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fuchsia / third_party / swift / 71a72524247bb050f1d9d9eb69085c221ea6e61a / . / lib / IRGen / GenProto.cpp
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//===--- GenProto.cpp - Swift IR Generation for Protocols -----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements IR generation for protocols in Swift.
//
// Protocols serve two masters: generic algorithms and existential
// types. In either case, the size and structure of a type is opaque
// to the code manipulating a value. Local values of the type must
// be stored in fixed-size buffers (which can overflow to use heap
// allocation), and basic operations on the type must be dynamically
// delegated to a collection of information that "witnesses" the
// truth that a particular type implements the protocol.
//
// In the comments throughout this file, three type names are used:
// 'B' is the type of a fixed-size buffer
// 'T' is the type which implements a protocol
// 'W' is the type of a witness to the protocol
//
//===----------------------------------------------------------------------===//
#include "swift/AST/ASTContext.h"
#include "swift/AST/CanTypeVisitor.h"
#include "swift/AST/Types.h"
#include "swift/AST/Decl.h"
#include "swift/AST/IRGenOptions.h"
#include "swift/AST/SubstitutionMap.h"
#include "swift/ClangImporter/ClangModule.h"
#include "swift/IRGen/Linking.h"
#include "swift/SIL/SILDeclRef.h"
#include "swift/SIL/SILModule.h"
#include "swift/SIL/SILValue.h"
#include "swift/SIL/SILWitnessVisitor.h"
#include "swift/SIL/TypeLowering.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
#include "CallEmission.h"
#include "ConstantBuilder.h"
#include "EnumPayload.h"
#include "Explosion.h"
#include "FixedTypeInfo.h"
#include "Fulfillment.h"
#include "GenArchetype.h"
#include "GenClass.h"
#include "GenEnum.h"
#include "GenHeap.h"
#include "GenMeta.h"
#include "GenOpaque.h"
#include "GenPoly.h"
#include "GenType.h"
#include "GenericRequirement.h"
#include "IRGenDebugInfo.h"
#include "IRGenFunction.h"
#include "IRGenModule.h"
#include "MetadataPath.h"
#include "NecessaryBindings.h"
#include "ProtocolInfo.h"
#include "TypeInfo.h"
#include "GenProto.h"
using namespace swift;
using namespace irgen;
namespace {
/// A class for computing how to pass arguments to a polymorphic
/// function. The subclasses of this are the places which need to
/// be updated if the convention changes.
class PolymorphicConvention {
protected:
IRGenModule &IGM;
ModuleDecl &M;
CanSILFunctionType FnType;
CanGenericSignature Generics;
std::vector<MetadataSource> Sources;
FulfillmentMap Fulfillments;
GenericSignature::ConformsToArray getConformsTo(Type t) {
return Generics->getConformsTo(t, M);
}
public:
PolymorphicConvention(IRGenModule &IGM, CanSILFunctionType fnType);
ArrayRef<MetadataSource> getSources() const { return Sources; }
void enumerateRequirements(const RequirementCallback &callback);
void enumerateUnfulfilledRequirements(const RequirementCallback &callback);
/// Returns a Fulfillment for a type parameter requirement, or
/// nullptr if it's unfulfilled.
const Fulfillment *getFulfillmentForTypeMetadata(CanType type) const;
/// Return the source of type metadata at a particular source index.
const MetadataSource &getSource(size_t SourceIndex) const {
return Sources[SourceIndex];
}
private:
void initGenerics();
void considerNewTypeSource(MetadataSource::Kind kind, unsigned paramIndex,
CanType type, IsExact_t isExact);
bool considerType(CanType type, IsExact_t isExact,
unsigned sourceIndex, MetadataPath &&path);
/// Testify to generic parameters in the Self type of a protocol
/// witness method.
void considerWitnessSelf(CanSILFunctionType fnType);
/// Testify to generic parameters in the Self type of an @objc
/// generic or protocol method.
void considerObjCGenericSelf(CanSILFunctionType fnType);
void considerParameter(SILParameterInfo param, unsigned paramIndex,
bool isSelfParameter);
void addSelfMetadataFulfillment(CanType arg);
void addSelfWitnessTableFulfillment(CanType arg, ProtocolDecl *proto);
void addPseudogenericFulfillments();
};
} // end anonymous namespace
PolymorphicConvention::PolymorphicConvention(IRGenModule &IGM,
CanSILFunctionType fnType)
: IGM(IGM), M(*IGM.getSwiftModule()), FnType(fnType) {
initGenerics();
auto rep = fnType->getRepresentation();
if (fnType->isPseudogeneric()) {
// Protocol witnesses still get Self metadata no matter what. The type
// parameters of Self are pseudogeneric, though.
if (rep == SILFunctionTypeRepresentation::WitnessMethod)
considerWitnessSelf(fnType);
addPseudogenericFulfillments();
return;
}
if (rep == SILFunctionTypeRepresentation::WitnessMethod) {
// Protocol witnesses always derive all polymorphic parameter
// information from the Self argument. We also *cannot* consider other
// arguments; doing so would potentially make the signature
// incompatible with other witnesses for the same method.
considerWitnessSelf(fnType);
} else if (rep == SILFunctionTypeRepresentation::ObjCMethod) {
// Objective-C thunks for generic methods also always derive all
// polymorphic parameter information from the Self argument.
considerObjCGenericSelf(fnType);
} else {
// We don't need to pass anything extra as long as all of the
// archetypes (and their requirements) are producible from
// arguments.
unsigned selfIndex = ~0U;
auto params = fnType->getParameters();
// Consider 'self' first.
if (fnType->hasSelfParam()) {
selfIndex = params.size() - 1;
considerParameter(params[selfIndex], selfIndex, true);
}
// Now consider the rest of the parameters.
for (auto index : indices(params)) {
if (index != selfIndex)
considerParameter(params[index], index, false);
}
}
}
void PolymorphicConvention::addPseudogenericFulfillments() {
enumerateRequirements([&](GenericRequirement reqt) {
MetadataPath path;
path.addImpossibleComponent();
unsigned sourceIndex = 0; // unimportant, since impossible
Fulfillments.addFulfillment({reqt.TypeParameter, reqt.Protocol},
sourceIndex, std::move(path));
});
}
void
irgen::enumerateGenericSignatureRequirements(CanGenericSignature signature,
const RequirementCallback &callback) {
if (!signature) return;
// Get all of the type metadata.
for (auto gp : signature->getSubstitutableParams()) {
callback({CanType(gp), nullptr});
}
// Get the protocol conformances.
for (auto &reqt : signature->getRequirements()) {
switch (reqt.getKind()) {
// Ignore these; they don't introduce extra requirements.
case RequirementKind::Superclass:
case RequirementKind::SameType:
case RequirementKind::Layout:
continue;
case RequirementKind::Conformance: {
auto type = CanType(reqt.getFirstType());
auto protocol =
cast<ProtocolType>(CanType(reqt.getSecondType()))->getDecl();
if (Lowering::TypeConverter::protocolRequiresWitnessTable(protocol)) {
callback({type, protocol});
}
continue;
}
}
llvm_unreachable("bad requirement kind");
}
}
void
PolymorphicConvention::enumerateRequirements(const RequirementCallback &callback) {
return enumerateGenericSignatureRequirements(Generics, callback);
}
void PolymorphicConvention::enumerateUnfulfilledRequirements(const RequirementCallback &callback) {
enumerateRequirements([&](GenericRequirement requirement) {
if (requirement.Protocol) {
if (!Fulfillments.getWitnessTable(requirement.TypeParameter,
requirement.Protocol)) {
callback(requirement);
}
} else {
if (!Fulfillments.getTypeMetadata(requirement.TypeParameter)) {
callback(requirement);
}
}
});
}
void PolymorphicConvention::initGenerics() {
Generics = FnType->getGenericSignature();
}
void PolymorphicConvention::considerNewTypeSource(MetadataSource::Kind kind,
unsigned paramIndex,
CanType type,
IsExact_t isExact) {
if (!Fulfillments.isInterestingTypeForFulfillments(type)) return;
// Prospectively add a source.
Sources.emplace_back(kind, paramIndex, type);
// Consider the source.
if (!considerType(type, isExact, Sources.size() - 1, MetadataPath())) {
// If it wasn't used in any fulfillments, remove it.
Sources.pop_back();
}
}
bool PolymorphicConvention::considerType(CanType type, IsExact_t isExact,
unsigned sourceIndex,
MetadataPath &&path) {
struct Callback : FulfillmentMap::InterestingKeysCallback {
PolymorphicConvention &Self;
Callback(PolymorphicConvention &self) : Self(self) {}
bool isInterestingType(CanType type) const override {
return type->isTypeParameter();
}
bool hasInterestingType(CanType type) const override {
return type->hasTypeParameter();
}
bool hasLimitedInterestingConformances(CanType type) const override {
return true;
}
GenericSignature::ConformsToArray
getInterestingConformances(CanType type) const override {
return Self.getConformsTo(type);
}
} callbacks(*this);
return Fulfillments.searchTypeMetadata(IGM, type, isExact, sourceIndex,
std::move(path), callbacks);
}
void PolymorphicConvention::considerWitnessSelf(CanSILFunctionType fnType) {
CanType selfTy = fnType->getSelfInstanceType();
// First, bind type metadata for Self.
Sources.emplace_back(MetadataSource::Kind::SelfMetadata,
MetadataSource::InvalidSourceIndex,
selfTy);
if (auto *proto = fnType->getDefaultWitnessMethodProtocol(M)) {
// The Self type is abstract, so we must pass in a witness table.
addSelfMetadataFulfillment(selfTy);
// Look at the witness table for the conformance.
Sources.emplace_back(MetadataSource::Kind::SelfWitnessTable,
MetadataSource::InvalidSourceIndex,
selfTy);
addSelfWitnessTableFulfillment(selfTy, proto);
} else {
// If the Self type is concrete, we have a witness thunk with a
// fully substituted Self type. The witness table parameter is not
// used.
considerType(selfTy, IsInexact, Sources.size() - 1, MetadataPath());
}
}
void PolymorphicConvention::considerObjCGenericSelf(CanSILFunctionType fnType) {
// If this is a static method, get the instance type.
CanType selfTy = fnType->getSelfInstanceType();
unsigned paramIndex = fnType->getParameters().size() - 1;
// Bind type metadata for Self.
Sources.emplace_back(MetadataSource::Kind::ClassPointer, paramIndex,
selfTy);
if (isa<GenericTypeParamType>(selfTy))
addSelfMetadataFulfillment(selfTy);
else
considerType(selfTy, IsInexact,
Sources.size() - 1, MetadataPath());
}
void PolymorphicConvention::considerParameter(SILParameterInfo param,
unsigned paramIndex,
bool isSelfParameter) {
auto type = param.getType();
switch (param.getConvention()) {
// Indirect parameters do give us a value we can use, but right now
// we don't bother, for no good reason. But if this is 'self',
// consider passing an extra metatype.
case ParameterConvention::Indirect_In:
case ParameterConvention::Indirect_In_Constant:
case ParameterConvention::Indirect_In_Guaranteed:
case ParameterConvention::Indirect_Inout:
case ParameterConvention::Indirect_InoutAliasable:
if (!isSelfParameter) return;
if (type->getNominalOrBoundGenericNominal()) {
considerNewTypeSource(MetadataSource::Kind::GenericLValueMetadata,
paramIndex, type, IsExact);
}
return;
case ParameterConvention::Direct_Owned:
case ParameterConvention::Direct_Unowned:
case ParameterConvention::Direct_Guaranteed:
// Classes are sources of metadata.
if (type->getClassOrBoundGenericClass()) {
considerNewTypeSource(MetadataSource::Kind::ClassPointer,
paramIndex, type, IsInexact);
return;
}
// Thick metatypes are sources of metadata.
if (auto metatypeTy = dyn_cast<MetatypeType>(type)) {
if (metatypeTy->getRepresentation() != MetatypeRepresentation::Thick)
return;
// Thick metatypes for Objective-C parameterized classes are not
// sources of metadata.
CanType objTy = metatypeTy.getInstanceType();
if (auto classDecl = objTy->getClassOrBoundGenericClass())
if (classDecl->usesObjCGenericsModel())
return;
considerNewTypeSource(MetadataSource::Kind::Metadata,
paramIndex, objTy, IsInexact);
return;
}
return;
}
llvm_unreachable("bad parameter convention");
}
void PolymorphicConvention::addSelfMetadataFulfillment(CanType arg) {
unsigned source = Sources.size() - 1;
Fulfillments.addFulfillment({arg, nullptr}, source, MetadataPath());
}
void PolymorphicConvention::addSelfWitnessTableFulfillment(CanType arg, ProtocolDecl *proto) {
unsigned source = Sources.size() - 1;
Fulfillments.addFulfillment({arg, proto}, source, MetadataPath());
}
const Fulfillment *
PolymorphicConvention::getFulfillmentForTypeMetadata(CanType type) const {
return Fulfillments.getTypeMetadata(type);
}
void irgen::enumerateGenericParamFulfillments(IRGenModule &IGM,
CanSILFunctionType fnType,
GenericParamFulfillmentCallback callback) {
PolymorphicConvention convention(IGM, fnType);
// Check if any requirements were fulfilled by metadata stored inside a
// captured value.
auto generics = fnType->getGenericSignature();
for (auto genericParam : generics->getGenericParams()) {
auto genericParamType = genericParam->getCanonicalType();
auto fulfillment
= convention.getFulfillmentForTypeMetadata(genericParamType);
if (fulfillment == nullptr)
continue;
auto &source = convention.getSource(fulfillment->SourceIndex);
callback(genericParamType, source, fulfillment->Path);
}
}
namespace {
/// A class for binding type parameters of a generic function.
class EmitPolymorphicParameters : public PolymorphicConvention {
IRGenFunction &IGF;
SILFunction &Fn;
public:
EmitPolymorphicParameters(IRGenFunction &IGF, SILFunction &Fn);
void emit(Explosion &in, WitnessMetadata *witnessMetadata,
const GetParameterFn &getParameter);
private:
CanType getTypeInContext(CanType type) const;
CanType getArgTypeInContext(unsigned paramIndex) const;
/// Fulfill local type data from any extra information associated with
/// the given source.
void bindExtraSource(const MetadataSource &source, Explosion &in,
WitnessMetadata *witnessMetadata);
void bindParameterSources(const GetParameterFn &getParameter);
void bindParameterSource(SILParameterInfo param, unsigned paramIndex,
const GetParameterFn &getParameter) ;
// Did the convention decide that the parameter at the given index
// was a class-pointer source?
bool isClassPointerSource(unsigned paramIndex);
};
} // end anonymous namespace
EmitPolymorphicParameters::EmitPolymorphicParameters(IRGenFunction &IGF,
SILFunction &Fn)
: PolymorphicConvention(IGF.IGM, Fn.getLoweredFunctionType()),
IGF(IGF), Fn(Fn) {}
CanType EmitPolymorphicParameters::getTypeInContext(CanType type) const {
return Fn.mapTypeIntoContext(type)->getCanonicalType();
}
CanType EmitPolymorphicParameters::getArgTypeInContext(unsigned paramIndex) const {
return getTypeInContext(FnType->getParameters()[paramIndex].getType());
}
void EmitPolymorphicParameters::bindExtraSource(const MetadataSource &source,
Explosion &in,
WitnessMetadata *witnessMetadata) {
switch (source.getKind()) {
case MetadataSource::Kind::Metadata:
case MetadataSource::Kind::ClassPointer:
// Ignore these, we'll get to them when we walk the parameter list.
return;
case MetadataSource::Kind::GenericLValueMetadata: {
CanType argTy = getArgTypeInContext(source.getParamIndex());
llvm::Value *metadata = in.claimNext();
setTypeMetadataName(IGF.IGM, metadata, argTy);
IGF.bindLocalTypeDataFromTypeMetadata(argTy, IsExact, metadata);
return;
}
case MetadataSource::Kind::SelfMetadata: {
assert(witnessMetadata && "no metadata for witness method");
llvm::Value *metadata = witnessMetadata->SelfMetadata;
assert(metadata && "no Self metadata for witness method");
// Mark this as the cached metatype for Self.
auto selfTy = FnType->getSelfInstanceType();
CanType argTy = getTypeInContext(selfTy);
setTypeMetadataName(IGF.IGM, metadata, argTy);
auto *CD = selfTy.getClassOrBoundGenericClass();
// The self metadata here corresponds to the conforming type.
// For an inheritable conformance, that may be a subclass of the static
// type, and so the self metadata will be inexact. Currently, all
// conformances are inheritable.
IGF.bindLocalTypeDataFromTypeMetadata(
argTy, (!CD || CD->isFinal()) ? IsExact : IsInexact, metadata);
return;
}
case MetadataSource::Kind::SelfWitnessTable: {
assert(witnessMetadata && "no metadata for witness method");
llvm::Value *wtable = witnessMetadata->SelfWitnessTable;
assert(wtable && "no Self witness table for witness method");
// Mark this as the cached witness table for Self.
if (auto *proto = FnType->getDefaultWitnessMethodProtocol(M)) {
auto selfTy = FnType->getSelfInstanceType();
CanType argTy = getTypeInContext(selfTy);
auto archetype = cast<ArchetypeType>(argTy);
setProtocolWitnessTableName(IGF.IGM, wtable, argTy, proto);
IGF.setUnscopedLocalTypeData(archetype,
LocalTypeDataKind::forAbstractProtocolWitnessTable(proto),
wtable);
}
return;
}
}
llvm_unreachable("bad source kind!");
}
void EmitPolymorphicParameters::bindParameterSources(const GetParameterFn &getParameter) {
auto params = FnType->getParameters();
// Bind things from 'self' preferentially.
if (FnType->hasSelfParam()) {
bindParameterSource(params.back(), params.size() - 1, getParameter);
params = params.drop_back();
}
for (unsigned index : indices(params)) {
bindParameterSource(params[index], index, getParameter);
}
}
void EmitPolymorphicParameters::bindParameterSource(SILParameterInfo param, unsigned paramIndex,
const GetParameterFn &getParameter) {
// Ignore indirect parameters for now. This is potentially dumb.
if (IGF.IGM.silConv.isSILIndirect(param))
return;
CanType paramType = getArgTypeInContext(paramIndex);
// If the parameter is a thick metatype, bind it directly.
// TODO: objc metatypes?
if (auto metatype = dyn_cast<MetatypeType>(paramType)) {
if (metatype->getRepresentation() == MetatypeRepresentation::Thick) {
paramType = metatype.getInstanceType();
llvm::Value *metadata = getParameter(paramIndex);
IGF.bindLocalTypeDataFromTypeMetadata(paramType, IsInexact, metadata);
}
return;
}
// If the parameter is a class type, we only consider it interesting
// if the convention decided it was actually a source.
// TODO: if the class pointer is guaranteed, we can do this lazily,
// at which point it might make sense to do it for a wider selection
// of types.
if (isClassPointerSource(paramIndex)) {
llvm::Value *instanceRef = getParameter(paramIndex);
SILType instanceType = SILType::getPrimitiveObjectType(paramType);
llvm::Value *metadata =
emitDynamicTypeOfHeapObject(IGF, instanceRef, instanceType);
IGF.bindLocalTypeDataFromTypeMetadata(paramType, IsInexact, metadata);
return;
}
}
bool EmitPolymorphicParameters::isClassPointerSource(unsigned paramIndex) {
for (auto &source : getSources()) {
if (source.getKind() == MetadataSource::Kind::ClassPointer &&
source.getParamIndex() == paramIndex) {
return true;
}
}
return false;
}
namespace {
/// A class for binding type parameters of a generic function.
class BindPolymorphicParameter : public PolymorphicConvention {
IRGenFunction &IGF;
CanSILFunctionType &SubstFnType;
public:
BindPolymorphicParameter(IRGenFunction &IGF, CanSILFunctionType &origFnType,
CanSILFunctionType &SubstFnType)
: PolymorphicConvention(IGF.IGM, origFnType), IGF(IGF),
SubstFnType(SubstFnType) {}
void emit(Explosion &in, unsigned paramIndex);
private:
// Did the convention decide that the parameter at the given index
// was a class-pointer source?
bool isClassPointerSource(unsigned paramIndex);
};
} // end anonymous namespace
bool BindPolymorphicParameter::isClassPointerSource(unsigned paramIndex) {
for (auto &source : getSources()) {
if (source.getKind() == MetadataSource::Kind::ClassPointer &&
source.getParamIndex() == paramIndex) {
return true;
}
}
return false;
}
void BindPolymorphicParameter::emit(Explosion &nativeParam, unsigned paramIndex) {
if (!isClassPointerSource(paramIndex))
return;
assert(nativeParam.size() == 1);
auto paramType = SubstFnType->getParameters()[paramIndex].getType();
llvm::Value *instanceRef = nativeParam.getAll()[0];
SILType instanceType = SILType::getPrimitiveObjectType(paramType);
llvm::Value *metadata =
emitDynamicTypeOfHeapObject(IGF, instanceRef, instanceType);
IGF.bindLocalTypeDataFromTypeMetadata(paramType, IsInexact, metadata);
}
void irgen::bindPolymorphicParameter(IRGenFunction &IGF,
CanSILFunctionType &OrigFnType,
CanSILFunctionType &SubstFnType,
Explosion &nativeParam,
unsigned paramIndex) {
BindPolymorphicParameter(IGF, OrigFnType, SubstFnType)
.emit(nativeParam, paramIndex);
}
static bool shouldSetName(IRGenModule &IGM, llvm::Value *value, CanType type) {
// If value names are globally disabled, honor that.
if (!IGM.EnableValueNames) return false;
// Suppress value names for values with opened existentials.
if (type->hasOpenedExistential()) return false;
// If the value already has a name, honor that.
if (value->hasName()) return false;
// Only do this for local values.
return (isa<llvm::Instruction>(value) || isa<llvm::Argument>(value));
}
void irgen::setTypeMetadataName(IRGenModule &IGM, llvm::Value *metadata,
CanType type) {
if (!shouldSetName(IGM, metadata, type)) return;
SmallString<128> name; {
llvm::raw_svector_ostream out(name);
type.print(out);
}
metadata->setName(type->getString());
}
void irgen::setProtocolWitnessTableName(IRGenModule &IGM, llvm::Value *wtable,
CanType type,
ProtocolDecl *requirement) {
if (!shouldSetName(IGM, wtable, type)) return;
SmallString<128> name; {
llvm::raw_svector_ostream out(name);
type.print(out);
out << '.' << requirement->getNameStr();
}
wtable->setName(name);
}
namespace {
/// A concrete witness table, together with its known layout.
class WitnessTable {
llvm::Value *Table;
const ProtocolInfo &Info;
public:
WitnessTable(llvm::Value *wtable, const ProtocolInfo &info)
: Table(wtable), Info(info) {}
llvm::Value *getTable() const { return Table; }
const ProtocolInfo &getInfo() const { return Info; }
};
/// A class which lays out a witness table in the abstract.
class WitnessTableLayout : public SILWitnessVisitor<WitnessTableLayout> {
SmallVector<WitnessTableEntry, 16> Entries;
public:
/// The next witness is an out-of-line base protocol.
void addOutOfLineBaseProtocol(ProtocolDecl *baseProto) {
Entries.push_back(WitnessTableEntry::forOutOfLineBase(baseProto));
}
void addMethod(SILDeclRef func) {
auto decl = cast<AbstractFunctionDecl>(func.getDecl());
Entries.push_back(WitnessTableEntry::forFunction(decl));
}
void addPlaceholder(MissingMemberDecl *placeholder) {
for (auto i : range(placeholder->getNumberOfVTableEntries())) {
(void)i;
Entries.push_back(WitnessTableEntry());
}
}
void addAssociatedType(AssociatedType requirement) {
Entries.push_back(WitnessTableEntry::forAssociatedType(requirement));
}
void addAssociatedConformance(const AssociatedConformance &req) {
Entries.push_back(WitnessTableEntry::forAssociatedConformance(req));
}
ArrayRef<WitnessTableEntry> getEntries() const { return Entries; }
};
/// A path through a protocol hierarchy.
class ProtocolPath {
IRGenModule &IGM;
/// The destination protocol.
ProtocolDecl *Dest;
/// The path from the selected origin down to the destination
/// protocol.
SmallVector<WitnessIndex, 8> ReversePath;
/// The origin index to use.
unsigned OriginIndex;
/// The best path length we found.
unsigned BestPathLength;
public:
/// Find a path from the given set of origins to the destination
/// protocol.
///
/// T needs to provide a couple of member functions:
/// ProtocolDecl *getProtocol() const;
/// const ProtocolInfo &getInfo() const;
template <class T>
ProtocolPath(IRGenModule &IGM, ArrayRef<T> origins, ProtocolDecl *dest)
: IGM(IGM), Dest(dest), BestPathLength(~0U) {
// Consider each of the origins in turn, breaking out if any of
// them yields a zero-length path.
for (unsigned i = 0, e = origins.size(); i != e; ++i) {
auto &origin = origins[i];
if (considerOrigin(origin.getProtocol(), origin.getInfo(), i))
break;
}
// Sanity check that we actually found a path at all.
assert(BestPathLength != ~0U);
assert(BestPathLength == ReversePath.size());
}
/// Returns the index of the origin protocol we chose.
unsigned getOriginIndex() const { return OriginIndex; }
/// Apply the path to the given witness table.
llvm::Value *apply(IRGenFunction &IGF, llvm::Value *wtable) const {
for (unsigned i = ReversePath.size(); i != 0; --i) {
wtable = emitInvariantLoadOfOpaqueWitness(IGF, wtable,
ReversePath[i-1]);
wtable = IGF.Builder.CreateBitCast(wtable, IGF.IGM.WitnessTablePtrTy);
}
return wtable;
}
private:
/// Consider paths starting from a new origin protocol.
/// Returns true if there's no point in considering other origins.
bool considerOrigin(ProtocolDecl *origin, const ProtocolInfo &originInfo,
unsigned originIndex) {
assert(BestPathLength != 0);
// If the origin *is* the destination, we can stop here.
if (origin == Dest) {
OriginIndex = originIndex;
BestPathLength = 0;
ReversePath.clear();
return true;
}
// Otherwise, if the origin gives rise to a better path, that's
// also cool.
if (findBetterPath(origin, originInfo, 0)) {
OriginIndex = originIndex;
return BestPathLength == 0;
}
return false;
}
/// Consider paths starting at the given protocol.
bool findBetterPath(ProtocolDecl *proto, const ProtocolInfo &protoInfo,
unsigned lengthSoFar) {
assert(lengthSoFar < BestPathLength);
assert(proto != Dest);
// Keep track of whether we found a better path than the
// previous best.
bool foundBetter = false;
for (auto base : proto->getInheritedProtocols()) {
// ObjC protocols do not have witnesses.
if (!Lowering::TypeConverter::protocolRequiresWitnessTable(base))
continue;
auto baseIndex = protoInfo.getBaseIndex(base);
// Compute the length down to this base.
unsigned lengthToBase = lengthSoFar;
if (!baseIndex.isPrefix()) {
lengthToBase++;
// Don't consider this path if we reach a length that can't
// possibly be better than the best so far.
if (lengthToBase == BestPathLength) continue;
}
assert(lengthToBase < BestPathLength);
// If this base *is* the destination, go ahead and start
// building the path into ReversePath.
if (base == Dest) {
// Reset the collected best-path information.
BestPathLength = lengthToBase;
ReversePath.clear();
// Otherwise, if there isn't a better path through this base,
// don't accumulate anything in the path.
} else if (!findBetterPath(base, IGM.getProtocolInfo(base),
lengthToBase)) {
continue;
}
// Okay, we've found a better path, and ReversePath contains a
// path leading from base to Dest.
assert(BestPathLength >= lengthToBase);
foundBetter = true;
// Add the link from proto to base if necessary.
if (!baseIndex.isPrefix()) {
ReversePath.push_back(baseIndex);
// If it isn't necessary, then we might be able to
// short-circuit considering the bases of this protocol.
} else {
if (lengthSoFar == BestPathLength)
return true;
}
}
return foundBetter;
}
};
} // end anonymous namespace
/// Return true if the witness table requires runtime instantiation to
/// handle resiliently-added requirements with default implementations.
static bool isResilientConformance(const NormalProtocolConformance *conformance) {
// If the protocol is not resilient, the conformance is not resilient
// either.
if (conformance->getProtocol()->hasFixedLayout())
return false;
// If the protocol is in the same module as the conformance, we're
// not resilient.
if (conformance->getDeclContext()->getParentModule()
== conformance->getProtocol()->getParentModule())
return false;
// We have a resilient conformance.
return true;
}
/// Is there anything about the given conformance that requires witness
/// tables to be dependently-generated?
static bool isDependentConformance(IRGenModule &IGM,
const NormalProtocolConformance *conformance,
ResilienceExpansion expansion) {
// If the conformance is resilient, this is always true.
if (isResilientConformance(conformance))
return true;
// Check whether any of the inherited conformances are dependent.
for (auto inherited : conformance->getProtocol()->getInheritedProtocols()) {
if (isDependentConformance(IGM,
conformance->getInheritedConformance(inherited)
->getRootNormalConformance(),
expansion))
return true;
}
// If the conforming type isn't dependent, the below check is never true.
if (!conformance->getDeclContext()->isGenericContext())
return false;
// Check whether any of the associated types are dependent.
if (conformance->forEachTypeWitness(nullptr,
[&](AssociatedTypeDecl *requirement, Type type,
TypeDecl *explicitDecl) -> bool {
// RESILIENCE: this could be an opaque conformance
return type->hasArchetype();
})) {
return true;
}
return false;
}
/// Detail about how an object conforms to a protocol.
class irgen::ConformanceInfo {
friend ProtocolInfo;
public:
virtual ~ConformanceInfo() {}
virtual llvm::Value *getTable(IRGenFunction &IGF,
CanType conformingType,
llvm::Value **conformingMetadataCache) const = 0;
/// Try to get this table as a constant pointer. This might just
/// not be supportable at all.
virtual llvm::Constant *tryGetConstantTable(IRGenModule &IGM,
CanType conformingType) const = 0;
};
static llvm::Value *
emitWitnessTableAccessorCall(IRGenFunction &IGF,
const NormalProtocolConformance *conformance,
CanType conformingType,
llvm::Value **srcMetadataCache) {
auto accessor =
IGF.IGM.getAddrOfWitnessTableAccessFunction(conformance, NotForDefinition);
// If the conformance is generic, the accessor takes the metatype
// as an argument.
llvm::CallInst *call;
if (conformance->getDeclContext()->isGenericContext()) {
// Emit the source metadata if we haven't yet.
if (!*srcMetadataCache) {
*srcMetadataCache = IGF.emitTypeMetadataRef(conformingType);
}
call = IGF.Builder.CreateCall(accessor, {*srcMetadataCache});
} else {
call = IGF.Builder.CreateCall(accessor, {});
}
call->setCallingConv(IGF.IGM.DefaultCC);
call->setDoesNotAccessMemory();
call->setDoesNotThrow();
return call;
}
/// Fetch the lazy access function for the given conformance of the
/// given type.
static llvm::Function *
getWitnessTableLazyAccessFunction(IRGenModule &IGM,
const NormalProtocolConformance *conformance,
CanType conformingType) {
assert(!conformingType->hasArchetype());
llvm::Function *accessor =
IGM.getAddrOfWitnessTableLazyAccessFunction(conformance, conformingType,
ForDefinition);
// If we're not supposed to define the accessor, or if we already
// have defined it, just return the pointer.
if (!accessor->empty())
return accessor;
if (IGM.getOptions().OptimizeForSize)
accessor->addFnAttr(llvm::Attribute::NoInline);
// Okay, define the accessor.
auto cacheVariable = cast<llvm::GlobalVariable>(
IGM.getAddrOfWitnessTableLazyCacheVariable(conformance, conformingType,
ForDefinition));
emitLazyCacheAccessFunction(IGM, accessor, cacheVariable,
[&](IRGenFunction &IGF) -> llvm::Value* {
llvm::Value *conformingMetadataCache = nullptr;
return emitWitnessTableAccessorCall(IGF, conformance, conformingType,
&conformingMetadataCache);
});
return accessor;
}
namespace {
/// Conformance info for a witness table that can be directly generated.
class DirectConformanceInfo : public ConformanceInfo {
friend ProtocolInfo;
const NormalProtocolConformance *RootConformance;
public:
DirectConformanceInfo(const NormalProtocolConformance *C)
: RootConformance(C) {}
llvm::Value *getTable(IRGenFunction &IGF, CanType conformingType,
llvm::Value **conformingMetadataCache) const override {
return IGF.IGM.getAddrOfWitnessTable(RootConformance);
}
llvm::Constant *tryGetConstantTable(IRGenModule &IGM,
CanType conformingType) const override {
return IGM.getAddrOfWitnessTable(RootConformance);
}
};
/// Conformance info for a witness table that is (or may be) dependent.
class AccessorConformanceInfo : public ConformanceInfo {
friend ProtocolInfo;
const NormalProtocolConformance *Conformance;
public:
AccessorConformanceInfo(const NormalProtocolConformance *C)
: Conformance(C) {}
llvm::Value *getTable(IRGenFunction &IGF, CanType type,
llvm::Value **typeMetadataCache) const override {
// If we're looking up a dependent type, we can't cache the result.
if (type->hasArchetype()) {
return emitWitnessTableAccessorCall(IGF, Conformance, type,
typeMetadataCache);
}
// Otherwise, call a lazy-cache function.
auto accessor =
getWitnessTableLazyAccessFunction(IGF.IGM, Conformance, type);
llvm::CallInst *call = IGF.Builder.CreateCall(accessor, {});
call->setCallingConv(IGF.IGM.DefaultCC);
call->setDoesNotAccessMemory();
call->setDoesNotThrow();
return call;
}
llvm::Constant *tryGetConstantTable(IRGenModule &IGM,
CanType conformingType) const override {
return nullptr;
}
};
/// A class which lays out a specific conformance to a protocol.
class WitnessTableBuilder : public SILWitnessVisitor<WitnessTableBuilder> {
IRGenModule &IGM;
ConstantArrayBuilder &Table;
unsigned TableSize = ~0U; // will get overwritten unconditionally
CanType ConcreteType;
const NormalProtocolConformance &Conformance;
ArrayRef<SILWitnessTable::Entry> SILEntries;
const ProtocolInfo &PI;
Optional<FulfillmentMap> Fulfillments;
SmallVector<std::pair<size_t, const ConformanceInfo *>, 4>
SpecializedBaseConformances;
// Metadata caches are stored at negative offsets.
unsigned NextCacheIndex = 0;
bool RequiresSpecialization = false;
public:
WitnessTableBuilder(IRGenModule &IGM,
ConstantArrayBuilder &table,
SILWitnessTable *SILWT)
: IGM(IGM), Table(table),
ConcreteType(SILWT->getConformance()->getType()->getCanonicalType()),
Conformance(*SILWT->getConformance()),
SILEntries(SILWT->getEntries()),
PI(IGM.getProtocolInfo(SILWT->getConformance()->getProtocol()))
{
// TODO: in conditional conformances, allocate space for the assumed
// conformances here.
// If the conformance is resilient, we require runtime instantiation.
if (isResilientConformance(&Conformance))
RequiresSpecialization = true;
}
/// The top-level entry point.
void build();
/// Create the access function.
void buildAccessFunction(llvm::Constant *wtable);
/// A base protocol is witnessed by a pointer to the conformance
/// of this type to that protocol.
void addOutOfLineBaseProtocol(ProtocolDecl *baseProto) {
#ifndef NDEBUG
auto &entry = SILEntries.front();
assert(entry.getKind() == SILWitnessTable::BaseProtocol
&& "sil witness table does not match protocol");
assert(entry.getBaseProtocolWitness().Requirement == baseProto
&& "sil witness table does not match protocol");
auto piIndex = PI.getBaseIndex(baseProto);
assert(piIndex.getValue() == Table.size()
&& "offset doesn't match ProtocolInfo layout");
#endif
SILEntries = SILEntries.slice(1);
// TODO: Use the witness entry instead of falling through here.
// Look for a protocol type info.
const ProtocolInfo &basePI = IGM.getProtocolInfo(baseProto);
const ProtocolConformance *astConf
= Conformance.getInheritedConformance(baseProto);
const ConformanceInfo &conf =
basePI.getConformance(IGM, baseProto, astConf);
// If we can emit the base witness table as a constant, do so.
llvm::Constant *baseWitness = conf.tryGetConstantTable(IGM, ConcreteType);
if (baseWitness) {
Table.addBitCast(baseWitness, IGM.Int8PtrTy);
return;
}
// Otherwise, we'll need to derive it at instantiation time.
RequiresSpecialization = true;
SpecializedBaseConformances.push_back({Table.size(), &conf});
Table.addNullPointer(IGM.Int8PtrTy);
}
void addMethod(SILDeclRef requirement) {
auto &entry = SILEntries.front();
SILEntries = SILEntries.slice(1);
// Handle missing optional requirements.
if (entry.getKind() == SILWitnessTable::MissingOptional) {
Table.addNullPointer(IGM.Int8PtrTy);
return;
}
#ifndef NDEBUG
assert(entry.getKind() == SILWitnessTable::Method
&& "sil witness table does not match protocol");
assert(entry.getMethodWitness().Requirement == requirement
&& "sil witness table does not match protocol");
auto piIndex =
PI.getFunctionIndex(cast<AbstractFunctionDecl>(requirement.getDecl()));
assert(piIndex.getValue() == Table.size()
&& "offset doesn't match ProtocolInfo layout");
#endif
SILFunction *Func = entry.getMethodWitness().Witness;
llvm::Constant *witness = nullptr;
if (Func) {
witness = IGM.getAddrOfSILFunction(Func, NotForDefinition);
} else {
// The method is removed by dead method elimination.
// It should be never called. We add a pointer to an error function.
witness = IGM.getDeletedMethodErrorFn();
}
Table.addBitCast(witness, IGM.Int8PtrTy);
return;
}
void addPlaceholder(MissingMemberDecl *placeholder) {
llvm_unreachable("cannot emit a witness table with placeholders in it");
}
void addAssociatedType(AssociatedType requirement) {
#ifndef NDEBUG
auto &entry = SILEntries.front();
assert(entry.getKind() == SILWitnessTable::AssociatedType
&& "sil witness table does not match protocol");
assert(entry.getAssociatedTypeWitness().Requirement
== requirement.getAssociation()
&& "sil witness table does not match protocol");
auto piIndex = PI.getAssociatedTypeIndex(requirement);
assert(piIndex.getValue() == Table.size()
&& "offset doesn't match ProtocolInfo layout");
#endif
SILEntries = SILEntries.slice(1);
CanType associate =
Conformance.getTypeWitness(requirement.getAssociation(), nullptr)
->getCanonicalType();
// This type will be expressed in terms of the archetypes
// of the conforming context.
assert(!associate->hasTypeParameter());
llvm::Constant *metadataAccessFunction =
getAssociatedTypeMetadataAccessFunction(requirement, associate);
Table.addBitCast(metadataAccessFunction, IGM.Int8PtrTy);
}
void addAssociatedConformance(AssociatedConformance requirement) {
// FIXME: Add static witness tables for type conformances.
CanType associate =
Conformance.getAssociatedType(requirement.getAssociation())
->getCanonicalType();
assert(!associate->hasTypeParameter());
ProtocolConformanceRef associatedConformance =
Conformance.getAssociatedConformance(requirement.getAssociation(),
requirement.getAssociatedRequirement());
#ifndef NDEBUG
auto &entry = SILEntries.front();
(void)entry;
assert(entry.getKind() == SILWitnessTable::AssociatedTypeProtocol
&& "sil witness table does not match protocol");
auto associatedWitness = entry.getAssociatedTypeProtocolWitness();
assert(associatedWitness.Requirement == requirement.getAssociation()
&& "sil witness table does not match protocol");
assert(associatedWitness.Protocol ==
requirement.getAssociatedRequirement()
&& "sil witness table does not match protocol");
auto piIndex = PI.getAssociatedConformanceIndex(requirement);
assert(piIndex.getValue() == Table.size()
&& "offset doesn't match ProtocolInfo layout");
#endif
SILEntries = SILEntries.slice(1);
llvm::Constant *wtableAccessFunction =
getAssociatedTypeWitnessTableAccessFunction(requirement,
associate,
associatedConformance);
Table.addBitCast(wtableAccessFunction, IGM.Int8PtrTy);
}
private:
llvm::Constant *buildInstantiationFunction();
llvm::Constant *
getAssociatedTypeMetadataAccessFunction(AssociatedType requirement,
CanType associatedType);
llvm::Constant *
getAssociatedTypeWitnessTableAccessFunction(
AssociatedConformance requirement,
CanType associatedType,
ProtocolConformanceRef conformance);
void emitReturnOfCheckedLoadFromCache(IRGenFunction &IGF,
Address destTable,
llvm::Value *selfMetadata,
llvm::function_ref<llvm::Value*()> body);
/// Allocate another word of private data storage in the conformance table.
unsigned getNextCacheIndex() {
RequiresSpecialization = true;
return NextCacheIndex++;
}
const FulfillmentMap &getFulfillmentMap() {
if (Fulfillments) return *Fulfillments;
Fulfillments.emplace();
if (ConcreteType->hasArchetype()) {
struct Callback : FulfillmentMap::InterestingKeysCallback {
bool isInterestingType(CanType type) const override {
return isa<ArchetypeType>(type);
}
bool hasInterestingType(CanType type) const override {
return type->hasArchetype();
}
bool hasLimitedInterestingConformances(CanType type) const override {
return false;
}
GenericSignature::ConformsToArray
getInterestingConformances(CanType type) const override {
llvm_unreachable("no limits");
}
} callback;
Fulfillments->searchTypeMetadata(IGM, ConcreteType, IsExact,
/*sourceIndex*/ 0, MetadataPath(),
callback);
}
return *Fulfillments;
}
};
} // end anonymous namespace
/// Build the witness table.
void WitnessTableBuilder::build() {
visitProtocolDecl(Conformance.getProtocol());
TableSize = Table.size();
}
/// Return the address of a function which will return the type metadata
/// for an associated type.
llvm::Constant *WitnessTableBuilder::
getAssociatedTypeMetadataAccessFunction(AssociatedType requirement,
CanType associatedType) {
// If the associated type is non-dependent, we can use an ordinary
// metadata access function. We'll just end up passing extra arguments.
if (!associatedType->hasArchetype()) {
return getOrCreateTypeMetadataAccessFunction(IGM, associatedType);
}
// Otherwise, emit an access function.
llvm::Function *accessor =
IGM.getAddrOfAssociatedTypeMetadataAccessFunction(&Conformance,
requirement);
if (IGM.getOptions().OptimizeForSize)
accessor->addFnAttr(llvm::Attribute::NoInline);
IRGenFunction IGF(IGM, accessor);
if (IGM.DebugInfo)
IGM.DebugInfo->emitArtificialFunction(IGF, accessor);
Explosion parameters = IGF.collectParameters();
llvm::Value *self = parameters.claimNext();
setTypeMetadataName(IGM, self, ConcreteType);
Address destTable(parameters.claimNext(), IGM.getPointerAlignment());
setProtocolWitnessTableName(IGM, destTable.getAddress(), ConcreteType,
requirement.getSourceProtocol());
// If the associated type is directly fulfillable from the type,
// we don't need a cache entry.
// TODO: maybe we should have a cache entry anyway if the fulfillment
// is expensive.
if (auto fulfillment =
getFulfillmentMap().getTypeMetadata(associatedType)) {
llvm::Value *metadata =
fulfillment->Path.followFromTypeMetadata(IGF, ConcreteType, self,
/*cache*/ nullptr);
IGF.Builder.CreateRet(metadata);
return accessor;
}
// Bind local type data from the metadata argument.
IGF.bindLocalTypeDataFromTypeMetadata(ConcreteType, IsExact, self);
// For now, assume that an associated type is cheap enough to access
// that it doesn't need a new cache entry.
if (auto archetype = dyn_cast<ArchetypeType>(associatedType)) {
llvm::Value *metadata = emitArchetypeTypeMetadataRef(IGF, archetype);
IGF.Builder.CreateRet(metadata);
return accessor;
}
// Otherwise, we need a cache entry.
emitReturnOfCheckedLoadFromCache(IGF, destTable, self,
[&]() -> llvm::Value* {
return IGF.emitTypeMetadataRef(associatedType);
});
return accessor;
}
/// Return a function which will return a particular witness table
/// conformance. The function will be passed the metadata for which
/// the conformance is being requested; it may ignore this (perhaps
/// implicitly by taking no arguments).
static llvm::Constant *
getOrCreateWitnessTableAccessFunction(IRGenModule &IGM, CanType type,
ProtocolConformance *conformance) {
assert(!type->hasArchetype() && "cannot do this for dependent type");
// We always emit an access function for conformances, and in principle
// it is always possible to just use that here directly. However,
// if it's dependent, doing so won't allow us to cache the result.
// For the specific use case of an associated type conformance, we could
// use a cache in the witness table; but that wastes space per conformance
// and won't let us re-use the cache with other non-dependent uses in
// the module. Therefore, in this case, we use the address of the lazy-cache
// function.
//
// FIXME: we will need to pass additional parameters if the target
// conformance is conditional.
auto rootConformance = conformance->getRootNormalConformance();
if (rootConformance->getDeclContext()->isGenericContext()) {
return getWitnessTableLazyAccessFunction(IGM, rootConformance, type);
} else {
return IGM.getAddrOfWitnessTableAccessFunction(
conformance->getRootNormalConformance(),
NotForDefinition);
}
}
static void buildAssociatedTypeValueName(CanType depAssociatedType,
SmallString<128> &name) {
if (auto memberType = dyn_cast<DependentMemberType>(depAssociatedType)) {
buildAssociatedTypeValueName(memberType.getBase(), name);
name += '.';
name += memberType->getName().str();
} else {
assert(isa<GenericTypeParamType>(depAssociatedType)); // Self
}
}
llvm::Constant *WitnessTableBuilder::
getAssociatedTypeWitnessTableAccessFunction(AssociatedConformance requirement,
CanType associatedType,
ProtocolConformanceRef associatedConformance) {
if (!associatedType->hasArchetype()) {
assert(associatedConformance.isConcrete() &&
"no concrete conformance for non-dependent type");
return getOrCreateWitnessTableAccessFunction(IGM, associatedType,
associatedConformance.getConcrete());
}
// Otherwise, emit an access function.
llvm::Function *accessor =
IGM.getAddrOfAssociatedTypeWitnessTableAccessFunction(&Conformance,
requirement);
IRGenFunction IGF(IGM, accessor);
if (IGM.DebugInfo)
IGM.DebugInfo->emitArtificialFunction(IGF, accessor);
if (IGM.getOptions().OptimizeForSize)
accessor->addFnAttr(llvm::Attribute::NoInline);
Explosion parameters = IGF.collectParameters();
llvm::Value *associatedTypeMetadata = parameters.claimNext();
// We use a non-standard name for the type that states the association
// requirement rather than the concrete type.
if (IGM.EnableValueNames) {
SmallString<128> name;
name += ConcreteType->getString();
buildAssociatedTypeValueName(requirement.getAssociation(), name);
associatedTypeMetadata->setName(name);
}
llvm::Value *self = parameters.claimNext();
setTypeMetadataName(IGM, self, ConcreteType);
Address destTable(parameters.claimNext(), IGM.getPointerAlignment());
setProtocolWitnessTableName(IGM, destTable.getAddress(), ConcreteType,
Conformance.getProtocol());
ProtocolDecl *associatedProtocol = requirement.getAssociatedRequirement();
const ConformanceInfo *conformanceI = nullptr;
if (associatedConformance.isConcrete()) {
const ProtocolInfo &protocolI = IGM.getProtocolInfo(associatedProtocol);
conformanceI =
&protocolI.getConformance(IGM, associatedProtocol,
associatedConformance.getConcrete());
// If we can emit a constant table, do so.
// In principle, any time we can do this, we should try to re-use this
// function for other conformances. But that should typically already
// be covered by the !hasArchetype() check above.
if (auto constantTable =
conformanceI->tryGetConstantTable(IGM, associatedType)) {
IGF.Builder.CreateRet(constantTable);
return accessor;
}
}
// If the witness table is directly fulfillable from the type,
// we don't need a cache entry.
// TODO: maybe we should have a cache entry anyway if the fulfillment
// is expensive.
if (auto fulfillment =
getFulfillmentMap().getWitnessTable(associatedType,
associatedProtocol)) {
llvm::Value *wtable =
fulfillment->Path.followFromTypeMetadata(IGF, ConcreteType, self,
/*cache*/ nullptr);
IGF.Builder.CreateRet(wtable);
return accessor;
}
// Bind local type data from the metadata arguments.
IGF.bindLocalTypeDataFromTypeMetadata(associatedType, IsExact,
associatedTypeMetadata);
IGF.bindLocalTypeDataFromTypeMetadata(ConcreteType, IsExact, self);
// For now, assume that finding an abstract conformance is always
// fast enough that it's not worth caching.
// TODO: provide an API to find the best metadata path to the conformance
// and decide whether it's expensive enough to be worth caching.
if (!conformanceI) {
assert(associatedConformance.isAbstract());
auto wtable =
emitArchetypeWitnessTableRef(IGF, cast<ArchetypeType>(associatedType),
associatedConformance.getAbstract());
IGF.Builder.CreateRet(wtable);
return accessor;
}
// Otherwise, we need a cache entry.
emitReturnOfCheckedLoadFromCache(IGF, destTable, self,
[&]() -> llvm::Value* {
return conformanceI->getTable(IGF, associatedType, &associatedTypeMetadata);
});
return accessor;
}
void WitnessTableBuilder::
emitReturnOfCheckedLoadFromCache(IRGenFunction &IGF, Address destTable,
llvm::Value *selfMetadata,
llvm::function_ref<llvm::Value*()> body) {
// Allocate a new cache slot and drill down to it.
int cacheIndex = -1 - getNextCacheIndex();
Address cache = IGF.Builder.CreateConstArrayGEP(destTable, cacheIndex,
IGM.getPointerSize());
llvm::Type *expectedTy = IGF.CurFn->getReturnType();
cache = IGF.Builder.CreateBitCast(cache, expectedTy->getPointerTo());
// Load and check whether it was null.
auto cachedResult = IGF.Builder.CreateLoad(cache);
// TODO: When LLVM supports Consume, we should use it here.
if (IGF.IGM.IRGen.Opts.Sanitizers & SanitizerKind::Thread)
cachedResult->setOrdering(llvm::AtomicOrdering::Acquire);
auto cacheIsEmpty = IGF.Builder.CreateIsNull(cachedResult);
llvm::BasicBlock *fetchBB = IGF.createBasicBlock("fetch");
llvm::BasicBlock *contBB = IGF.createBasicBlock("cont");
llvm::BasicBlock *entryBB = IGF.Builder.GetInsertBlock();
IGF.Builder.CreateCondBr(cacheIsEmpty, fetchBB, contBB);
// Create a phi in the continuation block and use the loaded value if
// we branched directly here. Note that we arrange blocks so that we
// fall through into this.
IGF.Builder.emitBlock(contBB);
auto result = IGF.Builder.CreatePHI(expectedTy, 2);
result->addIncoming(cachedResult, entryBB);
IGF.Builder.CreateRet(result);
// In the fetch block, bind the archetypes and evaluate the body.
IGF.Builder.emitBlock(fetchBB);
llvm::Value *fetchedResult = body();
// Store the fetched result back to the cache.
// We need to transitively ensure that any stores initializing the result
// that are visible to us are visible to callers.
IGF.Builder.CreateStore(fetchedResult, cache)->setOrdering(
llvm::AtomicOrdering::Release);
auto fetchedResultBB = IGF.Builder.GetInsertBlock();
IGF.Builder.CreateBr(contBB);
result->addIncoming(fetchedResult, fetchedResultBB);
}
/// Emit the access function for this witness table.
void WitnessTableBuilder::buildAccessFunction(llvm::Constant *wtable) {
llvm::Function *fn =
IGM.getAddrOfWitnessTableAccessFunction(&Conformance, ForDefinition);
IRGenFunction IGF(IGM, fn);
if (IGM.DebugInfo)
IGM.DebugInfo->emitArtificialFunction(IGF, fn);
wtable = llvm::ConstantExpr::getBitCast(wtable, IGM.WitnessTablePtrTy);
// If specialization isn't required, just return immediately.
// TODO: allow dynamic specialization?
if (!RequiresSpecialization) {
IGF.Builder.CreateRet(wtable);
return;
}
// The target metadata is the first argument.
assert(isDependentConformance(IGF.IGM, &Conformance,
ResilienceExpansion::Maximal));
Explosion params = IGF.collectParameters();
llvm::Value *metadata;
if (Conformance.getDeclContext()->isGenericContext())
metadata = params.claimNext();
else
metadata = llvm::ConstantPointerNull::get(IGF.IGM.TypeMetadataPtrTy);
// Okay, we need a cache. Build the cache structure.
// struct GenericWitnessTable {
// /// The size of the witness table in words.
// uint16_t WitnessTableSizeInWords;
//
// /// The amount to copy from the pattern in words. The rest is zeroed.
// uint16_t WitnessTableSizeInWordsToCopy;
//
// /// The protocol.
// RelativeIndirectablePointer<ProtocolDescriptor> Protocol;
//
// /// The pattern.
// RelativeDirectPointer<WitnessTable> WitnessTable;
//
// /// The instantiation function, which is called after the template is copied.
// RelativeDirectPointer<void(WitnessTable *, const Metadata *)> Instantiator;
//
// void *PrivateData[swift::NumGenericMetadataPrivateDataWords];
// };
// First, create the global. We have to build this in two phases because
// it contains relative pointers.
auto cache = cast<llvm::GlobalVariable>(
IGM.getAddrOfGenericWitnessTableCache(&Conformance, ForDefinition));
// We need an instantiation function if the base conformance
// is non-dependent.
// TODO: the conformance might be conditional.
llvm::Constant *instantiationFn;
if (SpecializedBaseConformances.empty()) {
instantiationFn = nullptr;
} else {
instantiationFn = buildInstantiationFunction();
}
auto descriptorRef = IGM.getAddrOfLLVMVariableOrGOTEquivalent(
LinkEntity::forProtocolDescriptor(Conformance.getProtocol()),
IGM.getPointerAlignment(), IGM.ProtocolDescriptorStructTy);
// Fill in the global.
auto cacheTy = cast<llvm::StructType>(cache->getValueType());
ConstantInitBuilder cacheInitBuilder(IGM);
auto cacheData = cacheInitBuilder.beginStruct(cacheTy);
// WitnessTableSizeInWords
cacheData.addInt(IGM.Int16Ty, TableSize);
// WitnessTablePrivateSizeInWords
cacheData.addInt(IGM.Int16Ty, NextCacheIndex);
// RelativeIndirectablePointer<ProtocolDescriptor>
cacheData.addRelativeAddress(descriptorRef);
// RelativePointer<WitnessTable>
cacheData.addRelativeAddress(wtable);
// Instantiation function
cacheData.addRelativeAddressOrNull(instantiationFn);
// Private data
{
auto privateDataTy =
llvm::ArrayType::get(IGM.Int8PtrTy,
swift::NumGenericMetadataPrivateDataWords);
auto privateDataInit = llvm::Constant::getNullValue(privateDataTy);
auto privateData =
new llvm::GlobalVariable(IGM.Module, privateDataTy, /*constant*/ false,
llvm::GlobalVariable::InternalLinkage,
privateDataInit, "");
cacheData.addRelativeAddress(privateData);
}
cacheData.finishAndSetAsInitializer(cache);
cache->setConstant(true);
llvm::Value *instantiationArgs =
llvm::ConstantPointerNull::get(IGM.Int8PtrPtrTy);
auto call = IGF.Builder.CreateCall(IGM.getGetGenericWitnessTableFn(),
{ cache, metadata, instantiationArgs });
call->setDoesNotThrow();
IGF.Builder.CreateRet(call);
}
llvm::Constant *WitnessTableBuilder::buildInstantiationFunction() {
llvm::Function *fn =
IGM.getAddrOfGenericWitnessTableInstantiationFunction(&Conformance);
IRGenFunction IGF(IGM, fn);
if (IGM.DebugInfo)
IGM.DebugInfo->emitArtificialFunction(IGF, fn);
// Break out the parameters.
Explosion params = IGF.collectParameters();
Address wtable(params.claimNext(), IGM.getPointerAlignment());
llvm::Value *metadata = params.claimNext();
llvm::Value *instantiationArgs = params.claimNext();
(void) instantiationArgs; // unused for now
// TODO: store any required conditional-conformance information
// in the private data.
// Initialize all the specialized base conformances.
for (auto &base : SpecializedBaseConformances) {
// Ask the ConformanceInfo to emit the wtable.
// TODO: we may need to bind extra information in the IGF in order
// to make conditional conformances work.
llvm::Value *baseWTable =
base.second->getTable(IGF, ConcreteType, &metadata);
baseWTable = IGF.Builder.CreateBitCast(baseWTable, IGM.Int8PtrTy);
// Store that to the appropriate slot in the new witness table.
Address slot = IGF.Builder.CreateConstArrayGEP(wtable, base.first,
IGM.getPointerSize());
IGF.Builder.CreateStore(baseWTable, slot);
}
IGF.Builder.CreateRetVoid();
return fn;
}
/// Do a memoized witness-table layout for a protocol.
const ProtocolInfo &IRGenModule::getProtocolInfo(ProtocolDecl *protocol) {
return Types.getProtocolInfo(protocol);
}
/// Do a memoized witness-table layout for a protocol.
const ProtocolInfo &TypeConverter::getProtocolInfo(ProtocolDecl *protocol) {
// Check whether we've already translated this protocol.
auto it = Protocols.find(protocol);
if (it != Protocols.end()) return *it->second;
// If not, lay out the protocol's witness table, if it needs one.
WitnessTableLayout layout;
if (Lowering::TypeConverter::protocolRequiresWitnessTable(protocol))
layout.visitProtocolDecl(protocol);
// Create a ProtocolInfo object from the layout.
ProtocolInfo *info = ProtocolInfo::create(layout.getEntries());
info->NextConverted = FirstProtocol;
FirstProtocol = info;
// Memoize.
Protocols.insert(std::make_pair(protocol, info));
// Done.
return *info;
}
/// Allocate a new ProtocolInfo.
ProtocolInfo *ProtocolInfo::create(ArrayRef<WitnessTableEntry> table) {
size_t bufferSize = totalSizeToAlloc<WitnessTableEntry>(table.size());
void *buffer = ::operator new(bufferSize);
return new(buffer) ProtocolInfo(table);
}
ProtocolInfo::~ProtocolInfo() {
for (auto &conf : Conformances) {
delete conf.second;
}
}
/// Find the conformance information for a protocol.
const ConformanceInfo &
ProtocolInfo::getConformance(IRGenModule &IGM, ProtocolDecl *protocol,
const ProtocolConformance *conformance) const {
assert(conformance->getProtocol() == protocol &&
"conformance is for wrong protocol");
// Drill down to the root normal conformance.
auto normalConformance = conformance->getRootNormalConformance();
// Check whether we've already cached this.
auto it = Conformances.find(normalConformance);
if (it != Conformances.end()) return *it->second;
ConformanceInfo *info;
// If the conformance is dependent in any way, we need to unique it.
// TODO: maybe this should apply whenever it's out of the module?
// TODO: actually enable this
if (isDependentConformance(IGM, normalConformance,
ResilienceExpansion::Maximal)) {
info = new AccessorConformanceInfo(normalConformance);
// Otherwise, we can use a direct-referencing conformance.
} else {
info = new DirectConformanceInfo(normalConformance);
}
Conformances.insert({normalConformance, info});
return *info;
}
void IRGenModule::emitSILWitnessTable(SILWitnessTable *wt) {
// Don't emit a witness table if it is a declaration.
if (wt->isDeclaration())
return;
// Don't emit a witness table that is available externally.
// It can end up in having duplicate symbols for generated associated type
// metadata access functions.
// Also, it is not a big benefit for LLVM to emit such witness tables.
if (isAvailableExternally(wt->getLinkage()))
return;
// Build the witnesses.
ConstantInitBuilder builder(*this);
auto witnesses = builder.beginArray(Int8PtrTy);
WitnessTableBuilder wtableBuilder(*this, witnesses, wt);
wtableBuilder.build();
assert(getProtocolInfo(wt->getConformance()->getProtocol())
.getNumWitnesses() == witnesses.size()
&& "witness table size doesn't match ProtocolInfo");
// Produce the initializer value.
auto initializer = witnesses.finishAndCreateFuture();
auto global = cast<llvm::GlobalVariable>(
getAddrOfWitnessTable(wt->getConformance(), initializer));
global->setConstant(true);
global->setAlignment(getWitnessTableAlignment().getValue());
// FIXME: resilience; this should use the conformance's publishing scope.
wtableBuilder.buildAccessFunction(global);
// Behavior conformances can't be reflected.
if (wt->getConformance()->isBehaviorConformance())
return;
NormalProtocolConformance *Conf = wt->getConformance();
addProtocolConformanceRecord(Conf);
CanType conformingType = Conf->getType()->getCanonicalType();
if (!doesConformanceReferenceNominalTypeDescriptor(*this, conformingType)) {
// Trigger the lazy emission of the foreign type metadata.
NominalTypeDecl *Nominal = conformingType->getAnyNominal();
if (auto *clas = dyn_cast<ClassDecl>(Nominal)) {
if (clas->isForeign())
getAddrOfForeignTypeMetadataCandidate(conformingType);
} else if (isa<ClangModuleUnit>(Nominal->getModuleScopeContext())) {
getAddrOfForeignTypeMetadataCandidate(conformingType);
}
}
}
/// True if a function's signature in LLVM carries polymorphic parameters.
/// Generic functions and protocol witnesses carry polymorphic parameters.
bool irgen::hasPolymorphicParameters(CanSILFunctionType ty) {
switch (ty->getRepresentation()) {
case SILFunctionTypeRepresentation::Block:
// Should never be polymorphic.
assert(!ty->isPolymorphic() && "polymorphic C function?!");
return false;
case SILFunctionTypeRepresentation::Thick:
case SILFunctionTypeRepresentation::Thin:
case SILFunctionTypeRepresentation::Method:
case SILFunctionTypeRepresentation::Closure:
return ty->isPolymorphic();
case SILFunctionTypeRepresentation::CFunctionPointer:
case SILFunctionTypeRepresentation::ObjCMethod:
// May be polymorphic at the SIL level, but no type metadata is actually
// passed.
return false;
case SILFunctionTypeRepresentation::WitnessMethod:
// Always carries polymorphic parameters for the Self type.
return true;
}
llvm_unreachable("Not a valid SILFunctionTypeRepresentation.");
}
/// Emit a polymorphic parameters clause, binding all the metadata necessary.
void EmitPolymorphicParameters::emit(Explosion &in,
WitnessMetadata *witnessMetadata,
const GetParameterFn &getParameter) {
// Collect any early sources and bind local type data from them.
for (auto &source : getSources()) {
bindExtraSource(source, in, witnessMetadata);
}
auto getInContext = [&](CanType type) -> CanType {
return getTypeInContext(type);
};
// Collect any concrete type metadata that's been passed separately.
enumerateUnfulfilledRequirements([&](GenericRequirement requirement) {
auto value = in.claimNext();
bindGenericRequirement(IGF, requirement, value, getInContext);
});
// Bind all the fulfillments we can from the formal parameters.
bindParameterSources(getParameter);
}
llvm::Value *
MetadataPath::followFromTypeMetadata(IRGenFunction &IGF,
CanType sourceType,
llvm::Value *source,
Map<llvm::Value*> *cache) const {
LocalTypeDataKey key = {
sourceType,
LocalTypeDataKind::forTypeMetadata()
};
return follow(IGF, key, source, Path.begin(), Path.end(), cache);
}
llvm::Value *
MetadataPath::followFromWitnessTable(IRGenFunction &IGF,
CanType conformingType,
ProtocolConformanceRef conformance,
llvm::Value *source,
Map<llvm::Value*> *cache) const {
LocalTypeDataKey key = {
conformingType,
LocalTypeDataKind::forProtocolWitnessTable(conformance)
};
return follow(IGF, key, source, Path.begin(), Path.end(), cache);
}
/// Follow this metadata path.
///
/// \param sourceKey - A description of the source value. Not necessarily
/// an appropriate caching key.
/// \param cache - If given, this cache will be used to short-circuit
/// the lookup; otherwise, the global (but dominance-sensitive) cache
/// in the IRGenFunction will be used. This caching system is somewhat
/// more efficient than what IGF provides, but it's less general, and it
/// should probably be removed.
llvm::Value *MetadataPath::follow(IRGenFunction &IGF,
LocalTypeDataKey sourceKey,
llvm::Value *source,
iterator begin, iterator end,
Map<llvm::Value*> *cache) {
assert(source && "no source metadata value!");
// The invariant is that this iterator starts a path from source and
// that sourceKey is correctly describes it.
iterator i = begin;
// Before we begin emitting code to generate the actual path, try to find
// the latest point in the path that we've cached a value for.
// If the caller gave us a cache to use, check that. This lookup is very
// efficient and doesn't even require us to parse the prefix.
if (cache) {
auto result = cache->findPrefix(begin, end);
if (result.first) {
source = *result.first;
// If that was the end, there's no more work to do; don't bother
// adjusting the source key.
if (result.second == end)
return source;
// Advance the source key past the cached prefix.
while (i != result.second) {
Component component = *i++;
(void) followComponent(IGF, sourceKey, /*source*/ nullptr, component);
}
}
// Otherwise, make a pass over the path looking for available concrete
// entries in the IGF's local type data cache.
} else {
auto skipI = i;
LocalTypeDataKey skipKey = sourceKey;
while (skipI != end) {
Component component = *skipI++;
(void) followComponent(IGF, skipKey, /*source*/ nullptr, component);
// Check the cache for a concrete value. We don't want an abstract
// entry because, if one exists, we'll just end up here again
// recursively.
if (auto skipSource =
IGF.tryGetConcreteLocalTypeData(skipKey.getCachingKey())) {
// If we found one, advance the info for the source to the current
// point in the path, then continue the search.
sourceKey = skipKey;
source = skipSource;
i = skipI;
}
}
}
// Drill in on the actual source value.
while (i != end) {
auto component = *i++;
source = followComponent(IGF, sourceKey, source, component);
// If we have a cache, remember this in the cache at the next position.
if (cache) {
cache->insertNew(begin, i, source);
// Otherwise, insert it into the global cache.
} else {
IGF.setScopedLocalTypeData(sourceKey, source);
}
}
return source;
}
/// Call an associated-type witness table access function. Does not do
/// any caching or drill down to implied protocols.
static llvm::Value *
emitAssociatedTypeWitnessTableRef(IRGenFunction &IGF,
llvm::Value *parentMetadata,
llvm::Value *wtable,
WitnessIndex index,
llvm::Value *associatedTypeMetadata) {
llvm::Value *witness = emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
// Cast the witness to the appropriate function type.
auto sig = IGF.IGM.getAssociatedTypeWitnessTableAccessFunctionSignature();
auto witnessTy = sig.getType();
witness = IGF.Builder.CreateBitCast(witness, witnessTy->getPointerTo());
FunctionPointer witnessFnPtr(witness, sig);
// Call the accessor.
auto call = IGF.Builder.CreateCall(witnessFnPtr,
{ associatedTypeMetadata, parentMetadata, wtable });
return call;
}
/// Drill down on a single stage of component.
///
/// sourceType and sourceDecl will be adjusted to refer to the new
/// component. Source can be null, in which case this will be the only
/// thing done.
llvm::Value *MetadataPath::followComponent(IRGenFunction &IGF,
LocalTypeDataKey &sourceKey,
llvm::Value *source,
Component component) {
switch (component.getKind()) {
case Component::Kind::NominalTypeArgument:
case Component::Kind::NominalTypeArgumentConformance: {
assert(sourceKey.Kind == LocalTypeDataKind::forTypeMetadata());
auto generic = cast<BoundGenericType>(sourceKey.Type);
auto reqtIndex = component.getPrimaryIndex();
GenericTypeRequirements requirements(IGF.IGM, generic->getDecl());
auto &requirement = requirements.getRequirements()[reqtIndex];
auto module = IGF.getSwiftModule();
auto subs = generic->getContextSubstitutionMap(module,
generic->getDecl());
auto sub = requirement.TypeParameter.subst(subs)->getCanonicalType();
// In either case, we need to change the type.
sourceKey.Type = sub;
// If this is a type argument, we've fully updated sourceKey.
if (component.getKind() == Component::Kind::NominalTypeArgument) {
assert(!requirement.Protocol && "index mismatch!");
if (source) {
source = emitArgumentMetadataRef(IGF, generic->getDecl(),
requirements, reqtIndex, source);
setTypeMetadataName(IGF.IGM, source, sourceKey.Type);
}
// Otherwise, we need to switch sourceKey.Kind to the appropriate
// conformance kind.
} else {
assert(requirement.Protocol && "index mismatch!");
auto conformance = *subs.lookupConformance(requirement.TypeParameter,
requirement.Protocol);
assert(conformance.getRequirement() == requirement.Protocol);
sourceKey.Kind = LocalTypeDataKind::forProtocolWitnessTable(conformance);
if (source) {
auto protocol = conformance.getRequirement();
source = emitArgumentWitnessTableRef(IGF, generic->getDecl(),
requirements, reqtIndex, source);
setProtocolWitnessTableName(IGF.IGM, source, sourceKey.Type, protocol);
}
}
return source;
}
case Component::Kind::NominalParent: {
assert(sourceKey.Kind == LocalTypeDataKind::forTypeMetadata());
NominalTypeDecl *nominalDecl;
if (auto nominal = dyn_cast<NominalType>(sourceKey.Type)) {
nominalDecl = nominal->getDecl();
sourceKey.Type = nominal.getParent();
} else {
auto generic = cast<BoundGenericType>(sourceKey.Type);
nominalDecl = generic->getDecl();
sourceKey.Type = generic.getParent();
}
if (source) {
source = emitParentMetadataRef(IGF, nominalDecl, source);
setTypeMetadataName(IGF.IGM, source, sourceKey.Type);
}
return source;
}
case Component::Kind::OutOfLineBaseProtocol: {
auto conformance = sourceKey.Kind.getProtocolConformance();
auto protocol = conformance.getRequirement();
auto &pi = IGF.IGM.getProtocolInfo(protocol);
auto &entry = pi.getWitnessEntries()[component.getPrimaryIndex()];
assert(entry.isOutOfLineBase());
auto inheritedProtocol = entry.getBase();
sourceKey.Kind =
LocalTypeDataKind::forAbstractProtocolWitnessTable(inheritedProtocol);
if (conformance.isConcrete()) {
auto inheritedConformance =
conformance.getConcrete()->getInheritedConformance(inheritedProtocol);
if (inheritedConformance) {
sourceKey.Kind = LocalTypeDataKind::forConcreteProtocolWitnessTable(
inheritedConformance);
}
}
if (source) {
WitnessIndex index(component.getPrimaryIndex(), /*prefix*/ false);
source = emitInvariantLoadOfOpaqueWitness(IGF, source, index);
source = IGF.Builder.CreateBitCast(source, IGF.IGM.WitnessTablePtrTy);
setProtocolWitnessTableName(IGF.IGM, source, sourceKey.Type,
inheritedProtocol);
}
return source;
}
case Component::Kind::AssociatedConformance: {
auto sourceType = sourceKey.Type;
auto sourceConformance = sourceKey.Kind.getProtocolConformance();
auto sourceProtocol = sourceConformance.getRequirement();
auto &pi = IGF.IGM.getProtocolInfo(sourceProtocol);
auto &entry = pi.getWitnessEntries()[component.getPrimaryIndex()];
assert(entry.isAssociatedConformance());
auto association = entry.getAssociatedConformancePath();
auto associatedRequirement = entry.getAssociatedConformanceRequirement();
CanType associatedType =
sourceConformance.getAssociatedType(sourceType, association)
->getCanonicalType();
sourceKey.Type = associatedType;
auto associatedConformance =
sourceConformance.getAssociatedConformance(sourceType, association,
associatedRequirement);
sourceKey.Kind =
LocalTypeDataKind::forProtocolWitnessTable(associatedConformance);
assert((associatedConformance.isConcrete() ||
isa<ArchetypeType>(sourceKey.Type)) &&
"couldn't find concrete conformance for concrete type");
if (source) {
WitnessIndex index(component.getPrimaryIndex(), /*prefix*/ false);
auto sourceMetadata = IGF.emitTypeMetadataRef(sourceType);
auto associatedMetadata = IGF.emitTypeMetadataRef(sourceKey.Type);
source = emitAssociatedTypeWitnessTableRef(IGF, sourceMetadata, source,
index, associatedMetadata);
setProtocolWitnessTableName(IGF.IGM, source, sourceKey.Type,
associatedRequirement);
}
return source;
}
case Component::Kind::Impossible:
llvm_unreachable("following an impossible path!");
}
llvm_unreachable("bad metadata path component");
}
void MetadataPath::dump() const {
auto &out = llvm::errs();
print(out);
out << '\n';
}
void MetadataPath::print(llvm::raw_ostream &out) const {
for (auto i = Path.begin(), e = Path.end(); i != e; ++i) {
if (i != Path.begin()) out << ".";
auto component = *i;
switch (component.getKind()) {
case Component::Kind::OutOfLineBaseProtocol:
out << "out_of_line_base_protocol[" << component.getPrimaryIndex() << "]";
break;
case Component::Kind::AssociatedConformance:
out << "associated_conformance[" << component.getPrimaryIndex() << "]";
break;
case Component::Kind::NominalTypeArgument:
out << "nominal_type_argument[" << component.getPrimaryIndex() << "]";
break;
case Component::Kind::NominalTypeArgumentConformance:
out << "nominal_type_argument_conformance["
<< component.getPrimaryIndex() << "]";
break;
case Component::Kind::NominalParent:
out << "nominal_parent";
break;
case Component::Kind::Impossible:
out << "impossible";
break;
}
}
}
/// Collect any required metadata for a witness method from the end of
/// the given parameter list.
void irgen::collectTrailingWitnessMetadata(IRGenFunction &IGF,
SILFunction &fn,
Explosion &params,
WitnessMetadata &witnessMetadata) {
assert(fn.getLoweredFunctionType()->getRepresentation()
== SILFunctionTypeRepresentation::WitnessMethod);
llvm::Value *wtable = params.takeLast();
assert(wtable->getType() == IGF.IGM.WitnessTablePtrTy &&
"parameter signature mismatch: witness metadata didn't "
"end in witness table?");
wtable->setName("SelfWitnessTable");
witnessMetadata.SelfWitnessTable = wtable;
llvm::Value *metatype = params.takeLast();
assert(metatype->getType() == IGF.IGM.TypeMetadataPtrTy &&
"parameter signature mismatch: witness metadata didn't "
"end in metatype?");
metatype->setName("Self");
witnessMetadata.SelfMetadata = metatype;
}
/// Perform all the bindings necessary to emit the given declaration.
void irgen::emitPolymorphicParameters(IRGenFunction &IGF,
SILFunction &Fn,
Explosion &in,
WitnessMetadata *witnessMetadata,
const GetParameterFn &getParameter) {
EmitPolymorphicParameters(IGF, Fn).emit(in, witnessMetadata, getParameter);
}
Size NecessaryBindings::getBufferSize(IRGenModule &IGM) const {
// We need one pointer for each archetype or witness table.
return IGM.getPointerSize() * Requirements.size();
}
void NecessaryBindings::restore(IRGenFunction &IGF, Address buffer) const {
bindFromGenericRequirementsBuffer(IGF, Requirements.getArrayRef(), buffer,
[&](CanType type) { return type;});
}
void NecessaryBindings::save(IRGenFunction &IGF, Address buffer) const {
emitInitOfGenericRequirementsBuffer(IGF, Requirements.getArrayRef(), buffer,
[&](GenericRequirement requirement) -> llvm::Value* {
CanType type = requirement.TypeParameter;
if (auto protocol = requirement.Protocol) {
auto wtable =
emitArchetypeWitnessTableRef(IGF, cast<ArchetypeType>(type), protocol);
return wtable;
} else {
auto metadata = IGF.emitTypeMetadataRef(type);
return metadata;
}
});
}
void NecessaryBindings::addTypeMetadata(CanType type) {
// Bindings are only necessary at all if the type is dependent.
if (!type->hasArchetype()) return;
// Break down structural types so that we don't eagerly pass metadata
// for the structural type. Future considerations for this:
// - If we have the structural type lying around in some cheap fashion,
// maybe we *should* just pass it.
// - Passing a structural type should remove the need to pass its
// components separately.
if (auto tuple = dyn_cast<TupleType>(type)) {
for (auto elt : tuple.getElementTypes())
addTypeMetadata(elt);
return;
}
if (auto fn = dyn_cast<FunctionType>(type)) {
addTypeMetadata(fn.getInput());
addTypeMetadata(fn.getResult());
return;
}
if (auto inout = dyn_cast<InOutType>(type)) {
addTypeMetadata(inout.getObjectType());
return;
}
if (auto metatype = dyn_cast<MetatypeType>(type)) {
addTypeMetadata(metatype.getInstanceType());
return;
}
// Generic types are trickier, because they can require conformances.
// Otherwise, just record the need for this metadata.
Requirements.insert({type, nullptr});
}
void NecessaryBindings::addProtocolConformance(CanType type,
ProtocolConformanceRef conf) {
if (!conf.isAbstract()) return;
assert(isa<ArchetypeType>(type));
// TODO: pass something about the root conformance necessary to
// reconstruct this.
Requirements.insert({type, conf.getAbstract()});
}
llvm::Value *irgen::emitImpliedWitnessTableRef(IRGenFunction &IGF,
ArrayRef<ProtocolEntry> entries,
ProtocolDecl *target,
const GetWitnessTableFn &getWitnessTable) {
ProtocolPath path(IGF.IGM, entries, target);
auto wtable = getWitnessTable(path.getOriginIndex());
wtable = path.apply(IGF, wtable);
return wtable;
}
llvm::Value *irgen::emitWitnessTableRef(IRGenFunction &IGF,
CanType srcType,
ProtocolConformanceRef conformance) {
llvm::Value *srcMetadataCache = nullptr;
return emitWitnessTableRef(IGF, srcType, &srcMetadataCache, conformance);
}
/// Emit a protocol witness table for a conformance.
llvm::Value *irgen::emitWitnessTableRef(IRGenFunction &IGF,
CanType srcType,
llvm::Value **srcMetadataCache,
ProtocolConformanceRef conformance) {
auto proto = conformance.getRequirement();
assert(Lowering::TypeConverter::protocolRequiresWitnessTable(proto)
&& "protocol does not have witness tables?!");
// If we don't have concrete conformance information, the type must be
// an archetype and the conformance must be via one of the protocol
// requirements of the archetype. Look at what's locally bound.
if (conformance.isAbstract()) {
auto archetype = cast<ArchetypeType>(srcType);
return emitArchetypeWitnessTableRef(IGF, archetype, proto);
}
// All other source types should be concrete enough that we have
// conformance info for them. However, that conformance info might be
// more concrete than we're expecting.
// TODO: make a best effort to devirtualize, maybe?
auto concreteConformance = conformance.getConcrete();
assert(concreteConformance->getProtocol() == proto);
// Check immediately for an existing cache entry.
auto wtable = IGF.tryGetLocalTypeData(
srcType,
LocalTypeDataKind::forConcreteProtocolWitnessTable(concreteConformance));
if (wtable) return wtable;
auto &protoI = IGF.IGM.getProtocolInfo(proto);
auto &conformanceI =
protoI.getConformance(IGF.IGM, proto, concreteConformance);
wtable = conformanceI.getTable(IGF, srcType, srcMetadataCache);
IGF.setScopedLocalTypeData(
srcType,
LocalTypeDataKind::forConcreteProtocolWitnessTable(concreteConformance),
wtable);
return wtable;
}
/// Emit the witness table references required for the given type
/// substitution.
void irgen::emitWitnessTableRefs(IRGenFunction &IGF,
const Substitution &sub,
llvm::Value **metadataCache,
SmallVectorImpl<llvm::Value*> &out) {
auto conformances = sub.getConformances();
// We don't need to do anything if we have no protocols to conform to.
if (conformances.empty()) return;
// Look at the replacement type.
CanType replType = sub.getReplacement()->getCanonicalType();
for (auto &conformance : conformances) {
auto *proto = conformance.getRequirement();
if (!Lowering::TypeConverter::protocolRequiresWitnessTable(proto))
continue;
auto wtable = emitWitnessTableRef(IGF, replType, metadataCache,
conformance);
out.push_back(wtable);
}
}
static CanType getSubstSelfType(CanSILFunctionType origFnType,
const SubstitutionMap &subs) {
// Grab the apparent 'self' type. If there isn't a 'self' type,
// we're not going to try to access this anyway.
assert(!origFnType->getParameters().empty());
auto selfParam = origFnType->getParameters().back();
CanType inputType = selfParam.getType();
// If the parameter is a direct metatype parameter, this is a static method
// of the instance type. We can assume this because:
// - metatypes cannot directly conform to protocols
// - even if they could, they would conform as a value type 'self' and thus
// be passed indirectly as an @in or @inout parameter.
if (auto meta = dyn_cast<MetatypeType>(inputType)) {
if (!selfParam.isFormalIndirect())
inputType = meta.getInstanceType();
}
// Substitute the `self` type.
// FIXME: This has to be done as a formal AST type substitution rather than
// a SIL function type substitution, because some nominal types (viz
// Optional) have type lowering recursively applied to their type parameters.
// Substituting into the original lowered function type like this is still
// problematic if we ever allow methods or protocol conformances on structural
// types; we'd really need to separately record the formal Self type in the
// SIL function type to make that work, which could be managed by having a
// "substituted generic signature" concept.
if (!subs.empty()) {
inputType = inputType.subst(subs)->getCanonicalType();
}
return inputType;
}
namespace {
class EmitPolymorphicArguments : public PolymorphicConvention {
IRGenFunction &IGF;
public:
EmitPolymorphicArguments(IRGenFunction &IGF,
CanSILFunctionType polyFn)
: PolymorphicConvention(IGF.IGM, polyFn), IGF(IGF) {}
void emit(const SubstitutionMap &subs,
WitnessMetadata *witnessMetadata, Explosion &out);
private:
void emitEarlySources(const SubstitutionMap &subs, Explosion &out) {
for (auto &source : getSources()) {
switch (source.getKind()) {
// Already accounted for in the parameters.
case MetadataSource::Kind::ClassPointer:
case MetadataSource::Kind::Metadata:
continue;
// Needs a special argument.
case MetadataSource::Kind::GenericLValueMetadata: {
out.add(IGF.emitTypeMetadataRef(getSubstSelfType(FnType, subs)));
continue;
}
// Witness 'Self' arguments are added as a special case in
// EmitPolymorphicArguments::emit.
case MetadataSource::Kind::SelfMetadata:
case MetadataSource::Kind::SelfWitnessTable:
continue;
}
llvm_unreachable("bad source kind!");
}
}
};
} // end anonymous namespace
/// Pass all the arguments necessary for the given function.
void irgen::emitPolymorphicArguments(IRGenFunction &IGF,
CanSILFunctionType origFnType,
const SubstitutionMap &subs,
WitnessMetadata *witnessMetadata,
Explosion &out) {
EmitPolymorphicArguments(IGF, origFnType).emit(subs, witnessMetadata, out);
}
void EmitPolymorphicArguments::emit(const SubstitutionMap &subs,
WitnessMetadata *witnessMetadata,
Explosion &out) {
// Add all the early sources.
emitEarlySources(subs, out);
// For now, treat all archetypes independently.
enumerateUnfulfilledRequirements([&](GenericRequirement requirement) {
llvm::Value *requiredValue =
emitGenericRequirementFromSubstitutions(IGF, Generics, M,
requirement, subs);
out.add(requiredValue);
});
// For a witness call, add the Self argument metadata arguments last.
for (auto &source : getSources()) {
switch (source.getKind()) {
case MetadataSource::Kind::Metadata:
case MetadataSource::Kind::ClassPointer:
// Already accounted for in the arguments.
continue;
case MetadataSource::Kind::GenericLValueMetadata:
// Added in the early phase.
continue;
case MetadataSource::Kind::SelfMetadata: {
assert(witnessMetadata && "no metadata structure for witness method");
auto self = IGF.emitTypeMetadataRef(getSubstSelfType(FnType, subs));
witnessMetadata->SelfMetadata = self;
continue;
}
case MetadataSource::Kind::SelfWitnessTable: {
// Added later.
continue;
}
}
llvm_unreachable("bad source kind");
}
}
NecessaryBindings
NecessaryBindings::forFunctionInvocations(IRGenModule &IGM,
CanSILFunctionType origType,
const SubstitutionMap &subs) {
NecessaryBindings bindings;
// Bail out early if we don't have polymorphic parameters.
if (!hasPolymorphicParameters(origType))
return bindings;
// Figure out what we're actually required to pass:
PolymorphicConvention convention(IGM, origType);
// - unfulfilled requirements
convention.enumerateUnfulfilledRequirements(
[&](GenericRequirement requirement) {
CanType type = requirement.TypeParameter.subst(subs)->getCanonicalType();
if (requirement.Protocol) {
auto conf = *subs.lookupConformance(requirement.TypeParameter,
requirement.Protocol);
bindings.addProtocolConformance(type, conf);
} else {
bindings.addTypeMetadata(type);
}
});
// - extra sources
for (auto &source : convention.getSources()) {
switch (source.getKind()) {
case MetadataSource::Kind::Metadata:
case MetadataSource::Kind::ClassPointer:
continue;
case MetadataSource::Kind::GenericLValueMetadata:
bindings.addTypeMetadata(getSubstSelfType(origType, subs));
continue;
case MetadataSource::Kind::SelfMetadata:
bindings.addTypeMetadata(getSubstSelfType(origType, subs));
continue;
case MetadataSource::Kind::SelfWitnessTable:
// We'll just pass undef in cases like this.
continue;
}
llvm_unreachable("bad source kind");
}
return bindings;
}
/// The information we need to record in generic type metadata
/// is the information in the type's generic signature, minus the
/// information recoverable from the type's parent type. This is
/// simply the information that would be passed to a generic function
/// that takes the (thick) parent metatype as an argument.
GenericTypeRequirements::GenericTypeRequirements(IRGenModule &IGM,
NominalTypeDecl *typeDecl)
: TheDecl(typeDecl) {
// We only need to do something here if the declaration context is
// somehow generic.
auto ncGenerics = typeDecl->getGenericSignatureOfContext();
if (!ncGenerics) return;
// Construct a representative function type.
auto generics = ncGenerics->getCanonicalSignature();
CanSILFunctionType fnType = [&]() -> CanSILFunctionType {
CanType type = typeDecl->getDeclaredInterfaceType()->getCanonicalType();
if (auto nominal = dyn_cast<NominalType>(type)) {
ParentType = nominal.getParent();
} else {
ParentType = cast<BoundGenericType>(type).getParent();
}
// Ignore the existence of the parent type if it has no type parameters.
if (ParentType && !ParentType->hasTypeParameter())
ParentType = CanType();
SmallVector<SILParameterInfo, 1> params;
if (ParentType) {
auto parentMetatype =
CanMetatypeType::get(ParentType, MetatypeRepresentation::Thick);
params.push_back(SILParameterInfo(parentMetatype,
ParameterConvention::Direct_Unowned));
}
return SILFunctionType::get(generics, SILFunctionType::ExtInfo(),
/*callee*/ ParameterConvention::Direct_Unowned,
params, /*results*/ {}, /*error*/ None,
IGM.Context);
}();
// Figure out what we're actually still required to pass
PolymorphicConvention convention(IGM, fnType);
convention.enumerateUnfulfilledRequirements([&](GenericRequirement reqt) {
assert(generics->isCanonicalTypeInContext(reqt.TypeParameter,
*IGM.getSwiftModule()));
Requirements.push_back(reqt);
});
// We do not need to consider extra sources.
}
void
GenericTypeRequirements::enumerateFulfillments(IRGenModule &IGM,
const SubstitutionMap &subs,
FulfillmentCallback callback) {
if (empty()) return;
for (auto reqtIndex : indices(getRequirements())) {
auto &reqt = getRequirements()[reqtIndex];
CanType type = reqt.TypeParameter.subst(subs)->getCanonicalType();
if (reqt.Protocol) {
auto conformance = *subs.lookupConformance(reqt.TypeParameter,
reqt.Protocol);
callback(reqtIndex, type, conformance);
} else {
callback(reqtIndex, type, None);
}
}
}
void GenericTypeRequirements::emitInitOfBuffer(IRGenFunction &IGF,
const SubstitutionMap &subs,
Address buffer) {
if (Requirements.empty()) return;
auto generics =
TheDecl->getGenericSignatureOfContext()->getCanonicalSignature();
auto &module = *TheDecl->getParentModule();
emitInitOfGenericRequirementsBuffer(IGF, Requirements, buffer,
[&](GenericRequirement requirement) {
return emitGenericRequirementFromSubstitutions(IGF, generics, module,
requirement, subs);
});
}
void irgen::emitInitOfGenericRequirementsBuffer(IRGenFunction &IGF,
ArrayRef<GenericRequirement> requirements,
Address buffer,
EmitGenericRequirementFn emitRequirement) {
if (requirements.empty()) return;
// Cast the buffer to %type**.
buffer = IGF.Builder.CreateElementBitCast(buffer, IGF.IGM.TypeMetadataPtrTy);
for (auto index : indices(requirements)) {
// GEP to the appropriate slot.
Address slot = buffer;
if (index != 0) {
slot = IGF.Builder.CreateConstArrayGEP(slot, index,
IGF.IGM.getPointerSize());
}
llvm::Value *value = emitRequirement(requirements[index]);
if (requirements[index].Protocol) {
slot = IGF.Builder.CreateElementBitCast(slot, IGF.IGM.WitnessTablePtrTy);
}
IGF.Builder.CreateStore(value, slot);
}
}
llvm::Value *
irgen::emitGenericRequirementFromSubstitutions(IRGenFunction &IGF,
CanGenericSignature generics,
ModuleDecl &module,
GenericRequirement requirement,
const SubstitutionMap &subs) {
CanType depTy = requirement.TypeParameter;
CanType argType = depTy.subst(subs)->getCanonicalType();
if (!requirement.Protocol) {
auto argMetadata = IGF.emitTypeMetadataRef(argType);
return argMetadata;
}
auto proto = requirement.Protocol;
auto conformance = *subs.lookupConformance(depTy, proto);
assert(conformance.getRequirement() == proto);
llvm::Value *metadata = nullptr;
auto wtable = emitWitnessTableRef(IGF, argType, &metadata, conformance);
return wtable;
}
void GenericTypeRequirements::bindFromBuffer(IRGenFunction &IGF,
Address buffer,
GetTypeParameterInContextFn getInContext) {
bindFromGenericRequirementsBuffer(IGF, Requirements, buffer, getInContext);
}
void irgen::bindFromGenericRequirementsBuffer(IRGenFunction &IGF,
ArrayRef<GenericRequirement> requirements,
Address buffer,
GetTypeParameterInContextFn getInContext) {
if (requirements.empty()) return;
// Cast the buffer to %type**.
buffer = IGF.Builder.CreateElementBitCast(buffer, IGF.IGM.TypeMetadataPtrTy);
for (auto index : indices(requirements)) {
// GEP to the appropriate slot.
Address slot = buffer;
if (index != 0) {
slot = IGF.Builder.CreateConstArrayGEP(slot, index,
IGF.IGM.getPointerSize());
}
// Cast if necessary.
if (requirements[index].Protocol) {
slot = IGF.Builder.CreateElementBitCast(slot, IGF.IGM.WitnessTablePtrTy);
}
llvm::Value *value = IGF.Builder.CreateLoad(slot);
bindGenericRequirement(IGF, requirements[index], value, getInContext);
}
}
void irgen::bindGenericRequirement(IRGenFunction &IGF,
GenericRequirement requirement,
llvm::Value *value,
GetTypeParameterInContextFn getInContext) {
// Get the corresponding context type.
auto type = getInContext(requirement.TypeParameter);
if (auto proto = requirement.Protocol) {
assert(isa<ArchetypeType>(type));
assert(value->getType() == IGF.IGM.WitnessTablePtrTy);
setProtocolWitnessTableName(IGF.IGM, value, type, proto);
auto kind = LocalTypeDataKind::forAbstractProtocolWitnessTable(proto);
IGF.setUnscopedLocalTypeData(type, kind, value);
} else {
assert(value->getType() == IGF.IGM.TypeMetadataPtrTy);
setTypeMetadataName(IGF.IGM, value, type);
IGF.bindLocalTypeDataFromTypeMetadata(type, IsExact, value);
}
}
namespace {
/// A class for expanding a polymorphic signature.
class ExpandPolymorphicSignature : public PolymorphicConvention {
public:
ExpandPolymorphicSignature(IRGenModule &IGM, CanSILFunctionType fn)
: PolymorphicConvention(IGM, fn) {}
void expand(SmallVectorImpl<llvm::Type*> &out) {
for (auto &source : getSources())
addEarlySource(source, out);
enumerateUnfulfilledRequirements([&](GenericRequirement reqt) {
out.push_back(reqt.Protocol ? IGM.WitnessTablePtrTy
: IGM.TypeMetadataPtrTy);
});
}
private:
/// Add signature elements for the source metadata.
void addEarlySource(const MetadataSource &source,
SmallVectorImpl<llvm::Type*> &out) {
switch (source.getKind()) {
case MetadataSource::Kind::ClassPointer: return; // already accounted for
case MetadataSource::Kind::Metadata: return; // already accounted for
case MetadataSource::Kind::GenericLValueMetadata:
return out.push_back(IGM.TypeMetadataPtrTy);
case MetadataSource::Kind::SelfMetadata:
case MetadataSource::Kind::SelfWitnessTable:
return; // handled as a special case in expand()
}
llvm_unreachable("bad source kind");
}
};
} // end anonymous namespace
/// Given a generic signature, add the argument types required in order to call it.
void irgen::expandPolymorphicSignature(IRGenModule &IGM,
CanSILFunctionType polyFn,
SmallVectorImpl<llvm::Type*> &out) {
ExpandPolymorphicSignature(IGM, polyFn).expand(out);
}
void irgen::expandTrailingWitnessSignature(IRGenModule &IGM,
CanSILFunctionType polyFn,
SmallVectorImpl<llvm::Type*> &out) {
assert(polyFn->getRepresentation()
== SILFunctionTypeRepresentation::WitnessMethod);
assert(getTrailingWitnessSignatureLength(IGM, polyFn) == 2);
// A witness method always provides Self.
out.push_back(IGM.TypeMetadataPtrTy);
// A witness method always provides the witness table for Self.
out.push_back(IGM.WitnessTablePtrTy);
}
FunctionPointer
irgen::emitWitnessMethodValue(IRGenFunction &IGF,
CanType baseTy,
llvm::Value **baseMetadataCache,
SILDeclRef member,
ProtocolConformanceRef conformance,
CanSILFunctionType fnType) {
auto fn = cast<AbstractFunctionDecl>(member.getDecl());
auto fnProto = cast<ProtocolDecl>(fn->getDeclContext());
assert(conformance.getRequirement() == fnProto);
// Find the witness table.
llvm::Value *wtable = emitWitnessTableRef(IGF, baseTy, baseMetadataCache,
conformance);
// Find the witness we're interested in.
auto &fnProtoInfo = IGF.IGM.getProtocolInfo(conformance.getRequirement());
auto index = fnProtoInfo.getFunctionIndex(fn);
llvm::Value *witnessFnPtr =
emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
Signature signature = IGF.IGM.getSignature(fnType);
witnessFnPtr = IGF.Builder.CreateBitCast(witnessFnPtr,
signature.getType()->getPointerTo());
return FunctionPointer(witnessFnPtr, signature);
}
Signature IRGenModule::getAssociatedTypeMetadataAccessFunctionSignature() {
auto &fnType = AssociatedTypeMetadataAccessFunctionTy;
if (!fnType) {
fnType = llvm::FunctionType::get(TypeMetadataPtrTy,
{ TypeMetadataPtrTy,
WitnessTablePtrTy },
/*varargs*/ false);
}
auto attrs = llvm::AttributeList::get(getLLVMContext(),
llvm::AttributeList::FunctionIndex,
llvm::Attribute::NoUnwind);
return Signature(fnType, attrs, DefaultCC);
}
llvm::Value *irgen::emitAssociatedTypeMetadataRef(IRGenFunction &IGF,
llvm::Value *parentMetadata,
llvm::Value *wtable,
AssociatedType associatedType) {
auto &pi = IGF.IGM.getProtocolInfo(associatedType.getSourceProtocol());
auto index = pi.getAssociatedTypeIndex(associatedType);
llvm::Value *witness = emitInvariantLoadOfOpaqueWitness(IGF, wtable, index);
// Cast the witness to the appropriate function type.
auto sig = IGF.IGM.getAssociatedTypeMetadataAccessFunctionSignature();
auto witnessTy = sig.getType();
witness = IGF.Builder.CreateBitCast(witness, witnessTy->getPointerTo());
FunctionPointer witnessFnPtr(witness, sig);
// Call the accessor.
assert((!IGF.IGM.DebugInfo || IGF.Builder.getCurrentDebugLocation()) &&
"creating a function call without a debug location");
auto call = IGF.Builder.CreateCall(witnessFnPtr,
{ parentMetadata, wtable });
return call;
}
Signature
IRGenModule::getAssociatedTypeWitnessTableAccessFunctionSignature() {
auto &fnType = AssociatedTypeWitnessTableAccessFunctionTy;
if (!fnType) {
// The associated type metadata is passed first so that this function is
// CC-compatible with a conformance's witness table access function.
fnType = llvm::FunctionType::get(WitnessTablePtrTy,
{ TypeMetadataPtrTy,
TypeMetadataPtrTy,
WitnessTablePtrTy },
/*varargs*/ false);
}
auto attrs = llvm::AttributeList::get(getLLVMContext(),
llvm::AttributeList::FunctionIndex,
llvm::Attribute::NoUnwind);
return Signature(fnType, attrs, DefaultCC);
}