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Replace nominal type descriptors with a hierarchy of context descriptors.

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This new format more efficiently represents existing information, while
more accurately encoding important information about nested generic
contexts with same-type and layout constraints that need to be evaluated
at runtime. It's also designed with an eye to forward- and
backward-compatible expansion for ABI stability with future Swift
versions.
This commit is contained in:
Joe Groff
2017-12-12 09:57:36 -08:00
parent 9ac1dc80b0
commit a7a3b17597
58 changed files with 3418 additions and 1291 deletions
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72
stdlib/public/runtime/Metadata.cpp
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@@ -1026,16 +1026,53 @@ swift::swift_getTupleTypeMetadata3(const Metadata *elt0, const Metadata *elt1,
/***************************************************************************/
/*** Nominal type descriptors **********************************************/
/***************************************************************************/
template<>
bool NominalTypeDescriptor::isEqual(const NominalTypeDescriptor *other) const {
bool swift::equalContexts(const ContextDescriptor *a,
const ContextDescriptor *b)
{
// Fast path: pointer equality.
if (this == other) return true;
if (a == b) return true;
// If both nominal type descriptors are known to be unique, we're done.
if (this->isUnique() && other->isUnique()) return false;
// If either context is null, we're done.
if (a == nullptr || b == nullptr)
return false;
// Compare the mangled names.
return strcmp(this->Name.get(), other->Name.get()) == 0;
// If either descriptor is known to be unique, we're done.
if (a->isUnique() || b->isUnique()) return false;
// Do the kinds match?
if (a->getKind() != b->getKind()) return false;
// Do the parents match?
if (!equalContexts(a->Parent.get(), b->Parent.get()))
return false;
// Compare kind-specific details.
switch (auto kind = a->getKind()) {
case ContextDescriptorKind::Module: {
// Modules with the same name are equivalent.
auto moduleA = cast<ModuleContextDescriptor>(a);
auto moduleB = cast<ModuleContextDescriptor>(b);
return strcmp(moduleA->Name.get(), moduleB->Name.get()) == 0;
}
case ContextDescriptorKind::Extension:
case ContextDescriptorKind::Anonymous:
// These context kinds are always unique.
return false;
default:
// Types in the same context with the same name are equivalent.
if (kind >= ContextDescriptorKind::Type_First
&& kind <= ContextDescriptorKind::Type_Last) {
auto typeA = cast<TypeContextDescriptor>(a);
auto typeB = cast<TypeContextDescriptor>(b);
return strcmp(typeA->Name.get(), typeB->Name.get()) == 0;
}
// Otherwise, this runtime doesn't know anything about this context kind.
// Conservatively return false.
return false;
}
}
/***************************************************************************/
@@ -1418,7 +1455,7 @@ static void _swift_initGenericClassObjCName(ClassMetadata *theClass) {
static void _swift_initializeSuperclass(ClassMetadata *theClass) {
#if SWIFT_OBJC_INTEROP
// If the class is generic, we need to give it a name for Objective-C.
if (theClass->getDescription()->GenericParams.isGeneric())
if (theClass->getDescription()->isGeneric())
_swift_initGenericClassObjCName(theClass);
#endif
@@ -1428,11 +1465,9 @@ static void _swift_initializeSuperclass(ClassMetadata *theClass) {
// to the class metadata.
{
const auto *description = theClass->getDescription();
auto &genericParams = description->GenericParams;
auto *classWords = reinterpret_cast<void **>(theClass);
if (genericParams.Flags.hasVTable()) {
if (description->hasVTable()) {
auto *vtable = description->getVTableDescriptor();
for (unsigned i = 0, e = vtable->VTableSize; i < e; ++i) {
classWords[vtable->getVTableOffset(theClass) + i]
@@ -1454,17 +1489,18 @@ static void _swift_initializeSuperclass(ClassMetadata *theClass) {
auto *superWords = reinterpret_cast<const uintptr_t *>(theSuperclass);
while (ancestor && ancestor->isTypeMetadata()) {
const auto *description = ancestor->getDescription();
auto &genericParams = description->GenericParams;
// Copy the generic requirements.
if (genericParams.hasGenericRequirements()) {
memcpy(classWords + genericParams.getOffset(ancestor),
superWords + genericParams.getOffset(ancestor),
genericParams.NumGenericRequirements * sizeof(uintptr_t));
if (description->isGeneric()
&& description->getGenericContextHeader().hasArguments()) {
memcpy(classWords + description->getGenericArgumentOffset(ancestor),
superWords + description->getGenericArgumentOffset(ancestor),
description->getGenericContextHeader().getNumArguments() *
sizeof(uintptr_t));
}
// Copy the vtable entries.
if (genericParams.Flags.hasVTable()) {
if (description->hasVTable()) {
auto *vtable = description->getVTableDescriptor();
memcpy(classWords + vtable->getVTableOffset(ancestor),
superWords + vtable->getVTableOffset(ancestor),
@@ -2852,8 +2888,6 @@ const WitnessTable *swift::swift_getGenericWitnessTable(
return entry->get(genericTable);
}
uint64_t swift::RelativeDirectPointerNullPtr = 0;
/***************************************************************************/
/*** Allocator implementation **********************************************/
/***************************************************************************/