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SILGenConstructor.cpp
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//===--- SILGenConstructor.cpp - SILGen for constructors ------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#include "ArgumentSource.h"
#include "Conversion.h"
#include "ExecutorBreadcrumb.h"
#include "Initialization.h"
#include "LValue.h"
#include "RValue.h"
#include "SILGenFunction.h"
#include "SILGenFunctionBuilder.h"
#include "Scope.h"
#include "swift/AST/ASTMangler.h"
#include "swift/AST/ForeignErrorConvention.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/PropertyWrappers.h"
#include "swift/Basic/Defer.h"
#include "swift/Basic/Generators.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/SILInstruction.h"
#include "swift/SIL/SILUndef.h"
#include "swift/SIL/TypeLowering.h"
#include <map>
using namespace swift;
using namespace Lowering;
namespace {
class LoweredParamsInContextGenerator {
SILGenFunction &SGF;
ArrayRefGenerator<ArrayRef<SILParameterInfo>> loweredParams;
public:
LoweredParamsInContextGenerator(SILGenFunction &SGF)
: SGF(SGF),
loweredParams(SGF.F.getLoweredFunctionType()->getParameters()) {
}
using reference = SILType;
/// Get the original (unsubstituted into context) lowered parameter
/// type information.
SILParameterInfo getOrigInfo() const {
return loweredParams.get();
}
SILType get() const {
return SGF.getSILTypeInContext(loweredParams.get(),
SGF.F.getLoweredFunctionType());
}
SILType claimNext() {
auto param = get();
advance();
return param;
}
bool isFinished() const {
return loweredParams.isFinished();
}
void advance() {
loweredParams.advance();
}
void finish() {
loweredParams.finish();
}
};
} // end anonymous namespace
static ManagedValue emitManagedParameter(SILGenFunction &SGF,
SILValue value, bool isOwned) {
if (isOwned) {
return SGF.emitManagedRValueWithCleanup(value);
} else {
return ManagedValue::forBorrowedRValue(value);
}
}
static SILValue emitConstructorMetatypeArg(SILGenFunction &SGF,
ValueDecl *decl) {
// In addition to the declared arguments, the constructor implicitly takes
// the metatype as its first argument, like a static function.
auto metatypeTy = MetatypeType::get(
decl->getDeclContext()->getSelfInterfaceType());
auto *DC = decl->getInnermostDeclContext();
auto &ctx = SGF.getASTContext();
auto VD =
new (ctx) ParamDecl(SourceLoc(), SourceLoc(),
ctx.getIdentifier("$metatype"), SourceLoc(),
ctx.getIdentifier("$metatype"), DC);
VD->setSpecifier(ParamSpecifier::Default);
VD->setInterfaceType(metatypeTy);
return SGF.F.begin()->createFunctionArgument(
SGF.getLoweredTypeForFunctionArgument(DC->mapTypeIntoContext(metatypeTy)),
VD);
}
// FIXME: Consolidate this with SILGenProlog
static RValue emitImplicitValueConstructorArg(SILGenFunction &SGF,
SILLocation loc,
CanType interfaceType,
DeclContext *DC,
LoweredParamsInContextGenerator &loweredParamTypes,
Initialization *argInit = nullptr) {
auto type = DC->mapTypeIntoContext(interfaceType)->getCanonicalType();
// Restructure tuple arguments.
if (auto tupleIfaceTy = dyn_cast<TupleType>(interfaceType)) {
// If we don't have a context to emit into, but we have a tuple
// that contains pack expansions, create a temporary.
TemporaryInitializationPtr tempInit;
if (!argInit && tupleIfaceTy.containsPackExpansionType()) {
tempInit = SGF.emitTemporary(loc, SGF.getTypeLowering(type));
argInit = tempInit.get();
}
// Split the initialization into element initializations if we have
// one. We should never have to deal with an initialization that
// can't be split here.
assert(!argInit || argInit->canSplitIntoTupleElements());
SmallVector<InitializationPtr> initsBuf;
MutableArrayRef<InitializationPtr> eltInits;
if (argInit) {
eltInits = argInit->splitIntoTupleElements(SGF, loc, type, initsBuf);
assert(eltInits.size() == tupleIfaceTy->getNumElements());
}
RValue tuple(type);
for (auto eltIndex : range(tupleIfaceTy->getNumElements())) {
auto eltIfaceType = tupleIfaceTy.getElementType(eltIndex);
auto eltInit = (argInit ? eltInits[eltIndex].get() : nullptr);
RValue element = emitImplicitValueConstructorArg(SGF, loc, eltIfaceType,
DC, loweredParamTypes,
eltInit);
if (argInit) {
assert(element.isInContext());
} else {
tuple.addElement(std::move(element));
}
}
// If we created a temporary initializer above, finish it and claim
// the managed buffer.
if (tempInit) {
tempInit->finishInitialization(SGF);
auto tupleValue = tempInit->getManagedAddress();
if (tupleValue.getType().isLoadable(SGF.F)) {
tupleValue = SGF.B.createLoadTake(loc, tupleValue);
}
return RValue(SGF, loc, type, tupleValue);
// Otherwise, if we have an emitInto, return forInContext().
} else if (argInit) {
argInit->finishInitialization(SGF);
return RValue::forInContext();
}
return tuple;
}
auto &AC = SGF.getASTContext();
auto VD = new (AC) ParamDecl(SourceLoc(), SourceLoc(),
AC.getIdentifier("$implicit_value"),
SourceLoc(),
AC.getIdentifier("$implicit_value"),
DC);
VD->setSpecifier(ParamSpecifier::Default);
VD->setInterfaceType(interfaceType);
auto origParamInfo = loweredParamTypes.getOrigInfo();
auto argType = loweredParamTypes.claimNext();
auto *arg = SGF.F.begin()->createFunctionArgument(argType, VD);
bool argIsConsumed = origParamInfo.isConsumed();
// If the lowered parameter is a pack expansion, copy/move the pack
// into the initialization, which we assume is there.
if (auto packTy = argType.getAs<SILPackType>()) {
assert(isa<PackExpansionType>(interfaceType));
assert(packTy->getNumElements() == 1);
assert(argInit);
assert(argInit->canPerformPackExpansionInitialization());
auto expansionTy = packTy->getSILElementType(0);
auto openedEnvAndEltTy =
SGF.createOpenedElementValueEnvironment(expansionTy);
auto openedEnv = openedEnvAndEltTy.first;
auto eltTy = openedEnvAndEltTy.second;
auto formalPackType = CanPackType::get(SGF.getASTContext(), {type});
SGF.emitDynamicPackLoop(loc, formalPackType, /*component*/0, openedEnv,
[&](SILValue indexWithinComponent,
SILValue packExpansionIndex,
SILValue packIndex) {
argInit->performPackExpansionInitialization(SGF, loc,
indexWithinComponent,
[&](Initialization *eltInit) {
auto eltAddr =
SGF.B.createPackElementGet(loc, packIndex, arg, eltTy);
ManagedValue eltMV = emitManagedParameter(SGF, eltAddr, argIsConsumed);
eltMV = SGF.B.createLoadIfLoadable(loc, eltMV);
eltInit->copyOrInitValueInto(SGF, loc, eltMV, argIsConsumed);
eltInit->finishInitialization(SGF);
});
});
argInit->finishInitialization(SGF);
return RValue::forInContext();
}
ManagedValue mvArg = emitManagedParameter(SGF, arg, argIsConsumed);
// This can happen if the value is resilient in the calling convention
// but not resilient locally.
if (argType.isAddress()) {
mvArg = SGF.B.createLoadIfLoadable(loc, mvArg);
}
if (argInit) {
argInit->copyOrInitValueInto(SGF, loc, mvArg, argIsConsumed);
argInit->finishInitialization(SGF);
return RValue::forInContext();
}
return RValue(SGF, loc, type, mvArg);
}
/// If the field has a property wrapper for which we will need to call the
/// wrapper type's init(wrappedValue:, ...), call the function that performs
/// that initialization and return the result. Otherwise, return \c arg.
static RValue maybeEmitPropertyWrapperInitFromValue(
SILGenFunction &SGF,
SILLocation loc,
VarDecl *field,
SubstitutionMap subs,
RValue &&arg) {
auto originalProperty = field->getOriginalWrappedProperty();
if (!originalProperty ||
!originalProperty->isPropertyMemberwiseInitializedWithWrappedType())
return std::move(arg);
auto initInfo = originalProperty->getPropertyWrapperInitializerInfo();
if (!initInfo.hasInitFromWrappedValue())
return std::move(arg);
return SGF.emitApplyOfPropertyWrapperBackingInitializer(loc, originalProperty,
subs, std::move(arg));
}
static void
emitApplyOfInitAccessor(SILGenFunction &SGF, SILLocation loc,
AccessorDecl *accessor, SILValue selfValue,
Type selfIfaceTy, SILType selfTy,
RValue &&initialValue) {
SmallVector<SILValue> arguments;
auto emitFieldReference = [&](VarDecl *field, bool forInit = false) {
auto fieldTy =
selfTy.getFieldType(field, SGF.SGM.M, SGF.getTypeExpansionContext());
return SGF.B.createStructElementAddr(loc, selfValue, field,
fieldTy.getAddressType());
};
// First, let's emit all of the indirect results.
for (auto *property : accessor->getInitializedProperties()) {
arguments.push_back(emitFieldReference(property, /*forInit=*/true));
}
// `initialValue`
std::move(initialValue).forwardAll(SGF, arguments);
// And finally, all of the properties in `accesses` list which are
// `inout` arguments.
for (auto *property : accessor->getAccessedProperties()) {
arguments.push_back(emitFieldReference(property));
}
// The `self` metatype.
auto metatypeTy = MetatypeType::get(accessor->mapTypeIntoContext(selfIfaceTy));
arguments.push_back(SGF.B.createMetatype(loc, SGF.getLoweredType(metatypeTy)));
SubstitutionMap subs;
if (auto *env =
accessor->getDeclContext()->getGenericEnvironmentOfContext()) {
subs = env->getForwardingSubstitutionMap();
}
SILValue accessorRef =
SGF.emitGlobalFunctionRef(loc, SGF.getAccessorDeclRef(accessor));
(void)SGF.B.createApply(loc, accessorRef, subs, arguments, ApplyOptions());
}
static SubstitutionMap getSubstitutionsForPropertyInitializer(
DeclContext *dc,
NominalTypeDecl *nominal) {
// We want a substitution list written in terms of the generic
// signature of the type, with replacement archetypes from the
// constructor's context (which might be in an extension of
// the type, which adds additional generic requirements).
if (auto *genericEnv = dc->getGenericEnvironmentOfContext()) {
// Generate a set of substitutions for the initialization function,
// whose generic signature is that of the type context, and whose
// replacement types are the archetypes of the initializer itself.
return SubstitutionMap::get(
nominal->getGenericSignatureOfContext(),
QuerySubstitutionMap{genericEnv->getForwardingSubstitutionMap()},
LookUpConformanceInModule(dc->getParentModule()));
}
return SubstitutionMap();
}
static void emitImplicitValueConstructor(SILGenFunction &SGF,
ConstructorDecl *ctor) {
RegularLocation Loc(ctor);
Loc.markAutoGenerated();
if (ctor->requiresUnavailableDeclABICompatibilityStubs())
SGF.emitApplyOfUnavailableCodeReached();
AssertingManualScope functionLevelScope(SGF.Cleanups,
CleanupLocation(Loc));
auto loweredFunctionTy = SGF.F.getLoweredFunctionType();
// FIXME: Handle 'self' along with the other arguments.
assert(loweredFunctionTy->getNumResults() == 1);
auto selfResultInfo = loweredFunctionTy->getResults()[0];
auto *paramList = ctor->getParameters();
auto *selfDecl = ctor->getImplicitSelfDecl();
auto selfIfaceTy = selfDecl->getInterfaceType();
SILType selfTy = SGF.getSILTypeInContext(selfResultInfo, loweredFunctionTy);
auto *decl = selfTy.getStructOrBoundGenericStruct();
assert(decl && "not a struct?!");
std::multimap<VarDecl *, VarDecl *> initializedViaAccessor;
decl->collectPropertiesInitializableByInitAccessors(initializedViaAccessor);
// Emit the indirect return argument, if any.
bool hasInitAccessors = !decl->getInitAccessorProperties().empty();
SILValue resultSlot;
if (selfTy.isAddress()) {
auto &AC = SGF.getASTContext();
auto VD = new (AC) ParamDecl(SourceLoc(), SourceLoc(),
AC.getIdentifier("$return_value"),
SourceLoc(),
AC.getIdentifier("$return_value"),
ctor);
VD->setSpecifier(ParamSpecifier::InOut);
VD->setInterfaceType(selfIfaceTy);
resultSlot = SGF.F.begin()->createFunctionArgument(selfTy, VD);
} else if (hasInitAccessors) {
// Allocate "self" on stack which we are going to use to
// reference/init fields and then load to return.
resultSlot = SGF.emitTemporaryAllocation(Loc, selfTy);
}
LoweredParamsInContextGenerator loweredParams(SGF);
// Emit the elementwise arguments.
SmallVector<RValue, 4> elements;
for (size_t i = 0, size = paramList->size(); i < size; ++i) {
auto ¶m = paramList->get(i);
elements.push_back(
emitImplicitValueConstructorArg(
SGF, Loc, param->getInterfaceType()->getCanonicalType(), ctor,
loweredParams));
}
SGF.AllocatorMetatype = emitConstructorMetatypeArg(SGF, ctor);
(void) loweredParams.claimNext();
loweredParams.finish();
auto subs = getSubstitutionsForPropertyInitializer(decl, decl);
// If we have an indirect return slot, initialize it in-place.
if (resultSlot) {
auto elti = elements.begin(), eltEnd = elements.end();
llvm::SmallPtrSet<VarDecl *, 4> storedProperties;
{
auto properties = decl->getStoredProperties();
storedProperties.insert(properties.begin(), properties.end());
}
for (auto *member : decl->getAllMembers()) {
auto *field = dyn_cast<VarDecl>(member);
if (!field)
continue;
if (initializedViaAccessor.count(field))
continue;
// Handle situations where this stored propery is initialized
// via a call to an init accessor on some other property.
if (auto *initAccessor = field->getAccessor(AccessorKind::Init)) {
if (field->isMemberwiseInitialized(/*preferDeclaredProperties=*/true)) {
assert(elti != eltEnd &&
"number of args does not match number of fields");
emitApplyOfInitAccessor(SGF, Loc, initAccessor, resultSlot,
selfIfaceTy, selfTy, std::move(*elti));
++elti;
continue;
}
}
// If this is not one of the stored properties, let's move on.
if (!storedProperties.count(field))
continue;
auto fieldTy =
selfTy.getFieldType(field, SGF.SGM.M, SGF.getTypeExpansionContext());
SILValue slot =
SGF.B.createStructElementAddr(Loc, resultSlot, field,
fieldTy.getAddressType());
if (SGF.getOptions().EnableImportPtrauthFieldFunctionPointers &&
field->getPointerAuthQualifier().isPresent()) {
slot = SGF.B.createBeginAccess(
Loc, slot, SILAccessKind::Init, SILAccessEnforcement::Signed,
/* noNestedConflict */ false, /* fromBuiltin */ false);
}
InitializationPtr init(new KnownAddressInitialization(slot));
// If it's memberwise initialized, do so now.
if (field->isMemberwiseInitialized(/*preferDeclaredProperties=*/false)) {
assert(elti != eltEnd &&
"number of args does not match number of fields");
(void)eltEnd;
FullExpr scope(SGF.Cleanups, field->getParentPatternBinding());
RValue arg = std::move(*elti);
// If the stored property has an attached result builder and its
// type is not a function type, the argument is a noescape closure
// that needs to be called.
if (field->getResultBuilderType()) {
if (!field->getValueInterfaceType()
->lookThroughAllOptionalTypes()->is<AnyFunctionType>()) {
auto resultTy = cast<FunctionType>(arg.getType()).getResult();
arg = SGF.emitMonomorphicApply(
Loc, std::move(arg).getAsSingleValue(SGF, Loc), {}, resultTy,
resultTy, ApplyOptions(), std::nullopt, std::nullopt);
}
}
maybeEmitPropertyWrapperInitFromValue(SGF, Loc, field, subs,
std::move(arg))
.forwardInto(SGF, Loc, init.get());
++elti;
} else {
// TODO: This doesn't correctly take into account destructuring
// pattern bindings on `let`s, for example `let (a, b) = foo()`. In
// cases like that, we ought to evaluate the initializer expression once
// and then do a pattern assignment to the variables in the pattern.
// That case is currently forbidden with an "unsupported" error message
// in Sema.
assert(field->getTypeInContext()->getReferenceStorageReferent()->isEqual(
field->getParentExecutableInitializer()->getType()) &&
"Initialization of field with mismatched type!");
// Cleanup after this initialization.
FullExpr scope(SGF.Cleanups, field->getParentPatternBinding());
// If this is a property wrapper backing storage var that isn't
// memberwise initialized and has an original wrapped value, apply
// the property wrapper backing initializer.
if (auto *wrappedVar = field->getOriginalWrappedProperty()) {
auto initInfo = wrappedVar->getPropertyWrapperInitializerInfo();
auto *placeholder = initInfo.getWrappedValuePlaceholder();
if (placeholder && placeholder->getOriginalWrappedValue()) {
auto arg = SGF.emitRValue(placeholder->getOriginalWrappedValue());
maybeEmitPropertyWrapperInitFromValue(SGF, Loc, field, subs,
std::move(arg))
.forwardInto(SGF, Loc, init.get());
continue;
}
}
SGF.emitExprInto(field->getParentExecutableInitializer(), init.get());
}
if (SGF.getOptions().EnableImportPtrauthFieldFunctionPointers &&
field->getPointerAuthQualifier().isPresent()) {
SGF.B.createEndAccess(Loc, slot, /* aborted */ false);
}
}
// Load as "take" from our stack allocation and return.
if (!selfTy.isAddress() && hasInitAccessors) {
auto resultValue = SGF.B.emitLoadValueOperation(
Loc, resultSlot, LoadOwnershipQualifier::Take);
SGF.B.createReturn(ImplicitReturnLocation(Loc), resultValue,
std::move(functionLevelScope));
return;
}
SGF.B.createReturn(ImplicitReturnLocation(Loc),
SGF.emitEmptyTuple(Loc), std::move(functionLevelScope));
return;
}
// Otherwise, build a struct value directly from the elements.
SmallVector<SILValue, 4> eltValues;
auto elti = elements.begin(), eltEnd = elements.end();
for (VarDecl *field : decl->getStoredProperties()) {
auto fieldTy =
selfTy.getFieldType(field, SGF.SGM.M, SGF.getTypeExpansionContext());
RValue value;
FullExpr scope(SGF.Cleanups, field->getParentPatternBinding());
// If it's memberwise initialized, do so now.
if (field->isMemberwiseInitialized(/*preferDeclaredProperties=*/false)) {
assert(elti != eltEnd && "number of args does not match number of fields");
(void)eltEnd;
value = std::move(*elti);
++elti;
} else {
// Otherwise, use its initializer.
// TODO: This doesn't correctly take into account destructuring
// pattern bindings on `let`s, for example `let (a, b) = foo()`. In
// cases like that, we ought to evaluate the initializer expression once
// and then do a pattern assignment to the variables in the pattern.
// That case is currently forbidden with an "unsupported" error message
// in Sema.
assert(field->isParentExecutabledInitialized());
Expr *init = field->getParentExecutableInitializer();
// If this is a property wrapper backing storage var that isn't
// memberwise initialized, use the original wrapped value if it exists.
if (auto *wrappedVar = field->getOriginalWrappedProperty()) {
auto initInfo = wrappedVar->getPropertyWrapperInitializerInfo();
auto *placeholder = initInfo.getWrappedValuePlaceholder();
if (placeholder && placeholder->getOriginalWrappedValue()) {
init = placeholder->getOriginalWrappedValue();
}
}
value = SGF.emitRValue(init);
}
// Cleanup after this initialization.
SILValue v = maybeEmitPropertyWrapperInitFromValue(SGF, Loc, field, subs,
std::move(value))
.forwardAsSingleStorageValue(SGF, fieldTy, Loc);
eltValues.push_back(v);
}
SILValue selfValue = SGF.B.createStruct(Loc, selfTy, eltValues);
SGF.B.createReturn(ImplicitReturnLocation(Loc),
selfValue, std::move(functionLevelScope));
return;
}
// FIXME: the callers of ctorHopsInjectedByDefiniteInit is not correct (rdar://87485045)
// we must still set the SGF.ExpectedExecutor field to say that we must
// hop to the executor after every apply in the constructor. This seems to
// happen for the main actor isolated async inits, but not for the plain ones,
// where 'self' is not going to directly be the instance. We have to extend the
// ExecutorBreadcrumb class to detect whether it needs to do a load or not
// in it's emit method.
//
// So, the big problem right now is that for a delegating async actor init,
// after calling an async function, no hop-back is being emitted.
/// Returns true if the given async constructor will have its
/// required actor hops injected later by definite initialization.
static bool ctorHopsInjectedByDefiniteInit(ConstructorDecl *ctor,
ActorIsolation const& isolation) {
// must be async, but we can assume that.
assert(ctor->hasAsync());
auto *dc = ctor->getDeclContext();
auto selfClassDecl = dc->getSelfClassDecl();
// must be an actor
if (!selfClassDecl || !selfClassDecl->isAnyActor())
return false;
// must be instance isolated
switch (isolation) {
case ActorIsolation::ActorInstance:
return true;
case ActorIsolation::Erased:
llvm_unreachable("constructor cannot have erased isolation");
case ActorIsolation::Unspecified:
case ActorIsolation::Nonisolated:
case ActorIsolation::NonisolatedUnsafe:
case ActorIsolation::GlobalActor:
return false;
}
}
void SILGenFunction::emitValueConstructor(ConstructorDecl *ctor) {
MagicFunctionName = SILGenModule::getMagicFunctionName(ctor);
if (ctor->isMemberwiseInitializer())
return emitImplicitValueConstructor(*this, ctor);
// True if this constructor delegates to a peer constructor with self.init().
bool isDelegating = ctor->getDelegatingOrChainedInitKind().initKind ==
BodyInitKind::Delegating;
if (ctor->requiresUnavailableDeclABICompatibilityStubs())
emitApplyOfUnavailableCodeReached();
// Get the 'self' decl and type.
VarDecl *selfDecl = ctor->getImplicitSelfDecl();
auto &lowering = getTypeLowering(selfDecl->getTypeInContext());
// Decide if we need to do extra work to warn on unsafe behavior in pre-Swift-5
// modes.
MarkUninitializedInst::Kind MUIKind;
if (isDelegating) {
MUIKind = MarkUninitializedInst::DelegatingSelf;
} else if (getASTContext().isSwiftVersionAtLeast(5)) {
MUIKind = MarkUninitializedInst::RootSelf;
} else {
auto *dc = ctor->getParent();
if (isa<ExtensionDecl>(dc) &&
dc->getSelfStructDecl()->getParentModule() != dc->getParentModule()) {
MUIKind = MarkUninitializedInst::CrossModuleRootSelf;
} else {
MUIKind = MarkUninitializedInst::RootSelf;
}
}
// Allocate the local variable for 'self'.
emitLocalVariableWithCleanup(selfDecl, MUIKind)->finishInitialization(*this);
ManagedValue selfLV =
maybeEmitValueOfLocalVarDecl(selfDecl, AccessKind::ReadWrite);
assert(selfLV);
// Emit the prolog.
emitBasicProlog(ctor,
ctor->getParameters(),
/*selfParam=*/nullptr,
ctor->getResultInterfaceType(),
ctor->getEffectiveThrownErrorType(),
ctor->getThrowsLoc(),
/*ignored parameters*/ 1);
AllocatorMetatype = emitConstructorMetatypeArg(*this, ctor);
// Make sure we've hopped to the right global actor, if any.
if (ctor->hasAsync()) {
auto isolation = getActorIsolation(ctor);
// if it's not injected by definite init, we do it in the prologue now.
if (!ctorHopsInjectedByDefiniteInit(ctor, isolation)) {
SILLocation prologueLoc(selfDecl);
prologueLoc.markAsPrologue();
emitConstructorPrologActorHop(prologueLoc, isolation);
}
}
// Create a basic block to jump to for the implicit 'self' return.
// We won't emit this until after we've emitted the body.
// The epilog takes a void return because the return of 'self' is implicit.
prepareEpilog(ctor, std::nullopt, ctor->getEffectiveThrownErrorType(),
CleanupLocation(ctor));
// If the constructor can fail, set up an alternative epilog for constructor
// failure.
SILBasicBlock *failureExitBB = nullptr;
SILArgument *failureExitArg = nullptr;
auto resultType = ctor->mapTypeIntoContext(ctor->getResultInterfaceType());
auto &resultLowering = getTypeLowering(resultType);
if (ctor->isFailable()) {
SILBasicBlock *failureBB = createBasicBlock(FunctionSection::Postmatter);
// On failure, we'll clean up everything (except self, which should have
// been cleaned up before jumping here) and return nil instead.
SILGenSavedInsertionPoint savedIP(*this, failureBB,
FunctionSection::Postmatter);
failureExitBB = createBasicBlock();
Cleanups.emitCleanupsForReturn(ctor, IsForUnwind);
// Return nil.
if (F.getConventions().hasIndirectSILResults()) {
// Inject 'nil' into the indirect return.
assert(F.getIndirectResults().size() == 1);
B.createInjectEnumAddr(ctor, F.getIndirectResults()[0],
getASTContext().getOptionalNoneDecl());
B.createBranch(ctor, failureExitBB);
B.setInsertionPoint(failureExitBB);
B.createReturn(ctor, emitEmptyTuple(ctor));
} else {
// Pass 'nil' as the return value to the exit BB.
failureExitArg = failureExitBB->createPhiArgument(
resultLowering.getLoweredType(), OwnershipKind::Owned);
SILValue nilResult =
B.createEnum(ctor, SILValue(), getASTContext().getOptionalNoneDecl(),
resultLowering.getLoweredType());
B.createBranch(ctor, failureExitBB, nilResult);
B.setInsertionPoint(failureExitBB);
B.createReturn(ctor, failureExitArg);
}
FailDest = JumpDest(failureBB, Cleanups.getCleanupsDepth(), ctor);
}
// If this is not a delegating constructor, emit member initializers.
if (!isDelegating) {
auto *typeDC = ctor->getDeclContext();
auto *nominal = typeDC->getSelfNominalTypeDecl();
// If we have an empty move only struct, then we will not initialize it with
// any member initializers, breaking SIL. So in that case, just construct a
// SIL struct value and initialize the memory with that.
//
// DISCUSSION: This only happens with noncopyable types since the memory
// lifetime checker doesn't seem to process trivial locations. But empty
// move only structs are non-trivial, so we need to handle this here.
if (nominal->getAttrs().hasAttribute<RawLayoutAttr>()) {
auto *module = ctor->getParentModule();
// Raw memory is not directly decomposable, but we still want to mark
// it as initialized. Use a zero initializer.
auto &C = ctor->getASTContext();
auto zeroInit = getBuiltinValueDecl(C, C.getIdentifier("zeroInitializer"));
B.createBuiltin(ctor, zeroInit->getBaseIdentifier(),
SILType::getEmptyTupleType(C),
SubstitutionMap::get(zeroInit->getInnermostDeclContext()
->getGenericSignatureOfContext(),
{selfDecl->getTypeInContext()},
LookUpConformanceInModule(module)),
selfLV.getLValueAddress());
} else if (isa<StructDecl>(nominal) && !nominal->canBeCopyable()
&& nominal->getStoredProperties().empty()) {
auto *si = B.createStruct(ctor, lowering.getLoweredType(), {});
B.emitStoreValueOperation(ctor, si, selfLV.getLValueAddress(),
StoreOwnershipQualifier::Init);
} else {
emitMemberInitializers(ctor, selfDecl, nominal);
}
}
emitProfilerIncrement(ctor->getTypecheckedBody());
// Emit the constructor body.
emitStmt(ctor->getTypecheckedBody());
// Build a custom epilog block, since the AST representation of the
// constructor decl (which has no self in the return type) doesn't match the
// SIL representation.
SILValue selfValue;
{
SILGenSavedInsertionPoint savedIP(*this, ReturnDest.getBlock());
assert(B.getInsertionBB()->empty() && "Epilog already set up?");
auto cleanupLoc = CleanupLocation(ctor);
if (!F.getConventions().hasIndirectSILResults()) {
// Otherwise, load and return the final 'self' value.
if (selfLV.getType().isMoveOnly()) {
selfLV = B.createMarkUnresolvedNonCopyableValueInst(
cleanupLoc, selfLV,
MarkUnresolvedNonCopyableValueInst::CheckKind::
AssignableButNotConsumable);
}
selfValue = lowering.emitLoad(B, cleanupLoc, selfLV.getValue(),
LoadOwnershipQualifier::Copy);
// Inject the self value into an optional if the constructor is failable.
if (ctor->isFailable()) {
selfValue = B.createEnum(cleanupLoc, selfValue,
getASTContext().getOptionalSomeDecl(),
getLoweredLoadableType(resultType));
}
} else {
// If 'self' is address-only, copy 'self' into the indirect return slot.
assert(F.getConventions().getNumIndirectSILResults() == 1
&& "no indirect return for address-only ctor?!");
// Get the address to which to store the result.
SILValue completeReturnAddress = F.getIndirectResults()[0];
SILValue returnAddress;
if (!ctor->isFailable()) {
// For non-failable initializers, store to the return address directly.
returnAddress = completeReturnAddress;
} else {
// If this is a failable initializer, project out the payload.
returnAddress = B.createInitEnumDataAddr(
cleanupLoc, completeReturnAddress,
getASTContext().getOptionalSomeDecl(), selfLV.getType());
}
// We have to do a non-take copy because someone else may be using the
// box (e.g. someone could have closed over it).
B.createCopyAddr(cleanupLoc, selfLV.getLValueAddress(), returnAddress,
IsNotTake, IsInitialization);
// Inject the enum tag if the result is optional because of failability.
if (ctor->isFailable()) {
// Inject the 'Some' tag.
B.createInjectEnumAddr(cleanupLoc, completeReturnAddress,
getASTContext().getOptionalSomeDecl());
}
}
}
// Finally, emit the epilog and post-matter.
auto returnLoc = emitEpilog(ctor, /*UsesCustomEpilog*/true);
// Finish off the epilog by returning. If this is a failable ctor, then we
// actually jump to the failure epilog to keep the invariant that there is
// only one SIL return instruction per SIL function.
if (B.hasValidInsertionPoint()) {
if (!failureExitBB) {
// If we're not returning self, then return () since we're returning Void.
if (!selfValue) {
CleanupLocation loc(ctor);
loc.markAutoGenerated();
selfValue = emitEmptyTuple(loc);
}
B.createReturn(returnLoc, selfValue);
} else {
if (selfValue)
B.createBranch(returnLoc, failureExitBB, selfValue);
else
B.createBranch(returnLoc, failureExitBB);
}
}
}
void SILGenFunction::emitEnumConstructor(EnumElementDecl *element) {
Type enumIfaceTy = element->getParentEnum()->getDeclaredInterfaceType();
Type enumTy = F.mapTypeIntoContext(enumIfaceTy);
auto &enumTI =
SGM.Types.getTypeLowering(enumTy, TypeExpansionContext::minimal());
if (element->requiresUnavailableDeclABICompatibilityStubs())
emitApplyOfUnavailableCodeReached();
RegularLocation Loc(element);
CleanupLocation CleanupLoc(element);
Loc.markAutoGenerated();
// Emit the indirect return slot.
std::unique_ptr<Initialization> dest;
if (enumTI.isAddressOnly() && silConv.useLoweredAddresses()) {
auto &AC = getASTContext();
auto VD = new (AC) ParamDecl(SourceLoc(), SourceLoc(),
AC.getIdentifier("$return_value"),
SourceLoc(),
AC.getIdentifier("$return_value"),
element->getDeclContext());
VD->setSpecifier(ParamSpecifier::InOut);
VD->setInterfaceType(enumIfaceTy);
auto resultSlot =
F.begin()->createFunctionArgument(enumTI.getLoweredType(), VD);
dest = std::unique_ptr<Initialization>(
new KnownAddressInitialization(resultSlot));
}
Scope scope(Cleanups, CleanupLoc);
LoweredParamsInContextGenerator loweredParams(*this);
// Emit the exploded constructor argument.
SmallVector<ArgumentSource, 2> payloads;
if (element->hasAssociatedValues()) {
auto elementFnTy =
cast<AnyFunctionType>(
cast<AnyFunctionType>(element->getInterfaceType()->getCanonicalType())
.getResult());
auto elementParams = elementFnTy.getParams();
payloads.reserve(elementParams.size());
for (auto param: elementParams) {
auto paramType = param.getParameterType();
RValue arg = emitImplicitValueConstructorArg(*this, Loc, paramType,
element, loweredParams);
payloads.emplace_back(Loc, std::move(arg));
}
}
// Emit the metatype argument.
AllocatorMetatype = emitConstructorMetatypeArg(*this, element);
(void) loweredParams.claimNext();
loweredParams.finish();
// If possible, emit the enum directly into the indirect return.
SGFContext C = (dest ? SGFContext(dest.get()) : SGFContext());
ManagedValue mv = emitInjectEnum(Loc, payloads,
enumTI.getLoweredType(),
element, C);
// Return the enum.
auto ReturnLoc = ImplicitReturnLocation(Loc);
if (dest) {
if (!mv.isInContext()) {
dest->copyOrInitValueInto(*this, Loc, mv, /*isInit*/ true);
dest->finishInitialization(*this);
}
scope.pop();
B.createReturn(ReturnLoc, emitEmptyTuple(CleanupLocation(Loc)));
} else {
assert(enumTI.isLoadable() || !silConv.useLoweredAddresses());
SILValue result = mv.ensurePlusOne(*this, ReturnLoc).forward(*this);
scope.pop();
B.createReturn(ReturnLoc, result);
}
}
void SILGenFunction::emitClassConstructorAllocator(ConstructorDecl *ctor) {
assert(!ctor->isFactoryInit() && "factories should not be emitted here");
// Emit the prolog. Since we're just going to forward our args directly
// to the initializer, don't allocate local variables for them.
RegularLocation Loc(ctor);
Loc.markAutoGenerated();
// Forward the constructor arguments.
// FIXME: Handle 'self' along with the other body patterns.
SmallVector<SILValue, 8> args;
// If the function we're calling has an indirect error result, create an
// argument for it.
if (F.getConventions().hasIndirectSILErrorResults()) {
assert(F.getConventions().getNumIndirectSILErrorResults() == 1);
auto paramTy = F.mapTypeIntoContext(
F.getConventions().getSILErrorType(getTypeExpansionContext()));
auto inContextParamTy = F.getLoweredType(paramTy.getASTType())
.getCategoryType(paramTy.getCategory());
SILArgument *arg = F.begin()->createFunctionArgument(inContextParamTy);
IndirectErrorResult = arg;
args.push_back(arg);
}
bindParametersForForwarding(ctor->getParameters(), args);
if (ctor->requiresUnavailableDeclABICompatibilityStubs())
emitApplyOfUnavailableCodeReached();
AllocatorMetatype = emitConstructorMetatypeArg(*this, ctor);
SILValue selfMetaValue = AllocatorMetatype;
// Allocate the "self" value.
VarDecl *selfDecl = ctor->getImplicitSelfDecl();
SILType selfTy = getLoweredType(selfDecl->getTypeInContext());
assert(selfTy.hasReferenceSemantics() &&
"can't emit a value type ctor here");
// Use alloc_ref to allocate the object.
// TODO: allow custom allocation?
// FIXME: should have a cleanup in case of exception
auto selfClassDecl = ctor->getDeclContext()->getSelfClassDecl();
SILValue selfValue;
// Allocate the 'self' value.
bool useObjCAllocation = usesObjCAllocator(selfClassDecl);
if (ctor->hasClangNode() ||
ctor->shouldUseObjCDispatch() ||
ctor->isConvenienceInit()) {
assert(ctor->hasClangNode() || ctor->isObjC());
// For an allocator thunk synthesized for an @objc convenience initializer
// or imported Objective-C init method, allocate using the metatype.
SILValue allocArg = selfMetaValue;
// When using Objective-C allocation, convert the metatype
// argument to an Objective-C metatype.
if (useObjCAllocation) {
auto metaTy = allocArg->getType().castTo<MetatypeType>();
metaTy = CanMetatypeType::get(metaTy.getInstanceType(),