = { type };
auto &cache = getCache(genericTable);
auto entry = cache.findOrAdd(args, numGenericArgs,
[&]() -> WitnessTableCacheEntry* {
// Allocate the witness table and fill it in.
auto entry = allocateWitnessTable(genericTable,
cache.getAllocator(),
args, numGenericArgs);
// Call the instantiation function to initialize
// dependent associated type metadata.
if (!genericTable->Instantiator.isNull()) {
genericTable->Instantiator(entry->get(genericTable),
type, instantiationArgs);
}
return entry;
});
return entry->get(genericTable);
}
uint64_t swift::RelativeDirectPointerNullPtr = 0;
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