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The dumper method dumps: 1. The container's metadata pointer. 2. A pointer to the container's value. 3. Whether or not said value is stored inline in the container. This provides a general overview that can be used even when working with SIL code in the debugger by grabbing a pointer to swift Anys and then calling the c++ any method upon them. The verifier is intended to be used in conjunction with ASAN for maximum effect to catch use-after-frees of existential boxes. While implementing this I refactored some code from ExistentialTypeMetadata into methods on OpaqueExistentialContainer. ExistentialTypeMetadata just calls these methods now instead of implementing the code inline.
103 lines
3.6 KiB
C++
103 lines
3.6 KiB
C++
//===--- ExistentialContainer.h -------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_RUNTIME_EXISTENTIALCONTAINER_H
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#define SWIFT_RUNTIME_EXISTENTIALCONTAINER_H
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#include "swift/Runtime/Metadata.h"
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namespace swift {
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/// The basic layout of an opaque (non-class-bounded) existential type.
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template <typename Runtime>
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struct TargetOpaqueExistentialContainer {
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ValueBuffer Buffer;
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const TargetMetadata<Runtime> *Type;
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// const void *WitnessTables[];
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const TargetWitnessTable<Runtime> **getWitnessTables() {
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return reinterpret_cast<const TargetWitnessTable<Runtime> **>(this + 1);
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}
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const TargetWitnessTable<Runtime> *const *getWitnessTables() const {
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return reinterpret_cast<const TargetWitnessTable<Runtime> *const *>(this +
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1);
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}
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void copyTypeInto(swift::TargetOpaqueExistentialContainer<Runtime> *dest,
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unsigned numTables) const {
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dest->Type = Type;
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for (unsigned i = 0; i != numTables; ++i)
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dest->getWitnessTables()[i] = getWitnessTables()[i];
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}
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/// Return true if this opaque existential container contains a value that is
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/// stored inline in the container. Returns false if the value is stored out
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/// of line.
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bool isValueInline() const;
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/// Project out a pointer to the value stored in the container.
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///
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/// *NOTE* If the container contains the value inline, then this will return a
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/// pointer inside the container itself. Otherwise, it will return a pointer
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/// to out of line memory.
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const OpaqueValue *projectValue() const;
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/// Cleans up an existential container instance whose value is uninitialized.
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void deinit();
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#ifndef NDEBUG
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/// Verify invariants of the container.
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///
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/// We verify that:
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///
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/// 1. The container itself is in live memory.
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/// 2. If we have an out of line value, that the value is in live memory.
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///
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/// The intention is that this is used in combination with ASAN or Guard
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/// Malloc to catch use-after-frees.
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void verify() const LLVM_ATTRIBUTE_USED;
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/// Dump information about this specific box and its contents. Only intended
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/// for use in the debugger.
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LLVM_ATTRIBUTE_DEPRECATED(void dump() const LLVM_ATTRIBUTE_USED,
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"Only meant for use in the debugger");
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#endif
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};
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using OpaqueExistentialContainer = TargetOpaqueExistentialContainer<InProcess>;
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/// The basic layout of a class-bounded existential type.
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template <typename ContainedValue>
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struct ClassExistentialContainerImpl {
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ContainedValue Value;
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const WitnessTable **getWitnessTables() {
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return reinterpret_cast<const WitnessTable **>(this + 1);
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}
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const WitnessTable *const *getWitnessTables() const {
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return reinterpret_cast<const WitnessTable *const *>(this + 1);
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}
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void copyTypeInto(ClassExistentialContainerImpl *dest,
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unsigned numTables) const {
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for (unsigned i = 0; i != numTables; ++i)
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dest->getWitnessTables()[i] = getWitnessTables()[i];
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}
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};
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using ClassExistentialContainer = ClassExistentialContainerImpl<void *>;
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using WeakClassExistentialContainer =
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ClassExistentialContainerImpl<WeakReference>;
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} // end swift namespace
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#endif
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