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ProtocolInfo.h
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ProtocolInfo.h
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//===--- ProtocolInfo.h - Abstract protocol witness layout ------*- C++ -*-===//
//
// 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 defines types for representing the abstract layout of a
// protocol.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_IRGEN_PROTOCOLINFO_H
#define SWIFT_IRGEN_PROTOCOLINFO_H
#include "swift/AST/Decl.h"
#include "swift/AST/ProtocolAssociations.h"
#include "swift/IRGen/ValueWitness.h"
#include "WitnessIndex.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Support/TrailingObjects.h"
namespace swift {
class CanType;
class ProtocolConformance;
namespace irgen {
class IRGenModule;
class TypeInfo;
/// A witness to a specific element of a protocol. Every
/// ProtocolTypeInfo stores one of these for each requirement
/// introduced by the protocol.
class WitnessTableEntry {
enum WitnessKind {
PlaceholderKind,
OutOfLineBaseKind,
MethodKind,
AssociatedTypeKind,
AssociatedConformanceKind
};
struct OutOfLineBaseWitness {
ProtocolDecl *Protocol;
};
struct MethodWitness {
SILDeclRef Witness;
};
struct AssociatedTypeWitness {
AssociatedTypeDecl *Association;
};
struct AssociatedConformanceWitness {
TypeBase *AssociatedType;
ProtocolDecl *Protocol;
};
WitnessKind Kind;
union {
OutOfLineBaseWitness OutOfLineBaseEntry;
MethodWitness MethodEntry;
AssociatedTypeWitness AssociatedTypeEntry;
AssociatedConformanceWitness AssociatedConformanceEntry;
};
WitnessTableEntry(WitnessKind Kind) : Kind(Kind) {}
public:
static WitnessTableEntry forPlaceholder() {
return WitnessTableEntry(WitnessKind::PlaceholderKind);
}
static WitnessTableEntry forOutOfLineBase(ProtocolDecl *proto) {
assert(proto != nullptr);
WitnessTableEntry entry(WitnessKind::OutOfLineBaseKind);
entry.OutOfLineBaseEntry = {proto};
return entry;
}
/// Is this a base-protocol entry?
bool isBase() const { return Kind == WitnessKind::OutOfLineBaseKind; }
bool matchesBase(ProtocolDecl *proto) const {
assert(proto != nullptr);
return isBase() && OutOfLineBaseEntry.Protocol == proto;
}
/// Given that this is a base-protocol entry, is the table
/// "out of line"?
bool isOutOfLineBase() const {
assert(isBase());
return true;
}
ProtocolDecl *getBase() const {
assert(isBase());
return OutOfLineBaseEntry.Protocol;
}
static WitnessTableEntry forFunction(SILDeclRef declRef) {
assert(!declRef.isNull());
WitnessTableEntry entry(WitnessKind::MethodKind);
entry.MethodEntry = {declRef};
return entry;
}
bool isFunction() const { return Kind == WitnessKind::MethodKind; }
bool matchesFunction(SILDeclRef declRef) const {
return isFunction() && MethodEntry.Witness == declRef;
}
SILDeclRef getFunction() const {
assert(isFunction());
return MethodEntry.Witness;
}
static WitnessTableEntry forAssociatedType(AssociatedType ty) {
WitnessTableEntry entry(WitnessKind::AssociatedTypeKind);
entry.AssociatedTypeEntry = {ty.getAssociation()};
return entry;
}
bool isAssociatedType() const {
return Kind == WitnessKind::AssociatedTypeKind;
}
bool matchesAssociatedType(AssociatedType assocType) const {
return isAssociatedType() &&
AssociatedTypeEntry.Association == assocType.getAssociation();
}
AssociatedTypeDecl *getAssociatedType() const {
assert(isAssociatedType());
return AssociatedTypeEntry.Association;
}
static WitnessTableEntry
forAssociatedConformance(AssociatedConformance conf) {
WitnessTableEntry entry(WitnessKind::AssociatedConformanceKind);
entry.AssociatedConformanceEntry = {conf.getAssociation().getPointer(),
conf.getAssociatedRequirement()};
return entry;
}
bool isAssociatedConformance() const {
return Kind == WitnessKind::AssociatedConformanceKind;
}
bool matchesAssociatedConformance(const AssociatedConformance &conf) const {
return isAssociatedConformance() &&
AssociatedConformanceEntry.AssociatedType ==
conf.getAssociation().getPointer() &&
AssociatedConformanceEntry.Protocol ==
conf.getAssociatedRequirement();
}
CanType getAssociatedConformancePath() const {
assert(isAssociatedConformance());
return CanType(AssociatedConformanceEntry.AssociatedType);
}
ProtocolDecl *getAssociatedConformanceRequirement() const {
assert(isAssociatedConformance());
return AssociatedConformanceEntry.Protocol;
}
friend bool operator==(WitnessTableEntry left, WitnessTableEntry right) {
if (left.Kind != right.Kind)
return false;
switch (left.Kind) {
case WitnessKind::PlaceholderKind:
return true;
case WitnessKind::OutOfLineBaseKind:
return left.OutOfLineBaseEntry.Protocol ==
right.OutOfLineBaseEntry.Protocol;
case WitnessKind::MethodKind:
return left.MethodEntry.Witness == right.MethodEntry.Witness;
case WitnessKind::AssociatedTypeKind:
return left.AssociatedTypeEntry.Association ==
right.AssociatedTypeEntry.Association;
case WitnessKind::AssociatedConformanceKind:
return left.AssociatedConformanceEntry.AssociatedType ==
right.AssociatedConformanceEntry.AssociatedType &&
left.AssociatedConformanceEntry.Protocol ==
right.AssociatedConformanceEntry.Protocol;
}
llvm_unreachable("invalid witness kind");
}
};
/// Describes the information available in a ProtocolInfo.
///
/// Each kind includes the information of the kinds before it.
enum class ProtocolInfoKind : uint8_t {
RequirementSignature,
Full
};
/// An abstract description of a protocol.
class ProtocolInfo final :
private llvm::TrailingObjects<ProtocolInfo, WitnessTableEntry> {
friend TrailingObjects;
friend class TypeConverter;
/// The number of table entries in this protocol layout.
unsigned NumTableEntries;
ProtocolInfoKind Kind;
ProtocolInfoKind getKind() const {
return Kind;
}
ProtocolInfo(ArrayRef<WitnessTableEntry> table, ProtocolInfoKind kind)
: NumTableEntries(table.size()), Kind(kind) {
std::uninitialized_copy(table.begin(), table.end(),
getTrailingObjects<WitnessTableEntry>());
}
static std::unique_ptr<ProtocolInfo> create(ArrayRef<WitnessTableEntry> table,
ProtocolInfoKind kind);
public:
/// The number of witness slots in a conformance to this protocol;
/// in other words, the size of the table in words.
unsigned getNumWitnesses() const {
assert(getKind() == ProtocolInfoKind::Full);
return NumTableEntries;
}
/// Return all of the entries in this protocol witness table.
///
/// The addresses of the entries in this array can be passed to
/// getBaseWitnessIndex/getNonBaseWitnessIndex, below.
ArrayRef<WitnessTableEntry> getWitnessEntries() const {
return {getTrailingObjects<WitnessTableEntry>(), NumTableEntries};
}
/// Given the address of a witness entry from this PI for a base protocol
/// conformance, return its witness index.
WitnessIndex getBaseWitnessIndex(const WitnessTableEntry *witness) const {
assert(witness && witness->isBase());
auto entries = getWitnessEntries();
assert(entries.begin() <= witness && witness < entries.end() &&
"argument witness entry does not belong to this ProtocolInfo");
if (witness->isOutOfLineBase()) {
return WitnessIndex(witness - entries.begin(), false);
} else {
return WitnessIndex(0, true);
}
}
/// Given the address of a witness entry from this PI for a non-base
/// witness, return its witness index.
WitnessIndex getNonBaseWitnessIndex(const WitnessTableEntry *witness) const {
assert(witness && !witness->isBase());
auto entries = getWitnessEntries();
assert(entries.begin() <= witness && witness < entries.end());
return WitnessIndex(witness - entries.begin(), false);
}
/// Return the witness index for the protocol conformance pointer
/// for the given base protocol requirement.
WitnessIndex getBaseIndex(ProtocolDecl *protocol) const {
for (auto &witness : getWitnessEntries()) {
if (witness.matchesBase(protocol))
return getBaseWitnessIndex(&witness);
}
llvm_unreachable("didn't find entry for base");
}
/// Return the witness index for the witness function for the given
/// function requirement.
WitnessIndex getFunctionIndex(SILDeclRef declRef) const {
assert(getKind() >= ProtocolInfoKind::Full);
for (auto &witness : getWitnessEntries()) {
if (witness.matchesFunction(declRef))
return getNonBaseWitnessIndex(&witness);
}
llvm_unreachable("didn't find entry for function");
}
/// Return the witness index for the type metadata access function
/// for the given associated type.
WitnessIndex getAssociatedTypeIndex(IRGenModule &IGM,
AssociatedType assocType) const;
/// Return the witness index for the protocol witness table access
/// function for the given associated protocol conformance.
WitnessIndex
getAssociatedConformanceIndex(const AssociatedConformance &conf) const {
for (auto &witness : getWitnessEntries()) {
if (witness.matchesAssociatedConformance(conf))
return getNonBaseWitnessIndex(&witness);
}
llvm_unreachable("didn't find entry for associated conformance");
}
};
/// Detail about how an object conforms to a protocol.
class ConformanceInfo {
virtual void anchor();
public:
virtual ~ConformanceInfo() = default;
virtual llvm::Value *getTable(IRGenFunction &IGF,
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;
};
} // end namespace irgen
} // end namespace swift
#endif