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SILGenPoly.cpp
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//===--- SILGenPoly.cpp - Function Type Thunks ----------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Swift function types can be equivalent or have a subtyping relationship even
// if the SIL-level lowering of the calling convention is different. The
// routines in this file implement thunking between lowered function types.
//
//
// Re-abstraction thunks
// =====================
// After SIL type lowering, generic substitutions become explicit, for example
// the AST type (Int) -> Int passes the Ints directly, whereas (T) -> T with Int
// substituted for T will pass the Ints like a T, as an address-only value with
// opaque type metadata. Such a thunk is called a "re-abstraction thunk" -- the
// AST-level type of the function value does not change, only the manner in
// which parameters and results are passed. See the comment in
// AbstractionPattern.h for details.
//
// Function conversion thunks
// ==========================
// In Swift's AST-level type system, certain types have a subtype relation
// involving a representation change. For example, a concrete type is always
// a subtype of any protocol it conforms to. The upcast from the concrete
// type to an existential type for the protocol requires packaging the
// payload together with type metadata and witness tables.
//
// Between function types, the type (A) -> B is defined to be a subtype of
// (A') -> B' iff A' is a subtype of A, and B is a subtype of B' -- parameters
// are contravariant, and results are covariant.
//
// A subtype conversion of a function value (A) -> B is performed by wrapping
// the function value in a thunk of type (A') -> B'. The thunk takes an A' and
// converts it into an A, calls the inner function value, and converts the
// result from B to B'.
//
// VTable thunks
// =============
//
// If a base class is generic and a derived class substitutes some generic
// parameter of the base with a concrete type, the derived class can override
// methods in the base that involved generic types. In the derived class, a
// method override that involves substituted types will have a different
// SIL lowering than the base method. In this case, the overridden vtable entry
// will point to a thunk which transforms parameters and results and invokes
// the derived method.
//
// Some limited forms of subtyping are also supported for method overrides;
// namely, a derived method's parameter can be a superclass of, or more
// optional than, a parameter of the base, and result can be a subclass of,
// or less optional than, the result of the base.
//
// Witness thunks
// ==============
//
// Protocol witness methods are called with an additional generic parameter
// bound to the Self type, and thus always require a thunk. Thunks are also
// required for conditional conformances, since the extra requirements aren't
// part of the protocol and so any witness tables need to be loaded from the
// original protocol's witness table and passed into the real witness method.
//
// Thunks for class method witnesses dispatch through the vtable allowing
// inherited witnesses to be overridden in subclasses. Hence a witness thunk
// might require two levels of abstraction difference -- the method might
// override a base class method with more generic types, and the protocol
// requirement may involve associated types which are always concrete in the
// conforming class.
//
// Other thunks
// ============
//
// Foreign-to-native, native-to-foreign thunks for declarations and function
// values are implemented in SILGenBridging.cpp.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "silgen-poly"
#include "ExecutorBreadcrumb.h"
#include "FunctionInputGenerator.h"
#include "Initialization.h"
#include "LValue.h"
#include "RValue.h"
#include "SILGen.h"
#include "SILGenFunction.h"
#include "SILGenFunctionBuilder.h"
#include "Scope.h"
#include "TupleGenerators.h"
#include "swift/Basic/Generators.h"
#include "swift/AST/ASTMangler.h"
#include "swift/AST/Decl.h"
#include "swift/AST/DiagnosticsSIL.h"
#include "swift/AST/ExistentialLayout.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/Module.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/Types.h"
#include "swift/SIL/PrettyStackTrace.h"
#include "swift/SIL/AbstractionPatternGenerators.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/TypeLowering.h"
#include "llvm/Support/Compiler.h"
using namespace swift;
using namespace Lowering;
static ParameterConvention
getScalarConventionForPackConvention(ParameterConvention conv) {
switch (conv) {
case ParameterConvention::Pack_Owned:
return ParameterConvention::Indirect_In;
case ParameterConvention::Pack_Guaranteed:
return ParameterConvention::Indirect_In_Guaranteed;
case ParameterConvention::Pack_Inout:
return ParameterConvention::Indirect_Inout;
default:
llvm_unreachable("not a pack convention");
}
llvm_unreachable("bad convention");
}
namespace {
class IndirectSlot {
llvm::PointerUnion<SILValue, SILType> value;
public:
explicit IndirectSlot(SILType type) : value(type) {}
IndirectSlot(SILValue address) : value(address) {
assert(address->getType().isAddress());
}
SILType getType() const {
if (value.is<SILValue>()) {
return value.get<SILValue>()->getType();
} else {
return value.get<SILType>();
}
}
bool hasAddress() const { return value.is<SILValue>(); }
SILValue getAddress() const {
return value.get<SILValue>();
}
SILValue allocate(SILGenFunction &SGF, SILLocation loc) const {
if (hasAddress()) return getAddress();
return SGF.emitTemporaryAllocation(loc, getType());
}
};
} // end anonymous namespace
static bool hasAbstractionDifference(SILType resultType1,
SILType resultType2) {
return resultType1.getASTType() != resultType2.getASTType();
}
static bool hasAbstractionDifference(IndirectSlot resultSlot,
SILValue resultAddr) {
return hasAbstractionDifference(resultSlot.getType(),
resultAddr->getType());
}
static bool hasAbstractionDifference(IndirectSlot resultSlot,
SILResultInfo resultInfo) {
return resultSlot.getType().getASTType()
!= resultInfo.getInterfaceType();
}
/// A helper function that pulls an element off the front of an array.
template <class T>
static const T &claimNext(ArrayRef<T> &array) {
assert(!array.empty() && "claiming next from empty array!");
const T &result = array.front();
array = array.slice(1);
return result;
}
namespace {
/// An abstract class for transforming first-class SIL values.
class Transform {
private:
SILGenFunction &SGF;
SILLocation Loc;
public:
Transform(SILGenFunction &SGF, SILLocation loc) : SGF(SGF), Loc(loc) {}
virtual ~Transform() = default;
/// Transform an arbitrary value.
RValue transform(RValue &&input,
AbstractionPattern inputOrigType,
CanType inputSubstType,
AbstractionPattern outputOrigType,
CanType outputSubstType,
SILType outputLoweredTy,
SGFContext ctxt);
/// Transform an arbitrary value.
ManagedValue transform(ManagedValue input,
AbstractionPattern inputOrigType,
CanType inputSubstType,
AbstractionPattern outputOrigType,
CanType outputSubstType,
SILType outputLoweredTy,
SGFContext ctxt);
/// Transform a metatype value.
ManagedValue transformMetatype(ManagedValue fn,
AbstractionPattern inputOrigType,
CanMetatypeType inputSubstType,
AbstractionPattern outputOrigType,
CanMetatypeType outputSubstType,
SILType outputLoweredTy);
/// Transform a tuple value.
ManagedValue transformTuple(ManagedValue input,
AbstractionPattern inputOrigType,
CanTupleType inputSubstType,
AbstractionPattern outputOrigType,
CanTupleType outputSubstType,
SILType outputLoweredTy,
SGFContext ctxt);
/// Transform a function value.
ManagedValue transformFunction(ManagedValue fn,
AbstractionPattern inputOrigType,
CanAnyFunctionType inputSubstType,
AbstractionPattern outputOrigType,
CanAnyFunctionType outputSubstType,
const TypeLowering &expectedTL);
};
} // end anonymous namespace
ManagedValue
SILGenFunction::emitTransformExistential(SILLocation loc,
ManagedValue input,
CanType inputType,
CanType outputType,
SGFContext ctxt) {
assert(inputType != outputType);
FormalEvaluationScope scope(*this);
if (inputType->isAnyExistentialType()) {
CanType openedType = OpenedArchetypeType::getAny(inputType,
F.getGenericSignature());
SILType loweredOpenedType = getLoweredType(openedType);
input = emitOpenExistential(loc, input,
loweredOpenedType, AccessKind::Read);
inputType = openedType;
}
// Build conformance table
CanType fromInstanceType = inputType;
CanType toInstanceType = outputType;
// Look through metatypes
while (isa<MetatypeType>(fromInstanceType) &&
isa<ExistentialMetatypeType>(toInstanceType)) {
fromInstanceType = cast<MetatypeType>(fromInstanceType)
.getInstanceType();
toInstanceType = cast<ExistentialMetatypeType>(toInstanceType)
->getExistentialInstanceType()->getCanonicalType();
}
assert(!fromInstanceType.isAnyExistentialType());
ArrayRef<ProtocolConformanceRef> conformances =
SGM.M.getSwiftModule()->collectExistentialConformances(
fromInstanceType,
toInstanceType,
/*allowMissing=*/true);
// Build result existential
AbstractionPattern opaque = AbstractionPattern::getOpaque();
const TypeLowering &concreteTL = getTypeLowering(opaque, inputType);
const TypeLowering &expectedTL = getTypeLowering(outputType);
return emitExistentialErasure(
loc, inputType, concreteTL, expectedTL,
conformances, ctxt,
[&](SGFContext C) -> ManagedValue {
return manageOpaqueValue(input, loc, C);
});
}
/// Apply this transformation to an arbitrary value.
RValue Transform::transform(RValue &&input,
AbstractionPattern inputOrigType,
CanType inputSubstType,
AbstractionPattern outputOrigType,
CanType outputSubstType,
SILType outputLoweredTy,
SGFContext ctxt) {
// Fast path: we don't have a tuple.
auto inputTupleType = dyn_cast<TupleType>(inputSubstType);
if (!inputTupleType) {
assert(!isa<TupleType>(outputSubstType) &&
"transformation introduced a tuple?");
auto result = transform(std::move(input).getScalarValue(),
inputOrigType, inputSubstType,
outputOrigType, outputSubstType,
outputLoweredTy, ctxt);
return RValue(SGF, Loc, outputSubstType, result);
}
// Okay, we have a tuple. The output type will also be a tuple unless
// there's a subtyping conversion that erases tuples, but that's currently
// not allowed by the typechecker, which considers existential erasure to
// be a conversion relation, not a subtyping one. Anyway, it would be
// possible to support that here, but since it's not currently required...
assert(isa<TupleType>(outputSubstType) &&
"subtype constraint erasing tuple is not currently implemented");
auto outputTupleType = cast<TupleType>(outputSubstType);
assert(inputTupleType->getNumElements() == outputTupleType->getNumElements());
assert(outputLoweredTy.is<TupleType>() &&
"expected lowered output type wasn't a tuple when formal type was");
assert(outputLoweredTy.castTo<TupleType>()->getNumElements() ==
outputTupleType->getNumElements());
// Pull the r-value apart.
SmallVector<RValue, 8> inputElts;
std::move(input).extractElements(inputElts);
// Emit into the context initialization if it's present and possible
// to split.
SmallVector<InitializationPtr, 4> eltInitsBuffer;
MutableArrayRef<InitializationPtr> eltInits;
auto tupleInit = ctxt.getEmitInto();
if (!ctxt.getEmitInto()
|| !ctxt.getEmitInto()->canSplitIntoTupleElements()) {
tupleInit = nullptr;
} else {
eltInits = tupleInit->splitIntoTupleElements(SGF, Loc, outputTupleType,
eltInitsBuffer);
}
// At this point, if tupleInit is non-null, we must emit all of the
// elements into their corresponding contexts.
assert(tupleInit == nullptr ||
eltInits.size() == inputTupleType->getNumElements());
SmallVector<ManagedValue, 8> outputExpansion;
for (auto eltIndex : indices(inputTupleType->getElementTypes())) {
// Determine the appropriate context for the element.
SGFContext eltCtxt;
if (tupleInit) eltCtxt = SGFContext(eltInits[eltIndex].get());
// Recurse.
RValue outputElt = transform(std::move(inputElts[eltIndex]),
inputOrigType.getTupleElementType(eltIndex),
inputTupleType.getElementType(eltIndex),
outputOrigType.getTupleElementType(eltIndex),
outputTupleType.getElementType(eltIndex),
outputLoweredTy.getTupleElementType(eltIndex),
eltCtxt);
// Force the r-value into its context if necessary.
assert(!outputElt.isInContext() || tupleInit != nullptr);
if (tupleInit && !outputElt.isInContext()) {
std::move(outputElt).forwardInto(SGF, Loc, eltInits[eltIndex].get());
} else {
std::move(outputElt).getAll(outputExpansion);
}
}
// If we emitted into context, be sure to finish the overall initialization.
if (tupleInit) {
tupleInit->finishInitialization(SGF);
return RValue::forInContext();
}
return RValue(SGF, outputExpansion, outputTupleType);
}
// Single @objc protocol value metatypes can be converted to the ObjC
// Protocol class type.
static bool isProtocolClass(Type t) {
auto classDecl = t->getClassOrBoundGenericClass();
if (!classDecl)
return false;
ASTContext &ctx = classDecl->getASTContext();
return (classDecl->getName() == ctx.Id_Protocol &&
classDecl->getModuleContext()->getName() == ctx.Id_ObjectiveC);
}
static ManagedValue emitManagedLoad(SILGenFunction &SGF, SILLocation loc,
ManagedValue addr,
const TypeLowering &addrTL) {
// SEMANTIC ARC TODO: When the verifier is finished, revisit this.
if (!addr.hasCleanup())
return SGF.B.createLoadBorrow(loc, addr);
auto loadedValue = addrTL.emitLoad(SGF.B, loc, addr.forward(SGF),
LoadOwnershipQualifier::Take);
return SGF.emitManagedRValueWithCleanup(loadedValue, addrTL);
}
/// Apply this transformation to an arbitrary value.
ManagedValue Transform::transform(ManagedValue v,
AbstractionPattern inputOrigType,
CanType inputSubstType,
AbstractionPattern outputOrigType,
CanType outputSubstType,
SILType loweredResultTy,
SGFContext ctxt) {
// Load if the result isn't address-only. All the translation routines
// expect this.
if (v.getType().isAddress()) {
auto &inputTL = SGF.getTypeLowering(v.getType());
if (!inputTL.isAddressOnly() || !SGF.silConv.useLoweredAddresses()) {
v = emitManagedLoad(SGF, Loc, v, inputTL);
}
}
// Downstream code expects the lowered result type to be an object if
// it's loadable, so make sure that's satisfied.
auto &expectedTL = SGF.getTypeLowering(loweredResultTy);
loweredResultTy = expectedTL.getLoweredType();
// Nothing to convert
if (v.getType() == loweredResultTy)
return v;
CanType inputObjectType = inputSubstType.getOptionalObjectType();
bool inputIsOptional = (bool) inputObjectType;
CanType outputObjectType = outputSubstType.getOptionalObjectType();
bool outputIsOptional = (bool) outputObjectType;
// If the value is less optional than the desired formal type, wrap in
// an optional.
if (outputIsOptional && !inputIsOptional) {
return SGF.emitInjectOptional(
Loc, expectedTL, ctxt, [&](SGFContext objectCtxt) {
return transform(v, inputOrigType, inputSubstType,
outputOrigType.getOptionalObjectType(),
outputObjectType,
loweredResultTy.getOptionalObjectType(),
objectCtxt);
});
}
// If the value is an optional, but the desired formal type isn't an
// optional or Any, force it.
if (inputIsOptional && !outputIsOptional &&
!outputSubstType->isExistentialType()) {
// isImplicitUnwrap is hardcoded true because the looseness in types of
// @objc witnesses/overrides that we're handling here only allows IUOs,
// not explicit Optionals.
v = SGF.emitCheckedGetOptionalValueFrom(Loc, v,
/*isImplicitUnwrap*/ true,
SGF.getTypeLowering(v.getType()),
SGFContext());
// Check if we have any more conversions remaining.
if (v.getType() == loweredResultTy)
return v;
inputIsOptional = false;
}
// Optional-to-optional conversion.
if (inputIsOptional && outputIsOptional) {
// If the conversion is trivial, just cast.
if (SGF.SGM.Types.checkForABIDifferences(SGF.SGM.M,
v.getType(), loweredResultTy)
== TypeConverter::ABIDifference::CompatibleRepresentation) {
if (v.getType().isAddress())
return SGF.B.createUncheckedAddrCast(Loc, v, loweredResultTy);
return SGF.B.createUncheckedBitCast(Loc, v, loweredResultTy);
}
auto transformOptionalPayload =
[&](SILGenFunction &SGF, SILLocation loc, ManagedValue input,
SILType loweredResultTy, SGFContext context) -> ManagedValue {
return transform(input, inputOrigType.getOptionalObjectType(),
inputObjectType, outputOrigType.getOptionalObjectType(),
outputObjectType, loweredResultTy, context);
};
return SGF.emitOptionalToOptional(Loc, v, loweredResultTy,
transformOptionalPayload);
}
// Abstraction changes:
// - functions
if (auto outputFnType = dyn_cast<AnyFunctionType>(outputSubstType)) {
auto inputFnType = cast<AnyFunctionType>(inputSubstType);
return transformFunction(v,
inputOrigType, inputFnType,
outputOrigType, outputFnType,
expectedTL);
}
// - tuples of transformable values
if (auto outputTupleType = dyn_cast<TupleType>(outputSubstType)) {
auto inputTupleType = cast<TupleType>(inputSubstType);
return transformTuple(v,
inputOrigType, inputTupleType,
outputOrigType, outputTupleType,
loweredResultTy, ctxt);
}
// - metatypes
if (auto outputMetaType = dyn_cast<MetatypeType>(outputSubstType)) {
if (auto inputMetaType = dyn_cast<MetatypeType>(inputSubstType)) {
return transformMetatype(v,
inputOrigType, inputMetaType,
outputOrigType, outputMetaType,
loweredResultTy);
}
}
// Subtype conversions:
// A base class method returning Self can be used in place of a derived
// class method returning Self.
if (auto inputSelfType = dyn_cast<DynamicSelfType>(inputSubstType)) {
inputSubstType = inputSelfType.getSelfType();
}
// - casts for classes
if (outputSubstType->getClassOrBoundGenericClass() &&
inputSubstType->getClassOrBoundGenericClass()) {
auto class1 = inputSubstType->getClassOrBoundGenericClass();
auto class2 = outputSubstType->getClassOrBoundGenericClass();
// CF <-> Objective-C via toll-free bridging.
if ((class1->getForeignClassKind() == ClassDecl::ForeignKind::CFType) ^
(class2->getForeignClassKind() == ClassDecl::ForeignKind::CFType)) {
return SGF.B.createUncheckedRefCast(Loc, v, loweredResultTy);
}
if (outputSubstType->isExactSuperclassOf(inputSubstType)) {
// Upcast to a superclass.
return SGF.B.createUpcast(Loc, v, loweredResultTy);
} else {
// FIXME: Should only happen with the DynamicSelfType case above,
// except that convenience inits return the static self and not
// DynamicSelfType.
assert(inputSubstType->isExactSuperclassOf(outputSubstType)
&& "should be inheritance relationship between input and output");
return SGF.B.createUncheckedRefCast(Loc, v, loweredResultTy);
}
}
// - upcasts for collections
if (outputSubstType->getStructOrBoundGenericStruct() &&
inputSubstType->getStructOrBoundGenericStruct()) {
auto *inputStruct = inputSubstType->getStructOrBoundGenericStruct();
auto *outputStruct = outputSubstType->getStructOrBoundGenericStruct();
// Attempt collection upcast only if input and output declarations match.
if (inputStruct == outputStruct) {
FuncDecl *fn = nullptr;
if (inputSubstType->isArray()) {
fn = SGF.SGM.getArrayForceCast(Loc);
} else if (inputSubstType->isDictionary()) {
fn = SGF.SGM.getDictionaryUpCast(Loc);
} else if (inputSubstType->isSet()) {
fn = SGF.SGM.getSetUpCast(Loc);
} else {
llvm::report_fatal_error("unsupported collection upcast kind");
}
return SGF.emitCollectionConversion(Loc, fn, inputSubstType,
outputSubstType, v, ctxt)
.getScalarValue();
}
}
// - upcasts from an archetype
if (outputSubstType->getClassOrBoundGenericClass()) {
if (auto archetypeType = dyn_cast<ArchetypeType>(inputSubstType)) {
if (archetypeType->getSuperclass()) {
// Replace the cleanup with a new one on the superclass value so we
// always use concrete retain/release operations.
return SGF.B.createUpcast(Loc, v, loweredResultTy);
}
}
}
// - metatype to Protocol conversion
if (isProtocolClass(outputSubstType)) {
if (auto metatypeTy = dyn_cast<MetatypeType>(inputSubstType)) {
return SGF.emitProtocolMetatypeToObject(Loc, metatypeTy,
SGF.getLoweredLoadableType(outputSubstType));
}
}
// - metatype to AnyObject conversion
if (outputSubstType->isAnyObject() &&
isa<MetatypeType>(inputSubstType)) {
return SGF.emitClassMetatypeToObject(Loc, v,
SGF.getLoweredLoadableType(outputSubstType));
}
// - existential metatype to AnyObject conversion
if (outputSubstType->isAnyObject() &&
isa<ExistentialMetatypeType>(inputSubstType)) {
return SGF.emitExistentialMetatypeToObject(Loc, v,
SGF.getLoweredLoadableType(outputSubstType));
}
// - block to AnyObject conversion (under ObjC interop)
if (outputSubstType->isAnyObject() &&
SGF.getASTContext().LangOpts.EnableObjCInterop) {
if (auto inputFnType = dyn_cast<AnyFunctionType>(inputSubstType)) {
if (inputFnType->getRepresentation() == FunctionTypeRepresentation::Block)
return SGF.B.createBlockToAnyObject(Loc, v, loweredResultTy);
}
}
// - existentials
if (outputSubstType->isAnyExistentialType()) {
// We have to re-abstract payload if its a metatype or a function
v = SGF.emitSubstToOrigValue(Loc, v, AbstractionPattern::getOpaque(),
inputSubstType);
return SGF.emitTransformExistential(Loc, v,
inputSubstType, outputSubstType,
ctxt);
}
// - upcasting class-constrained existentials or metatypes thereof
if (inputSubstType->isAnyExistentialType()) {
auto instanceType = inputSubstType;
while (auto metatypeType = dyn_cast<ExistentialMetatypeType>(instanceType))
instanceType = metatypeType.getInstanceType();
auto layout = instanceType.getExistentialLayout();
if (layout.getSuperclass()) {
CanType openedType =
OpenedArchetypeType::getAny(inputSubstType,
SGF.F.getGenericSignature());
SILType loweredOpenedType = SGF.getLoweredType(openedType);
FormalEvaluationScope scope(SGF);
auto payload = SGF.emitOpenExistential(Loc, v,
loweredOpenedType,
AccessKind::Read);
payload = payload.ensurePlusOne(SGF, Loc);
return transform(payload,
AbstractionPattern::getOpaque(),
openedType,
outputOrigType,
outputSubstType,
loweredResultTy,
ctxt);
}
}
// - T : Hashable to AnyHashable
if (outputSubstType->isAnyHashable()) {
auto *protocol = SGF.getASTContext().getProtocol(
KnownProtocolKind::Hashable);
auto conformance = SGF.SGM.M.getSwiftModule()->lookupConformance(
inputSubstType, protocol);
auto addr = v.getType().isAddress() ? v : v.materialize(SGF, Loc);
auto result = SGF.emitAnyHashableErasure(Loc, addr, inputSubstType,
conformance, ctxt);
if (result.isInContext())
return ManagedValue::forInContext();
return std::move(result).getAsSingleValue(SGF, Loc);
}
// Should have handled the conversion in one of the cases above.
v.dump();
llvm_unreachable("Unhandled transform?");
}
ManagedValue Transform::transformMetatype(ManagedValue meta,
AbstractionPattern inputOrigType,
CanMetatypeType inputSubstType,
AbstractionPattern outputOrigType,
CanMetatypeType outputSubstType,
SILType expectedType) {
assert(!meta.hasCleanup() && "metatype with cleanup?!");
auto wasRepr = meta.getType().castTo<MetatypeType>()->getRepresentation();
auto willBeRepr = expectedType.castTo<MetatypeType>()->getRepresentation();
SILValue result;
if ((wasRepr == MetatypeRepresentation::Thick &&
willBeRepr == MetatypeRepresentation::Thin) ||
(wasRepr == MetatypeRepresentation::Thin &&
willBeRepr == MetatypeRepresentation::Thick)) {
// If we have a thin-to-thick abstraction change, cook up new a metatype
// value out of nothing -- thin metatypes carry no runtime state.
result = SGF.B.createMetatype(Loc, expectedType);
} else {
// Otherwise, we have a metatype subtype conversion of thick metatypes.
assert(wasRepr == willBeRepr && "Unhandled metatype conversion");
result = SGF.B.createUpcast(Loc, meta.getUnmanagedValue(), expectedType);
}
return ManagedValue::forObjectRValueWithoutOwnership(result);
}
/// Explode a managed tuple into a bunch of managed elements.
///
/// If the tuple is in memory, the result elements will also be in
/// memory.
static void explodeTuple(SILGenFunction &SGF, SILLocation loc,
ManagedValue managedTuple,
SmallVectorImpl<ManagedValue> &out) {
// If the tuple is empty, there's nothing to do.
if (managedTuple.getType().castTo<TupleType>()->getNumElements() == 0)
return;
SmallVector<SILValue, 16> elements;
bool isPlusOne = managedTuple.hasCleanup();
if (managedTuple.getType().isAddress()) {
SGF.B.emitDestructureAddressOperation(loc, managedTuple.forward(SGF),
elements);
} else {
SGF.B.emitDestructureValueOperation(loc, managedTuple.forward(SGF),
elements);
}
for (auto element : elements) {
if (element->getType().isTrivial(SGF.F)) {
out.push_back(ManagedValue::forRValueWithoutOwnership(element));
continue;
}
if (!isPlusOne) {
out.push_back(ManagedValue::forBorrowedRValue(element));
continue;
}
if (element->getType().isAddress()) {
out.push_back(SGF.emitManagedBufferWithCleanup(element));
continue;
}
out.push_back(SGF.emitManagedRValueWithCleanup(element));
}
}
/// Apply this transformation to all the elements of a tuple value,
/// which just entails mapping over each of its component elements.
ManagedValue Transform::transformTuple(ManagedValue inputTuple,
AbstractionPattern inputOrigType,
CanTupleType inputSubstType,
AbstractionPattern outputOrigType,
CanTupleType outputSubstType,
SILType outputLoweredTy,
SGFContext ctxt) {
const TypeLowering &outputTL =
SGF.getTypeLowering(outputLoweredTy);
assert((outputTL.isAddressOnly() == inputTuple.getType().isAddress() ||
!SGF.silConv.useLoweredAddresses()) &&
"expected loadable inputs to have been loaded");
// If there's no representation difference, we're done.
if (outputLoweredTy == inputTuple.getType().copyCategory(outputLoweredTy))
return inputTuple;
assert(inputOrigType.matchesTuple(outputSubstType));
assert(outputOrigType.matchesTuple(outputSubstType));
auto inputType = inputTuple.getType().castTo<TupleType>();
assert(outputSubstType->getNumElements() == inputType->getNumElements());
// If the tuple is address only, we need to do the operation in memory.
SILValue outputAddr;
if (outputTL.isAddressOnly() && SGF.silConv.useLoweredAddresses())
outputAddr = SGF.getBufferForExprResult(Loc, outputLoweredTy, ctxt);
// Explode the tuple into individual managed values.
SmallVector<ManagedValue, 4> inputElts;
explodeTuple(SGF, Loc, inputTuple, inputElts);
// Track all the managed elements whether or not we're actually
// emitting to an address, just so that we can disable them after.
SmallVector<ManagedValue, 4> outputElts;
for (auto index : indices(inputType->getElementTypes())) {
auto &inputEltTL = SGF.getTypeLowering(inputElts[index].getType());
ManagedValue inputElt = inputElts[index];
if (inputElt.getType().isAddress() && !inputEltTL.isAddressOnly()) {
inputElt = emitManagedLoad(SGF, Loc, inputElt, inputEltTL);
}
auto inputEltOrigType = inputOrigType.getTupleElementType(index);
auto inputEltSubstType = inputSubstType.getElementType(index);
auto outputEltOrigType = outputOrigType.getTupleElementType(index);
auto outputEltSubstType = outputSubstType.getElementType(index);
auto outputEltLoweredTy = outputLoweredTy.getTupleElementType(index);
// If we're emitting to memory, project out this element in the
// destination buffer, then wrap that in an Initialization to
// track the cleanup.
std::optional<TemporaryInitialization> outputEltTemp;
if (outputAddr) {
SILValue outputEltAddr =
SGF.B.createTupleElementAddr(Loc, outputAddr, index);
auto &outputEltTL = SGF.getTypeLowering(outputEltLoweredTy);
assert(outputEltTL.isAddressOnly() == inputEltTL.isAddressOnly());
auto cleanup =
SGF.enterDormantTemporaryCleanup(outputEltAddr, outputEltTL);
outputEltTemp.emplace(outputEltAddr, cleanup);
}
SGFContext eltCtxt =
(outputEltTemp ? SGFContext(&outputEltTemp.value()) : SGFContext());
auto outputElt = transform(inputElt,
inputEltOrigType, inputEltSubstType,
outputEltOrigType, outputEltSubstType,
outputEltLoweredTy, eltCtxt);
// If we're not emitting to memory, remember this element for
// later assembly into a tuple.
if (!outputEltTemp) {
assert(outputElt);
assert(!inputEltTL.isAddressOnly() || !SGF.silConv.useLoweredAddresses());
outputElts.push_back(outputElt);
continue;
}
// Otherwise, make sure we emit into the slot.
auto &temp = outputEltTemp.value();
auto outputEltAddr = temp.getManagedAddress();
// That might involve storing directly.
if (!outputElt.isInContext()) {
outputElt.forwardInto(SGF, Loc, outputEltAddr.getValue());
temp.finishInitialization(SGF);
}
outputElts.push_back(outputEltAddr);
}
// Okay, disable all the individual element cleanups and collect
// the values for a potential tuple aggregate.
SmallVector<SILValue, 4> outputEltValues;
for (auto outputElt : outputElts) {
SILValue value = outputElt.forward(SGF);
if (!outputAddr) outputEltValues.push_back(value);
}
// If we're emitting to an address, just manage that.
if (outputAddr)
return SGF.manageBufferForExprResult(outputAddr, outputTL, ctxt);
// Otherwise, assemble the tuple value and manage that.
auto outputTuple =
SGF.B.createTuple(Loc, outputLoweredTy, outputEltValues);
return SGF.emitManagedRValueWithCleanup(outputTuple, outputTL);
}
void SILGenFunction::collectThunkParams(
SILLocation loc, SmallVectorImpl<ManagedValue> ¶ms,
SmallVectorImpl<ManagedValue> *indirectResults,
SmallVectorImpl<ManagedValue> *indirectErrors) {
// Add the indirect results.
for (auto resultTy : F.getConventions().getIndirectSILResultTypes(
getTypeExpansionContext())) {
auto paramTy = F.mapTypeIntoContext(resultTy);
// Lower result parameters in the context of the function: opaque result
// types will be lowered to their underlying type if allowed by resilience.
auto inContextParamTy = F.getLoweredType(paramTy.getASTType())
.getCategoryType(paramTy.getCategory());
SILArgument *arg = F.begin()->createFunctionArgument(inContextParamTy);
if (indirectResults)
indirectResults->push_back(ManagedValue::forLValue(arg));
}
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);
if (indirectErrors)
indirectErrors->push_back(ManagedValue::forLValue(arg));
IndirectErrorResult = arg;
}
// Add the parameters.
auto paramTypes = F.getLoweredFunctionType()->getParameters();
for (auto param : paramTypes) {
auto paramTy = F.mapTypeIntoContext(
F.getConventions().getSILType(param, getTypeExpansionContext()));
// Lower parameters in the context of the function: opaque result types will
// be lowered to their underlying type if allowed by resilience.
auto inContextParamTy = F.getLoweredType(paramTy.getASTType())
.getCategoryType(paramTy.getCategory());
params.push_back(B.createInputFunctionArgument(inContextParamTy, loc));
}
}
/// If the inner function we are calling (with type \c fnType) from the thunk
/// created by \c SGF requires an indirect error argument, returns that
/// argument.
static std::optional<SILValue>
emitThunkIndirectErrorArgument(SILGenFunction &SGF, SILLocation loc,
CanSILFunctionType fnType) {
// If the function we're calling has an indirect error result, create an
// argument for it.
auto innerError = fnType->getOptionalErrorResult();
if (!innerError || innerError->getConvention() != ResultConvention::Indirect)
return std::nullopt;
// If the type of the indirect error is the same for both the inner
// function and the thunk, so we can re-use the indirect error slot.
auto loweredErrorResultType = SGF.getSILType(*innerError, fnType);
if (SGF.IndirectErrorResult &&
SGF.IndirectErrorResult->getType().getObjectType()
== loweredErrorResultType) {
return SGF.IndirectErrorResult;
}
// The type of the indirect error in the inner function differs from
// that of the thunk, or the thunk has a direct error, so allocate a
// stack location for the inner indirect error.
SILValue innerIndirectErrorAddr =
SGF.B.createAllocStack(loc, loweredErrorResultType);
SGF.enterDeallocStackCleanup(innerIndirectErrorAddr);
return innerIndirectErrorAddr;
}
namespace {
class TranslateIndirect : public Cleanup {
AbstractionPattern InputOrigType, OutputOrigType;
CanType InputSubstType, OutputSubstType;
SILValue Input, Output;
public:
TranslateIndirect(AbstractionPattern inputOrigType, CanType inputSubstType,
AbstractionPattern outputOrigType, CanType outputSubstType,
SILValue input, SILValue output)
: InputOrigType(inputOrigType), OutputOrigType(outputOrigType),
InputSubstType(inputSubstType), OutputSubstType(outputSubstType),
Input(input), Output(output) {
assert(input->getType().isAddress());
assert(output->getType().isAddress());
}
void emit(SILGenFunction &SGF, CleanupLocation loc,
ForUnwind_t forUnwind) override {
FullExpr scope(SGF.Cleanups, loc);
// Re-assert ownership of the input value.
auto inputMV = SGF.emitManagedBufferWithCleanup(Input);
// Set up an initialization of the output buffer.
auto &outputTL = SGF.getTypeLowering(Output->getType());
auto outputInit = SGF.useBufferAsTemporary(Output, outputTL);
// Transform into the output buffer.
auto mv = SGF.emitTransformedValue(loc, inputMV,
InputOrigType, InputSubstType,
OutputOrigType, OutputSubstType,
Output->getType().getObjectType(),
SGFContext(outputInit.get()));
if (!mv.isInContext())
mv.ensurePlusOne(SGF, loc).forwardInto(SGF, loc, outputInit.get());
// Disable the cleanup; we've kept our promise to leave the inout
// initialized.
outputInit->getManagedAddress().forward(SGF);
}
void dump(SILGenFunction &SGF) const override {
llvm::errs() << "TranslateIndirect("
<< InputOrigType << ", " << InputSubstType << ", "
<< OutputOrigType << ", " << OutputSubstType << ", "
<< Output << ", " << Input << ")\n";
}
};
template <class Expander>
class OuterPackArgGenerator {
Expander &TheExpander;
public:
using reference = ManagedValue;
OuterPackArgGenerator(Expander &expander) : TheExpander(expander) {}
reference claimNext() {