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87ec607233
The YAML format is the same one produced by the -dump-type-info frontend mode. For now this is only enabled if the -read-type-info-path frontend flag is specified. Progress on <rdar://problem/17528739>.
106 lines
3.7 KiB
C++
106 lines
3.7 KiB
C++
//===--- LegacyLayoutFormat.h - YAML format for legacy layout ---*- C++ -*-===//
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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 - 2017 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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//
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// This file defines the YAML format for the backward deployment type layout
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// dump.
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//
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// When a class with @objc ancestry is statically visible to Clang code, older
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// Objective-C runtimes do not give us the opportunity to run any code to
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// initialize the class metadata when it is realized.
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//
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// This creates a problem if the class has resiliently-sized fields. Since the
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// standard library and overlays are now built with resilience enabled, this
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// creates a backward-compatibility issue where such class definitions would now
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// require singleton metadata initialization instead of idempotent metadata
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// initialization, and singleton metadata initializaiton precludes the class
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// from being statically visible to Clang.
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//
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// To support this case, we emit fixed metadata for any such class, and in place
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// of each resilient field type, we use previously-emitted fixed type info.
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//
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// This fixed type info must match the Swift standard library and overlays used
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// for backward deployment, since on older Objective-C runtimes these layouts
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// will be used at runtime.
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//
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// However, since these types are resilient, their layouts might change in the
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// future. Newer Objective-C runtimes will expose a hook allowing the Swift
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// runtime to re-compute the class layout when the class is realized.
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//
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// Note that except for metadata emission, field accesses and instance
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// allocation for such classes must proceed as if they use singleton metadata
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// initialization, loading the field offsets from global variables and loading
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// the size and alignment dynamically from metadata when allocating.
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//
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// Also, any Swift-side accesses of the metadata must call the metadata accessor
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// function, allowing the Swift runtime to re-initialize the layout if
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// necessary.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_IRGEN_LEGACY_LAYOUT_FORMAT_H
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#define SWIFT_IRGEN_LEGACY_LAYOUT_FORMAT_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/YAMLTraits.h"
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#include "llvm/Support/raw_ostream.h"
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namespace swift {
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namespace irgen {
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struct YAMLTypeInfoNode {
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std::string Name;
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uint64_t Size;
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uint64_t Alignment;
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uint64_t NumExtraInhabitants;
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bool operator<(const YAMLTypeInfoNode &other) const {
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return Name < other.Name;
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}
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};
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struct YAMLModuleNode {
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StringRef Name;
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std::vector<YAMLTypeInfoNode> Decls;
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};
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} // namespace irgen
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} // namespace swift
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namespace llvm {
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namespace yaml {
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template <> struct MappingTraits<swift::irgen::YAMLTypeInfoNode> {
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static void mapping(IO &io, swift::irgen::YAMLTypeInfoNode &node) {
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io.mapRequired("Name", node.Name);
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io.mapRequired("Size", node.Size);
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io.mapRequired("Alignment", node.Alignment);
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io.mapRequired("ExtraInhabitants", node.NumExtraInhabitants);
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}
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};
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template <> struct MappingTraits<swift::irgen::YAMLModuleNode> {
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static void mapping(IO &io, swift::irgen::YAMLModuleNode &node) {
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io.mapRequired("Name", node.Name);
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io.mapOptional("Decls", node.Decls);
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}
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};
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} // namespace yaml
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} // namespace llvm
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LLVM_YAML_IS_SEQUENCE_VECTOR(swift::irgen::YAMLTypeInfoNode);
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LLVM_YAML_IS_DOCUMENT_LIST_VECTOR(swift::irgen::YAMLModuleNode);
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#endif // SWIFT_IRGEN_LEGACY_LAYOUT_FORMAT_H
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