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5e98accde42ae4fd858cba1caebfb9b6521779cb
swift-mirror/lib/IRGen/GenClass.cpp
Adrian Prantl 5e98accde4 Debug info: Rename createFunction -> emitFunction for consistency. 
Swift SVN r7054
2013-08-08 21:20:07 +00:00

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//===--- GenClass.cpp - Swift IR Generation For 'class' Types -----------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 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
//
//===----------------------------------------------------------------------===//
//
// This file implements IR generation for class types.
//
//===----------------------------------------------------------------------===//
#include "GenClass.h"
#include "swift/ABI/Class.h"
#include "swift/AST/Attr.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/Decl.h"
#include "swift/AST/Module.h"
#include "swift/AST/Pattern.h"
#include "swift/AST/PrettyStackTrace.h"
#include "swift/AST/TypeMemberVisitor.h"
#include "swift/AST/Types.h"
#include "swift/SIL/SILModule.h"
#include "swift/SIL/SILType.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/CallSite.h"
#include "Explosion.h"
#include "GenFunc.h"
#include "GenMeta.h"
#include "GenObjC.h"
#include "GenProto.h"
#include "GenType.h"
#include "IRGenDebugInfo.h"
#include "IRGenFunction.h"
#include "IRGenModule.h"
#include "GenHeap.h"
#include "HeapTypeInfo.h"
using namespace swift;
using namespace irgen;
/// Does the given class have a Swift refcount?
bool irgen::hasSwiftRefcount(IRGenModule &IGM, ClassDecl *theClass) {
// Scan to the root class.
while (theClass->hasSuperclass()) {
theClass = theClass->getSuperclass()->getClassOrBoundGenericClass();
assert(theClass && "base type of class not a class?");
}
// If the root class is implemented in swift, then we have a swift
// refcount.
return hasKnownSwiftImplementation(IGM, theClass);
}
/// Different policies for accessing a physical field.
enum class FieldAccess : uint8_t {
/// Instance variable offsets are constant.
ConstantDirect,
/// Instance variable offsets must be loaded from "direct offset"
/// global variables.
NonConstantDirect,
/// Instance variable offsets are kept in fields in metadata, but
/// the offsets of those fields within the metadata are constant.
ConstantIndirect,
/// Instance variable offsets are kept in fields in metadata, and
/// the offsets of those fields within the metadata must be loaded
/// from "indirect offset" global variables.
NonConstantIndirect
};
namespace {
class FieldEntry {
llvm::PointerIntPair<VarDecl*, 2, FieldAccess> VarAndAccess;
public:
FieldEntry(VarDecl *var, FieldAccess access)
: VarAndAccess(var, access) {}
VarDecl *getVar() const {
return VarAndAccess.getPointer();
}
FieldAccess getAccess() const {
return VarAndAccess.getInt();
}
};
/// Layout information for class types.
class ClassTypeInfo : public HeapTypeInfo<ClassTypeInfo> {
ClassDecl *TheClass;
mutable StructLayout *Layout;
/// Can we use swift reference-counting, or do we have to use
/// objc_retain/release?
const bool HasSwiftRefcount;
public:
ClassTypeInfo(llvm::PointerType *irType, Size size, Alignment align,
ClassDecl *D, bool hasSwiftRefcount)
: HeapTypeInfo(irType, size, align), TheClass(D), Layout(nullptr),
HasSwiftRefcount(hasSwiftRefcount) {}
bool hasSwiftRefcount() const {
return HasSwiftRefcount;
}
~ClassTypeInfo() {
delete Layout;
}
ClassDecl *getClass() const { return TheClass; }
const StructLayout &getLayout(IRGenModule &IGM) const;
Alignment getHeapAlignment(IRGenModule &IGM) const {
return getLayout(IGM).getAlignment();
}
ArrayRef<ElementLayout> getElements(IRGenModule &IGM) const {
return getLayout(IGM).getElements();
}
};
/// A class for computing properties of the instance-variable layout
/// of a class. TODO: cache the results!
class LayoutClass {
IRGenModule &IGM;
ClassDecl *Root;
SmallVector<FieldEntry, 8> Fields;
bool IsMetadataResilient = false;
bool IsObjectResilient = false;
bool IsObjectGenericallyArranged = false;
ResilienceScope Resilience;
public:
LayoutClass(IRGenModule &IGM, ResilienceScope resilience,
ClassDecl *theClass, CanType type)
: IGM(IGM), Resilience(resilience) {
layout(theClass, type);
}
/// The root class for purposes of metaclass objects.
ClassDecl *getRootClassForMetaclass() const {
// If the formal root class is imported from Objective-C, then
// we should use that. For a class that's really implemented in
// Objective-C, this is obviously right. For a class that's
// really implemented in Swift, but that we're importing via an
// Objective-C interface, this would be wrong --- except such a
// class can never be a formal root class, because a Swift class
// without a formal superclass will actually be parented by
// SwiftObject (or maybe eventually something else like it),
// which will be visible in the Objective-C type system.
if (Root->hasClangNode()) return Root;
return IGM.getSwiftRootClass();
}
const FieldEntry &getFieldEntry(VarDecl *field) const {
for (auto &entry : Fields)
if (entry.getVar() == field)
return entry;
llvm_unreachable("no entry for field!");
}
private:
void layout(ClassDecl *theClass, CanType type) {
// TODO: use the full type information to potentially make
// generic layouts concrete.
// First, collect information about the superclass.
if (theClass->hasSuperclass()) {
CanType superclassType = theClass->getSuperclass()->getCanonicalType();
auto superclass = type->getClassOrBoundGenericClass();
assert(superclass);
layout(superclass, superclassType);
} else {
Root = theClass;
}
// If the class is resilient, then it may have fields we can't
// see, and all subsequent fields are *at least* resilient ---
// and if the class is generic, then it may have
// dependently-sized fields, and we'll be in the worst case.
bool isClassResilient = IGM.isResilient(theClass, Resilience);
if (isClassResilient) {
IsMetadataResilient = true;
IsObjectResilient = true;
if (theClass->getGenericParamsOfContext() != nullptr) {
IsObjectGenericallyArranged = true;
}
}
// Okay, make entries for all the physical fields we know about.
for (auto member : theClass->getMembers()) {
auto var = dyn_cast<VarDecl>(member);
if (!var) continue;
// Skip properties that we have to access logically.
assert(isClassResilient || !IGM.isResilient(var, Resilience));
if (var->isProperty())
continue;
Fields.push_back(FieldEntry(var, getCurFieldAccess()));
// Adjust based on the type of this field.
// FIXME: this algorithm is assuming that fields are laid out
// in declaration order.
adjustAccessAfterField(var);
}
}
FieldAccess getCurFieldAccess() const {
if (IsObjectGenericallyArranged) {
if (IsMetadataResilient) {
return FieldAccess::NonConstantIndirect;
} else {
return FieldAccess::ConstantIndirect;
}
} else {
if (IsObjectResilient) {
return FieldAccess::NonConstantDirect;
} else {
return FieldAccess::ConstantDirect;
}
}
}
void adjustAccessAfterField(VarDecl *var) {
if (var->isProperty()) return;
CanType type = var->getType()->getCanonicalType();
switch (IGM.classifyTypeSize(type, ResilienceScope::Local)) {
case ObjectSize::Fixed:
return;
case ObjectSize::Resilient:
IsObjectResilient = true;
return;
case ObjectSize::Dependent:
IsObjectResilient = IsObjectGenericallyArranged = true;
return;
}
llvm_unreachable("bad ObjectSize value");
}
};
} // end anonymous namespace.
/// Return the index of the given field within the class.
static unsigned getFieldIndex(ClassDecl *base, VarDecl *target) {
// FIXME: This is algorithmically terrible.
unsigned index = 0;
for (Decl *member : base->getMembers()) {
if (member == target) return index;
if (auto var = dyn_cast<VarDecl>(member))
if (!var->isProperty())
++index;
}
llvm_unreachable("didn't find field in type!");
}
namespace {
class ClassLayoutBuilder : public StructLayoutBuilder {
SmallVector<ElementLayout, 8> LastElements;
public:
ClassLayoutBuilder(IRGenModule &IGM, ClassDecl *theClass)
: StructLayoutBuilder(IGM) {
// Start by adding a heap header.
addHeapHeader();
// Next, add the fields for the given class.
addFieldsForClass(theClass);
}
/// Return the element layouts for the most-derived class.
ArrayRef<ElementLayout> getLastElements() const {
return LastElements;
}
private:
void addFieldsForClass(ClassDecl *theClass) {
if (theClass->hasSuperclass()) {
// TODO: apply substitutions when computing base-class layouts!
auto superclass
= theClass->getSuperclass()->getClassOrBoundGenericClass();
assert(superclass);
// Recur.
addFieldsForClass(superclass);
// Forget about the fields from the superclass.
LastElements.clear();
}
// Collect fields from this class and add them to the layout as a chunk.
addDirectFieldsFromClass(theClass);
}
void addDirectFieldsFromClass(ClassDecl *theClass) {
assert(LastElements.empty());
for (Decl *member : theClass->getMembers()) {
VarDecl *var = dyn_cast<VarDecl>(member);
if (!var || var->isProperty()) continue;
auto &eltType = IGM.getFragileTypeInfo(var->getType());
// FIXME: Type-parameter-dependent field layout isn't implemented yet.
if (!eltType.isFixedSize()) {
IGM.unimplemented(var->getLoc(), "non-fixed class layout");
exit(1);
}
LastElements.push_back(ElementLayout::getIncomplete(eltType));
}
// Add those fields to the builder.
addFields(LastElements, LayoutStrategy::Universal);
}
};
}
const StructLayout &ClassTypeInfo::getLayout(IRGenModule &IGM) const {
// Return the cached layout if available.
if (Layout) return *Layout;
// Add the heap header.
ClassLayoutBuilder builder(IGM, getClass());
// Set the body of the class type.
auto classPtrTy = cast<llvm::PointerType>(getStorageType());
auto classTy = cast<llvm::StructType>(classPtrTy->getElementType());
builder.setAsBodyOfStruct(classTy);
// Record the layout.
Layout = new StructLayout(builder, classTy, builder.getLastElements());
return *Layout;
}
/// Cast the base to i8*, apply the given inbounds offset (in bytes,
/// as a size_t), and cast to a pointer to the given type.
llvm::Value *IRGenFunction::emitByteOffsetGEP(llvm::Value *base,
llvm::Value *offset,
llvm::Type *objectType,
const llvm::Twine &name) {
assert(offset->getType() == IGM.SizeTy);
auto addr = Builder.CreateBitCast(base, IGM.Int8PtrTy);
addr = Builder.CreateInBoundsGEP(addr, offset);
return Builder.CreateBitCast(addr, objectType->getPointerTo(), name);
}
/// Cast the base to i8*, apply the given inbounds offset (in bytes,
/// as a size_t), and create an address in the given type.
Address IRGenFunction::emitByteOffsetGEP(llvm::Value *base,
llvm::Value *offset,
const TypeInfo &type,
const llvm::Twine &name) {
auto addr = emitByteOffsetGEP(base, offset, type.getStorageType(), name);
return type.getAddressForPointer(addr);
}
/// Emit a field l-value by applying the given offset to the given base.
static OwnedAddress emitAddressAtOffset(IRGenFunction &IGF,
llvm::Value *base,
llvm::Value *offset,
VarDecl *field) {
auto &fieldTI = IGF.getFragileTypeInfo(field->getType());
auto addr = IGF.emitByteOffsetGEP(base, offset, fieldTI,
base->getName() + "." + field->getName().str());
return OwnedAddress(addr, base);
}
OwnedAddress irgen::projectPhysicalClassMemberAddress(IRGenFunction &IGF,
llvm::Value *base,
SILType baseType,
VarDecl *field) {
auto &baseClassTI = IGF.getFragileTypeInfo(baseType).as<ClassTypeInfo>();
ClassDecl *baseClass = baseType.getClassOrBoundGenericClass();
LayoutClass layout(IGF.IGM, ResilienceScope::Local, baseClass,
baseType.getSwiftRValueType());
auto &entry = layout.getFieldEntry(field);
switch (entry.getAccess()) {
case FieldAccess::ConstantDirect: {
// FIXME: This field index computation is an ugly hack.
unsigned fieldIndex = getFieldIndex(baseClass, field);
Address baseAddr(base, baseClassTI.getHeapAlignment(IGF.IGM));
auto &element = baseClassTI.getElements(IGF.IGM)[fieldIndex];
Address memberAddr = element.project(IGF, baseAddr,
/*non fixed offsets*/ nullptr);
return OwnedAddress(memberAddr, base);
}
case FieldAccess::NonConstantDirect: {
Address offsetA = IGF.IGM.getAddrOfFieldOffset(field, /*indirect*/ false);
auto offset = IGF.Builder.CreateLoad(offsetA, "offset");
return emitAddressAtOffset(IGF, base, offset, field);
}
case FieldAccess::ConstantIndirect: {
auto metadata = emitHeapMetadataRefForHeapObject(IGF, base, baseType);
auto offset = emitClassFieldOffset(IGF, baseClass, field, metadata);
return emitAddressAtOffset(IGF, base, offset, field);
}
case FieldAccess::NonConstantIndirect: {
auto metadata = emitHeapMetadataRefForHeapObject(IGF, base, baseType);
Address indirectOffsetA =
IGF.IGM.getAddrOfFieldOffset(field, /*indirect*/ true);
auto indirectOffset =
IGF.Builder.CreateLoad(indirectOffsetA, "indirect-offset");
auto offsetA =
IGF.emitByteOffsetGEP(metadata, indirectOffset, IGF.IGM.SizeTy);
auto offset =
IGF.Builder.CreateLoad(Address(offsetA, IGF.IGM.getPointerAlignment()));
return emitAddressAtOffset(IGF, base, offset, field);
}
}
llvm_unreachable("bad field-access strategy");
}
/// Emit the deallocating destructor for a class in terms of its destroying
/// destructor.
void irgen::emitDeallocatingDestructor(IRGenModule &IGM,
ClassDecl *theClass,
llvm::Function *deallocator,
llvm::Function *destroyer) {
IRGenFunction IGF(IGM, ExplosionKind::Minimal, deallocator);
if (IGM.DebugInfo)
IGM.DebugInfo->emitArtificialFunction(IGF, deallocator);
Type thisType = theClass->getDeclaredTypeInContext();
const ClassTypeInfo &info =
IGM.getFragileTypeInfo(thisType).as<ClassTypeInfo>();
llvm::Value *obj = deallocator->getArgumentList().begin();
obj = IGF.Builder.CreateBitCast(obj, info.getStorageType());
// The destroying destructor returns the pointer back as a %swift.refcounted,
// so we don't need to keep it live across the call.
obj = IGF.Builder.CreateCall(destroyer, obj);
// Emit the deallocation.
llvm::Value *size = info.getLayout(IGM).emitSize(IGF);
emitDeallocateHeapObject(IGF, obj, size);
IGF.Builder.CreateRetVoid();
}
/// Emit an allocation of a class.
llvm::Value *irgen::emitClassAllocation(IRGenFunction &IGF, SILType thisType) {
// FIXME: Long-term, we clearly need a specialized runtime entry point.
auto &classTI = IGF.IGM.getFragileTypeInfo(thisType).as<ClassTypeInfo>();
auto &layout = classTI.getLayout(IGF.IGM);
llvm::Value *metadata = emitClassHeapMetadataRef(IGF, thisType);
llvm::Value *size = layout.emitSize(IGF);
llvm::Value *alignMask = layout.emitAlignMask(IGF);
llvm::Value *val = IGF.emitAllocObjectCall(metadata, size, alignMask,
"reference.new");
llvm::Type *destType = layout.getType()->getPointerTo();
return IGF.Builder.CreateBitCast(val, destType);
}
/// emitClassDecl - Emit all the declarations associated with this class type.
void IRGenModule::emitClassDecl(ClassDecl *D) {
PrettyStackTraceDecl prettyStackTrace("emitting class metadata for", D);
auto &classTI = Types.getFragileTypeInfo(D).as<ClassTypeInfo>();
auto &layout = classTI.getLayout(*this);
// Emit the class metadata.
emitClassMetadata(*this, D, layout);
// Emit the deallocating destructor.
llvm::Function *deallocator
= getAddrOfDestructor(D, DestructorKind::Deallocating);
llvm::Function *destroyer
= getAddrOfDestructor(D, DestructorKind::Destroying);
emitDeallocatingDestructor(*this, D, deallocator, destroyer);
// FIXME: This is mostly copy-paste from emitExtension;
// figure out how to refactor!
for (Decl *member : D->getMembers()) {
switch (member->getKind()) {
case DeclKind::Import:
case DeclKind::TopLevelCode:
case DeclKind::Protocol:
case DeclKind::UnionElement:
case DeclKind::Extension:
case DeclKind::InfixOperator:
case DeclKind::PrefixOperator:
case DeclKind::PostfixOperator:
llvm_unreachable("decl not allowed in class!");
// We can have meaningful initializers for variables, but
// we can't handle them yet. For the moment, just ignore them.
case DeclKind::PatternBinding:
continue;
case DeclKind::Subscript:
// Getter/setter will be handled separately.
continue;
case DeclKind::TypeAlias:
continue;
case DeclKind::Union:
emitUnionDecl(cast<UnionDecl>(member));
continue;
case DeclKind::Struct:
emitStructDecl(cast<StructDecl>(member));
continue;
case DeclKind::Class:
emitClassDecl(cast<ClassDecl>(member));
continue;
case DeclKind::Var:
if (cast<VarDecl>(member)->isProperty())
// Getter/setter will be handled separately.
continue;
// FIXME: Will need an implementation here for resilience
continue;
case DeclKind::Func:
emitLocalDecls(cast<FuncDecl>(member));
continue;
case DeclKind::Constructor:
emitLocalDecls(cast<ConstructorDecl>(member));
continue;
case DeclKind::Destructor:
emitLocalDecls(cast<DestructorDecl>(member));
continue;
}
llvm_unreachable("bad extension member kind");
}
}
namespace {
enum ForMetaClass_t : bool {
ForClass = false,
ForMetaClass = true
};
typedef std::pair<ClassDecl*, Module*> CategoryNameKey;
/// Used to provide unique names to ObjC categories generated by Swift
/// extensions. The first category for a class in a module gets the module's
/// name as its key, e.g., NSObject (MySwiftModule). Another extension of the
/// same class in the same module gets a category name with a number appended,
/// e.g., NSObject (MySwiftModule1).
llvm::DenseMap<CategoryNameKey, unsigned> CategoryCounts;
/// A class for building class data (in Objective-C terms, class_ro_t) or
/// category data (category_t).
class ClassDataBuilder : public ClassMemberVisitor<ClassDataBuilder> {
IRGenModule &IGM;
ClassDecl *TheClass;
ExtensionDecl *TheExtension;
const LayoutClass *Layout;
const StructLayout *FieldLayout;
bool HasNonTrivialDestructor = false;
bool HasNonTrivialConstructor = false;
llvm::SmallString<16> CategoryName;
SmallVector<llvm::Constant*, 8> Ivars;
SmallVector<llvm::Constant*, 16> InstanceMethods;
SmallVector<llvm::Constant*, 16> ClassMethods;
SmallVector<llvm::Constant*, 4> Protocols;
SmallVector<llvm::Constant*, 8> Properties;
llvm::Constant *Name = nullptr;
unsigned NextFieldIndex = 0;
public:
ClassDataBuilder(IRGenModule &IGM, ClassDecl *theClass,
const LayoutClass &layout,
const StructLayout &fieldLayout)
: IGM(IGM), TheClass(theClass), TheExtension(nullptr),
Layout(&layout), FieldLayout(&fieldLayout) {
visitMembers(TheClass);
}
ClassDataBuilder(IRGenModule &IGM, ClassDecl *theClass,
ExtensionDecl *theExtension)
: IGM(IGM), TheClass(theClass), TheExtension(theExtension),
Layout(nullptr), FieldLayout(nullptr)
{
buildCategoryName(CategoryName);
for (Decl *member : TheExtension->getMembers())
visit(member);
// ObjC protocol conformances may need to pull method descriptors for
// definitions from other contexts into the category.
for (unsigned i = 0, size = TheExtension->getProtocols().size();
i < size; ++i)
visitObjCConformance(TheExtension->getProtocols()[i],
TheExtension->getConformances()[i]);
}
void visitObjCConformance(ProtocolDecl *protocol,
ProtocolConformance *conformance) {
assert(TheExtension &&
"should only consider objc conformances for extensions");
if (protocol->isObjC())
for (auto &mapping : conformance->getWitnesses()) {
ValueDecl *vd = mapping.second.Decl;
if (vd->getDeclContext() != TheExtension)
visit(vd);
}
for (auto &inherited : conformance->getInheritedConformances())
visitObjCConformance(inherited.first, inherited.second);
}
/// Build the metaclass stub object.
void buildMetaclassStub() {
assert(Layout && "can't build a metaclass from a category");
// The isa is the metaclass pointer for the root class.
auto rootClass = Layout->getRootClassForMetaclass();
auto rootPtr = IGM.getAddrOfMetaclassObject(rootClass);
// The superclass of the metaclass is the metaclass of the
// superclass. Note that for metaclass stubs, we can always
// ignore parent contexts and generic arguments.
//
// If this class has no formal superclass, then its actual
// superclass is SwiftObject, i.e. the root class.
llvm::Constant *superPtr;
if (TheClass->hasSuperclass()) {
auto base = TheClass->getSuperclass()->getClassOrBoundGenericClass();
superPtr = IGM.getAddrOfMetaclassObject(base);
} else {
superPtr = rootPtr;
}
auto dataPtr = emitROData(ForMetaClass);
dataPtr = llvm::ConstantExpr::getPtrToInt(dataPtr, IGM.IntPtrTy);
llvm::Constant *fields[] = {
rootPtr,
superPtr,
IGM.getObjCEmptyCachePtr(),
IGM.getObjCEmptyVTablePtr(),
dataPtr
};
auto init = llvm::ConstantStruct::get(IGM.ObjCClassStructTy,
makeArrayRef(fields));
auto metaclass =
cast<llvm::GlobalVariable>(IGM.getAddrOfMetaclassObject(TheClass));
metaclass->setInitializer(init);
}
private:
void buildCategoryName(llvm::SmallVectorImpl<char> &s) {
llvm::raw_svector_ostream os(s);
// Find the module the extension is declared in.
DeclContext *ModuleDC = TheExtension;
do {
ModuleDC = ModuleDC->getParent();
} while (ModuleDC && !isa<Module>(ModuleDC));
Module *TheModule = cast<Module>(ModuleDC);
os << TheModule->Name;
unsigned categoryCount = CategoryCounts[{TheClass, TheModule}]++;
if (categoryCount > 0)
os << categoryCount;
os.flush();
}
public:
llvm::Constant *emitCategory() {
assert(TheExtension && "can't emit category data for a class");
SmallVector<llvm::Constant*, 11> fields;
// struct category_t {
// char const *name;
fields.push_back(IGM.getAddrOfGlobalString(CategoryName));
// const class_t *theClass;
if (TheClass->hasClangNode())
fields.push_back(IGM.getAddrOfObjCClass(TheClass));
else {
llvm::Constant *metadata = tryEmitConstantHeapMetadataRef(IGM,
TheClass->getDeclaredTypeOfContext()->getCanonicalType());
assert(metadata &&
"extended objc class doesn't have constant metadata?");
fields.push_back(metadata);
}
// const method_list_t *instanceMethods;
fields.push_back(buildInstanceMethodList());
// const method_list_t *classMethods;
fields.push_back(buildClassMethodList());
// const protocol_list_t *baseProtocols;
fields.push_back(buildProtocolList());
// const property_list_t *properties;
fields.push_back(buildPropertyList());
// };
return buildGlobalVariable(fields, "_CATEGORY_");
}
llvm::Constant *emitROData(ForMetaClass_t forMeta) {
assert(Layout && FieldLayout && "can't emit rodata for a category");
SmallVector<llvm::Constant*, 11> fields;
// struct _class_ro_t {
// uint32_t flags;
fields.push_back(buildFlags(forMeta));
// uint32_t instanceStart;
// uint32_t instanceSize;
// The runtime requires that the ivar offsets be initialized to
// a valid layout of the ivars of this class, bounded by these
// two values. If the instanceSize of the superclass equals the
// stored instanceStart of the subclass, the ivar offsets
// will not be changed.
Size instanceStart = Size(0);
Size instanceSize = Size(0);
if (!forMeta) {
instanceSize = FieldLayout->getSize();
if (FieldLayout->getElements().empty()) {
instanceStart = instanceSize;
} else {
// FIXME: assumes layout is always sequential!
instanceStart = FieldLayout->getElements()[0].getByteOffset();
}
}
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty,
instanceStart.getValue()));
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty,
instanceSize.getValue()));
// uint32_t reserved; // only when building for 64bit targets
if (IGM.getPointerAlignment().getValue() > 4) {
assert(IGM.getPointerAlignment().getValue() == 8);
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty, 0));
}
// const uint8_t *ivarLayout;
// GC/ARC layout. TODO.
fields.push_back(null());
// const char *name;
// It is correct to use the same name for both class and metaclass.
fields.push_back(buildName());
// const method_list_t *baseMethods;
fields.push_back(forMeta ? buildClassMethodList()
: buildInstanceMethodList());
// const protocol_list_t *baseProtocols;
// Apparently, this list is the same in the class and the metaclass.
fields.push_back(buildProtocolList());
// const ivar_list_t *ivars;
fields.push_back(forMeta ? null() : buildIvarList());
// const uint8_t *weakIvarLayout;
// More GC/ARC layout. TODO.
fields.push_back(null());
// const property_list_t *baseProperties;
fields.push_back(forMeta ? null() : buildPropertyList());
// };
auto dataSuffix = forMeta ? "_METACLASS_DATA_" : "_DATA_";
return buildGlobalVariable(fields, dataSuffix);
}
private:
llvm::Constant *buildFlags(ForMetaClass_t forMeta) {
ClassFlags flags = ClassFlags::CompiledByARC;
// Mark metaclasses as appropriate.
if (forMeta) {
flags |= ClassFlags::Meta;
// Non-metaclasses need us to record things whether primitive
// construction/destructor is trivial.
} else if (HasNonTrivialDestructor || HasNonTrivialConstructor) {
flags |= ClassFlags::HasCXXStructors;
if (!HasNonTrivialConstructor)
flags |= ClassFlags::HasCXXDestructorOnly;
}
// FIXME: set ClassFlags::Hidden when appropriate
return llvm::ConstantInt::get(IGM.Int32Ty, uint32_t(flags));
}
llvm::Constant *buildName() {
if (Name) return Name;
// If the class is being exported as an Objective-C class, we
// should export it under its formal name.
if (TheClass->isObjC()) {
Name = IGM.getAddrOfGlobalString(TheClass->getName().str());
return Name;
}
// Otherwise, we need to mangle the type.
auto type = TheClass->getDeclaredType()->getCanonicalType();
SmallVector<char, 128> buffer;
Name = IGM.getAddrOfGlobalString(IGM.mangleType(type, buffer));
return Name;
}
llvm::Constant *null() {
return llvm::ConstantPointerNull::get(IGM.Int8PtrTy);
}
/*** Methods ***********************************************************/
public:
/// Methods need to be collected into the appropriate methods list.
void visitFuncDecl(FuncDecl *method) {
if (!requiresObjCMethodDescriptor(method)) return;
llvm::Constant *entry = emitObjCMethodDescriptor(IGM, method);
if (!method->isStatic()) {
InstanceMethods.push_back(entry);
} else {
ClassMethods.push_back(entry);
}
}
private:
llvm::Constant *buildClassMethodList() {
return buildMethodList(ClassMethods, TheExtension
? "_CATEGORY_CLASS_METHODS_"
: "_CLASS_METHODS_");
}
llvm::Constant *buildInstanceMethodList() {
return buildMethodList(InstanceMethods, TheExtension
? "_CATEGORY_INSTANCE_METHODS_"
: "_INSTANCE_METHODS_");
}
/// struct method_list_t {
/// uint32_t entsize; // runtime uses low bits for its own purposes
/// uint32_t count;
/// method_t list[count];
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildMethodList(ArrayRef<llvm::Constant*> methods,
StringRef name) {
return buildOptionalList(methods, 3 * IGM.getPointerSize(), name);
}
/*** Protocols *********************************************************/
/// typedef uintptr_t protocol_ref_t; // protocol_t*, but unremapped
llvm::Constant *buildProtocolRef(ProtocolDecl *protocol) {
// FIXME
return llvm::ConstantPointerNull::get(IGM.Int8PtrTy);
}
/// struct protocol_list_t {
/// uintptr_t count;
/// protocol_ref_t[count];
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildProtocolList() {
return buildOptionalList(Protocols, Size(0), TheExtension
? "_CATEGORY_PROTOCOLS_"
: "_PROTOCOLS_");
}
/*** Ivars *************************************************************/
public:
/// Variables might be properties or ivars.
void visitVarDecl(VarDecl *var) {
if (var->isProperty()) {
visitProperty(var);
} else {
visitIvar(var);
}
}
private:
/// Ivars need to be collected in the ivars list, and they also
/// affect flags.
void visitIvar(VarDecl *var) {
// FIXME: how to handle ivar extensions in categories?
if (!Layout && !FieldLayout)
return;
Ivars.push_back(buildIvar(var));
if (!IGM.isPOD(var->getType()->getCanonicalType(),
ResilienceScope::Local)) {
HasNonTrivialDestructor = true;
}
// Build property accessors for the ivar if necessary.
visitProperty(var);
}
/// struct ivar_t {
/// uintptr_t *offset;
/// const char *name;
/// const char *type;
/// uint32_t alignment;
/// uint32_t size;
/// };
llvm::Constant *buildIvar(VarDecl *ivar) {
assert(Layout && FieldLayout && "can't build ivar for category");
// FIXME: this is not always the right thing to do!
auto &elt = FieldLayout->getElements()[NextFieldIndex++];
auto offsetAddr = IGM.getAddrOfFieldOffset(ivar, /*indirect*/ false);
auto offsetVar = cast<llvm::GlobalVariable>(offsetAddr.getAddress());
offsetVar->setConstant(false);
auto offsetVal =
llvm::ConstantInt::get(IGM.IntPtrTy, elt.getByteOffset().getValue());
offsetVar->setInitializer(offsetVal);
// TODO: clang puts this in __TEXT,__objc_methname,cstring_literals
auto name = IGM.getAddrOfGlobalString(ivar->getName().str());
// TODO: clang puts this in __TEXT,__objc_methtype,cstring_literals
auto typeEncode = llvm::ConstantPointerNull::get(IGM.Int8PtrTy);
auto &ivarTI = IGM.getFragileTypeInfo(ivar->getType());
Size size;
Alignment alignment;
if (auto fixedTI = dyn_cast<FixedTypeInfo>(&ivarTI)) {
size = fixedTI->getFixedSize();
alignment = fixedTI->getFixedAlignment();
} else {
// FIXME: set something up to fill these in at runtime!
size = Size(0);
alignment = Alignment(0);
}
// If the size is larger than we can represent in 32-bits,
// complain about the unimplementable ivar.
if (uint32_t(size.getValue()) != size.getValue()) {
IGM.error(ivar->getLoc(),
"ivar size (" + Twine(size.getValue()) +
" bytes) overflows Objective-C ivar layout");
size = Size(0);
}
llvm::Constant *fields[] = {
offsetVar,
name,
typeEncode,
llvm::ConstantInt::get(IGM.Int32Ty, size.getValue()),
llvm::ConstantInt::get(IGM.Int32Ty, alignment.getValue())
};
return llvm::ConstantStruct::getAnon(IGM.getLLVMContext(), fields);
}
/// struct ivar_list_t {
/// uint32_t entsize;
/// uint32_t count;
/// ivar_t list[count];
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildIvarList() {
Size eltSize = 3 * IGM.getPointerSize() + Size(8);
return buildOptionalList(Ivars, eltSize, "_IVARS_");
}
/*** Properties ********************************************************/
/// Properties need to be collected in the properties list.
void visitProperty(VarDecl *var) {
if (requiresObjCPropertyDescriptor(var)) {
if (llvm::Constant *prop = buildProperty(var))
Properties.push_back(prop);
auto getter_setter = emitObjCPropertyMethodDescriptors(IGM, var);
InstanceMethods.push_back(getter_setter.first);
if (getter_setter.second)
InstanceMethods.push_back(getter_setter.second);
}
}
/// Build the property attribute string for a property decl.
void buildPropertyAttributes(VarDecl *prop,
llvm::SmallVectorImpl<char> &out,
ClassDecl *theClass) {
llvm::raw_svector_ostream outs(out);
// Emit the type encoding.
// FIXME: Only correct for class types.
outs << "T@";
// FIXME: Assume 'NSObject' really means 'id'.
if (theClass->getName() != prop->getASTContext().getIdentifier("NSObject"))
outs << '"' << theClass->getName().str() << '"';
// FIXME: Emit attributes for (nonatomic, strong) if the property has a
// setter, or (nonatomic, readonly) if the property has only a getter.
// Are these attributes always appropriate?
outs << (prop->isSettable()
? ",&,N" // strong, nonatomic
: ",R,N"); // readonly, nonatomic
// Emit the selector name for the getter. Clang only appears to emit the
// setter name if the property has an explicit setter= attribute.
outs << ",V" << prop->getName();
outs.flush();
}
/// struct property_t {
/// const char *name;
/// const char *attributes;
/// };
llvm::Constant *buildProperty(VarDecl *prop) {
// FIXME: For now we only emit properties of ObjC class type.
ClassDecl *theClass
= IGM.SILMod->Types.getLoweredBridgedType(prop->getType(),
AbstractCC::ObjCMethod)
->getClassOrBoundGenericClass();
if (!theClass)
return nullptr;
if (!theClass->isObjC())
return nullptr;
llvm::SmallString<16> propertyAttributes;
buildPropertyAttributes(prop, propertyAttributes, theClass);
llvm::Constant *fields[] = {
IGM.getAddrOfGlobalString(prop->getName().str()),
IGM.getAddrOfGlobalString(propertyAttributes)
};
return llvm::ConstantStruct::getAnon(IGM.getLLVMContext(), fields);
}
/// struct property_list_t {
/// uint32_t entsize;
/// uint32_t count;
/// property_t list[count];
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildPropertyList() {
Size eltSize = 2 * IGM.getPointerSize();
return buildOptionalList(Properties, eltSize, TheExtension
? "_CATEGORY_PROPERTIES_"
: "_PROPERTIES_");
}
/*** General ***********************************************************/
/// Build a list structure from the given array of objects.
/// If the array is empty, use null. The assumption is that every
/// initializer has the same size.
///
/// \param optionalEltSize - if non-zero, a size which needs
/// to be placed in the list header
llvm::Constant *buildOptionalList(ArrayRef<llvm::Constant*> objects,
Size optionalEltSize,
StringRef nameBase) {
if (objects.empty())
return llvm::ConstantPointerNull::get(IGM.Int8PtrTy);
SmallVector<llvm::Constant*, 3> fields;
// In all of the foo_list_t structs, either:
// - there's a 32-bit entry size and a 32-bit count or
// - there's no entry size and a uintptr_t count.
if (!optionalEltSize.isZero()) {
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty,
optionalEltSize.getValue()));
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty, objects.size()));
} else {
fields.push_back(llvm::ConstantInt::get(IGM.IntPtrTy, objects.size()));
}
auto arrayTy =
llvm::ArrayType::get(objects[0]->getType(), objects.size());
fields.push_back(llvm::ConstantArray::get(arrayTy, objects));
return buildGlobalVariable(fields, nameBase);
}
/// Build a private global variable as a structure containing the
/// given fields.
llvm::Constant *buildGlobalVariable(ArrayRef<llvm::Constant*> fields,
StringRef nameBase) {
auto init = llvm::ConstantStruct::getAnon(IGM.getLLVMContext(), fields);
auto var = new llvm::GlobalVariable(IGM.Module, init->getType(),
/*constant*/ true,
llvm::GlobalVariable::PrivateLinkage,
init,
Twine(nameBase)
+ TheClass->getName().str()
+ (TheExtension
? Twine("_$_") + CategoryName.str()
: Twine()));
var->setAlignment(IGM.getPointerAlignment().getValue());
var->setSection("__DATA, __objc_const");
return var;
}
public:
/// Member types don't get any representation.
/// Maybe this should change for reflection purposes?
void visitTypeDecl(TypeDecl *type) {}
/// Pattern-bindings don't require anything special as long as
/// these initializations are performed in the constructor, not
/// .cxx_construct.
void visitPatternBindingDecl(PatternBindingDecl *binding) {}
/// Subscripts should probably be collected in extended metadata.
void visitSubscriptDecl(SubscriptDecl *subscript) {
// TODO
}
/// Constructors should probably be collected in extended metadata.
void visitConstructorDecl(ConstructorDecl *ctor) {
// TODO
}
/// The destructor doesn't really require any special
/// representation here.
void visitDestructorDecl(DestructorDecl *dtor) {}
};
}
/// Emit the private data (RO-data) associated with a class.
llvm::Constant *irgen::emitClassPrivateData(IRGenModule &IGM,
ClassDecl *cls) {
assert(IGM.ObjCInterop && "emitting RO-data outside of interop mode");
CanType type = cls->getDeclaredTypeInContext()->getCanonicalType();
auto &classTI = IGM.getFragileTypeInfo(type).as<ClassTypeInfo>();
auto &fieldLayout = classTI.getLayout(IGM);
LayoutClass layout(IGM, ResilienceScope::Universal, cls, type);
ClassDataBuilder builder(IGM, cls, layout, fieldLayout);
// First, build the metaclass object.
builder.buildMetaclassStub();
// Then build the class RO-data.
return builder.emitROData(ForClass);
}
/// Emit the metadata for an ObjC category.
llvm::Constant *irgen::emitCategoryData(IRGenModule &IGM,
ExtensionDecl *ext) {
assert(IGM.ObjCInterop && "emitting RO-data outside of interop mode");
ClassDecl *cls = ext->getDeclaredTypeInContext()
->getClassOrBoundGenericClass();
assert(cls && "generating category metadata for a non-class extension");
ClassDataBuilder builder(IGM, cls, ext);
return builder.emitCategory();
}
const TypeInfo *TypeConverter::convertClassType(ClassDecl *D) {
llvm::StructType *ST = IGM.createNominalType(D);
llvm::PointerType *irType = ST->getPointerTo();
bool hasSwiftRefcount = ::hasSwiftRefcount(IGM, D);
return new ClassTypeInfo(irType, IGM.getPointerSize(),
IGM.getPointerAlignment(),
D, hasSwiftRefcount);
}
/// Lazily declare the Swift root-class, SwiftObject.
ClassDecl *IRGenModule::getSwiftRootClass() {
if (SwiftRootClass) return SwiftRootClass;
auto name = Context.getIdentifier("SwiftObject");
// Make a really fake-looking class.
SwiftRootClass = new (Context) ClassDecl(SourceLoc(), name, SourceLoc(),
MutableArrayRef<TypeLoc>(),
/*generics*/ nullptr,
Context.TheBuiltinModule);
SwiftRootClass->getMutableAttrs().ObjC = true;
SwiftRootClass->setIsObjC(true);
return SwiftRootClass;
}
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