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Many, many, many types in the Swift compiler are intended to only be allocated in the ASTContext. We have previously implemented this by writing several `operator new` and `operator delete` implementations into these types. Factor those out into a new base class instead.
74 lines
2.5 KiB
C++
74 lines
2.5 KiB
C++
//===--- ASTAllocated.h - Allocation in the AST Context ---------*- 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 - 2020 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_AST_ASTALLOCATED_H
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#define SWIFT_AST_ASTALLOCATED_H
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#include <cassert>
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#include <cstddef>
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namespace swift {
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class ASTContext;
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/// The arena in which a particular ASTContext allocation will go.
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enum class AllocationArena {
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/// The permanent arena, which is tied to the lifetime of
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/// the ASTContext.
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///
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/// All global declarations and types need to be allocated into this arena.
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/// At present, everything that is not a type involving a type variable is
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/// allocated in this arena.
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Permanent,
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/// The constraint solver's temporary arena, which is tied to the
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/// lifetime of a particular instance of the constraint solver.
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///
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/// Any type involving a type variable is allocated in this arena.
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ConstraintSolver
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};
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namespace detail {
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void *allocateInASTContext(size_t bytes, const ASTContext &ctx,
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AllocationArena arena, unsigned alignment);
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}
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/// Types inheriting from this class are intended to be allocated in an
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/// \c ASTContext allocator; you cannot allocate them by using a normal \c new,
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/// and instead you must either provide an \c ASTContext or use a placement
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/// \c new.
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///
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/// The template parameter is a type with the desired alignment. It is usually,
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/// but not always, the type that is inheriting \c ASTAllocated.
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template <typename AlignTy>
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class ASTAllocated {
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public:
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// Make vanilla new/delete illegal.
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void *operator new(size_t Bytes) throw() = delete;
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void operator delete(void *Data) throw() = delete;
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// Only allow allocation using the allocator in ASTContext
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// or by doing a placement new.
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void *operator new(size_t bytes, const ASTContext &ctx,
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AllocationArena arena = AllocationArena::Permanent,
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unsigned alignment = alignof(AlignTy)) {
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return detail::allocateInASTContext(bytes, ctx, arena, alignment);
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}
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void *operator new(size_t Bytes, void *Mem) throw() {
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assert(Mem && "placement new into failed allocation");
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return Mem;
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}
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};
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}
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#endif
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